Determination of sulfur release and its kinetics in rapid pyrolysis of coal

Garcı́a-Labiano, F.; Hampartsoumian, E.; Williams, A.

doi:10.1016/0016-2361(95)00049-b

Cited by 66 publications

(34 citation statements)

References 18 publications

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“…Similar results have been reported in earlier studies of rapid pyrolysis 18 and hydropyrolysis of coal, where the sulfur yield in the gas increased over the temperature range between 700 and Figures 2−5 show that the H 2 S concentration and mass of sulfur in the gas phase increased with an increase in the water/ coal mass ratio. For example, at 800°C with an initial H 2 pressure of 25 psi, the H 2 S concentration increased from 760 ppmv (7.6 × 10 −4 ) to 3000 ppmv (3 × 10 −3 ) and the mass of sulfur in the gas phase increased from 0.6 to 8.0 mg as the water/coal mass ratio increased from 0.5 to 3.…”

Section: Resultssupporting

confidence: 86%

Experimental Study of Gaseous Sulfur Species Formation during the Steam Hydrogasification of Coal

et al. 2014

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Steam hydrogasification is the thermochemical conversion of carbonaceous materials into synthesis gas in a steamand hydrogen-rich environment. The formation of gas-phase sulfur species during the pyrolysis and gasification of sulfurcontaining feedstocks, such as coal, presents well-known challenges. Gas-phase sulfur component formation under typical steam hydrogasification conditions was studied experimentally, and the impact of process parameters has been evaluated. The experimental results show that sulfur in the feedstock is mainly converted to hydrogen sulfide (H 2 S) during the steam hydrogasification reaction (SHR) process. Carbonyl sulfide (COS) and carbon disulfide (CS 2 ) were not observed in the gas phase. The H 2 -and steam-rich environment in the SHR process is favorable for the formation of H 2 S and suppresses COS and CS 2 formation. The H 2 S concentration in the gas phase increased consistently with increasing temperatures (700−800°C) and increasing water/coal mass ratios (0.5−3). These results are important in the development of a downstream sulfur cleanup system during SHR-based coal conversion.

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Section: Resultssupporting

confidence: 86%

Experimental Study of Gaseous Sulfur Species Formation during the Steam Hydrogasification of Coal

et al. 2014

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“…The organic sulphur exists either in aromatic rings or in aliphatic functional groups. The distribution between organic and pyritic sulphur depends on the rank and total sulphur content of the coal [17]. The release of the sulphur to form SO 2 in the oxy-fuel combustion process can depend on the sulphur distribution.…”

Section: Methodsmentioning

confidence: 99%

“…However, it is known that not all the sulphur contained in the coal is emitted as SO 2 either because it is already in sulphates form [17] or because coal ashes retain part of the SO 2 released [22][23][24].…”

Section: Influence Of the Ca/s Molar Ratiomentioning

confidence: 99%

Optimum temperature for sulphur retention in fluidised beds working under oxy-fuel combustion conditions

Diego

Rufas

Garcı́a-Labiano

et al. 2013

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Oxy-fuel combustion is one of the leading options for power generation with CO 2 capture. The process consists of burning the fuel with a mixture of nearly pure oxygen and a CO 2 -rich recycled flue gas, resulting in a product flue gas from the boiler containing mainly CO 2 and H 2 O. Among the possible boiler types, fluidised bed combustors are very appropriate for the oxy-fuel process because they allow the in-situ desulphurisation by feeding Ca-based sorbents into the combustor.In this work, the effect of the temperature of the combustor on the retention of the SO 2 generated in the combustion of two coals with very different sulphur content (a lignite and an anthracite) has been studied. The experimental facility used was a bubbling fluidised bed (BFB) combustor of ~3 kW th . Tests were conducted under oxy-fuel combustion mode and also under enriched-air combustion mode for comparison reasons. A Spanish limestone "Granicarb" was used as Ca-based sorbent for sulphur retention. The temperatures tested were between 800 and 970 ºC using Ca/S molar ratios between 0 and 3.It was found that in BFB combustors operating under oxy-fuel combustion conditions the optimum temperature to achieve the highest sulphur retention was 900-925 ºC, whereas operating with enriched air the optimum combustion temperature was ºC. Working at the optimum temperature, the SO 2 retentions were lower in oxy-fuel 2 combustion than in enriched air combustion conditions. It was also observed that working with lignite there was 10-15% of sulphur retention by coal ashes, however, working with anthracite the sulphur retention by coal ashes was negligible. This finding was independent of the combustion mode used, oxy-fuel or enriched air.

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“…It has also been reported that, in pulverized coal combustion, conversion of coal‐N to NO x increases when the N in the devolatilized solid residue (char) increases upon pyrolysis . Most researchers, however, have not considered the release of nitrogen and sulfur from char following devolatilization, such that only a few papers have been published on this topic to date …”

Section: Introductionmentioning

confidence: 99%

Formation of molecular nitrogen and hydrogen sulfide during high‐temperature pyrolysis of coals

Tsubouchi

2014

Asia-Pacific J Chem Eng

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Nitrogen and sulfur release from eleven coals during pyrolysis at high temperatures (≥1000°C) was studied in both fixed-bed and free-fall quartz reactors. Yields of N 2 , char-N and H 2 S were found to depend strongly on the pyrolysis conditions, such that N 2 and H 2 S yields increased with increasing pyrolysis temperature and coal particle residence time, whereas char-N decreased. There was also a strong inverse correlation between N 2 and char-N yields, suggesting that the majority of N 2 is produced from char-N through solid-phase reactions. H 2 S formation had no clear relationship with the carbon and sulfur contents of the parent coal. Demineralization with HCl washing was observed to remove primarily Ca 2+ cations from four low rank coals examined and to increase the char-N and H 2 S yields but decrease N 2 generation. In contrast, the addition of 3 wt% Ca to the four coals drastically enhanced N 2 formation and suppressed the formation of char-N and H 2 S. The X-ray diffraction analysis of the chars derived from Ca-loaded coals revealed that the Ca was present primarily as CaO with an average crystallite size of 15-45 nm, and that the presence of the Ca promoted carbon crystallization. Small diffraction peaks due to CaS were also observed. Fine particles of CaO may not only promote N 2 formation through solid phase reactions of char-N but undergo sulfur capture reactions. A mechanism for the Ca-catalyzed N 2 formation was discussed in terms of solid-solid reactions between CaO particles and char-N.

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Determination of sulfur release and its kinetics in rapid pyrolysis of coal

Cited by 66 publications

References 18 publications

Experimental Study of Gaseous Sulfur Species Formation during the Steam Hydrogasification of Coal

Experimental Study of Gaseous Sulfur Species Formation during the Steam Hydrogasification of Coal

Optimum temperature for sulphur retention in fluidised beds working under oxy-fuel combustion conditions

Formation of molecular nitrogen and hydrogen sulfide during high‐temperature pyrolysis of coals

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