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Next Generation Geothermal Power Plants

Description: A number of current and prospective power plant concepts were investigated to evaluate their potential to serve as the basis of the next generation geothermal power plant (NGGPP). The NGGPP has been envisaged as a power plant that would be more cost competitive (than current geothermal power plants) with fossil fuel power plants, would efficiently use resources and mitigate the risk of reservoir under-performance, and minimize or eliminate emission of pollutants and consumption of surface and ground water. Power plant concepts were analyzed using resource characteristics at ten different geothermal sites located in the western United States. Concepts were developed into viable power plant processes, capital costs were estimated and levelized busbar costs determined. Thus, the study results should be considered as useful indicators of the commercial viability of the various power plants concepts that were investigated. Broadly, the different power plant concepts that were analyzed in this study fall into the following categories: commercial binary and flash plants, advanced binary plants, advanced flash plants, flash/binary hybrid plants, and fossil/geothed hybrid plants. Commercial binary plants were evaluated using commercial isobutane as a working fluid; both air-cooling and water-cooling were considered. Advanced binary concepts included cycles using synchronous turbine-generators, cycles with metastable expansion, and cycles utilizing mixtures as working fluids. Dual flash steam plants were used as the model for the commercial flash cycle. The following advanced flash concepts were examined: dual flash with rotary separator turbine, dual flash with steam reheater, dual flash with hot water turbine, and subatmospheric flash. Both dual flash and binary cycles were combined with other cycles to develop a number of hybrid cycles: dual flash binary bottoming cycle, dual flash backpressure turbine binary cycle, dual flash gas turbine cycle, and binary gas turbine cycle. Results of this study indicate that dual flash type plants are ...
Date: September 1, 1995
Creator: Brugman, John; Hattar, Mai; Nichols, Kenneth & Esaki, Yuri
Partner: UNT Libraries Government Documents Department

Liquid natural gas as a transportation fuel in the heavy trucking industry. Fourth quarterly progress report, April 1, 1995--June 30, 1995

Description: This project encompasses the first year of a proposed three year project with emphasis focused on LNG research issues that may be categorized as direct diesel replacement with LNG fuel, and long term storage/utilization of LNG vent gases produced by tank storage and fueling/handling operation. In addition, a potential new utilization of LNG fuel has been found, as a part of this work on the fundamental nature of adsorption of LNG vent gases in higher hydrocarbons; follow on research for this and other related applications and transfer of technology are proceeding at this time.
Date: September 1, 1995
Creator: Sutton, W.H.
Partner: UNT Libraries Government Documents Department

Natural gas monthly, November 1995

Description: The Natural Gas Monthly (NGM) highlights activities, events, and analyses of interest to public and private sector organizations associated with the natural gas industry. Volume and price data are presented each month for natural gas production, distribution, consumption, and interstate pipeline activities. Producer-related activities and underground storage data are also reported. From time to time, the NGM features articles designed to assist readers in using and interpreting natural gas information.
Date: December 5, 1995
Partner: UNT Libraries Government Documents Department

Fundamental studies for sol-gel derived gas-separation membranes

Description: We prepared silica membranes using sol-gel techniques and explored the effects of postdeposition sintering, capillary stresses developed during drying, and surface derivatization of the membranes with titanium iso-propoxide. We observed that both partial sintering of membranes and development of larger-capillary stresses during membrane formation lead to consolidation of the membrane structure as evidenced by increased ideal separation factors, e.g. {alpha}CO{sub 2}2/CH{sub 4} > 250 over the temperature range of 160 to 220 C. Surface derivatization was also shown to be an effective tool to reduce the membrane pore size in an angstrom by angstrom fashion, resulting in comparable separation factors. What`s more, the altered pore surface chemistry of TiO{sub 2} derivatized membranes may lead to improved stability and impart catalytic properties to the membrane surface.
Date: July 1, 1995
Creator: Brinker, C.J. & Sehgal, R.
Partner: UNT Libraries Government Documents Department

Novel carbons from Illinois coal for natural gas storage. Quarterly report, 1 December 1994--28 February 1995

