煤气化过程中产生的焦油在低温下会发生冷凝，堵塞工艺设备，污染燃气设备，增加运行成本。而基于焦油生成特性调整运行参数，可降低气化炉原始焦油质量浓度和焦油脱除成本。为获得流化床煤气化过程中焦油的生成特性，借助流化床反应器，研究温度、空气当量比、表观气速、煤的粒径和含水率等对气化气中焦油生成量的影响规律。研究结果表明：升高温度或提高空气当量比，均有利于降低煤气化过程中焦油质量浓度，但2者的影响有限。炉内表观气速ug在0.19～0.33 m/s逐渐增加时，气固两相间接触混合加剧，改善了炉内传热传质效果，促进焦油热分解，而当鼓泡流态化向湍动流态化过渡时，气固两相间的接触混合不再明显增强，焦油质量浓度变化不大；煤颗粒粒径较小，可提高化学反应速率，促进产生焦油的热分解，但在一定的流化风速下，气化原料粒径越小，越易分布在床面，反而削弱了煤和床料间的热量传递，缩短了焦油在炉内的停留时间，导致焦油质量浓度增大；不同含水率的煤在气化过程中测得焦油质量浓度差异较明显，含水率过高或过低都对降低焦油的生成量不利。

Tar generated during the coal gasification may condense at low temperature,thus blocking the process equipment,leading to the pollution of the equipment,and increasing operating costs. The adjustment of operation parameters based on the tar generation characteristics would be conducive to reduce the original tar emission from a gasifier and reduce the cost of tar removal. In order to obtain the generation characteristics of tar in fluidized bed coal gasification,the effects of parameters such as bed temperature,air equivalent ratio,superficial gas velocity,coal particle size and water content,upon the generation amount of tar in the product gas were studied by fluidized bed reactor. The results show that increasing temperature or air equivalent ratio is beneficial to the decrease of tar mass concentration,but the effects are both limited. When the apparent gas velocity ug in the furnace increases from 0.19 to 0.33 m/s,more intensified contact and mixing between gas and solids improve the effects of heat transfer and mass transfer in the gasifier and promote the thermal decomposition of tar produced. However,as the bubbling fluidization transits to turbulent fluidization,the contact and mixing between gas and solids are no longer significantly enhanced,and the tar mass concentration thus changes little. The small diameters of coal particles can improve the chemical reaction rate and promote the thermal decomposition of tar. However,at a certain fluidization gas velocity,the smaller the gasification feedstocks is,the more it is easily distributed on the bed,which weakens the heat transfer between coals and bed materials,and shortens the residence time of tar in the furnace,leading to the rise of tar mass concentration. The tar mass concentrations in the product gas of coal gasification under different moisture contents have obvious difference. Neither too high nor too low for water content are beneficial to the reduction of tar generation.

0 引言

1 试验

   1.1 试验物料

   1.2 试验装置

   1.3 试验方法

2 结果与分析

   2.1 温度对煤气化焦油质量浓度的影响

   2.2 空气当量比对煤气化焦油质量浓度的影响

   2.3 表观气速对煤气化焦油质量浓度的影响

   2.4 煤粒径对煤气化焦油质量浓度的影响

   2.5 含水率对煤气化焦油质量浓度的影响

3 结论