How to select the minimum flow valve of the feed pump

It can be selected according to the equal diameter of the pipeline, and can be selected according to the maximum flow rate and the flow range of the valve.

The flow control valve, also known as the 400x flow control valve, is a multi-functional valve that uses a high-precision pilot mode to control the flow rate. It is suitable for pipes where the flow and pressure of the water distribution pipe need to be controlled, and the predetermined flow rate is maintained.

Limit the excessive flow to a predetermined value and reduce the upstream high pressure appropriately, even if the pressure upstream of the main valve changes, it will not affect the flow downstream of the main valve.

The main function of the minimum flow valve of the feed pump is to ensure that the feed pump is opened in time for recirculation when the flow rate of the feed pump is less than a certain value, so as to prevent cavitation inside the feed pump due to local overheating vaporization. Since it was put into operation, the minimum flow valve has the problems of short life and large leakage flow.

The manufacturing plant generally specifies a minimum allowable flow value for the operation of the feed pump, which is generally 25% to 30% of the rated flow rate. The purpose of specifying the minimum permissible flow rate is to prevent vaporization of the feed water due to too little water output.

Extended information: Before the pump starts, the pump and the inlet pipe are filled with water, after the pump is running, under the action of the centrifugal force generated by the high-speed rotation of the impeller, the water in the impeller flow channel is thrown around, pressed into the volute, the impeller inlet forms a vacuum, and the water of the pool is sucked along the suction pipe under the external atmospheric pressure to supplement this space.

The inhaled water is then thrown out by the impeller and enters the outlet pipe through the volute. It can be seen that if the impeller of the centrifugal pump rotates continuously, it can continuously absorb and press water, and the water can be continuously lifted from low to high or far away. To sum up, a centrifugal pump is called a centrifugal pump because it lifts water to a high place due to the centrifugal force generated by the high-speed rotation of the impeller.

1) The flow direction of water along the centrifugal pump is sucked in along the axial direction of the impeller and flows out perpendicular to the axial direction, that is, the direction of the inlet and outgoing water flow is 90° to each other.

2) Since the centrifugal pump relies on the impeller inlet to form a vacuum to absorb water, it is necessary to pour water into the pump and the suction pipe before starting, or use a vacuum pump to pump air to discharge the air to form a vacuum, and the pump casing and water suction pipeline must be strictly sealed, and no air leakage is allowed, otherwise it cannot form a vacuum, and it will not be able to absorb water.

The minimum flow valve, the pressure before the valve is the outlet pressure under the minimum flow condition of the feed pump, the pressure after the minimum flow valve considers that the boiler water can return to the deaerator, which is usually slightly higher than the working pressure of the deaerator, and the loss of the pipeline from the outlet of the minimum flow valve to the deaerator should also be considered, but the outlet pressure should not be too high to avoid impacting the deaerator.

25% 30% of rated flow.

According to the query question bank test questions, the general high-pressure feed pump is not allowed to run for a long time under the minimum flow rate below the minimum flow rate required by the coarse socks, and the minimum flow rate is about () of the rated flow rate. Answer: d, so it is 25% to 30% of the rated flow.

A water pump is a machine that transports or pressurizes a liquid. It transmits the mechanical energy or other external energy of the prime mover to the liquid, so that the liquid energy increases, and is mainly used to transport liquids including water, oil, acid and alkali, emulsion, suspension emulsion and liquid rolling metal.

<> control requirements: make the boiler feed pump start and run safely, and eliminate the damage to the pump due to too small flow, increased temperature rise, and strong cavitation of water. (Older power stations have a minimum flow control valve that uses a switch-type type, and there are also automatic circulation valves that use a mechanical pump.)

The working condition of the inlet pump: the pressure drop is up to 160-350 kg, which is the valve with the largest pressure difference in the power station system, and the flow rate is generally 30% of the normal flow.

Valve requirements: anti-cavitation, anti-blocking structure, V-level sealing level, the valve works continuously when the pump starts and stops running, and the secondary valve closes the valve after the pump starts normally, and the valve is usually opened by fault.

Assuming a wall thickness of 4mm

85*(250 100), that is, the inner diameter is at least.

Take a tube with an outer diameter of 159mm and a wall thickness of 6mm.

Dude, the choice of pipe diameter and flow rate is based on the economic flow rate as the standard.

That is, q s = 2m s

Of course, 2m s is an approximate value, and generally speaking, 3m s is acceptable, but the higher the flow rate, the higher the loss.

The size of the water diameter of the submersible pump is the inner diameter or the outer diameter or the nominal diameter of the water diameter of the submersible pump refers to the inner diameter, the unit is inches, not the city inch, but the inch inch, 1 inch (inch) =.

Before opening the pump, the suction pipe and the pump must be filled with liquid, after the pump is opened, the impeller rotates at high speed, and the liquid in it rotates with the blades, under the action of centrifugal force, it flies away from the impeller and shoots outward, and the injected liquid gradually slows down in the pump casing diffusion chamber, and the pressure gradually increases, and then flows out from the pump outlet and discharge pipe.

In the center of the blade, because the liquid is thrown around, there is no air and no liquid vacuum low-pressure area is formed, and the liquid in the liquid pool flows into the pump through the suction pipe under the action of the atmospheric pressure on the pool surface, and the liquid is continuously sucked up from the liquid pool and continuously flows out from the discharge pipe.

The flow rate of a water pump is the amount of liquid (volume or mass) that the pump can convey out per unit of time.

The flow rate of the pump is usually represented by the letter Q, and the flow rate unit of the pump is m3 s (cubic meter seconds), l s (liter seconds), or m3 h (cubic meter hours), and the conversion relationship between them is: 1m3 s = 1000l s = 3600 m3 h.

Design flow: Under the premise of satisfying efficiency, the flow rate is generally used as a reference point, and the energy value added (head) obtained from the pump inlet to the outlet under different flow rates is generally drawn, and then the performance curve is drawn.

Rated flow: According to the median value (limit value) of the flow rate obtained by the test, the rated flow rate of the pump will be marked on the nameplate when the pump leaves the factory, and the work efficiency is the highest under this flow data, if it deviates from the flow rate during use, the efficiency of the pump will be reduced, and if the deviation is too much, it will also lead to the phenomenon of motor burning.

Maximum Flow: The pump is capable of outputting the maximum flow value (peak).

Summary. Hello, I'm glad this question was left to me. Hello, 100-350ISG, IHG, YG, IRG vertical pipeline pump can, the flow rate of this model:

120m3 h, head: 142mShaft power: kw.

In addition, we can also provide you with the best quality ** and perfect after-sales service system, you can buy with confidence. You are welcome to call us for specific details.

Hello, I'm glad this question was left to me. Hello, 100-350ISG, IHG, YG, IRG vertical pipeline pump can, the flow rate of this model: 120m3 h, head:

142m shaft power: kw. In addition, we can also provide you with the best quality ** and perfect after-sales service system, you can buy with confidence.

This is a hydraulic valve, how big a pump does this valve need, please wait a minute.

4% (compression coefficient) liters This is the volume of hydraulic oil compressed under pressure liters This is the total amount of oil converted into flow liters in minutes, 12 megapascal pumps, kilowatt motors can.

You don't understand! This is a 120 liter valve.

Hello, can you elaborate on the problem a little more?

Hello, for some reason, I'm sorry I can't hear your voice for the time being, can you type it to explain?

You're a layman.

<> it's not easy for everyone.