Description: The goal of this project is to develop a technology for producing microengineered adsorbent carbons from Illinois coal and to evaluate the potential application of these novel materials for storing natural gas for use in emerging low pressure, natural gas vehicles (NGV). The focus of the project is to design and engineer adsorbents that meet or exceed the performance and cost targets established for low-pressure natural gas storage materials. Potentially, about two million tons of adsorbent could be consumed in natural gas vehicles by year 2000. If successful, the results obtained in this project could lead to the use of Illinois coal in a sowing and profitable market that could exceed 6 million tons per year. During this reporting period, a series of experiments were made to evaluate the effect of coal pre-oxidation, coal pyrolysis, and char activation on the surface area development and methane adsorption capacity of activated carbons/chars made from IBC-102. The optimum production conditions were determined to be: coal oxidation in air at 225C, oxicoal (oxidized coal); devolatilization in nitrogen at 400C; and char gasification in 50% steam in nitrogen at 850C. Nitrogen BET surface areas of the carbon products ranged from 800--1100 m{sup 2}/g. Methane adsorption capacity of several Illinois coal derived chars and a 883 m{sup 2}/g commercial activated carbon were measured using a pressurized thermogaravimetric analyzer at pressures up to 500 psig. Methane adsorption capacity (g/g) of the chars were comparable to that of the commercial activated carbon manufactured by Calgon Carbon. It was determined that the pre-oxidation is a key processing step for producing activated char/carbon with high surface area and high methane adsorption capacity. The results to date are encouraging and warrant further research and development in tailored activated char from Illinois coal for natural gas storage.
Date: December 31, 1995
Creator: Rostam-Abadi, M.; Sun, Jian; Lizzio, A.A. & Fatemi, M.
Partner: UNT Libraries Government Documents Department

Reserve estimates in western basins. Part 2: Piceance Basin

Description: This study characterizes an extremely large gas resource located in low permeability, sandstone reservoirs of the Mesaverde group in the Piceance Basin, Colorado. Total in place resource is estimated at 307.3 Tcf. Via application of geologic, engineering and economic criteria, the portion of this resource potentially recoverable as reserves is estimated. Those volumes estimated include probable, possible and potential categories and total 5.8 Tcf as a mean estimate of recoverable gas for all plays considered in the basin. About 82.6% of the total evaluated resource is contained within sandstones that have extremely poor reservoir properties with permeabilities considered too low for commerciality using current frac technology. Cost reductions and technology improvements will be required to unlock portions of this enormous resource. Approximately 2.7% of the total resource is contained within sandstone reservoirs which do not respond to massive hydraulic fracture treatments, probably due to their natural lenticular nature. Approximately 6.8% of the total resource is located in deeply buried settings below deepest established production. Approximately 7.9% of the total resource is considered to represent tight reservoirs that may be commercially exploited using today`s hydraulic fracturing technology. Recent technology advances in hydraulic fracturing practices in the Piceance Basin Mesaverde has resulted in a marked improvement in per well gas recovery which, where demonstrated, has been incorporated into the estimates provided in this report. This improvement is so significant in changing the risk-reward relationship that has historically characterized this play, that previously uneconomic areas and resources will graduate to the economically exploitable category. 48 refs., 96 figs., 18 tabs.
Date: October 1, 1995
Partner: UNT Libraries Government Documents Department

CleanFleet. Final report: Volume 7, vehicle emissions

Description: Measurements of exhaust and evaporative emissions from Clean Fleet vans running on M-85, compressed natural gas (CNG), California Phase 2 reformulated gasoline (RFG), propane gas, and a control gasoline (RF-A) are presented. Three vans from each combination of vehicle manufacturer and fuel were tested at the California Air Resources Board (ARB) as they accumulated mileage in the demonstration. Data are presented on regulated emissions, ozone precursors, air toxics, and greenhouse gases. The emissions tests provide information on in-use emissions. That is, the vans were taken directly from daily commercial service and tested at the ARB. The differences in alternative fuel technology provide the basis for a range of technology options. The emissions data reflect these differences, with classes of vehicle/fuels producing either more or less emissions for various compounds relative to the control gasoline.
Date: December 1, 1995
Partner: UNT Libraries Government Documents Department

