Final Year Design ProjectA Plant Design Report on The Production of Biodiesel from 30 TPD Waste Cooking Oil Project Supervisor Dr. Maria Mustafa Muhammad Abubakar DDP-SP13-BEC-043 Muhammad Hashim Khan DDP-SP13-BEC-053 Shahzaib Younas DDP-SP13-BEC-085 Zohaib Uzair DDP-SP13-BEC-101 Department of Chemical Engineering Biodiesel Production Using Waste Cooking Oils Muhammad Abubakar DDP-SP13-BEC-043 Muhammad Hashim Khan DDP-SP13-BEC-053 Shahzaib Younas DDP-SP13-BEC-085 Zohaib Uzair DDP-SP13-BEC-101 A report submitted in partial fulfilment of the requirements for the award of the degree of Bachelor of Science in Chemical Engineering Department of Chemical Engineering I declare that this I declare that this thesis entitled “title of the thesis” is the result of my own research except as cited in the references. The thesis has not been accepted for any degree and is not concurrently submitted in candidature of any other degree. Signature: .................................................... Name: .................................................... Date: .................................................... iii ACKNOWLEDGEMENT We would like to express our sincere gratitude to all those who have assisted and guided us during our project study. First of all, we would like to thank our supervisor, Doctor Maria Mustafa for her guidance and support during the course of this project. She provided us with invaluable supervision from the beginning until the completion of our project. We would also like to thank the lab engineers and technicians, who have assisted us through this project. They have catered to our equipment needs during the project. I would also like to express my most sincere feelings of gratitude towards Doctor Fahad who helped the group in designing the reactors. Last but not the least, we also express our honest gratitude to all our colleagues, friends and beloved family for their endless love and support throughout the project. iv ABSTRACT Biodiesel is a type of bio fuel which can be derived from new or used vegetable oils and animal fats. It is a biodegradable, renewable energy and clean burning alternative. Due to the price hike in conventional fuels in the last decade studies have been made to introduce biodiesel as a feasible alternative to conventional diesel. Diesel Engines can also be made to run on cooking oils as such but due to their high viscosity and carbon content they cause some undesirable problems in diesel engines. To make these cooking oils more suitable for diesel engine consumption we turn them into esters via the process of transesterificatio n. This reduces their molecular weight to one thirds and lowers their viscosity, essentially making them more suitable as engine fuels. But even then, it is mostly recommended that this biofuel be used with commercial diesel as a mixture i.e. 20% biodiesel 80% diesel. The process we’ve worked upon is the base-catalysed trans-esterification method, which will be used to produce biodiesel from waste oils. This process is initially assisted by acid catalysed esterification for the reduction of free fatty acids to acceptable limits. To induce simplicity and understanding we have assumed waste soya bean oil to be our raw material. The core objective of this paper would to design and develop a profitable biodiesel production plant. Relying on the conventional mass and energy balances we can estimate the real-life construction of this plant. v List of Figures Figure 3.1.1-Process Flow Diagram ................................................................................... 9 Figure 4.1.1 Material Balance (Filter) .............................................................................. 18 Figure 4.2.1 Material Balance (R-1) ................................................................................. 19 Figure 4.3.1 Material Balance (R-2) ................................................................................. 21 Figure 4.4.1 Material Balance (C-1) ................................................................................. 22 Figure 4.5.1 Material Balance (C-2) ................................................................................. 24 Figure 4.6.1 Material Balance (MT-1).............................................................................. 26 Figure 4.7.1 Material Balance (C-3) ................................................................................. 27 Figure 4.8.1 Material Balance (FT) .................................................................................. 28 Figure 4.9.1 Material Balance (MT-2).............................................................................. 29 Figure 4.10.1 Material Balance (C-4) ............................................................................... 31 Figure 4.11.1 Material Balance (MT-3)............................................................................ 32 Figure 4.12.1 Material Balance (D-1) ............................................................................... 33 Figure 4.13.1 Material Balance (D-2) ............................................................................... 34 Figure 5.2.1 Steam Properties ........................................................................................... 36 Figure 5.3.1 Energy Balance (HE-1) ................................................................................ 37 Figure 5.4.1 Energy Balance (HE-2) ................................................................................ 38 Figure 5.5.1 Energy Balance (HE-3) ................................................................................ 39 Figure 5.5.1 Energy Balance (HE-4) ................................................................................ 40 Figure 5.7.1 Energy Balance (R-1) ................................................................................... 41 Figure 5.8.1 Energy Balance (R-2) ................................................................................... 43 Figure 5.9.1 Energy Balance (FT) .................................................................................... 44 Figure 5.10.1 Energy Balance (Condenser) ...................................................................... 45 Figure 5.11.1 Energy Balance (HE-5) .............................................................................. 46 Figure 5.12.1 Energy Balance (DC-1) .............................................................................. 48 Figure 5.13.1 Energy Balance (DC-2) .............................................................................. 50 Figure 6.3.1 Flash Tank .................................................................................................... 68 Figure 7.2.1 Reactor Control ............................................................................................ 99 Figure 7.3.1 Heat Exchanger Control ............................................................................. 100 vi Figure 7.4.1 Distillation Column Control ....................................................................... 101 vii List of Tables Table 4.1-1 Material Balance (Filter) ............................................................................... 18 Table 4.2-1 Reactor1 Parameters ...................................................................................... 19 Table 4.2-2 Material Balance (R-1) .................................................................................. 19 Table 4.3-1 Reactor2 Parameters ...................................................................................... 20 Table 4.3-2 Material Balance (R-2) .................................................................................. 20 Table 4.4-1 Centrifuge1 Parameters ................................................................................. 21 Table 4.4-2 Material Balance (C-1) .................................................................................. 22 Table 4.5-1 Centrifuge1 Parameters ................................................................................. 23 Table 4.5-2 Material Balance (C-2) .................................................................................. 24 Table 4.6-1 Mixing Tank Parameters ............................................................................... 24 Table 4.6-2 Material Balance (MT-1)............................................................................... 25 Table 4.7-1 Centrifuge3 Parameters ................................................................................. 26 Table 4.7-2 Material Balance (C-3) .................................................................................. 27 Table 4.8-1 Material Balance (FT) ................................................................................... 28 Table 4.9-1 Material Balance (MT-2)............................................................................... 29 Table 4.10-1 Centrifuge4 Parameters ............................................................................... 30 Table 4.10-2 Material Balance (C-4) ................................................................................ 30 Table 4.11-1 Material Balance (MT-3)............................................................................. 32 Table 4.12-1 Material Balance (D-1) ................................................................................ 32 Table 4.13-1 Material Balance (D-2) ................................................................................ 33 Table 5.3-1 Energy Balance (HE-1) ................................................................................. 37 Table 5.4-1 Energy Balance (HE-2) ................................................................................. 38 Table 5.5-1 Energy Balance (HE-3) ................................................................................. 39 Table 5.6-1 Energy Balance (HE-4) ................................................................................. 40 Table 5.7-1 Reactor1 Parameters ...................................................................................... 41 Table 5.7-2 Energy Balance (R-1) .................................................................................... 42 Table 5.8-1 Reactor2 Parameters ...................................................................................... 43 Table 5.8-2 Energy Balance (R-2) .................................................................................... 44 Table 5.9-1 Energy Balance (FT) ..................................................................................... 45 viii Table 5.10-1 Energy Balance (Condenser) ....................................................................... 46 Table 5.11-1 Energy Balance (HE-5) ............................................................................... 47 Table 5.12-1 Energy Balance for Boiler of DC-1 ............................................................. 49 Table 5.12-2 Energy Balance for Condenser of DC-1...................................................... 49 Table 5.13-1 Energy Balance for Boiler of DC-2 ............................................................. 51 Table 5.13-2 Energy Balance for Condenser of DC-2...................................................... 51 ix Table of Contents Chapter 1 INTRODUCTION ___________________________________________ 1 1.1 Biofuels _______________________________________________________ 1 1.2 What Is Biodiesel? _______________________________________________ 1 1.3 Advantages & Disadvantages_______________________________________ 2 1.4 What Are Oils? __________________________________________________ 3 1.5 Vegetable Oils as Fuels (Properties) _________________________________ 3 Chapter 2 LITERATURE REVIEW ______________________________________ 4 2.1 Process Selection ________________________________________________ 4 2.2 Transesterification _______________________________________________ 4 2.3 Pre-treatment ___________________________________________________ 4 2.4 Standard Practices & Their Flowsheets _______________________________ 5 2.5 Raw Materials __________________________________________________ 6 2.5.1 Choice of Oil ________________________________________________ 6 2.5.2 Catalyst ____________________________________________________ 6 2.5.3 Alcohol ____________________________________________________ 7 2.5.4 Factors Affecting the Transesterification Process ___________________ 7 Chapter 3 PROCESS DESCRIPTION & FLOWSHEET ______________________ 9 3.1 Process Flow Diagram & Description ________________________________ 9 3.1.1 Filter ______________________________________________________ 9 3.1.2 Heat Exchanger (HE-1)_______________________________________ 10 3.1.3 Pre-Treatment Reactor _______________________________________ 10 3.1.4 Heat Exchanger (HE-2)_______________________________________ 10 3.1.5 Heat Exchanger (HE-3)_______________________________________ 10 x 3.1.6 Pre-treatment Heat Exchanger (PT_HE-1) ________________________ 10 3.1.7 Pre-treatment Heat Exchanger (PT_HE-2) ________________________ 10 3.1.8 Pre-treatment Distillation (P_D) ________________________________ 11 3.1.9 Reactor1 (R1) ______________________________________________ 11 3.1.10 Heat Exchanger (HE-4)_______________________________________ 11 3.1.11 Reactor2 (R2) ______________________________________________ 11 3.1.12 Centrifuge1 (C1) ____________________________________________ 11 3.1.13 Centrifuge2 (C2) ____________________________________________ 11 3.1.14 Mixing Tank1 (Wash Tank) ___________________________________ 12 3.1.15 Centrifuge 3 (C3) ___________________________________________ 12 3.1.16 Flash Tank (FT1) ___________________________________________ 12 3.1.17 Mixing Tank2 (MT2) ________________________________________ 12 3.1.18 Centrifuge4 (C4) ____________________________________________ 12 3.1.19 Mixing Tank3 (MT3) ________________________________________ 12 3.1.20 Heat Exchanger (HE-5)_______________________________________ 12 3.1.21 Distillation Column 1 (D1) ____________________________________ 12 3.1.22 Distillation Column 2 (D2) ____________________________________ 13 3.2 Products ______________________________________________________ 13 3.1.23 Glycerine __________________________________________________ 13 3.3 Testing of Used Oil _____________________________________________ 13 Chapter 4 MATERIAL BALANCE _____________________________________ 16 4.1 Survey for Waste Cooking Oil Collection ______________________________ 16 3.1.24 Capacity Selection___________________________________________ 17 4.2 Material Balance (Filter) _________________________________________ 17 4.3 Material Balance Reactor1 (R-1) ___________________________________ 18 xi 4.4 Material Balance (Reactor 2) ______________________________________ 20 4.5 Material Balance (Centrifuge1) ____________________________________ 