Engineering Technology Conference on Energy, Parts A and B, 2002
A Co-firing technology with coal:biomass blends is expected to reduce land application requiremen... more A Co-firing technology with coal:biomass blends is expected to reduce land application requirements for manure based biomass wastes, and provide a renewable, low cost, and zero net fossil based CO2 fuel. The choice of low BTU biomass fuels may include conventional agricultural or unconventional animal based biomass fuels depending upon local availability and transportation costs. For power plants located near feedlots where cattle are fattened for slaughter, the best choice of renewable biomass fuel is feedlot manure, properly referred to as feedlot biomass (FB). Coal can be mixed with FB in a 90:10 (coal:FB) ratio by mass and fired in existing boiler burners. A 30 KW (100,000 BTU/hr) boiler burner facility was built and tested for firing coal or coal-FB blends at Texas A&M University. FB has a moisture content ranging from 20% to 40% moisture, but most of the previous data have been generated using low moisture FB (<10% moisture) due to problems processing moist manure. The curr...
Due to increasingly harsh environmental regulations, the demand for low sulfur (S) coal has drama... more Due to increasingly harsh environmental regulations, the demand for low sulfur (S) coal has dramatically increased. This increase in demand is expected to cause the price of coal to rise. Such a scenario has caused the utilities to explore the possibilities of supplementing coal with fuel alternatives such as the byproducts of process industries. The supplemental fuel for utilities located near feedlots (e.g. Northwest Texas) happens to be feedlot manure. Feedlot manure is attractive because it is nearly ten times cheaper than coal and is relatively inexpensive to transport. A small scale boiler burner facility has been constructed to simulate a utility class boiler. Experiments were conducted with coal only and then for coal/feedlot manure. Three types of feedlot manure are examined; raw feedlot manure, partially composted feedlot manure, and finished composted feedlot manure. Performance characteristics and emission data were taken for each case. A summary of the results is as follows: (1) Low sulfur Wyoming coal was fired and a gasification efficiency of 66 % was measured; (2) Emissions measurements were recorded and it was seen that emissions of NO{sub x} and SO{sub 2} increased as the burnt mass fraction increased. however, all emissions were within NSPS guidelines; (3)more » The successful firing of coal and feedlot manure was achieved, a gasification efficiency in the range of 86% was measured, which is higher than 66% obtained when firing coal along; (4) When the fuel blend is fully burnt, the NO{sub x} emissions with the blend firing was lower than the firing with coal alone.« less
A brief overview is presented of various energy units; terminology; and basic concepts in energy ... more A brief overview is presented of various energy units; terminology; and basic concepts in energy conversion including pyrolysis, gasification, ignition, and combustion. Detailed sets of fuel properties of coal, agricultural biomass, and animal waste are presented so that ...
Volume 3: Coal, Biomass and Alternative Fuels; Cycle Innovations; Electric Power; Industrial and Cogeneration, 2015
The integrated gasification and combined cycle (IGCC), uses low rank coal (higher moisture and vo... more The integrated gasification and combined cycle (IGCC), uses low rank coal (higher moisture and volatile contents and lower heating value) as fuel for gasification (e.g Texaco gasifier of Tampa electric with low ash coal) and convert the solid fuel into synthetic gas mainly consisting of CO and H2. During the storage of fresh low rank but highly reactive coals near the IGCC plants, the coals undergo drying and low temperature atmospheric oxidation which raises the temperature, reduces the moisture and eventually causes spontaneous ignition if the temperature rises above about 800 °C in the coal piles for bituminous and 500 °C for lignite coals. Thus it is of interest to understand the dewatering mechanism of the low rank lignite by drying samples using N2, CO2 and air (which represents partial oxidation) as drying mediums. Fundamental experiments were performed on dewatering of coal samples using thermo-gravimetric analysis (TGA) with different particle sizes and drying mediums. A wi...
