Difference between split adjustable shrinkage holes and balanced adjustable shrinkage holes

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The difference between the double-core adjustable throat and the single-core adjustable throat: The adjustable throat is used in the horizontal powder delivery pipeline at the outlet of the coal grinder, to control the flow rate of coal powder exiting the grinder. Developed using advanced foreign technology, it features a completely circular pipe at its bottom, which prevents the accumulation of coal powder there – a problem that could prevent adjustment of the core plate or even cause coal powder explosions. The rotation torque applied to the handwheel is transmitted through a drive rod to move the valve plate up and down, thereby adjusting the cross-sectional area of the pipeline. It is a valve designed to regulate the flow rate of the air-powder mixture in the powder delivery pipeline; the rotation torque from the handwheel is transmitted through a screw sleeve to move the drive rod connected to the valve gate upward, thus adjusting the pipeline’s cross-sectional area.

I. Structure: The main components include a welded shell, a symmetrical dual-core valve gate, and a transmission mechanism. The valve gate is made of wear-resistant cast material and is installed within a shell perpendicular to the centerline of the pipeline. The transmission mechanism uses the handwheel to drive a screw rod and a crank-like arm, which in turn drive the valve gate to adjust its cross-sectional area through a sealed shaft. There are two core plates on either side, moving back and forth around the centerline of the pipeline, thereby adjusting the opening area. The coal powder flows always along the centerline of the pipeline, eliminating the problem of eccentric flow associated with single-core adjustable throats. This reduces flow losses and wear on the pipe walls, thus extending the service life of the powder delivery pipeline.

II. Working principle of the dual-core adjustable throat: The dual-core adjustable throat is an improved version of the traditional single-core adjustable throat, designed to regulate the flow rate of the air-powder mixture in the powder delivery pipeline. It utilizes the rotation torque from the handwheel, which is converted into upward and downward forces through the drive rod, causing the upper and lower valve plates to move in opposite directions. This action helps to adjust the cross-sectional area of the pipeline. III. Performance characteristics of the dual-core adjustable shrinkage hole: 1. The dual-core plate and the wear-resistant channel cylinder are made of rare-earth wear-resistant steel, offering excellent wear resistance, good sealing properties, smooth operation, good adjustability, precise manufacturing, and an attractive appearance. 2. The air-powder mixture flow within the pipeline remains at the center of the pipe. Since the dual-core plate with adjustable constricting holes moves back and forth from the center of the pipe, this eliminates the problem of eccentric flow, reduces flow resistance and wear on the pipe walls, thereby extending the service life of the powder transfer pipeline. 3. The double-core adjustable neck design features a sealing mechanism, which prevents coal powder from entering the neck area; as a result, it maintains flexible operation at all times and has a long service life. 4. Compact structure with minimal installation space required. 5. Low operating torque, flexible switching, with no sticking. For double-core adjustable shrinkage holes with an inner diameter of DN300–DN600, the relevant materials and manufacturing processes can be customized to suit the requirements of the specific installation site. III. Main parameters: The balanced dual-core adjustable choke is primarily used to regulate the resistance of the primary air duct; the range of adjustment for the flow area is from 25% to 100% of the cross-sectional area. Depending on the specifications of the inlet and outlet connections, there are 8 different types of balanced adjustable chokes available. The split-type dual-core adjustable choke is used to regulate the resistance of the primary air ducts in the powder feeding pipes, ensuring that the primary air velocity at the burner inlet remains consistent for each powder feeding pipe. Main technical parameters: The adjustment range is 30%-100% of the pipe cross-sectional area. Operating temperature: ≤350°C. Connection methods: Direct welding and flange type. 2. Split-type dual-core adjustable reducing tee – The following parameters should be provided at the time of ordering: Maximum operating pressure: pa; Maximum operating temperature: °C. Main technical parameters for the balanced-type dual-core adjustable reducing tee: Nominal diameter: DN300–DN600; Minimum flow area: 25% of the cross-sectional area; Flow area: 100% of the cross-sectional area. IV. Design features: It features a design with an adjustable shrinkage hole; the housing uses a fixed seal, while the shaft end employs a packing bearing seal structure, ensuring that there is no leakage from the adjustable shrinkage hole and preventing dust accumulation. 1. An adjustable orifice plate is used; the dual-core plate moves back and forth from the center of the pipe to adjust the opening area. The coal powder inside the pipeline always flows at the center of it, which eliminates the problem of eccentric flow of coal powder in second-generation adjustable converging nozzles, reduces flow losses, prevents excessive wear on the pipe walls, and thus extends the service life of the coal powder delivery pipeline. 2. It is equipped with a sealing mechanism, which prevents coal powder from entering the interior of the orifice; as a result, it can always remain flexible in operation and has a long service life. 3. It is equipped with a dial and pointer for adjusting the opening degree; the dial shows the percentage of cross-sectional area adjustment as well as the travel distance, enabling very convenient and intuitive adjustment. 4. The double-core plate and the wear-resistant channels are made of rare-earth wear-resistant steel, offering excellent wear resistance, good sealing properties, smooth starting performance, good adjustability, an attractive appearance, and fine manufacturing quality. Cylinder material: A3. Core plate material: ZG40CrMoNiMnSiREV. Plate welding → grinding → ultrasonic testing → assembly → debugging → overall pressure testing → painting