煤炭地下气化覆岩温度和裂隙的试验与数值模拟研究

发布时间：2018-03-08 16:04

本文选题：地下气化　切入点：温度场　出处：《中国矿业大学(北京)》2017年博士论文　论文类型：学位论文

【摘要】：煤炭地下气化技术是一种可以将煤转换成可燃气体的化工技术,是国家提倡的洁净有效利用煤炭资源的先进技术。煤炭地下气化集建井、采煤、地面气化三大工艺为一体,变传统的物理采煤为化学采煤,省去了庞大的煤炭开采、运输、洗选、气化等工艺的设备,具有安全性好、投资少、效益高、污染少等优点,深受世界各国的重视,被誉为第二代采煤方法。与传统采煤和地面气化相比,煤炭的地下气化技术有以下优势:可以回收传统方法开采不经济和无法开采的煤炭资源;由于煤炭无须人工开采,地下气化最大限度的减少了矿工的健康和安全问题;减少了固体废物排放很少;减少了对社会经济的影响;投资省,煤气成本低。国家计委、国家经贸委、国家煤炭工业局、国家科技部等都对煤炭气化技术制定了“十五”期间的发展规划、纲要、计划,提出要推进煤炭气化技术的开发和应用,继续做好煤炭地下气化试验,探索煤炭开发和利用的新途径,引进国外先进的煤炭气化技术。煤炭地下气化开采完成以后,将会形成巨大的燃空区域,改变顶板的支撑条件,使围岩的应力状态和岩石的强度发生改变,进而在围岩中产生裂隙带,裂隙带的产生直接对燃空区围岩的稳定性和渗透性产生影响。经过地下水长期的浸泡和淋溶,灰渣中的有害有机物和微量元素就会溶解于水中,通过导水裂隙带进入到含水层中,从而引起地下水质的污染。近年来,尽管人们对燃空区的上覆岩层破坏规律做了不少理论上的研究,但是大都直是停留在应力-应变的角度来讨论气化煤层上覆岩层的破坏规律。对于燃烧高温和上覆岩层破坏之间的关系的解释还很少。因此,建立气化高温作用下的力学模型,模拟气化采场上覆岩层的破坏规律,并根据上覆岩层的破坏规律提出气化研究区的安全生产和施工措施具有非常重要的意义。论文以新奥集团乌兰察布市玫瑰营矿为研究对象,对研究区所取的岩石试件进行热物理试验和力学试验,通过实验室试验研究了煤层顶底板不同岩性岩石在常温到1000℃的温度条件下的热物理性质(密度,比热容,导热系数等),建立了气化煤层顶底板不同岩性岩石的热物理性质(密度,比热容,导热系数等)随温度变化的函数关系式。根据拟合的热物理参数随温度变化的函数关系式,建立COMSOL Multiphysics温度场概念模型,并根据各种岩石热物理参数随温度变化的曲线方程和温度场控制方程模拟了煤炭气化过程中的温度场,研究了在气化过程中温度场随燃烧长度变化的分布情况。通过试验研究了煤层顶板和底板的主要岩层顶板细砂岩、顶板砂质泥岩、顶板泥岩、底板细砂岩和底板泥岩岩石试件在常温下的力学性质,所获的力学参数(弹性模量、泊松比、抗压强度、抗剪强度、抗拉强度、内摩擦角、粘聚力)。参考力学参数随温度变化的研究成果,建立FLAC3D数值模型,结合气化过程中温度场的变化情况对气化煤层覆岩的裂隙场进行了模拟研究。煤炭地下气化开采完成以后,将会形成巨大的燃空区域,改变顶板的支撑条件,使围岩的应力状态和岩石的强度发生改变,进而在围岩中产生裂隙带,裂隙带的产生直接对燃空区围岩的稳定性和渗透性产生影响。经过地下水长期的浸泡和淋溶,灰渣中的有害有机物和微量元素就会溶解于水中,通过导水裂隙带进入到含水层中,从而引起地下水质的污染。针对这一污染现象,提出了燃空区注浆充填的治理建议。论文得到主要研究成果如下:1.通过对研究区资料的收集,确定研究区的地理位置以及交通状况,然后对研究区的区域地质概况做了简单的总结。研究区地层由老到新主要有:中太古界集宁(岩)群上部(Ar2j2)及下部(Ar2j1)、中生界侏罗系上统火山岩段(J32)、新生界古近系渐新统呼尔井组(E3h)、新近系中新统汉诺坝组(N1h)、新近系上新统宝格达乌拉组(N2b)、第四系全新统(Qh l)、(Qh al+pl)。研究区所在的内蒙古自治区集宁煤田玫瑰营子矿区内共发育断层7条,DF1~DF7,均为正断层,对煤炭地下气化所在的研究区地层及煤层影响不明显,这是煤炭地下气化的可行性的先决条件。研究区内赋存1#和2#两层煤,其中2#煤层为煤炭地下气化的目标煤层,煤层的厚度较大,是煤炭地下气化的可行性的物质基础。2.通过实验室试验研究了煤层顶底板不同岩性岩石在常温到1000℃的温度条件下的热物理性质(密度,比热容,导热系数等),拟合了热物理参数随温度变化的曲线方程,建立COMSOL Multiphysics温度场概念模型,并根据各种岩石热物理参数随温度变化的曲线方程和温度场控制方程模拟了煤炭气化过程中的温度场分布情况。在初始燃烧阶段,煤层燃空区范围很小,煤层顶底板的温度基本相等都保持在最大值1000℃,温度以热传导的方式向围岩四周扩散,当燃烧长度L=100m时,燃空区左端煤壁的温度接近于岩层的初始温度20℃。当燃烧长度L=100m时,达到最大,煤层顶板20.5m的范围内温度大于20℃,煤层底板23.1m的范围内温度大于20℃。3.通过试验研究了煤层顶板和底板的主要岩层顶板细砂岩、顶板砂质泥岩、顶板泥岩、底板细砂岩和底板泥岩岩石试件在常温下的力学性质,所获的力学参数(弹性模量、泊松比、抗压强度、抗剪强度、抗拉强度、内摩擦角、粘聚力)对于研究燃空区顶板覆岩的破坏规律,以及裂隙带的发育规律具有十分重要的意义。4.根据气化燃烧煤层泥岩顶板的力学参数随气化高温变化而改变的性质规律和气化过程中的气化温度在顶板的传播分布规律,建立FLAC3D力学模型。依据4条基本假设,通过改变泥岩顶板力学参数的方式来反演极高温度下的气化过程。对气化结束时和气化结束5年后两种情况下的模拟结果每10m为一组进行对比分析,相同位置处在气化结束5年的模拟结果中,燃空裂隙高度会有不同程度的增高。同时,两种情形下的燃空裂隙高度增量受煤层的气化厚度影响最为明显。通过运用Surfer11绘制两种情况下燃空裂隙发育范围和高度对比图,在气化燃空区的前段,气化裂隙带的高度逐渐增加,并都在距离气化起始位置60 m处出现最大值,裂隙高度超过40 m的区域都集中在气化燃空区的前段。在气化结束5年后,燃空裂隙高度超过35m的范围明显向前推进了。5.煤炭地下气化开采完成以后,将会形成巨大的燃空区域,改变顶板的支撑条件,使围岩的应力状态和岩石的强度发生改变,进而在围岩中产生裂隙带,裂隙带的产生直接对燃空区围岩的稳定性和渗透性产生影响。经过地下水长期的浸泡和淋溶,灰渣中的有害有机物和微量元素就会溶解于水中,通过导水裂隙带进入到含水层中,从而引起地下水质的污染。针对这一污染现象,提出了燃空区注浆充填的治理建议。
[Abstract]:Underground coal gasification technology is a kind of coal can be converted into combustible gas chemical technology, advanced technology is the country to promote the clean and efficient use of coal resources. Coal underground gasification in mine construction, coal mining, ground gasification technology three as a whole, change the traditional physical coal mining coal mining chemical, eliminates the need for extensive coal mining transport, washing, gasification process equipment, has good