摘 要:煤炭在燃烧过程中会产生大量的NOx和SO2，而生物质燃料作为一种可再生能源，具有低硫、低氮、零CO2净排放的特点。采用生物质热解技术获得的生物质焦，可广泛应用于烟气脱硫脱氮领域，实现降低污染物排放的目的。生物质焦的结构特性对于其脱硫脱氮性能具有重要一下，因此，开展生物质焦及其活化特性的研究具有重要意义。本文对五种生物质原料及其热解焦和生物质活化焦进行了实验研究，得到以下结果：
生物质随着热解和活化程度的不断加深，其水分的含量呈减小的趋势，灰分的含量呈增加的趋势，挥发分含量不断减小，达到一定程度后趋于不变。不同生物质的工业分析都呈现这一规律。不同生物质的得焦率不同，数值相差较大，得焦率随着热解和活化程度的加深而显著下降。
生物质热解后，C元素含量增加，其含量随着热解温度的升高而减小，O元素含量减小，其含量随着热解温度的升高而降低，H元素的含量减小，变化不大。水蒸气活化焦的O元素含量减小且其含量随着热解温度的升高而降低，C元素和H元素含量变化较小。
热解使生物质表面的形貌结构均发生了显著的变化。随着热解温度的升高，表面的热分解程度显著明显。生物质在热解过程造成了不同程度的破裂与分解，表层结构破裂后暴露出内部丰富的大量管型或孔型组织结构。水蒸气活化使得生物质焦的表面结构进一步发生变化，部分出现内部外部结构断裂和坍塌的现象。
生物质焦的比表面积与孔隙结构的参数在热解过程中显著增加，水蒸气活化后，其参数增加更为显著；快速热解制得的生物质焦的相关孔隙结构参数大于慢速热解。
本文还进行了生物质脱硫脱氮脱汞系统的设计、安装和调试工作，脱硫脱氮脱汞系统由混气系统、脱硫脱氮脱汞反应系统和测量系统组成。
关键词：生物质；生物质焦；水蒸气活化；基本特征分析；脱硫脱氮脱汞
Abstract:A large amount of NOx and SO2 emissions will generate during coal combustion, and cause serious environment pollution. Biomass is concerned as a renewable energy, with the characteristics of low sulfur, low nitrogen, no emission of CO2. Biomass char prepared by pyrolysis technology can be used as sorbents of desulfurization and denitrification, and achieve NOx and SO2. Emissions control. The basic characteristics of biomass chars have a significant on their performance of desulfurization and denitrification. In this paper, characteristics of five kinds of biomass (including straw, cotton stalk, corn stalks, rice straw, rice husk) and its activated biomass chars are experimentally studied, the results are listed as follows:
With the pyrolysis and activation process preceding, the moisture content decreased, the content of ash increased, and the volatile content keep decreasing to a certain extent tends to remain unchanged. Proximate analyses of different biomass have shown the same law. Different biomass have different biomass char yield, the biomass char yield decreased significantly with the deeping of pyrolysis and activation process.
After pyrolysis process, C element content increased, but the C element content decreases as the pyrolysis temperature increases, O element content decreases and O elements decreases as the pyrolysis temperature decreases, H elements content decreases, and the pyrolysis temperature has little influence on it. O element content of activated biomass char decreases and it decreases as the pyrolysis temperature decreases, C elements and H elements are in little change.
The specific surface area and the parameters of the pore structure of the biomass chars increased greatly during pyrolysis. After the steam activation, the parameters increased more significantly. With the activation of the steam, the internal hole structure of the biomass char will be optimized, massive oil tar will be removed, so more closed holes will open. At the same time, the microporous number will increase significantly, the specific surface area will increase too. It will provide better structure parameters for the adsorption process.
At the same time, a facility of desulphurization, denitrification and mercury removal with biomass chars, which includes simulated gas preparation system, furnace, adsorbent, and measurement system, were designed and established.
Key Words: Biomass; Biomass char; steam activation; basic characteristics; desulfurization, denitrification and the removal of mercury
