Search Results (31)

Natural gas purification and the mitigation of carbon dioxide (CO₂) emissions from flue gases are critical steps in alleviating the greenhouse effect and significantly mitigate multiple environmental challenges associated with global warming. Hypercrosslinked polymers (HCPs) have become a hot topic as prospective adsorbents for gas purification and separation, owing to their low cost and scalability. Hence, TPB-Ben, TPB-Nap, and TPB-Ant were synthesized through a solvent knitting strategy, with the modification in the size of the monomers serving as a distinctive feature. This alteration aimed to explore the impact of phenyl ring quantity on the polymers’ gas adsorption and separation efficiency. All HCPs showed outstanding selective separation capability of CO₂ from CO₂/CH₄ and CO₂/N₂ mixtures, such as TPB-Ben-3-2 (CO₂/CH₄: 10.77; CO₂/N₂: 59.72), TPB-Nap-3-2 (CO₂/CH₄: 9.12; CO₂/N₂: 61.31), and TPB-Ant-3-2 (CO₂/CH₄: 10.00; CO₂/N₂: 62.89), which could be potential candidate adsorbents for natural gas purification and CO₂ capture. Considering the mild reaction conditions, low cost, efficient gas adsorption, and the potential for scalable production, these polymers are considered ideal selective solid adsorbents for capturing CO₂. This further highlights the significance of the solvent knitting strategy. Full article

To enhance the efficiency of flue gas purification from straw combustion, a combined approach using the ammonia method and electrostatic charged spray was investigated. This study investigated the charging characteristics of atomized droplets and their impact on flue gas purification. The results show that the charge-to-mass ratio of droplets increases and then decreases as charging voltages increase. At a constant voltage, the ratio increases with higher ammonia concentrations and shows a gradual increase with higher spray pressures. For flue gases from three common straw combustion sources, the average dust removal rate at 8 kV was 2.5 to 3 times higher than at 0 kV. Under the 8 kV condition with a 10% ammonia solution, the NO removal rate was approximately 4.7 times, and the NO₂ removal rate was 2.8 times compared to water alone. Particulate matter, NO, and NO₂ removal rates were 61.2%, 88.6%, and 88.1%, respectively, at a spray pressure of 0.5 MPa, 8 kV charging voltage, and 10% ammonia concentration. This study provides an experimental foundation for developing high-efficiency flue gas purification systems for straw combustion. Full article

SO₂ and NO_x emissions from iron and steel production pollute the atmosphere. With the implementation of ultra-low emission standards, the requirements for flue gas purification have become more stringent. Activated carbon, due to its rich surface chemistry, stable physical structure, and excellent adsorption and renewability, has a significant effect on the synergistic removal of multiple pollutants from industrial flue gas, and its industrial application has achieved a SO₂ removal rate of ≥98% and a NO_x removal rate of ≥83%. Firstly, we analyze the structure of activated carbon and the adsorption principle, discuss the mechanism of desulfurization and denitrification, and explore the shortcomings of the technology; then, we summarize the modification methods of activated carbon, determine the impregnation method of loading non-precious metal oxides as the optimal solution, and elucidate the loading conditions, process, and reaction mechanism; finally, we discuss the current status of the research, analyze the process deficiencies and the direction of optimization, and look forward to the prospect of development. Full article

Rhenium metal is extensively utilized in the aerospace industry for the manufacturing of various superalloys due to its unique properties, and plays an indispensable role in the field of high technology. Rhenium resources are primarily associated with copper, molybdenum, and other metal ores. Ammonium perrhenate is predominantly derived from copper and molybdenum ore roasting flue gas scrubbers containing various impurities in the rhenium-containing contaminated acid. The complex composition of the contaminated acid renders the enrichment and purification of ammonium perrhenate more challenging, necessitating further research and development of the technology. This paper reviews the research progress in ammonium perrhenate enrichment and purification technology, encompassing chemical precipitation, adsorption, extraction, ion exchange, extraction chromatography, and recrystallization. It analyses the advantages and limitations of various methods, with the aim of providing a reference for future developments in ammonium perrhenate enrichment and purification technology. Furthermore, the paper presents a prospective view on the development of ammonium perrhenate enrichment and purification technology, focusing on the objective of obtaining more selective purification materials and more efficient purification techniques for ammonium perrhenate. Full article

