【摘要】：近幾年,隨著經(jīng)濟(jì)的快速增長,細(xì)微顆粒PM2.5的污染越來越嚴(yán)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(tuán)聚作為一種應(yīng)用在除塵器前的預(yù)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(tuán)聚技術(shù)開展了實(shí)驗(yàn)和模擬兩方面的研究。在實(shí)驗(yàn)方面,設(shè)計(jì)并搭建燃煤電廠顆粒物低頻聲波團(tuán)聚實(shí)驗(yàn)臺(tái),采用某電廠不同的燃煤飛灰作為實(shí)驗(yàn)所用氣溶膠。研究了在聲壓級(jí)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(tuán)聚細(xì)微顆粒物的效果,分析不同參數(shù)對團(tuán)聚效果的影響。結(jié)果表明:當(dāng)頻率為1400Hz,聲壓級(jí)為146d B時(shí),團(tuán)聚效率最高。隨著聲壓級(jí)和氣溶膠初始濃度的增加,團(tuán)聚效果也不斷增強(qiáng)。但是考慮到能耗問題,聲壓級(jí)和氣溶膠初始濃度都應(yīng)適度選擇。在理論方面,探索細(xì)微顆粒物聲波團(tuán)聚的機(jī)理并進(jìn)行數(shù)值模擬研究。首先對不同團(tuán)聚機(jī)理的團(tuán)聚核函數(shù)進(jìn)行模擬,表明同向團(tuán)聚核函數(shù)值遠(yuǎn)高于其它作用機(jī)理下的數(shù)值。對于粒徑為1μm和2.5μm的亞細(xì)微顆粒,其最佳團(tuán)聚頻率都在10k Hz以上。其次,采用改進(jìn)后的分組法對聲波團(tuán)聚氣溶膠過程進(jìn)行數(shù)值模擬,在頻率、聲壓級(jí)及氣溶膠初始濃度影響下,模擬所得結(jié)果基本與實(shí)驗(yàn)結(jié)果相符。在對溫度的模擬中發(fā)現(xiàn),團(tuán)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(tuán)聚機(jī)理組成的模型進(jìn)行數(shù)值模擬,并與實(shí)驗(yàn)結(jié)果作對比分析,從而表明不同機(jī)理對于顆粒團(tuán)聚的影響,得到適用于燃煤電廠細(xì)微顆粒聲波團(tuán)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(shí)驗(yàn)結(jié)果相符,僅在部分粒徑段出現(xiàn)些微偏差。在與實(shí)驗(yàn)值的對比中發(fā)現(xiàn),布朗團(tuán)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(hào)：2128673