Increasing mass transfer of volatile organic compounds in air scrubbers: relation between partition coefficient and mass transfer coefficient in a pilot‐scale scrubber

Abstract

BACKGROUNDThe mass transfer of volatile organic compounds (VOCs) from waste gas streams to liquid in scrubbers is determined by the overall volumetric mass transfer coefficient (Kga), which is dependent on the air‐to‐water partition coefficient (KAW, dimensionless). The application of additives in the water phase can alter this KAW to lower values thus increasing the Kga. Previous research provided partitioning data of new scrubber liquids and this study will link the partitioning data with mass transfer characteristics in a pilot‐scale scrubber.RESULTSThe Kga was experimentally determined using a VOC pulse addition response (PAR) method in a pilot‐scale scrubber with randomised or structured packing (1.6 m height, diameter 0.1 m). VOCs were injected at the inlet of the scrubber. SIFT‐MS was used for the online measurement of the VOC concentration. An advection–absorption model was used to calculate the Kga values for a set of VOCs and different scrubber liquid properties. Scrubber liquids and VOCs were applied to evaluate the Kga values in a KAW range from 2.6 × 10‐3 to 4.0 × 10, a gas velocity between 0.34 and 1.17 m s‐1 and liquid flow of 0.4 m3 h‐1. The obtained Kga ranged from 0 to 2.27 s‐1.CONCLUSIONA relationship between the Kga, gas velocity and KAW was established. Based on this mathematical model, the economical/technical suitability of applying an additive to the scrubbing liquid of industrial installations can be evaluated. β‐cyclodextrin was applied as additive in the scrubber and Kga values were significantly higher than with pure water. © 2018 Society of Chemical Industry