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Effects of process parameters on granules properties produced in a high shear granulatorRahmanian, Nejat, Naji, A., Ghadiri, M. January 2011 (has links)
No / Results of a study on the influence of process parameters such as impeller speed, granulation time and binder viscosity on granule strength and properties are reported. A high shear granulator (Cyclomix manufactured by Hosokawa Micron B.V., The Netherlands) has been used to produce granules. Calcium carbonate (Durcal) was used as feed powder and aqueous polyethylene glycol (PEG) as the binder. The dried granules have been analysed for their strength, density and size distribution. The results show that increasing the granulation time has a great affect on granules strength, until an optimum time has been reached. The underlying cause is an increase in granule density. Granules are consolidated more at higher impeller speeds. Moreover, the granule size distribution seems not to be affected significantly by an increase in impeller speed. Granules produced with high binder viscosity have a considerably lower strength, wide strength distribution due to poor dispersion of binder on the powder bed. Binder addition methods have showed no considerable effect on granule strength or on granule size distribution.
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Cattle feedlot dust – laser diffraction analysis of size distribution and estimation of emissions from unpaved roads and wind erosionGonzales, Howell B. January 1900 (has links)
Master of Science / Department of Biological & Agricultural Engineering / Ronaldo G. Maghirang / Large cattle feedlots emit considerable amounts of particulate matter (PM), including
TSP (total suspended particulates), PM[subscript]10 (PM with equivalent aerodynamic diameter of 10 μm or
less), and PM[subscript]2.5 (PM with equivalent aerodynamic diameter of 2.5 μm or less). Particulate
emissions result from pen surface disturbance by cattle hoof action, vehicle traffic on unpaved
roads and alleyways, and wind erosion. Research is needed to determine concentrations of
various size fractions, size distribution, and emission rates from various sources in feedlots. This
research was conducted to measure particle size distribution using laser diffraction method and
estimate emissions from unpaved roads and wind erosion.
Particle size distribution and concentrations of PM[subscript]10 and PM[subscript]2.5 at a commercial cattle
feedlot in Kansas (Feedlot 1) were measured over a 2-yr period. The feedlot had a capacity of
30,000 head and total pen area of 50 ha and was equipped with a sprinkler system for dust
control. Collocated low-volume samplers for TSP, PM[subscript]10, and PM[subscript]2.5 were used to measure
concentrations of TSP, PM[subscript]10, and PM[subscript]2.5 at the upwind and downwind edges of the feedlot. Dust
samples that were collected by TSP samplers were analyzed with a laser diffraction analyzer to
determine particle size distribution. Particle size distribution at the downwind edge of the
feedlot was also measured with micro-orifice uniform deposit impactor (MOUDI). The laser
diffraction method and MOUDI did not differ significantly in mean geometric mean diameter
(13.7 vs. 13.0 μm) but differed in mean geometric standard deviation (2.9 vs. 2.3). From laser
diffraction and TSP data, PM[subscript]10 and PM[subscript]2.5 concentrations were also calculated and were not
significantly different from those measured by low-volume PM[subscript]10 and PM[subscript]2.5 samplers (122 vs.
131 μg/m[superscript]3 for PM[subscript]10; 26 vs. 35 μg/m[superscript]3 for PM[subscript]2.5). Both PM[subscript]10 and PM[subscript]2.5 fractions decreased as
pen surface moisture contents increased, while the PM[subscript]2.5/PM[subscript]10 ratio did not change much with
pen surface moisture content.
Published emission models were used to estimate PM[subscript]10 emissions from unpaved roads
and wind erosion at Feedlot 1 and another nearby feedlot (Feedlot 2). Feedlot 2 had a capacity
of 30,000 head, total pen surface area of 59 ha, and used water trucks for dust control. Estimated
PM[subscript]10 emissions from unpaved roads and wind erosion were less than 20% of total PM[subscript]10
emissions obtained from inverse dispersion modeling. Further research is needed to establish the
applicability of published emission estimation models for cattle feedlots.
