Effect of water vapor on the pore structure and sulfation of CaO

Wang, Chunbo; Zhang, Yue; Jia, Lei; Tan, Yewen

doi:10.1016/j.fuel.2014.04.007

Cited by 28 publications

(22 citation statements)

References 24 publications

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“…After the furnace reached the set temperature and was purged by synthetic flue gas for 15 min, the sample (80 ± 2 mg) was loaded into a quartz boat, and its mass was continually measured by a mass monitor (accuracy 0.1 mg) and recorded by computer. Our previous work with this system showed that it has sufficient accuracy for this type of study.…”

Section: Methodsmentioning

confidence: 98%

“…To increase the sulfation rate, a smaller particle size, higher SO 2 concentration and optimum temperature are suggested . Limestone particles in a CFB are recirculated and sulfated for periods of hours, and the long‐term sulfation reaction can usually be divided into a fast‐reaction stage and a slow‐reaction stage . The common consensus is that the fast‐sulfation stage is controlled by the intrinsic reaction rate or SO 2 diffusion, while in the slow stage the diffusion through the CaSO 4 product layer is the major resistance to sulfation …”

Section: Introductionmentioning

confidence: 99%

“…Investigation has shown that the calcination of CaCO 3 , sintering and sulfation of CaO are all significantly affected by H 2 O . Many investigations have reported that the calcination of CaCO 3 can be greatly accelerated by H 2 O, even at very low steam pressures . Researchers have put forward different theories to explain the effect of H 2 O on CaCO 3 decomposition.…”

Section: Introductionmentioning

confidence: 99%

“…H 2 O can also affect the sulfation of CaO . Some investigations have reported that H 2 O had little influence on the sulfation reaction in the fast stage, but significantly accelerated the reaction rate in the slow‐sulfation stage.…”

Section: Introductionmentioning

confidence: 99%

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The combined effect of H₂O and SO₂ on the simultaneous calcination/sulfation reaction in CFBs

et al. 2019

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The combined effect of H2O and SO2 on the reaction kinetics and pore structure of limestone during simultaneous calcination/sulfation reactions under circulating fluidized bed (CFB) conditions was first studied in a constant‐temperature reactor. H2O can accelerate the sulfation reaction rate in the slow‐sulfation stage significantly but has a smaller effect in the fast‐sulfation stage. H2O can also accelerate the calcination of CaCO3, and should be considered as a catalyst, as the activation energy for the calcination reaction was lower in the presence of H2O. When the limestone particles are calcining, SO2 in the flue gas can react with CaO on the outer particle layer and the resulting CaSO4 blocks the CaO pores, increases the diffusion resistance of CO2, and, in consequence, decreases the calcination rate of CaCO3. Here, gases containing 15% H2O and 0.3% SO2 are shown to increase the calcination rate. This means that the accelerating effect of 15% H2O on CaCO3 decomposition is stronger than the impeding effect caused by 0.3% SO2. The calcination rate of limestone particles was controlled by both the intrinsic reaction and the CO2 diffusion rate in the pores, but the intrinsic reaction rate played a major role as indicated by the effectiveness factors determined in this work. This may explain the synergic effect of H2O and SO2 on CaCO3 decomposition observed here. Finally, the effect of H2O and SO2 on sulfur capture in a 600 MWe CFB boiler burning petroleum coke is also analyzed. The sulfation performance of limestone evaluated by simultaneous calcination/sulfation is shown to be much higher than that by sulfation of CaO. Based on our calculations, a novel use of the wet flue gas recycle method was put forward to improve the sulfur capture performance for high‐sulfur low‐moisture fuels such as petroleum coke. © 2019 American Institute of Chemical Engineers AIChE J, 65: 1256–1268, 2019

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Section: Methodsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The combined effect of H₂O and SO₂ on the simultaneous calcination/sulfation reaction in CFBs

et al. 2019

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“…The formed calcium sulfate (CaSO 4 ) layer is porous due to carbon dioxide (CO 2 ) production which escapes during the reaction (Eqn (1)). The parameters affecting the overall rate and conversion of reactions (Eqns (1) and (3)) are as follows: temperature ( T ), pressure ( P ), partial pressure of the gaseous reactants (

