Role of Additives in Controlling Agglomeration and Defluidization During Fluidized Bed Combustion of High-Sodium, High-Sulphur Low-Rank Coal

Linjewile, Temi M.; Manzoori, A.Reza

doi:10.1007/0-306-46920-0_24

Cited by 10 publications

(28 citation statements)

References 10 publications

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“…The circulating fluidized bed (CFB) gasifier operates at 850–950 °C. Research results show that the appropriate bed materials and suitable operating parameters could effectively inhibit fouling and slagging . During CFB gasification, air preheating could increase H 2 and CO production and the gas heating value .…”

Section: Introductionmentioning

confidence: 97%

Effect of the Air-Preheated Temperature on Sodium Transformation during Zhundong Coal Gasification in a Circulating Fluidized Bed

Song

et al. 2017

Energy Fuels

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Preheated air could improve the coal gas heating value and gas quality but, meanwhile, may cause slagging in the gasifier as a result of the enrichment of sodium in the ash. In this work, the migration and transformation of sodium during the Zhundong coal circulating fluidized bed gasification with different air-preheated temperatures were investigated. During the Zhundong coal gasification at 940 °C, with the air-preheated temperature increased from 20 to 600 °C, the air equivalent ratio decreased from 0.52 to 0.38 and the sodium content in the bottom ash increased 62.99%, 425.58% for circulating ash, and 44.02% for fly ash as a result of the effect of carbon inhibition. Accordingly, the release fraction of gaseous sodium decreased 42.82%. The condensation of gaseous sodium started at 800 °C of the coal gas temperature and reached a maximum at about 700 °C. The turning point of the temperature increased with the increase of the air-preheated temperature. The air-preheated temperature had little influence on the sodium occurrence of bottom ash. With the increase of the air-preheated temperature, the fraction of H2O-soluble sodium in fly ash and circulating ash increased and the ash fusion temperature of both fly ash and bottom ash dropped. Slagging blocks appeared during the gasification when the air-preheated temperature was up to 600 °C. Slagging blocks mainly contain SiO2 and Na2O. Sodium in the slagging blocks mainly exists as Na2Si2O5, insoluble sodium. The air-preheated temperature should be less than 600 °C to ensure the stable operation when the content of Na2O in the Zhundong coal ash is up to above 7.28%.

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Section: Introductionmentioning

confidence: 97%

Effect of the Air-Preheated Temperature on Sodium Transformation during Zhundong Coal Gasification in a Circulating Fluidized Bed

Song

et al. 2017

Energy Fuels

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“…Moreover, iron oxide was more effective than corundum in preventing bed agglomeration, while silica sand was not suitable as a bed material for the incineration of a biomass with a high alkaline content in the ash. Additives have been found to exhibit either chemical or physical dilution effects, depending on the extent of the interaction between the additive and the ash particles [5]. Under conditions in which the Fe 2 O 3 /(Na 2 O+K 2 O) molar ratio was greater than unity, Grubor et al [4] and Lee et al [7] reported that only Fe 2 O 3 could react with alkalis because of the higher reaction rate between Fe 2 O 3 and sodium or potassium relative to SiO 2 and alkalis.…”

Section: Introductionmentioning

confidence: 99%

“…The initial adhesion between sticky bed particles leads to the formation of bed agglomerates, followed by further ash-bed particle interactions [3]. Therefore, several researchers have studied methods to mitigate the agglomeration problem, primarily by reducing the formation of these alkali silicate melts [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Prevention of bed agglomeration with iron oxide during fluidized bed incineration of refuse-derived fuels

Kim

Lee

2009

Korean J. Chem. Eng.