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Measurement and control of particulate emissions from cattle feedlots in KansasGuo, Li January 1900 (has links)
Doctor of Philosophy / Department of Biological & Agricultural Engineering / Ronaldo G. Maghirang / Emissions of particulate matter (PM) are an increasing concern for large open beef cattle feedlots. Research is needed to develop science-based information on PM emissions and abatement measures for mitigating those emissions. This research was conducted to (1) measure PM concentrations emitted from large cattle feedlots, (2) compare different samplers for measuring concentrations of PM with equivalent aerodynamic diameter of 10 µm or less (PM10), (3) evaluate the relative effectiveness of pen surface treatments in reducing PM10 emissions, and (4) predict PM control efficiency of vegetative barriers.
Concentrations of PM with equivalent aerodynamic diameter of 2.5 µm or less (PM2.5), PM10, and total suspended particulates (TSP) upwind and downwind of two large cattle feedlots (KS1, KS2) in Kansas were measured with gravimetric samplers. The downwind and net concentrations generally decreased with increasing water content (WC) of the pen surface; for effective control of PM emissions from feedlots, it appears that pen surface WC should be at least 20% (wet basis).
Three types of samplers for measuring PM10 concentrations in feedlots KS1 and KS2 were compared: Tapered Element Oscillating Microbalance™ (TEOM), high-volume (HV), and low-volume (LV) PM10 samplers. Measured PM10 concentration was generally largest with the TEOM PM10 sampler and smallest with the LV PM10 sampler.
A laboratory apparatus was developed for measuring the PM10 emission potential of pen surfaces as affected by surface treatments. The apparatus was equipped with a simulated pen surface, mock cattle hooves that moved horizontally across the pen surface, and PM10 samplers that collected emitted PM10. Of the surface treatments evaluated, application of water (6.4 mm) and hay (723 g/m2) exhibited the greatest percentage reduction in PM10 emission potential (69% and 77%, respectively) compared with the untreated manure layer.
Computational fluid dynamics (CFD) was applied to predict airflow and particle collection by a row of trees (2.2 m high × 1.6 m wide). Predicted particle collection efficiencies generally agreed with published data and ranged from less than 1% for 0.875-µm particles to approximately 32% for 15-µm particles.
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Microstructure of Gas Hydrates in Sedimentary MatricesChaouachi, Marwen 15 July 2015 (has links)
No description available.
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A Continuous Mathematical Model of the One-Dimensional Sedimentation Process of Flocculated Sediment ParticlesTorrealba, Sebastian Fernando 01 January 2010 (has links)
A new continuous one-dimensional sedimentation model incorporating a new continuous flocculation model that considers aggregation and fragmentation processes was derived and tested. Additionally, a new procedure to model sediment particle size distribution (PSD) was derived. Basic to this development were three different parametric models: Jaky, Fredlund and the Gamma probability distribution (GPD) were chosen to fit three different glass micro-spheres PSDs having average particle sizes of 7, 25 and 35 microns. The GPD provided the best fit with the least parameters. The bimodal GPD was used to fit ten sediment samples with excellent results (< 5% average error). A continuous flocculation model was derived using the method of moments for solving the continuous Smoluchowski coagulation equation with fragmentation. The initial sediment PSD was modeled using a bimodal GPD. This new flocculation model resulted in a new general moments’ equation that considers aggregation and fragmentation processes, which is represented by a system of ordinary differential equations. The model was calibrated using a genetic algorithm with initial and flocculated PSDs of four sediment samples and four anionic polyacrylamides flocculants. The results show excellent correlation between predicted and observed values (R2 > 0.9878). A new continuous one-dimensional sedimentation model that resulted in a scalar hyperbolic conservation law was derived from the well-known Kynch kinematic sedimentation model. The model was calibrated using column tests results with glass micro-spheres particles. Two different glass microspheres particle size distributions (PSDs) were used with average diameters of 7 and 37 microns. Excellent values of coefficient of determination (R2 > 0.89, except for one test replicate) were obtained for both the small and large glass micro-spheres PSDs. These results suggest that the proposed sedimentation model can be expanded to model the sedimentation process inside a sediment pond.
