煤热解气氛下S、Hg协同反应的试验研究
发布时间：2019-05-19 00:07
【摘要】：目前,我国燃煤主要污染物排放标准日趋严格,近年来国家大力推进实施超低排放控制技术,致使主要污染物末端治理工艺更加复杂。燃煤烟气中汞含量少、浓度低,到目前为止我国尚没有商业化并广泛投入应用的燃煤电站经济、高效的脱汞技术。大气污染控制已经上升为国家战略,针对燃煤烟气中控制汞排放技术,要从源头和过程排放控制相结合出发,实现经济、高效、协同控制。研究表明,煤热解脱汞工艺是燃烧前期脱汞的可行方案。燃烧前热处理生成的烟气中的汞浓度会大大提高,而且烟气处理量大大减少。同时,在燃烧前热处理过程中,对煤中的S也能得到一定程度上的脱除,实现协同控制。另一方面,前期研究发现,高硫煤中硫、汞赋存形态存在正相关关系,并且脱汞技术中中硫、汞存在相关关系。煤中汞在热解或燃烧过程中的主要形态为Hg0,同时,煤热解过程中含硫的主要形式为H2S,而煤燃烧后的烟气中硫元素的绝大部分存在形式为S02。H23与S02在适当条件下发生化学反应产生硫单质,单质硫与汞蒸气发生反应生成稳定的化合物HgS,从而实现脱除汞的目的。基于此,山东大学提出高硫煤热解、燃烧过程中硫、汞协同脱除的方法。首先通过控制煤中硫元素的热解和燃烧产物H2S、02、S02之间发生化学变化形成硫单质,然后硫单质与热解出的Hg反应生成稳定的化合物HgS,最后从热解气中排出,实现煤中硫、汞元素在燃烧前期的协同脱除。本文搭建了单质硫与汞蒸气(S-Hg)反应试验系统和模拟气体H2S-S02-Hg联合反应试验系统。首先试验研究了非催化与催化条件下S、Hg反应特征和温度、气氛种类对该反应进行程度的影响。研究发现S与Hg在常温下即可发生反应,但受到温度的限制,汞的脱除效率较低。当温度升高时,S与Hg的反应速度增大。催化条件下,反应温度为100℃时,汞的脱除率为76.8%。添加铝基催化剂可以显著地促进S-Hg反应的进行,大幅提升汞的脱除率。在非催化条件下,氧气能够提升气相单质汞的脱除效果,但提升比例不大。催化条件下随着氧气体积分数的增加S-Hg反应效率显著提升。C02气体对S-Hg反应没有影响。S02作为硫化氢与二氧化硫归中反应重要的反应物对S-Hg反应作用甚微,在实际中不作为主要影响因素来考虑。其次试验研究了非催化条件下H2S-S02-Hg联合反应的脱汞效果和催化条件下H2S-S02-Hg联合反应特征及多因素对该反应进行程度的影响。研究发现,非催化条件下联合反应中单质汞脱除率整体较低,脱汞效果差,在实际生产中不宜应用。催化条件下反应温度为200℃时,汞的脱除效率为82%,H2S-SO2反应率达到80%,温度过高并不会提升联合反应的进行程度。反应时间延长,联合反应更加充分,但反应时间延长至3s时,联合反应效率提升不明显。联合反应H2S-S02反应率受摩尔比的影响比较大,汞的脱除效率也受到影响,但变化程度没有H2S-S02反应大。摩尔比为2时,联合反应效率最高。C02对联合反应不存在影响。随着模拟气氛中02浓度的提升,汞的去除效率呈现上升趋向,H2S-S02反应率呈下降趋势,在实际应用中要综合考虑氧气的体积分数对两个分反应的影响。随着联合反应入口单质汞浓度的提升,联合反应汞的脱除能力下降。
[Abstract]:At present, the emission standard of coal-fired main pollutants in China is becoming more and more strict, and in recent years, the state has vigorously promoted the implementation of the ultra-low emission control technology, leading to the more complicated end-treatment process of the main pollutants. The mercury content in the coal-fired flue gas is low, the concentration is low, so far, the coal-fired power station has not been commercialized and has been widely applied to the economic and high-efficiency mercury-removing technology of the coal-fired power station. The control of air pollution has risen to the national strategy, and the control of the mercury discharge technology in the coal-fired flue gas should be combined with the control of the source and the process to realize the economic, efficient and cooperative control. The study shows that the coal-heat-releasing mercury process is a feasible scheme for mercury removal in the early stage of combustion. The mercury concentration in the flue gas generated by the heat treatment before combustion can be greatly improved, and the treatment capacity of the flue gas is greatly reduced. At the same time, the S in the coal can be removed to a certain extent during the pre-combustion heat treatment process, and the synergistic control can be realized. On the other hand, in the early stage, there is a positive correlation between sulfur and mercury in the high-sulfur coal, and there is a correlation between the sulfur and the mercury in the mercury-removing technology. The main form of the mercury in the process of pyrolysis or combustion is Hg0, at the same time, the main form of sulfur in the coal pyrolysis process is H2S, and most of the sulfur elements in the flue gas after coal combustion is in the form of S02. H23 and S02 generate sulfur simple substance by chemical reaction under the appropriate conditions, The elemental sulfur reacts with the mercury vapor to form a stable compound HgS, thereby achieving the purpose of removing mercury. On the basis of this, Shandong University proposed a method of co-removal of sulfur and mercury in the process of pyrolysis and combustion of high-sulfur coal. firstly, the sulfur element is formed by controlling the chemical change between the pyrolysis of the sulfur element in the coal and the H2S,02 and S02 of the combustion products, The co-removal of the mercury element in the