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Cyclohexane Production Unit. Presented by Brian Clifton. Executive Summary. The cyclohexane production plant is not economically feasible unless the price of cyclohexane is more than double the price of benzene.
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Cyclohexane Production Unit Presented by Brian Clifton
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.
Outline • Process Overview • Economic and Risk Analysis • Pipe Network • Pump System • Heat Exchanger • Distillation Column
Process Overview • Benzene is hydrogenated in a Gibbs reactor at high temperature and pressure to form cyclohexane
Economic Analysis • Production Cost: $7.14/gal • Revenue: $3.60/gal • TCI: $2.5 million • NPW: negative $1 billion • Accuracy: ±10% • Required ROI: 8%
Strauss Plots/Propagation of Error • Strauss plots for FCI, product cost, and product cost • Propagation of error method
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
Pumping Section • Cyclohexane is pumped from the process to a storage tank at 555 psia which is 35 feet above the flash tank
Pump Section • Piping • All pipe are stainless steel schedule 40 • ability to resist corrosion
Pump Section • Pump • Positive displacement pump • 9 hp required • 415 ft head available • All components are stainless steel
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.
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.
Heat Exchanger Network • Heat exchanger 1 was designed rigorously • A temperature – heat diagram was created
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
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
Distillation Column • 30 theoretical trays • Optimal feed location: 16th tray • Column height: 32 feet • Column diameter: 42 inches
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
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.