Pulse Cleaning Research Articles

Research and application of bag filter system for railway ballast bed coal suction vehicles: An optimization and application study.

The current bag filter system used by railway ballast bed coal suction vehicles for cleaning coal dust from railway tunnels has low operational efficiency and generates significant volumes of dust. This paper describes a simulation test unit designed to enhance the dust removal performance in railway tunnels. The flow field inside the simulation test unit is investigated under different operating conditions through numerical simulations, and the variations in air volume and working resistance, total dust collection efficiency, and optimal operating parameters of a pulse cleaning system are identified through a series of experiments. The numerical results show that the pulse cleaning system does not significantly affect the uniformity of the flow field distribution at the bottom of the filter cartridge during the process of operation. The experimental research indicates that the simulation test unit satisfies the design requirements, achieving an average total dust removal efficiency of 99.93%. A field application shows that the total dust mass concentration at the operator position can be reduced from 335.8 mg∙m-3 to 4.2 mg∙m-3, effectively improving the operating environment within the tunnel.

Experimental Investigations of the Detachment of Different Particle Structures from a Magnetizable Fiber in the Gas Phase

A current subject of research is the application of magnetic effects for the detachment of accumulated particles of fibrous collectors in gas particle separation. Initial studies have already shown the magnetically induced detachment behavior of a compact particle structure after a single deflection from a single fiber. In this study, the detachment behavior of particle structures with different morphologies from a single fiber is investigated as a function of the particle loading stage on the fiber, the external magnetic flux density, the inflow velocity and the number of regenerations of the fiber for a certain parameter range. Diffusive and more compact particle structures with non-magnetic properties are deposited on the magnetizable single fiber. By applying an external magnetic field, the fiber is magnetized and experiences a torsional moment. The deposited particle structures on the fiber are detached by the acceleration forces. The detachment of the particle structures is observed using a high-speed camera and the image sequences are analyzed. By determining the projection area before and after the fiber deflection, a degree of regeneration is calculated. With magnetic-induced regeneration, high degrees of regeneration close to 100% can be achieved. Repetitive fiber deflections improve the detachment of the particle structures. The magnetic-induced regeneration is suitable for applications where flow reversal is not possible and can be performed either online or offline. Due to the gentle regeneration, fewer emissions are produced on the clean gas side than, for example, with jet pulse cleaning. It makes it easier to achieve emission limits and simplifies product recovery.

Modeling and Cleaning Performance Optimization of Conical Filter Cartridge of Gas Turbine Intake Filter

Intake quality is crucial to gas turbines’ operation. The cartridge filter in the gas turbine intake system filters the gas and outputs a highly clean gas into the gas turbine, while pulse cleaning technology ensures the continuous and efficient operation of cartridge filters. While the current cylindrical pleated filter cartridge used in pulse cleaning usually suffers from insufficient upper cleaning, the conical pleated filter cartridge can effectively solve this issue by providing a greater upper cleaning area with significant application prospects. Despite the existing potential, research on conical filter cartridge cleaning performance is limited; thus, this paper aims to investigate the advantages of pulse cleaning using a conical filter cartridge via numerical simulation. Results demonstrate that while the conical filter cartridge enhances the cleaning strength, cleaning uniformity decreases slightly. To address this shortcoming, this paper innovatively proposes a combination of scattering nozzles and conical filter cartridges to explore the impact of the installation position of scattering nozzles on the cleaning. The modeling and cleaning performance analysis in our research illustrates that the optimal cleaning effect can be achieved under specific conditions when the scattering nozzle is installed parallel to the conical filter cartridge’s inlet. The research work in this paper provides a solution for optimizing the pulse cleaning performance of conical filter cartridges.

Cleaning up of high-energy ultrashort pulses with saturable absorbers

Pulse energy transferred from the peak to wings is inevitable in the process of ultrashort optical pulse amplification due to the accumulation of high nonlinearity, which degrades the temporal pulse quality. The energy-related saturable absorbers are applied to remove the wings of high-energy pulses without causing a severe loss of the peak in this research. A cascaded-saturable-absorbers system is proposed, and the effects of the cascaded order, low-intensity loss coefficient, saturable fluence, relaxation time and input fluence distribution on the pulse wings are numerically investigated, respectively. The obtained results can provide a general guidance of design for high-energy ultrashort pulse cleaning.

