【摘要】：我國(guó)面臨著能源危機(jī)和環(huán)境污染雙重挑戰(zhàn),因此開(kāi)發(fā)新能源部分替代煤是我國(guó)能源改革優(yōu)化的重要方向。我國(guó)屬于農(nóng)業(yè)大國(guó),生物質(zhì)能源作為一種豐富清潔的可再生能源可代替部分煤,同時(shí)由于燃煤排放至大氣中的細(xì)顆粒物過(guò)多,導(dǎo)致我國(guó)現(xiàn)階段作為嚴(yán)重的霧霾等問(wèn)題,細(xì)顆粒的排放對(duì)人類(lèi)的生存環(huán)境造成巨大的威脅,因此研究生物質(zhì)與煤混燒灰的細(xì)顆粒物在電除塵器內(nèi)部的相互作用從而實(shí)現(xiàn)尾部細(xì)顆粒的減排是燃煤電站開(kāi)發(fā)新能源過(guò)程中必不可少的,這對(duì)于探求可代替煤的最佳生物質(zhì)能源是十分重要的。本文選取的燃料分別為常見(jiàn)的生物質(zhì)燃料玉米秸稈與無(wú)煙煤兩種燃料,首先將玉米秸稈破碎后分別按照0、10%、15%、20%、100%的比例與無(wú)煙煤混摻后,經(jīng)燃燒形成一系列混燒灰。首先通過(guò)實(shí)驗(yàn)對(duì)這一系列混燒灰的理化特性(真密度、粒徑分布)等進(jìn)行了實(shí)驗(yàn)研究,為后續(xù)混燒灰在電除塵器內(nèi)部的相互作用情況做準(zhǔn)備。實(shí)驗(yàn)結(jié)果表明隨著生物質(zhì)玉米秸稈與無(wú)煙煤混燒比例的增加,混燒灰的真密度呈現(xiàn)逐漸下降的趨勢(shì)。同時(shí)由于玉米秸稈與無(wú)煙煤的混合燃燒,使得其粒徑分布較純無(wú)煙煤灰或純玉米秸稈灰發(fā)生了一定變化,但變化不是很明顯,其粒徑分布的峰值相同或接近。其次,本文主要對(duì)電除塵器內(nèi)部三種團(tuán)聚機(jī)理(熱團(tuán)聚、湍流團(tuán)聚、電團(tuán)聚)進(jìn)行了模擬研究,首先根據(jù)顆粒粒徑確定了不同團(tuán)聚機(jī)理下的團(tuán)聚核函數(shù)。由三種團(tuán)聚核函數(shù)可知,熱團(tuán)聚效果與發(fā)生團(tuán)聚的兩顆粒粒徑的差值相關(guān),差值越大,熱團(tuán)聚核函數(shù)愈大,并且熱團(tuán)聚作用對(duì)亞微米級(jí)顆粒的團(tuán)聚效果優(yōu)于微米級(jí)顆粒。湍流團(tuán)聚效果與顆粒粒徑相關(guān),顆粒粒徑越大,團(tuán)聚效果愈佳,湍流團(tuán)聚對(duì)微米級(jí)顆粒聚并作用優(yōu)于亞微米級(jí)顆粒。電團(tuán)聚效果愈顆粒粒徑相關(guān),顆粒粒徑越大,其所帶荷電量越多,電團(tuán)聚效果越明顯,電團(tuán)聚對(duì)于微米級(jí)顆粒以及亞微米級(jí)顆粒的團(tuán)聚效果均很明顯。最后在確定了團(tuán)聚核函數(shù)后,利用Fluent軟件對(duì)生物質(zhì)與煤混燒灰在電除塵器內(nèi)部的相互作用情況進(jìn)行了模擬研究。首先通過(guò)自帶的自定義函數(shù)功能(UDF)將不同的團(tuán)聚核函數(shù)程序?qū)胲浖?接著利用顆粒群平衡模型(PBM)與歐拉-歐拉雙流體模型耦合,采用Sectional分區(qū)算法進(jìn)行求解。研究結(jié)果表明:當(dāng)流場(chǎng)流速為1.0m/s,顆粒體積分?jǐn)?shù)為1.4%時(shí)熱團(tuán)聚效果最佳,并且在玉米秸稈與無(wú)煙煤混摻比為10%時(shí)熱團(tuán)聚效果最好;當(dāng)流場(chǎng)流速為1.5m/s,顆粒體積分?jǐn)?shù)為1.4%時(shí)湍流團(tuán)聚效果最佳;當(dāng)流場(chǎng)流速為1.0m/s,顆粒體積分?jǐn)?shù)為1.4%時(shí)電團(tuán)聚效果最佳,并且在玉米秸稈與無(wú)煙煤混摻比為10%時(shí)電團(tuán)聚效果最佳。電除塵器中顆粒團(tuán)聚主要以電團(tuán)聚為主,熱團(tuán)聚和湍流團(tuán)聚為輔,三者共同為微米級(jí)顆粒的團(tuán)聚起到十分重要的促進(jìn)作用。因此發(fā)展超細(xì)顆粒物團(tuán)聚減排新技術(shù),應(yīng)特別重視電團(tuán)聚技術(shù)、熱團(tuán)聚技術(shù)以及湍流團(tuán)聚技術(shù)。電除塵器最佳運(yùn)行工況為流場(chǎng)流速1.0m/s,顆粒數(shù)密度體積分?jǐn)?shù)為1.4%,玉米秸稈/無(wú)煙煤混燒比為10%,對(duì)后續(xù)的電除塵器改造及燃料選型具有十分重要的意義。
[Abstract]:China is faced with the dual challenge of energy crisis and environmental pollution, so it is an important way to develop new energy part instead of coal as the optimization of our country's energy reform. China belongs to the big agricultural power, and the biomass energy source is used as a rich and clean renewable energy source to replace some coal, and at the same time, due to the excessive fine particles discharged from the coal to the atmosphere, the present stage of our country, as a serious haze, The emission of fine particles poses a great threat to the living environment of human beings, so the interaction of the fine particles of the graduate material and the coal mixed ash in the electric dust collector to realize the emission reduction of the tail fine particles is essential in the development of a new energy source for the coal-fired power station, This is very important for exploring the optimal biomass energy sources that can be used in place of coal. The fuel selected in this paper is the common biomass fuel, corn straw and anthracite, and first, the corn straw is crushed and then mixed with anthracite according to the ratio of 0, 10%, 15%, 20% and 100%, respectively, and then the mixture is burnt to form a series of mixed ash. The physical and chemical properties (such as the true density and the particle size distribution) of this series of ash mixed ash were studied by the experiment, and the interaction of the mixed ash in the dust collector was prepared. The experimental results show that with the increase of the mixing ratio of the biomass corn straw and the anthracite, the true density of the mixed ash shows a decreasing tendency. At the same time, due to the