SUMMER TRAINING REPORTON AT BABRALA(U.P.) SUBMITTED BY:- AMAN KR SINGH Serial No.-05/11 Roll No.- 1104551004 Final B.Tech. Chemical Engineering H.B.T.I. KANPUR CERTIFICATE This is to certify that AMAN KR SINGH (Roll number:-1104551004), Student of Chemical Engineering Department, HBTI Kanpur has completed the summer training in urea department on the project entitled “COMPARISON OF PRILLING TOWER ON THE ACTUAL AND DESIGN DATA” under our guidance. He has a good appetite for learning. We wish success for his future. Project head: Mr. U.P Singh (Head of Department urea plant) Project Guide:Mr. Prabhat Srivastava (Manager Urea Department) Mr. Siddharth ACKNOWLEDGEMENT Words are inadequate and out of place at times particularly in the context of expressing sincere feelings in the contribution of this work, is no more than a mere ritual. It is our privilege to acknowledge with respect & gratitude, the keen valuable and ever-available guidance rendered to us by Name and Designation of Training Guide/Mentor of industry without the wise counsel and able guidance, it would have been impossible to complete the training in this manner. I am always be highly grateful to Mr. U.P Singh, (Head of Department), and Mr. PrabhatSrivastava,(MANAGER)for providing this opportunity to carry out the present work. I would like to thank Mr. Siddharth for his appreciations that made me more enthusiastic in delivering my best efforts for completion of the project We express gratitude to other faculty members of Chemical Engineering Department, HBTIK for their intellectual support throughout the course of this work. Finally, we are indebted to our family and for their ever available help in accomplishing this task successfully. Above all we are thankful to the almighty god for giving strength to carry out the present work. Name of Candidate :Aman Kr Singh I have not submitted the same report in any other organization. Singh .DECLARATION I hereby declare that all the information mentioned in the project report is best to my knowledge. Aman Kr. All the findings are based on my own effort and research. No. Theory Various methods to make a 3. 4.L. 5. Urea Plant (Process Description) and function of important sections.C. Introduction to Company 2. Height of the tower. & . Results 7. Name 1.CONTENTS S. Project Objective finished product. Calculations 6. Fire & Safety Fire Prevention Classification of fire Firefighting gadgets appliances Safety programme at T. References Diameter of the tower. Scope for further improvement 1.8. food. which constitutes nearly 12 per cent of the total urea produced by India's private sector. with the largest domestic market share. petroleum. refining. paints. TCL has a varied user industry base comprising glass. The fertilizers. The products go into numerous end-use applications in a variety of industries: glass. food additives.. . INTRODUCTION TO TATA CHEMICALS LIMITED BABRALA Tata Group. tanning. pesticides. With an export presence in South and Southeast Asia. paper.8 per cent. dyes. Established in 1939. is one of the largest inorganic complexes in the world beginning to TATA Group. The complex has an installed capacity of 3500 MTPD. it has set itself the objective of achieving global cost competitiveness in soda-ash. sold under the brand name 'Paras'. An ISO-9001/14001 OHSAS 18001 certified company. Experience 9. Its first plant. Tata Chemicals is among the world's largest producers of synthetic soda ash.000-crore ($14. detergents. iodized salt segment. lead the market in West Bengal. Tata Chemicals makes urea at its fertilizer complex in Babrala. pharmaceuticals. the highest in the country. Bihar and Jharkhand. 4000 crores and is part of the Rs 65. by itself. photography. building and construction. and meet the most rigorous international specifications.2 million tons per annum. India's foremost business conglomerate. rayon. Its salt has a purity percentage of 99. The Haldia plant has production volumes exceeding 1. pulp. TCL is also a pioneer and market leader in the branded. Tata Chemicals. Its foray into phosphatic fertilizers follows the merger of Hind Lever Chemicals Limited into Tata Chemicals Limited. which is also called inaugurated establishment of TATA. direct farm application etc. agriculture. It is India's leading manufacturer and marketer of inorganic chemicals and fertilizers. with a turnover of over Rs. TCL's phosphatic fertilizer complex at Haldia in West Bengal is currently the only manufacturing unit for DAP/NPK complexes in West Bengal.25 billion) TCL's products and production processes are benchmarked with the best of global touchstones. paper. and chemicals. textiles. produced at the company's integrated complex at Mithapur on the Gujarat coast in western India. the Middle East and Africa. textiles. chemicals. Tata Chemicals is also one of India's leading manufacturers of urea and phosphatic fertilizers. YogyataPramanPatra Award. Delhi. 1997.2004. NSCI safety award for 2006. TCL. ICC Aditya Birla Award for Best Responsible Care Committed Company and ICC Award for Social Responsibility for 2005-06. Nine ABCI (Association of Business Communicators of India) Awards.2—4. Fertilizer Association of India. 