CRADA opportunities in pressurized combustion research

Description: The Morgantown Energy Technology Center recently began operation of a Low Emissions Combustor Test and Research (LECTR) Facility. This facility was built to support the development of Advanced Gas Turbine Systems (ATS) by providing test facilities and engineering support to METC customers through the ATS University-Industry Consortiu and through CRADA participation with industrial partners. The LECTR is a versatile test facility with capabilities for evaluating a variety of low emissions combustion concepts at temperatures and pressures representative of gas turbine applications. The LECTR was constructed as a mid-scale test platform to support DOE`s ATS program and utilizes the full range of high pressure (up to 30 atm) high temperature (1000{degrees}F air preheat, 3300{degrees}F combustor wall), and mass flows (3.5 lb/s combustion air) available in METC`s Advanced Combustion Facility. The LECTR is now operational and has most recently been employed to characterize the operating and emissions characteristics of an industrical-scale, lean premixed gas burner at elevated pressures for potential gas turbine applications.
Date: December 31, 1995
Creator: Maloney, D.J.; Norton, T.S. & Casleton, K.H.
Partner: UNT Libraries Government Documents Department

Pricing local distribution services in a competitive market

Description: Unbundling and restructuring of local distribution services is the focus of the natural gas industry. As a result of regulatory reforms, a competitive local distribution market has emerged, and the validity of traditional cost-based regulation is being questioned. One alternative is to completely unbundle local distribution services and transform the local distribution company into a common carrier for intrastate transportation services. Three kinds of alternative pricing mechanisms are examined. For firm intrastate transportation services, cost-based pricing is the preferred method unless it can be shown that a competitive secondary market can be established and maintained. Pricing interruptible transportation capacity is discussed.
Date: December 1, 1995
Creator: Duann, D.J.
Partner: UNT Libraries Government Documents Department

Buildings and energy in the 1980`s

Description: Many energy programs were put into place during the 1970`s and 1980`s to lessen the dependence upon foreign oil supplies and to improve how all forms of energy are used. A significant percent of total energy consumption occurred in the residential and commercial sectors. This report concentrates on the physical makeup of the residential and commercial buildings sectors and their use of energy, and examines changes that occurred during the 1980`s. Chapter 1 presents a summary of major findings. The following three chapters focus on different aspects of the overarching theme of buildings and energy in the 1980`s. Chapter 2 discusses major characteristics of residential and commercial buildings. Chapter 3 considers the major energy sources and end uses in terms of number of buildings and floorspace. Chapter 4 focuses on energy consumption and expenditures. Chapters 2, 3, and 4 contain tables at the end of each chapter that summarize data from detailed tables that are available separately on diskette or via EIA`s Electronic Publishing System (EPUB). Following the body of the report, appendices and a glossary provide additional information on the methodologies used in this report and on the residential and commercial building consumption surveys on which this report is based. 62 figs., 30 tabs.
Date: June 1, 1995
Partner: UNT Libraries Government Documents Department

New Technology for America`s Electric Power Industry. Emissions reduction in gas turbines

Description: Argonne National Laboratory is examining alternatives to straight natural gas firing. Research has shown that the addition of certain catalytic agents, such as in hydrogen co-firing, shows promise. When hydrogen co-firing is used in tandem with steam injection, a decrease in both CO and NO{sub x} emissions has been observed. In-process hydrogen production and premixing with the natural gas fuel are also being explored.
Date: April 1, 1995
Partner: UNT Libraries Government Documents Department

Characterization of the LGFSTF wind tunnel in preparation for the DOE/EPA hazardous chemical evaporation rate experiments

Description: The Environmental Protection Agency and the Department of Energy are conducting chemical evaporation rate experiments in the DOE`s Liquefied Gaseous Fuels Spill Test Facility (LGFSTF) wind tunnel to determine the effect on evaporation rate of pool temperature and wind speed. Evaporation rates measured in these tests will be used to verify mathematical models used to define the source (gas) rate inputs to dispersion models. In preparation for the experiments the LGFSTF tunnel has been modified to provide for the simulation of an atmospheric boundary layer flow on the tunnel floor. This report describes work performed by the DOE Modeling Support Center at the University of Arkansas to define (characterize) the turbulence properties in the boundary layer of the (modified) wind tunnel test section. Hot wire anemometry measurements were made to characterize the boundary layer flow over the evaporation test pan. Mean velocity and turbulence statistics were measured along a verticle line (extending from 0.5 cm to 60 cm above the tunnel floor) located on the tunnel centerline immediately upwind of the evaporation pan. The x-direction mean velocity data were analyzed to estimate the applicable values of the surface roughness and friction velocity for four tunnel (variable frequency controller) speed settings: 15 Hz, 30 Hz, 45 Hz, and 60 Hz.
Date: March 1, 1995
Creator: Havens, J.; Walker, H. & Spicer, T.
Partner: UNT Libraries Government Documents Department

