The active circulation valve is a pump protection device. It actively protects the centrifugal pump (especially the hot water medium) from partial cavitation damage and instability that may occur in the pump body when operating at low load. Once the pump flow rate falls below the preset flow, the bypass is completely opened to ensure that the pump needs a small flow rate. Even if the main road is completely closed, that is, the main road traffic is zero, the small flow can be actively circulated through the bypass. The pressure is lowered by an integrated multi-stage saving regulator in the bypass. The active circulation valve has a large diameter bypass, this valve is used for large bypass flow rates, and the pressure difference is as large as 4MPa.
The active circulation valve integrates four functions into one:
1. Flow perception: The main valve disc can actively sense the main flow in the process system, and then determine the orientation of the main valve disc and the bypass valve disc according to this flow rate.
2. Recirculation control: the small flow required for the normal operation of the pump can be sucked into the storage equipment through the bypass, and the H-Q characteristics of the pump can be adjusted to complete the recirculation.
3. Bypass multi-stage decompression: The bypass control system can reduce the high pressure of the reflux medium from the pump outlet to the low pressure suitable for the reflux storage equipment with low noise and low wear.
4. Check back: It also has the effect of an active circulation valve to avoid the liquid from flowing back into the pump body. ZDT bypass check is optional.
Working principle of active circulation valve:
Depending on the perceived flow rate of the main circuit, the main disc check cone will actively move to a certain position. Together with the main valve disc drives the bypass valve stem, the main valve disc action is transmitted to the bypass, and the azimuth of the bypass valve disc is controlled to change the saving area of the bypass, and then the flow rate of the bypass is controlled. When the main disc returns to the seated closed state, all flow is returned through the bypass. When the main disc rises to the top position, the bypass is completely closed and all pump flow flows to the section system.
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