Sugar Definition Sucrose is common table sugar obtained from sugar cane and sugar beets.The chemical Formula C12H22O11 which does not reduce Tollens or Feling’s reagents is determined by the stereochemistry of the D-Glucoside and D-Fructroside linkage to form sucrose. The results of XRay studies and the Synthesis of +sucrose lead to the conclusion that (+) Sucrose is a beta DFructoside and an alpha D-Glucoside. The Chemical Form of the Sucrose In Simple Form of sucrose Physical properties of Sucrose 1) Pure Sucrose Crystal are Transparent and colorless 2) Heat Conductivity of crystallized Sucrose Only Crystal of sucrose 00.00139 cal/cm-sec°c 3) The Dipole moment is found to be 3.1x1018 dyne/cm² 4) The Dielectric constants of sucrose Crystal is different directions values and between 3.5 and 3.85 was found. 5) Piezoelectric effect of sucrose was observed, the sucrose is Dia-magnetic, and the specific magnetic susceptibility is being 0.57. 6) The density of crystalline Sucrose at 1.5°c is 1.5879gm/ml, were found powdered crystalline sucrose. 7) Linear thermal expansion 8) Melting point of sucrose is 185-186°c 9) Specific Volume of Crystallized Sucrose is 0.63ml/gm @ 15°c under Normal pressure. 10) Molecular weight of sucrose is 342.296 11) Normal Entropy of sucrose is 86.1kcal/mole 12) 13) 14) Enthalpy of formation is 530.8 kcal/mole Work of formation amount to -317.6kcal/mole at 25°c and 760mm pressure of Hg. Enthalpy of combustion is -1351.3kcal/mole Chemical Properties of Sucrose: 1) Sucrose is a carbohydrate of the formula C12H22O11 2) It is a disaccharide, consisting of monosaccharide components. 3) Refined sugar contains about 99.99% of sucrose. 4) Purest sucrose is obtained by redissolving sugar in water precipitating with absolute Ethyl Alcohol. 5) Sucrose is very soluble in water and faintly hygroscopic. 6) Small quantities of salt decrease the solubility of sucrose, while higher quantities of salt increase it. 7) When sucrose solutions are treated with metal hydroxides under suitable conditions, colloidal turbidities, syrup gels or flake precipitates are obtained. 8) In the presence of hydrogen ions a hydrolytic, decomposition of sucrose takes place. 9) When the sucrose solutions are heated in presence of OH-Ions, decomposition takes place. 10) In a solution of sucrose with lime of Ph 12, the sugar loss in one hour boiling under normal pressure was found to be about 0.5%. Cane Preparation Equipment The following table gives recommendations on cane preparation equipment Installed Specific powers and tip speeds. Cane Preparation Equipment Installed Power Specific Power Description [kW/tfh] Leveller knives 6 First knives 15 Second knives (heavy duty) 30 Shredder 60 Total 111 Southern African industry average 84 Tip Speed [m/s] 50 60 60 100 Tip Clearance [mm] 1000 150 50 Installed Specific Power for Milling Table of required installed power for a milling tandem Number of Mills Four mills Five mills Six mills Diffuser + two mills Specific Power per Mill [kW/tfh] 22 20 18 25 Mill Capacity Calculations There are a large number of formulae for the calculation of the capacity of a milling tandem Hugot gives the following formula: A = 0.3 if the tandem is preceded by a shredder n is the mill speed in rev/min N is the number of rollers in the tandem L is the length of the roll in meters D is the mean diameter of the rollers in meters f is the fiber percent cane .06·n·D) ·L·D2/f Where c is a factor dependent on the cane preparation equipment.8 c·n·√N· (1-0. c= 1. 8 c·n·√N· (1-0.Example: Capacity of the plant---------------------5000 TCD Cane crushing per hour--------------5000/22 =227.75x10 kg/m³ .06·n·D) ·L·D2/f (Or) Mill setting calculation (based on Fiber Index loaded Method) Fiber loaded in various mill the following formula FL=1000x AxF/60x3.e-14%) D=Pitch Circle Diameter of the Top Roller N=Speed of the Roller (rpm) L=Length of the Roller A. A=Total Cane crushing per hour F=Fiber percentage of cane (i.14xDxNxl (Kg/m2) Where. Fiber % of Bagasse Approximately percentage of fiber in bagasse foe each mill first mill=34% Second mill=39% Third mill=45% Fourth mill=50% Formula for fiber Index is given =Fiber % of bagassex1.27 TCH Imbibitions percentage of cane-----------35±2% Bagasse percentage on cane--------------29±1% Hugot gives the following formula: A = 0. 75 x feed roller work opening Mill Sizing Nomogram The nomogram below from is a quick guide to sizing a milling tandem .Discharge roller setting Dr=Fiber Load/Fiber Index (mm) Feed Roller setting Fr=mill ratio x Discharge work opening Trash plate setting Tp=1. Geometry of Mills Ratio of feed opening to discharge opening in the mill ratio = 2 working position . Top roll mean diameter Discharge roll mean diameter Feed roll mean diameter Tooth Pitch Tooth Flat Tooth Angle Tooth Depth Roll Length Speed of top roll MDT = 45 in MDD = 45 in MDF = 45 in TP = 2 in T fl = 6 mm T ang = 45° T depth = (TP .T fl) / (2 · tan(Tang / 2)) l roll = 7 ft n = 3 rpm Tooth Profile Mill Operating Parameters Cane throughput tch = 250 ton/hr f%c = 15% . MDT / 2 + MDD / 2 soD = 18 mm set feed opening (Tip to Bottom) set discharge opening (Tip to Bottom) .25 in at rest mill lift l = 15 mm Horizontal distance between top roll and feed roll HF = √(TF2 .667 m3/min woF = volEscrF/ (vTF · l roll) woF = 58 mm TF = MDT / 2 + MDF / 2 + woF TF = 1201 mm TD = MDT / 2 + MDD / 2 + woD TD = 1172 mm described volume in the discharge opening Feed Work Opening Top .Feed roll Centers (Working) Top .Discharge roll Centers (Working) Vertical distance between top and side roll centers Vrest = 33.(Vrest + l)2) centers HF = 839 mm Horizontal distance between top roll and discharge HD = √(TD2 .(Vrest + l)2) roll centers HD = 797 mm soF = √(HF 2 + Vrest2) .fiber % cane fibrethput = tch · f%c fibrethput = 567 kg/min vTF = n / 2 · (MDT + MDF) / 2 vTF = 10.77 m/min vTD = n / 2 · (MDT + MDD) / 2 vTD = 10.MDT / 2 + MDF / 2 soF = 47 mm soD = √(HD2 + Vrest2) .77 m/min ffD = 850 kg/m3 fibre fill in the discharge opening fibre throughput Average peripheral velocity of top/feed rolls Average peripheral velocity of top/discharge rolls fibre fill in the feed opening ffF = ffD / mill ratio volEscrD = fibrethput / ffD volEscrD = 0. and points out that the Simplest approximation to this is an arc whose center is offset from the centre point (in the Working position) of the top roll along a horizontal line towards the discharge roll.2 mm Rw = MDT / 2 +1.1 mm Length of vertical line from centre point of top roll (in set position) to top surface of Trash Plate Recommended fibre fill [kg/m3] for a milling train Mill No 7 Mill Tandem 6 Mill Tandem 5 Mill Tandem 1 500.0 875.75 times the feed work opening.75 · woF – l Rs = 658.75 · woF Radius of Trash Plate in working position Rw = 673.3 700. The amount Of the offset is given below.0 2 583.Trash Plate Settings Hugot notes that the ideal shape of a trash plate is the logarithmic spiral. The work opening on the vertical plane through the centre of the top roll is 1.0 3 666.0 500.0 833.0 500.0 625.1 mm Rs = MDT / 2 +1.0 1000.0 750.0 4 5 . Offset Distance from center of top roll to center of radius for trash plate surface Ow = (MDT / 2 + woF) / 25 Ow = 25.0 800.3 600.0 900.7 750. it is necessary in practice to make a compromise. and of course. it is necessary that bearing materials be used which have certain desirable properties. low modulus of elasticity. Amongst these we must include such factors as mechanical strength. b. Since these factors cannot all be obtained to a desirable degree in a single material.0 Mill Bearings Bearing Pressures The maximum pressure that a bearing can withstand is mainly a function of the bearing material. generally in the case of sugar mills. . introduced. The most common bearing materials consist of a. The material of the shaft or journal is established from considerations of strength and rigidity. Standard sugar mill practice limits the bearing pressure to about 10 MPa. softness and low melting point. Separating these two elements is the lubricant. and may or may not be integral with it. white metals. and the shaft or moving member.7 1000. and c. corrosion resistance. copper base alloys. Because the conditions under which bearings must operate in service may vary over a wide range. and will invariably be steel. Economic considerations. by external pressure feeding. Aluminum-base alloys. high thermal conductivity.0 7 1000. Materials for Plain Bearings The two essential elements in a plain bearing are the bearing or bearing material itself. The bearing or bearing material is located in a housing or structure.6 916. The bronzes that are common in sugar mills have a recommended maximum bearing pressures of up to 100 MPa for phosphor bronze and 50 MPa for tin-bronzes. and since such metals are highly competitive. it demands the use of a hardened steel journal. as is required of the Babbitt or white metal bearing materials.025-0.100-0. where high frictional stresses are likely to occur. i. broadly referred to as Babbitt (after Isaac Babbitt.050 mm are used with copper lead over the back-up material.White Metal White metals is a term used to include the tin and lead-base metals. solid units. White metal is not commonly used as a sugar mill bearing material Copper-base Alloys Copper-base alloys including lead-bronze. gun-metal and phosphor-bronze are widely used as bearing materials. and is used for general service bearings. 