1997-98. 2001-02. Nov.CREDENTIALS OF TATA CHEMICALS LIMITED BABRALA AWARDS: Prestigious Industry Award. . 2008. Excellence in Safety. Second best productivity performance in Nitrogenous Fertilizers Industry. 500 crores in foreign exchange every year and provide the farmer with nitrogenous nutrient. UK. 2000-01. 1998. of UP. Safety Gold Awards. Dec. Babrala is estimated to save the country about Rs. TCL BABRALA: THE NATION’S CONCEIT Substituting a part of the imports of Urea. which could help raise the food production by about 4 million tones/year. Jawaharlal Nehru memorial National Award for Pollution Control and Energy Conservation. British Safety Council. Dec.2004. Best Technical Innovation Award. CII-Exim Bank Award for Business Excellence. Produced more than 100% of the designated production during the first year of commercial production. Ministry of Power. National Energy Conservation Award. National Energy Conservation Award. Best Production Performance Award for Nitrogenous Fertilizers. Fertilizers Association of India Award for the Best Technical Innovation 2007. First major steps towards the fulfillment of a long standing TATA CHEMICALS commitment to provide the farmer with an optimal package of agriculture inputs to safe guard the food security of the company. 1995. Greentech Foundation. 1998. Ministry of Power.. World Environment Foundation. Govt. Indian Chemical Council (ICC) confers the ICC award for social responsibility 200506. 5 Star Rating in Safety. Fertilizer Association of India. Golden Peacock Environmental Management Award. Fertilizers Association of India. Commendation Certificate for Strong Commitment to TQM. productivity and safety It is the only fertilizer plant in the country to use dual feedstock: natural gas or naphtha. or a combination of both. and produced 9. among the best of its kind in India and comparable to the best in the world. MILESTONES OF TATA CHEMICALS LIMITED. ISO 14001 certificate for Babrala township obtained in 2004. 1994 ISO 14001 certificate obtained in October 2000. 1994 UREA UNIT Urea Prill Test conducted October 04. Now produce capacity of 8. BABRALA Commercial Production Started on December 21. 1994 First Prill Test conducted through Unit 2 November 05. has set new standards in technology. 1994 First feed into Primary Reformer October 20.102. 64. 1994 First Carbon Dioxide for making Urea October 23. BABRALA . 1994 AMMONIA UNIT First firing of Reformer Furnace for dry out of refractory October 12. 40. which constitutes nearly 12 per cent of the total urea produced by India's private sector. energy conservation. Current maximum capacity is 101%. 1994 First Ammonia production November 14. Produced more than 8. 51.764 tons of Nitrogenous Urea in year 1996-97.000 tons of Urea per year.35 tons of Urea achieving a capacity of 113% in the year1995-96. COMPOSITION OF TATA CHEMICALS LIMITED. The Babrala facility. Total production of urea at Babrala is 3575 tons/day maximum and 3500 tons/day average. 1994 Second Prill Test conducted through Unit 2 December 09. Mithapur THOMASSON. Gas Turbine Generator 2X20 MW Urea Synthesis 6. Two Cooling Tower have a common Prilling 24000 Msection.0Ammonia Plant Capacity: 2000MTPD Technology: HALDOR TOPSE Process. Rajpura block. Gunnor . DENMARK Plant (Single Stream) Production: 2000tons/day of liquid Ammonia. Naptha Bulk Storage 3X6300 KL TCL. Ltd. Methanation. Basic scheme involves the following steps: Desulphurization. After de-bottlenecking Plant at TCL.1. District Sambhal. Babrala is the first low energy plant in the country.Offsite and Utilities S. UNIT CAPACITY TECHNOLOGY Technology: SNAMPROGETTI Process. Synthesis and Chilling. 2. /hr M/S Paharpur Cooling Tower 4. M. Secondary Reforming and fired heater Carbon Dioxide Shift. ITALY 1. N.Urea Plant Capacity: 3500 MTPD 3. Tank SALIENT FEATURES OF TATA CHEMICALS LIMITED. Holland L&T M/S TechnofabEngg. Water Plant 3X450 M3 Basic scheme involves the following steps: 5. Captive Power Plant 1X110 TPH THERMAX/ L&T 3 urea strings 3. D. Ammonia Storage Tank 2X5000 MT M/S Kaveri Engineering Carbon Dioxide requirements supplied from ammonia plant. Storage and supply to Urea unit 2. Heat Recovery Unit 2X90 TPH Waste Water Treatment section 7. BABRALA Location Babrala. Primary. . Present installed capacity Ammonia:2000 MTPD Urea: 3500 MTPD Man power Deployment (During Commissioning/ Erecting phase ) Total 7. Land Area UNIQUE FEATURES OF TATA CHEMICALS LIMITED. south-east of Delhi.. BABRALA An integrated energy network. Punjab.13 Gcal/MT of Urea. Mathura Consumptive water source Eight deep bore wells. factor in achieving high energy efficiency.128 man-hours. 160km. . West Bengal. which is the key.P. Assam.855. The current low operating energy record is 5. Bihar. 