scholarly journals CFD and Laboratory Studies of Dust Cleaning Efficacy of an Efficient Four Stage Non-Clogging Impingement Filter for Flooded-Bed Dust Scrubbers

2021 ◽  
Author(s):  
Ashish Ranjan Kumar ◽  
Neeraj Gupta ◽  
Steven Schafrik
Keyword(s):  
Laboratory Experiments ◽  
Computer Models ◽  
Dust Particles ◽  
Airflow Rate ◽  
Water Spray ◽  
Laboratory Studies ◽  
Cleaning Efficiency ◽  
Industrial Dust ◽  
Dust Filter ◽  
Cleaning Efficacy

Abstract Fibrous-type filters are used to capture dust particles in mining and other occupations where personnel are exposed for prolonged periods. Dust cleansing systems including flooded-bed dust scrubbers use these mesh-type multi-layered filters. These filters trap dust particles efficiently on their surface and inside their mesh. However, their continued operation leads to dust build-up and subsequent clogging. This results in increased resistance of the filter and lowered airflow rate through the scrubber. This could potentially enhance the exposure of the miners. A non-clogging self-cleaning impingement screen type dust filter was designed by the authors for use in mining and industrial dust cleansing applications. The filter guides dirt-laden air through rapidly turning paths which forces it to shed heavier particles. The particles impact one of the impermeable solid metallic filter surfaces and are removed from the airstream. A full cone water spray installed upstream prevents any surface build-up of dust. This paper summaries the computer models generated to show the filter operations and laboratory experiments including optical particle counting to establish the cleaning efficiency.

scholarly journals Laboratory Determination of Coal Dust Cleaning Efficacy of a Fibrous Filter for Flooded-Bed Dust Scrubber

Minerals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 295
Author(s):  
Neeraj Gupta ◽  
Ashish Ranjan Kumar ◽  
Steven Schafrik
Keyword(s):  
Water Flow ◽  
Coal Dust ◽  
Dust Concentration ◽  
Dust Particles ◽  
Fibrous Filter ◽  
Cleaning Efficiency ◽  
Variable Frequency Drive ◽  
Room And Pillar Mining ◽  
Set Up ◽  
Cleaning Efficacy

Fibrous-type dust filters are used in flooded-bed dust scrubbers to capture dust from underground room and pillar mining atmospheres. They have 10–30 layers of finely woven strands that trap particles through the interception and impaction process. A full-cone water spray is installed upstream of the filter, which floods the screen. A scrubber’s efficacy is usually measured and reported in terms of reduction in gravimetric dust concentration at a known location in a mine. This paper reports the particle-size-dependent dust removal efficiency of a fibrous filter obtained from an instrumented test-set up. A variable frequency drive and an inline flow control knob were used to control the airflow through the filter and water flow onto the filter. Optical particle counting of coal dust particles upstream and downstream was carried out to determine the cleaning efficacy. Experiments showed an increase in cleaning efficiency for all the dust particles with their size. A progressive decrease in dust concentration downstream of the filter with an increase in water flow through the nozzle affirmed the capture of dust particles by water sprays.

Investigation of the different particle size dust releases from rigid filter candles during pulse-jet cleaning

2021 ◽  
pp. 095440622110179
Author(s):  
Xin Luan ◽  
Zhongli Ji ◽  
Longfei Liu ◽  
Ruifeng Wang
Keyword(s):  
Particle Size ◽  
Critical Role ◽  
Operating Conditions ◽  
Solid Particles ◽  
Dust Particles ◽  
Cleaning Efficiency ◽  
Term Operation ◽  
Cleaning Performance ◽  
Experimental Apparatus ◽  
Pulse Jet

