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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

Pulsed atmospheric fluidized-bed combustion. Quarterly report, October--December 1994

Description: Minor changes were made in the steam/water pressure pipe routing from and to boiler shell, to accommodate the bed module orientation change. The ash silo pad elevation was lowered to match the nearest access road level. Grounding system drawing was revised. Foundation work was completed December 31, 1994.
Date: January 1, 1995
Partner: UNT Libraries Government Documents Department

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

DISPOSAL OF FLUIDIZED BED COMBUSTION ASH IN AN UNDERGROUND MINE TO CONTROL ACID MINE DRAINAGE AND SUBSIDENCE

Description: This project will evaluate the technical, economic and environmental feasibility of filling abandoned underground mine voids with alkaline, advanced coal combustion wastes (Fluidized Bed Combustion-FBC ash). Success will be measured in terms of technical feasibility of the approach (i.e. % void filling), cost, environmental benefits (acid mine drainage and subsidence control) and environmental impacts (noxious ion release). This document reports on progress made during Phase III. The report is divided into three major sections. The first deals with the Hydraulic Injection component. This section of the report describes the progress and milestones associated with the grouting activities of the project. The Phase III tasks of Economic Analysis and Regulatory Analysis is covered under this section. The second component is Pneumatic Injection. This section reports on progress made towards completing the demonstration project. The last component involves evaluating the migration of contaminants through the grouted mine. A computer model has been developed in earlier phases and will model the flow of water in and around the grouted Longridge mine.
Date: April 1, 1999
Partner: UNT Libraries Government Documents Department

DISPOSAL OF FLUIDIZED BED COMBUSTION ASH IN AN UNDERGROUND MINE TO CONTROL ACID MINE DRAINAGE AND SUBSIDENCE

Description: This project will evaluate the technical, economic and environmental feasibility of filling abandoned underground mine voids with alkaline, advanced coal combustion wastes (Fluidized Bed Combustion-FBC ash). Success will be measured in terms of technical feasibility of the approach (i.e. % void filling), cost, environmental benefits (acid mine drainage and subsidence control) and environmental impacts (noxious ion release). This document reports on progress made during Phase III. The report is divided into three major sections. The first deals with the Hydraulic Injection component. This section of the report describes the progress and milestones associated with the grouting activities of the project. The Phase III tasks of Economic Analysis and Regulatory Analysis is covered under this section. The second component is Pneumatic Injection. This section reports on progress made towards completing the demonstration project. The last component involves evaluating the migration of contaminants through the grouted mine. A computer model has been developed in earlier phases and will model the flow of water in and around the grouted Longridge mine.
Date: April 1, 2000
Partner: UNT Libraries Government Documents Department

Particulate hot gas stream cleanup technical issues

Description: The analyses of hot gas stream cleanup particulate samples and descriptions of filter performance studied under this contract were designed to address problems with filter operation that have been linked to characteristics of the collected particulate matter. One objective of this work was to generate an interactive, computerized data bank of the key physical and chemical characteristics of ash and char collected from operating advanced particle filters and to relate these characteristics to the operation and performance of these filters. The interactive data bank summarizes analyses of over 160 ash and char samples from fifteen pressurized fluidized-bed combustion and gasification facilities utilizing high-temperature, high pressure barrier filters.
Date: September 30, 1999
Creator: Pontius, D.H. & Snyder, T.R.
Partner: UNT Libraries Government Documents Department

DISPOSAL OF FLUIDIZED BED COMBUSTION ASH IN AN UNDERGROUND MINE TO CONTROL ACID MINE DRAINAGE AND SUBSIDENCE

Description: This project will evaluate the technical, economic and environmental feasibility of filling abandoned underground mine voids with alkaline, advanced coal combustion wastes (Fluidized Bed Combustion-FBC ash). Success will be measured in terms of technical feasibility of the approach (i.e. % void filling), cost, environmental benefits (acid mine drainage and subsidence control) and environmental impacts (noxious ion release). This document reports on progress made during Phase III. The report is divided into three major sections. The first deals with the Hydraulic Injection component. This section of the report describes the progress and milestones associated with the grouting activities of the project. The Phase III tasks of Economic Analysis and Regulatory Analysis is covered under this section. The second component is Pneumatic Injection. This section reports on progress made towards completing the demonstration project. The last component involves evaluating the migration of contaminants through the grouted mine. A computer model has been developed in earlier phases and will model the flow of water in and around the grouted Longridge mine.
Date: July 1, 1999
Partner: UNT Libraries Government Documents Department

