Filtration Elements Research Articles

Research and development of a mature and reliable method for filtration of hot producer gases

The paper aims to summarize the technical and process development of hot gas filtration technology that was tested and optimized under the conditions of producer gases generated through the gasification of wood chips in afixed-bed 60kWth GazEla reactor. The paper describes the results of testing two generations of hot gas filters, four types of filtration elements, as well as a range of auxiliary subunits (i.a. methods for secure fixing and sealing of the filters). Additionally, an in-depth analysis was performed on the efficiency of pulse-jet cleaning, which through a statistical study indicated change-effect relationships between the main pulse-jet parameters. Based on this learning curve, the paper presents a set of guidelines that can be used for the development of robust hot gas filters, as well as for resolving their unstable operation.

Изменение состава перифитона элементов фильтрации установок замкнутого водоснабжения при совместном воздействии УФ-излучения и ультразвука

The article considers the effect of ultraviolet (UV) radiation and ultrasound (US) on the qualitative and quantitative indicators of the filtration elements periphyton in a recirculation aquaculture system (RAS) under different treatment regimens. It is assumed that the combined effect of UV and US will improve the efficiency of water purification in the RAS and also contribute to the elimination of pathogenic microorganisms. It was shown that the maximum diversity of periphyton organisms was observed in the absence of UV and US action. A total of 26 taxonomic units were found, with some of them categorized as unclassified (Unclassified_Rotifer; Unclassified_Nematode). High relative frequency of occurrence was noted for the species Arcella vulgaris (16.86%), Centropyxis aculeata (21.03%), and Arcella sp. (16.86%) of the testate amoebae class in the control group. Ciliates were also represented by a large number of species. Of 10 infusoria 6 belonged to free-living forms and 4 to sessile forms. Vorticella convallaria (16.21%), Stylonychia pustulata (13.98%), Zoothamnium sp. (13.98%) had the highest relative occurrence in the control. Ultraviolet radiation led to changes in the abundance of certain groups of hydrobionts, in particular, representatives of ciliates and oligochaetes. Using a UV source reduced the relative frequency of Arcella sp. and Centropyxis sp. to 3.33 and 6.66% correspondingly, relative to the control. The combined impact of US and UV caused a significant decrease in the relative frequency of Ciliate and Oligoheata, but had little effect on testate amoebae and rotifers. According to the results obtained, it can be supposed that the presence of an additional source of US radiation contributes to the reduction of the number of free-living forms of parasitic infusoria and can prevent the development of microbial and parasitic diseases. Thus, additional studying the biofilter microbial community under the influence of UV and US radiation is required.

Novel porous ceramic with high strength and thermal performance using MA hollow spheres

The objective of this work is to obtain a multifunctional porous ceramic material at low cost with improved properties and that can be used in many applications like: thermal and acoustic insulation, refractory support and hot gas filtration elements. To that end, a novel facile strategy to fabricate porous ceramics by foaming and pore-forming agent methods using magnesia-aluminum spinel hollow spheres (MASHSs) was reported for the first time, in which calcium aluminate cement (CAC) served as high-temperature binder. The influence of temperature ranging from 1500 ​°C to 1700 ​°C on the thermal conductivity, porosity and mechanical strength were investigated. The results show that, the obtained MASHSs ceramic exhibits high porosity (67.2–71.9%) and thermal conductivity (0.18–0.38 ​W/mK), and compressive strength (6.1–17.1 ​MPa), which is mainly due to the change in crack directions and microstructure optimization with the prolong of firing temperature. The crack directions changed from the surface of MASHSs to the interior MASHSs, which consumes more crack energy, and thus leading to the excellent mechanical performance. What is more, the introduction of MASHSs makes it difficult to lose heat at elevated temperature, and thereby improving the thermal conductivity of materials.

