LIMB Demonstration Project Extension and Coolside Demonstration

Abstract

This report presents results from the Limestone Injection Multistage Burner (LIMB) Demonstration Project Extension. LIMB is a furnace sorbent injection technology designed for the reduction of sulfur dioxide (S02) and nitrogen oxides (NO=) emissions from coal-fired utility boilers. The testing was conducted on the 105 MWe, coal-fired, Unit 4 boiler at Ohio Edison's Edgewater Station in Lorain, Ohio. In addition to the LIMB Extension activities, the overall project included demonstration of the Coolside process for SO= removal for which a separate report has been issued. The primary purpose of the DOE LIMB Extension testing, which began in April 1990, was to demonstrate the generic applicability of LIMB technology. The program sought to characterize the SO2 emissions that result when various calcium-based sorbents are injected into the furnace, while burning coals having sulfur content ranging from 1.6 to 3.8 weight percent. The four sorbents used included calcitic limestone, dolomitic hydrated lime, calcitic hydrated lime, and calcitic hydrated lime with a small amount of added calcium lignosulfonate. The original EPA project focused on tests with calcitic hydrated lime while burning a D 3.0 weight percent sulfur Ohio coal, although tests with the lignosulfonate-doped material were added after pilot studies appeared to show enhanced reactivity. The results indicated SO2 removal efficiencies of greater than 70 percent are possible while operating at a close approach to the adiabatic saturation temperature of the flue gas. Efficiencies on the order of 60 percent were found in tests without close approach operation. The results presented in this report include those obtained for the various coal/sorbent combinations. They further characterize the SO2 removal to be expected with and without humidification to close approach to saturation over a range of calcium/sulfur stoichiometries. The effects of injection at different elevations in the furnace are explored, and in the case of limestone as the sorbent, the influence of particle size distribution is quantified. This report also addresses the effects of the LIMB process on boiler and plant operations. The increased particulate loading in the boiler and downstream equipment has the greatest impact on operations. Without effective sootblowing, heat transfer rapidly degrades when the lime sorbents are used. Particulate removal equipment must be capable of handling the increased D°°°I 1! loading. Moreover, the quicklimecomponent of the ash requiresthat precautionarymeasures be taken to avoid and/or minimize potential difficultiesfrom steaming and high pH conditions in service I water when handling and transportingthe ash. B&W DRB-XCLTM low-NO= burnerswere used throughout the project as these had been installed as part of the original EPA LIMB demonstration. The report discussesthe resultant NO, emissioncontrol in light of such operationalparameters as load, excess air, and pulverizers/burners in service. These variables were monitored more carefully duringthe current dem...

Reduction of pulverized coal boiler's emissions through ReEngineered Feedstock™ co-combustion

“…Because of its wide availability and low cost, limestone (CaCO 3 ) is the sorbent the most studied and the most used in furnace sorbent injection [17], and was therefore a natural choice. However, its performances are limited in PCB environment because of the high temperature.…”