The Experts below are selected from a list of 36 Experts worldwide ranked by ideXlab platform

Alejandro Molina - One of the best experts on this subject based on the ideXlab platform.

  • ignition and devolatilization of pulverized Bituminous Coal particles during oxygen carbon dioxide Coal combustion
    Proceedings of the Combustion Institute, 2007
    Co-Authors: Alejandro Molina, Christopher R. Shaddix
    Abstract:

    Abstract Oxygen/carbon dioxide recycle Coal combustion is actively being investigated because of its potential to facilitate CO 2 sequestration and to achieve emission reductions. In the work reported here, the effect of enhanced oxygen levels and CO 2 bath gas is independently analyzed for their influence on single-particle pulverized Coal ignition of a U.S. Eastern Bituminous Coal. The experiments show that the presence of CO 2 and a lower O 2 concentration increase the ignition delay time but have no measurable effect on the time required to complete volatile combustion, once initiated. For the ignition process observed in the experiments, the CO 2 results are explained by its higher molar specific heat and the O 2 results are explained by the effect of O 2 concentration on the local mixture reactivity. Particle ignition and devolatilization properties in a mixture of 30% O 2 in CO 2 are very similar to those in air.

  • the effect of potassium bromide and sodium carbonate on Coal char combustion reactivity
    Proceedings of the Combustion Institute, 2005
    Co-Authors: Alejandro Molina, Jeffrey J Murphy, Christopher R. Shaddix, Linda Gail Blevins
    Abstract:

    The addition of halogens, particularly iodine, to the gas during Coal char oxidation has been used in previous studies to quench gas-phase chemistry, thereby allowing one to separate the effects of homogeneous and heterogeneous reactions. Halogen addition suppresses the gas-phase radicals to near-equilibrium levels. A similar effect can be expected from other compounds with high efficiency as fire suppressants, such as alkali metals. The effectiveness of the use of additives in distinguishing homogeneous and heterogeneous reactions during char oxidation relies on the assumption that radicals are suppressed while heterogeneous reactions occurring on the char surface are not affected. The present work tests this assumption for potassium bromide (KBr) and sodium carbonate (Na2CO3) reacting with a pulverized Eastern Bituminous Coal char during oxidation. An increase in CO and a slight reduction in particle temperature were observed with the addition of KBr, consistent with known effects of halogens on gas-phase chemistry. An increase in particle size was also observed with the KBr addition. This observation and the results of model calculations suggest that there is significant incorporation of liquid KBr on the char surface under the conditions examined. With Na2CO3 addition, the particle temperature did not change, the particle size showed a slight decrease, and CO production increased. Although the mechanisms for Na interaction with radicals at combustion conditions are not well established, char oxidation modeling suggests that a decrease in OH concentration in the particle boundary layer is the cause for the observed increase in CO production. It is concluded that Na2CO3 has clear advantages over KBr for inhibiting gas-phase chemistry without affecting char oxidation for the conditions investigated here.

Christopher R. Shaddix - One of the best experts on this subject based on the ideXlab platform.

  • ignition and devolatilization of pulverized Bituminous Coal particles during oxygen carbon dioxide Coal combustion
    Proceedings of the Combustion Institute, 2007
    Co-Authors: Alejandro Molina, Christopher R. Shaddix
    Abstract:

    Abstract Oxygen/carbon dioxide recycle Coal combustion is actively being investigated because of its potential to facilitate CO 2 sequestration and to achieve emission reductions. In the work reported here, the effect of enhanced oxygen levels and CO 2 bath gas is independently analyzed for their influence on single-particle pulverized Coal ignition of a U.S. Eastern Bituminous Coal. The experiments show that the presence of CO 2 and a lower O 2 concentration increase the ignition delay time but have no measurable effect on the time required to complete volatile combustion, once initiated. For the ignition process observed in the experiments, the CO 2 results are explained by its higher molar specific heat and the O 2 results are explained by the effect of O 2 concentration on the local mixture reactivity. Particle ignition and devolatilization properties in a mixture of 30% O 2 in CO 2 are very similar to those in air.

  • the effect of potassium bromide and sodium carbonate on Coal char combustion reactivity
    Proceedings of the Combustion Institute, 2005
    Co-Authors: Alejandro Molina, Jeffrey J Murphy, Christopher R. Shaddix, Linda Gail Blevins
    Abstract:

    The addition of halogens, particularly iodine, to the gas during Coal char oxidation has been used in previous studies to quench gas-phase chemistry, thereby allowing one to separate the effects of homogeneous and heterogeneous reactions. Halogen addition suppresses the gas-phase radicals to near-equilibrium levels. A similar effect can be expected from other compounds with high efficiency as fire suppressants, such as alkali metals. The effectiveness of the use of additives in distinguishing homogeneous and heterogeneous reactions during char oxidation relies on the assumption that radicals are suppressed while heterogeneous reactions occurring on the char surface are not affected. The present work tests this assumption for potassium bromide (KBr) and sodium carbonate (Na2CO3) reacting with a pulverized Eastern Bituminous Coal char during oxidation. An increase in CO and a slight reduction in particle temperature were observed with the addition of KBr, consistent with known effects of halogens on gas-phase chemistry. An increase in particle size was also observed with the KBr addition. This observation and the results of model calculations suggest that there is significant incorporation of liquid KBr on the char surface under the conditions examined. With Na2CO3 addition, the particle temperature did not change, the particle size showed a slight decrease, and CO production increased. Although the mechanisms for Na interaction with radicals at combustion conditions are not well established, char oxidation modeling suggests that a decrease in OH concentration in the particle boundary layer is the cause for the observed increase in CO production. It is concluded that Na2CO3 has clear advantages over KBr for inhibiting gas-phase chemistry without affecting char oxidation for the conditions investigated here.

Linda Gail Blevins - One of the best experts on this subject based on the ideXlab platform.

  • the effect of potassium bromide and sodium carbonate on Coal char combustion reactivity
    Proceedings of the Combustion Institute, 2005
    Co-Authors: Alejandro Molina, Jeffrey J Murphy, Christopher R. Shaddix, Linda Gail Blevins
    Abstract:

    The addition of halogens, particularly iodine, to the gas during Coal char oxidation has been used in previous studies to quench gas-phase chemistry, thereby allowing one to separate the effects of homogeneous and heterogeneous reactions. Halogen addition suppresses the gas-phase radicals to near-equilibrium levels. A similar effect can be expected from other compounds with high efficiency as fire suppressants, such as alkali metals. The effectiveness of the use of additives in distinguishing homogeneous and heterogeneous reactions during char oxidation relies on the assumption that radicals are suppressed while heterogeneous reactions occurring on the char surface are not affected. The present work tests this assumption for potassium bromide (KBr) and sodium carbonate (Na2CO3) reacting with a pulverized Eastern Bituminous Coal char during oxidation. An increase in CO and a slight reduction in particle temperature were observed with the addition of KBr, consistent with known effects of halogens on gas-phase chemistry. An increase in particle size was also observed with the KBr addition. This observation and the results of model calculations suggest that there is significant incorporation of liquid KBr on the char surface under the conditions examined. With Na2CO3 addition, the particle temperature did not change, the particle size showed a slight decrease, and CO production increased. Although the mechanisms for Na interaction with radicals at combustion conditions are not well established, char oxidation modeling suggests that a decrease in OH concentration in the particle boundary layer is the cause for the observed increase in CO production. It is concluded that Na2CO3 has clear advantages over KBr for inhibiting gas-phase chemistry without affecting char oxidation for the conditions investigated here.

Douglas Orr - One of the best experts on this subject based on the ideXlab platform.

  • sorbent injection for small esp mercury control in low sulfur Eastern Bituminous Coal flue gas
    2006
    Co-Authors: Carl Richardson, Katherine Dombrowski, Douglas Orr
    Abstract:

    This project Final Report is submitted to the U.S. Department of Energy (DOE) as part of Cooperative Agreement DE-FC26-03NT41987, 'Sorbent Injection for Small ESP Mercury Control in Low Sulfur Eastern Bituminous Coal Flue Gas.' Sorbent injection technology is targeted as the primary mercury control process on plants burning low/medium sulfur Bituminous Coals equipped with ESP and ESP/FGD systems. About 70% of the ESPs used in the utility industry have SCAs less than 300 ft2/1000 acfm. Prior to this test program, previous sorbent injection tests had focused on large-SCA ESPs. This DOE-NETL program was designed to generate data to evaluate the performance and economic feasibility of sorbent injection for mercury control at power plants that fire Bituminous Coal and are configured with small-sized electrostatic precipitators and/or an ESP-flue gas desulfurization (FGD) configuration. EPRI and Southern Company were co-funders for the test program. Southern Company and Reliant Energy provided host sites for testing and technical input to the project. URS Group was the prime contractor to NETL. ADA-ES and Apogee Scientific Inc. were sub-contractors to URS and was responsible for all aspects of the sorbent injection systems design, installation and operation at the different host sites. Full-scale sorbent injection for mercury control more » was evaluated at three sites: Georgia Power's Plant Yates Units 1 and 2 [Georgia Power is a subsidiary of the Southern Company] and Reliant Energy's Shawville Unit 3. Georgia Power's Plant Yates Unit 1 has an existing small-SCA cold-side ESP followed by a Chiyoda CT-121 wet scrubber. Yates Unit 2 is also equipped with a small-SCA ESP and a dual flue gas conditioning system. Unit 2 has no SO2 control system. Shawville Unit 3 is equipped with two small-SCA cold-side ESPs operated in series. All ESP systems tested in this program had SCAs less than 250 ft2/1000 acfm. Short-term parametric tests were conducted on Yates Units 1 and 2 to evaluate the performance of low-cost activated carbon sorbents for removing mercury. In addition, the effects of the dual flue gas conditioning system on mercury removal performance were evaluated as part of short-term parametric tests on Unit 2. Based on the parametric test results, a single sorbent (e.g., RWE Super HOK) was selected for a 30-day continuous injection test on Unit 1 to observe long-term performance of the sorbent as well as its effects on ESP and FGD system operations as well as combustion byproduct properties. A series of parametric tests were also performed on Shawville Unit 3 over a three-week period in which several activated carbon sorbents were injected into the flue gas duct just upstream of either of the two Unit 3 ESP units. Three different sorbents were evaluated in the parametric test program for the combined ESP 1/ESP 2 system in which sorbents were injected upstream of ESP 1: RWE Super HOK, Norit's DARCO Hg, and a 62:38 wt% hydrated lime/DARCO Hg premixed reagent. Five different sorbents were evaluated for the ESP 2 system in which activated carbons were injected upstream of ESP 2: RWE Super HOK and coarse-ground HOK, Norit's DARCO Hg and DARCO Hg-LH, and DARCO Hg with lime injection upstream of ESP 1. The hydrated lime tests were conducted to reduce SO3 levels in an attempt to enhance the mercury removal performance of the activated carbon sorbents. The Plant Yates and Shawville studies provided data required for assessing carbon performance and long-term operational impacts for flue gas mercury control across small-sized ESPs, as well as for estimating the costs of full-scale sorbent injection processes. « less

