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Theoretical substantiation of the physical principle of increasing the efficiency of ultrasonic agglomeration of submicron particles is proposed, which is based on the creation of resonant conditions for forming vortex flows in gas gaps. The generated vortex flows lead to a local increase in the concentration of particles, which increases the frequency of collisions and, consequently, the efficiency of agglomeration. A numerical model of this process is proposed. The results of calculations carried out on the basis of the numerical model made it possible to ascertain that the efficiency of agglomeration when creating vibrations by a flexurally oscillating radiator (a collection of vortex flows is formed) is more than four times higher than in the case of creating vibrations using a piston radiator (one little-effective vortex flow is generated). [ABSTRACT FROM AUTHOR]

Analytical dependencies for calculating the economically optimal value of the conditional gas velocity in a cyclone are identified taking into account both technical and economic parameters that affect the gas cleaning cost. A method for determining the optimal cyclone diameter and the number of cyclones corresponding to the minimum cost of gas cleaning taking into account the required dust collection efficiency is proposed. Based on the dependencies identified, it has been established that the recommended fixed values of the conditional gas velocity used today when selecting a cyclone are overestimated in most cases. [ABSTRACT FROM AUTHOR]

The article considers the methods for choosing an economically optimal standard size of a cyclone-dust collector: choosing the optimal type, diameter and number of cyclones. The results of calculating the most profitable options (for given cleaning conditions), as well as economic and energy losses that may occur with an arbitrary choice of the cyclone type and the use of a simplified calculation method used today based on the recommended fixed values of the conventional gas velocity, are presented. Based on the technical and economic calculations, an analysis of the manufactured range of the most common NIIOGAZ cyclones has been performed; a number of missing options for cyclone standard sizes that would reduce the cost of cyclone gas cleaning have been detected. [ABSTRACT FROM AUTHOR]

[Display omitted] Garnet-type Ta-doped Li 7 La 3 Zr 2 O 12 (LLZTO) electrolyte suffers from unstable chemical passivation under air exposure, responsible for the poor interfacial wettability and conductivity with Li metal. Instead of conventional methods to remove surface contaminants by mechanical polishing, acid etching and high temperature reduction, herein we propose a simple strategy of interfacial gas release and detergency to smartly convert Li 2 CO 3 passivation layer into ion-conductive Li 3 PO 4 domains at mild temperature (∼200 ℃). The in-situ formation of PH 3 vapor and its phosphorization enables a dramatic decrease of Li/garnet interfacial resistance down to 2 Ω cm2 at room temperature (RT). The improved interfacial wettability and conductivity endow the symmetric cells with ultra-stable galvanostatic cycling over 1500 h and high critical current density of 2.6 mA/cm2. The high coulombic efficiency of Li plating enables a high reversibility of solid-state NCM811/Li cells even under a low N/P ratio (∼4) and high cut-off voltage of 4.5 V at RT. The prototype of fluoride-garnet solid-state batteries are successfully driven as rechargeable system (rather than widely known primary battery) with high conversion capacity (400 ∼ 500 mAh/g) and high-rate performance (251.2 mAh/g at 3 C). This interface infiltration-detergency approach provides a practical solution to the achievement of high-energy solid-state Li metal batteries. [ABSTRACT FROM AUTHOR]

Biomass gasification is a versatile thermochemical process that can be used for direct energy applications and the production of advanced liquid and gaseous energy carriers. In the present work, the results are presented concerning the H2 production at a high purity grade from biomass feedstocks via steam/oxygen gasification. The data demonstrating such a process chain were collected at an innovative gasification prototype plant coupled to a portable purification system (PPS). The overall integration was designed for gas conditioning and purification to hydrogen. By using almond shells as the biomass feedstock, from a product gas with an average and stable composition of 40%-v H2, 21%-v CO, 35%-v CO2, 2.5%-v CH4, the PPS unit provided a hydrogen stream, with a final concentration of 99.99%-v and a gas yield of 66.4%. [ABSTRACT FROM AUTHOR]

The aim of this paper is to define and select stable zones in the off-gas duct of an ore-thermal furnace using a mathematical model. This is needed to increase the effectiveness of exhaust gas composition control in metallurgical silicon production. Methods. The goals of this study were achieved by means of computational fluid dynamics. A model with a water-cooled furnace roof as well as a model comprising steel gas passes with a sliding shutter was developed using ANSYS Fluent software. Both models were symmetrical to ensure a uniform gas-dust distribution, which allowed us to test the adequacy of the obtained models. The models were based on the Navier–Stokes equations system as well as on a discrete phase model (DPM) that was developed using the Euler–Lagrange method. Results. As a result of the modelling, a transition flow mode (Re 0-7437) was revealed behind the sliding shutter. As such, it can be assumed that the most suitable place for measuring equipment to be installed is directly behind the closed part of the sliding shutter. [ABSTRACT FROM AUTHOR]

