FBC desulfurization process using coal with low sulfur content, high oxidizing conditions and metamorphic limestones

Bragança, Saulo Roca; Castellan, Jorge Luiz

doi:10.1590/s0104-66322009000200015

Cited by 13 publications

(6 citation statements)

References 15 publications

(28 reference statements)

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“…The increase of SO 2 concentration always enhances the sulfation rate of the CaO, as shown in the research of Abanades et al [23] and Diego et al [11]. Smaller sorbent particle size is favorable for the reaction of CaO and SO 2 because of the larger specific surface area smaller particles has [10,24]. However, sorbent with smaller particles may have shorter residence time in the furnace due to its higher elutriation level, which may cause a lower SO 2 removal efficiency [9].…”

Section: Introductionmentioning

confidence: 88%

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Simultaneous calcination and sulfation of limestone in CFBB

Wang

Chen

Jia³

et al. 2015

Applied Energy

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Section: Introductionmentioning

confidence: 88%

“…There is an optimum temperature at about 850°C for the desulfurization using CaO in air-fired CFBBs [23,24], although a lower optimum temperature of 825°C was once reported by Tarelho et al [8]. The efficiency of SO 2 removal decreases with the increase in the bed temperature above the optimum value for sulfur capture.…”

Section: Introductionmentioning

confidence: 93%

Simultaneous calcination and sulfation of limestone in CFBB

Wang

Chen

Jia³

et al. 2015

Applied Energy

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“…Both limestones reached ~70% of desulfurization efficiency. Other results of the limestones from southern Brazil used in desulfurization on bench and pilot scale can be found in the works of one of the authors (Bragança, 2003(Bragança, , 2009Sebag, 2001). The main disadvantage of the use of limestone Do is the smallest amount of calcium oxide (Table 2).…”

Section: Evaluation Of Limestones Do and D1 In Fbcmentioning

confidence: 99%

Evaluation of Limestone Impurities in the Desulfurization Process of Coal Combustion Gas

Souza

Bragança

2017

Braz. J. Chem. Eng.

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-Limestones have been used to capture SO2 emitted during the combustion of coal for decades. However, due to the complexities of the variables involved in this process, many issues are still being studied. Some tests were performed in a fluidized bed reactor, which was used to evaluate the performance of the limestones in the bed for flue gas desulfurization, burning low sulfur coal. Metamorphic dolomitic limestones of low cost were evaluated considering the impurity level and need for beneficiation. They were characterized chemically, physically and microstructurally (X-ray fluorescence, X-ray diffraction, laser particle size analyzer, scanning electronic microscope). The data obtained were compared to a calcitic limestone of elevated purity and higher market value. The results showed little effect of the major impurities present in the dolomitic limestones in the calcination and desulfurization processes. Microcrystalline impurities showed a marked effect promoting grain sintering in calcination conditions of TGA/DTA tests in different atmospheres, as shown in SEM images. Dolomitic limestones generate more solid waste and capture less SO2 per kcal (a slightly decrease in the thermal efficiency of the reactor) compared to calcitic limestones. However, due to the lower cost, they were considered to be attractive for the FBC process (2 mg SO2/kcal at Ca/S=3).

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“…SO 2 capture is strongly affected by the temperature. High temperature will cause the sintering of sorbent particles and thermodynamic instability of CaSO 4 under reducing conditions, and low temperature will reduce the calcination rate and inhibit the pore development, thus the maximum sulfur capture efficiency in atmospheric fluidized beds is usually achieved at 850 °C or a little lower [7,8,9,10]. Limestones vary greatly in properties, and the geological properties also have strong influence on the reactivity of CaO.…”

Section: Introductionmentioning

confidence: 99%

Effects of the Limestone Particle Size on the Sulfation Reactivity at Low SO2 Concentrations Using a LC-TGA

Cai

Huang

et al. 2019

Materials

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Limestone particle size has a crucial influence on SO2 capture efficiency, however there are few studies on the sulfation reactivity, which covers a broad range of particle sizes at low SO2 concentrations. In this paper, a large-capacity thermogravimetric analyzer (LC-TGA) was developed to obtain the sulfur removal reaction rate under a wide range of particle sizes (3 μm–600 μm) and SO2 concentrations (250 ppm–2000 ppm), and then compared with the results of a traditional fixed bed reactor and a commercial TGA. The experimental results showed that the LC-TGA can well eliminate the external mass transfer and obtain a better measurement performance. Both the final conversion and the reaction rate reduced with the decreasing of SO2 concentration, but ultrafine limestone particles still showed the good sulfation reactivity even at 250 ppm SO2. An empirical sulfation model was established based on the experimental results, which can well predict the sulfation process of different limestone particle sizes at low SO2 concentrations. The model parameters have a strong negative correlation against the particle size, and the fit of the reaction order of SO2 was found to be about 0.6. The model form is very simple to incorporate it into available fluidized bed combustion models to predict SO2 emission.

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FBC desulfurization process using coal with low sulfur content, high oxidizing conditions and metamorphic limestones

Cited by 13 publications

References 15 publications

Simultaneous calcination and sulfation of limestone in CFBB

Simultaneous calcination and sulfation of limestone in CFBB

Evaluation of Limestone Impurities in the Desulfurization Process of Coal Combustion Gas

Effects of the Limestone Particle Size on the Sulfation Reactivity at Low SO2 Concentrations Using a LC-TGA

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