Search results

Filters

  • Journals
  • Authors
  • Keywords
  • Date
  • Type

Search results

Number of results: 8
items per page: 25 50 75
Sort by:
Download PDF Download RIS Download Bibtex

Abstract

To produce the lime required for the Bayer process, two parallel flow regenerative shaft kilns (PFR) were used in the Iran Alumina plant located in Jajarm, North Khorasan Province, Iran. In this study, the calcination conditions of limestone were modelled in a laboratory furnace by considering three factors of limestone size, temperature and calcination time using the Box-Behnken method. The calcination model of limestone was obtained using a quadratic equation. Due to the importance of limestone dust in the performance of industrial kilns, conditions of calcification and its reactivity with water were examined at three temperature ranges of 800, 1000, and 1200°C, by two methods of titration and standard ASTM C110. The results indicated a decrease in reactivity of lime relative to the increased temperature of calcination and the lack of forming the burnt lime particles that stick together (blocking). Finally, the ratio of input limestone (kg) to fuel (m3) was reduced from 16.4 to 15.3 to increase the average temperature of the burning zone to 1000°C. Also, excess air was reduced from 40 to 20%. In this condition, the lime quality was increased by about 6% in the kilns.
Go to article

Authors and Affiliations

Hosseinali Mirzaei
1
ORCID: ORCID
Mohammad Noaparast
1
ORCID: ORCID
Hadi Abdollahi
1
ORCID: ORCID

  1. School of Mining Engineering, College of Engineering, University of Tehran, Tehran, Iran
Download PDF Download RIS Download Bibtex

Abstract

Contamination of the natural environment with petroleum pollution is still a frequent and particularly dangerous phenomenon, thus there is a need to remove these pollutants. Various types of mineral sorbents (silicate minerals, zeolites, perlite, diatomite, clay rocks) are highly valued in remediation processes due to their affordable, big selectivity and high efficiency. However, many sorbents are not resistant to moisture, which limits their use. The hydrophobization process improves the effectiveness of sorbents used in a humid environment. The DAMSORB produced by IM-POL was hydrophobized with a methanolic stearic acid solution. The use of cheap stearic acid as a modifier is economically advantageous. The evaluation of the hydrophobic properties of the modified material was performed on the basis of the results obtained from the tests: water absorption, floating on the water surface and the contact angles were determined. Tests of the sorption of petroleum-derived compounds were performed on the basis of three procedures: in accordance with the technical sheet of the leading producer of hydrophobic sorption materials in Poland, the Westighouse’s method in the oil layer and the Westighouse’s method on a flat surface. The modified sorbent floats on the surface of the water very well. The average value of the contact angle for the modified sample is 104 degrees. Material is super hydrophobic. In the water environment, the hydrophobized samples have a higher absorption capacity in relation to oil contaminations compared to the raw material. Features of the modified sorbent, such as good buoyancy on the water surface, low affinity to water and better absorption of oil from the solution, make it possible to use the material to remove petroleum contamination from water and highly moist surfaces.
Go to article

Authors and Affiliations

Elżbieta Vogt
1
ORCID: ORCID
Karolina Topolska
1

  1. AGH University of Science and Technology, Kraków, Poland
Download PDF Download RIS Download Bibtex

Abstract

The homogeneity of an immiscible liquid–liquid system was investigated in a baffled vessel agitated by a Rushton turbine. The dispersion homogeneity was analyzed by comparing Sauter mean diameters and drop size distribution (DSD) determined in different measured regions for various impeller speeds. The sizes of droplets were obtained by the in-situ measurement technique and by the Image Analysis (IA) method. Dispersion kinetics was successfully fitted with Hong and Lee (1983) model. The effect of intermittency turbulence on drop size reported by Bałdyga and Podgórska (1998) was analyzed and the multifractal exponent ������ was evaluated.
Go to article

Bibliography

Bałdyga J., Bourne J.R., 1993. Drop breakup and intermittent turbulence. J. Chem. Eng. Japan, 26, 738–741. DOI: 10.1252/jcej.26.738.

Bałdyga J., Bourne J.R., 1995. Interpretation of turbulent mixing using fractals and multifractals. Chem. Eng. Sci., 50, 381–400. DOI: 10.1016/0009-2509(94)00217-F.