Application of new and novel fracture stimulation technologies to enhance the deliverability of gas storage wells

Description: Based on the information presented in this report, our conclusions regarding the potential for new and novel fracture stimulation technologies to enhance the deliverability of gas storage wells are as follows: New and improved gas storage well revitalization methods have the potential to save industry on the order of $20-25 million per year by mitigating deliverability decline and reducing the need for costly infill wells Fracturing technologies have the potential to fill this role, however operators have historically been reluctant to utilize this approach due to concerns with reservoir seal integrity. With advanced treatment design tools and methods, however, this risk can be minimized. Of the three major fracturing classifications, namely hydraulic, pulse and explosive, two are believed to hold potential to gas storage applications (hydraulic and pulse). Five particular fracturing technologies, namely tip-screenout fracturing, fracturing with liquid carbon dioxide, and fracturing with gaseous nitrogen, which are each hydraulic methods, and propellant and nitrogen pulse fracturing, which are both pulse methods, are believed to hold potential for gas storage applications and will possibly be tested as part of this project. Field evidence suggests that, while traditional well remediation methods such as blowing/washing, mechanical cleaning, etc. do improve well deliverability, wells are still left damaged afterwards, suggesting that considerable room for further deliverability enhancement exists. Limited recent trials of hydraulic fracturing imply that this approach does in fact provide superior deliverability results, but further RD&D work is needed to fully evaluate and demonstrate the benefits and safe application of this as well as other fracture stimulation technologies.
Date: April 1, 1995
Partner: UNT Libraries Government Documents Department

Investigation of remotely-sensed geobotanical and structural methods for hydrocarbon exploration in west-central West Virginia. Quarterly report, August--October 1995

Description: Accomplishments are presented for the following tasks: satellite image acquisition and rectification; spectral reflectance measurements; Equitrans storage reservoir data synthesis; and equipment purchase. Under the first task, two USGS EROS Data Center images have been purchased. The new scenes were not cloud-free, but were still very useful. The April 10 image was collected just prior to leaf-out in the spring, and the September 20 image just prior to fall leaf change. This was a bit disappointing, as it was hoped that the fall image might show some early sign of senescence that would be useful for vegetation discrimination. However, unexpectedly, there appears to ba spectral anomaly that is found both over the Volcano field and Equitrans Lewis County Storage Reservoir. The anomaly which is not present in the visible bands, is a significant increase in TM band 4 (0.76-0.90 {mu}m, near infrared), and to a lesser extent in TM band 5 (1.55-1.75 {mu}m, min infrared) over the reservoirs. Although it is too early to confirm that this is a geobotanical anomaly, this is a very encouraging sign. Furthermore, it points to the value of a multi-temporal collection of imagery. The Landsat Thematic Mapper overflew West Virginia on October 18 1995. Unfortunately there is apparently some cloud in this image. EOSAT had some problem in recovering this scene, but it has been corrected, and the scene is being purchased. Coincident with October 18 overpass, spectral reflectance data were collected in the field. Spectra were measure of leaves of selected trees. In addition, spectra were collected of spectrally flat objects such as asphalt parking lot and gravel parking lot, for use in normalization of the images.
Date: October 1, 1995
Partner: UNT Libraries Government Documents Department

Integrated analysis of production potential and profitability of a horizontal well in the Lower Glen Rose Formation, Maverick County, Texas

Description: The U.S. Department of Energy/Morgantown Energy Technology Center (DOE/METC) awarded a contract in 1991 to Prime Energy Corporation (PEC) to demonstrate the benefit of using horizontal wells to recover gas from low permeability formations. The project area was located in the Chittim field of Maverick County, Texas. The Lower Glen Rose Formation in the Chittim field was a promising horizontal well candidate based on the heterogenous nature of the reservoir (suggested by large well-to-well variances in reserves) and the low percentage of economical vertical wells. Since there was substantial evidence of reservoir heterogeneity, it was unknown whether the selected, wellsite would penetrate a reservoir with the desired properties for a horizontal well. Thus, an integrated team was formed to combine geologic analysis, seismic interpretation, reservoir engineering, reservoir simulation, and economic assessment to analyze the production potential and profitability of completing a horizontal well in the Lower Glen Rose formation.
Date: March 1, 1995
Creator: Ammer, J.R.; Mroz, T.H.; Zammerilli, A.M.; Yost, A.B. II; Muncey, J.G. & Hegeman, P.S.
Partner: UNT Libraries Government Documents Department

