DESIGN AND IMPLEMENTATION OF A 120 MW COAL MINE METHANE FIRED POWER PLANT IN SHANXI PROVINCE, PEOPLE'S REPUBLIC OF CHINA

摘要

Methane is naturally found in coal seams throughout the world. The amount of methane trapped in a coal seam varies by country and by region. The presence of methane in coal represents the principal hazard associated with underground mining of coal. It is necessary to continuously extract methane to keep the methane concentration in the mine below its lower explosive limit. The lower explosive limit of methane is five percent by volume. Methane can be extracted from a coal seam in three forms: Coal Bed Methane (CBM) Extracted by drilling wells from the surface into the coal seam prior to mining, or from a coal seam which may never be mined. CBM generally has a methane content of over 90 percent? Coal Mine Methane (CMM) Extracted from the mine itself, while mining is underway, or sometimes after mining is complete. CMM generally has a methane content of 35 percent to 60 percent. The nonmethane fraction of the CMM is virtually all air (nitrogen and oxygen). CMM is extracted by drilling horizontal wells into the coal seam? and Ventilation Air Ventilation air contains very low concentrations of methane. As the name implies, it is the exhaust from systems designed to flush the mine with fresh air to provide a safe environment for mine personnel. Ventilation air is generally unsuitable for energy recovery. CBM and CMM can be converted into several forms of useful energy, including electricity, boiler fuel, pipeline quality gas, or vehicle fuel.