Fluidized bed gasification technology offers an attractive way to use inhomogeneous biomass residues and various waste-derived feedstocks in power and heat production as well as in various circular economy concepts based on the synthesis gas route. A fluidized bed gasification process development (PDU) plant of 200 kW capacity was operated with Solid Recovered Fuels (SRFs) and demolition wood. In part of the tests carried out with SRF, deposits were formed in the gas lines, and the pressure drop of the filter increased as well. However, optimal combination of gasification, gas cooling and filtration conditions were found to achieve a stable pressure drop, avoid deposit formation and to achieve efficient removal of gas contaminants. The effects of the operating conditions on the achieved carbon conversion and formation of tars and other gas contaminants were studied. The produced gas was filtered at 370-500 °C using two alternative filtration systems applying ceramic bag filters or ceramic fiber filters. The removal efficiency of waste-derived trace metals and chlorine was determined at different filtration temperatures. [ABSTRACT FROM AUTHOR]

The work is devoted to the numerical study of the process of downdraft fixed-bed gasification of woody biomass. Such processes are used to produce combustible gases at lowcapacity power plants. To improve the quality of the produced gas, it is proposed to use a mixture of wood fuel with a non-combustible material that can exhibit catalytic activity in the decomposition of undesired tary products. Adding a non-combustible material leads to lower heat value of fuel mixture, but contributes to a deeper gas purification. The aim of the study is to select the optimal "active material / wood fuel" ratio and to determine the minimum material activity at which its addition to the fuel becomes effective.

To predict the behavior of gas-cleaning filters during real-world operation, it is essential to understand their response to ambient conditions. The temporary presence of water droplets in gas-cleaning filtration systems due to fog, spray rain, or condensation, as examples of irregular events, has an impact on the filters’ operating performance, especially when soluble particles are present. In this work, surface filters were loaded with mixtures of water-soluble salt particles and insoluble glass spheres. These were, subsequently, exposed to water mist and dried by a particle-free gas stream. A novel approach to analyze the drainage of solution on filters with soluble filter cakes is presented, which allows the detection of solubles on the clean gas side of the filter. As a result, this work, for the first time, presents a sighting of the penetration of soluble filter cake material through gas-cleaning filters. Furthermore, filter performance, in terms of differential pressure and fractional separation efficiency, was determined and a characteristic differential pressure evolution for hydrophilic filters during exposure to water mist was also identified. The fractional separation efficiency of gas-cleaning filters decreases due to exposure to water mist. The findings are supported by scanning electron microscopy (SEM) images, energy-dispersive X-ray (EDX), and X-ray microtomography (µ-CT analysis) images.

Biomass gasification is a versatile thermochemical process that can be used for direct energy applications and the production of advanced liquid and gaseous energy carriers. In the present work, the results are presented concerning the H2 production at a high purity grade from biomass feedstocks via steam/oxygen gasification. The data demonstrating such a process chain were collected at an innovative gasification prototype plant coupled to a portable purification system (PPS). The overall integration was designed for gas conditioning and purification to hydrogen. By using almond shells as the biomass feedstock, from a product gas with an average and stable composition of 40%-v H2, 21%-v CO, 35%-v CO2, 2.5%-v CH4, the PPS unit provided a hydrogen stream, with a final concentration of 99.99%-v and a gas yield of 66.4%.

The direct methanation of biogas using hydrogen from electrolysis is a promising pathway for seasonal storage of renewables in the natural gas network. It offers particular advantages over the methanation of carbon dioxide separated from biogas, as it eliminates a costly and unnecessary carbon dioxide separation step. The key implementation challenges facing direct methanation of biogas are reviewed here: 1) treatment of biogas impurities; 2) competing reactor concepts for methanation; and 3) competing process concepts for final upgrading. For each of these three aspects, the state of the art is reviewed, focusing especially on results which have been validated at a high Technology Readiness Level (TRL) at recent long-duration demonstrations. The different technology solutions have advantages and disadvantages which may fit best to different technical and economic boundary conditions, which are discussed. As a final outlook, TRL 8 demo plants will be necessary to show the full potential of these systems, and to obtain consistent operation data to allow a cost comparison.

The capacity of adsorber beds used in industrial-scale temperature-swing adsorption diminishes over time due to bed aging. Here, we present industrial data on the temperature signals from fixed-bed adsorbers using activated carbon designed to remove benzene and other impurities from the gas produced in biomass gasification. The aging of the adsorber beds proceeds due to irreversible adsorption of trace species and manifests itself via two simultaneous effects: a decrease in the availability of active adsorption sites over time and an increase in the overall thermal mass of the bed. Both effects tend to dampen the temperature response of the beds during operation, implying that they are easily confounded. Model descriptions of bed aging should account for both effects.

