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Experimental Study on Fluidization of Biomass, Inert Particles, and Biomass/Sand Mixtures

Description: Fluidization of biomass particles is an important process in the gasification, pyrolysis and combustion in order to extract energy from biomass. Studies on the fluidization of biomass particles (corn cob and walnut shell), inert particles (sand, glass bead, and alumina), which are added to facilitate fluidization of biomass, and biomass/sand mixture were performed. Experiments were carried out in a 14.5 cm internal diameter cold flow fluidization bed to determine minimum fluidization velocities with air as fluidizing medium. On the of basis of experimental data from both present work and those found in the literature, new correlations were developed to predict minimum fluidization velocity for inert particles as well as biomass particles. It was found that the proposed correlations satisfactorily predict minimum fluidization velocities and was in well agreement with experimental data. Furthermore, effect of weight percentage of biomass in the biomass/sand mixtures was studied. The weight fraction of biomass particles in the mixture was chosen in the range of 0 ~ 100 wt. %. The results show that minimum fluidization velocity of the mixtures increases with an increase in biomass content. Using the present experimental data, a new correlation was developed in terms of mass ratio for predicting values of minimum fluidization velocity of these mixtures. However, the validity of the proposed correlation should be further studied by conducting more experiments using the biomass/sand mixtures of different particle size, shape, and density.
Date: May 2011
Creator: Paudel, Basu
Partner: UNT Libraries

Development of methods to predict agglomeration and disposition in FBCs

Description: This 3-year, multiclient program is providing the information needed to determine the behavior of inorganic components in FBC units using advanced methods of analysis coupled with bench-scale combustion experiments. The major objectives of the program are as follows: (1) To develop further our advanced ash and deposit characterization techniques to quantify the effects of the liquid-phase components in terms of agglomerate formation and ash deposits, (2) To determine the mechanisms of inorganic transformations that lead to bed agglomeration and ash deposition in FBC systems, and (3) To develop a better means to predict the behavior of inorganic components as a function of coal composition, bed material characteristics, and combustion conditions.
Date: November 1, 1995
Creator: Mann, M.D.; Henderson, A.K.; Swanson, M.K. & Erickson, T.A.
Partner: UNT Libraries Government Documents Department

A Comparative Study of Iron-, Nickel-, and Cobalt-Base Weldments Exposed in TVA 20-MW and Rocketdyne Atmospheric Fluidized Bed Combustors

Description: Experimental iron-, nickel-, and cobalt-base weldment materials were exposed in TVA 20-MW and Rocketdyne atmospheric fluidized bed combustors (AFBCs) at 849 degrees C for 1261 h and 871 degrees C for 1000 h, respectively. Post-exposure analyses were conducted at Argonne National Laboratory. All specimens experienced different degrees of internal oxidation/sulfidation. Among eight filler materials, Marathon 25/35R and Haynes 188 showed the least corrosion attack, i.e., less than 0.5 mm/yr. A high nickel content in the weldment was unfavorable for corrosion resistance in the AFBC environment. Differences in the coal/bed chemistry of the TVA and Rocketdyne systems yielded different corrosion behavior in the materials. Calcium sulfate deposits on the specimens significantly affected the internal oxidation/sulfidation of the alloys. The results of this study supplement the material data base, in particular that of weldment performance, and aid in materials selection for AFBC applications.
Date: June 1990
Creator: Wang, D. Y. & Natesan, K.
Partner: UNT Libraries Government Documents Department

