【摘要】：氮氧化物(NOx)是主要的大氣污染物之一,它不僅危害人和動物的健康,而且破壞生態(tài)環(huán)境。因?yàn)榛痣姀S是NOx的主要排放源,所以控制火電廠的NOx排放成為電力行業(yè)亟須解決的問題。與傳統(tǒng)NOx處理技術(shù)相比,低溫等離子體技術(shù)具有占地面積小、投資少、沒有二次污染等諸多優(yōu)點(diǎn)。目前對于等離子體廢氣處理領(lǐng)域大多采用的是板板電極,而本文研究的是常溫常壓環(huán)境下氣液兩相介質(zhì)阻擋放電反應(yīng)器產(chǎn)生的等離子體對NOx的去除效果。因?yàn)榱u基自由基(OH)在NOx去除過程中起著重要的作用,所以本文采用發(fā)射光譜法對低溫等離子體中活性基團(tuán)的類型及分布特征進(jìn)行了診斷分析,著重分析了液相成分、峰值電壓、電源頻率以及相對空氣濕度等對OH自由基的影響。主要結(jié)論有:OH自由基的光譜強(qiáng)度隨著NaOH溶液濃度、峰值電壓以及電源頻率的增加而增加;OH自由基的光譜強(qiáng)度隨著空氣相對濕度的增加先增加后減小。相同實(shí)驗(yàn)條件下,氣液兩相介質(zhì)阻擋放電的OH自由基光譜強(qiáng)度均高于傳統(tǒng)板板電極介質(zhì)阻擋放電,這將有利于NOx的去除。其次,本文研究了峰值電壓、氣體停留時間、NOx起始濃度、氣體流量、NaOH溶液濃度、煙氣相對濕度等條件對氣液兩相介質(zhì)阻擋放電的NOx去除率和NO2生成量的影響,并對比分析了在相同實(shí)驗(yàn)條件下氣液兩相介質(zhì)阻擋放電和板板電極的NOx去除率。研究發(fā)現(xiàn):NOx的去除率與峰值電壓呈正比,在峰值電壓為21kV時達(dá)到最大值;NOx的去除率隨著氣體停留時間的增長而提高,氣體停留大于30s時達(dá)到最大值;NOx去除率隨著NOx起始濃度、氣體流量的增加而減小;NOx去除率隨著NaOH濃度的增加而增加,在NaOH濃度為1.5mol/L是達(dá)到最大值;NOx去除率隨著煙氣相對濕度的增加呈現(xiàn)先增加而后大幅減小的趨勢,在相對濕度為50%時NOx去除率達(dá)到最大;液相為NaOH溶液的氣液兩相介質(zhì)阻擋放電的NO2生成量遠(yuǎn)遠(yuǎn)小于傳統(tǒng)板板電極。相同實(shí)驗(yàn)條件下,氣液兩相介質(zhì)阻擋放電對NOx的去除率明顯大于板板電極介質(zhì)阻擋放電。本文的研究成果為氣液兩相介質(zhì)阻擋放電在火電廠的脫硝應(yīng)用提供一定的理論依據(jù)和應(yīng)用價值。
[Abstract]:Nitrogen oxide (NOx) is one of the major atmospheric pollutants, which not only harms human and animal health, but also destroys the ecological environment. Because thermal power plant is the main emission source of NOx, controlling NOx emission of thermal power plant becomes an urgent problem to be solved in power industry. Compared with traditional NOx technology, low temperature plasma technology has many advantages, such as small area, less investment, no secondary pollution and so on. At present, plate electrode is used in plasma waste gas treatment, and the removal efficiency of NOx by plasma produced by gas-liquid two-phase dielectric barrier discharge reactor under normal temperature and atmospheric pressure is studied in this paper. Because hydroxyl radical (OH) plays an important role in the removal of NOx, the type and distribution of active groups in low temperature plasma were diagnosed and analyzed by means of emission spectrometry, and the composition of liquid phase was emphatically analyzed. The effect of peak voltage, power frequency and relative air humidity on OH free radical. The main conclusions are as follows: the spectral intensity of OH radical increases with the increase of the concentration of NaOH solution, the peak voltage and the frequency of power supply, and the spectral intensity of OH radical increases first and then decreases with the increase of air relative humidity. Under the same experimental conditions, the OH free radical spectral intensity of gas-liquid dielectric barrier discharge is higher than that of conventional plate electrode, which will be beneficial to the removal of NOx. Secondly, the effects of peak voltage, residence time of gas, initial concentration of NOx, flow rate of gas, concentration of NaOH solution and relative humidity of flue gas on NOx removal rate and NO2 production of gas-liquid two-phase dielectric barrier discharge are studied. The NOx removal rates of gas-liquid two-phase dielectric barrier discharge and plate electrode were compared and analyzed under the same experimental conditions. It is found that the removal rate of NOx is proportional to the peak voltage and reaches the maximum when the peak voltage is 21kV, and the removal rate of NOx increases with the increase of gas residence time, and reaches the maximum when the gas stays more than 30 s. The removal rate of NOx decreased with the initial concentration of NOx and the increase of gas flow rate, and the removal rate of NOx increased with the increase of NaOH concentration, and reached the maximum when the concentration of NaOH was 1.5mol/L. With the increase of relative humidity of flue gas, the removal rate of NOx increased first and then decreased significantly, and the removal rate of NOx reached the maximum when the relative humidity was 50. The NO2 production of gas-liquid two-phase dielectric barrier discharge in NaOH solution is much smaller than that of conventional plate electrode. Under the same experimental conditions, the removal rate of NOx by gas-liquid two-phase dielectric barrier discharge is obviously higher than that of plate electrode dielectric barrier discharge. The research results in this paper provide certain theoretical basis and application value for the application of gas-liquid two phase dielectric barrier discharge in denitrification of thermal power plant.
【學(xué)位授予單位】：西安理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TM621;X773

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本文編號：2319246