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Coal Combustion Effect Of Process Conditions On Char Reactivity Quarterly Technical Report October 1 1994 December 31 1994
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Book Synopsis Coal Combustion: Effect of Process Conditions on Char Reactivity. Quarterly Technical Report, October 1, 1994-December 31, 1994 by :
Download or read book Coal Combustion: Effect of Process Conditions on Char Reactivity. Quarterly Technical Report, October 1, 1994-December 31, 1994 written by and published by . This book was released on 1994 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Coal Combustion: Effect of Process Conditions on Char Reactivity. Quarterly Technical Report, July 1, 1994--September 30, 1994 by :
Download or read book Coal Combustion: Effect of Process Conditions on Char Reactivity. Quarterly Technical Report, July 1, 1994--September 30, 1994 written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The project will quantify the effect of the following pyrolysis conditions on the macropore structure and on the subsequent reactivity of chars: (a) pyrolysis heating rate; (b) final heat treatment temperature (HTT); (c) duration of heat treatment at HTT (or soak time); (d) pyrolysis atmosphere (N[sub 2] or O[sub 2]/N[sub 2] mixtures); (e) coal particle size (100-1,000[mu]m in diameter); (f) sulfur-capturing additives (limestone); and (g) coal rank. Pyrolysis experiments will be carried out for three coals from the Argonne collection: (1) a high-volatile bituminous coal with high ash content (Illinois[number-sign]6), (2) a bituminous coal with low ash content (Utah Blind Canyon) and (3) a lower rank subbituminous coal (Wyodak-Anderson seam). A mathematical model was developed to study the thermal ignition of char particles. The model assumes a bimodal pores size distribution with small micropores (of the order of a few[angstrom]) and large micropores in the[mu]m size range. All the model parameters can be estimated using data obtained previously in our laboratory. We are currently testing this model to determine its validity and to investigate how char properties (porosity, particle size, macropore surface area, micropore radius) and operating conditions (temperature, oxygen concentration, flow rate) affect ignition phenomena.
Download or read book Coal Combustion written by and published by . This book was released on 1994 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: Our efforts during the past quarter focused on quantifying the effects of pyrolysis conditions on the macropore structure of Illinois No. 6 chars. Using the image analysis technique developed in our laboratory, we analyzed the macropore structure of char samples produced at three different heating rates (0.1, 1 and 10°C/s), two different final heat treatment temperatures (500 and 700°C) and two different atmospheres (inert with pure N2 and reactive with 5% O2 in N2). Chars produced under all conditions had a very open macropore structure evidenced by the ability of the encapsulating epoxy to penetrate almost the entire pore structure. Increasing heating rates and the addition of oxygen produced char samples with larger macroporosity and higher values of macropore surface area. We would thus expect that high pyrolysis heating rates and the presence of oxygen would result in more reactive chars.
Download or read book Energy Research Abstracts written by and published by . This book was released on 1995 with total page 782 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Coal Combustion: Effect of Process Conditions on Char Reactivity. Quarterly Technical Report No. 14, January 1, 1995-March 31, 1995 by :
Download or read book Coal Combustion: Effect of Process Conditions on Char Reactivity. Quarterly Technical Report No. 14, January 1, 1995-March 31, 1995 written by and published by . This book was released on 1995 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Coal Combustion written by and published by . This book was released on 1991 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: The project will quantify the effect of the following pyrolysis conditions on the macropore structure and on the subsequent reactivity of chars: (a) pyrolysis heating rate; (b) final heat treatment temperature (HTT); (c) duration of heat treatment at HTT (or soak time); (d) pyrolysis atmosphere (N2 or O2/N2 mixtures); (e) coal particle size (100 - 1000 [mu]m in diameter); (f) sulfur-capturing additives (limestone); and (g) coal rank. Pyrolysis experiments will be carried out for three coals from the Argonne collection: (1) a high-volatile bituminous coal with high ash content (Illinois {number_sign}6), (2) a bituminous coal with low ash content (Utah Blind Canyon) and (3) a lower rank subbituminous coal (Wyodak-Anderson seam).
