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Maintenance method and steps of power plant regulating valve 2020-03-30


The regulating valve is used to regulate the flow of the medium in the equipment and the pipe. Its working principle is mainly to change the flow area between the valve core and the valve seat to achieve the purpose of regulating the flow. The structure has a multi-stage throttling, rotary cylinder, Sleeve plunger type, flat gate type and cage type. Large-scale thermal power plants have complex systems and high requirements on the regulation of the medium. Therefore, the regulating valve is widely used in the steam and water systems of the unit. With the continuous improvement of the unit's automation, the regulation performance of the regulating valve is required. It continues to improve.

 

1, valve disintegration

 

(1) Remove the compressed air pipe joints, solenoid valves, etc. connected to the air control operating mechanism.

 

(2) Loosen the nut that connects the driving rod of the operating mechanism with the valve door rod, and loosen the door rod until it disengages from the driving rod.

 

(3) Loosen the nut of the control device bracket at the upper end of the valve cover, lift out the air control device, and place it in a fixed position.

 

(4) Loosen the bolt of the valve cover, take out the cover together with the door rod, and set it up.

 

5 (5) Loosen the gland bolt, pull out the door rod and door core from the cover head, and place it in a fixed position.

 

(6) Take out the sleeve of the valve body and the split valve wire seat and sealing gasket on the valve seat, and place them in a fixed position.

 

2, cleanup inspection

 

(1) Check the valve line on the valve core and the valve seat, which should be intact, and there are no defects that affect the sealing effect. If there are minor defects, use abrasive sand to grind to eliminate them; if there are deep blowouts or pits, they should be repaired on a lathe; if the valve line damage is severe and cannot be repaired, the spare parts should be replaced.

 

(2) Check that the seal section of the valve stem is smooth and clean.

 

(3) The periphery of the window of the inspection sleeve should be free of oxides and other impurities from accumulating and adhering to it, and if necessary, it should be cleaned.

 

(4) Check that the sealing surface between the valve line and the valve seat on the valve seat should be smooth and complete without dents, trachoma and penetrating scratches that affect the sealing.

 

(5) Check that the sealing surface between the bonnet and the valve body is complete.

 

(6) Check the inside of the valve body, especially the inner wall on the outlet side, and there should be no obvious blow loss and thinning.

 

(7) Check the packing in the packing room and replace it if damaged.

 

(8) All sealing surfaces should be cleaned.

 

3. Reinstall

 

Outfitting is performed in the reverse steps of disintegration. Pay attention to the following points when reinstalling:

 

(1) All gaskets should be replaced with new ones.

 

(2) After the sleeve is assembled, the upper sealing surface and the sealing surface on the valve body should be kept at the same height to ensure the sealing effect of the head and valve seat.

 

(3) When the control seat is connected to the valve body, the nut of the transmission door rod should be tightened to facilitate adjustment.

 

4.Adjustment

 

After the valve is put back in place, install the peripheral accessories such as the gas control joint in place, and adjust the valve with the relevant personnel of the thermal control.

 

(1) Turn on the compressed air, adjust the valve stem to the closed position, then operate the control device to open the valve fully, adjust the door stem to the direction of closing by 2 ~ 3mm, and then adjust the valve stem and the air control device. Fasten the nut.

 

(2) Adjust the valve to the closed position, adjust the valve opening indicator to the zero position, and then operate the valve switch several times to confirm that the valve is fully switched and the switching process is continuously active. If there is no jamming, the limit adjustment ends.

 

(3) Adjust the positioning plate of the action switch so that the action of the action switch is correct when the valve is fully opened and closed.


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