Performance Evaluation of a Laboratory-Scale Packed Column

Author : Rivera, Jocelyn Ilagan
Major Adviser : Alcanzare, Edilberto A.; Demafelis, Rex B.
Major Co-Adviser : Demafelis, Rex B.
Committee Members : Movillon, Jovita L.; Arquiza, Apollo C.
Year : 1994
Month : April
Type : Thesis
Degree: BS
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The performance of a laboratory scale packed column was evaluated for the absorption of Ammonia gas from an Ammonia-Air mixture using water as the absorber. The weak liquor flowrate was maintained at 120 ml per minute while the Ammonia-Air gas flowrate was varied at 1.13, 2.14 and 2.82 pounds per hour at ammonia concentration of 16 mole percent. For ammonia concentration of 20 mole percent the rich gas flowrates were 0.94, 2.16 and 2.86 lb/h. And the rich gas flowrates set for 25 mole percent ammonia were 0.91, 2.20 and 2.92 lb/h. The results showed that at low rich gas flowrate of 0.91 lb/hr and high rich gas concentration of 25 mole percent a maximum recovery of 74.06 percent can be achieved. The overall composite gas phase mass transfer coefficient (KG a) at ammonia concentrations of 16, 20 and 25 % were 4.20, 4.50, 4.06 (lb mole/h atm ft2), respectively. The additional parameters determined for the evaluation of the column performance included overall number of transfer units in gas phase (NOG), overall height of transfer unit in gas phase (HOG), height equivalent to theoretical plate (HETP), gas mass velocity (Gyact) and the pressure drop (-ΔP). The values determined for NOG were: 1.56, 1.84 and 2.03 units. For HOG the values were: 1.37, 1.16 and 1.05 ft. The computed HETP were 3.85, 3.23 and 2.96 ft. For the Gyact the values were 0.06, 0.08 and 0.09 lb/ ft2s. The (-ΔP) for the column was also determined to have a constant value equal to 0.20 in. H2O/ft. packed height. These column parameters were calculated for Ammonia concentrations 16, 20 and 25 % respectively.

To improve the efficiency of the packed column and to fully evaluate its operational capability it is recommended to use appropriate flow meters and employ a rapid but accurate method of ammonia concentration analysis.

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