Desulfurization of fuels with half-calcined dolomite. First kinetic data

Ruth, L.A.; Squires, Arthur M.; Graff, R.A.

doi:10.1021/es60071a004

Cited by 58 publications

(52 citation statements)

References 3 publications

(3 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Many studies of the reaction between calcined limestone (CaO) and half or fully calcined dolomites (respectively CaC0 3 -Mg0 and CaO-MgO) with HzS have been published (Abbasian et al, 1990;Freund, 1981;Squires et al, 1971;Ruth et al, 1972;Yen, 1979). These works were often concerned with the addition of limestone or dolomite to the coal in the gasifier where the conditions are such that the calcination of the calcium carbonate or the magnesium carbonate might occur rapidly (Freund, 1981), or were conducted at a C0 2 fugacity low enough to obtain partial or total calcination of the calcium carbonate.…”

Section: Chapi'er 2: Previous Workmentioning

confidence: 99%

Structural studies in limestone sulfidation

Fenouil¹

1993

View full text Add to dashboard Cite

Section: Chapi'er 2: Previous Workmentioning

confidence: 99%

Structural studies in limestone sulfidation

Fenouil¹

1993

View full text Add to dashboard Cite

“…As the equilibrium constant for reaction (2) is seen to be several orders of magnitude larger than for reaction (3), it may be inferred that reaction (2) is the main gas/solid reaction involved in the regeneration of CaS by CO 2, Further, the equilibrium constant for reaction (4) is in turn larger than that for reaction (2) by several orders of magnitude. Under the conditions, for example, at high temperatures, where chemical reaction is not controlling, the gas-phase at the reaction site is likely to be at equilibrium with respect to reaction (2) and (3).…”

Section: Chemistry and Thermodynamicsmentioning

confidence: 94%

Kinetic and Structural Studies of Regeneration of Sulfided Dolomite in Carbon Dioxide I the First Cycle Regeneration

Chou

1984

Chemical Engineering Communications

View full text Add to dashboard Cite

Communicated by H. L. Toor)Half-calcined dolomite (CaCO,' MgO) is one of the most promising sorbents for desulfurizing fuel gas at high temperatures. for environmental reasons, the spent dolomite must be capable of regeneration for cyclic use. Regeneration by a mixed gas of H 20/CO, has not met with success due mainly to the deterioration of sorbent reactivity with cycling. This research investigates an alternative method of regeneration using CO 2 alone and its application to cyclic use.Kinetic data for first cycle regeneration are collected in a TGA system at 500 to 950°C and 1 to 21.4 atm.The effects of gas-composition, preconditioning and solid structure are also studied. The results show that regeneration by CO, is equally effectiveas by H 20/C0 2 in terms of sorbent reactivity. More significantly, the sorbent has shown it much slower deterioration upon cycling. Examination of solid structure by SEM and compositional profile of sulfur by XES reveals that the reaction proceeds topochemically above 700°C and homogeneously below 650°C. A transport-reaction model is developed and shown to agree closely with experimental results.

show abstract

“…In view of this difference, the information that is presently available on the sulfidation of limestone-derived calcines (e.g., see and Efthimiadis and Sotirchos (1992)) and sulfidation of half-calcined dolomites (e.g., see Ruth et al (1972) and Yen et al (1981)) from studies in thermogravimetric analysis (TGA) systems and other types of reactors is inapplicable to the direct reaction of limestones with H 2 S. Few fundamental studies have been presented in the literature on the direct reaction of limestones with H 2 S, and most of those have been carried out under low pressures or under conditions where both sulfidation reactions ( (7) and (8)) could take place (Attar and Dupuis, 1979). …”

Section: Background Informationmentioning

confidence: 99%

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

Sotirchos¹

1998

View full text Add to dashboard Cite

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...

show abstract

Desulfurization of fuels with half-calcined dolomite. First kinetic data

Cited by 58 publications

References 3 publications

Structural studies in limestone sulfidation

Structural studies in limestone sulfidation

Kinetic and Structural Studies of Regeneration of Sulfided Dolomite in Carbon Dioxide I the First Cycle Regeneration

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

Contact Info

Product

Resources

About