Daily Maintenance Management of Gas Control Valves in Coal Chemical Plants-1

- May 10, 2018-

In coal chemical installations, the process medium is mostly pulverized coal, black water, slag water, etc., and the scouring of valves and meters is very serious. Therefore, the maintenance of valves is more important and the requirements are more stringent. In view of the complexity of the pulverized coal gasification process and the adverse effect of the working environment on the valve, the effective experience in the maintenance, maintenance and repair of the valve of the coal chemical enterprise was discussed. The valve was visually managed and daily The maintenance and commissioning and the planned maintenance put forward better suggestions and effective implementation methods, providing a reference for valve management of similar devices.


    The valve is the control device of the fluid pipeline. Its main function is to cut off or connect the circulation of the medium in the pipeline, change the flow direction of the medium from the role of the diversion medium, and regulate the medium pressure and flow in the pipeline. Warm and overpressure safety protection to protect the normal operation of the pipeline equipment. Therefore, the management of the valves is of great significance for ensuring the safe and stable operation of the production equipment.


1, the type of coal gasification valve

    In view of the complexity of coal gasification coal gasification process in coal chemical companies and the harsh environment of work environment, the types of valves used in the coal gasification industry are many, such as pulverized coal cut-off valves, pulverized coal control valves, oxygen valves, and black water angle valves. Skate valve, high pressure differential vent valve, etc.

1.1 Angle Black Water Regulator

    Angle black water control valve is specially developed for the harsh working conditions of coal chemical industry, can withstand high-strength erosion, corrosion and high pressure differential system, suitable for coal chemical industry in the gasification, flash evaporation and slag water treatment and other sections to achieve the process The precise control of the flow, pressure, liquid level, etc. of the medium, and the multi-stage flash evaporation of the discharged black water in order to recover the grey water and heat.


    The use of black water regulating valve, valve seat, valve core using tungsten carbide as a whole sintering, diffusion section, inner liner or tungsten carbide spray coating, both to ensure that the seat, valve core hardness and anti-scour, but also from the material to improve Valves are corrosion resistant and suitable for high flow media. The valve body is improved on the basis of the venturi valve, the flow passage large arc smoothly transitions, and the flow resistance is extremely small, so that the medium is maximally prevented from flushing the valve trim and the valve cavity. The flow passage cross-sectional area of the throttle (valve seat) is changed from fusion to gradual change, effectively avoiding the cavitation damage to the valve trim. The unique design of the scraper type, lower positioning, and lower anti-rotation of the lower guide end, as well as the valve seat position and the stem guide device are greatly reduced, and the side in and bottom out to enhance the self-cleaning function and stability. The valve stem and packing are protected from the design and craftsmanship. The outer surface of the valve stem is sprayed with Ni60. After grinding, the surface finish is polished to a mirror surface of 0.4 or more. Under scouring and strong corrosion, (the surface of Ni60 produces a material similar to enamel glaze), it effectively protects the smoothness of the stem, reduces the media adhesion of the stem, and avoids damage to the filler caused by damage to the stem. Leak in the mouth.


1.2 Pulverized coal cut-off valve and lock slag valve

    For the lock-slag valve and the pulverized coal valve, the valve zero leakage or lower leakage is critical, once the ball valve has a slight leakage, micron-sized pulverized coal under the action of high-pressure gas is very destructive, the valve ball and the seat seal The surface is damaged, the inner leakage can not maintain the pressure, stuck, pulverized coal leakage to the valve cavity so that the valve switch is not in place and then stuck; the small slag in the lock slag valve enters the sealing surface under the action of high pressure water vapor, resulting in scratches, leakage Will be further increased, resulting in failure to maintain pressure, switch is not in place and then stuck. Therefore, the amount of leakage is the primary consideration in the selection of pulverized coal cutoff valves and lockup slag valves.


2, the daily maintenance of the valve

    The preventive maintenance of industrial high-temperature and high-pressure valves can reduce the appearance of valves when they are used, and is the most economical and reliable way to solve valve leakage and prolong the service life of valves. The daily maintenance of the valve pursues “seven-point three-point maintenance”. For the valve maintenance work, more important is prevention and routine maintenance.


2.1 The establishment of the valve ledger

    Establish and improve the accounting system for each valve and shut-off valve in the production facility. The ledger includes the valve specification, type, purpose, process media, medium temperature, medium pressure, valve body material, valve stem material, valve diameter, action mode, flow characteristics, packing seal type, solenoid valve model, positioner model, execution The important information such as the organization form, adjustment form, power source form, and so on, in order to better understand the important parameters of the regulating valve and the shut-off valve and the valve models needed for the production characteristics. Establishing and perfecting the account is a prerequisite for our work and a prerequisite for doing a good job. Therefore, the ledger must be focused on management and updated in a timely manner according to the situation so that it is easy to grasp first-hand information from the ledger so that routine maintenance can be done. Not passive.


2.2 Visual Management of Field Valves

    In order to make operators clear the principle of on-site valves, maintenance methods, inspection points, to facilitate the timely and accurate disposal of the valve in the event of a fault emergency situation, the valve work principle, structural diagrams are collected, and posted to the site; the device All the pneumatic valve switching modes and valve fault positions are counted, and the identification plate is made to be hung on the site. The position of the pneumatic valve is marked by brushing; the inspection points of the valve are printed and sealed and posted to the site to realize the valve equipment. The site visual management.


    After the visualized management is implemented, the basic structure and principle of the corresponding regulating valve can be quickly distinguished during inspection and maintenance. That is, the inspection time is saved and the lost and lost during the inspection process is avoided, ensuring the high standard and high quality of the maintenance work.


    Valve gas source as the power mechanism of the valve should also be regarded as the key point of day-to-day management. The gas source listing identification of the valve, the on-site gas source pipe valve fixing and the hanging sign plate must be used to prevent personnel from accidentally closing the gas source valve, causing the valve to suddenly Loss of gas shuts off or opens.


2.3 On-site valve periodic inspection

2.3.1 Regularly check the regulating valve and shut-off valve every month to check whether the pressure of the air source is normal, whether there is leakage of the filter gas source connector, whether there is leakage of the valve positioner gas source connector, or whether the gas cylinder and the gas source connector have joints. Non-leakage, fixed gas source, vibration, positioner inlet seal, valve components without rust and mechanical damage, valve stem is clean, feedback fasteners loose, check shaft packing seal Whether there is leakage at the sealing gasket, etc., and the inspection results are recorded in a timely manner. The operating operator and maintenance personnel are responsible for signing the confirmation, and the problems are easy to deal with in a timely manner. Regularly lubricate the screws and moving parts of the regulating valve to lubricate the grease; regularly pressurize the pressure reducer and the positioner.

2.3.2 In order to prevent the abnormality in the operation of gasifier shut-off valve from being detected in a timely manner, identify and identify important valve lists, establish a gasification device and importantly cut off the valve action schedule, check and record the important valve action time in each shift, and submit it to automation. Engineers conduct audits and comparisons. Abnormalities in valve operating time can be detected in a timely manner. Further inspections and confirmations are made. Valves are maintained and processed in advance to achieve the purpose of pre-inspection and pre-repair, avoiding sudden failure of the valve and causing system shutdown.


2.3.3 The long-term non-actuated valves, high-pressure venting shut-off valves, etc., shall be commissioned once a week to reduce the jamming of valves and avoid normal opening and closing in the event of an emergency.