Characterization and re-use potential of by-products generated from the Ohio State Carbonation and Ash Reactivation (OSCAR) process

Abstract

Two novel sorbents (i.e. “regenerated sorbent” and “supersorbent”) for dry flue gas desulfurization were tested, and by-products characterized, using a pilot-scale version of the Ohio State Carbonation and Ash Reactivation (OSCAR) process. The main elements of the process consisted of sorbent production, a riser reactor, cyclone and baghouse. Trace elements, including As, Se and Hg, were found at higher levels in the OSCAR solid by-products (in both the cyclone and baghouse) compared to traditional lime spray dryer (LSD) ash. Polycyclic aromatic hydrocarbons (PAHs) detected on solid by-products were primarily small molecular weight compounds at low concentration (e.g., μg/kg). Small particulates (⩽3 μm) that escaped from the cyclone and were captured by the baghouse showed higher trace element concentrations, possibly due to the lower operating temperature and greater specific surface area of solids in the baghouse. Operating conditions including flue gas flow rate and sorbent injection rate influenced the levels of trace elements and PAHs in OSCAR by-product material. Capture of PAHs was observed to increase with Ca concentration in experiments using supersorbent injection. However, possible release of PAHs occurred with regenerated sorbent injection. The concentrations of trace elements in leachate for all OSCAR cyclone samples tested were below Resource Conservation and Recovery Act limits. The concentrations of most trace elements in OSCAR by-product were also below the limits regulated in the EPA 503 Rule except As and Se. The similarity in the physical and engineering properties of OSCAR cyclone samples to natural cohesive soils suggests that this material can be utilized in a variety of construction, reclamation, and agricultural applications.