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Item Cofiring of coal and dairy biomass in a 100,000 btu/hr furnace(2009-05-15) Lawrence, Benjamin DanielDairy biomass (DB) is evaluated as a possible co-firing fuel with coal. Cofiring of DB offers a technique of utilizing dairy manure for power/steam generation, reducing greenhouse gas concerns, and increasing financial returns to dairy operators. The effects of cofiring coal and DB have been studied in a 30 kW (100,000 BTU/hr) burner boiler facility. Experiments were performed with Texas Lignite coal (TXL) as a base line fuel. The combustion efficiency from co-firing is also addressed in the present work. Two forms of partially composted DB fuels were investigated: low ash separated solids and high ash soil surface. Two types of coal were investigated: TXL and Wyoming Powder River Basin coal (WYO). Proximate and ultimate analyses were performed on coal and DB. DB fuels have much higher nitrogen (kg/GJ) and ash content (kg/GJ) than coal. The HHV of TXL and WYO coal as received were 14,000 and 18,000 kJ/kg, while the HHV of the LA-PC-DBSepS and the HA-PC-DB-SoilS were 13,000 and 4,000 kJ/kg. The HHV based on stoichiometric air were 3,000 kJ/kg for both coals and LA-PC-DB-SepS and 2,900 kJ/kg for HA-PC-DB-SoilS. The nitrogen and sulfur loading for TXL and WYO ranged from 0.15 to 0.48 kg/GJ and from 0.33 to 2.67 for the DB fuels. TXL began pyrolysis at 640 K and the WYO at 660 K. The HA-PC-DB-SoilSs began pyrolysis at 530 K and the LA-PC-DB-SepS at 510 K. The maximum rate of volatile release occurred at 700 K for both coals and HA-PC-DB-SoilS and 750K for LA-PC-DB-SepS. The NOx emissions for equivalence ratio (?) varying from 0.9 to 1.2 ranged from 0.34 to 0.90 kg/GJ (0.79 to 0.16 lb/mmBTU) for pure TXL. They ranged from 0.35 to 0.7 kg/GJ (0.82 to 0.16 lb/mmBTU) for a 90:10 TXL:LA-PC-DB-SepS blend and from 0.32 to 0.5 kg/GJ (0.74 to 0.12 lb/mmBTU) for a 80:20 TXL:LA-PC-DB-SepS blend over the same range of ?. In a rich environment, DB:coal cofiring produced less NOx and CO than pure coal. This result is probably due to the fuel bound nitrogen in DB is mostly in the form of urea which reduces NOx to non-polluting gases such as nitrogen (N2).Item Development of a Low NOx Burner System for Coal Fired Power Plants Using Coal and Biomass Blends(2010-01-16) Gomez, Patsky O.The low NOx burner (LNB) is the most cost effective technology used in coal-fired power plants to reduce NOx. Conventional (unstaged) burners use primary air for transporting particles and swirling secondary air to create recirculation of hot gases. LNB uses staged air (dividing total air into primary, secondary and tertiary air) to control fuel bound nitrogen from mixing early and oxidizing to NOx; it can also limit thermal NOx by reducing peak flame temperatures. Previous research at Texas A&M University (TAMU) demonstrated that cofiring coal with feedlot biomass (FB) in conventional burners produced lower or similar levels of NOx but increased CO. The present research deals with i) construction of a small scale 29.31 kW (100,000 BTU/hr) LNB facility, ii) evaluation of firing Wyoming (WYO) coal as the base case coal and cofiring WYO and dairy biomass (DB) blends, and iii) evaluating the effects of staging on NOx and CO. Ultimate and Proximate analysis revealed that WYO and low ash, partially composted, dairy biomass (LA-PC-DB-SepS) had the following heat values and empirical formulas: CH0.6992N0.0122O0.1822S0.00217 and CH_1.2554N_0.0470O_0.3965S_0.00457. The WYO contained 3.10 kg of Ash/GJ, 15.66 kg of VM/GJ, 0.36 kg of N/GJ, and 6.21 kg of O/GJ while LA-PC-DB-SepS contained 11.57 kg of Ash/GJ, 36.50 kg of VM/GJ, 1.50 kg of N/GJ, and 14.48 kg of O/GJ. The construction of a LNB nozzle capable of providing primary, swirled secondary and swirled tertiary air for staging was completed. The reactor provides a maximum residence time of 1.8 seconds under hot flow conditions. WYO and DB were blended on a mass basis for the following blends: 95:5, 90:10, 85:15, and 80:20. Results from firing pure WYO showed that air staging caused a slight decrease of NOx in lean regions (equivalence ratio, greater than or equal to 1.0) but an increase of CO in rich regions (=1.2). For unstaged combustion, cofiring resulted in most fuel blends showing similar NOx emissions to WYO. Staged cofiring resulted in a 12% NOx increase in rich regions while producing similar to slightly lower amounts of NOx in lean regions. One conclusion is that there exists a strong inverse relationship between NOx and CO emissions.Item Effect of Co-Firing Torrefied Woody Biomass with Coal in a 30 kWt Downfired Burner(2014-04-25) Thanapal, Siva SMesquite and juniper can be beneficially utilized for gasification and combustion applications. Torrefaction