United States Environmental Protection Agency Air and Energy Engineering Research Laboratory Research Triangle Park, NC 27711 Research and Development EPA/600/SR-93/064 August 1993 v^EPA Project Summary Proceedings: 1991 SO2 Control Symposium Brian K. Gullett These proceedings document the 1991 SO2 Control Symposium, held De- cember 3-6, 1991, in Washington, DC. The symposium focused attention on recent improvements in conventional sulfur dioxide (SOJ control technolo- gies, emerging processes, and strate- gies for complying with the Clean Air Act Amendments (CAAA) of 1990. It provided an international forum for the exchange of technical and regulatory information on SO2 control technology. More than 800 representatives of 20 countries from government, academia, flue gas desulfurization (FGD) process suppliers, equipment manufacturers, engineering firms, and utilities attended. In all, 50 U.S. utilities and 10 utilities in other countries were represented. In 11 technical sessions, speakers presented 111 technical papers on development, operation, and commercialization of wet and dry FGD, clean coal technologies, and combined sulfur oxide/nitrogen oxide (SO^NOJ processes. This Project Summary was developed by EPA's Air and Energy Engineering Research Laboratory, Research Tri- angle Park, NC, to highlight key topics of interest on SO2 control that are fully documented in a separate report of the same title (see Project Report ordering information at back). Introduction The Symposium, jointly sponsored by the Electric Power Research Institute (EPRI), the Air and Energy Engineering Research Laboratory of the U.S. Environ- mental Protection Agency (AEERL/EPA), and the U.S. Department of Energy (DOE), is held periodically to transfer technical information and advance technology de- velopment application for control of sulfur dioxide (SO2) emissions from fuel com- bustion. The proceedings from this Symposium are five volumes, containing 111 presented papers covering 14 technical sessions: Session Subject Area I Opening Remarks (EPRI, EPA, and DOE guest speak- ers) 1 Emission Allowance Panel Discussion 2 Clean Air Act Compliance Strategies 3A Wet FGD Process Improve- ments 3B Furnace Sorbent Injection 4A Wet FGD Design Improve- ments 4B Dry FGD Technologies 5A Wet FGD Full Scale Opera- tions 5B Combined SO,/NOX Tech- nologies 6A Wet FGD Operating Issues 6B Clean Coal Demonstrations/ Emerging Technologies Printed on Recycled Paper ------- 8A 8B Poster Session (papers on all aspects of SO2 control) Commercial FGD Designs FGD By-Product Utilization These proceedings also contain open- ing remarks by the co-sponsors and com- ments by the three guest speakers. The guest speakers were Shelley Fidler - As- sistant, Policy Subcommittee on Energy and Power, U.S. Congress; Jack S. Siegel - Deputy Assistant Secretary, Office of Coal Technology, U.S. DOE; and Michael Shapiro - Deputy Assistant Administrator, Office of Air and Radiation, U.S. EPA. Clean Air Act Compliance issues were discussed in a panel discussion on emis- sion allowance trading and a session on compliance strategies for coal-fired boil- ers. Key Points • To comply with Title IV of the CAAA in Phase I, wet limestone and lime FGD systems will dominate a very competitive scrubber market. By Phase II, a total of 40-50 GW of scrub- bing will be in place. • Additives are increasing wet FGD sys- tem performance to >95% SO2 re- moval. Methodologies are being de- veloped to evaluate an abundance of wet FGD design improvements. • The $5 billion Clean Coal Technology Program has demonstrated and is continuing to demonstrate the com- mercial feasibility of technologies that have already reached proof-of-con- cept stage. • In the area of dry FGD systems, fur- nace, economizer, and duct injection are low-capital-cost emerging tech- nologies for retrofit of older coal-burn- ing boilers. Newly developing simul- taneous SOj/NO,, technologies expand the choices available to boiler opera- tors and ease operational problems with a combined system. • In addition to SO2 control technolo- gies, the symposium highlighted the many uncertainties surrounding com- pliance with the CAAA. These unre- solved issues include EPA's pending decision on NOX regulation for Phase I Group 1 units under Title IV, visibil- ity, a short-term ambient air standard for SO2, air toxics, and air standards for NOX emissions in ozone nonattainmerit areas. Present operat- ing issues include continuous emis- sion monitoring systems, mist elimi- nator system problems, and acid mist emissbns. Key regulatory uncertain- ties include accounting issues, taxa- tion concerns, and planning questions. Several presenters encouraged ac- tive utility participation in the resolu- tion of many of these issues. Opening Remarks Since the previous SO2 Control Sympo- sium in May 1990, Congress passed the Clean Air Act Amendments of 1990. To comply with the CAAA, EPRI expects scrubbing of 12-15 GW of utility capacity in Phase I, a 40-50 GW scrubbing total by Phase II, and extensive coal switching in both phases. Wet limestone and lime FGD systems are dominating the market in Phase I, and limestone forced oxidation systems are the most often selected technologies. Ad- ditives and enhanced designs are increas- ing performance to >95% SO2 removal. Dry FGD systems are a niche market, and air toxics are becoming a factor in select- ing scrubbers because of potential up- coming air toxics legislation. Various