P_{{SO}_{2}}

P_{O_{2}}

), diameter or general geometry of the CaCO 3 particle ( d p ), structural characteristics of limestone, reaction time ( t ) and water vapor. Capture of sulfur (S) by sulfur trioxide (SO 3 ) formation does not have a significant impact, due to the small degree of conversion of SO 2 to SO 3 in non‐catalytic conditions .…”

Section: Introductionmentioning

confidence: 99%

Experimental study and parametric analysis of SO₂ capture in limestone fixed bed reactor

Bontzolis

Petraki

Spartinos

2019

J of Chemical Tech & Biotech

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BACKGROUND The use of absorbents, based on calcium, for the reduction of sulfur dioxide (SO2) emissions from power plants has been studied for the last 90 years. The present work is part of a research project, which aims at the development of a fixed and a moving bed limestone filter. A filter is placed after the burning, in order to capture SO2 from the flue gases of pulverized lignite combustors. An experimental study and a parametric analysis in a limestone and lignite fixed bed reactor for SO2 capture were conducted in previous works. RESULTS This work studies experimentally the SO2 capture by analyzing the following parameters: inlet mole fraction of SO2, inlet mole fraction of O2, volumetric flow rate, average temperature in bed, type of calcium carbonate (CaCO3) and length of the solid bed. Under specific circumstances, conversion of SO2 values were found to be greater than 0.99 in the gas outlet for more than 110 min. CONCLUSION Useful conclusions are drawn regarding the behavior of a fixed bed reactor in different conditions. The results highlight the importance of technological interest in the dry process for SO2 capture. © 2019 Society of Chemical Industry

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On the modeling of the co₂‐catalyzed sintering of calcium oxide

Maya

Bhatia

2017

AIChE Journal

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A comprehensive mathematical model for the CO2‐catalyzed sintering of CaO is proposed. It takes into account the mechanisms of surface diffusion and grain boundary diffusion, catalyzed by CO2 chemisorption and dissolution, respectively. In addition, the model proposed here considers the change in pore size distribution during sintering, grain growth, and the densification by lattice diffusion, which is the intrinsic sintering mechanism of the CaO. Model predictions are validated using experimental data on the sintering of two CaO samples, one of them derived from pure CaCO3 and the other from limestone. It is found that impurities in limestone‐derived CaO do not significantly affect the CO2 dissolution or chemisorption processes; however, they strongly increase the rate of sintering by lattice diffusion. It is also established that low temperatures and CO2 partial pressures promote the coarsening by surface diffusion, whereas high temperatures and CO2 partial pressures favor densification. © 2017 American Institute of Chemical Engineers AIChE J, 63: 3286–3296, 2017

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Effect of water vapor on the pore structure and sulfation of CaO

Cited by 28 publications

References 24 publications

The combined effect of H₂O and SO₂ on the simultaneous calcination/sulfation reaction in CFBs

The combined effect of H₂O and SO₂ on the simultaneous calcination/sulfation reaction in CFBs

Experimental study and parametric analysis of SO₂ capture in limestone fixed bed reactor

On the modeling of the co₂‐catalyzed sintering of calcium oxide

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Effect of water vapor on the pore structure and sulfation of CaO

Cited by 28 publications

References 24 publications

The combined effect of H2O and SO2 on the simultaneous calcination/sulfation reaction in CFBs

The combined effect of H2O and SO2 on the simultaneous calcination/sulfation reaction in CFBs

Experimental study and parametric analysis of SO2 capture in limestone fixed bed reactor

On the modeling of the co2‐catalyzed sintering of calcium oxide

Contact Info

Product

Resources

About

The combined effect of H₂O and SO₂ on the simultaneous calcination/sulfation reaction in CFBs

The combined effect of H₂O and SO₂ on the simultaneous calcination/sulfation reaction in CFBs

Experimental study and parametric analysis of SO₂ capture in limestone fixed bed reactor

On the modeling of the co₂‐catalyzed sintering of calcium oxide