21 4.6 Material Balance (Centrifuge 2)____________________________________ 22 4.7 Material Balance (Mixing Tank 1) __________________________________ 24 4.8 Material Balance (Centrifuge 3)____________________________________ 26 4.9 Material Balance (Flash Tank) _____________________________________ 27 4.10 Material Balance (Mixing Tank 2) ________________________________ 28 4.11 Material Balance (Centrifuge 4) __________________________________ 29 4.12 Material Balance (Mixing Tank 3) ________________________________ 31 4.13 Material Balance (Distillation Column 1) __________________________ 32 4.14 Material Balance (Distillation Column 2) __________________________ 33 Chapter 5 ENERGY BALANCE _______________________________________ 35 5.1 Cp Calculation _________________________________________________ 35 5.2 Equipment ____________________________________________________ 36 5.3 Energy Balance Heater (HE-1) ____________________________________ 37 5.4 Energy Balance Heater (HE-2) ____________________________________ 38 5.5 Energy Balance Heater (HE-3) ____________________________________ 39 5.6 Energy Balance Heater (HE-4) ____________________________________ 40 5.7 Energy Balance (Reactor 1) _______________________________________ 41 5.8 Energy Balance (Reactor 2) _______________________________________ 42 5.9 Energy Balance (Flash Tank) ______________________________________ 44 5.10 Energy Balance Condenser ______________________________________ 45 5.11 Energy Balance Heater (HE-5) ___________________________________ 46 5.12 Energy Balance Distillation Column (DC-1) ________________________ 48 5.13 Energy Balance Distillation Column (DC-2) ________________________ 50 xii Chapter 6 EQUIPMENT DESIGN ______________________________________ 52 6.1 Reactor Design _________________________________________________ 52 6.1.1 Reactor Selection ___________________________________________ 54 6.1.2 Rate Constants______________________________________________ 55 6.1.3 Reactor Impeller ____________________________________________ 57 6.1.4 Specifications Sheet _________________________________________ 57 6.1.5 Pressure Drop ______________________________________________ 58 6.2 Heat Exchanger Design __________________________________________ 58 6.2.1 Types with respect to Structure_________________________________ 58 6.2.2 Principal Parts ______________________________________________ 59 6.2.3 Working Principle of Double Pipe Heat Exchanger _________________ 60 6.2.4 HEAT TRANSFER MODES __________________________________ 60 6.2.5 Types of Double Pipe Heat Exchanger ___________________________ 60 6.2.6 Double Pipe Heat Exchangers__________________________________ 60 6.2.7 Operation of Double Pipe Heat Exchanger________________________ 61 6.2.8 Heat Exchanger Design_______________________________________ 62 6.2.9 Mechanical Design __________________________________________ 67 6.3 Flash Tank ____________________________________________________ 68 6.4 Distillation Column Design (D-1) __________________________________ 70 6.4.1 Choice between Plate and Packed Column________________________ 70 6.4.2 Choice of Plate Type_________________________________________ 71 6.4.3 Design Steps for A Distillation Column __________________________ 71 6.4.4 From which the theoretical no. of stages to be 7 ___________________ 75 6.4.5 Feed plate location __________________________________________ 75 6.4.6 Column Diameter ___________________________________________ 75 xiii 6.5 DISTILLATION COLUMN DESIGN ______________________________ 79 6.5.1 Top Operating Line __________________________________________ 81 6.5.2 Bottom Operating Line _______________________________________ 82 6.5.3 Ideal no of trays is 8 _________________________________________ 83 6.5.4 Efficiency And Total Number Of Real Stages _____________________ 83 6.5.5 Superficial Vapor Velocity ____________________________________ 85 6.5.6 Net Area Required __________________________________________ 85 6.5.7 Column Diameter ___________________________________________ 86 6.5.8 Height of the column : _______________________________________ 86 6.5.9 Plate Pressure Drop __________________________________________ 88 6.5.10 Residual Head ______________________________________________ 89 6.5.11 Check Residence Time _______________________________________ 89 6.5.12 Check Entrainment __________________________________________ 89 6.6 Mixing Tank Design_____________________________________________ 91 6.6.1 Volume Calculation _________________________________________ 91 6.6.2 Thickness _________________________________________________ 91 6.6.3 choice of closure :- __________________________________________ 92 6.6.4 Impeller design _____________________________________________ 93 6.6.5 Design Data________________________________________________ 96 Chapter 7 INSTRUMENTATION & PROCESS CONTROL _________________ 97 7.1 Introduction ___________________________________________________ 97 7.1.1 Requirements of Control ______________________________________ 97 7.1.2 Safety ____________________________________________________ 97 7.1.3 Product Specification ________________________________________ 97 7.1.4 Environmental Regulation ____________________________________ 97 xiv 7.1.5 Operational Constraints_______________________________________ 97 7.1.6 Economics _________________________________________________ 98 7.2 Reactors ______________________________________________________ 98 7.3 Heat Exchanger ________________________________________________ 99 7.4 Distillation Column ____________________________________________ 100 Chapter 8 COST ESTIMATION _______________________________________ 102 8.1 Introduction __________________________________________________ 102 8.2 Equipment Cost Estimation ______________________________________ 103 8.1.1 Reactor Cost Estimation _____________________________________ 103 8.1.2 Flash Tank Cost Estimation __________________________________ 103 8.1.3 Heat Exchanger Cost Estimation ______________________________ 104 8.1.4 Centrifuge Cost Estimation ___________________________________ 105 8.1.5 Distillation Column Cost Estimation (D-1) ______________________ 106 8.1.6 Distillation Column Cost Estimation (D-2) ______________________ 108 8.3 Total Equipment Cost___________________________________________ 110 8.4 Total Physical Plant Cost (PPC)___________________________________ 110 8.5 Total Investment_______________________________________________ 111 8.6 Annual Operating Cost __________________________________________ 111 8.7 Direct Production Costs _________________________________________ 112 8.8 Annual Production Cost _________________________________________ 113 8.9 Production Cost _______________________________________________ 113 Chapter 9 SITE & MATERIAL SELECTION ____________________________ 114 9.1 The Project ___________________________________________________ 114 9.2 Proposal for Site Location _______________________________________ 114 9.2.1 Raw Materials _____________________________________________ 114 xv 9.2.2 Climate __________________________________________________ 115 9.2.3 Market ___________________________________________________ 115 9.2.4 Waste Disposal ____________________________________________ 115 9.2.5 Transport _________________________________________________ 115 9.2.6 Water Supply______________________________________________ 115 9.2.7 Labour Supply_____________________________________________ 116 9.3 Conclusion ___________________________________________________ 116 Chapter 10 HAZOP STUDY ___________________________________________ 117 10.1 HAZOP On Double Pipe Heat Exchanger _________________________ 117 10.2 HAZOP On Distillation Column (Parameter Pressure) _______________ 118 10.3 HAZOP On Distillation Column (Parameter Temperature) ____________ 119 10.4 Hazard Analysis _____________________________________________ 120 Appendix A Matlab Program __________________________________________ 124 Appendix B Flash Tank Data _________________________________________ 128 Appendix C D-1 Data _______________________________________________ 130 Appendix D D-2 Data _______________________________________________ 135 Appendix E Heat Exchanger Charts & Graphs ____________________________ 139 Appendix F Costing Indices __________________________________________ 143 References ___________________________________________________________ 145 xvi Chapter 1 INTRODUCTION 1.1 Biofuels Such fuels which are usually obtained from the flora and fauna around us are usually called as biofuels. Ever since the start of the industrial revolution people have had the idea of running automobiles on edible oils. In that sense biodiesel is also a biofuel. It dates back to 1853 and was coined by E. Duffy and J. Patrick. At the Paris, International Exhibitio n in 1900, Rudolf Diesel demonstrated a test engine sample working on peanuts oil. In 1912, Rudolf Diesel said, “The use of vegetable oils for engine fuels may seem insignifica nt today. But such oils may become in course of time as important as petroleum and the coal tar products of the present time” (Marco Aurélio, 2011). Diesel was indeed right as in the previous decade we saw conventional fuel prices sky rocketing. This immensely helped the sustainable energy sector as it put in the minds of people, the fear of economic shakedown both on an individual as well as on a national basis. 1.2 What Is Biodiesel? To a layman term biodiesel implies diesel obtained from biological sources such as plant or animals. It is a type of biofuel. As it turns out there are essentially 4 ways of converting organic sources into biodiesel. These are listed as. 1. Direct use or blending of oils 2. Micro-emulsion 3. Pyrolysis (gasification) 4. Trans-esterification Biodiesel or fatty acid methylated esters are derived or obtained from animal or plant stocks, due to their renewability they form a sustainable class of fuels. This very reason makes them a very viable choice for future fuels and hence they are receiving considerable importance from the scientific community. One of the very simple production methods of biodiesel is transesterification in which the triolein sources are reacted with methanol under appropriate conditions, often in the presence of a catalyst. The catalyst even through it is not consumed during the reaction helps decrease the reaction times. The main product of these reactions is simply biodiesel while glycerol is produced as a by-product in the aftermath of the reaction. Due to higher conversions in this reaction it is understood that very little oil is wasted. In order to bypass the catalyst, use we can run the reaction under supercritical conditions however this amounts to increased costs. Another method is via the use of biochemical routes. Now looking at the point number one the confusion persists that whether or not vegetable oil is or is not an alternative of conventional fuels in pure form. Actually, vegetable is a whole lot more viscous that biodiesel, it also has very high flash point due to this very reason and some others vegetable cannot be used as an alternative to diesel as it is and has to be processed before usage. One of the methods as listed above is the transesterifica tio n of the oils. This involves the conversion of the triglycerides (oils) into methylated or ethylated esters. However due to the efficiency and other concerns methylated ester are often preferred. Also, that they burn efficiently and provide more power. Because of the lesser energy costs and greater viability as opposed to the other processes we will prefer the method of transesterification. 1.3 Advantages & Disadvantages 1. One of the key advantages of this biofuel is sustainability. The fact that we grow cooking oil sources means that an abundance can theoretically be made. 2. Biodegradability is another important factor which contributes to the pro camp of biodiesel. A simple proof of that is when left in open atmospheric conditions biodiesel degrades much more rapidly as compared to commercial diesel. 3. There is less sulphur in biodiesel as compared to commercial diesel. This leads to some major environmental pros while the greater amount of oxygen ensures that this biofuel burns completely deceasing the emission of CO2. Biodiesel despite being “greener” has its own demerits some of which are discussed below. 1. Greater NOx emissions. 2. Despite being less viscous that cooking oils biodiesel is still more viscous than diesel, this is the reason we still have to mix biodiesel with commercial grade diesel. 2 Viscosity leads to stresses and large droplets which can cause wear on the fuel inject or systems. 3. Remember the degradation part, here is when it becomes a problem. When exposed to the open environment for longer periods these esters degrade into smaller components and decrease some of the desirable properties of our fuel. 4. Except for a few countries vegetable oils are generally very expensive. Even in Pakistan which is an agricultural economy the price of vegetable oil is higher than that of commercial diesel. This takes a huge toll on the economic viability of the whole process. 1.4 What Are Oils? Fats and oils are primarily water-insoluble, hydrophobic substances in the plant and animal kingdom that are made up of one mole of glycerol and three moles of fatty acids and are commonly referred to as triglycerides. The difference between a fat and oil is signified by their physical states at room temperature. A triglyceride that is a liquid at room temperature is called as oil while a triglyceride that is solid at room temperature is called as a fat. One important thing to note here is that triglycerides derived from mammals are usually fats while those derived from cold blooded animals as well as plants are oils. 1.5 Vegetable Oils as Fuels (Properties) Vegetable cooking oils have viscosities 11-17times that of diesel fuel. Volumetric heating values is about 39-40 Mega Joule/kg while for diesel it is 45 Mega Joule/kg. The flash point for vegetable oils is very high, more than 200 degrees centigrade. It has been found that the utilization of vegetable oils as fuels led to problems related to type and grade of oil as well as climate conditions. Some common problems are carbon deposits, plugging if the fuel lines, gelling of lubricating oils, foiled piston heads and ring sticking. Cetane number of vegetable oils is very high hence reducing the ignition delay. In addition to all this they have high iodine value which increases their oxidation rate. Therefore, long time storage is not recommended for vegetable oils. 3 Chapter 2 LITERATURE REVIEW 2.1 Process Selection Of the several methods, available for producing bio- diesel, transesterification of natural oils and fats is currently the method of choice. The purpose of the process is to lower the viscosity of the oil or fat. As far as the other processes are concerned, although blending of oils and other solvents and micro emulsions of vegetable oils lowers the viscosity it causes engine performance problems, such as carbon deposit and lubricating oil contamination. Meanwhile, pyrolysis produces more bio gasoline than biodiesel fuel [1]. 