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Pressure fluctuations as a diagnostic tool for fluidized beds. Technical progress report, October 1, 1995--December 30, 1995

Description: Experimentation was conducted to determine the nature of bubbling fluidized bed (BFB) pressure fluctuations. The goal of the experiments was to explain the physical phenomena that governs the structure of pressure fluctuations. A study of the effect of the differential pressure tap spacing was conducted. The results confirmed the hypothesis that spatial aliasing can significantly distort expected fluctuation structure. The behavior of bubbling bed fluctuations was compared to previously published theories that predicted the natural frequency of incipiently fluidized beds. A modified theory was derived for fluidized systems which better predicts the observed frequency in shallow fluidized beds. This theory not only predicts the natural frequency of bed oscillations, but also explains the second order system behavior observed in bubbling fluidized bed Bode plots. The effect of bubble coalescence in deep bed acts both to decrease the frequency of bed oscillations and to complicate the observed frequency response with multiple peaks.
Date: January 15, 1996
Creator: Brown, R.C.
Partner: UNT Libraries Government Documents Department

Pressure fluctuations as a diagnostic tool for fluidized beds. Technical progress report, April 1--June 30, 1995

Description: The first phase of experimentation for the comprehensive similitude study on the two laboratory scale cold-model circulating fluidized beds has been completed. This first phase required the acquisition and analysis of pressure fluctuation data from a 2.0 inch diameter pressurized circulating fluidized bed. The second phase required the matching of each of the 20 experiments in a cold-model twice the size of the smaller 2.0 inch circulating fluidized bed model using similitude relations. Problems of excessive electrostatic buildup were encountered in this second phase. To alleviate these problems, the large model had to be redesigned and reconstructed. The focus of the research this past quarter has been devoted to these modifications. Currently, the new sections have been constructed and the modified circulating fluidized bed is in the process of reassembly. Two related projects were undertaken while the large circulating fluidized bed model was being modified. A bubbling bed was constructed such that pressure fluctuation data could be measured in both bubbling and turbulent fluidization regimes. The purpose of such tests was to relate pressure fluctuation structure in the lower sections of the circulating fluidized bed with phenomena observed in bubbling/turbulent regimes. Two probes designed to measure heat transfer coefficients in the large and small circulating fluidized bed models were completed and initially tested under bubbling bed conditions. These tests insured the validity and accuracy of the bed to surface heat transfer coefficient measurement. The two probes were constructed as an additional means of validating similitude relations in circulating fluidized beds in addition to pressure fluctuations.
Date: July 14, 1995
Creator: Brown, R.C.
Partner: UNT Libraries Government Documents Department

Pressure fluctuations as a diagnostic tool for fluidized beds. Technical progress report, July 1, 1995--September 30, 1995

Description: Comprehensive experimentation has been conducted to determine whether circulating fluidized bed (CFB) pressure fluctuations can be used to verify that similitude conditions in circulating fluidized beds have been achieved. Using two geometrically similar CFB models, pressure fluctuations were recorded while the full set of similitude parameters were matched under a broad range of operating conditions. The method of data acquisition and analysis is shown to be very important in order to observe the significant frequency phenomena. Under relatively dilute conditions similar power spectral density and Bode plot profiles are observed in the two geometrically similar beds. The dominant frequency under these dilute conditions is inversely proportional to the characteristic CFB dimension. Under conditions of higher solids loading, an additional lower bed frequency phenomena is observed in the spectrum which may be a function of the depth of the lower dense bed in the CFB. It is evident from the results that under some operating conditions, a single dimensionless frequency is not sufficient to validate the achievement of similitude using pressure fluctuations. The results also suggest that the use of similitude parameters as they are currently defined is limited to dilute operating conditions, prior to the formation of a lower dense CFB.
Date: January 1, 1996
Creator: Brown, R.C.
Partner: UNT Libraries Government Documents Department

Methodology for making environmental as low as reasonably achievable (ALARA) determinations

