OCR Text |
Show for the runs with Mississippi lime. The one run conducted at 29°F approach was not used in deriving the above correlations. The correlation equations are of the same form in the two correlation variables as the equations used for Black River lime. RECYCLE SIMULATION TEST WITH BLACK RIVER LIME The pilot recycle simulation test confirmed the significant enhancement of sorbent utilization efficiency by sorbent recycle in the Coolside process. Substantial enhancement was possible because the recycle sorbent was only slightly less active than fresh hydrated lime on the basis of available calcium and sodium. Based on pilot test results, it is estimated that after steady-state recycle is established, system (humidifier + baghouse) S02 removals with Black River lime would be 50 and 54% at 1.0 and 1.8 recycle ratios, respectively, at 1/1 fresh Ca IS and 0.2/1 fresh Na/Ca and 25°F approach. Recycle ratio, R, is defined as (Ib recycle sorbent)/(lb fresh lime and fly ash). In a once-through run at the same fresh feed conditions, 111 CalS and 0.2/1 Na/Ca, and 25°F approach, the observed system removal was only 41%. To attain 54% S02 removal with Black River lime without recycle would require a 1.4/1 fresh CalS and 0.2/1 fresh Na/Ca mol ratio, based on the correlation developed in the once-through simulation test. I n the recycle simu lation tests, steady-state continuous recycle was simulated by making successive sets of pilot runs with batchwise recycle. Fresh lime and recycle sorbent were simultaneously fed to the pilot humidifier. For the first set of recycle runs, the recycle sorbent was the waste ash collected from previous once-through simulation runs with Black River lime. In the second set of recycle runs in the succession, the recycle sorbent for a given run was the baghouse ash from the previous recycle run at the same test conditions. The recycle ratio (R) was held constant between successive runs, thus sol ids loading was also roughly constant. By conducting the runs in this manner, the overall sorbent utilization and the S02 removal approach 11 |