Carbon materials have been employed in many applications in flue gas purification due to their high specific surface area, good chemical inertness, and tunable surface chemistry. However, traditional methods such as adsorption or metal-loaded catalysis can be financially burdensome. The surface of carbon materials contains abundant vacancies, interstitial atoms, boundaries, and other defects. These structural defects are often modified with saturated or unsaturated functional groups containing heteroatoms such as oxygen, nitrogen, etc., thus possessing a certain acid–base property and redox ability, which makes the carbon materials themselves have some catalytic activity. The metal-free carbon catalytic purification of flue gas pollutants offers a promising solution to improve removal efficiency while reducing costs significantly. This review examines the research on carbon materials for the removal of flue gas pollutants, presenting recent advancements in carbon catalysis purification of NO_x, SO₂, and VOCs. It analyzes the critical properties of carbon materials that govern carbon catalytic efficiency, such as surface functional groups, surface defects, and pore structure. Finally, it summarizes methods for regulating these properties to achieve higher efficiencies in the metal-free carbon-catalyzed purification of flue gas pollutants. Full article

This research presents the impact of diesel blends with tire pyrolysis oil (TPO) as an additive for minimizing the wear and tear of engine components. This study investigates the blends of normative diesel oil with TPO content ranging from 5% m/m to 20% m/m. Reference measurements are made for pure diesel oil (D100) and pure TPO. This investigation included an evaluation of the corrosion effect and the effect of the fuels tested on abrasive wear. For each fuel, the sulfur content, water content, lubricity (which is defined as the corrected average diameter of the wear trace during the high-frequency reciprocating rig (HFRR) test), and impurity content are determined. Impurities are assessed using indicators such as ash residue, coking residue from 10% distillation residue, determination of wear metals and contaminants, insoluble impurity content, and total sediment by hot filtration. All parameters are determined using recognized methods described in international standards. Approximation models are built for all the analyzed parameters, which can be used in future studies. At the same time, the individual values of the analyzed factors are compared with the threshold values specified in selected standards and regulations. Consequently, it is possible to assess the usefulness of individual fuels in terms of meeting the requirements for minimum wear of engine components. The results show the suitability of pyrolysis oil and the potential for its use as an additive to fossil fuels in terms of meeting most factors. Some of the fuels tested did not meet the standards for acceptable sulfur content. However, in terms of sulfur content, all of the analyzed fuels can be used to power watercraft and land-based power and thermal power plants equipped with flue gas desulphurization systems. A second indicator for not meeting the standards is the ash residue value, which indicates the high content of non-combustible, mainly metallic, substances in the pyrolysis oil used for the tests. Post-recycled oils must, therefore, undergo appropriate purification before being used as an additive to diesel fuels for internal combustion engines. Once the post-recycling oil has been subjected to desulfurization and advanced filtration, it can be used as a fuel additive for land vehicles, which fits in with closed-loop economies and sustainable development strategies. Full article

The modeling of a mixer used for mixing ammonia and flue gasses is considered. Simulations were performed using Flow Vision 3.14 (TESIS LLC). As a result of the simulation, the distribution of concentrations along the mixer length was obtained at 50%, 65%, 85%, and full flue gas loading. It was found that operations at 100% and 85% gas loads are accompanied by an acceptable distribution of ammonia in the mixer volume (Cov = 0.05). The development and creation of an experimental model in real production was carried out according to the results of the numerical simulation. The simulation results were compared with experimental data on the speed and concentration of ammonia in the control section. The discrepancy, in general, did not exceed 15%. The developed mixer corresponds to modern developments in terms of mixing quality but is simpler in design and more compact. Full article

The high-temperature roasting/smelting process of copper and zinc concentrates will cause the mercury in the concentrate to evaporate into the flue gas, and most of the mercury in the flue gas will eventually enter the waste acid in its ionic form. A highly efficient mercury removal agent M201 with long carbon chains and loaded active functional groups can adsorb and disperse fine particles for mercury removal in the system. Through bridging, the linear structure is woven into a network to achieve large-scale capture and dispersion of fine particles and colloidal substances. The recommended operating conditions for developing mercury deep purification technology are as follows: M201 reagent concentration of 50 g/L, 6 mL/L added acid solution, room temperature, mixing time of 5 min, air flotation time of 10 min, ventilation rate of 0.1 L/min, H₂SO₄ concentration of 33.67 g/L, and the residual mercury content of 2 mg/L (the mercury content reaches 0.01 mg/L after two-stage mercury removal treatment). Meanwhile, the residual arsenic content is 21.9 mg/L. This study shows a better separation of arsenic and mercury and achieves one-step mercury removal. Full article

