The Design Of Liquid Oxygen/LNG High Pressure Combustor

Based on the current energy and environmental issues,a new cycle with liquid-oxygen high-pressure direct-fired carbon capture has been produced.Liquid oxygen replaces the compressed air in the operation of the gas turbine.CO₂/H₂O mixed steam is produced by high-pressure combustion of liquid oxygen and LNG powers generation.Carbon dioxide is liquefied by cold energy of liquid oxygen and LNG after moisture is removed by expansion steam to achieve full capture,storage and use of carbon dioxide.Because the existing combustors can not meet the requirements of this new power cycle,this article carries out the preliminary design of the ultra-high pressure combustion combustor.Firstly,combustor design method,combustor design flow,and preliminary combustor parameters are established.The way to calculate thermodynamic parameters and transmission parameters under high pressure,as density,viscosity coefficient,heat conduction coefficient,and constant pressure specific heat,is using equation of state.The parameters fit the correlation of temperature parameters.A numerical model for non-premixed turbulent combustion with supercritical pressure is established.Secondly,the effect of pressure on the supercritical turbulent combustion process during the start-up of the combustor is discussed to provides reference data and guidance for the definition of overall combustor and nozzle size.The paper focuses on exploring the effect of different oxygen-fuel ratios?0.5,1,2?on the methane-liquid oxygen non-premixed turbulent combustion process.Results reveal that the effect of oxygen-fuel ratios on flame temperature and structure is similar under different pressures.At the oxygen-fuel ratio is 2,1,and 0.5,the flame becomes shorter and the maximum flame temperature increases as the pressure increases.When the oxygen combustion rate ratio is 0.5,the flame becomes the shortest.At the oxygen-fuel ratio is 2,1,and 0.5,the oxygen injection length decreases as the pressure increases.When the oxygen-fuel ratio is 0.5,the range of the high-temperature zone is the largest.When flame speed ratio is 1,flame length and flame width is suitable.The injection inlet diameter of the methane liquid oxygen is determined,and the length and diameter of the combustor are determined based on the flame length and axial velocity at oxygen gas speed ratio 1.Finally,the effect of combustor flame tube material on the divergence cooling flow heat transfer performance of multi-inclined holes is discussed to provide reference for combustor cooling structure.The paper discusses the effect of different materials?SiO₂ ceramic coating,Si₃N₄ high temperature ceramics and reinforced carbon-carbon composites?on the heat transfer performance of divergent cooling flow in oblique holes with different pore sizes?5mm,7mm,9mm?.The results reveal that the faster the wall temperature decreases,the stronger the cooling effect with increasing pore size.The greatest effect of pore size on the cooling effect is the SiO₂ ceramic coating.For SiO₂ ceramic coatings,Si₃N₄ high temperature ceramics,reinforced carbon-carbon composites,the average effect of the cooling surface of the film on the surface of the aperture of 9 mm is respectively increased by 32.9%,6.4%,and6.1%compared with the case of 5mm.When using Si₃N₄ high-temperature ceramics,the wall temperature is between986K-1983K at a hole diameter of 9mm.It is lower than the safe temperature of Si₃N₄ high temperature ceramics,this material can be used in the high temperature area of the combustor flame cylinder.When using reinforced carbon-carbon composites,the wall temperature is between 1048-2068K at 5,7 and 9mm apertures.It is lower than the safe temperature of reinforced carbon-carbon composites,this material can be used in the high temperature zone of the combustor flame tube to provide a reference for the practical application of the combustor.