Structural Evolution of Carbon During Oxidation

Description: The examination of the structural evolution of carbon during oxidation has proven to be of scientific interest. Early modeling work of fluidized bed combustion showed that most of the reactions of interest occurs iOn the micropores, and this work has concentrated on these pores. This work has concentrated on evolution of macroporosity and rnicroporosity of carbons during kinetic controlled oxidation using SAXS, C02 and TEM analysis. Simple studies of fluidized bed combustion of coal chars has shown that many of the events considered fragmentation events previously may in fact be "hidden" or nonaccessible porosity. This makes the study of the microporous combustion characteristics of carbon even more important. The generation of a combustion resistant grid, coupled with measurements of the SAXS and C02 surface areas, fractal analysis and TEM studies has confined that soot particles shrink during their oxidation, as previously suspected. However, this shrinkage results in an overall change in structure. This structure becomes, on a radial basis, much more ordered near the edges, while the center itself becomes transparent to the TEM beam, implying a total lack of structure in this region. Although complex, this carbon structure is probably burning as to keep the density of the soot particles nearly the same. The TEM techniques developed for examination of soots has also been applied to Spherocarb. The Spherocarb during oxidation also increases its ordering,. This ordering, by present theories, would imply that the reactivity would go. However, the reactivity goes up, implying that structure of carbon is secondary in importance to catalytic effects.
Date: October 28, 1998
Creator: Sarofim, Adel F. & Kandas, Angelo
Partner: UNT Libraries Government Documents Department

Ultra-Supercritical Pressure CFB Boiler Conceptual Design Study

Description: Electric utility interest in supercritical pressure steam cycles has revived in the United States after waning in the 1980s. Since supercritical cycles yield higher plant efficiencies than subcritical plants along with a proportional reduction in traditional stack gas pollutants and CO{sub 2} release rates, the interest is to pursue even more advanced steam conditions. The advantages of supercritical (SC) and ultra supercritical (USC) pressure steam conditions have been demonstrated in the high gas temperature, high heat flux environment of large pulverized coal-fired (PC) boilers. Interest in circulating fluidized bed (CFB) combustion, as an alternative to PC combustion, has been steadily increasing. Although CFB boilers as large as 300 MWe are now in operation, they are drum type, subcritical pressure units. With their sizes being much smaller than and their combustion temperatures much lower than those of PC boilers (300 MWe versus 1,000 MWe and 1600 F versus 3500 F), a conceptual design study was conducted herein to investigate the technical feasibility and economics of USC CFB boilers. The conceptual study was conducted at 400 MWe and 800 MWe nominal plant sizes with high sulfur Illinois No. 6 coal used as the fuel. The USC CFB plants had higher heating value efficiencies of 40.6 and 41.3 percent respectively and their CFB boilers, which reflect conventional design practices, can be built without the need for an R&D effort. Assuming construction at a generic Ohio River Valley site with union labor, total plant costs in January 2006 dollars were estimated to be $1,551/kW and $1,244/kW with costs of electricity of $52.21/MWhr and $44.08/MWhr, respectively. Based on the above, this study has shown that large USC CFB boilers are feasible and that they can operate with performance and costs that are competitive with comparable USC PC boilers.
Date: June 30, 2006
Creator: Fan, Zhen; Goidich, Steve; Robertson, Archie & Wu, Song
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


Description: The purpose of this report is to present the progress made on the project ''Establishment of an Environmental Control Technology Laboratory with a Circulating Fluidized-Bed Combustion (CFBC) System'' during the quarter January--March 2004. The following tasks have been completed. First, plans for the renovation of space for a new Combustion Laboratory for the CFBC Facility have progressed smoothly. Second, the design calculations, including the mass balances, energy balances, heat transfer, and strength calculations have been completed. Third, considerable modifications have been made on the draft design of the CFBC Facility based on discussions conducted during the project kick-off meeting held on January 13, 2004 at the National Energy Technology Laboratory (NETL). Comments received from various experts were also used to improve the design. Finally, the drawings of all assembly parts have been completed in order to develop specifications for the fabrication of individual parts. At the same time, the proposed work for the next quarter has been outlined in this report.
Date: April 1, 2004
Creator: Pan, Wei-Ping; Liu, Kunlei & Riley, John T.
Partner: UNT Libraries Government Documents Department

Materials Performance in the Atmospheric Fluidized-Bed Cogeneration Air Heater Experiment

