【作者】 李勇；

【导师】 章名耀； 肖军；

【作者基本信息】 东南大学 ， 热能工程， 2006， 硕士

【摘要】 燃煤联合循环发电技术是洁净煤发电新技术的发展方向之一。但燃煤释放出的碱金属蒸汽易形成污垢,而且会引起燃气轮机叶片的高温腐蚀。因此有规定,高温燃气轮机入口烟气中碱金属蒸汽浓度一般不能超过0.024×10^-6,但实际中却往往比许可值高出一至几个数量级。研究燃煤过程碱金属赋存迁移规律将对燃煤联合循环发电技术的发展起到相当重要的促进作用。基于化学平衡体系下的最小Gibbs自由能原理,利用Aspen Plus过程模拟软件,建立了燃煤过程模型和碱金属的赋存、迁移模型。模拟得出了煤中氯含量、反应温度与压力、Ca/S、空煤比等影响因素下碱金属赋存、迁移的规律,同时将添加脱硫剂前后不同影响因素下的模拟结果作了对比,并对碱金属达标含量所对应的工况进行了分析预测。为了研究燃煤过程碱金属赋存、迁移规律,并检验数值模型的正确性,设计了燃煤试验台和碱金属采样装置,通过试验手段获取了不同煤种不同工况下碱金属赋存、迁移的数据。将试验结果和相对应的工况计算值相对照后发现,计算值和试验值有较好的吻合度,特别在1130 K附近。最后结果表明:常压条件下,要使徐州烟煤燃烧后烟气中气态碱金属排放含量达到0.024×10^-6需将燃烧温度定在1044 K,而对于煤样GBW11119和GBW11120,为达到同样的气态碱金属含量,燃烧温度需分别定在1003 K和973 K;当压力为1×10⁶Pa时,三煤种燃烧温度需分别定在1082 K、1040 K和1000 K时,烟气中气态碱金属含量才能降到0.024×10^-6。这些数据为燃煤联合循环发电的优化设计和制定有效的碱金属排放控制策略,以及为生产运行提供了相当重要的参考依据。对于碱金属盐在受热面上沉积问题的研究也有借鉴意义。更多还原

【Abstract】 Coal-fired combined cycle power generation technology is one of the trends of clean coal power generation technology. However, alkali vapors easily deposited on heat exchanger surfaces to lead to slagging, and in gas turbines they caused high-temperature corrosion of turbine blades. Although tolerance limit of alkali vapors in the flue gas was usually given under 0.024 ppm by weight at the inlet of gas turbines, it was actually one or more orders of magnitude than that of the limit. Research for the occurrence and migration mechanism of alkali metal will play an important role in the development of coal-fired combined cycle power generation technology.Based on the Gibbs free energy minimization principle of chemical equilibrium, two models of coal-fired process and alkali occurrence and migration were developed using Aspen Plus software. Conclusions were drawn about the occurrence and migration mechanisms of alkali under the factors of Cl-containing in coal, reactor temperature and pressure, Ca/S, the ratio of air and coal, etc., and the results for adding limestone compared with those without limestone. Moreover, the conditions for limit level of alkali vapors were predicted.For studying and validating the occurrence and migration models of alkali, equipments for coal combustion and alkali sampling were designed and got the data of alkali occurrence and migration for different coals and under different conditions. After comparing the results of experimentation with those of computing, two results were approach, especially near 1130 K. It was found that under an atmospheric pressure, the amount of alkali vapors was decreased to 0.024 ppm by weight in 1044 K for Xuzhou coal, and for coal GBW11119 and coal GBW11120 the temperature should be increased to 1003 K and 973 K to the same level, respectively. While the reactor pressure was 10~6 Pa, the temperature should be1082 K, 1040 K and 1000 K for these coal samples, respectively. The results provided an important reference for the design of Coal-fired combined cycle power generation, the plan of alkali control and produce operation. Meanwhile, it is important for studying alkali slagging on the heat surface.更多还原