1839). as bushes without the supporting shell surrounding the bearing material. This alloy also has good resistance to corrosion in sea water. in common with the white metal bearings. having well bearing properties and capable of withstanding Somewhat higher loads than the lead-bronze alloys. Lead bronze bushes are frequently used in the form of single. Gun-metal provides a relatively cheap and easy to machine material. and this reduction is a function of thickness. Because of the high hardness of this material. it is usual to limit the thickness to between about 0. It has a low tendency to seizure. they are recommended for most applications where the loading is not severe.175 mm and thicknesses of only 0. Phosphor-bronze is used for heavily loaded bearings.e. Babbitt bearings are manufactured with the white metal lined onto steel. Typical Sugar Mill Bearings Rein in Cane Sugar Engineering states that typically sugar mill bearings are tin bronzes with the following composition Cu Sn Pb Zn 84% 10% 3% 3% . cast iron and copper base alloys. and has greater fatigue strength to withstand higher temperatures. Lead-bronze is the cheapest. Since white metal suffers a reduction in fatigue strength with increase in temperature. This is achieved by supplying lubricant to the bearing under pressure. The correct precharge pressure which ensures that the top roll floats about its design position is important to ensure good extraction and to protect the mill from damage. The higher the precharge pressure the softer the spring rate. The hydraulic oil in the system is not compressible. This means the mill headstock may be subjected to very high forces. but the gas in the accumulator is and it is this gas that has the give that allows the roll to float. attention must be given to the adequate supply of lubricant at all times. Description SMR SMR MEDIUM CLEAR HEAVY ASMR MEDIUM* ASMR HEAVY* . Sugar Mill Lubricants Castrol SMR Grades Castrol SMR lubricants are especially formulated for sugar mill roll bearings and gearboxes. A low precharge pressure will make the system very stiff and may not allow sufficient float to let tramp iron through the mill. It is usual practice to allow the top roll of a sugar mill to float in the vertical direction to: keep a nearly constant pressure on the mat of bagasse in the mill allow some throughput variation without sacrificing extraction protect the mill from damage from tramp iron Typically hydraulic rams together with a gas accumulator provide the downward force on the bearing caps to resist the upward force of the bagasse on the mill roll. They are viscous black oils fortified with load bearing additives and incorporate emulsifiers to resist the harmful effects of the inevitable contamination with sugar juices encountered in use. They also find use in other heavily loaded open gears and pinions. which may cause damage. A high precharge pressure will make the system very soft and the top roll bearing may continually rise up to its maximum lift. The gas accumulator acts as an air spring. and in particular to the location of oil Supply holes and grooves. These grades are now lead free. The gas in the accumulator is precharged with a particular gas pressure. This together with the allowable bearing pressure mentioned above indicates that the total bearing area should be about 20% to 30% of the projected roll area. Under these conditions. Bearing Loads and Sizes Specific roll loads are in the range of 2 to 3 MN per square metre of projected roll area. Consequently hydrostatic lubrication is required.Lubrication Sugar mill shafts do not turn sufficiently fast for a hydrodynamic film of lubricant to be formed between the journal and the bearing. Bitumen based lubricants are often used in sugar mill bearings. not anticipated in design. 05(moisture % sample) .31.kg-1 The net calorific value.995 1205 1925 1 228 11450 Viscosity @ 100°C (mm2/s) 50. By ASTM standards the HCV is calculated at atmospheric pressure and at 20°C.5 126. In industrial practice it is not practicable to reduce the temperature of the combustion products below dew point to condense the moisture present and recover its latent heat.0 VIE Color Pour Point (°C) Flash Point CCC (°C) Bitumen Compounding EP Additives 84 Black 0 250 Yes Yes 160 Red/Green 6 212 Nil Yes Yes 83 Black 0 254 Yes Yes Yes 74 Black +12 256 Yes Yes Yes Bagasse Calorific Value Gross calorific value. 14(brix % sample)] kJ.5 167. 05(ash % sample) .Density @ 20°C Viscosity @ 40°C (mm2/s) 0.914 0. thus the latent heat of the vapor is not available for heating purposes and must be subtracted from the HCV. LCV of bagasse is calculated by the formula: . also known as the lower calorific value (LCV).196.949 0.952 0.0 50. also known as the higher calorific value (HCV) of bagasse is calculated from the following formula: HCV= [19 605 .196. assumes that the water formed by combustion and also the water of constitution of the fuel remains in vapor form. kg-1 Do online calculations of HCV and LCV.6+68.27 TCH) Bagasse percentage on cane--------------68.27 TCH) Mixed Juice Percentage on cane-------------------238.LCV= [18 309 .27+79.31.6 Tons (227.196.54 tons (227.781 Pipe sizing Use these pages to calculate pipe sizes and pressure drops due to friction in the pipes. Select the parameter to be used as the graphs X-axis by clicking the appropriate radio button.54=238.207. Example: Capacity of the plant---------------------5000 TCD Cane crushing per hour--------------5000/22 =227.181 tons (227. 6 (moisture % sample) . 05 (ash % sample) .27 TCH) Mill Balance calculation: Mill Input=Mill Out put Cane + Imbibitions water=Bagasse + Mixed Juice 227. for the following products: The pressure drop is calculated from the following formula hf = 4·f·le / d · v2/ 2·g where . 14 (brix % sample)] kJ.27 TCH Imbibitions percentage of cane-----------35±2% Bagasse percentage on cane--------------29±1% Mixed Juice Percentage on cane-------------------105±2% As per our capacity of the mill: Imbibitions percentage of cane-----------79.181 306.81≈306. 81m/s2 f = 0.001375 · (1 + (20000· k / d + 106 / Re)1/3) Where k = relative roughness of the bore of the pipe Re = Reynolds Number = ρ·v·d / μ ρ = density µ = dynamic viscosity To be select the imbibitions water pump & motor Specific Speed of Pumps Pumps (and fans) can be characterized by various dimensionless parameters. Specific Speed The specific speed. φ Pressure parameter. hf = head loss due to friction f = friction factor calculated from the formula below le = equivalent pipe length taking into account valves and fittings d = bore of pipe v = average flow velocity g = acceleration due to gravity 9. Π Diameter parameter Δ The most important of these is the specific speed Pump Selection These dimensionless parameters can be used calculate how similar pumps operate under differing conditions (the similarity laws).Nsis given by. ψ Power parameter.5·n/ (g·H)0. Ns Flow parameter.75 Specific speed can also be calculated as follows where φ . Specific Speed. These similarity laws (detailed below) can be used to select a pump given a duty point. Ns = Q0. 5/ψ0.and ψ are defined below Ns = φ0.75 The specific speed of a pump is associated with the impeller shape Low Specific Speed Ns=0.05 Medium Specific Speed Ns=0.10 . High Specific Speed Ns=0. Δ = ψ0.5 Pipe Specifications Each sugar factory needs a pipe specification so that when a pipe is being repaired or a section of plant is being added those implementing the change know exactly which type of pipe. ψ = g·H/n2/D2 Power Parameter The power parameter. flanges. Π is given by. The following are the main types of pipe that will be needed with recommended .25/φ0. ψ is given by.20 Flow Parameter The flow parameter. φ is given by. φ = Q/n/D3 Pressure Parameter The pressure parameter. Δ is given by. Π = φ·ψ·η Diameter Parameter The diameter parameter. gaskets and valves to use. fittings. corrosion allowance and material parameters Sl.pressure. temperature.5 mm 2 mm 3 mm 1.5 mm Material Carbon Steel Stainless steel Carbon Steel Carbon Steel Carbon Steel Stainless steel Full vacuum 100°C to 10 bar g Full vacuum 100°C to 10 bar g pressure Full vacuum 200°C to 3 bar g Full vacuum 130°C to 10 bar g 31 bar g Full vacuum 400°C 100°C Condensates High steam Vacuum pressure Pipe Stress Analysis Why? The reasons one does a pipe stress analysis on a piping system are as follows to comply with legislation to ensure the piping is well supported and does not sag or deflect in an unsightly way under its own weight to ensure that the deflections are well controlled when thermal and other loads are applied to ensure that the loads and moments imposed on machinery and vessels by the thermal growth of the attached piping are not excessive to ensure that the stresses in the pipe work in both the cold and hot conditions are below the allowable How? The model is constructed from piping general arrangement drawings. piping isometric drawings and piping and valve specifications.6 mm 0. Once the system is .no 01 02 03 04 05 06 Product Non food grade Food grade Low steam Pressure Temperature Corrosion Allowance 2 mm 0. encastre or built-in. This information is normally provided by the equipment manufacturer. A seemingly solid gusseted bracket Welded to a house column does not qualify as an anchor if the column does not Have the strength to resist the loads applied to it. Cold pull has no effect on the code stress. rotational or a combination of both. comprehensive stress analysis calculations are done. Cold Pull or Cold Spring This is used to pre-load the piping system in the cold condition in the opposite direction to the expansion. A pipe restraint positioned in line with a neutral plane prevents differential Expansion forces between the pipe and the machine. Anchors A rigid restraint which provides substantially full fixity. i. Neutral Planes of Movement This refers to the planes on the 3 axes of a turbo machine or pump from where expansion of the machine starts eg the fixed end of a turbine casing. Spring Hangers Used to support a piping system that is subjected to vertical thermal movements. modifications to the model are made to ensure compliance with the above requirements. . usually used in Combination with restraints and cold pulls. Ideally allowing neither