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Title: Investigation and Demonstration of Dry Carbon-Based Sorbent Injection for Mercury Control

Abstract

Public Service Company of Colorado and ADA Technologies, Inc. have performed a study of the injection of activated carbon for the removal of vapor-phase mercury from coal-fired flue gas streams. The project was completed under contract to the US Department of Energy's National Energy Technology Laboratory, with contributions from EPRI and Public Service Company. The prime contractor for the project was Public Service Company, with ADA Technologies as the major subcontractor providing technical support to all aspects of the project. The research and development effort was conducted in two phases. In Phase I a pilot facility was fabricated and tests were performed using dry carbon-based sorbent injection for mercury control on a coal-fired flue gas slipstream extracted from an operating power plant. Phase II was designed to move carbon injection technology towards commercial application on coal-fired power plants by addressing key reliability and operability concerns. Phase II field work included further development work with the Phase I pilot and mercury measurements on several of PSCo's coal-fired generating units. In addition, tests were run on collected sorbent plus fly ash to evaluate the impact of the activated carbon sorbent on the disposal of fly ash. An economic analysis was performed wheremore » pilot plant test data was used to develop a model to predict estimated costs of mercury removal from plants burning western coals. Testing in the pilot plant was undertaken to quantify the effects of plant configuration, flue gas temperature, and activated carbon injection rate on mercury removal. All three variables were found to significantly impact the mercury removal efficiency in the pilot. The trends were clear: mercury removal rates increased with decreasing flue gas temperature and with increasing carbon injection rates. Mercury removal was much more efficient with reverse-gas and pulse-jet baghouse configurations than with an ESP as the particulate control device. The native fly ash of the host unit provided significant mercury removal capacity, so that the activated carbon sorbent served as an incremental mercury removal mechanism. Tests run to characterize the waste product, a combination of fly ash and activated carbon on which mercury was present, showed that mercury and other RCRA metals of interest were all below Toxic Characteristic Leaching Procedure (TCLP) regulatory limits in the leachate. The presence of activated carbon in the fly ash was shown to have an effect on the use of fly ash as an additive in the manufacture of concrete, which could limit the salability of fly ash from a plant where activated carbon was used for mercury control.« less

Authors:
;
Publication Date:
Research Org.:
Public Service Company of Colorado
Sponsoring Org.:
USDOE
OSTI Identifier:
883038
DOE Contract Number:
AC22-95PC95256
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; ACTIVATED CARBON; ADDITIVES; BAGHOUSES; CARBON; CONFIGURATION; ECONOMIC ANALYSIS; EFFICIENCY; FLUE GAS; FLY ASH; LEACHING; MERCURY; PARTICULATES; PILOT PLANTS; POWER PLANTS; REMOVAL; TESTING; WASTES

