Gas Cleaning Process Research Articles

Synthetic diesel from biomass by Fischer-Tropsch synthesis

The production of liquid hydrocarbons fuel from biomass by Fischer-Tropsch synthesis has become more and more attractive due to its advantages compared to fossil diesel: environmental friendliness by recycling wood and agricultural wastes and reducing emissions of greenhouse gases (CO, CO2 ,SO2,NOx,unburned hydrocarbons and particulate matters), absence of sulphur and nitrogen, higher combustion efficiency, higher cetane number and also the compatibility with existing diesel engines and infrastructure. In this paper the Fischer-Tropsch synthesis process from biomass applied at the Güssing plant was investigated. Each stage of the installation: biomass gasification, gas cleaning and Fischer-Tropsch process, in terms of the equipment used and the parameters necessary for the synthesis, was analysed and discussed. Also, during the synthesis the gas composition of the syngas before and after each stage was analysed, using gas chromatography. The same analytical method was used in order to determine the carbon distribution of the Fischer-Tropsch fuels obtained in the process. The ASF model was applied and an α value of 0.89 was calculated for the products.

Recovery of Spent Methyldiethanolamines and Reduced Environmental Impact

The main purpose of the study is to study and analyze the causes of degradation of 25-30% solutions of ethanolamines (methyldiethanolamine and methylmethyldiethanolamine) used in natural gas purification. The negative changes in ethanolamines that affect their physicochemical properties, absorption capacity and efficiency of gas cleaning as a result of destruction were studied. It has been established that one of the main factors affecting the working properties of ethanolamines and their regeneration is their saturation with high-temperature-resistant salts, organic acids, bitsins, di-, tri-, tetra-amine compounds. As a result of research and analysis, the possibility of increasing the efficiency of gas cleaning by reducing the volume of ethanolamines purchased from abroad and extending the service life as a result of the reuse of ethanolamines from the above substances in the gas cleaning process was studied. As a result, the negative impact on the environment, flora, soil structure, and ground and surface waters has been reduced by reducing their release into the environment.

Analysis of the causes of formation of ethanolamine destruction products in absorbent solutions used in gas cleaning

The causes of degradation of absorbent solutions used in natural gas purification were analyzed. Factors affecting the physico-chemical properties of absorbents, absorption volume were studied. Compounds (thermally stable salts (TBT), organic acids, di-, tri-, tetra-compounds of amines) affecting the efficiency of gas cleaning and reducing the physico- chemical and working properties of ethanolamine solution were studied. It was determined that the accumulation of the above compounds in the absorbent solution causes its saturation, adversely affects the physico- chemical and working properties of the absorbent solution, and makes it unsuitable for the gas cleaning process.

Integration of adsorption based post-combustion carbon dioxide capture for a natural gas-fired combined heat and power plant

This paper proposes a continuous CO2 capture system for natural gas combined heat and power (CHP) facility and explores the potential of low-temperature vacuum-swing adsorption (VSA) process for post-combustion CO2 capture (PCC) in the context of carbon capture and storage (CCS). Although VSA has strong potential for efficient CO2 capture in district-scale energy systems, previous case studies have largely focused on high-emission coal combustion sources, making VSA application challenging for these conditions. We address this issue by theoretically designing a ready-to-operate flue gas cleaning process with CCS for a medium-sized 4.3 MW natural gas CHP operating in the local industry. Our in-depth analysis examines the most critical parts such as dehydration, involving condenser and temperature-swing adsorption (TSA), and CO2 capture via VSA. The conceptual design and performance of VSA are approached by developing a mathematical model to estimate the technology size and performance. This work shows that utilising a small fraction of heat recovered from CHP-generated flue gas is sufficient to supply the necessary heat for auxiliary units, and that using natural cooling water for dehydration effectively reduces moisture (87 vol%) and energy demand for final dehydration via TSA. Furthermore, it demonstrates that 4-step VSA consisting of 15 columns using zeolite 13X can separate CO2 with a desired purity of 90.4%, meeting the requirements for CO2 storage and transportation onshore, at a 15.6% recovery rate. The cost of achieving high CO2 purity without pre-pressurising the CO2-rich flue gas, while maintaining cycle simplicity, is discussed. Overall, our paper provides a comprehensive approach to retrofitting distract-scale power plants with CO2-lean emissions, presenting a ready-to-operate flue gas cleaning technology based on real operating conditions and technical restrictions, which can contribute towards decarbonisation.

