Investigation of subbituminous coal and lignite combustion processes in terms of mercury and arsenic removal

Marczak, Marta; Wierońska, Faustyna; Burmistrz, Piotr; Strugała, A.; Kogut, Krzysztof; Lech, Sebastian

doi:10.1016/j.fuel.2019.04.082

Cited by 27 publications

(10 citation statements)

References 27 publications

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“…Among the all materials, Fe 2 O 3 , Mg(OH) 2 , Ca(OH) 2 , Lp, and Dp seemed to be the most effective (% RE: 85−98%), which is comparable to activated carbon. 23 Dolomite, limestone, and gypsum were characterized by a lower removal efficiency averaging ∼62%.…”

Section: Resultsmentioning

confidence: 99%

“…As the flue gas temperature decreased to 120 °C, part of the As gas condensed on the quartz retort, significantly reducing the amount of As in the flue gas directly before the sorbent bed. The installation is described in more detail in an earlier publication . Depending on the removal efficiency of the tested material, As gas would adsorb on its surface or sorb in solutions (in impingers) located behind the sorbent bed.…”

Section: Applied Analytical Methodsmentioning

confidence: 99%

“…The installation is described in more detail in an earlier publication. 23 Depending on the removal efficiency of the tested material, As gas would adsorb on its surface or sorb in solutions (in impingers) located behind the sorbent bed. According to US EPA Method 29, 24 each of the impingers contained 100 mL of a mixture of 5% nitric acid (V) and 10% hydrogen peroxide.…”

Section: Introductionmentioning

confidence: 99%

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Assessment of the Applicability of Ca-Based Sorbents for Arsenic Removal from Flue Gases

2022

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Arsenic is one of the most hazardous compounds released into the atmosphere from coal conversion processes. One possibility to limit its amount in the flue gas is to inject dusty sorbents directly into the flue gas duct. The aim of this study was to analyze the removal efficiency of gaseous forms of As on selected Ca-based materials, with a focus on sorbents based on waste materials versus traditionally used sorbents. Coal combustion byproducts, waste (such as filter cake, fly ash, and gypsum), sedimentary rocks (dolomite and limestone), and chemical reagents like Ca(OH)2, Fe2O3, and Mg(OH)2 were examined in the quartz retort in a heated furnace where the temperature of the sorbent bed was 120 °C. The source of Asgas was the direct combustion of coal at 1200 °C. Among the tested materials, calcined limestone, calcined dolomite, Fe2O3, Mg(OH)2, and Ca(OH)2 were the most effective (removal efficiency: 85–98%). In the case of waste materials, the highest efficiency was obtained for filter cakes. However, because of their high content of toxic elements, they could be used as sorbent only after thermal preparation at 250 °C. Furthermore, the analyses showed that an increased Ca concentration in the sorbent may promote Asgas adsorption more than the development of the sorption surface area.

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Section: Resultsmentioning

confidence: 99%

Section: Applied Analytical Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Assessment of the Applicability of Ca-Based Sorbents for Arsenic Removal from Flue Gases

2022

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“…The semicoke masses are 5 g in T1 and T2. The existing studies showed that during the semicoke combustion, the residual binding mercury and oxygen have a violent REDOX reaction, and mercury escapes into the gas phase generated by combustion in the form of Hg 0 and Hg 2+ . In the presence of CFB ash during combustion, the calculation results of mercury balance show that 50% of Hg 0 will react with Fe 2 O 3 and CaO in the CFB ash and convert to Hg 2+ .…”

Section: Results and Discussionmentioning

confidence: 99%

Influence of Solid Heat Carriers on Mercury Migration Characteristics in Coal Pyrolysis/Circulating Fluidized Bed Combustion-Staged Conversion Process

