Research On Feed Gas Adsorption Pretreatment In Liquefaction Processes Of Coalbed Methane

With the development of natural gas industry, the research on non-traditional nature gas --coalbed gas has become more and more important. Utilization of coalbed methane (CBM) is an efficient way to keep the coal industry running in a more safe way, to protect environment and to make best use of natural resource.Transporting CBM to end consumers is an effective way of utilizing CBM. Cryogenic liquefaction processes need efficient ways to remove impurities from the feed gas, such as CO₂. Unlike normal natural gas, coalbed methane has richer nitrogen. In order to meet the gas market standard, we should add a process to concentrate CH₄.This thesis elaborates the study on the adsorption pretreatment of the liquefaction processing of coalbed methane as follows:(1) A special experimental apparatus is set up to test the performance of removing impuritis in the adsorption way at ambient condition, and also the performance of adsorption separation of CH₄/N₂ under normal and cryogenic conditions.(2) Because of the possibly high nitrogen content in CBM, the effect of nitrogen content on adsorption of CO₂ in CBM is analyzed with experimental results.(3) Because of the possibly high pressure of CBM, the adsorption removal of CO₂ in CBM and adsorption separation of CH₄/N₂ under high pressure are analyzed.(4) A mathematical model of adsorption separation process in the pretreatment process of CBM is built, and some preliminary numerical calculation is done with the model.(5) Considering the integration of energy utilization of the adsorption and liquefaction processes, the possible plan on CH₄/N₂ separation under cryogenic condition is proposed, and preliminary experimental study is carried out.The research about the adsorption pretreatment of CBM in this paper will be significant to the development of CBM liquefaction processes and plants.