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Key words power plant; valve leakage; measures power plant as the main organization and place of power production, the production and management of power plants is very important, the power plant needs to use a lot of equipment in the production process, but also need to use various pipe networks for media In the process of fluid transportation, the function of the valve is very important. The valve can play an important role in regulating the operation of the pipe network system. If the version leaks, it will cause unnecessary waste of energy resources. During the operation of the power plant, many of the media leaking from the valve are also dangerous, which will affect the safety of other equipment of the power plant and the staff. Therefore, in the process of power plant operation, it is necessary to strengthen the analysis and treatment of the valve leakage problem.
1 Form and Causes of Valve Leakage 1.1 Valve Packing Leakage During the use of the valve, relative movement occurs between the stem and the packing. During the rotation of the stem, the packing will be loose due to long-term external force. Leakage, which includes not only the rotation of the valve stem, but also the influence of temperature, pressure and other factors in the environment in which the valve is used. Under the combined effect of these factors, their filler properties may be affected, aging, loss of elasticity. Therefore, leakage problems occur during use [1].
1.2 Flange Leakage Flange leakage mainly refers to the problem of flange sealing performance of the valve. Generally speaking, the sealing of the valve is mainly achieved by flange sealing. With the pre-tightening force of the connecting bolt and the gasket, sufficient is achieved. Sealing the specific pressure to prevent fluid and media leakage inside the pipe, but after a long period of actual use, the valve may still have flange leakage problems. In general, the causes of valve leakage mainly include insufficient sealing force of the gasket, bolt deformation or other human factors. If the pressing force of the sealing gasket is insufficient, the roughness of the joint surface is insufficient during the use of the valve, so that the position of the sealing gasket moves, and there is a gap between the sealing surface and the flange surface, thereby causing leakage. The bolt deformation is a kind of failure problem of parts such as gaskets and bolts. Once these parts fail, the sealing of the flange surface will be problematic, and the aging or cracking of the gasket will usually occur; human factors The influence on the flange seal mainly refers to the unreasonable installation of the gasket. If the installation process is unreasonable and irregular when installing the gasket, the partial seal of the gasket may be insufficient. In this case, it is easy to leak in the process of use.
1.3 External leakage of valve body External leakage is the quality problem of the valve itself, mainly the key parts of the valve. There are sealing or performance defects in the process of production, such as the existence of pores and cracks in the valve. During the process of use, the liquid is washed and corroded for a long time, which will lead to further expansion of these defects, which will gradually lead to leakage problems.
2 Application measures with pressure plugging 2.1 Countermeasures for valve packing leakage As mentioned above, the valve packing leakage problem is due to the performance of the valve packing itself, which needs to be solved after the occurrence, only from the injection The hole adds a new sealant to it, replacing the seal of the valve material with the performance of the sealant, thereby forming a sealed cavity inside the valve, thereby preventing the valve from continuing to leak. However, in the process of injecting the sealant, the following points should be noted:
1 If the packing box wall of the valve is thicker or larger in diameter, then in the process such as the bee, the hole can be directly opened at the outer wall of the stuffing box, and then tapped with a tap to screw the special auxiliary valve into the screw hole. Open the main valve and then use a baffle with a hole to pass the long drill bit through the small hole into the injection valve, then inject the sealant into it, and tighten the injection valve after the sealant is injected. 2 If the packing box wall of the valve is relatively thin, in the process of injecting the sealant, it is necessary to use the auxiliary clamp for dynamic sealing, increase the wall thickness of the valve packing culvert, and prevent the pressure of the high pressure injection gun during the process of refilling the sealant. Damage to the wall of the stuffing box [2].
2.2 Countermeasures for flange leakage For the leakage problem at the flange connection of the valve, it is necessary to carry out specific analysis for the following situations when solving:
1 If the clearance at the flange is relatively small and the leakage is relatively small, then the bolt-specific auxiliary joint can be directly installed on the removed bolt, the nut can be tightened, the injection bolt can be installed, and the copper wire or the packing can be embedded into the method. In the gap of the blue, a new sealed cavity is formed, and then a sealant is injected therein. 2 If the gap at the flange joint is relatively large, it is necessary to use a convex clamp in the process of designing, and the injection hole is designed in the middle of the two flange connection bolts, and the position of the bolt is staggered, in order to prevent medium leakage, Compressed air can be used to purge the leaked media to one side. 3 If there is a leak at the flange joint of the large diameter, it is necessary to use a local pressure plugging method, fix it with a clamp, and then inject the sealant locally to effectively eliminate the dynamic leak point.
2.3 Countermeasures for valve body leakage When there is a problem of valve body leakage, it is necessary to select an appropriate solution according to the pressure of the medium and the amount of leakage. If the pressure of the medium is small and the leakage is small, then Before the leakage problem is further expanded, the leaking point is polished, and then the appropriate taper pin is sent to the leaking point for temporary sealing, and then externally sealed with an adhesive, and finally the sealing tape is wound on the outside. Sealed to form a new sealing structure. If the leakage medium pressure is relatively large and the leakage amount is relatively large, then in the solution, it is necessary to first weld a nut with an inner diameter larger than the leakage point on the valve body so that the medium can flow out from the nut and cooperate with Corresponding plugs are screwed into the nut to stop the leak [3].
3 Conclusion At present, in the process of using power plant equipment in China, the valve leakage problem is a common and dangerous problem. The long-term leakage of the valve will affect the economic benefits of the entire power plant, and it will also seriously threaten the safety of production personnel. . However, pressure plugging is a relatively professional technology. In the application process, there is a relatively high requirement for the professional ability and knowledge of the workers. Therefore, the power plant's person in charge needs to strengthen the belt for the power plant valve leakage problem. Research on pressure plugging, so as to effectively improve the efficiency and quality of problem solving.
References [1] Zhang Shaojun. Key points for maintenance of common pipe valves in power plants [J]. Technology and Enterprise, 2013, (07): 314.
[2] Gao Xiang, Chen Zhigang. Method of leakage outside the valve and pressure plugging method in power plant[J].North China Electric Power,2008,(10):46-48,51.
[3] Lin Bo. Application of Pressure Sealing Technology in Outer Valve Leakage Treatment of Power Plants[J].Valves, 2006,(02):41-43.
Informatization Analysis of Countermeasures for Valve Leakage in Power Plants
Abstract Power plant is the main place for power production. The operation status of equipment and pipe network directly affects the production and transmission of electricity. Among the many equipments in power plants, valves are the key and important components. The operation of the network has a direct impact. However, in the process of production and operation of power plants in China, valve leakage problems often occur. Long-term leakage of valves will affect the production safety and economic benefits of the entire power plant. Therefore, this paper analyzes the problem of valve leakage in power plants and discusses its Responses.