基于高溫還原法和UV-DOAS的煙氣總汞在線監(jiān)測(cè)技術(shù)研究
發(fā)布時(shí)間：2018-10-08 16:14
【摘要】：我國(guó)是燃煤大國(guó),燃煤電廠消費(fèi)占多數(shù),而電力供應(yīng)的能源以煤炭為主的現(xiàn)狀短時(shí)間不會(huì)改變,燃煤電廠在給人們帶來(lái)經(jīng)濟(jì)效益的同時(shí),也帶來(lái)了嚴(yán)重的環(huán)境污染問(wèn)題。煙氣汞的排放對(duì)環(huán)境及人體具有很大的危害,近年來(lái)對(duì)煙氣汞的關(guān)注也越來(lái)越多,2012年最新實(shí)施的《火電廠大氣污染排放標(biāo)準(zhǔn)》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(duì)汞的排放越來(lái)越嚴(yán)格。煙氣汞排放主要是Hg0和2(10)Hg,以光學(xué)為基礎(chǔ)的在線監(jiān)測(cè)方法只能針對(duì)原子汞,因此2(10)Hg需要轉(zhuǎn)變成0Hg后才能實(shí)現(xiàn)在線監(jiān)測(cè)。本文利用高溫還原法結(jié)合紫外差分光譜法實(shí)現(xiàn)煙氣總汞的在線監(jiān)測(cè)。制備了高溫加熱系統(tǒng),搭建了元素汞標(biāo)氣發(fā)生系統(tǒng)、二價(jià)汞標(biāo)氣發(fā)生系統(tǒng)和模擬煙氣汞監(jiān)測(cè)系統(tǒng),并對(duì)各個(gè)系統(tǒng)的組成部分,包括高溫加熱系統(tǒng)、標(biāo)氣制備系統(tǒng)、光學(xué)系統(tǒng)、數(shù)據(jù)采集及處理系統(tǒng)等進(jìn)行分析介紹。采用低壓汞燈為光源,結(jié)合單色儀對(duì)汞進(jìn)行測(cè)量,將汞的測(cè)量光譜范圍確定為253.4-253.9nm。以零價(jià)汞為準(zhǔn),比較了高溫情況和常溫狀態(tài)下汞監(jiān)測(cè)情況,高溫情況下汞的誤差為8.7%,驗(yàn)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(duì)汞測(cè)量光譜進(jìn)行處理,對(duì)單組份零價(jià)汞和二價(jià)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(cè)實(shí)驗(yàn)時(shí),比較零價(jià)汞與二價(jià)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(cè)量,兩者的濃度反演遺傳算法接近實(shí)際值,但積分面積法波動(dòng)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(duì)汞監(jiān)測(cè)的影響實(shí)驗(yàn)發(fā)現(xiàn),在實(shí)驗(yàn)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(guò)大過(guò)小的汞濃度都會(huì)致使測(cè)量低于真實(shí)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(hào)：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(hào)：2257414
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