Gas Purification Process Research Articles

Исследование методов и современных технических решений очистки аэрозольных выбросов промышленности

The analysis and characterization of aerosol emissions into the atmosphere are given, the ways of formation of primary and secondary aerosols are considered. The process of atmospheric aging of aerosols, which has a negative impact on the environment, is considered. The functional links between aerosol emissions, their source and impact on climate and public health are presented. The possible influence of the reactions of liquid and solid aerosol particles on the properties of atmospheric air is considered. The main methods of purification of industrial aerosol emissions are considered: adsorption purification, thermal and catalytic neutralization, chemisorption and absorption purification. The ways of increasing the efficiency of adsorption processes, for example, the separation of adsorbent in the apparatus, are analyzed. The essence of the process of thermal neutralization of gas mixtures is described, it is established that thermal installations based on the direct combustion method work more efficiently when combining thermal and catalytic neutralization methods, designs of combined equipment are presented, and ways to increase the intensity of the apparatus are considered. The process of gas purification based on the absorption process is considered. It is determined that absorption plants for cleaning gases from harmful components are the most effective and efficient due to the high level of technical implementation of the process. The development and improvement of the main absorber equipment is aimed at achieving maximum cleaning efficiency with an optimal pressure drop that determines energy consumption. The analysis shows the negative impact of natural and anthropogenic aerosols on the environment. In order to correctly solve the problem, information on the sources, composition and properties of aerosols is needed to select the most effective and economically profitable cleaning method, which will help reduce the anthropogenic load on the atmosphere.

Development of an automated system for the purification of alkanolamine solutions

The alkanolamine solutions used in natural gas purification processes are inevitably degraded over time. This occurs due to accumulation of reaction products from the reactions with carbon dioxide, hydrogen sulphide, oxygen and other impurities present in the gas streams, as well as from thermal degradation. The degradation of solutions leads to the formation of thermostable compounds that not only reduce absorption efficiency, but also increase corrosive activity. Furthermore, part of the amine turns into a bound state and becomes ballast. The necessity of purification of alkanolamine solutions is becoming more and more urgent since the cost of maintaining efficient operation of gas treatment plants grows, and environmental safety requirements increase. Purification of solutions makes it possible to prolong their service life, reduce the cost of purchasing new reagents and reduce the negative impact on the equipment. In this work the method of anion-exchange technology of purification is used. Unlike vacuum distillation and electrodialysis, the considered technology does not require significant energy costs for generation and maintenance of vacuum, and heating of solutions, it can be easily integrated into the existing production process without any significant changes in the infrastructure. The described problem is relevant for Kazakhstan oil refineries, two of which use methyldiethanolamine, and one of which uses diethanolamine, and the existing practice of maintaining the operability of the systems is based on periodic replacement of part of the solution with pure amine. The development of automated systems for purification of such solutions makes it possible to significantly improve process control, minimise manual labour, and improve the overall economic efficiency of production.

RESEARCH OF ELECTRICITY GENERATION TECHNOLOGY USING GASIFICATION OF PREPARED BIOMASS

The rapid growth of the part of decentralized power generation, associated with the use of renewable energy sources for its production, is one of the main directions of the modern development of power generation systems. The article summarizes the state and direction of development of the world and Ukrainian energy industry. The development of electricity generating equipment based on gas generation is briefly described. The results of the study of electricity production technology using gasification of prepared biomass are given. The technological schemes for the preparation of generator gas as motor fuel and the requirements of manufacturers for the quality of gaseous fuel in the case of its use as motor fuel in modern engines are presented. Methods of determining the content of polluting components in gas, data on the composition of condensate taken from generator gas are given. The presented scheme of gas purification is intended for the use of solid residues of the gasification process for gas purification from finished biofuel. The results of the analysis of the sorption properties of coke-sol residue and the results of gas purification using it as a filter are given. The results of the operation of the complex for the production of electricity by the gasification method are given. It is shown that the environmental indicators of the installation in terms of CO and NOx emissions into the atmosphere meet Euro-5 requirements. Bibl. 20, Fig. 4, Tab. 4.

