PDD_18_EDM2 - Process Design Decisions(PDD Prof B V Babu Process Design Decisions Copyright © 2008-2009 B V Babu BITS-Pilani Copyright ©

Info iconThis preview shows pages 1–8. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Process Design Decisions (PDD) Prof B V Babu Process Design Decisions Copyright © 2008-2009 B V Babu, BITS-Pilani Copyright © 2008-2009 B V Babu, BITS-Pilani LECTURE - 18 Process Design Decisions (PDD) Prof B V Babu Engineering Economics • Recap • Economic Decision Making – Example : Design of a solvent recovery system – Design of Gas Absorber System • Flow sheet Alternatives • Design Heuristic Copyright © 2008-2009 B V Babu, BITS-Pilani Copyright © 2008-2009 B V Babu, BITS-Pilani • Material Balances • Trade-offs for fractional recovery in Absorber & Distillation columns • Trade-offs for solvent flow rate in Absorber • Rules of thumb (Heuristics) • Importance of Solute-free basis quantities • Summary Process Design Decisions (PDD) Prof B V Babu Design of Gas Absorber System Flow Sheets & alternatives for gas absorption system • Before any calculations, it is necessary – To invent a flow sheet for process – The simplest possible flow sheet we might imagine is: Copyright © 2008-2009 B V Babu, BITS-Pilani Copyright © 2008-2009 B V Babu, BITS-Pilani Process Design Decisions (PDD) Prof B V Babu Design of Gas Absorber System: Flow sheet TION BER Air Solvent (Water) (77 F = 25 C or less) Acetone COOLANT Copyright © 2008-2009 B V Babu, BITS-Pilani Copyright © 2008-2009 B V Babu, BITS-Pilani Fig. 1 Flow sheet of gas absorption HEAT DISTILLAT ABSORB Acetone + Water Acetone + Air (Gas Feed having solute) Water + traces of Acetone COOLANT POLLUTION TREATMENT Sewer Process Design Decisions (PDD) Prof B V Babu Design of Gas Absorber System: Flow sheet • We use water as a solvent (because it is cheap) – to recover acetone from air stream in the gas absorber, and • Then we distill the acetone product from the water • And throw away the water • Environmental constraints may preclude this possibility Copyright © 2008-2009 B V Babu, BITS-Pilani Copyright © 2008-2009 B V Babu, BITS-Pilani • So, we include cost for pollution treatment • Of course, we could recycle the process water to the gas absorber – And in this way we would avoid any environmental problem • If we used any thing other than water as a solvent , we would always recover and recycle the solvent Process Design Decisions (PDD) Prof B V Babu Design of Gas Absorber: Alternate Flow sheet Acetone COOLANT TION BER Air Solvent COOLANT Copyright © 2008-2009 B V Babu, BITS-Pilani Copyright © 2008-2009 B V Babu, BITS-Pilani Fig. 2 Alternate flow sheet of gas absorption HEAT DISTILLAT 212 F ABSORB Acetone + Water Acetone + Air (Gas Feed having solute) Process Design Decisions (PDD) Prof B V Babu Design of Gas Absorber: Alternate Flow sheet • It is reasonable to question, whether discarding the process water, as shown in Fig. 1 can ever be justified – Even when a pollution treatment facility is available • The only justification is based on the temperature of the process water entering the gas absorber a recycle process (Fig 2) is used, we cool the recycle...
View Full Document

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.

Page1 / 24

PDD_18_EDM2 - Process Design Decisions(PDD Prof B V Babu Process Design Decisions Copyright © 2008-2009 B V Babu BITS-Pilani Copyright ©

This preview shows document pages 1 - 8. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online