Selection of wear-resistant materials for grate coolerDate: 2019-06-21 Views:
1 High temperature section raft and side panel material selection
The clinker temperature at the end of the grate cooler is the highest (about 1400 °C), and it has the highest temperature oxidation corrosion of the slab and side plates. Therefore, the requirements for selecting the slab and side plate materials are the highest. In addition, the different structural forms of the trampoline at this place have different requirements for the material of the seesaw and the side plates. According to the working condition and wear failure mechanism of the feed end of the grate cooler, the girder and side plates at the place should be made of heat-resistant steel with good anti-oxidation performance, high heat-resistance temperature and good anti-wear performance. According to the influence and function of alloying elements and carbon in steel, we know that Ni element is an austenite forming element, which has good coordination with Cr and good oxidation resistance; C element content is at the upper limit, which is beneficial to abrasion resistance and heat resistance. However, it is not conducive to anti-oxidation, so the carbon content of heat-resistant steel should be controlled as close as possible to the midline, generally about 0.25%-0.40%. Based on the above factors, according to China's heat-resistant steel casting standard (GB/T8492-1987), we recommend ZG35Cr26Ni12 heat-resistant steel for the raft and side plates in the high temperature section of the chiller (clinker temperature is about 1400-700 °C). The heat-resistant steel has a maximum use temperature of 1,100 ° C, high temperature strength, good oxidation resistance and anti-wear performance. ZG4OCr25Ni20 heat-resistant steel with slightly higher carbon content can also be used. Its maximum service temperature is 1150 °C, it has high creep strength and long-lasting strength, strong resistance to high-temperature gas corrosion, good anti-wear performance, but high cost.
The different boring machine structures at the feed end of the grate cooler have different requirements for the material of the slab and the side plates. For example, the first-generation and second-generation grate coolers and the third-generation grate cooler designed by a few units, the first row of rafts at the man-end end are movable rafts, and the clinker discharged from the kiln is quickly pushed away by the movable slab. There is no foundation for rooting and no snowman will be formed. The disadvantage is that the high-temperature red hot clinker discharged from the kiln is directly washed on the raft, so that the slab is subjected to high temperature oxidation and spalling, and the wear is particularly serious. Even if ZG40Cr25Ni20 heat-resistant steel is selected, its service life is only 3.6. month. It is inevitable that the high temperature section of the raft is frequently replaced, which greatly reduces the operating rate of the chiller (≤80%) and increases the cost.
2.Selection of slab and side panel materials for medium temperature section
In the middle temperature section of the grate cooler, the clinker has been significantly cooled, and the clinker temperature has changed to about 700-400 °C. The high temperature oxidation corrosion resistance of clinker has been significantly reduced, and the application of thick layer control technology can effectively protect the seesaw. Due to the thick layer, the clinker at the bottom of the bottom plate is sufficiently cooled to prevent thermal wear and hot corrosion of the upper layer of high temperature clinker on the raft, which is beneficial to prolong the service life of the raft. ZG30Cr26Ni5 heat-resistant steel can be used for the raft and side plate materials in the middle section of the grate cooler. The maximum temperature is 1050 °C, which has good high temperature strength, good oxidation resistance, good anti-wear performance and load-bearing temperature. Up to 650 ° C. Or use ZG35Cr24Ni7SiN heat-resistant steel, the maximum use temperature is 1100 ° C, high temperature strength, good oxidation resistance, but high cost, generally not recommended.
3.Selection of cage plate and side plate materials for low temperature section
In the low temperature section of the grate cooler, the clinker temperature has been reduced to a minimum, generally around 400 to 110 °C. At this time, the hardness of the clinker has reached the highest, and the wear resistance of the slab and the side slab is mainly considered, and has certain anti-oxidation ability. We recommend ZG4OCr9si2 or ZG3OCrl8Mnl2Si2N, or ZG30Cr26Ni5 heat-resistant steel, the cost is slightly higher.