unresolved issues will signifi- cantly impact how utilities control SO2. These issues include EPA's pending deci- sion on NOX regulation in Phase I, plume visibility, and a short-term ambient air stan- dard for SO2. One year after passage of the CAAA, numerous questions relating to the role of 50 to 70% removal technologies, coal cleaning versus control technologies, and emerging technologies still remain unan- swered. Many utilities have announced they may choose compliance strategies that rely on low-sulfur coal or fuel switch- ing and may defer a decision on technol- ogy options until the tougher Phase II requirements in the year 2000. Clean Air Act Amendments Overview Two featured luncheon speakers pro- vided overviews of the Clean Air Act Amendments of 1990. Shelley Fidler, As- sistant, Policy Subcommittee on Energy and Power, encouraged active participa- tion by all in the industry in shaping CAAA implementation. Michael Shapiro of EPA, characterized the CAAA as environmentally aggressive, the first use of a cap on total emissions, and a test of a novel market-based ap- proach to allowance trading. Emission Allowance Trading Utilities are reluctant to buy or sell emis- sion allowances, according to EPRI, until the rules are clearer and the market is favorable. Although there are no trades yet, many utilities are planning to trade if appropriate. Alice LeBlanc of the Environmental De- fense Fund stated that the CAAA man- dates tough environmental goals, introduces a market-based trading sys- tem, motivates innovation in the utility in- dustry, and sets a key precedent for future legislation. Craig Glazer, Chairman of the Ohio Pub- lic Utility Commission, suggests a proactive approach to promoting an active emission allowance trading market. He suggested that utilities follow a planning approach that includes listing all feasible plant op- tions, ranking these by cost-effectiveness, inputting them to a production costing model, and then calculating revenue re- quirements for each option. Compliance Strategies CAAA compliance strategies were dis- cussed from a variety of perspectives, in- cluding the impact of scrubbing in Phase I, roles of scrubbing and emission allow- ance trading, methodologies for determin- ing strategies, costs for use in these methodologies, and international impacts. C.E. Fink of Consolidation Coal Com- pany indicated that up to 50 % of total Phase I SO2 reductions could be achieved with scrubbing and gave reasons why scrubbers are a low-cost compliance strat- egy- Regarding the costs of various scrub- bing technologies, a recently completed EPRI-sponsored project updated the costs of 26 FGD processes to 1990 dollars and also analyzed the technical merit and com- mercial status of currently available and emerging SO2 control technologies. Future Issues Several issues will impact the way elec- tric utilities comply with the CAAA. These include air toxics, NOX emissions in ozone nonattainment areas, waste minimization, and water quality. Most of these will be the subject of legislation in the next few years. The CAAA requires several detailed studies of the risks associated with fossil- fuel combustion. Based on these studies, EPA will determine whether further con- trols are needed. Ongoing studies by EPRI, DOE, and others will provide information to assist in this evaluation of air toxics. New Developments In Wet FGD In the area of process improvements to wet FGD, increasing SO2 removal effi- ciency was the focus of several presenta- tions. In an attempt to dispel the negative connotation of using additives that is preva- lent in the industry, R.E. Moser of EPRI ------- provided an overview of the current status of additive use in wet FGD systems and the functions they may perform in future designs. The session on wet FGD design im- provements emphasized both increasing SO2 removal efficiency and reducing costs. Improvements in new as well as retrofit designs were discussed. EPRI is investi- gating a range of design options, includ- ing the use of trays and packing, additional liquid flow rate, and performance addi- tives, for limestone and magnesium-en- hanced lime systems to determine SO2 collection capability and relative costs. Wet FGD Operation Two presentations summarized wet FGD technology currently used in many operat- ing plants. A. Saleem of General Electric Environmental Services covered the de- sign and operation of single-train open spray tower FGD systems, and P. Rader of ABB Environmental Systems described the design of advanced limestone wet FGD systems in retrofit applications. While fu- ture operating issues include control of air toxics, present operating issues include continuous emission monitoring systems (CEMs), mist eliminator system problems, and acid mist emissions. Clean Coal Demonstrations/ Technologies In 1986, the U.S. DOE initiated the Clean Coal Technology (CCT) Program to demonstrate the commercial feasibility of technologies that have already reached the proof-of-concept stage. Status reports on several CCT projects were presented later in the afternoon. R. Bolli of Ohio Edison presented current design features and recent test results from various Ohio Edison CCT projects. Results from the Limestone Injection Multistage Burner (LIMB) extension test- ing at Edgewater were presented by T. Goots of B&W. LIMB combines furnace sorbent injection (FSI) of lime with humid if ication after the air heater and use of low-NOx burners to