35t/h Flake Type Chain Grate

Product introduction

The grate surface of a flake-type chain grate is usually made up of 4~12 parallel chains (similar to the chain structure of a bicycle). Each chain uses shovel-shaped bolts to join several short chain sections made up of large links, small links, washers, liners and other parts. The grate plates are assembled on the chains by means of splints; the splints are folded forwards and backwards, pressed close against each other and arranged in a fish-scale pattern. When the grate plates reach the rear and turn into the lower idle run, the plates tip over one after another under their own weight and hang upside down on the splints, so that the ash is removed automatically and the plates are cooled.

Adjacent chains are connected by tie rods and sleeves, which keep the chain spacing unchanged.

Scope of application and requirements

Scope of application

This grate is a mechanised layer-combustion device for boilers and is suitable for boilers with an evaporation capacity of 10~60t/h. This grate can burn bituminous coal, lignite and peat. This grate uses a coal hopper to drop the coal automatically. A pneumatic coal feeder can also be fitted, or the grate can be installed upside down and fitted with a mechanical pneumatic spreader stoker, so that it becomes a mechanised suspension-combustion chamber type.

Use requirements

The coal burnt by this grate shall meet the following requirements:

(1) The maximum particle size of the coal shall not exceed 40mm; the content of 0~3mm coal fines shall be less than 30%;

(2) The moisture content on a dry basis shall be less than 20%;

(3) The ash content on a dry basis shall not exceed 30% but shall not be lower than 10%;

(4) The ash deformation temperature shall be higher than 1250℃;

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

(6) If the above coal quality requirements conflict with the coal quality requirements of the coal feeding equipment, the higher of the two shall be adopted.

The primary air temperature used by this grate shall not exceed 200℃ (not more than 160℃ when burning anthracite).

Structure and characteristics

The whole grate is divided into seven parts: (1) driving shaft; (2) driven shaft; (3) supports (of one-piece structure, with low ash support plates and friction strips); (4) grate chain; (5) coal hopper; (6) front air damper; (7) slag stopper. The air supply device of the coal feeding equipment and the grate gearbox are not included in this grate.

(1) The working surface of the grate, that is, the grate surface part, is formed by many grate plates stacked continuously at an incline in a scale pattern; the air passage section is 8%-10%.

(2) The grate chain is characterised by a large number of chains, and the chains are fixed on the grate chain in groups of five splint columns. The grate chain is joined and fixed by long shafts and liners, and rollers are threaded between the grate chains. The rollers mesh with the teeth on the main wheel and drive the chain wheel of the driving furnace to rotate. The grate is driven by the driving wheel, and the driven wheel runs as a sliding one.

(3) Sectional air supply is used inside the grate. Along the length of the grate it is divided into several large-capacity air chambers, and each air chamber is connected separately to an air supply duct. The air entering an air chamber slows down owing to diffusion and can fill the whole chamber evenly. A butterfly damper is provided on the air supply duct to regulate the air pressure in the air chamber.

(4) The ash removal device of the air chambers uses push-pull and tie-rod type ash drop doors. When the handle of an ash drop door is turned or pushed, the ash falls onto the grate chain below. The grate chain moves on the lower bottom plate and pushes the ash to the front end of the grate, where it falls into the ash hopper or the slag trough.

The ash can also be removed manually. The push-pull handle passes through the air supply duct and is located outside the duct; its arrangement is consistent with that of the air supply duct, that is, single-side air supply means single-side ash discharge, double-side air supply means double-side ash discharge, and single-side air supply with double-side ash discharge is also possible.

(5) The seal between both sides of the grate chain and the supports adopts a labyrinth or contact structure, and coal blocks are placed there to prevent coal from leaking into the two sides of the grate.

(6) The slag retaining device adopts an eagle-iron slag retaining device. The slag stopper, namely the eagle iron, is placed behind the driven shaft. The head of the slag stopper is pressed onto the grate chain by its own weight, and its lower part is mounted on the support and welded to the grate support.

(7) To meet the needs of routine inspection, maintenance and ventilation, an inspection door is provided on the slope above the front air damper. If natural ventilation is required, the damper and the ash drop doors of the air chambers can be opened.

(8) The coal hopper is mounted on the wall plates on both sides of the supports. A coal gate is provided inside the coal hopper, and the thickness of the coal layer is adjusted by raising and lowering the coal gate.

Model parameters

Operating features

1. The coal layer is in contact with the whole grate surface, but the chains are not heated directly, so operation is safe and reliable;

2. The grate clearance is extremely small and little coal leaks; the grate plates are thin and the cooling conditions are good;

3. The plates can be replaced without stopping the boiler;

4. Because the chain structure is flexible, when the tooth profile of the sprocket on the driving shaft deviates slightly, the tension adjusts itself and good meshing is maintained.