Bałdyga J., PodgórskaW., 1998. Drop break-up in intermittent turbulence. Maximum stable drop size and transient sizes of drops. Can. J. Chem. Eng., 76, 456–470. DOI: 10.1002/cjce.5450760316.

Bucciarelli E., Formánek R., Kysela B., Fort I., Šulc R., 2019. Dispersion kinetics in mechanically agitated vessel. EPJ Web Conf., 213, 02008. DOI: 10.1051/epjconf/201921302008.

Chen H.T., Middleman S., 1967. Drop size distribution in agitated liquid–liquid systems. AIChE J., 13, 989–995. DOI: 10.1002/aic.690130529.

Formánek R., Kysela B., Šulc R., 2019a. Drop size evolution kinetics in a liquid–liquid dispersions system in a vessel agitated by a Rushton turbine. Chem. Eng. Trans., 74, 1039–1044. DOI: 10.3303/CET1974174.

Formánek R., Kysela B., Šulc R., 2019b. Image analysis of particle size: effect of light source type. EPJ Web Conf., 213, 02021. DOI: 10.1051/epjconf/201921302021.

Formánek R., Šulc R., 2019c. Dispersion of immiscible liquid–liquid system in a vessel agitated by a Sawtooth impeller: Drop size time evolution. Proceedings of the International Conference Experimental Fluid Mechanics 2019. Franzensbad, Czech Republic, 19–22 November 2019, 136–139.

Formánek R., Šulc R., 2020. The liquid–liquid dispersion homogeneity in a vessel agitated by a high-shear sawtooth impeller. Processes, 8, 1012. DOI: 10.3390/pr8091012.

Hinze J.O., 1955. Fundamentals of the hydrodynamic mechanism of splitting in dispersion processes. AIChE J., 1, 289–295. DOI: 10.1002/aic.690010303.

Hong P.O., Lee J.M., 1983. Unsteady-state liquid–liquid dispersions in agitated vessels. Ind. Eng. Chem. Process Des. Dev., 22, 130–135. DOI: 10.1021/i200020a021.

Jasikova D., Kotek M., Kysela B., Sulc R., Kopecky V., 2018. Compiled visualization with IPI method for analysing of liquid–liquid mixing process. EPJ Web Conf., 180, 02039. DOI: 10.1051/epjconf/201818002039.

Khalil A., Puel F., Chevalier Y., Galvan J.-M., Rivoire A., Klein J.-P., 2010. Study of droplet size distribution during an emulsification process using in situ video probe coupled with an automatic image analysis. Chem. Eng. J., 165, 946–957. DOI: 10.1016/j.cej.2010.10.031.

Kolmogorov A.N., 1949. On the breakage of drops in a turbulent flow. Dokl. Akad. Nauk SSSR, 66, 825–828. Kraume M., Gäbler A., Schulze K., 2004. Influence of physical properties on drop size distribution of stirred liquid–liquid dispersions. Chem. Eng. Technol., 27, 330–334. DOI: 10.1002/ceat.200402006.

Maaß S., Kraume M., 2012. Determination of breakage rates using single drop experiments. Chem. Eng. Sci., 70, 146–164. DOI: 10.1016/j.ces.2011.08.027.

Malík M., Primas J., Kotek M., Jašíková D., Kopecký V., 2019. Mixing of two immiscible phases measured by industrial electrical impedance tomography system. Mech. Ind., 20, 707. DOI: 10.1051/meca/2019081.

Maluta F., Montante G., Paglianti A., 2020. Analysis of immiscible liquid–liquid mixing in stirred tanks by Electrical Resistance Tomography. Chem. Eng. Sci., 227, 115898. DOI: 10.1016/j.ces.2020.115898.

Pacek A.W., Chamsart S, Nienow A.W., Bakker A., 1999. The influence of impeller type on mean drop size and drop size distribution in an agitated vessel. Chem. Eng. Sci., 54, 4211–4222. DOI: 10.1016/S0009-2509(99)00156-6.

Rodgers T.L., Cooke M., 2012. Correlation of drop size with sheat tip speed. 14��ℎ European Conference on Mixing. Warszawa, Poland, 10–13 September 2012, 407–412.

Šulc R., Ditl P., Fort I., Jašíkova D., Kotek M., Kopecký V., Kysela B., 2017. Local velocity scaling in T400 vessel agitated by Rushton turbine in a fully turbulent region. EPJ Web Conf., 143, 02120. DOI: 10.1051/epjconf/201714302120.

