Abstract:

Pressure water scrubbing technology has become one of the key technologies of biogas purification. This paper adopted a packed absorption column to study on carbon dioxide removal. The influences of absorption pressure, absorption temperature, carbon dioxide content on the product gas and height of packing layer on carbon dioxide removal rate as well as those of liquid/gas ratio and biogas flow on volumetric overall absorption coefficient were investigated. At the same time, the intensive tests used a two-stage absorption column combined with a packed column and a spray column for purification process of pressure water. It was shown from the results that the increased absorption pressure, liquid-gas ratio and height of packing layer and reduced absorption temperature were favorable of removing carbon dioxide. Besides, volumetric overall absorption coefficient rose with increasing liquid/gas ratio and biogas flow. Two-stage absorption column was able to improve the effect of carbon dioxide absorption. When the biogas flow was 10 L·min^-1, the height of packing layer 100 cm and carbon dioxide content less than 3%, about 12% of the amount of absorption liquid can be reduced by two-stage absorption column compared with the traditional packed tower. Furthermore, when the two-stage absorption column of 110 cm was used, the optimum purification effect can be obtained and the carbon dioxide removal rate can reach 97.4%.

Key words: biogas, carbon dioxide, pressure water scrubbing, two-stage absorption column, volumetric overall absorption coefficient, biomethane

摘要：

压力水洗技术已成为提纯沼气的关键技术之一。采用填料吸收塔进行CO₂脱除实验研究，考察了液气比、吸收压力、吸收温度、CO₂初始含量、填料层高度对CO₂脱除率的影响，以及液气比、沼气流量对总体积吸收系数的影响，并运用填料塔与喷雾塔结合的二段式吸收塔进行压力水洗提纯沼气的过程强化实验。实验结果表明，吸收压力和液气比的增大、吸收温度的降低、填料层高度的增加有利于CO₂的脱除，体积总吸收系数随着液气比及沼气流量的增加而增大。二段式吸收塔能够提高CO₂吸收效果，当沼气处理量为10 L·min^-1，填料层高度为100 cm，CO₂含量小于3%时，与填料塔相比二段式吸收塔可以减少约12%的吸收液用量，并且采用110 cm填料的二段式吸收塔获得最佳的提纯效果，CO₂脱除率达到97.4%。

关键词: 沼气, 二氧化碳, 压力水洗, 二段式吸收塔, 体积总吸收系数, 生物甲烷