Dissertations / Theses on the topic 'Dust control'
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Weidman, Justin Earl. "Dust Control Usage: Strategic Technology Interventions." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/26562.
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An intervention to improve adoption of dust control technology is designed, implemented and evaluated using three theoretical frameworks: the Health Belief Model (HBM), Diffusion of Innovation, and the Technology Acceptance Model. A quasi-experimental design (pretest-posttest, with control group) was used to evaluate the effectiveness of the intervention. An integrated conceptual model, employing key constructs from these frameworks, was developed to predict and describe â adoption readinessâ . Adoption readiness combines the attitudes and perceptions about a technology with the capacity to implement the technology. The primary hypothesis was that the key construct scores of the three theoretical models would improve post-intervention, particularly, â adoption readinessâ . Workers in the drywall finishing industry have been found to be at risk of developing respiratory disease and disability. Studies have shown that drywall finish workers have been subject to overexposure to dust concentrations that contain respiratory heath hazardous particles including silica, talc, mica, and calcite. Prevention through Design (PtD) solutions, which are effective at reducing dust levels, do exist for these operations. Some of these PtD solutions include using vacuum sanders, wet sanding methods, pole sanding and using low dust joint compound in lieu of using personal protective equipment (PPE) as a primary form of exposure protection. Previous studies have determined barriers to adoption of current PtD solutions for dust exposure reduction. Usability, productivity, quality of finish and cost were all identified as barriers to adoption. An intervention directed at those involved in the drywall industry is needed to increase the usage of engineered dust control.
This dissertation project developed, implemented, and evaluated three interventions to address the barriers to adoption through education and marketing strategies. Development of the interventions included strategies to improve industry usage of dust control technologies. The interventions targeted workers, small companies, and large companies involved in drywall finishing.Ph. D.
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Matar, Hattan Saleh. "Evaluating dust exposure from steel manufacturing electrical arc furnaces." Online version, 2009. http://www.uwstout.edu/lib/thesis/2009/2009matarh.pdf.
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Ramachandran, Narayanan. "MODELING AND CONTROL OF ACOUSTIC LEVITATION FOR DUST CONTROL APPLICATION." OpenSIUC, 2010. https://opensiuc.lib.siu.edu/theses/364.
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The objective is to study and model acoustic levitation by treating it as a control system problem rather than visualizing it as a physical system problem. The specific agenda is to model the acoustic levitation system and design a controller using the obtained model; this model can be used in for "Active dust control" in a closed chamber. A test-bed needs to be developed and constructed for experimental investigation and proof of concept of particle manipulation using sonic/ultrasonic waves. Acoustic standing waves are well established physical concepts, but controlling and modeling the same is a difficult control system problem because of various non-linearity that creeps in an acoustic system at high frequency. Future work would involve in designing a robust controller using the model obtained. The same needs to be extended to the 3-d acoustic dust control system.
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Glass, Emmett V. "Environmental control of house dust mites : strategies for limiting exposure to house dust mites and their allergens /." The Ohio State University, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=osu1486461246818192.
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Almuhanna, Emad Ali. "Dust control in livestock buildings with electrostatically-charged water spray." Diss., Manhattan, Kan. : Kansas State University, 2007. http://hdl.handle.net/2097/275.
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Von, Holdt Johanna RC. "Lower Kuiseb River sediments and their control on dust emission." Master's thesis, University of Cape Town, 2013. http://hdl.handle.net/11427/12755.
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Includes bibliographical references.Previous studies, using remote sensing, have identified the Kuiseb River in Namibia as the dustiest river in Southern Africa. Dust plumes detected from this basin are mostly associated with the Lower Kuiseb River, between the end of the bedrock canyon at Natab and the Kuiseb Delta towards the Atlantic Ocean. The purpose of this study was to examine the surface materials of the Lower Kuiseb River and establish their potential towards dust production, leading to such plumes. This investigation focused predominantly on the size characteristics of 153 surface sediment samples collected from the Kuiseb main channel, its terraces, delta, gravel plain surfaces and tributaries, dunes and interdune, all of which were analysed using a Malvern Mastersizer 2000 laser diffractometer. In addition, other sediment characteristics such as mineralogy, organic matter content, soluble salts; and selected surface roughness elements were also considered. Furthermore MODIS satellite imagery was used to assess the dust emission activity from each of the geomorphological units sampled in the field for the period from 2005 to 2013. This study has demonstrated surface sediments suitable for dust production to increase towards the coast with particular "dusty" floodplain surfaces between Swartbank and Rooibank, as well as the Kuiseb Delta. It appears that silt crusts formed as the flood water dissipate, provide a main source of appropriately sized material for deflation. The crusts consist entirely of silt and clay sized material, with a maximum of 97% <63μm, 39% <10μm and 6% <μm. Dust producing surfaces of the gravel plain include the gravel plain drainage, which has the largest quantity of clay sized material (maximum of 11% <μm). Anthropogenic disturbances of the surface are likely playing a role in the production of dust, with livestock farming causing a fragmentation of crusts in the river valley, and mining and off-road driving disturbing the gravel plain.
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Chen, Rui. "Bio Stabilization for Geopolymer Enhancement and Mine Tailings Dust Control." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/319999.
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The first part of the thesis investigates the enhancement of fly ash-based geopolymer with alkali pretreated sweet sorghum fiber. The unconfined compression, splitting tensile and flexural tests were conducted to investigate the mechanical properties of geopolymer composite. The results indicate that the inclusion of sweet sorghum fiber slightly decreases the unconfined compressive strength (UCS), however, the splitting tensile and flexural strengths as well as the post-peak toughness increase with the fiber content up to 2% and then decrease thereafter. A durability test program containing 10 wet/dry cycles was performed to evaluate the long-term performance of the geopolymer composite related to wet/dry cycling. The results indicate that both the UCS and the splitting tensile strength of the geopolymer composite progressively decrease with the number of wet/dry cycles. The second part of the thesis investigates the utilization of biopolymers to stabilize MT for dust control. First, a fall cone method was adopted to evaluate the Atterberg limits and undrained shear strength of MT stabilized with biopolymers. The results indicate that the inclusion of biopolymers increases both the liquid limit and the undriained shear strength of MT. Two new equations are proposed for predicting the undrained shear strength of MT based on liquid limit and water content, and liquidity index. Second, an experimental program including moisture retention, wind tunnel and surface strength tests was performed to evaluate the effectiveness of biopolymer stabilization for dust control. The results indicate that biopolymers are effective in enhancing the moisture retention capacity, improving the dust resistance, and increasing the surface strength of MT. Third, a durability test program containing 10 wet/dry cycles was applied to MT samples treated with biopolymer solutions of different concentrations. The results show that the dust resistance of MT samples progressively decreases with the number of wet/dry cycles. Finally, experimental and numerical studies on the unconfined compressive strength (UCS) of MT stabilized with biopolymer were carried out. It is found that inclusion of biopolymer into MT favors the increase of adhesion between MT particles and thus the increase of the UCS of MT.
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Freeman, Elisabeth A. "Geotextile separators for dust suppression on gravel roads." Diss., Columbia, Mo. : University of Missouri-Columbia, 2006. http://hdl.handle.net/10355/4503.
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Thesis (M.S.)--University of Missouri-Columbia, 2006.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (February 7, 2007) Includes bibliographical references.
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Hakim, Huma E. "The agglomeration of cement to facilitate transportation." Morgantown, W. Va. : [West Virginia University Libraries], 1999. http://etd.wvu.edu/templates/showETD.cfm?recnum=988.
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Thesis (M.S.)--West Virginia University, 1999.Title from document title page. Document formatted into pages; contains xii, 91 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 76-78).
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Zhang, Guobin. "Performance of reduced-scale vortex amplifiers used to control glovebox dust." Thesis, University of Central Lancashire, 2005. http://clok.uclan.ac.uk/20086/.