Šulc R., Pešava V., Ditl P., 2015. Local turbulent energy dissipation rate in a vessel agitated by a Rushton turbine. Chem. Process Eng., 36, 135–149. DOI: 10.1515/cpe-2015-0011.

Zhou G, Kresta S.M., 1998. Evolution of drop size distribution in liquid–liquid dispersions for various impellers. Chem. Eng. Sci., 53, 2099–2113. DOI: 10.1016/S0009-2509(97)00437-5.
Go to article

Authors and Affiliations

Roman Formánek
1
Radek Šulc
1

  1. Czech Technical University in Prague, Faculty of Mechanical Engineering, Department of Process Engineering, Technická 4, 160 00 Prague, Czech Republic
Download PDF Download RIS Download Bibtex

Abstract

The selection of the formwork system for high rise building affects the entire construction project duration and cost. The study reports the factors influencing the selection of different formwork system in the construction of high rise buildings through structural questionnaire survey from the client, contractor, consultant, and interviews with expert members. Total of 40 technical factors was identified from the literature and 220 filled questionnaires were received from the respondent. Relative Importance Index method is used to find the topmost factors affecting the selection of formwork system. Additionally, from factor analysis 22 factors were identified to have a correlation with one another. Regression analysis reveals that duration of the project, maintenance cost, adaptability, and safety have impact on formwork selection across time, cost and quality. These findings could potentially increase the construction company’s existing knowledge in relation to formwork selection.

Go to article

Authors and Affiliations

Viswanathan Rajeshkumar
V. Sreevidya
Download PDF Download RIS Download Bibtex

Abstract

Freeform surfaces have wider engineering applications. Designers use B-splines, Non-Uniform Rational B-splines, etc. to represent the freeform surfaces in CAD, while the manufacturers employ machines with controllers based on approximating functions or splines. Different errors also creep in during machining operations. Therefore the manufactured freeform surfaces have to be verified for conformance to design specification. Different points on the surface are probed using a coordinate measuring machine and substitute geometry of surface established from the measured points is compared with the design surface. The sampling points are distributed according to different strategies. In the present work, two new strategies of distributing the points on the basis of uniform surface area and dominant points are proposed, considering the geometrical nature of the surfaces. Metrological aspects such as probe contact and margins to be provided along the sides have also been included. The results are discussed in terms of deviation between measured points and substitute surface as well as between design and substitute surfaces, and compared with those obtained with the methods reported in the literature.

Go to article

Authors and Affiliations

G. Rajamohan
M. Shunmugam
G. Samuel
Download PDF Download RIS Download Bibtex

Abstract

Cranes belong to underactuated mechanical systems, an important subclass of nonlinear control systems typified by fewer control inputs than the degrees of freedom. The usual performance goal of a crane is to execute a desired motion of the load, specified by as many outputs as the control inputs. The challenging task of inverse simulation study, in which control of the underactuated system subject to execute the partly specified motion is determined, is usually formulated in independent variables. In this paper, a dependent variable formulation is motivated and developed. Compared to the independent variable formulation, the use of dependent variables leads to much simpler governing equations, and their effective number is reduced. The developed formulation is illustrated by a simulation model of an overhead crane executing a rest-to-rest maneuver of the load along a specified curvilinear trajectory.

Go to article

Authors and Affiliations

Wojciech Blajer
Krzysztof Kołodziejczyk
Download PDF Download RIS Download Bibtex

Abstract

This article examines two collections of manuscripts (previously unanalyzed) with poems which make up Leopold Staff’s debut volume The Dreams of Power. The poet offered them as a gift to Maryla Wolska who deposited them in the Michał Pawlikowski Archives at Medyka. With access to the fi rst, nearly complete, collection we can get an insight into the process of selecting poems for the version that was to go to print (1899–1901). As most of the poems are dated, we are able to establish their sequence and reconstruct the changing concept of their selection. Of special value are twelve poems which had been dropped in the process, and for most part remained unpublished. Each of them is presented briefl y in the article. Apart from making this discovery, the article demonstrates that Leopold Staff’s debut volume as we know it had an earlier version with a set of poems, different from the one that was earmarked for publication under that title.

Go to article

Authors and Affiliations

Krystyna Zabawa
ORCID: ORCID

This page uses 'cookies'. Learn more