Geotechnology for low-permeability gas reservoirs, 1995

Description: The permeability, and thus the economics, of tight reservoirs are largely dependent on natural fractures, and on the in situ stresses that both originated fractures and control subsequent fracture permeability. Natural fracture permeability ultimately determines the gas (or oil) producibility from the rock matrix. Therefore, it is desirable to be able to predict, both prior to drilling and during reservoir production, (1) the natural fracture characteristics, (2) the mechanical and transport properties of fractures and the surrounding rock matrix, and (3) the present in situ stress magnitudes and orientations. The combination of activities described in this report extends the earlier work to other Rocky Mountain gas reservoirs. Additionally, it extends the fracture characterizations to attempts of crosswell geophysical fracture detection using shear wave birefringence and to obtaining detailed quantitative models of natural fracture systems for use in improved numerical reservoir simulations. Finally, the project continues collaborative efforts to evaluate and advance cost-effective methods for in situ stress measurements on core.
Date: June 1, 1995
Creator: Brown, S.; Harstad, H.; Lorenz, J.; Warpinski, N.; Boneau, T.; Holcomb, D. et al.
Partner: UNT Libraries Government Documents Department

Estimating Potential Stranded Commitments for U.S. Investor-Owned Electric Utilities

Description: New technologies, low natural gas prices, and federal and state utility regulations are restructuring the electricity industry. Yesterday's vertically integrated utility with a retail monopoly franchise may be a very different organization in a few years. Conferences, regulatory-commission hearings, and other industry fora are dominated by debates over the extent and form of utility deintegration, wholesale competition, and retail wheeling. A key obstacle to restructuring the electricity industry is stranded commitments. Past investments, power-purchase contracts, and public-policy-driven programs that made sense in an era of cost-of-service regulation may not be cost-effective in a competitive power market. Regulators, utilities, and other parties face tough decisions concerning the mitigation and allocation of these stranded commitments. We developed and applied a simple method to calculate the amount of stranded commitments facing U.S. investor-owned electric utilities. The results obtained with this method depend strongly on a few key assumptions: (1) the fraction of utility sales that is at risk with respect to competition, (2) the market price of electric generation, and (3) the number of years during which the utility would lose money because of differences between its embedded cost of production and the market price.
Date: January 1, 1995
Creator: Baxter, L.
Partner: UNT Libraries Government Documents Department

Enhancing the use of coals by gas reburning-sorbent injection. Quarterly report No. 30, January 1--March 31, 1995

Description: The objective of this project is to evaluate and demonstrate a cost effective emission control technology for acid rain precursors, oxides of nitrogen (NO{sub x} and sulfur (SO{sub x}), on two coal fired utility boilers in Illinois. The specific objectives are to demonstrate reductions of 60 percent in NO{sub x} and 50 percent in SO{sub x} emissions, by a combination of two developed technologies, gas reburning (GR) and sorbent injection (SI). With GR, about 80--85 percent of the coal fuel is fired in the primary combustion zone. The balance of the fuel is added downstream as natural gas to create a slightly fuel rich environment in which NO{sub x} is converted to N{sub 2.} The combustion process is completed by overfire air addition. SO{sub x} emissions are reduced by injecting dry sorbents (usually calcium based) into the upper furnace. The sorbents trap SO{sub x} as solid sulfates that are collected in the particulate control device. This project is conducted in three phases at each site: (1) Design and Permitting, (2) Construction and Startup, and (3) Operation, Data Collection, Reporting and Disposition. Technology transfer to industry is accomplished through the formation of an industry panel. Phase I of the project commenced on June 5, 1987. Phases I, II and III for the Illinois Power Project have been completed; Phases I and II for the CWLP project have been completed; Phase III is in progress. All site activities have been completed with the exception of restoration at CWLP.
Date: May 16, 1995
Partner: UNT Libraries Government Documents Department