A Study of the Pulse Cleaning Process for Metal Fiber Filter Bags Based on a Discrete Phase Particle Deposition Model

Emissions of airborne particulate matter are a major cause of air pollution. A numerical approach was used to establish a single-filter-bag cleaning model based on the discrete phase particle deposition distribution law to study the effect of pulse backflushing operation parameters on the cleaning performance of the specific structure of the dust collector. It was found that increasing the pulse blowing pressure (0.2 MPa to 0.6 MPa) and extending the pulse width (0.02 s to 0.1 s) resulted in an increase in the side wall pressure of the filter bag and, thus, improved its cleaning effect. The influence of the injection pressure on the side wall pressure peak of the filter bag was more obvious than that of the pulse width. However, it cannot be concluded that the greater the injection pressure and pulse width, the better the cleaning effect. Therefore, in the actual production application, the operating cost of the equipment needs to be taken into account, as well as the amount of dust on the surface of the filter bag.

Temporal contrast improvement through cascaded second-order nonlinear processes in a thin BBO crystal.

We demonstrate temporal contrast improvement through cascaded second-order nonlinear processes in a 340-µm BBO crystal. The process was initiated by second harmonic (SH) generation, followed by difference frequency generation (DFG) between the SH and the short wavelength part of the fundamental wave (FW). The idler of DFG was selected by a spectral filter, and an output pulse energy of 573 µJ was obtained at 1 kHz with excellent spatial profile and a power fluctuation as low as 0.076% (rms) in 14 hours. The temporal contrast was improved by more than 2 orders of magnitude to approximately 1011, which could be further enhanced with different spectral filters. The excellent stability, energy scalability, and contrast enhancement ability make this simple and robust method very suitable to be integrated into the pulse cleaning system in many different ultra-intense laser facilities.

Study of a new type slit injection pipe on pulse cleaning performance to the rectangular flat pleated filter

A new slit injection pipe was designed to better clean the rectangular flat pleated filter using pulse cleaning technology. The pulse-jet performance of the slit injection pipe was compared with that of the hole injection pipe. The result showed that the pulse-jet intensity increased with the increase of tank pressure. The static pressure increased from the top to the bottom of the rectangular flat pleated filter during pulse-jet cleaning. The optimal jet distance decreased with the decrease of nozzle diameters of hole injection pipes. However, the optimal jet distance decreased as the slit nozzle width of silt injection pipes increased. Compared with the 7*D9 injection pipe, the peak positive pressures with a 120 mm jet distance at P3 and P6 increased by 441, 1339 Pa. The composite pressure and the pulse-jet uniformity increased by 744 Pa and 2.22 times, respectively. The slit injection pipe ω1 has a higher pulse injection performance.

Filter life comparison of different levels of nanofiber coated cleanable‐surface filter for gas turbine

AbstractHigh‐efficiency air filtration is a basic requirement for the most cost‐effective operation of high‐efficiency gas turbines. The filtration system protects the gas turbine from damaging debris. In gas turbine/dust collector applications, higher efficiency filtration could be achieved with nanofibers, which provide higher equipment protection than traditional media. With a nanofiber performance filter layer, the dust accumulates on the surface of the filtration media rather than within the media and could be cleaned off easily with a back pulse resulting in long filter life and a low‐operating pressure drop. In this study five type of gas tribune nanofiber coated corrugated cellulose/synthetic filter media were developed. Nanofiber coating was adjusted for five filtration efficiency level, 50 ≤ E < 60, 60 ≤ E < 70, 70 ≤ E < 85, 85 ≤ E < 95 and 95 ≤ E, pore size and filter‐life of the developed media were evaluated. One of the developed nanofiber coated media was also compared with two other commercial nanofiber coated gas tribune filter media, a glass fiber type filter media and a commercial fine fiber gas tribune filter media. It was seen that, with decreasing penetration levels due to nanofiber coating level, initial 30 cycle durations of filter life evaluation could reach about 229.9 to 250.7 min. Highest final cycle duration of 188.7 min belonged to cellulose/synthetic blend corrugated filter media with penetration of 13.66%. Nanofiber based surface filter media was cleaned up better than fine fiber media and final 30 cycle sequences were significantly higher. Surface of the nanofiber coated media was smoother when compared to fine fiber media and during the initial and final cycle test dust could not penetrate inside and could not hang to this smooth surface. So, with back pulse cleaning cake releasing have performed easily. It was also seen that, for higher filter life nanofiber coating should be uniform and robust to back pulse cleaning.

