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深部矿井煤炭−地热协同开采系统研究

Research on coal-geothermal collaborative exploration system in deep mines

  • 摘要: 在煤炭资源深部开采趋势下,矿井高温热害问题日益严重,引起矿井高温热害的热源实质为可持续利用的地热能,在进行煤炭开采的同时将深部矿井地热能提取并进行资源化利用,是建设绿色矿山、降低矿井碳排放的创新途径。总结了国内外深部矿产和地热能共采现状,从工艺流程和关键设备方面分析了煤炭−地热协同开采的可行性,最终提出一种煤炭−地热协同开采系统。该系统总体采用闭式循环,包括地面热能利用系统和井下取热系统,通过在预采煤层水平钻孔并布置同轴套管换热器提取煤层地热能,并由地面热泵机组将从井下开采的低品位地热能进行利用。秉承“先采热、后回采”的时间和空间协同原则,预先在回采工作面前向划分采热工作面,提出顺序采热、交替采热2种模式,确保采热过程对采煤过程无干扰。分析了空间协同设计、煤层钻孔、高效采热和智能监控调控等关键技术,对煤炭开采和地热能提取进行井下空间协同设计,提出基于煤层注水的同轴套管换热器布置工艺,使用快捷装配式同轴套管换热器可进行多种组合实现高效采热,构建智能监控调控平台并提出相关优化模型,构建取热量计算模型,提出智能控制采热方式。简化煤系地层传热过程,构建煤层采热传热模型,可根据回采工作面实际情况和出口风流参数对回采工作面采热能力进行计算评估。根据煤层采热传热模型,分析得出煤层初始温度、煤炭运输量、回采工作面出口风流温度、风流含湿量变化量是决定煤层采热量的关键参数。定义回采工作面风流含湿量不变且回采工作面出口风流等效温度不高于28 ℃时的采热量为煤层最大采热量。系统的应用将会使深部矿井热害资源化,不仅解决了煤炭开采热害问题,而且实现了深部矿井地热能综合利用。

     

    Abstract: Under the trend of deep mining of coal resources, the problem of high temperature heat damage in mines is becoming increasingly serious, the heat source that causes high temperature heat damage in mines is actually sustainably used geothermal energy, extracting and utilizing geothermal energy from deep mines while mining coal is an innovative way to build green mines and reduce mine carbon dioxide emission. This paper summarizes the current situation of deep mineral and geothermal energy collaborative exploration at China and abroad, analyzes the feasibility in terms of processes and key equipment and finally proposes a system of coal-geothermal collaborative exploration. The system adopts closed cycle mode, including ground heat utilization system and underground extracting system, drilling horizontal holes and installing coaxial casing heat exchangers at the coal to extract the heat, and utilization of the extracted low-grade geothermal energy through the heat pump on ground. Adhering to the principle of “mining heat first and then mining” in terms of time and space coordination, the thermal mining face is divided in front of the mining work in advance, and two modes of sequential and alternating thermal mining are proposed to ensure that the thermal mining process does not interfere with the coal mining process. Analyzed key technologies including spatial collaborative design, coal seam drilling, efficient heat extraction, and intelligent monitoring and control. Conducted underground spatial collaborative design for coal mining and geothermal energy extraction, proposed a coaxial casing heat exchanger layout process based on coal seam water injection. Multiple combinations of quick assembly coaxial casing heat exchangers can be used to achieve efficient heat extraction. Building an intelligent monitoring and control platform and proposed relevant optimization models, building a heat extraction calculation model and propose an intelligent control heat extraction method. Simplify the heat transfer process of coal formations, construct a heat transfer model for heat extraction from coal to calculate and evaluate the heat capacity of the mining face based on its actual situation and the outlet airflow parameters. According to the heat transfer model, the initial temperature of coal, the coal transportation volume, and the outlet air flow temperature through mining face are the key parameters that determine the heat extraction from the coal. The heat extraction is the maximum when the moisture content of the air flow of the working face remains unchanged and the equivalent temperature of the air flow at the outlet of the working face is not higher than 28 ℃. The application of this system will converting heat damage of deep mine to useful resources, which not only solves the problem of heat damage of coal mining, but also realizes the comprehensive utilization of geothermal energy in deep mine.

     

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