has been considered to be one of the thermal pretreatment options to improve the chemical (e.g. heat content) and physical (e.g. grindability) properties of raw biomass. A simple three component parallel reaction model (TCM) was formulated to study the effect of heating rate, temperature, residence time and type of biomass on torrefaction process. Typically inert environment (e.g. N_(2), He, Ar) is maintained to prevent oxidation of biomass during torrefaction. A novel method for utilization of carbon dioxide as the pretreatment medium for woody biomass has been investigated in the current study. Both raw and the torrefied biomass (TB) were pyrolyzed using TGA under N_(2). The TB fuels were also fired with coal in a 30 kWt downfired burner to study the NOx emission. In addition, tests were also done using raw biomass (RB) (mesquite and juniper) blended with coal and compared with results obtained from cofiring TB with coal. A zero dimensional model has been developed to predict the combustion performance of cofired fuels. The results are as follows. TGA studies yielded global kinetics based on maximum volatile release (MVR) method. TCM predicts higher loss of hemicellulose upon torrefaction when compared to the other components, cellulose and lignin resulting in improved heat values of TB. Comparable mass loss at lower temperatures, improved grindability, and improved fuel properties were observed upon using CO_(2) as the torrefaction medium. Co-firing 10% by mass of raw mesquite with coal reduced the NOx emission from 420 ppm to 280 ppm for an Equivalence ratio (ER) of 0.9. Further cofiring TB with coal reduced the NOx emission by 10% when compared to base case NOx emission from combustion of pure PRB coal. NOx emission decreased with increase in equivalence ratio. In addition, a term used in the biological literature, respiratory quotient (RQ), is applied to fossil and biomass fuels to rank the potential of fuels to produce carbon dioxide during oxidation process. Lesser the value of ?RQ? of a fuel, lower the global warming potential.Item Essays on Efficiency of the Farm Credit System and Dynamic Correlations in Fossil Fuel Markets(2012-11-28) Dang, Trang Phuong Th 1977-Markets have always changed in response to either exogenous or endogenous shocks. Many large events have occurred in financial and energy markets the last ten years. This dissertation examines market behavior and volatility in agricultural credit and fossil fuel markets under exogenous and endogenous changes in the last ten years. The efficiency of elements within the United States Farm Credit System, a major agricultural lender in the United States, and the dynamic correlation between coal, oil and natural gas prices, the three major fossil fuels, are examined. The Farm Credit system is a key lender in the U.S. agricultural sector, and its performance can influence the performance of the agricultural sector. However, its efficiency in providing credit to the agricultural sector has not been recently examined. The first essay of the dissertation provides assessments on the performance of elements within the Farm Credit System by measuring their relative efficiency using a stochastic frontier model. The second essay addresses the changes in relationship in coal, oil, and natural gas markets with respect to changes and turbulence in the last decade, which has also not been fully addressed in literature. The updated assessment on the relative performance of entities within the Farm Credit System provides information that the Farm Credit Administration and U.S. policy makers can use in their management of and policy toward the Farm Credit System. The measurement of the changes in fossil fuel markets? relationships provides implications for energy investment, energy portfolio anagement, energy risk management, and energy security. It can also be used as a foundation for structuring forecasting models and other models related to energy markets. The dynamic correlations between coal, oil, and natural gas prices are examined using a dynamic conditional correlation multivariate autoregressive conditional heteroskedasticity (MGARCH DCC) model. The estimated results show that the FCS?s five banks and associations with large assets have more efficiently produced credit to the U.S. agricultural sector than smaller sized associations. Management compensation is found to be positively associated with the system?s efficiency. More capital investment and monitoring along with possible consolidation are implied for smaller sized associations to enhance efficiency. On average, the results show that the efficiency of the associations is increasing over time while the average efficiency of the five large banks is more stable. Overall, the associations exhibit