1519 acres Plant area:1.069 acres Township area:350 acres Green belt: 100 acres Fuel Natural gas (main) Naphtha (alternate) Fuel Source Natural gas supplied by GAIL (HBJ Pipeline) Naphtha from IOCL.Tehsil. This provides a well-coordinated and integrated control of the entire complex from one location and on line inters plant sharing of information. Peak (month) 405.P. Urea to captive power and steam generation plant (CPSSGP) and other offsite and utility plants. This has been found extremely beneficial especially during plant startups and upsets. Approx. The second unique feature is common single central control room (CCR) for ammonia.799 man-hours. Beneficiary states U. M. The flexible range of the ratio of natural gas and naphtha as a fuel/ feed is a major reason for this. Uttar Pradesh. Smoking ignited fire: Smoking or even carrying cigarettes/ beedies/matches/lighter etc. loose electrical contacts. “A fire is a combination of fuel. 2. This is likely in non-lubricated and not well maintained machinery. All non-smoking areas should carry “NO SMOKING” signboards. high current. oxygen and source of ignition”. FIRE PREVENTION SOURCES: THROUGH ELIMINATION OF IGNITION To prevent fire the first is to remove the cause of fire. temporary direct connections without proper fittings.1 FIRE PREVENTION: Fire prevention can be done in three ways: Eliminate sources of ignition.FIRE AND SAFETY FIRE CHEMISTRY: The well-known “Fire triangle” requires the three ingredients of fire namely fuel. Eliminate combustible substances.2. short circuiting. frictional fires can also be started by the friction of moving parts of machinery which are overheated due to excess friction. Friction and overheated material: In flame proof areas. Eliminate air excess to combustible substances. FIRE PREVENTION THROUGH ELIMINATION OF COMBUSTIBLE MATERIALS: . Studies made by fire insurance company shows that majority of fires are caused by following general sources of ignition: Electrically limited fire: Improper earthing. over heating of electrical equipment are among the common cause of electrically initiative fires. oxygen and source of ignition. in the following areas is a serious offence. carbon dioxide etc. 2.Tins and cans of flammable materials like paints. cotton waste etc. . Waste disposal:All combustible waste must be regarded in such a way that can be disposed of as such and not burnt.2 CLASSIFICATION OF FIRES: Fires are classified according to the nature of fuel burning and fire extinguishing methods that can be applied and the following is the fire classification under the Indian fire code. Waste and combustible materials:All combustible wastes and materials like waste paper. Class “A” fires can also be extinguished by all the available means of extinguishing fires like foam. are categorized as class “B” fire. petrol etc. accumulated after a job should be transported to waste bins and is the responsibilities of the person doing the job that creates the wastes. paper etc. oils.: These should be handled carefully ensuring that no undue spillages takes place during their uses and any spillages takes place during their use and any spillage should be cleaned immediately. is called class “A” fire. clothing. CLASS “B” FIRE: Fires where the burning fuel is a flammable liquid Naphtha. CLASS “A” FIRE CLASS “B” FIRE CLASS “C” FIRE CLASS “D” FIRE CLASS “E” FIRE CLASS “A” FIRE: Fires where the burning fuel is a cellulosic material such as wood. Fueling of vehicle tanks: Engine should be always switched off while fueling a vehicle. dry sand should covered over the spill immediately till only dry sand is visible on the spilled area. soda acid. spirit etc. It can be extinguished by the water and sand. dry chemical powder. wet thick cotton blanket or sand. If diesel or petrol spills over during fueling. PREVENTION THROUGH ELIMINATION OXYGEN SUPPLY: Smoothening: It is a process of covering the burning area with a non-combustible substance like asbestos or fire proof blanket. CLASS “C” FIRE: Fire involving flammable like natural gases hydrogen are classified as class “C” fire.It contain under pressurized liquid carbon dioxide. Only carbon dioxide and D. the fire and safety department of T.C. FOAM:.3 FIRE FIGHTING GADGETS AND APPLIANCES: CO2:. dry chemical powder extinguishers are the desired means of controlling “B” class fires. Water is forbidden as a fire fighting means on class “B” fires. SODA ACID:.L The company conducts regular programs for safety measures. .C. potassium etc.Contain aluminous sulphate in inner container and sodium bicarbonate in outer one. CLASS “E” FIRE: Fires involving electrical equipment’s are classified as “E” class fires. This must be the intermediate and very first step. Foam. competitions etc. Sand buckets are useful in most cases of metallic fires. DRY CHEMICAL POWDER:. 