45t/h Cross-beam Type Grate

Product introduction

The cross-beam grate is a new type of cross-beam grate plate featuring inclined air outlets. Unlike existing grate plates, which discharge air vertically upwards, the ventilation holes of the inclined-outlet cross-beam grate plate direct the air at a certain angle to the vertical. When the air leaves the grate plate it has a horizontal velocity, which helps the air spread horizontally in the coal bed, strengthens the mixing of coal and air, and reduces coal leakage through the grate.

Application scope and requirements

Application scope

The cross-beam grate is a mechanized grate-firing unit with a compact structure. It is suitable for boilers with an evaporation capacity of 20~40 t/h and above. Its main structural difference from the chain grate is that it uses many rigid cross beams. The grate plates are installed in the corresponding grooves of the cross beams, and the cross beams are fixed to the drive chains. There are generally two drive chains (several can be installed when the grate is very wide), driven by the sprockets mounted on the front shaft (drive shaft).

It is widely used in various large boilers and in special equipment such as heating and drying equipment. It is suitable for burning bituminous coal, lignite and peat; specially designed incineration equipment can also burn other fuels such as bagasse and various types of waste.

Operating requirements

The medium used in this grate must meet the following requirements:

(1) The maximum particle size of the coal must not exceed 40 mm, the content of 05 mm coal fines must not exceed 50%, and the content of 030 mm coal fines must be less than 25%.

(2) The moisture content of the coal is less than 20%, with 8~12% being the best.

(3) The ash content of the coal must be less than 30% but not less than 10%, and the volatile matter content must not be less than 20%.

(4) The ash fusion temperature of the coal must be higher than 1250℃.

(5) The caking property should not be too strong.

(6) The net calorific value of the coal must be higher than 4350 kcal/kg.

(7) If the above medium requirements conflict with the medium requirements of the coal feeding equipment, the higher requirement shall be adopted.

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

Structure and characteristics

The whole grate consists of the following components: (1) support frame; (2) grate chain; (3) ash discharge device; (4) side seals; (5) air inlet pipes; (6) rear guide blocks; (7) front air baffle device; (8) shaft assemblies; (9) coal hopper assemblies.

(1) The support frame consists of left and right side wall plates and front, middle and rear cross beams. Between the cross beams, the ash discharge device and the air chamber partitions, several relatively closed large-capacity air chambers are formed; in this way the air supply to each area of the grate surface can be adjusted, so that the fuel burns fully.

(2) The chain consists of chain links passing through rollers, intermediate guide blocks, chain shafts, retaining rings, pin shafts, etc. Bolt slots are cast in the chain links, and the cross beams are fixed with bolts.

(3) One end of the grate is driven by the drive shaft and needs no driven shaft, and a guide device is installed at the other end; the transition of the chain between the upper guide rail and the lower guide rail is completed by the drive shaft and the guide device. The torque of the drive shaft is provided by the grate reducer through a coupling.

(4) The side seals are horizontal right-angle flow-passage side seals; together with the side seals of the grate plates, the two sealing lines improve the safety and reliability of operation.

(5) The ash discharge device is of the push-pull type; pulling the ash discharge door handle opens the ash discharge door, and the fine ash and coal fines collected in the air chamber can then be discharged.

(6) The layer-spreading coal feeding device is widely used in the coal hopper assembly; the coal entering the furnace is loose and layered and burns fully, which improves the thermal efficiency of the boiler.

(7) The grate has a compact structure and a reasonable layout; the grate chain moves inside sealed guide rails, is not exposed to high temperature and only bears the tension of grate movement; the grate plates made of heat-resistant material contact the high-temperature burning coal bed on the cross beams and bear no stress when heated, which extends the service life of the grate.

(8) The grate has no rear shaft and no eagle irons, which reduces the failure rate of the rear part of the grate during operation and improves operating efficiency.

(9) The grate chain runs under tension without arching or climbing; chain movement is rolling friction, so the required running torque is low and the noise is low.

(10) The grate is well sealed as a whole; air leakage and air cross-flow between air chambers can be prevented. The air supply to each air chamber can be adjusted separately, which is convenient and practical.

(11) The grate surface is flat, and the grate plates overlap each other and are closely arranged, which prevents coal leakage and coal dropping; grate plates can be replaced conveniently without shutting down the boiler.

Model parameters

Operating features

1. Good structural rigidity: the grate plates are not heated, and the cross beams and chains are not heated either, so the grate is safer and more durable;

2. Large effective grate area, low resistance and even air distribution;

3. Chain movement is rolling friction, so the required running torque is low and the friction noise is low;

4. The grate is well sealed as a whole, air leakage and air cross-flow between air chambers can be prevented, and the air supply to each air chamber can be adjusted separately, which is convenient and practical;

5. The grate surface is flat, the grate blocks overlap each other and are closely arranged, so coal leakage and coal dropping are unlikely, and grate plates can be replaced conveniently without shutting down the boiler;

6. The ventilation section area of the grate is large, generally up to 10%-17%, and combustion is extremely complete;

7. The grate has no rear shaft and no eagle irons, so the rear part of the grate is unlikely to fail inside the furnace.