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Thermal power plant valve pressure plugging technology
Power plant valves are mainly used to control a variety of equipment and their pipeline fluid medium operation, valve leakage often occurs in the packing, flange seals and valve body, valve leakage for a long time can cause stem and flange sealing surface of the red Erosion, the final valve can be scrapped, coupled with the loss of fluid medium, the power plant to increase consumption, rising costs, economic decline. If the medium fluid is toxic, flammable, explosive, corrosive and so on, leakage, such as poisoning, fire, explosion and other casualties and accelerating the corrosion rate of plant equipment, shorten the service life, pollute the surrounding environment seriously and damage the power Production, damage people's health. The existence of the leak poses a serious threat to safe production, resulting in an increase in unplanned downtime of power plants. The following describes some of the causes of valve leakage and plugging methods and the valve repair and maintenance methods for reference. 2, the form of leakage and the factors 2.1 Leakage of valve packing and the reasons Valve in operation, the valve stem with the filler there is a relative movement, which includes rotation and axial movement. As the number of switches increases, the number of relative motions also increases, as well as temperature, pressure and the characteristics of the fluid medium and other effects, the valve packing is the most prone to leakage sites. It is due to the gradual reduction of contact pressure of packing, filler aging itself, loss of elasticity and other causes. At this time, the pressure medium will leak outwardly along the contact gap between the packing and the stem, and will blow away a part of the filler and flush the stem out of the groove for a long time, so as to enlarge the leakage. 2.2 Flange Leakage Flange valve seal is mainly relying on the bolt preload, through the gasket to achieve a sufficient seal than the pressure, to prevent the pressure fluid sealed by the leak. There are many reasons for its leakage, gasket insufficient pressure, the surface roughness does not meet the requirements, gasket deformation and mechanical vibration, etc. will cause the seal gasket and the flange surface of the joint lax strict leak . In addition bolt deformation or elongation, gasket aging, resilience decline, such as cracks can also cause the flange surface sealing lax and strict. Flange leaks can not be ignored as human factors, such as partial installation of gaskets, partial pressure than partial tight tight, over the gasket design limits, and the uneven force in the process of flange fastening or two methods Lan center line offset, resulting in fake tight phenomenon are prone to leakage. 2.3 The leakage of the valve body and the reasons for leakage of the valve body is mainly due to the valve manufacturing process casting or forging defects caused, such as trachoma, pores, cracks, etc., and fluid medium erosion and cavitation is also caused by valve body leakage Common factors. 3 with pressure plugging principle and advantages 3.1 Principle of pressure plugging The principle of pressure plugging is based on the liquid medium in dynamic conditions, the solid sealing material sealing mechanism as the basic basis. Method is to install special equipment leak site, the use of sealing parts and special equipment formed between the chamber, the use of special high-pressure plastic injection tools will be injected into the chamber sealant, and filled the entire chamber space, the sealant squeeze The force is balanced with the pressure of the leakage medium, and a new sealing structure is established to block the passage of the leakage pores and block the leakage of the medium. 3.2 The advantages of pressure plugging (1) does not require downtime or isolation of the system. (2) No pressure relief to the system. (3) Save a lot of energy and manpower. (4) greatly reduce the power loss caused by equipment isolation or downtime. (5) Reduce the social and economic losses. 4 Several common leakage point pressure sealing method introduced According to the specific conditions of the power plant production site, you can use to replace the valve, replace the valve packing, flange gasket replacement or welding holes to eliminate the general method of leakage.