35t/h Cross-beam Type Grate

Product introduction

The cross-beam-type grate is a new type of cross-beam grate plate on which an oblique air outlet is applied. This kind of grate plate differs from existing grate plates, whose air outlets point vertically upwards: the air outlet direction of the ventilation holes of the oblique-outlet cross-beam grate plate forms a certain angle with the vertical direction. When the grate air leaves the grate plate it has a horizontal velocity, which helps the air to diffuse horizontally in the coal bed, strengthens the mixing of coal and air, and reduces the phenomenon of coal leaking through the grate.

Scope of application and requirements

Scope of application

The cross-beam grate is a mechanized layer-firing unit with a compact structure. The cross-beam grate is suitable for boilers with an evaporation capacity of 20~40t/h and above. Its main structural difference from the chain-belt grate is that many rigid crossbeams are used. 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 can be installed when the grate is very wide), driven by the sprockets mounted on the front shaft (driving 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 by this grate must meet the following requirements:

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

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

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

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

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

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

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

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

Structure and characteristics

The complete grate consists of the following components: (1) support frame; (2) grate chain; (3) ash discharge device; (4) side seal; (5) air inlet pipe; (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 wall plates and front, middle and rear crossbeams. Between the crossbeams, 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 zone of the grate surface can be adjusted and the fuel can be fully burned.

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

(3) One end of the grate is driven by the driving shaft and requires no 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 carried out by the driving shaft and the guide device. The driving shaft torque is provided by the grate reducer through the coupling.

(4) The side seal is a horizontal right-angle flow channel side seal; together with the grate plate side seal it provides two sealing lines, which improve the safety and reliability of operation.

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

(6) The stratified coal feeding device is widely used in the coal hopper assembly; the coal entering the furnace is loose and stratified 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 moving tension of the grate; the grate made of heat-resistant material contacts the high-temperature burning coal bed 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 lowers 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 and without chain climbing; the chain movement is rolling friction, so the running torque requirement is low and the noise is low.

(10) The grate has good overall sealing; air leakage and cross-flow between air chambers can be prevented. 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 can prevent coal leakage and coal dropping; the grate plates can be replaced conveniently without stopping the boiler.

Model parameters

Boiler evaporation capacity	Grate effective area m²	Grate effective length mm	Grate effective width mm	Driving shaft torque N·m	Air supply mode	Ventilation section ratio %	Ventilation resistance pa
20 t/h	23.29	6830	3410	20000	Double-side air supply	8.5	1000
40 t/h	35.38	7800	4550	30000	Double-side air supply	8.5	1000
65 t/h	57.6	8150	6960	50000	Double-side air supply	8.5	1000
75 t/h	63.7	7503	8490	70000	Double-side air supply	8.5	1000
80 t/h	71.2	8360	8518	60000	Double-side air supply	8.5	1000
90 t/h	80	9373	8540	70000	Double-side air supply	8.5	1000
100 t/h	97.71	9165	9570	90000	Double-side air supply	8.5	1000
130 t/h	126.66	9590	13210	Dual reducers	Isobaric air box	8.5	1000
160 t/h	153.17	10458	14700	Dual reducers	Isobaric air box	8.5	1000
200 t/h	185.94	10458	17780	Dual reducers	Isobaric air box	8.5	1000
260 t/h	248.4	13500	18400	Dual reducers	Isobaric air box	8.5	1000
300 t/h	295.2	14260	20700	Dual reducers	Isobaric air box	8.5	1000

Operating features

1. The structure has good rigidity, the grate plates are not heated, and the crossbeams and chains are not heated either, so it is safer and more durable;

2. The grate has a large effective area, low resistance and even air distribution;

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

4. The grate has good overall sealing, which can prevent air leakage and cross-flow between air chambers; the air supply of each air chamber can be adjusted separately, which is convenient and practical;

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

6. The ventilation cross-sectional area 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.