Reduction of calcium sulfate in a coal-fired circulating fluidized bed furnace

Talukdar, J.; Basu, Prabir; Greenblatt, J. H.

doi:10.1016/0016-2361(96)00054-3

Cited by 34 publications

(34 citation statements)

References 6 publications

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“…3−13 Graphite, char, hydrogen, and carbon monoxide are all capable of reducing calcium sulfate to SO 2 , but out of all, carbon monoxide (reactions 2 and 4) is reported to be the most effective CaSO 4 reducing agent. 8 At CO concentrations higher than 0.1 vol %, CaS or CaO become more stable than CaSO 4 . 9 ↔ + + 2CaSO (s) 2CaO(s) 2SO (g) O (g) 4 2 2 (1)…”

Section: ■ Introductionmentioning

confidence: 98%

Waste Gypsum Board and Ash-Related Problems during Combustion of Biomass. 1. Fluidized Bed

et al. 2015

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This paper is the first in a series of two describing the use of waste gypsum boards as an additive during combustion of biomass. This paper focuses on experiments performed in a bench-scale bubbling fluidized-bed reactor (5 kW). Three biomass fuels were used, i.e., wheat straw (WS), reed canary grass (RC), and spruce bark (SB), with and without addition of shredded waste gypsum board (SWGB). The objective of this work was to determine the effect of SWGB addition on biomass ash transformation reactions during fluidized bed combustion. The combustion was carried out in a bed of quartz sand at 800 or 700°C for 8 h. After the combustion stage, a controlled fluidized−bed agglomeration test was carried out to determine the defluidization temperature. During combustion experiments, outlet gas composition was continuously measured by means of Fourier transform infrared spectroscopy. At the same place in the flue gas channel, particulate matter was collected with a 13-stage Dekati low-pressure impactor. Bottom and cyclone fly ash samples were collected after the combustion tests. In addition, during the combustion tests a 6-h deposit sample was collected with an air-cooled (430°C) probe. All ash samples were analyzed by means of scanning electron microscopy combined with energy dispersive X-ray spectrometry for elemental composition and with X-ray powder diffraction for the detection of crystalline phases. Decomposition of CaSO 4 originating from SWGB was mainly observed during combustion of reed canary grass at 800°C. The decomposition was observed as doubled SO 2 emissions. No significant increase of SO 2 during combustion of SB and WS was observed. However, the interaction of SWGB particles with WS and SB ash forming matter, mainly potassium containing compounds, led to the formation of K 2 Ca 2 (SO 4 ) 3 .

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Section: ■ Introductionmentioning

confidence: 98%

Waste Gypsum Board and Ash-Related Problems during Combustion of Biomass. 1. Fluidized Bed

et al. 2015

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“…In the atmosphere, sulfur in coal releases in the form of H 2 S which reacts with CaO to form CaS in the following steps. [11] After entering dilute phase zone, H 2 S and CaS will still be oxidized to SO 2 and CaSO 4 in the following reactions if air is sufficient:…”

Section: Effect Of Excess Air Coefficient On So 2 Emissionmentioning

confidence: 99%

Investigation on SO₂ emission from 410t/h circulating fluidized bed boiler burning petroleum coke and coal

Duan

Chen

et al. 2009

Asia-Pacific J Chem Eng

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Effects of operation parameters including bed temperature, Ca/S molar ratio, excess air coefficient, fly ash recirculation rate and limestone microstructure on SO 2 emission were investigated on a 410t/h circulating fluidized bed (CFB) boiler burning petroleum coke and coal. Results show that for different fuels, SO 2 emission is correspondingly related to the sulfur content in it under the same operation conditions. With increasing bed temperature, SO 2 concentration in the flue gas reduces first and then increases. There is an optimal desulfurization temperature. For burning bituminous coal (BC) only or 70% BC + 30% petroleum coke (PC), the optimal desulfurization temperature is about 850• C, while it is about 850-870• C for burning 50% anthracite (AN) + 50% PC. SO 2 emission decreases with the increase in Ca/S ratio, excess air coefficient and fly ash recirculation rate. Microstructure of limestone has distinct effects on their SO 2 retention capacity, and bigger specific surface area and higher specific pore volume lead to stronger SO 2 capture activities. The optimal temperature, Ca/S ratio and excess air coefficient for different fuels are recommended for industrial application. 

