Modeling and comparison of different syngas cooling types for entrained-flow gasifier

A three-dimensional numerical model has been developed for studying the multiphase flow and heat transfer process in the syngas cooler. The realizable k−ε turbulent model and discrete random walk (DRW) model were adopted to simulate the gas phase and particle phase flow fields, respectively. The discrete ordinate model (DOM) was applied to solve the radiative heat transfer equation, and the gas radiative properties were calculated by weight-sum-of-gray-gases model (WSGGM). The ash particle radiative properties were also considered in the radiative heat transfer calculation. The convection heat-transfer between the gas phase and discrete phase is also considered. The flow field and temperature distribution results are in good agreement with the experimental data. Firstly, the results indicate that the RSC should be the better choice for integrated gasification combined cycle (IGCC) power plant. For cooling-syngas quenching cooler, the outlet region has higher risk of fouling and slagging because the outlet gas and particle temperature are about 940 °C, and exceed the criteria temperature 760 °C (suggested in the literature). Secondly, when the inlet velocity and flow rate of the quenching gas are fixed, the more the quenching gas inlets are, the better the flow field and temperature field are. A recirculation region with the diameter about 1.5-2.0 m is formed in the center of the cooler under the quenching gas profile, and the intensity of the reflux flow increases with the number of quenching gas inlets. The particles are rapidly quenched when the particle flow through the quenching gas profile. Furthermore, the temperature of the quenching gas, and the temperature of the water in the tubes of membrane wall also have important effect on the temperature field in the RSC.