In order to achieve near-zero pollution emissions, the integration of pre-combustion carbon capture technology in integrated gasification combined cycle systems is considered to be one of the most feasible methods. When hydrogen or hydrogen-rich gas is fed into the gas turbine as a fuel, it faces the test of tempering problems. Tempering is an inherent problem in lean premixed combustion systems. It means that the flame that should have stabilized inside the flame tube propagates upstream into the premixed section.
According to the different causes of tempering, there are four main types of tempering: tempering of the boundary layer, tempering of the overall flow, tempering caused by thermoacoustic oscillations, and backing of Combustion Induced Vortex Breakdown. CIVB tempering is the main tempering form in swirling premixed combustion. In addition, hydrogen fuel is more prone to CIVB tempering due to its high flame propagation speed, wide flame stability limit, short auto-ignition delay time and other combustion characteristics and limited diffusion of thermophysical combustion characteristics.
Recently, researchers from the Institute of Engineering Thermophysics of the Chinese Academy of Sciences, through a combination of numerical simulations and experiments, have comprehensively analyzed the influence of structural parameters and operating parameters on the CIVB tempering, and found that the cyclone structure, premixed section structure, and air inlet temperature The fuel composition is the main factor affecting the CIVB tempering. Each parameter acts on the CIVB tempering by changing the flow field distribution and the flame characteristics.
Based on the above, the mechanism and process of tempering are explored. The CIVB tempering route is divided into three parts: the occurrence of vortex shedding constitutes the flow field of the CIVB tempering; the flame propagates upstream and stabilizes in the broken vortex. The flame path of CIVB tempering occurs; the irreversible energy loss caused by vortex shedding makes the differential pressure of tempering driving force decrease significantly. The inability to maintain the change of flow field path and flame path constitutes the feedback route of CIVB tempering. The three routes are closely integrated to jointly promote the occurrence of CIVB tempering. Since the pressure difference is the driving force behind the CIVB tempering, any change that can increase the pressure difference will promote the occurrence of CIVB tempering. Therefore, from the perspective of the tempering mechanism, the pressure difference can be weakened to suppress the tempering. occur.
This research was supported by the Director's Fund and related results have been published in "China Science: Science and Technology".
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