Abstract: The disadvantages of the traditional pumping station configuration are analyzed. The functional characteristics of the new hydraulic control valve are expounded from the aspects of installation method and working reason, and the broad application prospect of the product is prospected.
Keywords: water hammer, booster pump, control valve
For the majority of water supply enterprises, the accidents occur the most, have a direct impact on the water supply, and the most influential part is the pressurized pump house of the water plant. The pump house accident means stopping the water, directly affecting the benefits of the enterprise, and will supply water. Enterprises cause serious economic losses and social impacts, so water supply companies refer to pressurized pumping houses as the heart of water supply companies.
How to ensure the normal operation of the various systems in the pressurized pumping station is a problem that the water supply company has always been eager to solve. In order to solve this problem, various water supply companies and professionals have been striving to find the best solution.
Let's analyze the frequent incidents of the pumping station:
According to incomplete statistics, more than 90% of accidents in pressurized pumping rooms occur in the pump and its outlet pipe, and the remaining 10% appear in electricity and other aspects, and 90% of the 90% are in the water outlet of the pump. In the configuration, the main performance is: valve closure is not strict, burst and major water hammer accident. Therefore, the frequent occurrence of accidents in the pressurized pump room is concentrated on the configuration of the pump outlet, which is directly related to the traditional configuration, as shown in Figure 1.
This configuration has a lot of drawbacks:
1) When the pump is turned on, a light load process must be required. The purpose is to prevent the back pressure in the pipe network from acting back under the condition that the valve opening speed of the check valve in front of the pump is too fast, acting on the impeller of the water pump. When the pump is turned on, the load is too heavy, the current is too large, the motor is burnt, and the pump shaft is bent. Therefore, if this process is to be realized, in the traditional operation process, the pump must be started first, and the water pump reaches a certain speed, and the water outlet reaches It can be opened under the condition of back pressure. It is called: first open the pump, then open the valve. The control of this process can only be achieved by setting up the electric valve and the pump delay connection. In the absence of the electric valve, it is done manually, but the electric valve is often unable to be delayed or inaccurate due to the delay. Accurate control of the slow-opening time often causes this light-loading process to fail, resulting in frequent motor and water pump failures, and this method is labor-intensive, labor-intensive, unreliable, and cannot achieve a light load in the true sense.
2) When the pump is stopped, in order to prevent the impact of the water hammer on the water pump and the outlet check valve, the control valve is often closed first, and then the pump is stopped. In this case, if the power failure suddenly occurs, the electric control valve cannot be closed in time. Manual valves can not be manually shut down in a short period of time. In addition, if the check valve is not closed tightly, the pump will be reversed or a water hammer accident will occur.
3) The check valve of the pump outlet, under the impact of the water hammer pressure, often appears to be tightly closed and the valve plate is broken. It is simply impossible to rely solely on a water hammer eliminator to eliminate water hammer, so there is an urgent need for a device that can completely eliminate water hammer. The booster pump automatic control valve produced by Tianjin Guowei Water Supply and Drainage Equipment Manufacturing Co., Ltd. is developed and produced for some of the above drawbacks. It can solve some of the above problems, and it is a new type of energy-saving product without manual and electric operation. Datong City Water Supply Company Ershui Factory!##$$ At the end of the year, the company was remodeled at the end of the year. The product was first contacted in the design, and the traditional process was still selected. The valve selection is shown in Figure 2.
When the designers and company leaders contacted the booster pump self-control valve, after careful investigation and careful analysis and comparison, it was concluded that the biggest disadvantage of the micro-resistance slow-closing check valve is that the closure is not strict and the damage rate is extremely high. After one or several times of use, the valve is damaged and needs to be repaired. This new hydraulic valve can replace multiple valves, that is, only one valve can completely replace the electric valve, the micro-resistance slow-closing check valve and the exhaust. The full function of the valve. Therefore, it is decided to use the valve in the actual installation. The installation of the product is simple and convenient. It is only necessary to install the valve at the water outlet of the pump, and then add a maintenance valve. It can completely eliminate the water hammer without any electrical components, so the water hammer eliminator is saved, which greatly saves The installation space is shown in Figure 3.
The booster pump self-control valve is divided into three parts: the main valve body, the diaphragm control room and the bypass pipe, with the diaphragm as the boundary, the diaphragm above the upper chamber, and the drain pipe, and the diaphragm below the lower cavity. Connected to the valve inlet pipe, the small valve plate is fixed on the valve stem, and the large valve plate slides up and down on the valve stem. When the motor is started, the pressure at the inlet of the valve gradually increases. The pressure water: 1) generates a force that pushes the large valve plate upwards. At this time, the valve cannot be opened immediately (because the diaphragm controls the back pressure of the upper chamber). 2) Pressure enters the lower chamber of the diaphragm control chamber through the bypass tube. As the amount of water in the lower chamber increases, when the pressure in the lower chamber is greater than the pressure in the upper chamber, the pressure in the lower chamber pushes the diaphragm upward, and the small valve plate does not exert pressure on the large valve plate. 3) The large valve plate has a force to push it upwards. Under the action of these two forces, the valve is gradually opened, so as to achieve the purpose of light load, closed brake and slow opening when the pump is started. When a sudden power failure or accident stops the pump or stops the pump normally, the flow rate of the pressure water at the inlet of the valve decreases, and the large valve plate also drops. When the flow rate is zero (ie, the flow rate at the inlet is zero), the large valve plate Due to its own gravity, it is quickly closed (time 3s ~ 5s), which can prevent most of the water from flowing backward. At this time, a water pressure difference is formed before and after the valve, and the pressure water is relieved by the three pressure relief grooves at the bottom of the small valve plate. 4) The pressurized water enters the upper chamber of the diaphragm control chamber from the bypass pipe (this process is a suction chamber, which can effectively absorb a part of the water energy). When the upper chamber pressure water is larger than the lower chamber, the pressure water pushes the diaphragm to move downward. When the lower chamber pressure water is completely squeezed out, the small valve plate slowly descends and returns to the standby state. During this process, the slow closing time can be adjusted (3s to 150s), at which time the valve plate is completely closed, and the dripping water does not leak. Because of its four kinds of water hammer elimination functions, such as quick closing, linear pressure relief, suction pressure chamber and slow closing, it has no sound when it stops, and the effect is very good.
The features of this new hydraulic valve are:
1) No manual, no electricity, completely automatic, relying on the pressure difference generated by the upper and lower chambers when the pump starts and stops to realize automatic operation and control, which provides favorable conditions for realizing water supply automation.
2) It has three functions of control valve, check valve and water hammer eliminator, and also has linear pressure relief function, which saves installation space and reduces loss to some extent.
3) Ultra-wide valve body design. The minimum flow rate is 1.1 times the valve diameter, the maximum is more than 2 times, and the opening and closing pressure is low, so that the head loss is small and the pressure loss is small during the working process. See Table 1 for comparison with alternative products.
It can be seen from Table 1 that the booster pump can completely eliminate the water hammer in the use of the pressurized pump room. In summary, the application of the booster pump in the pressurized pumping room can save installation space, reduce losses, effectively eliminate water hammer, reduce accident rate, and is economically viable, so that the heart of the water supply enterprise can safely and reliably beat. Datong City Water Supply Company has used this valve for more than one year and is running well. It is worthy of promotion and application in the vast water supply industry.
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