Gas and particle flow characteristics in the gas reversing chamber of a syngas cooler for a 300 MWe IGCC process

The gas reversing chamber (GRC) is the top part of a syngas cooler in the Shell coal gasification process, in which the quenched syngas flowing from the gasifier is turned downward into evaporator channels. Using computational fluid dynamics (CFD), this study investigated the detailed gas/particle flow and heat transfer characteristics in the GRC of an integrated gasification combined cycle (IGCC) process with 300 MWe capacity for operational loads between 50 and 100%. The gas flow rapidly changed its direction to downward after impinging onto the wall opposite to the inlet. This led to the formation of a higher velocity region along the opposite side, increasing the gas flow rate in the outer channel of the evaporator. In contrast, a region with low velocity below 2 m/s developed towards the inlet side above the evaporator, which may lead to the significant deposition of fly slag particles onto the structural elements. Larger wall heat flux appeared along the main gas stream with a maximum of 180 kW/m² at full load. Convection accounted for about 70% of the total heat transfer rate, of which the coefficient was correlated to Nu = 8.778 Re^0.435Pr^0.3. Many particles impinged onto the wall along the main gas stream, especially at the joint connecting the transfer duct and the GRC. However, erosion by fly slag was not expected to be significant, mainly due to the reduced gas velocity at the high operating pressure (43 bar).