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Water at 1 atm is being used to remove 65% of the CO2 from a gas stream via absorption. The inlet gas stream is 100mol/h and consists of 8 mol% CO2 and the balance nitrogen. How many equilibrium stages would be required if we operate at 1.5 (S/G)min? Henrys law constant for CO2 in water is 1640 atm/mol frac.

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4 votes

Answer:

2

Step-by-step explanation:

Without mincing words, let's dive straight into the solution to the question above. We are given the following information or parameters which is going to aid in solving this problem:

Amount Of CO2 to be removed from a gas stream due to absorption = 65%, amount of the inlet gas stream = 100 mol/h, amount of the CO2 = 8 mol%, and the Henrys law constant for CO2 in water = 1640 atm/mol frac.

STEP ONE: Determine the mole ratio for the inlet gas and the outlet gas.

The mole ratio of the inlet gas = 8/92 = 0.087 and the mole ratio of outlet gas = 8 × 0.35/92 = 0.03.

NB; the 0.35 is the amount remaining after 65% of CO2 has been removed that is 100% - 65% = 35% =0.35.

STEP TWO: The next step here is to determine the value for the mass balance and hence, the absorption factor.

A × 0.087 = A × 0.03 + C × [0.087/1640]. = C
\\/A║[min] = 1075.47.

Thus, 1.5 C
\\/A ║[min] = 1613.2.

The absorption factor = 1613.2/1640 = 0.984 = 1 [approximately].

STEP THREE: Determine the number of equilibrium stages that would be required if we operate at 1.5 (S/G)min.

Thus, the equilibrium stages would be required if we operate at 1.5 (S/G)min = 0.087 - 0.03/ 0.03 - 0 = 1.9 = 2 [approx.]

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