煤粉在加压富氧条件下的燃烧特性研究

发布时间：2018-05-08 17:19

本文选题：煤粉富氧燃烧 + 加压　；参考：《北京交通大学》2015年硕士论文

【摘要】：富氧燃烧技术作为一种新型环境友好的燃煤方式,其原理是利用空气分离获得的高纯氧和部分锅炉排烟(主要是C02和H20)混合而成的混合气代替空气作为燃烧时的氧化剂,从而使燃烧排烟中的C02浓度大幅提高,高浓度的CO2有利于进行分离和贮存,是近些年来较为有希望的燃煤近零排放技术之一。而在常规富氧燃烧原理的基础上提出的加压富氧燃烧概念,具有明显的技术和经济优势。目前国内外对于加压富氧燃烧技术的研究主要集中在数值模拟及通过热重实验研究富氧燃烧方式下煤粉的燃烧与燃尽特性,因此,通过实验研究煤粉在加压富氧条件下的燃烧过程,探究压力对煤粉燃烧特性的影响规律,将有助于煤粉加压富氧燃烧技术的健康发展。本文主要采用实验研究和理论分析的方法对下述问题开展了重点研究。首先使用Aspen Plus流程模拟软件对煤粉在加压富氧条件下的燃烧过程进行了热力学分析研究,研究了压力对燃烧生成物的影响。之后完成了加压固定床反应器实验装置的设计、搭建及调试：对实验零部件进行了测试并对实验装置进行了总体安装、检测和试运行。确保所搭建的实验装置可以安全、可靠地运行。最后在搭建好的加压固定床反应器系统上开展了加压富氧条件下煤粉燃烧实验,并就压力对煤粉富氧燃烧特性及烟气成份的影响进行了分析。结果表明：与常压条件相比,煤粉在O230%/CO270%气氛加压条件下燃烧时,着火时间随压力的增加而下降,且下降幅度逐渐减小,2MPa及5MPa工况着火较为迅速；燃尽时间随压力的增加而增加,5MPa工况燃尽时间最长,而3MPa工况下煤粉燃尽时间与常压工况下煤粉富氧燃烧燃尽时间接近；燃烧最高温度随压力的增加而升高,在2MPa时达到最高;不同压力工况下煤粉燃烧速率随压力变化表现出较大差异。不同压力工况下烟气中氧气浓度变化都经历先降后升的过程,其中在0.1MPa、4MPa、5MPa工况下O2浓度在反应3分钟时达到最小值：CO浓度随压力的变化都随时间经历了先升后降的过程。相对于常压,加压工况下CO浓度显著下降；各工况下CO2浓度的变化趋势比较类似,在整个过程中都随时间经历了一定的波动,在各个时间点,基本随压力的增加而升高。
[Abstract]:As a new kind of environment-friendly coal burning technology, oxygen-enriched combustion technology is based on the mixture of high purity oxygen and partial boiler exhaust gas (mainly CO2 and H20), which is obtained by air separation instead of air as oxidant in combustion. Therefore, the CO2 concentration in combustion and exhaust smoke is greatly increased, and the high concentration of CO2 is favorable for separation and storage. It is one of the promising near-zero emission technologies for coal combustion in recent years. On the basis of the conventional oxygen-enriched combustion principle, the concept of pressurized oxygen-enriched combustion has obvious technical and economic advantages. At present, the research on pressurized oxygen-enriched combustion technology at home and abroad is mainly focused on numerical simulation and thermogravimetric experiments to study the combustion and burnout characteristics of pulverized coal under oxygen-enriched combustion mode. The experimental study on the combustion process of pulverized coal under the condition of pressurized oxygen enrichment and the study of the influence of pressure on the combustion characteristics of pulverized coal will contribute to the healthy development of pressurized oxygen-enriched combustion technology of pulverized coal. This paper focuses on the following problems by means of experimental research and theoretical analysis. Firstly, the thermodynamic analysis of combustion process of pulverized coal under pressurized and oxygen-enriched conditions was carried out by using Aspen Plus process simulation software, and the effect of pressure on combustion product was studied. After that, the design, construction and debugging of the experimental device of pressurized fixed-bed reactor are completed. The experimental parts are tested, and the experimental device is installed, tested and tested. Make sure that the experimental device can run safely and reliably. Finally, the experiments of pulverized coal combustion under the condition of pressurized oxygen enrichment were carried out in a pressurized fixed-bed reactor system, and the effects of pressure on the combustion characteristics of pulverized coal and the composition of flue gas were analyzed. The results show that the ignition time of pulverized coal decreases with the increase of the pressure, and decreases gradually with the increase of pressure, and decreases gradually under the condition of O _ 230 / CO _ (270)% under atmospheric pressure, and the ignition time of pulverized coal under the condition of O _ (230) / CO _ (270)% atmosphere is faster than that under normal pressure. The burnout time increases with the increase of pressure at 5 MPA, but the burnout time of pulverized coal under 3MPa condition is close to that of pulverized coal combustion under atmospheric pressure, and the maximum combustion temperature increases with the increase of pressure, and reaches the highest at 2MPa. The combustion rate of pulverized coal varies greatly with the pressure under different pressure conditions. The change of oxygen concentration in flue gas under different pressure conditions all experienced the process of first decreasing and then rising. In the condition of 0.1 MPA ~ 4 MPA, O _ 2 concentration reached the minimum value in 3 minutes of reaction, and the change of oxygen concentration with pressure experienced the process of rising first and then decreasing with time. Compared with atmospheric pressure, CO concentration decreased significantly under pressurized conditions, and the variation trend of CO2 concentration was similar under each condition, which fluctuated with time during the whole process, and increased with the increase of pressure at each time point.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TK16

【参考文献】