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Vamzdyno nuogulų tyrimas ir apibūdinimas / The research and characterization of pipeline scalesVerikienė, Vaida 22 June 2010 (has links)
Baigiamajame magistro darbe „Vamzdyno nuogulų tyrimas ir apibūdinimas“, apžvelgus mokslinės literatūros šaltinius, apibūdintos ant vamzdžių vidinių sienelių susidarančios nuogulos, kurių sudėtyje vyrauja geležies junginiai. Nagrinėjama, kokią įtaką vandens kokybei turi ant skirtingų medžiagų vamzdžių vidinių sienelių susidariusios nuogulos. Aptariama, kokios dėl nuogulų susidarymo iškyla problemos vandentiekio sistemoje.
Vilniaus Gedimino technikos universiteto Vandentvarkos katedros laboratorijoje buvo atliktas eksperimentas, sumontavus du eksperimentinius stendus. Juos sudarė skirtingų medžiagų (PE, cinkuoto plieno ir seno plieno) vamzdynų sistemos, kuriomis cirkuliavo skirtingos kokybės vanduo. Buvo nustatyta kiekybinė ir kokybinė nuogulų sudėtis. Kiekybinė sudėtis apibūdinta ChDS pokyčiu, esant skirtingai vandens išbuvimo trukmei vamzdyne. Kokybinę sudėtį apibūdina geležies, mangano junginių, amonio jonų, nitritų ir nitratų koncentracijos vandenyje. Tai pat nustatyta vamzdyno nuogulų granuliometrinė sudėtis. Atlikus tyrimus paaiškėjo, kad bendrosios geležies koncentracija mažiausia buvo PE, o didžiausia – seno plieno vamzdyno mėginiuose. PE vamzdyne mangano koncentracija didėjo ilgėjant vandens užsistovėjimo trukmei. Amonio jonų, nitritų ir nitratų kiekiai mėginiuose neviršijo higienos normų. PE vamzdynų nuogulų ChDS rodikliai buvo mažiausi abiejuose stenduose. Palyginus eksperimentinių stendų nuogulų mėginių rezultatus, paaiškėjo, kad ChDS reikšmės priklauso nuo vandens... [toliau žr. visą tekstą] / In the Master‘s Thesis "The research and characterization of pipeline scales" the literature review of scientific sources was described pipeline scales which contains predominantly iron compounds. The impact of water quality on the pipeline scales was investigated. Negative impact of the formation of pipeline scales on water distribution system was analysed.
Experimental investigation was carried out in the laboratory scaled equipment at Water Management Department of VGTU. Experimental pipelines consist of different materials (galvanized steel, old steel and polyethylene (PE)) pipe system with circulated different water quality. The quantitative and qualitative composition of the scales was measured. The quantitative composition was described of the change of COD under different water age in to the different pipelines. The qualitative composition was described by iron, manganese compounds, ammonium, nitrite and nitrate concentrations in water. It was also set the particle size content of pipeline scales.
Results showed that the lowest iron concentration was in PE pipe samples and the highest in an old steel pipe samples. The concentration of manganese increased with increasing duration of water age in PE pipe. Ammonium ions, nitrite and nitrate levels didn't exceed the requirements of hygiene norm. The lowest COD rates were in PE pipe scales in both laboratory scaled equipments. It was found that COD values depend on the quality of water that circulated in pipeline. It was... [to full text]
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Development of clinically relevant in vitro performance tests for powder inhalersWei, Xiangyin 01 January 2015 (has links)
While realistic in vitro testing of dry powder inhalers (DPIs) can be used to establish in vitro–in vivo correlations (IVIVCs) and predict in vivo lung doses, the aerodynamic particle size distributions (APSDs) of those doses and their regional lung deposition remains unclear. Four studies were designed to improve testing centered on the behavior of Novolizer®. Different oropharyngeal geometries were assessed by testing different mouth-throat (MT) models across a realistic range of inhalation profiles (IPs) with Salbulin® Novolizer®. Small and large Virginia Commonwealth University (VCU) and Oropharyngeal Consortium (OPC) models produced similar ranges for total lung dose in vitro (TLDin vitro), while results for medium models differed significantly. While either group may be selected to represent variations in oropharyngeal geometry, OPC models were more difficult to use, indicating that VCU models were preferable. To facilitate simulation of human IPs through DPIs, inhalation profile data from a VCU clinical trial were analyzed. Equations were developed