110111-488-490-491 - X out = 0.06 I bP lb n - C ' Y = 0.02...

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IbP Y = 0.02 IbP X out = 0.06 lb n - C ' In _. lb methane 9 Equilibrium data can be approximated as Y = 1.5X. Find the HETP for the packing. D6.* We wish to design a stripping column to remove carbon dioxide from water. This is done by heating the water and passing it countercurrent to a nitrogen stream in a staged stripper. Operation is isothermal and isobaric at 60°C and 1 atm pressure. The water contains 9.2 x 10- 6 mole frac CO 2 and flows at 100,000 lb/h. Nitrogen (N 2 ) enters the column as pure nitrogen and flows at 2500 ft 3 /h. Nitrogen is at 1 atm and 60°e. We. desire an outlet water concentration that is 2 x 10- 7 mole frac CO 2 , Ignore nitrogen sol- ubility in water and ignore the volatility of the water. Equilibrium data are in Table 12~ · 1. Use a Murphree vapor efficiency of 40%. Find outlet vapor composition and number of real stages needed. D7. We wish to absorb ammonia from an air stream using water at O°C and a total pressure of 1.30 atm. The entering water stream is pure water. The entering vapor is 17.2 wt· % ammonia. We desire to recover 98% of the ammonia in the water outlet stream. The· total gas flow rate is 1050 kg/h. We want to use a solvent rate that is 1.5 times the min- imum solvent rate. Assume that temperature is constant at O°C, water is nonvolatile, and air does not dissolve in water. Equilibrium data are available in Table 12-3. Find L min , L, and N. D8. HCI is being absorbed from two air streams into water in a countercurrent staged lab- oratory absorber at lOoC and a pressure of 2.0 atm. Feed rate of gas feed 1 is 1.0 kmollh of total gas, and this gas is 20 mol % HCl. Feed rate of gas feed 2 is 0.5 kmollh of total gas, and this gas is 5 mol % HC!. The entering water is pure. The outlet gas should be 0.002 mole fraction HCl. Equilibrium data are given below. Use the opti- mum feed locations for both gas feeds. Note: Use ratio units. If careful with units, the liquid units can be in mass and the gas units in moles, which is effectively the form of the equilibrium data. Derive the oper- ating equation and external mass balances to determine where to include the molecu- lar weight of HCI (36.46). Because HCI has a very large·heat of absorption in water, the column will have to be well-cooled to maintain the temperature at lODe. Com- mercial units are not isothermal. a.
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This note was uploaded on 12/29/2011 for the course CHE 128 taught by Professor Scott,s during the Fall '08 term at UCSB.

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110111-488-490-491 - X out = 0.06 I bP lb n - C ' Y = 0.02...

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