Witold Żukowski - Academia.edu (original) (raw)
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Papers by Witold Żukowski
Energies, 2020
Aluminosilicate microspheres are a valuable fraction of coal fly ash with diverse applications du... more Aluminosilicate microspheres are a valuable fraction of coal fly ash with diverse applications due to their low density. Currently, there is no efficient and ecologically rational method of cenosphere recovery from fly ash. A combination of dry methods for the recovery of both fine ash particles and aluminosilicate microspheres from coal fly ash is presented. It is comprised of fluidised bed separation followed by screening and pneumatic separation in a free-fall air chamber. Fluidised bed separation was assisted by a mechanical activator to prevent agglomeration. This step reduced the portion of material that required further treatment by 52–55 wt.%, with the recovery of microspheres exceeding 97%. Then, the concentrates were individually subjected to pneumatic separation. The final separation product for the fly ash containing 0.64 wt.% cenospheres was a cenosphere concentrate that constituted about 17 wt.% of the initial fly ash. The recovery of cenospheres was around 81%. Usage ...
In this paper, the possibility of achieving a stable fluidised bed made of the cenospheres was ex... more In this paper, the possibility of achieving a stable fluidised bed made of the cenospheres was examined. Cenospheres are the waste material from hard coal power plants. This material is perfectly spherical, and it is thin-walled and filled with gases (mainly CO2, N2). Because of their low density, particle size and sphericity, cenospheres can be easily fluidised even at low flow rates of the fluidising medium. Moreover, the application of acoustic waves during the fluidisation of cenospheres removes the apparent effect of double stationary states and moves the minimum fluidisation velocity into lower gas flow rates.
Fluidization is a two phase process involves on the suspension powdery solid layer in the stream ... more Fluidization is a two phase process involves on the suspension powdery solid layer in the stream of fluid (gas or liquid) flowing vertically from the bottom of the column. Intensive mixing occurs in bed and developed interfacial contact area creates the high heat and mass transfer coefficients. Nature of thefluidized bed allows to create a very good environment for the processes such as drying, combustion or conducting catalytic chemical reactions. The purpose of the research was to determine the influence of changing the fluidizing medium velocity to the process of mixing taking place inside the bed of different weights and grain size. The range of the research included the study of heterogeneity of porosity, creation and association of bubbles of different sizes and shapes. The research was conducted in a laboratory reactor with bubbles, atmospheric fluidized bed in the form of quartz sand of varying particle size and weight. The air given through perforated gas distributor was fl...
Combustion and Flame, 2019
A fluidised bed of low-density (< 0.9 g/cm 3) hollow microspheres (cenospheres) was used for the ... more A fluidised bed of low-density (< 0.9 g/cm 3) hollow microspheres (cenospheres) was used for the combustion of selected liquid and solid fuels. It was proven that with such a fluidised bed, these materials burned inside the bed, not on its surface. For the purpose of some experiments the cenospheres with a nanometric, catalytic layer of iron oxide was prepared by original method using fluidised bed and Fe(CO) 5 as a Fe 2 O 3 precursor. The combustion was examined in the temperature range of 40 0-70 0 °C. When the inert fluidised bed was heated to 700 °C, ∼90% of the carbon of the degraded samples reacted to CO 2 (93% for paraffin wax, and 84% for paraffin oil and glycerol). When the process was performed in the catalytic bed, ∼90% of the conversion to CO 2 of the carbon contained in glycerol and paraffin fuels was achieved at 500 °C. The acoustic analysis confirmed that combustion takes place either just in the bubbles (inert bed) or both on the surface of particles and in the bubbles (catalytic bed). The analysis of acoustic signals showed that the explosions occurring in the bed do not form a deterministic pattern.