safety, less investment, high efficiency, less pollution and so on, by the world attention, known as the second generation of mining methods. Compared with the traditional coal mining and underground gasification, underground coal gasification technology has the following advantages: the traditional method of mining recovery can not the economy and not due to coal mining of coal resources; mining underground gasification without manual, to minimize the health and safety of miners; reduce the solid waste emissions reduced to the social economy is small; The influence of gas; investment, low cost. The State Planning Commission, the State Economic and Trade Commission, the State Bureau of coal industry, the State Ministry of science and technology of coal gasification technology developed during "fifteen" development plan, program, plan, put forward to promote the development and application of coal gasification technology, continue to do the exploration of underground coal gasification test. A new way of coal development and utilization of coal gasification technology, the introduction of foreign advanced. After the underground gasification of coal mining is completed, will form a huge change in the fuel air area, roof support conditions, the rock stress state and rock strength change, resulting in fracture zone in the surrounding rock, the fractured zone directly influence on the stability of goaf surrounding rock and gas permeability. After long term groundwater soaking and leaching, harmful organic matter in ash and trace elements will be dissolved in water, the water flowing fractured zone Into the aquifer, which caused by underground water pollution. In recent years, while doing a lot of research on the theory of damage to the overlying strata of combustion space area of the people, but the most direct is to stay in the stress-strain angle to discuss the failure law of the overburden on the gasification of coal seam on the relation between combustion. High temperature and overburden failure explanation is rarely. Therefore, the mechanics model is established under the action of high temperature gasification, gasification simulation of mining overburden failure law field, has very important significance and put forward the gasification of area according to the failure law of the overburden of the safe production and construction measures. According to the new Austrian group in Wulanchabu the city rose camp mine as the research object, the study area of rock specimen thermal physical test and the mechanical test, through laboratory tests on coal seam roof and floor of different rocks at room temperature to 1000 DEG C The thermal physical properties of temperature conditions (density, specific heat capacity, thermal conductivity, thermal physical properties) established the gasification coal seams of different rocks (density, specific heat capacity, thermal conductivity) relation with temperature changes. According to the functional relation of the thermal physical parameters of fitting with the temperature changing, establish the conceptual model of COMSOL Multiphysics temperature field, and according to the thermal physical parameters of all kinds of rocks with the temperature change curve equation and the temperature field control