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Ventilation systems for a nuclear plant must have a very high reliability and effectiveness. In this application, fluidic devices have advantages which electro-mechanical and pneumatic devices lack. Fluidic devices will not easily wear out, they have a relatively fast response and in some cases they may be cheaper than an equivalent conventional device. Most importantly, they have fewer moving parts (usually none) so are inherently reliable, so long as the fluidic design is effective. So vortex amplifiers (VXA) are ideal for active ventilation systems where access for maintenance is problematic. From 1995 to 2000, space limitations at Sellafield drove the desire to minimise VXA size and also glovebox size. Recently completed plant expansions use a smaller version of VXA produced by scaling geometrically the existing standard model. It is called the mini-VXA. Subsequent performance of the mini-VXA has been disappointing with high oxygen levels noted in the inerted gloveboxes; this required an expensive increase in the inert gas supply rate of gloveboxes to mitigate against fire risk. After doing experiments using a mini-VXA and typical glovebox, the author has confirmed the high 02 levels. The 02 distribution in the glovebox indicates that oxygen is entering the glovebox by the VXA supply ports; against the general direction of flow. The ultimate source of this back leakage is the control port (that is open to atmosphere) and smoke visualisation studies on the mock VXA indicate a mechanism. This is due to separated flow patterns with excessive control port momentum. A temporary solution using an orifice plate and spacing chamber has been shown to reduce essential nitrogen supply to one quarter that without the modification. Addition of the orifice plates enables further reduction in nitrogen use, and the smallest orifice tested performs best with no discernable cost in pressure drop and therefore fan power. The author also found the following points. The ratio of control port area to supply port area is a critical parameter affecting mixing of the two airstreams. Yet exit port area is unimportant. The ratio of supply port area to exit port area has no influence on discharge coefficient (at least within the scope of current work). It is also identified that the ratio of chamber height to exit port radius does not affect the discharge coefficient or two angle parameters. Doubling chamber height, supply port area and control port area at the same time has a slight effect on the discharge coefficient (attributed partly to a viscous effect), but no effect on the two angle parameters. The chamber height has little effect on Reynolds number. If the supply port area is not too small relative to the exit port, the supply port area will not significantly affect Reynolds number. The use of discharge coefficient and the two angle parameters to characterize VXA performance breaks with the traditional form of dimensionless characteristics that are used for the purpose. Testing these alternate characteristics has enabled the momentum (which dominates control of VXA performance) to be more explicitly expressed in updated design rules.
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Bariar, Bhaskar. "Wettability Studies and its Role in Coal and Quartz Dust Control." OpenSIUC, 2013. https://opensiuc.lib.siu.edu/theses/1247.
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AN ABSTRACT OF THE THESIS OF BHASKAR BARIAR for the Masters of Science degree in Mechanical Engineering and Energy Processes presented on July 2nd, 2013, at Southern Illinois University, Carbondale. TITLE: WETTABILITY STUDIES AND ITS ROLE IN COAL AND QUARTZ DUST CONTROL. ADVISOR: Dr. Kanchan Mondal CO-ADVISOR: Dr. Y. P. Chugh This thesis presents the wettability studies conducted to determine the wettability characteristics of dust generated from different sections of typical coal seams from three Interior Basin coal mines for improved respirable coal and quartz dust (< 10μm) control. A modified form of film flotation was employed to determine absolute wettability (AW) which is a measure of the maximum wettability of a particular material in a given wetting fluid. AW was evaluated as a function of surface tension of the wetting fluid and surfactant concentration in the base wetting fluid which was water. Coal seam samples were found to be 89-96% wettable with water alone and increase in wettability was observed with reduction in the surface tension or increase in the surfactant concentration in the base wetting fluid. The surface tension of the fluid was reduced by the addition of predetermined amounts of methanol to water (0 to 1.5 wt %) or surfactant concentration (0.0005 to 0.005 wt %) in water. The effect of surfactant was evaluated by analyzing the overall effect on wettability obtained due to addition of surfactant in the wetting fluid in conjunction with the wettability results obtained from experiments aimed towards evaluating the alterations to the surface properties of the coal particles due to surfactant adsorption on these particles. A new technique, developed by Mondal and Chugh, was then used to evaluate wettability rates. Wettability rates were evaluated by identical wetting fluids used for estimating absolute wettability. It was found that 64-84% of the coal (depending on the coal sample source) was wetted in just 60 seconds. In addition, both the wettability and wettability rates were correlated with particle size, quartz and surface charge partitioning into the wetted and un-wetted fractions. Contrary to the popular belief that finer particles are difficult to wet, results from absolute wettability studies showed that larger fraction of the finer particles were wetted in water as compared to the coarser particles. On the other hand, it was found that the rate of particle capture by wetting and subsequent settling was higher for coarser particles. It was generally found that the quartz recovery was a function of the wettability of the coal sample. From the wettability rate studies, it was observed that the incremental quartz capture reached a maximum value within the first 20 seconds. Additional research should be conducted to assess wetting of different particle size coal and quartz dust. It is recommended that different types of surfactants be tested and additional characterizations should be developed for organic fraction recovery in the wetted fraction.
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McLellan, P. G. "Control of rectifier equipment used for electrostatic precipitation." Thesis, Open University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375938.
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Aitken, Robert John. "Methods for the optimisation of filtration systems for pollution control in deep mine environments." Thesis, University of Nottingham, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260602.
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Marstorp, Gustav. "Automated Control System for Dust Concentration Measurements Using European Standard Reference Method." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-292583.
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Most companies that have any type of combustion or other pollution process via emission to air needs to measure their emissions to ensure they are within legal boundaries. Among the different types of pollution measurements, one of the most common is dust concentration, also known as particle concentration. An important factor in dust concentration measurements is to ensure that the concentration of the measured dust is representative to the dust concentration in the emissions. This is measured in isokinetic deviation, defined as (vn vd)=vd, where vn is the velocity in the entry nozzle and vd the velocity in the duct. Methods of dust concentration measurements used today are dependent on manual tuning and sensor readings, and the isokinetic deviation is calculated after a test. The focus of this project was therefore to investigate how the process of dust concentration measurements using standard reference methods could be automated in the way that isokinetic sampling is controlled and regulated by an automated control system in real time. Pressures, temperatures and sampled gas volume were quantized. A PIDcontroller was designed, implemented and tested. The PID-controller took the differential pressure between the inside of the entry nozzle and the duct, called zero pressure, as input. The system was tested in a laboratory environment by letting a radial fan create a flow, and thus create a zero pressure of -60 Pa, meaning that the pressure in the duct was 60 Pa greater than the pressure inside the entry nozzle. The PID-controller was then enabled and ran for five minutes. The result showed that the PID-controller managed to control the system to the reference point in less than 50 seconds for entry nozzles of diameters 6 mm, 8 mm, 10 mm and 12 mm. The results of the isokinetic deviations were -12 %, -5 %, -6 % and -4 % for entry nozzles with diameters 6 mm, 8 mm, 10 mm and 12 mm respectively. This is higher than the accepted values according to the European standard, which allows deviations in the interval -5%to 15%. However, these tests ran for relatively short time periods and started with large deviations which made it difficult to reach an isokinetic deviaiton in the accepted interval. Possible improvements could be to include the real time isokinetic deviation in the PID-controller, this would make it possible to change the reference value of the zero pressure in real time and guarantee isokinetic deviations in the accepted interval, even in extraordinary situations.EU-regler ställer krav på anläggningar att kontrollera och begränsa sina utsläpp av stoft enligt EU standard 13284-1:2017. Vid en stoftmätning måste det tas hänsyn till många parametrar, där en av de viktigaste parametrarna är att provtagningen ska utföras isokinetiskt. Isokinetisk provtagning innebär att hastigheten i kanalen (skorstenen) är samma som i sonden där provgasen sugs ut. Dagens metoder för stoftmätning förlitar sig på manuella inställningar och den isokinetiska avvikelsen beräknas efter ett test. Det resulterade i frågeställnigen hur en automatiserad metod för bestämning av masskoncentration av stoft kan utformas så att den isokinetiska avvikelsen beräknas i realtid. Tryck, temperatur och gasvolym kvantiserades från analoga sensorer och kommunicerades till en mikrokontroller med det seriella protokollet I2C. En PID-reglator designades, implementerades och testades. PID-regulatorn tog tryckskillnaden mellan kanal och sond som insignal. Utsignalen från PID-regulatorn var en spänning som via en motordriven ventil kontrollerade inflödet i munstycket. Systemet testades i laborativ miljö genom att låta en fläkt skapa ett flöde tills den uppmätta tryckskillnaden mellan sond och kanal var -60 Pa. Därefter aktiverades PID-regulatorn och testet pågick sedan i fem minuter. Testet utfördes för munstycken med diameterna 6 mm, 8 mm, 10 mm och 12 mm. Resultatet visade att PID-regulatorn styrde systemet till referenspunkten på mindre än 50 sekunder för samtliga diametrar på munstyckena. De isokinetiska avvikelserna (skillnaden i hastighet mellan munstycke och kanal) beräknades till -12 %, -5 %, -6 % och -4 % för munstyckena 6 mm, 8 mm, 10 mm och 12 mm. I två av fallen var det högre än det accepterade värdet enligt EU standarden som tillåter avvikelser inom intervallet -5 % till 15 %. Det kan förklaras av att testen utfördes under en relativ kort tidsperiod och startades med stora avvikelser. Regulatorn skulle dock kunna förbättras genom att använda testets aktuella isokinetiska avvikelse och med den informationen bestämma systemets referenspunkt. Det skulle göra det möjligt att kompensera för tidigare avvikelser och på det sättet uppnå isokinetiska avvikelser inom tillåtet intervall även för extremfall.