САМООЧИСНИЙ ФІЛЬТР ДЛЯ ЗАМКНУТИХ ГІДРОСИСТЕМ СІЛЬСЬКОГОСПОДАРСЬКОГО ОБЛАДНАННЯ

The issue of increasing the reliability and durability of hydraulic units of closed hydraulic systems of agricultural equipment is considered, due to better cleaning of the working fluid by filtration units. The design of a self-cleaning filter with hydraulic automatic control of backwashing of slotted filtration elements with a counterflow of the working fluid is proposed. A special stand has been developed for simulating the operation of a self-cleaning filter of closed hydraulic systems of agricultural equipment. Experimental studies on a special stand confirmed the efficiency of the proposed design and made it possible to identify its main advantages in comparison with domestic and foreign counterparts. Based on the analysis of transient processes with increased pressure pulsation of agricultural equipment of a closed hydraulic drive, the actual pressure drop at which automatic flushing is triggered was established, compared with the calculated one, in which it was impossible to take into account such real factors as friction in the sealing units, the characteristics of the springs, distortions, tightness of valve pairs, fluctuations in dimensional chains. The most optimal operating mode of auto-washing equipment with a choke diameter of 1.0 mm has been determined. The auto-washing equipment was switched on at a pressure drop of 1.5 MPa (15 atm) and in an improved mode – pressure pulsations with an amplitude of 2 MPa (20 atm) when the auto-wash was turned off decreased in time to 0.12 s. It is noted that the developed self-cleaning filter for closed hydraulic systems of agricultural equipment will improve the reliability and increase the service life of the elements of hydraulic units and the machine itself as a whole.

COMPREHENSIVE FILTRATION SYSTEM FOR CLOSED HYDROSYSTEMS OF AGRICULTURAL EQUIPMENT

The article the issue of increasing the durability and reliability of units of closed hydraulic systems of agricultural equipment by ensuring the purity of the working fluid is considered. The analysis of existing systems of filtration of working liquid for the closed hydraulic systems of the agricultural equipment is resulted. It is noted that the basis of the created and implemented filtration systems are filtration installations in pressure mains, including with automatic washing, which provide filtration fineness up to 50 μm, filter elements which have high strength, reliability and are capable of countercurrent washing at working pressure of hydraulic system. The complex system of filtration of working liquid for the closed hydraulic systems of the agricultural equipment is offered. The filtration system of the working fluid provides for the use of filters with backwash and filtration elements with a slit-like brass wire of round cross section. The total length of the filtration gap of one filtration element with a width of 0.05 mm is 40 m The filter provides passive cleaning technology - countercurrent flushing, as the simplest in design, easy to manufacture and sufficiently efficient and cheap. Feature of the filtration installation is a possibility of washing of its filtration elements by a countercurrent of working liquid. The signal for flushing is the occurrence of a pressure drop on the filter, which can be used to judge the degree of contamination and the readings of manometers installed at the inlet and outlet of a closed hydraulic system of agricultural equipment. It is noted that the developed complex filtration system for closed hydraulic systems of agricultural equipment will increase the reliability of control hydraulics at least twice and reduce costly downtime of agricultural machinery due to failure of sealed elements of hydraulic equipment.

In-situ formation of polyvinylidene fluoride microspheres within polycaprolactone electrospun mats

This study discusses the manufacture of hierarchical composite membranes via the combination of electrospinning and vapour-induced phase separation (VIPS). The fabrication approach here proposed makes possible the in-situ generation of polyvinylidene fluoride (PVDF) spherical microparticles within electrospun nonwoven mats of polycaprolactone (PCL) fibres. Morphological investigations of the PCL-PVDF membranes show that the PVDF microspheres are distributed within the whole volume of the electrospun mats and, depending on the PVDF concentration used for the VIPS process, they can form permanent joints between fibres. Consequently, the fibre-particle systems exhibit increased Young's modulus and tensile strength (up to 1.7-fold increase) if compared to PCL electrospun mats, while maintaining a porous structure. The results of this study provide a new platform for the development of fibres-based systems that find application as scaffolds for tissue engineering, drug delivery devices, filtration elements for water, wastewater and air treatment.

On homotopy equivalence of filtered spaces

We investigate the category of metric filtered spaces and establish there an analog of well-known Milnor's theorem on characterization of filtered homotopic equivalences through topological properties of filtration elements. The key ingredient of the proof consists in reduction of the filtered category to a stratified category.

Fractal Reconstruction of Microscopic Rough Surface for Soot Layer during Ceramic Filtration Based On Weierstrass–Mandelbrot Function

The microscopic surface of soot layer on the external surface of filtration elements is rather hard to reconstruct. In this study, an incinerator–filter setup was designed to mimic the capture of soot particles in flue gas to achieve the samples to construct the rough soot-layer surface. The specific velocities around the ceramic cartridge were determined by particle image velocimetry (PIV) measurement. Resorting to a box-counting method, the fractal dimensions (FDs) were determined by Richardson–Mandelbrot method with binary images of samples. Accordingly, the in situ thickness of soot layer was constructed with consideration of particle deposit and the microscopic rough surfaces were modeled by employing Weierstrass–Mandelbrot (W-M) function. Additionally, a comparison between the constructed surface and real surface achieved from the image taken by atomic force microscopy (AFM) was performed. The results suggest that all roughness deviations of constructed surface from real surface of soot layer not ex...