2. zinc. Some of these are listed below: Training programs on safety.C. which not only creates awareness about safety but also maintains it. After the inner container both react and produce a liquid of entrapped CO2.L organizes many programs to motivate in this direction and to make the employees aware. are classified as class “D” fire.Blanketing is a useful first aid fire control for “B” class fire. National safety day 4th march is being celebrated each year with earnestness and includes various awareness programs.4 SAFETY PROGRAMME AT T. carbon dioxide.P extinguishers are used on class “E” fires. aluminum. CLASS “D” FIRE: Fire involving material like magnesium. Special dry chemical powder also works on class “D” fires. competitions and includes various awareness programs.Contain a double container with sodium bicarbonate solution in outer container and dilute sulphuric acid in the inner container. After cracking the container both reacts to produce carbon dioxide and the foam stabilizer makes stable form of carbon dioxide. Dry chemical powder and carbon dioxide are useful in controlling “C” class fire. 2.It contains an inert dry chemical powder of sodium bicarbonate or potassium bicarbonate or potassium chloride and diammonium phosphate along with liquid carbon dioxide under pressure. The best means of extinguishing “C” type fire is by stopping the gas supply to the leaking vessels or pipe lines if possible. HALON/ BROMOCHLOROFLUORO METHANE:-Halon is in the form of a liquid gas under pressure that is released on pressing the knob. Full body protection suits. Goggles for eye protection. Devices for power cut. Safety shoes for foot protection. Gloves for hand protection. Home safety. Safety belts or life belts or harness. and. . face. Face shields foot protection. SAFETY PROVISIONS Personal protective equipment (PPEs): The various types of PPEs are: Helmet for head protection. Hoists and lifts. Breathing apparatus or respiratory protection equipment. eye protection. Fencing of machinery. Hoods for head. Use of safety equipment. neck. Safety slogan competition. Ear plugs and muff for ear protection. Safety quiz. carbon dioxide and ammonium carbamate). Conversion of carbon dioxide to urea isapproximately 60% at a pressure of 50 barg.3. the pressure is reduced from 240 to 17 barg and the solution is heated.Purification The major impurities in the mixture at this stage are water from the urea production reaction and unconsumed reactants (ammonia. Firstly. but because biuret burns the leaves of plants. The solution is then purified in the same process as was used for the liquid from the first reactor. The unconsumed reactants are removed in three stages3. This is an exothermic reaction. The first reactor acheives 78% conversion of the carbon dioxide to urea and the liquid is then purified. Step 2 . is designed to maximisethese reactions while inhibiting biuret formation: 2NH2CONH2 NH2CONHCONH2 + NH3 biuret This reaction is undesirable. which causes the ammonium carbamate to decompose . not only because it lowers the yield of urea.UREA SYNTHESIS (Process Description) Urea is produced from ammonia and carbon dioxide in two equilibrium reactions: 2NH3 + CO2 NH2COONH4 Ammonium carbamate NH2COONH4 NH2CONH2 + H2O urea The urea manufacturing process. The structure of these compounds is shown in Figure 3. shown schematically in Figure below. This means that urea which contains high levels of biuret is unsuitable for use as a fertiliser. Step 1 . and heat is recovered by a boiler which produces steam.Synthesis A mixture of compressed CO2 and ammonia at 240 barg is reacted to form ammonium carbamate. The second reactor recieves the gas from the first reactor and recycle solutionfrom the decomposition and concentration sections. with more ammonia and carbon dioxide being lost at each stage. The reactor.to ammonia and carbon dioxide: NH2COONH4 2NH3 + CO2 At the same time. Detailed Study Of Each Section High Pressure Synthesis Section-Figure below shows the Process synthesis section. Efforts were made in the past to realize an easy. carbamate condenserand ejector comprise the synthesis section as major equipment. Liquid ammonia is fed into thereactor via the ejector. The excess ammonia is purified and used as feedstock to the primary reactor. simple and reliable process.Prilling The urea melt is typically fed into a conical shaped bucket spinning in the centre of a concrete tall prilling tower. Most of the CO 2 is fed to the stripper as stripping media and the rest is fedto the reactor as a source of passivation air and a raw material for urea synthesis in the reactor. At this stage some urea crystals also form. Step 4 . Stripped urea solution is sent to MP decomposition stage. By the time the mixture is at -0.0 barg and finally to -0.Concentration 75% of the urea solution is heated under vacuum. Efforts were made in the past to realize an easy. Urea synthesis solution leaving thereactor is fed to the stripper.35 barg. Sometimes static sprayers are applied. The pressure is then reduced to 2. The urea melt is typically fed into a conical shaped bucket spinning in the centre of a concrete tall prilling tower. Sometimes static sprayers are applied. At each stage the unconsumed reactants are absorbed into a water solution which is recycled to the secondary reactor.The . Thestripped off gas is fed to vertical submerged-type carbamate condenser.Carbamate solution from the carbamate condenser is fed to the reactor after being pumped by theejector that is motivated by high pressure liquid ammonia. some of the ammonia and carbon dioxide