Разработка и исследование плазмохимической технологии получения смешанных оксидов урана и плутония из растворов

This paper presents the results of work on the application of plasma-chemical technology for producing uranium and plutonium oxides and their homogeneous mixtures from nitrate solutions of a given composition for the purpose of manufacturing fuel element cores. The technology is based on the process of high-temperature decomposition of aqueous solutions of salts by spraying them into a flow of the heat-transfer gas (air) heated to 5000 – 6000 K in a plasma torch. It is a highly productive short-stage process. No reagents are required for salt precipitation; there are no filtration and high-temperature treatment precipitation operations; the resulting powders are chemically active. It was found that the transformation time of salt solution drops to oxides is 0.05 – 0.10 s for the length of 0.5 – 0.7 m. The temperature in the reactor varies in the range of 1200 – 1800 K; no sintering and fusion of particles occurs. The apparatus-technological scheme of the plant has been developed. The technological equipment is made in a nuclear-safe design and installed in the exhaust boxes. The scheme includes a high-frequency induction plasmatron (plasma torch) with coaxial gas inlet into the discharge chamber. The high-frequency induction discharge is excited by inserting a grounded ignition electrode into the plasmatron discharge chamber. The plasmatron design provides the possibility of long continuous operation at high plasma temperatures with the creation of intensive plasma-jet processes for processing radioactive solutions. The reactor provides ways to prevent product accumulation on the walls (gas curtain method, electric pulse cleaning of cylindrical surfaces, vortex tangential gas supply at the level of the outlet holes of the injectors). Equipment for the separation of nanodispersed oxide powders from high-temperature steam- and powder-gas flows (vortex precipitators, filters with a metal-woven partition) has been developed and applied. The degree of oxide recovery in vortex precipitators is 88 – 92 % per stage, in filters with a metal-cloth partition the degree of purification reaches 105 – 108. Plasma-chemical oxides are nanocrystalline and nanoscale materials represented by crystalline and amorphous structures. Mixed powders are a homogeneous mixture of oxides in the form of solid solutions. The particle size does not exceed 3 μm; the crystallite size is about 10 nm. Fuel elements were manufactured from mixed powders at FGUP “Mayak”, which passed successful tests in the “Bor-60” reactor. Seven industrial fuel elements were manufactured for the BN-600 reactor, six of which were loaded into the reactor.

Preparation and performance characteristics of an environmentally-friendly agglomerant to improve the dry dust removal effect for filter material

The incomplete and uneven dust removal of a pulse filter greatly reduces the dust removal efficiency, which affects the efficiency, service life, and running resistance of dust removers. Therefore, due to improve the pulse cleaning effect, an agglomerant developed by free radical polymerization was added during dust removal. The optimal process conditions were determined by measuring the viscosity, surface tension, and atomization effect of the agglomerant solution. The phases, chemical composition, surface morphology, and morphology of the agglomerant and coal dust were characterized by infrared spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, and scanning electron microscopy. Molecular dynamics simulations were used to study the interaction mechanism between the agglomerant and coal dust. Finally, the dust removal performance under water mist conditions and agglomerate solution atomization was tested using a pulse filter. The results showed that a 0.3 % agglomerant solution effectively reduced the surface tension of the solution and displayed good wetting and bonding properties. Compared with water misting, the agglomerant solution subjected to an atomization rate of 2400 m3/h prolonged the filtration period, reduced the filtration resistance, and reduced the dust emission concentration. These results have important theoretical and practical significance for improving the dust removal effect of pulse filters.

Semi-continuous Monitoring of Cr(VI) and Cr(III) during a Soil Extraction Process by Means of an Ion Transfer Device and Graphite Furnace Atomic Absorption Spectroscopy.

Electrodialytic separation of Cr(VI) and Cr(III) followed by graphite furnace atomic absorption spectrometry for monitoring of soil extraction was studied. The sensitivity was improved by in-line purification of the solutions and bi-polar pulse cleaning. The detection limit for both Cr(VI) and Cr(III) was 0.01 μg L-1. The system was successfully used to monitor the concentration change during soil extraction with dual solution line filtration. The results demonstrate the difference in concentration changes with the different sources of Cr(VI).

Numerical Investigation of Phase-Conjugate Wave Generation as a Pulse Cleaner in Femtosecond Petawatt Laser Systems

We report on comprehensive research regarding the potential of phase-conjugate wave (PCW) generation via backward degenerate four-wave mixing process as a pulse cleaner in femtosecond high-power laser systems. We analyzed the performance of this technique by investigating the contrast enhancement capability, gain bandwidth, and energy conversion efficiency. All of these parameters are important in pulse cleaning. The numerical calculations verified that a considerably large efficiency bandwidth product and an excellent contrast enhancement capability can be realized by finding a balance between each physical effect. The simulation results based on this study provide guidance for the application of this technique in laser systems with different bandwidths. The method, which is based on PCW generation, provides new insights for femtosecond petawatt laser systems as pulse cleaners.