WRF modeling of PM2.5 remediation by SALSCS and its clean air flow over Beijing terrain

Atmospheric simulations were carried out over the terrain of entire Beijing, China, to investigate the effectiveness of an air-pollution cleaning system named Solar-Assisted Large-Scale Cleaning System (SALSCS) for PM2.5 mitigation by using the Weather Research and Forecasting (WRF) model. SALSCS was proposed to utilize solar energy to generate airflow therefrom the airborne particulate pollution of atmosphere was separated by filtration elements. Our model used a derived tendency term in the potential temperature equation to simulate the buoyancy effect of SALSCS created with solar radiation on its nearby atmosphere. PM2.5 pollutant and SALSCS clean air were simulated in the model domain by passive tracer scalars. Simulation conditions with two system flow rates of 2.64 × 105 m3/s and 3.80 × 105 m3/s were tested for seven air pollution episodes of Beijing during the winters of 2015–2017. The numerical results showed that with eight SALSCSs installed along the 6th Ring Road of the city, 11.2% and 14.6% of PM2.5 concentrations were reduced under the two flow-rate simulation conditions, respectively.

Impact of filtration elements on bioelectrical signal

Filtering of the wanted signal from the noise caused by power lines, magnetic pickup, interference from body movement, etc. in the field of medical data processing is a weighty problem of cardiography. To date, different types of digital filters have been used to clear the signal from unnecessary frequency bands. This paper presents the results of the filter simulation in MATLAB package.

Waterworks conditions in the Republic of Serbia: Use of membrane processes

Waterworks conditions in the Republic of Serbia were discussed in the paper with a special note to the usage of membrane processes. Nano filtration process and its application were reviewed. Potential solutions for clean drinking water distribution was given. Also, alternative solutions such as cisterns, existing wells and springs, small home filtration elements and Public wells with purified water were presented.

Simulation of Structural Characteristics and Depth Filtration Elements in Interconnected Nanofibrous Membrane Based on Adaptive Image Analysis

Due to their unique structural features, electrospun membranes have gained considerable attention for use in applications where quality of depth filtration is a dominant performance factor. To elucidate the depth filtration phenomena it is important to quantify the intrinsic structural properties independent from the dynamics of transport media. Several methods have been proposed for structural characterization of such membranes. However, these methods do not meet the requirement for the quantification of intrinsic structural properties in depth filtration. This may be due to the complex influence of transport media dynamics and structural elements in the depth filtration process. In addition, the different morphological architectures of electrospun membranes present obstacles to precise quantification. This paper seeks to quantify the structural characteristics of electrospun membranes by introducing a robust image analysis technique and exploiting it to evaluate the permeation-filtration mechanism. To this end, a nanostructured fibrous network was simulated as an ideal membrane using adaptive local criteria in the image analysis. The reliability of the proposed approach was validated with measurements and comparison of structural characteristics in different morphological conditions. The results were found to be well compatible with empirical observations of perfect membrane structures. This approach, based on optimization of electrospinning parameters, may pave the way for producing optimal membrane structures for boosting the performance of electrospun membranes in end-use applications.

Penetration of sub-micron aerosol droplets in composite cylindrical filtration elements

Advection–diffusion transport of aerosol droplets in composite cylindrical filtration elements is analyzed and compared to experimental data. The penetration, characterizing the fraction of droplets that passes through the pores of a filtration element, is quantified for a range of flow rates. The advection–diffusion transport in a laminar Poiseuille flow is treated numerically for slender pores using a finite difference approach in cylindrical coordinates. The algebraic dependence of the penetration on the Peclet number as predicted theoretically, is confirmed by experimental findings at a variety of aspect ratios of the cylindrical pores. The effective penetration associated with a composite filtration element consisting of a set of parallel cylindrical pores is derived. The overall penetration of heterogeneous composite filtration elements shows an algebraic dependence to the fourth power on the radii of the individual pores that are contained. This gives rise to strong variations in the overall penetration in cases with uneven distributions of pore sizes, highly favoring filtration by the larger pores. The overall penetration is computed for a number of basic geometries, providing a point of reference for filtration design and experimental verification.

Improving the technology for the tundish refining of steel in order to elevate the quality of continuous-cast semifinished products and rolled plates

An integrated technology has been developed for obtaining continuous-cast slabs to be used in rolling plates for critical applications. Special filtration elements are installed in partitions inside the tundish to reduce the content of nonmetallic inclusions in the continuous-cast semifinished product. A channeled ceramic lance for injecting the steel with argon has been developed and installed in the bottom of tundishes to remove nonmetallic inclusions 20 μm or smaller. Metallographic studies confirm the effectiveness of the new technology for obtaining plates of high-strength steels.