2.2 Transesterification Transesterification of vegetable oils with alcohol is the best method for biodiesel production. There are two types of transesterifications, one is with catalyst and other one is without catalyst. Transesterification is a reversible reaction and the excess of alcohol shifts the equilibrium to the product side. Base-catalysed transesterification is one process that converts waste cooking oil to biodiesel fuel. Fats and oils are tri esters of glycerol (triglycerides), with three long chain fatty acids that give the molecule a high molecular weight and low volatility. A base- catalysed transesterification (using methanol as the alcohol and NaOH as the catalyst) converts fats and oils to the methyl esters of the three individual fatty acids. It is to be noted here that the reaction would still proceed without a catalyst but would be too slow and may take days to complete, therefore the addition of catalyst becomes necessity. With molecular weights about a third of the original triglyceride, these methyl esters are more volatile and work well in diesel engines, the mixture of fatty acid methyl esters is called biodiesel [2]. The purpose of using methanol is its low commercial price and the reason that it gives better performance in engines. Methanol has both physical as well as chemical advantages. Esters produced using methanol gave higher power and produced more torque [3]. 2.3 Pre-treatment Free fatty acids are known as to cause saponification during the transesterification reaction. Soaps make biodiesel purification harder and hence it is necessary to limit the FFA content. 4 This is done by the esterification process in which acid along with methanol is employed to convert the FFAs into esters (biodiesel). Glycerine washing is then employed to purify the refined oil. After such a treatment, the oil phase, having a low level of free fatty acids (less than 0.5 wt.%), was subjected to the alkali-catalysed transesterification. 2.4 Standard Practices & Their Flowsheets Conventionally the alcoholysis or transesterification of virgin or used cooking oils is done via base catalyst. This can be done in either batch mode or it can be a continual process. In most cases the catalyst is sodium hydroxide or sodium methylate. It is recovered after the transesterification reaction as sodium glycerate, sodium methylate and sodium soaps in the glycerol phase. An acidic neutralization step with, for example, aqueous hydrochlo r ic acid is required to neutralize these salts. In that case glycerol is obtained as an aqueous solution containing sodium chloride. Depending on the process, the final glycerol purity is about 80% to 95%. When caustic is employed in the catalyst role it can react with the broken glycerides to form soap. These soaps can dissolve in the glycerol produced during the reactions in the reactors. They cause a major hurdle in the purification of glycerol. These soaps need to be broken down into FFAs by employing HCl. We have done this in our process. The loss of esters converted to fatty acids can reach as high as 1% of the biodiesel production. 5 Figure 2.4 Global Scheme for A Typical Biodiesel Setup 2.5 Raw Materials 2.5.1 Choice of Oil There are more than 350 oil bearing crops identified, among which only sunflo wer, soybean, cottonseed, rapeseed and peanut oils are considered as potential alternative fuels for diesel engines [4]. We will be considering soya oil because the biodiesel produced by this type of waste shows similar properties as diesel. Another point that warrants its selection is it’s cetane number which is closer to petroleum diesel. Also, it is abundantly produced as waste. 2.5.2 Catalyst Transesterification can also be catalysed by Lowry acids. These catalysts give very high yields in alkyl esters but reactions are slow, requiring typically temperature above 100 degrees centigrade and hours to complete the conversion [5]. We therefore use base catalysed reactions which are comparatively less time consuming as compared to the before mentioned. For that purpose, we can use potassium or sodium hydroxide but because of better solubility of KOH with methanol we would likely prefer methanol. As we will come 6 to know the topic of catalyst is a sensitive one and affect heavily on the yield and reaction times of the process. The biodiesel industry currently uses sodium methoxide, because methoxide cannot form water upon reaction with alcohol such as with hydroxides, which influence the reaction and the quality of the production biodiesel [6]. Furthermore, base-catalysed reactions are performed at generally lower temperatures, pressures, and reaction times and are less corrosive to industrial equipment than acid-catalysed methods [7]. Therefore, fewer capital and operating costs are incurred by biodiesel production facilities in the case of the base- catalysed transesterification method. 2.5.3 Alcohol Studies have shown that methylated esters are more suitable for diesel engines as compared to ethylated ones. Hence, we will want a source for a methyl group and not an ethyl group. The obvious choice is methanol. Another advantage is the cost factor because methanol is cheaper than ethanol and easier to source as compared to ethanol. Ethanol could even be a banned item in a specific country due to various reasons. 2.5.4 Factors Affecting the Transesterification Process Main factors affecting the transesterification process are. 1. Methanol/Oil Molar Ratio 2. Temperature 3. Reaction Time 4. Mixing 5. FFAs & Moisture 6. Catalyst Conc. 7 Figure 2-5-Factors Effecting FAME 8 Chapter 3 PROCESS DESCRIPTION & FLOWSHEET 3.1 Process Flow Diagram & Description Figure 3.1.1-Process Flow Diagram 3.1.1 Filter First of all, the waste cooking oil or WCO goes to a filter where solid chunks of impurities in it are removed. These are chunks from the eatables that have been heated in the oil. This filtered WCO is then pumped into the reactor R1. The oil is still high In FFAs however hence and cannot be processed by regular base catalysed transesterification method hence 9 we first need to perform acid assisted esterification in order to bring the FFAs to an acceptable level before we can pursue the traditional base catalysed transesterification. 3.1.2 Heat Exchanger (HE-1) Water is heated to 55 °C in HE-1. This water is used to wash the biodiesel further along the process. According to [8] hot water washing is a good way to obtain high purity biodiesel (FAME) product. 3.1.3 Pre-Treatment Reactor In the pre-treatment reactor esterification reaction is carried out at 70 °C, 400 kPa and a 6:1 molar ratio of methanol to crude oil. This is necessary in order to bring the FFAs downs to a level where they can be processed by the transesterification reactor i.e. R-1. Otherwise the free fatty acids can react with the alkali catalyst to produce soaps causing emulsio ns. Emulsions make the purification of biodiesel difficult. 3.1.4 Heat Exchanger (HE-2) Mix of caustic and alcohol is heated to 60 °C in this heat exchanger. This stream is used both in R-1 & R-2 and since our reaction takes place at 60 °C, hence this stream is heated to 60 °C. 3.1.5 Heat Exchanger (HE-3) The HE-3 heats the filtered waste cooking oil from ambient temperatures to 60 °C. 3.1.6 Pre-treatment Heat Exchanger (PT_HE-1) Effluents of the pre-treatment reactor are cooled in this heat exchanger to 46 °C. 3.1.7 Pre-treatment Heat Exchanger (PT_HE-2) The glycerine washing separates the oil and it is heated in this heat exchanger. This oil is then routed to the R-1 for base catalysed transesterification. The purpose of this heat exchanger is angina, to bring the temperature of oil to 60 °C. The FFAs by now have been brought down to acceptable levels. 10 3.1.8 Pre-treatment Distillation (P_D) The stream other than the majority oil stream emanating from the glycerine washing column is treated in this distillation unit. In P_D, five theoretical stages and a reflux ratio of 5 are used. At 28 °C and 20 kPa, 94% of the total methanol fed to the column is recovered in the distillate (i.e., stream 111) at the rate of 188 kg/h. It contained 99.94% methanol and 0.06% water and is recycled to pre-treatment esterification reactor. At 70 °C and 30 kPa, bottom stream 112 (147 kg/h) is composed of 75% glycerol, 8% methanol, 7% sulfur ic acid, 7% oil and 3% water. 3.1.9 Reactor1 (R1) Filtered WCO then enters the reactor1 where a feed of caustic mixed with methanol is already coming in. The oil is heated to approx. 55-60 degree centigrade at atmospheric pressure. Under such condition 90% conversion is achieved in the first reactor. Effluent of R1 contains biodiesel, un-reacted oil, soap, salts etc. 3.1.10 Heat Exchanger (HE-4) Effluents of R-1 are heated to 60 °C. 3.1.11 Reactor2 (R2) Stream originating from C1 goes to R2 along with remaining methanol + catalyst at atmospheric pressure and residence time of 1 hour. Here our conversions levels touch the 99% mark. 3.1.12 Centrifuge1 (C1) The effluent of R1 goes to the centrifuge where the un-reacted oil and the biodiesel produced are separated from the glycerol. This glycerol is not pure and needs treatment in terms of solvent recycles and impurity removal. 3.1.13 Centrifuge2 (C2) The effluent of R2 is fed to the centrifugal separator where the un-reacted oil and the biodiesel produced are separated from the glycerol. This glycerol is not pure and needs treatment in terms of solvent recycles and impurity removal. 11 3.1.14 Mixing Tank1 (Wash Tank) Now the biodiesel stream from the C2 is fed to the mixing tank and is washed with the process wash water and HCL solution. This neutralizes the catalyst and converts any soap to FFA. 3.1.15 Centrifuge 3 (C3) The MT1 effluent is fed to the centrifuge where the biodiesel is recovered together with small amounts of water. 3.1.16 Flash Tank (FT1) Final purification of biodiesel is achieved in the flash drum that operates under vacuum. (5 kPa). 3.1.17 Mixing Tank2 (MT2) Streams originating from C1, C2, C3 and the stream from the head of the FT end up in the MT2. These contain methanol, glycerol, water as well as FFA, soaps and salts. This stream is first treated with HCl to convert soaps into FFAs. 3.1.18 Centrifuge4 (C4) The effluent of MT2 then passes through the C4 and thus FFAs get removed. We get a stream that is rich in methanol and glycerol. 3.1.19 Mixing Tank3 (MT3) Glycerol and methanol rich stream is treated with NaOH to maintain pH. The resulting stream is fed to the distillation columns D1. 3.1.20 Heat Exchanger (HE-5) The purpose of this heat exchanger is to bring the feed of the first distillation column to the required temperature. 3.1.21 Distillation Column 1 (D1) D1 operates slightly above atmospheric pressure. We get glycerol and water from bottom which is 80% wt. /wt. glycerol & water. The top product consists of water and methanol. 12 3.1.22 Distillation Column 2 (D2) D2 is operated at high pressure (50 kPa). We get almost pure 99.99 % methanol which is then recycled as input stream from the top. Water is obtained from the bottom which can be recycled as washing water. 3.2 Products There are two main products of the transesterification process. Glycerin Biodiesel 3.1.23 Glycerine To make the biodiesel plant economically attractive we have to make sure that anything coming out of a product line other than the main product itself is sellable. For the most part only two products are produced in a continuous biodiesel plant, its biodiesel and glycerol. Excess methanol is reused or sold. However, there is a catch, glycerol produced during the process is impure since it contains some quantities of methanol which make it highly unsafe for a large sector of human consumable producing industries. It also has salts as well as FFAs. Its physical appearance is also very undesirable. Hence the traditional markets are off limits. To make the glycerol pure we generally flash or distil it but since it (glycerol) is a high boiling component it can cause a strain on our financials. So, what ends up happening is that this bio glycerol is used as a cattle feed supplement as it adds to the cattle’s feed to weight gain ratio. This is because certain animals can handle toxic methanol and its breakdown products. Another use for the bio glycerol is the cement industry. It is added to various parts of the process such as in clinkering, kilning etc. to add to the cement strength. However, in our project the simulation indicates that the bottom product is essentially 80% glycerol and 20% methanol. If this can be translated to reality, then the economic viability of the process can surely be ever increased. 3.3 Testing of Used Oil Chemically used oils contain triglycerides. When they are used for cooking purposes these go through changes and the oil ends up having abundance of free fatty acids. It is these 13 acids that cause the acidity of the used oil. The problem is that when we try to make biodiesel out of such oil and add KOH and alcohol for the purpose along with alcohol, it ends up making soap. Soap is not what we want, we want biodiesel. So, for that we have to measure the extra amount of KOH that needs to go in our batch of waste oil. For this very purpose, we do a titration of our oil sample. Prepare titration solution by mixing 1 gram of KOH in 1 L distilled water. Prepare 3 beakers. Take1 ml of waste cooking oil and pour in beaker no. 1. Pour 10 ml of isopropyl alcohol. Take your titrating solution in a third beaker. Mix oil and alcohol. Add some indicator drops into the oil and alcohol mixture. Now begin titrating. Slowly pour the titrating solution till pink colour appears and remains so for 30 seconds. It is generally considered that oil using 0-3 ml of the above-mentioned titrating solution indicates a “good” cooking oil. Oil that uses 3-5 ml of the titration solution is average oil while anything above that is harmful for human health since it has been heavily used and has a lot of fatty acids. It is to be noted here that the presence of FFA greatly affects the transesterification process. It has been noted that our oil must have a FFA value lower than 3% for the base catalysed reaction to produce favourable results. Ester yields are greatly reduced in the presence of greater than three percent FFAs. Since we are using a base catalysed process we have to debate on the Achilles heel of base catalysed transesterification and that is be soap formation. The issue is not so relevant as long as the FFAs are within the 3-4 % mark but waste or used cooking oils can contain up to 15 % FFAs. Our catalyst NaOH doesn’t react well with triglycerides but reacts with mono glycerides well and diglycerides to some extent. This results in soap which again calls for even more purification. And with purification comes energy costs. To counter this problem, we can use vacuum distillation to remove the FFAs from our triglycer ides beforehand and sell them off either as animal feed or a separate esterification can be arranged where different conditions can be perhaps used to convert these FFAs into biodiesel. For smaller values of FFAs we can simply add in more catalyst and carry on with removing the soap [9]. Now that we’ve calculated the catalyst to be used we can now proceed with the normal biodiesel production. This is because we have effectively counteracted the free fatty acids. 