DISPOSAL OF FLUIDIZED BED COMBUSTION ASH IN AN UNDERGROUND MINE TO CONTROL ACID MINE DRAINAGE AND SUBSIDENCE

Description: This project will evaluate the technical, economic and environmental feasibility of filling abandoned underground mine voids with alkaline, advanced coal combustion wastes (Fluidized Bed Combustion-FBC ash). Success will be measured in terms of technical feasibility of the approach (i.e. % void filling), cost, environmental benefits (acid mine drainage and subsidence control) and environmental impacts (noxious ion release). This document reports on progress made during Phase III. The report is divided into three major sections. The first deals with the Hydraulic Injection component. This section of the report describes the progress and milestones associated with the grouting activities of the project. The Phase III tasks of Economic Analysis and Regulatory Analysis is covered under this section. The second component is Pneumatic Injection. This section reports on progress made towards completing the demonstration project. The last component involves evaluating the migration of contaminants through the grouted mine. A computer model has been developed in earlier phases and will model the flow of water in and around the grouted Longridge mine.
Date: January 1, 2000
Partner: UNT Libraries Government Documents Department

Control of trace metal emissions during coal combustion. Technical progress report, October 1, 1995--December 31, 1995

Description: Emissions of toxic trace metals in the form of metal fumes or submicron particulates from a coal-fired combustion source have received greater environmental and regulatory concern over the past years. Current practice of controlling these emissions is to collect them at the cold end of the process by air-pollution control devices such as electrostatic precipitators and baghouses. However, trace metal fumes may not always be effectively collected by these devices because the formed fumes are extremely small. The proposed research is to explore the opportunities for improved control of toxic trace metal emissions at the hot end of the coal combustion process, i.e., in the combustion chamber. The technology proposed is to prevent the metal fumes from forming during the process. Specifically, the technology is to employ suitable sorbents to reduce the amount of metal volatilization during combustion and capture volatized metal vapors. The objectives of this project are to demonstrate the technology and to characterize the metal capture process during coal combustion in a fluidized bed combustor. The following progress has been made during the performance period from Oct. 1, 1995 through Dec. 31, 1995: (1) Additional combustion experiments involving both coal and wood pellets were carried out in the constructed quartz fluidized bed combustor. (2) A new Buck Scientific Model 210VGP Atomic Absorption spectrophotometer equipped with a continuous flow hydride generator especially for arsenic and selenium was installed for the project. (3) A paper, entitled ``Capture of Toxic Metals by Various Sorbents during Fluidized Bed Coal Combustion,`` was presented at the 1995 AIChE Annual Meeting held in Miami, November 13--17, 1995. (4) A manuscript, entitled ``Trace Metal Capture by Various Sorbents during Fluidized Bed Coal Combustion,`` was submitted to the 26th International Symposium on Combustion for presentation and for publication in the symposium proceedings. 1 ref., 3 tabs.
Date: January 1, 1996
Creator: Ho, Thomas C.
Partner: UNT Libraries Government Documents Department

Development and testing of PRD-6 hot gas filters

Description: The overall objective of this program is to develop and commercialize PRD-66 hot gas filters for application in pressurized fluidized bed combustors (PFBC) and Integrated Gas Combined Cycle (IGCC) power generation systems. The work is being carried out in phases with the following specific objectives: Demonstrate acceptable mechanical, chemical, and filtration properties in exposure tests; produce and qualify selected prototype design filter elements in high temperature high pressure (HTHP) simulated PFBC exposure tests; and (Option) generate a manufacturing plan to support commercial scale-up. The project is being carried out in five tasks, two of which have been completed and the third is underway. Task 1 provided the management plan and the necessary NEPA information for the project. In Task 2, the test plan was written. Laboratory work began in Task 3, which consists of three subtasks. In Subtask 3.1, attempts at design improvements of the baseline candle filter were made. Also in Subtask 3.1, mechanical property tests suitable for monitoring progress toward stronger filters, and ultimately for process control, were surveyed. After choosing the best test, mechanical properties of the baseline filter would be obtained.
Date: December 1, 1995
Creator: Chambers, J.A.
Partner: UNT Libraries Government Documents Department