The aim of this paper is to define and select stable zones in the off-gas duct of an ore-thermal furnace using a mathematical model. This is needed to increase the effectiveness of exhaust gas composition control in metallurgical silicon production. Methods. The goals of this study were achieved by means of computational fluid dynamics. A model with a water-cooled furnace roof as well as a model comprising steel gas passes with a sliding shutter was developed using ANSYS Fluent software. Both models were symmetrical to ensure a uniform gas-dust distribution, which allowed us to test the adequacy of the obtained models. The models were based on the Navier–Stokes equations system as well as on a discrete phase model (DPM) that was developed using the Euler–Lagrange method. Results. As a result of the modelling, a transition flow mode (Re 0-7437) was revealed behind the sliding shutter. As such, it can be assumed that the most suitable place for measuring equipment to be installed is directly behind the closed part of the sliding shutter.

Sulfur, and in particular, H 2 S removal is of significant importance in gas cleaning processes in different applications, including biogas production and biomass gasification. H 2 S removal with metal oxides is one of the most viable alternatives to achieve deep desulfurization. This process is usually conducted in a packed bed configuration in order to provide a high solid surface area in contact with the gas stream per unit of volume. The operating temperature of the process could be as low as room temperature, which is the case in biogas production plants or as high as 900 ∘ C suitable for gasification processes. Depending on the operating temperature and the cleaning requirement, different metal oxides can be used including oxides of Ca, Fe, Cu, Mn and Zn. In this review, the criteria for the design and scale-up of a packed bed units are reviewed and simple relations allowing for quick assessment of process designs and experimental data are presented. Furthermore, modeling methods for the numerical simulation of a packed bed adsorber are discussed. [ABSTRACT FROM AUTHOR]

Char is the solid by-product of biomass gasification. It usually represents a cost for plant owners, who have to dispose of it at a cost. However, its high carbon content and surface area could make it suitable for further applications, such as adsorption. In this work, we studied its potential for the adsorptive removal of hydrogen sulphide (H 2 S), a common pollutant present in the producer gas of gasification, as well as in biogas from anaerobic digestion. Different samples of char collected from commercial gasification plants in South Tyrol (Italy) were tested. The adsorption was reproduced in a lab-scale tubular fixed-bed reactor. The results highlight that all samples could capture hydrogen sulphide, showing different adsorption performances. The materials' specific surface area and metal and oxygen content seem to affect the removal capacity. After these tests, we selected the best-performing char, and tested its adsorption performance in different operative conditions, i.e. at different inlet concentrations of H 2 S and temperatures. Image 1 • The use of the residual char from biomass gasification to adsorb H 2 S was studied. • Samples of char from commercial plants collected, characterised and employed. • All the samples were able to adsorb H 2 S with different efficiency. • Different behaviours due to the specific surface area, oxygen and metal content. • The effect of the H 2 S inlet volume fraction and temperature was also assessed. [ABSTRACT FROM AUTHOR]

Highlights • Different chars and types of active carbon have been tested for adsorption and cracking of toluene and naphthalene. • In the lowest temperature range (250–400 °C), adsorption of aromatics took place on the surface of chars. • In the highest temperature range (600–800 °C), decomposition of aromatics with H 2 and CH 4 production was observed. • Gasification-derived char exhibited a good catalytic activity towards cracking and the slowest deactivation tendency. Abstract The carbonaceous products of gasification or pyrolysis (chars) and active carbon (AC) have been found effective as adsorbents for tar species and active as catalysts for tar conversion. However, a deeper understanding of the interaction between aromatic compounds and carbonaceous surfaces is needed for the practical implementation and optimization of carbon–based gas cleaning systems. The aim of this work is to investigate the performance of various wood-derived chars and AC within a wide temperature range (250–800 °C). Residual char from gasification, pyrolysis char and two types of AC were tested for their capability to remove tar model compounds (toluene and naphthalene) from a gaseous flow. A dedicated setup was used for this purpose, while post-experimental characterization revealed the modifications occurring at the surface of chars. Adsorption was observed in the lower temperature range, whereas cracking reactions were found to initiate at 600 °C and to become significant at 800 °C. Results suggested that AC represents a better option for tar adsorption applications (e.g. carbon filters) operating at temperatures of 250 °C and possibly below, whereas gasification residual char resulted as the most promising substrate for tar cracking at temperatures of 800 °C and above. [ABSTRACT FROM AUTHOR]

• Catalytic direct methanation of biogas was demonstrated with real biogas. • Stable operation of the fluidised bed methanation for over 1100 h. • Biomethane with an average methane yield of 96% was injected into the gas grid. • Slow deactivation by organic sulphur compounds was identified and solved. • Experimental results were in accordance with results from a rate-based model. The catalytic direct methanation of biogas to produce biomethane was conducted in a pilot plant with real biogas from a biogas plant in Zurich. Stable operation of the methanation system including a bubbling fluidised bed could be demonstrated for over 1100 h of regular operation with subsequent injection into the gas grid. An average methane yield of 96% was reached. During the long-duration experiment, the slow deactivation process was monitored and found to be only moderate. Organic sulphur compounds could be identified as the main source of deactivation. However, deactivation from coking could not be fully excluded. With appropriate measures in the gas cleaning unit, so that no sulphur compounds were measured subsequently (limit of detection: <0.05 ppm of relevant components), the yield reduction went close to zero. Additionally, experimental results were compared to simulation results from a rate-based model presented elsewhere. Model predictions and experimental results are in accordance. The kinetics used in the rate-based model allowed a correct prediction of the optimum reaction temperature found by experimental results. [ABSTRACT FROM AUTHOR]

