Coal stokers can be classified on basis of coal burning capacities
According ASHRAE coal stokers for automatic feeding fuel to a furnace can be classified after their coal burning capacities:
- Class 1 Stokers - 10 to 100 lbs (4.5 to 45 kg) coal per hour
- Class 2 Stokers - 100 to 300 lbs (4.5 to 135 kg) per hour
- Class 3 Stokers - 300 to 1200 lbs (135 to 540 kg) per hour
- Class 4 Stokers - more than 1200 lbs (more than 540 kg) per hour
Bituminous coal with an ash fusion temperature of 2200 oF to 2600 oF is ideal for stoker operations.
Depending on the construction of the stoker the size of the coal should be between 1 1/4-inch to 3/4-inch.
Oil treatment of the coal is quite common to reduce the dust problem. Oil treatment of the coal also adds lifetime to mechanical conveyors, feed screws etc.