Pilot-Scale Evaluation Of Advanced Solvents For CO2 Capture From Coal-Fired Utilities

In 1992, international concern about climate change (a change to Earth\u27s climate, especially those produced by global warming) led to the United Nations Framework Convention on Climate Change (UNFCCC). The ultimate objective of that convention was the stabilization of greenhouse gas concentrations in the atmosphere at a level that mitigates anthropogenic interference with the climate system (1). There has been a growing concern about global climate change which scientists believe is (arguably) caused mainly by anthropogenic emission of greenhouse gases (GHGs) into the atmosphere. The overall goal of this work was to evaluate next generation solvents at a pilot scale level to determine the advantages and disadvantages these advanced solvent have over the current industry standard. To accomplish this goal a pilot scale system was designed and fabricated on the back end of the Energy and Environmental Research Center\u27s Combustion Test Facility. The system was used to evaluate six solvents which included Hitachi\u27s H3-1, MDEA/Piperazine, Huntsman\u27s Jeff Treat XP, MEA and two others. Because of the proprietary nature of these solvents not all information can be shared. It was determined that advanced solvents are the best available technology for implementing CO2 capture at the large scale. Advanced solvents will be the technology that will make it to the market place sooner than other technologies due to the long time use of amine solvents in the oil and gas industry for their removal of CO2. For the case of postcombustion capture, the main conclusions are that 90% CO2 capture can be met with MEA and advanced solvents. The EERC system was able to capture at least 90% of the CO2 present in the flue gas for each advanced solvent and the baseline MEA. Results of the testing indicate that the use of advanced solvents, such as H3-1, can reduce the cost of capture considerably. Data from the advanced solvents and MEA tests conducted show that for similar test conditions, MEA required about 10-40% more regeneration energy input to achieve 90% CO2 capture than the advanced amine-based solvents. H3-1 required the lowest heat input (~1475 Btu/lb CO2), and the reboiler duty for MDEA+PZ was ~1600 Btu/lb CO2. The regeneration energy requirement for MEA was estimated to be in the range of 1775-1940 Btu/lb CO2 captured. The MEA case required a 30% to 50% higher solvent flow rate than H3-1 to attain 90% CO2 capture for a given amount of treated flue gas. Conversely, tests on MDEA+PZ showed a solvent usage about 135% higher than MEA to reach 90% capture. Consequently, use of H3-1 for a large-scale process could lead to significant economic benefits over MEA and MDEA+PZ. Lower solvent flow rates require smaller pumps and less energy to pump the solvent through the columns. Advanced solvents show promise, but improvements will still need to be made to reduce capital and operating costs to make the technology economically feasible for today\u27s market. Advanced contactors and solvent promoters will be technologies that may enable these solvent to become more economically favorable

JV Task 106 - Feasibility of CO2 Capture Technologies for Existing North Dakota Lignite-Fired Pulverized Coal Boilers

The goal of this project is to provide a technical review and evaluation of various carbon dioxide (CO{sub 2}) capture technologies, with a focus on the applicability to lignite-fired facilities within North Dakota. The motivation for the project came from the Lignite Energy Council's (LEC's) need to identify the feasibility of CO{sub 2} capture technologies for existing North Dakota lignite-fired, pulverized coal (pc) power plants. A literature review was completed to determine the commercially available technologies as well as to identify emerging CO{sub 2} capture technologies that are currently in the research or demonstration phase. The literature review revealed few commercially available technologies for a coal-fired power plant. CO{sub 2} separation and capture using amine scrubbing have been performed for several years in industry and could be applied to an existing pc-fired power plant. Other promising technologies do exist, but many are still in the research and demonstration phases. Oxyfuel combustion, a technology that has been used in industry for several years to increase boiler efficiency, is in the process of being tailored for CO{sub 2} separation and capture. These two technologies were chosen for evaluation for CO{sub 2} separation and capture from coal-fired power plants. Although oxyfuel combustion is still in the pilot-scale demonstration phase, it was chosen to be evaluated at LEC's request because it is one of the most promising emerging technologies. As part of the evaluation of the two chosen technologies, a conceptual design, a mass and energy balance, and an economic evaluation were completed

