Removing ammonia from air with a constant pH, slightly acidic water spray wet scrubber using recycled scrubbing solution

Previous research on wet scrubbers has only studied highly acidic scrubbing solutions because of their high ammonia capture efficiencies; however, the high acidity created practical problems. Lower acidity solutions would reduce corrosion, maintenance, and cost; however, designers may need to use strategies for increasing scrubber effectiveness, such as using lower air velocities. The objective of this studywas to determine if a spray scrubber with slightly acidic and higher p H scrubbing solution （pH from 2 to 8） could effectively remove NH3 from NH3 laden air （such as animal building exhaust air）, and also collect this valuable resource for rater use as a fertilizer. A bench-scale spray wet scrubber treated 20 ppmv NH3/air mixture in a countercurrent contact chamber. First, the solution pH was varied from 2 to 8while maintaining constant air velocity at 1.3 m. s-1. Next, air velocity was increased （2and 3 m.s-1） while solution pH remained constant at pH6. At 1.3 m.s -1, NH3 removal efficiencies ranged between 49.0% （pH8） and 84.3% （pH2）. This study has shown that slightly acidic scrubbing solutions are a practical means of removing ammonia from air especially if the scrubber is designed to increase collisions between solution droplets and NH3 molecules. The NH3 removed from the air was held in solution as NH4＋ and accumulates over time so the solution should be an excellent fertilizer.

Effect of ring baffle configuration in a self-priming venturi scrubber using CFD simulations

This study uses computational fluid dynamics to survey the gas‒liquid flow hydrodynamics of a self-priming venturi scrubber with and without ring baffles.Based on the simulation results,we explore how the structure and configuration parameters such as baffle height,opening-area ratio,and baffle thickness affect the injection flow rate and the homogeneity of the gas‒liquid mixture.In addition,we report the best structure and configuration parameters for the ring baffle.The best position for the ring baffle is at nearly 7/16 of the length of the diffuser above the throat.Having the baffle too near the throat causes large pressure loss,decreasing the injection flow rate.The decrease in opening-area ratio leads to a lower injection flow rate and a more homogeneous gas‒liquid mixture.The optimal value depends on the requirement of the injection flow rate.For the baffle thickness,5 mm is recommended;an overly thick baffle decreases the homogeneity of the gas‒liquid mixture near the throat.All structure parameters and configuration parameters must satisfy the requirement imposed by the injection flow rate and scrubbing efficiency.