The Simulation Experiment Study On Biogenic Coalbed Methane Production From Low And Middle Rank Coal Macerals

Researching influence of organic macerals in coal on the biogenic gas generation in coal seams can not only helps to understand the biogas formation mechanism of coal seams,but also provides theoretical basis and technical support for the exploration and evaluation of biogas resources in coal seams.The researching objects of this paper are the fertilizer coal from huainan mining area and the lignitous coal from longkou basin.Using the float-and-sink method to selected out the different organic micro-components in the coal samples and testing its organic matter based on the fully understanding the geological overview of the research area and the basic properties of the samples.The raw coals and organic macerals were used to simulate the formation of biogas to analyze the relationship between organic macerals and production of biogas.The research results are as follows:?1?Obtained the density of separation and suitable particle size of vitrinite?huminite?and inertinite by float-and-sink method.?2?The results of simulated experiment show that the production of biogas has three stages:the period of rapid increase of rate and cumulative production,the period of decrease of rate and slowly increase of cumulative production?the period of rate of gas production increases stably.vitrinite?huminite?of same rank coals has the highest biogas production,followed by raw coal,and the least is the inertinite.Compared with different coal rank coals,the lower rank of coals,the more biogas producted.The peak rate of biogas production are vitrinite?huminite?and raw coals trail vitrinite?huminite?.The inertinite posessess lowest rate of biogas production.While rate of biogas production of huminite in lignitous coals lag behind raw sample of lignitous coals.The main components of biogas gas are CH₄and CO₂.The vitrinite?huminite?produce the largest methane prodution,followed by raw coal,and the methane's prodution of inertinite is smallest.?3?The net biogas production of different rank coals is positively correlated with organic matter content,H/C and lipid hydrogen content through linear fitting analysis.The early rate of biogas production is positively correlated with chloroform asphalt"A"content,lipid hydrogen content,d₀₀₂and other parameters,and negatively correlated with fat structure parameters,L_aand L_cparameters.The comparison of the organic matter content,content of trace element,and other strutural parameters of the macerals in different rank coal found that vitrinite?huminite?have higher organic matter content,and the organic matter structure has more fatty hydrocarbon content.There are more aromatic structures with less hydrogen in the qualitative group.The aromatic layers are arranged more regularly and tightly in space,the degree of condensation of the aromatic ring is greater,.The higher content of vitrinite?huminite?contain in coals,the more beneficial it is to the production of biomethane.?4?The output of methane in different ranks is closely related to the organic H/C.The H/C decreases as the coal metamorphism increases,and the capacity of biogas production decreases.