flash off. stripper. In the evaporation stage molten urea (99% w/w) is produced at 140oC. which evaporates off some of the water.35 barg a solution of urea dissolved in water and free of other impurities remains. Step 3 . The remaining 25% of the 68% w/w urea solution is processed under vacuum at 135oC in a two series evaporator-separator arrangement. The solution is then heated from 80 to 110oC to redissolve these crystals prior to evaporation. NH3 and CO2 gascondenses to form ammonium carbamate and urea in the shell side of the carbamate condenser. simple and reliable process. increasing the urea concentration from 68% w/w to 80% w/w. . Packed bedis provided at the top to absorb uncondensed NH 3 and CO2 into recycle carbamate solution fromMP absorption stage. The unique heat integration between the synthesis section and downstream sections further reduces energy requirement (See Figure). Inert gas from top of the packed bed is sent to MP absorption stage. .condensation heat is recovered to generate low pressure steam in the tube side. One is utilized for decomposition in the medium pressure sectionand the other is for low pressure steam generation to be utilized in the low pressure andevaporation sections.while appropriate elevation of the carbamate condenser supplies additional driving force bygravity. Condensation heat in medium pressure section is also utilized inevaporation section. The stripped NH 3 and CO2gas mixture is sent to the carbamate condenser and the condensation heat is recovered by the twoparallel carbamate condensers. MP steam is supplied to synthesis section to decompose and separate excess NH3 and carbamate in the stripper. Thedriving force for liquid and gas circulation in the synthesis loop is mainly provided by the ejector. Sometimes static sprayers are applied. Efforts were . Then there is 1st and 2nd vaccum separator which is used to separate ammonia carbon dioxide and water vapours present in urea solution . Pre VaccumAndVaccum Evaporation Section-Firstly there is vaccum pre concentrator section which is used to increase the concentration of urea solution to the evaporation section. Then there is a carbonate solution pump which is used to pump carbonate to decomposition section. Prilling Tower-The urea melt is typically fed into a conical shaped bucket spinning in the centre of a concrete tall prilling tower. In second vaccumconcentrator total evaporation of water remaining in urea solution takes place.Then there is a absorber which absorbs NH3 and CO2 from the reaction.Medium Pressure Decomposition Section-In this section concentration of urea takes place . There is a ammonia absorber and inert washing tower in which inert gas saturated in NH3vapour is scrubbed with cooled steam condensate.Then partial evaporation of water present in urea solution coming from the vaccum pre concentrator holder.It consist of medium pressure decomposition column which function is to decompose carbamate and separate from urea solution. Then there is a medium pressure condenser which function is to condense mixture of liquid and gas .Vaccum system is used to make vaccum in two evaporation section. Low Pressure Decomposition Section-The function of this section is same as the medium pressure decomposition section but it operates at a reduced pressure then earlier. The rotating bucket is a sieve-like cylindrical or conical drum that rotates . simple and reliable process. Sometimes static sprayers are applied. Urea in solid form is produced in the final process stage by either granulation or prilling. Efforts were made in the past to realize an easy. urea melt is pumped to the top of 50 to 60 meter (above ground) cylindrical concrete tower where it is fed to the prilling device that called rotating bucket. Prilling Tower 4.made in the past to realize an easy.PROJECT OBJECTIVEComparison OfPrilling Tower On The Actual And Design DataBrief Description Of Prilling Tower And Process Involved In It --Urea is marketed as a solution or in the solid form. simple and reliable process. In theprilling process. The urea melt is typically fed into a conical shaped bucket spinning in the centre of a concrete tall prilling tower. Transformation of urea from melt to solid prills takes place in the urea prilling tower. and thus a solidification-cooling process takes place. thus both the dry bulb temperature and humidity of the ambient air highly affect the quality of the final product Based on the reportedinformation from the company that is in some days in summer session.about its axis. 6) An adiabatic process is considered due to the material (concrete low thermal conductivity =0. K)and large thickness of the tower wall (0. 3) The pressure drop along the tower is neglected (about 0. 