Commonly Used Furnace Door Classifications for Boiler Grate Accessories

Commonly Used Furnace Door Classifications for Boiler Grate Accessories

I. Overall Classification Approach The standard furnace doors for biomass chain grates / reciprocating grates are mainly divided into: manhole doors, observation doors, ash cleaning doors, fuel charging doors, and explosion doors. The most frequently purchased by field engineers are observation doors, ash cleaning doors, and manhole doors. Common materials: HT200 cast iron, heat-resistant nodular cast iron; for high-temperature conditions, RTCr heat-resistant cast iron is selected.

1. Observation Door / Fire Door Function Observe furnace combustion conditions, material layer thickness, flame, and grate operation; the door is equipped with high-temperature resistant quartz glass sight glass.

Structure Two mainstream types: circular and square Circular observation door: commonly used for small biomass boilers Square observation door: standard for 6-ton and above medium-large chain grates and reciprocating grates ✅ Advantages: compact structure, flexible installation, good sealing; allows quick viewing of internal combustion ❌ Limitations: small opening, cannot accommodate personnel entry, cannot clean large slag blocks Installation position: both sides of furnace walls, front and rear arches, upper side walls of grate

2. Ash Cleaning Door / Clinker Door Function Clean slag, coke blocks, and ash that fall under the grate; most commonly used on both sides of reciprocating grates.

Characteristics Door panel size is relatively large, sealing flange is thickened; some models come with small ash cleaning shovels for use. ✅ Advantages: convenient for maintenance and slag cleaning, no need to open manholes for major shutdown ❌ Limitations: only suitable for cleaning scattered ash and small slag blocks Installation position: lower left and right sides of grate, side walls of air chambers

3. Manhole Door Function For personnel entry and exit during shutdown maintenance; replacing grate bars, inspecting chains, cleaning large-area coking.

Specifications Standard square large opening, hinge compression bolt sealing, with high-temperature resistant asbestos/ceramic fiber sealing gasket. ✅ Advantages: sufficient space, convenient for personnel to inspect the grate body ❌ Limitations: large volume, occupies furnace space; strictly prohibited to open during operation Applicable for: boilers ≥4T/h and above, front and rear ends of grate, side wall maintenance positions

4. Fuel Charging Door / Feed Door Function Manual fuel feeding, mostly seen in small manual-feeding biomass boilers; automatic feeding boilers generally no longer equipped. ✅ Advantages: emergency manual fuel supplement ❌ Limitations: basically eliminated in automatic boilers, opening easily causes flame ejection and smoke leakage Current market trend: large and medium chain/reciprocating furnaces rarely order separately

5. Explosion Door / Explosion Vent Function Biomass fuel has high volatile content; releases pressure when combustible gas in furnace explodes, protecting the furnace body. Two types: gravity explosion door, diaphragm explosion door. ⚠️ Important reminder: cannot replace regular inspection doors, only for safety protection use. Installation position: top of furnace, flue inlet.

6. Air Chamber Inspection Door / Small Air Adjustment Door Exclusive for grate air chambers! High-frequency accessory for grate accessories Used for air chamber maintenance, air leakage inspection, and auxiliary primary air adjustment; large quantities accompany chain grate and reciprocating grate air boxes. Small size, simple cast iron sealing door, with high demand from overseas customers.