Energy cascade release of coal in different oxidation environment

doi:10.11949/j.issn.0438-1157.20161011

Abstract

Abstract:

Introducing the supercritical water oxidation technology into the clean combustion of coal to solve serious problems of low combustion efficiency and pollution of traditional coal combustion, this paper analyzed the reaction characteristics of coal in two different oxidizing atmosphere of air and supercritical water. Furthermore, based on different reaction paths and by means of the energy utilization diagram methodology, the energy conversion characteristics of coal oxidizing in different atmosphere were analyzed, and the new mechanism of energy release of coal oxidizing in aqueous phase was revealed. Finally, the exergy analysis of practical application process of two kinds of oxidation was carried out. The results showed that the aqueous phase oxidation of coal reduced chemistry exergy level from 1 to 0.83, this is to say, the grade difference between chemistry energy and heat source was decreased, indicating that it reduced the irreversible loss of the conversion process from chemical energy into physical energy, exergy losses decreased about 6.04% and thermal exergy increased by 5.25%. The exergy efficiency of coal oxidation in supercritical water was as high as 80.1% about 24.2% higher than oxidation in air, and thus it can greatly improve the exergy efficiency.

Key words: coal, supercritical water oxidation, energy utilization diagram methodology, cascade release of chemical energy

摘要：

针对传统煤燃烧能量利用效率低、污染严重等问题，将超临界水氧化技术应用于煤的清洁燃烧过程，分析了煤在空气和超临界水两种不同的氧化氛围中的反应特性。进而，基于不同的反应路径，利用图像(火用)分析法，剖析了煤在两种氧化氛围中的能量转换特点，揭示了煤在水相氧化氛围中的能量释放新机理，最后对煤在超临界水氧化反应器和传统锅炉中的实际过程进行了(火用)分析。结果表明，水相氧化将煤的化学能品位从1降低到0.83，并且减小了煤的化学能品位与热源品位之差，从而降低了煤中化学能向物理能转变的不可逆损失，(火用)损失减少了6.04%，热(火用)增加了5.25%，而且水相氧化没有传热(火用)损失；运用(火用)分析理论，计算得到超临界水氧化反应器(火用)效率高达80.1%，高出传统锅炉(火用)效率24.2%。

关键词: 煤, 超临界水氧化, 图像(火用)分析, 化学能梯级释放

CLC Number:

YAN Qiuhui, HOU Yanwan, LUO Jieren, MIAO Haijun. Energy cascade release of coal in different oxidation environment[J]. CIESC Journal, 2016, 67(12): 5305-5310.

闫秋会, 侯彦万, 罗杰任, 苗海军. 煤在不同氧化氛围中的能量梯级释放[J]. 化工学报, 2016, 67(12): 5305-5310.

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