發(fā)布時(shí)間：2018-04-26 17:14

  本文選題：煉化廢液焚燒 + 余熱鍋爐��； 參考：《大連理工大學(xué)》2015年碩士論文

【摘要】：石油化工、冶金、制藥等行業(yè)排放的毒性大、生物降解能力弱的高含鹽有機(jī)廢液給生態(tài)環(huán)境帶來(lái)的危害日趨嚴(yán)重。目前,國(guó)內(nèi)外處理工業(yè)有機(jī)廢液常用方法為熱化學(xué)轉(zhuǎn)化法,如焚燒法,此方法不僅可以使廢液中有害物質(zhì)徹底分解,而且可以回收焚燒過程產(chǎn)生的高溫能量,達(dá)到節(jié)能環(huán)保的目的。但是,在回收余熱過程中,余熱鍋爐換熱元件往往會(huì)產(chǎn)生嚴(yán)重的積灰、結(jié)渣問題,給余熱鍋爐安全、穩(wěn)定運(yùn)行帶來(lái)一系列不利影響,如積灰搭橋、熱效率降低、高溫腐蝕、換熱元件磨損等。本文以某石化企業(yè)煉化廢液焚燒余熱鍋爐為研究對(duì)象,對(duì)爐內(nèi)飛灰粒子遷移、分布和沉積特征、余熱鍋爐換熱及阻力特性進(jìn)行數(shù)值模擬研究,主要研究?jī)?nèi)容及結(jié)論如下：(1)建立余熱鍋爐氣-固兩相流動(dòng)及換熱數(shù)學(xué)模型,利用熱動(dòng)力學(xué)平衡計(jì)算軟件FactSage得到廢液焚燒形成富堿(鹽)型飛灰粒子的熔融曲線,并根據(jù)其物化特性,提出將臨界速度黏附模型與熔融組分黏附模型相結(jié)合,即采用臨界速度-熔融組分黏附模型對(duì)爐內(nèi)飛灰粒子黏附情況進(jìn)行評(píng)價(jià)。通過將數(shù)值計(jì)算結(jié)果與現(xiàn)場(chǎng)測(cè)試數(shù)據(jù)進(jìn)行對(duì)比,驗(yàn)證了本文建立的氣-固兩相流動(dòng)和換熱數(shù)學(xué)模型的合理性,以及提出的飛灰粒子黏附模型的可靠性。大尺寸粒子沉積全部發(fā)生在換熱管迎風(fēng)側(cè)-60°到600范圍內(nèi),沉積層呈山峰狀分布；微米級(jí)粒子在管子迎風(fēng)側(cè)沉積層同樣呈山峰狀分布,且主要集中在-500到50°區(qū)間內(nèi),在背風(fēng)側(cè)則均勻分布；亞微米級(jí)粒子均勻沉積于管子迎風(fēng)側(cè)和背風(fēng)側(cè)。(2)利用臨界速度-熔融組分黏附模型對(duì)多種因素影響下鍋爐內(nèi)飛灰粒子遷移、分布及沉積特征進(jìn)行研究。結(jié)果表明：粒子尺寸、管型、煙氣流速、橫向管間距對(duì)粒子沉積概率影響顯著,而縱向管間距只對(duì)亞微米級(jí)粒子沉積概率影響明顯；增大半橢圓管長(zhǎng)短半軸比、橫向管間距或減小煙氣流速,均可以顯著減小粒子沉積概率；隨著縱向管間距的增大,亞微米級(jí)粒子沉積概率減小明顯,而微米級(jí)和大尺寸粒子以及粒子總沉積概率則呈微弱增大趨勢(shì)；粒子尺寸對(duì)沉積概率影響顯著,粒子尺寸越大,沉積概率越大。(3)對(duì)余熱鍋爐內(nèi)換熱及阻力特性進(jìn)行研究,并利用綜合對(duì)流換熱性能評(píng)價(jià)指標(biāo)PEC反映換熱與壓力降變化產(chǎn)生的綜合效果。結(jié)果表明：增大長(zhǎng)短半軸比、煙氣流速或減小橫向管間距,均可以獲得更好的綜合對(duì)流換熱性能,當(dāng)S2/D取2時(shí),PEC取得最大值。其中,煙氣流速對(duì)PEC影響最為顯著；入口煙氣流速增大給爐內(nèi)Nu數(shù)和壓力降帶來(lái)顯著提高,而隨著長(zhǎng)短半軸比、橫向及縱向管間距的增大,Nu熱系數(shù)和壓力降均隨之降低。
[Abstract]:In petrochemical, metallurgical, pharmaceutical and other industries, organic waste liquid with high salinity and low biodegradability is harmful to the ecological environment. At present, the common methods of treating industrial organic waste liquid at home and abroad are thermochemical conversion method, such as incineration method. This method can not only completely decompose the harmful substances in the waste liquid, but also recover the high temperature energy produced by incineration process. Achieve the purpose of energy saving and environmental protection. However, in the process of recovering the waste heat, the heat transfer elements of the waste heat boiler often produce serious ash deposition, slagging problems, which bring a series of adverse effects to the safe and stable operation of the waste heat boiler, such as building bridges, reducing the thermal efficiency, and corroding at high temperature. Wear and tear of heat transfer elements, etc. In this paper, the characteristics of fly ash particle migration, distribution and deposition, heat transfer and resistance characteristics of waste heat boiler in a petrochemical enterprise are studied. The main research contents and conclusions are as follows: (1) the mathematical model of gas-solid two-phase flow and heat transfer in waste heat boiler is established. The melting curve of waste liquid incineration to form alkali (salt) type fly ash particles is obtained