O Douglas - One of the best experts on this subject based on the ideXlab platform.

  • Sorbent Injection for Small ESP Mercury Control in Low Sulfur Eastern Bituminous Coal Flue Gas
    URS Group Inc., 2006
    Co-Authors: Richardso Carl, Dombrowski Katherine, O Douglas
    Abstract:

    This project Final Report is submitted to the U.S. Department of Energy (DOE) as part of Cooperative Agreement DE-FC26-03NT41987, 'Sorbent Injection for Small ESP Mercury Control in Low Sulfur Eastern Bituminous Coal Flue Gas.' Sorbent injection technology is targeted as the primary mercury control process on plants burning low/medium sulfur Bituminous Coals equipped with ESP and ESP/FGD systems. About 70% of the ESPs used in the utility industry have SCAs less than 300 ft2/1000 acfm. Prior to this test program, previous sorbent injection tests had focused on large-SCA ESPs. This DOE-NETL program was designed to generate data to evaluate the performance and economic feasibility of sorbent injection for mercury control at power plants that fire Bituminous Coal and are configured with small-sized electrostatic precipitators and/or an ESP-flue gas desulfurization (FGD) configuration. EPRI and Southern Company were co-funders for the test program. Southern Company and Reliant Energy provided host sites for testing and technical input to the project. URS Group was the prime contractor to NETL. ADA-ES and Apogee Scientific Inc. were sub-contractors to URS and was responsible for all aspects of the sorbent injection systems design, installation and operation at the different host sites. Full-scale sorbent injection for mercury control was evaluated at three sites: Georgia Power's Plant Yates Units 1 and 2 [Georgia Power is a subsidiary of the Southern Company] and Reliant Energy's Shawville Unit 3. Georgia Power's Plant Yates Unit 1 has an existing small-SCA cold-side ESP followed by a Chiyoda CT-121 wet scrubber. Yates Unit 2 is also equipped with a small-SCA ESP and a dual flue gas conditioning system. Unit 2 has no SO2 control system. Shawville Unit 3 is equipped with two small-SCA cold-side ESPs operated in series. All ESP systems tested in this program had SCAs less than 250 ft2/1000 acfm. Short-term parametric tests were conducted on Yates Units 1 and 2 to evaluate the performance of low-cost activated carbon sorbents for removing mercury. In addition, the effects of the dual flue gas conditioning system on mercury removal performance were evaluated as part of short-term parametric tests on Unit 2. Based on the parametric test results, a single sorbent (e.g., RWE Super HOK) was selected for a 30-day continuous injection test on Unit 1 to observe long-term performance of the sorbent as well as its effects on ESP and FGD system operations as well as combustion byproduct properties. A series of parametric tests were also performed on Shawville Unit 3 over a three-week period in which several activated carbon sorbents were injected into the flue gas duct just upstream of either of the two Unit 3 ESP units. Three different sorbents were evaluated in the parametric test program for the combined ESP 1/ESP 2 system in which sorbents were injected upstream of ESP 1: RWE Super HOK, Norit's DARCO Hg, and a 62:38 wt% hydrated lime/DARCO Hg premixed reagent. Five different sorbents were evaluated for the ESP 2 system in which activated carbons were injected upstream of ESP 2: RWE Super HOK and coarse-ground HOK, Norit's DARCO Hg and DARCO Hg-LH, and DARCO Hg with lime injection upstream of ESP 1. The hydrated lime tests were conducted to reduce SO3 levels in an attempt to enhance the mercury removal performance of the activated carbon sorbents. The Plant Yates and Shawville studies provided data required for assessing carbon performance and long-term operational impacts for flue gas mercury control across small-sized ESPs, as well as for estimating the costs of full-scale sorbent injection processes