Effect of Pump Parameters on Vacuum in Water-jet Pump System

1 Analysis of water jet pump working system In order to simplify the calculation process, the following assumptions are made for the water jet pump system: a. Except for the nozzle, the pipeline resistance in the water jet pump system is not counted. The design of the water jet pump system is based on the principle of optimization. All the gas entering the mixing room was promptly drained.

Based on the above assumptions, the water flow rate through the nozzle is: the water flow rate at the outlet of a water-gas jet pump nozzle, m3/s; the number of nozzles; the pressure at the outlet of a water pump; Pa; water-gas jet pumping Difference between chamber and pump outlet height, m; Water density, kg/m; Partial resistance coefficient; - Diameter of outlet pipe of pump, m;d, 2* Diameter of single nozzle; m. * Coefficient, k = 0.77; m * Area ratio, refers to the body flow of the mixing tube and nozzle area.

From the above derivation results, it can be seen that the air taken by the water jet pump system is proportional to the flow rate at the outlet of the water-gas jet pump nozzle. The greater the water flow, the more air is carried away, and the vacuum degree of the equipment is The higher, the increase in the flow of the water jet pump system at the outlet of its water-gas jet pump nozzle is an effective means of increasing the vacuum of the water jet pump system.

The water flow rate at the outlet of the water-air jet pump nozzle of the water jet pump system is related to the flow rate of the water pump. Its value is equal to the actual value of the water flow rate of the pump. If the flow rate of the water pump is large enough, the flow rate at the outlet of the nozzle will become the pressure of the water pump. The function, which is the actual flow, is proportional to the pressure that the pump can provide.

Therefore, properly increasing the pressure of the water pump is beneficial to the improvement of the vacuum degree of the system.

In the actual production, due to problems in the design and use process, the water-jet pump system can not meet the actual needs of production.

At this time, a larger pump with a larger flow rate will be used instead of the original pump. It is hoped that the vacuum degree of the system will be increased by the water flow rate of the large pump, but the desired effect is not obtained. This is because according to the foregoing analysis, merely increasing the flow rate of the water pump does not satisfy the increase in the vacuum degree of the water jet pump system, and the rated pressure of the water pump should be appropriately increased.

2 Calculation Examples After the maintenance of the on-site nozzles, nuclear calculations were performed on the Vacuum Pump being used.

0.05. Substituting the p and water jet pump system parameters into equation (1): From the calculation it can be seen that the flow generated by the pump is 0.063 m3/s and the actual flow of the pump is 0. Visible, the actual flow generated by the pump is lower than Its design ability, therefore, the water pump's flow and pressure ratio in this set of water jet pump system is unreasonable.

According to the calculation results, in order to increase the pressure of the water pump to increase the water flow rate at the outlet of the water-gas jet pump nozzle through the water jet pump system, an IS20CH5C-315 water pump is used.

Substituting the structural parameters of p and water jet pump system into equation (1): It can be seen that using 620 (-15 (-315 water pump instead of E20H50-250 water pump, the water flow rate at the nozzle will add about 50%, close to the design requirements The water flow rate at the nozzle of the water-air jet pump is improved, the vacuum degree of the water jet pump system is obviously improved, the efficiency of the cylinder filter has been basically improved, and the efficiency of the cylinder filter is not solved completely. It provides a reliable guarantee for the smooth production of Vacuum Products.