Heap, MP
1997
Waste Incineration for Resource Recovery in a Regenerative Life Support System
Brouwer, J.; Kemp, G.; Heap, M.P.; Lighty, J.S.; Burton, B.; Sirdeshpande, A.; Inkley, D.; Pershing, D.W.; Fisher, J. and Pisharody, S.
Western States Section of the Combustion Institute, Spring 1997
For the last two years, the University of Utah and Reaction Engineering International, in cooperation with Ames Research Center, have been developing a waste incineration system for regenerative life support systems. The system is designed to burn inedible plant biomass and human waste. The exhaust gas is currently designed to recycle back to the plant growth chamber and will eventually be recycled to the human chamber after passing through a Trace Contaminant Control System. The incineration system, a fluidized bed reactor, has been designed for a 4-person mission. This paper will detail the design of the components of this system. In addition, results will be presented from testing at the University of Utah. Presently, the unit has been shipped to Ames Research Center for more tests prior to delivery to Johnson Space Center for testing in a 90-day, 4-person test.
Waste Incineration for Resource Recovery in a Bioregenerative Life Support System
Lighty, J.S.; Burton, B.; Sirdeshpande, A.; Inkley, D.; Pershing, D.W.; Brouwer, J.; Kemp, G.; Heap, M.P.; Fisher, J. and Pisharody, S.
27th International Conference on Environmental Systems, Lake Tahoe, Nevada, July 14-17, 1997
For the last two years, the University of Utah and Reaction Engineering International, in cooperation with NASA Ames Research Center (ARC), have been developing a waste incineration system for regenerative life support systems. The system is designed to burn inedible plant biomass and human waste. The goal is to obtain an exhaust gas clean enough to recycle to either the plant or human habitats. The incineration system, a fluidized bed reactor, has been designed for a 4-person mission. This paper will detail the design of the units. In addition, results will be presented from testing at the University of Utah. Presently, the unit has been shipped to Ames Research Center for more tests prior to delivery to Johnson Space Center for testing in a 90-day, 4-person test.
1996
The Formation and Control of NOx Emissions from Biomass Combustion
Pershing, D.W.; Lighty, J.S.; Harding, S.N.; Brouwer, J.; Heap, M.P.; Munro, J.M. and Winter, R.M.
Proceedings from the Finnish-Swedish Flame Days, Naantali, Finland, September, 1996. Funded by Environmental Protection Agency, US Department of Energy and National Science Foundation.
Biomass fuels account for a significant fraction of the worldwide energy usage. In 1990 consumption is believed to have exceeded 13 quads according to Tillman (1991). This does not include the combustion of peat that is known to be widely used in some northern European countries and in parts of the former Soviet Union. Biomass energy consumption is also a significant fraction of total energy usage in many developing nations. Hence, emissions from combustion of biofuels are of interest to the environmental community.
Most biomass materials generally produce lower NOx emissions when they are burned than their fossil fuel counterparts, but under certain conditions NOx emissions can be significant. Biomass fuels usually contain relatively limited amounts of organic nitrogen (often 0.1 ± 0.1%) so NOx formation from fuel nitrogen is generally small (except in the case of peat and some plant wastes). Biofuels also tend to burn at cooler combustion temperatures (due to higher moisture contents and the presence of oxygen in the fuel structure), which tends to minimize the formation of NOx by the thermal mechanism (the high temperature fixation of N2 in the combustion air).
The purpose of this paper is review the available information on the formation and the control of NOx emissions during the combustion of biofuels alone and in combination with fossil fuels and/or wastes. Both laboratory and pilot scale studies have been included, as well as full scale field test results where they are generally available.
1992
Solid Waste Incineration in Rotary Kilns
Pershing, D.W.; Lighty, J.S.; Silcox, G.D.; Heap, M.P. and Owens, W.D.
Combustion Science and Technology, 1992 (in press). (Previously presented at the First International Conference on Combustion Technologies for a Clean Environment, Vilamoura, Portugal, September 1991.) Funded by the National Science Foundation, Environmental Protection Agency, Gas Research Institute and ACERC.
