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3 pages, 155 KiB

Open AccessEditorial

Formation, Emission and Control Technology of Particulate Matters during Solid Fuel Combustion

by Chang Wen, Youjian Zhu and Yishu Xu

Atmosphere 2023, 14(1), 122; https://doi.org/10.3390/atmos14010122 - 5 Jan 2023

Cited by 2 | Viewed by 1578

Abstract

The emission of particulate matters during anthropic activities is an environmental pollution and health hazard to countries globally, especially developing ones, which cannot be ignored [...] Full article

(This article belongs to the Special Issue Emissions, Control, and Utilization Technology of Particulate Matters)

Research

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10 pages, 1381 KiB

Open AccessArticle

Emission Characteristics of Gaseous and Particulate Mercury from a Subcritical Power Plant Co-Firing Coal and Sludge

by Changkang Li, Chang Wen, Dapeng Wang, Changxi Zhao and Rui Li

Atmosphere 2022, 13(10), 1656; https://doi.org/10.3390/atmos13101656 - 11 Oct 2022

Cited by 6 | Viewed by 1786

Abstract

Field tests were carried out in a subcritical coal-fired power plant co-firing coal and sludge to analyze the emission characteristics of gaseous and particulate mercury. EPA30B method was applied to determine the mercury speciation in different positions of the flue gas, including the [...] Read more.

Field tests were carried out in a subcritical coal-fired power plant co-firing coal and sludge to analyze the emission characteristics of gaseous and particulate mercury. EPA30B method was applied to determine the mercury speciation in different positions of the flue gas, including the inlet and outlet of the selective catalytic reduction DeNO_X system (SCR) and electrostatic precipitator (ESP); PM₁₀ (with aerodynamic diameter ≤10 μm) was collected using a cyclone and a Dekati low-pressure impactor (DLPI). Before accessing the SCR, Hg in flue gas from both single coal combustion and co-firing mainly existed as Hg⁰; the higher content of Hg in sludge than coal led to the much higher Hg⁰ concentration for co-firing. The total Hg concentration at not only the SCR inlet and outlet but also the ESP inlet did not change obviously. However, Hg_p concentration at the ESP inlet increased significantly, accompanied by a decrease in Hg⁰. The transformation of Hg⁰ to Hg_p appeared to be more distinct for co-firing. The higher HCl concentration of co-firing derived from the much higher Cl content of sludge than coal, and together with the higher ash content of sludge containing more minerals capable of adsorbing Hg⁰, may lead to the greater transformation from Hg⁰ to Hg²⁺ and Hg_p when co-firing. After the ESP disposal, nearly all Hg_p was removed along with PM₁₀, and most Hg⁰ was also removed. The removal efficiency of mercury after the ESP was 92.12% under coal firing and 92.83% under co-firing conditions, respectively. The slightly higher mercury removal efficiency under co-firing should be attributed to the complete removal of the higher concentration of Hg_p. Full article

(This article belongs to the Special Issue Emissions, Control, and Utilization Technology of Particulate Matters)

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12 pages, 1581 KiB

Open AccessArticle

Impacts of Nano SiO₂ Addition on the Formation of Ultrafine Particulate Matter during Coal Combustion

by Huakun Wang, Yishu Xu, Kai Zhang, Baohua Zhang, Shanshan Min, Yimin Liu, Jingji Zhu and Jingjing Ma

Atmosphere 2022, 13(10), 1624; https://doi.org/10.3390/atmos13101624 - 5 Oct 2022

Cited by 3 | Viewed by 1469

Abstract

Clay minerals composed of Si and Al could help reduce ultrafine particulate matter (PM) formation as an additive during coal combustion while currently unacceptable high adding dosages (normally 3–5 wt.%) are required due to their inadequate capture efficiency. To find additives that could [...] Read more.

