煤种配合比对煤焦水蒸气气化反应特性的影响

选取长焰煤、气煤及肥煤为原料,通过调配比例得到不同配合煤,采用捣固方法,在终温为1 150℃的程序升温马弗炉中制备坩埚焦,利用实验室固定床反应器考察煤焦的水蒸气气化反应性,并对产气量及产品气组成进行测试。结果表明,配合煤焦水蒸气气化反应性及产品气组成与配合煤比例的变化密切相关,配合煤中对焦的水蒸气气化反应性起提高作用的煤种的顺序为:长焰煤气煤肥煤。气化过程中煤焦孔隙结构的变化行为是影响煤焦反应性的主要因素,具有较大煤阶差的长焰煤与肥煤比例的相对变化对焦结构的影响最为显著,对焦的反应性的影响也最为明显。配合煤比例变化影响催化性矿物质在焦中的含量,适度增加配合煤中肥煤及气煤的比例有利于催化性矿物质在焦中的滞留,当配合煤中肥煤比例为0. 3左右时,该影响作用最为显著,煤种比例变化对配合煤挥发分组成及热解过程孔隙结构发展的影响会改变催化性矿物质在焦中的含量。焦中催化性矿物质可以促进焦气化反应过程中水煤气变换反应的发生,进而可以调变产品气的组成。在利用过剩焦化产能及低质炼焦煤制备气化焦的过程中,研究结果可以为调配配煤方案以有效改善气化焦的反应性并调变产品气的组成提供理论依据。

Effects of blending ratios of coals in blends on the steam-gasification characteristics of coke

The coal blends with the different ratios of three dif-ferent ranks of coals were used for the preparation of the coke at 1 150 ℃ in a muffle furnace.The gasification reactivity,gas production and the composition of product gas were tested through a fixed-bed reactor in a laboratory scale coupled with the gas analyzer.It shows that the gasification reactivity and product gas composition are con-trolled by the coal blending ratios in the blends.The order that the increasing effect of single coal on the CRI of the cokes is:MSC>WGC>DFC.The relative change of the subbituminous coal and fat coal in blends has the crucial influence on the pore structure and the reactivity of the coke.The blending ratio of the coals in blends affects the content of the catalytic element in the coke.The increase of the gas coal and fat coal lead to the increase of the catalytic element in the coke,and the ratio of fat coal being about 0.3 is especially helpful for the retaining of the catalytic element.The component of volatiles and the evolution of the pore structure during pyrolysis influence the content of catalytic element in the coke.The catalytic elements in the coke can promote the occurrence of the water-gas shift reaction and then adjust the composition of product gas.The results provide a theoretical foundation for improving the coke reactivity and modifying the composition of the product gas through the optimization of coal blending in the coking process,thus contributing to the utilization of excess coking capacity and low quality coking coal.