Chain Belt Type Grate

Product introduction

On the chain belt type grate the grate surface itself is the chain. The chain is driven by sprockets, so the grate moves slowly. The grate plates are usually made of cast iron. After assembly the necessary air gaps are kept between the grate plates, and a separate air chamber with adjustable air volume is usually provided under the grate, so that air enters the fuel bed through the gaps for combustion. Coal falls evenly onto the grate from the coal hopper at the front. The coal bed thickness is adjusted by raising and lowering the coal gate.

As the grate moves backwards, the coal starts to ignite, burns and burns out. The burnt ash is discharged manually or mechanically. In another arrangement a coal spreader throws the coal to the rear of the grate and the grate moves forwards, so that no coal hopper feed is needed. The grate speed is adjusted through the gear drive according to the coal type and boiler load.

Scope of application and requirements

Scope of application

The chain belt type grate is a mechanised layer-combustion device; it can be matched to boilers with an evaporation capacity of 1–25 t/h and can also be used for various heating and drying equipment. It is suitable for burning bituminous coal, lignite and peat. With a special design it can also serve as biomass fuel combustion equipment using bagasse, wood, rice husk and similar materials as raw material.

Operating requirements

The coal used in this grate should meet the following requirements:

The maximum coal particle size should not exceed 40mm, and coal fines below 0–5mm are not recommended.
The moisture content of the coal should be less than 20%, preferably 8–10%.
The ash content of the coal must not exceed 30% but must not be lower than 10%, and the volatile matter must not be lower than 20%.
The ash melting temperature should be above 1290℃.
The coking tendency should be low.
The net calorific value of the coal should not exceed 4226 kcal/kg.
If the coal quality requirements above conflict with the coal feed setting, the higher value applies.

The primary air temperature for this grate must not exceed 200℃.

Structure and characteristics

Components: 1. drive shaft; 2. driven shaft; 3. support frame; 4. ash removal device; 5. air control device; 6. grate chain; 7. coal hopper; 8. front air baffle; 9. side seal.

Simple structure, low metal consumption and a large ventilation cross-section ratio; however, the strength and performance requirements for the drive shaft, the driven shaft and the grate plates are higher.
Several mutually independent air chambers are arranged lengthwise inside the grate. The primary air entering a chamber slows down as it diffuses and can fill the chamber evenly. The air flow into each chamber can be adjusted with the air control device.
Each air chamber is fitted with an ash removal device. The bottom of the chamber is provided with an ash floor plate having an ash outlet, and a movable door connected to the ash pull rod normally covers the ash outlet. When the ash pull rod is operated periodically, the ash falls from the outlet onto the grate chain below, and the chain carries it to the front section or to an ash collecting hopper near the ash discharge door, where the ash is removed by hand.
The grate runs normally once it has been commissioned at the cooperating factory; it can be shipped as a complete unit, or shipped in parts as the user requires.

Model parameters

Boiler evaporation capacity	Grate effective area m²	Grate effective width mm	Shaft extension length (to grate centreline) mm	Output shaft end diameter mm	Number of air chambers
1 t/h	2.68	980	767	Φ60	4
2 t/h	3.84	1030	783	Φ60	4
4 t/h	5.39	1400	980	Φ60	5
6 t/h	7	1400	1015	Φ80	5
8 t/h	9.9	1960	1235	Φ80	6
10 t/h	11.65	2330	1662	Φ100	5
15 t/h	18.99	2890	1880	Φ100	6
20 t/h	22.6	3440	2205	Φ120	6

Operating features

Compared with other chain grates, lower metal consumption and a simpler structure, and easier to manufacture, install and operate;
The chain grate runs reliably, burns steadily and accepts a wide range of fuels, and is often used in industrial boilers.