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The present study was performed to evaluate the effect of iron oxide addition on the prevention of bed agglomeration during the fluidized bed incineration of refuse-derived fuels (RDFs) having different alkali contents. To investigate the extent of bed agglomeration as a function of the Fe 2 O 3 /(K 2 O+Na 2 O) molar ratio, a simulation was performed by using a thermodynamic equilibrium model. Based on this simulation, potassium (K) component exhibited a much higher affinity for iron (Fe) component than for silicon (Si) component, and the extent of agglomeration was remarkably reduced. Therefore, a small amount of iron oxide added to the bed effectively reduced the extent of bed agglomeration in the fluidized bed incineration process. Furthermore, the extent of agglomeration decreased as the molar ratio of Fe 2 O 3 /(K 2 O+Na 2 O) increased until unity was attained. In excess Fe 2 O 3 , no potassium silicate melts existed in the products, while the amount of sodium silicate melts remained constant.

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“…To solve this problem, mineral additives (Kyi and Chadwick, 1999;Wei et al, 2016) and bed materials (Linjewile and Manzoori, 1999;McCullough et al, 2011;Van Eyk et al, 2012;Vuthaluru et al, 1999;Xu et al, 2014) were reported as the main breakthrough. For example, silicon (Si)-rich minerals were found to be good sorbents for retaining Na-based compounds within coal ash, reducing the possibility of fouling in boiler tails (Kyi and Chadwick, 1999).…”

Section: Introductionmentioning

confidence: 99%

“…For example, silicon (Si)-rich minerals were found to be good sorbents for retaining Na-based compounds within coal ash, reducing the possibility of fouling in boiler tails (Kyi and Chadwick, 1999). Aluminum (Al)-rich minerals could increase the melting points of ash particles to inhibit the formation of low-temperature eutectics (Linjewile and Manzoori, 1999;McCullough et al, 2011;Van Eyk et al, 2012;Vuthaluru et al, 1999;Wei et al, 2016;Xu et al, 2014). Phosphorus (P)-rich sludge could effectively retain alkali metals in residual ash in the form of high-melting-point phosphates, avoiding defluidization of biomass in FB (Li, 2014).…”

Section: Introductionmentioning

confidence: 99%

Effect of bed materials on slagging and fouling during Zhundong coal gasification

Song

et al. 2017

Energy Exploration & Exploitation

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The suitable bed material is important to inhibit ash-related problems including agglomeration and slagging in furnace and fouling on tail heated surfaces during coal gasification in fluidized bed. For newfound high-alkali vast-reserve Zhundong coal in China, the selection of bed material in fluidized bed should be paid more attention because of its more serious ash-related issues. Five bed materials including quartz, kaolin, corundum, sludge ash, and phosphate rock were used to investigate their feasibility to solve the ash-related issues of two typical types of Zhundong coal including Tianchimulei coal and Shaerhu coal. All of five bed materials could effectively impact the release and transformation of alkali and alkaline earth metal species, especially Na species. The capture order of Na by five bed materials from high to low was sludge ash, quartz, kaolin, corundum, and phosphate rock for the two types of coal, and ash fusion temperatures of residual ash added different bed materials were in orders of phosphate rock > corundum > sludge ash > kaolin > quartz for Tianchimulei coal and corundum > phosphate rock > sludge ash > kaolin > quartz for Shaerhu coal. This influence of bed materials was mainly related to their chemical compositions, especially Al-, Si-, and P-based compounds. Due to the strong capture of alkali and alkaline earth metal-based compounds and high ash fusibility temperature, sludge ash was suggested as the appropriate selection of the bed material during Zhundong coal gasification in fluidized bed. Moreover, this suggestion would contribute to the sewage sludge treatment.

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Role of Additives in Controlling Agglomeration and Defluidization During Fluidized Bed Combustion of High-Sodium, High-Sulphur Low-Rank Coal

Cited by 10 publications

References 10 publications

Effect of the Air-Preheated Temperature on Sodium Transformation during Zhundong Coal Gasification in a Circulating Fluidized Bed

Effect of the Air-Preheated Temperature on Sodium Transformation during Zhundong Coal Gasification in a Circulating Fluidized Bed

Prevention of bed agglomeration with iron oxide during fluidized bed incineration of refuse-derived fuels

Effect of bed materials on slagging and fouling during Zhundong coal gasification

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