Fossil fuel conversion -- Measurement and modeling

Description: The main objective of this program is to understand the chemical and physical mechanisms in coal conversion processes and incorporate this knowledge in computer-aided reactor engineering technology for the purposes of development, evaluation, design, scale up, simulation, control and feedstock evaluation in advanced coal conversion devices. To accomplish this objective, this program will: (1) provide critical data on the physical and chemical processes in fossil fuel gasifier and combustors; (2) further develop a set of comprehensive codes; and (3) apply these codes to model various types of combustors and gasifier (fixed-bed, transport reactor, and fluidized-bed for coal and gas turbines for natural gas). Results are presented on the devolatilization of large coal particles; transport reactor modeling; fluidized bed model; nitrogen evolution from small and large coal particles; modeling of hydrogen cyanide and ammonia release during coal pyrolysis; oxidation rates for large coal particles at high pressures; advanced fixed-bed model development and evaluation; application of ACERC combustion and gasification codes to AFR diagnostic capabilities to systems of interest to METC; and submodel for lean premixed combustion of natural gas in industrial gas turbines.
Date: November 1, 1995
Creator: Solomon, P.R.; Smoot, L.D.; Serio, M.A.; Hamblen, D.G.; Brewster, B.S. & Radulovic, P.T.
Partner: UNT Libraries Government Documents Department

Performance and economic evaluation of the seahorse natural gas hot water heater conversion at Fort Stewart. Final report

Description: The Federal government is the largest single energy consumer in the United States with consumption of nearly 1.5 quads/year of energy (10{sup 15} quad = 1015 Btu) and cost valued at nearly $10 billion annually. The US Department of Energy`s (DOE) Federal Energy Management Program (FEMP) supports efforts to reduce energy use and associated expenses in the Federal sector. One such effort, the New Technology Demonstration Program (NTDP) seeks to evaluate new energy -- saving US technologies and secure their more timely adoption by the US government. Pacific Northwest Laboratory (PNL) is one of four DOE laboratories that participate in the New Technologies Demonstration Program, providing technical expertise and equipment to evaluate new, energy-saving technologies being studied under that program. This report provides the results of a field evaluation that PNL conducted for DOE/FEMP with funding support from the US Department of Defense (DoD) Strategic Environmental Research and Development Program (SERDP) to examine the performance of 4 candidate energy-saving technology-a water heater conversion system to convert electrically powered water heaters to natural gas fuel. The unit was installed at a single residence at Fort Stewart, a US Army base in Georgia, and the performance was monitored under the NTDP. Participating in this effort under a Cooperative Research and Development Agreement (CRADA) were Gas Fired Products, developers of the technology; the Public Service Company of North Carolina; Atlanta Gas Light Company; the Army Corps of Engineers; Fort Stewart; and Pacific Northwest Laboratory.
Date: December 1, 1995
Creator: Winiarski, D.W.
Partner: UNT Libraries Government Documents Department

Natural gas annual 1994: Volume 2

Description: The Natural Gas Annual provides information on the supply and disposition of natural gas to a wide audience including industry, consumers, Federal and State agencies, and educational institutions. This report, Volume 2, presents historical data fro the Nation from 1930 to 1994, and by State from 1967 to 1994.
Date: November 1, 1995
Partner: UNT Libraries Government Documents Department

Rayleigh/Raman/LIF measurements in a turbulent lean premixed combustor

Description: Much of the industrial electrical generation capability being added worldwide is gas-turbine engine based and is fueled by natural gas. These gas-turbine engines use lean premixed (LP) combustion to meet the strict NO{sub x} emission standards, while maintaining acceptable levels of CO. In conventional, diffusion flame gas turbine combustors, large amount of NO{sub x} forms in the hot stoichiometric zones via the Zeldovich (thermal) mechanism. Hence, lean premixed combustors are rapidly becoming the norm, since they are specifically designed to avoid these hot stoichiometric zones and the associated thermal NO{sub x}. However, considerable research and development are still required to reduce the NO{sub x} levels (25-40 ppmvd adjusted to 15% O{sub 2} with the current technology), to the projected goal of under 10 ppmvd by the turn of the century. Achieving this objective would require extensive experiments in LP natural gas (or CH{sub 4}) flames for understanding the combustion phenomena underlying the formation of the exhaust pollutants. Although LP combustion is an effective way to control NO{sub x}, the downside is that it increases the CO emissions. The formation and destruction of the pollutants (NO{sub x} and CO) are strongly affected by the fluid mechanics, the finite-rate chemistry, and their (turbulence-chemistry) interactions. Hence, a thorough understanding of these interactions is vital for controlling and reducing the pollutant emissions. The present research is contributing to this goal by providing a detailed nonintrusive laser based data set with good spatial and temporal resolutions of the pollutants (NO and CO) along with the major species, temperature, and OH. The measurements reported in this work, along with the existing velocity data on a turbulent LP combustor burning CH{sub 4}, would provide insight into the turbulence-chemistry interactions and their effect on pollutant formation.
Date: December 31, 1995
Creator: Nandula, S.P.; Pitz, R.W.; Barlow, R.S. & Fiechtner, G.J.
Partner: UNT Libraries Government Documents Department