Rotary kilns are used to dispose of many solid wastes and sludges and to thermally treat contaminated soils. In this communication the fates of hydrocarbon and metal species are examined with a view toward optimization of new kiln designs and maximizing existing unit throughout while minimizing pollutant emissions. Initially, process fundamentals are considered to characterize the controlling phenomena. Pilot- and large-scale data are then examined to define practical system complexities. Finally, techniques for data scale-up and performance prediction are summarized. Temperature is clearly the most important parameter with respect to the fate of both metal and hydrocarbon species; hence, heat transfer is often rate limiting. High temperatures favor hydrocarbon evolution, but can also enhance the formation of toxic metal fumes. Both the solid composition and the moisture content can significantly influence the time at temperature required for hydrocarbon destruction and metal vaporization.
Improving bed mixing helps contaminant release but can also aggravate puffing tendencies with batch charging. Full-scale performance predictions currently require a combination of small-scale data and computer modeling. Future work needs to focus on verification of large-scale predictions for complex mixtures and sludges so that expensive trial burns can be minimized.
1991
Solid Waste Incineration in Rotary Kilns
Pershing, D.W.; Lighty, J.S.; Silcox, G.D.; Heap, M.P. and Owens, W.D.
First International Conference on Combustion Technologies for a Clean Environment, Vilamoura, Portugal, September 1991. Funded by the National Science Foundation, Environmental Protection Agency, Gas Research Institute and ACERC.
Rotary kilns are used to dispose of many solid wastes and sludges and to thermally treat contaminated soils. In this communication the fates of hydrocarbon and metal species are examined with a view toward optimization of new kiln designs and maximizing existing unit throughout while minimizing pollutant emissions. Initially, process fundamentals are considered to characterize the controlling phenomena. Pilot- and large-scale data are then examined to define practical system complexities. Finally, techniques for data scale-up and performance prediction are summarized. Temperature is clearly the most important parameter with respect to the fate of both metal and hydrocarbon species; hence, heat transfer is often rate limiting. High temperatures favor hydrocarbon evolution, but can also enhance the formation of toxic metal fumes. Both the solid composition and the moisture content can significantly influence the time at temperature required for hydrocarbon destruction and metal vaporization.
Improving bed mixing helps contaminant release but can also aggravate puffing tendencies with batch charging. Full-scale performance predictions currently require a combination of small-scale data and computer modeling. Future work needs to focus on verification of large-scale predictions for complex mixtures and sludges so that expensive trial burns can be minimized.
1988
Advanced NOx Reduction Processes Using -NH and -CN Compounds in Conjunction with Staged Air Addition
Chen, S.L.; Cole, J.A.; Heap, M.P.; Kramlich, J.C.; McCarthy, J.M. and Pershing, D.W.
Twenty-Second Symposium (International) on Combustion/The Combustion Institute, 1135-1145, 1988. Funded by Pittsburgh Energy Technology Center.
The effectiveness of combustion modifications for the control of nitrogen oxide emissions from coal fired combustors is most often limited by problems due to carbon burnout or flame impingement. This paper presents new data on the use of selective reducing agents suggesting that a hybrid control scheme is possible which uses combustion modification to provide those conditions that optimize the selective reduction process. Very low emission levels appear possible that can presently only be achieved by catalytic reduction. The experimental studies were conducted in a tunnel furnace that simulated the thermal environment within a pulverized coal boiler. Application of each of the agents (ammonia, urea, cyanuric acid, and ammonium sulfate) to an overall fuel lean environment produced NO reduction behavior very similar to that of thermal deNOx. However, if the agent was added to the fuel rich zone of a rich/lean staged combustor, very high NO reductions were obtained after the leanout point. The result of the staging was to extend the effectiveness of the agent to lower temperatures relative to overall lean injection. Parametric variations indicated that in addition to temperature, the most important variable was the rich zone stoichiometry. Kinetic modeling suggests that the rich zone acts primarily as a source of CO. At the rich/lean transition the CO is oxidized and excess OH is produced by the usual chain branching reactions. For low initial CO concentrations the excess radicals are consumed by:
NH3 + OH = NH2 + H2O
HNCO + H = NH2 + CO
The NH2 is then available for reaction with NO to eventually yield N2. The strong rich zone stoichiometry dependence is exerted mainly through the amount of CO supplied to the lean zone. Insufficient CO will limit the extent of the initial NH3 or HNCO reaction.
