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1
Content available Three-phases bubble column to polyethylene terephthalate depolymerization for cement mortar composites improvement
Hameed A. M., Alzuhairi M., Ibrahim S. I.
Journal of Achievements in Materials and Manufacturing Engineering
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2022
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Vol. 112, nr 1
5--12
EN
Purpose: This paper aims to prepare depolymerized polyethylene terephthalate (DPET) powder from recycled plastic water bottles. Adding this DPET powder to the cement mortar was also studied. Design/methodology/approach: The adopted PET depolymerization process includes the usage of both ethylene glycol (EG) as solvent and nano-MgO as a catalyst. A bubble column reactor was designed for this process. Five different mortar groups were made; each has different DPET content of 0%, 1%, 3%, 6% and 9% as a sand replacement. The flexural strength testand the water absorption measurement are done after two curing periods: 7 and 28 days. Findings: The research finding demonstrated that the flexural strength of mortar was reduced by increasing the DPET powder percentage and the maximum dropping was 15% when 9% of DPET was added. The ability of the mortar to absorb the water was reduced by 14.5% when DPET powder was 9%. The mortar microstructure is featured with fewer cavities and porosity. Research limitations/implications: This work’s employed bubble column technique is limited only to the laboratory environment and needs to be scaled up within industrial mass production. For future research, it is suggested to decrease depolymerization time by using smaller pieces of plastic water bottle waste and trying other types of nanocatalyst. Practical implications: The modified mortar can be utilized in areas where moisture, rainfalls, and sanitation systems exist. Originality/value: The article claims that depolymerized waste PET improves chemical process efficiency by lowering reaction time and improving mass and heat transfer rates. Besides, this approach saves money. It is found out that the depolymerized plastic waste is much more functional due to its high cohesion capability than being used as small PET pieces.
2
Content available Energy consumption in terms of shear stress for two types of membrane bioreactors used for municipal wastewater treatment processes
Ratkovich N., Bentzen T., Rasmussen M.
Archives of Thermodynamics
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2012
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Vol. 33, no. 2
85-106
EN
Two types of submerged membrane bioreactors (MBR): hollow fiber (HF) and hollow sheet (HS), have been studied and compared in terms of energy consumption and average shear stress over the membrane wall. The analysis of energy consumption was made using the correlation to determine the blower power and the blower power demand per unit of permeate volume. Results showed that for the system geometries considered, in terms the of the blower power, the HF MBR requires less power compared to HS MBR. However, in terms of blower power per unit of permeate volume, the HS MBR requires less energy. The analysis of shear stress over the membrane surface was made using computational fluid dynamics (CFD) modelling. Experimental measurements for the HF MBR were compared with the CFD model and an error less that 8% was obtained. For the HS MBR, experimental measurements of velocity profiles were made and an error of 11% was found. This work uses an empirical relationship to determine the shear stress based on the ratio of aeration blower power to tank volume. This relationship is used in bubble column reactors and it is extrapolate to determine shear stress on MBR systems. This relationship proved to be overestimated by 28% compared to experimental measurements and CFD results. Therefore, a corrective factor is included in the relationship in order to account for the membrane placed inside the bioreactor.
3
Content available Multifractal properties of large bubble paths in a single bubble column
Mosdorf R., Wyszkowski T., Dąbrowski K.
Archives of Thermodynamics
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2011
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Vol. 32, no. 1
3-20
EN
In the paper the paths of bubbles emitted from the brass nozzle with inner diameter equal to 1.6 mm have been analyzed. The mean frequency of bubble departure was in the range from 2 to 65.1 Hz. Bubble paths have been recorded using a high speed camera. The image analysis technique has been used to obtain the bubble paths for different mean frequencies of bubble departures. The multifractal analysis (WTMM - wavelet transform modulus maxima methodology) has been used to investigate the properties of bubble paths. It has been shown that bubble paths are the multifractals and the influence of previously departing bubbles on bubble trajectory is significant for bubble departure frequency f[b] > 30 Hz.
4
Content available Mathematical modelling of wet oxidation of excess sludge
Chacuk A., Imbierowicz M.
