FQ647F_16C pneumatic coal injection valve DN32 Design

 Valve models should normally be expressed valve type, drive type, connection type, structural features, sealing surface material, body material and nominal pressures and other factors.Standardization of valve type valve design, selection, sales provides a convenient. Today the type of valve and materials more and more, the valve for the model is more complicated. Although the preparation of a unified standard valve type, but can not meet the growing needs of the development of industrial valves. At present, the valve manufacturer generally uniform numbering method, where the method can not be used uniform numbers, each manufacturer according to their needs develop numbering method. FQ647F-16C pneumatic coal injection valve model based on national standards and the development of methodologies Shantou valve plant shown in Figure 1.

Figure 1 valve type arrangement

     

    Two pairs of valve performance requirements

    FQ647F-16C pneumatic coal injection valve DN32 with reference to international advanced design and manufacture of the prototype of the new structure dedicated coal injection valve, is the metallurgical blast furnace pulverized coal injection system on the device-specific accessories. In order to meet different specifications, different kinds of steel, coal injection valve by turning the blast furnace pulverized coal combustion play a role in raising the temperature of the blast furnace, coal injection system must be ready quickly open and close in order to meet the temperature requirements, and its rapid opening , turn-off is controlled by the computer to achieve. Therefore, pulverized coal pneumatic valve must have the following three characteristics:

    (1) The response speed required to complete in 1 ~ 2s open and close operation to meet the requirements of automatic control computer;

    (2) to stabilize the pressure in the pressure pipe and pipe medium coal incidental leakage of harmful gases, so pneumatic coal injection valve does not leak;

    (3) To protect the sealing surface being pulverized coal injection erosion and wear, do not appear sealing surface strain and stuck (rotation is not flexible) phenomenon, so you must use the fully open or fully closed, prohibited by throttling.

    Three ball design

    3.1 Work

    The ball valve body and the pneumatic device by the two parts. Opening and closing movement by pneumatic actuator - cylinder driven valve stem rotation, so as to drive the ball forward and reverse rotation 90 ° to achieve.

    To open the valve (that is, the sphere diameter flange diameter on the same axis), the compressed air from the actuator of the A-side air intake, push the piston moves backward, the piston rod driven through the turn crank lever rotation, and between the lever and the valve stem cap connected to the use of square, the turn lever is rotated, following the rotation of the stem, but also led to the sphere is rotated clockwise 90 °, so that the valve in the through state, the pressure medium in the pipeline coal through the blast furnace pulverized coal injection valve. When the valve opening, as shown in Figure 2.

Figure 2 valve opening

Figure 3 valve off

    Conversely, to close the valve when the inlet from the B-side, the piston moves forward, driving the ball rotated counterclockwise 90 °, the valve is closed, as shown in Figure 3.

    While the valve is in the fully open or fully closed state, the need to adjust the pneumatic actuator positioning adjustment screws on the two, you can make the ball was fully open or fully closed.

    3.2 Ball Structure Description

    3.2.1 fixed dome structure (shaft-supported)

    To reduce the valve operating torque and enhanced reliability of sealing and avoid compression of the ball is displaced, and the outlet end of the first sealing surface wear, so the ball valve the fixed structure, its structure is shown in Figure 4, which uses The lower shaft of the ball the ball fixed (stem, the sphere and the centerline of the shaft must be on the same axis). Structure in the form of fixed ball valve comes with floating seat, or pressure in the sphere rotates, the valve seat moves, seals are pressed onto the ball, in order to ensure sealing. Usually with the ball of the upper and lower shaft with bronze sleeve bearings or self-lubricating bearings, reduce operating torque.

Figure 4 fixed ball structure

    3.2.2 sealing structure

1 sphere 2 ring 3. Seat 4.O-ring 5 disc spring 6. Adjustable pads 7. Flange

Figure 5 sealing structure

    The sealing structure of the valve shown in Figure 5. Tight seal 2 3 mounted on the seat, the seat 3 in the flange 7 4 sealed by O-rings, seals and 2 by means of disc springs 5 pre-compacted in a sphere, adjust the adjusting shim 6, I can adjust the tight sealing surface than the pressure. To the disc spring seal structure, with a sealing action with automatic compensation. The seal between the gasket and the ball except the pre-compacted by the coned disc spring to ensure sealing, the still rely DWN and seat ring outer diameter D _JH loop area formed by the pressing force of the ball on the medium to achieve the seal, seal Reliability depends largely on the average diameter of the sealing surface D _MP and the valve seat diameter D _JH ratio. If D _JH / DMP value is not large enough, the ball will not be able to ensure a reliable seal; if D _JH / D _MP value is too large, it will cause an overload sealed, leaving the valve switching torque increases, accelerated wear and tear.

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