equation to simulate the temperature field of coal gasification process, gasification process in the temperature field distribution with the combustion length change was studied. Through the tests of coal seam roof and floor of the main roof fine the roof of sandstone, sandy mudstone, fine sandstone and mudstone roof, floor and floor mudstone rock specimens under normal temperature and mechanical properties, the mechanical parameters (elastic modulus, Poisson's ratio, compressive strength Degree, shear strength, tensile strength, friction angle, cohesion). Research of mechanical parameters with the temperature change, the FLAC3D model is established, combined with the change of the temperature field in the gasification process of coal gasification of overlying rock fissure field were studied. After the completion of the mining of underground coal gasification, combustion will be formed the empty area is huge, change the supporting conditions of roof, the surrounding rock stress state and rock strength change, resulting in fracture zone in the surrounding rock, the fractured zone has direct combustion on the stability of goaf surrounding rock permeability and generation influence. After long term groundwater soaking and leaching of harmful organic matter, ash and trace elements will be dissolved in water into the aquifer through the water flowing fractured zone, which caused by underground water pollution. The pollution phenomenon, the cavity grouting treatment recommendations. The main research results are as follows: 1. by analyzing the data collected in the research area, geographical location and traffic conditions, then the regional geology of the study area were briefly summarized. The strata in the study area are mainly from the old to the new in the Archean Jining group (rock) (Ar2j2) (Upper and lower Ar2j1), Mesozoic Jurassic volcano rock section (J32), Cenozoic Paleogene Oligocene call Seoul well group (E3h), Neogene Miocene Hannuoba group (N1h), Neogene new Tongbao group (N2b), Al ula quaternary Holocene (Qh L (Qh). Al+pl). The study area is located in the Inner Mongolia Autonomous Region Jining coal rose Ying Zi within the mining area were developed in 7 faults, DF1~DF7, are normal faults, influence on strata and coal research area of underground coal gasification is not obvious, it is the prerequisite for the feasibility of underground coal gasification. Study on the occurrence of 1# and 2# in the region of two layers coal, The 2# coal seam underground coal gasification target coal seam, coal seam thickness, is the material basis of.2. feasibility of underground coal gasification by laboratory experimental study on coal seam roof and floor rock in different thermal physical properties of room temperature to 1000 DEG C under the temperature conditions (density, specific heat capacity, thermal conductivity, heat equation) the physical parameters were fitted with the temperature changing, establish the conceptual model of COMSOL Multiphysics temperature field, and according to the thermal physical parameters of all kinds of rocks with the temperature change curve equation and the temperature field control equation to simulate the temperature distribution of coal gasification process. In the initial stage of combustion, coal