Enhancing the performance of biofilters with sorption ability for simultaneous purification of landfill gases using laterite soil-based substrate

Various harmful gas emissions are a major controversial issue globally, and open dumpsites have become a leading contributor to atmospheric pollution. The study aims to introduce a high-performance landfill gas purification substrate using laterite soil, an iron, and aluminum-rich, highly available soil type in tropical countries; the final suggested substrate contained uniformly mixed laterite soil and compost with a 4:1 fraction by volume. A self-design setup that can maintain moisture content and aerobic conditions was used with an active landfill gas collection system through the gas wells established on the Karadiyana landfill in Sri Lanka under a tropical climate. The elimination capacity of CH4, NH3, VOCs, and H2S were 202860 ± 51595, 91 ± 30, 75 ± 27, and 6 ± 3 mg m−3 h−1 with 91 ± 3, 96 ± 1, 93 ± 3 and 83 ± 4% of removal efficiencies respectively at a 9.4 min empty bed residence time (EBRT). Selected laterite soil acts as an adsorption material and provides a better bio-filtering substrate with compost due to its specific characteristics. The hybrid gas purification process, absorption, and biofiltration within the proposed material were the reasons for higher performance, and the setup may be successful under the industrial waste gas streams. Further investigation should be carried out to study the medium's effectiveness as the covering layer on the dump with the successful lowest thickness, regarding secondary pollutants, and industrial applicability under unique specific conditions.

Porphyrin-based schiff-base and aminal nitrogen-rich porous organic polymers for capture of SO2 and CO2

Due to its serious hazards to human health and the environment, the deep removal of sulfur dioxide (SO2) has been of great significance. Thus, it is critical to develop high efficient SO2 capture and sequestration materials in gas purification process. Herein, we reported two novel prophyrin-based nitrogen-rich porous organic polymers (POPs), PrPOA-BP and PrPSN-BP, constructed through the simple catalyst-free condensation reaction. Owing to the strong affinity to SO2 from the conjugate-electron macrocycles structure of prophyrin and nitrogen-rich porous networks, also the high porous structure, these two POPs demonstrated excellent SO2 capture and separation performance with the adsorption uptakes up to 18.2 mmol g−1 (273 K, 1 bar), 13.3 mmol g−1 (298 K, 1 bar), 1.68 mmol g−1 (298 K, 0.01 bar). This very competitive performance has far exceeded most of the prior reported nanoporous materials. Meanwhile, the IAST selectivities of SO2/CO2 (10/90, v/v) could reach 107.8 and 72.0 at 273 and 298 K, 1 bar. This study represents a new type prophyrin-based POPs materials and confirms the intrinsic potential for high efficiency SO2 capture and sequestration.

Cyclone-coalescence separation technology for enhanced droplet removal in natural gas purification process

Natural gas is increasingly recognized as a clean energy source due to its high quality, low pollution levels, and abundant availability. However, certain gas fields contain complex components that require purification for efficient transportation and utilization. Addressing these issues involves efficient gas–liquid separation technology. Existing gas–liquid separation units face challenges such as efficiency, liquid entrainment, energy consumption, and the need for consumable replacement. This study focuses on a novel cyclone-coalescence separator that combines centrifugal and coalescence principles. Implemented in a high-acid natural gas purification plant in China, the cyclone-coalescence separator demonstrated efficiency primarily influenced by gas velocity and diameter. Optimal performance was observed with a 75 mm diameter reactor at velocities of 8–12 m s−1, achieving a peak efficiency of 96%. The hydrophilic glass fiber with a monofilament structure can coalesce droplets effectively. In practical industrial use, under operational conditions, the hydrocyclone's liquid discharge rate is 89.6 kg·h−1 with an inlet concentration of 382.7 g·m3. Over a 400-h cycle, the cyclone-coalescence separator demonstrated superior separation performance with an average liquid discharge volume of 9.09 mg·kg−1, compared to 4.93 mg·kg−1 for the precision filter. This successful industrial implementation presents a promising approach to natural gas purification.

