本文選題：煤　切入點：降溫過程　出處：《西安科技大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：煤自燃的發(fā)展是一個復(fù)雜的物理和化學(xué)的動態(tài)過程。當煤發(fā)生自燃后,應(yīng)及時采取適當?shù)姆罍缁鸫胧?抑制煤自燃的發(fā)展。在降溫過程中需實時監(jiān)測火區(qū)的溫度以及氣體濃度等參數(shù),因此,對煤自然降溫過程的研究顯得尤為重要。為了研究煤自然降溫過程的自燃特性,本文通過程序?qū)嶒炑芯坎煌悍N在不同粒徑以及不同降溫方式下的自燃特性,分析粒徑和降溫方式對降溫過程氣體產(chǎn)物濃度的影響,根據(jù)CO濃度將降溫過程劃分為不同的階段,并進行動力學(xué)的分析,同時將升溫過程和不同降溫過程進行對比和分析。結(jié)果表明:煤自然降溫過程屬于一個非線性的動態(tài)過程。降溫過程中,實驗載氣中氧氣濃度越大,煤樣粒徑越小,煤樣生成的氣體產(chǎn)物濃度越大,生成C2H4氣體的最低溫度越低;通過CO濃度將不同降溫過程分成不同溫度階段,并計算出其活化能,表現(xiàn)為實驗煤樣變質(zhì)程度越高,活化能值越大;在相同實驗載氣的情況下,升溫過程相比于降溫過程中生成相同的氣體濃度(CO、C2H4和1/3焦煤CO2)時的溫度發(fā)生了一定的“滯后”;實驗煤樣為褐煤和無煙煤時,升溫過程相比于降溫過程中生成相同的CO2濃度時的溫度發(fā)生了一定的“提前”;褐煤和1/3焦煤的空氣降溫過程的耗氧速率大于空氣升溫過程的耗氧速率,無煙煤空氣升溫過程與空氣降溫過程的耗氧速率存在兩個交點。同時,通過自然發(fā)火實驗研究煤樣升溫過程和絕氧降溫過程中高溫點移動規(guī)律、氣體產(chǎn)物濃度以及自燃特性參數(shù)和極限參數(shù),并進行對比分析。結(jié)果表明:升溫過程和降溫過程高溫點的位置變化不完全重合;為消除降溫過程中漏風(fēng)量無法測量的因素,得到了單位流量耗氧速率、單位流量CO、CO2產(chǎn)生率以及單位流量最大、最小放熱強度的計算方法,其結(jié)果與程序升溫結(jié)果相同,證明了方法的可行性以及增加了升溫過程與降溫過程的可比性;自然發(fā)火升溫過程中,煤溫在50℃時,下限氧濃度、最小浮煤厚度和上限漏風(fēng)強度均達到最值,當浮煤厚度小于0.648m時,浮煤不會發(fā)生自燃現(xiàn)象;自然發(fā)火降溫過程中,煤溫在80℃時,下限氧濃度、最小浮煤厚度和上限漏風(fēng)強度均達到最值,當浮煤厚度小于0.384m時,浮煤不會發(fā)生復(fù)燃現(xiàn)象。因此,研究煤自然降溫過程特性在煤礦采空區(qū)煤自燃、封閉火區(qū)等實施滅火后,對指導(dǎo)煤降溫過程中煤溫以及氣體濃度的變化具有非常重要的意義。
[Abstract]:The development of coal spontaneous combustion is a complex physical and chemical dynamic process. In order to study the spontaneous combustion characteristics of coal, it is necessary to monitor the parameters of temperature and gas concentration in real time during the cooling process, so it is very important to study the natural cooling process of coal. In this paper, the spontaneous combustion characteristics of different coal types under different particle sizes and different cooling modes are studied by program experiments. The effects of particle size and cooling mode on the concentration of gas products in the process of cooling are analyzed. According to the concentration of CO, the cooling process is divided into different stages. The results show that the natural cooling process of coal is a nonlinear dynamic process. The higher the oxygen concentration in the experimental gas is, the higher the oxygen concentration is during the cooling process. The smaller the particle size of coal sample is, the greater the concentration of gas product is, and the lower the minimum temperature of C _ 2H _ 4 gas is, and the activation energy is calculated by dividing the different cooling process into different temperature stages by CO concentration. The higher the metamorphic degree of experimental coal is, the greater the activation energy is. The temperature of the heating process is lagged when the same gas concentration is produced during the cooling process, and the experimental coal samples are lignite and anthracite, while the temperature of the coking coal is lower than that of the coking coal with the same concentration of CO _ (2) H _ (4) and 1/3 coking coal (CO _ (2)). The oxygen consumption rate of the air cooling process of lignite and 1/3 coking coal is higher than that of the air temperature rising process, and the oxygen consumption rate of the air cooling process of lignite and 1/3 coking coal is higher than that of the air heating process. There are two intersections between the oxygen consumption rate of anthracite air heating process and the air cooling process. At the same time, the moving law of high temperature points in the process of coal sample heating and adiabatic cooling is studied by natural combustion experiment. The gas product concentration, spontaneous combustion characteristic parameters and limit parameters are compared and analyzed. The results show that the change of the position of the high temperature points in the heating process and the cooling process is not completely coincident, and in order to eliminate the factors that the air leakage can not be measured during the cooling process, The calculation methods of oxygen consumption rate per unit flow rate, CO _ 2 production rate per unit flow rate and maximum and minimum exothermic intensity per unit flow rate are obtained. The results are the same as those of programmed heating. It is proved that the method is feasible and the comparability between the heating process and the cooling process is increased, the lower oxygen concentration, the minimum floating coal thickness and the upper wind leakage intensity can reach the maximum value when the coal temperature is 50 鈩，

本文編號：1586372