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Application of New Water Hammer Protective Valve in Jinjiang No.2 Waterworks
I. Introduction of Jinjiang No.2 Waterworks Pumping Station The long-term scale of the second waterworks in Jinjiang City, Fujian Province is 200,000 / d and the first-phase water supply scale is 100,000 / d. Treatment process using enhanced conventional processing. Construction of the water intake pump built on a long-term scale once, according to a 100,000 / d installation of equipment. A selection of three models for the horizontal centrifugal pump 600S47A, dual standby. 600S47A pump technical parameters: Q = 550 ~ 900L / s, H = 46 ~ 37m, n = 970r / min, N = 318 ~ 380kW. Each pump inlet pipe to install a manual butterfly valve, outlet pipe mounted a micro-blocking slow closing check valve and an electric butterfly valve, a manual butterfly valve. Water pipeline length 2224m, diameter DNl000. After put into trial operation in May 2001, due to the water distribution network is not very perfect, the daily water supply 40,000 / d or so, and the automation does not keep up, resulting in frequent open pump units, resulting in more serious water hammer phenomenon, open The measured maximum pressure after the pump down to 1.30MPa, about three times the normal working pressure of water supply, much larger than the specification allows the range (water hammer should be less than 1.5 times the pump pressure), and an increase of electronic control devices and electric head Regular operation, the greater chance of failure, the safe operation of the system caused a potential risk. Second, water hammer calculation and analysis Jinjiang second waterworks take water pumping station water hammer phenomenon, mainly due to the imperfection of automatic management and frequent open stop pump unit to stop the pump water hammer. 9.3.1 of the "Code for Pumping Station Design" stipulates that "it is probable that pump stations with water hammer damage will be required to calculate stop-pump water hammers in the design phase and to allow easy calculation by calculation in the feasibility study stage; Design stage and construction drawing stage should adopt the characteristic line method or other relatively high accuracy calculation method to calculate. " The basic principle of stopping pump water hammer calculation is to establish the equation of motion and continuous equation of water hammer process according to the theory of elastic water column. These two equations are hyperbolic family of partial differential equations. By solving partial differential equations and calculus, Hammer analysis and calculation of the most important basic equations, and by simplifying the incident pump was discharged to simplify the two boundary conditions at the formula, using Newton-Raphson iterative formula, you can solve the γ (actual flow / rated flow) and β (Actual speed / rated speed) approximation. After the calculation, get four groups of pump transient curve (stop pump transient curve refers to the sudden stop pump, flow Q, pressure head H and speed n and torque M, etc. with time curve), a variety of conditions Sewage hammer peak in the table below. No. Basic condition Check valve operation Max water hammer (m) / Occurrence time (s) 1 2 Parallel operation of two water pumps in parallel 19.5s1555.644 / 20.52 2 1 Water pump running evenly Close 19.5s121.295 / 19.44 3 2 sets Parallel operation of the pump run side by side 13.5s105.153 / 16.56 4 1 Turbine pump is running evenly closed 9s68.436 / 13.32 Microstrain slow closing check valve Due to its fast closing construction reasons, can not reach its ideal two stages of retarded (Fast off 80%, slow closing 20%). Stop pumping water hammer because of accidents is a negative pressure wave, positive pressure waves after the process. When the accident pump start, the pump outlet valve Department, the flow rate decreases, the pressure decreases, and due to the balance of micro-resistance balance valve balancer and shaft side of the frictional resistance, the valve plate can not be closed or very slowly closed. When the water starts to flow backwards and the pressure starts to rise, the valve plate quickly closes to more than 80% under the water reflow impact, and then completes the second closing process and the slow closing phase. Water hammer elimination measures are set to bidirectional pressure regulating tower, one-way pressure regulating tower, pressure tank, water hammer eliminator and cancel the check valve and so on under certain conditions, the use of each have their own limitations and deficiencies, it is difficult to universally applied and pushed the factory . Third, the new water hammer protection valve to solve the application of water hammer ①multi-function pump control valve Introduction Zhuzhou South Valve Manufacturing Co., Ltd. developed and produced JD745X-type multi-function pump control valve is a hydraulic principle to achieve the whole process of automatic operation The new hydraulic valve can be fully automatic centrifugal pump to open the pump when the slow open, stop the pump when the slow closure, can effectively stop the pump to stop the production of water hammer. The valve can replace the electric valve, check valve and water hammer eliminator at the same time, does not require any human, electric or hydraulic power as the valve driving force. The structure of the multi-functional pump control valve consists of the main valve and the external accessories, the main valve is composed of the valve body, diaphragm, main valve plate, slow closing