The methodology and results of a calculation of economic and energy-saving effects in cyclones through the use of vane-type whirling devices are presented. Data on the reduction in hydraulic resistance and energy consumption achieved with gas cleaning by means of such devices in СN-11 and СN-15 cyclones, the types of cyclones that are the most common, are given. It is shown that the use of energysaving devices is economically profitable, with a recoupment period of less than a year on average. [ABSTRACT FROM AUTHOR]

The paper focuses on the theoretical description of the cleaning of syngas from biomass and waste gasification using catalytic methods, and on the verification of the theory through experiments. The main obstruction to using syngas from fluid gasification of organic matter is the presence of various high-boiling point hydrocarbons (i.e., tar) in the gas. The elimination of tar from the gas is a key factor in subsequent use of the gas in other technologies for cogeneration of electrical energy and heat. The application of a natural or artificial catalyst for catalytic destruction of tar is one of the methods of secondary elimination of tar from syngas. In our experiments, we used a natural catalyst (dolomite or calcium magnesium carbonate) from Horní Lánov with great mechanical and catalytic properties, suitable for our purposes. The advantages of natural catalysts in contrast to artificial catalysts include their availability, low purchase prices and higher resilience to the so-called catalyst poison. Natural calcium catalysts may also capture undesired compounds of sulphure and chlorine. Our paper presents a theoretical description and analysis of catalytic destruction of tar into combustible gas components, and of the impact of dolomite calcination on its efficiency. The efficiency of the technology is verified in laboratories. The facility used for verification was a 150 kW pilot gasification unit with a laboratory catalytic filter. The efficiency of tar elimination reached 99.5%, the tar concentration complied with limits for use of the gas in combustion engines, and the tar content reached approximately 35 mg/mn3. The results of the measurements conducted in laboratories helped us design a pilot technology for catalytic gas cleaning.

The material characteristics and properties of transition metal dichalcogenide (TMDCs) have gained research interest in various fields, such as electronics, catalytic, and energy storage. In particular, many researchers have been focusing on the applications of TMDCs in dealing with environmental pollution. TMDCs provide a unique opportunity to develop higher-value applications related to environmental matters. This work highlights the applications of TMDCs contributing to pollution reduction in (i) gas sensing technology, (ii) gas adsorption and removal, (iii) wastewater treatment, (iv) fuel cleaning, and (v) carbon dioxide valorization and conversion. Overall, the applications of TMDCs have successfully demonstrated the advantages of contributing to environmental conversation due to their special properties. The challenges and bottlenecks of implementing TMDCs in the actual industry are also highlighted. More efforts need to be devoted to overcoming the hurdles to maximize the potential of TMDCs implementation in the industry.

Natural gas is becoming increasingly important as a primary energy source. A suitable replacement for fossil natural gas is bio-SNG, produced by biomass gasification, followed by methanation. A major challenge is efficient gas cleaning processes for removal of sulfur compounds and other impurities. The present study focuses on development of a gas cleaning step for a product gas produced in a 50 MWfuel gasification system. The developed gas cleaning washing process is basically a modification of the Rectisol process. Several different process configurations were evaluated using Aspen plus, including PC-SAFT for the thermodynamic modeling. The developed configuration takes advantage of only one methanol wash column, compared to two columns in a conventional Rectisol process. Results from modeling show the ability of the proposed configuration to remove impurities to a sufficiently low concentrations - almost zero concentration for H2S, CS2, HCl, NH3 and HCN, and approximately 0.01 mg/Nm3 for COS. These levels are acceptable for further upgrading of the gas in a methanation process. Simultaneously, up to 92% of the original CO2 is preserved in the final cleaned syngas stream. No process integration or economic consideration was performed within the scope of the present study, but will be investigated in future projects to improve the overall process.