.................................................................................................... more .............................................................................................................................................................. 4
A combustion model using three mixture fractions has been developed for accurate simulation of co... more A combustion model using three mixture fractions has been developed for accurate simulation of coal:manure combustion. This model treats coal and manure off gases separately. This model has been incorporated into the PCGC-2 (Pulverized Coal Gasification and Combustion--2-Dimensional, from Brigham Young University) code. Numerical results of this simulation are presented. The results are compared with those from the two mixture fraction model of the original code. While the overall simulation results from both models appear similar, there are significant differences in local temperature predictions in the near burner region.
Concentrated animal feeding operations (both slaughter and dairy cattle) lead to land, water, and... more Concentrated animal feeding operations (both slaughter and dairy cattle) lead to land, water, and air pollution if waste storage and handling systems are not effectively managed. At the same time, cattle biomass (CB), which includes both slaughter/feedlot biomass (FB) and dairy biomass (DB), have the potential to be a source of green energy at coal-fired power plants. Part I presented results on NOx reductions with pure FB or Coal: FB blends as reburn fuels. Part II deals with results from reburning with pure DB or Coal: DB blends as reburn fuels. A mixture of NG with a small amount of NH3 was used to generate the baseline NOx of 400–420 ppm (or 185–194 g/GJ). NOx emissions were found to be reduced by as much as 96% when reburning with FB. The effects of reburn fuel type, equivalence ratio (ERRBZ) in the reburn zone, vitiated air, several injection configurations of reburn fuel and initial NO concentrations on NOx emissions were investigated. The ERRBZ shows a significant effect on ...
Cattle biomass (CB or manure from cattle) is proposed as reburn fuel under slightly fuel-rich con... more Cattle biomass (CB or manure from cattle) is proposed as reburn fuel under slightly fuel-rich conditions. The CB includes wastes from cattle feedlots (cattle grown in feedlots to slaughter weights of 450–640 kg) termed as Feedlot Biomass (FB) and cattle wastes from dairy farms termed as Dairy Biomass (DB). NOx emissions from coal-fired power plants can be reduced by using pure CB and Coal:CB mixtures as reburn fuels (10~30% by heat) injected after the primary combustion region. Experiments with Coal:CB mixtures as reburn fuels were performed using the 30 kW burner facility. Part I deals with results from experiments using pure FB and Coal:FB blends as reburn fuels while Part II presents results on extent of NOx reduction using pure DB and Coal:DB blends as reburn fuels (RF). In the current work, results on NOx emission are presented with FB and Coal:FB blends as RF. The parametric studies include: equivalence ratio in reburn zone (ERRBZ), vitiated air, angle of reburn nozzles, prese...
A literature review describes the development of interactive and group combustion (GC) studies, t... more A literature review describes the development of interactive and group combustion (GC) studies, the bubble combustion (BC) model, the pulverized coal gasification and combustion (PCGC) model for burners, the packet combustion (PACC) model for engines, and various NO/sub x/ models. The group combustion (GC) model for a cloud of coal-water slurry drops in a confined volume is described with correction factors. The heat transfer model is given with results for nodal temperatures of cylinder head utilizing iron componet through an engine cycle. The NO/sub x/ model is also given with incorporation into the PACC model;results are given for NO/sub x/ emissions as a function of crank angle, injection timing, inlet manifold temperature etc. Results from the GC model are currently being incorporated in the PACC model. The correction factor from the nonsteady GC model varies from 0.2 to 0.1. Pressure vs time plot confirms GE bomb reactor data. Ignition starts as a heterogeneous process, leadin...
Carbon dioxide (CO2) is one of the greenhouse gases which cause global warming. The amount of fos... more Carbon dioxide (CO2) is one of the greenhouse gases which cause global warming. The amount of fossil fuels consumed to meet the demands in the areas of power and transportation is projected to increase in the upcoming years. Depending on carbon content, each power plant fuel has its own potential to produce carbon dioxide. Similarly, the humans consume food containing carbohydrates (CH), fat, and protein which emit CO2 due to metabolism. The biology literature uses respiratory quotient (RQ), defined as the ratio of CO2 moles exhausted per mole of O2 consumed within the body, to estimate CO2 loading in the blood stream and CO2 in nasal exhaust. Here, we apply that principle in the field of combustion to relate the RQ to CO2 emitted in tons per GJ of energy released when a fuel is combusted. The RQ value of a fuel can be determined either from fuel chemical formulae (from ultimate analyses for most liquid and solid fuels of known composition) or from exhaust gas analyses. RQ ranges fr...
