Coal bed gas extraction method and device

The invention discloses a coal bed gas extraction method and device. The device comprises a centrifugal air pump, a straight-through motor, a suction inlet end cover and a cooling liquid circulating system, the suction inlet end cover is provided with a suction inlet so that coal bed gas can be conveyed into the straight-through type motor. The straight-through type motor comprises a motor shell, a stator winding, a hollow rotor and air guide fan blades; the centrifugal air pump comprises a pump shell, a front gland, a pump shaft and an impeller; the motor shell is connected with the pump shell, one end of the pump shaft is fixed to the front gland, the other end of the pump shaft is fixed to the suction inlet end cover, and the impeller and the air guide fan blades are driven by the hollow rotor and the pump shaft to pressurize coal bed gas. Cooling pipes are arranged in the motor shell and the pump shell, and the cooling liquid circulation system is connected with the cooling pipes to cool the device. And f