Sustainable development goals for 2030 aim at the extensive reduction of the global sanitation breach; this might be achieved by renewed sanitation technologies and while providing sanitation recover valuable products such as energy. Consequently, this work presents a gasification–solid oxide fuel cell (SOFC) power plant that was configured for high-efficiency energy recovery from faecal sludge. The main limitations of faecal sludge gasification are the production of impurities, such as tar, and the high energy requirements for both the endothermic gasification process and removing the high moisture content in the feedstock. However, results from this work indicate that a superheated steam dryer combined with an indirectly heated multistage gasifier and a gas-cleaning unit can overcome the mentioned limitations. The external heat for the gasifier is supplied by the process heat available and a microwave plasma torch, and there is sufficient heat to drive a micro steam turbine. Thermodynamic calculations indicated that the plant could reach a net electrical efficiency of the order of 65%. As a result, a gasification–SOFC power plant is more suitable for energy recovery than any other process such as biochar production by pyrolysis; hence, it might become a technology that is financially feasible and can be used globally for sanitation purposes. [ABSTRACT FROM AUTHOR]

The research efforts for SOFC plants fed by biogas moved from the prototypal research to the feasibility of pilot plants up to achieve industrial size plants. Siloxanes among the other trace compounds contained in biogas appear to be the most detrimental for the fuel cell performance. Siloxanes are difficult to be detected and monitored continuously in the gas matrix. A direct injection mass spectrometry technique (PTRMS) was adopted for the monitoring of siloxane removal. Commercial and waste derived sorbent materials are experimentally tested for the removal of siloxanes. Waste derived material was selected to implement the circular recovery purposes. A simple parametric investigation study was developed. It was considered the influence of gas velocity and sulphur compounds, as co-vapors. Physical and chemical characteristics were correlated to the adsorption capacity. Results show three separated groups. Group I shows the best performance in terms of siloxane removal. There is a direct and strong relation between active surface area and microporous volume with the adsorption capacity. This direct correlation is not verified for some elements such as Fe and S, while it is respected for Cu and K. Higher performance are registered for not all the commercial carbons. In fact, the physical structure and impregnating agents are crucial for the siloxane removal. [ABSTRACT FROM AUTHOR]

Gaseous-emissions absorption technology based on vibroturbulization effects is developed. A diagram of the latest modification of the gaseous-emissions absorption unit with a jet apparatus is presented. Test results show that the proposed technology is efficient. [ABSTRACT FROM AUTHOR]

Features of the process of separation in structured packing are considered, a new design of jalousie separation packing is proposed, and results of experimental and analytic investigations of the new design are presented. [ABSTRACT FROM AUTHOR]

Pyrolysis chars from wastes were investigated as sorbents for H 2 S removal from syngas. The H 2 S removal tests were performed at ambient temperature in various dry gas matrices (N 2 , Air, Syngas) to study the effect of the gas composition on the adsorption efficiency. Two chars were produced by the pyrolysis of: used wood pallets (UWP), and a 50/50% mixture of food waste (FW) and coagulation-flocculation sludge (CFS). The chars were functionalized by low-cost processes without chemicals: gas phase oxygenation and steam activation. Activated chars were the most efficient materials due to their large specific surface area, alkaline pH, basic O-containing groups and structural defects in graphene-like sheets. Raman analysis evidenced that inherent mineral species (especially Ca and Fe) increased the H 2 S removal efficiency by promoting the formation of metal sulfide and metal sulphate species at the char surface. Mesopores lower than 70 Å were revealed to be important adsorption sites. Under dry Syngas matrix, the chars remained efficient and selective toward H 2 S removal despite the presence of CO 2 , while O 2 in the Air matrix decreased their removal capacity due to the formation of sulfur acid species. The most efficient material was the steam activated char from FW/CFS, with a removal capacity of 65 mg H2S .g −1 under dry syngas. This char was proved to be completely regenerated with a thermal treatment under N 2 at 750 °C. This study demonstrated that activated chars from food waste and sludge could be used as eco-friendly, affordable, and selective materials for syngas desulfurization even under dry atmosphere. [ABSTRACT FROM AUTHOR]

The article offers key points for new gas chromatographers to be successful in dealing with gas chromatography (GC) issues such as contamination. It notes that three contamination causes a degradation in peak shape, making it worse as the contamination builds up. It suggests that the need for source cleaning can be identified by monitoring the performance of a standard injected over time.

Biosphere carbon sinks are crucial for reducing atmospheric carbon dioxide (CO 2 ) concentration to mitigate global warming, but are substantially affected by the input of reactive nitrogen (N r ). Although the effects of anthropogenic CO 2 emission and nitrogen deposition (indicated by N r emission to atmosphere) on carbon sink have been studied, it is unclear how their ratio (C/N) changes with economic development and how such change alters biosphere carbon sinks. Here, by compiling datasets for 132 countries we find that the C/N ratio continued to increase despite anthropogenic CO 2 and N r emissions to atmosphere both showing an asymmetric para-curve with economic growth. The inflection points of CO 2 and N r emissions are found at around $15,000 gross domestic product per capita worldwide. Economic growth promotes the use of N r and energy, while at the same time increases their use efficiencies, together resulting in occurrences of inflection points of CO 2 and N r emissions. N r emissions increase slower but decrease faster than that of CO 2 emissions before and after the inflection point, respectively. It implies that there will be relatively more anthropogenic CO 2 emission but less N deposition with economic growth. This may limit biosphere carbon sink because of relative shortage of Nr. This finding should be integrated/included in global climate change modelling. Efforts, such as matching N deposition with carbon sequestration on regional scale, to manage CO 2 and N r emissions comprehensively to maintain a balance are critical. [ABSTRACT FROM AUTHOR]