Clay minerals composed of Si and Al could help reduce ultrafine particulate matter (PM) formation as an additive during coal combustion while currently unacceptable high adding dosages (normally 3–5 wt.%) are required due to their inadequate capture efficiency. To find additives that could effectively reduce the formation of ultrafine PM, coal combustion with a novel nano SiO₂ additive (<100 nm) was performed to evaluate its effects on reducing ultrafine PM. The generated PM₁₀ was sampled to characterize their particle size distribution, mass yield, size-resolved composition and micromorphology. The results showed that adding a small dosage (0.6%) of nano SiO₂ reduced the mass yield of ultrafine PM by 30.70%, showing a much higher ultrafine PM capture efficiency than an existing micron-sized natural clay mineral. However, its performance on different coals varied due to disparities in ash content and composition in coal. A composition analysis revealed that the Na content in the ultrafine PM was decreased after adding nano SiO₂, indicating that nano SiO₂ inhibited the migration of volatile alkali metals such as Na into ultrafine PM because the Na-containing mineral vapor reacted with the nano SiO₂ additive particles with a large specific surface area at a high temperature and inhibited their transformation into ultrafine PM via homogenous nucleation. Changes in the element size distributions and micromorphology showed that the majority of the added nano SiO₂ particles reacted or coalesced with each other and/or the minerals embedded in coal, finally growing into a larger PM. Full article

(This article belongs to the Special Issue Emissions, Control, and Utilization Technology of Particulate Matters)

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15 pages, 1194 KiB

Open AccessArticle

Effect of Densification on Biomass Combustion and Particulate Matter Emission Characteristics

by Wei Yang, Leida Lv, Yong Han, Yu Li, Huihui Liu, Youjian Zhu, Wennan Zhang and Haiping Yang

Atmosphere 2022, 13(10), 1582; https://doi.org/10.3390/atmos13101582 - 28 Sep 2022

Cited by 8 | Viewed by 1888

Abstract

The effect of biomass densification on combustion characteristics and particulate matter (PM) emission was studied in this work by means of thermogravimetric, combustion kinetic, and PM analyses with respect to the size distribution and elementary composition. Cornstalk as a typical agricultural biomass residue [...] Read more.

The effect of biomass densification on combustion characteristics and particulate matter (PM) emission was studied in this work by means of thermogravimetric, combustion kinetic, and PM analyses with respect to the size distribution and elementary composition. Cornstalk as a typical agricultural biomass residue and camphorwood as a woody biomass were used in the experiment for comparison. It can be concluded that the biomass densification increases the ignition, burnout, and composite combustion indexes, leading to a better performance of biomass combustion. The main reaction mechanism of cornstalk pellets can be well-expressed with the chemical reaction series model, whereas the diffusion mechanism and chemical reaction series models can be applied to the combustion of camphorwood pellets. The biomass densification has little effect on the composition of PM but significantly changes the yield of PM. The influence of biomass densification on PM emission is related to the biomass properties. The densification significantly reduces the PM emission for cornstalk but significantly increases the yield of particles of aerodynamic cutoff diameters less than 1μm (PM₁) for camphorwood. Full article

(This article belongs to the Special Issue Emissions, Control, and Utilization Technology of Particulate Matters)

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10 pages, 3897 KiB

Open AccessArticle

Electric Field-Driven Air Purification Filter for High Efficiency Removal of PM_2.5 and SO₂: Local Electric Field Induction and External Electric Field Enhancement

by Jian Li, Qingyun Sun, Zhongxin Ping, Yihong Gao, Peiyu Chen and Fangzhi Huang

Atmosphere 2022, 13(8), 1260; https://doi.org/10.3390/atmos13081260 - 9 Aug 2022

Cited by 3 | Viewed by 2170

Abstract

Removal rate and durability are the two most important parameters of an ideal air purification filter to remove inhalable particles and toxic gases. Here, based on the interaction of a local electric field and an external electric field, a novel coaxial core–shell CuO@NH [...] Read more.

