Groundwater was contaminated with 120 µg/L of benzene, and your company must tre

Question

Groundwater was contaminated with 120 µg/L of benzene, and your company must treat it to achieve an effluent concentration of 1 µg/L or less benzene. Check whether or not a readily available packed tower stripping column is able to meet the requirements. The existing packed tower has 3.25 m effective packing height (plus 20% extra for height for safety that you do not take into account in your calculations), and 1.3 m internal diameter. Data Henry’s law of constant = 5.921 x 10-3 atm m3/mole KLa = 0.66 min-1 Air flow rate = 11.00 m3/min Water flow rate = 0.50 m3/min Temperature = 298 °K

Explanation / Answer

Answer:

1. if air is used for the stripping purpose, it is almost impossible to achieve the given stripping operation. Some inert gas may be useful for the same operation.

2. the area of the given tower can't be calculated as the diameter of the tower is not given.

the given question may be solved by considering

the height of the packed tower Z = HtXNt (i.e height of each unit X number of units)

since kla is provided Ht = L/(Kla (1-x)lm

where, L is the mol of liquid at any time in the tower

(1-x)lm = (x1- x*)-(x2- x*)/ (ln((x1- x*)/(x2- x*))

Nt for the stripper can be calculated (when henry law is applicable)

= ln[{{ x2-(y1/m)*(1-A)/ x1-(y1/m)}+A}/ (1-A)

A=L/mG

m is Henry's constant

x1, x2, y1, y2 are the inlet and outlet conc of benzene in liquid and gas phase

Hope this will help

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