Simulation And Analysis Of Gas Flow Distribution In Radial Flow Air Adsorber

With the development of air separation requirement, the scale of radial flowfilters also becomes bigger and gas flow rate multiplies. Axial non-uniformitybecomes a more acute problem. Gas flow distribution in the filter is investigated bycomputational fluid dynamics (CFD). Annular packed beds and perforated plates aresimplified and modeled by porous media model and porous jump model, respectively.The simulation result of CFD model is validated with published experimental results.The axial uniformity of the flow distribution in the operating condition is analyzed. Itis found that the axial uniformity of the flow distribution is affected by many factors,including the area ratio of the center pipe cross-sectional to the annular channel, theporosity of both the center pipe and annular packed beds, the gas flow rate ofdesorption and the adding of a cone distributorIn the adsorption process, the pressure drop at the top of the channels in the centerpipe (collecting channel) is obvious, which leads to a poor utilization of the upper partof beds. The axial uniformity of the flow distribution reaches top while the value ofarea ratio of the center pipe cross-sectional to the annular channel is0.887. And theaxial uniformity of the flow distribution of molecular sieve layer and alumina layer is0.914and0.934, respectively. In addition, the decreasing of the porosity of centerpipe results in the increase of uniformity of the gas flow at the cost of very largepressure drop. What’s more, the uniformity in two layers can also be both improvedby lowering the porosity of molecular sieve layer, but lowing that of alumina willonly improve the uniformity in molecular sieve layer a little.In the desorption process, pressure drop in the center pipe is larger than the one inannular channel, resulting in the nonuniformity of the flow distribution. And theuniformity of the inner molecular sieve layer and the alumina layer reaches themaximum at the value of0.99and0.985, when the area ratios of center pipe toannular channel are0.46and0.41, respectively. Unlike that in the adsorption process,the uniformity in two layers can be improved by lowering the porosity of any layer inthe desorption process. At last, it is also found that the uniformity is decreased a lotwith the increasing of desorption flow rate. It is also shown that a cone distributor will increase the uniformity in desorptionprocess to a great extent but decrease that in adsorption process a little.A comparative optimal solution is proposed as follows:1. adjusting the porosityof the inner molecular sieve layer to0.33and that of the alumina layer to0.35,respectively;2. adding a cone distributor. The uniformity in the two layers will beimproved in both processes with reasonable addition of pressure drop.