Abstract: The iron and steel industry, as one of the lifebloods of the national economy, has become a key focus of attention in the field of energy conservation and emission reduction as the goals of carbon peaking and carbon neutrality continue to advance. Iron ore sintering is the second largest carbon emission process in the iron and steel industry after blast furnace ironmaking. Existing studies indicate that steam injection onto the sintering bed surface can improve the fuel combustion efficiency of the sinter layer, increase the sintering index, and reduce CO emission concentration of flue gas. In this work, the mechanism of CO emission reduction by injection of steam onto the sintering bed surface was studied. The effect of steam on CO gas oxidation at high temperatures was studied by using a fixed bed experiment to simulate the injection steam onto the sintering bed surface. The results showed that the steam in the gas phase system can significantly promote the oxidation of CO. The gas phase oxidation of CO almost did not occur in the condition of no water vapor, and the steam promoted CO oxidation significantly when the volume fraction was above 2.0%. The CO oxidation reaction catalyzed by steam starts at 650℃, and the reaction accelerates with the increase of temperature. A stable and continuous reaction interval appears at 700℃ and above. With the volume fraction of steam increasing, the beginning time of CO gas phase oxidation was advanced and the duration was extended. Under the conditions of O2 and CO volume fractions of 2.0% and 2.5%, respectively, the steam volume fraction of 12.0% can promote the highest CO oxidation efficiency, and the CO oxidation efficiency can reach at 99.95%. The research was of great significance for improving the theory of steam injection technology on sinter surfaces and guiding production practice.

Key words: iron ore sintering, steam injection, gas phase system, CO oxidation

摘要： 铁矿烧结是钢铁行业仅次于高炉炼铁的第二大碳排放工序。烧结料面喷吹水蒸气可以提高烧结料层燃料燃烧效率，降低烟气CO排放浓度。本工作对烧结料面喷吹水蒸气在烧结过程中实现CO减排的机理进行研究，采用固定床实验模拟烧结料面喷吹水蒸气，研究了高温条件下水蒸气对CO气相氧化的影响。结果表明，气相体系中水蒸气对CO氧化有显著促进作用。CO气相氧化在无水的条件下几乎不发生，2.0%体积分数以上水蒸气显著促进CO氧化；水蒸气催化CO氧化反应起始于650℃，随温度升高反应不断加快，700℃及以上时会出现一个稳定连续的反应区间。随着通入水蒸气体积分数的增加，CO气相氧化的开始时间提前，持续时间延长。在O2和CO体积分数分别为2.0%, 2.5%的条件下，水蒸气体积分数为12.0%时促进CO氧化效率最高，CO氧化效率可达99.95%。该研究对完善烧结料面喷吹水蒸气技术理论，指导生产实践具有重要意义。

关键词: 铁矿烧结, 喷洒蒸气, 气相体系, CO氧化