低浓度含氧煤层气吸附富集过程中吸附塔高径比的影响规律

Impact of ratio of height to diameter on enrichment process for lowconcentration and oxygen-bearing coal bed methane

根据Coward爆炸三角形提出一种安全的分离富集低浓度含氧煤层气的设想——等比例变压吸附法,通过实验证明采用活性炭和碳分子筛作为混合吸附剂,可以在保证解吸气、排放气中甲烷浓度和氧气浓度不进入爆炸范围的前提下将煤层气中的甲烷浓度从20%富集到30%以上。实验研究了吸附塔高径比对解吸气和排放气中甲烷、氧气的浓度分布以及高径比对反吹时间的影响。结果表明提高高径比、增加反吹过程均能降低排放气和解吸气的爆炸性,实现低浓度含氧煤层气安全富集的可行性。但高径比过大,吸附时间过长,单位时间内吸附循环数减少,会降低吸附剂的利用率,增大床层阻力,增加压缩机能耗。

Based on the Coward explosion triangle, author suggested a safe enrichment method for low-concentration and oxygen-bearing coal bed methane （CBM） which was called proportion pressure swing adsorption（PPSA）. The ex- perimental results prove that the CH4 and 02 concentration in desorption and exhaust gas can both be controlled well and not over explosive limit,and the ca4 concentration in CBM can be increased form 20% to 30% ,with the applica- tion of the mixture of active carbon（AC） and carbon molecular sieve（CMS） as adsorbent in the process of PPSA. This paper experimentally investigated the impact of ratio of height to diameter（RHD） on the CH4 and 02 concentration in desorption and exhaust gas, as well as the purge step. The results show that the increase of RHD and the purge time can reduce the explosiveness of desorption and exhaust gas, which can ensure the enrichment safe for low-concentration and oxygen-bearing CBM. But the adsorption time will be prolonged with the increase of RHD ,which may leads to the decrease of adsorption cycle number and adsorbent utilization, as well as the increase of bed resistance and compressor energy consumption.