to represent the range of flow rate vs. time curves for use with DPIs of known airflow resistance. A new method was developed to couple testing using VCU MT models and simulated IPs with cascade impaction to assess the APSDs of TLDin vitro for Budelin® Novolizer®. This method produced IVIVCs for Budelin’s total lung dose, TLD, and was sufficiently precise to distinguish between values of TLDin vitro and their APSDs, resulting from tests using appropriately selected MT models and IPs. For example, for slow inhalation, TLD values were comparable in vivo and in vitro; TLDin vitro ranged from 12.2±2.9 to 66.8±1.7 mcg aerosolized budesonide while APSDs in vitro had mass median aerodynamic diameters of 3.26±0.27 and 2.17±0.03 µm, respectively. To explore the clinical importance of these variations, a published computational fluid dynamic (CFD) model was modified and coupled to accept the output of realistic in vitro tests as initial conditions at the tracheal inlet. While simplified aerosol size metrics and flow conditions used to shorten CFD simulations produced small differences in theoretical predictions of regional lung deposition, the results broadly agreed with the literature and were generally consistent with the median values reported clinically for Budelin.
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The synthesis and study of some metal catalysts supported on modified MCM-41Mokhonoana, Malose Peter 17 November 2006 (has links)
PhD thesis -
Faculty of Science / The main aim of this thesis has been to study the way in which Fe(III) and Co(II)
incorporation into Si-MCM-41 synthesis gels affects the properties of the unmodified
material. Another aim was to investigate the influence of these hetero-atoms
on the dispersion and particle size distribution as well as the catalytic activity of
supported Au nanoparticles in the CO oxidation reaction.
Si-MCM-41 has been successfully synthesized in this work using mixtures containing
CTAB as a structure-directing agent (SDA) and water-glass as a SiO2
source. Replacement of water-glass with pre-calcined Si-MCM-41 for SiO2 source
in the secondary synthesis step has produced Si-MCM-41 with improved structural
properties (XRD, HRTEM and Raman spectroscopy), including restructured
and more crystalline pore walls (Raman spectroscopy).
The conventional shortcomings of Si-MCM-41 as a support for catalyticallyactive
(transition) metal components such as low hydrothermal stability, low PZC,
lack of cation exchange capacity and no reducibility have been partially addressed
by modification with Fe(III) and Co(II). The premodification was achieved both
during framework synthesis and after synthesis by the incipient wetness impregnation
(IWI) method. As opposed to the one-pot synthesis of metal-containing
derivatives, the IWI method gave materials with high metal loadings and maximal
retention of the properties of pristine Si-MCM-41. On the other hand, metal
incorporation during synthesis to a loading of ~8.8 wt% using aqueous solutions
of metal precursors showed some collapse of the mesostructure. Consequently
methods were sought to incorporate this amount of metal (and up to double, i.e.,
16 wt%) with maximal retention of the MCM-41 characteristics. These methods
included (i) using Si-MCM-41 as a SiO2 source, (ii) dissolving the metal precursors
in an acid solution before inclusion into the synthesis gel, and (iii) using
freshly precipitated alkali slurries of the metal precursors. The first method
produced a highly ordered 16wt% Fe-MCM-41 material with excellent reducibility
(TPR showed three well-resolved peaks) and pore-wall structure (Raman spectroscopy). Like the aqueous route, the acid-mediated metal incorporation route
did not produce ordered materials at metal contents of ~16 wt%. The base precipitate
route produced highly ordered composite materials up to 16 wt% metal
content, with characteristics similar to those of Si-MCM-41 (XRD, BET and
HRTEM), although some metal phases were observed as a separate phase on the
SiO2 surface. Thus, metal-containing MCM-41 materials could be obtained with
conservation of MCM-41 mesoporosity. Raman spectroscopic studies have shown
that the effect of transition metal incorporation in MCM-41-type materials is to
strengthen the pore walls (shift of Si-O-Si peaks to higher frequencies), while
TPR studies revealed that the essentially neutral framework of Si-MCM-41 could
be rendered reducible by transition metal incorporation.
