Daily Maintenance Management of Gas Control Valves in Coal Chemical Plants-2

- May 11, 2018-

3, valve inspection, maintenance

    The maintenance of valves in chemical companies is also indispensable. Valves in the long-term operation are easily subject to external environmental pollution, such as rain, snow, dust, sand, etc., and are affected by the flushing of conveying medium and mechanical wear during operation. The valve will produce different degrees of damage, and timely repair can control the damage in an acceptable state and repair it in time. In recent years, we have gradually advanced the cycle management of valves and components, identified the service life of valve wearing parts, checked and replaced the valve wearing parts according to the operating cycle, and realized the pre-repair of the valve, which ensured the long period of the valve. run.


3.1 key parts of valve repair

The key inspection locations during valve overhaul include the following aspects:

1) Check the inner wall of the valve: In the occasion of high temperature, high pressure difference and corrosive medium, the inner wall of the valve is often subjected to the impact and corrosion of the medium, and the pressure and corrosion must be checked;

2) Check valve seat: Because the medium penetrates during work, the inner surface of the thread used to fix the valve seat is susceptible to corrosion and causes the valve seat to loosen;

3) Check the valve core: The valve core is eroded by the medium during the working process. When the inspection is over, check whether the various parts of the valve core are corroded and worn.


3.2 The maintenance work of the valve during the overhaul

1) During the shutdown of the gasifier, the important valves of the gasifier shall be replaced and replaced, and the air source and air pressure reducing filters of all valves shall be dismantled. All coal valves, pressure relief valves, balancing valves, lock slag valves, flushing water valve actuators, valve balls, forks, etc. are inspected and problems are promptly replaced and repaired.



2) Due to the problems in the design of the black water flow control valve, the ash is likely to accumulate in the valve cavity. After the ash accumulation, the valve spool is often stuck or inoperable, which seriously affects the process adjustment. During the overhaul, the valve was dismantled and investigated. It was found that the pressure opening in the valve seat caused the backflow of grey water to the valve cavity, and the accumulation of ash residue could not be discharged. The internal structure of the valve core was modified and the pressure inside the valve seat was equalized. Welding is blocked to prevent backflow of grey water, and the valve operates well after driving.


3) Maintenance of pulverized coal cut-off valve: During the overhaul, check the surface corrosion of the valve surface of the pulverized coal cut-off valve, polish and clean the external surface of the valve, paint after the assembly pressure test is completed, check the ball wear condition, and use thermal spray nickel. Base hard alloy plus tungsten carbide hardened; rework the worn valve seat and match with the ball; straighten the deformation of the cylinder barrel; replace the seat spring, graphite self-expanding seal ring, packing seal assembly, valve body compound Gaskets, cylinder seals.


    The maintenance of the regulating valves and shut-off valves of coal chemical installations is a persevering task that runs through the whole process of production and operation of the entire plant. All maintenance personnel are required to be vigilant at all times, adhere to high standards of maintenance, maintenance and repair, and start from the details. Start with the actual operation of the company itself to ensure long-term, safe and stable operation of the device.