An experimental investigation of scrubber internals at conditions of low pressure

This paper reports experimental results for the performance of natural gas demisting equipment (natural gas scrubbers), and on basis of this discusses possible improvements in the design of gas scrubbers. The separation efficiency and pressure drop of gas scrubber internals: a vane-type inlet, a mist mat and a cyclone deck, for two gas–liquid systems: air–water and air–Exxsol were determined at a range of gas and liquid flows. To interpret results, a model for the cut size of an axial flow cyclone is given. The results show that when reentrainment limits the separation performance of the scrubber the separation performance varies with the nature of the liquid injected, so that design on basis of an air–water system has to be done with caution. The results and the analysis presented further indicate that the K-value, although generally a good evaluation parameter, does not take into account some significant effects, such as the nature of the fluids, changes in the free area for flow, e.g. in the mist mat, and the action of scrubber internals in general. The separation efficiency is shown to be dominated by reentrainment from the cyclone deck at the liquid loadings and gas flows used, loadings and flows which are typical for an industrial scrubber.