JV Task 107- Pilot-Scale Emission Control Technology Testing for Constellation Energy

An Indonesian, Colombian, and Russian coal were tested in the Energy & Environmental Research Center's combustion test facility for their performance and an evaluation of mercury release and capture with selected additives in both electrostatic precipitator and baghouse configurations. Sorbents included the carbon-based materials NORIT DARCO Hg, Sorbent Technologies B-PAC and B-PAC LC, STI Rejects provided by Constellation Energy, and Envergex e-Sorb, along with ChemMod's high-temperature additive. Each coal was evaluated over several days and compared. Ash-fouling tests were conducted, and mercury levels were monitored using continuous mercury monitors (CMMs). The Ontario Hydro mercury sampling method was also utilized. The Indonesian coal had the lowest ash content, lowest sulfur content, and lowest energy content of the three coals tested. The Colombian coal had the highest mercury content and did contain a significant level of selenium which can interfere with the ability of a CMM to monitor mercury in the gas stream. All sorbents displayed very favorable results. In most cases, mercury removal greater than 86% could be obtained. The Indonesian coal displayed the best mercury removal with sorbent addition. A maximum removal of 97% was measured with this coal using Envergex's carbon-based sorbent at a rate of 4 lb/Macf across an electrostatic precipitator. The high ash and selenium content of the Colombian coal caused it to be a problematic fuel, and ash plugging of the test furnace was a real concern. Problems with the baghouse module led to limited testing. Results indicated that native capture across the baghouse for each coal type was significant enough not to warrant sorbent addition necessary. The fouling potential was the lowest for the Indonesian coal. Low sulfur content contributes to the poor potential for fouling, as witnessed by the lack of deposits during testing. The Russian and Colombian coals had a much higher potential for fouling primarily because of their high ash contents, but the potential was highest for the Colombian coal. Of the three coals tested, the Colombian would be the least desirable

JV Task 122 - Assessment of Mercury Control Options for the San Miguel Electric Cooperative Power Plant

In the United States, testing has been under way at electric coal-fired power plants to find viable and economical mercury control strategies to meet pending regulations. San Miguel Electric Cooperative (SMEC) engaged the Energy & Environmental Research Center (EERC) through a request for proposal (RFP) to perform research tests to evaluate sorbent-based technologies at its coal-fired San Miguel Generating Station to identify possible technology options that could be used by SMEC to meet the mercury reduction requirements of future U.S. federal standards. The goal of the testing was to target a mercury removal of {ge}90%. The EERC has successfully field-tested several sorbent-based technologies in previous projects that offer promise and potential to achieve a target removal of {ge}90%. Based on these field test results, yet recognizing that fuel type and plant operating conditions affect mercury capture significantly, the EERC proposed research tests to evaluate potential sorbent-based technologies provided by Norit Americas and the EERC that could potentially meet SMEC's mercury control objectives. Over the period of May through mid-June 2008, the EERC tested injection of both treated and nontreated activated carbon (AC) provided by Norit Americas and sorbent enhancement additives (SEAs) provided by the EERC. Tests were performed at San Miguel Unit 1 (450 MW) and included injection at the inlet of the air heater (AH) (temperature of 720 F). The test coal was a Texas lignite fuel with an average moisture content of 31.19%, an ash content of 26.6%, a heating value of 5,094 Btu/lb, a sulfur content of 2.7%, and a mercury concentration of 0.182 ppm, all reported on an as-received basis. Pilot-scale testing results identified DARCO{reg_sign} Hg-LH, SEA2 + DARCO{reg_sign} Hg, and the ChemMod sorbents as technologies with the potential to achieve the target mercury removal of {ge}90% at the full-scale test. Mercury concentrations were tracked with continuous mercury monitors (CMMs) at the electrostatic precipitator (ESP) inlet (ESP In), scrubber inlet, and scrubber outlet of San Miguel Unit 1, and a dry sorbent trap method was used to take samples periodically to measure mercury concentrations at the each of the CMM sampling locations described above. A limited number of Ontario Hydro (OH) measurements were also conducted. Removal efficiencies were calculated from mercury-in-coal values to scrubber out CMM values. Sorbent trap samples taken at the each sampling location outlet were found to be fairly consistent with CMM values. A maximum mercury removal of 78.5% was achieved with the SEA2 + DARCO Hg sorbent combination at injection rates of 50 ppm and 4 lb/Macf, respectively. An injection rate of 4 lb/Macf for DARCO Hg-LH and DARCO Hg resulted in mercury removals of 70.0% and 64.2%, respectively. These mercury reduction values were achieved at full load and at stable plant operating conditions. Scrubber reemission was observed during sorbent injection and had a significant effect on coal to scrubber out mercury removal values. When the sorbents were injected into San Miguel Unit 1 at the AH inlet, no effects on unit operations were observed. ESP performance throughout the test period was fairly steady, with only one minor breakdown. However, it should be noted that test durations were short

