【摘要】：我國的能源結(jié)構(gòu)以煤炭為主。燃煤發(fā)電是我國最主要的煤炭消費(fèi)途徑,是煤炭能源轉(zhuǎn)換的主要環(huán)節(jié)。燃煤發(fā)電帶來的環(huán)境污染問題一直是環(huán)境治理的重點(diǎn)。燃煤煙氣中的主要污染物是氮氧化物(NOx),氮氧化物對自然環(huán)境和人類健康都有極大的危害。國家為了嚴(yán)格控制氮氧化物的排放,要求燃煤電廠使用選擇性催化還原(SCR)工藝脫除煙氣中的氮氧化物。為了研究SCR工藝中催化劑的結(jié)構(gòu)和磨損對催化還原系統(tǒng)的影響,本研究利用計(jì)算流體動力學(xué)(CFD)模擬SCR系統(tǒng)流場,并對模擬結(jié)果進(jìn)行分析得到結(jié)論。根據(jù)SCR反應(yīng)器實(shí)際情況,使用Gambit軟件建立了多種滿足模擬實(shí)驗(yàn)要求的三維模型,并根據(jù)計(jì)算要求進(jìn)行網(wǎng)格劃分。最終在Fluent軟件中進(jìn)行數(shù)值模擬,得到模擬數(shù)據(jù)和圖表。選取了蜂窩式、波紋板式、平板式三種催化劑結(jié)構(gòu),研究其孔結(jié)構(gòu)、孔徑、安裝距離等參數(shù)對SCR系統(tǒng)流場的影響。根據(jù)現(xiàn)場采集的催化劑磨損數(shù)據(jù),模擬了催化劑磨損后對SCR系統(tǒng)流場的影響。數(shù)值模擬結(jié)果表明平板式催化劑氣體通過性最佳,不易發(fā)生磨損的和積灰現(xiàn)象,蜂窩式催化劑氣體通過性較差,波紋板式催化劑的氣體通過性介于二者之間。催化劑的孔徑越大氣體通過性越好,單層催化劑的壓力降越小。兩層催化劑間距越大,越有利于氣體混合。磨損后的催化劑會改變反應(yīng)器內(nèi)流場,使得催化劑失效速度加快。理想狀態(tài)下應(yīng)選擇孔徑大、壓力降小、層間距大、耐磨性好的催化劑,但受催化反應(yīng)效率限制還應(yīng)在各項(xiàng)參數(shù)上做出取舍。
[Abstract]:China's energy structure is dominated by coal. Coal-fired power generation is the main way of coal consumption and the main link of coal energy conversion. The environmental pollution caused by coal-fired power generation has always been the focus of environmental control. The main pollutant in coal-fired flue gas is nitrogen oxide (NOx), which has great harm to natural environment and human health. In order to strictly control the emission of nitrogen oxides, coal-fired power plants are required to use selective catalytic reduction (SCR) process to remove nitrogen oxides from flue gas. In order to study the effect of catalyst structure and wear on the catalytic reduction system in SCR process, the computational fluid dynamics (CFD) (CFD) was used to simulate the flow field in SCR system, and the simulation results were analyzed. According to the actual situation of SCR reactor, a variety of three-dimensional models satisfying the requirements of simulation experiments were established by using Gambit software, and the meshes were divided according to the requirements of calculation. Finally, the numerical simulation is carried out in the Fluent software, and the simulated data and charts are obtained. Three kinds of catalyst structures, honeycomb, corrugated plate and flat plate, were selected to study the effects of pore structure, pore size and installation distance on the flow field of SCR system. Based on the field data of catalyst wear, the influence of catalyst wear on the flow field of SCR system was simulated. The numerical simulation results show that the gas passing ability of flat plate catalyst is the best, and the wear and ash accumulation are not easy to occur. The gas passing ability of honeycomb catalyst is poor, and the gas passing performance of corrugated plate catalyst is between the two. The larger the pore size of the catalyst is, the better the gas transmissibility is, and the smaller the pressure drop of the monolayer catalyst is. The larger the distance between the two catalysts, the more favorable the gas mixing. The worn catalyst can change the flow field in the reactor and accelerate the failure rate of the catalyst. Under the ideal condition, the catalyst with large pore size, small pressure drop, large layer spacing and good wear resistance should be chosen. However, due to the limitation of catalytic reaction efficiency, the choice should be made on various parameters.
【學(xué)位授予單位】：華北電力大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：X773;O643.36

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