Research On Design And Performance Of Dual Fuel Nozzle With Steam Injection From Gas Channel

As an advanced cycle,chemically recuperated cycle has the advantages of high energy efficiency and low emissions.The working characteristics of chemically recuperated cycle determine its combustor has the function of gas/liquid dual fuel combustion and steam injection combustion,which requires the nozzle have the function of oil injection,steam injection,dual fuel injection and reformed gas injection.So,it takes a very important role in chemically recuperated gas turbine combustor design and operation to research duel fuel nozzle technology deeply.After injected into the combustor from gas channel of dual fuel nozzle,steam forms a shielding layer between oil and air and thus affects the mixing and combustion between oil and air,which can easily cause flameout phenomenon in combustor.Under high steam/carbon ratio condition,as low calorific value gas,the mass flow rate of reformed gas is large and the flowfield is difficult to organize,which will lead to some problems such as low combustion efficiency,extended flame length,worst outlet temperature field uniformity and overheating nozzle head.The phenomena and problems need to be studied and sovled urgently.Therefore,based on the requirement of in situ replacement of nozzle,the research work has been carried out as follows:(1)For the antetype oil combustor,the parameters related to the combustion flowfield were obtained and organization method of flowfield was analyzed by numerical simulation method in combustor design condition.For the chemically recuperated cycle combustor,based on the requirement of the oil mass flow rate and atomization performance,the dual-orifice pressure-swirl atomizer was selected for the oil channel of the dual fuel nozzle,and the structure size of the oil channel was calculated using empirical coefficient method.The performance of the oil channel has met the combustor design requirments.(2)The effects of injection scheme of reformed gas on combustion flowfield have been studied.Firstly,for the antetype axial swirl hole type dual fuel nozzle used in experimental condition,the reformed gas combustor performance and flowfield charateristics were numerically studied under antetype oil combustor design condition.The results show that the recirculation zone structure in combustor head has been affected by the flow of reformed gas.Secondly,according to the axial and radial injection scheme of gas fuel,the effect of the swirl number,outlet method,nozzle installation position of reformed gas for axial injection scheme and the injection angle,injection velocity,nozzle installation position of reformed gas for radial injection scheme on main parameters of combustion flowfield was analyzed,which could provide the basic method for the design of dual fuel nozzle.(3)The multi-streamline control scheme of reformed gas combustion flowfield was proposed.According to the scheme,based on the oil channel structure,the above basic method was used to design the gas channel.Multi-streamline control of reformed gas combustion flowfield was achieved through triple-injection scheme of gas channel.And then the problems of low combustion efficiency and worsening outlet temperature field uniformity were solved.The temperature of nozzle head was reduced.(4)The nozzle structure was optimized by orthogonal numerical test method and the optimum structural parameters under antetype oil combustor design condition were obtained.At the same time,based on the research results about the effect of reformed gas mass flow rate,a new type of dual fuel nozzle structure was designed and the problem of in situ replacement of nozzle was overcome.(5)The effect of steam mass flow rate on the combustion flowfiled in combustor was studied numerically.The reasons for combustor flameout were analyzed and the steam injection flameout limit bodundaries under different conditions were obtained.The results show that the steam injection flameout limit boundary can be widen 38.3% under antetype oil combustor design condition for the multi-stage dual fuel nozzle,in comparison with the modification axial swirl hole type dual fuel nozzle.The steam injection flameout limit boundary increases with the incrase of the combustor condition.(6)The numerical simulation on combustor flowfield was carried out with different fuel combination models and overfueling conditions.The parameters related to the combustion flowfield for different fuel combination models and effect of fuel mass flow rate on combustor performance was obtained.The research can provide a guideline for combustor operation.