Flue Gas Recirculation in a Gas Turbine: Impact on Performance and Operational Behavior
Flue Gas Recirculation in a Gas Turbine: Impact on Performance and Operational Behavior
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燃气轮机中的烟气再循环：对性能和运行行为的影响
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
Eribert Benz
中科院分区：
文献类型：
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作者：
F. Sander;R. Carroni;Stefan Rofka;Eribert Benz
在接下来的几十年里，严格减少温室气体排放只有通过以下战略的贡献才能实现：生产效率、减少能源需求和从化石燃料发电厂捕获二氧化碳(CO2)。由于化石燃料发电厂占全球温室气体排放总量的25%[1]，因此捕获和储存这些发电过程产生的二氧化碳是值得的。对于天然气发电厂，燃烧后二氧化碳捕集是低排放发电厂最成熟的技术。二氧化碳的捕获是通过化学吸收发电厂废气中的二氧化碳来实现的。与燃煤电厂相比，将二氧化碳捕集应用于天然气联合循环发电厂(CCPP)的优势在于，参考循环(没有二氧化碳捕集)实现了较高的净效率。这远远超过了排气中二氧化碳浓度较低的缺点。烟气再循环(FGR)是指余热锅炉排出的烟气经过部分冷却后回馈到燃气轮机进气口。在这方面，FGR是有益的，因为可以显著增加二氧化碳的浓度，将减少流向二氧化碳捕获单元的体积流量，并且提高了具有二氧化碳捕获的CCPP的整体性能。本文研究分析了燃气轮机(GT)和联合循环电厂(CCPP)燃气轮机(GT)和联合循环电厂(CCPP)FGR的影响。此外，还研究了FGR对有无CO2捕集的CCPP的影响。再循环回燃气轮机的部分烟气需要进一步冷却，然后才能与环境空气混合。对烟气再循环率和温度的敏感性进行了研究。这两个参数都会影响燃气轮机的工作流体组成的变化、压缩机入口处的相对湿度以及对燃气轮机和CCPP的整体性能的影响。压缩机入口处的条件也决定了燃气轮机和水/蒸汽循环如何分别受到FGR的影响。对于燃烧系统而言，空燃比(AFR)是反映FGR对燃烧过程影响的重要参数。AFR表示燃烧过程与完全燃烧所需的化学计量(或技术)极限的接近程度。AFR越低，燃烧过程越接近化学计量极限。此外，对现有操作限制和总体操作行为的影响将在带有FGR的燃气轮机的操作概念的背景下进行调查和讨论。版权所有(2011)，由阿尔斯通技术有限公司提供。
The rigorous reduction of greenhouse gas emissions in the upcoming decades is only achievable with contribution from the following strategies: production efficiency, demand reduction of energy and carbon dioxide (CO2 ) capture from fossil fueled power plants. Since fossil fueled power plants contribute largely to the overall global greenhouse gas emissions (> 25% [1]), it is worthwhile to capture and store the produced CO2 from those power generation processes. For natural-gas-fired power plants, post-combustion CO2 capture is the most mature technology for low emissions power plants. The capture of CO2 is achieved by chemical absorption of CO2 from the exhaust gas of the power plant. Compared to coal fired power plants, an advantage of applying CO2 capture to a natural-gas-fired combined cycle power plant (CCPP) is that the reference cycle (without CO2 capture) achieves a high net efficiency. This far outweighs the drawback of the lower CO2 concentration in the exhaust. Flue Gas Recirculation (FGR) means that flue gas after the HRSG is partially cooled down and then fed back to the GT intake. In this context FGR is beneficial because the concentration of CO2 can be significantly increased, the volumetric flow to the CO2 capture unit will be reduced, and the overall performance of the CCPP with CO2 capture is increased. In this work the impact of FGR on both the Gas Turbine (GT) and the Combined Cycle Power Plant (CCPP) is investigated and analyzed. In addition, the impact of FGR for a CCPP with and without CO2 capture is investigated. The fraction of flue gas that is recirculated back to the GT, need further to be cooled, before it is mixed with ambient air. Sensitivity studies on flue gas recirculation ratio and temperature are conducted. Both parameters affect the GT with respect to change in composition of working fluid, the relative humidity at the compressor inlet, and the impact on overall performance on both GT and CCPP. The conditions at the inlet of the compressor also determine how the GT and water/steam cycle are impacted separately due to FGR. For the combustion system the air/fuel-ratio (AFR) is an important parameter to show the impact of FGR on the combustion process. The AFR indicates how close the combustion process operates to stoichiometric (or technical) limit for complete combustion. The lower the AFR, the closer operates the combustion process to the stoichiometric limit. Furthermore, the impact on existing operational limitations and the operational behavior in general are investigated and discussed in context of an operation concept for a GT with FGR.Copyright © 2011 by Alstom Technology Ltd.