Experimental investigation of particle deposition in filter media during filtration cycles with regeneration by pulse jet cleaning

The objective of this study was to experimentally evaluate the influence of particle deposition on gas filtration with pulse jet cleaning. Filtration experiments were performed using dolomitic limestone particles, with polyester and polypropylene filter media. A total of 100 filtration tests were performed with a surface velocity of 4 cm/s. The stipulated maximum pressure drop was 1000 Pa, the pulse time was 200 ms, and the pulse pressure was 200 kPa. After 100 filtration cycles, the polyester filter presented higher cleaning efficiency, higher collection efficiency, lower particle retention, higher permeability, lower residual pressure drop, and lower mass retained after reverse air pulse cleaning, compared to the polypropylene filter. The results confirmed that the polyester filter presented excellent operational performance when pulse jet cleaning was used. Furthermore, surface filtration was more pronounced for the polyester filter, due to lower deposition of particles inside the filter.

Электроимпульсная очистка карнизов

Электроимпульсная очистка карнизов

Investigation to rectangular flat pleated filter for collecting corn straw particles during pulse cleaning

This work investigated the amounts of dust residual of a rectangular flat pleated filter for collecting corn straw particles during pulse cleaning and attempted to explore the causes of incomplete cleaning. In this study, dust residual, filter’s pressure drops and static peak pressures were obtained across flat pleated filter during the pulse cleaning. The optimum parameters were obtained that the pulse electromagnetic valve size was one inch, the pulse pressure was 0.2–0.3 MPa, and the filtration velocity was 0.6 m/min for the nozzle type with 7 holes with a diameter of 7 mm (7 × Ф7 mm). Under this condition, the experimental results show that the dust residuals were 198.4 (64%), 52.7 (17%), 58.9 (19%) g for initial collected dust residual 310 g at top, middle and bottom areas of the filter panel, respectively. The dust residuals were major on the top area of the filter panel, especially on the gap locations between the two-adjacent pulse airflows. Meanwhile, the more pulse interval or dust concentration was increased the dust residuals of the filter panel and the pressure drops of the filter were increased. Moreover, the static peak pressure distribution can give guidance to the dust residual distribution.

Study of Pulse Cleaning Process in Metal Fiber Filters

Three kinds of FeCrAl fibers with different pore sizes were prepared by design, fabrication, sintering and repression. The pore size, resistance and capacity were tested. The results show that the initial resistance and efficiency is reduced, while the capacity is increased with the increase of pore size. The pulse-jet cleaning of fibers were operated based on VDI3926 standard at different face velocity and cleaning pressure. The result indicates sample 3 with 22 μm fiber diameter have the longest cleaning lifespan. The four stages of the standard VDI3926 are completed in the face velocity of 0.06 m/s, the dust concentration of 2 g/m 3 and pressure drop prior to pulse-jet cleaning is 3500 Pa. The sample increment weighing reaches 12.31 g, the average efficiency is as high as 98.5% and consumed time is 3 h after 30 times artificial aging. The fiber with 22 μm diameter shows the longest lifespan.

An analysis of a reverse pulse cleaning process using high-flow pleated fabric filter cartridges

Abstract A high-flow fabric filter cartridge with a high pleat ratio, along with a large diameter, and a large filtration area, showed increased susceptibility to incomplete cleaning, caused by the greater variation of pulse airflow in the filter cartridge. In order to investigate the cleaning characteristics of high-flow pleated fabric filter cartridges, a pleated fabric filter cartridge (Φ325 × Φ215 × 1000 mm) was used to the experiment. Then, the peak pressure distribution along the height of the filter cartridge with five measurement locations was recorded using five pressure transducers. The process of dust cake born off the filter cartridge was photographed using a high-speed camera. The cleaning process of a high-flow filter cartridge was examined, and the peak pressure variation on the filter cartridge was determined during the pulse cleaning. The results show the following: the process duration of the dust cake born off the filter cartridge was 372 ms. The maximum peak pressures were 4932, 14,026, 3998, 8813, and 1962 Pa from the top to the bottom along the height of the filter cartridge, respectively. The peak pressure and duration formed by the pulse airflow are indicative of the cleaning process of dust cake born off filter cartridge. Although a peak pressure high to 673 Pa appears at location one with the first transient time, only a minor amount of dust particles was born off filter cartridge. Therefore, the process of quartz particles born off the entire filter cartridge was not only related to the peak pressure, but also to the duration. Meanwhile, the experiment shows that an increase in the pulse width can decrease the likelihood of dust particles being reattached on the bottom of the filter cartridge. The peak pressures increase on the filter cartridge when the pleat number decreases from the 155 to 125. This can decrease the incidence of incomplete cleaning.