movement nor bending moments to pass through them. True anchors are usually difficult to achieve. so that the effects of expansion are reduced. The modifications may include one or more of the following tools Restraints A device which prevents. Commercially available single coil spring units are suitable for most applications. taking care to set the boundary conditions. but can be used to reduce the nozzle loads on machinery or vessels. Cold pull is usually 50% of the expansion of the pipe run under consideration.accurately modeled. Restraints can be either directional. If not available from this source.e. resists or limits the free thermal movement of the pipe. the fixed points of the machine must be determined by inspection and an estimation of the turbine growths calculated. Expansion Loops A purpose designed device which absorbs thermal growth. It is important that free horizontal movement of the pipe is not impeded unless horizontal restraint is desired. According to Hooke's law. rods or slippers are used. or where vertical movement is intentionally prevented or directed. Slipppers and rollers must be well designed and lubricated. This variation between cold and hot should be between 25 and 50% of the hot loaded condition. solid supports in the form of rollers. the spring's supporting capacity will vary in direct proportion to the amount of displacement the spring undergoes due to thermal movement.25 Velocity[m/s] 40 24 31 37 46 76 37 46 49 76 .Supplier's catalogues adequately cover the selection of these springs. Fluid Flow Velocities Guidelines for the acceptable ranges of flow velocity for various fluids found in a sugar factory Goodall Description Water for space heating Water for boiler feed Saturated steam Superheated steam Velocity[m/s] 2 3 30 50 4 6 50 100 Hugot Description Superheated steam Saturated steam Exhaust (wet/oily) Bled vapor Vapor under vacuum Suction Water 1 1. Solid Vertical Support In places where vertical thermal movement does not create undesirable effects. 2 1.5 0.5 0.3 Lyle Description Water Superheated steam Dry Saturated steam Wet exhaust steam Moderate vacuum water vapor High vacuum water vapor Velocity[m/s] 1.25 0.15 2.22 46 31 21 46 61 2.25 0.44 61 40 31 61 107 Babcock & Wilcox Description High pressure steam Velocity[m/s] 41 61 .5 2 1.1 1.5 0.75 0.25 1.Juice Syrup Molasses Massecuites Delivery Water Juice Syrup Molasses Massecuites 1 0.75 0.2 1 0.2 0. 3. in special cases Saturated Steam.0 . Discharge Condensate Heating circulation Steam Saturated Steam.0 .65 3.5 ft/s 1.54 76 3.5 .2.8 ft/s 82 .6.3 .6 .8.40 .3.5 .8.5 1. Suction Boiler feed water.5 .0 m/s 25 .3 .1 .Low pressure steam Water general 61 2.6 0.0 1.2 pressure) Discharge line for booster pump 1.25 m/s .3 Suction lines for pump (low 0.2 3.2 3.60 30-40 .8.0.82 ft/s -1.2.9.2.81 From a source on the internet Maximal velocity in pipes Water Tap water (low noise) Tap water Cooling water Boiler feed water.2. at peak load Steam / Water emulsion Oil Suction lines for pumps m/s 0.6.50 .0.3 4.5 0.5 1.5 3.164 .0 . medium and low pressure Saturated Steam.1.3 .1.6 -8.0 Discharge line for burner pump Air .197 99 .2.2 4.0 .0 m/s ft/s .5 .3. high pressure Saturated Steam.5 .2 1.7 1.9 .0 1.0.0.131 .3 .131 .3 .9 . 1.8 .8 2.13 6.3 .8.15 15 .Combustion air ducts Air inlet to boiler room Warm air for house heating Vacuum cleaning pipe Compressed air pipe Ventilation ducts (hospitals) 12 .49 49 .5 6 6 4.0 .30 1.3 26 .9.82 9.0 10 .13 Ventilation ducts (office buildings) 2.5 Valves Liquid ft/s 30 25 20 20 15 Steam or Gas m/s 120 90 75 70 55 Steam or Gas ft/s 400 300 250 225 175 mm 15 .5 .6 .8 .20 1-3 0.98 5.66 3.8 .5.25 40 .0 .9 .49 66 .15 20 .4.16 16 .50 65 .0 .0 5.4.3.200 250 – 400 Angle .100 150 .low) Boiler with modulating burner (3:1) To keep the surface free from soot the velocity should always exceed .26 31 .0 .13 .4 40 .15 ft/s .0 8 .4.25 3.0 It is recommended that the maximum inlet velocities applied to control valves should be as shown in the tables below Gate Valve Size Liquid m/s 9 7.5 Exhaust gas m/s Ducts at minimum load Stack at minimum load Boiler with one-step burner (on off) Boiler with two-step burner (high . the pressure cannot fall below the vapor pressure at the temperature concerned.Cavitation is likely to occur on the inlet side of a pump particularly if the pump is situated at a level well above the surface of the liquid in the supply reservoir. For the sake of good efficiency and the prevention of damage to the impeller. The intense pressures.5 9 7. This alternate formation and collapse of vapor bubbles may be repeated with a frequency of many thousand times a second.Since cavitation begins when the pressure reaches too low a value.25 40 . and particularly at those where high velocity and high elevation are combined.5 12 10. it is likely to occur at points where the velocity or the elevation is high. . even though acting for only a very brief time over a tiny area. Not only is cavitation destructive: the larger pockets of vapor may so disturb the flow that the efficiency of a machine is impaired. Any solid surface in the vicinity is also subjected to these intense pressures. Everything possible should therefore be done to eliminate cavitation in fluid machinery. Although air cavitation is less damaging than vapour cavitation to surfaces. when cavitations occurs in a turbine or pump it may sound as though gravel were passing through the machine.Size mm 15 . In a liquid. The liquid moving from all directions collides at the centre of the cavity. Parts of the surface may even be torn completely away. If at any point the vapor pressure is reached. thus giving rise to very high local pressures (up to 1 GPa). it has a similar effect on the efficiency of the machine. aided perhaps by corrosion.400 m/s 13. to ensure that at every point the pressure of the liquid is above the vapour pressure. When the liquid has air in solution this is released as the pressure falls and so air cavitation also occurs. These bubbles are carried along by the flow. the liquid boils and small bubbles of Vapor form in large numbers. that is.100 150 .50 65 . can cause severe damage to the surface. the pressures are propagated from the cavities by pressure waves similar to those encountered in water hammer. regions in which the pressure falls to values considerably below atmospheric. and so the surface becomes badly scored and pitted. because. even if the cavities are not actually at the solid surface. The material ultimately fails by fatigue.200 250 . Associated with cavitating flow there may be considerable vibration and noise. A cavity results and the surrounding liquid rushes in to fill it. however. and on reaching a point where the pressure is higher they suddenly collapse as the vapor condenses to liquid again. on the low-pressure side of the runner.5 ft/s 45 40 35 30 25 m/s 135 105 90 85 70 ft/s 450 350 300 275 225 Cavitations in Centrifugal Pumps There may be. cavitation should be avoided. hf = pmin /ρg + v12 /2g where v1 is the fluid velocity at the point where the static pressure has its least value pmin is the minimum static pressure z1 the elevation of the surface of the liquid in the reservoir above this point where the static pressure has its least value p0 the absolute pressure at that surface p0 = pgauge + patm ρis the density of the fluid at its operating temperature hf is the head loss due to friction in the suction line.Applying the energy equation between the surface of liquid in the supply reservoir and the entry to the impeller (where the pressure is a minimum) we have. Re-arranging the above equation gives pmin /ρg = p0 /ρg .v12 /2g + z1 For cavitation not to occur pmin > pv where .hf . for steady conditions p0 /ρg + z1 . care must be taken to include the effect of all devices such as strainers and valves in the suction line. v12 /2g + z1 > 0 A parameter called Nett Positive Suction Head (NPSH) is defined as NSPHa = p0 /ρg . We can consider the following points to select the pipe size: Density is a physical characteristic. It is a measurement of the amount of matter in a given volume of Something.6 Tons (227.no 01 Product Food grade Pressure Temperature Corrosion Allowance 0.5 mm Material Stainless steel Full vacuum to 100°C 10 bar g So.pv is the vapour pressure of the liquid.hf + z1 The NPSH available at the inlet flange of the pump can be calculated from the above equation. These equations can be rearranged to give the criterion for no cavitation in the pump suction line. The higher an object's density.pv /ρg .27 TCH) So selection of the pipe materials as per the reference of the table above Sl. p0 /ρg . The pump curves in the pump catalog generally give the NPSH required at each volume flow the pump is required to do. and is a measure of mass per unit of volume of a Material or substance.pv /ρg . The average density of an object equals its total mass divided by its . the higher its mass per unit of volume. we can select the pipe line material is Stainless steel. For good pump operation NPSHavailable > NPSHrequired Mixed Juice Percentage on cane-------------------238.hf . This data is taken from multiple sources including Hugot and Tromp Sugar Cane lb/ft3 kg/m3 200.2 400.1785 g/L = 0.0001785 g/mL.1785 kg/m3 = 0.000.4 120.5 .0001785 kg/L = 0. A denser object (such as iron) will have less volume than an equal mass of some less dense substance (such as water).000 kg/dm3 = 1.000 g/cm3 = 1. tangled and tamped 12. Density of Sugar Factory Products The tables below give the approximate range of densities for selected cane factory products.0001785 kg/dm3 = 0. neatly bundled Billeted cane 25 22 Whole stick tangled cane but loosely 10 tipped into cane carrier Knifed cane Shredded cane Bagasse exiting the final mill 18 20 7.3 320.0001785 g/cm3 = 0.000 kg/L = 1. Water is the reference with its highest density at 3.water .000 g/mL.total volume.5 down as in a cane transport vehicle Whole stick cane.noble gas Copper has a density of 8950 kg/m3 = 8.000 cm3.1 Whole stick cane.5 352.2 288. Water has a density of 1000 kg/m3 = 1000 g/L = 1. Density Examples: Solid . 