This study aims to advance the recycling of mercury-containing waste and promote sustainable development within the polyvinyl chloride (PVC) industry. Our innovative system integrates pre-treatment technology (spraying potassium permanganate and demisting and dust removal) with efficient non-thermal plasma oxidation, resulting in excellent treatment efficiency, low cost, and simple operation. With a processing capacity of 3000 m³/h, the concentration of mercury emissions in flue gas can achieve the target of <0.01 mg/m³, boasting a removal efficiency exceeding 98%, which satisfies the standard “Emission standard of air pollutants for industrial kiln and furnace” (GB 9078-1996). Our results can provide technical support for the comprehensive purification of mercury-containing flue gas during the resource recovery process from mercury-containing waste. The application of our system can contribute to reducing mercury emissions in the PVC industry, lowering occupational exposure risks for workers, and promoting China’s better compliance with “the Minamata Convention on Mercury”. Full article

The cement industry is regarded as one of the primary producers of world carbon emissions; hence, lowering its carbon emissions is vital for fostering the development of a low-carbon economy. Carbon capture, utilization, and storage (CCUS) technologies play significant roles in sectors dominated by fossil energy. This study aimed to address issues such as high exhaust gas volume, low CO₂ concentration, high pollutant content, and difficulty in carbon capture during cement production by combining traditional cement production processes with cryogenic air separation technology and CO₂ purification and compression technology. Aspen Plus^® was used to create the production model in its entirety, and a sensitivity analysis was conducted on pertinent production parameters. The findings demonstrate that linking the oxygen-enriched combustion process with the cement manufacturing process may decrease the exhaust gas flow by 54.62%, raise the CO₂ mass fraction to 94.83%, cut coal usage by 30%, and considerably enhance energy utilization efficiency. An exergy analysis showed that the exergy efficiency of the complete kiln system was risen by 17.56% compared to typical manufacturing procedures. However, the cryogenic air separation system had a relatively low exergy efficiency in the subsidiary subsystems, while the clinker cooling system and flue gas circulation system suffered significant exergy efficiency losses. The rotary kiln system, which is the main source of the exergy losses, also had low exergy efficiency in the traditional production process. Full article

There are many technologies for removal of sulfur dioxide (SO₂) from flue gases. They are intrinsic part of the efforts for sustainability of energy production as they reduce the harmful impact of fossil fuel combustion on the environment by minimizing one of the main air pollutants. A wide range of methods use alkaline absorbents. In most cases, the products obtained from the absorption process have to undergo further oxidation, which increases the cost of carrying out the process. As a final result, the sulfates obtained (Na₂SO₄ and CaSO₄) have limited practical application and there is a problem with their disposal. Scientific and engineering efforts have been directed towards the development of a practically waste-free technology for gas purification from SO₂. An absorption–adsorption method is proposed, which comprises absorption of SO₂ in water with simultaneous adsorption of the resultant sulfurous acid (H₂SO₃) from the aqueous solution with a synthetic anion-exchange resin. Regeneration of the adsorbent is accomplished with a dilute solution of ammonia (NH₃), followed by decomposition of the resulting ammonium sulfite ((NH₄)₂SO₃) with nitric acid (HNO₃). The products of the processes are pure gaseous (liquefied) SO₂ and an aqueous solution of ammonium nitrate (NH₄NO₃). Sulfur dioxide has a wide range of applications in the chemical industry; ammonium nitrate is a product with a variety of commercial uses as well, the most common of which is as a soil fertilizer. The new absorption–adsorption method offers a practically waste-free technology. The basic unit of this technology is a bubble-cap tray column where the absorption–adsorption process is carried out in an aqueous suspension of a synthetic anion-exchange resin. This work presents a CFD simulation of the flow on the bubble-cap tray. A physical model of the column is constructed, which contains a bubble-cap tray fabricated by 3D printing. As a result of this experimental study, new data on the tray pressure drop, gas holdup, and the kinetics of the absorption–adsorption process were obtained. Full article