Zhang

Wang

et al. 2021

Energy Fuels

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The migration of mercury pollutants is an inevitable problem in the coal pyrolysis/circulating fluidized bed (CFB) combustion-staged conversion process. To explore the influence of circulating ash on the occurrence and migration of mercury in a staged process, two-stage mercury removal experiments were conducted in a fixed-bed reactor with high-mercury coal. The effects of ash-to-coal ratio, ash particle size, metal oxides in ash, and ash–coal placement types on mercury in coal pyrolysis gas, liquid, and solid products were investigated. The results showed that mercury in coal pyrolysis volatiles mainly escapes in the form of Hg0 and Hg2+, and Hg0 is the main form of mercury in the volatiles. Fe2O3, CaO, and MgO in circulating ash reacted with Hg0 in coal pyrolysis volatiles at a high temperature to oxidize Hg0 to Hg2+. Larger ash-to-coal ratio and smaller ash particle size could significantly increase the conversion efficiency of Hg0 to Hg2+. When ash and coal were mixed, the oxidation rate of Hg0 during coal pyrolysis was significantly better than that in the layered pyrolysis of ash and coal. Temperature was the most important factor affecting Hg0 escape during coal pyrolysis. The combustion experiments of pyrolysis semicoke showed that the mercury in semicoke and tar completely escaped in the form of Hg0. This study provides a reference for the purification of mercury-containing pollutants in the pyrolysis and combustion-staged conversion process.

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“…Arsenic (As), a semivolatile trace element, has attracted worldwide attention because of its toxicity, persistence, and bioaccumulation. − Arsenic mainly exists in nature in the form of coal and metal sulfides, and coal-fired power plants are considered to be one of the main anthropogenic emission sources of arsenic. During the process of coal combustion, arsenic evaporates and its main speciation in flue gas is As 3+ vapor (As 2 O 3 (g)). , However, just an insignificant part of arsenic may react with fly ash particles to be eventually solidified, while most arsenic tends to be concentrated in sub-micron fine particles such that it becomes difficult to capture arsenic by electrostatic precipitators (ESPs), bag filters, and other existing air pollution control devices (APCDs) at the power plants. − Arsenic spreads in the atmosphere after emission, causing irreversible harm to the ecological environment and health.…”

Section: Introductionmentioning

confidence: 99%

Microscopic Spherical α-Fe₂O₃ for Highly Efficient Gaseous Arsenic Capture in Simulated Flue Gas Under a Wide Temperature Range

et al. 2021

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Arsenic emitted from coal-fired flue gas poses a threat to human health and the ecological environment due to its high toxicity and bioaccumulation. In this work, the microscopic spherical α-Fe2O3 sorbent was prepared by a one-step hydrothermal method to effectively capture arsenic in the flue gas. The effects of reaction temperature, sulfur dioxide (SO2), nitric oxide (NO), oxygen (O2), and inlet arsenic concentration on its adsorption performance were investigated. The results showed that the most suitable adsorption temperature was 600 °C, and As2O3(g) was finally fixed in the product in the form of FeAsO4. SO2 and O2 played a positive role in the adsorption of arsenic, while NO displayed a slight effect on the adsorption of arsenic. In addition, the arsenic adsorption capacity improved with the increase of the inlet arsenic concentration. Based on its excellent arsenic removal performance and SO2 resistance performance, the α-Fe2O3 sorbent can be considered a promising material for arsenic removal.

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Investigation of subbituminous coal and lignite combustion processes in terms of mercury and arsenic removal

Cited by 27 publications

References 27 publications

Assessment of the Applicability of Ca-Based Sorbents for Arsenic Removal from Flue Gases

Assessment of the Applicability of Ca-Based Sorbents for Arsenic Removal from Flue Gases

Influence of Solid Heat Carriers on Mercury Migration Characteristics in Coal Pyrolysis/Circulating Fluidized Bed Combustion-Staged Conversion Process

Microscopic Spherical α-Fe₂O₃ for Highly Efficient Gaseous Arsenic Capture in Simulated Flue Gas Under a Wide Temperature Range

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Investigation of subbituminous coal and lignite combustion processes in terms of mercury and arsenic removal

Cited by 27 publications

References 27 publications

Assessment of the Applicability of Ca-Based Sorbents for Arsenic Removal from Flue Gases

Assessment of the Applicability of Ca-Based Sorbents for Arsenic Removal from Flue Gases

Influence of Solid Heat Carriers on Mercury Migration Characteristics in Coal Pyrolysis/Circulating Fluidized Bed Combustion-Staged Conversion Process

Microscopic Spherical α-Fe2O3 for Highly Efficient Gaseous Arsenic Capture in Simulated Flue Gas Under a Wide Temperature Range

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Product

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Microscopic Spherical α-Fe₂O₃ for Highly Efficient Gaseous Arsenic Capture in Simulated Flue Gas Under a Wide Temperature Range