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The use of knife-type gate valve in coal washing plant and precautions

After a heavy coal reform in a coal washing plant in 1998, the coal washing process is mainly jigging rough selection, heavy medium cyclone selection, and coal slurry flotation. The heavy medium process pipeline is mainly a solid-liquid two-phase mixed heavy medium suspension. The medium is seriously worn on the pipelines and equipment. The gate valves used in the pipelines are mainly knife-type gate valves. The knife-type gate valves currently used in coal washing plants are divided into three types: manual, electric and electro-hydraulic. The main types are PZ73 manual clamp type knife gate valve, PZ973 electric wafer type gate valve, PZ273 electro-hydraulic clamp type knife. Type gate valve, the manufacturer is mainly Zhejiang Zhongcheng Valve Factory. The knife type gate valve is composed of a valve body, a valve plate, a valve stem, a hand wheel (drive device) and a sealing member. The gate plate, the valve stem and the upper cover are made of stainless steel, and the wear resistance is good, and the valve body is carbon steel. Seals are divided into rubber, fluoroplastic and alloy steel seals. The opening and closing member of the knife-type gate valve is a gate. The direction of movement of the gate is perpendicular to the direction of the fluid. The gate or the electrohydraulic device is used to drive the gate through the valve stem to open and close the gate valve. The use of knife-type gate valve in coal washing plant and precautions 1. Characteristics of knife-type gate valve 1) The knife-type gate valve adopts the clip-on structure, compact structure, small size, light weight, small space, easy to install, and the operation of opening and closing the gate valve is labor-saving. , reducing the labor intensity of maintenance workers. 2) The bottom end of the gate of the knife-type gate valve is in the shape of a blade. It has a cutting function for materials, fibers and debris, and it is not easy to block the shutter, and has a good opening and closing function. 3) Reasonable sealing surface and packing sealing design make the valve sealing reliable. 4) The gate has multiple support points, which makes the gate have a good self-centering. 5) A hard Teflon scraper is installed on the upper end of the blade to prevent dust, sand and other abrasive substances from entering the stuffing box, which improves the life of the ram. 2. Usage and precautions 1) PZ73 type wafer type gate valve is mainly used in heavy medium and slime water pipelines in our factory. It is mainly used as cut-off in pipelines. It cannot be used as regulating flow. Open or fully closed to avoid sealing or erosion of the ram, accelerate wear and greatly reduce service life. 2) Pay attention to the installation direction of the valve during installation. The side with chamfered gate is the pressure side after the valve is closed. The direction of the arrow of the valve body is the flow direction of the medium after the valve is opened. 3) Lubricating oil should be regularly applied to each moving part during the use of the valve. 4) After the valve is used for a long time, the packing should be worn out. The packing should be replaced in time. The bolts of the packing gland should be evenly tightened and should not be pressed into a skewed state to avoid the movement of the valve stem or the leakage. Since the knife-type gate valve is used in the process pipeline of the coal washing plant, the effect is very good, the worker is easy to install and maintain, and the maintenance labor intensity is low. The use of the gate body is mainly caused by the serious wear of the gate body during the use process, and the gate is not tight, five or six months. A complete set of replacement gate valves is required. It is the hope of the majority of users to improve the valve body material or improve the structure of the overcurrent component inside the brake body to improve the service life of the gate valve in the worn medium pipe.

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