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Relangi, Durga Devika. "WETTING CHARACTERISTICS OF HERRIN COAL AND ITS APPLICATION FOR IMPROVED DUST CONTROL." OpenSIUC, 2012. https://opensiuc.lib.siu.edu/theses/827.
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This thesis has developed wetting characteristics of coal dust from Herrin coal seam in Illinois for improved respirable coal and quartz dust (< 10µm) control. Wetting characteristics were assessed by a wettability technique called Fixed Time Wettability (FTW) method which simulates the actual underground wetting environment. Immediate roof and immediate floor materials bulk samples were found to be 100% wettable by water alone, whereas coal seam samples were 55-90% wettable. Two variables: contact time between water droplets and dust particles and, the temperature of the water were found to affect the degree of wettability. FTW was carried out at as a function of water temperature (7.2oC to 40.5oC) and contact time (10 to 25 seconds) which increased wettability 2-18% and 8-32%, respectively. In addition, the wetted and un-wetted samples collected from wettability experiments were subjected to Scanning Electron Microscopy (SEM) and particle size distribution analyses. It was found that particles are irregular in shape in both wetted and un-wetted fractions and some agglomeration of fine particles was observed in a few un-wetted fraction samples. The concept of increased contact time was incorporated in engineering controls by increasing the wet scrubber filter screen inclination (which is a function of the screen surface area). The filter screen inclination was minimizing the pressure drop across it using Computational Fluid Dynamics (CFD) analysis. It was found that 60 degree (with respect to the vertical) would provide minimal pressure drop and should be considered for implementation. Additional research should be conducted on assessing selective wetting of different particle sizes of coal and quartz in airborne dust, developing data on wettability as a function of particle size and implementing the developed concepts such as contact time and temperature in the field for improved dust control.
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Copeland, Natalie Suzanne. "Evaluating a wood-strand material for wind erosion control and air quality protection." Online access for everyone, 2007. http://www.dissertations.wsu.edu/Thesis/Fall2007/n_copeland_113007.pdf.
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Martinez, Giancarlo Lopez. "Environmental and Behavioral control of the American House Dust Mite, Dermatophagoides Farinae Hughes." The Ohio State University, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=osu1392822781.
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Backes, Audrey Ann. "Evaluation of Particulate Matter Inside Control Rooms at a Quarry and Processing Facility." University of Toledo Health Science Campus / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=mco1418321178.
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Kumar, Anand. "Dust Transportation and Settling within the Mine Ventilation Network." UKnowledge, 2019. https://uknowledge.uky.edu/mng_etds/51.
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Dust is ubiquitous in underground mine activities. Continuous inhalation of dust could lead to irreversible occupational diseases. Dust particles of size lower than 75.0 µm, also known as float coal dust, can trigger a coal dust explosion following a methane ignition. Ventilation air carries the float coal dust from the point of production to some distance before it’s deposited on the surfaces of underground coal mine. Sources of dust are widely studied, but study of dust transportation has been mainly based on experimental data and simplified models. An understanding of dust transportation in the mine airways is instrumental in the implementation of local dust control strategies.
This thesis presents techniques for sampling float coal dust, computational fluid dynamics (CFD) analysis, and mathematical modeling to estimate average dust deposition in an underground coal mine. Dust samples were taken from roof, ribs, and floor at multiple areas along single air splits from longwall and room and pillar mines. Thermogravimetric analysis of these samples showed no conclusive trends in float coal dust deposition rate with location and origin of dust source within the mine network. CFD models were developed using the Lagrangian particle tracking approach to model dust transportation in reduced scale model of mine. Three dimensional CFD analysis showed random deposition pattern of particle on the mine model floor. A pseudo 2D model was generated to approximate the distance dust particles travel when released from a 7 ft. high coal seam. The models showed that lighter particles released in a high airflow field travel farthest. NIOSH developed MFIRE software was adopted to simulate dust transportation in a mine airway analogous to fume migration. The simulations from MFIRE can be calibrated using the dust sampling results to estimate dust transportation in the ventilation network.
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Yuen, Albert Wai Ling Materials Science & Engineering Faculty of Science UNSW. "Collector current density and dust collection in wire-plate electrostatic precipitators." Awarded by:University of New South Wales. Materials Science and Engineering, 2006. http://handle.unsw.edu.au/1959.4/28274.
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Even minimal improvements in particle collection efficiency of electrostatic precipitators significantly reduce dust emission from fossil-fuelled power stations and reduce pollution. Yet current designs rely on the Deutsch collection theory, which was developed for tubular precipitators and has been applied to wire-plate precipitators on the assumption that the inter-electrode electric fields at the same discharge distance in both were similar. Differences in geometry and associated collector electric fields and current density non-uniformity have not been taken into account, although the collector electric field and current density of the wire-plate precipitator are not uniform. And observations show that precipitated dust patterns and the distribution of collector current density are interrelated. Investigations revealed a simple square law relationship between the collector electric field and the collector current density in the space charge dominated coronas. Applying this relationship to the Deutsch collection theory led to a current-density-based collection formula that takes into account the non-uniform collector current density distribution. The current-density-based collection formula is then used to assess the impact of collector current density on collection efficiency, the results closely following published measurements. Applying the current-density-based collection formula to estimate the dust accumulation shows that most of the dust accumulates at collector locations facing the corona wires. The effect of the non-uniform precipitated dust layer on collection performance is assessed using the distributed corona impedance - the ratio of the inter-electrode voltage and the non-uniform collector current. Re-distribution of the collector current profile as dust builds up is also compatible with published measurements. Finally this is applied to optimize the wire-plate precipitator collection performance. This shows that optimal collection performance is obtained with the wire-wire spacing less than the wire-plate distance, once again confirming published experimental results. This is the first analytical approach to show better collection performance can be achieved at the ratio of wire-wire spacing/wire-plate distance not equal to unity, which has been the standard industry practice since 1960.
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Xiao, Fuchun Safety Science Faculty of Science UNSW. "Electrostatic charging of water sprays by corona and induction for dust suppression." Awarded by:University of New South Wales. School of Safety Science, 2000. http://handle.unsw.edu.au/1959.4/27410.