Download or read book Coal Combustion written by and published by . This book was released on 1992 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: The project will quantify the effect of the following pyrolysis conditions on the macropore structure and on the subsequent reactivity of chars: (a) pyrolysis heating rate; (b) final heat treatment temperature (HTT); (c) duration of heat treatment at HTT (or soak time); (d) pyrolysis atmosphere (N2 or O2/N2 mixtures); (e) coal particle size (100--1,000 [mu]m in diameter); (f) sulfur-capturing additives (limestone); and (g) coal rank. Pyrolysis experiments will be carried out for three coals from the Argonne collection: (1) a high-volatile bituminous coal with high ash content (Illinois {number_sign}6), (2) a bituminous coal with low ash content (Utah Blind Canyon) and (3) a lower rank subbituminous coal (Wyodak-Anderson seam). (VC).
Download or read book Coal Combustion written by and published by . This book was released on 1992 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: Our reactors have been reassembled at their new locations and the shakedown procedure was carried out successfully. The reactors are again fully operational and a series of experiments is already under way to continue our study on the effect of particle size on char combustion. Our main effort was focused on the mathematical modeling of char combustion. Computer simulations were carried out using our new three-dimensional model that allows us to study how char reactivities are affected by diffusional limitations in the micropores. We used again computational grids modeling three Illinois {number_sign}6 chars produced under nitrogen at heating rates of 0.1, 1 and 10 °C/s. Simulation results showed that diffusional limitations in the micropores have a significant effect on char reactivity and that the degree of micropore utilization is a strong function of conversion. We have also carried out simulations to investigate the role of inert ash inclusions and to determine how such inclusions affect the reactivity of chars.
Download or read book Coal Combustion written by and published by . This book was released on 1995 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: The project will quantify the effect of the following pyrolysis conditions on the macropore structure and on the subsequent reactivity of chars: (a) pyrolysis heating rate; (b) final heat treatment temperature (HTT); (c) duration of heat treatment at HTT (or soak time); (d) pyrolysis atmosphere (N2 or O2/N2 mixtures); (e) coal particle size (100--1000 [mu]m in diameter); (f) sulfur-capturing additives (limestone); and (g) coal rank. Pyrolysis experiments will be carried out for three coals from the Argonne collection: (1) a high-volatile bituminous coal with high ash content (Illinois {number_sign}6), (2) a bituminous coal with low ash content (Utah Blind Canyon) and (3) a lower rank subbituminous coal (Wyodak-Anderson seam). A systematic study was carried out in the past quarter to validate the mathematical model for ignition phenomena presented in the previous quarterly report. Model predictions of the effect of pyrolysis heating rate, particle size, and oxygen concentration on ignition behavior are in excellent agreement with experimental results. Moreover, our results show that the model can be used to estimate the particle temperature during ignition and the minimum ignition temperature for various process conditions.
Download or read book Coal Combustion written by and published by . This book was released on 1992 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the past quarter, we carried out a study of the kinetics of char combustion, assessed the reproducibility error of our experiments, and continued our systematic study of the effects of particle size and oxygen concentration on the reactivity of chars. The results from the kinetic study indicated that the rate expression for combustion of Illinois No. 6 chars is first order with respect to the oxygen concentration. The activation energy and the preexponential factor for this reaction were also calculated. The reproducibility error assessment shows that the average relative error increases with increasing particle size. Thus, the number of combustion runs needed for accurate measurements of the reaction rate increases with increasing particle size. For combustion in the regime of diffusional limitations, our results show the ignition temperature decreases with increasing pyrolysis heating rates, increasing coal particle size, decreasing heat treatment temperatures and increasing oxygen concentrations. The kinetic parameters (activation energy, preexponential rate factor, and order of reaction) for the combustion of Illinois No. 6 coal were determined using our thermogravimetric reactor with video microscopy imaging (TGA/VMI). In order to obtain a constant slope from the Arrhenius plot, the experiments were performed in the kinetic control regime. Our previous results demonstrated that in this regime char reactivity is independent of pyrolysis heating rate, heat treatment temperature (HTT), soak time and particle size. For this study therefore, we chose to pyrolyze and combust particles from the 28--32 mesh (500--600 [mu]m) fraction of Illinois No. 6 coal.
