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煤热解产物分布及主要元素的迁移规律研究
石振
学位类型硕士
导师高士秋 ; 许光文
2016-07
学位授予单位中国科学院研究生院
学位授予地点北京
学位专业化学工程
关键词煤热解 固定床 热解产物 元素迁移
摘要

煤炭是我国的主要能源,而我国煤炭资源主要以低阶煤为主,在低阶煤利用过程中,煤热解技术是清洁、高效利用低阶煤资源并提高其产品附加值的有效方法。煤中有机质主要由C、H、O、N、S五种主要元素组成,其中N和S元素在煤炭利用过程中是产生污染物(NOx、SOx)的来源,因此,很有必要研究煤热解过程中这五种主要元素在热解过程中的迁移情况,更加深入的认识煤热解过程,并有效地控制污染物的释放。本文的主要研究内容和结果如下:(1) 在石英管固定床反应器中对神木烟煤进行快速热解实验,研究了热解温度对煤快速热解产物分布及五种主要元素在热解产物中迁移规律的影响。结果表明,在实验温度500~900 ℃范围内,随热解温度升高,半焦产率下降,气体产率增大,焦油产率先增大后降低,在600 ℃达到最大值9.2%(ω),热解水收率先增大后略有降低;半焦中C、H、O和N元素迁入量下降,S元素迁入量先降低后略有增大,在700 ℃达到最小值67.0%;热解气中C、H、O元素迁入量呈现增大的趋势,N和S元素迁入量先增大后减小,分别在800 ℃和600 ℃达到最大值28.8%和27.9%;焦油中C、H、O元素迁入量呈现先增大后降低的趋势,均在600 ℃分别达到最大值9.3%、14.0%和7.2%,N元素和S元素迁入量有缓慢增大的趋势;热解水中H和O元素迁入量先增大后略有降低,在700 ℃分别达到最大值14.5%和48.5%。此外还对比研究了快速热解和慢速热解过程中产物分布及主要元素迁移规律的异同。(2) 在内构件固定床反应器中研究了热解温度对神木烟煤热解产物分布和煤中五种主要元素在热解产物中分配的影响。研究结果表明,随热解温度升高,半焦产率降低,气体产率增大,焦油产率略有增大,热解水产率略有降低;H2、CH4、CO、CO2、C2+C3、HCN、NH3、H2S和COS产率均呈现增大的趋势;半焦中各元素的迁入量均降低,气体中各元素的迁入量均增大,焦油中各元素的迁入量变化不大。(3) 在内构件移动床1000 t/a中试实验数据的基础上结合内构件移动床20 万t/a示范工程的设计参数,对神木烟煤热解过程中的能量和效率变化进行了计算。结果表明,用热解气燃烧给焦炉供热时,每热解1 t煤需要燃烧热解气89.7 m3,煤热解过程的热效率达到93.7%。

其他摘要

Coal is the main energy resource in China, and more than half of China’s total coal reserve is low-rank coal. Pyrolysis is a clean technology to utilize low-rank coal and obtain high value-added products effectively. The organic matter of the coal mainly consists of five elements of C, H, O, N and S, while N and S are the main sources of pollutants (NOx and SOx) respectively during utilizing the coal. Thus, it is necessary to explore the migration of the five main elements during coal pyrolysis so as to intensively understand the coal pyrolysis and effectively control the emission of pollutants during coal utilization. The followings are the main contents and conclusions:(1) The effect of pyrolysis temperature on distribution of products and migration of main elements (C, H, O, N and S) during rapid pyrolysis of Shenmu bituminous coal was investigated in a fixed-bed quartz reactor. The results showed that with the pyrolysis temperature increasing from 500 ℃ to 900 ℃, the char yield decreased and the gas yield increased continuously, while the tar yield increased to a maximum of 9.2%(ω) at 600 ℃ and then declined. When the pyrolysis temperature increased, the transfer ratios of C, H, O and N in the char decreased and the transfer ratio of S in the char first decreased and then increased with the minimum ratio of 67.0% at 700 ℃. With the increase of temperature, the transfer ratios of C, H and O in the gas increased and the transfer ratios of N and S in the gas first increased and then decreased at 800 ℃ and 600 ℃ with the maximum values of 28.8% and 27.9%, respectively. The transfer ratios of C, H and O in the tar first increased respectively to the maximum values of 9.3%, 14.0% and 7.2% at 600 ℃ and then decreased, while the transfer ratios of N and S slightly increased with the pyrolysis temperature increasing. The transfer ratios of H and O in the water first increased respectively to the maximum values of 14.5% and 48.5% at 700 ℃ and then decreased slightly with pyrolysis temperature increasing. Moreover, the difference between slow pyrolysis and rapid pyrolysis was also studied on the migration of main elements in the products during Shenmu coal pyrolysis.(2) The effect of pyrolysis temperature on distribution of products and migration of main elements (C, H, O, N and S) during pyrolysis of Shenmu bituminous coal was investigated in the reactor with internals. The results showed that with the pyrolysis temperature increasing the yields of char and water decreased while the yields of gas and tar increased. The yields of H2, CH4, CO, CO2, C2+C3, HCN, NH3, H2S and COS all increased when the pyrolysis temperature increased. The transfer ratios of all the elements declined in the char and increased in the gas while changed little in the tar with the increase of pyrolysis temperature. (3) The energy and efficiency were calculated for pyrolysis of Shenmu bituminous coal in moving bed reactor with internals based on the experimental data from the 1000 t/a pilot plant and the design parameters for 200 kt/a demonstration plant. The result showed that 89.7 m3 pyrolysis gas would be combusted to provide the energy that 1 t coal pyrolysis needed, and the efficiency of Shenmu coal pyrolysis was 93.7% at 1000 ℃. 

语种中文
文献类型学位论文
条目标识符http://ir.ipe.ac.cn/handle/122111/22944
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石振. 煤热解产物分布及主要元素的迁移规律研究[D]. 北京. 中国科学院研究生院,2016.
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