Removal rate and durability are the two most important parameters of an ideal air purification filter to remove inhalable particles and toxic gases. Here, based on the interaction of a local electric field and an external electric field, a novel coaxial core–shell CuO@NH₂-MIL-53(Al) nanowire array was synthesized on a rigid copper net, which was used to remove PM_2.5 and SO₂ simultaneously. The removal rates of PM_2.5 by the filter with and without an external electric field can reach 98.72% and 44.41%, respectively, and the adsorption capacity of SO₂ can reach 4.87 mol/m². After repeated filtration and cleaning for 10 cycles, the air pollution removal efficiency can be kept almost stable. Full article

(This article belongs to the Special Issue Emissions, Control, and Utilization Technology of Particulate Matters)

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14 pages, 3501 KiB

Open AccessArticle

Transformation and Migrant Mechanism of Sulfur and Nitrogen during Chemical Looping Combustion with CuFe₂O₄

by Haichuan Li, Ziheng Han, Chenye Hu, Jingjing Ma and Qingjie Guo

Atmosphere 2022, 13(5), 786; https://doi.org/10.3390/atmos13050786 - 12 May 2022

Cited by 9 | Viewed by 2045

Abstract

Chemical looping combustion (CLC) is a key technology for capturing CO₂. Different types of oxygen carrier (OC) particles are used in coal CLC. The migration and transformation behaviors of sulfur and nitrogen are basically the same when CaFe₂O₄ [...] Read more.

Chemical looping combustion (CLC) is a key technology for capturing CO₂. Different types of oxygen carrier (OC) particles are used in coal CLC. The migration and transformation behaviors of sulfur and nitrogen are basically the same when CaFe₂O₄ and Fe₂O₃/Al₂O₃ are used as OC. CLC can be divided into two reaction stages: coal pyrolysis and char gasification; SO₂ and NO show bimodal release characteristics, both of which show a basic trend of rising first and then falling down. The contents of H₂S and NO₂ increased rapidly at the beginning of the reaction and then decreased slowly at the stage of char gasification. H₂S is released rapidly during coal pyrolysis and discharged from the reactor with flue gas, and then part of H₂S is converted to SO₂ during the char gasification stage by OC particles. NO can be oxidized by OC particles and form NO₂. The increase in the reaction temperature and oxygen-to-carbon ratio (O/C) contributes to the release of sulfur and nitrogen and higher reaction temperature and O/C can inhibit the formation of metal sulfide. O₂ released by CuFe₂O₄ significantly increases the contents of SO₂, H₂S, NO and NO₂ in flue gas. This work is helpful for improving control strategies for pollutants. Full article

(This article belongs to the Special Issue Emissions, Control, and Utilization Technology of Particulate Matters)

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14 pages, 3214 KiB

Open AccessFeature PaperArticle

The Influence of Pore Distribution of Coal Char in the Char Fragmentation and Included Minerals Partitioning: A Percolation Modeling

by Rui Li, Zhenqi Jing, Jingjing Ma, Long Qin, Kai Yan and Chang Wen

Atmosphere 2022, 13(4), 628; https://doi.org/10.3390/atmos13040628 - 15 Apr 2022

Cited by 7 | Viewed by 1760

Abstract

The processes of char fragmentation, including mineral partitioning and particulate matter (PM) formation during dense and porous char combustion, were observed by a site percolation model. This model simulated the diffusion-controlled regime of char combustion, and the size distributions of included minerals in [...] Read more.

The processes of char fragmentation, including mineral partitioning and particulate matter (PM) formation during dense and porous char combustion, were observed by a site percolation model. This model simulated the diffusion-controlled regime of char combustion, and the size distributions of included minerals in typical bituminous coal were determined by the computer-controlled scanning electron microscope (CCSEM), and the data were put into the char matrix randomly. The model presents the influence of initial pore distribution on char oxidation and fragmentation, the impact of the char conversion process on the extent of fragmentation, the change of ash distributions with the char conversion, and the particulate matters (PM) size distribution, which is derived from the consequence of the competition between char fragmentation and included minerals partitioning and coalescence. The results indicate that with increasing initial char porosity (φ), the number of large size pores increases but the number of pores decreases, which leads to open pores increasing, close pores decreasing, and the surface reaction area increasing. While φ ≥ 0.4, char fragmentation obviously occurs during the stage in which the rates of char conversion are 0.4–0.6, and it looks as though the maximum value of fragmentation will transfer to an earlier conversion stage if it has a larger φ. The enhanced φ shows a positive effect on the increase in the number and concentration of PM < 10 μm (nominally aerodynamic diameter), this is attributed to char fragments more drastically, and the probability of mineral coalescence reduces a lot. Full article

