Principles for setting the minimum flow valve of a pump

It mainly aims to avoid the effects resulting from the pump operating at low flow rates; to prevent vibration and temperature rise under such conditions

Agree: Mainly to avoid the effects caused by the pump operating at low flow rates; to prevent vibration and temperature rise under such conditions

The low flow protection of a pump is designed to ensure that the low flow valve opens when the flow rate is below a certain threshold, thereby preventing damage to the pump. Generally, centrifugal pumps have a preferred operating range as well as an allowable operating range; operating within these ranges ensures the pump’s efficiency and stability. If the pump operates outside these ranges, vibration occurs, the pump temperature rises, axial and radial forces become unbalanced, and the shaft may bend. These parameters are usually specified by the manufacturer

The low flow rate of a pump is generally specified by the manufacturer, based on the pump’s inherent properties, to ensure stable operation of the pump at that flow rate. This is commonly applied to high-speed pumps, and it is very useful during the startup and testing of such pumps

I’ve learned about it. I really hadn’t paid attention to this issue before, but our facility doesn’t have high-speed pumps

The minimum flow valve is installed in multi-stage pumps for starting purposes, right? Starting a centrifugal pump involves simply closing the valve and starting it under backpressure; when a multi-stage pump cannot be started under backpressure, the valve must be closed to initiate operation. To prevent excessive pressure at the pump outlet and avoid accidents, a minimum flow valve is used to regulate the outlet pressure of the multi-stage centrifugal pump.

Minimum flow valve I. Overview The minimum flow valve is also known as the boiler feed pump recirculation valve. In power plants, it is installed at the outlet of the feed water pump and connected to the deaerator. The boiler feed pump draws water from the deaerator and sends it to the boiler. To prevent the feed water pump from overheating and to avoid cavitation, its flow rate must under all circumstances be at least a certain specified safe flow rate, that is, the minimum flow rate. When the flow rate required for the boiler feedwater is very low, such as when the turbine trips, it is necessary to open the minimum flow valve promptly to return a portion of the high-pressure water from the pump outlet back to the deaerator, thereby ensuring the safe operation of the feedwater pump. The system in which this valve is located is called the recirculation system. II. Operating conditions of the minimum flow valve: This valve is normally closed, and it needs to open automatically when the steam turbine trips. It needs to adjust the flow rate according to the system requirements. The operating parameters of this valve are as follows: before the valve, the pressure is 17.5–38.7 Mpa and the temperature is 141–232°C; after the valve, the pressure is 0–0.07 Mpa and the temperature is 41–109°C. This means that the valve must withstand a high pressure difference in order to prevent cavitation and reduce erosion and noise – thus, the operating conditions are quite severe. III. Patent products with outstanding performance: To cope with such harsh operating conditions, Suzhou Delan Valve Technology Development Co., Ltd. has developed its own patented products. This valve utilizes the principle of circulating counterflow; it features annular grooved discs, and these discs are stacked to form a cylindrical throttle sleeve that serves as the valve’s internal component. This design effectively reduces fluid pressure and controls fluid velocity, prevents cavitation and erosion, reduces noise, and extends the valve’s service life. It is a specialized valve designed specifically for recirculation systems. IV. An ideal product proven by practice: This valve was granted a **patent in 2004, and after being used by more than a dozen customers over the past few years, it has delivered satisfactory results and received high praise from them; it is currently the ideal product among valve options with the lowest flow rate. QQ 329781587: I can help you solve this problem. If needed, I can offer you a free trial of our smallest flow control valves. . QQ329781587, Phone: 18962115893, .15250460259. We use our own patented technology, a circulating counterflow structure

As a supplement to point 5 on the 5th floor, by utilizing the minimum flow line during pump switching, the transition can be made smoother, thereby reducing fluctuations in the system.

It’s generally not used; it’s rarely employed in either design or on-site applications, as this valve is very expensive – possibly more so than your pump. It is used only under extremely special process conditions and pump arrangements.