Rigid filters made of ceramic or metal are widely used to remove solid particles from hot gases at temperature above 260 °C in the petrochemical and coal industries. Pulse-jet cleaning of fine dust from rigid filter candles plays a critical role in the long-term operation of these filters. In this study, an experimental apparatus was fabricated to investigate the behavior of a 2050 mm filter candle, which included monitoring the variation of pressure dynamic characteristics over time and observing the release of dust layers that allowed an analysis of the cleaning performance of ISO 12103-1 test dusts with different particle size distributions. These results showed the release behavior of these dusts could be divided into five stages: radial expansion, axial crack, flaky release, irregular disruption and secondary deposition. The cleaning performance of smaller sized dust particles was less efficient as compared with larger sized dust particles under the same operating conditions primarily because large, flaky-shaped dust aggregates formed during the first three stages were easily broken into smaller, dispersed fragments during irregular disruption that forced more particles back to the filter surface during secondary deposition. Also, a “low-pressure and long-pulse width” cleaning method improved the cleaning efficiency of the A1 ultrafine test dust from 81.4% to 95.9%.

scholarly journals Heterogeneous reactions of mineral dust aerosol: implications for tropospheric oxidation capacity

2017 ◽  
Author(s):  
Mingjin Tang ◽  
Xin Huang ◽  
Keding Lu ◽  
Maofa Ge ◽  
Yongjie Li ◽  
...  
Keyword(s):  
Mineral Dust ◽  
Dust Aerosol ◽  
Heterogeneous Reactions ◽  
Dust Particles ◽  
Laboratory Studies ◽  
Research Strategies ◽  
Aerosol Composition ◽  
Oxidation Capacity ◽  
Open Questions ◽  
Modelling Studies

Abstract. Heterogeneous reactions of mineral dust aerosol with trace gases in the atmosphere could directly and indirectly affect tropospheric oxidation capacity, in addition to aerosol composition and physicochemical properties. In this article we provide a comprehensive and critical review of laboratory studies of heterogeneous uptake of OH, NO3, O3, and their directly related species as well (including HO2, H2O2, HCHO, HONO, and N2O5) by mineral dust particles. Atmospheric importance of heterogeneous uptake as sinks for these species are assessed (i) by comparing their lifetimes with respect to heterogeneous reactions with mineral dust to lifetimes with respect to other major loss processes and (ii) by discussing relevant field and modelling studies. We have also outlined major open questions and challenges in laboratory studies of heterogeneous uptake by mineral dust and discussed research strategies to address them in order to better understand the effects of heterogeneous reactions with mineral dust on tropospheric oxidation capacity.

Persistent, vertical-migration rhythms in benthic microflora.: II. Field and Laboratory Studies On Diatoms From The Banks Of The River Avon

1966 ◽  
Vol 46 (1) ◽  
pp. 191-214 ◽  
Author(s):  
F. E. Round ◽  
J. D. Palmer
Keyword(s):  
High Temperatures ◽  
Vertical Migration ◽  
Laboratory Experiments ◽  
Biological Clock ◽  
Diatom Species ◽  
Laboratory Studies ◽  
Natural Conditions ◽  
Constant Illumination ◽  
Different Temperatures ◽  
Clock Hypothesis

The vertical migration of two Euglena species and several diatom species into and out of the sediment on the banks of the River Avon has been studied under natural conditions. All species have been shown to migrate vertically upwards when exposed during daylight. Tidal flooding of the sediment is generally preceded by re-burrowing of the algae beneath the surface. Methods have been devised to follow these migrations in both the field and laboratory. Laboratory experiments show that these migrations are rhythmic, continuing under constant illumination and temperature and removed from tidal influence. The effect of three different temperatures and three different light intensities has been investigated. Transfer from low to high temperatures has been shown to reset the phase of the rhythm. The results are discussed in relation to other work and to the ‘biological clock’ hypothesis.

scholarly journals Oxidation of atmospheric reduced sulphur compounds: perspective from laboratory studies