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Dust control is a very significant issue in underground coal mining. The benefits of reducing dust levels will be a lesser risk of lung disease to coal miners, improved working conditions and a reduced risk of dust explosions. Coal dust is commonly suppressed by water sprays but suppression efficiency is not high because dust tends to travel in the air flow round the water droplets rather than being captured by them. If water sprays are electrostatically charged, then a significant improvement in dust suppression efficiency may be achieved. Of the three principal droplet charging mechanisms, i.e. corona charging, induction charging and contact charging, corona charging is the most widely used in many industrial fields including dust suppression, However, it requires a high applied voltage, ranging from thousands to more than a hundred thousand volts, depending on the geometry of the charging equipment. Induction charging has been used in agricultural spraying since Law (1978) developed an embedded-electrode induction charging spraying nozzle. This nozzle provides a compact, inexpensively fabricated droplet charger and, reduces design requirements on size and output voltage (of the order of 1000 volts). It also reduces the potential for mechanical damage, misalignment and personnel hazard. In order to evaluate the effectiveness of dust suppression, either the charge on individual droplets or the charge-to-mass ratio of water sprays needs to be known. However, the parameters which control the charge applied to water and the charging rate have been unsolved theoretically for any charging mechanism. The existing theories for the induction-charged and air-atomising a liquid jet have been found to be inadequate. And there is no theory available for corona charging of the droplets produced with a pneumatic nozzle in order to predict the spray charge level or the spray charge-to-mass ratio. In view of this situation, mathematical models have been developed in this thesis for both the corona and induction charging mechanisms. During the development of the theories, it has been assumed that for corona charging, that the jet is disintegrated into droplets and the droplets are then charged; for induction charging, that the jet is first charged and the charged jet is then disintegrated into charged droplets. The Sauter mean diameter of the sprays, D32 , plays an important role in linking the individual droplet charge to the spray charge-to-mass ratio for both charging mechanisms. The developed theories are general models suitable for any liquid with both corona and induction charging. Theoretical calculations for the spray charge-to-mass ratio, individual droplet charge and the ratio of droplet charge to the Rayleigh charge limit have been presented for almost all of the influencing electrical and mechanical parameters such as applied voltage, air flowrate, liquid flowrate, liquid conductivity, liquid dielectric constant, nozzle dimensions, cylindrical electrode dimensions, and fluid parameters, for example, density, viscosity and surface tension. In the calculation for corona charging of droplets, the effect of the droplets on corona current and corona-onset voltage has been assessed for first time. The introduction of the Sauter mean diameter of the sprays, D32 , makes the assessment possible. Theoretical calculations for induction charging of liquid jets have shown that provided liquids have a conductivity value higher than the critical value, s = - 10 4 S/m, then they can be charged satisfactorily by the induction charging method. Among all of the influencing parameters, the electrical and mechanical parameters determine the charging rate and the water spray charge level. The suitability of employing these two charging mechanisms to dust suppression in coal mine has been evaluated based on the spray charge level, safety issues and the simplicity or otherwise of the equipment. The induction charging method was considered to have advantages over its corona charging counterpart, and has been chosen for charging the water sprays in the experiment program. Water has a conductivity of s = - 10 2 S/m, higher than the critical value, s = - 10 4 S/m. Based upon theoretical considerations, it is concluded that water is an appropriate liquid for corona charging, based on its dielectric constant, and for induction charging, based on its conductivity. In order to facilitate the testing of electrostatically charged water spray cloud parameters, a spray charger/collector was designed and constructed by others and a computerised data acquisition system has been employed. According to the theory developed for induction charging, the optimum length of the charging electrode has been analysed based upon the assumption that water jet is first charged and then the charged jet is disintegrated into charged droplets by the high pressure air. An experimental program examined the dependence of spray current upon four parameters: air flowrate, water flowrate, applied voltage and jet diameter. The experiments have shown that the induction-charged air-atomising nozzle used in the experiment is able to impart a significant charge into the water sprays. The spray charge-to-mass ratio calculated based upon the measured spray current demonstrates the same characteristics as predicted by theory: increasing with air flowrate, decreasing with water flowrate, increasing with applied voltage to a peak value then decreasing with further increase in the voltage, and increasing with jet diameter. A successful interpretation of an important phenomenon in the inductioncharged air-atomising a water jet, that spray charge-to-mass ratio and spray current increase with air pressure (or air flowrate) and decrease with increasing water flowrate, has been achieved based on the theories developed in this thesis. This phenomenon occurs because increasing air flowrate and/or decreasing water flowrate leads to a higher velocity of jet flowing through the induction electrode. However, when water flowrate becomes very small, a decrease in spray current with increasing air pressure (or flowrate) may be caused both by jet breakup inside the electrode and by contraction of the jet. In order to verify the theory, a preliminary comparison of experimental data with theoretical predictions employing a constant kic in the air-jet interaction coefficient a which was assumed to be 0.7 has shown a general agreement. However, the value of kic appears to be related to jet diameter, air/water mass ratio and applied voltage. An empirical equation for kic has then been formulated based on the experimental data for the spray charge-to-mass ratio. Finally a comparison of experimental results with theoretical predictions using the formulated kic shows an improved agreement. It is concluded that the induction-charged air-atomising nozzle has a potential application in dust suppression in coal mines, as the voltage required to charge water sprays is only 1000 ~ 1200 volts, and that the theory developed for induction charging of water sprays can be used to guide laboratory investigations and design processes for dust suppression and other industrial applications which might employ the electrostatic charging of liquid sprays.
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Kumar, Ashish R. "COMPUTATIONAL FLUID DYNAMICS (CFD) MODELING AND VALIDATION OF DUST CAPTURE BY A NOVEL FLOODED BED DUST SCRUBBER INCORPORATED INTO A LONGWALL SHEARER OPERATING IN A US COAL SEAM." UKnowledge, 2015. http://uknowledge.uky.edu/mng_etds/25.
Full textAbstract:
Dust is a detrimental, but unavoidable, consequence of any mining process. It is particularly problematic in underground coal mining, where respirable coal dust poses the potential health risk of coal workers’ pneumoconiosis (CWP). Float dust, if not adequately diluted with rock dust, also creates the potential for a dust explosion initiated by a methane ignition. Furthermore, recently promulgated dust regulations for lowering a miner’s exposure to respirable coal dust will soon call for dramatic improvements in dust suppression and capture.
Computational fluid dynamics (CFD) results are presented for a research project with the primary goal of applying a flooded-bed dust scrubber, with high capture and cleaning efficiencies, to a Joy 7LS longwall shearer operating in a 7-ft (2.1 m) coal seam. CFD software, Cradle is used to analyze and evaluate airflow patterns and dust concentrations, under various arrangements and conditions, around the active mining zone of the shearer for maximizing the capture efficiency of the scrubber.
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Gassman, Richard. "Effect of dust filtration control on CO2 and NH3 concentrations in a swine farrowing room." Thesis, University of Iowa, 2015. https://ir.uiowa.edu/etd/1969.
Full textAbstract:
Swine workers in concentrated animal feeding operations (CAFOs) are at risk of developing respiratory illnesses as a result of exposure to a combination of ammonia (NH3), carbon dioxide (CO2), and dust. The purpose of this study was to determine whether the use of a recirculating ventilation system with a filter-type air pollution control (APC) unit (Shaker Dust Collector, United Air Specialists Inc.), selected to control dust, would inadvertently increase NH3 and CO2 concentrations in a farrowing room.
During the 2013-14 winter season, NH3 and CO2 concentrations were measured at six fixed locations throughout the farrowing room test site. Direct reading instruments (NH3: VRAE, Rae Systems Inc.; CO2: ToxiRAE Pro, Rae Systems Inc.) were deployed for 24-hour periods throughout the season on 18 randomly selected days. Contaminant concentrations were measured and compared by ventilation status (APC ON: 11 days, APC OFF: 7 days).
Ammonia concentrations were above the literature recommended limit (7 ppm) on 13 of the 18 sample days (72%) and even exceeded the threshold limit value (TLV) of 25 ppm on one of the sample days. Carbon dioxide concentrations exceeded the literature recommended limit of 1540 ppm on all 18 sample days, and average concentrations were half of the TLV (2500 ppm). There was no statistically significant difference in NH3 (p > 0.23) or CO2 (p > 0.67) when concentrations were compared by APC status.
The results of this study indicate a recirculating ventilation system with filter dust control does not increase NH3 or CO2 concentrations spatially or temporally in the room during operation. Future work will investigate engineering control options to reduce CO2 concentrations in the farrowing room.
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Fourie, Hanlie. "Exposure to tailings dust, the characterization thereof and the evaluation of current control measures / H. Fourie." Thesis, North-West University, 2007. http://hdl.handle.net/10394/1142.
Full textAbstract:
Background:
Tailings dam workers are exposed to tailings dust that has a potential health risk due to the
element contents in the dust. The extent of exposure of tailings dam workers is unknown.
Consequently, the elements, level of exposure, the potential adverse effects to health,
compliance to legislative requirements and the efficiency of the current control measures were
investigated.
Design and Method:
During the trials, 69 personal dust samples were collected during three full production shifts
from tailings dam workers in three different tailings dam environments. The field filters were
weighed to calculate the total dust concentrations. Bulk samples and field filters were analysed
using the 32-element and particle size distribution scans. The between-dam, between-days and
between-group variances were determined to assess the changes in exposure levels.
Results:
The tailings dam workers were not overexposed to tailings dust. Mean exposures were below
the OEL for PNOC, measuring 0,124 mg/m3 (TD 1) 0,366 mg/m3 (TD 2) and 2,956 mg/m3 (TD
3). Three outliers in the data were present in TD 3 and exceeded the action level for PNOC. A
major part of the particle size distribution consisted of inhalable sizes (>I0 μm). Cyclone
tailings dams have smaller particle sizes than spigot tailings dams, though 85% of the particles
in all tailings dams were larger than 10 μm. Some elements identified in the dust have potential
respiratory health effects. No significant differences existed between the three tailings dams
regarding tailings dust concentrations (p=0,527 on 5% significant level and p=0,292 on 10%
significant level). There was, however, a significant difference on a 5% significant level between
the days (p=0,003 and p=0,006). The workers on the cyclone tailings dams had smaller
exposures than workers on the spigot tailings dams, and the pipeline labourers were more
exposed than the mudguards.
