基于高温还原法和UV-DOAS的烟气总汞在线监测技术研究
发布时间：2018-10-08 16:14
【摘要】：我国是燃煤大国,燃煤电厂消费占多数,而电力供应的能源以煤炭为主的现状短时间不会改变,燃煤电厂在给人们带来经济效益的同时,也带来了严重的环境污染问题。烟气汞的排放对环境及人体具有很大的危害,近年来对烟气汞的关注也越来越多,2012年最新实施的《火电厂大气污染排放标准》燃煤锅炉大气污染排放浓度限值规定:汞及其汞的化合物的排放浓度限值为0.033mmg,对汞的排放越来越严格。烟气汞排放主要是Hg0和2(10)Hg,以光学为基础的在线监测方法只能针对原子汞,因此2(10)Hg需要转变成0Hg后才能实现在线监测。本文利用高温还原法结合紫外差分光谱法实现烟气总汞的在线监测。制备了高温加热系统,搭建了元素汞标气发生系统、二价汞标气发生系统和模拟烟气汞监测系统,并对各个系统的组成部分,包括高温加热系统、标气制备系统、光学系统、数据采集及处理系统等进行分析介绍。采用低压汞灯为光源,结合单色仪对汞进行测量,将汞的测量光谱范围确定为253.4-253.9nm。以零价汞为准,比较了高温情况和常温状态下汞监测情况,高温情况下汞的误差为8.7%,验证了高温系统的可行性。在传统DOAS法的基础上,应用傅里叶变换法、遗传算法和积分面积法对汞测量光谱进行处理,对单组份零价汞和二价汞浓度反演分析,其中积分面积法浓度反演结果的误差最小,最小误差为-1.3%,且误差水平比另外三种算法更稳定。模拟烟气总汞在线监测实验时,比较零价汞与二价汞添加的先后顺序,结果表明先后顺序并没有影响总汞的测量,两者的浓度反演遗传算法接近实际值,但积分面积法波动性更小,误差控制在5%以内;傅里叶变换发和传统DOAS法误差偏离较大,不适合低浓度汞的反演。分析不同冷凝温度对汞监测的影响实验发现,在实验室环境下,冷凝温度设置在22-25℃内,其反演误差最小,过大过小的汞浓度都会致使测量低于真实值。
[Abstract]:China is a big coal-fired country, and the consumption of coal-fired power plants accounts for the majority, and the current situation that coal is the main source of power supply will not change for a short time. Coal-fired power plants not only bring economic benefits to people, but also bring serious environmental pollution problems. The emission of mercury from flue gas is harmful to the environment and human body. In recent years, more and more attention has been paid to mercury in flue gas. In 2012, the latest implementation of the "Standard of Atmospheric pollution Emission from Thermal Power plants" stipulates that the limit of atmospheric pollution emission from coal-fired boilers is 0.033 mmg for mercury and its compounds. Mercury emissions are becoming more and more stringent. Mercury emissions from flue gas are mainly measured by Hg0 and 2 (10) Hg, optical-based on-line monitoring methods only for atomic mercury, so 2 (10) Hg needs to be transformed into 0Hg to realize on-line monitoring. In this paper, the method of high temperature reduction and UV differential spectroscopy is used to realize the on-line monitoring of total mercury in flue gas. The high temperature heating system, elemental mercury standard gas generation system, bivalent mercury standard gas generation system and simulated flue gas mercury monitoring system were prepared, and the components of each system, including high temperature heating system, standard gas preparation system, optical system, were established. Data acquisition and processing system is introduced. The low pressure mercury lamp was used as the light source and the monochromator was used to measure mercury. The measuring spectrum range of mercury was determined to be 253.4-253.9 nm. The mercury monitoring at high temperature is compared with that under normal temperature. The error of mercury at high temperature is 8.7, which verifies the feasibility of the high temperature system. On the basis of the traditional DOAS method, Fourier transform method, genetic algorithm and integral area method are used to deal with the mercury measurement spectrum, and the single-component zero-valence mercury and divalent mercury concentration inversion analysis is carried out, in which the integral area method has the smallest error in the concentration inversion results. The minimum error is -1.3 and the error level is more stable than the other three algorithms. When simulating the on-line monitoring experiment of total mercury in flue gas, the sequence of zero valence mercury and divalent mercury addition is compared. The results show that the order does not affect the measurement of total mercury, and the concentration inversion genetic algorithm is close to the actual value. However, the integral area method is less volatile and the error is less than 5%, and the Fourier transform method and the traditional DOAS method deviate greatly, so it is not suitable for the inversion of low concentration mercury. By analyzing the effect of different condensation temperature on mercury monitoring, it is found that in laboratory environment, the inversion error is minimum when the condensation temperature is set at 22-25 鈩，
本文编号：2257414
[Abstract]:China is a big coal-fired country, and the consumption of coal-fired power plants accounts for the majority, and the current situation that coal is the main source of power supply will not change for a short time. Coal-fired power plants not only bring economic benefits to people, but also bring serious environmental pollution problems. The emission of mercury from flue gas is harmful to the environment and human body. In recent years, more and more attention has been paid to mercury in flue gas. In 2012, the latest implementation of the "Standard of Atmospheric pollution Emission from Thermal Power plants" stipulates that the limit of atmospheric pollution emission from coal-fired boilers is 0.033 mmg for mercury and its compounds. Mercury emissions are becoming more and more stringent. Mercury emissions from flue gas are mainly measured by Hg0 and 2 (10) Hg, optical-based on-line monitoring methods only for atomic mercury, so 2 (10) Hg needs to be transformed into 0Hg to realize on-line monitoring. In this paper, the method of high temperature reduction and UV differential spectroscopy is used to realize the on-line monitoring of total mercury in flue gas. The high temperature heating system, elemental mercury standard gas generation system, bivalent mercury standard gas generation system and simulated flue gas mercury monitoring system were prepared, and the components of each system, including high temperature heating system, standard gas preparation system, optical system, were established. Data acquisition and processing system is introduced. The low pressure mercury lamp was used as the light source and the monochromator was used to measure mercury. The measuring spectrum range of mercury was determined to be 253.4-253.9 nm. The mercury monitoring at high temperature is compared with that under normal temperature. The error of mercury at high temperature is 8.7, which verifies the feasibility of the high temperature system. On the basis of the traditional DOAS method, Fourier transform method, genetic algorithm and integral area method are used to deal with the mercury measurement spectrum, and the single-component zero-valence mercury and divalent mercury concentration inversion analysis is carried out, in which the integral area method has the smallest error in the concentration inversion results. The minimum error is -1.3 and the error level is more stable than the other three algorithms. When simulating the on-line monitoring experiment of total mercury in flue gas, the sequence of zero valence mercury and divalent mercury addition is compared. The results show that the order does not affect the measurement of total mercury, and the concentration inversion genetic algorithm is close to the actual value. However, the integral area method is less volatile and the error is less than 5%, and the Fourier transform method and the traditional DOAS method deviate greatly, so it is not suitable for the inversion of low concentration mercury. By analyzing the effect of different condensation temperature on mercury monitoring, it is found that in laboratory environment, the inversion error is minimum when the condensation temperature is set at 22-25 鈩，
本文编号：2257414
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