【作者】 成闪闪；

【导师】 查晓雄；

【作者基本信息】 哈尔滨工业大学 ， 土木工程， 2011， 硕士

【摘要】 随着环境恶化以及可持续发展概念的普及,二氧化碳作为导致环境温室效应的主要气源逐渐被大众视为主要环境污染物之一。如何利用及控制大气中二氧化碳含量成为当今炙手可热的课题。本文从节约能源及环境保护的角度出发,主要分超临界二氧化碳改造材料及地下封存两部分研究了土木行业对能源及环境的可能的贡献。根据A. Saetta的多孔材料温度、湿度及气体流动耦合的封闭微分方程组,本文首先建立了混凝土多孔砖自然碳化数值模型,并与牛荻涛碳化深度经验公式进行对比,验证了模型正确性后通过修正二氧化碳及混凝土相关参数进行了普通和再生骨料混凝土多孔砖超临界碳化的数值模拟,结果表明与多孔砖自然碳化不同,超临界碳化时多孔砖内二氧化碳含量不是碳化反应速度的控制因素;模型结果还表示多孔砖相对湿度对超临界碳化中碳化速度的影响远大于其对自然碳化速度的影响。碳化程度及截面平均抗压强度基本按负指数规律随时间延长而增长。本文也探讨了二氧化碳作为助燃剂的煤炭地下气化上覆岩层移动规律的研究,并在气化过程可行性得以验证以后进行了二氧化碳地下封存的数值模拟。首先进行了煤炭地下气化过程中纵截面水平向温度分布的数值模拟,结果表明地下温度场仅影响2米以内岩层性质。利用这一结果,本文模拟了浅埋煤层地下气化时空洞发展、煤层顶板移动及地表沉降,并与已有国外结果对比,二者吻合较好,验证了本文模型的正确性。之后通过加大煤层埋深,进行了深埋煤层地下气化过程的模拟,结果显示深埋煤层地下气化完成后的地表不均匀沉降仅为浅埋煤层地表不均匀沉降的7%,因此从岩层移动角度考虑,深埋煤层地下气化的安全性更高。最后本文利用深埋煤层以1m/天的燃烧速度气化完成后的模型进行了二氧化碳埋存的可行性研究,加入二氧化碳压力影响时,地表沉降会减小,因此二氧化碳地下封存可抵消部分煤炭地下气化引起的上覆岩层的移动,对地表建筑基础更有利。更多还原

【Abstract】 As the realization of deterioration of the environment and the spread of the idea of sustainable development, CO₂ has been treated as one of the pollutants to our environment due to its greenhouse effect. How to utilize and control the CO₂ content in the atmosphere has become a popular project. On the view of energy conservation and environment protection, this thesis mainly demonstrates the improvements of building materials and the underground sealing of CO₂, in order to make the possible contribution of civil industry on environmental protection and energy conservation.Based on the close differential equation set raised by Saetta about the coupling flow of temperature, moisture and gas in porous materials, this thesis develops the numerical model of natural carbonation of concrete porous brick first. After the result of the model has been proved by the experimental formula raised by Ditao Niu, this thesis develops the super-critical carbonation simulation on normal and recycled aggregates concrete porous brick separately by revising the relative parameters of CO₂ and concrete. The result demonstrates that the control factor of carbonation is not the CO₂ content in the brick, but the reaction velocity of CaCO3, which is different with the result of the natural carbonation. The result also shows that the influence of the relative humidity in the porous brick on the super-critical carbonation velocity is more significant compared with its influence on the natural carbonation. The carbonation degree and average pressure strength changes along the principle of negative exponent as time goes up.In the second part of this thesis, the move principle of the upper seam during the underground coal gasification using CO₂ as the ignite gas has been researched, and the simulation of the CO₂ underground storage has been represented after the possibility of UCG has been proved. This thesis first proceeds the numerical simulation of the longitudinal section temperature distribution, the result of which shows that the temperature field only influences the properties of rocks at the range of 2 meters. Based on this result, this thesis simulates the cavity development, the movement of the coal roof and the surface displacement during the shallow coal seam gasification. The result fits well with the existed result in Farhangi’s thesis, thus the model in this thesis is proved valid. The deep storage coal UCG has also been simulated in this thesis by adding the depth of coal seam to 1000 meters. The result presents that the nonuniform displacement of deep coal is only 7% to the displacement of superficial coal seam. Thus, in the view of the seam move, the safety of UCG in deep coal in higher than that in superficial coal. At last, this thesis gives the simulation of CO₂ underground storage on the basis of UCG at the gasification velocity of 1m/day. When the pressure of CO₂ is put on the cavity boundaries after UCG, the surface displacement is decreased. In the consequence, the underground storage of CO₂ is beneficial to surface building basement since the pressure of CO₂ can diminish part of the displacement caused by UCG.更多还原