1 m3 = 1. Helium has a density of 0.4 160.95 kg/dm3 = 8.98 °C (ρ = 1 g/cm3) and the correct SI unit of ρ = 1000 kg/m3.95 g/cm3. 2250 1.0582 1.1117 1.2 1586.9 ρ [kg/m3] 1. evaporators.9 294. the table below is the International Standard Atmosphere adapted from Thermodynamic and Transport Properties of Fluids arranged by GFC Rogers and YR Mayhew.2 297. 3rd edition International Standard Atmosphere Z [m] -2500 -2000 -1500 -1000 -500 0 500 1000 1500 2000 2500 p [Pa] 135210 127780 120700 113930 107480 101325 95460 89880 84560 79500 74690 T [K] 304. barometric condensers and in NPSH calculations for pumps it is necessary to know the atmospheric pressure.5473 1.9570 .1673 1.2 271.4 275. there are those that are at higher altitudes where atmospheric pressure is below the well known 101325 Pa for sea level there are tables of atmospheric pressure variation with altitude.7 278.4 301.0066 0.Bagasse stacked to 2 metre height 11 (moisture = 44%) Sucrose crystal Amorphous sucrose Bulk white sugar Bagged white sugar Raw sugar (96° Pol) in a pile Bagged raw sugar 99. While many cane sugar factories are close to the sea.7 56.4782 1.9 281.0 94.7 880 700 900 680 The International Standard Atmosphere For the design of pans.1 54.4 288.2 42.4 176.9 43.7 291.4114 1.3470 1.15 284.2849 1.2 1507. 8 0.001321598·(Z/1000)2) p = ρ·R0/M·T where T is temperature in Kelvin ρ is density in kg/m3 p is pressure in pascals Z is altitude (above mean sea level) in meters R0 is the universal gas constant = 8134.8194 0.7770 0.3 220.006492255 · Z ρ = 1.8634 0.7 265.4136 0.3886 0.2 258.7 226.9647 kg/kmol Water Pipe Sizing Water Properties Temperature Pressure °C bar abs .9 255.4 262.0.6602 0.2 233. pressure can then be calculated from the universal gas law.9 242.7365 0.6243 0.4958 0. T = 288.5 223.4397 0.5901 0.15 .9093 0.2 245.3648 Tables are not convenient for computer calculations: regression formulae have been prepared from the above data for temperature and density.4 J/kg/K M is the molar mass of air = 28.09543718·(Z/1000) .5573 0.4671 0.5258 0.7 252.4 249.225 · e(-0.5 236.6975 0.0 229.3000 3500 4000 4500 5000 5500 6000 6500 7000 7500 8000 8500 9000 9500 10000 10500 11000 70120 65780 61660 57750 54050 50540 47220 44080 41110 38300 35650 33150 30800 28580 26500 24540 22700 268.0.7 239.0 216. Mass Flow ton/h Max Flow Velocity m/s Pipe System Type Description Short Radius 90º Bends Long Radius 90º Bends Short Radius 45º Bends Tees .Line Flow Tees .Branch Flow 180º Return Bends Gate Valves (Fully Open) Globe Valves (Fully Open) Angle Valves (Fully Open) Butterfly Valves (Fully Open) Ball Valves (Fully Open) Plug Valves (Fully Open) Swing Check Valves Wafer Check Valves Numbers/Length The above are consider to be select the pipe size: . Example: Mixed Juice Temperature Pressure Mass Flow Max Flow Velocity 45 °C 5 bar abs 238.6 ton/h 1.Line Flow Tees .Branch Flow 180º Return Bends Gate Valves (Fully Open) Globe Valves (Fully Open) Angle Valves (Fully Open) Butterfly Valves (Fully Open) Ball Valves (Fully Open) Plug Valves (Fully Open) Numbers/Length 60mtrs 5 2 2 0 0 0 4 0 0 0 0 0 .2 m/s Type Description Pipe length Short Radius 90º Bends Long Radius 90º Bends Short Radius 45º Bends Tees . 3 m3/h 0.0 ton/h 990.0°C 238.Swing Check Valves Wafer Check Valves 0 0 Water Pipe Sizing – Results Water Temperature Mass Flow Density Viscosity Volume Flow Flow Velocity Frictional Head Loss Pipe Size Short Radius 90° Bends Long Radius 90° Bends Short Radius 45° Bends Tees .9 m/s 0.s 240.4 m DN300 5 2 2 0 0 0 4 0 0 0 0 0 0 Steam Pipe Sizing Steam Properties Temperature Pressure Mass Flow Max Flow Velocity Pipe System °C bar abs ton/h m/s .4 kg/m3 0.Branch Flow 180° Return Bends Gate Valve (Fully Open) Angle Valve (Fully Open) Butterfly Valve (Fully Open) Ball Valve (Fully Open) Plug Valve (Fully Open) Swing Check Wafer Check 45.Line Flow Tees .6 mPa. Branch Flow 180º Return Bends Gate Valves (Fully Open) Globe Valves (Fully Open) Angle Valves (Fully Open) Butterfly Valves (Fully Open) Ball Valves (Fully Open) Plug Valves (Fully Open) Swing Check Valves Wafer Check Valves Numbers/Length Example Evaporator Steam Inlet Pressure—3kg/cm² Temperature----120°c Flow rate---35 t/hr Saturated steam velocity----50 .Type Description Short Radius 90º Bends Long Radius 90º Bends Short Radius 45º Bends Tees .Line Flow Tees . Branch Flow 180º Return Bends Gate Valves (Fully Open) Globe Valves (Fully Open) Angle Valves (Fully Open) Butterfly Valves (Fully Open) Ball Valves (Fully Open) Plug Valves (Fully Open) 60mtrs 5 3 0 0 0 2 0 0 0 0 0 .Line Flow Tees .Steam Properties Temperature Pressure Mass Flow Max Flow Velocity Pipe System 120 °C 3 bar abs 35 ton/h 50 m/s Type Description Numbers/Length Pipe length Short Radius 90º Bends Long Radius 90º Bends Short Radius 45º Bends Tees . 6 m/s 12.7 m3/s 49.0 bar abs 35.9 µPa.s 5.Swing Check Valves Wafer Check Valves 0 0 Steam Pipe Sizing – Results Steam Temperature Steam Pressure Mass Flow Specific Volume Viscosity Volume Flow Flow Velocity Frictional Pressure Loss Pipe Size Short Radius 90° Bends Long Radius 90° Bends Short Radius 45° Bends Tees .6 m3/kg 12.6 kPa DN400 0 5 3 0 0 0 2 0 0 0 0 0 = m Line Frequency=50Hz/60Hz Example: .Branch Flow 180° Return Bends Gate Valve (Fully Open) Angle Valve (Fully Open) Butterfly Valve (Fully Open) Ball Valve (Fully Open) Plug Valve (Fully Open) Swing Check Pump selection The following data can required the pump selection Pump duty Volume flow= ______________m3/h Head Density = kg/m3 120.0 ton/h 0.Line Flow Tees .0°C 3. 2 8.3 58.5 Eff Op [kW] 8.9 Power Installed Power [kW] 11 11 11 15 .0 73.4 9.4 kg/m³ Line Frequency=60 Hz Selection Speed [rpm] 3546 1773 1182 887 Pump Size No Selection 125-315 No Selection No Selection Imp [mm] 150 267 387 507 Dia Max [%] 76.1 9.0 Eff Op [kW] 8.2 8.8 68.5 10.8 72.0 65.8 63.6 Power Installed Power [kW] 11 11 11 15 Mixed Juice: 238 tons/hr Volume Flow: 238tons/hr (or) m³/h Head= 30 m (approx) Density=320.7 9.4 kg/m³ Line Frequency=50 Hz Selection Speed [rpm] 2955 1478 985 739 Pump Size No Selection 150-315 No Selection No Selection Imp [mm] 173 315 459 604 Dia Max [%] 75.Mixed Juice: 238 tons/hr Volume Flow: 238tons/hr (or) m³/h Head= 30 m (approx) Density=320. Liquid . This hot condensate is too hot for imbibitions duty. The obvious product to cool it against is the mixed juice from the mills. for two reasons. hot imbibitions releases waxes from the canes causing the mills to slip during the winter months hot imbibitions can cause clouds of mist in the mill house which reduces visibility (a safety hazard) This hot condensate must be cooled before it can be used as imbibitions. Hence a liquid liquid heater Cane throughput Fibercon Brix%Cane Imbibition%Fibre in Cane Moisture%Bagasse Brix%Bagasse Imbibition Temperature (into heater) Imbibition Temperature (out of heater) Juice Temperature (into heater) Mixed Juice Purity Tube Length OHTC TCH % % % % % °C °C °C % m kW/m2K Example: . often contaminated with sugar and not suitable for boiler feed water.Liquid Heater Rapid Design Usually imbibitions water is hot condensate from the process house. Cane throughput Fibercon Brix%Cane Imbibition%Fibre in Cane Moisture%Bagasse Brix%Bagasse Imbibition Temperature (into heater) Imbibition Temperature (out of heater) Juice Temperature (into heater) Mixed Juice Purity Tube Length OHTC 227TCH 15% 15% 300% 50% 2% 95°C 70°C 35°C 85% 3.9°C 95.8m 0.4kW/m2K Basic Data 258.2t/h 102.2t/h 35.8m 2978.0°C 42.1°C 3.0°C 44.5kW Juice Flow Imbibition Flow Juice Inlet Temp Juice Outlet Temp Imbibition Inlet Temp Imbibition Outlet Temp LMTD Tube Length Heat Flux .0°C 70. 8 2.9 1. air in the heating steam air in the cooling water Quantity of Air to be Removed A number of authors have expressed an opinion on the the amount of incondensable gas to be removed from the condensers.9m2 Design Options The following table gives a number of options that should provide an acceptable design of liquid liquid heater Tube Dia 35 42 42 54 76 Tubes per Pass 37 31 37 19 7 Passes 13 13 11 16 29 Flow Velocity 2.5 Vacuum Equipment Purpose of the Vacuum Equipment The vacuum equipment's function is to remove the incondensable gases that find their way into the vapour stream. inherently in the juice.3 1. Sadly.Heating Surface 176.6 1. the quantities of air to be removed as . and as is typical there is little agreement among them. The incondensable gases come from the following sources: leakage of air into the vessels. 