The tailings dams did comply with legislative control measures. However, washing facilities for
the cleaning of overalls due to elements in the dust, such as nickel, chromium and manganese
need to be considered. Workers need to be educated in work practices and procedures,
personal hygiene and symptoms that can be experienced after exposure. Engineering control
measures such as water sprayers covering the entire tailings dam, the use of fixed or temporary
windscreens in the area where work is done and covering of the roads on the tailings dam with
gravel or water spray can be considered as dust suppressant controls.
Conclusion:
The study met the issues set out in chapter 1, hypotheses were rejected and accepted and
future studies were suggested.Thesis (M.Sc. (Occupational Hygiene))--North-West University, Potchefstroom Campus, 2007.
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Ding, Xuhan. "Research and Application of Non-traditional Chemical Stabilizers on Bauxite 3 Residue (Red Sand) Dust Control." Thesis, Curtin University, 2018. http://hdl.handle.net/20.500.11937/74926.
Full textAbstract:
Although the treatment of red sand dust pollution is challenging, one potential approach to mitigate such issue is the application of non-traditional chemical stabilizers. In this paper, the Mechanisms of dust emission and chemical stabilization of red sand are proposed, the performance of different non-traditional stabilizer on dust control is studied and compared, and dust control performance and the change of mechanical properties are correlated for a sound red sand dust control strategy.
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Van, Jaarsveld Francis. "Characterising and mapping of wind transported sediment associated with opencast gypsum mining." Thesis, Stellenbosch : Stellenbosch University, 2008. http://hdl.handle.net/10019.1/2352.
Full textAbstract:
Thesis (MSc (Earth Sciences))--Stellenbosch University, 2008.This study aims to provide a practical tool for the prediction and management of dust generated by the activities of an opencast mining operation. The study was conducted on opencast gypsum mines in the semi-arid environment of the Bushmanland, 90 km north of Loeriesfontein in the Northern Cape Province from April 2000 to October 2007. The vertical and horizontal components of wind transported sediment were sampled and a dust settling model was designed to predict the settling pattern of dust generated by opencast mining operations. The model was applied to soil samples collected from an area surrounding a mine. The influence sphere of the mining operation was predicted by the application of the model and then mapped. Once the influence sphere is mapped, the dust influence can be managed with the aid of an onsite weather station. By further applying the predictions based on climatic data, the influence sphere can be modelled. The model is not only applicable to the planning phase of an opencast mine to plan the position of dust sensitive areas like the living quarters, office buildings and workshops etc., but also to indicate the historical impact that a mining operation had once a quarry on an active mine is worked out and rehabilitated or a mine is closed. The model application can also aid with the explanation and visual or graphic representation of the predicted impact of planned mining operations on communities or neighbouring activities to them and thus avoid later penalties.
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Joseph, Karen Elizabeth. "The effect of providing bedding encasings on adherence to dust mite control procedures in pediatric asthma patients." Morgantown, W. Va. : [West Virginia University Libraries], 2000. http://etd.wvu.edu/templates/showETD.cfm?recnum=1605.
Full textAbstract:
Thesis (M.A.)--West Virginia University, 2000.Title from document title page. Document formatted into pages; contains viii, 123 p. Includes abstract. Includes bibliographical references (p. 63-68).
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Young, Deborah Elspeth. "Evaluation of Dust Control Technologies for Drywall Finishing Operations: Industry Implementation Trends, Worker Perceptions, Effectiveness and Usability." Diss., Virginia Tech, 2007. http://hdl.handle.net/10919/28602.
Full textAbstract:
Drywall finishing operations have been associated with worker exposure to dust that contains known particulate respiratory health hazards, such as silica, talc, and mica. Despite the existence of engineering, work-practice, and personal-protective-equipment (PPE) control technologies for the mitigation of this hazard, worker exposures persist in the drywall finishing industry. This research employed a macroergonomic framework to evaluate this problem and identify barriers to dust control technology adoption in the key subsystems: personnel, technological, and organizational.
In the first study, the organizational subsystem was evaluated through a telephone interview of 264 drywall finishing firm owners. This study found the most commonly used dust control technology was respiratory protection. Cost, usability, environmental factors, and productivity were barriers identified in preventing adoption of other technologies.
In the second study, of the technological subsystem, 16 participants performed simulated drywall finishing tasks with each of four methods, in a laboratory setting. Dust particles were monitored and compared among the technologies used. Participants performed usability evaluations of the four tools. The ventilated sander produced less respirable-size class dust than did the other three tools. The block sander produced more dust than the other three tools. Usability evaluations revealed that the block sander was easiest to learn, easiest to use, and perceived to be the best overall, while the wet method and pole sander were considered to have poor usability in terms of ease of use and productivity. Usability problems associated with perceived comfort and ease of use were identified for the ventilated sander, but it was tied for "overall best" with the block sander.
The third study, of drywall finishing worker perceptions, employed the Health Belief Model to assess barriers to technology adoption, risk, susceptibility, and benefits. Results showed that workers have a high perception of the risk associated with drywall dust, but a lower perception of individual susceptibility to disease as a result of occupational exposure. Barriers to the use of dust control technologies were identified as being associated with organizational and usability factors. Most participants indicated having access only to respiratory protection, among the available dust control methods.Ph. D.
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Gorin, S. Steven. "Control of the effects of wind, sand, and dust by the citadel walls, in Chan Chan, Peru." Diss., Virginia Polytechnic Institute and State University, 1988. http://hdl.handle.net/10919/53698.
Full textAbstract:
Chan Chan, the prehistoric capital of the Chimu culture (ca. A.D. 900 to 1450), is located in the Moche Valley close to the Pacific Ocean on the North Coast of Peru. Its sandy desert environment is dominated by the dry onshore turbulent and gusty winds from the south. The nucleus of this large urban community built of adobe is visually and spatially dominated by 10 monumental rectilinear high walled citadels that were thought to be the domain of the rulers. The form and function of these immense citadels has been an enigma for scholars since their discovery by the Spanish ca. 1535. Previous efforts to explain the citadels and the walls have emphasized the social, political, and economic needs of the culture. The use of the citadels to control the effects of the wind, sand, and dust in the valley had not been previously considered.
Through the use of theoretical constructions and wind tunnel experiments, it is established that the form of the classic variant of the citadel was developed from a longtime interaction between the man—built environment and the natural environment. The Chimu had designed a courtyard system that reduced stress and discomfort from wind, sand, and dust by means of architectural features that included: the rectilinear citadel plan with the long axis parallel to the prevailing winds; the contiguous courtyards with the long axis in common; the high exterior walls; the high interior transverse walls; and the triangular cross section of the walls. It is demonstrated that these features kept out the blowing sand, reduced the wind speeds at pedestrian level, and kept dust, entrained in the airstream by the anthropogenic activity outside the walls, from entering the enclosures. It is also demonstrated that there is a correlation between the degree of protection afforded in a sector of the citadel and the social, political, and economic activities that took place in that sector.PH. D.
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Brabec, Daniel L. "Experimental and numerical modeling of dust control at grain receiving with a high-pressure water fogging system /." Search for this dissertation online, 2003. http://wwwlib.umi.com/cr/ksu/main.
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Kumar, Ashish R. "Dust Control Examination using Computational Fluid Dynamics Modeling and Laboratory Testing of Vortecone and Impingement Screen Filters." UKnowledge, 2018. https://uknowledge.uky.edu/mng_etds/44.
Full textAbstract:
Heavy industries, such as mining, generate dust in quantities that present an occupational health hazard. Prolonged exposure to the respirable dust has been found to result in many irreversible occupational ailments in thousands of miners. In underground mining applications, a variety of scrubbing systems are used to remove dust near the zones of generation. However, the wire-mesh type fibrous screens in the flooded-bed dust scrubbers used on continuous miners, are prone to clogging due to the accumulation of dust particles. This clogging results in a reduced capture efficiency and a higher exposure to the personnel. This research establishes the Vortecone, an inertial wet scrubber system, as a suitable alternative to the existing filters. The Vortecone accelerates its inlet fluids into a rapid circulatory motion into a vortex chamber, preferentially moving the heavier particles towards the impermeable surface to be trapped by the circulating water film. Vortecones are used on automobile painting lines and capture over-sprayed paint particles with cleaning efficacies exceeding 99 % while requiring only infrequent maintenance. The existing design of the Vortecone could also be altered to control the flow patterns.