5) Radiation heat transfer between urea prills and the prilling tower walls is neglected (estimated about 0. and break up due to centrifugal and capillary instability. Thus. ) . the prills are hot to the limit that cannot be packed directly.01 Pa). the following assumptions are considered: 1) The droplet/ particle are spherical (from experimentalmeasurements) 2) Steady state for the urea melt is maintained.4% as reported from the company) is neglected. Three forces affect on the particle during its fall throughthe tower. The product. Hydrodynamics balance The prilling tower has a cylindrical shape.z ) with the unit vectors ( er . in humid/ hot days.63 m/s measured by the company).6%).k ) respectively. A countercurrent cooling air stream enters from intake openings located around the circumference of the tower at a height approximately 7 meters from the ground level of the tower.1% only) so that the effects of droplets/ particles on each other in both heat transfer and movement are neglected. the weight force Fw 4 Fw=m p g=ρ π R p3 g 3 ( that actsdownward.θ. As ambient air is used in the process of cooling and solidification of the prills inside the tower.8-1. as well as the conversion of urea to ammonia and carbon dioxide(around 0. the prilling process hydrodynamics model is derived in the cylindrical coordinates ( r. In addition. These forces are. constant pressure conditions can beapplied. urea prills. 4) Evaporation of urea in the whole process. Heat and mass transfer between the downward urea droplets and the upward cooling air stream along the heightof the tower occurs. the lamp of prills forms at the bottom of the tower that also is not desired for the product quality. goes from the tower base to a conveyor belt where it has collected and packed. While designing prilling tower. The delay in the packing process leads to a decrease in the yearly company production. Liquid jets emerge from the various holes on the curved surface of the drum.e . 8) Average value of the air velocity in the axial direction is considered (0. The liquid urea droplets formed fall downward the prilling tower.4 W/m. therefore.25 m) 7) The volumetric ratio of droplets/ particles in the prilling tower is normally very small (around 0. The air stream exhaust from the tower through the exhausted stakes located at the top of the tower where it spreads in the surrounding environment. and hence two phases exist in each droplet liquid and solid. Heat from the core of the particle transfers to the ambient air by conduction through the liquid and solid phases of the prills.5 Where Rep ¿ ρ a V az D p μa both ofthem acts upward as illustrated in figure.Buoyancy force FB F B=ρ a V p g= ρa ( 43 π R ) g 3 p . the solid particle loses sensible heat and further cooling takes place until the particle exits from the bottom of the tower at certain temperature.Heat transfer between the particles and the cooling air takes place along the height of the tower. In this stage. a solid layer δ ( z ) begins to appear on the surface of the droplet. Three zones of state have been assumed for each particle as it falls from the top to the bottom of the prilling tower. Energy Balance. the liquid droplet loses its sensible heat to the cooling air until it reachesthe crystallization temperature. The three zones are shown below Figure showing different zones in prilling tower- . and Drag force FD 1 F D = ρa C D ( π R p2)Vrel 2 V 0 2 The drag coefficient CD is determined by the formula for 2<Rep<500 CD= 18. the solid layer moves toward the center decreasing the liquid phase until the droplet becomes completely solid. In the second zone. In the last zone. In the first zone.5 ℜ p0. The urea melt is fed to the granulator.0 %. In the lower part of the granulator a number of headers are installed with the urea melt line in the center of the air header. The nozzle is a film spraying nozzle surrounded by injection air in a cylindrical pattern around the urea melt. The core of the system is the urea melt nozzle in the granulator. Prilling Tower method 2.Prilling Tower method.552 ℜ p 2 Pr 3 Where Nu and Pr are the dimensionless Nusselt and the Prantdlnumber.In the suction of the urea melt pump the urea melt is mixed with the urea formaldehyde. In the first evaporator the urea solution isconcentrated to about 95. The air header itself is insulated with a water resistant material to prevent heattransfer from the cold fluidization air to the secondary air. Thissolution is added to stabilize the final product. The urea formaldehyde is added as a precondensatemixture between formaldehyde and urea.In figure 2 a process flow diagram is given of the lay out of the granulation plant. A concentration of formaldehyde in thefinal product of 0.the heat transfer coefficient is obtained from the Ranz-Marshall’s equation as follows 1 1 Nu=2+0.5 %.30 % is enough to realize good final product properties. To reach this concentration twoevaporators are installed in the urea melt plant. This secondary air . Rotoform Technology 1. By this design it is assured that the urea melt line is always in a hot environment preventing the risk of the crystallization ofthe urea melt.This method has been discussed in detail in the above section. Granulation method 3. 