Description: An overall evaluation concept for use in making differential cost-benefit analyses in environmental as low as reasonably achievable (ALARA) determinations is being implemented by Rockwell Hanford Operations. This evaluation includes consideration of seven categories: (1) capital costs; (2) operating costs; (3) state of the art; (4) safety; (5) accident or upset consequences; (6) reliability, operability, and maintainability; and (7) decommissionability. Appropriate weighting factors for each of these categories are under development so that ALARA determinations can be made by comparing scores of alternative proposals for facility design, operations, and upgrade. This method of evaluation circumvents the traditional basis of a stated monetary sum per person-rem of dose commitment. This alternative was generated by advice from legal counsel who advised against formally pursuing this avenue of approach to ALARA for environmental and occupational dose commitments.
Date: January 1, 1982
Creator: Brown, R.C. & Speer, D.R.
Partner: UNT Libraries Government Documents Department

Pressure fluctuations as a diagnostic tool for fluidized beds. Technical progress report, January 1, 1996--March 31, 1996

Description: Additional pressure fluctuation data was recorded from the ISU power plants two CFB boilers. Absolute pressure fluctuations were measured immediately above the distributor nozzles and near the top of the CFB boilers. The fluctuations measured near the bottom of the bed exhibit a highly oscillatory (0.25-0.3 Hz) phenomena. This {open_quotes}square wave{close_quotes} pressure signal is observed at all times of the day and under different boiler loadings. Steps were taken to insure that abasing was not the cause of the observed pressure dynamics. It is hypothesized that these fluctuations are the result of the coal feed system, and are not related to the CFB hydrodynamics. Pressure fluctuations measured near the top of the bed do not show this dominant periodic behavior attributed to the coal feed system. The Bode plots of pressure fluctuations in this region show a near -40 dB/decade roll-off and a cornering frequency of around 0.07 Hz. This result suggests that the pressure dynamics in industrial scale CFBs may be governed by a wave phenomenon similar to that observed in the laboratory scale circulating fluidized beds. This result cannot be confined until more is known about the boiler control dynamics, and more extensive boiler instrumentation is available.
Date: April 20, 1996
Creator: Brown, R.C.
Partner: UNT Libraries Government Documents Department

Pressure fluctuations as a diagnostic tool for fluidized beds. Technical progress report, April 1--June 30, 1996

Description: The pressure fluctuations in the transition regime between bubbling fluidization and fast fluidization were investigated using system identification techniques. The results show that the voidage waves and surface eruption effects seen in bubbling fluidized beds are also observed in the transition regime fluctuations. In addition, a third frequency phenomenon is observed in the spectrum which is hypothesized to be a surface wave phenomenon analogous to surface waves in water. The validity of previously derived similitude parameters for bubbling fluidized beds (BFB) was investigated using spectral analysis of pressure fluctuations. When BFB similitude parameters are matched in two different beds, the pressure dynamics are similar under most conditions, suggesting that the correct similitude parameters have been defined for BFBs.
Date: July 10, 1996
Creator: Brown, R.C.
Partner: UNT Libraries Government Documents Department

Pressure fluctuations as a diagnostic tool for fluidized beds. [Quarterly] technical progress report, January 1, 1995--March 31, 1995

Description: A series of preliminary experiments were conducted at the Iowa State University power plant circulating fluidized bed boiler (CFB). Pressure fluctuation measurements were recorded from a pressure transducer located immediately above the primary air distributor at the base of the CFB boiler under normal operating conditions. The purpose of these initial experiments was to examine the general pressure fluctuation structure of the fluidized bed boiler in order to assess what further signal processing techniques may be necessary for valid pressure fluctuation analysis and analytical characterization. These initial results show that the CFB boiler pressure fluctuations obtained are highly periodic. Due to the dominance of this periodic component (and its subsequent harmonics), the Bode plots of these pressure fluctuation signals are difficult to interpret. While an overall system roll-off is apparent, neither the overall system order nor the system time constants can be adequately estimated from this initial data. Further data recorded from other locations in the CFB boiler should provide a more complete explanation of the nature of boiler pressure fluctuations. This initial experimentation suggests that a better description of pressure fluctuations could be attained using signal filtering techniques. Numerous experiments were also completed using the 2.0 inch diameter cold-model CFB, completing the first stage of a comprehensive set of similitude experiments. This bed was pressurized, and fluidized with 0.15 and 0.2 mm steel shot. A variety of operating conditions were selected such that similitude parameters could be matched in a 4.0 inch diameter CFB model exactly twice the scale of this small CFB. Currently, the final similitude tests in the small CFB with 0.1 mm steel shot are being performed.
Date: April 10, 1995
Creator: Brown, R.C. & Brue, E.
Partner: UNT Libraries Government Documents Department