14 Coincidentally this test can also be used to gauge how good our oil is for cooking purposes. Used oil having a significant amount of free fatty acids is not a good choice. It is harmful for health. This is precisely the reason that used cooking oil should not be reused rather it should be waster in accordance with the laws of the country. 15 Chapter 4 MATERIAL BALANCE Material balance is the backbone in the design and conceiving of a chemical plant along with the energy balance. It helps us in conceiving the designs, in financial evaluation, in process control and in optimizing the process. Let’s say for example a solvent is required for the extraction of soya bean oil (which also happens to be our primary triolein) from the its source. In order to calculate the arithmetic quantity of that solvent required we can apply the material balance on that particular unit. But even better is that we can not only use that information to calculate the amount of solvent required we can also use that informa tio n for the design and development of the machines that extracts the soya bean oil. Hence in every plant design we first go through the phase of the material balance. We can use the processed information in the design of equipment or in the evaluation of the economics of the process. Material balance can also help in deciding the raw material that we can use to achieve the same end product. Quite a few different types of processing can achieve the same end result, so that case studies (simulations) of the processes can assist materially in the financial decisions that must be made. Material balances also helps in the hourly and daily operating decisions of plant managers. For the most part we’ve used stoichiometry for our balances especially in reactors. For almost all separation processes in our process we were provided with figures. 4.1 Survey for Waste Cooking Oil Collection We carried out an online survey to assess the amount of waste oil we could gather. According to eatoye.com Lahore has 1000 restaurants from which you can order a delivery... but the website has mostly branded places listed so we can only get but a rough estimate from the website. I am going with an estimate that Lahore has three times the places eatoye.com has listed. Exotic food is limited so I am going with a very low estimate. The average waste vegetable oil generation column has been sourced from a study [10]. Units are litres/month as also indicated in the paper from where the figures are sourced. Most establishments seem to favour canola oil, while unspecified vegetable oil and liquid shortening bring up a distant second and third respectively. The survey showed that vegetable oils like sunflower oil and corn-mixes were the least common types of oils being used in the group. Low responses in the Sunflower Oil, Corn/Soy Oil and 16 Corn/Canola Oil categories produced exceptionally high averages, skewing the data and producing a total average volume significantly higher than the total average volume by restaurant type. 3.1.24 Capacity Selection Waste Cooling Oil Flow 30068.9043 kg/day OR 30.06 ton/day 4.2 Material Balance (Filter) The composition of our crude oil after pre-treatment is as such. Fin Calculatio Fout1 Calculatio Fout2(kg/hr. Component (Kg/hr.) n (Kg/hr.) n ) 1220.296 1220.2963* Oil 1220.2963 ~ ~ 3 1 Palmitic. A 7.016 7.016*1 7.016 ~ ~ Moisture 3.13 3.13*1 3.13 ~ ~ Unsaponifie 55.87 ~ ~ 55.87*1 56.25 d 17 Ash .37586 ~ ~ .37586*1 .37586 Table 4.2-1 Material Balance (Filter) 4.3 Material Balance Reactor1 (R-1) The reaction is as: 1𝑡𝑟𝑖𝑜𝑙𝑒𝑖𝑛 + 6𝑚𝑒𝑡ℎ𝑎𝑛𝑜𝑙 ⇔ 3𝐹𝐴𝑀𝐸 + 1𝑔𝑙𝑦𝑐𝑒𝑟𝑜𝑙 + 3𝑚𝑒𝑡ℎ𝑎𝑛𝑜𝑙 𝑐𝑎𝑡𝑎𝑙𝑦𝑠𝑡 1 mole FFA consumes 1 mole of catalyst to produce 1 mole of soap + water. 1𝐹𝐹𝐴 + 1𝑐𝑎𝑡𝑎𝑙𝑦𝑠𝑡 ⇔ 1𝑠𝑜𝑎𝑝 + 1𝑤𝑎𝑡𝑒𝑟 𝑐𝑎𝑡𝑎𝑙𝑦𝑠𝑡 Reactor conditions and parameters are as such. Figure 4.2.1 Material Balance (Filter) Pressure Atmospheric 18 Temperature 60 °C Conversion 90 % Residence Time 1 hour Table 4.3-1 Reactor1 Parameters Calculation (90% Component Fin (Kmol/hr.) Fout (Kmol/hr.) Conv.) 1.3558 - Oil 1.3558 .13558 (1.3558*.90) Palmitic. A .025 .025 - .02255 .00250 Moisture (Water) .174 .174 + .0222 .1965 FAME ~ 3*(1.3558*.90) 3.660 Glycerol ~ 1.3558*.90 1.220 Methanol 7.32 3*(1.3558*.90) 3.6608 Catalyst .2929 .2929-(.0250-.0025) .2787 Soap ~ .0250*.90 .0225 Table 4.3-2 Material Balance (R-1) Figure 4.3.1 Material Balance (R-1) 19 4.4 Material Balance (Reactor 2) Reactor 2 has similar conditions as reactor 1. Overall conversion is 99%. Pressure Atmospheric Temperature 60 °C Conversion 90 % Residence Time 1 hour Table 4.4-1 Reactor2 Parameters Calculation (90% Component Fin (Kmol/hr.) Fout(Kmol/hr.) Conv.) Oil .13558 .13558*.01 .001358 8.94E-06-(8.94E- Palmitic. A 8.94E-06 8.94E-07 06*90%) Moisture (Water) .001965 .0019 + .0002335 .00219 3.660 + FAME 3.660 4.0269 (3*.13558*.90) Glycerol ~ .13558*.90 .1220 2.196 + .7321 = (.13558*90%*3) + Methanol 4.539 2.9281 2.9281 .0026 + .029 = .029-((8.94E-06)- Catalyst .0301 .0316 .0000137) .000225 + (8.94E- Soap .000225 .0002335 06*.90) Table 4.4-2 Material Balance (R-2) 20 Figure 4.4.1 Material Balance (R-2) 4.5 Material Balance (Centrifuge1) Centrifuges are assumed to achieve 99% recovery of the components. In Centrifuge1 and Centrifuge2 methanol is assumed to be distributed by 60% in the biodiesel phase and 40% in the glycerol phase. In Centrifuge3 methanol is assumed to distribute by 10% in the biodiesel phase and in Centrifuge4 by 100% in the glycerol phase. Recovery 99 % 60 % (With FAME)/40% (With Methanol Distribution Glycerol) Table 4.5-1 Centrifuge1 Parameters Componen Fin(kg/hr. Calculation Fout1(kg/hr. Calculation Fout2(kg/hr. t ) s ) s ) FAME 1098.26 1098.26*1 1098.26 ~ ~ 21 Glycerol 112.267 ~ ~ 112.267*1 112.267*1 Methanol 117.148 117.148*.60 70.28 117.148*.40 46.859 Palmitic. A .7016 0.7016*.01 0.00701 .7016*.99 .69 Catalyst 11.1502 11.1502*.01 0.108 11.1502*.99 11.03 Soap 6.76 6.76*.01 0.067 6.76*.99 6.69 Oil 122.02 122.02*1 122.02 ~ ~ Water 3.538 3.538*.01 0.035 3.538*.99 3.52 Table 4.5-2 Material Balance (C-1) Figure 4.5.1 Material Balance (C-1) 4.6 Material Balance (Centrifuge 2) Recovery 99 % 22 60 % (With FAME)/40% (With Methanol Distribution Glycerol) Table 4.6-1 Centrifuge1 Parameters Componen Fin(kg/hr. Calculation Fout1(kg/hr. Calculation Fout2(kg/hr. t ) s ) s ) Palmitic. 1208.0934* 1208.0934 1208.0934 ~ ~ A 1 Glycerol 11.22 ~ ~ 11.22*1 11.22 145.2640*.6 145.2640*.4 Methanol 145.2640 87.1584 58.1056 0 0 .0002505*.0 .0002505*.9 FFA .0002505 1.37E-07 .0002480 1 9 Catalyst 1.2049 1.2049*.01 .011 1.2049*.99 1.160 Soap .07000 .07000*.01 .0007 .07000*.99 .06937 Oil 1.2202 1.2202*1 1.2202 ~ ~ Water .0395 .0395*.01 .000395 .0395*.99 .039 23 Table 4.6-2 Material Balance (C-2) Figure 4.6.1 Material Balance (C-2) 4.7 Material Balance (Mixing Tank 1) The stream is fed to a mixing tank together with process (wash) water and HCl solution so as to neutralize the catalyst and convert any soap to FFA. The wash and pH adjustment tank effluent is fed to a centrifuge (C3) where biodiesel is recovered with small amounts of water. There are two reactions occurring in this mixer… SOAP + HCl FFA + NaCl HCl + NaOH H20 + NaCl Wash Water Ratio (Wt.) 1:1 (For Every kg FAME) HCl (Molar) 1:1 (For Every Mole Catalyst + Soap) Table 4.7-1 Mixing Tank Parameters 24 Compone Fin1(kmol/ Calculatio Fin2(kg/h Fout1(kmol/ Calculation nt hr.) ns r.) hr.) FAME 4.0269 ~ ~ ~ 4.0269 Methanol 2.7237 ~ ~ ~ 2.7237 (3.19E- Palmitic. 3.196E-11 ~ ~ 11+293E-03) 2.10E-06 A *90% .012049- Catalyst .012049 ~ ~ 3.0122E-05 (.000293*90%) 2.33E-06- Soap 2.33E-06 ~ ~ 2.33E-07 2.10E-06 Oil .0013 ~ ~ ~ .0013 (.00029*.90+2.3 Salt ~ ~ ~ .0002656 3E-6) .00029+2.335E- HCl ~ ~ .000300 ~ 06 (1208.09/18) Water 2.199E-05 ~ 65.25 67.11 +2.19E-05 Table 4.7-2 Material Balance (MT-1) 25 Figure 4.7.1 Material Balance (MT-1) 4.8 Material Balance (Centrifuge 3) Recovery 99 % Methanol Distribution 10 % (FAME) / 90% (Glycerol) Table 4.8-1 Centrifuge3 Parameters Compone Fin(kg/hr Fout1(kg/hr Fout2(kg/hr Calculations Calculations nt .) .) .) FAME 1208.0934 1208.0934*1 1208.0934 ~ ~ Methanol 87.15 87.15*.10 8.715 87.15*.90 78.435 Palmitic. .0005 .0005*.01 5.8E-06 .0005*.99 .0005 A Catalyst .0012 .0012*.01 .000012 .0012*.99 .00188 9.314E- 9.314E- Soap 9.314E-06 9.24E-08 9.34E-08 06*.01 06*.99 26 Oil 1.220 1.220*1 1.220 ~ ~ Salt .015 .015*.01 .00015 .015*.99 .015 1208.0992*.0 1208.0992*.9 Water 1208.0992 12.08 1196.9020 1 9 Table 4.8-2 Material Balance (C-3) Figure 4.8.1 Material Balance (C-3) 4.9 Material Balance (Flash Tank) Final purification of biodiesel is achieved in the flash drum that operates under vacuum. (5 kPa) 27 Fin Fout1 Component Calculation Calculation Fout2(kg/hr.) (Kg/hr.) (Kg/hr.) FAME 1208.0934 ~ ~ 1208.0934*1 1208.0934 Methanol 8.7158 8.7158*1 8.7158 ~ ~ Oil 1.186 ~ ~ 1.186*1 1.186 Water 12.08 12.08*1 12.08 ~ ~ Table 4.9-1 Material Balance (FT) Figure 4.9.1 Material Balance (FT) 4.10 Material Balance (Mixing Tank 2) 28 Compo Fin1(kg/ Fin2(kg/ Fin3(kg/ Fin4(kg/ Fout(kg/ Calculations nent hr.) hr.) hr.) hr.) hr.) Glycero 109.155 10.91 ~ ~ 109.155+10.91 120 l Methan 45.56+56.49+76.2 45.56 56.49 76.2 8.47 186 ol +8.47 Palmiti .6945+.00029+.00 .6945 .00029 .0005 ~ .6983 c. A 05 Catalys 10.70 1.16 .0116 ~ 10.70+1.16+.0116 11.8798 t 9.24E- 6.69+.069+9.24E- Soap 6.69 .069 ~ 6.76 06 06 1162.86 3.502+.039+1162. Water 3.502 .039 11.74 1178.15 3 8+11.74 Table 4.10-1 Material Balance (MT-2) 4.11 Material Balance (Centrifuge 4) Figure 4.10.1 Material Balance (MT-2) 29 Recovery 99 % Methanol Distribution 100 % In Glycerol Phase Table 4.11-1 Centrifuge4 Parameters Compone Fin(kmol/h Calculatio Fout1(kmol/h Calculatio Fout2(kmol/h nt r.) ns r.) ns r.) Glycerol 1.30 1.30*1 1.30 ~ ~ Methanol 5.8 5.8*1 5.8 ~ ~ Palmitic. .0024+.022 .0024 ~ ~ .0250 A 55 Catalyst .2933 ~ ~ ~ ~ Soap .02255 ~ ~ ~ ~ Water 64.800 64.8+.315 65.11 ~ ~ HCl .315 .003*1 .003 .2933+.022 NaCl ~ ~ ~ .31588 55 Table 4.11-2 Material Balance (C-4) 30 Figure 4.11.1 Material Balance (C-4) 4.12 Material Balance (Mixing Tank 3) Reaction taking place in the mixer 3 is as under… NaOH + HCl H2O + NaCl Compone Fin1(kmol/h Calculatio Fin2(kmol/h Calculati Fout1(kmol/h nt r.) ns r.) on r.) Glycerol 1.342 ~ ~ 1.342*1 1.342 Methanol 6.0038 ~ ~ 6.0038*1 6.0038 Water 66.96 ~ ~ 66.96*1 66.96 HCl .003 ~ ~ ~ ~ 31 NaOH ~ .003*1 .003 ~ ~ NaCl ~ ~ ~ .003*1 .003 Table 4.12-1 Material Balance (MT-3) Figure 4.12.1 Material Balance (MT-3) 4.13 Material Balance (Distillation Column 1) All glycerol is removed in the bottom product of D1 which is 80% w/w in glycerol and the remaining is predominantly water. Fin Fout Component Calculation Calculation Fout2(kg/hr.) (Kg/hr.) 1(Kg/hr.) Glycerol 123.49 ~ ~ 123.49*1 123.49 Methanol 192.123 192.123*1 192.123 ~ ~ Water 1205.40 1205.40*.90 1175.40 1205-1175 30 NaCl .1095 ~ ~ ~ ~ Table 4.13-1 Material Balance (D-1) 32 Figure 4.13.1 Material Balance (D-1) 4.14 Material Balance (Distillation Column 2) Fin Fout Component Calculation Calculation Fout2(kg/hr.) (Kg/hr.) 1(Kg/hr.) Methanol 192.123 192.123*1 192.123 ~ ~ Water 1175.40 ~ ~ 1175.40*1 1175.40 Table 4.14-1 Material Balance (D-2) 33 Figure 4.14.1 Material Balance (D-2) 34 Chapter 5 ENERGY BALANCE To properly utilize the energy that is consumed or produced within a chemical producing industry the engineer must be familiar with the fundamentals of the energy balance. This includes the know-how of the basic terminology associated with the subject. An engineer’s main attention ought to be devoted to heat, work, enthalpy, and internal energy. Next, the energy balance must be applied to the project. This can help in calculating the amount of steam that our heater needs for heating purposes or the cooling water required for cooling a stream to a required temperature. In our project, we have used the standard enthalpy calculation formula that goes as. 𝑇 𝐻 = 𝑚 ∫ 𝐶𝑝 𝑑𝑇 𝑇𝑑 𝑘𝑚𝑜𝑙 𝑊ℎ𝑒𝑟𝑒 𝑚 = 𝑚𝑜𝑙𝑎𝑟 𝑓𝑙𝑜𝑤 𝑟𝑎𝑡𝑒 𝑖𝑛 ℎ𝑟 𝐽 𝑊ℎ𝑒𝑟𝑒 𝐶𝑝 = ℎ𝑒𝑎𝑡 𝑐𝑎𝑝𝑎𝑐𝑖𝑡𝑦 𝑖𝑛 𝑘𝑚𝑜𝑙. 𝐾 𝑇𝑑 = 𝐷𝑎𝑡𝑢𝑚 𝑇𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒 𝑖𝑛 𝐾 𝑇 = 𝑆𝑝𝑒𝑐𝑖𝑓𝑖𝑒𝑑 𝑇𝑒𝑚𝑒𝑝𝑟𝑎𝑡𝑢𝑟𝑒 𝑖𝑛 𝐾𝑒𝑙𝑣𝑖𝑛 5.1 Cp Calculation We know that value of Cp and specific enthalpy is a function of temperature and that function can be written as an empirical power series equation. Now if we take this equation and put in the above equation and integrate it, we’ll get something like below which we can then use to calculate our enthalpy. 𝐶𝑝 = 𝑎 + 𝑏 ∗ 𝑇 + 𝑐 ∗ 𝑇 2 + 𝑑 ∗ 𝑇 3 𝑏 𝑐 𝑑 𝐻 = 𝑚 ∗ ( 𝑎 ∗ (𝑇 − 𝑇𝑑 ) + (𝑇 2 − 𝑇𝑑2 ) + (𝑇 3 − 𝑇𝑑3 ) + (𝑇 4 − 𝑇𝑑4 )) 2 3 4 𝑘𝑚𝑜𝑙 𝑊ℎ𝑒𝑟𝑒 𝑚 = 𝑚𝑜𝑙𝑎𝑟 𝑓𝑙𝑜𝑤 𝑟𝑎𝑡𝑒 𝑖𝑛 ℎ𝑟 𝐽 𝑊ℎ𝑒𝑟𝑒 𝐶𝑝 = ℎ𝑒𝑎𝑡 𝑐𝑎𝑝𝑎𝑐𝑖𝑡𝑦 𝑖𝑛 𝑘𝑚𝑜𝑙. 𝐾 𝑇𝑑 = 𝐷𝑎𝑡𝑢𝑚 𝑇𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒 𝑖𝑛 𝐾 35 𝑇 = 𝑆𝑝𝑒𝑐𝑖𝑓𝑖𝑒𝑑 𝑇𝑒𝑚𝑒𝑝𝑟𝑎𝑡𝑢𝑟𝑒 𝑖𝑛 𝐾𝑒𝑙𝑣𝑖𝑛 The values of heat constants were used from the book “Perry’s Chemical Enginee rs’ Handbook”. However, some values were also obtained from other sources such as Coulson Vol. 6 and internet. Some static Cp values were also used after appropriate unit conversion. Energy balance Calculation Steady state Law of conservation of energy applied on each equipment is applied by using the following equation. 𝐻𝑖𝑛 − 𝐻𝑜𝑢𝑡 + 𝐶𝑜𝑛𝑠𝑢𝑚𝑝𝑡𝑖𝑜𝑛 + 𝐻𝑒𝑎𝑡 𝐴𝑑𝑑𝑖𝑡𝑖𝑜𝑛 = 0 5.2 Equipment We are applying our energy balance on the following equipment… Heat Exchangers Reactors R1 and R2 Distillation Column D1 and D2 Flash Tank Figure 5.2.1 Steam Properties 36 5.3 Energy Balance Heater (HE-1) The heater is used for heating water that washes the FAME. For every kg biodiesel, we use 1 kg water, since hot water provides better washing we heat it to about 55 °C. Our reference or datum temperature is 25 °C. Figure 5.3.1 Energy Balance (HE-1) So, as stated above we calculate the specific enthalpy of our feed and product stream using the heat equation constants from the Perry’s. We then put it into the formula to calculate our enthalpy. Flow 𝑯𝒊𝒏 − 𝑯𝒐𝒖𝒕 Component a b c D T1 T2 𝑱 (kmol/h) =𝑸( ) 𝒉𝒓. Water 276370 -2090 8.125 - 298 333 79.11 1.72E+08 0.0141 Table 5.3-1 Energy Balance (HE-1) 𝑄 𝑘𝑔 𝑅𝑒𝑞𝑢𝑖𝑟𝑒𝑑 𝑆𝑡𝑒𝑎𝑚 𝐹𝑙𝑜𝑤 𝑅𝑎𝑡𝑒 (𝑚𝑠𝑡𝑒𝑎𝑚 ) = = 79.11 𝜆 ℎ𝑟. 