Polish Journal of Chemical Technology
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2007
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Vol. 9, nr 2
1-4
EN
A mathematical model enabling a quantitative description of wet oxidation of excess sludge in continuous bubble columns is proposed. The model consists of mass and heat transfer kinetic equations and material and heat balance equations of gas and liquid phases flowing through the absorber. The equations of material and heat balance refer to a parallel, co- current flow of gas and liquid phase and take into account a complex chemical reaction in the liquid phase core. The proposed model was used in a numerical simulation of wet oxidation in a bubble absorber for different process conditions: flow rate and composition of the gas and liquid phase, temperature and pressure, and different heights and diameters of the column.
5
Content available remote Mathematical modelling of wet oxidation of excess sludge in bubble columns
Chacuk A., Imbierowicz M.
Polish Journal of Chemical Technology
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2006
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Vol. 8, nr 2
1-4
EN
A mathematical model enabling a quantitative description of wet oxidation of excess sludge in continuous bubble columns is proposed. The model consists of mass and heat transfer kinetic equations as well as material and heat balance equations of gas and liquid phases flowing through the absorber. The equations of material and heat balance refer to parallel, the co- and counter-current flow of gas and liquid phase and take a complex chemical reaction in the liquid phase core into account. The proposed model was used in a numerical simulation of wet oxidation in a bubble absorber for different process conditions: the flow rate and the composition of the gas and liquid phase, the temperature and pressure, and different heights and diameters of the column.
6
Obliczenia symulacyjne hydrodynamiki kolumny barbotażowej
Rudniak L., Bielski P., Moniuk W., Pohorecki R.
Inżynieria Chemiczna i Procesowa
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2001
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T. 22, z. 3E
1237--1242
PL
W celu określenia wpływu własności fizykochemicznych cieczy na wielkość zatrzymania gazu wykonano obliczenia symulacyjne hydrodynamiki laboratoryjnej kolumny barbotażowej dla siedmiu cieczy organicznych w temperaturze pokojowej i pod ciśnieniem normalnym przy użyciu modelu ASMM zaimplementowanego w programie FLUENT. Wyniki obliczeń porównano z danymi doświadczalnymi.
EN
In order to establish the influence of liquid properties on gas holdup numerical simulation of laboratory bubble column hydrodynamics were carried out for seven organic liquids operated at atmospheric pressure and low temperature using ASMM model implemented in FLUENT software. Results from computer simulation were compared with experimental data.
7
Konstrukcja czujnika tlenu a przebieg krzywych rozkładu czasu przebywania gazu w kolumnie barbotażowej
Kawalec-Pietrenko B., Szczepaniak J.
Inżynieria i Aparatura Chemiczna
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1998
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Nr 2
6-10
PL
Badano rozkład czasów przebywania fazy gazowej w kolumnie barbotażowej za pomocą elektrochemicznego czujnika tlenu. Czujnik tlenu umieszczano w strumieniu gazu opuszczającym kolumnę barbotażową. Jako znacznika użyto par acetonu, benzenu, heksanu, octanu etylu, ksylenu i toluenu. Wykazano, że rodzaj membrany czujnika ma zasadnicze znaczenie dla sygnału ciśnienia cząstkowego tlenu w powietrzu zawierającym pary substancji organicznych. Stwierdzono, że w dobrej zgodności z wartościami cytowanymi w literaturze pozostają liczby Pecleta obliczone na podstawie krzywych rozkładu czasu przebywania gazu uzyskanych za pomocą czujnika tlenu z membraną teflonową i przy użyciu jako znacznika par dowolnych spośród badanych substancji organicznych.
EN
The gas residence time distribution in a bubble column using the electro-chemical oxygen sensor has been investigated. The gas sensor was situated inside gas stream leaving the bubble column. Vapours of acetone, benzene, hexane, ethyl acetate, xylene and toluene were used as a marker. It has been proved that a type of the sensor membrane influenced decisively the oxygen partial pressure in the air comprising vapours of organic compounds. It has been stated that Peclet numbers calculated on the basis of the gas residence time distribution curves which were obtained by the oxygen sensor with the Teflon membrane and using any of the organic compounds vapours tested, conformed sufficiently well to the values cited in literature.
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