(This article belongs to the Special Issue Emissions, Control, and Utilization Technology of Particulate Matters)

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12 pages, 2456 KiB

Open AccessArticle

Study of the Treatment of Organic Waste Gas Containing Benzene by a Low Temperature Plasma-Biological Degradation Method

by Yu Li, Jialin Lv, Qi Xu, Yalan Cai, Hailong Yang, Yingying Li, Yanyan Yao, Wenjuan Wang and Nan Liu

Atmosphere 2022, 13(4), 622; https://doi.org/10.3390/atmos13040622 - 13 Apr 2022

Cited by 2 | Viewed by 2377

Abstract

Volatile organic compounds (VOCs) from the pharmaceutical and chemical industries have been a matter of concern for some years in China. Achieving efficient degradation of chlorobenzene (CB) in waste gas is difficult because of its high volatility and molecular stability. A DBD (dielectric [...] Read more.

Volatile organic compounds (VOCs) from the pharmaceutical and chemical industries have been a matter of concern for some years in China. Achieving efficient degradation of chlorobenzene (CB) in waste gas is difficult because of its high volatility and molecular stability. A DBD (dielectric barrier discharge) biological method was proposed to treat chlorobenzene, aiming to control high operating costs and prevent secondary pollution. In this investigation, a DBD biological method was introduced to deal with chlorobenzene by optimization of process parameters. The results showed that the degradation efficiency of chlorobenzene was close to 80% at a hydraulic retention time (HRT) of 85 s when the inlet concentration was 700 mg·m⁻³ for the biological method. The degradation efficiency of chlorobenzene reached 80% under a discharge voltage of 7 kV, an inlet concentration of 700 mg·m⁻³ and an HRT of 5.5 s. The degradation efficiency of an integrated system can be increased by 15–20% compared with that of a single biological system. Therefore, this method can be used as a new way to address chlorobenzene pollution in the pharmaceutical and chemical industries. Full article

(This article belongs to the Special Issue Emissions, Control, and Utilization Technology of Particulate Matters)

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14 pages, 4468 KiB

Open AccessArticle

Behavior of Selenium during Chemical-Looping Gasification of Coal Using Copper-Based Oxygen Carrier

by Jingjing Ma, Jiameng Hu, Huifen Kang, Ziheng Han and Qingjie Guo

Atmosphere 2022, 13(4), 547; https://doi.org/10.3390/atmos13040547 - 29 Mar 2022

Cited by 3 | Viewed by 1892

Abstract

The migration and transformation behavior of selenium during coal chemical looping gasification (CLG) under the impact of a CuO/Bentonite (Ben) oxygen carrier (OC) were studied in a batch fluidized bed reactor. In the CLG process, the total percentage of selenium released in gaseous [...] Read more.

The migration and transformation behavior of selenium during coal chemical looping gasification (CLG) under the impact of a CuO/Bentonite (Ben) oxygen carrier (OC) were studied in a batch fluidized bed reactor. In the CLG process, the total percentage of selenium released in gaseous phase was 73.06%. In the conventional gasification process, 91.71% of the total selenium was released in a gaseous state. The addition of CuO/Ben OC apparently promoted the transformation from gaseous selenium to particulate selenium. The oxygen–carbon ratio (O/C) played an important role in affecting the fraction of gaseous selenium released in the gasification process, with results showing that the amount of selenium adsorbed by CuO/Ben OC was added along with the increase in OC. By means of X-ray photoelectron spectroscopy (XPS) characterization, we found that the reduced CuO/Ben OC contained a small amount of Cu₂Se due to the oxidation and adsorption of selenium onto their porous surface. The regeneration performance of the CuO/Ben OC was favorable after 10 regeneration cycles of the CLG process. The increase in the pore volumes and specific surface areas contributed to the enhanced capacity of retaining selenium for CuO/Ben OC. Full article

(This article belongs to the Special Issue Emissions, Control, and Utilization Technology of Particulate Matters)

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