Recycle of Modified Fly Ash from Furnace Sorbent Injection

摘要

The paper discusses technical and economic studies to assess the impact of recycle on the furnace sorbent injection process. Levelized costs of various recycle schemes were compared to baseline (non-recycle) costs using the EPA LIMB Cost Model and the LIMB Recycle Model. Laboratory and pilot-scale tests were performed to evaluate the technical feasibility of the recycle schemes. Use of recycle to enable replacement of expensive hydrated lime sorbent with limestone suggested possible savings of 21 percent in 15-year levelized costs per ton of SO2 removed. The process may not be feasible, however, due to sorbent disintegration. Recycle with quicklime and hydrated lime as sorbents gave projected savings of up to $79 and $127 per ton of SO2 removed, respectively. Pilot-scale studies showed that 78-90 percent hydration of unused sorbent could be achieved in 30-263 minutes. Of the separation processes investigated, only cyclonic separation and steam elutriation were found to be feasible.