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Design Of A Propylene Storage Facility

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1996 Annual Conference


Washington, District of Columbia

Publication Date

June 23, 1996

Start Date

June 23, 1996

End Date

June 26, 1996



Page Count


Page Numbers

1.144.1 - 1.144.6



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Paper Authors

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Pamela Brown

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Harry Sills

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NOTE: The first page of text has been automatically extracted and included below in lieu of an abstract

I .— .

Session 3213

Design of a Propylene Storage Facility

Harry Sills, Pamela Brown Stevens Institute of Technology

Senior Design students were to design a propylene storage facility. The problem required solution of mass and energy balances and sizing of heat exhangers, separators, and an adiabatic flash valve. The objective was to minimize the cost per kg. of propylene recovered. Modification and improvement of the initial flow diagram was also encouraged. Solution of this problem was facilitated by the use of CACHE software. Equipment costs were estimated using scaling factors, and cost indexes. Utility costs were also provided to the students. A degrees-of-freedom analysis reveals that there is one degree of freedom, making this an open ended problem. In order to optimize this process, the production cost vs. the temperature of the cold fluid leaving the first heat exchanger was plotted. By selecting the temperature at the minimum production cost, the problem is completely specified. Students worked in teams of three to design the propylene facility and submit a formal report. They were given 10 days to complete the assignment. Because of the magnitude of the assignment, delegation of tasks, and parallel completion of tasks was necessary. Weekly private meetings with the instructors and teaching assistant were scheduled with each team to answer questions, and simulate industrial progress meetings with supervisors. The students reported that the assignment was demanding, but worthwhile. They integrated concepts learned throughout the undergraduate curriculum had experience writing a formal report, meeting a deadline, preparing concise questions and progress reports for the weekly meeting, and working in teams. The problem follows:

Problem Statement: Propylene is stored at 700 psia and 60 OF by dissolving it in liquid n- octane. The mole fraction of propylene is 0.515. When recovery of the propylene is desired, it passes through a series of heat exchangers and an adiabatic flash valve to lower the pressure and change the temperature. The final product is 99 mole% propylene vapor at 30 psia and 60°F. The n-octane is returned to storage. A heat exchange network for a propylene storage facility is shown in figure 1 (1). The feed stream, which contains propylene dissolved n-octane, is preheated in the first heat exchanger, H-1, to recover heat by partially condensing a recycled stream consisting of propylene and n-octane. This feed mixture is further heated to its bubble point in a second heat exchanger, H-2, using high pressure steam. The mixture then passes through an adiabatic flash valve and goes to a perfect phase separator, S-2. The vapor leaving the phase separator is parially condensed when it is used as the heat transfer fluid in H- 1. It is further condensed by passing through heat exchanger H-3. The stream then enters a phase separator where the product, 1000 lb. moles/hr (454 kg. mole/hr) of 99 mole% propylene at 30 psia is

?@xij 1996 ASEE Annual Conference Proceedings ‘..+,Ryy’:

Brown, P., & Sills, H. (1996, June), Design Of A Propylene Storage Facility Paper presented at 1996 Annual Conference, Washington, District of Columbia. 10.18260/1-2--5968

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