a higher variation of efficiency than the five banks. In terms of energy markets the estimates from the MGARCH DCC model indicate significant and changing dynamic correlations and related volatility between the coal, oil, and natural gas prices. The coal price was found to experience more volatility and become more closely related to oil and natural gas prices in recent periods. The natural gas price was found to become more stable and drift away from its historical relationship with oil.Item Low pH waters in the vicinity of Oak Hill Mine : a statistical evaluation of water quality(2014-08) Mercier, Lilith Joy; Sharp, John Malcolm, Jr.Lignite (brown coal) mine-mouth power plants supply a significance portion of electricity generated annually in Texas. Most lignite is produced from the Wilcox Group at surface mines located near a power plant. At the Oak Hill Mine, a lignite mine in the Sabine Uplift area of northeast Texas, the presence of low pH seeps has delayed the release of some portions of the reclaimed land from bond of some until all surface water bodies achieves a stable pH between 6 and 9. But this federal requirement may require an artificial elevation of surface water pH above the natural range for low volume, groundwater-fed surface water bodies in that region. The primary objective of this thesis is to determine whether the distribution of groundwater pH at Oak Hill Mine has become more acidic as a result of mining activity. This study shows that low pH (<6.0) groundwater was common within the mine permit area prior to mining activities; the 95% confidence interval for the median pH of overburden pre-disturbance (OP) wells is 4.7 to 4.8. This naturally occurring, low pH groundwater is produced by the weathering (oxidative dissolution) of pyrite in the Carrizo Sand and overburden Wilcox Group. Although low pH groundwater occurs naturally within the Oak Hill Mine permit area, groundwater pH has also decreased (groundwater has become more acidic) as a result of mining activities. The 95% confidence interval for the median pH of overburden reclamation (OR) wells is 4.1 to 4.2, indicating that mining activities has changed the median groundwater pH by approximately -0.5 standard units. Underburden groundwater is less acidic than overburden groundwater, but also becomes more acidic after mining activities. Underburden pre-disturbance (UP) groundwater has a median pH of 6.2 to 6.3 at the 95% confidence interval, whereas underburden reclamation (UR) groundwater has a median pH of 5.6 to 5.8 at the 95% confidence interval.Item Mercury emission behavior during isolated coal particle combustion(2009-05-15) Puchakayala, Madhu BabuOf all the trace elements emitted during coal combustion, mercury is most problematic. Mercury from the atmosphere enters into oceanic and terrestrial waters. Part of the inorganic Hg in water is converted into organic Hg (CH3Hg), which is toxic and bioaccumulates in human and animal tissue. The largest source of human-caused mercury air emissions in the U.S is from combustion coal, a dominant fuel used for power generation. The Hg emitted from plants primarily occurs in two forms: elemental Hg and oxidized Hg (Hg2+). The coal chlorine content and ash composition, gas temperature, residence time and presence of different gases will decide the speciation of Hg into Hg0 and Hg2+. For Wyoming coal the concentrations of mercury and chlorine in coal are 120ppb and 140ppb. In order to understand the basic process of formulation of HgCl2 and Hg0 a numerical model is developed in the current work to simulate in the detail i) heating ii) transient pyrolysis of coal and evolution of mercury and chlorine, iii) gas phase oxidation iv) reaction chemistry of Hg and v) heterogeneous oxidation of carbon during isolated coal particle combustion. The model assumes that mercury and chlorine are released as a part of volatiles in the form of elemental mercury and HCl. Homogenous reaction are implemented for the oxidation of mercury. Heterogeneous Hg reactions are ignored. The model investigates the effect of different parameters on the extent of mercury oxidation; particle size, ambient temperature, volatile matter, blending coal with high chlorine coal and feedlot biomass etc,. Mercury oxidation is increased when the coal is blended with feedlot biomass and high chlorine coal and Hg % conversion to HgCl2 increased from 10% to 90% when 20% FB is blended with coal. The ambient temperature has a negative effect on mercury oxidation, an increase in ambient temperature resulted in a decrease in the mercury oxidation. The percentage of oxidized mercury increases from 9% to 50% when the chlorine concentration is increased from 100ppm to 1000ppm. When the temperature is decreased from 1950 K to 950 K, the