Download or read book Coal Combustion written by and published by . This book was released on 1992 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the past quarter, we systematically investigated the effects of particle size, pyrolysis heating rate, and heat treatment temperature on the reactivity of chars. The results show that pyrolysis heating rates or particle size do not affect the reactivity of chars in the kinetic control regime (420°C). High heat treatment temperatures (HTT) slightly lowered the char intrinsic reactivities. When the char particles were reacted in the regime of diffusional limitations (625°C), a significant effect of particle size was detected. We observed that decreasing final heat treatment temperatures resulted in small increases of the intrinsic reactivity for the smallest particles. For the largest particles, however, the effect of decreasing HTT was dramatic. By lowering the HTT from 775 to 625°C, the reactivity of chars at 625°C increased by a factor of 6 for chars produced from 20--25 mesh coal particles. Finally, the shape of the reactivity patterns changed significantly as we moved from the regime of kinetic control to the regime of intraparticle diffusional limitations.
Book Synopsis Coal Combustion: Effect of Process Conditions on Char Reactivity. Final Technical Report, September 1, 1991-May 31, 1995 by :
Download or read book Coal Combustion: Effect of Process Conditions on Char Reactivity. Final Technical Report, September 1, 1991-May 31, 1995 written by and published by . This book was released on 1996 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Beantwortung d. zu Kiel gedruckten Sendschreibens, betreffend die im Holsteinischen wütende Hornvieh-Seuche by :
Download or read book Beantwortung d. zu Kiel gedruckten Sendschreibens, betreffend die im Holsteinischen wütende Hornvieh-Seuche written by and published by . This book was released on 1745* with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Coal Combustion written by and published by . This book was released on 1993 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the past quarter, we systematically investigated the effects of pyrolysis heating rates on the fate of single particles of Utah Blind Canyon coal. These results were compared to those we obtained previously for Illinois No. 6 coal particles. The Blind Canyon coal particles show lower devolatilization rates with its maximum rate occurring at higher temperature. Illinois No. 6 coal particles swell more during pyrolysis and alternately expand and contract as they shrink to their final size, while Blind Canyon coal particles expand and contract smoothly without vigorous ''bubbling''. The final particle size of the various chars shows a strong dependence on the pyrolysis heating rate and the parent coal.
Download or read book Coal Combustion written by and published by . This book was released on 1993 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the past quarter, we developed the image analysis procedure for obtaining the transient swelling patterns of pyrolyzing coal particles. Pyrolysis experiments were videotaped and a sequence of digital images was acquired from each experiment tape at rates of 1.5 to 6 images per second. These digital images were then processed to measure the size and shape of pyrolyzing particles as a function of pyrolysis temperature. A systematic analysis of the transient swelling patterns showed significant differences among runs carried out at different heating rates. At low heating rates (1°C/s), the particles swelled rapidly to their maximum size. This initial swelling was followed by a ''bubbling'' phase during which the particles underwent a rapid sequence of expansions and contractions as bubbles of volatiles grew in the particle interior and broke through their surface. The particle size then decreased to show a small final swelling. At higher heating rates, the particle size decreased significantly during the ''bubbling'' phase and the final swelling was higher. A systematic comparison of particle swelling and devolatilization rates is also presented.
Book Synopsis Government Reports Annual Index by :
Download or read book Government Reports Annual Index written by and published by . This book was released on 1995 with total page 1686 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sections 1-2. Keyword Index.--Section 3. Personal author index.--Section 4. Corporate author index.-- Section 5. Contract/grant number index, NTIS order/report number index 1-E.--Section 6. NTIS order/report number index F-Z.
Download or read book Coal Combustion written by and published by . This book was released on 1992 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: Our reactors have been reassembled at their new locations and the shakedown procedure was carried out successfully. The reactors are again fully operational and a series of experiments is already under way to continue our study on the effect of particle size on char combustion. Our main effort was focused on the mathematical modeling of char combustion. Computer simulations were carried out using our new three-dimensional model that allows us to study how char reactivities are affected by diffusional limitations in the micropores. We used again computational grids modeling three Illinois {number_sign}6 chars produced under nitrogen at heating rates of 0.1, 1 and 10 °C/s. Simulation results showed that diffusional limitations in the micropores have a significant effect on char reactivity and that the degree of micropore utilization is a strong function of conversion. We have also carried out simulations to investigate the role of inert ash inclusions and to determine how such inclusions affect the reactivity of chars.
