10_32_ps3 - 10.32 Spring 2005 Problem Set 3 Due Friday,...

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10.32 Spring 2005 Problem Set 3 Due Friday, April 1, 2005 The Kraft process for the manufacture of paper involves a pulping step in which wood chips are broken down into cellulose and lignin. The aqueous pulping solution, called white liquor, contains sodium hydroxide and sodium sulfide. Following treatment of the wood chips with this white liquor, the cellulose pulp is filtered from the solution, now called Kraft Black Liquor (KBL). This KBL contains about 15 percent dissolved solids and is usually concentrated using multi-effect evaporation to 60 to 70 percent solids. It has been suggested that reverse osmosis can be used to perform the initial concentration of the KBL. Completely replacing the evaporators is probably not feasible because the pressure required would be several hundred atmospheres to overcome the osmotic pressure. We wish to design the initial reverse osmosis stage to concentrate KBL from 15 to 20 weight percent dissolved solids. The permeate should have less than 0.4 weight percent solids.
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This note was uploaded on 11/27/2011 for the course CHEMICAL E 10.302 taught by Professor Clarkcolton during the Fall '04 term at MIT.

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10_32_ps3 - 10.32 Spring 2005 Problem Set 3 Due Friday,...

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