Citation Formats

Jim Butz, and Terry Hunt. Investigation and Demonstration of Dry Carbon-Based Sorbent Injection for Mercury Control. United States: N. p., 2005. Web. doi:10.2172/883038.
Jim Butz, & Terry Hunt. Investigation and Demonstration of Dry Carbon-Based Sorbent Injection for Mercury Control. United States. doi:10.2172/883038.
Jim Butz, and Terry Hunt. Tue . "Investigation and Demonstration of Dry Carbon-Based Sorbent Injection for Mercury Control". United States. doi:10.2172/883038. https://www.osti.gov/servlets/purl/883038.
@article{osti_883038,
title = {Investigation and Demonstration of Dry Carbon-Based Sorbent Injection for Mercury Control},
author = {Jim Butz and Terry Hunt},
abstractNote = {Public Service Company of Colorado and ADA Technologies, Inc. have performed a study of the injection of activated carbon for the removal of vapor-phase mercury from coal-fired flue gas streams. The project was completed under contract to the US Department of Energy's National Energy Technology Laboratory, with contributions from EPRI and Public Service Company. The prime contractor for the project was Public Service Company, with ADA Technologies as the major subcontractor providing technical support to all aspects of the project. The research and development effort was conducted in two phases. In Phase I a pilot facility was fabricated and tests were performed using dry carbon-based sorbent injection for mercury control on a coal-fired flue gas slipstream extracted from an operating power plant. Phase II was designed to move carbon injection technology towards commercial application on coal-fired power plants by addressing key reliability and operability concerns. Phase II field work included further development work with the Phase I pilot and mercury measurements on several of PSCo's coal-fired generating units. In addition, tests were run on collected sorbent plus fly ash to evaluate the impact of the activated carbon sorbent on the disposal of fly ash. An economic analysis was performed where pilot plant test data was used to develop a model to predict estimated costs of mercury removal from plants burning western coals. Testing in the pilot plant was undertaken to quantify the effects of plant configuration, flue gas temperature, and activated carbon injection rate on mercury removal. All three variables were found to significantly impact the mercury removal efficiency in the pilot. The trends were clear: mercury removal rates increased with decreasing flue gas temperature and with increasing carbon injection rates. Mercury removal was much more efficient with reverse-gas and pulse-jet baghouse configurations than with an ESP as the particulate control device. The native fly ash of the host unit provided significant mercury removal capacity, so that the activated carbon sorbent served as an incremental mercury removal mechanism. Tests run to characterize the waste product, a combination of fly ash and activated carbon on which mercury was present, showed that mercury and other RCRA metals of interest were all below Toxic Characteristic Leaching Procedure (TCLP) regulatory limits in the leachate. The presence of activated carbon in the fly ash was shown to have an effect on the use of fly ash as an additive in the manufacture of concrete, which could limit the salability of fly ash from a plant where activated carbon was used for mercury control.},
doi = {10.2172/883038},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Nov 01 00:00:00 EST 2005},
month = {Tue Nov 01 00:00:00 EST 2005}
}

Technical Report:

