After discovering this situation during the trial production of the biogas slag suction truck with the DVE vacuum pump, the piping system was carefully analyzed. It is believed that the suction and spraying of the mechanical oil is due to the strong gas in the piping system after the DVE vacuum pump is stopped. Caused by flow. If the DVE vacuum pump stops running, the gas flow in the piping system can be completely prevented, which can effectively prevent the occurrence of these two harmful phenomena.

Through further analysis of the piping system diagram, it is found that the direction of the gas flow at the inlet and outlet of the DVE vacuum pump is unchanged whether it is air suction and slag suction operation or air pumping and spraying operation. Taking advantage of this feature, imagine adding a one-way valve in one of the inlet or outlet directions of the DVE vacuum pump. When the DVE vacuum pump is stopped, the gas flow can be effectively prevented, that is, when the tank body is under negative pressure, the outside air cannot enter. ; When the tank is under positive pressure, the gas cannot come out. In this way, the gas in the piping system cannot flow when the DVE vacuum pump is stopped, which can prevent the mechanical oil from being sucked into the tank or rushing out to the outside.

From this point of view, there are three positions for adding the one-way valve. When the first improvement was made, the one-way valve was added to the position of the pump outlet pipe, and the suction and pressure tests were performed, and the effect was found to be significantly improved. However, a small amount of mechanical oil is still sucked in or out. According to analysis, although the one-way valve prevents the gas flow in the main pipeline, the negative or positive pressure gas in the oil-gas separator and the DVE vacuum pump will still flow with the outside atmosphere through the four-way valve, thereby driving the flow of oil.

Therefore, the inferred position is also inappropriate, because there is a thin oil pipe connected between the oil-air separator and the DVE vacuum pump. The addition of a one-way valve here cannot completely prevent the gas flow in the main pipe, so the above problems will still exist.

Therefore, in the second improvement, the one-way valve was directly added to the inlet position of the DVE vacuum pump, that is, the final state is shown in Figure 1. Adding it here can completely overcome the problems caused by the above two positions. Block the gas flow in the piping system. After the negative pressure suction slag operation and the positive pressure spraying operation test. After the DVE vacuum pump stopped, there was no phenomenon of mechanical oil being sucked into the tank or rushed out. The effect was very good, and this problem was fully solved.
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