Absolute radiant heat flow

Absolute radiant heat flow The radiant energy emitted per unit area in one direction. 

One cautionary note should be kept in mind when using Eqs. (42)-(45) and (71) to calculate radiative heat transfer in FFB. The bed s absolute temperature 1), is normally assumed to be uniform across the bed and is used as the source or sink temperature in Eqs. (42) and (43). This assumption may be inappropriate in those cases in which a dense aimular region of particles shields the FFB wall from the bulk bed. In sueh situations, it is the average temperature of the particles in the annular layer that should be taken as the source/ sink temperature for ealeulation of radiant heat flux to/from the wall. This requires a mass and heat balance analysis for the material flowing in the annulus, and the reader is referred to Chapter 19 for necessary hydrodynamic models. 

The increased combustion air flow was needed not for combustion, but to transfer heat from the radiant section (firebox) to the convective section. This is what we call heat balancing. In this situation, oxygen requirements to reach absolute combustion become irrelevant as we are now operating with a very plentiful supply of oxygen. 

---