AVOIDANCE OF OCCUPATIONAL RISKS OF WORKERS AND MAN-MADE EMERGENCY SITUATIONS DURING CLEANING OF METALLURGICAL EMISSIONS

The article highlights the problem of increasing the level of flue gas filtration at industrial enterprises using the example of the metallurgical industry with the determination of technologically possible ways to increase the level of sulfur removal from gaseous emissions into the atmosphere. This can prevent occupational risks for employees of enterprises due to the reduction of the harmful effects of the components of industrial emissions on occupational health. Increasing the level of understanding of the impact of technological parameters on the target result opens up opportunities for organizing a more balanced and stable flue gas cleaning process. This, in turn, increases the ability of factories to comply with sanitary standards and prevent emergencies of a man-made nature when the maximum permissible concentrations of harmful components in gaseous emissions are exceeded. Solving this problem is possible when using mathematical modeling based on determining the relationship between the level of sulfur removal and the technological indicators of the desulfurization process. Regression analysis was used as a method for building a mathematical model. At the same time, the construction of a multifactorial mathematical model was carried out, based on the industrial parameters of the production of the metallurgical enterprise. The visualization of the obtained results is carried out by presenting the constructed mathematical model as three-dimensional graphs in the form of surfaces with the involvement of some of the technological indicators. The obtained results make it possible to optimize the production indicators to increase the efficiency of the desulfurization of gaseous emissions of the industrial enterprise. At the same time, additional aspects of the relationship between filtration indicators and the degree of purification from harmful components in flue gases are revealed, which allows to establish the most favorable process conditions and can be used not only in the metallurgical industry, but also in the thermal power industry. Keywords: industrial gases, desulfurization, labor hygiene, risks, occupational diseases, environmental safety.

Influence of the Filtration Velocity on the Local Oil Distribution of Oleophilic Coalescence Filter Media

Fibrous nonwoven coalescence filters are commonly utilized in gas-cleaning processes to separate liquid droplets from a gas stream, e.g., oil mists. These filters are mainly composed of micro glass fibers and in some cases, small amounts of synthetic fibers. The shape of the deposited oil on filter fibers of the filter media depends on several factors, including the oil saturation, wettability, roughness, diameter of the fibers and fiber arrangement. The oil deposits can take the form of, e.g., axially symmetric barrel-shaped droplets or larger structures, such as oil sails between adjacent fibers. Understanding the initial state of the coalescence filtration process and the impact of the deposited oil structures on the separation efficiency requires characterizing these structures. X-ray microtomography (µ-CT) and artificial intelligence tools for segmentation can be utilized to visualize, identify and analyze deposited oil structures in the micrometer region. To quantify and compare oil structures formed at three distinct filtration velocities (10, 25 and 40 cm s−1) commonly utilized in industrial applications and one defined oil saturation of oleophilic coalescence filter media, applying X-ray microtomography is the main emphasis of this work. The results indicate that there is no significant influence of the filtration velocity on the local saturation (determined via µ-CT), the number- and volume-based fractions of the identified deposited oil structures on or between adjacent fibers as well as the droplet concentrations and distributions of deposited oil droplets. It is assumed that the structure of the deposited oil formed by coalescence in the filter medium is dominated by the wetting properties of the fibers (surface tension and surface energy) and the saturation, independent of the filtration velocity.