Mechanisms of coal-water mixture combustion in fluidized beds

Description: The first quarter of FY 1990 was used to correct problems described in the previous progress report and to initiate a series of experiments on calcination and sulfation of coal-water-limestone mixtures (CWLM) in fluidized beds. Results are discussed and compared to the burning of dry coal in a limestone bed. 10 refs., 5 figs.
Date: January 1, 1989
Creator: Brown, R.C.
Partner: UNT Libraries Government Documents Department

Final Scientific/Technical Report

Description: The overall goal of this project was to establish an education and training program in biobased products at Iowa State University (ISU). In particular, a graduate program in Biorenewable Resources and Technology (BRT) was to be established as a way of offering students advanced study in the use of plant- and crop-based resources in the production of biobased products. The program was to include three fundamental elements: an academic program, a research program, and industrial interactions. The academic program set out to introduce a new graduate major in Biorenewable Resources and Technology. Unlike other schools, which only offer certificates or areas of emphasis in biobased products, Iowa State University offers both M.S. and Ph.D degrees through its graduate program. Core required courses in Biorenewable Resources and Technology include a foundation course entitled Fundamentals of Biorenewable Resources (BRT 501); a seminar course entitled Biobased Products Seminar (BRT 506); a laboratory course, and a special topics laboratory course. The foundation course is a three-credit course introducing students to basic concepts in biorenewable resources and technology. The seminar course provides students with an opportunity to hear from nationally and internationally recognized leaders in the field. The laboratory requirement is a 1-credit laboratory course or a special topics laboratory/research experience (BRT 591L). As part of student recruitment, quarter-time assistantships from DOE funds were offered to supplement assistantships provided by faculty to students. Research was built around platform teams in an effort to encourage interdisciplinary research and collaborative student learning in biorenewable resources. A platform is defined as the convergence of enabling technologies into a highly integrated system for transforming a specific feedstock into desired products. The platform teams parallel the way industry conducts research and product development. Platform teams organize faculty and students for cross-disciplinary, systems-oriented research and collaborative learning. To date, nine platforms ...
Date: May 4, 2006
Creator: Brown, R. C. & McCarley, T. M.
Partner: UNT Libraries Government Documents Department

Bed material agglomeration during fluidized bed combustion. Final report

Description: The purpose of this project is to determine the physical and chemical reactions which lead to the undesired agglomeration of bed material during fluidized bed combustion of coal and to relate these reactions to specific causes. A survey of agglomeration and deposit formation in industrial fluidized bed combustors (FBCs) indicate that at least five boilers were experiencing some form of bed material agglomeration. Deposit formation was reported at nine sites with deposits most commonly at coal feed locations and in cyclones. Other deposit locations included side walls and return loops. Three general types of mineralogic reactions were observed to occur in the agglomerates and deposits. Although alkalies may play a role with some {open_quotes}high alkali{close_quotes} lignites, we found agglomeration was initiated due to fluxing reactions between iron (II) from pyrites and aluminosilicates from clays. This is indicated by the high amounts of iron, silica, and alumina in the agglomerates and the mineralogy of the agglomerates. Agglomeration likely originated in the dense phase of the FBC bed within the volatile plume which forms when coal is introduced to the boiler. Secondary mineral reactions appear to occur after the agglomerates have formed and tend to strengthen the agglomerates. When calcium is present in high amounts, most of the minerals in the resulting deposits are in the melilite group (gehlenite, melilite, and akermanite) and pyroxene group (diopside and augite). During these solid-phase reactions, the temperature of formation of the melilite minerals can be lowered by a reduction of the partial pressure of CO{sub 2} (Diopside + Calcite {r_arrow}Akermanite).
Date: January 1, 1996
Creator: Brown, R.C.; Dawson, M.R. & Smeenk, J.L.
Partner: UNT Libraries Government Documents Department