valve plate, valve seat, stem assembly and other major components; In the valve body outside the two connecting pipe composition; by properly adjusting the two connecting pipe on the two manual control valve, you can adjust the multi-function pump control valve opening time and slow closing time in order to achieve full automatic control of pump operation skills requirement. ⑵ working principle Multi-function pump control valve is a dual-chamber diaphragm controller, the use of hydraulic principles to control the main valve plate quick closing and slow closing valve plate slow and slow closing action, the work process is as follows: before the pump is opened, the valve After the pressure water into the double chamber controller on the cavity, due to the diaphragm controller plate area is larger than the valve plate area, this time the valve is closed. Pump start, with the pump pressure rising, the pump water on the one hand to produce the main valve plate to promote the opening force, on the other hand into the lower diaphragm controller, the diaphragm lifted up, and the diaphragm controller The water in the upper cavity is connected with the outlet of the main valve through the external pipe to release it. In this way, the multi-function water pump control valve is slowly opened under the controllable speed so as to realize the light-load start of the water pump. When the pump is shut down, the flow rate of the medium in the valve gradually decreases. When it approaches zero, the main valve plate slidably cooperating with the valve stem rapidly slides off under its own gravity, and the main valve plate is provided with a bleed hole to weaken Water hammer impact. After the main valve plate is closed, the pressure loss in front of the valve, pressure water after the valve enters the upper chamber of the diaphragm controller and push the pressure plate to slowly close the slow closing valve plate fixed on the valve rod, thereby eliminating the water hammer and preventing reverse flow of the medium . ⑶ The main performance parameters Nominal pressure: 1 OMPa, 1 6MPa, 25MPa, 4 OMPa Minimum working pressure: O 07MPa Applicable medium: raw water, water, sewage, oil slow closing time: 3-120s (adjustable) Water hammer peak: ≤ 1.2 times the rated pressure of the outlet pump ② multi-function pump control valve selection and installation of Jinjiang Second Waterworks pumping station in August 2001 selection and installation of multi-function pump control just. JD745X-1.0 (DN600) 2 units. Multifunctional pump control valve installation structure is simple and convenient, the original check valve and manual butterfly valve removed, the original electric butterfly valve as a service valve, and then adjust the installation tube can be slightly in the normal operation of the pump, the electric butterfly valve is often Open the state, the electric butterfly valve from the original function of the valve into service valve, greatly reduced the number of opening and closing, therefore, to improve the valve performance and service life, as multi-function pump control valve without external power or accessories , So after installation a little inspection and debugging, you can put into use. Fourth, the multi-function pump control valve to eliminate the effect and evaluation of water hammer Water intake pump room with two DN600 multi-function pump control valve, the operation is very smooth and normal, eliminating the water hammer caused by security risks and greatly improve the safety and reliability. ⑴ pump starts, the pump port pressure shows 0.45MPa - 0.5MPa, and then after about 30s slowly down to about 0.39MPa, the valve before the valve after the pressure difference of about 0.01MPa-0.02MPa, indicating that the valve Resistance loss is minimal. (2) When the pump is shut down, the main valve plate of the valve will be closed automatically at zero flow rate, and then the slow valve plate will be closed at about 40s, the pressure at the outlet of the valve will drop to about 0.26MPa first and then rise to 0.47MPa, Finally, slowly dropped to the network pressure value of their own, the increase in pressure rise is very small, within the allowable range of the specification, indicating that the valve closing effect is very smooth, eliminating the effect of water hammer is ideal, with a slow open and Quick closure, slow closure, absorbing three kinds of fire water hammer way, and the action completely interlocked, will not produce misoperation, stop the pump when the valve does not sound a little, vibration, and close the valve tightly. ⑶ Because this valve is fully automatic hydraulic control principle, in full accordance with the operation of the automatic operation, so management, operation is very convenient, without special management, greatly reducing the labor intensity of workers, the valve structure is simple, fewer points of failure to install , Debugging is very convenient, basic without maintenance and repair. Through this application practice, indicating JD745X-1.0-type multi-function pump control valve as a check, pump control, eliminating the three functions of water hammer in one of the new valve, no electrical control, no external power, in full accordance with the pump operation Automatic opening and closing procedures, simple installation, convenient management, high safety and reliability, it is an ideal new product for the selection of the valve on the pump pressure pipe. It is very suitable for the automatic control of water supply, and for the safe operation of pump room and pipe network The ideal conditions.