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  • The U.S. Department of Energy (DOE) issued Public Service Company of Colorado (PSCO) a cost sharing contract to evaluate carbon-based sorbents for mercury control on a 600 acfm laboratory-scale particulate control module (PCM). The PCM can be configured as simulate an electrostatic precipitator, a pulse-jet fabric filter, or a reverse-gas fabric filter and is installed on an operating coal-fired power plant. Three different dry carbon-based sorbents were tested this quarter to determine their mercury removal capability in the different configurations. The project is currently in the seventh quarter of an eight-quarter Phase I project. Testing in all configurations is nearlymore » complete. Original plans included the use of an on-line mercury analyzer to collect test data. However, due to very low baseline mercury concentration, on-line measurement did not provide accurate data. The project used a modified MESA method grab sample technique to determine inlet and outlet mercury concentrations. A major concern during sorbent evaluations was the natural ability of the flyash at the test site to remove mercury. This often made determination of sorbent only mercury removal difficult. The PCM was configured as a reverse-gas baghouse and brought online with "clean" flue gas on March 10* at an A/C of 2.0 ft/min. The dustcake forms the filtering media in a reverse gas baghouse. In the absence of flyash, the bags were precoated with a commercially available alumina silicate material to form an inert dustcake. Some baseline tests were completed with clean gas for comparison to clean gas pulse jet tests. The PCM was reconfigured as a TOXECON unit in April 1997 with testing completed in May 1997. TOXECON, an EPIU patented technology, is a pulse-jet baghouse operating at a high A/C ratio downstream of a primary particulate colIector with sorbent injection upstream of the baghouse for air toxics removal. Mercury removals of O to 97o/0 were obtained depending on test conditions.« less
  • The overall objective this two phase program is to investigate the use of dry carbon-based sorbents for mercury control. During Phase 1, a bench-scale field test device that can be configured as an electrostatic precipitator, a pulse-jet baghouse, or a reverse-gas baghouse has been designed and will be integrated with an existing pilot-scale facility at PSCo`s Comanche Station. Up to three candidate sorbents will then be injected into the flue gas stream upstream of the test device to determine the mercury removal efficiency for each sorbent. During the Phase 11 effort, component integration for the most promising dry sorbent technologymore » (technically and economically feasible) shall be tested at the 5000 acfm pilot-scale. An extensive work plan has been developed for the project. Three sorbents will be selected for evaluation at the facility through investigation, presentation, and discussion among team members: PSCO, EPRI, ADA, and DOE. The selected sorbents will be tested in the five primary bench-scale configurations: pulse `et baghouse, TOXECON, reverse-gas baghouse, electrostatic precipitator, and an ESP or fabric filter `with no Comanche ash in the flue gas stream. In the EPRI TOXECON system, mercury sorbents will be injected downstream of a primary particulate control device, and collected in a pulse-jet baghouse operated at air-to-cloth ratios of 12 to 16 ft/min, thus separating the mercury and sorbent from the captured flyash. In the no-ash configuration, an external flyash sample will be injected into a clean gas stream to investigate possible variations in sorbent effectiveness in the presence of different ashes. The use of an existing test facility, a versatile design for the test fixture, and installation of a continuous mercury analyzer will allow for the completion of this ambitious test plan. The primary activity during the quarter was to complete fabrication and installation of the facility.« less
  • The overall objective this two phase program is to investigate the use of dry carbon-based sorbents for mercury control. This information is important to the utility industry in anticipation of pending regulations. During Phase 1, a bench-scale field test device that can be configured as an electrostatic precipitator, a pulse-jet baghouse, or a reverse-gas baghouse has been designed and will be integrated with an existing pilot-scale facility at PSCo`s Comanche Station. Up to three candidate sorbents will then be injected into the flue gas stream upstream of the test device to determine the mercury removal efficiency for each sorbent. Duringmore » the Phase II effort, component integration for the most promising dry sorbent technology (technically and economically feasible) shall be tested at the 5000 acfm pilot-scale. The primary activity during the quarter was the design and fabrication of the facility. The main structure, which incorporates the particulate control module (PCM), sorbent injection section and in-duct heater was functionally complete at the end of March. Finish work on the structure will take place in April and arrangements are being made to erect the facility at the host site, Comanche Station, on April 29 and 30, 1996. Final selection of sorbents has been postponed until late April when results from testing in EPRI laboratories should be available.« less
  • The overall objective to this two phase program is to investigate dry carbon-based sorbents for mercury control. During Phase I, a bench-scale field test device that can simulate an electrostatic precipitator, a pulse-jet baghouse, or a reverse-gas baghouse will be designed and integrated with an existing pilot-scale facility at Public Service Company of Colorado`s (PSCo`s) Comanche station. Various sorbents will then be injected to determine the mercury removal efficiency for each. During Phase II effort, component integration of the most promising technologies shall be tested at the 5000 acfm pilot-scale. The primary task currently underway is the facility design. Themore » design is expected to be finished in January, 1996. The facility, regardless of the particulate control module configuration, will be fitted with supply line injection port, through which mercury sorbents and SO{sub 2} control sorbents can be added to the flue gas stream.« less
  • The U.S. Department of Energy (DOE) has issued Public Service Company of Colorado (PSCo) a cost sharing contract to evaluate carbon-based sorbents for mercury control on a 600 acfm laboratory scale particulate control module (PCM). The PCM can simulate an electrostatic precipitator, a pulse-jet fabric filter, and a reverse air fabric filter and uses actual flue gas from an operating coal-fired power plant. Up to 3 different dry carbon-based sorbents will be tested to determine the mercury removal capability in the different configurations. The project is currently in the fifth quarter of an eight quarter Phase I project. The PCMmore » has been fabricated and mercury removal testing with the ESP configuration has been completed. Original plans included the use on an on-line meercury analyzer to collect the test data. However, due to very low baseline mercury concentration, on-line measurement did not provide accurate data. The project has continued using a modified MESA method grab sample technique to determine inlet and outlet mercury concentrations. A major concern during sorbent evaluations has been the natural ability of the flyash at the test site to remove mercury. This has made determination of sorbent only mercury removal difficult. Overall vapor-phase mercury removals of 15 to 70% have been obtained but this includes mercury removals in the range of 30% by the flyash. It is believed that a maximum of approximately 40% removal due to the sorbent only has been obtained. A number of test and sampling modifications are in progress to increase the data confidence and many questions remain. Startup of the pulse jet configuration began in early November but results of this testing are not available at this time. The project team has decided to proceed with pulse jet testing using flue gas that does not contain significant flyash quantities to further investigate the sorbent only mercury removal.« less