Carbon-based materials for low concentration CO2 capture and electrocatalytic reduction

The gradual increase in carbon dioxide (CO2) concentration in the atmosphere has been recognized as a significant problem for humankind. CO2 flue gas is one of the most apparent contributing sources of emissions. CO2 capture and conversion are environmental-friendly and efficient ways to reduce atmospheric carbon dioxide emissions from flue gases. Considering the traditional expensive gas purification process of low-concentration CO2, the low-cost capturing and electrocatalytic CO2 reduction (ECR) at low concentration by newly-developed carbon-based materials provide an attractive approach to convert low-concentration CO2 in flue gas into high-value fuels and chemicals. Developing and integrating carbon-based capturing and catalytic materials with an understanding of the mechanism has a promising future and will promote this technology toward practical application. This review describes recent progress in the design, preparation, and structural characterization of existing carbon-based materials for the capture and catalysis of low-concentration CO2. The crucial factors of capturing and catalysis performance of all the carbon-based materials are also summarized. Furthermore, the review identifies existing research problems and challenges, and outlines future research directions. We also discuss the prospects for the industrialization of low-concentration CO2 capture and ECR. The remaining technological challenges and future directions for enhancing and applying of carbon-based materials for CO2 capture and electrocatalytic reduction are highlighted.

Purification of Steel Mill Gases under Changing Feed Stock Conditions

AbstractThis paper focuses on the operation and results of the gas treatment pilot plant for the purification and conditioning of steel mill gases, a key element of the Carbon2Chem® Technical Center in Duisburg, Germany. Using highly sensitive analytics, it is demonstrated that steel mill gas impurities which are detrimental to downstream catalytic conversion are reduced to single‐digit ppb levels. Strategies for adapting the gas purification process to take account of the transformation of steelmaking towards direct reduction are also discussed.

Ultra-fast polarity switching GC-IMS for the analysis of volatiles in biogas

The Renewable Energy Act 2023 (§39i) requires reducing corn silage in biogas plants from 40 % to 30 % in 2026. Since corn silage yields the highest biogas per weight unit of all biogas feedstocks, this poses new challenges for biogas plant operators. However, alternative biogas feedstocks not harvested directly from the field may contain siloxanes due to the use of care products and disinfectants. The conversion of siloxanes into silicon dioxide during the combustion process seriously threatens the lifetime and efficiency of the used gas engine, even in very low concentrations. Consequently, we present a highly sensitive measurement system for monitoring biogas. Detection limits down to 0.037 mg/m³ for the tested siloxanes have been reached. Furthermore, ketones can be detected down to 0.002 mg/m³, alcohols down to 0.001 mg/m³. The device combines an ultra-fast polarity switching ion mobility spectrometer with a switching time of 12 ms and a resolving power of RP = 70, a gas chromatographic pre-separation, and a non-dispersive infrared sensor for methane. In this context, we analyzed the biogas composition for volatile substances and siloxanes, whereby we only found the volatile substances. For demonstration, biogas was analyzed at three different stages during the gas purification process.

The Influence of the Frequency of Ultrasound on the Exhaust Gas Purification Process in a Diesel Car Muffler

This research aimed to analyze the possibility of installing an ultrasonic emitter in an already manufactured car and to prove the possibility of cleaning the exhaust gases of an internal combustion engine through the action of an ultrasonic wave due to coagulation and examining the optimal regimes of its work. The existing theoretical solution to describe the proposed process was analyzed. A Mercedes-Benz M-Class ML 270 CDI MT car with the OM 612 DE 27 LA Diesel engine was used for the experiment. An ultrasound generator and an ultrasound emitter were connected to the muffler. The stand was connected to the car via the inlet with a rubber hose that directs the exhaust gases out of the car. The crankshaft speed of the engine was changed in the range of 750 to 1250 rpm, which corresponds to urban conditions when cars are moving in heavy traffic jams. The content of CH, CO, CO2, and O2 in the exhaust gas of the vehicle was determined as a function of the crankshaft speed without ultrasonic exposure and with ultrasonic exposure at an ultrasound frequency of 25, 28, and 40 kHz. The results of the experiment showed that the introduction of an ultrasonic emitter into the muffler reduced the smoke content of the gas, increased the oxygen content, and reduced the amount of carbon dioxide in the exhaust gases. With an increase in the ratio between the ultrasonic frequency and the angular velocity of the engine crankshaft (f/ω), the smoke content of the gas also decreased. At the maximum values of ultrasonic frequency and angular velocity of the engine crankshaft selected in the experimental studies, the minimum value of the ratio of gas smoke indicators was achieved, and the degree of purification was 10–13%. Such results correspond to the condition of optimal operation of the ultrasonic muffler, where the ratio of gas to smoke values should tend to a minimum. These results confirm the potential of using ultrasound as a method for cleaning exhaust gases and underline the need for further research in this area.

