15t/h Flake Type Chain Grate

Product introduction

The grate surface of the flake type grate is usually made up of 4~12 parallel chains (similar to the chain structure of a bicycle). Each chain is formed by stringing together, with shovel shaped bolts, several short chain sections made up of large rings, small rings, washers, liner plates and other parts. The grate bars are assembled on the chains by means of clamping plates; the clamping plates are folded forwards and backwards, press close to one another and are arranged in a fish scale pattern. When the grate bars reach the tail end and turn into the lower return run, they turn over one after another by their own weight and hang upside down on the clamping plates, so that ash and slag are removed automatically and the bars are cooled.

Adjacent chains are connected by tie rods and sleeves so that the chain spacing remains unchanged.

Scope of application and requirements

Scope of application

This grate is a mechanized layer combustion device for boilers and is suitable for boilers with an evaporation capacity of 10~60 t/h. It can burn bituminous coal, lignite and peat. Coal is fed automatically from a coal hopper; it can also be equipped with a pneumatic coal feeder, or the grate can be installed upside down and equipped with a mechanical pneumatic spreader stoker to become the mechanized suspended combustion chamber type.

Service requirements

The coal burned on this grate must meet the following requirements:

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

(2) the moisture content on a dry basis must be less than 20%;

(3) the ash content on a dry basis must not exceed 30%, but must not be lower than 10%;

(4) the ash deformation temperature must be higher than 1250℃;

(5) the caking tendency 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 requirement shall be taken.

The primary air temperature used by this grate must not exceed 200℃ (when burning anthracite it must not exceed 160℃).

Structure and characteristics

The whole grate is divided into seven parts: (1) driving shaft, (2) driven shaft, (3) support (the support is of one piece construction, with a low ash carrying plate and friction strips), (4) furnace chain, (5) coal hopper, (6) front air damper, (7) slag stopper. This grate does not include the air supply device of the coal feeding equipment and the grate gearbox.

(1) The working face of the grate, that is the grate surface, consists of many grate bars stacked continuously at an inclination in a fish scale pattern, and the ventilation cross section is 8%-10%.

(2) The structural feature of the furnace chain is that there are many chains, and the chains are fixed on the furnace chain in groups of five clamping plate columns. The furnace chain is fixed by long shafts and liner plates threaded together, and rollers are threaded between the furnace chains. The rollers mesh with the teeth on the main wheel and drive the chain wheel of the transmission furnace to rotate. The grate is pushed along by the driving wheel, while the driven wheel runs as a slider.

(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 duct. Because of diffusion the air entering a chamber drops in velocity and can fill the whole chamber evenly. Butterfly doors are provided on the air ducts to regulate the air pressure in the air chambers.

(4) The ash discharge 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 furnace chain below. The furnace chain moves on the lower base 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 handles pass through the air ducts and are located on the outside of the air ducts; their arrangement is consistent with that of the air ducts, that is, with single side air supply the ash is discharged on one side, with two side air supply the ash is discharged on both sides, and single side air supply with two side ash discharge is also possible.

(5) The seal between the two sides of the furnace chain and the support uses a labyrinth or contact structure, and coal lumps are placed there to prevent coal from leaking into the two sides of the grate.

(6) The slag retaining device uses the eagle iron slag retaining device. The slag stopper, namely the eagle iron, is placed behind the driven shaft; its head presses on the furnace 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, repair 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 support. A coal gate is provided inside the coal hopper, and the thickness of the coal seam is adjusted by raising and lowering the coal gate.

Model parameters

Operating features

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

2. The grate gaps are extremely small and coal leakage is low; the grate bars are thin and the cooling conditions are good;

3. Replacement can be carried out without shutting down the boiler;

4. Because the chain structure is flexible, when the tooth profile of the chain wheel on the driving shaft deviates slightly, the tightness can adjust itself and good meshing is maintained.