Description: The Atmospheric Fluidized-Bed Cogeneration Air Heater Experiment (ACAHE) sponsored by the US Department of Energy (DOE) was initiated to assess the performance of various heat-exchanger materials to be used in fluidized-bed combustion air heater systems. Westinghouse Electric Corporation, through subcontracts with Babcock Wilcox, Foster Wheeler, and ABB Combustion Engineering Systems, prepared specifications and hardware for the ACAHE tests. Argonne National Laboratory contracted with Rockwell International to conduct tests in the DOE atmospheric fluidized-bed combustion facility. This report presents an overview of the project, a description of the facility and the test hardware, the test operating conditions, a summary of the operation, and the results of analyzing specimens from several uncooled and cooled probes exposed in the facility. Extensive microstructural analyses of the base alloys, claddings, coatings, and weldments were performed on specimens exposed in several probes for different lengths of time. Alloy penetration data were determined for several of the materials as a function of specimen orientation and the exposure location in the combustor. Finally, the data were compared with earlier laboratory test data, and the long-term performance of candidate materials for air-heater applications was assessed.
Date: February 1991
Creator: Natesan, K.
Partner: UNT Libraries Government Documents Department

Interpretation of pilot-scale, fluidized bed behavior using chaotic time series analysis

Description: In this paper, we apply conventional and chaotic time series analyses to the interpretation of pressure-drop measurements from a 250 kW, pilot-scale, bubbling fluidized bed combustor. Our results demonstrate that such analyses can be useful for discriminating different types of fluidization in a practical combustor and offer a basis for improving fluidized bed monitoring and control. A new comparative index that reflects the multivariate structure in pressure-drop measurements is proposed for detecting variations in the fluidized state. We also propose standards for acquiring fluidized bed pressure-drop measurements in pilot and commercial-scale facilities as well as three potential commercial uses. Recent findings regarding the effect of pressure tap location and design on the measured signal fidelity are discussed.
Date: June 1, 1993
Creator: Fuller, T. A.; Flynn, T. J.; Daw, C. S. & Halow, J. S.
Partner: UNT Libraries Government Documents Department

Pulsed atmospheric fluidized bed combustion. Quarterly technical progress report, April--June 1993

Description: In this quarter the design of the plant structures was completed 70%. The design philosophy of the structure economizes on the use of steel by providing supports for the hot cyclone and hot gas duct connecting the cyclone to the boiler while fulfilling the needs for platforms and walkways at the various levels necessary for operational access. Figures 1 through 6 indicate the layout of the plant structure. At the same time the structure for the Coarse Coal Silo V-2 and Limestone Silo V-4 were incorporated and completed. Following completion of the piping pressure drop calculations, pipe sizing and layout drawings, detailed drawings of the piping in different views are being prepared. The pulse combustor is used to burn fine coal particles and provide an ignition source and supplementary heat to the fluid bed. The following is a description of the components: air plenum, fine coal injectors, aerovalves, water jacket, and tailpipe inserts.
Date: July 30, 1993
Partner: UNT Libraries Government Documents Department

Pulsed atmospheric fluidized bed combustion. Quarterly technical progress report, October 1992--December 1992

Description: The Design and Engineering of most components in the Pulsed Atmospheric Fluidized Bed System was completed prior to September 1992. The components remaining to be designed at that time were: Aerovalves for the Pulse Combustor; Gas and coal injectors for the Pulse Combustor; Lines for PC tailpipes; Air plenum and inlet silencer; Refractory lined hot gas duct connecting outlet hot cyclone to boiler; Structure and platforms, and ladders around PAFBC vessel access and major equipment. Design work is currently in progress on all of the above components. Items 1, 2, 3 and 4 are 50% completed, and items 5 & 6 are 75% complete.
Date: January 1, 1993
Partner: UNT Libraries Government Documents Department

Pulsed Atmospheric Fluidized Bed Combustion. Technical Progress Report, July 1993--September 1993

