生物质与煤共热解对煤中硫脱除及迁移影响机制研究

The factors affecting the pyrolysis of biomass are very similar to those of coals, including heating rates, pyrolysis temperatures, residence times and so on. In addition, the pyrolysis temperature range of biomass can overlap with that of coals. If the active hydrogen from biomass pyrolysis can combine with sulfur-containing radicals during coal pyrolysis, the composition and content of sulfur forms would have a big change in gas, char and tar phases. However, the bio-oil or the metaplast, which was formed during biomass pyrolysis, can also affect the sulfur release and transformation behavior. But, the mechanism of biomass’ effects on sulfur removal and transformation is still unavailable. Thus, in this project, the mechanism of effects of biomass on sulfur removal and transformation behavior will be investigated during co-pyrolysis with coals. The fixed bed reactor (one section or multi-section heated)，thermogravimetric Analysis connected with mass spectrum would be used to study the effects of biomass on sulfur removal and release behavior during co-pyrolysis. Firstly, the factors affecting sulfur release and transformation, such as the types of biomass, the mixed ratio of biomass, mixed methods, heating rates and pyrolysis temperatures, would be investigated. Then, the sulfur forms and its content and transformation behavior in gas, char and tar phases would be analyzed detailedly. Lastly, the mechanism of effects of biomass on sulfur removal and transformation could be obtained during co-pyrolysis. Therefore, this project can provide theoretical basis for comprehensive utilization of high sulfur content and low quality coal and biomass.

生物质热解与煤热解的影响因素相似，二者均受升温速率、热解温度、反应停留时间等影响。生物质与煤的热解温区可部分重叠，如生物质释放的活性氢可与煤热解产生的含硫自由基结合，热解气、焦油和半焦中硫形态的组成及含量将会受到很大影响。生物质受热产生的胶质体、生物油也会影响煤热解过程中硫的逸出及迁移机制，但是目前关于生物质对煤热解脱硫的影响机制研究却很少。本项目欲对生物质与煤共热解对煤脱硫的影响机制进行研究，考察生物质与煤共热解对硫逸出及迁移机理的影响：采用固定床反应器（一段或和多段加热)和热重-质谱等研究生物质与煤的共热解对煤热解脱硫的影响，考察生物质的种类、加入量、加入方式、升温速率、热解温度等因素对硫逸出机理的影响，再对热解气体、焦油、半焦中硫形态及含量等进行详细分析，最终得出生物质对煤热解脱硫的影响机制。因此，通过本项目研究能为生物质与高硫劣质煤的综合利用技术奠定一定的基础。

采用热解-色谱（Py-GC）和热解-质谱（Py-MS）研究了Ar 和CO2 气氛下不同混合比例对鄂尔多斯煤（ED）/长治煤（CZ）与玉米芯（COB）共热解过程中硫迁移释放的影响；同时利用Py-GC 和Py-MS 考察了Ar 和CO2 气氛下长治煤中矿物质在共热解过程中对硫迁移转化的影响，并研究了长治煤与玉米芯的共热解方式对硫迁移释放的影响。 另外，探究了不同共热解方式（直接混合和间接分层）对阳泉原煤（YQR）、鄂尔多斯原煤（EDR）及其脱灰煤和脱黄铁矿煤与生物质（玉米芯）在Ar、CO2气氛下共热解时对硫迁移的影响。利用热解-色谱（Py-GC）考察了这两种煤在CO2 气氛下直接混合与间接分层共热解时，添加不同的生物质比例（25%、50%、75%、100%）对硫迁移与转化的影响。同时考察了微量氧气气氛（1% O2-Ar、3% O2-Ar）对阳泉原煤及其脱灰煤和脱黄铁矿煤共热解过程中硫迁移的影响规律。也 采用热解-色谱（Py-GC）对烟煤（BC）/无烟煤（AC）及其脱灰煤（DA）和脱黄铁矿煤（DP）以及煤矸石（CG）与杨树叶（YL）和木屑（SD）在Ar 和CO2 气氛下混合共热解过程中含硫气体的释放行为进行研究；同时考察了不同分层共热解方式对热解过程中含硫气体释放行为的影响，以及木聚糖（HCE）、微晶纤维素（CE）和碱性木素（LIG）与煤在高温区分层共热解时对含硫气体释放行为的影响。最后，利用第一性原理主要计算了煤热解过程中的噻吩及含硫气体在CuO（111）表面的脱硫-固硫机理；同时考察了活性氧原子负载及金属Ni掺杂后对CuO表面脱硫-固硫机理的影响机制；也考察了S原子在CuO不同切面上的吸附机理研究。也利用第一性原理计算了煤热解过程中，含硫气体及噻吩类硫在CaO（001）表面的脱硫机理；同时考察了改性CaO（001）表面对固硫机理的影响。所得结论可为煤与生物质共热解脱硫机理提供理论依据。