Waste Materials from the Power Industry as Potential Fuel for Fluidized Bed Boilers

Bulewicz, E.M.; Jurys, C.; Kandefer, Stanisław

doi:10.1016/s0166-1116(08)70972-5

Cited by 4 publications

(8 citation statements)

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“…In accordance with the above remarks, the experimental evidence in most of the studies of the literature indicates strong effects of the pore size distribution on the overall reactivity of the calcined solids (Borgwardt and Harvey, 1972;Wen and Ishida, 1973;Coughlin, 1974, 1976;Ulerich et al, 1977;Vogel et al, 1977;Hasler et al, 1984;Simons and Garman, 1986;Yu, 1987;Gullett and Bruce, 1987;Zarkanitis and Sotirchos, 1989;Zarkanitis, 1991 desulfurization is known to occur in PFBC units (Bulewicz and Kandefer, 1986;Murthy et al, 1979 …”

Section: Background Informationsupporting

confidence: 53%

“…Hayhurst (1984, 1987), for example, found that the reaction rate of precalcined limestones in a fluidized-bed reactor decreases with an increase in the operating pressure, both in the absence and presence of CO 2 . Working with a laboratory-size PFBC, Bulewicz et al (1986) observed an increase in the sorption capacity of Ca-based sorbents (chalk, limestone, and dolomite) with an increase in pressure up to 2 atm, but further increase in pressure caused a reduction in the sorption capacity of all samples. Similar observations were made by Jansson et al (1982).…”

Section: Background Informationmentioning

confidence: 97%

“…Studies of SO 2 removal at high pressures have been carried out both with carbonates and precalcined solids (Newby et al, 1980;Ulerich et al, 1982;Hayhurst, 1984, 1987;Bulewicz et al, 1986). However, because of the aforementioned complexities, with the exception of the general conclusion that favorable desulfurization is possible under PFBC conditions, there is not much agreement in the literature on the effects of the various parameters on the process.…”

Section: Background Informationmentioning

confidence: 99%

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REMOVAL OF H{sub 2}S AND SO{sub 2} BY CaCO{sub 3}-BASED SORBENTS AT HIGH PRESSURES

Sotirchos¹

1998

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ii EXECUTIVE SUMMARYThe theoretical and experimental investigation of the mechanism of SO 2 and H 2 S removal by CaCO 3 -based sorbents (limestones and dolomites) in pressurized fluidized-bed coal combustors (PFBC) and high pressure gasifiers, respectively, is the main objective of this study.It is planned to carry out reactivity evolution experiments under simulated high pressure conditions or in high pressure thermogravimetric and, if needed, fluidized-bed reactor (high pressure) arrangements. The pore structure of fresh, heat-treated, and half-calcined solids (dolomites) will be analyzed using a variety of methods. Our work will focus on limestones and dolomites whose reaction with SO 2 or H 2 S under atmospheric conditions has been studied by us or other research groups in past studies. Several theoretical tools will be employed to analyze the obtained experimental data including a variable diffusivity shrinking-core model and models for diffusion, reaction, and structure evolution in chemically reacting porous solids.During the six months of this reporting period, more work was done on the study of the behavior of the sulfidation of calcined limestones in the presence of small amounts of oxygen. As it was mentioned in the previous report, the incentive for carrying out sulfidation experiments in the presence of oxygen was provided by the observation that some sulfidation experiments that were conducted as oxygen was accidentally leaking into the feed mixture of the reactor showed completely different behavior from that obtained in the absence of oxygen. Experiments were carried out in the thermogravimetric analysis system that we developed for studying gas-solid reactions at atmospheric or subambient pressures using the two CaCO 3 solids (Greer limestone and Iceland spar) that we employed in our previous experiments. It was decided to conduct more experiments on the sulfidation of calcined limestones in the presence of small amounts of oxygen because the experimental curves that were obtained in our past experiments not only exhibited unsatisfactory quantitative reproducibility, but also in a few cases, the solid material that was placed on the pan (initially CaCO 3 ) was completely converted to gaseous products during exposure to a N 2 -H 2 S atmosphere containing small amounts of oxygen (below 0.2-0.3%). The new results led to conclusions that were in agreements with those reached in our iii previous studies. For small oxygen concentrations, the weight gained by small particles of the calcined sample during sulfidation went through a maximum, whereas for oxygen concentrations above 0.5-0.8%, it increased continuously and could reach values corresponding to complete conversion of CaO to CaSO 4 .The above behavior was more pronounced for the Greer Limestone sample, which past studies had shown that it exhibited much lower resistance to intraparticle mass transport than the other sample (Iceland Spar). The large particles (297-350 µm) of Greer Limestone and Iceland Spar we used in the experiments did not sho...