Experience with atmospheric fluidized bed gasification of switchgrass

Description: Switchgrass was gasified in a bubbling fluidized bed reactor rated at 800 kW (2.75 MMBtu/hr) thermal input and operating at atmospheric pressure. A combustible gas with higher heating value varying between 4.2--5.9 MJ/Nm{sup 3} (114--160 Btu/scf) was produced. Carbon conversion was approximately 85%. Difficulties in feeding high moisture switchgrass inhibited smooth reactor operation. Several feed systems for switchgrass were tried with varying degrees of success. The results of gasification trials using switchgrass as fuel are described.
Date: December 31, 1998
Creator: Smeenk, J. & Brown, R.C.
Partner: UNT Libraries Government Documents Department

Pressure fluctuations as a diagnostic tool for fluidized beds. Technical progress report, July 1, 1996--September 30, 1996

Description: By studying pressure fluctuations using a system identification approach, it is hypothesized that circulating fluidized bed (CFB) pressure fluctuations are indicative of CFB hydrodynamics in two ways. First, the frequency phenomenon that is observed in the lower regions of the CFB under conditions of high solids loading is the result of lower dense bed voidage oscillations. Our results suggest that a surface wave phenomena inversely proportional to the square root of the bed diameter is also be observed in CFB pressure fluctuations under most conditions. By matching revised similitude parameters between two CFBs a number of conclusions can be drawn. First, spectral analysis of pressure fluctuations, if properly applied, can be used to verify that similitude has been achieved. To do this, not only must the Bode plot characteristics important for hydrodynamics be identified, but the pressure fluctuation structure at all elevations of the CFB must be similar. The set of similitude parameters defined by Glicksman is not sufficient to establish hydrodynamic similitude. The solids flux as typically measured in the downcomer does not contain information on the solids hold-up in the riser, or the amount of solids that progress downwards in the annulus rather than exit the riser. It is better to use the total mass contained in the riser as the important ``solids`` parameter for the establishment of similitude, rather than the solids flux. This measurement can be made more accurately, monitored continuously, and is a much simpler measurement to perform in most CFB systems. Even with this new set of dimensionless parameters, the differences in the coefficient of restitution of particle/bed collisions may make a significant difference in the CFB hydrodynamics. The effects of particle collisions with the riser top-plate must be considered in similitude studies.
Date: October 10, 1996
Creator: Brown, R.C. & Brue, E.
Partner: UNT Libraries Government Documents Department

Pressure Fluctuations as a Disgnostic Tool for Fluidized Beds.

Description: The validity of using bubbling fluidized bed (BFB) similitude parameters to match a hot BFB to a cold BFB is being studied. Sand in a BFB combustor and copper powder in cold BFB model have been analyzed and found to be out of similitude. In the analysis process, it was determined that the condition of the screen covering the pressure tap affects the quality of pressure data recorded. In addition, distributor plate design and condition will affect the hydrodynamics of the bed. Additional tests are planned to evaluate the validity of similitude concepts in BFB.
Date: October 28, 1997
Creator: Brown, R. C. & Schroeder, J. R.
Partner: UNT Libraries Government Documents Department

Investigation of an integrated switchgrass gasification/fuel cell power plant. Final report for Phase 1 of the Chariton Valley Biomass Power Project

Description: The Chariton Valley Biomass Power Project, sponsored by the US Department of Energy Biomass Power Program, has the goal of converting switchgrass grown on marginal farmland in southern Iowa into electric power. Two energy conversion options are under evaluation: co-firing switchgrass with coal in an existing utility boiler and gasification of switchgrass for use in a carbonate fuel cell. This paper describes the second option under investigation. The gasification study includes both experimental testing in a pilot-scale gasifier and computer simulation of carbonate fuel cell performance when operated on gas derived from switchgrass. Options for comprehensive system integration between a carbonate fuel cell and the gasification system are being evaluated. Use of waste heat from the carbonate fuel cell to maximize overall integrated plant efficiency is being examined. Existing fuel cell power plant design elements will be used, as appropriate, in the integration of the gasifier and fuel cell power plant to minimize cost complexity and risk. The gasification experiments are being performed by Iowa State University and the fuel cell evaluations are being performed by Energy Research Corporation.
Date: September 30, 1998
Creator: Brown, R.C.; Smeenk, J. & Steinfeld, G.
Partner: UNT Libraries Government Documents Department

