OCR Text |
Show where Fc = mols / hr calcium in feed lime FN = mols/hr sodium in humidification water R = mols /hr c calcium in recycle feed RN = mols/hr sodium in recycle feed RS = mols / hr sulfur in recyc Ie feed The recycle data in the figure are those from both the 1 st and 2nd successive pilot recycle runs. The once-through data in the figure were calcualted using the once-through correlation derived for Black River lime (Equation 4). The somewhat lower activity of the recycle sorbent may be largely due to the fact that some of the available calcium in the recycle material had been converted to CaC0 3 , a relatively inactive Coolside sorbent. For example, for the recycle sorbent feed to the first set of recycle runs (waste from once-through runs), about 10% of the total available calcium in the recycle sorbent (i.e., all Ca not reacted with sulfur) was in the form of CaC0 3 • This indicates that some Ca (OH) 2 was converted to CaCO 3 in the oncethrough runs or during storage of the waste ash for recycle. There was, however, little additional carbonation of the sorbent observed in the successive recycle runs. Sorbent recycle significantly increased the total solids loading of the flue gas. At a fresh CatS ratio of 1/1, a fresh Na/Ca ratio of 0.2 and 3.4 grains / scf fly ash, the loadings were 6.0, 9.4, 12.3 and 17.0 grains/scf at recycle ratios of 0 (no recycle), 0.5,1.0 and 1.8, respectively. The amount of recycle possible at a given installation will depend on ESP capacity and hopper unloading capacity. COOLSIDE WASTE CHARACTERIZATION The following Coolside waste properties were determined by laboratory tests. 14 |