Enhancing Carbon Reactivity in Mercury Control in Lignite-Fired Systems

This project was awarded through the U.S. Department of Energy (DOE) National Energy Technology Laboratory Program Solicitation DE-PS26-03NT41718-01. The Energy & Environmental Research Center (EERC) led a consortium-based effort to resolve mercury (Hg) control issues facing the lignite industry. The EERC team-the Electric Power Research Institute (EPRI); the URS Corporation; the Babcock & Wilcox Company; ADA-ES; Apogee; Basin Electric Power Cooperative; Otter Tail Power Company; Great River Energy; Texas Utilities; Montana-Dakota Utilities Co.; Minnkota Power Cooperative, Inc.; BNI Coal Ltd.; Dakota Westmoreland Corporation; the North American Coal Corporation; SaskPower; and the North Dakota Industrial Commission-demonstrated technologies that substantially enhanced the effectiveness of carbon sorbents to remove Hg from western fuel combustion gases and achieve a high level ({ge} 55% Hg removal) of cost-effective control. The results of this effort are applicable to virtually all utilities burning lignite and subbituminous coals in the United States and Canada. The enhancement processes were previously proven in pilot-scale and limited full-scale tests. Additional optimization testing continues on these enhancements. These four units included three lignite-fired units: Leland Olds Station Unit 1 (LOS1) and Stanton Station Unit 10 (SS10) near Stanton and Antelope Valley Station Unit 1 (AVS1) near Beulah and a subbituminous Powder River Basin (PRB)-fired unit: Stanton Station Unit 1 (SS1). This project was one of three conducted by the consortium under the DOE mercury program to systematically test Hg control technologies available for utilities burning lignite. The overall objective of the three projects was to field-test and verify options that may be applied cost-effectively by the lignite industry to reduce Hg emissions. The EERC, URS, and other team members tested sorbent injection technologies for plants equipped with electrostatic precipitators (ESPs) and spray dryer absorbers combined with fabric filters (SDAs-FFs). The work focused on technology commercialization by involving industry and emphasizing the communication of results to vendors and utilities throughout the project

