Question

A packed column (50 cm diameter) is to be used to remove 6 mole percent of ammonia gas from air mixture at 1 atm. The inlet gas flow rate is (1200 + (student number/10)) kg/min.mº; the recovery of the separation process is 97% ammonia and the overall gas transfer coefficient is 2.134 kg/hr.m'atm. The equilibrium relation for the system may be taken as Y = 1.15: X, where x and y are expressed in mole fraction. Note: - convert the composition to the molar ratio Determine: 1. minimum mass liquid flow rate 2. The number of transfer unit and packed column volume that will be required for designing the column using 1.25 of minimum liquid flow rate

Answer 1

To determine the minimum mass liquid flow rate, convert the mole percent of ammonia to a decimal and calculate the moles of ammonia in the gas mixture. Then, divide the moles by the recovery to find the minimum mass liquid flow rate.

To calculate the number of transfer units and the packed column volume required for designing the column, multiply the minimum liquid flow rate by 1.25, divide by the overall gas transfer coefficient to find the number of transfer units, and divide by the height of a transfer unit to determine the packed column volume.

Step-by-step explanation:

To determine the minimum mass liquid flow rate, we need to calculate the moles of ammonia in the gas mixture. First, convert 6 mole percent to a decimal by dividing it by 100. Then, calculate the moles of ammonia using the molecular weight of ammonia (17 g/mol) and the total flow rate of the gas mixture. Finally, divide the moles of ammonia by the recovery of the separation process (97%) to find the minimum mass liquid flow rate.

To calculate the number of transfer units and the packed column volume required for designing the column using 1.25 times the minimum liquid flow rate, multiply the minimum liquid flow rate by 1.25. Then, divide this value by the overall gas transfer coefficient to find the number of transfer units. Finally, divide the number of transfer units by the height of a transfer unit (which can be estimated based on the column's type and packing) to determine the packed column volume.