Pressure fluctuations as a diagnostic tool for fluidized beds. Technical progress report, October 1, 1996--December 31, 1996

Description: The viability of matching hydrodynamic conditions in a hot bubbling fluidized bed (BFB) combustor and a cold BFB model are being evaluated. Similitude parameters are being matched in a 20.32 cm diameter BFB combustor and a 5.08 cm diameter cold BFB. In addition, tests are planned to investigate the effect loaded solids above the L-valve have on the flow rate.
Date: January 29, 1997
Creator: Brown, R.C. & Schroeder, J.R.
Partner: UNT Libraries Government Documents Department

Bed material agglomeration during fluidized bed combustion. Technical progress report, April 1, 1995--June 30, 1995

Description: During this quarter, agglomeration tests were conducted in a laboratory-scale fluidized bed combustor using coal and {open_quotes}model{close_quotes} components which allowed controlled amounts of clays and pyrites to be added during the test. These tests permitted a more direct evaluation of the interaction between iron compounds and aluminosilicates. With additional clay and pyrite (under simulated local reducing conditions found at coal feed locations) large agglomerates formed. The agglomerates were many times larger than those formed with a standard coal feed. When only clay was added to the fuel (no additional pyrite), agglomerates formed but they were much smaller and very friable. These tests support the hypothesis that local reducing conditions promote the interaction of iron in a +2 state and aluminosilicate material in the coal which leads to agglomeration during fluidized bed combustion. Also during this quarter, a deposit which formed in a fluidized bed boiler of a Texas-New Mexico Power Company was analyzed to determine the chemical and mineralogic mechanisms responsible for deposit formation. Mineral phases were determined by x-ray diffraction (XRD). Bulk chemical composition was determined by x-ray fluorescence spectroscopy (XRF). Polished sections of the deposit were made for optical and scanning electron microscopy.
Date: July 1, 1995
Creator: Brown, R.C.; Dawson, M.R. & Smeenk, J.L.
Partner: UNT Libraries Government Documents Department

Spectral methods applied to fluidized-bed combustors

Description: The goal of this research is to characterize coals and sorbents during the normal operation of an industrial-scale circulating fluidized bed (CFB) boiler. The method determines coal or sorbent properties based on the analysis of transient CO{sub 2} or SO{sub 2} emissions from the boiler. Fourier Transform Infrared (FTIR) spectroscopy is used to qualitatively and quantitatively analyze the gaseous products of combustion. Spectral analysis applied to the transient response of CO{sub 2} and SO{sub 2} resulting from introduction of a batch of coal or limestone into the boiler yields characteristic time constants from which combustion or sorbent models are developed. The method is non-intrusive and is performed under realistic combustion conditions. Results are presented from laboratory studies and power plant monitoring.
Date: November 1, 1995
Creator: Brown, R.C.; Raines, T.S. & Thiede, T.D.
Partner: UNT Libraries Government Documents Department

Bed material agglomeration during fluidized bed combustion. Technical progress report, January 1, 1995--March 31, 1995

Description: Experiments performed support the hypothesis that a reducing atmosphere during fluidized bed coal combustion contributes to the formation of agglomerates. Reducing conditions are imposed by controlling the amount of combustion air supplied to the combustor, 50% of theoretical in these experiments. These localized reducing conditions may arise from either poor lateral bed mixing or oxygen-starved conditions due to the coal feed locations. Deviations from steady-state operating conditions in bed pressure drop may be used to detect agglomerate formation. Interpretation of the bed pressure drop was made more straightforward by employing a moving average difference method. During steady-state operation, the difference between the moving point averages should be close to zero, within {plus_minus}0.03 inches of water. Instability within the combustor, experienced once agglomerates begin to form, can be recognized as larger deviations from zero, on the magnitude of {plus_minus}0.15 inches of water.
Date: April 1, 1995
Creator: Brown, R.C.; Dawson, M.R. & Smeenk, J.L.
Partner: UNT Libraries Government Documents Department

