Liu Wei, Wang Shuhao: Application of pressure wave propagation velocity difference in analysis of pipeline leakage points, oil and gas storage and transportation, 2000, 19 (5) 5657. Subject headings Application of pressure reduction wave leakage points of oil pipelines to oil pipelines (Qinhuangdao-Beijing) The oil has been stolen 11 times, which not only caused great economic losses to the country, but also seriously affected the normal production of the entire pipeline. Because criminals use pipeline pressure-opening technology and conceal the site completely after oil theft, it is difficult for the management personnel of oil transmission companies to find the location of oil theft in time. Therefore, the company management personnel are constantly exploring while strengthening pipeline management The experience of quickly and accurately determining the opening points of criminals stealing oil provides a feasible method for applying the principle of differential pressure wave propagation velocity difference in the process of pipeline fluid transportation. 1. Principle The United States developed the directional pressure wave alarm technology in the late 1970s. However, with the diversification of oil transportation technology and operation methods of long-distance pipelines, the promotion and application of this technology have been limited, such as open and closed oil transportation. The accuracy of the pressure transmission speed varies greatly. When the whole oil pipeline is transported in a closed manner, the oil coming from the upper station does not pass through the bypass tank, and directly enters the oil pump of the lower station to pressurize. The pressure does not pass the attenuation loss of the bypass tank during operation. In the closed operation state, when the pipeline is perforated and oil is stolen, due to the pressure difference between the inside and outside of the pipeline, the crude oil is quickly lost at the opening point, and the pressure in the pipeline drops. The crude oil on both sides of the pipe is replenished to the opening. This process is transmitted upward and downstream in sequence, which is equivalent to the generation of a decompression wave propagating at a certain speed at the opening. The positioning method of transient decompression wave is to calculate the position of the opening according to the time difference between the upstream and downstream propagation of the transient decompression wave generated at the opening and the propagation speed of the decompression wave in the tube. The propagation speed of decompression waves in crude oil is generally about 1 1200 m / s. As long as the decompression wave sensors at both ends of the pipeline accurately capture the decompression waves containing oil theft information, the occurrence of oil theft can be detected The positioning is based on the time difference of the decompression wave propagating to both ends and the propagation speed of the decompression difference. L. The distance between upstream and downstream stations, m; the difference between the pressure sudden change time of the upstream station and the pressure sudden change time of the downstream station, s. Second, application examples October 27, 1999 Qin-Beijing oil pipeline segmented closed oil transportation, 23:49:55 The outgoing pressure of the upstream Qinhuangdao oil station suddenly dropped by 0.08 MPa, and the incoming pressure of the downstream Changli oil station suddenly dropped at 23:50:07. 23:52:43, 23:54:07 sudden drop, the pressure difference time difference of each station is 12s, 156s, 84s. The distance between each oil pump station is 60km, and the propagation speed of decompression wave in crude oil is generally 11200m / It is about s, so the time difference between the decompression wave to the upstream and downstream stations cannot exceed 60s, so it is concluded that the opening point is between the upstream Qinhuangdao oil station and the nearest downstream station Changli oil station. The distance from Qinhuangdao oil station should be 24km. The on-site line inspection found that the oil theft point was 26km away from the upstream Qinhuangdao oil station, and the error of the location of the opening point was 3. After calculation, the relevant data of the pipeline when the criminals stole the oil on November 25, 1999 are as follows. The calculation result is that the opening point is 27. 26.3km away from the upstream station and the criminals and vehicles are captured at the opening. The calculation error is three. The problem of the decompression wave propagation velocity difference formula However, the actual a depends on the elasticity of the pipe wall and the compressibility of the liquid. There are few foreign studies on heat transfer crude oil pipelines, and the change of a is neglected. If there is a more accurate formula for calculating the value of a, then the oil steal hole Point judgment will be more accurate. In addition, under the conditions of the open oil transportation process, abnormal changes in the tank position of the intermediate station are also the main factors for judging whether to open the hole to steal oil. The on-site inspection of the pipeline is also an important part of discovering the openings of oil theft and arresting criminals as soon as possible. The pipeline management personnel of Qinhuangdao Oil Pipeline Company patrolled and understood along the route, drawn a map of roads and intersections along the route that are close to the pipeline and where heavy-duty vehicles can pass, and were familiar with the landform features along the route, in order to discover problems in time. If you can quickly determine the location of the oil-stealing hole, you can rush to the scene and arrest the criminal within 40 minutes from the nearest oil station. Bathroom Hardware,Shower Door Rollers,Bathroom Hardware Sets,Modern Bathroom Hardware BNF HARDWARE CO., LTD , https://www.bnfhardware.cn
Application of pressure wave propagation velocity difference in analysis of pipeline leakage point