Gold-containing mesoporous nanocomposites were prepared by both direct synthesis
and post-synthetically. Catalysts prepared by direct hydrothermal synthesis
were always accompanied by formation of large Au particles because of the need
to calcine the materials at 500 oC in order to remove the occluded surfactant
template. The presence of transition metal components in Me-MCM-41 (Me = Fe
and Co) has been found to play a significant role in the particle size distribution
and also the dispersion of Au nanoparticles when these materials were used as
supports. In general, a base metal-containing support was found to produce
smaller Au nanoparticles than the corresponding siliceous support. It has been
proposed that the transition metal components serve as anchoring or nucleation
sites for the Au nanoparticles, which are likely to sinter during calcination. The
anchoring sites thus retard the surface mobility of Au at calcination temperatures
above their TTammann.
The use of the Au/Me-MCM-41 materials as catalysts in the CO oxidation
reaction has led to the following observations: (i) catalyst on metal-containing
supports showed better activity than those on Si-MCM-41, probably due to the
induced reducibility in metal-MCM-41, (ii) catalysts prepared by direct synthesis
showed inferior activity owing to large Au particles, (iii) increasing Au content
improves the catalytic performance, (iv) increasing the Fe content of the support at constant Au improves the catalytic performance, and (v) changing the base
metal component of the support from Fe to Co led to a significant improvement in
catalytic activity. The similarity of the apparent activation energies (Ea) for the 5
wt% Au-containing 5 wt% Fe- and 5 wt% Co-MCM-41 suggested that the
difference in catalytic activity is associated with the number of active sites
possessed by each catalyst system. The observed order of catalytic activity of
these 5 wt% Au-containing systems in terms of the support type is: Co-MCM-41
> Fe-MCM-41 > Si-MCM-41. This was further supported by the average Au
particle size, which, in terms of the support, followed the order Co-MCM-41 <
Fe-MCM-41 < Si-MCM-41. Thus, metal-support interactions between Au and
MCM-41 have been enhanced by introducing Fe(III) and Co(II), which also
induced framework charge, ion exchange capacity (IEC) and reducibility in the
neutral siliceous support.
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Evaluation of emulsion destabilization by light scattering applied to metalworking fluids. / Avaliação da desestabilização deemulsões por espalhamento de luz, aplicada a fluídos de corte.Assenhaimer, Cristhiane 25 August 2015 (has links)
Monitoring of emulsion properties is important in many applications, like in foods and pharmaceutical products, or in emulsion polymerization processes, since aged and broken emulsions perform worse and may affect product quality. In machining processes, special types of emulsions called metalworking fluids (MWF) are widely used, because of its combined characteristics of cooling and lubrication, increasing the productivity, enabling the use of higher cutting speeds, decreasing the amount of power consumed and increasing tool life. Even though emulsion quality monitoring is a key issue in manufacturing processes, traditional methods are far from accurate and generally fail in providing the tools for determining the optimal useful life of these emulsions, with high impact in costs. The present study is dedicated to the application of a spectroscopic sensor to monitor MWF emulsion destabilization, which is related to changes in its droplet size distribution. Rapeseed oil emulsions, artificially aged MWF and MWF in machining application were evaluated, using optical measurements and multivariate calibration by neural networks, for developing a new method for emulsion destabilization monitoring. The technique has shown good accuracy in rebuilding the droplet size distribution of emulsions for monomodal and bimodal distributions and different proportions of each droplet population, from the spectroscopic measurements, indicating the viability of this method for monitoring such emulsions. This study is part of a joint project between the University of São Paulo and the University of Bremen, within the BRAGECRIM program (Brazilian German Cooperative Research Initiative in Manufacturing) and is financially supported by FAPESP, CAPES, FINEP and CNPq (Brazil), and DFG (Germany). / Sem resumo em português.