burning range of goaf is very small, the temperature is basically the same seam the top and bottom are kept to a maximum of 1000 DEG C, spread to the surrounding rock around the temperature the heat conduction method, when the length of L=100m combustion, coal mined out area at the left end of the temperature is close to the wall In the initial formation temperature of 20 degrees Celsius. When the combustion length L=100m, maximum temperature range of coal seam roof in 20.5M is greater than 20 DEG C, the temperature range of coal seam floor in 23.1m is greater than 20 DEG.3. are studied through the experiment of coal seam roof and floor of the main roof roof sandstone, sand mudstone, mudstone roof, floor fine the sandstone and mudstone floor rock specimens under normal temperature and mechanical properties, the mechanical parameters (elastic modulus, Poisson's ratio, compressive strength, shear strength, tensile strength, friction angle, cohesion) for the study of ignition failure law of goaf roof, and crack zone development law with gasification temperature the nature of law and the gasification process is of great significance to.4. according to the mechanical parameters of coal gasification and combustion with high temperature gasification mudstone roof and the changes in the distribution law of main roof, the establishment of FLAC3D model on the basis of the 4 force. A basic assumption, by changing the mechanical parameters of mudstone roof to inversion of high temperature gasification process. At the end of the end of the gasification and gasification simulation results after 5 years, two cases of each 10m as a group for comparative analysis, the same position in the gasification end simulation results of 5 years, the fuel air gap height there will be increased in different degrees. At the same time, two cases of fracture height increment by the fuel air gasification of coal seam thickness effect is most obvious. Through the use of Surfer11 to draw the two case the fuel air fractured range and high contrast map, in the gasification cavity of the preceding paragraph, the height of the fractured zone of gasification increases gradually, and have a maximum value at a distance of 60 m gasification starting position, fracture height of more than 40 m areas are concentrated in the front section of the gasification combustion space area. In the 5 years after the end of the gasification range, the fuel air slit height of more than 35m was pushed forward. After the.5. underground coal gasification mining is completed, will form a huge change in the fuel air area, roof support conditions, the rock stress state and rock strength change, resulting in fracture zone in the surrounding rock, the fracture zone has direct influence on the stability of goaf surrounding rock and gas permeability through long term groundwater. The soaking and leaching of harmful organic pollutants in ash and trace elements will be dissolved in water into the aquifer through the water flowing fractured zone, which caused by underground water pollution. The pollution phenomenon, the cavity grouting treatment recommendations.

【学位授予单位】：中国矿业大学(北京)
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TD84

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