by using the thermal dynamic equilibrium calculation software FactSage. According to its physical and chemical characteristics, the critical velocity adhesion model and the melt component adhesion model are proposed to evaluate the adhesion of fly ash particles in the furnace by using the critical velocity-melting component adhesion model. By comparing the numerical results with the field test data, the rationality of the proposed mathematical model of gas-solid two-phase flow and heat transfer and the reliability of the proposed model are verified. The deposition of large size particles occurred in the range of -60 擄to 600 擄on the upwind side of the heat transfer tube, and the sediment layer was distributed in the form of a peak, while the micrometer particles distributed in the same way in the sediment layer of the tube side, and mainly concentrated in the range of -500 擄to 50 擄. On the leeward side, the submicron particles are uniformly deposited on the upwind and leeward sides of the tube. The critical velocity-melt component adhesion model is used to study the transport, distribution and deposition characteristics of fly ash particles in the boiler under the influence of many factors. The results show that particle size, tube type, flue gas flow rate and transverse tube spacing have significant effects on particle deposition probability, while longitudinal tube spacing has significant effect on submicron particle deposition probability, and increases the semi-elliptical tube length / half-axis ratio. The deposition probability of submicron particles decreased significantly with the increase of the longitudinal tube spacing or the decrease of flue gas velocity, and the deposition probability of submicron particles decreased significantly with the increase of the longitudinal tube spacing. However, the micrometer and large size particles and the total deposition probability of particles have a slight increasing trend, and the particle size has a significant effect on the deposition probability, and the larger the particle size, the greater the deposition probability.) the heat transfer and resistance characteristics in the waste heat boiler are studied. The comprehensive convection heat transfer performance evaluation index PEC is used to reflect the comprehensive effect of heat transfer and pressure drop. The results show that the better comprehensive convection heat transfer performance can be obtained by increasing the ratio of long and short axis, flue gas velocity or decreasing the transverse tube spacing, and the maximum value of PEC is obtained when S2 / D is 2. The influence of flue gas velocity on PEC is the most significant, and the increase of inlet flue gas velocity increases significantly the number of Nu and pressure drop in the furnace, while the thermal coefficient and pressure drop decrease with the increase of transverse and longitudinal tube spacing with the increase of the ratio of long and short axis.
【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：X742

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本文編號(hào)：1806917