【摘要】：近幾年,隨著經(jīng)濟的快速增長,細微顆粒PM2.5的污染越來越嚴重,對人們的生活環(huán)境造成了巨大影響。煤炭等化石燃料的燃燒是這些顆粒污染物主要來源之一。對于燃燒源顆粒物的控制和脫除已成為能源和環(huán)境領(lǐng)域急需解決的重要問題。聲波團聚作為一種應用在除塵器前的預處理技術(shù),因其易于操作、效果比較明顯而備受研究者的關(guān)注。鑒于此,本文對聲波團聚技術(shù)開展了實驗和模擬兩方面的研究。在實驗方面,設計并搭建燃煤電廠顆粒物低頻聲波團聚實驗臺,采用某電廠不同的燃煤飛灰作為實驗所用氣溶膠。研究了在聲壓級從133d B-146d B,頻率從1000Hz-2400Hz,氣溶膠初始數(shù)目濃度從1.33?105cm-3-3.55?105cm-3條件下聲波團聚細微顆粒物的效果,分析不同參數(shù)對團聚效果的影響。結(jié)果表明:當頻率為1400Hz,聲壓級為146d B時,團聚效率最高。隨著聲壓級和氣溶膠初始濃度的增加,團聚效果也不斷增強。但是考慮到能耗問題,聲壓級和氣溶膠初始濃度都應適度選擇。在理論方面,探索細微顆粒物聲波團聚的機理并進行數(shù)值模擬研究。首先對不同團聚機理的團聚核函數(shù)進行模擬,表明同向團聚核函數(shù)值遠高于其它作用機理下的數(shù)值。對于粒徑為1μm和2.5μm的亞細微顆粒,其最佳團聚頻率都在10k Hz以上。其次,采用改進后的分組法對聲波團聚氣溶膠過程進行數(shù)值模擬,在頻率、聲壓級及氣溶膠初始濃度影響下,模擬所得結(jié)果基本與實驗結(jié)果相符。在對溫度的模擬中發(fā)現(xiàn),團聚效果隨著溫度的升高而減緩,特別是溫度高于300℃。最后,將幾種不同團聚機理組成的模型進行數(shù)值模擬,并與實驗結(jié)果作對比分析,從而表明不同機理對于顆粒團聚的影響,得到適用于燃煤電廠細微顆粒聲波團聚的最適合模型。結(jié)果表明:四種不同數(shù)值模型模擬后的顆粒粒徑分布趨勢與實驗結(jié)果相符,僅在部分粒徑段出現(xiàn)些微偏差。在與實驗值的對比中發(fā)現(xiàn),布朗團聚主要作用于粒徑小于0.1μm以下的顆粒,而對大于0.1μm以上的顆粒其影響幾乎可以忽略。
[Abstract]:In recent years, with the rapid growth of economy, the pollution of PM2.5 is becoming more and more serious, which has a great impact on people's living environment. The combustion of fossil fuels such as coal is one of the main sources of these particulate pollutants. The control and removal of particulate matter from combustion source has become an important problem in the field of energy and environment. Acoustic agglomeration, as a pretreatment technique applied in front of dust catcher, has attracted much attention because of its easy operation and obvious effect. In view of this, the acoustic agglomeration technology has been studied in both experimental and simulation aspects. In the aspect of experiment, the low frequency acoustic wave agglomeration test table of particles in coal-fired power plant is designed and built. Different fly ash from coal burning in a power plant is used as the aerosol in the experiment. The effect of acoustic agglomeration of fine particles at sound pressure level from 133d B-146dB, frequency from 1000Hz to 2400Hz and initial concentration of aerosol from 1.33?105cm-3-3.55?105cm-3 was studied. The effect of different parameters on agglomeration effect was analyzed. The results show that when the frequency is 1400Hz and the sound pressure level is 146dB, the agglomeration efficiency is the highest. With the increase of the sound pressure level and the initial concentration of aerosol, the agglomeration effect is enhanced. However, considering energy consumption, sound pressure level and initial aerosol concentration should be appropriately selected. In theory, the mechanism of acoustic agglomeration of fine particles was explored and numerical simulation was carried out. Firstly, the agglomeration kernel function of different agglomeration mechanism is simulated, which shows that the value of codirectional agglomeration kernel function is much higher than that of other mechanisms. The optimum agglomeration frequency is above 10kHz for subfine particles with particle sizes of 1 渭 m and 2.5 渭 m. Secondly, the acoustic agglomeration aerosol process is numerically simulated by the improved grouping method. Under the influence of frequency, sound pressure level and initial concentration of aerosol, the simulated results are basically consistent with the experimental results. In the simulation of temperature, it is found that the agglomeration effect slows down with the increase of temperature, especially when the temperature is higher than 300 鈩，

本文編號：2128673