JV Task - 129 Advanced Conversion Test - Bulgarian Lignite

The objectives of this Energy & Environmental Research Center (EERC) project were to evaluate Bulgarian lignite performance under both fluid-bed combustion and gasification conditions and provide a recommendation as to which technology would be the most technically feasible for the particular feedstock and also identify any potential operating issues (such as bed agglomeration, etc.) that may limit the applicability of a potential coal conversion technology. Gasification tests were run at the EERC in the 100-400-kg/hr transport reactor development unit (TRDU) on a 50-tonne sample of lignite supplied by the Bulgarian Lignite Power Project. The quality of the test sample was inferior to any coal previously tested in this unit, containing 50% ash at 26.7% moisture and having a higher heating value of 5043 kJ/kg after partial drying in preparation for testing. The tentative conclusion reached on the basis of tests in the TRDU is that oxygen-blown gasification of this high-ash Bulgarian lignite sample using the Kellogg, Brown, and Root (KBR) transport gasifier technology would not provide a syngas suitable for directly firing a gas turbine. After correcting for test conditions specific to the pilot-scale TRDU, including an unavoidably high heat loss and nitrogen dilution by transport air, the best-case heating value for oxygen-blown operation was estimated to be 3316 kJ/m{sup 3} for a commercial KRB transport gasifier. This heating value is about 80% of the minimum required for firing a gas turbine. Removing 50% of the carbon dioxide from the syngas would increase the heating value to 4583 kJ/m{sup 3}, i.e., to about 110% of the minimum requirement, and 95% removal would provide a heating value of 7080 kJ/m{sup 3}. Supplemental firing of natural gas would also allow the integrated gasification combined cycle (IGCC) technology to be utilized without having to remove CO{sub 2}. If removal of all nitrogen from the input gas streams such as the coal transport air were achieved, a heating value very close to that needed to fire a gas turbine would be achieved; however, some operational issues associated with utilizing recycled syngas or carbon dioxide as the transport gas would also have to be resolved. Use of a coal with a quality similar to the core samples provided earlier in the test program would also improve the gasifier performance. Low cold-gas efficiencies on the order of 20% calculated for oxygen-blown tests resulted in part from specific difficulties experienced in trying to operate the pilot-scale TRDU on this very high-ash lignite. These low levels of efficiency are not believed to be representative of what could be achieved in a commercial KRB transport gasifier. Combustion tests were also performed in the EERC's circulating fluidized-bed combustor (CFBC) to evaluate this alternative technology for use of this fuel. It was demonstrated that this fuel does have sufficient heating value to sustain combustion, even without coal drying; however, it will be challenging to economically extract sufficient energy for the generation of steam for electrical generation. The boiler efficiency for the dried coal was 73.5% at 85% sulfur capture (21.4% moisture) compared to 55.3% at 85% sulfur capture (40% moisture). Improved boiler efficiencies for this coal will be possible operating a system more specifically designed to maximize heat extraction from the ash streams for this high-ash fuel. Drying of the coal to approximately 25% moisture probably would be recommended for either power system. Fuel moisture also has a large impact on fuel feedability. Pressurized gasifiers generally like drier fuels than systems operating at ambient pressures. The commercially recommended feedstock moisture for a pressurized transport reactor gasifier is 25% moisture. Maximum moisture content for a CFB system could be approximately 40% moisture as has been demonstrated on the Alstom CFB operating on Mississippi lignite. A preliminary economic evaluation for CO{sub 2} was performed on the alternatives of (1) precombustion separation of CO{sub 2} in an IGCC using the KBR transport gasifier and (2) postcombustion CO{sub 2} capture using a CFBC. It appears that the capture of CO{sub 2} from the high-pressure IGCC precombustion system would be less costly than from the low-pressure postcombustion CFBC system by a factor of 1.5, although the cost difference is not directly comparable because of the model input being limited to a higher coal quality than the Bulgarian lignite. While the decision to pursue precombustion removal of carbon dioxide has been technically proven with the Rectisol{reg_sign} and Selexol{trademark} processes, General Electric and Siemens have not sold any gas turbine systems running on the high-hydrogen syngas. They have successfully demonstrated a gas turbine on syngases containing up to 95% hydrogen. The technological hurdles should not be too difficult given this experience in the gas turbine industry

JV TASK 45-MERCURY CONTROL TECHNOLOGIES FOR ELECTRIC UTILITIES BURNING LIGNITE COAL, PHASE I BENCH-AND PILOT-SCALE TESTING

