20t/h Cross-beam Type Grate

Product introduction

The cross-beam type grate is a new type of crossbeam grate plate in which oblique air outlets are applied to the crossbeam grate plate. This grate plate is different from existing grate plates, whose air outlet direction is vertically upward: for the oblique-air-outlet crossbeam grate plate, the air outlet direction of the ventilation holes forms a certain angle with the vertical direction. When the grate air leaves the grate plate it has a horizontal velocity, which is conducive to the horizontal diffusion of the air in the coal seam, enhances the mixing effect of coal and air, and reduces the phenomenon of coal leaking from the grate.

Applicable scope and requirements

Scope of application

The cross-beam type grate is a mechanized layer-combustion unit with a compact structure. The crossbeam grate is suitable for boilers with an evaporation capacity of 20~40 t/h and above. Its main structural difference from the chain-belt grate is the use of many rigid crossbeams. The grate plates are installed in the corresponding grooves of the crossbeams, and the crossbeams are fixed on the drive chains. There are generally two drive chains (several may 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 for heating, drying and similar duties. 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.

Use requirements

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

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

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

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

(4) The ash melting point temperature of the coal shall be higher than 1250℃.

(5) The coking tendency should not be too strong.

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

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

The primary air temperature used in this grate shall not exceed 200℃.

Structure and characteristics

The complete grate consists of the following components: (1) support frame; (2) grate chain; (3) ash removal device; (4) side seal; (5) air inlet duct; (6) rear guide block; (7) front air baffle device; (8) shaft assembly; (9) coal hopper assembly.

(1) The support frame consists of left and right side wall plates and front, middle and rear crossbeams. Between the crossbeams, the ash removal device and the air chamber partitions, several relatively closed large-capacity air chambers are formed; in this way the air supply to each zone of the grate surface can be adjusted and full combustion of the fuel can be achieved.

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

(3) One end of the grate is driven by the drive shaft without need of a driven shaft, and the other end is fitted with a guide device; the transition of the chain between the upper guide rail and the lower guide rail is accomplished 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 seal is a horizontal right-angle flow-passage type side seal; together with the side seal of the grate plates, the two sealing lines improve the safety and reliability of operation.

(5) The ash removal device is of the push-pull type; by pushing or pulling the ash door handle to open the ash door, the fine ash and coal fines collected in the air chamber can be discharged.

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

(7) The grate has a compact structure and a rational 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 made of heat-resistant material contacts the high-temperature burning coal seam on the crossbeams and bears no stress when heated, thus extending the service life of the grate.

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

(9) The grate chain runs in a tensioned state, without arching or chain climbing; chain movement is rolling friction, so the running torque requirement is low and the noise is low.

(10) The grate has good overall sealing; it prevents air leakage and air cross-flow between air chambers. The air supply of 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; the grate plates can be replaced conveniently without stopping the boiler.

Model parameters

Operating features

1. Good structural rigidity; the grate plates are not exposed to heat, nor are the crossbeams and the chains, so the grate is safer and more durable;

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

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

4. Good overall sealing of the grate prevents air leakage and air cross-flow between air chambers, and the air supply of 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 is not easily lost or dropped, and the grate plates can be replaced conveniently without stopping the boiler;

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

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