Device for preparing liquefied natural gas by oxygen-bearing coal mine methane

The invention discloses a device for preparing liquefied natural gas by oxygen-bearing coal mine methane. The preparation method of the liquefied natural gas comprises a compression purification procedure and a liquefaction separation procedure, wherein, the liquefaction separation procedure comprises a main flow process and a refrigeration process, and the refrigeration process combines a mixed refrigerant with throttling refrigeration and a special refrigerant flow. In the invention, the refrigeration process combines mixed refrigeration with throttling refrigeration together to change the existing refrigeration process and fully and rationally utilize the cold energy recovery process during the technological process, thus improving the refrigeration efficiency and relatively enhancing the processing capability of the device; and for the coal mine methane with low single well production rate, the production cost can be saved, and power and energy can be saved by adopting only one set of compression equipment.