Cyclone behavior is complex and difficult to model. Recent years have seen the development of new and better predictive models for cyclone performance, which are providing new insights into how cyclone performance is affected by cyclone geometry. Experimental data are essential for verification of such models. In this article we present a dataset of more than 250 experimental determinations of cyclone penetration. The dataset includes cyclones with a wide range of sizes and geometries, tested at a wide range of flow rates. We illustrate some empirical, semi-empirical and mathematical approaches to modeling these cyclone data. For our data, we show that mathematical modeling approaches developed for large gas-cleaning cyclones can also be applied to small aerosol monitoring cyclones, to diverse cyclone geometries, and laminar flow operating conditions. [ABSTRACT FROM AUTHOR]

The mercury (Hg) distribution characteristics were investigated in three primary manganese smelting plants in Korea for the assessment of anthropogenic Hg released. Input and output materials were sampled from each process, and Hg concentrations in the samples were analyzed. Among the input materials, the most mercury was found in the manganese ore (83.1–99.7%) and mercury was mainly released through fly ash or off gas, depending on the condition of off gas cleaning system. As off gas temperature decreases, proportion and concentration of emitted gaseous elemental mercury (Hg 0 ) in off gas decreases. Based on mass balance study from these three plants and national manganese production data, the total amount of mercury released from those Korean plants was estimated to 644 kg/yr. About half of it was emitted into the air while the rest was released to waste as fly ash. With the results of this investigation, national inventory for Hg emission and release could be updated for the response to Minamata Convention on Mercury. [ABSTRACT FROM AUTHOR]

Energy, liquid biofuels and chemicals can be produced from biomass via gasification followed by gas cleaning over ZrO 2 -based catalysts. When a small amount of oxygen is added, ZrO 2 -based catalysts can be utilized in tar decomposition reactions (tar molecules need to be removed before further use). Oxidation of toluene as tar model compound was studied by temperature-programmed experiments over ZrO 2 , Y 2 O 3 -ZrO 2 and SiO 2 -ZrO 2 . In the first part of this study (Part A: Effect of oxygen on the formation of primary products), special attention was given to the effect of oxygen amount on the formation of synthesis gas components (CO and H 2 ) from toluene. The data obtained in Part A was extended and subjected to kinetic modeling. As a result, the reaction mechanism of toluene oxidation over ZrO 2 -based catalysts was discovered. The first step in toluene oxidation is the adsorption of toluene as a benzyl species. Next, the surface benzyl species is oxidized, possibly via superoxide surface species (O 2 − ), into four products in a single net primary reaction. Oxidation of CO and H 2 are the secondary reactions in the model. Furthermore, the present study clearly demonstrates the strength of temperature programming as a transient technique for comprehensive mechanistic investigations, kinetic model development and parameter estimation. [ABSTRACT FROM AUTHOR]

Biomass gasification combined with effective gas cleaning is an interesting way to produce energy or syngas for numerous applications. ZrO 2 -based catalysts have been proven to remove the undesired tar molecules when a convenient oxygen amount is added. The oxidation of toluene (a tar model compound) was addressed in this work by applying temperature-programmed surface reaction (TPSR) experiments with a continuous feed of toluene and oxygen. Complete toluene conversions were achieved over all zirconia-based catalysts (ZrO 2 , Y 2 O 3 -ZrO 2 and SiO 2 -ZrO 2 ) in toluene oxidation above 550 °C (toluene WHSV 0.06–0.07 1/h). Toluene was oxidized into four products (CO 2 , H 2 O, CO and H 2 ). The formation of incomplete oxidation products (CO and H 2 ) suggests that these catalysts are able to convert undesired tar molecules also into valuable synthesis gas components. Increasing the oxygen amount increased the product ratio of CO 2 and CO. Over pure ZrO 2 , the formation of CO and H 2 was detected at 600 °C even with the highest feed ratio of O 2 /TOL (≈3.5 × theoretical toluene total oxidation ratio), while over the doped zirconias the formation of CO and H 2 approached zero with increasing temperature and over-stoichiometric feeds. Separate CO oxidation experiments confirmed different but appreciable activities of different zirconia materials for that reaction. However, a very minor water-gas shift activity in the presence of oxygen was detected only over pure ZrO 2 at the studied temperature range. The collected multiresponse reaction data was subsequently subjected to transient kinetic modeling established on hypotheses of surface reaction mechanisms (Part B: Kinetic modeling). [ABSTRACT FROM AUTHOR]