Cold Flow Verification Test Facility

Description: The cold flow verification test facility consists of a 15-foot high, 3-foot diameter, domed vessel made of clear acrylic in two flanged sections. The unit can operate up to pressures of 14 psig. The internals include a 10-foot high jetting fluidized bed, a cylindrical baffle that hangs from the dome, and a rotating grate for control of continuous solids removal. The fluid bed is continuously fed solids (20 to 150 lb/hr) through a central nozzle made up of concentric pipes. It can either be configured as a half or full cylinder of various dimensions. The fluid bed has flow loops for separate air flow control for conveying solids (inner jet, 500 to 100000 scfh) , make-up into the jet (outer jet, 500 to 8000 scfh), spargers in the solids removal annulus (100 to 2000 scfh), and 6 air jets (20 to 200 scfh) on the sloping conical grid. Additional air (500 to 10000 scfh) can be added to the top of the dome and under the rotating grate. The outer vessel, the hanging cylindrical baffles or skirt, and the rotating grate can be used to study issues concerning moving bed reactors. There is ample allowance for access and instrumentation in the outer shell. Furthermore, this facility is available for future Cooperative Research and Development Program Manager Agreements (CRADA) to study issues and problems associated with fluid- and fixed-bed reactors. The design allows testing of different dimensions and geometries.
Date: December 31, 1996
Creator: Shamsi, A. & Shadle, L.J.
Partner: UNT Libraries Government Documents Department

AFBC co-firing of coal and hospital waste. Quarterly progress report, August 1--October 31, 1996

Description: The project objective is to design, construct, install, provide operator training and start-up a circulating fluidized bed combustion system at the Lebanon Pennsylvania Veteran`s Affairs Medical Center. This unit will co-fire coal and hospital waste providing lower cost steam for heating and possibly cooling (absorption chiller) and operation of a steam turbine-generator for limited power generation while providing efficient destruction of both general and infectious hospital waste. The steam generated as follows: (1) Steam = 20,000 lb/hr, (2) Temperature = 353 F (saturated), (3) Pressure = 125 psig, and (4) Steam quality = {approximately}98.5%.
Date: June 1, 1997
Partner: UNT Libraries Government Documents Department

Neural Network Based Montioring and Control of Fluidized Bed.

Description: The goal of this project was to develop chaos analysis and neural network-based modeling techniques and apply them to the pressure-drop data obtained from the Fluid Bed Combustion (FBC) system (a small scale prototype model) located at the Federal Energy Technology Center (FETC)-Morgantown. The second goal was to develop neural network-based chaos control techniques and provide a suggestive prototype for possible real-time application to the FBC system. The experimental pressure data were collected from a cold FBC experimental set-up at the Morgantown Center. We have performed several analysis on these data in order to unveil their dynamical and chaotic characteristics. The phase-space attractors were constructed from the one dimensional time series data, using the time-delay embedding method, for both normal and abnormal conditions. Several identifying parameters were also computed from these attractors such as the correlation dimension, the Kolmogorov entropy, and the Lyapunov exponents. These chaotic attractor parameters can be used to discriminate between the normal and abnormal operating conditions of the FBC system. It was found that, the abnormal data has higher correlation dimension, larger Kolmogorov entropy and larger positive Lyapunov exponents as compared to the normal data. Chaotic system control using neural network based techniques were also investigated and compared to conventional chaotic system control techniques. Both types of chaotic system control techniques were applied to some typical chaotic systems such as the logistic, the Henon, and the Lorenz systems. A prototype model for real-time implementation of these techniques has been suggested to control the FBC system. These models can be implemented for real-time control in a next phase of the project after obtaining further measurements from the experimental model. After testing the control algorithms developed for the FBC model, the next step is to implement them on hardware and link them to the experimental system. In this ...
Date: April 1, 1996
Creator: Bodruzzaman, M. & Essawy, M.A.
Partner: UNT Libraries Government Documents Department