Many practical combustion systems such as residential gas burners contain dense groupings or clus... more Many practical combustion systems such as residential gas burners contain dense groupings or clusters of jet flames with sufficiently small spacing between them, which causes flame interaction. The interaction effect, due in part to Oxygen deficiency in the interstitial space between the flames, causes the spreading of flames, which may merge together to form larger group flames. This interactive effect is studied analytically by revisiting the laminar isolated flame theory for 2D jets, for which similarity solutions are readily available in compressible form, and symmetrical interaction zones can be observed. Flame characteristics were studied by obtaining analytical expressions for flame specific parameters such as height and width, lift-off height and blow-off velocity, air entrainment and mixing layer growth. The theory for multiple interacting jets describes an approximate criterion for interburner spacing at which flame interaction and group flame formation are first observed....
Volume 6: Energy Systems: Analysis, Thermodynamics and Sustainability, 2007
ABSTRACT Researchers at Texas A&amp;M University have studied properties of cattle biomass (C... more ABSTRACT Researchers at Texas A&amp;M University have studied properties of cattle biomass (CB or manure) fuels and their possible utility in combustion systems. Larger, more concentrated animal feeding operations (CAFO) and farms make manure disposal more difficult. At the same time, due to the concentration of the manure, the CAFOs can be a source of a more feasible and reliable CB feedstock for fossil fuel supplementation and emissions reduction technologies. This paper reviews the history of work conducted on animal biomass fuels and current research and experiments undertaken by Texas A&amp;M University (TAMU) System research personnel. Feedlot biomass (FB), dairy biomass (DB), and chicken litter biomass (LB) are considered here. When cofiring with coal under rich conditions, the CB has the potential to reduce NOx and Hg emissions. Reburning coal with CB can be just as effective as and possibly more economical than reburning with conventional fuels like natural gas. In addition to cofiring and reburning, another possible energy conversion method is gasification of cattle biomass with air and air-steam oxidizing agents that can produce synthetic gases which can then be used in a variety of different combustion systems. The economic feasibility of utilizing animal-based biomass on existing coal-fired power plants is greatly dependent on the relative cost of coal, the biomass transportation distance to the combustion facility, and numerous other factors. Even though most of the methodologies and procedures, in this paper, deal with CB, similar schemes can be undertaken for most other animal or solid wastes.
Reburn technology is used in power plants in order to comply with NOx emission levels in existing... more Reburn technology is used in power plants in order to comply with NOx emission levels in existing coal fired power plants. While the main fuel coal supplies almost 80-90% of power (% by heat), additional fuel, called reburn fuel and supplying the remaining power, is fired in a secondary combustion chamber to control the NOx. This reburn fuel is typically natural gas. However, recent small scale tests at a 30 kW (100,000 BTU/hr) boiler burner facility co-firing coal with feedlot manure (“feedlot biomass”, FB) suggested that FB can serve as a more effective reburn fuel than natural gas. The boiler burner facility used was modified to fire premixed propane fuel with ammonia injection in order to simulate NOx in the exhaust from coal-fired units. Experiments were performed with coal or FB as reburn fuels in order to determine the relative performance. The FB is partially composted, ground manure from a cattle feedlot in the Texas High Plains. Results indicated NOX reduction with FB is almost 80 % while that of coal was only about 40 %. Further, the % NOx reduction was less sensitive to stoichiometry compared to coal. Thus, a reburn technology with FB as the reburn fuel may reduce NOx emissions while providing a utilization method for FB. It is speculated that most of the N in FB exists as NH3, and volatile matter of FB (little fixed carbon) is twice that of coal and hence FB serves as a better reburn fuel in controlling the NOx emission. Since FB fuel for co-firing or reburn normally contains high P and high ash, cattle feeding trials were conducted to produce FB with low ash/low P content as well. Co-fire test results were reported for low P-FB, but reburn results with low P-FB are not yet available.
