Sulfate decomposition from circulating fluidized bed combustors bottom ash

Hoteit, Ali; Bouquet, Eric; Schönnenbeck, Cornélius; Gilot, P.

doi:10.1016/j.ces.2007.07.057

Cited by 13 publications

(9 citation statements)

References 6 publications

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“…The aliphatic sulfur was decomposed below 770 K and the aromatic sulfur was decomposed at 673-973 K, as suggested by Miura et al [16]. The decomposing temperature of inorganic sulfate is usually over 1300 K [13,14]. Fig.…”

Section: Formation Of So 2 From Coal Combustion In 21%o 2 /79%n 2 Andmentioning

confidence: 97%

Sulfur evolution from coal combustion in O2/CO2 mixture

Duan

Zhao

Zhou

et al. 2009

Journal of Analytical and Applied Pyrolysis

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Section: Formation Of So 2 From Coal Combustion In 21%o 2 /79%n 2 Andmentioning

confidence: 97%

Sulfur evolution from coal combustion in O2/CO2 mixture

Duan

Zhao

Zhou

et al. 2009

Journal of Analytical and Applied Pyrolysis

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“…It is well-known that CaSO 4 is thermodynamically stable in air up to 1300 °C when it decomposes to lime (CaO) and sulfur dioxide/trioxide (SO 2 /SO 3 ) (reaction ). However, the decomposition of CaSO 4 at lower temperatures under reducing conditions has been reported in the literature. − Graphite, char, hydrogen, and carbon monoxide are all capable of reducing calcium sulfate to SO 2 , but out of all, carbon monoxide (reactions and ) is reported to be the most effective CaSO 4 reducing agent . At CO concentrations higher than 0.1 vol %, CaS or CaO become more stable than CaSO 4…”

Section: Introductionmentioning

confidence: 97%

“…The decomposition of calcium sulfate is highly temperature dependent, and only a small portion seems to be emitted under 850 °C. 13 It can be, however, enhanced by ferric salt 15 or iron oxide, 16 which can lower the decomposition temperature to 650 or 870 °C, respectively. The interactions of anhydrite with solid acidic oxides, major components of coal ash, were reported by Brady et al 6 Their experiments of coal combustion in air at approximately 930 °C with CaSO 4 , with and without addition of a small proportion of silica and alumina, showed that more than 30% of the sulfur was released in all cases.…”

Section: ■ Introductionmentioning

confidence: 99%

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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“…The absence of oxygen favours the decomposition of sulphates above 950 °C. At the same time, the decomposition is inhibited by increasing the O 2 concentration, especially over 5% [33,34]. Thus, the peak area of SO 2 during the whole oxidation process in an oxygen-bearing atmosphere is smaller than that in a pure CO 2 atmosphere.…”

Section: Effect Of Atmosphere On the Gas Evolvedmentioning

confidence: 98%

Oxidation Characteristics of the Semicoke From the Retorting of Oil Shale and Wheat Straw Blends in Different Atmospheres

Mu¹,

Han²,

Chen³

et al. 2019

Oil Shale

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A new way of utilizing oil shale is its co-retorting with wheat straw for oil. However, the process generates a great amount of combustible solid semicoke waste. To utilize this waste effectively for heating the retorting process, the current work investigated its oxidation characteristics by employing a combined thermogravimetry-mass spectrometry (TG-MS) system, and discussed the effects of three parameters, including the wheat straw mass fraction of matrix samples, as well as different ambient gases and their O 2 volume fraction, on the oxidation of the semicoke. In the presence of O 2 , the whole oxidation process of semicoke samples mainly consists of two stages: the combustion stage (300-600 °C) in which water, CO, CO 2 and pollutants are mainly released, and the decomposition stage (600-1000 °C) in which carbonates and sulphates decompose to release CO 2 and SO 2 , respectively. In the combustion stage, increasing both the wheat straw proportion of the original sample and the O 2 volume faction can improve the combustion performance of the resulting semicoke blends. In the decomposition stage, the gasification reaction also occurs to produce CO. During the entire oxidation process, semicoke in 21% O 2 /79% CO 2 would give off less NOx and SO 2 than in air. And, SO 2 formation is also influenced by the O 2 fraction, especially above 900 °C.

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Sulfate decomposition from circulating fluidized bed combustors bottom ash

Cited by 13 publications

References 6 publications

Sulfur evolution from coal combustion in O2/CO2 mixture

Sulfur evolution from coal combustion in O2/CO2 mixture

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

Oxidation Characteristics of the Semicoke From the Retorting of Oil Shale and Wheat Straw Blends in Different Atmospheres

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