1997 ◽  
Vol 352 (1350) ◽  
pp. 171-182 ◽  
Author(s):  
A. R. Ravishankara ◽  
Yinon Rudich ◽  
Ranajit Talukdar ◽  
Stephen B. Barone
Keyword(s):  
Boundary Layer ◽  
Laboratory Experiments ◽  
Marine Boundary Layer ◽  
Field Observations ◽  
Dimethyl Sulphide ◽  
Laboratory Studies ◽  
Sulphur Compounds ◽  
Complex Sequence ◽  
End Products ◽  
Reduced Sulphur Compounds

Results of laboratory experiments which address the course of the OH + DMS (dimethyl sulphide) reaction in the atmosphere are presented. It is shown that OH reacts via a complex sequence of reactions to produce CH 3 S and other products, and argued that NO 3 is unlikely to be an important oxidizer of DMS in the marine boundary layer (MBL) because it is very efficiently taken up by water droplets. A simplified mechanism for the oxidation of DMS in the troposphere is presented. This mechanism explains some of the field observations on the end products of DMS oxidation and their variations with temperature.

scholarly journals Laboratory measurements of stomatal NO<sub>2</sub> deposition to native California trees and the role of forests in the NO<sub><i>x</i></sub> cycle

2020 ◽  
Author(s):  
Erin R. Delaria ◽  
Bryan K. Place ◽  
Amy X. Liu ◽  
Ronald C. Cohen
Keyword(s):  
Laboratory Experiments ◽  
Field Measurements ◽  
Large Degree ◽  
Laboratory Studies ◽  
Laboratory Measurements ◽  
Deposition Fluxes ◽  
Deposition Velocities ◽  
Direct Laser ◽  
Leaf Level

Abstract. Both canopy-level field measurements and laboratory studies suggest that absorption of NO2 through the leaf stomata of vegetation is a significant sink of atmospheric NOx. However, the mechanisms of this foliar NO2 uptake and their impact on NOx lifetimes remains incompletely understood. To understand the leaf-level processes affecting ecosystem scale atmosphere-biosphere NOx exchange, we have conducted laboratory experiments of branch-level NO2 deposition fluxes to six coniferous and four broadleaf native California trees using a branch enclosure system with direct Laser Induced Fluorescence (LIF) detection of NO2. We report NO2 foliar deposition that demonstrates a large degree of inter-species variability, with maximum observed deposition velocities ranging from 0.15–0.51 cm/s during the daytime, as well as significant stomatal opening during the night. We also find that the contribution of mesophyllic processing to the overall deposition rate of NO2 varies by tree species, but has an ultimately inconsequential impact on NOx budgets and lifetimes. Additionally, we find no evidence of any emission of NO2 from leaves, suggesting an effective uni-directional exchange of NOx between the atmosphere and vegetation.

scholarly journals Properties and cleanability of new and traditional surface materials in cattle barns - a field study

2008 ◽  
Vol 17 (3) ◽  
pp. 227 ◽  
Author(s):  
R. KUISMA ◽  
H-R. KYMÄLÄINEN ◽  
M. HELLSTEDT
Keyword(s):  
Field Study ◽  
Laboratory Experiments ◽  
Laboratory Studies ◽  
Surface Materials ◽  
Colour Changes ◽  
The Difference ◽  
Coated Surfaces ◽  
One Year ◽  
The One

In this study surface properties and cleanability of new and traditional surface materials in cattle barns were examined in a field test. The concrete and plastic-coated samples were placed on a walking path on the floor and on a feeding table in a cattle barn. The surfaces were characterized using colorimetric and gloss measurements and determination of topography. In most cases, the colour of the surfaces placed on the floor darkened during the one year study period, whereas the colour changes of the samples placed on the feeding table did not show a similar trend. However, in both locations the plastic-coated surfaces were generally the easiest to clean, and the highest colour changes indicating soil residues were detected on the uncoated and silane-impregnated concrete surfaces. The difference between the locations was also seen in the gloss values, which increased in the samples placed on the floor during the one-year test period but varied considerably between the different materials on the surfaces placed on the feeding table. This field study confirmed the observation from earlier laboratory studies that plastic coatings improved the cleanability of concrete cattle barn surfaces. Silane impregnation was not functionally competitive with the plastic coatings. In general, the cleanability results were in accordance with the results of previous laboratory experiments but the field study provided practical information about the behaviour of the surface materials examined.;

