exam1s08 - st clarifier is at 95 ° C and the fresh water...

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A 3-stage clarifier system is used to separate precipitated calcium carbonate from a solution of sodium hydroxide as generated in the reaction below. Na 2 CO 3 + Ca(OH) 2 -----> 2NaOH + CaCO 3 | v The flowsheet is shown in Figure 1. The reaction occurs in a dilute solution with the concentration depending on the amount of recycle from the third thickener. An 11% solution is desired for the product NaOH, and the amount of wash water on the third thickener is adjusted to maintain this concentration; you may assume that the flow of fresh water is known for this problem. The solution entering the storage tank before the 1
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Unformatted text preview: st clarifier is at 95 ° C and the fresh water is at 40 ° C. Each clarifier stage generates a CaCO 3 sludge that is 30% solids; there is no carryover of sludge in the clarified solution. Reactions Products 480 t/day NaOH (100% soln) 600 t/day CaCO 3 (Suspended solid) a) Develop the GEMS block diagram for the system using the flowsheet and the data given above. 11% NaOH Soln. Dilute Recycle Sludge 30% solids 70% soln. 4 Sludge 30% solids 70% soln . 2 nd Clarifier 8 1 st Clarifier 1 2 3 5 Fresh Water Sludge 30% solids 70% soln . 3 rd Clarifier 8 Storage Tank...
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This note was uploaded on 08/22/2011 for the course WPS 417 taught by Professor Kirkman during the Spring '11 term at N.C. State.

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