Functional surface modification of PVDF membrane for chemical pulse cleaning

Membrane fouling research has become a focus, significant amount of work has been dedicated to membrane surface modification for improving anti-fouling performance. However, fouling still occurs, which means cleaning is inevitable. The present method is mainly inefficient offline chemical cleaning using specialized chemicals. So we put forward a new method of online chemical pulse cleaning accomplished by designing a kind of pH responsive molecular structure on the PVDF membrane surface, which was prepared through wet chemical strategy, under basic conditions, by using diethylenetriamine (DETA) as carrier of amino groups, and then these amino groups were activated with maleic anhydride (MAH) in order to introduce carboxyl groups. The modified membranes were characterized by attenuated total reflectance-Fourier transform infrared spectra (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), mechanical property, streaming potential and contact angle measurements. The results of water flux and swelling degree revealed the flexible chains had excellent pH-responsive. And the modified membranes showed outstanding anti-pollution capability and online chemical pulse cleaning effect when used to separate soybean oil-in-water emulsion and BSA solution. Meanwhile, the flux recovery rates after five times circulation could still reach 90.3% and 95.2%, respectively. This study provides a new way for building antifouling surface and improving cleaning efficiency.

The contribution of small leaks in a baghouse filter to dust emission in the PM2.5 range—A system approach

The contribution of leakage in a baghouse filter (defined as a short circuit between the upstream and downstream sides of the filter) to the emission of fine particles is quantified in comparison to other dust emission sources, and the influence of key operating variables on overall system response is analyzed. The study was conducted on a well-maintained pilot-scale filter unit (9 bags of 500g/m2 calendered polyester needle felt; total surface area 4.2m2) operated in Δp-controlled mode over a range of pulsing intensities, with two types of test dust (one free-flowing and the other cohesive) at inlet concentrations of 10 and 30g/m3. Leaks included single holes between 0.5 and 4mm diameter, intentionally placed in either the plenum plate or one of the filter bags, as well as seamlines from bag confectioning. Emissions were separated by source into a transient contribution due to dust penetration through the filter bags after each cleaning pulse, and a continuous contribution from leaks. This separation was based on a novel method of data processing that relies on time-resolved concentration measurements with a specially calibrated optical particle counter. Tiny leaks on the order of 1mm generated the same emission level as all the bags combined, and dominated continuous emissions. The equivalent leak cross section (leakage=media emission) was about 1ppm of the total installed filter surface, independent of upstream dust concentration. Leakage through open seamlines amounted to 75% of media emissions in case of free-flowing test dust. Leakage was restricted to aerodynamic diameters less than ∼5μm (roughly the PM2.5 mass fraction). For comparison, time-averaged mass penetration through conventional needle-felt media ranged from about 10−5 to 10−6, depending on cohesiveness of the particle material and pulse cleaning intensity, giving emission levels between about 0.02 and 0.2mg/m3 at the reference concentration of 10g/m2.

Numerical analysis on the gas flow dynamics from a rectangular slot-nozzle for pulse cleaning of filter unit

The flow dynamics of the pulse-jet gas around a rectangular slot-nozzle was analyzed numerically to predict the effects of nozzle shape and dimension on the pulse cleaning performance. The entrainment ratio and pressure magnitude along the nozzle axis were analyzed using Computational Fluid Dynamics (CFD) around a 3-D rectangular slot-nozzle of venturi shape and specified as the index to evaluate the cleaning effect. The influence of both the convergent ratio in the narrow direction (Rch) and in the wide direction (Rcw) as well as the divergent ratio (Rdw) in the wide direction of the nozzle was discussed, respectively. It was discovered that among of Rch, Rcw and Rdw, the flow dynamics were most sensitive to changes of Rch. Thus, the entrainment effect increased with increases of Rch, Rcw and Rdw, respectively, while the total mass of the entrained-air increased inversely. The dimensionless correlations for the entrainment ratio according to the relative variables of Rch, Rcw and Rdw were also developed to predict the entrainment ratio for the nozzle of different sizes compared with the reference novel nozzle proposed in the study.