Ren Yang

Experimental study on chemical recuperation using hybrid dielectric barrier discharge-catalytic methane-steam reforming

Hybrid dielectric barrier discharge-catalytic steam reforming is proposed here for use in chemically recuperated gas turbines, so as to be compatible with the low-temperature exhaust heat from turbines. Four different types of reactor were designed for comparison, and extensive experiments were performed to evaluate the exhaust heat recovery in terms of effective carbon recovery rate, methane conversion, fuel heating value increase rate, and total enthalpy increase rate. The effect of methane space velocity and reactor wall temperature on methane conversion have been analyzed. The results showed that, for any reactor, there was an optimum methane space velocity for the most heat recovery. With increasing wall temperatures, the parallel synergistic reforming technology induced more methane conversion than the other reactors. Under the same input power, parallel synergistic reactors could recover more exhaust heat than the sum of catalyst-only and plasma-only reactors, with a relative total enthalpy increase as much as three times the sum of the latter two. Moreover, the parallel synergistic reforming technology resulted in a higher relative total enthalpy increase for reformed gas at low temperatures. These results demonstrate that parallel synergistic reforming technology is a promising technology to significantly recover exhaust heat under different working conditions.

Analysis of Turbulence Models in Numerical Simulation of Combustion Chamber

Several turbulence models were analyzed in this paper for the chemically recuperated gas turbine (CRGT) combustor and numerical simulation of the combustor’s flow fields using these turbulence models was carried out with the aid of CFD method and finally the contrastive analysis was made. Realizable k-e and RNG k-e turbulence models, PDF combustion model and the SIMPLE algorithm method were adopted in the numerical simulation. Through comparison of key influencing factors of the combustor such as flame length, position of the high temperature zone, wall temperature and evenness of exit temperature field, it could be concluded that the Realizable k-e turbulence model demonstrates better performance with high quality of convergence precision and evenly distributed parameters that meet the design requirements better.Copyright

Fuel prereforming and combustion characteristics study of chemically recuperated gas turbine

The chemically recuperated gas turbine cycle testing platform was designed and built based on theoretical research and experimental study, which included the dual-stage flash evaporation, the diesel steam reformer, and the dual-fuel combustion system. In this paper, an experimental study on the oil (C7H16) prereforming performance is analyzed and the relative increment of the equivalent calorific value is 46.2%. Combustion characteristics are calculated with oil and reformed gas and the results show that main combustion zone temperature drops from 2280 to 1910u2009K, which leads the ultra-low NO emissions of 1.8u2009ppm. The flame is stable using reformed gas and the wall temperature is low, but the nonuniformity of outlet is relatively high. Thermal efficiency of combustion is more than 99% even at low load condition.

Feature-Section-Criterion for Predicting Lean Blowout and Comparison Research

Lean blowout (LBO) plays an important role in combustor performance. A new method named Feature-Section-criterion (FSC) for predicting the LBO of annular combustor has been put forward and expounded in this paper. A CFD software FLUENT has been used to simulate the combustion flow field of an annular combustor. The process of blowout and effects of flow split among swirlers and primary holes have been researched by using of FSC. The result shows that the predictions of FSC are in agreement with corresponding experimental data. So this method for predicting lean blowout is reliable and can be used for engineering applications.Copyright

Kinetic Effects of Non-Equilibrium Plasma-Assisted Methane Steam Reforming on Heat Recovery in Chemically Recuperated Gas Turbine

Plasma is proposed as a prospective tool for chemical heat recovery process without restriction from reaction temperature. The author designed DBD catalytic reactors and carried out extensive experiments to investigate methane conversion and products yield and analyze the effect laws of steam to methane ratio, resident time and reaction temperature on methane steam reforming (MSR). Based on extensive experimental studies of steam reforming, a detailed reaction mechanism for the plasma-assisted MSR was developed and evaluated by comparison of experimentally derived and numerically predicted conversion and products yield. The comparisons showed the kinetic model well predicted methane conversion and products yield in different operating conditions. By employing the kinetic model and path flux analysis module the kinetic effects of low temperature non-equilibrium plasma assisted CH4 steam reforming on the methane conversion was studied without catalyst. The results showed that CH3 recombination was the limiting reaction for CO production; meantime O was the critical species for CO production. By adding Ni catalyst can reduce methyl recombination and promote hydroxyl into oxygen, which is beneficial to heat recovery. The proposed research ensures the effect laws and characters of MSR by plasma, and contribute to improve the objective products concentration and furthermore the energy efficiency.Copyright