Description: This quarterly report is broken down between design and the status of the fabrication work being performed. The design section is divided between the following sections: Site layout, foundation design, structural design, piping design, pulse combustor components, and electrical & instrumentation design. As reported in the last quarterly report the location area of the PAFBC in the Clemson Energy Facility was inspected with a view to finalize the layout of the PAFBC plant. Some adjustments were made to the layout to accommodate Clemson University`s requirements and the available space. The most important changes are that the boiler and economizer were relocated in the structure above ground level in order to reduce the size of the footprint of the plant. Figure 1 is the plan view of the current layout. Figures 2 through 6 present different elevation views of the layout. The design of foundations for the entire plant is currently being executed by Industra Engineers Inc. of Greenville, SC. The different weights of various equipment located close to each other precludes the provision of independent foundations for each piece of equipment. One monolithic foundation platform for the whole area proves to be more economical for the current layout. In this quarter the design of the plant structures was completed. The drawings were sent out for expert review and approval. The drawings at this stage present complete structural and platform layout requirements. Changes will be made to various structural members based on the structural review and then detailed drawings of joint design and fabrication cutting plans will be prepared and issued for fabrication.
Date: October 30, 1993
Partner: UNT Libraries Government Documents Department

Bed material agglomeration during fluidized bed combustion. Technical progress report, January 1, 1994--March 31, 1994

Description: Laboratory combustion tests conducted this quarter support the hypothesis that localized reducing conditions promote formation of agglomerates in the bed of fluidized bed boilers. These tests were designed to simulate localized reducing conditions found in commercial fluidized bed combustors. Localized reducing conditions may occur from either poor lateral bed mixing or oxygen-starved bed conditions due to the coal feed configuration. It was found-that agglomeration can occur at lower theoretical air values while operating temperatures are within the range of fluidized bed boilers. Cohesion of bed particles appears to take place very rapidly when theoretical air in the bed approaches 70%. These tests also indicate that bed temperature, pressure drop, oxygen and carbon dioxide concentrations are affected by agglomeration. Agglomeration appears to result in: (1) An increase in the frequency of pressure fluctuations (bed pressure drop). (2) An increase in the magnitude of pressure fluctuations (bed pressure drop.) (3) A possible decrease in bed pressure differential over time. In addition, there appears to be an increase in the amount of available oxygen and a decrease in CO{sub 2}. Agglomerates formed in the laboratory are being subjected to mineralogical analyses which will then be compared to similar analyses of agglomerates removed from commercial boilers.
Date: April 1, 1994
Creator: Brown, R. C.; Dawson, M. R. & Smeenk, J. L.
Partner: UNT Libraries Government Documents Department

Second-generation pressurized fluidized bed combustion

Description: Under the sponsorship of the United States Department of Energy, Foster Wheeler Corporation is developing second-generation pressurized fluidized bed combustion (PFBC) power plant technology that will enable this type of plant to operate with net plant efficiencies in the range of 43 to 46 percent (based on the higher heating value of the coal), with a reduction in the cost of electricity of at least 20 percent. A three-phase program is under way. Its scope encompasses the conceptual design of a commercial plant through the process of gathering needed experimental test data to obtain design parameters.
Date: May 1, 1992
Creator: Wolowodiuk, W. & Robertson, A.
Partner: UNT Libraries Government Documents Department

DMEC-1 Pressurized Circulating Fluidized-Bed Demonstration Project

Description: The DMEC-1 project will demonstrate the use of Pyropower`s PYROFLOW pressurized circulating fluidized bed technology to repower an existing coal fired generating station. This will be the first commercial application of this technology in the world. The project is now in budget period 1, the preliminary design phase.
Date: December 1, 1992
Creator: Kruempel, G. E.; Ambrose, S. J. & Provol, S. J.
Partner: UNT Libraries Government Documents Department

Pulsed atmospheric fluidized bed combustion. Technical progress report, January--March 1994

Description: Industra has completed design of the structure which surrounds the fluidized bed. Details regarding their efforts are discussed below. Duke/Fluor Daniel has begun overall design review and will provide comments and recommendations early in the second quarter. Foundation and control room design are complete. Drawings have been submitted to Clemson University and bids have been requested from vendors. Structural design is complete and drawings have been submitted for bids. Industra has reviewed design of the bin structures and has provided recommendations for minor additions to them. Revisions have been made to the structure and are described.
Date: April 29, 1994
Partner: UNT Libraries Government Documents Department

Clean Coal II: PFBC Utility Demonstration Project. Annual report, [January 1, 1992--December 31, 1992]