reduce both SO2 and NOX emissions. FSI, in which sorbent injected in the furnace reacts with SO2 and is removed by particulate controls, can achieve moderate SO2 reduction (ap- proximately 50%) at a cost per ton of sulfur removed claimed to be lower than for wet FGD. Dry FGD Technologies Dry FGD processes include FSI, duct injection, and spray drying (dry scrubbing). Some of these technologies can signifi- cantly reduce capital costs, compared to conventional wet scrubbing. Dry processes can be divided into two categories: highl- and low-temperature processes. High-Temperature Processes Two utility-scale generating unit appli- cations of FSI with low NOX burners (LIMB) were presented. One of these, LIMB, lo- cated at Ohio Edison's Edgewater Sta- tion, is discussed in the section on Clean Coal Technologies. The second, an EPA- sponsored LIMB installation at the 180- MW Yorktown Unit 2 of Virginia Power Company, was reviewed by J. P. Clark of ABB Combustion Engineering Systems. Clark detailed plans for an 8-month test scheduled for 1992. Low-Temperature Processes The Limestone Emission Control (LEG) process removes SO2 using a moving bed of quarry-sized limestone, as covered by M.E. Prudich of Ohio University. DOE's duct injection technology program , funded through the Pittsburgh Energy Technol- ogy Center, will result in a duct injection design handbook. The EPA-developed advanced silicate (ADVAGATE) technology is a lime-based, duct injection process, in which silica-con- taining ash is reacted with lime at modest temperature to remove SO2. EPA's C. Sedman outlined recent ADVACATE pro- cess optimization in a pilot plant and re- ported plans for a 10-MW field evaluation at TVA's spray dryer/ESP pilot plant at the Shawnee Test Facility in 1992. Combined SCyNOx Technologies EPRI has evaluated the potential for developing combined SOj/NOx technolo- gies to provide attractive alternatives to conventional wet FGD and selective cata- lytic reduction (SCR). For new plants, the NOXSO, Copper Oxide, Zinc Oxide, and SNOX processes were rated equivalent or preferable to wet FGD/SCR. Various combined SO2/NOX processes were also discussed. Pilot-scale results of a furnace urea/sorbent slurry injection tech- nology were reviewed by EPA's B. K. Gullett. This EPA-sponsored project dem- onstrated the successful combination of Ca-based sorbent injection and selective non-catalytic reduction (SNCR) technolo- gies in a slurry process. D. Helfritch of R- C Environmental Services & Technologies presented results of subscale tests for use in a proof-of-concept demonstration of an integrated dry injection process consisting of combustion modification using low NO, burners, dry injection of hydrated lime at the economizer, dry injection of sodium bicarbonate at the air heater exit for addi- tional SO2 and NOX removal, and flue gas humidification for ESP conditioning. Conclusion To comply with the CAAA in Phase I, wet limestone and lime FGD systems will dominate a very competitive scrubber mar ket. By Phase II, a total of 40-50 GW of scrubbing will be in place. The 1991 EPRI/EPA/DOE SO2 Control Symposium presented many improve ments in SO2 control technology that will help utilities cost-effectively attain these levels of scrubbing. Additives are increas ing wet FGD system performance to >95% SO2 removal. The $5 billion CCT Program has demonstrated and is continuing to demonstrate the commercial feasibility of technologies that have already reached proof-of-concept stage. In the area of dry FGD systems, fur- nace, economizer, and duct injection are low-capital-cost emerging technologies for retrofit of older coal-burning boilers. Dry technologies like EPA's ADVACATE, cur- rently undergoing larger scale demonstra- tion, show promise for >90% SO2 removai. Newly developing simultaneous SOg/NO, technologies expand the choices available to boiler operators and ease operational problems with a combined system. In addition to SO2 control technologies, the symposium highlighted the many un- certainties surrounding CAAA compliance. Various unresolved issues will significantly impact how utilities control SO2. These issues include EPA's pending decision on NOX regulation in Phase I, visibility, a short- term ambient air standard for SO2, air toxics, NOX emissions in ozone nonattainment areas, waste minimization, and water quality. Present operating is- sues include CEMs, mist eliminator sys- tem problems, and acid mist emissions. Key regulatory uncertainties include ac- counting issues, taxation concerns, and planning questions. Several presenters encouraged active participation in the reso- lution of many of these issues. •ffV.3. GOVERNMENT PRINTING OFFICE: 1993 - 750-07I/UO044 ------- Brian K. Gullett is the EPA Project Officer (see below). The complete report, entitled "Proceedings: 1991 SO2 Control Symposium, Vol- umes 1, 2, 3, 4, and 5," (Order No. PB93-196095/AS; Cost: $52.00; subject to change) will be available only from: National Technical Information Service 5285 Port Royal Road Springfield, VA 22161 Telephone: 703-487-4650 The EPA Project Officer can be contacted at: Air and Energy Engineering Research Laboratory U.S. Environmental Protection Agency Research Triangle Park, NC 27711 United States Environmental Protection Agency Center for Environmental Research Information Cincinnati, OH 45268 Official Business Penalty for Private Use $300 BULK RATE POSTAGE & FEES PAID EPA PERMIT No. G-35 EPA/600/SR-93/064 ------- |