percentage of mercury oxidized increased from 3% to 27%.Item Novel approaches in determining baseline information on annual disposal rates and trace element content of U.S. coal combustion residues : a response to EPA’s June 2010 proposed disposal rule(2010-12) Chwialkowski, Natalia Ewa; Groat, Charles G.; Grimshaw, Thomas W.; Kyle, RichardAlthough products of coal combustion (PCCs) such as coal ash are currently exempted from classification as a hazardous waste in the United States under the 1976 Resource Conservation and Recovery Act (RCRA), the U.S. Environmental Protection Agency (EPA) is now revising a proposed rule to modify disposal practices for these materials in order to prevent contamination of ground- and surface water sources by leached trace elements. This paper analyzes several aspects of EPA’s scientific reasoning for instating the rule, with the intent of answering the following questions: 1) Are EPA’s cited values for PCC production and disposal accurate estimates of annual totals?; 2) In what ways can EPA’s leaching risk modeling assessment be improved?; 3) What is the total quantity of trace elements contained within all PCCs disposed annually?; and 4) What would be the potential costs and feasibility of reclassifying PCCs not under RCRA, but under existing NRC regulations as low-level radioactive waste (LLRW)? Among the results of my calculations, I found that although EPA estimates for annual PCC disposal are 20% larger than industry statistics, these latter values appear to be closer to reality. Second, EPA appears to have significantly underestimated historical PCC disposal: my projections indicate that EPA’s maximum estimate for the quantity of fly ash landfilled within the past 90 years was likely met by production in the last 30 years alone, if not less. Finally, my analysis indicates that while PCCs may potentially meet the criteria for reclassification as low-level radioactive waste by NRC, the cost of such regulation would be many times that of the EPA June proposed disposal rule ($220-302 billion for PCCs disposed in 2008 alone, versus $1.47 billion per year for the Subtitle C option and $236-587 million for Subtitle D regulatory options).Item NOx reduction with the use of feedlot biomass as a reburn fuel(2009-05-15) Goughnour, Paul GordonCoal fired power plants produce NOx at unacceptable levels. In order to control these emissions without major modifications to the burners, additional fuel called reburn fuel is fired under rich conditions (10-30 % by heat) after the coal burners. Additional air called overfire air (about 20 % of total air) is injected in order to complete combustion. Typically reburn fuel is natural gas (NG). From previous research at TAMU, it was found that firing feedlot biomass (FB) as reburn fuel lowers the NOx emission at significant levels compared to NG. The present research was conducted to determine the optimum operating conditions for the reduction of NOx. Experiments were performed in a small scale 29.3 kW (100,000 BTU/hr) reactor using low ash partially composted FB (LA PC FB) with equivalence ratio ranging from 1 to 1.15. The results of these experiments show that NOx levels can be reduced by as much as 90% - 95 % when firing pure LA PC FB and results are almost independent of. The reburn fuel was injected with normal air and then vitiated air (12.5 % O2); further the angles of reburn injector were set normal to the main gas flow and at 45-degrees upward. For LA PC FB no significant changes were observed; but high ash PC FB revealed better reductions with 45-degrees injector and vitiated air. This new technology has the potential to reduce NOx emissions in coal fired boilers located near cattle feedlots and also relieves the cattle industry of the waste.Item San Antonio's energy future(2006-08) Pearson, Eli Richard; Butler, Kent S.As demand for electricity increases, utilities turn to demand-side or supply-side responses in order to reduce demand or add supply to their energy portfolio. CPS Energy, a municipal utility owned by the City of San Antonio, Texas, recently broke ground on a new coal plant to meet rising demand for electricity. This report examines the public debate that accompanied the proposal and investigates the possibilities of other solutions for utilities to meet demand. Two case studies, overviews of the utilities in Austin, Texas, and Sacramento, California, provide insight into the considerations for utilities with renewable energy and demand-side management (DSM) in their energy portfolio. This professional report will evaluate these case studies and apply lessons learned to the case of CPS Energy in San Antonio, and report on the options available to utilities considering conventional supply-side additions and demand-side management.