發(fā)布時間：2018-02-08 13:08

  本文關(guān)鍵詞： 煤自燃 煤矸石山 自然發(fā)火 熱棒 移熱降溫 余熱移除　出處：《西安科技大學(xué)》2017年博士論文　論文類型：學(xué)位論文

【摘要】：自燃煤矸石山是一種比較特殊的燃燒系統(tǒng),具有易自燃、蓄熱大、易復(fù)燃的特點(diǎn)。露天堆放的煤炭和煤矸石時常發(fā)生自燃,浪費(fèi)資源、污染環(huán)境,嚴(yán)重的還會引發(fā)事故,造成巨大損失。常規(guī)治理手段主要從“隔氧”的角度來控制煤矸石山自燃,由于內(nèi)部積聚的熱量無法及時散除,隨著時間推移多會發(fā)生復(fù)燃。本文基于“降溫”的技術(shù)思路,提出自燃煤矸石山熱棒深部移熱降溫理方法。從理論角度分析了煤矸石自燃熱動力學(xué)過程及發(fā)火條件,研究風(fēng)流滲透、水分等內(nèi)外因與煤矸石山自燃特性之間的相互關(guān)系。公烏素煤矸石所含N、C、H元素、固定碳含量和比熱容均低于公烏素煤;含水率、含灰分量、含硫量、熱擴(kuò)散系數(shù)和導(dǎo)熱系數(shù)均高于公烏素煤。在相同的溫度梯度下,煤矸石內(nèi)部溫度變化傳播更迅速、溫度擴(kuò)散能力更大,比公烏素煤傳導(dǎo)的能量更多。相同的熱量加熱下,煤矸石升溫更快,更易自燃。煤矸石綜合燃燒指數(shù)S_n(V_(ad)+FC_(ad))/A_(ad)呈正相關(guān),擬合系數(shù)R~2=0.9759,煤矸石含揮發(fā)分和固定碳含量越高、灰分越低,其綜合燃燒性能越好。綜合燃燒指數(shù)S_n.點(diǎn)燃指數(shù)Di和燃盡指數(shù)Dh與FC_(ad)/V_(ad)呈正相關(guān),線性擬合相關(guān)系數(shù)分別為R~2=0.8429、0.9258、0.9972,在充分供氧燃燒條件下,燃料比越大,煤矸石的燃盡性能越好。耗氧速率、CO濃度和產(chǎn)生率、第三火災(zāi)系數(shù)R~3可作為預(yù)報煤矸石自燃的主要指標(biāo),CO_2和CH_4濃度及產(chǎn)生率、第一火災(zāi)系數(shù)R1第二火災(zāi)系數(shù)R~2作為輔助指標(biāo)。將煤矸石的熱失重過程劃分為脫附、氧化劑裂解、燃燒和熱活化及相變4個階段,得到了對應(yīng)階段失重率和特征溫度參數(shù)。采用Achar微分法和Coats-Redfern積分法聯(lián)合求解了煤矸石非控自燃動力學(xué)參數(shù)和機(jī)理函數(shù)。熱棒影響煤堆內(nèi)部溫度場熱行為的實(shí)驗研究表明,試驗期內(nèi)單根熱棒對煤堆的最大降溫幅度為33.4℃,降溫率39.6%;雙根熱棒作用下煤堆內(nèi)出現(xiàn)了“馬鞍”狀溫度場分布。推導(dǎo)了熱棒在煤堆中的降溫半徑數(shù)學(xué)關(guān)系式,計算得到80 h熱棒的散熱量分別為1.0865、2.1680和3.3649 MJ。模擬驗證了熱棒對煤堆內(nèi)部溫度場的影響及分布規(guī)律。研究表明,熱棒對煤堆的降溫效果與距離成負(fù)相關(guān),與自燃煤堆內(nèi)部熱源功率成正相關(guān)。熱棒對煤堆的蓄冷降溫能力隨時間持續(xù)增加。另外,本文確定了熱棒現(xiàn)場實(shí)施安裝工藝,建立了熱棒遠(yuǎn)程無線安全運(yùn)行監(jiān)測系統(tǒng),研究了工業(yè)試驗現(xiàn)場熱棒軸向溫度、煤矸石山水平、垂直溫度分布特征和日溫度變化特征,基于熱棒在煤堆中熱周轉(zhuǎn)過程,推導(dǎo)并計算了評價、判斷熱棒移熱降溫效果的散熱量等量化標(biāo)準(zhǔn)。本文的研究可為熱棒技術(shù)在煤矸石自燃防滅火領(lǐng)域的大范圍推廣應(yīng)用提供基礎(chǔ)和指導(dǎo)。
[Abstract]:The spontaneous combustion coal gangue mountain is a kind of relatively special combustion system, which has the characteristics of easy spontaneous combustion, large heat storage and easy re-burning. Spontaneous combustion of coal and coal gangue stored in the open air often occurs, waste resources, pollute the environment, and serious accidents occur. This paper is based on the technical thinking of "cooling down", because the internal heat accumulation can not be dissipated in time, and more and more reburning will occur over time, and this article is based on the technical thinking of "cooling down", which is mainly from the angle of "oxygen insulation", because the internal heat accumulation can not be dissipated in time. This paper puts forward a method of heat transfer and cooling mechanism in the deep part of spontaneous combustion gangue mountain heat rod, analyzes the thermal dynamic process and combustion conditions of spontaneous combustion of coal gangue from a theoretical point of view, and studies the permeation of air flow. The relationship between internal and external water content and spontaneous combustion characteristics of coal gangue. The fixed carbon content and specific heat capacity of gangue coal gangue are lower than those of gongwusu coal, the moisture content, ash content and sulfur content are lower than those of gongwusu coal. The thermal diffusion coefficient and thermal conductivity coefficient are both higher than those of Gongwusu coal. At the same temperature gradient, the internal temperature change of gangue propagates more rapidly, and the thermal diffusivity is larger than that of Gongwusu coal. Under the same heat heating, the thermal diffusivity of gangue is higher than that of gongwusu coal. The coal gangue heats up faster and is easier to self-ignite.; the comprehensive combustion index of coal gangue, Snn / V / D), has a positive correlation with FCU / A / A / A / D, and the fitting coefficient is 0.9759. The higher the volatile content and the fixed carbon content of coal gangue, the lower the ash content. The better the comprehensive combustion performance is, the better the comprehensive combustion index is: Sn.Ignition index Di and burnout index Dh are positively correlated with FCSAD / VSP / VSP, and the linear fitting correlation coefficients are RP20.84290.92580.9972, respectively. Under the condition of full oxygen combustion, the fuel ratio increases. The better the burnout performance of coal gangue is, the higher the oxygen consumption rate is, the CO concentration and production rate, and the third fire coefficient R3 can be used as the main index to predict the spontaneous combustion of coal gangue, such as CO-2 and CH_4 concentration and production rate. The first fire coefficient R1 and the second fire coefficient R2 are used as auxiliary indexes. The thermogravimetric process of coal gangue is divided into four stages: desorption, oxidant cracking, combustion and thermal activation and phase transition. The relative weightlessness rate and characteristic temperature parameters are obtained. The kinetic parameters and mechanism functions of uncontrolled spontaneous combustion of coal gangue are solved by Achar differential method and Coats-Redfern integral method. During the test period, the maximum cooling range of a single hot rod is 33.4 鈩，

本文編號：1495514