20t/h Reciprocating Grate
We supply the 20t/h reciprocating grate in a stepped arrangement, with fixed and moving grate bars placed alternately; the moving grate travels back and forth so that the coal bed descends evenly. The equipment is supplied from our partner factory to project parameters and can serve boilers from 1-200t/h, with a wide range of acceptable fuels.
Structure and working principle
A reciprocating grate consists of the coal hopper, frame, moving beams, fixed beams, moving and fixed grate bars, front air baffle and drive system. The moving grate stroke is normally 70-110mm, with a longer stroke selected for poorer coal; depending on the design the stroke can also reach 70-180mm.
As the moving grate advances, the coal bed is compressed, rolled and stirred, and part of the fresh coal is pushed onto the burning hot bed below; on the return stroke, some hot coal particles are carried back under the unburned bed, giving the fuel layer ignition from both sides. Because the coal bed moves relative to the grate, the bed is loosened and its permeability improves; friction between coal particles also breaks the ash shell around hot particles, which helps coke burn and crushes weakly caking coke lumps.
Fuel and operating requirements
The grate imposes the following quality requirements on the coal fed to the furnace.
| Item | Requirement |
|---|---|
| Maximum coal lump size | Not more than 40mm |
| Share of 0-6mm fines | Not less than 50% |
| Content of 0-3mm coal | Less than 25% |
| Moisture content | Less than 15%, with 5-10% preferred |
| Combustion ash | Not less than 10% |
| Ash melting point | Preferably above 1200℃ |
When the coal falls outside these ranges, the grate stroke and air distribution need adjustment; coal data can be provided at the selection stage for us to check.
Model parameters
The table below gives the effective grate area, effective width, air-flow section ratio and drive shaft torque for common boiler evaporations; the inclination is customised to user requirement.
| Boiler evaporation | Effective grate area (m²) | Effective grate width (mm) | Air-flow section ratio | Drive shaft torque (N.m) | Inclination |
|---|---|---|---|---|---|
| 4 t/h | 5.56 | 1600 | 6-8% | 2000 | Customised to user requirement |
| 6 t/h | 6.08 | 1600 | 6-8% | 3000 | Customised to user requirement |
| 8 t/h | 8.5 | 2100 | 6-8% | 4000 | Customised to user requirement |
| 10 t/h | 12.99 | 2020 | 6-8% | 5000 | Customised to user requirement |
| 15 t/h | 22.04 | 3300 | 6-8% | 7500 | Customised to user requirement |
| 30 t/h | 29.65 | 3730 | 6-8% | 30000 | Customised to user requirement |
| 40 t/h | 40 | 4630 | 6-8% | 40000 | Customised to user requirement |
| 65 t/h | 60.16 | 7020 | 6-8% | 60000 | Customised to user requirement |
| 100 t/h | 99.56 | 10480 | 6-8% | 75000 | Customised to user requirement |
| 130 t/h | 100 | 11580 | 6-8% | 100000 | Customised to user requirement |
| 160 t/h | 153 | 14700 | 6-8% | 125000 | Customised to user requirement |
| 200 t/h | 185 | 17780 | 6-8% | 150000 | Customised to user requirement |
| 260 t/h | 248 | 18400 | 6-8% | 185000 | Customised to user requirement |
| 300 t/h | 295 | 20700 | 6-8% | 210000 | Customised to user requirement |
The grate uses zoned air supply, with several independent air chambers along its length fed from wind boxes or ducts on both sides, and the air volume of each chamber is set by an adjusting device. Coal bed thickness is regulated by raising or lowering the coal gate, and the grate can be delivered as a complete unit or as separate parts.
Operating characteristics
The inclined reciprocating grate has a relatively simple structure, low metal consumption and convenient maintenance, and compared with a chain grate it tolerates a wider range of coals such as class II bituminous coal, class I bituminous coal, lignite and lean coal. It is suitable for high-moisture, high-ash, low-calorific-value (12560kJ/kg) and easily coking poor coal; with reasonable air supply and low air leakage, the carbon content in the ash is generally 18%-20%, 5%-10% lower than the slag from a hand-fired furnace, which reduces black smoke.