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Cyclohexane Production Unit
Presented by Brian Clifton
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Executive Summary The cyclohexane production plant is not economically feasible unless the price of cyclohexane is more than double the price of benzene. Yellow does not recommend IRI to proceed with the plans to build and operate this facility.
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Outline Process Overview Economic and Risk Analysis Pipe Network
Pump System Heat Exchanger Distillation Column
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Process Overview Benzene is hydrogenated in a Gibbs reactor at high temperature and pressure to form cyclohexane
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Process Overview
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Total Equipment Cost (2005)
Economic Analysis Equipment Cost Distillation column $53,200 Heat Exchanger E1 $14,800 Heat Exchanger E2 $1,230 Heat Exchanger E3 $6,610 Reactor $5,040 Mixer $2,500 Splitter Compressor $150,000 Flash $42,600 Total Equipment Cost (2005) $344,200
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Economic Analysis Production Cost: $7.14/gal Revenue: $3.60/gal
TCI: $2.5 million NPW: negative $1 billion Accuracy: ±10% Required ROI: 8%
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Strauss Plots/Propagation of Error
Strauss plots for FCI, product cost, and product cost Propagation of error method
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Monte Carlo Simulation
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Piping System Piping materials made of stainless steel
Insulation thickness of 1 inch Schedule 40 pipes increased to schedule 80 to operate under bursting strength FCI of $900,000 for piping system
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Piping Specifications
Stream Type Length (ft) Elbows (90o) Valves (globe) Pressure Drop (psia) Hydrogen 8'' Sch 80 700 3 Benzene 4'' Sch 80 500 5 Recycle 350 4 1 Feed 6'' Sch 80 150 6 2 Top Bottom Purge 300 S1 10'' Sch 80 S2 100 S3 S4 S5 S6 S7 S8
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Pumping Section Cyclohexane is pumped from the process to a storage tank at 555 psia which is 35 feet above the flash tank
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Pumping Section
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Pump Section Piping All pipe are stainless steel schedule 40
ability to resist corrosion
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Pump Section Pump Positive displacement pump 9 hp required
415 ft head available All components are stainless steel
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Pumping Section Cost for installation of the pumping section, including the pump, pipes, and valves, was determined to be $105,000 Total fixed capital investment for the cyclohexane plant up to $2.4 million.
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Heat Exchanger Network
There are three heat exchangers in the cylcohexane plant The heating utility required by the plant is minimized by using the hot product stream to pre-heat the incoming reactant stream.
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Heat Exchanger Network
Heat exchanger 1 was designed rigorously A temperature – heat diagram was created
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Heat Exchanger: Design
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Heat Exchanger: Design
The single pass, countercurrent design was selected No baffles were used, in order to maintain the shell-side pressure drop under 5 psi
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Heat Exchanger: Design
By Hand Pro/II Area (ft2) 2730 2980 U [Btu/(hr*ft^2°F)] 9.6 126.8 Number of tubes 326 x 2” OD 40 x 1” OD Length (ft) 16 284
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Heat Exchanger Design Triangular pitch Stainless steel heat exchangers
Hot streams were maintained tube side in all heat exchangers Heat exchanger 2 uses steam to heat the reactant stream Heat exchanger 3 uses cooling water to cool the product stream
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Distillation Column 30 theoretical trays
Optimal feed location: 16th tray Column height: 32 feet Column diameter: 42 inches
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Distillation Column Valve trays 94 valves / tray Tray spacing:
24 inches Condenser heat duty: -1.9 MM Btu/hr Reboiler heat duty: 3.01 MM Btu/hr
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Summary After the detailed designs were conducted, the cyclohexane plant was shown to not meet IRI’s criteria for profitablity. Yellow does not recommend IRI building and operating this facility.
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Questions ?
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