本文選題：CFD + 垃圾焚燒爐煙氣脫硝��； 參考：《哈爾濱工業(yè)大學》2017年碩士論文

【摘要】：隨著城市化進程的發(fā)展,我國城市垃圾問題日益嚴重。垃圾焚燒技術(shù)以其 減量化‖及 資源化‖等優(yōu)勢,逐漸成為我國垃圾處理的主流技術(shù)。垃圾焚燒不可避免的會產(chǎn)生二次污染氣體,其中NOx是垃圾焚燒產(chǎn)生的主要污染物之一。為控制垃圾焚燒NOx的排放,以達到最新國家和地方標準,應(yīng)對現(xiàn)有垃圾焚燒爐進行脫硝改造。選擇性非催化還原(SNCR)脫硝技術(shù)改造簡單、運行成本相對較低,是目前較流行的生活垃圾焚燒爐煙氣脫硝技術(shù)之一。本文以一臺400 t/d生活垃圾焚燒爐為研究對象,利用計算流體力學(CFD)軟件提出垃圾焚燒爐煙氣脫硝優(yōu)化改造方案。首先模擬焚燒爐內(nèi)的氣相燃燒過程和SNCR脫硝反應(yīng)過程,并通過獲取現(xiàn)場實測值、實驗驗證、文獻佐證等方式驗證所建立模型的可靠性。其次利用數(shù)值模擬方法,對垃圾焚燒的氣相燃燒過程和SNCR還原劑噴射過程進行優(yōu)化。最終提出并評估各垃圾焚燒爐煙氣脫硝綜合優(yōu)化方案。本文在優(yōu)化氣相燃燒過程時,設(shè)計了6種二次風噴射方式優(yōu)化方案,考察各噴射方式對爐內(nèi)煙氣運動及燃燒反應(yīng)的影響。結(jié)果表明:優(yōu)化二次風噴射方式可使爐內(nèi)形成螺旋結(jié)構(gòu),并使二次風停留時間最高提升40.62%。以此為基礎(chǔ),優(yōu)化二次風噴射速度,使一次風:二次風值為0.72:0.28時,達到優(yōu)化噴射條件。利用SNCR模型,通過單因素模擬和正交模擬,研究噴槍噴射參數(shù)(噴射粒徑、噴射速度、噴射角、噴射量、噴射濃度)對SNCR系統(tǒng)還原劑蒸發(fā)和混合的影響。根據(jù)研究結(jié)果,設(shè)計的最佳噴射參數(shù)為:噴射粒徑為400μm,噴射速度為35 m/s,噴射角為30°,噴射量50 kg/h,噴射濃度為25%。應(yīng)用最佳噴射參數(shù),研究噴槍個數(shù)和噴槍位置對還原劑分布的影響。設(shè)計的噴射最佳排布方式為:8噴槍噴射,采用4墻對噴方式,每墻各2噴槍,噴槍在各墻壁上由中央向兩側(cè)依次排布。結(jié)合氣相燃燒過程優(yōu)化和SNCR過程優(yōu)化,設(shè)計并篩選脫硝效果較好的綜合優(yōu)化方案進行工程成本及環(huán)境經(jīng)濟效益評估。各綜合優(yōu)化方案中,最佳脫硝效果方案的脫硝率可達55.52%。最低工程成本方案在改造15年時垃圾脫硝成本為5.46元/t。最佳環(huán)境經(jīng)濟效益方案在改造15年時噸NO去除成本為5 597元/t。以上方案的NO排放最高為183.8 mg/Nm3,滿足《GB18485-2014生活垃圾焚燒污染控制標準》和歐盟2000標準,且漏氨體積分數(shù)均小于10-4。
[Abstract]:With the development of urbanization, the problem of urban garbage in China is becoming more and more serious. MSW incineration technology has gradually become the mainstream technology of garbage disposal in our country because of its advantages of reducing quantity and resources. MSW incineration will inevitably produce secondary pollution gas, among which NOx is one of the main pollutants produced by MSW incineration. In order to control NOx emission from MSW incineration to meet the latest national and local standards, the existing MSW incinerator should be denitrified. Selective non-catalytic reduction (SNCR) denitrification is one of the most popular flue gas denitrification technologies in domestic waste incinerators because of its simple revamping and relatively low operating cost. In this paper, a 400 t / d MSW incinerator is used as a research object, and a scheme for optimizing flue gas denitrification of MSW incinerator is proposed by using computational fluid dynamics (CFD) software. Firstly, the gas combustion process and SNCR denitrification process in the incinerator were simulated, and the reliability of the established model was verified by obtaining the field measured values, experimental verification and documentary evidence. Secondly, the gas combustion process and SNCR reducing agent injection process of MSW incineration were optimized by numerical simulation. Finally, a comprehensive optimization scheme for flue gas denitrification of waste incinerators is proposed and evaluated. In this paper, six optimization schemes of secondary air injection are designed to optimize the gas combustion process, and the effects of different injection modes on the flue gas movement and combustion reaction in the furnace are investigated. The results show that the helical structure can be formed by optimizing the secondary air injection mode and the residence time of the secondary air can be raised by 40.622. On the basis of this, the injection velocity of secondary air is optimized to reach the optimal injection condition when the secondary air value is 0.72: 0.28. The effects of spray parameters (particle size, injection velocity, injection angle, injection volume and injection concentration) on the evaporation and mixing of reducing agent in SNCR system were studied by single factor simulation and orthogonal simulation using SNCR model. According to the results of the study, the optimum injection parameters are as follows: the injection diameter is 400 渭 m, the injection velocity is 35 m / s, the injection angle is 30 擄, the injection amount is 50 kg / h, the injection concentration is 25%. The effects of the number and position of the spray gun on the distribution of reducing agent were studied by using the optimum injection parameters. The optimal arrangement of spray is designed as: 1: 8 spray gun, 4 wall jet on each wall, 2 guns per wall, and the spray gun is arranged from the center to the two sides on each wall in turn. Combined with gas combustion process optimization and SNCR process optimization, a comprehensive optimization scheme with better denitrification effect was designed and selected for engineering cost and environmental economic evaluation. Among the comprehensive optimization schemes, the denitrification rate of the best denitrification scheme can reach 55.52%. The minimum project cost is 5.46 yuan / t when the cost of waste denitrification is 5.46 yuan / t. The cost of no removal is 5 597 yuan / t when the best environmental economic benefit scheme is reformed for 15 years. The highest no emission of the above scheme is 183.8 mg / Nm ~ (3), which meets the < GB18485-2014 MSW incineration pollution control standard] and EU 2000 standard, and the ammonia leakage volume fraction is less than 10-4.
【學位授予單位】：哈爾濱工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：X701

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