Experimental studies on reduction desulfurization of FGD gypsum from iron ore sintering process using CO/H2
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摘要: 通过热力学软件Factsage7.3对CO/H2还原CaSO4进行热力学平衡计算。计算得到CO/H2还原CaSO4生成CaO和SO2的最佳理论条件为:反应温度1100 ℃以上、摩尔比n(CO)∶n(CaSO4)=n(H2)∶n(CaSO4)=1,过高或过低的还原剂摩尔比均不利于CaSO4的还原脱硫,同时温度越高越有利于CaSO4的CO / H2还原脱硫。根据Factsage7.3计算结果,以N2作为混合气体,在高温炉中进行了15 g烧结烟气脱硫石膏的CO/H2还原脱硫试验,考察CO/H2浓度、反应温度、反应时间、还原气体流量对脱硫石膏CO/H2还原脱硫的影响。结果表明:有利于脱硫石膏CO还原脱硫的最佳条件为CO浓度5%、反应温度1050 ℃、反应时间30 min、气体流量5 L/min;有利于脱硫石膏H2还原脱硫的最佳条件为H2浓度8%、反应温度1050 ℃、反应时间30 min、气体流量为5 L/min,且CO分解还原脱硫效果较H2还原脱硫的效果要好。试验发现在900 ℃以上时脱硫石膏有烧结现象发生,且随温度升高烧结程度更重,影响了CO/H2的还原脱硫效率。Abstract: The thermodynamic equilibrium of CO/H2 reduction of CaSO4 was calculated through software FactSage 7.3. The optimum theoretical conditions for generation of CaO and SO2 by CO/H2 reduction of CaSO4 were obtained at more than 1100 ℃ of reaction temperature and mole ratio of n(CO)∶n(CaSO4)=1 or n(H2)∶n(CaSO4)=1. The reduction agent with a too high or too low mole ratio (n(CO)∶n(CaSO4) or n(H2)∶n(CaSO4)) is not beneficial to the reduction desulfurization of CaSO4. A higher temperature is favorable for the CO/H2 reduction desulfurization of CaSO4. According to the thermodynamic calculation results, experimental studies on reduction desulfurization of FGD gypsum from iron ore sintering process were carried out using CO/H2+N2 mixture gas in a furnace, and the influences of CO/H2 concentration, reaction temperature, reaction time and gas flow rate on the reduction desulfurization of FGD gypsum by CO/H2 were studied. The results show that the beneficial conditions for CO reduction desulfurization of FGD gypsum are CO concentration of 5%, temperature of 1050 ℃ for 30 min and gas flow rate of 5 L/min. The beneficial conditions for H2 reduction desulfurization are H2 concentration of 8%, temperature of 1050 ℃ for 30 min and gas flow rate of 5 L/min. The efficiency of reduction desulfurization by CO is better than that by H2. During the reduction process, FGD gypsum sinters above 900 ℃ and it makes a notable impact on the reduction desulfurization of the FGD gypsum.
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Key words:
- sintering /
- flue gas /
- desulfurization gypsum /
- reduction desulfurization /
- CO /
- H2 /
- desulfurization ratio
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表 1 烧结烟气脱硫石膏化学成分
Table 1. Compositions of FGD gypsum
% CaO SiO2 MgO Al2O3 TFe P (SO3) 全S 38.40 1.71 0.21 0.25 0.23 ≤0.003 (51.75) 20.70 -
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