pre-combustion stage. The reaction test system of elemental sulfur and mercury vapor (S-Hg) and simulated gas H2S-S02-Hg are set up in this paper. The reaction characteristics and temperature of S, Hg under non-catalytic and catalytic conditions and the influence of the kind of atmosphere on the reaction were studied. It is found that S and Hg can react at normal temperature, but are limited by temperature, and the removal efficiency of mercury is low. When the temperature is increased, the reaction rate of S and Hg is increased. Under the catalysis condition, the removal rate of mercury was 76.8% when the reaction temperature was 100 鈩，
本文编号：2480455
[Abstract]:At present, the emission standard of coal-fired main pollutants in China is becoming more and more strict, and in recent years, the state has vigorously promoted the implementation of the ultra-low emission control technology, leading to the more complicated end-treatment process of the main pollutants. The mercury content in the coal-fired flue gas is low, the concentration is low, so far, the coal-fired power station has not been commercialized and has been widely applied to the economic and high-efficiency mercury-removing technology of the coal-fired power station. The control of air pollution has risen to the national strategy, and the control of the mercury discharge technology in the coal-fired flue gas should be combined with the control of the source and the process to realize the economic, efficient and cooperative control. The study shows that the coal-heat-releasing mercury process is a feasible scheme for mercury removal in the early stage of combustion. The mercury concentration in the flue gas generated by the heat treatment before combustion can be greatly improved, and the treatment capacity of the flue gas is greatly reduced. At the same time, the S in the coal can be removed to a certain extent during the pre-combustion heat treatment process, and the synergistic control can be realized. On the other hand, in the early stage, there is a positive correlation between sulfur and mercury in the high-sulfur coal, and there is a correlation between the sulfur and the mercury in the mercury-removing technology. The main form of the mercury in the process of pyrolysis or combustion is Hg0, at the same time, the main form of sulfur in the coal pyrolysis process is H2S, and most of the sulfur elements in the flue gas after coal combustion is in the form of S02. H23 and S02 generate sulfur simple substance by chemical reaction under the appropriate conditions, The elemental sulfur reacts with the mercury vapor to form a stable compound HgS, thereby achieving the purpose of removing mercury. On the basis of this, Shandong University proposed a method of co-removal of sulfur and mercury in the process of pyrolysis and combustion of high-sulfur coal. firstly, the sulfur element is formed by controlling the chemical change between the pyrolysis of the sulfur element in the coal and the H2S,02 and S02 of the combustion products, The co-removal of the mercury element in the pre-combustion stage. The reaction test system of elemental sulfur and mercury vapor (S-Hg) and simulated gas H2S-S02-Hg are set up in this paper. The reaction characteristics and temperature of S, Hg under non-catalytic and catalytic conditions and the influence of the kind of atmosphere on the reaction were studied. It is found that S and Hg can react at normal temperature, but are limited by temperature, and the removal efficiency of mercury is low. When the temperature is increased, the reaction rate of S and Hg is increased. Under the catalysis condition, the removal rate of mercury was 76.8% when the reaction temperature was 100 鈩，
本文编号：2480455
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