𝑗𝑜𝑢𝑙𝑒𝑠 𝜆 = 𝐿𝑎𝑡𝑒𝑛𝑡 𝐻𝑒𝑎𝑡 𝑂𝑓 𝑉𝑎𝑝𝑜𝑟𝑖𝑧𝑎𝑡𝑖𝑜𝑛 𝑂𝑓 𝑆𝑡𝑒𝑎𝑚 = 2174000 𝑘𝑔 37 5.4 Energy Balance Heater (HE-2) This heater is used to heat the entering methanol and caustic to 60 °C. this is because our reaction in the reactor takes place at 60 °C. Figure 5.4.1 Energy Balance (HE-2) Flow Heat Heat 𝑯𝒊𝒏 − 𝑯𝒐𝒖𝒕 Component a b c d e T1 T2 𝑱 (kmol/h) In Out =𝑸( ) 𝒉𝒓. Catalyst 883.47 - -3.01 - .0422 298 333 .071 2.49 .862 0E+00 2.3E+7 2.3E+7 Methanol 105800 - .9379 0 0 298 333 8.053 362. Table 5.4-1 Energy Balance (HE-2) 𝑄 𝑘𝑔 𝑅𝑒𝑞𝑢𝑖𝑟𝑒𝑑 𝑆𝑡𝑒𝑎𝑚 𝐹𝑙𝑜𝑤 𝑅𝑎𝑡𝑒 (𝑚𝑠𝑡𝑒𝑎𝑚 ) = = 11.01 𝜆 ℎ𝑟. 𝑗𝑜𝑢𝑙𝑒𝑠 𝜆 = 𝐿𝑎𝑡𝑒𝑛𝑡 𝐻𝑒𝑎𝑡 𝑂𝑓 𝑉𝑎𝑝𝑜𝑟𝑖𝑧𝑎𝑡𝑖𝑜𝑛 𝑂𝑓 𝑆𝑡𝑒𝑎𝑚 = 2174000 𝑘𝑔 38 5.5 Energy Balance Heater (HE-3) Figure 5.5.1 Energy Balance (HE-3) Component a b c d e T1 T2 Flow Heat Heat 𝑯𝒊𝒏 − 𝑯𝒐𝒖𝒕 𝑱 (kmol/h) In Out =𝑸( ) 𝒉𝒓. Oil .45 .0007 .99 0 0 298 333 1120.646 FFA .43 0 0 0 0 298 333 7.01 1124.5 9.1E+7 9.13E+07 Water 276370 - 8.125 - 9e- 298 333 .174 2090 .014 6 Table 5.5-1 Energy Balance (HE-3) 𝑄 𝑘𝑔 𝑅𝑒𝑞𝑢𝑖𝑟𝑒𝑑 𝑆𝑡𝑒𝑎𝑚 𝐹𝑙𝑜𝑤 𝑅𝑎𝑡𝑒 (𝑚𝑠𝑡𝑒𝑎𝑚 ) == 42.02 𝜆 ℎ𝑟. 𝑗𝑜𝑢𝑙𝑒𝑠 𝜆 = 𝐿𝑎𝑡𝑒𝑛𝑡 𝐻𝑒𝑎𝑡 𝑂𝑓 𝑉𝑎𝑝𝑜𝑟𝑖𝑧𝑎𝑡𝑖𝑜𝑛 𝑂𝑓 𝑆𝑡𝑒𝑎𝑚 = 2174000 𝑘𝑔 39 5.6 Energy Balance Heater (HE-4) Figure 5.5.1 Energy Balance (HE-4) Flow Heat 𝑯𝒊𝒏 − 𝑯𝒐𝒖𝒕 Component a b c d e T1 T2 Heat In 𝑱 (kmol/h) Out =𝑸( ) 𝒉𝒓. FAME 30060 206 6 0 0 328 333 3.9153 44E- 3.E- 9E- Glycerol 8.242 0 328 333 0.11864 01 04 08 - Methanol 105800 .9379 0 0 328 333 4.413 362.3 FFA .43 0 0 0 0 328 333 8.95E-07 9.25E+7 1.10E+8 1.73E+07 - - - Catalyst 883.47 .0422 328 333 0.02928 2.495 3.013 .8621 Soap .56 0 0 0 0 328 333 0.000233 - - 9E- Water 276370 8.125 328 333 0.002199 2090 0.014 06 Oil .45 .0007 .99 0 0 328 333 0.11864 Table 5.6-1 Energy Balance (HE-4) 40 𝑄 𝑘𝑔 𝑅𝑒𝑞𝑢𝑖𝑟𝑒𝑑 𝑆𝑡𝑒𝑎𝑚 𝐹𝑙𝑜𝑤 𝑅𝑎𝑡𝑒 (𝑚𝑠𝑡𝑒𝑎𝑚 ) = = 7.98 𝜆 ℎ𝑟. 𝑗𝑜𝑢𝑙𝑒𝑠 𝜆 = 𝐿𝑎𝑡𝑒𝑛𝑡 𝐻𝑒𝑎𝑡 𝑂𝑓 𝑉𝑎𝑝𝑜𝑟𝑖𝑧𝑎𝑡𝑖𝑜𝑛 𝑂𝑓 𝑆𝑡𝑒𝑎𝑚 = 2174000 𝑘𝑔 5.7 Energy Balance (Reactor 1) Conditions of our reactor are given below. Pressure Atmospheric Temperature 60 °C Conversion 90 % Residence Time 1 hour Table 5.7-1 Reactor1 Parameters Feed goes in at our datum temperature i.e. 25 °C and in the reactor, we maintain a temperature of 60 °C in the reactor as per the kinetics study. We do this by cooling the reactor with water. Supposing that the temperature of our water rises by a 30 °C when cooling the reactor, we can calculate how much cooling water is required. Figure 5.7.1 Energy Balance (R-1) 41 The values of our constants have been obtained from Perry’s Handbook. 𝑯𝒊𝒏 − 𝑯𝒐𝒖𝒕 Flow Heat Component a b c d e T1 T2 Heat In 𝑱 (kmol/h) Out =𝑸( ) 𝒉𝒓. FAME 30060 206 6 0 0 298 333 3.5594 Glycerol 8.242 44E- 3.E- 9E- 0 298 333 1.1864 01 04 08 Methanol 105800 - .9379 0 0 298 333 3.559 362.3 FFA .43 0 0 0 0 298 333 .0701 1.12E+8 1.10E+8 5.25E+07 Catalyst 883.47 - - - .0422 298 333 .2704 2.495 3.013 .8621 Soap .56 0 0 0 0 298 333 6.7655 Water 276370 - 8.125 - 9E- 298 333 .1965 2090 0.014 06 Oil .45 .0007 .99 0 0 298 333 118.646 Table 5.7-2 Energy Balance (R-1) ∆𝑇 = 30 °C 𝑗𝑜𝑢𝑙𝑒𝑠 𝐶𝑝 = 4120 𝑘𝑔°C 𝑄 𝑘𝑔 𝐶𝑜𝑜𝑙𝑖𝑛𝑔 𝑊𝑎𝑡𝑒𝑟 𝐹𝑙𝑜𝑤 = = 417.96 ∆𝑇𝐶𝑝 ℎ𝑟. 5.8 Energy Balance (Reactor 2) Conditions of our reactor are given below. Feed goes in at our datum temperature i.e. 25 °C and in the reactor, we maintain a temperature of 60 °C to maintain the optimal conditions for our first reactor. Pressure Atmospheric Temperature 60 °C 42 Conversion 90 % Residence Time 1 hour Table 5.8-1 Reactor2 Parameters Figure 5.8.1 Energy Balance (R-2) The values of our constants have been obtained from Perry’s. 𝑯𝒊𝒏 Flow Heat − 𝑯𝒐𝒖𝒕 Component a b c d e T1 T2 Heat In (kmol/h) Out 𝑱 =𝑸( ) 𝒉𝒓. FAME 30060 206 6 0 0 328 333 3.9153 Glycerol 8.242 44E- 3.E- 9E- 0 328 333 0.11864 01 04 08 Methanol 105800 - .9379 0 0 328 333 4.413 1.07E+8 1.11E+8 1.02E+07 362.3 FFA .43 0 0 0 0 328 333 8.95E-07 Catalyst 883.47 - - - .0422 328 333 0.02928 2.495 3.013 .8621 43 Soap .56 0 0 0 0 328 333 0.000233 Water 276370 - 8.125 - 9E- 328 333 0.002199 2090 0.014 06 Oil .45 .0007 .99 0 0 328 333 0.11864 Table 5.8-2 Energy Balance (R-2) ∆𝑇 = 30 °C 𝑗𝑜𝑢𝑙𝑒𝑠 𝐶𝑝 = 4120 𝑘𝑔°C 𝑄 𝑘𝑔 𝐶𝑜𝑜𝑙𝑖𝑛𝑔 𝑊𝑎𝑡𝑒𝑟 𝐹𝑙𝑜𝑤 = = 81.54 ∆𝑇𝐶𝑝 ℎ𝑟. 5.9 Energy Balance (Flash Tank) Flash tank is used for the purification of our biodiesel (FAME). The feed essentially contains methanol, water and biodiesel. It operates at 5 kPa. A valve is used to reduce the pressure while heat is provided to flash our mixture so that methanol goes into the upwards stream while biodiesel is obtained from the bottom. Figure 5.9.1 Energy Balance (FT) 44 Flow Heat 𝑯 𝒊𝒏 − 𝑯 𝒐𝒖𝒕 Component a b c d e T1 T2 Heat In 𝑱 (kmol/h) Out =𝑸( ) 𝒉𝒓. Water 276370 - 8.125 - 9E- 312.9 357.7 .67116 2090 0.014 06 Methanol 105800 - .9379 0 0 312.9 357.7 .27237 4.03E+8 1.84E+8 1.43E+08 362.3 FAME 30060 206 6 0 0 312.9 357.7 4.02 Table 5.9-1 Energy Balance (FT) 𝑄 𝑘𝑔 𝑅𝑒𝑞𝑢𝑖𝑟𝑒𝑑 𝑆𝑡𝑒𝑎𝑚 𝐹𝑙𝑜𝑤 𝑅𝑎𝑡𝑒 (𝑚𝑠𝑡𝑒𝑎𝑚 ) = = 65.88 𝜆 ℎ𝑟. 𝑗𝑜𝑢𝑙𝑒𝑠 𝜆 = 𝐿𝑎𝑡𝑒𝑛𝑡 𝐻𝑒𝑎𝑡 𝑂𝑓 𝑉𝑎𝑝𝑜𝑟𝑖𝑧𝑎𝑡𝑖𝑜𝑛 𝑂𝑓 𝑆𝑡𝑒𝑎𝑚 = 2174000 𝑘𝑔 5.10 Energy Balance Condenser Figure 5.10.1 Energy Balance (Condenser) 45 Flow Heat 𝑯 𝒊𝒏 − 𝑯 𝒐𝒖𝒕 Component a b c d e T1 T2 Heat In 𝑱 (kmol/h) Out =𝑸( ) 𝒉𝒓. - - 9E- Water 276370 8.125 357.7 328 .6526 2090 0.014 06 - 4.32E+6 2.31E+8 - 2.1E+06 Methanol 105800 .9379 0 0 357.7 328 .2648 362.3 Table 5.10-1 Energy Balance (Condenser) ∆𝑇 = 30 °C 𝑗𝑜𝑢𝑙𝑒𝑠 𝐶𝑝 = 4120 𝑘𝑔°C 𝑄 𝑘𝑔 𝐶𝑜𝑜𝑙𝑖𝑛𝑔 𝑊𝑎𝑡𝑒𝑟 𝐹𝑙𝑜𝑤 = = 17.37 ∆𝑇𝐶𝑝 ℎ𝑟. 5.11 Energy Balance Heater (HE-5) The purpose of this heat exchanger is to bring the feed of the first distillation column to the required temperature i.e. 100 °C. Figure 5.11.1 Energy Balance (HE-5) So, as stated above we calculate the specific enthalpy of our feed and product stream using the heat equation constants from the Perry’s. We then put it into the formula to calculate our enthalpy. 46 Flow Heat 𝑯 𝒊𝒏 − 𝑯 𝒐𝒖𝒕 Component a b c d e T1 T2 Heat In 𝑱 (kmol/h) Out =𝑸( ) 𝒉𝒓. Glycerol 8.242 44E- 3.E- 9E- 0 328 333 1.3015 01 04 08 Methanol 105800 - .9379 0 0 328 333 5.8374 1.51E+8 3.82E+8 2.31E+8 362.3 Water 276370 - 8.125 - 9E- 328 333 65.1159 2090 0.014 06 Table 5.11-1 Energy Balance (HE-5) 𝑄 𝑘𝑔 𝑅𝑒𝑞𝑢𝑖𝑟𝑒𝑑 𝑆𝑡𝑒𝑎𝑚 𝐹𝑙𝑜𝑤 𝑅𝑎𝑡𝑒 (𝑚𝑠𝑡𝑒𝑎𝑚 ) = = 106.18 𝜆 ℎ𝑟. 𝑗𝑜𝑢𝑙𝑒𝑠 𝜆 = 𝐿𝑎𝑡𝑒𝑛𝑡 𝐻𝑒𝑎𝑡 𝑂𝑓 𝑉𝑎𝑝𝑜𝑟𝑖𝑧𝑎𝑡𝑖𝑜𝑛 𝑂𝑓 𝑆𝑡𝑒𝑎𝑚 = 2174000 𝑘𝑔 47 5.12 Energy Balance Distillation Column (DC-1) Feed going into the distillation column contains glycerol, water and methanol. Since glycerol has a very high boiling point as compared to the other two, it is separated out firs t. The following column separates the methanol from water. The first distillation column operates at a bit higher pressure than atmospheric pressure. (101.3 kPa) Figure 5.12.1 Energy Balance (DC-1) 48 Flow Component a b c d e T1 T2 𝑸𝒃 (kmol/h) Glycerol 8.242 44E- 3.E- 9E- 0 328 333 1.305 01 04 08 Methanol 105800 - .9379 0 0 328 333 0 1.18E+09 362.3 Water 276370 - 8.125 - 9E- 328 333 1.66 2090 0.014 06 Table 5.12-1 Energy Balance for Boiler of DC-1 𝑄𝑏 𝑘𝑔 𝑅𝑒𝑞𝑢𝑖𝑟𝑒𝑑 𝑆𝑡𝑒𝑎𝑚 𝐹𝑙𝑜𝑤 𝑅𝑎𝑡𝑒 (𝑚𝑠𝑡𝑒𝑎𝑚 ) = = 542.93 𝜆 ℎ𝑟. 𝑗𝑜𝑢𝑙𝑒𝑠 𝜆 = 𝐿𝑎𝑡𝑒𝑛𝑡 𝐻𝑒𝑎𝑡 𝑂𝑓 𝑉𝑎𝑝𝑜𝑟𝑖𝑧𝑎𝑡𝑖𝑜𝑛 𝑂𝑓 𝑆𝑡𝑒𝑎𝑚 = 2174000 𝑘𝑔 Flow Component a b c d e T1 T2 𝑸𝒄 (kmol/h) Glycerol 8.242 44E- 3.E- 9E- 0 328 333 0 01 04 08 Methanol 105800 - .9379 0 0 328 333 5.8374 1.55E+09 362.3 Water 276370 - 8.125 - 9E- 328 333 63.4492 2090 0.014 06 Table 5.12-2 Energy Balance for Condenser of DC-1 ∆𝑇 = 30 °C 𝑗𝑜𝑢𝑙𝑒𝑠 𝐶𝑝 = 4120 𝑘𝑔°C 𝑄𝑐 𝑘𝑔 𝐶𝑜𝑜𝑙𝑖𝑛𝑔 𝑊𝑎𝑡𝑒𝑟 𝐹𝑙𝑜𝑤 = = 12352.67 ∆𝑇𝐶𝑝 ℎ𝑟. 49 5.13 Energy Balance Distillation Column (DC-2) The second distillation column operates at 50 kPa and separates methanol from water. 99.9 mole % methanol is obtained as the distillate. Figure 5.13.1 Energy Balance (DC-2) 50 Flow Component a b c d e T1 T2 𝑸𝒃 (kmol/h) Water 276370 - 8.125 - 9E- 328 333 63.44 2090 0.014 06 4.04E+08 Methanol 105800 - .9379 0 0 328 333 0 362.3 Table 5.13-1 Energy Balance for Boiler of DC-2 𝑄𝑏 𝑘𝑔 𝑅𝑒𝑞𝑢𝑖𝑟𝑒𝑑 𝑆𝑡𝑒𝑎𝑚 𝐹𝑙𝑜𝑤 𝑅𝑎𝑡𝑒 (𝑚𝑠𝑡𝑒𝑎𝑚 ) = = 185.87 𝜆 ℎ𝑟. 𝑗𝑜𝑢𝑙𝑒𝑠 𝜆 = 𝐿𝑎𝑡𝑒𝑛𝑡 𝐻𝑒𝑎𝑡 𝑂𝑓 𝑉𝑎𝑝𝑜𝑟𝑖𝑧𝑎𝑡𝑖𝑜𝑛 𝑂𝑓 𝑆𝑡𝑒𝑎𝑚 = 2174000 𝑘𝑔 Flow Component a b c d e T1 T2 𝑸𝒄 (kmol/h) Water 276370 - 8.125 - 9E- 328 333 0 2090 0.014 06 6.16E+07 Methanol 105800 - .9379 0 0 328 333 5.83 362.3 Table 5.13-2 Energy Balance for Condenser of DC-2 ∆𝑇 = 30 °C 𝑗𝑜𝑢𝑙𝑒𝑠 𝐶𝑝 = 4120 𝑘𝑔°C 𝑄𝑐 𝑘𝑔 𝐶𝑜𝑜𝑙𝑖𝑛𝑔 𝑊𝑎𝑡𝑒𝑟 𝐹𝑙𝑜𝑤 = = 490.34 ∆𝑇𝐶𝑝 ℎ𝑟. 51 Chapter 6 EQUIPMENT DESIGN AFTER ALL the preliminary work, has been completed, the detailed design work can begin. Equipment can be designed in its final form and full specification sheets prepared for each item. Process flowsheet and equipment list can be checked and amended. Cost estimates can also be revised to account for any significant changes from the preliminar y design specifications. 6.1 Reactor Design Parameter Value Units Reactor Type CSTR Dimensionless Temperature 60 / 333 °C/°K Total Conversion 99 % Residence Time 1 𝒉𝒐𝒖𝒓 Number of Reactors 2 Dimensionless Configuration Series Dimensionless Molar Flow of Oil (𝑭𝒂𝒐 ) 1.355 𝒌𝒎𝒐𝒍/𝒉𝒐𝒖𝒓 Volumetric Flow Rate of Oil (𝒗𝒂𝒐 ) 1.35 𝒎𝟑 /𝒉𝒐𝒖𝒓 Cao 1.0 𝒌𝒎𝒐𝒍/𝒎𝟑 Material of Construction SS Type 304 Dimensionless Reactor volume can be calculated by the study of kinetics in our process. The study of kinetics can lead us to the volume by algorithms specifically designed to calculate reactor volume, conversion etc. kinetics for the transesterification reaction have been thoroughly studied albeit with some confusion and contradiction. Despite this we were able to find a paper that specifically studied the soya bean oil transesterification under our specified conditions i.e. 6:1 methanol oil ratio. And 1 % of catalyst w.r.t the weight of our oil. The temperature however was 50 °C [10]. the reactions are as such. 𝑇𝐺 + 𝑀𝑒𝑂𝐻 ⇔ 𝐷𝐺 + 𝐹𝐴𝑀𝐸 𝑘1/𝑘2 𝐷𝐺 + 𝑀𝑒𝑂𝐻 ⇔ 𝑀𝐺 + 𝐹𝐴𝑀𝐸 𝑘3/𝑘4 52 𝑀𝐺 + 𝑀𝑒𝑂𝐻 ⇔ 𝐺𝐿 + 𝐹𝐴𝑀𝐸 𝑘5/𝑘6 𝑇𝐺 + 3𝑀𝑒𝑂𝐻 ⇔ 𝐺𝐿 + 3𝐹𝐴𝑀𝐸 𝑘7/𝑘8 The rate equations used for volume calculation are given below. 𝑑[𝑇𝐺] = −𝑘1 ∗ [𝑇𝐺][𝐴] + 𝑘2[𝐷𝐺 ][𝐴] − 𝑘7[𝑇𝐺 ][𝐴]3 + 𝑘8[𝐴][𝐺𝐿 ]3 𝑑𝑡 𝑑[𝐷𝐺] = −𝑘1 ∗ [𝑇𝐺 ][𝐴] − 𝑘2[𝐷𝐺 ][𝐸 ] − 𝑘3[𝐷𝐺 ][𝐴] + 𝑘4[𝑀𝐺][𝐸] 𝑑𝑡 𝑑[𝑀𝐺] = 𝑘3 ∗ [𝐷𝐺 ][𝐴] − 𝑘4[𝑀𝐺 ][𝐸 ] − 𝑘5[𝑀𝐺 ][𝐴] + 𝑘6[𝐺𝐿][𝐸] 𝑑𝑡 𝑑[𝐸] = 𝑘1 ∗ [𝑇𝐺 ][𝐴] − 𝑘2[𝐷𝐺 ][𝐸] + 𝑘3[𝐷𝐺 ][𝐴] − 𝑘4[𝑀𝐺 ][𝐸 ] + 𝑘5[𝑀𝐺 ][𝐴] − 𝑘6[𝐺𝐿 [𝐸] + 𝑘7[𝑇𝐺 ][𝐴]3 − 𝑘9[𝐺𝐿][𝐸] 𝑑𝑡 𝑑[𝐺𝐿] = 𝑘5 ∗ [𝑀𝐺 ][𝐴] − 𝑘6[𝐺𝐿][𝐸] + 𝑘7[𝑇𝐺 ][𝐴]3 − 𝑘8[𝐺𝐿][𝐸]3 𝑑𝑡 The mole balance equation for a CSTR is as under… 𝐹𝑇𝐺 − 𝐹𝑇𝐺𝑜 𝑉= −𝑟𝑇𝐺 𝐹𝑇𝐺 ∗ 𝑋 𝑉= −𝑟𝑇𝐺 𝑑[𝑇𝐺] 𝑤ℎ𝑒𝑟𝑒 → −𝑟𝑇𝐺 = 𝑑𝑡 53 We solved the differential equations in matlab for both the reactors. The program is provided in Appendix A. Upon solving the equations, we got two volumes each. Reactor 𝑑2 𝑉 =𝜋∗ ∗ℎ 4 5.3 ∗ 4 = 𝑑2 ∗ ℎ 𝜋 6.3 ∗ 4 = 𝑑3 𝜋 ∗ 1.5 4.5 = 𝑑 3 𝑑 ≈ 1.7 𝑚 1 has a volume of 6.3 𝑚3 while theℎsecond 3 𝑚 has a volume of 1.42 𝑚 . ≈ 2.6reactor Similarly, for the R-2 we can calculate the diameter and height. 𝑑2 𝑉 =𝜋∗ ∗ℎ 4 1.06 ∗ 4 = 𝑑2 ∗ ℎ 𝜋 .8 ∗4 = 𝑑3 𝜋 ∗ 1.5 . 7 = 𝑑3 𝑑 ≈ 1.06 𝑚 ℎ ≈ 1.6 𝑚 6.1.1 Reactor Selection Following are the reasons for choosing CSTR for our project. Liquid phase reaction. Provides optimal mixing. The reactors can be operated at temperatures between -6.66 and 232 °C and at pressures up to 7 atm. Relatively cheap to construct. Also, relatively easy to clean and maintain. 54 Ease of control of temperature in each stage, since each operates in a stationary state; heat transfer surface for this can be easily provided hence it is relatively easy to maintain good temperature control with a CSTR. Can be readily adapted for automatic control in general, allowing fast response to changes in operating conditions (e.g., feed rate and concentration). With efficient stirring and viscosity that is not too high, the model behavior can be closely approached in practice to obtain predictable performance. 6.1.2 Rate Constants Sourced from [10] the rate constants are as such. Rate Constants (mole/dm^3*seconds) Value k1 .049 k2 .102 k3 .218 k4 1.280 k5 .239 k6 .007 k7 7.84e-05 k8 1.58e-05 55 Since ours is a well-mixed vessel as stated per our primary source. We need to have a stirrer involved which basically means that there is an impeller that needs be designed. 56 6.1.3 Reactor Impeller It is quite common practice to have vessels with some form of mixing apparatus, it I commonly referred to as an agitator. Especially in the case of a CSTR mixing plays an important role as the constituents are considered to be well mixed. The basis of this assumption is that the mixing is strong enough to provide enough mass transfer. Agitators are chosen predominantly on the basis of reactor volumes and fluid properties mainly the viscosity. For the selection of the reactor impeller we need to know about the reactor volume and the viscosity of the fluid. To calculate the volume of the reactor we simply need to use the provided ratio of impeller diameter to the rector diameter. This ratio is given in the volume 6. [11] 6.1.4 Specifications Sheet Parameter Value Units R-1 Volume 6.3 𝒎𝟑 R-2 Volume 1.4 𝒎𝟑 R-1 Diameter 1.7 𝒎 57 R-1 Height 2.6 𝒎 R-2 Diameter 1 𝒎 R-2 Height 1.6 𝒎 Impeller Type Turbine Dimensionless R-1 Impeller Dia. 1.06 𝒎 R-2 Impeller Dia. .6 𝒎 6.1.5 Pressure Drop In liquid-phase reactions, the concentration of reactants is insignificantly affected by even relatively large changes in the total pressure. Consequently, we can totally ignore the effect of pressure drop on the rate of reaction when sizing liquid phase chemical reactors. However, in gas-phase reactions, the concentration of the reacting species is proportional to the total pressure and consequently, proper accounting for the effects of pressure drop on the reaction system can, in many instances, be a key factor in the success or failure of the reactor operation. 6.2 Heat Exchanger Design A heat exchanger is a device built for efficient heat transfer from one fluid to another, whether a physical barrier separates the fluids so that they never mix, or the fluids are directly contacted. It is used for heating of one fluid while cooling the other. Heat transfer equipment is defined by the function it fulfils in a process. Exchangers recover heat between two process streams. 6.2.1 Types with respect to Structure Some major types are: Double pipe heat exchanger. Shell and tube heat exchanger. Compact heat exchanger. 58 Double pipe consists of two concentrically arranged pipes or tubes, with one fluid flowing in the inner pipe and the other in the annulus between the pipes. The term double pipe refers to a heat exchanger consisting of a pipe within a pipe, usually of a straight- le g construction with no bends. Hairpin heat exchangers consist of two shell assemblies housing a common set of tubes and interconnected by a return-bend cover referred to as the bonnet. 6.2.2 Principal Parts Two sets of concentric pipes which constitutes; i. Inner pipe. Annulu ii. Outer pipe. s iii. Annulus. Inner pipe Connecting tees. Return head. Return bend. Packing glands. 59 6.2.3 Working Principle of Double Pipe Heat Exchanger The basic working principle of the heat exchanger is based on the law of conservation of heat i.e. As by law of nature heat tends to flow from higher potential to lower potential. It tends to equalize the temperature of both streams. But physical barrier of good conductor prevents the both streams from physical mixing and allows only heat to flow from one to other. 