Localization of CsI Radioaerosols from the gas phase using various filtration elements

The behavior of 137Cs131I radioaerosols, yielded by CsI evaporation from a Pt healer into argon or air, during their localization with aqueous solutions and various filtration materials [filters based on Petryanov fabric (from here on, Petryanov filter), “while band” paper filter, and TRUMEM metallic membrane filter] was studied. The degree of localization of 137Cs131I radioaerosols was examined in relation to the amount of sublimed 137Cs131I, the number of bubblers in the system, the size of the nozzle in the bubbling system, and the gas stream flow rate. The efficiency of localization of 137Cs131I radioaerosols with a 10-layer stack of Petryanov filters from the gas stream with and without bubbling system was estimated. It was found that, at the stream velocity of 2–3 cm s−1, a 10-layer stack of Petryanov filters with the total thickness of 3 cm takes up ca. 97% of total 137Cs131I sublimed from the Pt heater. It was shown that the bubbling system does not affect the efficiency of localization of 137Cs131I radioaerosols by Petryanov filters but only favors decrease of the aerosol load on these filters. Electron-microscopic examination of the particle-size distribution of the CsI aerosols penetrating through aqueous solutions was carried out, and various filtration materials (Petryanov filter and “white band” paper filter) were tested.

Oxidative Hydrolysis of CsI Radioaerosols in a Steam-Gas Medium: A Study Using Filtration Elements

Oxidative hydrolysis of 137Cs- and 131I-labeled CsI aerosols in a steam-gas medium was studied at their localization on a column with filtration elements. At the air stream temperature of 403–423 K, water vapor content in air from 3–4 to 90 vol %, and stream velocity in the sorption column of 6–24 cm s−1, the CsI aerosols undergo oxidative hydrolysis, and the hydrolysis products react with the surfaces of the metallic and paper filtration elements. By varying the filter material, its internal surface area, and experimental conditions, it is possible to localize on the filtration elements from ∼5 to 98% of 0.17–70 mg of CsI coming to the filtration system.

Fabrication of crystalline membranes oriented in the (111) plane in a (100) silicon wafer

Anisotropic wet etching on the front and backside of a (100) silicon wafer is applied to fabricate free standing crystalline membranes oriented in the (111) plane. The effective area of the membranes is in the order of several tenths of a millimeter, whereas thickness ranges from several hundreds of microns down to less than a micron. The fabrication process requires two masks and a wet etch. Cantilevers with (111) orientation were milled from the membranes by means of a Focused Ion Beam. We propose the application of (111) oriented silicon membranes as filtration elements in a microfluidic system. Cantilevers oriented in {111} planes can be applied as (bio-) chemical sensor structures that can be integrated in the medium channel.

Special features of welding filtration elements of the cartridge type produced from porous metallic materials

Special features of welding filtration elements of the cartridge type produced from porous metallic materials

Development and Testing of a Thermoluminescence Dosemeter for Mixed Neutron-Photon-Beta Radiation Fields

A new four-element thermoluminescence (TL) dosemeter and dose evaluation algorithm have been developed and tested to better characterise personnel exposure in mixed neutron-photon-beta radiation fields. The prototype dosemeter is based on a commercially available TL card (with three 7LiF chips and one 6LiF chip) and modified filtration elements. The new algorithm takes advantage of the high temperature peak characteristics of the 6LiF element to quantify the neutron dose component better. The dosemeter was tested in various radiation fields, consisting of mixtures of two radiation types typically used for dosemeter performance testing, as well as mixtures of three radiation types to simulate possible exposure conditions. The new dosemeter gave superior performance, based on the tolerance levels, when using the new algorithm as compared to a conventional algorithm that did not use the high temperature peak methodology. The limitations and further improvements are discussed.

Experimental test to evaluate performance of an anaerobic reactor provided with an external membrane unit

The coupling of a wastewater treatment anaerobic reactor with a microfiltration or ultrafiltration membrane is particularly attractive: lower sludge production than in an aerobic reactor, methane production and dissociation of the mean residence times of the different phases. However, the industrial development of such a process is hampered by membrane fouling which can be a result of many causes and require a comprehensive study especially fouling by anaerobic suspensions. In order to simplify the study, the different phases of anaerobic oxidation were separated and this work is focused on the filtration of an anaerobic suspension fed with acetic acid as the sole carbon source at 2 g/l TOC. The effluent quality was excellent without sludge production in spite of large variation of the liquid phase space time. The tested filtration elements were tubular Carbosep membranes. The M14 membrane showed the greatest flux of 120 l/m2 h at 0.5 bar and 25 Pa shear stress and the flux increased to 180 l/m2 h when a baffle was introduced. The main fouling mechanism appears to be the particle deposition on the membrane surface as no flux decline was observed at higher cross-flow velocity.