2.respectively. Granulation method-The urea is fed to the unit with a concentration of 98. Various Methods To Make A Finished Product-1. result in regular pastilles with an optimum shape. chemical. food and fertilizer industries since the early 1980s and there are currently more than 1500 Rotoform units in operation worldwide.The Sandvik Process Systems’ Rotoform process as a very promising and successful alternative oraddition to the traditional finishing techniques of prilling and granulation. consists of a heated stator and a perforated rotating shell which turns concentrically around the stator to deposit drops of urea across the full width of the belt. The Rotoform HS (High Speed) drop former. The heat released during crystallization and cooling is transferred by the stainless steel belt to the cooling .5 .has a high velocity creating a zone with reduced pressure at the top of the nozzle. Mechanically. Stamicarbon and Sandvik Process Systems have been co-operating together to develop the Rotoformer for urea application. By this process there is no lump formation. typically 1.0 m. Urea is introduced under pressure (2-3 barg) in molten form to the drop former. a single Rotoform unit for urea pastillation consists of a continuously moving steel belt.TheRotoform process has been successfully employed in the petrochemical. after solidification. As a result of the lower pressure the seed material is sucked into this area and passes the urea melt. patented by Sandvik.Rotoform Technology.Already for nearly ten years. The rotating shell contains rows of small holes which are sized to deliver the required product size.2.6 wt% and in existing urea plants can be branched off from the urea evaporation section downstream of the urea melt pumps. The urea melt leaves the top of the nozzle as a film and the seed urea material has to pass this thin film. 3. with a drop former feeding device at one end of the moving belt and a scraper at the discharge endThe feed to the Rotoform is urea melt with a concentration of 99. wide and between 15 and 20 m in length (for a 125 – 175 metric ton/day unit). The circumferential speed of the Rotoformer is synchronized with the speed of the steel belt cooler ensuring that the drops are deposited on the belt without deformation and. In this way all seed material is covered by a thin film of urea melt and the concentratedliquid is completely consumed. . Under no circumstances can the cooling water come into contact with the urea product. The use of formaldehyde is not necessary in this technology to realize pastilles with a high crushingstrength.water. The product then falls directly onto a conveyor belt for transfer to storage. which is a unique feature of this technology. absorbs the heat and is collected in pans. Only some ammonia vapors which can be easily caught in a simple atmospheric absorber leading to a negligible emission of ammonia and urea. The cooling water is sprayed against the belt underside. There are no large air flows involved in this technology and there is no visible urea dust emission. After solidification the pastilles are smoothly released from the steel belt via an oscillating scraper. The pastilles are very uniform and additional screening is not needed. The section above the moving steel belt is enclosed with a hood and vented to an existing vent system. cooled in a cooling system (cooling tower) and returned to the Rotoform units. 6 224457 density of liquid= density of solid= specific heat capacity of liquid urea specific heat capacity of solidurea.00216 Physical properties of air(36.1) density of air = specific heat capacity of air= viscosity of air= thermal conductivity of air= mass flow rate of urea melt= (degree celcius) j/Kg Kg/m3(13 3) Kg/m3(20) 2098 j/(Kg*K)(132.14 kg/m3 1008 0.6 j/(Kg*K)[25-132] W/(m*K)[80] W*(m*k) N*sec/m2[80] (degree celcius) 1.CALCULATION - Physical properties of urea To(melting point) = ¡(latent heat)= 132.Calculation involving volumetric flow rate of air at the bottom of the prilling tower-- Heat given =Heat taken .5.83 1. 1230 1335 1748 thermal conductivity of liquid thermal conductivity of solid viscosity of liquid urea 0.19 0.000019 0.0268 j/(Kg*K) N*sec/m2 W*(m*K) 146000 Kg/hr Outlet temperature of air =83°C Inlet temperature of air= 42°C Inlet temperature of urea melt=137°C Outlet Temperature of Urea Melt=74°C 1. Calculation of diameter of prilling towerAssuming air velocity at the bottom of the prilling tower is 0.5148 meters π 3.0599676 ) = 26.51*3600) = 552.6) + 146*103 *224.457 + 146*103*(132.001448951 .6-74)*1.51m/sec Area of the prilling tower is = (volumetric flow rate of air)/(velocity of air *3600) A= 1155483.0599676 m2 Diameter of the tower is= √( 4∗552.Calulation of terminal velocity of the urea particleDiameter of granules = mass flow rate of urea melt= number of openings in the bucket*density of urea *volume of a urea particle From this diameter comes out to be 0.59 5 Kg/hr Volumetric flow rate is = m/(density of air at inlet temperature) = 1013582 m3/hr 2.595/(0.Sensible heat of the liquid +latent heat of fusion + sensible heat of the solid = Sensible heat of the air + latent heat of vapourisation of water Sensible heat of the liquid = (mass flow rate of urea melt)*(specific heat capacity of liquid )*(inlet