【作者】 李扬；

【导师】 王巍；

【作者基本信息】 大连理工大学 ， 动力工程（专业学位）， 2015， 硕士

【摘要】 在当今世界寻求能量的高效利用、环境的友好相处大格局下,燃气-蒸汽联合循环以其高效率、低排放的优良特性受到越来越多的关注和发展。联合循环由燃气轮机顶循环和余热锅炉与蒸汽轮机共同构成的底循环组成,针对已定燃气轮机的联合循环,底循环系统的集成匹配及其变工况研究具有重要意义。本文研究内容是“基于某重型燃机的燃气-蒸汽联合循环系统设计平台开发”项目的重要组成部分。根据某型燃机的设计工况排气参数,建立了单压、双压无再热、双压再热、三压无再热、三压再热五种底循环系统流程模型。基于热力学第一定律,以底循环功率Pst最高为目标函数,对五种流程蒸汽参数进行了详细的匹配研究,得出了蒸汽压力的匹配规律。在最优匹配结果的基础上,增加约束条件,得到系统综合分析下的设计参数。并比较讨论了五种流程综合分析下的循环性能特性。最后,以三压无再热底循环参数匹配结果作为设计条件,建立底循环系统流程的变工况计算模型,开展了底循环流程各节点参数的变工况趋势分析。结果发现,随着燃机功率的下降,高压、低压省煤器接近点温差降低,出现了零和负值,造成了省煤器出口水的汽化。针对低负荷时省煤器出现的汽化现象提出了两种解决方案,即重新设计底循环节点温差和接近点温差,以及改进底循环流程结构,分析了两种方案对于联合循环底循环性能的影响。本文针对燃气-蒸汽联合循环系统设计工况和变工况的研究成果为底循环系统设计和参数匹配提供了有意义的指导。更多还原

【Abstract】 Under the circumstance of seeking for high efficient energy use and environmental friendly development in today’s day and age, Gas-Steam Combined Cycle (GSCC) draws more and more attention due to its advantages of high efficiency and low pollution, and has witnessed a huge development in recent years. The GSCC is composed of the top cycle system (gas turbine) and the bottom cycle system (heat recovery steam generator and the steam turbine). The integrated matching and research on the off-design of the bottom cycle system of GSCC is significantly based on gas turbine exhaust parameters.The research content of this paper is an important part of a project named "The development of design platform of the GSCC system based on a heavy gas turbine".Based on a certain gas turbine exhaust parameters at design condition, five kinds of bottom system models were established, which are single pressure, dual pressure without reheat, dual pressure with reheat, triple pressure without reheat, triple pressure with reheat. Then according to the First Law of Thermodynamics, detailed research on the matching of the steam parameters of five kinds of processes was carried out by setting the bottom cycle power Pst as the objective function. As a result, the matching rules of steam pressure was obtained. After that, on the basic of the optimal matching results, comprehensive analysis design parameters of the system was obtained by increasing constraint conditions. In addition, comparing and discussing the performance characteristics of the five kinds of processes under the comprehensive analysis design was carried out.Finally, with the triple pressure without reheat bottom cycle comprehensive analysis design parameters as the design condition, the off-design model was established, then carried out the trend analysis of bottom cycle system key parameters at off-design condition. The results showed that as the decline of gas turbine power, high pressure and low pressure approach temperature difference reduced to zero or negative, and caused the evaporation of the economizer exit water. Concerning the vaporization in the economizer working in low load, two solutions were presented:the change of design parameters at design conditions and the improvement of the process structure of the bottom cycle system. Meanwhile, the performance changes of the bottom system with different gas turbine conditions were analyzed under those two solutions. The research results of GSCC at design and off-design conditions provided a significance guidance of bottom cycle system design and parameters matching.更多还原