Bed material agglomeration during fluidized bed combustion

Description: The purpose of this project is to determine the physical and chemical reactions which led to the undesired agglomeration of bed material during fluidized bed combustion and to relate these reactions to specific causes. Survey of industrial-scale fluidized bed combustors is being conducted to determine the occurrence of bed agglomeration and the circumstances under which agglomeration took place. This task should be finished by the end of February. Samples of bed material, agglomerate material, and boiler deposits are being requested from boiler operators as part of the survey. Once received, these sample will be analyzed to determine chemical and mineralogic composition. The bulk chemical determination will be performed using x-ray fluorescence and inductively coupled plasma-optical emission (ICP). Mineralogy will be detected by x-ray diffraction (XRD). Chemical and mineral reactions will be determined by scanning electron microscopy, optical microscopy, and electron microprobe.
Date: February 1, 1993
Creator: Brown, R.C.; Dawson, M.R. & Noble, S.
Partner: UNT Libraries Government Documents Department

Bed material agglomeration during fluidized bed combustion. Technical progress report, October 1, 1993--December 31, 1993

Description: During this quarter, agglomerates which formed in the FBC at Montana-Dakota Utilities (Heskett Station Unit 2 located in Bismarck, ND) were analyzed by x-ray diffraction analyses (XRD) for mineral determination; bulk chemical composition was determined by inductively coupled plasma spectroscopy; and polished sections were made for optical and scanning electron microscopy. Polarized-light microscopy was performed using a Zeiss research microscope. Individual mineral grains were analyzed using an ARL electron microprobe and a JOEL 840 scanning electron microscope. The agglomerate was found in the mechanical dust collector and was about ten centimeters in diameter with a dark-colored core and a greenish rim. The sample had voids up to ten millimeters in size; however, the agglomerate was hard to break apart. Bulk compositionally, the agglomerate consists primarily of calcium, silica, and alumina with relatively high abundances of iron (8 to 9 wt %), magnesium (5 to 9 wt %) and sodium (3 to 4 wt %). It is likely that the ``root`` cause of this agglomerate originated in the dense phase of the FBC bed. Because fluidized bed combustors work below the ash fusion temperature of coal ash, aluminosilicates (clays) in the ash probably became ``sticky`` due to fluxing reactions with pyrite (FeS{sub 2}) and perhaps alkalies (Na). This is indicated by the high amounts of iron, silica, and alumina in the agglomerate. Because of the size of the deposit, the bed particles probably agglomerated in the dust collector.
Date: January 1, 1994
Creator: Brown, R. C.; Dawson, M. R. & Smeenk, J. L.
Partner: UNT Libraries Government Documents Department

Bed material agglomeration during fluidized bed combustion. Technical progress report, September 30, 1992--December 31, 1992

Description: The purpose of this project is to determine the physical and chemical reactions which led to the undesired agglomeration of bed material during fluidized bed combustion and to relate these reactions to specific causes. Survey of industrial-scale fluidized bed combustors is being conducted to determine the occurrence of bed agglomeration and the circumstances under which agglomeration took place. This task should be finished by the end of February. Samples of bed material, agglomerate material, and boiler deposits are being requested from boiler operators as part of the survey. Once received, these sample will be analyzed to determine chemical and mineralogic composition. The bulk chemical determination will be performed using x-ray fluorescence and inductively coupled plasma-optical emission (ICP). Mineralogy will be detected by x-ray diffraction (XRD). Chemical and mineral reactions will be determined by scanning electron microscopy, optical microscopy, and electron microprobe.
Date: February 1, 1993
Creator: Brown, R. C.; Dawson, M. R. & Noble, S.
Partner: UNT Libraries Government Documents Department

Bed material agglomeration during fluidized bed combustion. Technical progress report, 1 July, 1993--30 September, 1993