The Energy & Environmental Research Center has completed the first phase of a 3-year, two-phase consortium project to develop and demonstrate mercury control technologies for utilities that burn lignite coal. The overall project goal is to maintain the viability of lignite-based energy production by providing utilities with low-cost options for meeting future mercury regulations. Phase I objectives are to develop a better understanding of mercury interactions with flue gas constituents, test a range of sorbent-based technologies targeted at removing elemental mercury (Hg{sup o}) from flue gases, and demonstrate the effectiveness of the most promising technologies at the pilot scale. The Phase II objectives are to demonstrate and quantify sorbent technology effectiveness, performance, and cost at a sponsor-owned and operated power plant. Phase I results are presented in this report along with a brief overview of the Phase II plans. Bench-scale testing provided information on mercury interactions with flue gas constituents and relative performances of the various sorbents. Activated carbons were prepared from relatively high-sodium lignites by carbonization at 400 C (752 F), followed by steam activation at 750 C (1382 F) and 800 C (1472 F). Luscar char was also steam-activated at these conditions. These lignite-based activated carbons, along with commercially available DARCO FGD and an oxidized calcium silicate, were tested in a thin-film, fixed-bed, bench-scale reactor using a simulated lignitic flue gas consisting of 10 {micro}g/Nm{sup 3} Hg{sup 0}, 6% O{sub 2}, 12% CO{sub 2}, 15% H{sub 2}O, 580 ppm SO{sub 2}, 120 ppm NO, 6 ppm NO{sub 2}, and 1 ppm HCl in N{sub 2}. All of the lignite-based activated (750 C, 1382 F) carbons required a 30-45-minute conditioning period in the simulated lignite flue gas before they exhibited good mercury sorption capacities. The unactivated Luscar char and oxidized calcium silicate were ineffective in capturing mercury. Lignite-based activated (800 C, 1472 F) carbons required a shorter (15-minute) conditioning period in the simulated lignite flue gas and captured gaseous mercury more effectively than those activated at 750 C (1382 F). Subsequent tests with higher acid gas concentrations including 50 ppm HCl showed no early mercury breakthrough for either the activated (750 C, 1382 F) Bienfait carbon or the DARCO FGD. Although these high acid gas tests yielded better mercury capture initially, significant breakthrough of mercury ultimately occurred sooner than during the simulated lignite flue gas tests. The steam-activated char, provided by Luscar Ltd., and DARCO FGD, provided by NORIT Americas, were evaluated for mercury removal potential in a 580 MJ/hr (550,000-Btu/hr) pilot-scale coal combustion system equipped with four particulate control devices: (1) an electrostatic precipitator (ESP), (2) a fabric filter (FF), (3) the Advanced Hybrid{trademark} filter, and (4) an ESP and FF in series, an EPRI-patented TOXECON{trademark} technology. The Ontario Hydro method and continuous mercury monitors were used to measure mercury species concentrations at the inlet and outlet of the control technology devices with and without sorbent injection. Primarily Hg{sup o} was measured when lignite coals from the Poplar River Plant and Freedom Mine were combusted. The effects of activated Luscar char, DARCO FGD, injection rates, particle size, and gas temperature on mercury removal were evaluated for each of the four particulate control device options. Increasing injection rates and decreasing gas temperatures generally promoted mercury capture in all four control devices. Relative to data reported for bituminous and subbituminous coal combustion flue gases, higher sorbent injection rates were generally required for the lignite coal to effectively remove mercury. Documented results in this report provide the impacts of these and other parameters and provide the inputs needed to direct Phase II of the project

JV Task 126 - Mercury Control Technologies for Electric Utilities Burning Bituminous Coal

The EERC developed an applied research consortium project to test cost-effective mercury (Hg) control technologies for utilities burning bituminous coals. The project goal was to test innovative Hg control technologies that have the potential to reduce Hg emissions from bituminous coal-fired power plants by {ge}90% at costs of one-half to three-quarters of current estimates for activated carbon injection (ACI). Hg control technology evaluations were performed using the EERC's combustion test facility (CTF). The CTF was fired on pulverized bituminous coals at 550,000 Btu/hr (580 MJ/hr). The CTF was configured with the following air pollution control devices (APCDs): selective catalytic reduction (SCR) unit, electrostatic precipitator (ESP), and wet flue gas desulfurization system (WFDS). The Hg control technologies investigated as part of this project included ACI (three Norit Americas, Inc., and eleven Envergex sorbents), elemental mercury (Hg{sup 0}) oxidation catalysts (i.e., the noble metals in Hitachi Zosen, Cormetech, and Hitachi SCR catalysts), sorbent enhancement additives (SEAs) (a proprietary EERC additive, trona, and limestone), and blending with a Powder River Basin (PRB) subbituminous coal. These Hg control technologies were evaluated separately, and many were also tested in combination