Engineering Technology Conference on Energy, Parts A and B, 2002
A Co-firing technology with coal:biomass blends is expected to reduce land application requiremen... more A Co-firing technology with coal:biomass blends is expected to reduce land application requirements for manure based biomass wastes, and provide a renewable, low cost, and zero net fossil based CO2 fuel. The choice of low BTU biomass fuels may include conventional agricultural or unconventional animal based biomass fuels depending upon local availability and transportation costs. For power plants located near feedlots where cattle are fattened for slaughter, the best choice of renewable biomass fuel is feedlot manure, properly referred to as feedlot biomass (FB). Coal can be mixed with FB in a 90:10 (coal:FB) ratio by mass and fired in existing boiler burners. A 30 KW (100,000 BTU/hr) boiler burner facility was built and tested for firing coal or coal-FB blends at Texas A&M University. FB has a moisture content ranging from 20% to 40% moisture, but most of the previous data have been generated using low moisture FB (<10% moisture) due to problems processing moist manure. The curr...
Due to increasingly harsh environmental regulations, the demand for low sulfur (S) coal has drama... more Due to increasingly harsh environmental regulations, the demand for low sulfur (S) coal has dramatically increased. This increase in demand is expected to cause the price of coal to rise. Such a scenario has caused the utilities to explore the possibilities of supplementing coal with fuel alternatives such as the byproducts of process industries. The supplemental fuel for utilities located near feedlots (e.g. Northwest Texas) happens to be feedlot manure. Feedlot manure is attractive because it is nearly ten times cheaper than coal and is relatively inexpensive to transport. A small scale boiler burner facility has been constructed to simulate a utility class boiler. Experiments were conducted with coal only and then for coal/feedlot manure. Three types of feedlot manure are examined; raw feedlot manure, partially composted feedlot manure, and finished composted feedlot manure. Performance characteristics and emission data were taken for each case. A summary of the results is as follows: (1) Low sulfur Wyoming coal was fired and a gasification efficiency of 66 % was measured; (2) Emissions measurements were recorded and it was seen that emissions of NO{sub x} and SO{sub 2} increased as the burnt mass fraction increased. however, all emissions were within NSPS guidelines; (3)more » The successful firing of coal and feedlot manure was achieved, a gasification efficiency in the range of 86% was measured, which is higher than 66% obtained when firing coal along; (4) When the fuel blend is fully burnt, the NO{sub x} emissions with the blend firing was lower than the firing with coal alone.« less
A brief overview is presented of various energy units; terminology; and basic concepts in energy ... more A brief overview is presented of various energy units; terminology; and basic concepts in energy conversion including pyrolysis, gasification, ignition, and combustion. Detailed sets of fuel properties of coal, agricultural biomass, and animal waste are presented so that ...
Volume 3: Coal, Biomass and Alternative Fuels; Cycle Innovations; Electric Power; Industrial and Cogeneration, 2015
The integrated gasification and combined cycle (IGCC), uses low rank coal (higher moisture and vo... more The integrated gasification and combined cycle (IGCC), uses low rank coal (higher moisture and volatile contents and lower heating value) as fuel for gasification (e.g Texaco gasifier of Tampa electric with low ash coal) and convert the solid fuel into synthetic gas mainly consisting of CO and H2. During the storage of fresh low rank but highly reactive coals near the IGCC plants, the coals undergo drying and low temperature atmospheric oxidation which raises the temperature, reduces the moisture and eventually causes spontaneous ignition if the temperature rises above about 800 °C in the coal piles for bituminous and 500 °C for lignite coals. Thus it is of interest to understand the dewatering mechanism of the low rank lignite by drying samples using N2, CO2 and air (which represents partial oxidation) as drying mediums. Fundamental experiments were performed on dewatering of coal samples using thermo-gravimetric analysis (TGA) with different particle sizes and drying mediums. A wi...