345·V. Graver. leakage of air [kg/h] = 0. The separation takes place by allowing the solid particles to settle out onto a tray. The benefits of the single tray short retention clarifier are: Short retention time. as a tray less clarifier). Bach and RapiDorr were popular.follows. but the SRI clarifier is almost standard for all new installations.035·mw. These solids originate from sand adhering to the cane stalks as well as from material inherent in the cane stalk. hence less sucrose destruction. and color formation Higher throughput capacity Lower capital cost Lower maintenance cost Easy to liquidate and hence regular cleaning is possible Flocculent usage and operability appear to be no different from multitray clarifiers Design The main design parameters are up flow velocity and the residence time Up flow Velocity The up flow velocity is calculated as half the initial settling rate of the mud in the juice. The SRI clarifier is a single tray clarifier (also known. The solids are swept from the tray into a mud compartment. oddly. where V is the volume of the vessel [m3] air in the juice [kg/h] = 0. characterized by short juice retention times (usually 40 minutes or less).1·mj. The initial settling rate is the slope of the steeply downward sloping part of . In the past multitray clarifiers. where mj is the flow of juice [t/h] air in the cooling water = 0. such as the Dorr. where mw is the flow of cooling water [t/h] air in the heating steam is not counted Juice Clarifiers Introduction A clarifier is used to separate out the solids suspended in the cane juice. from which it is pumped to filters for desweetening and dewatering. the up flow velocity can be assumed in the range 65 to 80 mm/min (Most SRI clarifiers in South Africa operate with an Up flow velocity below 72mm/min). and packing for . Sizing Given the volumetric juice flow and the above two parameters. Residence Time The residence time is usually on the range of 40 to 45 minutes. inspection and testing. Evaporators And Juice Heater Tubes Less Than Three Meters Long Scope This specification covers the material selection. the cross sectional area (hence diameter) and the operating depth of the clarifier can be calculated Specification for Vacuum Pan. In the case of a Greenfield project where the settling characteristics of the mud are unknown.the settling curve below. heat treatment. dimensional tolerances. marking. surface condition. The tube ends shall be cut square and deburred. with a longitudinal welded seam Code of Manufacture The tubes shall be manufactured.tubes that will be installed in vacuum pans. Quantities and Sizes Number of tubes required: Length of tube required: Nominal outside diameter of tubes Wall thickness of tubes Material The tubes shall be of TP304L stainless steel. The inspection and testing will be done using an independent inspection authority. Inspection and Testing The tubes shall be inspected and tested in accordance with ASTM A269. at the client's cost. Marking Each shall be marked in accordance with ASTM A269 and in addition shall bear the . evaporators and juice heaters in which the tubes are less than three meters long. This can be achieved either by pickling or bright annealing. inspected and tested in accordance with ASTM A269 Standard Specification for Seamless and Welded Austenitic Stainless Steel Tubing for General Service Dimensional Tolerances The dimensional tolerances shall be in accordance with ASTM A269 Heat Treatment The heat treatment shall be in accordance with ASTM A269 Surface Condition The external and internal weld bead shall be made flush. The tubes shall be supplied free of mill scale. following marks Sugartech Specification Packing The tubes shall be packed in bundles with wooden frames to protect the tube ends. with a longitudinal welded seam Code of Manufacture The tubes shall be manufactured. surface condition. marking. Specification for Vacuum Pan. A means of lifting the bundle. dimensional tolerances. The bundles shall be strapped and shrink-wrapped in plastic. and packing for tubes that will be installed in vacuum pans. inspected and tested in accordance with ASTM A268 Standard Specification for Seamless and Welded Ferritic and Martensitic Stainless Steel Tubing for General Service Dimensional Tolerances The dimensional tolerances shall be in accordance with ASTM A268 Heat Treatment The heat treatment shall be in accordance with ASTM A268 . in a way that will not damage the tubes. Evaporators And Juice Heater Tubes More Than Three Meters Long Scope This specification covers the material selection. evaporators and juice heaters in which the tubes are more than three meters long. Quantities and Sizes Number of tubes required: Length of tube required: Nominal outside diameter of tubes Wall thickness of tubes Material The tubes shall be of TP439 stainless steel. inspection and testing. heat treatment. shall be provided. at the client's cost. shall be provided. The bundles shall be strapped and shrink-wrapped in plastic. The inspection and testing will be done using an independent inspection authority. Inspection and Testing The tubes shall be inspected and tested in accordance with ASTM A268. Marking Each shall be marked in accordance with ASTM A268 and in addition shall bear the following marks Sugartech Specification Packing The tubes shall be packed in bundles with wooden frames to protect the tube ends. The tubes shall be supplied free of mill scale. in a way that will not damage the tubes. evaporators and pans are easy to expand into the tube plate corrosion resistant similar co-efficient of thermal expansion to the shell of the vessel have a good heat conductivity have a smooth and bright inside surface: a very low surface roughness favors a higher flow of the juices have a long life have a good cost : benefit ratio The choice material is between: mild steel copper (or brass) . Sugar Factory Tubes for Heating. This can be achieved either by pickling or bright annealing. Evaporating and Crystallizing Some desirable characteristics of tubes for juice heaters.Surface Condition The external and internal weld bead shall be made flush. The tube ends shall be cut square and deburred. A means of lifting the bundle. Full immunity to stress corrosion. The coefficient of thermal expansion for 304 is 1. inter-crystalline corrosion resistance. Tubes of 304 stainless steel should always be annealed after welding.8×10-2 mm/m/°C which is substantial more than that of carbon steel. 304 for shorter tubes and 439 for longer tubes. Coefficient of thermal expansion (in the range 0°C . When the vessel is hot the thermal stresses in the tubes will be high. pitting corrosion resistance.100°C) is 1. 439 Stainless Steel ASTM TP439 is a titanium stabilized ferritic grade of stainless steel (17-19% Cr) which is recommended for long evaporator or pan tubes (in excess of 5m long) Advantages of grade 439 fully ferritic metallurgical structure (ensured by the titanium stabilization) very good weld ability and ductility. Carbon Steel If it is decided that carbon steel tubes are to be used the recommended specification is BS3605 Gr 320 304 Stainless This grade of stainless steel can be used where the tube length is less than three meters. austenitic stainless steel (types AISI 304 and / or 316) special alloys (with higher chromium / nickel contents) ferritic stainless steel In practice the choice is between mild steel.02×10-2 mm/m/°C Stress corrosion cracking This type of corrosion occurs when . 304 stainless steel or 439 stainless steel. Carbon steel is not recommended because in the long run (a period of say 20 years) carbon steel tubes work out more expensive. This variation depends on the manufacturing process and on .: 26 vs. For vacuum pans with 100 mm diameter tubes the recommended wall thickness is 1.e.50 mm is quite sufficient (even on longer lengths up to 11 m) Tubes with 2. The risk will be higher if tubes over 7 meters in length (some designs of continuous pans. 316 or 316L) i. Falling-film evaporators and Kestner evaporators). Ferritic stainless steels are immune to stress corrosion cracking Heat transfer Thermal conductivity of ferritic stainless material is 40% higher than that of austenitic grades (like 304.6 or 1. Recommended Wall Thickness For evaporators and heaters. pan or juice heater under the above conditions the result will be cracks leading to breakage in the area near the tube plate.2 mm is acceptable. 304L. 15 watt/metre/°C.75 mm are recommended for those tubes located near Steam-entrance and subject to some vibration during the process. A susceptible material is subject to mechanical stress in a corrosive environment In an evaporator. for tubes longer than five meters a wallthickness of 1.6 mm clearance between tube and plate. with tube length less than five meters a wall thickness of 1. The danger of stress corrosion cracking exists in virtually all evaporators.6mm.Allow 0. Tube Hole Tolerances and Clearances The following definitions will help explain the calculation of hole clearances Tolerance Is the amount by which the actual size of the hole or tube varies from the nominal size.0 mm would be harder to swage into the holes and would require a 600°C Pre-heating of tube ends.5 or 1. Wall-thickness 1. 0%. But as noted above this will be a range.2%. Clearance Is the difference in size between the hole and the tube. Tolerances The tube OD tolerances depend on the tube manufacturer and his equipment and process.The maximum clearance shall be such that the tube material is not strained more than 2. See graph below (from Thum and Micleots) . the strain has exceeded the yield point. rather a 0.2% proof strain is regarded as the yield criterion. that is. The minimum clearance should be such that the tube material once expanded into the tube undergoes plastic deformation.3% strain for no good reason other than it is greater than 0. Because there is a maximum and a minimum tube outside diameter and a maximum and a minimum hole diameter there will be a range of clearances. The criterion set for minimum clearance is thus 0.random errors. Clearances The designer of a vessel can control the clearance between tube OD and tube sheet hole diameter. In most stainless steels there is no definite yield point. The best we can do is specify tolerances the manufacturer can achieve at a reasonable cost. In the same way the tube sheet hole tolerances are a function of the hole making process. 