mixed combustion of the corn straw and the anthracite, the grain size distribution of the corn straw is changed with the pure anthracite ash or the pure corn straw ash, but the change is not obvious, and the peak value of the particle size distribution is the same or close. Secondly, in this paper, three kinds of agglomeration mechanism (thermal agglomeration, turbulent agglomeration and electroreunification) inside the electric dust collector were simulated, and the aggregation kernel function under different agglomeration mechanism was first determined according to the particle size. It is known from the three aggregate core functions that the thermal agglomeration effect is related to the difference of the particle size of the two particles, the greater the difference, the greater the thermal agglomeration nuclear function, and the effect of the thermal agglomeration on the sub-micron particles is superior to that of the micron-sized particles. The effect of turbulent agglomeration is related to the particle size of the particles, the larger the particle size, the better the agglomeration effect, the agglomeration of the turbulent flow to the micron-sized particles, and the effect is better than the sub-micron-sized particles. The larger the particle size of the particles, the more the particle size of the particles, the more the charged amount of the particles, the more the electrical agglomeration, the more obvious the agglomeration of the micron-sized particles and the sub-micron-sized particles. Finally, the interaction between the biomass and the coal ash in the electrostatic precipitator was simulated by Fluent software after the function of the aggregation kernel was determined. First, different cluster kernel function programs are introduced into the software by the self-contained custom function function (UDF), and then the particle swarm optimization model (PBM) is used to couple with the Euler-Euler double fluid model, and the traditional partition algorithm is used for solving the problem. The results show that when the flow velocity of the flow field is 1. 0m/ s, the volume fraction of the particles is 1. 4%, the thermal agglomeration effect is the best, and the effect of the thermal agglomeration is the best when the mixing ratio of the corn straw and the anthracite is 10%; when the flow velocity of the flow field is 1. 5m/ s, the volume fraction of the particles is 1. 4%, the turbulent agglomeration effect is the best; When the flow velocity of the flow field is 1. 0m/ s, the volume fraction of the particles is 1. 4%, the effect of the electric agglomeration is the best, and the effect of the electric agglomeration is the best when the mixing ratio of the corn straw and the anthracite is 10%. The agglomeration of the particles in the electric dust collector is mainly composed of the electric agglomeration, the thermal agglomeration and the turbulent re-agglomeration as the auxiliary, which play a very important role in the agglomeration of the micron-sized particles. Therefore, the new technology of agglomeration and emission reduction of ultra-fine particles should be developed with special attention to the technology of electric agglomeration, heat-agglomeration and the technology of turbulent agglomeration. The optimum operating condition of the electric dust collector is the flow field flow rate of 1. 0m/ s, the volume fraction of the particle number density is 1.4%, and the mixed burning ratio of the corn straw/ anthracite is 10%, which is of great significance for the subsequent improvement of the electric dust collector and the selection of the fuel.
【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】：2017
【分類(lèi)號(hào)】：X701

【參考文獻(xiàn)】

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本文編號(hào)：2430076