Characteristic technology of sintering
1、Selective sintering flue gas circulation technology
Selective flue gas circulation technology is adopted, on one hand, it can reduce the investment and operation cost of flue gas DeSOx & DeNOx, on the other hand, it can effectively utilize flue gas waste heat and save solid fuel consumption.
The research shows that, the O2 content in sintering process is above 17%, it can ensure the quality and output of sinter. Flue gas circulation process is adopted, that is, the flue gas at the sintering machine charge end & discharge end is selected for circulation, this flue gas has high O2 content, low SO2 and NOx content, which is conducive to smooth sintering process; The content of SO2 and NOx in flue gas in the middle of sintering machine is high, which is conducive to DeSOx & DeNOx and will reduces pollutant discharge.
30~40% of the total flue gas quantity is selected for circulation, and some fresh air is supplemented to ensure that the O2 content entering sintering machine bed is about 18%, and the left 60~70% is discharged into atmosphere after DeSOx & DeNOx treatment to national standard.
2、New style sealed type annular cooler
In order to reduce air leakage rate of annular cooler, new style sealing structure of upper and lower double water seals is adopted, which greatly reduces air leakage between annular cooler air box and pallet car, and between pallet car and exhaust hood, on one hand, supply air volume of annular cooler fan is reduced to achieve energy conservation purpose, on the other hand, the annular cooler exhaust gas overflow is reduced, waste heat recovery volume is large, temperature is high, and environmental protection effect is excellent.
3、High efficiency cascade waste heat recovery technology
Sinter cooling will produce large amount of high-temperature waste gas, in order to maximize energy recovery, efficient cascade waste heat recovery technology is adopted to recover waste gas waste heat of annular cooler.
Due to adaptation of double water sealing annular cooler, waste gas temperature of annular cooler section I can reach 450℃, and section II can reach 390℃, to fully recover energy, high-temperature flue gas in section I and section II of annular cooler respectively enters waste heat recovery boiler, flue gas in section I is mixed with flue gas in section II through high-pressure superheater, and then flows through high-pressure evaporator, high-pressure economizer, low-pressure evaporator and condensate heater, and then again enters annular cooler bellows by hot air circulating fan for sinter cooling, then the next cycle proceed.
Due to good sealing effect of annular cooler, waste flue gas temperature in section III can reach 250℃~300℃, this flue gas still has high utilization value, which is used to produce 110℃ hot water by heat exchanger for external use.
4、Frequency conversion technology of main ID fan
Main ID fan is the core equipment for sintering process, power consumption of main ID fan accounts for the majority of whole power consumption in sintering process, in order to reduce power consumption in sintering process, asynchronous motor and variable frequency operation mode are adopted, instead of relying on damper to regulate the air volume, VFD adopts high-efficiency water-cooling mode, with obvious power saving effect.