The chemical looping gasification uses an oxygen carrier for solid fuel gasification by supplying insufficient lattice oxygen. The effect of gasifying medium on the coal chemical looping gasification with Ca SO4 as oxygen carrier is investigated in this paper. The thermodynamical analysis indicates that the addition of steam and CO2 into the system can reduce the reaction temperature, at which the concentration of syngas reaches its maximum value.Experimental result in thermogravimetric analyzer and a fixed-bed reactor shows that the mixture sample goes through three stages, drying stage, pyrolysis stage and chemical looping gasification stage, with the temperature for three different gaseous media. The peak fitting and isoconversional methods are used to determine the reaction mechanism of the complex reactions in the chemical looping gasification process. It demonstrates that the gasifying medium(steam or CO2) boosts the chemical looping process by reducing the activation energy in the overall reaction and gasification reactions of coal char. However, the mechanism using steam as the gasifying medium differs from that using CO2. With steam as the gasifying medium, parallel reactions occur in the beginning stage, followed by a limiting stage shifting from a kinetic to a diffusion regime. It is opposite to the reaction mechanism with CO2 as the gasifying medium.
利用热重分析仪及管式炉反应器研究了餐厨垃圾的热解行为。餐厨垃圾的热解过程包括两个阶段,结合微分法与积分法对两阶段进行了动力学计算,确定管式炉热解实验反应温度。对热解产物进行了分析,结果表明,气体产物主要是CO和CH4;固体产物焦的恒容低位发热量为20.33 MJ kg 1;液体产物焦油主要是醇和烃,占焦油总量的70.55%。通过分析不同热解温度焦的红外谱图、元素组成及热解过程的小分子气体释放规律,探究了餐厨垃圾的热解机理。290℃时,餐厨垃圾中肽键断裂,释放出大量CO2和CO;350℃时,脂类化合物已经完全分解或挥发;500℃时,焦中甲基及亚甲基峰消失,释放出大量烃类;未分解的物质主要是淀粉。最后考察了升温速率对热解产物分布的影响,发现提高升温速率,焦收率基本不变,焦油收率下降,气体产物收率增加。