Release of nitrogen and sulphur species from low-rank coal during entrained flow pyrolysis and gasification

This paper investigated the emission of N and S species during pyrolysis and gasification of Maddingley and Yallourn coal in an entrained flow reactor. Nitrogen pollutants (HCN and NH3) and sulphur pollutants (H2S and COS) were investigated under different temperatures (1000–1400 °C) and CO2 concentrations (10–40%). The release of N and S species during the two gasification processes, direct and two-step gasification, were also studied. It was found that no NH3 and COS were detected during pyrolysis and gasification of coal. The N and S in coal were mainly converted to gas-N (>60%) and gas-S (>50%) during entrained flow pyrolysis. Coal-N and Coal-S were converted to nearly 100% gaseous nitrogen and sulphur species during entrained flow gasification. High temperature improved H2S and HCN emissions during coal pyrolysis. High temperature promoted the HCN release during entrained flow gasification, whereas elevated CO2 concentration inhibited H2S and HCN emission. The majority of H2S and HCN emissions came from the pyrolysis part during two-step gasification. Direct coal gasification released less H2S and HCN than two-step gasification. The results provide essential information for the gas cleaning process downstream of entrained flow gasifiers.

Techno-Economic Assessment of Chemical Looping Gasification of Biomass for Fischer–Tropsch Crude Production with Net-Negative CO2 Emissions: Part 2

This work presents a techno-economic analysis of a novel gasification system, chemical looping gasification (CLG), used as the primary gasification process for biofuel production through Fischer–Tropsch synthesis (FTS). Two different gas cleaning process configurations, cold-gas cleanup and hot-gas cleanup process trains, are explored, along with off-gas utilization possibilities, to study their influence on the process economics of an integrated CLG–FT process plant. Off-gas recirculation to increase Fischer–Tropsch (FT) crude production has a significant influence on reducing the levelized production costs for FT crude. The results indicate that the specific production cost estimated for a CLG–FT plant with a hot-gas cleanup train is roughly 10% lower than the case with a cold-gas cleanup train, while the total plant costs remain relatively the same for all plant configurations. In addition to this, the former has a considerably higher overall system energy efficiency of 63%, roughly 18% more than the latter, considering the co-production of FT crude, district heating, and electricity. The specific investment costs range from 1.5 to 1.7 M€2018/MWLHV, and the specific FT crude production cost ranges from 120 to 147 €2018/MWhFT. Roughly 60% of total carbon fed to the process is captured, enabling net-negative CO2 emissions. A CO2 price for negative emissions would significantly reduce the specific fuel production costs and would, hence, be competitive with fossil-based liquid fuels.

Process simulation and evaluation for NH3/CO2 separation from melamine tail gas with protic ionic liquids

Melamine production is known to produce a tail gas with a significant amount of NH3 and CO2. The most common separation methods applied to melamine tail gas are water scrubbing and urea co-production technology. With good stability, non-volatility and tailored properties, ionic liquids (ILs) are regarded as vital potential solvents for gas separation. Therefore, two new process technologies, one is the ionic liquid-based process (IL-0), and the other is the enhanced ionic liquid process (IL-En) was employed and evaluated for energy and cost efficiency. The IL-En employs stripping on the treatment of melamine tail gas. The protic ionic liquid named 1-butyl imidazolium bis (trifluoromethylsulfonyl) imide ([Bim][NTf2]) was selected for the evaluation of the melamine tail gas cleaning process. Thermodynamic data were fitted to the NRTL equations. Three full process flowsheets were simulated in Aspen Plus V11 TM. A basic and an enhanced ionic liquid process (IL-0 and IL-En), a conventional water scrubbing (WS) technology as a comparison, process sensitivity analysis and energy/economic evaluation were carried out. The results showed that the total separation cost of the IL-En can be reduced by 61% compared to that of the WS process. Moreover, the IL-based flowsheet is simpler than WS and avoids wastewater discharge.

