Presentation on theme: "Performance and Costs of Mercury Control Technology for Bituminous Coals Performance and Costs of Mercury Control Technology for Bituminous Coals NC DAQ."— Presentation transcript:
Performance and Costs of Mercury Control Technology for Bituminous Coals Performance and Costs of Mercury Control Technology for Bituminous Coals NC DAQ Mercury and CO2 Workshop April 20, 2004 Raleigh, NC Michael D. Durham, Ph.D., MBA ADA-ES, Inc SouthPark Way, Unit B Littleton, CO (303)
Outline Mercury Emissions from Coal Fired Boilers Background on Control Technology Sorbent Injection for Controlling Hg Emissions Costs for Mercury Control Regulatory Parameters from a Control Device Perspective
PRS4003 Existing Source MACT Limits NOTE: Output-based standards are referenced to a baseline efficiency (35% for new units; 32% for existing units). Subcategory Hg (lb/TBtu) 1 Bituminous-fired2.0 Subbituminous-fired5.8
PRS4003 Mercury Emissions with Average Capture for Bituminous (46%) and Subbituminous (16%) Coals
PRS4003 Options Available for Reducing Mercury Emissions 1.Wet Flue Gas Desulfurization (FGD) Scrubbers. 2.Sorbent Injection. Novel approaches are not considered viable as time from development to market is too long
PRS4003 Control of Mercury in Wet FGD Scrubbers Oxidized Mercury is water soluble and can be captured in wet scrubbers. –Some captured mercury gets re-emitted. Elemental mercury cannot be captured by scrubbers.
PRS4003 Mercury Removal in Wet Scrubbers for Bituminous Coals Low correlation of existing data; difficult to predict the mercury removal that will be achieved in a WFGD
PRS4003 Enhancing Capture of Hg in Wet Scrubbers: Increase Amount of Oxidized Hg Coal Electrostatic Precipitator Wet Scrubber Oxidizing Chemicals SCR for NOx Oxidizing Catalysts
PRS4003 Status of Technologies for Oxidizing Mercury SCRs: –Documenting performance on full-scale installations. –Better performance on bituminous than subbituminous coals. –Possibility of aging effects. –Possibility of interferences from other chemicals. –Catalysts are being designed to reduce oxidation of SO 3 ; this may impact oxidation of Hg. Oxidizing Catalysts: –Pilot-scale testing under way. Oxidizing Chemicals: –Some very short-term full-scale tests. –Concerns with corrosion.
PRS4003 Sorbent Injection Mercury Control Technology
PRS4003 Coal-Fired Boiler with Sorbent Injection Sorbent Injection Ash and Sorbent ESP or FF Hg CEM
Activated Carbon Storage and Feed System
PRS4003 Powdered Activated Carbon Injection System
PRS4003 ADA-ES Hg Control Program: Phase I Full-scale field testing of sorbent-based mercury control on coal-fired boilers. Primary funding from DOE National Energy Technology Laboratory (NETL). Cofunding provided by: –Southern Company; –We Energies; –PG&E NEG; –EPRI; –Ontario Power Generation; –TVA; –FirstEnergy; –Kennecott Energy; and –Arch Coal.
PRS4003 Removal of Mercury Species with PAC on Bituminous Coal Bituminous with FF PARTICULATEOXIDIZEDELEMENTALTOTAL PAC Injection μg/m 3 μg/m 3 μg/m 3 μg/m 3 COHPAC Inlet COHPAC Outlet Removal Efficiency45.6% 85.7%99.3%90.6%
PRS4003 Cost and Performance of Sorbent-Based Mercury Control
PRS4003 Effect of Flue Gas Characteristics The capacity of sorbents to capture mercury decreases at higher temperatures. Chlorine and other trace acid gases play a significant role in the performance of PAC.
PRS4003 Adsorption Capacity vs. Temperature Equilibrium Adsorption Capacity - Darco FGD Temperature (F) g HgCl2 /g AC) (
PRS4003 Equilibrium Adsorption Capacities at 250°F Upstream and Downstream of SO 3 Injection
PRS4003 PAC Performance with ESPs: Effect of Trace Acid Gases
PRS4003 Sorbent Injection Upstream of a Wet Scrubber Injection of AC and capture in ESP will provide an additional mechanism to reduce mercury emissions. Oxidation of mercury produced by carbon could enhance capture in FGD. Decreased mercury levels in scrubber could reduce potential for reemission of elemental mercury from scrubber. Two DOE/Industry full-scale field tests are scheduled: –Georgia Power Yates; currently on-going, medium-sulfur bituminous coal; and –AEP Conesville; Spring 05, high-sulfur bituminous.