6.2.4 HEAT TRANSFER MODES Conduction Convection Radiation 6.2.5 Types of Double Pipe Heat Exchanger Double pipe exchangers are divided into two major types: Single-tube The Single-tube type consists of a single tube or pipe, either finned or bare, inside a shell. Multi-tube The Multi-tube type consists of several tubes, either finned or bare, inside a shell. 6.2.6 Double Pipe Heat Exchangers Advantages The use of longitudinal finned tubes will result in a compact heat exchanger for shell side fluids having a low heat transfer coefficient. Counter current flow will result in lower surface area requirements for 60 services having a temperature cross. Potential need for expansion joint is eliminated due to U-tube construction. Shortened delivery times can result from the use of stock components that can be assembled into standard sections. Modular design allows for the addition of sections at a later time or the rearrangement of sections for new services. Simple construction leads to ease of cleaning inspection and tube element. Disadvantages Hairpin sections are specially designed units which are normally not built to any industry standard other than ASME Code. However, TEMA tolerances are normally incorporated wherever applicable. Multiple hairpin sections are not always economically competitive with a single shell and tube heat exchanger. Proprietary closure design requires special gaskets. 6.2.7 Operation of Double Pipe Heat Exchanger Double pipe exchangers are usually assembled in 12-, 15-, or 20-ft effective lengths (the distance in each leg over which heat transfer occurs). When hairpins are employed in excess of 20ft, the inner pipe tends to sag and touch the outer pipe causing a poor flow distribution in the annulus. The best-known use of the hairpin is its operation in true counter current flow which yields the most efficient design for processes that have a close temperature approach or temperature cross. However, maintaining counter current flow in a tubular heat exchanger usually implies one tube pass for each shell pass. 61 The double-pipe exchanger is very flexible: vaporization, condensation, or single-phase convection can be carried out in either channel. The exchanger can be designed for very high pressures or temperatures if required. By proper selection of diameters and flow arrangements, a wide variety of flow rates can be handled. Design Calculation The purpose of this equipment is to heat the waste vegetable oil to the required temperature. 6.2.8 Heat Exchanger Design Assumed Calculations: 𝑄 A= 𝑈 ∗ ∆𝑇 By Assuming U = 300 W/m2 O C Q = 90481300 J/Kg (25133 Watt) A = 3.055 m2 As our area is not much big so we will use Double Pipe Heat Exchanger. 𝑄 m= 𝐶𝑝 ∗ ∆𝑇 m = 429.95 Kg/hr Pipe Side (Hot Water) Inlet temp = 90 o C Outlet temp = 50 o C Mass flow rate of hot water = 947.899 lb/hr Annulus side (WVO) Inlet temp = 25o C 62 Outlet tem = 60o C Mass flow rate of oil = 1217.44 Kg/hr Pipe Dimensions We are using 20ft length of the pipe. If the length of the pipe will be greater than 20-feet, the inner pipe tends to sag and it will touch the outer pipe and causes a poor flow distribution in the annulus. D2 = 0.0525 m D1 = 0.0420 m D = 0.0350 m Calculation of LMTD ∆𝑇1 − ∆𝑇2 LMTD = ∆𝑇1 ln(∆𝑇2) LMTD = 11.18 °C PHYSICAL PROPERTIES PHYSICAL PROPRTIES INNER PIPE ANNULUS Hot Water WVO Viscosity µ (Cp) 0.014 0.357 Thermal Conductivity (k)(W/m.K) 0.636 0.243 Heat capacity(Cp) (KJ/Kg.°C) 0.221 3.818 Density ρ(kg/m3 ) 965 908 63 Annulus Side (WVO) D 2 = 0.0525 m D 1 = 0.0420 m aa = 3.14(D 2 2- D1 2 )/4 aa = 0.00076 m2 Equivalent Diameter Deq = (D2 2- D1 2 )/ D 1 Deq = 0.023 m Mass Velocity Ga = W/ aa Ga = 1586494.5 Kg/hr.m2 Reynolds Number Re = DeGa/ µ Re = 28657.8558 L/D = 262.4 Jh = 100 Pr = Cp µ/k Pr = 5.593063265 ho = 1853.26 W/m2 .OC Inner pipe (Hot Water) D = 0.0350 m ap = 0.00096 m2 64 Gp = W/ ap Gp = 445005.07 Kg/hr.m2 Rep = DG p / µ Rep = 11706.02989 L/D = 175 Jh = 60 Pr = Cp µ/k Pr = 0.129183469 hi = 97.72362084 W/m2 .OC hio = 81.24011853 Uc = hio *ho /hio +ho Uc = 369.12 W/m2 .OC 1/UD = 1/Uc + Rd (Rd is assume as 0.002 hr.ft2 .OF/Btu) UD = 326.62 W/m2 .OC Required Area A = Q/UD∆T A = 2.80 m2 Required Length Required Length = Surface Area/0.435Ft2 L = 21.14 m Actual Length L = 24.38 m Hairpin = 2 Actual Area will be: 65 Form table for 1.25- in we have 0.435 Ft2 of external surface per foot length. Actual Length * 0.435 Actual Area (A) 3.23 m2 This area is close to the assumed calculation area (3.05 m2 ) The surface apply will actually be UD = 328.771447 W/m2 OC The overall heat transfer coefficient is close to the assumed calculation Rd = 0.001897 m2 .OC/W Pressure Drop (Annulus) 1) De’ = (D2 – D1 ) De’ = 0.01 m Re’a = De’ Ga/µ Re’a = 12520.00405 f = 0.0035 + 0.246 /( Re’a)0.42 f = 0.0085 ρ = 56.75 2) ∆Fa = 4f Ga2 L/2g ρ2 De’ ∆Fa = 0.94 m. V = G/3600 ρ V = 1.590 FPS 3) Ft = 3(V2 /2g’) Ft = 0.117 66 4) ∆Pa = 1.2676 Psi Inner Pipe 1) Rep = 35030 f = 0.0035 + 0.246 /( Rep )0.42 f = 0.00675791 ρ = 60.31 2) ∆Fp = 4f Ga2 L/2g ρ2 De’ ∆Fp 0.015 m. ∆Pp = 1.052 Psi 6.2.9 Mechanical Design Selection of material Inner pipe material : Carbon steel (approximately 0.30–0.59% carbon content) Whose density is = 7877.61 kg/m3 (table 2-118 Perry chemical Engineering 8th edition) The permissible stress is ft = 0.788 kg/m2 % Elongation = 28 Characteristics of material available in a wide range of standard forms and sizes good tensile strength and ductility not resistant to corrosion 67 6.3 Flash Tank 1. Final purification of biodiesel is achieved in the flash drum that operates under vacuum (5 kPa). 2. Modelling of the flash tank was performed on Aspen Hysys. Material balance & construction sheet is given in Appendix B. 3. The feed rates were taken from the material balance. 4. Pressure was provided in our primary source. 5. Temperature was set around the boiling point of water. 6. Components present in too low an amount were neglected for the ease. 7. Multiple fluid packages were used which gave similar results. These include NRTL Ideal. Figure 6.3.1 Flash Tank Operating Conditions of the flash tank are given as under. Flash Tank Conditions Liquid Residence Time 720 𝒔𝒆𝒄𝒐𝒏𝒅𝒔 Operating Pressure 5 Kilo Pascals Package Used NRTL Ideal Dimensionless Valve IN Conditions Temperature 55 °C 68 Operating Pressure 101.3 kPa Total Feed (Molar Flow) 5 kmol/h Mole Fraction (Triolein) .003 Dimensionless Mole Fraction (Methanol) .0548 Dimensionless Mole Fraction (H2O) .1350 Dimensionless Mole Fraction (FAME) .1350 Dimensionless Flash IN Conditions Temperature 53.32 °C Operating Pressure 5 kPa Total Feed (Molar Flow) 5 kmol/h Mole Fraction (Triolein) .003 Dimensionless Mole Fraction (Methanol) .0548 Dimensionless Mole Fraction (H2O) .1350 Dimensionless Mole Fraction (FAME) .1350 Dimensionless Flash UP Conditions Temperature 110 °C Operating Pressure 5 kPa Total Feed (Molar Flow) .8359 kmol/h Mole Fraction (Triolein) 0 Dimensionless Mole Fraction (Methanol) .3118 Dimensionless Mole Fraction (H2O) .6881 Dimensionless Mole Fraction (FAME) 0 Dimensionless Flash DOWN Conditions Temperature 110 °C Operating Pressure 5 kPa Total Feed (Molar Flow) .4.164 kmol/h Mole Fraction (Triolein) 0.0004 Dimensionless Mole Fraction (Methanol) .0032 Dimensionless Mole Fraction (H2O) .0240 Dimensionless Mole Fraction (FAME) .9725 Dimensionless 69 Table 6.3-1 Streams from Flash Tank Design Specifications of the flash tank are given as under. Parameter Value Units Diameter .609 𝒎 Total Length (Height) 3.353 𝒎 L/D Ratio 5 Dimensionless Material Type Carbon Steel Dimensionless Shell Thickness 6.350 𝒎𝒎 Corrosion Thickness 3.175 𝒎𝒎 Table 6.3-2 Design Specifications of Flash Tank 6.4 Distillation Column Design (D-1) In industry, it is common practice to separate a liquid mixture by distillation of the components, which have lower boiling points when they are in pure condition from those having higher boiling points. This process is accomplished by partial vaporizat ion and subsequent condensation 6.4.1 Choice between Plate and Packed Column Vapor liquid mass transfer operation may be carried out either in plate column or packed column. These two types of operations are quite different. A selection scheme considering the factors under four headings. Factors that depend upon the system i.e. scale, foaming, fouling factors, corrosive systems, heat evolution, pressure drop, liquid holdup. Factors that depend upon the fluid flow moment. Factors that depends upon the physical characteristics of the column and its internals i.e. maintenance, weight, side stream, size and cost. Factors that depend upon mode of operation i.e. batch distillation, continuous distillation, turndown, and intermittent distillation. 70 The relative merits of plate over packed column are as follows: Plate column are designed to handle wide range of liquid flow rates without flooding. If a system contains solid contents, it will be handled in plate column, because solid will accumulate in the voids, coating the packing materials and making it ineffective. Dispersion difficulties are handled in plate column when flow rate of liquid are low as compared to gases. For large column heights, weight of the packed column is more than plate column. If periodic cleaning is required, man holes will be provided for clea ning. In packed columns packing must be removed before cleaning. For non-foaming systems, the plate column is preferred. Design information for plate column are more readily available and more reliable than that for packed column. Inter stage cooling can be provide to remove heat of reaction or solution in plate column. When temperature change is involved, packing may be damaged. Plates are mostly used for large diameter more than 0.6 m For this particular process, “Methanol, DME, Water” plate column is selected because: System is non-foaming. Temperature is high. Diameter is greater than 0.6 meter. 6.4.2 Choice of Plate Type There are three main plate types, the bubble cap, sieve plates, ballast or valve plates. Sieve plate is selected because: They are lighter in weight and less expensive. It is easier and cheaper to install. Pressure drop is low as compared to bubble cap trays. Peak efficiency is generally high. Maintenance cost is reduced due to the ease of cleaning. 6.4.3 Design Steps for A Distillation Column Calculation of Minimum number of plates Calculation of optimum reflux ratio 71 Calculation of theoretical number of stages Calculation of actual number of stages Calculation of diameter of the column Calculation of the height of the column Design Calculations: Components mass % Feed Top Bottom Glycerol 0.08319 0.00 0.4401 Methanol 0.102 0.08416 0.00 Water 0.814 0.9158 0.5598 Stream Temperature Flow rate Pressure ℃ Kg/hr psi Feed 100 1485.35 49.3128 (3.35 atm) Top 98.1 1334.78 14.6488 (1atm) Bottom 250.3 150.71 15.95 (1.019atm) Pressure of feed = P = 49.31 psia Temperature of feed = T = 100 oC = 373K Boiling point of water = Tw = 101.1 °C = 374.1 K Boiling point of Methanol= Tm = 64.8 °C = 337.8 K Heat of Vaporization of methanol = ΔHvap = 35200 J/mol Relative Volatility Calculation −ΔHvapL 1 1 α =exp [ (T − T )] R w m 72 “integratedClausius-Clapeyron equation” −35200 1 1 α =exp [ (374 .1 − 337.8 )] 8.314 α = 3.37 6.4.3.1.1.1.1.1.1 Reflux Ratio (RD) Colburn’s method for minimum reflux 1 x 1−x RM = α−1 [ xdA − α ( 1−xdb )] fA fb 1 0.08416 1−0.00 RM = [ − 3.37 ( )] 3.37−1 0.102 1−0.08319 RM = 1.5 R = 1.2 RM R = 1.2 x 1.5 R = 1.8 73 Minimum Number of Stages Minimum number of Stages can be found Fenske relation. 6.4.3.1.1.1.1.1.2 where: N is the minimum number of theoretical plates required at total reflux (of which the reboiler is one), Xd is the mole fraction of more volatile component in the overhead distillate, Xb is the mole fraction of more volatile component in the bottoms, 𝜶𝒂𝒗𝒈 is the average relative volatility of the more volatile component to the less volatile component N min = 4 (reboiler is excluded) Plate Efficiency Using O’Connell relation Eo = 51 − 32.5 log 10 (μa αa ) µa = Molar average liquid viscosity mNs/m2 = 0.1553 mNs/m2 αa = average relative volatility = 3.37 Eo = 50.3(αa µa)-0.226 Eo = 68.226 % Theoretical no. of Plates: Gilliland related the number of equilibrium stages and the minimum reflux ratio and the no. of equilibrium stages with a plot that was transformed by Eduljee into the relation: 74 𝑵 − 𝑵𝒎𝒊𝒏 𝑹 − 𝑹𝒎𝒊𝒏 𝟎.𝟓𝟔𝟔 = 𝟎. 𝟕𝟓[ 𝟏 − ( ) ] 𝑵+𝟏 𝑹+𝟏 6.4.4 From which the theoretical no. of stages to be 7 (calculated by aspen see appendix C) 6.4.5 Feed plate location Using Kirkbride’s relation NR 0.0831 0.00075 2 1328.75 𝑙𝑜𝑔 = 0.206log [( )( ) ] NS 0.102 0.00662 151 NR = 0.611 NS R = 1.8, N=7 N r+N S = 6 NS = 6 - Nr N s = 7 - 0.61N s Ns = 4.3 Feed plate = 4 6.4.6 Column Diameter 𝝆𝑳 −𝝆𝒗 1⁄2 𝐮𝐕 = (−𝟎. 𝟏𝟕𝟏𝒍𝟐𝒕 + 𝟎. 𝟐𝟕𝒍𝒕 − 𝟎. 𝟎𝟒𝟕)[ ] 𝝆𝒗 75 Where uv = maximum allowable vapour velocity based on the gross total column cross- sectional area. Lt = plate spacing, m, (range 0.5 to 1.5) The column diameter, Dc can be calculated by 𝟒𝐯𝐰 𝐃𝐜 = √ 𝛑𝛒𝐯 𝒖𝒗 Where as Vw = is maximum vapour rate, m3 /s 𝑫𝒄 = 𝟎. 