Neural network-based monitoring and control of fluidized bed. Quarterly progress report, October 1, 1995--December 31, 1995

Description: This report summarizes work on chaotic behavior control in FBC systems. An update is given to the chaos control method designed to control the chaotic behavior in an FBC system; this method inludes a fully recurrent neural network called the Dynamic System Imitator (DSI). DSI mimics the behavior of a wide variety of dynamic systems in the real world; it was used for modeling linear, nonlinear and chaotic systems, and is also used for iterative prediction of chaotic system behavior. A general methodology for using the DSI to control a nonlinear system is applied to control the chaotic behavior of the Lorenz System. A plan is also outlined for using this method to the FBC system for predicting and controlling its chaotic behavior. Chaotic pressure data from an experimental FBC system was obtained (from METC) on normal and abnormal mixing. Results of chaos analysis applied to these data are presented. These techniques are used to identify the system behavior at different conditions, estimate system order, construct the system attractor, and locate the chaotic behavior in the pressure-drop time series data. Preliminary analysis show that both normal and abnormal conditions of FBC have chaotic characteristics. Objective is to develop a neuro-chaos controller to preserve the normal operational performance of the system.
Date: December 31, 1995
Creator: Bodruzzaman, M.
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

An Analysis of the High-Temperature Particulate Collection Problem

Description: Particulate agglomeration and separation at high temperatures and pressures are examined, with particular emphasis on the unique features of the direct-cycle application of fluidized-bed combustion. The basic long-range mechanisms of aerosol separation are examined, and the effects of high temperature and high pressure on usable collection techniques are assessed. Primary emphasis is placed on those avenues that are not currently attracting widespread research. The high-temperature, particulate-collection problem is surveyed, together with the peculiar requirements associated with operation of turbines with particulate-bearing gas streams.
Date: October 1977
Creator: Razgaitis, Richard
Partner: UNT Libraries Government Documents Department

Fluidized-Bed Regeneration of Sulfated Dolomite from a Coal-Fired FBC Process by Reductive Decomposition

Description: A fluidized-bed, reductive decomposition process has been developed for regenerating calcium sulfate, a product of fluidized-bed combustion. The effect of process operating variables on the extent of regeneration and on the SO2 levels in the off-gas has been determined, and a process model has been proposed. A process for regenerating spent SO2 sorbents has been developed on a PDU scale. Tymochtee dolomite that had been sulfated during fluidized-bed combustion of coal is regenerated (reductive decomposition of calcium sulfate to calcium oxide and SO2) by the incomplete combustion of either methane or coal in a fluidized-bed reactor.
Date: April 1977
Creator: Montagna, John C.; Vogel, G. J.; Smith, G. W. & Jonke, A. A.
Partner: UNT Libraries Government Documents Department

Decomposition of Calcium Sulfate : a Review of the Literature

Description: One of the important issues related to fluidized bed combustion of fossil fuels is the subsequent handling and/or treatment of the partially sulfated lime material removed from the combustor. One alternative would be to regenerate the sulfated additive to recover the sulfur, which would be stored for use, and lime that would be recycled for reuse in the combustor. It is the purpose of this report to review the development of regeneration technology which has progressed rather slowly as compared with the technology relative to the fluidized bed combustion process. The review covers research efforts specifically directed toward the regeneration of sulfated limestones plus those studies which have been made to investigate the decomposition of naturally occurring minerals of calcium sulfate. The report reviews basic thermodynamic and kinetic studies as well as laboratory, bench, and pilot scale process development studies. No attempt has been made in the review to evaluate the engineering, environmental, or economic merits of regeneration of the various regeneration schemes.
Date: December 1976
Creator: Swift, W. M.; Panek, Allen; Smith, G. W.; Vogel, G. J. & Jonke, A. A.
Partner: UNT Libraries Government Documents Department