Retracted: “DEVELOPMENT AND ANALYSIS OF AN INTEGRATED MILD/PARTIAL GASIFICATION COMBINED (IMPGC) CYCLE”

Abstract Around 50% of the world's electrical power supply comes from the Rankine cycle, and the majority of existing Rankine cycle plants are driven by coal. Given how unattractive coal is as an energy resource in spite of its high energy content, it becomes necessary to find a way to utilize coal in a cleaner and more efficient manner. Designed as a potential retrofit option for existing Rankine cycle plants, the Integrated Mild/Partial Gasification Combined (IMPGC) Cycle is an attractive concept in cycle design that can greatly increase the efficiency of coal-based power plants, particularly for retrofitting an old Rankine cycle plant. Compared to the Integrated Gasification Combined Cycle (IGCC), IMPGC uses mild gasification to purposefully leave most of the volatile matters within the feedstock intact (hence, yielding more chemical energy) compared to full gasification and uses partial gasification to leave some of the remaining char un-gasified compared to complete gasification. The larger hydrocarbons left over from the mild gasification process grant the resulting syngas a higher volumetric heating value, leading to a more efficient overall cycle performance. This is made possible due to the invention of a warm gas cleanup process invented by Research Triangle Institute (RTI), called the High Temperature Desulfurization Process (HTDP), which was recently commercialized. The leftover char can then be burned in a conventional boiler to boost the steam output of the bottom cycle, further increasing the efficiency of the plant, capable of achieving a thermal efficiency of 47.9% (LHV). This paper will first analyze the individual concepts used to create the baseline IMPGC model, including the mild and partial gasification processes themselves, the warm gas cleanup system, and the integration of the boiler with the heat recovery steam generator (HRSG). This baseline will then be compared with four other common types of power plants, including subcritical and ultra-supercritical (USC) Rankine cycles, IGCC, and natural gas. The results show that IMPGC consistently outperforms all other forms of coal-based power. IMPGC is more efficient than the standard subcritical Rankine cycle by nine percentage points, more than a USC Rankine cycle by nearly four points, and more than IGCC by seven points.

Liquid-phase sulfur recovery within a eutectic solvent coupled with low temperature carbon disulfide hydrolysis

Liquid phase sulfur recovery was explored in a eutectic solvent to demonstrate proof-of-concept for an alternative Claus tail gas cleanup process. A simulated tail gas feed containing 3% H2S and 1.5% SO2 was converted to elemental sulfur within a biphenyl and diphenyl ether eutectic solvent. The formed sulfur accumulates at the bottom of the reactor upon solvent saturation, allowing for liquid–liquid separation if the temperature is maintained above 120 °C. Alternatively, crystallization of elemental sulfur could be performed with lower sulfur solubility in the solvent at room temperature. In the temperature range of 120 – 150 °C, a Claus equilibrium conversion of > 99% was achieved when care was taken to maintain the H2S/SO2 ratio at 2:1. While lower temperature favours Claus equilibrium, destruction of other sulfur containing species such as CS2 often suffers at these lower temperatures. Therefore, CS2 destruction was explored within the eutectic solvent over both alumina and titania catalysts, which are commonly used in commercial applications. Good conversions were observed for both alumina and titania when maintaining the H2S/SO2 ratio at 2:1. Better CS2 conversions of 95% (over alumina) and 98% (over titania) were observed at 150 °C when operating at an H2S/SO2 ratio at 2.3:1. The total sulfur conversions, when assuming theoretical equilibrium conversion in the sulfur recovery unit, combined with the liquid-phase tail gas cleanup process ranged from 99.3 to 99.9%. Addition of water to the feed negatively affected the CS2 destruction on titania but had little effect on alumina. At sulfur saturation conditions, CS2 destruction was not affected on titania, but was negatively affected on alumina at 150 °C.

Retrofitting and simultaneous multi-criteria optimization with enhanced performance of an industrial gas-cleaning plant using economic, process safety, and environmental objectives

