High-temperature reaction between sulphur dioxide and limestone. V: The effect of periodically changing oxidizing and reducing conditions

Thermogravimetric analysis of the reaction between carbon and CaSO4·2H2O, gypsum and phosphogypsum in an inert atmosphere

Quand CaSO 4 est traite avec un melange de CO, CO 2 , SO 2 et N 2 a 1150°C dans un equipement d'analyse thermogravimetrique, differentes etapes de reaction sont identifiees et la distribution des produits finaux depend du potentiel reducteur (P CO /P CO2 2) des gaz. A de faibles potentiels (≤10), CaSO 4 2) des gaz. A de faibles potentiels (≤10), CaSO 4 est converti completement en CaO. A des potentiels moderes (par exemple 0,20), CuSO 4 est rapidement converti en CaO, qui est converti plus lentement en CaS

https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=1286&context=cbe_pubs

Reductive decomposition of calcium sulfate with carbon monoxide: reaction mechanism

Phosphogypsum decomposition is very complex because of its complicated compounds. In this study, using high-sulfur-concentration coal as a reducer, thermogravimetric analysis, differential thermal analysis, scanning electron microscopy, and X-ray diffraction were used to characterize the decomposition process of phosphogypsum in a nitrogen atmosphere at different conditions. Mechanism analysis and experiment results showed that the amount of the intermediate production of CaS depended on the heating rate and the size of coal used, which was produced mainly through the reaction between CaSO4 and C, and production would decrease with an increase of the coal size. 60 mesh was a suitable size of coal for phosphogypsum decomposition to get high recovery of the main production of CaO. Using Kissinger, Flynn−Wall−Ozaw, and Coats−Redfem methods, the mechanism model of phosphogypsum decomposition was confirmed, the decomposition process belonged to the core-form and growing mechanism (n = 2), and the kinetic model...

Reaction Mechanism and Kinetic Analysis of the Decomposition of Phosphogypsum via a Solid-State Reaction

The present disclosure relates to improved processes for treating hot sulfur-containing flue gas to remove sulfur therefrom. Processes in accordance with the present invention include preparing an aqueous slurry composed of a calcium alkali source and a source of reactive silica and/or alumina, heating the slurry to above-ambient temperature for a period of time in order to facilitate the formation of sulfur-absorbing calcium silicates or aluminates, and treating the gas with the heat-treated slurry compounds. Examples disclosed herein demonstrate the utility of these processes in achieving improved sulfur-absorbing capabilities. Additionally, disclosure is provided which illustrates preferred configurations for employing the present processes both as a dry sorbent injection and for use in conjunction with a spray dryer and/or bagfilter. Retrofit application to existing systems is also addressed.

Process for removing sulfur from sulfur-containing gases

Fluidized-Bed Combustion of Coal with Lime Additives. Kinetics and Mechanism of Regeneration of the Lime Sorbent

The reaction between carbonyl sulfide and calcium oxide was studied since the typical concentration of COS is 0.01Vertical Bar3< in the fuel gases from commercially available coal gasifiers. Rates of sorption of 0.1Vertical Bar3< COS in N/sub 2/, with 10Vertical Bar3< CO added to suppress decomposition of COS, were measured at 500/sup 0/-900/sup 0/C, a total pressure of 1 atm and a flow rate of 2000 std cc/min. The CaO sample was a reagent-grade fine powder with a particle size of 1-5 jm. The over-all rates at 600/sup 0/-900/sup 0/C correlated satisfactorily with the grain model (with a shape factor of 1.5), where chemical reaction was the rate-limiting step. The rate of reaction of COS with CaO was first order in COS with an activation energy of 4.3 kcal. The rate of sorption of COS by CaO was slightly higher than that of H/sub 2/S, using the literature data on the H/sub 2/S sorption. Significant sorption of COS takes place parallel to the sorption of H/sub 2/S in the coal gasification processes in which lime is used.

Kinetics of desulfurization of hot fuel gas with calcium oxide. Reaction between carbonyl sulfide and calcium oxide

This invention relates to the preparation of fine particles of reactive beta-dicalcium silicate by means of a solid state process which comprises firing a mixture of calcium sulfate, silica and a reducing additive selected from the group consisting of calcium sulfide, carbon, carbon monoxide, methane and hydrogen, at a temperature of about 850°-1000° C. A carrier gas such as nitrogen or carbon dioxide may also be added, if desired. A high concentration of sulfur dioxide is a by-product of this process.

James M. Chen

Papers

Fluidized-Bed Combustion of Coal with Lime Additives. Kinetics and Mechanism of Regeneration of the Lime Sorbent

Kinetics of desulfurization of hot fuel gas with calcium oxide. Reaction between carbonyl sulfide and calcium oxide

Preparation of reactive beta-dicalcium silicate

The optimal temperature of sulfur retention