Heap, MP
1997
Waste Incineration for Resource Recovery in a Regenerative Life Support System
Brouwer, J.; Kemp, G.; Heap, M.P.; Lighty, J.S.; Burton, B.; Sirdeshpande, A.; Inkley, D.; Pershing, D.W.; Fisher, J. and Pisharody, S.
Western States Section of the Combustion Institute, Spring 1997
For the last two years, the University of Utah and Reaction Engineering International, in cooperation with Ames Research Center, have been developing a waste incineration system for regenerative life support systems. The system is designed to burn inedible plant biomass and human waste. The exhaust gas is currently designed to recycle back to the plant growth chamber and will eventually be recycled to the human chamber after passing through a Trace Contaminant Control System. The incineration system, a fluidized bed reactor, has been designed for a 4-person mission. This paper will detail the design of the components of this system. In addition, results will be presented from testing at the University of Utah. Presently, the unit has been shipped to Ames Research Center for more tests prior to delivery to Johnson Space Center for testing in a 90-day, 4-person test.
Waste Incineration for Resource Recovery in a Bioregenerative Life Support System
Lighty, J.S.; Burton, B.; Sirdeshpande, A.; Inkley, D.; Pershing, D.W.; Brouwer, J.; Kemp, G.; Heap, M.P.; Fisher, J. and Pisharody, S.
27th International Conference on Environmental Systems, Lake Tahoe, Nevada, July 14-17, 1997
For the last two years, the University of Utah and Reaction Engineering International, in cooperation with NASA Ames Research Center (ARC), have been developing a waste incineration system for regenerative life support systems. The system is designed to burn inedible plant biomass and human waste. The goal is to obtain an exhaust gas clean enough to recycle to either the plant or human habitats. The incineration system, a fluidized bed reactor, has been designed for a 4-person mission. This paper will detail the design of the units. In addition, results will be presented from testing at the University of Utah. Presently, the unit has been shipped to Ames Research Center for more tests prior to delivery to Johnson Space Center for testing in a 90-day, 4-person test.
1996
The Formation and Control of NOx Emissions from Biomass Combustion
Pershing, D.W.; Lighty, J.S.; Harding, S.N.; Brouwer, J.; Heap, M.P.; Munro, J.M. and Winter, R.M.
Proceedings from the Finnish-Swedish Flame Days, Naantali, Finland, September, 1996. Funded by Environmental Protection Agency, US Department of Energy and National Science Foundation.
Biomass fuels account for a significant fraction of the worldwide energy usage. In 1990 consumption is believed to have exceeded 13 quads according to Tillman (1991). This does not include the combustion of peat that is known to be widely used in some northern European countries and in parts of the former Soviet Union. Biomass energy consumption is also a significant fraction of total energy usage in many developing nations. Hence, emissions from combustion of biofuels are of interest to the environmental community.
Most biomass materials generally produce lower NOx emissions when they are burned than their fossil fuel counterparts, but under certain conditions NOx emissions can be significant. Biomass fuels usually contain relatively limited amounts of organic nitrogen (often 0.1 ± 0.1%) so NOx formation from fuel nitrogen is generally small (except in the case of peat and some plant wastes). Biofuels also tend to burn at cooler combustion temperatures (due to higher moisture contents and the presence of oxygen in the fuel structure), which tends to minimize the formation of NOx by the thermal mechanism (the high temperature fixation of N2 in the combustion air).
The purpose of this paper is review the available information on the formation and the control of NOx emissions during the combustion of biofuels alone and in combination with fossil fuels and/or wastes. Both laboratory and pilot scale studies have been included, as well as full scale field test results where they are generally available.
1992
Solid Waste Incineration in Rotary Kilns
Pershing, D.W.; Lighty, J.S.; Silcox, G.D.; Heap, M.P. and Owens, W.D.
Combustion Science and Technology, 1992 (in press). (Previously presented at the First International Conference on Combustion Technologies for a Clean Environment, Vilamoura, Portugal, September 1991.) Funded by the National Science Foundation, Environmental Protection Agency, Gas Research Institute and ACERC.
