The grate cooler is important equipment in the clinker production of the cement manufacturing plant, the main function of the grate cooler is cooling and conveying cement clinker. Besides, the grate cooler also provides hot air for the rotary kiln and precalciner, which is considered as a vital part of heat recovery in the firing system. With the development of the cement manufacturing process and cement equipment, also include the cement clinker cooler technology, high-efficiency, and reliable clinker cooler become the key to make sure the productivity of the cement production line.
The grate cooler has four generations since it was created. The first generation is grate cooler with a thin layer, it has lower capacity; the second generation is grate cooler with a thick layer, there is a relative increase in its production, promote the cooling efficiency of grate cooler; the third generation is Air beam grate cooler, the cooling efficiency improve a lot compared the last generation; the fourth generation is commonly applied modern cement manufacturing plant, the layer becomes thickened, and it has high working efficiency and low maintenance cost.
Function of grate cooler
In most cement manufacturing plants, the grate cooler is very common like rotary kiln and cement mill. It is usually applied to various sections of the cement production line and plays different roles in the cement plant.
- As the processing equipment, the grate cooler takes on the task of cooling high-temperature clinker. Quench cooling can prevent the growth of the Clinker mineral crystal, especially for C3S crystal, which improves the strength and grindability. At the same time, quenching cooling makes the liquid phase into the vitreous body, to be good for the stability of the clinker, and improve the resistance to chemical corrosion.
- As the thermal equipment, except for cooling clinker, grate cooler also takes work on heating secondary air and tertiary air, try to increase the temperature of secondary and tertiary air into the kiln. The grate cooler not only recovery heat, but also has a good influence on helping to combust, and thermal distribution of the whole cement rotary kiln system.
- As the heat recovery equipment, the grate cooler takes the recycling task of a large amount of heat content of discharged clinker. The recycled heat will enter the kiln and furnace along with secondary air and tertiary air, which benefits for reducing the heat consumption of calcining.
- As the conveying equipment for clinker, the grate cooler can be used to convey high-temperature clinker. The cooling for high-temperature clinker is good for clinker conveying and storage.
In general, the grate cooler is made up of the upper case, lower case, grate bed, grate bed transmission, supporting device for grate bed, clinker crusher, funnel, drag chain conveyor, automatic lubricator, cooling air unit, and other parts. The grate plate is a wearing part in the grate cooler. After a long-term operation, the grate cooler will be damaged, deformed, wore, even cracked, etc. these wearing will affect the normal operation of the grate cooler.
As a grate cooler manufacturer who has decent years’ experience, AGICO CEMENT surmised several effective measures to extend service life of grate plates.
Select the material of grate plate correctly
Before entering the grate cooler, the clinker temperature is generally 1400℃. In the process of heat exchange, the grate plate is required to have certain heat resistance, thermal stability at high temperature, and adequate wear resistance.
High-temperature oxidation corrosion of the grate plate is more serious in the feeding end and the following high-temperature heat recovery area. Therefore, the grate plate should be made of Cr-Ni austenitic heat resistant steel with good oxidation resistance, high heat-resistance temperature, and wear resistance. In the middle-temperature cooling zone, the clinker has been significantly cooled, heat resistant steel such as ZG35Cr24Ni7SiN or ZG30Cr26Ni5 can be used. In the low-temperature cooling zone, the clinking temperature has been reduced to a low level. The grate plate material mainly considers its abrasion resistance and also requires certain anti-oxidation ability, such as ZG35Cr24Ni7SiN or ZG30Cr26Ni5 heat resistant steel.
Improve grate plate design
It is necessary to fully consider the influence of the whole structure on the service life of the grate plate when designing a grate plate. The leakage-proof material between the grate plates should be fully considered in the design to ensure the clearance of the grate plates. The designer should carry out a variety of tests on the improved grate plate and constantly improve its performance.
In terms of process operation, we should especially pay attention to the operation of the thick material layer to reduce air leakage in the air chamber and indoor air movement to avoid affecting cooling. The thick material layer protects the grate bed and grate plate and reduces the influence of incoming material fluctuation on the stability of the grate cooler operation.
Maintenance of the grate plate is very important. When entering the downwind chamber of the grate cooler, all grate plates and connection bolts of grate plates shall be timely checked, replacing cracked and worn grate plates. During installation and maintenance, the horizontal and vertical clearance between grate plates should be adjusted well.
In conclusion, the grate plate is a key component of the grate cooler. In order to extend the service life of the grate plate, it is necessary to timely track the development of the grate at home and abroad, optimize the grate plate, guarantee its performance.