Natural gas is one of the main sources of energy. Due to the abrupt change of oil and gas price in the global market, it is important to improve the production process and make it profitable in a sustainable manner. The purpose of the current study was to further enhance the performance of the methyl diethanolamine (MDEA) process plant by retrofitting the NG sweetening plant and subsequent multi-criteria optimization studies. Most of the literature studies focused on modeling and sensitivity analysis with little attention to the retrofitting aspects of the gas sweetening unit. Therefore, process retrofitting and simultaneous multi-objective optimization of the natural gas cleaning process using an elitist nondominated sorting genetic algorithm was carried out for the methyl diethanolamine solvent to improve the performance of the absorption well as regeneration column. Seven operating parameters and four conflicting objective functions were considered to formulate two-objective, three-objective, and four-objective optimization problems. Two separate models, i.e., (1) base case and (2) improved retrofitting case, were developed in ProMax process simulator software, and these were validated with actual plant data. All the optimization problems were solved with the base model and improved retrofitting model, and the Pareto optimal fronts were obtained. Up to 17.5% reduction on process safety indicator damage index (DI) was obtained for the lean-vapor compression (LVC) plant configuration considering the same actual plant return on investment (ROI) of 97.44% without affecting H2S removal efficiency. The retrofitted process with LVC can achieve a 42% reduction of acidification potential (AP) and 29% reduction of global warming potential (GWP) compare to the normal process. Therefore, the LVC process can give enhanced plant performance with H2S removal of 99.38%, which leads to the improved cleaner production of natural gas. However, the retrofitted process provides a comparative economic benefit than the existing process.

Development of a simplified gas ultracleaning process: experiments in biomass residue-based fixed-bed gasification syngas

For the realization of small-scale biomass-to-liquid (BTL) processes, low-cost syngas cleaning remains a major obstacle, and for this reason a simplified gas ultracleaning process is being developed. In this study, a low- to medium-temperature final gas cleaning process based on adsorption and organic solvent-free scrubbing methods was coupled to a pilot-scale staged fixed-bed gasification facility including hot filtration and catalytic reforming steps for extended duration gas cleaning tests for the generation of ultraclean syngas. The final gas cleaning process purified syngas from woody and agricultural biomass origin to a degree suitable for catalytic synthesis. The gas contained up to 3000 ppm of ammonia, 1300 ppm of benzene, 200 ppm of hydrogen sulfide, 10 ppm of carbonyl sulfide, and 5 ppm of hydrogen cyanide. Post-run characterization displayed that the accumulation of impurities on the Cu-based deoxygenation catalyst (TOS 105 h) did not occur, demonstrating that effective main impurity removal was achieved in the first two steps: acidic water scrubbing (AWC) and adsorption by activated carbons (AR). In the final test campaign, a comprehensive multipoint gas analysis confirmed that ammonia was fully removed by the scrubbing step, and benzene and H2S were fully removed by the subsequent activated carbon beds. The activated carbons achieved > 90% removal of up to 100 ppm of COS and 5 ppm of HCN in the syngas. These results provide insights into the adsorption affinity of activated carbons in a complex impurity matrix, which would be arduous to replicate in laboratory conditions.

CFD modeling of the forces in the wet scrubber acting on particulate matter released from biomass combustion

The flue gas from biomass combustion contains particulate matter, which is a considerable precarious constituent cause of serious health issues. The wet flue gas cleaning method is one of the most efficient solutions for small-scale boilers (≈100 kW) and small particles. In this study, the forces on particulate matter in a wet flue gas cleaning process using an absorption solution have been studied with the implementation of compiled user-defined function code in Ansys Fluent 19.2®. The forces governing the wet cleaning process as well as the corresponding conditions of the system have also been studied. Drag, buoyancy, diffusiophoresis, and thermophoresis forces have been analyzed as the most important forces acting on particulate matters. Simulations have been conducted for velocities, particle sizes, temperatures, and water vapor mass fractions within the same range as experiments in order to acquire trends for particle collection for these variables.Moreover, the influence of diffusiophoresis force was compared to that of the thermophoresis force under different conditions. It was unveiled that the diffusiophoresis force had a significant effect on nanoparticle collection. The impact of diffusiophoresis is increased by the ascending gradient of temperature as well as water vapor mass fraction. Simulations declare that the thermophoresis force effect is small compared to the diffusiophoresis force effect in the particle collection process. Thereby, one could conclude that the diffusiophoresis force governs the collection of particulate matter in the wet scrubber method. The model validation is confirmed by comparing the results with previous empirical models.

