Sulfur Capture by Fly Ash in Air and Oxy-fuel Pulverized Fuel Combustion

Belo, Lawrence P.; Spörl, Reinhold; Shah, Kalpit; Elliott, Liza; Stanger, Rohan; Maier, Jörg; Wall, Terry

doi:10.1021/ef500855w

Cited by 23 publications

(23 citation statements)

References 25 publications

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“…Not all sulfur released during the combustion of coal is captured in these units, as part of it is mitigated due to retention on fly ash particles of which Ca can constitute up to 40% [5][6][7][8]. In fact, fly ash with greater weight fractions of Ca or other alkali and alkaline earth metal oxides yields reduced SO x emissions through greater sulfur retention [9][10][11][12][13][14][15][16]. It is this beneficial impact of the fly ash that has attempts to capture and re-purpose spent fly ash as a cost effective sorbent for sulfur emissions [17,18].…”

Section: Introductionmentioning

confidence: 99%

Effect of flue gas components on the adsorption of sulfur oxides on CaO(1 0 0)

Galloway

Padak

2017

Fuel

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Due to the prevalence of coal combustion technologies utilizing calcium-based materials, it is important to understand the varied reactions between the flue gas species and these calciumbased materials. Of particular importance is the reaction between sulfur oxides (SO 2 or SO 3) and calcium oxide (CaO), which plays an important role in sulfur retention on fly ash during oxycoal combustion or carbon capture with calcium looping. To better understand these reactions, density functional theory (DFT) calculations were performed investigating SO x binding to CaO surfaces functionalized by other flue gas components. Analyses of the energetic, geometric and electronic nature of the modeled systems were conducted. Generally, the most stable conformation on the surface is in the form of either a sulfite-or sulfate-like structure. Water can have an effect on sulfur binding by introducing other favorable intermediate conformations, while carbon dioxide could negatively impact adsorption by weakening sulfur-surface bonds.

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Section: Introductionmentioning

confidence: 99%

Effect of flue gas components on the adsorption of sulfur oxides on CaO(1 0 0)

Galloway

Padak

2017

Fuel

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“…Belo et al 8 discussed in a previous paper the reaction routes of sulfur in a combustion system. SO 2 is formed from the decomposition and oxidation of organic and inorganic sulfur associated in the coal matrix.…”

Section: Introductionmentioning

confidence: 99%

High-Temperature Conversion of SO₂ to SO₃: Homogeneous Experiments and Catalytic Effect of Fly Ash from Air and Oxy-fuel Firing

et al. 2014

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The reaction of SO 2 with fly ash in the presence of O 2 and H 2 O involves a series of reactions that lead to the formation of SO 3 and eventually H 2 SO 4 . Homogeneous experiments were conducted to evaluate the effects of the procedural variables, i.e., temperature, gas concentrations, and residence time, on the post-combustion conversion of SO 2 to SO 3 . The results were compared to existing global kinetics and found to be dependent upon SO 2 , O 2 , residence time, and temperature and independent of H 2 O content. For a residence time of 1 s, temperatures of about 900°C are needed to have an observable conversion of SO 2 to SO 3 . Literature suggested that the conversion of SO 2 to SO 3 is dependent upon the iron oxide content of the fly ash. Experiments using three different fly ash samples from Australian sub-bituminous coals were used to investigate the catalytic effects of fly ash on SO 2 conversion to SO 3 at a temperature range of 400−1000°C. It was observed that fly ash acts as a catalyst in the formation of SO 3 , with the largest conversion occurring at 700°C. A homogeneous reaction at 700°C, without fly ash present, converted 0.10% of the available SO 2 to SO 3 . When fly ash was present, the conversion increased to 1.78%. The catalytic effect accounts for roughly 95% of the total conversion. Average SO 3 /SO 2 conversion values between fly ash derived from air and oxy-fuel firing and under different flue gas environments were found to be similar.

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“…Sulfur dioxide (SO 2 ) is one of the main gaseous pollutants that is emitted by a coal-fired power plant . SO 2 is the cause of many environmental problems, such as acid rain and adverse effects to human health.…”

Section: Introductionmentioning

confidence: 99%

“…Sulfur dioxide (SO 2 ) is one of the main gaseous pollutants that is emitted by a coal-fired power plant. 1 SO 2 is the cause of many environmental problems, such as acid rain and adverse effects to human health. SO 2 is also considered to be an important precursor for secondary PM2.5 formation in the atmosphere.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on In Situ Preparation of Supported Sorbent for Moderate Temperature CFB-FGD

2018

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Supported sorbent for flue gas desulfurization was prepared by a process of hydrating and drying a mixture of carrier particles and lumps of CaO in previous studies. Supported sorbent achieves high desulfurization efficiency in a Circulating Fluidized Bed (CFB) reactor at moderate temperature. However, the preparation process is complicated, which makes industrial application difficult. In this study, supported sorbent is prepared in situ in a CFB reactor by a coating process, in combination with SO2 removal. The experiments are conducted in a pilot-scale CFB experimental facility at 700–750 °C. The influence of operation parameters on supported sorbent formation and desulfurization efficiency is tested, including bed inventory, sprayer location, and spray method. The results show that the present process achieves 85.3% desulfurization efficiency with a Ca/S molar ratio of 2.01 when the bed inventory is 25 kg. This result is approximately 10 times higher than that of a zero bed inventory. The scanning electron microscope and energy dispersive spectrometer results show that the supported sorbent forms when fine Ca(OH)2 particles in the lime slurry adhere to the bed material surface. The residence time of the supported sorbent in the CFB reactor is significantly longer than that of the fine Ca(OH)2 particles. The adhesion efficiency is influenced by the spray location and spray method. The desulfurization performance of the supported sorbent prepared by the original hydration and drying method is also tested. The desulfurization efficiency is 25–35% higher than the present process because there is better adhesion in the original method than the in situ method. But the process complexity is significantly reduced when using the present process. The present process is a substantial attempt toward the application of supported sorbent.

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Sulfur Capture by Fly Ash in Air and Oxy-fuel Pulverized Fuel Combustion

Cited by 23 publications

References 25 publications

Effect of flue gas components on the adsorption of sulfur oxides on CaO(1 0 0)

Effect of flue gas components on the adsorption of sulfur oxides on CaO(1 0 0)

High-Temperature Conversion of SO₂ to SO₃: Homogeneous Experiments and Catalytic Effect of Fly Ash from Air and Oxy-fuel Firing

Experimental Study on In Situ Preparation of Supported Sorbent for Moderate Temperature CFB-FGD

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Sulfur Capture by Fly Ash in Air and Oxy-fuel Pulverized Fuel Combustion

Cited by 23 publications

References 25 publications

Effect of flue gas components on the adsorption of sulfur oxides on CaO(1 0 0)

Effect of flue gas components on the adsorption of sulfur oxides on CaO(1 0 0)

High-Temperature Conversion of SO2 to SO3: Homogeneous Experiments and Catalytic Effect of Fly Ash from Air and Oxy-fuel Firing

Experimental Study on In Situ Preparation of Supported Sorbent for Moderate Temperature CFB-FGD

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High-Temperature Conversion of SO₂ to SO₃: Homogeneous Experiments and Catalytic Effect of Fly Ash from Air and Oxy-fuel Firing