23 mm. The tube OD Tolerance is given by the manufacturer as +/. Tube nominal diameter Dtnom = 50. but they have proved themselves in practice in a number of Different types of vessels.It must be noted that both the minimum and maximum clearance criteria are Somewhat arbitrary.8 mm Tube OD tolerance told = 0.told . Practical Application Kestner evaporator tube For this example we will consider a 2 in nominal diameter tube.23 mm Minimum tube diameter Dtmin = Dtnom .0. say 0.000 +0.300 mm Minimum hole size Dhmin = Dhnom + 0.48 mm . The H12 tolerance is +0. the tube hole diameter is 51.2%.30% Diametral dilation Δd = ε Dtnom Δd = 0.57 mm Maximum tube diameter Dtmax = Dtnom + told Dtmax = 51.152 mm Nominal hole diameter Dhnom = Dtmax + Δd Dhnom = 51.18H12.18 mm The hole is going to be drilled and an ISO tolerance of H12 is achievable i.18 mm Maximum hole size Dhmax = Dhnom + tolh Dhmax = 51.300 Tube hole tolerance tolh = 0.03 mm In order to get plastic deformation of the tube as it is expanded it must be strained more than 0.3% Diametral strain ε = 0.Dtmin = 50.e.000 mm Dhmin = 51. Okay Maximum clearance Cl max = Dhmax .Okay Continuous vacuum pan tube In this example we will consider a 4 in nominal diameter tube.15 mm Minimum diametral strain εmin = Clmin / Dtnom εmin = 0.Dtmin Cl max = 0.38 mm Minimum tube diameter Dtmin = Dtnom .38 mm.3% .91 mm Maximum diametral strain εmax = Cl max / Dtnom εmax = 1.Check We will now check that the calculated clearances meet our criteria set above Minimum clearance Cl min = Dhmin .0.Dtmax Cl min = 0. Tube nominal diameter Dtnom = 101.796% . The tube OD Tolerance is given by the manufacturer as +/.6 mm Tube OD tolerance told = 0.22 mm Maximum tube diameter Dtmax = Dtnom + told .told Dtmin = 101. 305 mm Nominal hole diameter Dhnom = Dtmax + Δd Dhnom = 102.Dtmax = 101.350 Tube hole tolerance tolh = 0.30% Diametral dilation Δd = ε Dtnom Δd = 0.2%.28 mm The hole is going to be drilled and an ISO tolerance of H12 is achievable ie the Tube hole diameter is 102.000 mm Dhmin = 102.3% Diametral strain ε = 0.000 +0.98 mm In order to get plastic deformation of the tube as it is expanded it must be Strained more than 0. say 0.28H12.63 mm Check We will now check that the calculated clearances meet our criteria set above Minimum clearance . The H12 tolerance is +0.28 mm Maximum hole size Dhmax = Dhnom + tolh Dhmax = 102.350 mm Minimum hole size Dhmin = Dhnom + 0. Provide a crash stop in order to avoid swelling of the tubes just inside the plate-level. 5. If necessary it must be repaired adequately. Sugar Factory Tubes Sheet Ligaments The ligament on a tube sheet is the material between two tube holes.3% . 6. When expanding tubes into plates it is essential to start at the top of the vessel surplus of 5 mm (3/16") must be kept. 4. In a perfect . It is necessary to protect tubes near the steam entrance.Okay Tube Installation Points to note when expanding tubes into tube plates 1. 3. make sure that the surface of the bottom plate is quite clean and smooth. One must ensure that tube ends remain exposed above the tube plates. 2.393% .41 mm Maximum diametral strain εmax = Cl max / Dtnom εmax = 1.Okay Maximum clearance Cl max = Dhmax .Dtmin Cl max = 1. When replacing tubes in plates.Dtmax Cl min = 0. Five-roller expander with safety clutch should preferably be used instead of usual three-finger expander. Baffles should be built in.30 mm Minimum diametral strain εmin = Clmin / Dtnom εmin = 0. Ends of expanded tubes must never be welded to tube plates. This will avoid thermal shock and mechanical stresses which might be especially high at this particular part of the vessel.Cl min = Dhmin . 330 1.054 0.500 0.380 1.313 0.375 0.World the all the ligaments on a tube sheet will be exactly the same size.250 0.259 0.250 0.813 0. The Tubular Exchanger Manufacturers Association (TEMA) has guidelines on Minimum allowable ligaments on tube sheets.510 0.075 0.310 1.250 1.156 0.635 nominal ligament [inch] p-dh 0.250 1.625 p 0.146 0.500 0.090 0.125 0.510 0.146 0.500 0.116 0. tube dia tube pitch [inch] [inch] maximum hole diameter [inch] p/d t 1.178 0. However Due to the variation in hole size due to tolerance and also due to mistakes in hole Centre positioning there may be ligaments which are smaller than the theoretically Calculated ligament.625 0.375 0.500 0.060 0.090 . Now if it is found that on a particular tube sheet one or more Of the ligaments is smaller than the others are we to reject the tube sheet and all The work done on it? If the tube sheet is rejected.060 0.156 0.063 0.075 0.510 0.188 0.420 1.147 0.060 0.781 0.188 dh 0.635 0.531 0.500 1.025 0. Unfortunately their Recommendations only go up to 2 inch OD tubes.178 minimum permissible ligament [inch] dt 0.384 0.384 0. and costs incurred. the manufacturing Programme Will be delayed.688 0.075 0.300 p-d t 0.125 0.250 1.156 0.625 0.125 0.656 0.259 0. and so some extrapolation for 4 Inch tubes are required.115 0.116 0.375 0. 500 1.030 in) Where t = tube sheet thickness Minimum Permissible Ligament No ligament shall be less than ligmin = -0.209 0.000 1.063 1.188 1.000 1.219 0.000 1.125 1.375 1.360 1.(0.313 0.760 0.250 1.760 0.250 0.875 2.518 2.303 0.0032 t / dt in + 0.150 0.760 0.313 0.750 0.357 0.885 1.250 0.365 0.290 1.185 0.875 0.330 1.303 0.430 1.240 0.299 0.185 0.090 0.301 0.25 1.120 0.120 0.400 1.875 0.313 0.105 0.150 0.500 1.240 0.250 1.264 1.250 0.250 0.250 1.478 0.022 0.375 0.885 0.375 0.760 0.365 0.125 1.885 0.000 1.012 1.250 0.313 1.0.250 1.875 0.635 0.625 0.875 0.094 1.178 0.375 0.750 0.150 0.120 0.420 1.dh .363 0.250 1.563 1.0010465 + 0.238 0.310 1.750 0.250 1.188 0.000 0.313 0.120 0.185 0.500 0.012 1.375 0.250 1.500 2.750 0.180 0.250 Standard Ligaments 96% of ligaments shall be greater than ligstd = p .875 1.240 0.510467 · (p-dh) The factors in the above formula come from a linear regression of the data in the .885 0.380 1.150 0.012 1.938 1. 0010465 mm + 0.030 in) lstd = 17.0016 in · t / dt toldd = 0.8 mm Maximum tube hole dia dmax = 51.(2 · toldd + 0.Table above.72 mm Minimum ligament lmin = 0.48 mm Tube hole pitch p = 70 mm Drill drift tolerance toldd = 0.dmax .5067383 · (p . Example 1 In this example we consider a 2 in kestner evaporator type tube Tube plate thickness t = 25 mm Tube outside diameter dt = 2 in dt = 50.38 mm Example 2 In this example we consider a 4 in continuous vacuum pan type tube Tube plate thickness t = 25 mm Tube outside diameter .02 in Standard ligament lstd = p .dmax) lmin = 9. Desuperheating of steam is an almost universal feature of a sugar factory. usually by spraying atomized droplets of water into The flow of superheated steam.5067383 · (p . Superheated steam is steam that is at a Temperature above its saturation temperature.dt = 4 in dt = 101.63 mm Tube hole pitch p = 120 mm Drill drift tolerance toldd = 0.dmax) lmin = 8.(2 · toldd + 0.030 in) lstd = 16.dmax .01 in Standard ligament lstd = p .59 mm Minimum ligament lmin = 0.6 mm Maximum tube hole dia dmax = 102.78 mm Desuperheating of Steam A desuperheater is a device that cools superheated steam to a temperature close to its saturation temperature.0010465 mm + 0. This is for two reasons Steam turbines are generally designed to leave some superheat in their exhaust to prevent erosion of turbine blades by water droplets Juice and syrup should be boiled at less than about 125°C to reduce color formation and sucrose destruction .0016 in · t / dt toldd = 0. while the loss in molasses varies a lot.hw) Symbols m --mass flow rates [kg/s] h -. It is quite clear that the losses in bagasse and filter cake are almost constant.enthalpy [kJ/kg] Subscripts w --cooling water s1 --steam upstream of the desuperheater s2 --steam downstream of the desuperheater Sucrose Losses in a Cane Sugar Factory The data below are the industry average figures from South African factories as published in SASTA Procedings.There are numerous methods of desuperhing steam each with their own advantages and disadvantages: a good discussion on the various approaches to Desuperheating is given by Sprirax Sarco Theory A heat and mass balance over the desupeheater yield two equations ms2hs2 = ms1hs1 + mwhw ms2 = ms1 + mw Combining these yields mw = ms1 · (hs1 . The figures given in the table and graph below are as a percentage of the sucrose entering the factory in cane. the undetermined loss is fairly stable from year to year . The losses in 1993 and 1994 were high as a result of the drought at that time.hs2) / (hs2 . 48 1992 2.64 Undetermined 1.40 0.98 13.26 1.23 15.25 11.19 0.27 9.31 2.96 Total 14.85 13.27 Molasses 9.26 8.33 0.25 0.05 0.27 8.78 1990 2.94 1993 2.33 1991 2.29 9.24 1989 2.02 1.98 .Sucrose losses as a percentage of sucrose entering the factory Bagasse 1988 2.37 Filter Cake 0.76 1.92 13.86 1.76 12. 18 9.13 2.86 1995 2.25 1.25 9.99 13.23 8.25 0.14 2004 2005 Average Sulphitation Part I Sulphitation processes are subject to almost as many modifications as simple Defecation.91 2000 2.21 2.21 0.67 1. stepwise heating).81 14. fractional procedures). and .87 12.40 2.95 1.29 16.24 9.26 0.15 16.25 12.07 0.90 1999 2.28 0.99 13.27 0.37 2.31 0.25 0.65 9.04 0.1994 2.07 2.48 9.05 1997 2.22 10.00 13.97 12.02 2.96 9. simultaneous addition of lime and gas.17 0. temperature modifications (sulphiting cold or hot.73 13.97 2. sulphiting first.22 11.13 0.84 1.29 2.10 13. modifications of the sequence of addition of lime and SO2 (liming first.18 8.25 9.15 0.50 2001 2.45 1.71 2003 2. The variations may include the following: 1.33 1996 2.62 1. 2.77 14.96 1.73 1.01 15.18 1998 2.92 13.19 9.80 2002 2.14 0. 0-4. will result in a precipitate that permit filter-pressing. pH 4. and refined sugar by 25% 46% and 35% respectively the filterability is improved and molasses purity is . Sulphitation after Liming This process is termed alkaline sulphitation as opposed to acid sulphitation previously described. The success of the process is largely dependent on the quality and price of this molasses. Sulphitation is then carried out to about pH 7. with either manual or automatic control). After evaporation the syrup is cooled and sulphited to slight acidity (pH 6. continuous.5) is followed by heating. Cold Sulphitation The cold raw juice is pumped through a tower or box with a counter-current of SO2 to absorb as much gas as possible (acidity 3.45 liter).0 ml 0. Evaporation to a thin syrup follows. It uses about 8 gal (30 liters) of 26 Brix milk of lime per 100 gal (378 liter) of juice giving a large excess of lime. settling. The "boil-back" molasses is allowed to settle for several weeks before it is placed on the market. and only the most commonly used are outlined here. with an SO2 level of 30-40 ppm. Treating diffusion juice with lime and then sulphitation decreases the color of syrup. Heavier liming (10-12 gal. raw sugar. The A molasses is inverted to yield a sucrose-invert ratio of about 1:1.0 or below).1 N alkali for 10 ml of juice. This is for the production of raw sugar and A molasses. 