發(fā)布時(shí)間：2019-05-11 11:35

【摘要】：近年來,隨著火電行業(yè)“超低”排放概念再次熱議,氮氧化物排放要求得到了進(jìn)一步提高。SCR脫硝技術(shù)由于脫硝效率高、技術(shù)成熟等優(yōu)點(diǎn),一直是控制NOx排放的主要選擇。本文以某300MW燃煤機(jī)組SCR脫硝煙道內(nèi)部煙氣的流動(dòng)問題為研究對象,采用Fluent軟件對原始設(shè)計(jì)模型進(jìn)行了氣動(dòng)流場數(shù)值模擬。在分析得出原型煙氣分布規(guī)律的前提下,結(jié)合煙氣流動(dòng)特性以及壓力損失變化,首先研究了擴(kuò)張流道導(dǎo)流板與傾斜流道擾流管對噴氨系統(tǒng)以及反應(yīng)器內(nèi)速度場的影響。其次,根據(jù)噴氨混合系統(tǒng)存在的缺陷,通過增大渦流混合器直徑、傾斜角度以及改變噴嘴位置等措施,有針對性地對原型進(jìn)行了改進(jìn),優(yōu)化了煙道內(nèi)氨與煙氣的濃度分布。最后,綜合上述方案,獲得速度和濃度均勻性均滿足工程要求的最終優(yōu)化方案。結(jié)果表明：原型流場的速度和濃度均勻性較差。增加導(dǎo)流板改善了擴(kuò)張流道內(nèi)的煙氣流動(dòng),均化了速度和NH3/NO分布。擾流管改變了煙氣貼壁流動(dòng)規(guī)律,消除了催化劑入口速度分布不均現(xiàn)象,并且對壓力損失和濃度均勻性影響很小。適當(dāng)增加渦流混合器直徑和傾斜角度可以明顯增強(qiáng)噴氨系統(tǒng)氨氮的湍流摻混,結(jié)合噴嘴位置調(diào)整,明顯優(yōu)化了反應(yīng)器內(nèi)的濃度均勻性。
[Abstract]:In recent years, with the re-discussion of the concept of "ultra-low" emissions in thermal power industry, the emission requirements of nitrogen oxides have been further improved. NOx denitrification technology has been the main choice to control NOx emissions because of its high denitrification efficiency and mature technology. In this paper, the flow of flue gas in the SCR flue of a 300MW coal-fired unit is studied, and the aerodynamic flow field of the original design model is simulated by using Fluent software. On the premise of analyzing the distribution law of prototype flue gas, combined with the characteristics of flue gas flow and the change of pressure loss, the effects of diffuser guide plate and inclined channel spoiler on ammonia injection system and velocity field in reactor are studied at first. Secondly, according to the defects of ammonia injection mixing system, the prototype is improved by increasing the diameter of vortex mixer, inclined angle and changing the position of nozzle, and the concentration distribution of ammonia and flue gas in flue gas is optimized. Finally, the final optimization scheme which meets the engineering requirements is obtained by synthesizing the above scheme. The results show that the velocity and concentration uniformity of the prototype flow field is poor. The flue gas flow in the expansion channel is improved by increasing the guide plate, and the velocity and NH3/NO distribution are homogenized. The turbulent tube changed the flow law of flue gas adhesion, eliminated the uneven velocity distribution at the inlet of catalyst, and had little effect on pressure loss and concentration uniformity. Properly increasing the diameter and tilt angle of the swirl mixer can obviously enhance the turbulent mixing of ammonia nitrogen in the ammonia injection system, and the uniformity of the concentration in the reactor can be obviously optimized by adjusting the position of the nozzle.
【學(xué)位授予單位】：大連海事大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：X773

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本文編號：2474459