RKSfluid High temperature hard seal ball valve in chemical fiber steam application

RKSfluid design high-temperature hard-sealed ball valve used in chemical fiber steam introduces the sealing characteristics of high-temperature hard-sealed ball valve, analyzes the seat structure and sealing principle of various hard-sealed ball valves, and proposes an improved method of hard-sealed structure.
Product name and model: High temperature ball valve Ball valve has been widely used in petrochemical industry, long-distance pipelines and urban heating industries due to its characteristics of small fluid resistance, convenient operation, rapid opening and closing, good sealing and high reliability. The valve seat material adopts polytetrafluoroethylene (or filled polytetrafluoroethylene) as a soft-seal ball valve, and its operating temperature does not exceed 200 ° C. The valve seat material is made of metal, which is called hard-sealed ball valve or high temperature ball valve, and its use temperature is higher than 250 ℃. In recent years, in order to meet the needs of high temperature working conditions, domestic and foreign ball valve manufacturers have optimized the sealing structure of high temperature ball valves, which has significantly reduced the opening and closing torque, greatly extended the service life, and significantly improved the operating performance. The chemical fiber industry occupies an important position in the national economic and social development, and is also the country's main foundation and raw material industry. In the past two decades, China's chemical fiber industry has achieved rapid development. Among synthetic fiber varieties and structures, the output of polyester staple fiber accounts for one-third of the total national chemical fiber output. In 1992, Sinopec Energy Conservation Center calculated five names in the system. The average comprehensive energy consumption of major short-fiber manufacturers listed in the top of the country is 0.341t / t (standard oil), which is significantly different from the domestic level of 0.269t / t (standard oil). Zh
2.High-temperature hard-seal ball valve in the chemical fiber steam application ball valve hard seal structure
2.1 Sealing characteristics
The sealing feature of high temperature ball valves is mainly the use of metal sealing pairs, which has the advantage of a wide range of applicable temperatures, and the thermal expansion coefficients of various metals are not much different. As long as they are properly selected, they can be basically consistent, which is conducive to coordinate temperature difference deformation. The disadvantage is that the material has high hardness, and the specific pressure necessary to achieve the seal is high. Even if the pre-tightening force is used to achieve the seal, the wear between the valve seat and the ball is also large due to the large specific pressure of the seal, and the friction coefficient of the metal sealing surface is relatively high. Large, resulting in large opening and closing torque of the ball valve. Therefore, high temperature ball valves mostly use elastic sealing pairs, which have reliable performance, strong elastic compensation ability, wide application temperature range, and are suitable for both floating ball and fixed ball valves. Under the action of pre-tightening force and fluid pressure, the high temperature ball valve compresses the valve seat with the ball, which deforms the sealing surface of the valve seat to achieve sealing. Its sealing effect depends on the degree to which the valve seat can compensate for spherical out-of-roundness and micro-unevenness under the action of fluid pressure and pre-tightening force. Therefore, there must be a sufficient sealing specific pressure qb between the valve seat and the ball, and it must meet the
Where qb —---- the specific pressure to ensure the valve seal, MPa
q ———— Actual specific pressure during valve operation, MPa
〔Q〕 ———— Allowable specific pressure of valve seat material, MPa

2.2. Structural analysis of high temperature hard-sealed ball valve in chemical fiber steam application
(1) Seal structure of floating ball valve
The hard sealed high temperature ball valve shown in 1 is composed of a valve body, a ball body, a valve stem, a metal valve seat, and a flexible graphite seal ring between the valve seat and the valve body. The two valve seats are embedded in the valve body with the valve rod axis as the center of symmetry, the valve seat slides in the valve body embedding groove, and the seal between the valve seat and the valve body is realized by a flexible graphite seal ring. Due to the compressible deformation of the flexible graphite sealing ring, the ball valve of this structure will not be stuck due to the thermal expansion of the ball when it is used in a certain temperature range, and it can not be operated. Zh
1. Valve body 2. Ball 3. Stem 4. Sealing ring 5. Valve seat
High temperature ball valves use metal elastic rings as valve seat seals to compensate for changes in external conditions such as temperature differences, pressure and wear on the ball valve sealing performance. The valve is composed of a valve body, a ball body, a valve stem, a metal valve seat, a flexible graphite seal ring between the valve seat and the valve body, a metal elastic ring, a metal elastic ring pressure ring and a gasket. One of the two valve seats is a metal valve seat that can slide in the valve body embedding groove, and the other is a deformable metal elastic ring valve seat. When the ball of the structure is heated and expanded, the metal elastic ring valve seat can be deformed, so that the ball does not get stuck and cannot operate. Zh
High temperature hard seal ball valve in chemical fiber steam application 1. seal ring 2. valve seat 3. valve body 4. ball 5. valve stem 6. pressure ring 7. metal elastic ring 8. seal
Shanghai Qizhong Valve Co., Ltd.'s main valves are: globe valve, electric globe valve, high temperature ball valve using a disc spring-loaded sealing structure. The valve is composed of a valve body, a ball, a valve stem, a valve seat, a valve seat sealing ring, a valve seat, a valve seat sealing ring, a pressure ring and a disc spring. The front valve seat, the front valve seat sealing ring and the pressure ring are a component, and a disc spring is pressed on the component. After the ball valve is assembled, the disc spring is compressed. On the one hand, it provides the initial force for the valve seal, and on the other hand, it compresses the seal ring between the valve seat and the valve body to seal the valve seat and the valve body. The two valve seats of the ball valve of this structure are embedded in the valve body with the shaft center of the stem as the symmetrical center. Can't move. Zh
High-temperature hard-sealed ball valve in chemical fiber steam application Product features and uses:
Adopt the full-diameter floating ball valve sealing structure design, large flow capacity, small flow resistance, low switching torque, high temperature and not easy to block. Zh
The heightened stuffing box seal structure is adopted, and the filler material is selected from flexible graphite. Reliable outer seal. Zh
The valve seat is provided with a disc spring group, which can effectively absorb the thermal expansion of the ball and the valve seat under high temperature conditions. Zh
The two ends of the valve adopt flange structure, and the middle flange adopts stainless steel toothed pad + flexible graphite compound. Zh
The valve stem and the ball are connected in a flat square, which improves the transmission performance of the valve. Zh
The stem is designed with an integral shoulder to prevent the stem from blowing out. Zh
A wide range of applicable media, more suitable for high-temperature hard particles containing gas and air and powder particles.