.................................................................................................... more .............................................................................................................................................................. 4
A combustion model using three mixture fractions has been developed for accurate simulation of co... more A combustion model using three mixture fractions has been developed for accurate simulation of coal:manure combustion. This model treats coal and manure off gases separately. This model has been incorporated into the PCGC-2 (Pulverized Coal Gasification and Combustion--2-Dimensional, from Brigham Young University) code. Numerical results of this simulation are presented. The results are compared with those from the two mixture fraction model of the original code. While the overall simulation results from both models appear similar, there are significant differences in local temperature predictions in the near burner region.
Concentrated animal feeding operations (both slaughter and dairy cattle) lead to land, water, and... more Concentrated animal feeding operations (both slaughter and dairy cattle) lead to land, water, and air pollution if waste storage and handling systems are not effectively managed. At the same time, cattle biomass (CB), which includes both slaughter/feedlot biomass (FB) and dairy biomass (DB), have the potential to be a source of green energy at coal-fired power plants. Part I presented results on NOx reductions with pure FB or Coal: FB blends as reburn fuels. Part II deals with results from reburning with pure DB or Coal: DB blends as reburn fuels. A mixture of NG with a small amount of NH3 was used to generate the baseline NOx of 400–420 ppm (or 185–194 g/GJ). NOx emissions were found to be reduced by as much as 96% when reburning with FB. The effects of reburn fuel type, equivalence ratio (ERRBZ) in the reburn zone, vitiated air, several injection configurations of reburn fuel and initial NO concentrations on NOx emissions were investigated. The ERRBZ shows a significant effect on ...
Cattle biomass (CB or manure from cattle) is proposed as reburn fuel under slightly fuel-rich con... more Cattle biomass (CB or manure from cattle) is proposed as reburn fuel under slightly fuel-rich conditions. The CB includes wastes from cattle feedlots (cattle grown in feedlots to slaughter weights of 450–640 kg) termed as Feedlot Biomass (FB) and cattle wastes from dairy farms termed as Dairy Biomass (DB). NOx emissions from coal-fired power plants can be reduced by using pure CB and Coal:CB mixtures as reburn fuels (10~30% by heat) injected after the primary combustion region. Experiments with Coal:CB mixtures as reburn fuels were performed using the 30 kW burner facility. Part I deals with results from experiments using pure FB and Coal:FB blends as reburn fuels while Part II presents results on extent of NOx reduction using pure DB and Coal:DB blends as reburn fuels (RF). In the current work, results on NOx emission are presented with FB and Coal:FB blends as RF. The parametric studies include: equivalence ratio in reburn zone (ERRBZ), vitiated air, angle of reburn nozzles, prese...
A literature review describes the development of interactive and group combustion (GC) studies, t... more A literature review describes the development of interactive and group combustion (GC) studies, the bubble combustion (BC) model, the pulverized coal gasification and combustion (PCGC) model for burners, the packet combustion (PACC) model for engines, and various NO/sub x/ models. The group combustion (GC) model for a cloud of coal-water slurry drops in a confined volume is described with correction factors. The heat transfer model is given with results for nodal temperatures of cylinder head utilizing iron componet through an engine cycle. The NO/sub x/ model is also given with incorporation into the PACC model;results are given for NO/sub x/ emissions as a function of crank angle, injection timing, inlet manifold temperature etc. Results from the GC model are currently being incorporated in the PACC model. The correction factor from the nonsteady GC model varies from 0.2 to 0.1. Pressure vs time plot confirms GE bomb reactor data. Ignition starts as a heterogeneous process, leadin...
Carbon dioxide (CO2) is one of the greenhouse gases which cause global warming. The amount of fos... more Carbon dioxide (CO2) is one of the greenhouse gases which cause global warming. The amount of fossil fuels consumed to meet the demands in the areas of power and transportation is projected to increase in the upcoming years. Depending on carbon content, each power plant fuel has its own potential to produce carbon dioxide. Similarly, the humans consume food containing carbohydrates (CH), fat, and protein which emit CO2 due to metabolism. The biology literature uses respiratory quotient (RQ), defined as the ratio of CO2 moles exhausted per mole of O2 consumed within the body, to estimate CO2 loading in the blood stream and CO2 in nasal exhaust. Here, we apply that principle in the field of combustion to relate the RQ to CO2 emitted in tons per GJ of energy released when a fuel is combusted. The RQ value of a fuel can be determined either from fuel chemical formulae (from ultimate analyses for most liquid and solid fuels of known composition) or from exhaust gas analyses. RQ ranges fr...