PRS4003 Ash Issues The mercury captured by PAC, LOI, and ash appears to be very stable and unlikely to reenter the environment. The presence of PAC will most likely prevent the sale of ash for use in concrete. Several developing technologies to address the problem: –Separation –Combustion –Chemical treatment –Non-carbon sorbents –Configuration solutions such as EPRI TOXECON
PRS4003 Alabama Power E. C. Gaston Unit MW firing a variety of low- sulfur, washed eastern bituminous coals. Particulate Collection: –Hot-side ESP; SCA = 274 ft 2 /kacfm –COHPAC baghouse Wet ash disposal to pond. Primary funding from DOE/NETL with cofunding provided by: –Southern Company –Duke Energy –Ontario Power Generation –TVA –Kennecott Energy –We Energies – EPRI – First Energy – Hamon Research-Cottrell – Arch Coal
PRS4003 Phase I Test Results Injection Concentration (lbs/MMacf) % Hg Removal
PRS4003 Year-Long TOXECON TM Test Conduct ~ 1 year demonstration of TOXECON TM (sorbent injection into COHPAC) for power plant mercury control. Determine design criteria and costs for new TOXECON TM systems. Determine balance-of-plant impacts.
PRS4003 Daily and Weekly Average Mercury
PRS4003 Impact of Injection on Performance Injection Concentration (lbs/MMacf) Average p/b/h
PRS4003 Phase I Test Results Injection Concentration (lbs/MMacf) % Hg Removal
PRS4003 Low Load/Low Flow Test Baseline conditions limit injection concentration. Test plan changed to accommodate real-life conditions. Current air-to-cloth ratio of 8.0 ft/min is too high for TOXECON TM. Low load test conducted to simulate operation at air-to-cloth ratio of 6.0 ft/min –APC arranged for 72 hours of operation at low, steady load.
PRS4003 Low Load Test: A/C = 6.0 ft/min
PRS4003 ACI Cost Estimates for Bituminous Coals Assumptions –250 MW Plant; 80% Capacity Factor Capital and Operating Costs for ESP –50-70% Hg Removal: PAC 10 lb/Macf –PAC Injection Equipment: $790,000 –Carbon costs: $2,562,000/yr Capital and Operating Costs for FF –Add COHPAC Fabric Filter at $50/kW: $12,500,000 –80-90% Hg Removal: PAC 3 lb/Macf –PAC Injection Equipment: $790,000 –Carbon costs: $769,000/yr
PRS4003 Costs of Mercury Control Depend on Plant Size Not on Amount Removed Costs of mercury control are unrelated to the amount of mercury captured –Sorbent Injection Technology –SCR/FGD –Catalytic Oxidation –Other Developing Technologies
PRS4003 Conclusions on ACI Performance AC injection can effectively capture elemental and oxidized mercury from bituminous coals. There will be difference in site to site performance of ACI due to differences in coal, equipment, and flue gas characteristics. Fabric filters provide better contact between the sorbent and mercury than ESPs, resulting in higher removal levels at lower sorbent costs. Long-term results are promising showing consistent Hg removal greater than 85%. New COHPAC fabric filters will have to be designed to handle higher loadings of PAC to insure high (>90%) mercury removal.
PRS4003 Commercial Status of Technology 1.Equipment Similar equipment has been used successfully in the waste industry to inject AC into flue gas. It has successfully been scaled up for full-scale utility applications. Operating continuously for nearly a year at Gaston. Three AC injections systems currently operating. 2.Supply of Activated Carbon and Other Sorbents Sufficient supply available to meet several State regulations. Additional production needed to meet Federal regulations. Tremendous progress being made with improved sorbents. 3.Performance Will vary with type of equipment (FF vs. ESP). Will vary from site to site due to flue gas characteristics (temperature, acid gases).
PRS4003 Availability of Activated Carbons Current excess capacity of AC production in Tons/year NORIT Americas: 22,500 Other US Suppliers: 40,000 Total US Excess Capacity 62,500 Donau (Germany)130,000 CarboChem (China) 60,000 Total Import Excess Capacity190,000 Total US and Import Excess Capacity252,500
PRS4003 Number of 250 MW Plants that Can Be Treated by Currently Available AC (out of 1100 in US) Excess CapacityESPsFF Tons/yr(50-70%) (70-90%) US AC62, Total US 252, Plus Imports Manufacturers plan to increase production to meet market demand, but only upon regulatory certainty.
PRS4003 Regulatory Parameters from a Control Device Perspective 1.Long term averaging 2.Dual Limit Removal Efficiency Emission Limit 3.Flexibility in Achieving Mercury Removal Accounts for site by site variation in performance Enhances cost effectiveness 4.Mechanism to Encourage Adoption
PRS4003 Long-Term Averaging Time will Allow Control Devices to Adapt to Variations in Coal and Operating Conditions
PRS4003 Decisions on Mercury Control with Flexibility in Achieving Reductions Utilities would have a significant economic incentive to put mercury control on units that are: Higher emitters Larger plants Therefore, a flexible approach would result in the greatest reduction in total mercury emissions while minimizing costs
PRS4003 Flexibility Would Provide a Framework for Fleet-wide Decisions on Mercury Control
PRS4003 Flexibility Would Help Address Plant by Plant Variations in Performance Guarantees
PRS4003 Early Adoption of Technology Provides Increased Experience Base To date, 8 full-scale field tests have been completed through funding from DOE-NETL, EPRI, Utilities, APC Vendors, and Coal Companies. An additional 12 field tests are planned for the next 2-3 years. Economic incentives for early compliance are needed to offset risks with new technology. This will increase the operational data base (different fuels and equipment), decrease uncertainty, solidify guarantees.