This dissertation presents detailed computational fluid dynamics (CFD) models to describe air flow patterns in the Vortecone in steady and transient states. Multi-phase spray models were generated to simulate injection of water into the Vortecone. The volume of fraction (VOF) approach was adopted to mimic the air-water interface. The Lagrangian particle tracking method was used to model particle capture on the interface described by the VOF. The CFD models indicate excellent cleaning efficacies, especially of larger particles. Laboratory experiments with optical measurements of aerosols in a reduced scale model of the Vortecone validate the computer models. These experiments which were performed on dust samples with particle sizes 0.3 μm and above, show that the Vortecone captures 90 % particles by mass exceeding about 5.20 and 3.20 μm at air flows of 0.28 m3/s (600 cfm) and 0.38 m3/s (800 cfm), respectively. The development of detailed large eddy simulations (LES) of air flow in the Vortecone provides a novel contribution to research by better resolving the flow patterns.
An impactor-type, self-cleaning, non-clogging impingement screen system was designed as a substitute for conventional screens used in continuous miners. The screen could further be used as an efficient dust capturing mechanism with a demister in general mining applications. CFD models and laboratory experiments are presented to establish the cleaning efficacies of the system. Laboratory experiments to investigate the cleaning efficiency of a fibrous-type conventional screen is also discussed. The parameter, filter selection factor, is proposed to compare the performance of the three systems (Vortecone, fibrous screen, and impingement screen) under similar flows. The Vortecone has been found to be the most efficient dust-cleansing system, although it is the most power intensive fillter. The impingement screen shows a similar cleaning efficiency and a much higher availability compared to the conventional fibrous screen. Because of its minimal maintenance requirement, the impingement screen shows significant promise in dust-control applications in mining.
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Peng, Yanlei. "A retrospective study of dust storms and respiratory hospitalizations in El Paso, Texas using a case-crossover study design." To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2009. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
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Williams, Ischer Sarah Ashlee. "Evaluation of a sprinkler cooling system on inhalable dust and ammonia concentrations in broiler chicken production." Thesis, University of Iowa, 2016. https://ir.uiowa.edu/etd/3216.
Full textAbstract:
Indoor air contaminants such as dust and gases are present in concentrations that may be hazardous to worker health in poultry production. Poultry dust may contain inflammatory agents (e.g., endotoxin) and inhalation exposure has been associated with pulmonary symptoms. The current control practice to reduce worker exposure to poultry dust is the use of respiratory protection (e.g., filtering face-piece respirators). Limited research has been conducted to evaluate engineering controls to reduce dust concentrations in broiler chicken production. Therefore, the purpose of this research was to evaluate the effectiveness of a water sprinkling system to reduce inhalable dust and ammonia concentrations in a broiler chicken house.
Inhalable dust and ammonia concentrations were measured daily for the production cycle of a flock of broiler chickens (63 days). Inhalable dust was measured gravimetrically using an inhalable sampler and ammonia was measured by a direct reading sensor. Sampling was performed on a stationary mannequin inside two broiler chicken houses. One house used a sprinkler cooling system to deliver a water mist throughout the house and the second house was an untreated control. The sprinkler system activated 5 days after chicken placement and continued through day 63 of the broiler chicken production cycle. The following sprinkler activation program was used each hour from 6am to 10pm: days 5 – 9 five seconds, days 10 – 14 ten seconds, and days 15-63 for fifteen seconds.
Geometric mean (GM) inhalable dust concentrations collected in the treatment house (5.2 mg/m3) were lower than those found in the control house (6.0 mg/m3). The GM ammonia concentration within the treatment house was higher at 10.6 ppm (GSD: 1.80), compared to the control house (GM 9.51 ppm; GSD: 1.77). However, the observed differences were not statistically significant (p = 0.33 and p = 0.34, respectively).
Concentrations of inhalable dust were reduced by 11β when using the water sprinkling system, however the reduction was not statistically significant. The observed reduction in dust concentration was not sufficient to eliminate the need for respiratory protection.
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Wright, Gillian R. "The effect of domestic mechanical heat recovery ventilation on asthma control of patients allergic to the house dust mite." Thesis, University of Glasgow, 2008. http://theses.gla.ac.uk/189/.
Full textAbstract:
The prevalence of asthma has increased over the last generation, in parallel with a warm indoor microclimate. Central heating, fitted carpets and tight building construction have improved standards of heating and energy efficiency in homes, at the expense of ventilation. A warm, humid environment favours the growth of the house dust mite population. Allergy to the house dust mite is the most common allergy associated with asthma in the UK. Studies of occupational asthma, seasonal asthma and at altitude infer that the environment may directly affect symptoms of asthma. Allergen avoidance has been advocated as an important aspect of asthma management, yet the evidence for its efficacy has not been clear. Large studies of conventional measures to eradicate dust mites, such as mattress covers, have not shown a benefit for symptoms of asthma. As house dust mites are sensitive to humidity, an additional strategy would be to reduce indoor air humidity by improving ventilation. A randomised, double-blind placebo-controlled study examined the effect of the installation of domestic mechanical heat recovery ventilation on asthma control in the homes of 119 adults sensitive to house dust mite allergen. The study involved collaboration between the University Departments of Architecture, Respiratory Medicine and Immunology, local General Practices, the district general hospital, the local councils and industry. 100 participants completed follow-up. At twelve months, there was a clinically significant improvement in evening peak expiratory flow in the mechanical ventilation group and fewer admissions to hospital with asthma. There was a non-significant improvement in the mechanical ventilation group in the primary outcome, morning peak expiratory flow. There was a significant reduction in the asthma control questionnaire score at 3 months, but this was not sustained to 12 months. Rhinitis visual analogue scores for sneezing, nasal discharge and nasal blockage significantly improved in the group with mechanical ventilation compared to the control group at 6 months, but not at 12 months. There was no difference in exhaled nitric oxide, a measure of airway inflammation, between the two groups at 12 months. However, these clinical improvements could not be explained by reduced allergen exposure, as although indoor air humidity was reduced during the winter months, there was no difference between the house dust mite levels between the groups, nor in the levels of specific IgE to the house dust mite. Other mechanisms, such as mould, endotoxin, viral infection and environmental tobacco smoke should be considered in future work. In the mechanical ventilation group there was a modest individual gain of 0.02 Quality-adjusted life years over 12 months. However, it may still prove a cost-effective intervention if the clinical effects are sustained. Further research is required to establish if the clinical effects are sustained for greater than one year and to investigate the mechanism of the effect of improved home ventilation on respiratory health.
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Calvet, Sanz Salvador. "Experimental studies on gas and dust emissions to the atmosphere in rabbit and broiler buildings." Doctoral thesis, Universitat Politècnica de València, 2010. http://hdl.handle.net/10251/8304.
Full textAbstract:
La contaminación atmosférica originada por la producción animal intensiva afecta al medio ambiente global, a la salud de las personas y al bienestar de los animales de la propia granja. Se trata de una problemática de creciente interés en países en los que, como en el caso de España, se ha investigado poco hasta el momento. Esta tesis doctoral se centra en la medición experimental de concentraciones y emisiones de gases (amoniaco, metano, óxido nitroso y dióxido de carbono) y partículas (PM10) en granjas de pollos de cebo y de conejos, principalmente en clima mediterráneo, analizando los factores que afectan a dichas emisiones. Para ello, la tesis se compone de cinco trabajos de investigación diferenciados, aunque estrechamente relacionados entre sí. En primer lugar, se estudia en detalle la metodología empleada para medir las emisiones, basado en un balance en el que las variables son la concentración de gases y el flujo de ventilación; por otra parte, se desarrolla un procedimiento para el análisis de la incertidumbre cuyo objetivo es obtener indicadores de la calidad de los resultados. En segundo lugar, se aborda la medición del flujo de ventilación en granjas comerciales mediante el desarrollo de un circuito para la adquisición de información sobre el funcionamiento de los ventiladores. Posteriormente, y en aplicación de los dos anteriores estudios, se determinan las emisiones de gases en dos granjas comerciales de conejos y una de pollos en el litoral mediterráneo español, obteniendo resultados muy útiles para la mejora del inventario nacional de emisiones. Finalmente, se ha cuantificado la influencia de la actividad de los pollos de engorde en las emisiones de partículas y de gases, y se ha evaluado la aplicabilidad de un método para la determinación indirecta de la ventilación basado en el balance de dióxido de carbono. Los resultados obtenidos en estos experimentos y en los correspondientes análisis contribuyen al conocimiento general acerca de las emisionesCalvet Sanz, S. (2008). Experimental studies on gas and dust emissions to the atmosphere in rabbit and broiler buildings [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/8304
Palancia
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Colloff, M. J. "The biology and control of the European House Dust Mite, Dermatophagoides pteronyssinus (Trouessart, 1897) (Acari:Pyroglyphidae) in relation to atopic allergy." Thesis, University of Glasgow, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375455.
