Evaporator Optimization Project

Bryan PicouJames RobertsAdvisor: Dr. Junkun MaET 494Instructor : Dr. Cris Koutsougeras

Evaporator Optimization ProjectDomino SugarRefinery is in Arabi, LaProduce 8 million pounds of sugar per day on averageIt is the third largest sugar refinery in the worldEvaporator Optimization ProjectSteam is one of the most expensive resources for a refineryTake the current operation of the evaporators and make it more efficientTake the current operation of the melters and eliminate the steamEvaporatorsEvaporator uses steam in a vacuum to heat the sugar liquor and lower its density Left over vapors from this process is what we are trying to optimize

MelterTakes the raw sugar and uses steam to melt this sugar into a liquid.It uses direct steam injectionVapors from evaporator will be rerouted to power the melterCurrent Operation

Current Operation

Sugar Parameters Based upon 8 million pound melt rate8 % scrap rateSugar going into melters assuming 70 BrixSketch of Phase 1

Energy required to Melt SugarQ= Specific Heat * Mass of Sugar * Temperature

Q=0.65 BTU/lb F * 478,800 lb/hr * (165 F-130 F)

Q=10,892,700 Btu/hr

Barometric Condenser

Condenser Design Qsteam = QsugarMass of Steam * Latent Heat of Steam = Cp of Sugar * Mass of Sugar * TemperatureRearranging:Mass Steam = (Cp of Sugar * Mass of Sugar * temperature)/Latent Heat of SteamSteam With Phase ChangeQsugar = Mass of Steam * Latent Heat of Steam10,892,700 BTU/hr = m * 922.6 BTU/lbMass of Steam = 11,806.525 lb/hr

Sugar going to CondenserQ steam = Mass * Specific Heat * Temperature10,892,700 BTU/hr = m * 0.65 BTU/lb F * (188.421 F 165 F)M = 715,511.72 lb/hrM = 1079.6 gpmSteam Pipeline Head lossHL = f * (L/D) * (V2/2g)HL = 0.015 * (341/24) * (67.512/2*32.2)HL = 180.97Steam Pipeline DesignBabcock Formulap = 0.47 * (d+3.6/d^6) * m^2 * L * vp = 0.47 * (24+3.6/24^6) * 4.436^2 * 522 * 42.16p = 0.0294 psiap = 0.33%

Steam Pipeline Mach NumberMach Number = Velocity / Sonic VelocityMach Number = 84.5 ft/s / 1528.09 ft/s

Mach Number = 0.05624 Steam PipelineVelocity = Volumetric flow Rate / Cross-Sectional Area of pipeV in = 763,077.9 ft^3/hr / 3.14 ft^2V in = 67.51 ft/s

V out = 766,173 ft^3/hr / 3.14 ft^2V out = 84.5 ft/sSugar Pipeline DesignVolumetric Flow Rate = Velocity * AreaVelocity = Volumetric Flow Rate/AreaVolumetric Flow Rate of Sugar = 150,949.436 * (1/92.2) = 1637.196 ft3/hrArea of 4 in pipe = 0.0872 ft2Velocity = 5.214 ft/sResidence Time= Volume of Melter / Volumetric Flow RateVolume of Melter = 329.867 ft3Volumetric Flow Rate = 2884.34 ft3/hr= 6.86 min

Residence TimeResidence Time with South Melter= 10.29 min

Sugar Dissolution LabAdding a Melter the same sizeTheoretical Temperature = 246.75 * x-0.173

Theoretical Temperature = 246.75 * 13.72-0.173Theoretical Temperature = 156.85 F Residence Time with New Melter= 13.72 min

This extra melter would give the sugar an extra 33.24% more residence time than theoretically needed

Heat Exchangersp in HX#1 to HX#2 = Inlet from G5 pump Inlet of HX #2p in HX#1 to HX#2 = 47.39 psia 41.39 psiap in HX#1 to HX#2 = 6 psia

Approach Temperature3 PumpsP1/1 + Z1 + V12/2g hL + hA = P2/2 + Z2 + V22/2g

Condenser PumphL = 2.48 fthA = 10 psiaPipelinesV = Q/AMelter Recirculation Pipeline (8)V = 8659.33 ft^3 / (0.349 *3600)V = 6.89 ft/secSteam Pipeline SupportsF = E * I * ^2 / K * L^2F = 29000000 psi * 28.09 in^4 * ^2 / 2 * 420^2 in^2F = 22,788.8 lbDeflectionY = W * L^3/ 3 * E * IDeflection of I beamY = 1904.26 lb * 20^3 in ^3/ 3 * 29000000 psi * 127.7 in^4Y = 0.00137 inBolts (5/8) = F/A = 9427 psi

= 9427 psi/4 Bolts = 2356.7 psi / Bolt

Clevis Hangers = F/r^2

24 Steam Pipeline

R = 1904.26 / * 18000R = 0.183 in

Diameter = 0.367 inCondenser Supports (Stress) = W * L / Z = 17,314 lb * 109 in / 91.3 in^4 = 20,671.79 psi

Thermal ExpansionL = Lo * * T

Steam PipelineL = 3.96 inEvaporatorsMsi Lsi + MLi LLi = Mso Lso + Mso Lso

4A Evaporator Msi = (11.81 * 1141.4)+(476.35*107.5)-(488.16*104.8)/949.7Msi = 14.24 kpphEvaporatorsDensity of Liquor Exiting = Mass of Feed liquor * Density of Feed Liquor / Mass of Exiting LiquorDensity = 488.16 kpph * 64.4 Brix / 476.35 kpphDensity = 65.996 BrixEvaporatorsExiting Temperature of Liquor = Boiling Point Rise + Steam TemperatureExiting Temperature = 7.056 + 188.58Exiting Temperature = 195.64 FPhase 2

Heat ExchangerQ = U *A * TLMUA = Q * TLMCurrent OperationUA = 149,103.6

Evaporator Optimization ProjectUA = 149,943.9SavingsPhase 1$/year = (12,000 lb/hr * 986.2 BTU/lb / 79.5% Boiler Efficiency) * 24 hrs * ($3.73/1,000,000 BTU) * 260 days$/year = 346,734.88 SavingsPhase 2$/year = (2,600 lb/hr * 949.6 BTU/lb / 79.5% Boiler Efficiency) * 24 hrs * ($3.73/1,000,000 BTU) * 260 days$/year = 72,283.70

SavingsCombined$/year = 419,072.69PricesPhase 1Total Cost = $1,205,105.29 (+/- 15%)

Phase 2Total Cost = $221,429.38 (+/- 15%)

CombinedTotal Cost = $1,426,534.67 (+/- 15%)Return on InvestmentPhase 1ROI = 3.48 years

Phase 2ROI = 3.06 years

CombinedROI = 3.41 yearsFurther ResearchEliminating Steam to SaturatorsFinal Proposal

ReferencesDomino Sugar Corporation Cane Sugar Refining Handbookwww.sugartech.co.za