temperature -melting point of urea) Latent Heat of fusion = (mass flow rate of urea melt)*(latent heat of fusion) Sensible heat of solid= (mass flow rate of urea melt)*(specific heat of solid urea)(melting point of urea-outlet temperature of urea) Sensible heat of the air= (mass flow rate of air)*(specific heat capacity of air)*(outlet temperature of air -inlet temperature of air) Latent heat of vapourisation of water = (mass of water in the urea melt )*(latent heat of water) The equation of energy balance 146*103 *2098*(137-132.4/100*146*103*2260*103 The mass flow rate of air is(m) = 1155483.748 = m *1008*(8342) + . Uo(overall heat transfer coffecient) .Rep ¿ ρ a V az D p Rep =452.0726625 Pr =Cp ¿ μ /K =0.75 m/sec Calculation of heat transfer coffecient of solid ureaRe = 452.49308 =h*Dp/K .552 ℜ p 2 Pr 3 Nu = 12. h= 231.87009686 9 FD= 2.2 m/sec 0.78095E08 (buoyancy force) FW= 2.714627 Using the following equation to find Nu 1 1 Nu=2+0.073775 5 W/(m2*K) Time Required for cooling of liquid urea-3 Area of urea granules is= 4 /3 π R p .21088E05 (drag force) FB= 1.45 m/sec 4.08559E05 (gravitational force) we can see that drag force +buoyancy force is nearly = gravitational force terminal relatve velocity is taking average velocity of air = actual velocity of the particle is 5.0726625 μa CD= 0. where Rp is the radius of urea granules. melting point) UoAo*(average temperature of urea melt -average temperature of air) t(sec) comes out to be 8.6.001268 t(sec) = m*Cp*(inlet temperature of urea melt.where k is the thermal conductivity of liquid urea UoAo= 0.where k is the thermal conductivity of solid urea UoAo = 0.1/UoAo = 1/hi*Ai + (1/R1 -1/R2)/4 πK .001335865 t(sec) = m*Cp*(melting point of urea melt.995536453 Height of the prilling tower from the bucket to the air inletTotal height of the prilling tower is =(terminal velocity of the particle)*(toal time taken by urea pellet to reach the air inlet ) =79.467331107 Time required for cooling of solid urea1/UoAo = 1/hi*Ai + (1/R1 -1/R2)/4 πK .exit temperature of urea pellets) UoAo*(average temperature of solid urea -average temperature of air) t(sec) comes out to be 3.273136 Time Required for phase change of liquid urea to solid urea1/UoAo= 656.50meters 6.RESULT- .average temperature of air) t(sec) for phase change comes out to be4.2572 t(sec)= (latent of urea)*(mass of a single urea particle) UoAo (132. H. McGraw Hill International Editions. Smith. Encyclopedia of Industrial Chemistry. Vol. Yunus A. Tata McGraw Hill Process Flow Diagram. Introduction to chemical Engg Thermodynamics.M. Trainee Manual. M. 2007. MTPD UREA Plant (operating Manual Vol 1) J . 3. Babrala International Journal of Chemical Engineering and Applications.REFERENCES Fire and safety manual.52meters The height of the prilling tower is 79.C. Thermodynamics : An Engineering Approach.M Abbott. VanNess. Cengel.50meters 7. available at Tata Chemicals Limited. Fertilizer association of India. . Boles. No. 5. Micheal A. Wiley-VCH.The diameter of the prilling tower is 26. October 2012 Ullmann. Moreover food facility in canteen is much better in comparison to other industries. This industry also have beautiful township area which is clean and full of natural environment moreover this area is completely pollution free and also providing 24 hrs light facility. This industry consists of several employs and all are very much helpful as they helps trainee like me with their full devotion. For trainees TCL provides best technical library which consist of best books regarding all the technical aspects and for various field of engineering with good facility of internet but in my view its capacity is less and procedure of issuing books for trainees is very complicated. This industry is as prosperous as one engineer can dream. In nut and shell my experience in this industry is unforgettable and as good as I can think & I want to come here again in future. My residence is in township and there I feel as I am in heaven. They give us time from their busy schedule and try to resolve our every problem. .Experience I am in TCL under 5 week summer training and my first industrial experience is too good so that I cannot express it in my words. Moreover rule and regulations of traffic are up to the mark.8. This industry consist of wide and prosperous safety department which is providing a landmark to the most important parameter of the company “Safety” and this industry is standing as one of the most safe chemical industry of the world. SCOPE FOR FURTHUR IMPROVEMENT In summer there is a problem of getting urea prills at a high temperature. This problem can be avoided by using bucket with larger number of holes thus it will have larger area for heat transfer from urea prills. we can also pass the urea prills through a drier which will reduce the moisture content as well as the temperature of the urea prills. which makes it difficult to pack. .9. For obtaining a better product. which can be avoided by passing air through a dehumidification column. In humid condition there is a problem of lump formation or increased moisture in urea prills.