What types of grates are there?

Fixed type
The grate plates are generally strip-shaped or plate-shaped, fixedly installed at the bottom of the furnace or combustion chamber by surrounding frames. On this grate, coal can only be added and ash can only be removed manually at regular intervals, resulting in high labor intensity and poor combustion economic efficiency, making it suitable only for small capacity furnaces such as industrial boilers with an evaporation capacity of less than 0.5 tons/hour.

Mobile type
There are two types: chain belt type and chain type. The grate surface of the chain belt type is the chain belt itself; while the grate plates of the chain type are fixed on the upper supports or brackets of the chain. Both chain belt and chain grates are driven by sprockets to move the chain, allowing the grate plates to advance slowly. Coal falls evenly from the coal hopper at the front end of the grate onto the grate. The thickness of the coal layer is adjusted by a coal gate that rises and falls. As the grate moves backward, the coal ignites, burns, and eventually burns out. There are also methods that do not use a coal hopper but instead use a coal throwing machine to throw coal onto the rear part of the grate while the grate moves forward. The speed of the grate is adjusted by a gear transmission according to the type of coal and boiler load. Chain grates operate reliably, have stable combustion, and a wide fuel adaptability, and are widely used in industrial boilers.

Reciprocating type
Consists of a set of fixed grate plates and a set of reciprocating movable grate plates, available in stepped and horizontal types. The reciprocating motion of the movable grate plates gradually pushes the coal layer toward the rear for combustion, thus this type of grate has a wider adaptability to coal types.

Vibrating type
There is a small angle between the grate surface and the horizontal plane, and the grate plates are vibrated periodically by the action of a motor and an eccentric wheel. During vibration, the fuel layer continuously moves toward the rear of the furnace, allowing the burnt ash to fall into the ash pit at the end of the grate. This type of grate is characterized by its simple structure.

Bottom feeding type
A trough-shaped structure grate, with a screw rod installed at the bottom of the trough, leading to the coal hopper outside the furnace. Coal is fed from the lower part of the coal hopper into the coal trough through the screw rod, moving from bottom to top, entering the high-temperature combustion zone. When the ash exceeds the angle of repose, it is discharged to both sides by gravity. This grate has a simple structure but has certain requirements for the particle size and moisture of the coal, generally suitable only for small industrial boilers with an evaporation capacity of less than 1 ton/hour.

Reciprocating type
It is a small mechanized grate developed on the basis of a fixed stepped grate. It features a simple structure, easy manufacturing, low metal consumption, and good smoke and dust removal effects. It is more commonly used in small industrial boilers and is a combustion device with development prospects.
The structural forms of reciprocating grates: inclined reciprocating grate, horizontal reciprocating grate, and strip reciprocating grate.