A reduced mechanism for low-heating-value gas combustion in a perfectly stirred reactor

Description: We have begun an effort to accurately model NO{sub x} formation from the combustion of coal-derived fuels in turbine combustors. Both turbulent mixing and the chemical kinetics of ammonia oxidation are expected to have important influences upon NO{sub x} formation rates. This paper concentrates upon the development of a model for the kinetics. Previous empirical, kinetic mechanisms have inaccurately assumed equilibrium OH concentrations and ignored the chemistry of HCN, an important intermediate. We have developed a reduced mechanism by applying simplifying assumptions to a full, detailed mechanism for methane combustion with nitrogen chemistry. The mechanism contains 7 rates for 10 non-steady-state species, a single partial equilibrium assumption, and steady-state relations for 18 species. The Zeldovich and Fenimore mechanisms of NO formation are modeled, as is the NO recycle mechanism by which NO is converted to HCN. Nitric oxide formation from N{sub 2}O is also included. Two oxidation routes for NH{sub 3} are included: the first describes NH{sub 3} conversion to N, and then to NO; the second describes HNO formation, and final conversion of HNO to NO. Stirred reactor calculations were performed for three cases: (1) methane-air combustion with no nitrogenated species in the reactants, (2) methane-air combustion with 1000 ppmV NO in the reactants, and (3) methane-air combustion with 1000 ppmV NH{sub 3} in the reactants. The reactor temperature (1300 to 2000 K) and residence time (10{sup -4} to 10 {sup -1} s) were varied. Both the reduced and skeletal mechanism calculations agree very well with calculations using the detailed mechanism of Miller and Bowman, except for fuel-rich combustion at low temperatures (less than 1500 K), where results from the skeletal mechanism begin to deviate due to neglect of C{sub 2} chemistry.
Date: December 31, 1995
Creator: Marlow, D. & Norton, T.S.
Partner: UNT Libraries Government Documents Department

Premixed burner experiments: Geometry, mixing, and flame structure issues

Description: This research program is exploring techniques for improved fuel-air mixing, with the aim of achieving combustor operations up to stoichiometric conditions with minimal NO{sub x} and maximum efficiency. The experimental studies involve the use of a double-concentric natural gas burner that is operable in either premixed or non-premixed modes, and the system allows systematic variation of equivalence ratio, swirl strength shear length region and flow momentum in each annulus. Flame structures formed with various combinations of swirl strengths, flow throughput and equivalence ratios in premixed mode show the significant impact of swirl flow distribution on flame structure emanating from the mixedness. This impact on flame structure is expected to have a pronounced effect on the heat release rate and the emission of NO{sub x}. Thus, swirler design and configuration remains a key factor in the quest for completely optimized combustion. Parallel numerical studies of the flow and combustion phenomena were carried out, using the RSM and the k-E turbulence models. These results have not only indicated the strengths and limitations of CFD in performance and pollutants emission predictions, but have provided guidelines on the size and strength of the recirculation produced and the spatio-temporal structure of the combustion flowfield. The first stage of parametric studies on geometry and operational parameters at Morgan State University have culminated in the completion of a one-dimensional flow code that is integrated with a solid, virtual model of the existing premixed burner. This coupling will provide the unique opportunity to study the impact of geometry on the flowfield and vice-versa, with particular emphasis on concurrent design optimization.
Date: December 31, 1995
Creator: Gupta, A.K.; Lewis, M.J.; Gupta, M.; Oni, A.A. & Brown, Q.
Partner: UNT Libraries Government Documents Department