Through a massive population growth, waste management has become one of the main concerns of our time. In Portugal the growing volume of municipal solid waste has become a central problem for municipalities, due to lack of space and the high costs to solve it. Gasification has received a renewed interest in the municipal solid waste treatment since it limits dioxins formation, presents higher efficiency and requires less expensive gas cleaning equipment when compared to available methods gas. However, to make to process more appealing to both private sector and government institutions is necessary to overcome some concerns related to the process. To expedite the mainstream of this technology a first and second law analysis conducted on Portuguese municipal solid waste was carried out. The thermodynamic method was coupled with a previously developed numerical model. Said model was validated using data from a pilot scale plant. Both energy and exergy values were investigated in order to evaluate Portuguese municipal solid waste as an energy source. Optimal operating point was found at 900 °C for an equivalent ratio of 0.25. Tar content energy values decreased as high as 80% when temperature was increased to 900 °C. A comparison between several gasification efficiencies was investigated. [ABSTRACT FROM AUTHOR]

Este trabalho é parte de um projeto de desenvolvimento de filtros cerâmicos para a remoção de material particulado disperso em correntes gasosas em temperaturas elevadas. Os filtros cerâmicos utilizados para esta finalidade devem apresentar elevada porosidade aliada a uma distribuição homogênea de poros interconectados, resultando em estrutura permeável e com boa resistência mecânica e eficiência de coleta. Uma rota de processamento recentemente desenvolvida é utilizada para o processamento das peças, já que permite a obtenção de todas as características requeridas para uma filtração eficiente. Nesta técnica, os materiais porosos são processados a partir da incorporação de espumas aquosas em uma suspensão cerâmica de alumina e consolidados a partir da adição de cimento aluminoso. Comparado com outras rotas de processamento, este processo é mais atrativo, pois permite a fabricação de peças com geometrias complexas, economicamente viáveis e sem utilização de aditivos tóxicos. O objetivo deste trabalho foi otimizar a composição cerâmica de modo a atender aos requisitos de permeabilidade do filtro, tendo como base sua operação econômica em temperaturas elevadas em processos como incineração de resíduos, produção de cimento ou queima de biomassa em caldeiras em plantas químicas.This work is part of a project to develop ceramic filters to treat flue gases from cement plants, biomass boilers and waste incinerators. Ceramic filters used for these purposes must present high porosity, homogeneous porous distribution (interconnected) to result in bodies with high mechanical strength, permeability and collection efficiency for fine particles. A method recently developed has been used for the filters processing. In this new processing route, the porous samples were prepared through the incorporation of aqueous foams into alumina-based suspensions. Compared to other techniques, this process seems to be an attractive and cost effective solution for fabricating complex shaped bodies, without toxic admixtures. The procedure to establish the required features of the filtering membrane for a desired flow condition is described, as well as the experimental work to produce and select the ceramic membranes with such requirements.

Este trabalho é parte de um projeto de desenvolvimento de filtros cerâmicos para a remoção de material particulado disperso em correntes gasosas em temperaturas elevadas. Os filtros cerâmicos utilizados para esta finalidade devem apresentar elevada porosidade aliada a uma distribuição homogênea de poros interconectados, resultando em estrutura permeável e com boa resistência mecânica e eficiência de coleta. Uma rota de processamento recentemente desenvolvida é utilizada para o processamento das peças, já que permite a obtenção de todas as características requeridas para uma filtração eficiente. Nesta técnica, os materiais porosos são processados a partir da incorporação de espumas aquosas em uma suspensão cerâmica de alumina e consolidados a partir da adição de cimento aluminoso. Comparado com outras rotas de processamento, este processo é mais atrativo, pois permite a fabricação de peças com geometrias complexas, economicamente viáveis e sem utilização de aditivos tóxicos. O objetivo deste trabalho foi otimizar a composição cerâmica de modo a atender aos requisitos de permeabilidade do filtro, tendo como base sua operação econômica em temperaturas elevadas em processos como incineração de resíduos, produção de cimento ou queima de biomassa em caldeiras em plantas químicas.This work is part of a Brazilian project to develop ceramic filters to treat flue gases from cement plants, biomass boilers and waste incinerators. Ceramic filters used for these purposes must present high porosity, homogeneous porous distribution (interconnected) to result in bodies with high mechanical strength, permeability and collection efficiency for fine particles. A method recently developed has been used for the filters processing. In this new processing route, the porous samples were prepared through the incorporation of aqueous foams into alumina-based suspensions. Compared to other techniques, this process seems to be an attractive and cost effective solution for fabricating complex shaped bodies, without toxic admixtures. The procedure to establish the required features of the filtering membrane for a desired flow condition is described, as well as the experimental work to produce and select the ceramic membranes with such requirements.