Rotary kilns are used to dispose of many solid wastes and sludges and to thermally treat contaminated soils. In this communication the fates of hydrocarbon and metal species are examined with a view toward optimization of new kiln designs and maximizing existing unit throughout while minimizing pollutant emissions. Initially, process fundamentals are considered to characterize the controlling phenomena. Pilot- and large-scale data are then examined to define practical system complexities. Finally, techniques for data scale-up and performance prediction are summarized. Temperature is clearly the most important parameter with respect to the fate of both metal and hydrocarbon species; hence, heat transfer is often rate limiting. High temperatures favor hydrocarbon evolution, but can also enhance the formation of toxic metal fumes. Both the solid composition and the moisture content can significantly influence the time at temperature required for hydrocarbon destruction and metal vaporization.
Improving bed mixing helps contaminant release but can also aggravate puffing tendencies with batch charging. Full-scale performance predictions currently require a combination of small-scale data and computer modeling. Future work needs to focus on verification of large-scale predictions for complex mixtures and sludges so that expensive trial burns can be minimized.
1991
Solid Waste Incineration in Rotary Kilns
Pershing, D.W.; Lighty, J.S.; Silcox, G.D.; Heap, M.P. and Owens, W.D.
First International Conference on Combustion Technologies for a Clean Environment, Vilamoura, Portugal, September 1991. Funded by the National Science Foundation, Environmental Protection Agency, Gas Research Institute and ACERC.
Rotary kilns are used to dispose of many solid wastes and sludges and to thermally treat contaminated soils. In this communication the fates of hydrocarbon and metal species are examined with a view toward optimization of new kiln designs and maximizing existing unit throughout while minimizing pollutant emissions. Initially, process fundamentals are considered to characterize the controlling phenomena. Pilot- and large-scale data are then examined to define practical system complexities. Finally, techniques for data scale-up and performance prediction are summarized. Temperature is clearly the most important parameter with respect to the fate of both metal and hydrocarbon species; hence, heat transfer is often rate limiting. High temperatures favor hydrocarbon evolution, but can also enhance the formation of toxic metal fumes. Both the solid composition and the moisture content can significantly influence the time at temperature required for hydrocarbon destruction and metal vaporization.
Improving bed mixing helps contaminant release but can also aggravate puffing tendencies with batch charging. Full-scale performance predictions currently require a combination of small-scale data and computer modeling. Future work needs to focus on verification of large-scale predictions for complex mixtures and sludges so that expensive trial burns can be minimized.
1988
Advanced NOx Reduction Processes Using -NH and -CN Compounds in Conjunction with Staged Air Addition
Chen, S.L.; Cole, J.A.; Heap, M.P.; Kramlich, J.C.; McCarthy, J.M. and Pershing, D.W.
Twenty-Second Symposium (International) on Combustion/The Combustion Institute, 1135-1145, 1988. Funded by Pittsburgh Energy Technology Center.
The effectiveness of combustion modifications for the control of nitrogen oxide emissions from coal fired combustors is most often limited by problems due to carbon burnout or flame impingement. This paper presents new data on the use of selective reducing agents suggesting that a hybrid control scheme is possible which uses combustion modification to provide those conditions that optimize the selective reduction process. Very low emission levels appear possible that can presently only be achieved by catalytic reduction. The experimental studies were conducted in a tunnel furnace that simulated the thermal environment within a pulverized coal boiler. Application of each of the agents (ammonia, urea, cyanuric acid, and ammonium sulfate) to an overall fuel lean environment produced NO reduction behavior very similar to that of thermal deNOx. However, if the agent was added to the fuel rich zone of a rich/lean staged combustor, very high NO reductions were obtained after the leanout point. The result of the staging was to extend the effectiveness of the agent to lower temperatures relative to overall lean injection. Parametric variations indicated that in addition to temperature, the most important variable was the rich zone stoichiometry. Kinetic modeling suggests that the rich zone acts primarily as a source of CO. At the rich/lean transition the CO is oxidized and excess OH is produced by the usual chain branching reactions. For low initial CO concentrations the excess radicals are consumed by:
NH3 + OH = NH2 + H2O
HNCO + H = NH2 + CO
The NH2 is then available for reaction with NO to eventually yield N2. The strong rich zone stoichiometry dependence is exerted mainly through the amount of CO supplied to the lean zone. Insufficient CO will limit the extent of the initial NH3 or HNCO reaction.