This article presents the official results of the inventory of pollutants in Poland from road transport, developed in the National Centre for Emissions Management of the Institute of Environmental Protection–National Research Institute in Warsaw as part of the reporting of national pollutant emissions. Considerations concern pollutants harmful to the health of living organisms. Source information is available in official reports. The national emission of pollutants covers the years of balancing 1990–2020. The aim of the work is to assess the dynamic properties of the processes of national emission of pollutants. The list of substances whose emission is examined in the article is consistent with the list of substances in accordance with the European Monitoring and Evaluation Programme/European Environment Agency (EMEP/EEA) procedure. These are pollutants harmful to the health of living organisms. The inventory of pollutants contributing to the intensification of the greenhouse effect in the atmosphere is carried out as part of separate reports. The energy consumption of road vehicles was presented. The ratio of national annual emissions of pollutants in 2020 and in 1990 is the lowest for sulfur oxides and lead, followed by non-methane volatile organic compounds and carbon monoxide. The analysis of the national pollutant emission concerned the energy emission factor, which characterizes the ecological level of the accumulated category of road vehicles. This is an original element, not seen before in world literature and official reports of research institutes. An unambiguous trend of decreasing the energy emission factor of pollutants, apart from ammonia, was found, which is related to the use of catalytic flue gas purification systems. This is confirmed by the analysis of the ratio of the energy emission factor in 2020 and 1990, as well as the relative derivative of the energy emission factor in relation to the national annual emission of pollutants. Full article

In order to study the dynamic characteristics of the 660 MW ultra-supercritical circulating fluidized bed (CFB) boiler when the main fuel trip (MFT) and boiler trip (BT) are triggered, a dynamic simulation model of the 660 MW ultra-supercritical circulating fluidized bed boiler was established on the Apros simulation platform. The model dynamically simulated the MFT and BT processes at 100% BMCR, 75% THA, and 50% THA conditions, respectively. The steady-state simulation results showed a high accuracy compared with the designed parameters. The dynamic simulation results showed that after triggering the MFT and BT, owing to the huge thermal inertia, the bed temperature and steam temperature decreased lowly. For 100% BMCR and 75% THA conditions, the moisture separator always worked in dry state during the MFT and BT processes. For the 50% THA condition, the moisture separator quickly switched from dry to wet operation after the boiler triggers MFT and BT and gradually switched from wet to dry operation after MFT and BT were reset. Full article

Nitrogen oxide (NOx) is a major gaseous pollutant in flue gases from power plants, industrial processes, and waste incineration that can have adverse impacts on the environment and human health. Many denitrification (de-NOx) technologies have been developed to reduce NOx emissions in the past several decades. This paper provides a review of the recent literature on NOx post-combustion purification methods with different reagents. From the perspective of changes in the valence of nitrogen (N), purification technologies against NOx in flue gas are classified into three approaches: oxidation, reduction, and adsorption/absorption. The removal processes, mechanisms, and influencing factors of each method are systematically reviewed. In addition, the main challenges and potential breakthroughs of each method are discussed in detail and possible directions for future research activities are proposed. This review provides a fundamental and systematic understanding of the mechanisms of denitrification from flue gas and can help researchers select high-performance and cost-effective methods. Full article

To combat global warming, as an energy-saving technology, membrane separation can be applied to capture CO₂ from flue gas. Metal–organic frameworks (MOFs) with characteristics like high porosity have great potential as membrane materials for gas mixture separation. In this work, through a combination of grand canonical Monte Carlo and molecular dynamics simulations, the permeability of three gases (CO₂, N₂, and O₂) was calculated and estimated in 6013 computation–ready experimental MOF membranes (CoRE–MOFMs). Then, the relationship between structural descriptors and permeance performance, and the importance of available permeance area to permeance performance of gas molecules with smaller kinetic diameters were found by univariate analysis. Furthermore, comparing the prediction accuracy of seven classification machine learning algorithms, XGBoost was selected to analyze the order of importance of six structural descriptors to permeance performance, through which the conclusion of the univariate analysis was demonstrated one more time. Finally, seven promising CoRE-MOFMs were selected, and their structural characteristics were analyzed. This work provides explicit directions and powerful guidelines to experimenters to accelerate the research on membrane separation for the purification of flue gas. Full article