Description: Agglomerates formed in laboratory coal combustion tests were analyzed to determine the chemical and mineral reactions which lead to the cohesion of bed particles. Combustion tests were conducted at 75, 90, 100, and 120% theoretical air values. The test at 75% theoretical air resulted in the formation of bed agglomerates within 30 minutes. Agglomerates which formed at the lower theoretical air values were compared to unagglomerated bed samples by X-ray diffraction analyses. Polished thin sections of the agglomerates were made for optical and scanning electron microscopy. The results of these analyses indicate there were, in a broad sense, two types of mineralogic reactions which lead to the cohesion of bed particles in the agglomerates. One mechanism of cohesion resulted from the melting of bed particles to form a viscous material which bridged other bed particles. Based on the chemical composition of the glass (which resulted from the melt), this material was probably derived from aluminosilicate minerals in the sand bed or from clays within the coal. Because of the high iron content in these glasses (4 to 5 wt%), it is likely that iron pyrites in the coal were involved in fluxing reactions. In addition, MgO appears to be relatively high in the glasses. It is suspected that Ca-Mg carbonates (dolomite) from the bed sand are also involved in mineralogic reactions with the aluminosilicate melt. The second type of mineralogic reaction appears to be a reaction involving calcium and magnesium with other bed particles and with the aluminosilicate melt to form new mineral phases. Although the composition of these phases is somewhat variable, some resemble single-chain silicates or pyroxenes.
Date: November 1, 1993
Creator: Brown, R. C.; Dawson, M. R. & Noble, S. D.
Partner: UNT Libraries Government Documents Department

Techno-Economic Analysis of Biofuels Production Based on Gasification

Description: This study compares capital and production costs of two biomass-to-liquid production plants based on gasification. The first biorefinery scenario is an oxygen-fed, low-temperature (870?C), non-slagging, fluidized bed gasifier. The second scenario is an oxygen-fed, high-temperature (1,300?C), slagging, entrained flow gasifier. Both are followed by catalytic Fischer-Tropsch synthesis and hydroprocessing to naphtha-range (gasoline blend stock) and distillate-range (diesel blend stock) liquid fractions. Process modeling software (Aspen Plus) is utilized to organize the mass and energy streams and cost estimation software is used to generate equipment costs. Economic analysis is performed to estimate the capital investment and operating costs. Results show that the total capital investment required for nth plant scenarios is $610 million and $500 million for high-temperature and low-temperature scenarios, respectively. Product value (PV) for the high-temperature and low-temperature scenarios is estimated to be $4.30 and $4.80 per gallon of gasoline equivalent (GGE), respectively, based on a feedstock cost of $75 per dry short ton. Sensitivity analysis is also performed on process and economic parameters. This analysis shows that total capital investment and feedstock cost are among the most influential parameters affecting the PV.
Date: November 1, 2010
Creator: Swanson, R. M.; Platon, A.; Satrio, J. A.; Brown, R. C. & Hsu, D. D.
Partner: UNT Libraries Government Documents Department

Techno-Economic Analysis of Biomass Fast Pyrolysis to Transportation Fuels

Description: This study develops techno-economic models for assessment of the conversion of biomass to valuable fuel products via fast pyrolysis and bio-oil upgrading. The upgrading process produces a mixture of naphtha-range (gasoline blend stock) and diesel-range (diesel blend stock) products. This study analyzes the economics of two scenarios: onsite hydrogen production by reforming bio-oil, and hydrogen purchase from an outside source. The study results for an nth plant indicate that petroleum fractions in the naphtha distillation range and in the diesel distillation range are produced from corn stover at a product value of $3.09/gal ($0.82/liter) with onsite hydrogen production or $2.11/gal ($0.56/liter) with hydrogen purchase. These values correspond to a $0.83/gal ($0.21/liter) cost to produce the bio-oil. Based on these nth plant numbers, product value for a pioneer hydrogen-producing plant is about $6.55/gal ($1.73/liter) and for a pioneer hydrogen-purchasing plant is about $3.41/gal ($0.92/liter). Sensitivity analysis identifies fuel yield as a key variable for the hydrogen-production scenario. Biomass cost is important for both scenarios. Changing feedstock cost from $50-$100 per short ton changes the price of fuel in the hydrogen production scenario from $2.57-$3.62/gal ($0.68-$0.96/liter).
Date: November 1, 2010
Creator: Wright, M. M.; Satrio, J. A.; Brown, R. C.; Daugaard, D. E. & Hsu, D. D.
Partner: UNT Libraries Government Documents Department