增压O_2/CO_2气氛下煤燃烧特性实验研究

增压O2/CO2燃烧是一种可高效分离回收CO2的新兴燃烧技术,其燃烧机理与常压空气、常压O2/CO2燃烧存在较大差异。在加压热重分析仪上研究了增压条件下总压、氧浓度、气氛及粒径等反应参数对美国烟煤和淮北无烟煤燃烧特性的影响,确定了煤的着火温度,并对其进行燃烧动力学分析。结果表明,增压O2/CO2气氛下,随着压力或氧浓度的增加,DTG曲线向低温区移动,煤样整体燃烧速率加快。压力提升、氧浓度增加及煤粉细化均可改善O2/CO2气氛下煤样的着火特性。常压O2/CO2气氛下煤粉燃烧基本属于一级反应;增压O2/CO2气氛下,低温区属于0.5级反应,而高温区属于1.5级反应。

Experimental investigation on pressurized coal combustion characteristics under O2/CO2 atmosphere

The pressurized O₂/CO₂ combustion is a potential technique, which makes CO₂ separation and recovery more efficient. However, it has a notably different mechanism from the air combustion and the O₂/CO₂ combustion under atmospheric pressure. The combustion characteristics of an American bituminous coal and a Huaibei anthracite coal under O₂/CO₂ atmosphere were studied employing the thermo-gravimetric analyzer at various pressures (p=0.1~1.5 MPa). The influences of pressure, oxygen concentration, atmosphere and particle size on the coal combustion characteristics were inspected, and the ignition temperature was obtained. Also, the combustion kinetic parameters were calculated. The results indicate that as the total pressure or oxygen concentration increases, DTG curves move to the low temperature zone and the overall combustion rate of coal samples is accelerated under pressurized O₂/CO₂ atmosphere. The ignition characteristics of pulverized coal could be improved through the pressure enhancement, the increase of oxygen concentration and the reduction of particle size. The pulverized coal combustion under atmospheric pressure is basically a first order reaction. For pressurized oxy-fuel combustion, the reaction order is 0.5 under the low temperature zone, while the reaction order becomes 1.5 under the high temperature zone.