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Section: Background Informationsupporting

confidence: 53%

Section: Background Informationmentioning

confidence: 97%

Section: Background Informationmentioning

confidence: 99%

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REMOVAL OF H{sub 2}S AND SO{sub 2} BY CaCO{sub 3}-BASED SORBENTS AT HIGH PRESSURES

Sotirchos¹

1998

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“…Hayhurst (1984,1987), for example, found that the reaction rate of precalcined limestones in a fluidized-bed reactor decreases with an increase in the operating pressure, both in the absence and presence of CO2. Working with a laboratory-size PFBC, Bulewicz et al (1986) observed an increase in the sorption capacity of Ca-based sorbents (chalk, limestone, and dolomite) with an increase in pressure up to 2 atm, but further increase in pressure caused a reduction in the sorption capacity of all samples. Similar observations were made by Jansson et al (1982).…”

Section: Background Informationmentioning

confidence: 97%

“…Studies of SO, removal at high pressures have been carried out both with carbonates and precalcined solids (Newby et al,, 1980;Ulerich et al, 1982;Hayhurst, 1984, 1987;Bulewicz et al, 1986). However, because of the aforementioned complexities, with the exception of the general conclusion that favorable desulfurization is possible under PFBC conditions, there is not much agreement in the literature on the effects of the various parameters on the process.…”

Section: Background Informationmentioning

confidence: 99%

Removal of H{sub 2}S and SO{sub 2} by CaCO{sub 3}-based sorbents at high pressures. Semiannual report, August 1995--January 1996

Sotirchos¹

1996

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Influence of Periodically Changing CO₂ Partial Pressure on Sulfur Capture and Free Lime Content of Residues in PFBC

Qiu

Steenari

2000

Energy Fuels

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PFBC technology is still under development. Further research into the capture of SO 2 by limestone during PFBC is needed. The present work investigates the influence of periodically changing partial pressure of CO 2 on the sulfation of limestone and also the free lime content present in residual products. Experiments were conducted in a fixed-bed reactor under conditions typical of PFBC, that is, limestone particles were alternately exposed to the conditions of calcination and recarbonation as the reaction of sulfation proceeded. It was found that the degree of sulfation achieved was considerably higher with periodically changing partial pressure of CO 2 than with a steady high partial pressure of CO 2 . This was true even when the average value of the pressure during its periodical change exceeded the calcination equilibrium pressure. These findings may partly explain the high conversion of limestone obtained in PFBC units. Furthermore, the free lime content proved remarkably different for various cycle times of changing CO 2 partial pressure and/or various periods of a cycle time elapsing in the calcining region. This indicates that the content of free lime in solid residues from PFBC boilers can vary considerably with respect to overall operating conditions.

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Waste Materials from the Power Industry as Potential Fuel for Fluidized Bed Boilers

Cited by 4 publications

References 2 publications

REMOVAL OF H{sub 2}S AND SO{sub 2} BY CaCO{sub 3}-BASED SORBENTS AT HIGH PRESSURES

REMOVAL OF H{sub 2}S AND SO{sub 2} BY CaCO{sub 3}-BASED SORBENTS AT HIGH PRESSURES

Removal of H{sub 2}S and SO{sub 2} by CaCO{sub 3}-based sorbents at high pressures. Semiannual report, August 1995--January 1996

Influence of Periodically Changing CO₂ Partial Pressure on Sulfur Capture and Free Lime Content of Residues in PFBC

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Waste Materials from the Power Industry as Potential Fuel for Fluidized Bed Boilers

Cited by 4 publications

References 2 publications

REMOVAL OF H{sub 2}S AND SO{sub 2} BY CaCO{sub 3}-BASED SORBENTS AT HIGH PRESSURES

REMOVAL OF H{sub 2}S AND SO{sub 2} BY CaCO{sub 3}-BASED SORBENTS AT HIGH PRESSURES

Removal of H{sub 2}S and SO{sub 2} by CaCO{sub 3}-based sorbents at high pressures. Semiannual report, August 1995--January 1996

Influence of Periodically Changing CO2 Partial Pressure on Sulfur Capture and Free Lime Content of Residues in PFBC

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Influence of Periodically Changing CO₂ Partial Pressure on Sulfur Capture and Free Lime Content of Residues in PFBC