Sorbents for low temperature reactive adsorption of H 2 S were prepared by dispersing mixed Zn and Cu oxides onto a commercial activated carbon at fixed total metal loading and Cu:Zn atomic ratios from 0:1 to 1:1. Fresh and spent sorbents were characterized by means of ICP-MS, SEM-EDX, XRD, BET and pore size distribution, DRIFT and sulphur elemental analysis. H 2 S (50–3000 ppmv in N 2 ) removal tests were run under dynamic conditions at 30 °C. Due to the high dispersion of the metal oxide phase and its favorable interaction with the carbonaceous support, the functionalized sorbents showed a strongly enhanced adsorption capacity with respect to the raw activated carbon, under dry conditions. Furthermore, the utilization factor of the active phase (moles of S captured per mole of Cu + Zn) increased along with the Cu content up to 76%, thus demonstrating a clear promoting effect of Cu-insertion on the reactivity of ZnO, already at low Cu concentration. Temperature Programmed Desorption (TPD) of H 2 S and SO 2 from saturated sorbents showed that H 2 S adsorption was coupled with oxidation phenomena leading to the formation of metal sulphates apart from metal sulphides and/or elemental sulphur, testifying the complexity of the surface reactions. [ABSTRACT FROM AUTHOR]

Coal burning in power plants and industrial boilers is the largest combustion source of mercury emissions in China. Together, power plants and industrial boilers emit around 250 tonnes of mercury each year, or around half of atmospheric mercury emissions from anthropogenic sources in the country. Power plants in China are generally equipped with multi-pollutant control technologies, which offer the co-benefit of mercury removal, while mercury-specific control technologies have been installed in some facilities. In contrast, most industrial boilers have only basic or no flue gas cleaning. A combination of measures, including energy conservation, coal switching and blending, reducing the mercury contents of coals through washing, combustion controls, and flue gas cleaning, can be used to reduce mercury emissions from these stationary combustion sources. More stringent emission standards for the major air pollutants from coal-fired power plants and industrial boiler, along with standards for the previously unregulated mercury, were implemented recently, which is expected to bring significant reduction in their mercury emissions through the necessary upgrades of multi-pollutant and mercury-specific control technologies. Meanwhile, strong monitoring capacity and strict enforcement are necessary to ensure that the combustion sources operate in compliance with the new emission standards and achieve significant reduction in the emissions of mercury and other air pollutants. [ABSTRACT FROM AUTHOR]

A lot of particles from iron-making are removed with blast furnace off-gas and routed to the gas cleaning system. As water is used for cleaning the gas, the produced wash water contains a large amount of particles such as valuable Fe and C. However, the presence of zinc prevents recycling. In addition, the high amount of calcium results in uncontrolled scaling. Therefore, the properties of the wash water from scrubber and sludge, from the Finnish metal industry (SSAB Raahe), were evaluated in this study. Size fractionation of wash water revealed that Fe, Zn, Al, Mn, V, Cr and Cd appeared mainly in the larger fractions (>1.2 μm) and Na, Mg, Si, Ni, K, Cu and As appeared mainly in the smaller fractions (<1.2 μm) or in dissolved form. Calcium was found both in the larger fractions and dissolved (∼60 mg/L). Most of the particles in wash water were included in the 1.2–10 μm particle size and were settled effectively. However, a clear benefit was observed when using a chemical to enhance particle settling. In comparison to 2.5 h of settling without chemical, the turbidity was further decreased by about 94%, iron 85% and zinc 50%. Coagulation-flocculation experiments indicated that both low and high molecular weight cationic polymers could provide excellent purification results in terms of turbidity. Calcium should be removed by other methods. The particles in sludge were mostly in the 2–4 μm or 10–20 μm fractions. Further sludge settling resulted in high solids removal. [ABSTRACT FROM AUTHOR]

The appearance of aerosols in condensation processes may result in a loss of condensate mass, a reduction of efficiency, pollution and damage to equipment. The presence of inert gases in condensation is frequent and can lead to the formation of aerosol particles. Equipment used in industrial condensation, gas cleaning, the removal of pollutants or the recovery of valuable substances comprise some examples of interest. The complexity of the physical phenomena occurring simultaneously makes the study of these systems difficult and it is thought that modelling might help to better understand their behaviour. A model has been developed in this study that includes the condensation of the gaseous mixture and phenomena related to the presence of liquid particles. The model solves the conservative equations for species continuity, energy and the number of liquid particles. It also includes the precipitation of liquid particles via thermophoresis, diffusiophoresis and gravitational deposition, homogeneous nucleation and coagulation induced by the Brownian movement of the particles. A condenser presenting a simple shell-and-tube geometry was selected and subjected to a unidimensional spatial discretization. The particle size interval of the aerosol population was discretized following a sectional method of moving intervals. The interaction between continuous and discrete phases was calculated as condensational growth in non-dilute and non-ideal media. Some cases were solved for water liquid particles and vapour mixed with air and a comparison was carried out using experimental data from a previous study from the literature providing a good fit. It was observed that the condensation rate is not radically altered by the presence of particles, although the persistence of remaining growing droplets dispersed in the gas could produce the aforementioned undesirable effects. [ABSTRACT FROM AUTHOR]