Oxygen-enriched carbon molecular sieve hollow fiber membrane for efficient CO2 removal from natural gas

Natural gas is considered one of the most attractive low carbon energy sources while the separation of CO2 is a crucial process for the natural gas purification. Herein, cellulose-based carbon molecular sieve (CMS) hollow fiber membranes with high CO2 affinity capability were fabricated through a post-treatment strategy of hydrogen-induced reduction followed by oxygen-doped modification (H-O treatment), and show good potential for high pressure natural gas purification. The CMS membranes were reduced by H2 at high temperatures (500–600 °C) to form active sorption sites in the carbon matrix, and subsequently chemically absorbed O2 to generate oxygen-containing functional groups, which are favorable for CO2 adsorption and diffusion. After being treated at 600 °C (CMS-600), the CMS membrane presented a high CO2 adsorption capacity of 62.78 cm3/g (298 K). As a result, the CO2 permeability was enhanced from 264 to 1125 Barrer, with approximately 400 % improvement. Moreover, mixed gas separation performances (CO2/N2 and CO2/CH4) were investigated at high pressure and impurities feedings. The CMS membrane exhibited a remarkable CO2/CH4 separation factor of 104 when operated at 20 bar and 500 ppm heptane existed.

Bayesian predictive modeling for gas purification using breakthrough curves

This study proposes a predictive model for assessing adsorber performance in gas purification processes, specifically targeting the removal of chemical warfare agents (CWAs) using breakthrough curve analysis. Conventional parameter estimation methods, such as Brunauer-Emmett-Teller analysis, encounter challenges due to the limited availability of kinetic and equilibrium data for CWAs. To overcome these challenges, we implement a Bayesian parametric inference method, facilitating direct parameter estimation from breakthrough curves. The model’s efficacy is confirmed by applying it to H2S purification in a fixed-bed setup, where predicted breakthrough curves aligned closely with previous experimental and numerical studies. Furthermore, the model is applied to sarin with ASZM-TEDA carbon, estimating key parameters that could not be assessed through conventional experimental techniques. The reconstructed breakthrough curves closely match actual measurements, highlighting the model’s accuracy and robustness. This study not only enhances filter performance prediction for CWAs but also offers a streamlined approach for evaluating gas purification technologies under limited experimental data conditions.

Modeling and improving the scrubbing efficiency of an intensified ammonia process for coke oven gas purification

Coke oven gas (COG) is a valuable byproduct of coke production in the steel industry. Conventionally, undesired H2S and NH3 in COG are removed in separate columns in an ammonia process. In this work, an intensified ammonia process which removes both H2S and NH3 in a single column with multiple sections is studied. The intensified process occupies less space and is less expensive. A process model is built and validated using plant operating data. The underlying principal of scrubber operation is explained through the simulated concentration profile. The influences of important operating variables such as inlet COG flowrate, strong ammonia liquid flowrate, low ammonia liquid flowrate and concentrated NaOH solution flowrate are studied. It is shown that the H2S removal efficiency is sensitive to inlet COG flowrate, and that the flowrate of low ammonia liquid should be used as manipulate variable to control the outlet COG composition. Furthermore, it is found that to improve the H2S removal efficiency, the flowrate of concentrated NaOH solution should exceed a certain threshold. Otherwise the scrubbing liquid will be neutralized by CO2 in the COG, which will decrease the pH and alkalinity of the scrubbing liquid significantly.

