基于高溫還原法和UV-DOAS的煙氣總汞在線監(jiān)測技術(shù)研究
發(fā)布時間：2018-10-08 16:14
【摘要】：我國是燃煤大國,燃煤電廠消費占多數(shù),而電力供應(yīng)的能源以煤炭為主的現(xiàn)狀短時間不會改變,燃煤電廠在給人們帶來經(jīng)濟效益的同時,也帶來了嚴重的環(huán)境污染問題。煙氣汞的排放對環(huán)境及人體具有很大的危害,近年來對煙氣汞的關(guān)注也越來越多,2012年最新實施的《火電廠大氣污染排放標準》燃煤鍋爐大氣污染排放濃度限值規(guī)定:汞及其汞的化合物的排放濃度限值為0.033mmg,對汞的排放越來越嚴格。煙氣汞排放主要是Hg0和2(10)Hg,以光學為基礎(chǔ)的在線監(jiān)測方法只能針對原子汞,因此2(10)Hg需要轉(zhuǎn)變成0Hg后才能實現(xiàn)在線監(jiān)測。本文利用高溫還原法結(jié)合紫外差分光譜法實現(xiàn)煙氣總汞的在線監(jiān)測。制備了高溫加熱系統(tǒng),搭建了元素汞標氣發(fā)生系統(tǒng)、二價汞標氣發(fā)生系統(tǒng)和模擬煙氣汞監(jiān)測系統(tǒng),并對各個系統(tǒng)的組成部分,包括高溫加熱系統(tǒng)、標氣制備系統(tǒng)、光學系統(tǒng)、數(shù)據(jù)采集及處理系統(tǒng)等進行分析介紹。采用低壓汞燈為光源,結(jié)合單色儀對汞進行測量,將汞的測量光譜范圍確定為253.4-253.9nm。以零價汞為準,比較了高溫情況和常溫狀態(tài)下汞監(jiān)測情況,高溫情況下汞的誤差為8.7%,驗證了高溫系統(tǒng)的可行性。在傳統(tǒng)DOAS法的基礎(chǔ)上,應(yīng)用傅里葉變換法、遺傳算法和積分面積法對汞測量光譜進行處理,對單組份零價汞和二價汞濃度反演分析,其中積分面積法濃度反演結(jié)果的誤差最小,最小誤差為-1.3%,且誤差水平比另外三種算法更穩(wěn)定。模擬煙氣總汞在線監(jiān)測實驗時,比較零價汞與二價汞添加的先后順序,結(jié)果表明先后順序并沒有影響總汞的測量,兩者的濃度反演遺傳算法接近實際值,但積分面積法波動性更小,誤差控制在5%以內(nèi);傅里葉變換發(fā)和傳統(tǒng)DOAS法誤差偏離較大,不適合低濃度汞的反演。分析不同冷凝溫度對汞監(jiān)測的影響實驗發(fā)現(xiàn),在實驗室環(huán)境下,冷凝溫度設(shè)置在22-25℃內(nèi),其反演誤差最小,過大過小的汞濃度都會致使測量低于真實值。
[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，
本文編號：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，
本文編號：2257414
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