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“…As a result, Ca/S mole ratio is usually chosen between two and four in a classical fluidized bed combustor [29]. On the other hand, high SO 2 retention efficiencies were obtained for Ca/S mole ratios of less than two in a circulating fluidized bed combustor [30].…”

Section: Kinetic Modelmentioning

confidence: 99%

Si̇rkülasyonlu Bi̇r Akişkan Yatakli Yakicida İşletme Parametreleri̇ni̇n So2 Emi̇syonu Üzeri̇ndeki̇ Etki̇leri̇

Güngör¹

2016

Ömer Halisdemir Üniversitesi Mühendislik Bilimleri Dergisi

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Reducing SO 2 emission from power plants is one of the main issues for the environmental protection. One of the advantages of the CFB combustion technology of coal is in situ SO 2 capture by added sorbents, usually uncalcined limestone (CaCO 3 ). In this theoretical study effects of operational parameters such as sorbent particle diameter, Ca/S molar ratio and superficial velocity on SO 2 emission have been estimated using a previously developed dynamic 2D model for CFBCs. In the model, the unreacted shrinking core model has been adopted for desulphurization. As a result of this study; it is observed that operational bed velocity has positive effect on SO 2 emission. Air-staging strongly influences the concentration and distribution of sulphur compounds in the combustion chamber of fluidized beds. Feeding limestone with high proportion of fines into the combustor causes high sulphur retentions.Keywords: Circulating fluidized bed, coal combustion, modeling, SO 2 emission SĐRKÜLASYONLU BĐR AKIŞKAN YATAKLI YAKICIDA ĐŞLETME PARAMETRELERĐNĐN SO 2 EMĐSYONU ÜZERĐNDEKĐ ETKĐLERĐ ÖZET Çevresel korunma göz önüne alındığında, güç santrallerinde SO 2 emisyonunun indirgenmesi ana konulardan biridir. Kömürün sirkülasyonlu akışkan yatak (SAY) yakma teknoloji ile yakılmasının en önemli avantajlarından birisi de genellikle kalsine olmamış kireçtaşı (CaCO 3 ) gibi sorbentlerin eklenmesiyle doğal SO 2 tutma kabiliyetidir. Bu teorik çalışmada, sorbent tane çapı, Ca/S mol oranı ve yatak işletme hızı gibi işletme parametrelerinin SO 2 emisyonu üzerindeki etkileri; daha önce SAY yakıcılar için geliştirilmiş olan dinamik model kullanılarak tahmin edilmiştir. Modelde reaksiyona girmemiş büzülen tanecik modeli kükürt indirgenmesine adapte edilmiştir. Bu çalışma sonucunda; yatak işletme hızının SO 2 emisyonu üzerinde pozitif bir etkiye sahip olduğu, ikincil hava kullanmanın yatak içerisindeki sülfür dağılımı ve konsantresi üzerinde güçlü bir etkiye sahip olduğu ve beslenen kireçtaşının içeriğinin yüksek oranda toz içermesi durumunda yatak içerisinde kükürt indirgemesini arttırdığı görülmüştür.Anahtar Kelimeler: Sirkülasyonlu akışkan yatak, kömür yanması, modelleme, SO 2 emisyonu

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Reduction of calcium sulfate in a coal-fired circulating fluidized bed furnace

Cited by 34 publications

References 6 publications

Waste Gypsum Board and Ash-Related Problems during Combustion of Biomass. 1. Fluidized Bed

Waste Gypsum Board and Ash-Related Problems during Combustion of Biomass. 1. Fluidized Bed

Investigation on SO₂ emission from 410t/h circulating fluidized bed boiler burning petroleum coke and coal

Si̇rkülasyonlu Bi̇r Akişkan Yatakli Yakicida İşletme Parametreleri̇ni̇n So2 Emi̇syonu Üzeri̇ndeki̇ Etki̇leri̇

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Reduction of calcium sulfate in a coal-fired circulating fluidized bed furnace

Cited by 34 publications

References 6 publications

Waste Gypsum Board and Ash-Related Problems during Combustion of Biomass. 1. Fluidized Bed

Waste Gypsum Board and Ash-Related Problems during Combustion of Biomass. 1. Fluidized Bed

Investigation on SO2 emission from 410t/h circulating fluidized bed boiler burning petroleum coke and coal

Si̇rkülasyonlu Bi̇r Akişkan Yatakli Yakicida İşletme Parametreleri̇ni̇n So2 Emi̇syonu Üzeri̇ndeki̇ Etki̇leri̇

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Investigation on SO₂ emission from 410t/h circulating fluidized bed boiler burning petroleum coke and coal