【摘要】：近年來隨著社會(huì)經(jīng)濟(jì)的快速發(fā)展，電力供應(yīng)快速增加，燃煤量顯著增加，火電廠氮氧化物的排放總量快速增加。氮氧化物的排放對(duì)于大氣環(huán)境有著嚴(yán)重的危害性，必須有效地控制燃煤發(fā)電過程中氮氧化物的生成量，控制氮氧化物的排放已經(jīng)成為當(dāng)前我國環(huán)境保護(hù)工作的重點(diǎn)。為降低火電機(jī)組的NOx排放以滿足日益嚴(yán)格的排放標(biāo)準(zhǔn)以及改善空氣質(zhì)量，新老火電機(jī)組的煙氣脫硝工程顯得格外重要。 本文研究了火電機(jī)組NOx的生成機(jī)理以及影響因素，氮氧化物排放的控制及處理方法，并對(duì)不同的氮氧化物的處理方法進(jìn)行了比較，重點(diǎn)研究了選擇性催化還原法的原理、脫硝反應(yīng)過程中所發(fā)生的副反應(yīng)、脫硝系統(tǒng)的的組成、反應(yīng)器布置方案、脫硝工藝選擇的原則、脫硝反應(yīng)劑的制備以及不同脫硝劑反應(yīng)的比較，并分析了加裝SCR裝置對(duì)鍋爐主機(jī)設(shè)備的影響以及反應(yīng)器旁路煙道等有關(guān)問題。 結(jié)合某廠機(jī)組實(shí)際情況采取先降后脫的路線對(duì)該廠#156機(jī)組進(jìn)行了低氮燃燒器和脫硝工程的改造。根據(jù)改造前后機(jī)組運(yùn)行狀況以及有關(guān)電科院的試驗(yàn)結(jié)果，通過對(duì)低氮燃燒改造、分級(jí)配風(fēng)降低主燃燒區(qū)域的溫度場水平，有效減少了W型鍋爐熱力型NOx的生產(chǎn)量，明顯地降低了鍋爐煙氣NOx含量水平。由燃燒器改造前330-335MW負(fù)荷下NOx排放濃度平均值為1210mg/m3（標(biāo)態(tài)干基，O2=6%）降到改造后330MW負(fù)荷下NOx排放濃度602mg/m3，達(dá)到預(yù)期的改造目的（低于800mg/m3）。在350MW負(fù)荷下，鍋爐實(shí)測熱效率為92.63%，，高于設(shè)計(jì)值91.82%，在其它工況下，鍋爐熱效率均高于設(shè)計(jì)值，表明#6鍋爐經(jīng)濟(jì)性能良好。改造后各工況下的鍋爐熱效率均高于改造前的鍋爐熱效率。改造工程通過采用先降后脫的技術(shù)路線，對(duì)現(xiàn)有燃燒器進(jìn)行低氮改造使氮氧化物降低至一定水平后再進(jìn)行煙氣脫硝，最終使NOx的排放濃度達(dá)到《火電廠大氣污染物排放標(biāo)準(zhǔn)》（GB13223-2011）允許的氮氧化物排放濃度200mg/m3，為同類機(jī)組的脫硝系統(tǒng)改造提供寶貴經(jīng)驗(yàn)。
[Abstract]:In recent years, with the rapid development of social economy, the power supply is increasing rapidly, the amount of coal burning is increasing significantly, and the total amount of NOx emission from thermal power plants is increasing rapidly. The emission of nitrogen oxides is harmful to the atmospheric environment. It is necessary to effectively control the amount of nitrogen oxides produced in the process of coal-fired power generation and control the emission of nitrogen oxides has become the focus of environmental protection in China. In order to reduce the NOx emissions of thermal power units to meet the increasingly stringent emission standards and improve air quality, the flue gas denitrification project of new and old thermal power units is particularly important. In this paper, the formation mechanism and influencing factors of NOx, the control and treatment methods of NOx emission are studied, and the different treatment methods of NOx are compared, and the principle of selective catalytic reduction method is emphatically studied. The side reactions occurred in denitrification process, the composition of denitrification system, the layout of reactor, the principle of denitrification process selection, the preparation of denitrification reagents and the comparison of different denitrification reagents. The influence of SCR installation on boiler mainframe equipment and the related problems of reactor bypass flue were analyzed. The low nitrogen burner and denitrification project of # 156 unit were retrofitted according to the actual situation of the unit. According to the operating condition of the unit before and after the revamping and the test results of the electric institute concerned, by reforming the low nitrogen combustion, the temperature field level of the main combustion area is reduced by the staged air distribution, and the production of the thermal type NOx of the W type boiler is effectively reduced. The NOx content of boiler flue gas is obviously reduced. Before the revamping of the burner, the average concentration of NOx emission under 330-335MW load was reduced to 1210mg/m3 (standard dry base, O _ 2O _ 2 ~ (6%) to 60 ~ 2 mg / m ~ (3) of NOx emission concentration under 330MW load after revamping, which achieved the desired revamping purpose (lower than 800mg/m3). Under 350MW load, the measured thermal efficiency of boiler is 92.63, which is higher than the design value of 91.822.In other conditions, the thermal efficiency of boiler is higher than the design value, which indicates that the economic performance of # 6 boiler is good. The thermal efficiency of boiler is higher than that of boiler before revamping. By adopting the technical route of first reducing and then removing the existing burners, the revamping of the existing burners can reduce the nitrogen oxides to a certain level before flue gas denitrification. Finally, the emission concentration of NOx is up to 200 mg / m ~ 3 of nitrogen oxide emission permitted by GB13223-2011, which provides valuable experience for the revamping of denitrification system of similar units.
【學(xué)位授予單位】：華北電力大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：X773;TM621

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