Formation mechanism of arsenic-containing dust in the flue gas cleaning process of flash copper pyrometallurgy: A quantitative identification of arsenic speciation

The proper disposal of arsenic-containing smelting dust has been an important challenge in the copper pyrometallurgy industry which is mostly limited by the variability of arsenic content and species in different types of dusts. The eight types of flash smelting dusts produced along the gas line have been extensively characterized and comparatively studied. Arsenic content gradually increases along the flash smelting (FS) and flash converting (FC) parts of the gas line, and a negative correlation with the pH and copper content has been observed. PM10 accounts for 81.65% and 95.02% of the flash copper furnance (FSF) dust pocket dust and FSF electrostatic precipitator (ESP) dust, respectively. The size distribution variation inply the As enrichment in finer particles. The valence state of arsenic tends to migrate to reach higher valence states along both the FSF and FCF gas line, and the formation mechanism of different types of arsenic particles differs. The As(III)-O mainly remains in the WHB convection part dust and most of them are oxidized to arsenate compounds. More than 80% of the arsenic species was present in the ESP as As(V) and As(III)-arsenite. Fragmentation of concentrate particles and rapid condensation by gas phases lateral flushing of the pipe may produce arsenic particles in the waste heat boiler (WHB), while those remaining in the dust pocket and the ESP may result from adsorption, condensation, and chemical reactions. Temperature is the main factor that affects the deposition site of As2O3 particles. Alkali metal oxide particles influence As content and speciation in dusts by promoting the arsenate formation.

Small- to medium-scale deep syngas purification: Biomass-to-liquids multi-contaminant removal demonstration

The complete and economic removal of harmful components from biomass gasification-based syngas is a major challenge. A final gas cleaning concept for syngas purification to catalytic synthesis quality was developed as an alternative to organic-solvent scrubbing technologies. The motivation is to present smaller-scale BTL processes with a potentially lower-capex gas cleaning solution. The purpose of this study was to realize and validate the final gas cleaning concept in a real syngas environment and to study longer-term performance of deep gas cleaning. Two successful PDU-scale campaigns in complete biomass-to-liquids production chain were performed. A total on-stream time of 163 h was realized in syngas generated from residual woody- and agro-biomasses, with coupled gas feeding to Fischer-Tropsch synthesis. For S-species removal the final gas cleaning featured a novel hybrid of activated carbon- and ZnO-based bed materials. NH3 and partial CO2 removal was achieved by pressurized water scrubbing. The campaigns employed extensive continuous and non-continuous analysis techniques for the study of syngas impurities such as H2S, COS, NH3, HCN, HCl, benzene and tar. The final gas cleaning process demonstrated flexible deep removal of syngas contaminants of all tested biomass origins, thus achieving similar or better purification levels as conventional wet-scrubbing technologies. The cleaned gas was therefore suitable for catalytic synthesis purposes, demonstrating the technical feasibility of the new final cleaning process in conjunction with optimized hot gas cleaning.

Design and performance evaluation of an inclined nozzle and combustor of a downdraft moving bed gasifier for tar reduction

Tar formation is one of the major problems during biomass gasification due to blocking and fouling processes in engines and turbines. Downstream gas cleanup process and conditioning are required to eliminate tar issues. For this reason, methods to reduce tar formation inside the gasifier are gaining more attention. In this work, a novel design for an inclined nozzle and a combustor was proposed and tested in a low-tar biomass (LTB) gasifier to evaluate the effect on tar reduction. The design process was based on a swirling flow created by an inclined nozzle that allows good mixing between pyrolysis gases and gasifying air. The swirl combustor created large internal annular and reverse flow zones with the help of swirl flow. Thus, the combustor had a positive effect on the combustion of the mixture of air and pyrolysis gases and induced thermal cracking in the partial oxidation zone. Recycling ratio (recycle gas/air, v/v) and combustion degree of volatiles were used to evaluate the performance of the inclined nozzle and combustor. The result showed that the tar yields in pyrolysis and partial oxidation zones were on average 1693 mg/Nm3 and 255 mg/Nm3, respectively which accounted for a reduction of 86.6% and 12.7% tar compounds in these zones, respectively. Besides, the producer gas leaving the gasifier had a tar content below 1%, and measured tar content was 7.4-27.14 mg/Nm3 for the tested biomass with moisture contents of 9–34%. Tar removal efficiency was found on average 84.9% after passing the pyrolysis gas through the partial oxidation zone, whereas tar in the producer gas was removed with an efficiency of 99.1% at the gas outlet zone. At an equivalence ratio of 0.35, the new design had the optimal performance with a recycling ratio of 0.35 and combustion degree of volatiles of 98.6%. The achieved producer gas could be directly fed to an internal combustion engine or a gas turbine at small to medium level power generation in remote rural off-grid areas.