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Hill, Kara J. "Research on Preventing and Remediating the Dust Storms of China: A Case Study Investigating the Development of Salt Water Agriculture." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1306877383.
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Edvardsson, Karin. "Evaluation of Dust Suppressants for Gravel Roads : Methods Development and Efficiency Studies." Doctoral thesis, KTH, Väg- och banteknik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-12359.
Full textAbstract:
Approximately 75 percent (300 000 km) of the total Swedish road network and 20 percent(20 000 km) of the national road network consists of gravel roads. One of the most significantproblems associated with gravel roads is traffic-generated dust emission, which contributes tothe deterioration of the road surface and acts as a major source of particulate matter releasedinto the atmosphere, thereby involving public economics, road safety, human health, andenvironmental quality. In order to bind the fine granular material, which is prone to rise into theair, dust suppressants are applied on roads on a yearly basis. Methods for evaluating the efficiency of dust suppressants will facilitate in the selection of themost appropriate product and its optimal application rate. For example, methods forsupervision of residual dust suppressant concentration are valuable tools for estimatinglongevity and optimal application rates, and, consequently, effectiveness of different products. Application of the proper dust suppressant to a gravel road ensures road safety and ridingcomfort as well as creating a cleaner and healthier environment for residents in buildingsadjacent to the road. It also reduces the need and cost for vehicle repair, road maintenanceactivities, and aggregate supplementation. Both field-based and laboratory research were performed to evaluate the efficiency of varioussuppressants and the influence such factors as product concentration, leaching, and fine materialcontent have on the efficiency of different products. Within the field-based research, a newlydeveloped mobile methodology was used to measure dust emission on numerous test sectionstreated with various dust suppressants. In general, all dust suppressants tested, except apolysaccharide (sugar) and products, which form a brittle surface crust, i.e. lignosulphonate andbitumen emulsion, showed acceptable dust reduction. Test sections treated with a magnesium- or calcium chloride solution were the most effectivelydust suppressed. The application of solutions instead of a solid salts achieves a more uniformproduct distribution and, therefore, probably a more efficient performance. By applying acalcium- or magnesium chloride solution instead of traditionally used solids, the cost for annualdust control, as well as the environmental impact from the release of these chemicals in theenvironment, can be reduced by 50 percent. A significant problem when using dust suppressants is their tendency to leach during rainfalldue to their soluble properties. Residual chloride could be detected in the gravel wearing courseover a longer period of time than lignosulphonate and, therefore, showed more effective longtermperformance. Optimal percentages of fine material for minimal lignosulphonate andchloride leaching were found to be 15 percent by weight and 10-16 percent by weight,respectively. Ions of calcium chloride seemed to initiate flocculation of clay particles, therebypreventing them from leaching. Still, the fine material in gravel wearing courses has to be replenished regularly as indicated by studies of the longevity of fine material. Loss up to80 percent was found after two years. Toxicity tests show that dust suppressant application for dust control purposes, at traditionallyused application rates, does not constitute a threat to sensitive aquatic life. Tests on subsoilwater samples indicated elevated chloride levels, which possibly could cause corrosion to pipes,but not high enough to flavour drinking water.QC20100616
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Alam, Mohammad Masroor. "An integrated approach to dust control in coal mining face areas of a continuous miner and its computational fluid dynamics modeling /." Available to subscribers only, 2006. http://proquest.umi.com/pqdweb?did=1203573831&sid=2&Fmt=2&clientId=1509&RQT=309&VName=PQD.
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Ucci, Marcella. "The psychrometric control of house dust mites : testing the validity in UK dwellings of two combined hygrothermal population models for beds." Thesis, University College London (University of London), 2007. http://discovery.ucl.ac.uk/1445682/.
Full textAbstract:
Beds are a crucial source of house dust mite (HDM) allergens, which play a major role in allergic disease, particularly asthma. HDM require a specific combination of hygrothermal conditions to thrive. These bed conditions depend on a number of interacting factors, such as: external climate; building characteristics; heating, ventilation and moisture-producing habits; mattress properties; etc. Because of the complexity of the many interacting factors occuring in real dwellings, a modelling approach is required, whereby the models' predictions have to be consistent with field results. This thesis tested the hypothesis that a combined HDM population-hygrothermal model for beds can adequately predict field data and that the model can be a valuable tool for scenario modelling and intervention studies focused on the psychrometric control of house dust mites in UK housing. Two combined models were considered: a simple steady-state one-dimensional model (BED/MPI), and a complex transient three-dimensional mode (Lectus/Popmite). A combination of fieldwork and scenarios modelling was carried out, which involved hygrothermal and mite monitoring of 25 beds, utilising a novel technique whereby live mites were caged in mite bags and installed in monitored beds and bedrooms (82 sets of mites bags). The work was carried out as part of a multidisciplinary project aimed at developing and testing the models. Good agreement was found between field data and the models predictions, particularly when the uncertainties due to input variables and measurements were taken into account. The results showed that under borderline conditions for HDM growth, simple steady-state predictions may not be accurate. Temperature, not only RH, is a critical variable for HDMs. Areas for model improvement were also identified. In particular, factors other than hygrothermal conditions may be crucial for a beds mite carrying capacity, requiring further investigation: food, space availability, and mite movement. Despite these uncertainties, it can be concluded that greater ventilation, increased thermostat settings and reduced moisture rates can decrease mite levels in beds. The ventilation rates provided by some mechanical ventilation with heat recovery systems may be inadequate to sufficiently control moisture and reduce mite growth. Scenarios modelling suggests that there is considerable potential for the psychrometric control of house dust mites in UK dwellings.
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Petrov, Todor P. "DEVELOPMENT OF INDUSTRY ORIENTED CFD CODE FOR ANALYSIS / DESIGN OF FACE VENTILATION SYSTEMS." UKnowledge, 2014. http://uknowledge.uky.edu/mng_etds/12.
Full textAbstract:
Two of the main safety and health issues recognized during deep cut coal mining are methane and dust hazards. Advances in continuous miner technology have improved safety and productivity. However, these advances have created some environmental problems, notably more dust and methane being generated at the face during coal extraction.
Results of studies performed in the last three decades concerning the face ventilation for deep cut mining showed very complicated airflow behavior. The specifics of flow patterns developed by the face ventilation systems presents significant challenge for analytical description even for equipment-free entry. Fortunately, there are methods, such as numerical simulations that could be used to provide an engineering solution to the problem. Computational Fluid Dynamics (CFD) codes have been successfully applied during the last decade using the power of Supercomputers. Although significant progress has been made, a benchmark industry oriented CFD code dedicated to face ventilation is still not available.
The goal of this project is to provide the mining industry a software for CFD analysis and design of face ventilation systems. A commercial CFD system SC/Tetra Thermofluid Analysis System with Unstructured Mesh Generator, copyright © Cradle Co, was selected for a development platform. A number of CFD models were developed for the needs of this study including methane release, dust generation, 3D models of commonly used continuous mining machines, scrubbers and water spray systems. The developed models and the used CFD code were successfully validated in the part for methane dilution, using available data from small scale and full scale experiments. The developed models for simulation of dust control systems need to be validated in the future. The developed code automates all necessary steps needed for simulation of face ventilation systems, starting with the construction of a 3D model, generation of the computational mesh, solving and monitoring the calculations, to post-processing and graphical representation of the obtained results. This code shall allow mining engineers to design better and safer face ventilation systems while providing the Mine Safety and Health Administration (MSHA) a tool to check and approve the industry’ proposed ventilation plans.