Description: This is the second Annual Report submitted to the Department of Energy (DOE) in connection with the Cooperative Agreement between the DOE and the Appalachian Power Company (APCO) for the Pressurized Fluidized Bed Combustion (PFBC) Utility Demonstration Project. The report covers the period January 1, 1992 to December 31, 1992; during which time, Task 1.1.3 (Value Engineering) was started. Task 1.1.3 as well as continuation of Task 1.1.2 (Project Support) are associated with Budget Period 2 (BP2) of the Cooperative Agreement. BP2 tasks, which extend from January 1992 to January 1996, are aimed at reducing the technical and economic risks of a large commercial PFBC plant. This objective is being met by performing value engineering activities and testing various systems, including a sorbent fines admission system. Installation of this system (at the Tidd PFBC Demonstration Plant) started in December 1992. The sorbent system being installed is for the purpose of a process verification. Hardware costs specific to verification activities are being funded under the PFBC Utility Demonstration Project Cooperative Agreement. Test data is dependent upon operation of the Tidd facility. The present PFBC program identifies the year 2004 for completion of the project at an as-spent total shared cost of approximately $918 million.
Date: December 1, 1992
Partner: UNT Libraries Government Documents Department

TIDD PFBC Demonstration Project: Third quarterly technical progress report 1992, CY 1992

Description: This is the 22nd Technical Progress Report submitted to the Department of Energy in connection with the Cooperative Agreement between the DOE and the Ohio Power Company for the Tidd PFBC Demonstration Plant. This report covers the period from July 1, 1992 to September 30, 1992. The unit was operated for a total of 903 hours (including gas turbine air prewarming). There were 9 gas turbine starts, 11 preheating starts, and 8 operating periods with coal fire. The peak gross output of 59 MWH was achieved for the period of 1600 to 1700 hours on September 23, 1992. The longest coal fire was 422 hourb beginning at 1349 hours on August 9, 1992. Total gross generation was 32,418 MWH, and coal consumption was 15,846 tons. Testing was completed on the gas turbine blade resonance frequency problem. The report showed that a resonant frequency problem existing at high LPT speeds and at a mostly closed guide vane position. An operating curve was developed by ABBC to avoid the points of blade resonance. Monitoring of solid, liquid and gaseous waste streams, as detailed in the operations phase monitoring requirements in the EMP, were performed throughout the quarter.
Date: October 1, 1992
Partner: UNT Libraries Government Documents Department

Commercial second-generation PFBC plant transient model: Task 15

Description: The advanced pressurized fluidized bed combustor (APFBC) power plant combines an efficient gas-fired combined cycle, a low-emission PFB combustor, and a coal pyrolysis unit (carbonizer) that converts coal, America`s most plentiful fuel, into the gas turbine fuel. From an operation standpoint, the APFBC plant is similar to an integrated gasification combined cycle (IGCC) plant, except that the PFBC and fluid bed heat exchanger (FBHE) allow a considerable fraction of coal energy to be shunted around the gas turbine and sent directly to the steam turbine. By contrast, the fuel energy in IGCC plants and most other combined cycles is primarily delivered to the gas turbine and then to the steam turbine. Another characteristic of the APFBC plant is the interaction among three large thermal inertias--carbonizer, PFBC, and FBHE--that presents unique operational challenges for modeling and operation of this type of plant. This report describes the operating characteristics and dynamic responses of the APFBC plant and discusses the advantages and shortcomings of several alternative control strategies for the plant. In particular, interactions between PFBC, FBHE, and steam bottoming cycle are analyzed and the effect of their interactions on plant operation is discussed. The technical approach used in the study is described in Section 2. The dynamic model is introduced in Section 3 and described is detail in the appendices. Steady-state calibration and transient simulations are presented in Sections 4 and 5. The development of the operating philosophy is discussed in Section 6. Potential design changes to the dynamic model and trial control schemes are listed in Sections 7 and 8. Conclusions derived from the study are presented in Section 9.
Date: April 1, 1995
Creator: White, J.S.; Getty, R.T. & Torpey, M.R.
Partner: UNT Libraries Government Documents Department