Many practical combustion systems such as residential gas burners contain dense groupings or clus... more Many practical combustion systems such as residential gas burners contain dense groupings or clusters of jet flames with sufficiently small spacing between them, which causes flame interaction. The interaction effect, due in part to Oxygen deficiency in the interstitial space between the flames, causes the spreading of flames, which may merge together to form larger group flames. This interactive effect is studied analytically by revisiting the laminar isolated flame theory for 2D jets, for which similarity solutions are readily available in compressible form, and symmetrical interaction zones can be observed. Flame characteristics were studied by obtaining analytical expressions for flame specific parameters such as height and width, lift-off height and blow-off velocity, air entrainment and mixing layer growth. The theory for multiple interacting jets describes an approximate criterion for interburner spacing at which flame interaction and group flame formation are first observed....
Volume 6: Energy Systems: Analysis, Thermodynamics and Sustainability, 2007
ABSTRACT Researchers at Texas A&amp;M University have studied properties of cattle biomass (C... more ABSTRACT Researchers at Texas A&amp;M University have studied properties of cattle biomass (CB or manure) fuels and their possible utility in combustion systems. Larger, more concentrated animal feeding operations (CAFO) and farms make manure disposal more difficult. At the same time, due to the concentration of the manure, the CAFOs can be a source of a more feasible and reliable CB feedstock for fossil fuel supplementation and emissions reduction technologies. This paper reviews the history of work conducted on animal biomass fuels and current research and experiments undertaken by Texas A&amp;M University (TAMU) System research personnel. Feedlot biomass (FB), dairy biomass (DB), and chicken litter biomass (LB) are considered here. When cofiring with coal under rich conditions, the CB has the potential to reduce NOx and Hg emissions. Reburning coal with CB can be just as effective as and possibly more economical than reburning with conventional fuels like natural gas. In addition to cofiring and reburning, another possible energy conversion method is gasification of cattle biomass with air and air-steam oxidizing agents that can produce synthetic gases which can then be used in a variety of different combustion systems. The economic feasibility of utilizing animal-based biomass on existing coal-fired power plants is greatly dependent on the relative cost of coal, the biomass transportation distance to the combustion facility, and numerous other factors. Even though most of the methodologies and procedures, in this paper, deal with CB, similar schemes can be undertaken for most other animal or solid wastes.
Reburn technology is used in power plants in order to comply with NOx emission levels in existing... more Reburn technology is used in power plants in order to comply with NOx emission levels in existing coal fired power plants. While the main fuel coal supplies almost 80-90% of power (% by heat), additional fuel, called reburn fuel and supplying the remaining power, is fired in a secondary combustion chamber to control the NOx. This reburn fuel is typically natural gas. However, recent small scale tests at a 30 kW (100,000 BTU/hr) boiler burner facility co-firing coal with feedlot manure (“feedlot biomass”, FB) suggested that FB can serve as a more effective reburn fuel than natural gas. The boiler burner facility used was modified to fire premixed propane fuel with ammonia injection in order to simulate NOx in the exhaust from coal-fired units. Experiments were performed with coal or FB as reburn fuels in order to determine the relative performance. The FB is partially composted, ground manure from a cattle feedlot in the Texas High Plains. Results indicated NOX reduction with FB is almost 80 % while that of coal was only about 40 %. Further, the % NOx reduction was less sensitive to stoichiometry compared to coal. Thus, a reburn technology with FB as the reburn fuel may reduce NOx emissions while providing a utilization method for FB. It is speculated that most of the N in FB exists as NH3, and volatile matter of FB (little fixed carbon) is twice that of coal and hence FB serves as a better reburn fuel in controlling the NOx emission. Since FB fuel for co-firing or reburn normally contains high P and high ash, cattle feeding trials were conducted to produce FB with low ash/low P content as well. Co-fire test results were reported for low P-FB, but reburn results with low P-FB are not yet available.
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Papers by Kalyan Annamalai