Reforming of converter gas with coke oven gas for thermochemical energy storage and carbon dioxide emission reduction

During traditional processing and utilizing of converter gas, a common by-product gas of steel production, the recycling of waste heat is insufficient, carbon emission is high, and the added value of the gas is low. The reforming of converter gas with coke oven gas is proposed to utilize the gas more efficiently. The reforming recycles the waste heat of the gas by thermochemical energy storage technology and converts CH4 and CO2 into H-2 and CO, which improves the recovery rate of the waste heat and gas added value, and reduces the direct emission of CO2. Thermodynamic equilibrium calculation and regression analysis were used to investigate the effects of the temperature, pressure, and mole fraction of coke oven gas on the results of the reforming. The results show that atmospheric pressure and the temperature range of 850 degrees C-1000 degrees C are suitable for the reforming, at which the conversion rates of CH4 and CO2 are more than 90% and 75%, respectively. The ratio of H-2 to CO is determined by the mole fraction of coke oven gas. Then, the reforming process was investigated by experiments which simulated the reforming process in converter flue. The experimental results show that the in-suit catalysis of converter dust can significantly improve the conversion rates of CH4 and CO2 and the conversion rates can reach a high level at about 1000 degrees C. Then, the waste heat utilization of the reforming was investigated, and it was concluded that 35-40% of the waste heat is converted into chemical energy in the reforming. After the waste heat power generation of the product gas, the total recovery rate of waste heat is 60-65%. Finally, the amount of coke oven gas reformed by a fixed amount of converter gas without additional heating was calculated. The results show that when the preheating temperature of coke oven gas is 500 degrees C the range of 850 degrees C-900 degrees C is appropriate for the reforming, at which the conversion rate of CO2 is approximately 50% and about 40% of the waste heat was converted to chemical energy. For a steel plant with an annual output of 20 million, the direct emission of CO2 can reduce by 2.13 x 10(8) Nm(3), and waste heat of 3.24 x 10(6) GJ can be converted into chemical energy.

Automated summary

The research aims to improve the efficiency of converter gas utilization, reduce CO2 emissions, and enhance waste heat recovery by reforming coke oven gas. By using thermochemical energy storage technology to convert CH4 and CO2 into H-2 and CO, the study ensures the effectiveness of the reforming process.