PDD_33_CDQS_PPO - Process Design Decisions (PDD) Prof B V...

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Unformatted text preview: Process Design Decisions (PDD) Prof B V Babu Process Design Decisions Copyright © 2008-2009 B V Babu, BITS-Pilani LECTURE - 33 Process Design Decisions (PDD) Prof B V Babu Cost Diagram and Quick Screening of Process Alternatives • Cost diagram – Conventional approach – Alternative approach • Quick screening of process alternatives – Systematic procedure ase case and alternatives Copyright © 2008-2009 B V Babu, BITS-Pilani – Base case and alternatives • Preliminary Process Optimization • Rigorous Optimization • Approximate optimization – Objectives – Example • Dominant trade-offs for design variables • Rank order parameter (most important design variable) • Proximity parameter (incentive for optimization) Process Design Decisions (PDD) Prof B V Babu Cost Diagrams • Summarizing the cost information to find the best possible alternative – Cost diagrams • Conventional approach – 1. To prepare a table of equipment costs that is coded to a flowsheet. Copyright © 2008-2009 B V Babu, BITS-Pilani • Similar type of equipment i.e. compressors, heat exchangers, distillation columns etc. are grouped together – 2. A similar type of table is prepared for • Operating costs and • All the individual values for a particular type of utility, i.e. electric power, steam etc., are summed and reported as a single entry Process Design Decisions (PDD) Prof B V Babu Cost Diagrams • A cost summary for the disproportionation of toluene is given in – Flowsheet : Fig. 9.1-1 – Investment summary: Table 9.1-1 – Operating cost summary: Table 9.12 (or) 9.1-3 – Two tables are to be looked into simultaneously along with the Copyright © 2008-2009 B V Babu, BITS-Pilani flowsheet Process Design Decisions (PDD) Prof B V Babu Cost Diagrams • Alternative approach – All the costs are put on a flow sheet – Annualized, installed equipment costs are placed inside the boxes on the flow sheet and – Operating costs are attached to the stream arrows • Advantage Copyright © 2008-2009 B V Babu, BITS-Pilani – Visual picture of how the costs are distributed throughout the process – Costs of the pumps, drums are not included in the diagram, assuming they have small cost values Process Design Decisions (PDD) Prof B V Babu Quick Screening of Process Alternatives • Systematic procedure – Keep a list of each decision that we make as we proceed through the base-case design – Then as we change these decisions, we generate the process alternatives – We want to make some estimate of the economic importance of Copyright © 2008-2009 B V Babu, BITS-Pilani each alternative, rather than repeat the design for each case, in order to minimize our design effort – We use the cost diagrams as a tool in making these estimates – See Table 9.3-1 • Process alternatives for HDA process • Figs. 9.4-1 to 9.4-5 – 5 alternate flowsheets for HDA process with diphenyl recycled • Different from energy integration point of view (HENS) Process Design Decisions (PDD)...
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This note was uploaded on 02/29/2012 for the course CHEMICAL 332 taught by Professor Profb.v.babu during the Spring '09 term at Birla Institute of Technology & Science.

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PDD_33_CDQS_PPO - Process Design Decisions (PDD) Prof B V...

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