折流内构件移动床新疆淖毛湖煤热解试验研究

Experimental study on pyrolysis of Xinjiang Naomaohu coal in a moving bed with baffled internals

为了提取低阶煤中天然赋存的油气资源以获得高品质的焦油和煤气产品,并解决现有热解技术无法处理小粒径煤、焦油产率低、焦油品质差等技术瓶颈,提出了一种新型外热式折流内构件移动床热解工艺。以新疆淖毛湖煤为研究对象,考察了热解温度、分段控温、多段集气等因素对热解产物分布和品质的影响,验证了新型反应器(折流内构件和多段集气系统)强化小粒径低阶煤热解反应的可行性和先进性。结果表明:折流内构件移动床热解工艺可以处理小粒径低阶煤;折流内构件可强化颗粒的运动,可显著提高颗粒的传热速率,当颗粒进入第2床层时(大约需要40 min)可达到目标温度,且整个试验过程的温度分布较稳定;淖毛湖煤在低温下热解所得焦油品质较差,焦油中的脂肪烃含量较高,适当提高温度会促进焦油的二次反应并有助于提高焦油的品质;通过建立逐渐升温的温度梯度可以提高焦油品质;多段集气系统确保了挥发分物质及时排出,并抑制了挥发分物质在高温下的二次裂解反应;对于粒径为0.4~6.0 mm的新疆淖毛湖煤,当进煤量为5.0 kg/h、停留时间为2.0 h、热解温度为550℃时,焦油产率最高为10.81%,占格金焦油产率的82.5%,焦油中沸点大于360℃的重质组分含量为15.0%,该条件下的焦油的产率及品质均较高;在折流内构件强化热解反应的同时,通过协同调控反应器温度和分段集气可有效提高焦油的产率和品质。

In order to extract the oil and gas resources naturally present in low-rank coal to obtain high-quality tar and gas products,and to solve the technical bottlenecks that the existing pyrolysis technology cannot handle small-sized coal,low tar yield,and poor tar quality,etc,a new externally-heated pyrolysis technology for the moving bed with baffled internals was proposed.Taking the Naomaohu coal in Xinjiang as the research object,the effects of pyrolysis temperature,temperature control by stages,and multi-stage gas gathering on the distribution and quality of coal pyrolysis products were investigated.The feasibility and advancement of the new reactor(baffled internals and multi-stage gas gathering system)to strengthen the pyrolysis reaction of small-size low-rank coals were verified.The results show that the moving bed pyrolysis process with baffled internal components can handle low-rank coal with small particle size.The baffled internals can strengthen the movement of the particles and can significantly increase the heat transfer rate of the particles.When the particles enter the second bed(about 40 min),they can reach the target temperature,and the temperature distribution throughout the experiment is relatively stable.The tar obtained by pyrolysis of Naomaohu coal at low temperature has low quality,and the content of fatty hydrocarbons in tar is high.Properly increasing the temperature will promote the secondary reaction of tar and help to improve the quality of tar.The tar quality can be improved by establishing a gradually increasing temperature gradient.The multi-stage gas collection system ensures that the volatile matter is discharged in time and inhibits the secondary cracking reaction of the volatile matter at high temperature.For Xinjiang Naomaohu coal with a particle size of 0.4 mm to 6.0 mm,when the coal feed rate is 5.0 kg/h,the residence time is 2.0 h,and the pyrolysis temperature is 550℃,the highest tar yield is 10.81%,which is 82.5%of Gray-King tar yield.The content of heavy components with a boiling point greater than 360℃is 15.0%,and the tar yield and quality under this condition are high.While the baffled internals strengthen the pyrolysis reaction,the tar yield and quality can be effectively improved by synergistically regulating the reactor temperature and the staged gas collection.