Methods for characterization of sorbents used in fluidized bed boilers☆

Adánez, Juan; Labiano, Francisco García; Abánades, Juan Carlos; Diego, Luis F. de

doi:10.1016/0016-2361(94)90087-6

Cited by 35 publications

(22 citation statements)

References 16 publications

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“…Up to now, calcium based sorbents have been characterized with batch fluidized bed reactors under air combustion conditions (Adánez et al, 1994, Suyadal et al, 2005. In this paper, the effect of the principal variables affecting sulfur retention (temperature, CO 2 partial pressure, SO 2 concentration and particle size) under oxy-fuel combustion conditions have been analyzed with this technique.…”

Section: Temperature (ºC)mentioning

confidence: 99%

Characterization of a limestone in a batch fluidized bed reactor for sulfur retention under oxy-fuel operating conditions

Diego

Loscertales

Garcı́a-Labiano

et al. 2011

International Journal of Greenhouse Gas Control

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a b s t r a c t CO 2 and SO 2 are some of the main polluting gases emitted into atmosphere in combustion processes using fossil fuel for energy production. The former is one of the major contributors to build-up the greenhouse effect implicated in global climate change and the latter produces acid rain. Oxy-fuel combustion is a technology, which consists in burning the fuel with a mix of pure O 2 and recirculated CO 2 . With this technology the CO 2 concentration in the flue gas may be enriched up to 95%, becoming possible an easy CO 2 recovery. In addition, oxy-fuel combustion in fluidized beds allows in situ desulfurization of combustion gases by supplying calcium based sorbent.In this work, the effect of the principal operation variables affecting the sulfation reaction rate in fluidized bed reactors (temperature, CO 2 partial pressure, SO 2 concentration and particle size) under typical oxy-fuel combustion conditions have been analyzed in a batch fluidized bed reactor using a limestone as sorbent. It has been observed that sulfur retention can be carried out by direct sulfation of the CaCO 3 or by sulfation of the CaO (indirect sulfation) formed by CaCO 3 calcination. Direct sulfation and indirect sulfation operating conditions depended on the temperature and CO 2 partial pressure. The rate of direct sulfation rose with temperature and the rate of indirect sulfation for long reaction times decreased with temperature. An increase in the CO 2 partial pressure had a negative influence on the sulfation conversion reached by the limestone due to a higher temperature was needed to work in conditions of indirect sulfation. Thus, it is expected that the optimum temperature for sulfur retention in oxy-fuel combustion in fluidized bed reactors be about 925-950 • C. Sulfation reaction rate rose with decreasing sorbent particle size and increasing SO 2 concentration.

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Section: Temperature (ºC)mentioning

confidence: 99%

Characterization of a limestone in a batch fluidized bed reactor for sulfur retention under oxy-fuel operating conditions

Diego

Loscertales

Garcı́a-Labiano

et al. 2011

International Journal of Greenhouse Gas Control

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“…Some researchers [19][20] have found that the optimum temperature for sulphur retention was nearly 850 ºC under conventional air combustion in FB combustors. These operating conditions are characterised by low CO 2 concentrations in the flue gas (up to 16%).…”

Section: Influence Of Temperaturementioning

confidence: 99%

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

Diego

Rufas

Garcı́a-Labiano

et al. 2013

Fuel

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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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“…In the empirical models it is defined as an asymptotic or limiting value Ž in plots of conversion against time Lee and Georgakis, 1981;Zheng et al, 1982;Fee et al, 1983;Chang and Thodos, 1984; . Adanez et al, 1994 . In the grain model, it is related to thé limiting size of the grains when they fill up the initial porosity Correspondence concerning this article should be addressed to Dr. J. C. Abanades.…”

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confidence: 95%

“…Ž and Lyngfelt, 1998 , and batch fluidized-bed reactors Zheng . et al, 1982;Dennis and Hayhurst, 1986;Adanez et al, 1994 , all of which try to reproduce the environment in a boiler. The usual time given to such sulfation tests varies between 2 and 6 h.…”

mentioning

confidence: 97%