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Saifee, Quaid J. "Strategic and tactical models and algorithms for the coal industry under the 1990 Clean Air Act." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-09292009-020130/.
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Vijapur, Santosh H. "Design optimization and experimental study of a wet laminar electrostatic precipitator for enchancing collection efficiency of aerosols." Ohio : Ohio University, 2008. http://www.ohiolink.edu/etd/view.cgi?ohiou1227020758.
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Özdemir, Ismet [Verfasser], Per Nicolai [Akademischer Betreuer] Martens, and Christian [Akademischer Betreuer] Niemann-Delius. "A Decision Support System and Cost-Performance Analysis for Dust Control at Open-Pit Coal Mines / Ismet Özdemir ; Per Nicolai Martens, Christian Niemann-Delius." Aachen : Universitätsbibliothek der RWTH Aachen, 2015. http://d-nb.info/1127143654/34.
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Jeffries, Cameron. "Radiological exposure due to radioactivity carrying aerosols in a mineral sand processing plant." Thesis, Queensland University of Technology, 2002. https://eprints.qut.edu.au/37123/7/37123_Digitised%20Thesis.pdf.
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Mineral sand processing involves a radiological risk due to uranium and thorium series isotopes. Characterising the radioactive aerosol requires measurement of the activity size distribution and the isotopic composition of the aerosol. This is a time consuming process requiring long sampling times and sample counting after a suitable delay time. As a result a number of weeks are required to complete analysis of the activity size distribution. Instrumentation is now available that determines the number and mass distribution within a matter of minutes.
Measurements of activity, number and mass distribution and total activity concentration were made at six sites in the Consolidated Rutile Limited dry processing mill at Pinkenba, Queensland. The activity distribution was measured using a cascade impactor. The number distribution was measured using an Aerodynamic Particle Sizer. The mass distribution was measured with the impactor of two samples and was calculated from the measured number size distributions. The activity distribution was counted twice with a six month gap to test the effect of in growth of 210Po from attached 210Pb. It was concluded that 210Po in growth has a negligible effect on the measured activity size distributions.
The activity and mass distributions measured by the impactor were compared. The impactor measured mass distribution was compared to the APS calculated mass distribution. The activity distribution was compared with the number and mass distributions determined by the APS. Agreement was found between the activity and APS mass distribution. The results show that the activity distribution could be determined quickly by measuring the mass distribution with the APS and applying the total activity concentration.
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Junior, Agenor de Faria. "Aprimoramento do controle de qualidade do minério no planejamento de lavra de curto prazo: estudo de caso." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/3/3134/tde-11082010-164812/.
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Melhorar o conhecimento sobre o minério lavrado é um desafio enfrentado diariamente pelas empresas de mineração. O presente trabalho trata de um estudo realizado na mina de apatita, localizada na cidade de Cajati, interior do Estado de São Paulo, de propriedade da Bunge Fertilizantes S/A, onde são abordados temas relacionados ao planejamento de lavra de curto prazo, visando o aprimoramento dos procedimentos de coleta de amostras de pó-de-perfuratriz, que são sistematicamente coletadas com o objetivo de controle de qualidade da lavra, contribuindo para uma efetiva melhoria na gestão do planejamento de lavra e na tomada de decisões. Os resultados obtidos mostram que, da forma como as amostras são coletadas, ocorre um enriquecimento do teor de P2O5, podendo levar a tomada de decisões erradas por parte da operação da mina.Improve knowledge of the ore mined is a challenge faced daily by mining companies. This paper is a study in apatite mine, located in the city of Cajati, within São Paulo,propriety of Bunge Fertilizantes S/A, where are treated issues related to short term planning of the mine to improve procedures for collecting dust samples drilling, which are systematically collected for the purpose of quality control of mining, contributing to an effective improvement in the management of planning of mining and decision making. The results show that the way the sampling is done, there is an enrichment of content in P2O5, which can lead to making wrong decisions by the operation of the mine.
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Jakubský, Ondřej. "Řízení odprášení tavicích pecí na recyklaci hliníkového odpadu." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2009. http://www.nusl.cz/ntk/nusl-217908.
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The work deals with controlling and visualizing technology of dust exhaust of smeltery for recyclation of aluminum waste. In the first part of the work are analyzed the different ways of automatic control. Based on the analysis is proposed control system configuration, algorithm of control, communication interfaces and sensors of alarm, measurement and regulation. The second part deals with visualization and remote administration of control system. On the basis of selection for the visualization software is designed and implemented a system that provides visualization of technology, the archiving of measured operating values, events and errors.
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von, Holdt Johanna R. C. "Aeolian dust emission dynamics across spatial scales: landforms, controls and characteristics." Doctoral thesis, University of Cape Town, 2018. http://hdl.handle.net/11427/28364.
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Variable erodibility (surface characteristics) and erosivity factors (meteorological conditions) result in dust emission dynamics being complex in both space and time. Accounting for localscale surface variability is critical to our understanding of dust emitting processes. This study identifies mineral dust using remote sensing, establishes emission thresholds through field measurements and identifies particle chemistry for major dust sources in the Central Namib Desert. Examining over 2000 Landsat images over a period from 1972 to 2016, identified 40 days of visually detectable dust, originating from sub-km scale point sources. The observations suggest that dust sources can be identified at the landform scales which particularly include ephemeral river valleys and saline pan surfaces. These persist throughout the 25-year record; however, a gradual shift in source point clusters is noted through time, which can be tentatively attributed to anthropogenic modification of the hydrological systems. A PI-SWERL (Portable In-Situ Wind ERosion Lab) wind tunnel was used to measure the emission potential of the Landsat derived targets. The most emissive sources were paleostockpiles of alluvial silt deposits and associated degraded nebkhas within the Kuiseb River Delta. These had a geometric mean emission flux of 0.076 mg m-2 s -1. In comparison, the active channel had a geometric mean emission flux of 0.008 mg m-2 s -1, undisturbed desert pavement 0.007 mg m-2 s -1, pan surfaces 0.001 mg m-2 s -1 and wadis within the gravel plains 0.030 mg m-2 s -1. The emission thresholds were augmented with site-specific field measurements such gravel cover (%), moisture content (%), particle size (µm), elemental composition (%) and shear and compressive strength (kg cm-2). A Boosted Regression Tree (BRT) machine-learning algorithm identified the most important surface and sediment characteristics determining dust emission from the measured surfaces. The model explained 70.8% of the deviance in the measured dust flux with the top predictor variables and their relative importance (%) as follows: gravel cover, 16%; moisture content, 14%; kurtosis, 13%; very coarse silt, 13%; very fine sand, 11%; fine sand, 8%; compressive strength, 7%, calcium, 7% and magnesium, 6%. Such an analysis can be used to identify critical thresholds for dust emission and standardise testing protocols. Linking landforms with such emission measurements allow for the assessment of two existing dust emission schemes: the Preferential Dust Scheme (PDS; Bullard et al. 2011) and the Sediment Supply Map (SSM; Parajuli et al. 2017). Although these schemes represent a major advance in our representation of dust emission source areas and erodibility, this study shows that these schemes still need to be improved to accurately depict dust emission potential. For the PDS this would include producing a global rasterised output with quantified dust emission potential and for the SSM, a more accurate classification of the highly emissive geomorphic units. Landsat source point sediments were subjected to physical and geochemical analyses and compared to samples obtained from passive collectors such as the Big Spring Number Eight (BSNE) and active PI-SWERL exhaust emissions, using an auto-SEM (QEMSCAN). This provided individual particle mineralogy (>2 µm resolution) for a total of approximately 10000 to 60000 particles per sample which enabled a comparison of particle size, shape and mineralogy. The samples consist of a mixture of minerals reflecting the varied metamorphic geology and consists predominantly of feldspar, quartz, mica, other aluminosilicates such as the alteration products epidote and chlorite and low to medium grade metamorphics such as amphibole and pyroxene, iron oxihydroxides, titanium minerals, carbonates and clay minerals.
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Kumar, Abhinav. "Flow control optimization in a jet engine serpentine inlet duct." [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-1399.
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Dunst, Thomas [Verfasser], and Andreas [Akademischer Betreuer] Prohl. "Stochastic Control of Magnetization Dynamics / Thomas Dunst ; Betreuer: Andreas Prohl." Tübingen : Universitätsbibliothek Tübingen, 2016. http://d-nb.info/1164170384/34.
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