𝟗𝟏𝟒𝟒𝒎 Provisional Plate Design Column diameter = 0.914 m Column Area A 2 d 4 Side DC Top Width = 120.7mm Side DC Btm Width =120.7mm Side DC Top Length = 0.6189m Side DC Btm Length = 0.6189m Net area An = Ac – Ad = 0.6567m2 Active area Aa = Ac – 2Ad = 0.5542m2 Hole area Ah take 10% Aa = 5.584 × 10-2 m2 Pressure drop per plate Assume 100 mm water pressure drop per plate, Columnpressuredrop = 100 ∗ 10−3 ∗ 1000 ∗ 9.81 ∗ 18 76 = 17658 Pa TopPressure = 14 Psia Estimatedbottompressure = 15.5 psia Total Pressure Drop ht = hd + (hw + how) + hr Max delta P( ht of liq) = 3.871kpa ( aspen, see appendix) Height of Column No. of plates = 7 Tray spacing = 0.906 m Distance between 51 plates = 0.906 7 = 3.9 m Top clearance = 0.5 m Bottom clearance = 0.5 m Tray thickness = 575.1mm/plate Total height of column = 4.267m (aspen, see appendix) 77 SPECIFICATION SHEET OF DISTILLATION COLUMN Identification Item Distillation Column Item # T-501 Type Sieve Tray Function The separation of methanol from glycerol Design data No. of trays 7 Operating Pressure Slightly above than atm Operating Temperature 101 °C Tray spacing 079069 m Tray thickness 3.175 mm Height 4.267 m Diameter 0.9144 m Max Flooding 59% Total Weir Length 618.9mm Max weir load 12.63m3 /h.m DC Clearance 38.10mm Reflux ratio 1.8 Sieve hole Diameter 6.350mm Sieve hole Area 5.58 ×10-2 m2 No. of Holes(estimated) 1763 Liquid density 959.119Kg/m3 Vapor density 0.5881 Kg/m3 Material of Construction Stainless steel 18Cr/8Ni Ti stabilized (aspen, see appendix ) 78 6.5 DISTILLATION COLUMN DESIGN Feed = 1367.5263 Kg/hr = 71.3039 K.mole/hr Components Kg/hr Mol. Wt K.mole Mole% wt% CH3 OH 192.1234601 32 6.0038 8.42001 H2 O 1175.402976 18 65.10036 91.2998 About (8.42001+ 91.2998) = 99.71%) of the feed consists of methanol and water. Thus binary distillation can be assumed. Distillate = 192.1234601 Kg/hr = 6.0038 K.mole/hr Component Kg/hr Mol. Wt k.mole Mol. Wt wt% CH3 OH 192.1234601 32 5.854 99.99 H2 O 0.26964 18 0.1498 0.01 Bottom = 1175.402976 Kg/hr = 65.10036 K.mole Component Kg/hr Mol. Wt k.mole Mol. Wt wt% CH3 OH 0.02688 32 0.00084 0.01 H2 O 1175.402976 18 65.10036 99.9 We get Xf = 0.084 Xd = 0.9999 Xw = 0.01 79 (Equlibrium data from the compilation by Gmehling, J. and Onken, U. 1977. Vapor- Liquid Equilibrium Data Collection, Dechema, Frankfurt, Germany, vol. 1, p. 60.) from Chemical Engineering Design and Analysis: An Introduction T. M. Duncan and J. A. Reimer, Cambridge University Press, 1998. Equilibrium Data for Methanol – Water is given as follows Temp Temp x y y_calc Diagonal (oF) (oC) (mole (mole f) f) 212 100 0 0 0 0 209.12 98.4 0.012 0.068 0.164522 0.012 206.42 96.9 0.02 0.121 0.203265 0.02 204.44 95.8 0.026 0.159 0.226586 0.026 203.18 95.1 0.033 0.188 0.250089 0.033 201.38 94.1 0.036 0.215 0.259262 0.036 197.96 92.2 0.053 0.275 0.304281 0.053 194 90 0.074 0.356 0.349368 0.074 191.48 88.6 0.087 0.395 0.373577 0.087 188.42 86.9 0.108 0.44 0.408558 0.108 185.72 85.4 0.129 0.488 0.439742 0.129 182.12 83.4 0.164 0.537 0.485687 0.164 179.6 82 0.191 0.572 0.517318 0.191 174.38 79.1 0.268 0.648 0.595187 0.268 172.58 78.1 0.294 0.666 0.618443 0.294 169.7 76.5 0.352 0.704 0.666301 0.352 167.54 75.3 0.402 0.734 0.703963 0.402 165.56 74.2 0.454 0.76 0.740321 0.454 163.76 73.2 0.502 0.785 0.771772 0.502 161.6 72 0.563 0.812 0.809295 0.563 159.62 70.9 0.624 0.835 0.844504 0.624 156.56 69.2 0.717 0.877 0.894496 0.717 154.58 68.1 0.79 0.91 0.931129 0.79 152.96 67.2 0.843 0.93 0.956498 0.843 152.42 66.9 0.857 0.939 0.963042 0.857 150.26 65.7 0.938 0.971 0.999729 0.938 149 65 1 1 1.026572 1 Where X = Mole fracti on of M.V.C in Liquid phase Y = Mole fraction of M.V.C in Vapor phase 80 VLE for MeOH/H2O system Equilibrium Diagonal 1 0.9 0.8 0.7 y (m ole frac MeOH) 0.6 0.5 0.4 0.3 0.2 0.1 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 x (m ole frac MeOH) Now after drawing equilibrium curve (11.49) Coulson and Richardson Vol.2 𝑥𝑑− 𝑦 𝑓 Minimum Reflux Ratio = R m = 𝑦 𝑓 −𝑥 𝑓 = (0.9999 – 0.391)/(0.391 – 0.084)= 1.98 Reflux Ratio = R = 1.5* R m = 1.5 * 1.98=2.97 6.5.1 Top Operating Line F = 71.23kmol/hr D = 5.854 kmol/hr W = 71.05 kmol/hr D = 5.854Kmol/hr, XD = 0.99, xf =0.084 Ln = 17.79 Kmol/hr Vn = 23.456 Kmol/hr 𝐋𝐧 𝐃 yn = 𝐱 𝐧+𝟏 + 𝐱𝐃 𝐕𝐧 𝐕𝐧 17.79 5.864×0.999 yn = xn+1 + 23.456 23.456 yn = 0.75 xn+1 + 0.249 81 6.5.2 Bottom Operating Line F = 71.23 Kmol/hr, xw = 0.001, Lm = 89.09 Kmol/hr Vm = 23.655 Kmol/hr 𝐋𝐦 𝐁 Ym = 𝐱 𝐦+𝟏 − 𝐱𝐖 𝐕𝐦 𝐕𝐦 89.09 65.435×0.001 yn = xn+1 − 23.65 23.655 ym = 3.8012xm+1 −0.00276 The Points Of Top Operating Line 𝐃 (0 , 𝐱 𝐃)) ; (Xf , Xd) 𝐕𝐧 (0 , 0.249) ; (0.084 , 0.999) The Bottom Operating Line Points 𝐁 (0 , 𝐱 𝐰 ) ; (Xf , Xw) 𝑽𝒎 (0 ,0.00276) ; (0.084 , 0.01) 82 6.5.3 Ideal no of trays is 8 6.5.4 Efficiency And Total Number Of Real Stages Coulson and Richardson’s volume 6( page549) Eo = 51 – 32.5 Log μ a, aa Where Eo = Overall column efficiency percent. Average temperature of column = 87.5 o C = 189.5 o F (Kaye & Laby, Engineers Edge, RoyMech and Dynesonline) Viscosity of Methanol = 0.257 cp Viscosity of Water = 0.325 cp μ = (0.7108 * 0.257) + (0.2843 * 0.325) = 0.257 cp Eo = 51 – 32.5 Log (0.257) = 70 % 83 Actual number of trays in column = 8 / 0.7 = 12 Feed should be entered on plate # 6 Maximum vapor flow rate in rectifying section = Vn = 23.456 kg mole/hr Maximum liquid flow rate in rectifying section = Ln = 17.592 kg mole/hr Maximum vapor flow rate in stripping section = Vm = 23.655kg mole/hr Maximum liquid flow rate in stripping section = Lm = 89.09kg mole/hr Plate spacing initial estimate = T_S= 0.5m = 18in Calculation of column diameter based on flooding velocity Calculate FLV = liquid vapor flow factor LW V FW VW L LW = liquid mass flow rate kg/s VW = vapor mass flow rate, kg/s 17.592 1.15 FWT OP =23.655 √ 750 =0.039 89 .09 .5 FWbotom =23.655 √962 =0.022 From figure 11.27 Coulson and Richardson vol.6) t 1 = a constant obtained from fig 11.27 84 K1 Top = 0.08 K1 Bottom = 0.085 Flooding Velocity: U f = flooding velocity L V 0.2 U f K1 V 20 962 0.5 58 0.2 U f bottom 0.085 0.5 20 = 4.3 m/s 750 1.15 19 0.2 U f Top 0.08 1.15 20 = 2.17 m/s Based on 85% flooding velocity 6.5.5 Superficial Vapor Velocity Uˆ base 4.3 0.85 3.5 7 m/s Uˆ v,top 2.17 0.85 1.9 m/s Maximum volumetric Flow rate = V/ V Top = 0.573 m3 /sec Bottom = 1.147 m3 /sec 6.5.6 Net Area Required Maximum volume metric flow rate / superficial velocity Top = 0.5735/1.9 = 0.30m2 Bottom =- 1.471/3.57 = 0.41m2 85 As first trial take down comer area as 12% of the total. Column cross sectional area Base = 0.41/0.88 = 0.46 m2 Top = 0.30/0.88 = 0.34 m2 6.5.7 Column Diameter Diameter =√ (4 × Area /0.88 ) 2 Area = d 4 3.14(00.34) 2 3.14(0.46) 2 Top= 4 , = 0.090 m Bottom = 4 = 0.166m Diameter top =0.362m diameter bottom = 0.490 m 6.5.8 Height of the column : Hc=1.2 *T_S*(N-1) taken from paper 1.2(0.5)(16-1)=9 m Provisional Plate Design Column diameter (base) = 0.4827 m 2 Column Area Ac d 4 Ac = 0.182 m2 Downcomer area Ad = 0.12(0.182) = 0.021m2 Net area An = Ac – Ad = 0.182– 0.021 = 0.161m2 Active area Aa = Ac – 2Ad = 0.182 – 2(0.021) 86 = 0.14 m2 Hole area Ah take 10% Aa = 0.1 × 14 = 0.014m2 Weir length Ad / Ac = 0.021 / 0.182 = 0.115 (From figure 11.31 vol.6) lw / dc = 0.76 lw 1.6 0.76 lw = 1.22 m Take weir height , hw = 50 mm Hole diameter, dh = 5 mm Plate thickness = 5 mm Maximum liquid rate Lm’ = 89.09× 18 / 3600 = 0.4454 kg/sec Minimum liquid rate at 70% turn down 0.7*0.4454 = 0.31178s kg/sec 𝑜.4454 Maximum h0w =750( )2/3 =3.9313 mm liquid 962∗1.22 𝑜 .31174 Minimum how =750(962 ∗1.22 )2/3 =3.096 mm liquid At minimum hw + how = 50 + 3.096 = 53.096 mm liquid From fig 11.30, Coulson and Richardson Vol.6 K2 = 30.4 87 K 0.925 .4 d h U m in 2 v 1 / 2 30 .4 0.925 .4 5 U m in 0.51 / 2 = 14.2 m/s min. vapour rate Actual minimum vapour velocity Ah 0.70 6.5 0.155 = 28.1 m/s So minimum vapor rate will be well above the weep point. 6.5.9 Plate Pressure Drop Dry Plate Drop Max. Vapour velocity through holes Û h = Volumetric Flow Rate / Hole Area 1.417 Uh =0.155 =9.14 m/s Fom fig. 11.43 Coulson and Richardson Vol.6 for plate thickness/hole dia = 5/5 = 1 Ah Ah .155 and 0.1 Ap Aa 1.55 Co = 0.84 From Eq.11.88 Coulson vol.6 88 2 Uˆ hd 51 h V Co L 9.14 0.5 hd=51[0.84 ]2 962 =3.13 mm liquid 6.5.10 Residual Head 12 .5 10 3 hr 12 .9mm liquid mm liquid 962 Total Pressure Drop ht = hd + (hw + how) + hr Total pressure drop = 3.12+ (50 + 3.096) + 12.9 ht = 69.116 mm liquid 6.5.11 Check Residence Time Ad hbc L tr Lwd 0.23 0.218 962 tr 2.48 = 12.8 sec > 3 sec. so, result is satisfactory 6.5.12 Check Entrainment Uv = Maximum Volumetric Flow Rate of vapors/Net Area UV = 1.147/ 1.78 = 0.644 m/s 89 No of Holes Area of one hole 1.964 105 Number of Holes = Hole Area / Area of one hole 0.155 No. of holes = 6620 1.964 105 Specification Sheet Equipment Distillation Column Actual No.of Trays 12 Efficiency 70 % R 2.97 Diameter top 0.362 m Bottom diameter 0.49 m Height 9m No. of holes 6620 Superficial velocity 80 % of flooding velocity Pressure Drop 69.116 mm liquid 90 Tray Thickness 5mm Tray spacing 0.5 m 6.6 Mixing Tank Design 6.6.1 Volume Calculation we can calculate volume of tank by this formula 𝑄 v= τR 0.8 residence time= τR = 1 hr., volumetric flow rate Q=2.86862 m3 3 v = 3.582 m now we have 𝜋 V= D2L (1) 4 D= internal diameter L=height or length suppose 𝐿 =3 0r L=3D 𝐷 putting values of L in equation…. (1) 𝜋 v=4 D2 (3D) 3.14 3.582 = 3D3 4 3.582(4)=9.42 D3 D=1.521 m L=3(1.521) L = 4.563 m 6.6.2 Thickness Pressure in tank =1 atm 91 Pressure in guage = 1-1=0 𝑁 𝑁 Design pressure=Pi=0+10% =0.1 = 0.01 𝑚𝑚2 𝑚2 Material of construction= strainless steel 18cr/8Ni Design temperature = 55 °C 𝑁 Typical design stress at this temperature =f =160 𝑚𝑚2 (from table 13.2) Joint factor = 1 , diameter of tank Di = 1.521 m Thickness for cylindrical shell ‘e’ 𝑃𝑖 𝐷𝑖 e=2 𝐽 𝑓−𝑃𝑖 e=0.0000475 mm Corrosion allowance = 2mm e=2.0000475 mm 2.2 Thickness for head section Most standard ellipsoidal heads are manufactured with a major and minor axis ratio of 2 : 1. For this ratio, the following equation can be used to calculate the minimum thickness required: 𝑃𝑖 𝐷𝑖 e= 2 𝐽 𝑓−0.2𝑃𝑖 𝑜.𝑜1(1.521) e=2(1)(160)−0.2(0.01) = 0.0000475 m Add corrosion allowance = 2mm e = 2.0000475 mm 6.6.3 choice of closure :- torispherical heads are used when internal pressure 0-15 bar Pi Rc Cs e = 2𝑓𝐽+𝑃𝑖 (𝐶𝑠−0.2) where Cs = stress concentration factor for torispherical head 1 𝑅𝑐 cs= (3+√ ) 4 𝑅𝑘 92 Rc =crown radius Rk = knuckle radius (The ratio of the knuckle to crown radii should not be less than 0.06, to avoid buckling; and the crown radius should not be greater than the diameter of the cylindrical section. For formed heads (no joints in the head) the joint factor J is taken as 1.0) Rc =Rk (0.06) equal to dia of vessel RC= (1.52)(0.06) =0.0912 Cs=0.8075 Now put the values in the main equation .. 0.01(0.0912)(0.8075) e= =0.0000023 2(160)(1) +0.01(0.0912−0.2) add corrosion allowance =2 mm e = 2.0000023 mm 6.6.4 Impeller design Type = pitched-blade turbine impeller 93 It is used when fluid is low viscous it gives radial as well as axial mixing . Standard properties for impeller D a = impeller diameter D t = tank diameter =1.521 m Impeller dia 𝑫𝒂 𝟏 = 𝑫𝒕 𝟑 1.521 Da = =0.507 m 3 94 Depth of liquid 𝐻 =1 𝐷𝑡 H=1.521 Width of impeller blades 𝑤 1 =5 𝐷𝑎 𝐷 W= 5𝑎 = 0.104 m Length of impeller 𝐿 1 = 𝐷𝑎 4 𝐷𝑎 0.507 L= = =0.1267 m 4 4 Clearance 𝐸 1 = 𝐷𝑡 3 1.521 =0.507 m 3 Power calculation :- In impeller design rpm is taken as 20-150.For low viscous fluid it will be 90rpm. 𝐷2 𝑁𝑝 Reynold's number= μ Reynold's number >10,000 so Np=KT Np=Power number, KT=Constant for turbulent flow For pitched blade KT=1.27 𝑘𝑤 P = 0.04-0.10 𝑚3 D=0.507 ,N=90 rpm 0r 1.5 rps , 𝐤𝐠 ρ= 1060.8 𝐦𝟑 𝑃 Np=𝐷5 𝑁3 𝛒 Power for impeller is given by, P=kT N3 Da5 P=152 W = 0.152 kW 95 6.6.5 Design Data Parameter Value Units Volume 3.582 𝒎𝟑 Internal diameter 1.512 𝒎 Height 4.563 𝒎 𝑁 Total pressure .01 𝑚𝑚2 Operating temperature 55 °C Wall Thickness 2 𝒎𝒎 Closure Torri Spherical Dimensionless Impeller Type Pitch Blade Turbine Dimensionless Power for Impeller .152 kW 96 Chapter 7 INSTRUMENTATION & PROCESS CONTROL 7.1 Introduction Process control is an inherent requirement for any process industry in one way or the other. Instrumentation implement in the form of actual hardware. In our project, we are to propose the elements of instrumentation that will render control to our process. We have done that by applying process control on the common types of equipment in our process such as the reactor, heat exchanger and the distillation column. 7.1.1 Requirements of Control During the operation of chemical plant, the control system must satisfy several requirements and it must accomplish certain objectives, these are as following. 7.1.2 Safety The safe operation of chemical process is a primary requirement for the wellbeing of the people in the plant, thus the operating pressure, temperature and concentration of chemical should always be within allowable limits. 7.1.3 Product Specification To achieve the desired quantity and quality of our product we must put in place some appropriate instrumentation. This will ensure proper production. 7.1.4 Environmental Regulation Various laws may specify that temperatures, concentration of chemicals and flowrates of the effluents from a plant must be within certain limits. 7.1.5 Operational Constraints The various types of equipment’s used in a chemical plant have constraints inherent to their operations. 97 7.1.6 Economics The operation of a plant must conform with the market conditions, that is the availability of raw material and the demand of the final product. Furthermore, it should be as economical as possible in its utilization of raw materials, energy, capital and human labour. Thus, it is required that the operating conditions are controlled at given optimum levels of minimum operating costs and maximum profit. All the requirements above dictate the need for continuous monitoring of the operation of a chemical plant and external control to ensure the satisfaction of operational objectives. Generally, a control system satisfies the following 1. Suppressing the influence of external disturbances. 2. Ensuring the stability of chemical process. 3. Optimizing the performance of chemical process. 7.2 Reactors Measured Variable(s) 𝑭𝒐𝒊𝒍 , 𝑭𝑵𝒂𝑶𝑴𝒆 , 𝑻𝑹−𝟏 Manipulated Variable 𝐹𝑁𝑎𝑂𝑀𝑒 , 𝐹𝐶𝑜𝑜𝑙𝑖𝑛𝑔 𝑊𝑎𝑡𝑒𝑟 Controlled Variable 𝑇𝑅−1, 𝑭𝒐𝒊𝒍 /𝑭𝑵𝒂𝑶𝑴𝒆 Name of Control System Applied for Ratio Control Flow Control Name of Control System Applied for Cascade Control System Temperature Control Table 7.2-1 Measured, Control & Manipulated Variables for R-1 98 For the control of feeds into the CSTRs we use ratio control which divides the feed Figure 7.2.1 Reactor Control according to flowrate of the oil input into the CSTR. While for temperature control we use a cascade feedback control system. A cascade control system is one which uses temperature as a secondary measurement. We have to supply cooling water to the reactors in order to keep the reaction temperature around the optimum (60 °C). 7.3 Heat Exchanger The objective of this heat exchanger with this instrumentation is to keep the exit temperature of waste vegetable oil constant by manipulating the hot water flow. There are two principal disturbances (loads) that are measured for feed forward control: WVO flow rate and WVO inlet temperature. 99 Figure 7.3.1 Heat Exchanger Control 7.4 Distillation Column 100 Figure 7.4.1 Distillation Column Control 101 Chapter 8 COST ESTIMATION 8.1 Introduction Before the plant is put into production we must together some rough estimates of financia ls. The capital needed to supply the necessary plant facilities is called fixed capital investme nt while that for the operation of the plant is called the working principal and sum of two capitals is called total capital investment. An acceptable plant design must present a process that is capable of operating under conditions which will yield a profit. Since, Net profit total income-all expenses it is essential that chemical engineer be aware of the many different types of cost involved in manufacturing processes. Capital must be allocated for direct plant expenses; such as those for raw materials, labour, and equipment. Besides direct expenses, many other indirect expenses are incurred, and these must be included if a complete analysis of the total cost is to be obtained. Some examples of these indirect expenses are administrative salaries, product distribution costs and cost for interplant communication. Source for cost indices used is provided in Appendix F. 102 8.2 Equipment Cost Estimation 8.1.1 Reactor Cost Estimation For A CSTR Cylindrical Vessel We Have: 𝐶 = 𝐹𝑚 exp(2.631 + 1.3673(lnV) − .06309(𝑙𝑛𝑉 2 )) Parameter Value Units 𝑭𝒎 2.4 Dimensionless Volume 1644.06 𝑼𝑺 𝑮𝒂𝒍𝒍𝒐𝒏𝒔 Purchase Cost 26155 $ 𝑪𝒊𝒏𝒔𝒕𝒂𝒍𝒍𝒆𝒅 (∗ 𝟏. 