Numerical Simulation Study of Throttle Orifice Plate of Large Pressure Drop and Short Distance Pipeline Yu Lingmin, Li Honglin (Henan Oilfield Mobility Department, Nanyang 4731, Henan, Zeng Xiaokang, Zhou Yuan (China Nuclear Power Research and Design Institute, Chengdu 610041, Sichuan Province) I 丨 For Orifice The problem of strong vibration and high noise in the application of large pressure drop and short distance Sugao, the mechanism of the vibration of the Shoudao installed with the orifice plate was analyzed. Through the numerical simulation of the large pressure drop and short distance pipeline orifice plate The layout and structure of the orifice plate to mitigate the vibration of the pipeline are proposed. The results show that the two-level eccentric porous orifice plate form can effectively reduce the influence of large pressure drop and short distance cavitation and vortex phenomenon, thus alleviating the violent vibration.
I 丨 throttle orifice plate; pressure reduction; numerical simulation 2 I 丨 A large pressure drop and short distance pipeline orifice plate device is widely used in various industrial pipeline systems to achieve the purpose of reducing the pressure of soda and reducing the flow of soda. For larger pressure drop systems, the unreasonable setting of the orifice plate will lead to increased vibration of the pipeline and accompanied by strong noise, which will cause serious damage to the structure of the pipeline and the integrity of the system Yu Minmin (1963-), male, 1993 Graduated as an engineer, he is now mainly engaged in research work on oil field equipment matching; E-mailhnytylm is 457m3 / h; water medium temperature is 60 ° C; inlet pressure of throttle orifice plate is 20MPa; outlet pressure of throttle orifice plate is 021MPa; The specification is 02l9X12mm; the length of the pipeline is 460mm. 21 single-stage orifice orifice plate single-stage orifice plate streamline distribution diagram as shown. It can be seen that the velocity of the center line of the pipe behind the orifice plate is very high, which produces a vortex with a length of about 06m, which causes low-frequency vibration of the pipe. The pressure distribution diagram before and after the single-stage orifice plate is as shown. It can be seen that there is a negative pressure zone of about 300 mm downstream of the orifice plate. The pressure in this area is lower than the temperature of the water medium (60 corresponding saturation pressure CPv = 5 62X1iMPa) 13. At this time, it causes cavitation, which induces high-frequency vibration in the pipeline. Therefore, the design should not adopt the form of single-stage orifice orifice plate.
222 level concentric orifice orifice plate 2 level concentric orifice orifice plate distribution diagram as shown. It can be seen that the high-speed water flow through the orifice plate of the first stage directly passes through the orifice plate of the second stage due to the too small distance between the throttle pieces and the concentric circle structure, resulting in a vortex with a length of about 0.5m, which causes low frequency vibration. The pressure distribution diagram of the front and back of the concentric orifice plate of level 2 is as shown. It can be seen that there is a negative pressure zone of about 350mm downstream of the second stage, which leads to more serious cavitation, which causes severe high-frequency vibration of the pipeline. Therefore, it is not advisable to adopt the form of concentric orifice plate with 2 levels in design.
The pressure distribution diagram of the front and back of the 23-stage eccentric porous orifice plate and the 2-stage eccentric porous orifice plate are shown below. It can be seen that due to the eccentric porous structure, the water flow velocity is relatively stable, and only a vortex with a length of about 0.35m is generated after the second-stage orifice plate, so the low-frequency vibration of the pipeline is very small. The pressure distribution diagram before and after the second-level eccentric porous orifice plate is as shown. It can be seen that there is only one negative pressure zone with a length of less than 50 mm downstream of the second stage, so the probability of cavitation is small, and the pipeline will not generate high-frequency vibration. Therefore, the design can adopt the form of 2-stage eccentric porous orifice plate (see and).
3 Junction 1) When adopting the form of single-stage orifice plate or two-stage concentric orifice plate, large-scale eddy current and cavitation will occur, which will cause severe vibration of the pipeline.
Pressure distribution diagram before and after secondary eccentric orifice orifice plate. Pressure distribution diagram before and after secondary eccentric orifice orifice plate. Plane drawing of optimized orifice orifice plate. Second stage orifice orifice plate (left view). In the form of orifice plate, the vortex generated is small, and the probability of cavitation is small, so it will not cause violent vibration of the pipe, and it can play the role of throttle and pressure reduction.
Zhang Duqing, Zhang Guangcheng, Cao Lichun. Causes and countermeasures of vibration of steam and water pipes in power plants. Shandong Electric Power Technology, 2006 (1): 5fr57 Zhang Baofeng. Design and calculation of multi-stage orifice plate. Northwest Electric Power Technology, 2005 Zhang Bao, Hu Nengxiang, Xu Jinxi. Reasonable application of throttling orifice plate in soda pipes. Power Station System Engineering, 2005 Li Qidong
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