In an ethanol plant, the mixture of water and ethanol from the beer column distillate contains about 40% ethanol (molar basis) in water, together with the fusel oils described in the previous problem. This mixture is distilled to give an azeotropic mixture of ethanol and water (89% ethanol) overhead, with 99.9% recovery of ethanol. The fusel oil can cause blending problems if it is allowed to accumulate in the distillate. Fusel oil is a mixture of higher alcohols and ethers that can be approximated as a mixture of n-butanol and diethyl ether. This mixture is usually removed as a side stream from the column. When the side stream is contacted with additional water a two-phase mixture can be formed and the oil phase can be decanted to leave an ethanol-water phase that is returned to the column. 

1. Draw a flowsheet for this process. 

2. Estimate the stream flow rates and compositions for a production rate of 200,000 US gal/d of dry (100%) ethanol. 

3. Optimize the distillation column using the cost correlations given in Section 6.3 and assuming that reboiler heat costs $5/MMBtu. Minimize the total annualized cost of the column. 

Data from section 6.3

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Table 6.2 Process cost correlations. Process ABS Resin (15% Rubber) by emulsion polymerization Acetic Acid by Cativa process Acetic Acid by Low Water Methanol Carbonylation Acrolein by propylene oxidation with Bi/Mo catalyst Adipic acid from phenol. Alky lation (sulphuric acid effluent refrigeration process) Alkylation (HF process) Allyl chloride by propylene chlorination Alpha olefins (full range process) Alpha olefins (full range process) Benzene by Sulpholane extraction Benzene by toluene hydrodealkylation Benzene reduction by Bensat Biodiesel (FAME) from vegetable oil bis-HET by Eastman Glycolysis BTX Aromatics by Cyclar process BTX Aromatics by CCR Platforming Butadiene by extractive distillation Butadiene by Oxo-D plus extractive distillation Butene-1 by Alphabutol ethylene dimerization Butene-1 by BP Process Caprolactam from nitration-grade toluene Carbon monoxide by steam methane reforming Catalytic Condensation for Gasoline Production Catalytic reforming by CCR Platforming Coking by Flexicoking including Fluid Coking Coking by Selective Yield Delayed Coking Copolymer polypropylene by INNOVENE Licensor Generic BP Celanese Generic Generic Stratco/ DuPont UOP Generic Chevron Phillips Shell UOP/Shell Generic UOP Generic Eastman BP/UOP UOP UOP/BASF Texas Petrochem. Axens BP SNIA BPD S. p.A. Generic UOP UOP Foster Wheeler/UOP Capacity units MMIb/y BP MMIb/y MMIb/y MMlb/y MMIb/y bpd bpd MMlb/y MMIb/y MMIb/y MMgal/y MMgal/y bpd MMlb/y MMIb/y tpy tpy MMIb/y MMIb/y tpy bpd bpd ExxonMobil bpd bpd tpy tpy MMscf/y MMIb/y Slower Supper 50 500 500 30 300 4,000 400 400 50 50 8,000 100 50 5,000 12,000 80 250 20,000 40,000 2,000 10,000 300 15,000 150 15,000 2,000 3.474 0.6 2,000 2.772 0.6 200,000 800,000 200,000 800,000 100 100 300 20,000 5,000 30,000 1000 3.533 0.160 1,200 1,000 200 200 15,000 500 200 a 12.146 0.6 30,000 6.809 0.6 60,000 8.146 0.6 7.793 0.6 7.002 0.6 0.0275 0.6 2.747 0.6 0.500 0.6 0.044 0.6 0.015 0.6 500 5.514 0.6 500 11.314 0.6 0.153 7.581 60,000 5.240 80,000 0.169 0.6 120,000 0.321 0.6 6,000 0.363 0.6 0.6 0.6 0.0251 0.6 0.222 0.6 0.6 0.179 0.6 0.109 15,000 40,000 0.343 0.6 900 3.430 0.6 0.6 0.68 0.6