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Caracterização do material particulado em Cubatão / CHARACTERIZATION OF PARTICULATE MATTER IN CUBATÃOValarini, Simone Fernandes 05 May 2011 (has links)
Neste trabalho foi feita uma caracterização do material particulado coletado no Centro de Capacitação e Pesquisa em Meio Ambiente (CEPEMA) localizado na cidade de Cubatão, na Baixada Santista. As coletas ocorreram entre março de 2009 e novembro de 2010, utilizando amostradores de material particulado fino, grosso e inalável (Mini-Vol) e um impactador em cascata (MOUDI) para as várias frações do material particulado, durante oito campanhas experimentais. Foi realizada uma caracterização climatológica com os dados de temperatura, pressão atmosférica, umidade relativa, velocidade e direção do vento das estações da CETESB em Cubatão: Centro (10 anos), Vila Parisi (10 anos) e Vale do Mogi (4 anos). Os dados de chuva foram obtidos da Defesa Civil para a cidade de Santos. A maior parte das coletas de 2009 ocorreu em períodos em que houve precipitação, ao passo que as coletas de 2010 foram amostradas em períodos mais secos. O material particulado fino (MPF) teve concentrações médias de: 15,7 e 18,8 g m-3 em 2009 e 2010, respectivamente, quando coletado pelo MOUDI; e 15,8 e 23,6 g m-3, quando coletado pelo Mini-Vol. O material particulado grosso (MPG) teve concentrações médias de: 11,4 e 14,1 g m-3 em 2009 e 2010, respectivamente, quando coletado pelo MOUDI; e 18,9 e 13,4 g m-3, quando coletado pelo Mini-Vol. As análises de refletância mostraram que o Black Carbon está quase totalmente no MPF, chegando a 15% (20%) da massa do MPF quando coletado pelo MOUDI (Mini-Vol). Os íons dominantes são sulfato (SO42), nitrato (NO3), sódio (Na+), amônio (NH4+) e cálcio (Ca2+) e os elementos dominantes são enxofre (S), silício (Si) e ferro (Fe). As distribuições de tamanho mostram uma moda de nucleação bastante pronunciada para o S, K, Cl e P, indicando a contribuição de fontes antropogênicas e formação secundária do aerossol. As maiores concentrações de Si, Cl, Ca, Fe, Ca2+, NO3 e Na+ se encontram no MPG. Para o Cl e Na+, foram encontradas maiores concentrações nas amostras diurnas com vento do quadrante sul-sudoeste na estação do Centro, demonstrando a contribuição marinha. / This work evaluated the particulate matter (PM) collected at the Environmental Research and Training Center (CEPEMA) located in Cubatão City. Sampling was made between 2009, March and 2010, November for fine, coarse and inhalable aerosol (Mini-Vol) and for the various fractions of PM with a cascade impactor (MOUDI) during eight experimental campaigns. A climatological study was performed for temperature, pressure, relative humidity, wind speed and direction using data from CETESB stations: Centro (10 years), Vila Parisi (10 years) and Vale do Mogi (4 years). Precipitation data was obtained from the Civil Defense for the city of Santos. Most samplings made during 2009 were concomitant with rainy days, whereas 2010 samplings were made in drier periods. Fine particulate matter (FPM) had average concentrations of: 15.7 and 18.8 g m-3 in 2009 and 2010, respectively, with MOUDI and 15.8 and 23.6 g m-3, with Mini-Vol. Coarse Particulate Matter (CPM) had average concentrations of: 11.4 and 14.1 g m-3 in 2009 and 2010, respectively, with MOUDI, and 18.9 and 13.4 g m-3, with Mini-Vol. Reflectance analysis showed that the Black Carbon is almost completely in the FPM, reaching up to 15 % (20 %) of the FPM mass when sampled with MOUDI (Mini-Vol). Dominant ions are sulfate (SO42-), nitrate (NO3-), sodium (Na+), ammonium (NH4+) and calcium (Ca2+) and the dominant elements are sulfur (S), silicon (Si) and iron (Fe). The size distributions shows a very pronounced nucleation mode for the S, K, P and Cl, indicating the contribution of anthropogenic sources and secondary aerosol formation. The highest concentrations of Si, Cl, Ca, Fe, Ca2+, NO3- and Na+ are in CPM. For Cl- and Na+, major concentrations were found in samples with diurnal south-southwest wind indicating marine aerosol contribution.
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