Why is the efficiency of conventional sand pumps low?

The conventional sand pump structure is: the pump is located in the middle of the pipe column, with 10-15 sand settling pipes connected to the lower part, and a discharge valve and pen tip at the bottom. The reasons for low sand removal efficiency are as follows:

1. Due to the low liquid level of coalbed methane wells, which are generally 30-50 meters above the coal seam, there are many pocket sediments. Pump the coal powder from the 177.8mm (7-inch) casing into the 73.0mm (2 7/8-inch) oil pipe, with a length ratio of 1:7. Assuming there is 30 meters of coal powder inside the casing, the length of coal powder pumped into the oil pipe should be 210 meters. The sand storage tail pipe of the conventional sand pump is under the pump, and the pump suction pressure is low. When a 210m tail pipe is connected under the pump, the sand pump is already above the liquid level, and the pump cannot suction.

2. The lower end of the tail pipe is the inlet valve, and the extracted coal powder deposits inside the tail pipe, burying the inlet valve, preventing the discharge valve from opening and the pump from suction.