LABORATORY AND GREENHOUSE STUDIES ON EFFECT OF LIME AND OTHER AMENDMENTS ON WATER-SOLUBLE BORON IN SOIL

1958 ◽  
Vol 38 (1) ◽  
pp. 27-35 ◽  
Author(s):  
R. F. Bishop ◽  
R. L. Cook
Keyword(s):  
Sodium Hydroxide ◽  
Soil Ph ◽  
Laboratory Experiments ◽  
Boron Content ◽  
Magnesium Carbonate ◽  
Water Soluble ◽  
Plant Analysis ◽  
Laboratory Studies ◽  
Ph Values ◽  
Calcium And Magnesium

Greenhouse and laboratory experiments were used to study the effect of various soil amendments on the water-soluble boron content of a strongly acid soil.In the greenhouse, using ladino clover as the test crop, liming reduced boron availability as measured by soil and plant analysis. Calcium-boron ratios in the clover ranged from approximately 550:1 to 2000:1 and there was a significant correlation between the water-soluble boron in the soil and the boron content of the clover.In the laboratory studies calcium and magnesium carbonates were equally effective in decreasing water-soluble boron in soil. Gypsum was ineffective. Manure or alfalfa hay increased the water-soluble boron content of soil in proportion to the amounts applied. Applications of sodium hydroxide, resulting in a range of soil pH values from 4.82 to 9.72, were accompanied by decreases in water-soluble boron until a pH of approximately 8.0 was reached. Above this point water-soluble boron increased. At comparable pH values of approximately 7.0 or less, sodium hydroxide caused a smaller reduction in water-soluble boron than did either calcium or magnesium carbonate.

Precision Cleaning in a Production Environment with High-Pressure Water

1992 ◽  
Vol 35 (4) ◽  
pp. 34-44
Author(s):  
R. Nagarajan ◽  
R. Welker
Keyword(s):  
High Pressure ◽  
Chlorinated Solvents ◽  
Disk Drive ◽  
Water Spray ◽  
Production Environment ◽  
Cleaning Efficiency ◽  
Contamination Control ◽  
Advantages And Disadvantages ◽  
Production Run ◽  
Pressure Water

The increasing contamination control requirements for disk drives, and the prevailing mandate to climinate chlorinated solvents in cleaning applications have allowed high-pressure water spray to emerge as an effective and environmentally sound method for cleaning. Certain substrates, such as machined metals and alloys, can be cleaned using high-pressure water to state-of-the-art cleanliness levels. Following developmental investigations in the laboratory, two cleaners utilizing high-pressure (up to 3000 psig), high-flow (up to 50 gpm) water have been procured for use at suppliers of critical disk-drive components. Acceptance-runoff, certification, and production-run cleanliness data pertaining two the two high-pressure cleaners are presented here in terms of liquid-born particle counts on contaminants extracted from substrates ultrasonically, or by means of a low-pressure water spray. Results indicate that residual particulate contamination levels on high-pressure sprayed parts may be lower by more than two orders of magnitude compared with those obtained by more conventional cleaning methods. The cleaning efficiency increases significantly with particle size. The importance of nozzle manifold design and placement, for both cleaning and drying, is demonstrated quantitatively with examples of the deleterious consequences of not optimizing them. The underlying cleaning mechanism is explained briefly. Potential advantages and disadvantages associated with high-pressure water spray cleaning are fully discussed, and recommendations are offered for utilizing this technology most effectively.

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