Coal Mill Isolation Door

About this part

The coal mill isolation gate, also known as the coal mill slide gate (or coal mill shut-off gate), is installed on the cold primary air duct at the inlet of the coal mill. Its main function is to isolate the cold air entering the coal mill when the coal mill is shut down. The gate plate of the coal mill isolation gate should not be exposed to the outside, and the gate plate adopts a fully sealed structure. The internal and external leakage rates of the coal mill isolation gate are zero. This product is reliable in operation, flexible in opening and closing, and tightly sealed, solving the common problems of poor sealing and unstable operation of traditional coal mill isolation gates. This simplifies equipment switching and shutdown maintenance, and is currently widely used in power plants, steel mills, and other industries worldwide.

Technical Characteristics of Coal Mill Isolation Gate

• It can be installed and used in horizontal, vertical, inclined, and vertical positions depending on your site conditions.
• The opening and closing of the coal mill isolation gate are interlocked, facilitating centralized control by the DCS system. For ease of maintenance and special needs, it can also be operated manually on-site.
• The entire equipment is heat-treated, ensuring no deformation under large temperature differences. It adopts a novel sealing structure and sealing materials, resulting in good sealing performance and high wear resistance.
• The operating mechanism is safe and fast, reliably completing all actions. This reduces dust accumulation on the guide rails during the use of the coal mill isolation gate, lowering the failure rate and reducing maintenance costs and the labor intensity of maintenance personnel.
• The coal mill isolation gate can be controlled by electric, pneumatic, or manual means.
• The limit switch of the coal mill isolation gate uses a mechanical collision limit switch.

Structure and Performance of the Coal Mill Isolation Gate

The coal mill isolation gate mainly consists of a door frame, door seat, door panel, locking device, sealing system, opening and closing mechanism, and pulse soot blowing system. Both the door seat and door panel adopt a cavity structure, and are precision machined after overall heat treatment to ensure no thermal deformation. A special sealing device ensures no internal leakage at the front and back of the door panel and no external leakage at the shaft journal, thus achieving true zero leakage.

Actuator

The opening and closing drive mechanism of the coal mill isolation gate's slide plate is designed as an integrated unit. The coal mill isolation gate is supplied with a local control box. The coal mill isolation gate can be operated locally on-site or remotely controlled.

Corrosion Protection

Depending on the site conditions and requirements, the parts of the coal mill isolation gate that come into contact with flue gas can be lined with anti-corrosion materials to ensure that the gate is not corroded by flue gas and to guarantee its lifespan; suitable anti-corrosion materials include 304, 316L, and 2205 stainless steel.

Shovel-shaped Double-layer Structure Door Panel

The slide plate of the coal mill isolation gate is assembled from a central support and panels, followed by overall annealing treatment to completely overcome the stress of thermal deformation. The sealing surfaces of the slide plate and the door seat are then machined. This ensures a high degree of flatness on the slide plate surface, guaranteeing tight closure and no leakage.

Technical Parameters of the Coal Mill Isolation Gate

• Model: MMCB-A(length)*B(width)*H(height) Note: A*B can be rectangular, circular, or other specifications of air ducts, determined by your site conditions. H, the thickness of the coal mill isolation gate, is generally 500-800mm.
• Medium: Cold and hot air, flue gas
• Design Temperature: ≤150 degrees Celsius
• Design Pressure: ≥25kpa
• Compressed air supply pressure ≥ 0.45 MPa
• Voltage: AC 380V/50Hz
• The cold air shut-off valve should remain undeformed under working conditions, operate smoothly, and have good sealing performance without jamming. The time for the isolation valve to fully open or close should be ≤ 15S.

Installation Instructions for Coal Mill Isolation Valve

• The flue and air ducts should be welded to the inlet and outlet flanges; direct welding to the valve body is not recommended;
• If the medium contains dust, compressed air with a pressure of at least 1 bar should be connected to the reserved connector on the valve body;
• The support and suspension method of the coal mill isolation valve body shall be determined by the manufacturer;
• The coal mill isolation valve body has been adjusted at the factory. Do not disassemble it yourself.

Note: If the coal mill isolation valve is equipped with a locking actuator, when closing, the valve must be fully closed before locking; when opening, the locking actuator must be released first before starting the opening/closing actuator.

Scope of Supply

• Coal mill isolation valve body

(2) Actuator

• Counter flanges and fasteners for the interfaces on both sides of the coal mill isolation valve body

Quality documentation included

• Dimensional inspection report (CMM / profile projector) for critical features
• Material certificate with heat number traceability
• Surface finish and hardness records where specified
• Photographic packing record before shipment