【作者】 王贵军；

【导师】 罗永浩； 陆方；

【作者基本信息】 上海交通大学 ， 热能工程， 2010， 硕士

【摘要】 随着我国经济的持续快速发展,能源需求量日益增加;但是化石能源的广泛应用造成了日益严重的环境问题,而且其储量也有限。生物质能是CO2中性的可再生清洁能源,每年的产量巨大。然而生物质的利用存在着收集运输和储存成本高,磨粉能耗大等缺点。生物质烘焙预处理是一种能够显著改善生物质磨粉性能,提高生物质能量密度和储存性能,降低生物质运输储存成本的合理有效的方法。生物质与煤混合气化不仅有利于生物质的规模化利用,而且更够改善煤的气化特性。本文首先对生物质能源的特点、转化利用技术、生物质能利用的情况和政策,生物质利用的预处理方式以及混合气化的研究情况进行了总结。接着对农业生物质秸秆进行了烘焙预处理研究。在固定床实验台进行了四种典型的农业生物质秸秆N2氛围下的烘焙预处理试验,终温为200℃、250℃、300℃,加热时间均为30min。热解得到的固体半焦产物能量密度显著提高,对比原始的生物质其可磨性得到明显改善,并且具有了疏水性,便于储存运输和磨粉用于气流床气化。热解气体产物以CO2、CO为主还有少量CH4,并对气体的产生进行了动力学分析。液体产物主要是水分和焦油。随着热解温度升高,液体产物和气体产物量均增加,固体焦的质量产率和能量产率都下降。然后分析烘焙预处理的可行性。测量了烘焙预处理产生半焦的热值,求得了预处理过程的能量产率。虽然半焦的热值随烘焙温度的升高而增加,但是其能量产率却下降。生物质在烘焙过程中的吸热量很小,可以有自身的部分燃烧来提供。对250℃,30min条件下的烘焙过程;从固体能量产率、原始生物质和烘焙的固体产物运输储存成本、研磨能耗对比等方面衡量了烘焙预处理的可行性。发现烘焙预处理技术相对未经预处理的有竞争力。最后研究了生物质半焦与煤在CO2作为气化剂的气化特性。分别对生物质半焦、神府煤、以及两者按质量1:1的混合物在耐驰热重上以温速率为20℃/min从35℃升温至1200℃进行了气化实验。生物质半焦单独气化反应性比神府煤要好。混合气化反应均好于单独燃料的气化反应。混合气化反应性不仅与生物质种类有关,而且与热解预处理温度有关。混合气化不仅提高了反应性,而且使得最大失重速率发生的温度降低了。大部分的混合气化最终剩余物百分比也降低,最终反应温度低于神府煤。说明协同作用使得混合燃料气化发生在更低温度,且气化速率增加使得气化过程缩短。更多还原

【Abstract】 As China’s sustained and rapid economic development, energy demand is increasing. But extensive use of fossil fuels caused serious environmental problems, and its reserves are limited. Biomass is CO2 neutral and renewable clean energy, the annual products is very huge. However agricultural biomass have some drawbacks such as high moisture content, low energy density and widely distributed, as a result the cost of transport and store are high. Moreover, the raw biomass is poor grindability so that it is difficult to be used in pulverised boiler or entrained flow gasifier. Torrefaction is a mild pyrolysis process carried out at temperature ranging from 200℃to 300℃to dealing with those problems. Co-gasification of biomass and coal is not only beneficial to large-scale use of biomass, but also to improve the characteristics of coal gasification.Four samples were heated in a fix-bed at moderate temperature (200,250 and 300℃) under a N2 atmosphere for 30 minutes. The biomass chars after torrefied have a higher energy density and an improvement in the grindability characteristics compared with raw biomass and even have hydrophobic characteristics. The volatiles consist of a condensable fraction and a non-condensable fraction. The former mainly contain water and tar (organic products mainly acetic acid ). The non-condensable products are typically comprised of CO2, CO and a small amount of CH4, even trace of H2. The volatiles increased with the increasing of the torrefaction temperature, on the contrary the solid yield and energy yield all decreased. However, the grindability and energy density of the biomass char have a great improvement. A kinetic study on the generation of main non-condensable gases was accomplished.Then the feasibility analysis of torrefaction preprocessing was studied. The heating value of semi-char and energy yields of torrefaction were measured. Although the heating value of semi-char rises with torrefaction temperature increased, but the energy yield decline. Heat required of torretied biomass is very small, can be providing by a small part of biomass combustion. From the solid energy yields, the transport and storage costs, grinding energy consumption, untreated biomass and the solid products under the torrefaction conditions of 250℃, 30min were compared. Found that the pretreatment technology has competitive advantage.Finally using TGA,reactivity of biomass semi-char,coal and their blends in CO2 atmosphere was processed. The results showed that, for four biomass chars,the reactivity in CO2 atmosphere has same trend,the reactivity increases with carbon conversion. Different from reactivity of coal in CO2 atmosphere. Co-gasification reactivity is better than separate fuel gasification. Gasification reactivity related with the types of biomass and torrefaction temperature. Note the synergy makes the mixed fuel gasification occurs at a lower temperature, and the gasification rate of increase makes gasification process shorten. This result may be due to higher alkali metal content in biomass char than that in coal.更多还原