RESEARCH ON CO DEFLAGRATION AND EXPLOSION PREVENTION IN THE ALL-DRY PROCESS OF GAS SENSIBLE HEAT RECOVERY FOR BASIC OXYGEN FURNACE
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摘要: 氧气转炉煤气一般在850 °C左右时采用喷水/水雾法降温除尘, 导致煤气50%的显热被浪费. 为了充分利用转炉炼钢过程中富含CO煤气的余热资源, 新方法取消了喷水工艺, 采用转炉煤气全干法显热回收系统, 但是该技术在转炉煤气前烧与后烧阶段存在煤气爆炸的风险. 针对转炉全干法系统的安全稳定运行需求, 通过实验和理论计算研究了CO当量比、混合气初始温度和含水量等因素对CO爆燃特性的影响. 结果表明: CO爆燃的最大压力和火焰速度随着混合气体中CO当量比的减小呈现减少的趋势, 但当CO当量比小于0.368时, 则对火焰速度的影响不大. 在实验CO当量比范围内, 爆燃压力最大值为0.65 MPa, 最大爆燃速度约为750 m/s; 混合气体初始温度升高导致爆燃过程中产生的最大爆燃压力降低, 与此同时火焰速度会相对增加, 进而影响火焰传播时间. 含水量增加会导致CO爆燃的最大爆燃压力的增加, 但含水量到达0.463%后继续增大则对最大爆燃压力影响不大; 最后, 通过分析CO爆燃特性和实际生产过程, 提出了燃烧控制与强化以及煤气爆炸遏制等防爆方法和技术, 从而有效降低爆燃带来的损失.Abstract: When the gas of basic oxygen furnace (BOF) is about 850 °C, water spray is generally used for cooling and dedusting, resulting in 50% of the sensible heat of the gas being wasted. In order to fully utilize the waste heat resources rich in CO gas during the converter steelmaking process, the new method cancels the water spraying process and adopts the converter gas fully dry sensible heat recovery system. However, this technology poses a risk of gas explosion during the pre and post combustion stages of the converter gas. In response to the safe and stable operation requirements of the full dry process system of the converter, this article investigates the effects of factors such as CO equivalence ratio, initial temperature of the mixed gas, and water content on CO deflagration characteristics through experiments and theoretical calculations. The results show that the maximum pressure and deflagration speed of CO deflagration decreases with the decrease of CO equivalence ratio in the mixed gas. But, when the CO equivalence ratio is less than 0.368, the effect on flame speed is not significant. Within the range of CO equivalence ratio in the experiment, the maximum deflagration pressure is 0.65 MPa, and the maximum deflagration speed is about 750 m/s; The initial temperature increase of the mixed gas leads to a decrease in the maximum deflagration pressure generated during the deflagration process, while the flame speed increases relatively, thereby affecting the flame propagation time. An increase in water content will lead to an increase in the maximum deflagration pressure of CO deflagration, but further increase after the water content reaches 0.463% has little effect on the maximum deflagration pressure; Finally, by analyzing the characteristics of CO deflagration and the actual production process, explosion-proof methods and technologies such as combustion control and enhancement, as well as gas explosion containment, were proposed to effectively reduce the losses caused by deflagration.
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图 1 实验系统流程图
1. variable frequency roots blower, 2. barometer, 3. ball valve, 4. mass flow meter, 5. ball valve, 6. ball valve, 7. water tank, 8. temperature and humidity measurement port, 9. electric heater, 10. thermocouple, 11. igniter, 12. pressure sensor, 13. silencer, 14. flame sensor, 15. mass flow meter, 16. electromagnetic valve, 17. gas cylinder, 18. control and signal acquisition station
Figure 1. Flow chart of experimental system
表 1 工况表
Table 1. Operating conditions
NO T/K Gas flow/( Nm3·h−1) CO equivalence ratio Φ CO volume concentration/% Water concentration/% air CO 1 368 28 8.2 0.697 22.7 0.329 2 368 33 8.2 0.591 19.9 0.329 3 368 38 8.2 0.514 17.7 0.329 4 368 43 8.2 0.454 16.0 0.329 5 368 48 8.2 0.407 14.6 0.329 6 368 53 8.2 0.368 13.4 0.329 7 368 56 8.2 0.350 12.8 0.329 8 368 59 8.2 0.331 12.2 0.329 9 342 28 8.2 0.697 22.7 0.329 10 440 28 8.2 0.697 22.7 0.329 11 503 28 8.2 0.697 22.7 0.329 12 538 28 8.2 0.697 22.7 0.329 13 573 28 8.2 0.697 22.7 0.329 表 2 不同温度下各管段火焰传播时间
Table 2. Flame propagation time of each pipe section at different initial temperatures
Temperature/K Smooth
section/msObstacle
section/msTotal time/ms 342 145.15 152.10 6.95 368 140.46 146.77 6.32 440 116.40 122.30 5.90 480 97.50 102.85 5.35 503 85.50 90.00 4.50 -
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