Radiation transport for MHD pollution control

A method for calculation of radiation cooling of MHD exhaust gases in a steam generator is given. A two-group radiation transport equation is derived which takes account of both an optically-thick diffusing component with an effective mean-free-path and an optically-thin component. The diffusing components cools the region near the wall making a radiation boundary layer. Real gas emissivities are used, based on known band profiles and strengths for the expected gas composition. Gas-dynamic effects are included and compressible and incompressible flows treated. Comparison is made with a simple, optically-thin calculation using radiation data of Hottel which gives results consistent with the average determined by the diffusion model. The radiation emission determines the gas cooling rate in the steam generator and, hence, the nitric oxide emission rate with stack gases. Results of a detailed gas-kinetic calculation based on two stage combustion show that for reasonable furnace size the NO emission rate is reduced below the corresponding EPA standard for coal combustion.