Emission reduction process for the energetic use of biogenic residues

During the combustion of biogenic residues particulate matter, nitrogen oxides, chlorine and sulphur compounds as well as dioxins and furans occur in elevated concentrations depending on the respective fuel composition. Corresponding abatement technology is only available for the power plant sector and cannot be used economically on small biomass plants. Therefore an exhaust gas purification procedure was developed and tested which can be used economically in decentral biomass plants. The core of the exhaust aftertreatment process is a fabric filter with catalytically active filter bags which enables a combined reduction of dust and nitrogen oxides. An additional precoating of the fabric filter also removes acidic exhaust gas components such as SO2 and HCl. Experiments were conducted on pilot and field scale. Significant reduction of particle emissions, nitrogen oxides and chlorine compounds could be achieved. Further optimization of the quantities of reducing agent and precoat material supplied is necessary in order to improve the performance of the exhaust gas cleaning process.

Steady State Numerical Simulation of Natural Gas Cleaning Process

Natural gas is a promising elective source of methane (CH₄) due to its accessibility and renewability. However, unfortunately, a high rate of carbon dioxide (CO₂) and very little hydrogen sulfide (H₂S) is found in this CH₄ source. These compounds must be removed to get natural gas of satisfactory quality. One of the most modern common strategies of synchronous CO₂and H₂S removal is chemical absorption, i.e. the use of a Pressure Swing Absorber (PSA). In order to design an efficient plant, the characteristic acidic gas treating plant is mimicked utilizing Aspen HYSYS 8.8. The point of this mimicry is to attain the methane immaculateness of the natural gas by determining the optimum working pressure using a Pressure Swing Absorber (PSA) in which the feed sour gas is fed to the absorber at a concentration of 0.25 CO₂ and 0.0004 H₂S. The absorber parameters are: 30°C (temperature), 1.1 bars (initial pressure) and 15 m³/h (stream rate), and 25 wt. % monoethanolamine (MEA) concentrate. A 20-stage PSA with a tray diameter of 1.7 m is used. The results of the study show that in order to obtain natural gas with a methane purity of 95%, a PSA working pressure of 5 bars is needed.

Multiscale Simulation of Gas Cleaning Processes

This paper considers modeling the processes of cleaning air from finely dispersed solid contaminants clustered in the form of nanoparticles. The purification technology chosen for the study involves the use of a system consisting of nanofilters and sorbents. Both cleaning methods used in it are currently in high demand and are often combined in appropriate devices. The first cleaning method using nanofilters ensures a high purification quality. However, this method is expensive as it requires frequent replacement of the filter elements (membranes) and the disposal of these elements. The second method of cleaning with sorbents gives a relatively low quality of cleaning but enables multiply repeated a purification procedure after washing the sorbent with special liquids. The optimization of air cleaning devices using nanofilters and sorbents requires a detailed investigation of the processes occurring in the cleaning system. The proposed study addresses part of the problem associated with the passage of an air flow containing solid contaminant nanoparticles through a layer of granular sorbent. For this purpose, a multiscale mathematical model, a numerical algorithm, and a parallel implementation of the model on a macroscopic scale have been developed. The novelty of the approach consists in the use of a quasigasdynamic model for describing the flow in the absorbing layer and in the proposed multiscale formulation of the problem. The preliminary calculations based on the macromodel showed the efficiency of the proposed approach.