The effect of nozzle number, concentration of input ammonia gas and scrubbing liquid pressure on NH3 removal efficiency of a spray tower

Spray tower is a cost effective and simple equipment for ammonia gas purification. But its’ appropriate performance in the removal of ammonia gas is under question. In this study, the effect of nozzle number, concentration of input ammonia gas and scrubbing liquid pressure over the removal efficiency of spray tower was studied.
In present study, a spray tower was used to remove ammonia from air at room temperature and barometric pressure of Tehran. Ammonia gas at average concentration of 24.1, 52 and 68 parts per million was injected into the tower. Water was applied at a volumetric flow rate of 5 liters per minute and at 9, 10 and 12 bar head as the scrubbing liquid. The air flow rate in 3737.8 liters per minute was adjusted by a variable speed fan. Scrubbing liquid was sprayed using 1, 2 and 3 nozzle settings with a 20 μm size. The collected data were analyzed using the SPSS software.
The highest removal efficiency of 88.38% and the lowest removal efficiency of 51.47% Were obtained. Increasing the number of nozzles did not increase the removal efficiency significantly (P-Value = 0.06).
Removal efficiency of spray tower decreased by increasing the input ammonia gas concentration. Increasing the number of nozzles mounted on the spray tower from 1 to 3 increased the removal efficiency. Increasing the scrubbing liquid pressure increased the removal efficiency of ammonia gas by spray tower. It is advisable to increase the size of the nozzle outlet and apply caustic scrubbing solution to get removal efficiencies of higher than 90%.