DUST COLLECTION EFFICIENCY UNDER IN-PHASE TURBULENCE CONDITIONS IN THE PRESENCE OF PHASE TRANSITIONS

The article presents the results of a study of the dust collection efficiency in a regular packing layer of a rotoclone-type hybrid apparatus on the particle inertia index in the presence of phase transition processes. The effect of phase transitions on the efficiency of gas purification processes under inphase turbulence conditions is considered. Based on the conditions of stability of the in-phase vortex formation regime of the gas phase in a regular packing layer, the dominant influence of turbulent diffusion mechanisms on the intensity of phase transition processes and, as a consequence, on the dust collection efficiency has been established. In this case, the predominant influence is in the area of highly dispersed and finely dispersed dust fractions. The results of the experimental studying the patterns of dust collection efficiency depending on the particle inertia index in the presence of phase transition processes are presented. The studies were carried out for three phase transition modes: condensation of vaporsfrom a vapour-gas mixture, evaporation of a spraying liquid as well as a neutral mode. Using A.N. Kolmogorov’s hypothesis,the basic equations and results of calculating the numerical values of local characteristics of a turbulent gas flow in a regular packing layer are presented under the assumption of isotropic turbulence realized in a layer of a regular packing, whose local characteristics do not depend on coordinates and direction.

Determination of the design features of the device for neutralizing toxic components of flue gases

The influence of the boiler unit load on the area of heterogeneous reactions of the process of catalytic flue gas purification is considered. The optimal geometric characteristics of the neutralizer monolith were determined when the steam capacity of the TGME-464 boiler unit varied from 220 to 500 t/h. The calculations were performed using a mathematical model for the conditions of the operating power equipment. The optimal size of the unit cell of the catalyst block is determined in a wide range of boiler load regulation. The data obtained as a result of the study formed the basis for designing a sample of an industrial neutralizer of toxic flue gas components without the introduction of an external reagent.

Disclosure of the nano-scale hydrogen dynamics on mono-vacancy graphene: a reactivity study with incoming gases.

Hydrogenated monovacancy graphene (Hx-MVG, x = 1-7) is investigated for stability, gas interactions, hydrogen migration, and catalytic capabilities using density functional theory (DFT) calculations and molecular dynamics (MD) simulations. The study highlights the robust stability of Hx-MVG, except for H6-MVG, which displays instability in hydrogen migration with an energy barrier of 0.73 eV. Gas interaction analysis with various gases (CH2O, CO2, HCN, NH3, and NO2) reveals physisorption for most gases, with notable alterations observed with NO2, leading to the formation of nitrous acid in different configurations, where trans-HONO exhibits the highest stability. This research represents a significant advancement in gas purification and catalytic processes, providing insights into toxic gas removal and chemical reaction enhancement. Emphasizing metal-free materials, the findings offer innovative approaches to effectively address environmental and industrial challenges.

A High-Performance N2-Selective MXene Membrane with Double Selectivity Mechanism for N2/CH4 Separation.

Membrane-based separation process for unconventional natural gas purification (mainly N2/CH4 separation) has attracted more attention due to its considerable economic benefits. However, the majority of separation membranes at this stage, particularly N2-selective membranes, achieve the desired separation target by mainly relying on the diffusivity-selectivity mechanism. To overcome the limitation of a single mechanism, 2D lamellar MXene membranes with a double selectivity mechanism are prepared to enhance N2 permeance and N2/CH4 selectivity via introducing unsaturated metal sites into MXene, which can form specific interactions with N2 molecules and enhance N2 permeation. The resulting membranes exhibit an inspiring N2/CH4 separation performance with an N2 permeance of 344 GPU and N2/CH4 selectivity of 13.76. The collaboration of the double selectivity mechanism provides a new idea for the development of a novel N2-selective membrane for N2 removal and CH4 purification, which further broadens the application prospects of membrane separation technology in the field of unconventional natural gas purification.

Fabrication of Pillar-Cage Fluorinated Anion Pillared Metal-Organic Frameworks via a Pillar Embedding Strategy and Efficient Separation of SO2 through Multi-Site Trapping.

