Chain Grate vs Cross-beam Grate: Working Principles and Features

In industrial boilers, the chain grate and the cross-beam grate are two common grate types. They play a key role in fuel combustion and each has its own working principle and features.

Chain Grate

The chain grate works like a precision conveyor belt. It consists of a drive sprocket, an idle sprocket and a chain running between them. Many grate bars are mounted on the chain, and fuel is evenly spread on the grate bars from the front end. As the chain turns slowly, fuel is gradually carried into the furnace. Inside the furnace, the air chamber below the grate supplies air, which flows up through the gaps between the grate bars to contact the fuel and start combustion. During combustion, the fuel moves backward with the grate while going through drying, volatile release and coke combustion stages.

The chain grate has clear advantages: a relatively simple structure, stable and reliable operation, continuous fuel supply for a smooth combustion process, and strong fuel adaptability. Both lump coal and granular biomass fuel burn well on it. However, it also has limitations. Because of the grate bars’ movement, fuel may be unevenly distributed, causing incomplete local combustion and reducing boiler efficiency. Also, after long operation, the grate bars wear out and need regular maintenance and replacement.