38 . yielding a near-white sugar that is heavily washed in the centrifugal. Liming to slight acidity (pH about 6. and decanting as in the defecation process.5). giving a total sugar of 65% at 80 Brix. Obviously these variables permit a large series of combinations. Sulfitation can also be carried out by injecting SO2 (industrial liquid SO2 in cylinders) into the cold raw juice to a level of about 400 ppm SO2. is frequently followed by a second boiling to a raw sugar. One boiling. Addition of reagents (batch.3.5 producing a heavy precipitate that may be removed with settling and decantation. and the syrup is settled for 6-24 h before vacuum pan boiling. Many of the continuous liming processes may have different fractional procedures. baffles to ensure proper circulation and other details. but are not in general practice. Continuous Sulphitation Continuous sulphitation means the continuous addition of SO2 and lime to the constantly flowing stream of juice. when a quantity of lime is added to attain a strongly alkaline reaction (pH 10+). pH 6. The juice is first heated to this temperature then sulphited and limed boiled. As in all other similar processes. Control of Temperatures and Reactions . after which the sulphitation is completed to neutrality to litmus (pH about 7.47. Harloff's process is a hot treatment procedure in which the juice is heated to 75 °C and the lime and SO2 are added simultaneously in such a way as to maintain the reaction acid to phenolphthalein and alkaline to litmus (pH about 7. 55 Brix against 65 Brix or higher Sulphited syrup is usually maintained at a distinct acid reaction. the juice is finally brought to boiling temperatures in juice heaters and settled. giving better sugar recovery Hot Sulphitation Hot sulphitation serves to reduce the solubility of calcium-sulphite.5. the minimum solubility is at about 75°C (167 °F). The syrup density is lower than in ordinary defecation processes.2).6. Marches shows many different procedures with diagrams indicating construction details.1 .lower. methods of lime and gas addition. Sulphitation of Syrup Sulphiting the syrup leaving the evaporators gives a sugar of higher and more regular quality than juice sulphitation alone. and settled.8). except toward the end. which is more soluble at low temperatures. Sulphitators Generally the mixed cold juice is sprayed into tall vertical cylindrical tanks. Either the flow of gas through the system is induced by an air ejector or the SO2 is under pressure.9-7. The sulphitated juices are drawn from the conical bottom of the tower at a pH of 3. fitted for the upper twothirds with a series of hardwood grids made of 2 x 4 ft (0.0. to give a clarified juice to the evaporators of pH 6.Good circulation and thorough mixing both of the lime and of SO2 are very important a bent circulation baffle devised by Thompson gives the best results in cylindrical sulphitators Avoidance of high alkalinities at high temperatures or for extended periods is recommended for the same reasons as in defecation control: such high alkalinities result in decomposition of reducing sugars and in color formation. limed in a separate liming tank to pH 6. generally to neutrality. and the lime addition is regulated by a controller.2 m) or more in diameter and possibly 15 ft (4. then heated to boiling and settled.8-4. Continuous sulphitation can be carried out in cylindrical sulphitators holding a fixed volume of juice.6 x 1.5-6. The juice enters the top of the tower in a spray and falls through the wooden grillwork. The supply of gas is kept constant.8. 4ft (1. In actual practice.0. then is maintained near the neutral .5 m) high. while the milk of lime is added constantly to the entering juice and a continuous pressurized flow of SO2 into the liquid near the bottom of the tank supplies the needed circulation. Temperatures above 75 °C are detrimental and some prefer not to exceed 70 °C until the final pH adjustment is made. the juice is pre-limed before entering the sulphiting tank. Heated juice (75 °C) flows through the tank continuously. where it encounters the rising current of SO2.2 m) timbers set on edge. Poor mixing of lime and juice may produce local over-liming. Mechanical feed ensures continuous . obviously detrimental to piping. Zozulya et al. better boiling properties of syrups and molasses because of reduced viscosities. Sulphur Stoves or Burners The production of SO2 occurs when sulphur is burned in a current of air. because moisture in the air will cause the formation of sulphuric acid. and it should be replaced before it becomes saturated with water. especially with juices of deteriorated or frozen cane. and the material selected is sold in Argentina under the trade name Clarigel. about every 8 h. Performance data of this new design show results superior to the conventional spray type with better gas utilization and Decolourisation. The advantages claimed are lower sulphur and lime consumption. and soon.point by the sulphitation-lime addition. and can be especially serious if it reaches the juice. The juice is fed into the feedline through a perforated disc and comes into contact with SO2 gas metered through a valve at right angles to the liquid stream. An internal cyclone at the top of the tank acts as exhaust gas-liquid separator and as supplementary mixer for the incoming gas and the juice. Rotary sulphur burners use induced draft. The drying agent is generally quicklime spread on trays. much greater removal of organic non-sugars. Bentonite is clay. and less scaling of evaporators. Oldertype stoves operate intermittently. describe a new sulphitator which comprises a vertical tank with a feed-line at right angles to the top of the side wall. Sulphitation with Bentonite A process employing colloidal bentonite combined with sulphitation was developed in Argentina for the production of direct-consumption white sugars. In any type of sulphur burner the air supplied to the furnace should be dry. modem burners provide for the addition of sulphur without interruption of the burning. The Swedish Celleco SBM-250 sulphur burner has a burning capacity of 5 t/d but has a turn-down ratio of 20:1. There are new methods of SO2 generation. Best results are obtained with sulphur of high purity (99. where the oxidation of the sulphur and mixing with the diluting air are completed.0-3. but can also function effectively at 42 psig.operation. A typical flow scheme for a modern SO2 generation plant is given . a cast-iron or brick lined compartment with baffles. The sulphur melts by its own heat of combustion in the rotating cylinder. presenting a large surface for combustion as the sulphur drips through the air. A uniform gas (5-16% SO2) free of sulphuric acid is delivered to the sulphitators. or 250 kg/d.0 psig. Air is drawn in at an adjustable neck ring and anti-sublimation sleeve at the connection between the rotating drum and combustion chamber.6-99. It is normally operated at 2.9%). precise control of SO2 addition. Hydrogen Peroxide Hydrogen peroxide has also been tried in sugar refining. MeGinnis diagrams a system for the introduction of liquid SO2. and reduced white sugar .Liquid Sulphur Dioxide Where transportation costs will permit. freedom from sulfuric acid. liquid SO2 offers many advantages. A large reduction in sulphur consumption results. and elimination of sulfur-burning equipment are other advantages. The method is comparatively trouble free and adapts itself readily to automatic pH control. the amount used is relatively small and the apparatus sometimes a bit crude. Design Considerations Sulphur burner. Production of SO2 gas: The combustion of sulphur is required to produce sulphur dioxide. geared mainly to reducing excessive alkalinity to the neutral point. a tower for contacting liquor and SO2 Or a venturi system of contacting. This is done. Equipment Because sulphitation is only a minor operation in a carbonization refinery. such as the Quarez sulphitator.color by 46% and ash by 20%. because the reaction takes place in the gaseous state between sulphur vapour and oxygen. another Process such as ion-exchange can also be used to remove excess calcium. Especially the sulphur burner. The latter is then separated from the liquor during a second filtration to produce a final clear liquor. Sulphitation Part II Current Technology The carbonated liquor after the first filtration still contains an appreciable amount of calcium in solution which has to be removed. Sulphitation is not an essential part of a carbonization refinery. according to the formula: S + O2 → SO2 + 293 kJ The reaction is exothermic and the combustion gas has an SO2content of 6 to . the sulphur burner for production of SO2 gas 2. The equipment in use in our refineries to perform liquor sulphitation consists of: 1. By treating the filtrate with sulphur dioxide to form calcium sulphite precipitate. but then the operation is not critical enough to warrant a more complex approach.16%. Prevent the sublimation of sulphur. The cooling of SO2 gas to below 200°C is essential. 