Flue gas desulfurization is crucial for both human health and ecological environments. However, developing efficient SO2 adsorbents that can break the trade-off between adsorption capacity and selectivity is still challenging. In this work, a new type of fluorinated anion-pillared metal-organic frameworks (APMOFs) with a pillar-cage structure is fabricated through pillar-embedding into a highly porous and robust framework. This type of APMOFs comprises smaller tetrahedral cages and larger icosahedral cages interconnected by embedded [NbOF5]2- and [TaOF5]2- anions acting as pillars. The APMOFs exhibits high porosity and density of fluorinated anions, ensuring exceptional SO2 adsorption capacity and ultrahigh selectivity for SO2/CO2 and SO2/N2 gas mixtures. Furthermore, these two structures demonstrate excellent stability towards water, acid/alkali, and SO2 adsorption. Cycle dynamic breakthrough experiments confirm the excellent separation performance of SO2/CO2 gas mixtures and their cyclic stability. SO2-loaded single-crystal X-ray diffraction, Grand canonical Monte Carlo (GCMC) simulations combined with density functional theory (DFT) calculations reveal the preferred adsorption domains for SO2 molecules. The multiple-site host-guest and guest-guest interactions facilitate selective recognition and dense packing of SO2 in this hybrid porous material. This work will be instructive for designing porous materials for flue gas desulfurization and other gas-purification processes.

Bulk and interfacial properties of methane-heavy hydrocarbon mixtures

Methane-heavy hydrocarbons are typical mixtures in natural gas extraction, purification and production processes. However, the microscopic behavior of methane diffusion, dissolution and adsorption within heavy hydrocarbon liquids has not been solved yet. Therefore, the bulk and interfacial characteristics of methane-heavy hydrocarbon mixtures were systematically analyzed. And the real and rippled interfaces were identified using a new method. The results indicate that density of heavy hydrocarbon-rich phase decreases with decreasing chain length and increasing pressure, while that of the methane-rich phase increases instead. When methane molecules dissolve into bulk liquids, heavy hydrocarbon chains stretch and the intermolecular separation distances increase. Additionally, the interaction energy between the two molecules is the main reason for system swelling. The Gibbs relative adsorption of methane improves until reaching the saturation limit as pressure adds. The intrinsic interface analyses show that the strong adsorption of methane mainly exists in the first surface layer in dilute solutions, which becomes more pronounced with increasing methane fraction. For heavy hydrocarbons with shorter chains, surface layers are narrower and their separation distances are reduced. Furthermore, methane molecules prefer staying at the outer edge of surface layers and are nearer to gas phase than heavy hydrocarbons by approximately 0.2–0.7 Å.

Dual combustion oxyhydrogen-diesel: Effects on internal components of engine

In Mexico, diesel is the second most used fuel, representing 28% of the national consumption, being the largest greenhouse gas emitter. In this work, the diesel engine can run smoothly in dual combustion mode diesel fuel/oxyhydrogen gas (OH2G) because OH2G fed to the diesel engine is limited by the volume available in the combustion chamber; this allows the timing and pressure in the combustion chamber to be kept within the limits of the engine y a combustion without detonations was observed, the existing infrastructure is used, and the consumption of diesel and contaminants emissions could be reduced. This study shows the effects produced in the engine combustion chamber by the dual combustion process of diesel fuel/oxyhydrogen after 500 h of operation. Two air-cooled mono-cylinder diesel engines with a displacement of 405 cm3 were operated; a D100 engine was operated with 100% diesel and OH210 engine in dual combustion (diesel fuel/oxyhydrogen) was operated. Both engines were maintained at 40% load with respect to their maximum power during 500 h OH2G was generated in situ by alkaline electrolysis, and a flow of 2 sL min-1 was fed through the intake port during the suction stroke of the engine. Visual analysis, weight and dimensions of the engine parts, metallographic analysis, oil analysis, and electrolyte drag were used to determine the effects on the component materials. For the engine with dual combustion, diesel fuel/oxyhydrogen, was no structural damage to the engine components, although a slight corrosion onset was observed in some components, such as the piston ring. Moreover, iron and aluminum in the oil were off-standard, which is attributed to the corrosion processes occurring because of water steam containing electrolyte traces being fed to the engine with the oxyhydrogen gas. This implies that more oil changes are necessary within a short period. Therefore, a more robust gas purification process will be implemented, and the injection system will be optimized.