𝟔) 41848 $ 𝑊ℎ𝑒𝑟𝑒 𝐼𝑛𝑑𝑒𝑥 𝐼𝑛 1985 = 333.3 𝑊ℎ𝑒𝑟𝑒 𝐼𝑛𝑑𝑒𝑥 𝐼𝑛 2016 = 668.1 668.1 𝐶𝑜𝑠𝑡 𝐼𝑛 2016 = 26155 ∗ = 52427.7 $ 333.3 8.1.2 Flash Tank Cost Estimation For A CSTR Cylindrical Vessel We Have: 𝐶 = 𝐹𝑚 𝐶𝑏 + 𝐶𝑎 Parameter Value Units 103 𝑭𝒎 1.7 Dimensionless Volume 34.55 𝑓𝑡 3 Purchase Cost 4562.86 $ 𝑪𝒊𝒏𝒔𝒕𝒂𝒍𝒍𝒆𝒅 (∗ 𝟏. 𝟓) 6844.30 $ 𝑊ℎ𝑒𝑟𝑒 𝐼𝑛𝑑𝑒𝑥 𝐼𝑛 1985 = 333.3 𝑊ℎ𝑒𝑟𝑒 𝐼𝑛𝑑𝑒𝑥 𝐼𝑛 2016 = 668.1 668.1 𝐶𝑜𝑠𝑡 𝐼𝑛 2016 = 4562.86 ∗ = 9146.2549 $ 333.3 8.1.3 Heat Exchanger Cost Estimation For Double Pipe Heat Exchanger: [12] 𝐶 = 900 ∗ 𝑓𝑚 ∗ 𝑓𝑝 ∗ 𝐴.18 Parameter Value Units 𝒇𝒎 1 Dimensionless 𝒇𝒑 1 Dimensionless Area 34.8 𝒇𝒕𝟐 Purchase Cost 1705 $ 𝑪𝒊𝒏𝒔𝒕𝒂𝒍𝒍𝒆𝒅 (∗ 𝟐. 𝟎) 3410 $ 104 𝑊ℎ𝑒𝑟𝑒 𝐼𝑛𝑑𝑒𝑥 𝐼𝑛 1985 = 333.3 𝑊ℎ𝑒𝑟𝑒 𝐼𝑛𝑑𝑒𝑥 𝐼𝑛 2016 = 650.9 650.9 𝐶𝑜𝑠𝑡 𝐼𝑛 2016 = 1705 ∗ = 3329.68 $ 333.3 8.1.4 Centrifuge Cost Estimation For Centrifuge: 𝐶 = 𝑎 +𝑏 ∗𝑊 Parameter Value Units 𝒂 98 Dimensionless 𝒃 5.06 Dimensionless W 1.344 𝒕𝒐𝒏𝒔/𝒉𝒓 Purchase Cost 104804.78 $ 𝑪𝒊𝒏𝒔𝒕𝒂𝒍𝒍𝒆𝒅 (∗ 𝟏. 𝟐) 125765.74 $ 𝑊ℎ𝑒𝑟𝑒 𝐼𝑛𝑑𝑒𝑥 𝐼𝑛 1985 = 333.3 𝑊ℎ𝑒𝑟𝑒 𝐼𝑛𝑑𝑒𝑥 𝐼𝑛 2016 = 668.1 668.1 𝐶𝑜𝑠𝑡 𝐼𝑛 2016 = 104804.78 ∗ = 210081.228 $ 333.3 105 8.1.5 Distillation Column Cost Estimation (D-1) For Distillation Column: 𝐶𝑡 = 𝑓1 ∗ 𝐶𝑏 + 𝑁𝑓2 𝑓3 𝑓4 𝐶𝑡 ∗ 𝐶𝑝1 𝐿 𝑇 𝐶𝑏 = exp(7.123 + .1478(𝑙𝑛𝑊 ) + .0248(𝑙𝑛𝑊 ) + .0158( )( 𝑏 ) 𝐷 𝑇𝑝 9020 < 𝑊 < 2470000, 2 < 𝐷 < 16 𝑓𝑡. 𝑡𝑟𝑎𝑦 𝑑𝑖𝑎𝑚𝑒𝑡𝑒𝑟 𝑁 = 𝑁𝑢𝑚𝑏𝑒𝑟 𝑂𝑓 𝑇𝑟𝑎𝑦𝑠 𝐶𝑝1 = 204.9𝐷 .6332 𝐿.8016 2 < 𝐷 < 24 57 < 𝐿 < 170 𝑓𝑡 Material 𝑭𝟏 𝑭𝟐 Stainless steel, 304 1.7 1.189+.05770D Stainless steel, 316 2.1 1.401+.07240D Carpenter (20CB-3) 3.2 1.525+.07880D Nickel-200 5.4 Monel-400 3.6 2.306+.1120D Inconel-600 3.9 lncoloy-825 3.7 Titanium 7.7 106 Tray Types 𝑭𝟑 Valve 1.00 Grid .80 Bubble Cap 1.59 Sieve .85 Parameter Value Units 𝑭𝟏 1.7 Dimensionless 𝑪𝒃 11540 $ 𝑭𝟐 1.27 Dimensionless 𝑭𝟑 .85 Dimensionless 𝑭𝟒 1.693 Dimensionless 𝑪𝒕 285.4 $ 𝑪𝒑𝟏 4170.6 $ 𝑪𝒑𝒖𝒓𝒄𝒉𝒂𝒔𝒆𝒅67732.96 $ 𝑊ℎ𝑒𝑟𝑒 𝐼𝑛𝑑𝑒𝑥 𝐼𝑛 1985 = 333.3 𝑊ℎ𝑒𝑟𝑒 𝐼𝑛𝑑𝑒𝑥 𝐼𝑛 2016 = 668.1 668.1 𝐶𝑜𝑠𝑡 𝐼𝑛 2016 = 67732.96 ∗ = 135770.74$ 333.3 107 8.1.6 Distillation Column Cost Estimation (D-2) For Distillation Column: 𝐶𝑡 = 𝑓1 ∗ 𝐶𝑏 + 𝑁𝑓2 𝑓3 𝑓4 𝐶𝑡 ∗ 𝐶𝑝1 𝐿 𝑇 𝐶𝑏 = exp(7.123 + .1478(𝑙𝑛𝑊 ) + .0248(𝑙𝑛𝑊 ) + .0158( )( 𝑏 ) 𝐷 𝑇𝑝 9020 < 𝑊 < 2470000, 2 < 𝐷 < 16 𝑓𝑡. 𝑡𝑟𝑎𝑦 𝑑𝑖𝑎𝑚𝑒𝑡𝑒𝑟 𝑁 = 𝑁𝑢𝑚𝑏𝑒𝑟 𝑂𝑓 𝑇𝑟𝑎𝑦𝑠 𝐶𝑝1 = 204.9𝐷 .6332 𝐿.8016 2 < 𝐷 < 24 57 < 𝐿 < 170 𝑓𝑡 Material 𝑭𝟏 𝑭𝟐 Stainless steel, 304 1.7 1.189+.05770D Stainless steel, 316 2.1 1.401+.07240D Carpenter (20CB-3) 3.2 1.525+.07880D Nickel-200 5.4 Monel-400 3.6 2.306+.1120D Inconel-600 3.9 lncoloy-825 3.7 Titanium 7.7 108 Tray Types 𝑭𝟑 Valve 1.00 Grid .80 Bubble Cap 1.59 Sieve .85 Parameter Value Units 𝑭𝟏 1.7 Dimensionless 𝑪𝒃 11540 $ 𝑭𝟐 1.9 Dimensionless 𝑭𝟑 .85 Dimensionless 𝑭𝟒 1.224 Dimensionless 𝑪𝒕 285.4 $ 𝑪𝒑𝟏 4170.6 $ 𝑪𝒑𝒖𝒓𝒄𝒉𝒂𝒔𝒆𝒅32253.96 $ 𝑊ℎ𝑒𝑟𝑒 𝐼𝑛𝑑𝑒𝑥 𝐼𝑛 1985 = 333.3 𝑊ℎ𝑒𝑟𝑒 𝐼𝑛𝑑𝑒𝑥 𝐼𝑛 2016 = 668.1 668.1 𝐶𝑜𝑠𝑡 𝐼𝑛 2016 = 32253.96 ∗ = 64653.077$ 333.3 109 8.3 Total Equipment Cost Serial No. Equipment Cost ($) 1 Reactor (*2) 17869 2 Heat Exchanger (*5) 17869 3 Distillation Column (*2) 69176.95 4 Centrifuge (*4) 419219 5 Flash Tank 6844 7 Mixing Tank (*3) 97140 Total 536984 8.4 Total Physical Plant Cost (PPC) 1 f1 Equipment Erection .4 2 f2 Piping .7 3 f3 Instrumentation .2 4 f4 Electrical .1 5 f5 Utilities .5 6 f6 Storage .15 110 𝑃𝑃𝐶 = 𝑃𝐶𝐸 ∗ (1 + 𝑓1 + 𝑓2 + 𝑓3 + 𝑓4 + 𝑓5 + 𝑓6) 𝑊ℎ𝑒𝑟𝑒 𝑃𝐶𝐸 = 𝑃𝑢𝑟𝑐ℎ𝑎𝑠𝑒𝑑 𝐸𝑞𝑢𝑖𝑝𝑚𝑒𝑛𝑡 𝐶𝑜𝑠𝑡 𝑊ℎ𝑒𝑟𝑒 𝑃𝑃𝐶 = 𝑇𝑜𝑡𝑎𝑙 𝑃ℎ𝑦𝑠𝑖𝑐𝑎𝑙 𝑃𝑙𝑎𝑛𝑡 𝐶𝑜𝑠𝑡 = 1637801.19 $ Fixed Capital 1 f7 Designing & Eng. .3 2 f8 Contingencies .1 𝐹𝑖𝑥𝑒𝑑 𝐶𝑎𝑝𝑖𝑡𝑎𝑙 = 𝑃𝑃𝐶 ∗ (1 + 𝑓7 + 𝑓8) 𝑊ℎ𝑒𝑟𝑒 𝑃𝑃𝐶 = 𝑃ℎ𝑦𝑠𝑖𝑐𝑎𝑙 𝑃𝑙𝑎𝑛𝑡 𝐶𝑜𝑠𝑡 = 1637801.19 $ 𝐹𝑖𝑥𝑒𝑑 𝐶𝑎𝑝𝑖𝑡𝑎𝑙 = 𝐸𝑞𝑢𝑖𝑝𝑚𝑒𝑛𝑡 𝐶𝑜𝑠𝑡 = 2292921.66 $ 8.5 Total Investment Working Capital (5% of fixed capital) = 114646.08 $ 𝑇𝑜𝑡𝑎𝑙 𝐼𝑛𝑣𝑒𝑠𝑡𝑚𝑒𝑛𝑡 𝑅𝑒𝑞𝑢𝑖𝑟𝑒𝑑 𝐹𝑜𝑟 𝑃𝑟𝑜𝑗𝑒𝑐𝑡 = 𝐹𝑖𝑥𝑒𝑑 𝐶𝑎𝑝𝑖𝑡𝑎𝑙 + 𝑊𝑜𝑟𝑘𝑖𝑛𝑔 𝐶𝑎𝑝𝑖𝑡𝑎𝑙 𝑇𝑜𝑡𝑎𝑙 𝐼𝑛𝑣𝑒𝑠𝑡𝑚𝑒𝑛𝑡 𝑅𝑒𝑞𝑢𝑖𝑟𝑒𝑑 𝐹𝑜𝑟 𝑃𝑟𝑜𝑗𝑒𝑐𝑡 = 2407567.75 $ 8.6 Annual Operating Cost Annual Fixed Cost 1 Maintenance Cost 7% of Fixed Capital 2272983.43 $ 2 Operating Labour Depend on Market 159108.84 $ 111 20 % of Operating 3 Laboratory Cost 1820437.50 $ Labour 20 % of Operating 4 Supervision 364087.50 $ Labour 5 Plants Overheads 50% of Operating Labour 910218.75 $ 6 Capital Charges 10% of Fixed Capital 227298.34 $ 7 Insurance 1% of Fixed Capital 45459.67.67 $ 8 Local Taxes 2% of Fixed Capital 3913427.94 $ Total Fixed Cost 3917415.58 $ Annual Variable Cost 1 Raw Materials Depends on Market Rate 9385819.61 $ 2 Miscellaneous 10 % of Maintenance Cost 15910.88 $ Total Variable Cost 9401870.06 $ 8.7 Direct Production Costs Direct Production Cost = Total Fixed Cost + Total Variable Cost = 13319285.65 $ 112 8.8 Annual Production Cost R & D Cost = 25 % of Direct production Cost Annual Production Cost = Direct Production Cost + R & D = 16,6,49,107.06 $ Annual Production Cost (In Rs. ) = 1,744,410,192.21 𝑅𝑠. 8.9 Production Cost Operating hours of plant per annum = 8000/ year kg 𝑘𝑔 Product Rate = X = 10512000 hr 𝑦𝑒𝑎𝑟 Annual Production Cost 16649107 $ Production Cost = = = 1.72 Annual Production Rate 9654336 𝑘𝑔 $ Production Cost (in Rs. ) = 180.21 𝑘𝑔 113 Chapter 9 SITE & MATERIAL SELECTION 9.1 The Project Our project deals with the production of waste cooking oils (preferably soybean oil) via the method of base catalysed transesterification. We are to design a viable continuo us method of production of our product using the cheapest resources possible while maintaining little to no compromise on quality. 9.2 Proposal for Site Location The criteria most important for the selection of our site location are as listed. 1. Raw Materials 2. Market 3. Energy Availability 4. Climate 5. Transport 6. Water Supply 7. Waste Disposal 8. Labor Supply 9.2.1 Raw Materials The raw materials for our project are as follows. 1. Waste Cooking Oil 2. KOH 3. Methanol Possible route for the cheapest waste oil for our product is perhaps through food markets or at ports near Karachi where waste oil from abroad is dumped. A setup near edible markets would be really profitable if their presence is limited to a smaller area. In this way, our transportation cost would be massively cut down which will eventually cheapen our fuel making it more viable for the masses. Hence it is recommended that the plant be set near an area which deals with food items on regular basis and in large volumes. 114 9.2.2 Climate FAMEs have an approximate pour pt. between -10 to -20 degree centigrade. It is therefore essential that our site not be located in an area with temperatures lower than 0 degree centigrade. This will cause the biodiesel flow to hinder and in turn the energy consumptio n will increase. 9.2.3 Market Our end product may be sold at conventional fuel pumps in the form of mixing of the diesel reservoir with manufactured biodiesel in proportionate amount. However, the governme nt must enforce stricter laws regarding air pollution prior to that. An example would be the environmental protection laws of Europe and the United States. 9.2.4 Waste Disposal 1. Salts 2. Filter Residue Main wastes from our production unit would be salts and filter residue. Both of these are not that harmful for human health. Filter residue, since it is organic waste can be sold as manure for crops. The salt can also be sourced to the preferable industries. Hence, waste disposal is not the most critical of issues. 9.2.5 Transport It is essential for any industry to have a sound means for both transferal of its raw materials and its products. It is highly recommended that our project be located near a busy route. It will also ensure the quick availability of our product to the masses. Since we’ve already established that our project needs to be in the vicinity of a cluster of food outlets, the issue has been resolved to a greater extent. 9.2.6 Water Supply In biodiesel production, it is quite necessary that we have a reasonable water supply means. This is because it is often required by the biodiesel manufacturers to wash their fuel. This is done in order to remove the impurities. Hence a sustained water supply is necessary for a biodiesel plant. 115 9.2.7 Labour Supply In a country like Pakistan labour is not really an issue especially since our project is to be located in a populous city. 9.3 Conclusion So, a few points’ important tips for the site selection for our project are. 1. Plant should be near a mass food market. 2. Should have adequate storage facilities for waste oil collected from the above- mentioned outlets. 3. Should be near a main road for easy transportation of raw materials and finis hed goods. 4. It is necessary that the plant be installed in a place with a weather that is not too cold. Else we will have to invest a lot of resources on the pumping of our finis hed product. 5. Also, provision of energy is a key factor to our project since we will be using steam for the removal of methanol from our (ester + methanol) mixture. We can use natural gas for this purpose or wood which is locally sourced for winters when there is a shortage of gas utility. 116 Chapter 10 HAZOP STUDY A hazard and operability study is a procedure for the systematic, critical, examination of the operability of a process. When applied to a process design or an operating plant, it indicates potential hazards that may arise from deviations from the intended design conditions. HAZOP is basically for safety and hazards are the main concern. Operability problems degrade plant performance (product quality, production rate, profit). For HAZOP, considerable engineering insight is required - engineers working independently could develop different results. 10.1 HAZOP On Double Pipe Heat Exchanger Guide Word Deviation Causes Consequences Action Temperature of Low Less flow of Less Pipe blockage oil remains temperature heating water constant alarm Temperature of High More flow of Failure of hot More oil increase from temperature heating water water valve set point alarm 117 10.2 HAZOP On Distillation Column (Parameter Pressure) Guide Word Deviation Causes Consequences Action Inlet Pipe Check Inlet NO Deviation Rupture/Inlet No Separation Pipeline & Valve Closed Valve Check Inlet Less Separation, Leakage in Pipe Condition, No Pressure Off Specified LESS Column Check Tower Product Walls Temperature Both Install PIC at Low Pressure Too High Components MORE Inlet & TIC in Inside the Methanol & Column Column Water Vaporize 118 10.3 HAZOP On Distillation Column (Parameter Temperature) Guide Word Deviation Causes Consequences Action Temperature Reboiler Not No Separation of Install Flow Higher Than Working The Components Control Valves MORE Required Properly Both Vaporize at Steam Inlet to The Reboiler 119 10.4 Hazard Analysis The Process of Hazard Identification is the procedure to assess all the hazards that could directly and indirectly affect the safe operation of that plant and or system, and is referred to as the Hazard Identification procedure or HAZAD. The Plant of fame having differe nt hazards which could cause an Event (release of toxic, flammable or explosive chemica ls, or any action) that could result in injury to personnel or harm to the environment. That Hazards are listed in the table below: Hazard/Threat Causes Consequence Possible Safeguards Exposure of Possible leak in May cause eye Flush eyes with glycerol glycerol storage irritation. May plenty of water for tank or line. cause skin irritation. at least 15 minutes. Can cause Flush skin with gastrointestinal plenty of water for irritation. at least 15 minutes while removing contaminated clothing and shoes. Never give anything by mouth to an unconscious person. Do NOT induce vomiting Exposure of FAME Possible leak in Severely irritation Irrigate eyes with a biodiesel storage to skin and eyes, heavy stream of tank or line. Inhalation cause water for at least 15 irritation of to 20 minutes. 120 respiratory tract. Wash exposed May cause central areas of the body nervous system with soap and depression with water. Remove symptoms of from area of dizziness, headache, exposure; seek nausea, vomiting, medical attention if and drowsiness. symptoms persist. Give one or two glasses of water to drink. If gastro- intestinal symptoms develop, consult medical personnel. (Never give anything by mouth to an unconscious person.) Fire/Explosion due Heating or any May result in loss of Storage should be to biodiesel ignition source in human lives and designed according storage or auto material and to internationally ignition due to equipment loss recognized high temperature guidance and Flash Point requirements. Use (Method Used): water spray to cool 130.0 C or 266.0 drums exposed to F min (ASTM 93) fire. Dry chemical, foam, halon (may not be permissible in some countries), 121 CO2, water spray (fog). Water stream may splash the burning liquid and spread fire. Exposure of Possible leak in High concentrations If vapours or mists biodiesel biodiesel tank in air causes frost are generated, wear burns to eyes a NIOSH approved irritating, to organic vapor/mist respiratory system. respirator. Safety Causes burns. May glasses, goggles, or cause cancer. face shield Harmful to aquatic recommended to organisms. protect eyes from mists or splashing. PVC coated gloves recommended to prevent skin contact. Employees must practice good personal hygiene, washing exposed areas of skin several times daily and laundering contaminated clothing before re- use 122 Exposure of Possible leak of Hazardous in case Check for and methanol methanol from of skin contact remove any contact cylinders or pipe (irritant), of eye lenses. Immediately lines contact (irritant), of flush eyes with ingestion, of running water for at inhalation. Slightly least 15 minutes, hazardous in case of keeping eyelids skin contact open. Cold water (permeator). Severe may be used. Get over-exposure can medical attention, result in death. Cold water may be used. Get medical attention if inhaled, remove to fresh air. If not breathing, give artificial respiration. If breathing is difficult, give oxygen. Get medical attention immediately 123 Appendix A Matlab Program 124 125 126 127 Appendix B Flash Tank Data 128 129 Appendix C D-1 Data 130 131 132 133 134 Appendix D D-2 Data 135 136 137 138 Appendix E Heat Exchanger Charts & Graphs 139 140 141 142 Appendix F Costing Indices 143 144 References [1] M. A. H. b. Fangrui Ma, “Biodiesel production: a review,” Nebraska, 1999. [2] L. W. JR., Orgainc Chemistry, Pearson. [3] G. Knothe, Dependence of biodiesel fuel properties on the structure of fatty acid alkyl esters, 2005. [4] M. S. C. HUNG, “PROSPECT OF BIODIESEL PRODUCTION FROM WASTE OIL AND FAT IN MALAYSIA,” 2010. [5] C. M. T. S. M. L. L. &. S. Garcia, Transesterfication of soybean oil catalyzed by sulfated zirconia, 2008. [6] W. Y. &. B. 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Kern, Process Heat Transfer, McGraw Hill, 1950. 145