4. The air flow should be kept constant and controlled. A regulated supply of sulphur should be provided. a circulating pump. The Sulphur Tower As the name implies this is a tower containing splash trays. The Quarez The Quarez sulphitation system consists of a holding tank. The sulphited liquor. The liquor is broken into droplets in falling from one splash tray to the next. Ideally the design and operation of sulphur burners require that some important points be Recognized. which causes the SO2 gas to be sucked in and mixed. exits the tower at the base into a small seal tank. drying of the air of combustion is also required to prevent the formation of H2SO4. since the tower is under slight vacuum. 2. A simple type of sulphur burner is normally used being of the stationary type and quite suitable for the light sulphitation of liquor required. which can cause blockages and impair SO2 production by controlling the furnace temperature to less than 300°C. The. The points mentioned above are not easy to control in the type of furnace in use. stacked on top of one another and designed to create a continuous passage for the liquor from the top to the bottom. if possible. Reaction takes place as the SO2 conies into contact with the liquor. in particular: 1. The rest of the liquor by-passes the . 3. the production of SO3 then being negligible (5). The gas is drawn up the tower by suction from a fan and the exhaust fumes are dispersed into the atmosphere. a venturi and sulphur furnace to produce SO2 the level in the tank is kept constant by means of an overflow. with calcium sulphite precipitate in suspension. while the SO2 gas travels up the tower. Liquor in the holding tank is circulated by the pump and a certain amount is forced through an injector creating a vacuum. Keep to a minimum the formation of SO3 which will react with moisture in the air to produce sulphuric acid. but a lower pH than this will result in inversion of sucrose and must be avoided. This system is in operation in Pongola and the data available on the installation is given here: Refined sugar throughput Tons Brix in Raw Melt Volume of liquor to Sulphitation Number of circulations Capacity of circulating pump 22 25 Tons/hr Tons/hr 20 15 300 m³/hr /hr m³/hr PRACTICAL CONSIDERATIONS Operating control Sulphitation is carried out to a pH of 7. the setting of which controls the amount of gassing and the final pH of the liquor. It is therefore of paramount importance to reliably control the final pH set point. A heat exchanger of the shell and tube type is normally . Filtration Filtration of the sulphited liquor should take place at or near 85°C to take advantage of the decreasing solubility of calcium sulphite at high temperatures as well as lower viscosity.injector by means of an adjustable valve.9 – 6.8. This is generally done by varying the proportion of SO2 gas to liquor by measuring liquor pH.0 and even at 6. The sweet water should be returned to process that is C and B sugar melting. B and C. etc and preferably not back to the raw sugar refinery melter. and overall recovery are well defined and universally understood. on account of color and ash increase in refinery melt. pan movement water.used for this purpose. Sadly in the alcohol industry things are a little more disorderly. and is calculated by the formula below Yf = Vb · ab / (Mm · fsm) where Yf = fermentation yield Vb = volume of beer [liter] . In the sugar industry ratios like extraction. The amount of calcium sulphite precipitate is much less than the carbonate precipitate and less filtering surface is required. To help bring a little order the following is offered Theory There are four commonly used measures of yield Fermentation yield Fermentation efficiency Alcohol recovery Overall Conversion Efficiency Fermentation yield Fermentation yield is measured in liters of absolute alcohol in beer per ton of sugars in molasses. boiling house recovery. Disposal of Sweet Water The cake from the primary and secondary filters is sent to sludge filters for sweetening-off. Distillery Yields Background Just as in a sugar factory there are a number of measures of operational efficiency in a distillery. 511.794 corresponds to the specific gravity of absolute alcohol and the factor 0. and is given by Ef = Yf · 0.1 grams of alcohol and 1000 .794 / 0.5111 is best explained as follows: If one kilogram of sugar was completely fermented (using theoretical 100% efficient yeast).ab = alcohol content of beer (v/v) Mm = mass of molasses [tonne] fsm = fermentable sugars content of molasses (m/m) Fermentation efficiency Fermentation efficiency is an expression of how much alcohol was actually produced in beer relative to the amount that could be theoretically produced.1 = 488.9 grams of carbon dioxide would result. Alcohol recovery is calculated as follows Ede = (aaVp + ssVf) / aaVb · 100 where Ede = Alcohol recovery (or distillation and evaporation efficiency) aaV p ssV f aaV b = volume of potable alcohol as liters absolute alcohol = volume of feints as liters absolute alcohol = volume of beer as liters absolute alcohol Overall Conversion Efficiency Overall conversion efficiency is a measure of how much alcohol is finally produced relative to the amount that could be theoretically produced. Alcohol recovery Alcohol recovery is a measure of how much alcohol was finally produced relative to the amount that was in the beer.5111 × (100/1000) The factor 0.511. and is given by . It shows the amount of losses in the evaporation and distillation sections combined. 70 2001/02 3.Eo = Ef · Ede · 100 Values of Yield The following table gives values of yield that one would expect in a well run Distillery Parameter Alcohol Recovery Fermentation Yield Fermentation Efficiency Overall Conversion Efficiency Alcohol from Cane Molasses This article sets out a way of calculating how much alcohol you can make from the molasses your sugar factory produces. How much molasses? The fist step is to calculate how much molasses you will produce.5% 573 89% 87% Molasses at a standard 85°Bx Year Molasses% Cane 2000/01 3.93 . In the Southern African Industry it is usual to express the amount of molasses made per tonne of cane crushed at a standard molasses brix of 85° The South African Industry average figures for the past five years are shown Below Value 98. 2002/03 4.03 2003/04 3.73 2004/05 4.16 So the amount of molasses produced is M = C · M85 · 0.85 / Bm where M = tonnes molasses produced C = tonnes cane crushed M85 = Molasses at 85° brix as a percentage on cane crushed Bm = Actual brix of molasses produced Fermentable sugars The next step is to calculate the amount of fermentable sugars (FS) in the molasses. The fermentable sugars in molasses are sucrose, glucose and fructose; there are other sugars present in molasses, they are either unfermentable or are in small enough quantities that they can be ignored. There are a number of ways of measuring fermentable sugars in molasses; the most accurate is High Performance Liquid Chromatography (HPLC). The Lane and Eynon method also described in the SASTA Lab Manual is a two step process, which measures reducing sugars by titration. Reducing sugars are those sugars which reduce Fehlings reagents. Glucose and fructose reduce Fehlings reagents, sucrose does not, so the sucrose is inverted using hydrochloric acid and the reduction titration is repeated and the total reducing sugars can be calculated. The problems with this method are there are other substances in the molasses which are also reducing agents, but are not fermentable sugars, so this method overestimates the amount of fermentable sugars, and the titration is complex and requires a degree of skill to ensure repeatability, that may not always be present in a sugar factory laboratory. South African Industry data on molasses quality are given as a guideline South African Industry Average Molasses Quality Year 2000/01 Refractometer brix 84.26% Sucrose/refractomete r brix Purity 37.21% Fructose% 7.55% Glucose% 5.41% FS%brix molasses 52.59% in 2001/02 84.44% 37.03% 7.58% 5.47% 52.48% 2002/03 85.09% 37.24% 7.14% 5.13% 51.66% 2003/04 84.79% 37.92% 7.08% 5.22% 52.43% 2004/05 83.97% 36.94% 7.93% 5.20% 52.58% So, it is clear that about 52.5% of the brix in molasses are fermentable sugars. To calculate the tonnes of fermentable sugars in molasses we use the following Formula FS = M · Bm · FS%B where FS = tonnes fermentable sugars in molasses M = tonnes molasses produced Bm = Actual brix of molasses produced FS%B = fermentable sugars as a percentage on brix in molasses Alcohol Yield The amount of alcohol produced is given by A = FS · Yf · Ede where A = liters of alcohol produced Yf = Fermentation yield Ede = Alcohol recovery (or distillation and evaporation efficiency) Design a limed juice flash tank Tank Mixed Juice Diameter Flow [tonne/h] [mm] A 50 60 70 80 100 125 150 175 200 1457 1625 1756 1878 2097 2344 2569 2774 2966 Flash [DN] B 350 400 400 450 500 550 600 650 700 Pipe Juice [DN] C 150 150 150 150 200 200 200 250 250 Inlet Juice [DN] D 200 200 200 250 250 250 300 300 350 Outlet Drain [DN] E 80 80 80 100 100 100 100 100 150 . exhaust steam is often used for juice heating or. preferably bled vapour from the evaporators. the juice circulates through the tubes. . this is provided by the juice heaters. It is thus necessary to have a heat exchanger between vapour and juice. Suitable headers force the juice to pass a certain number of times from bottom to top and from top to bottom of the heater by restricting the juice each time to a few of the tubes.225 250 275 300 325 350 375 400 3146 3146 3478 3633 3700 3926 4063 4194 750 800 800 850 900 950 950 1000 250 300 300 300 300 300 350 350 350 350 400 400 450 450 450 450 150 150 150 150 150 150 150 150 Juice Heaters Because high pressure steam is very valuable. if possible. and the vapour outside them. The juice heater (below) consists of an assembly of tubes. the log mean temperature difference (LMTD) and the heating surface area. Q = h· A· ΔTlog Where .Vertical Juice Heater (Coil) The basic calculation of the juice heater is to calculate the amount of heat transferred using the overall heat transfer co-efficient (OHTC).