PJCT, 2008
Reduction of carbon dioxide emission through the sorption in situ using a fluidised bed reactor T... more Reduction of carbon dioxide emission through the sorption in situ using a fluidised bed reactor The paper discusses the possibility of using the reversible reaction CaCO3 ↔ CaO + CO2 for the cyclic capture and release of CO2 directly inside a fluidised bed combustor. This could lead to the lowering of CO2 emissions into the atmosphere, as part of an effort to mitigate the greenhouse effect associated with the rising atmospheric CO2 concentrations resulting from obtaining energy from burning fossil fuels. An enrichment coefficient E has been introduced and defined as a measure of the production of CO2 (on calcining CaCO3) or its removal (on carbonation of CaO) with respect to the level associated with fuel combustion alone. The observations made on the effect of introducing an additional external stream of CO2 on the efficiency of the chemical capture process have been described. Through an appropriate control of the temperature inside the reactor it is possible to change the value o...
Combustion and Flame, 2002
A laboratory size quartz reactor has been used to burn methane, LPG (liquid petroleum gas) and ar... more A laboratory size quartz reactor has been used to burn methane, LPG (liquid petroleum gas) and aromatic hydrocarbon vapors in a bubbling fluidized bed. Most measurements and observations were made for lean mixtures of fuel and air with quartz sand in the bed, but in some experiments NO, NO2, or CCl4 were introduced with the fuel, the stoichiometry was varied or the bed material changed. The quantities monitored were the bed temperature at two levels and the freeboard concentrations of O2, CO2, CO, NO, NO2, and in some runs, ...
Environment Protection Engineering, 2006
Much of air pollution is due to burning of fossil fuels, but some purpose-produced biofuels and b... more Much of air pollution is due to burning of fossil fuels, but some purpose-produced biofuels and biowastes can be burned very cleanly. Historic towns should maintain high standards of air purity, but deriving all heat and power from burning of biomass cannot be feasible, but using some biowastes can help locally, with savings on energy transport and flue gas cleaning systems. It can also contribute to reducing greenhouse emissions. This has been demonstrated, eg, at Niepołomice where several types of waste have been effectively and ...
Archivum Combustionis, 2010
Polymers are used to produce plastics and nowadays there are lots of everyday usage products made... more Polymers are used to produce plastics and nowadays there are lots of everyday usage products made from polymers. Consequently there are lots of waste polymers in municipal solid waste as well. Combustion of waste polymers is a very practical method for the total disposal of them from the environment but although the typical chemical composition of natural fuels, polymers are very specific fuels and it is not easy to burn them giving complete combustion products, that are CO2 and H2O. In the following work the method of the ...
Combustion and Flame, 1999
Acoustic effects accompany the combustion of gaseous fuels in bubbling fluidized beds of inert ma... more Acoustic effects accompany the combustion of gaseous fuels in bubbling fluidized beds of inert materials. In an exploratory study of this effect, using a laboratory-size fluidized bed in which a mixture of propane and butane was burned, the bed's temperature was monitored continuously and the acoustic effects were recorded. The temperature ranges over which combustion was "noisy" and "quiet" were identified; the acoustic signals were shown to fall into a number of characteristic patterns, which can yield information about the character of the combustion process, in relation to "mini-explosions" in bubbles of the combustible mixture rising through the bed, their intensity and frequency. The results could be used to develop a new method of controlling the operation of fluidized beds burning a gaseous fuel.
Energies, 2020
Aluminosilicate microspheres are a valuable fraction of coal fly ash with diverse applications du... more Aluminosilicate microspheres are a valuable fraction of coal fly ash with diverse applications due to their low density. Currently, there is no efficient and ecologically rational method of cenosphere recovery from fly ash. A combination of dry methods for the recovery of both fine ash particles and aluminosilicate microspheres from coal fly ash is presented. It is comprised of fluidised bed separation followed by screening and pneumatic separation in a free-fall air chamber. Fluidised bed separation was assisted by a mechanical activator to prevent agglomeration. This step reduced the portion of material that required further treatment by 52–55 wt.%, with the recovery of microspheres exceeding 97%. Then, the concentrates were individually subjected to pneumatic separation. The final separation product for the fly ash containing 0.64 wt.% cenospheres was a cenosphere concentrate that constituted about 17 wt.% of the initial fly ash. The recovery of cenospheres was around 81%. Usage ...
In this paper, the possibility of achieving a stable fluidised bed made of the cenospheres was ex... more In this paper, the possibility of achieving a stable fluidised bed made of the cenospheres was examined. Cenospheres are the waste material from hard coal power plants. This material is perfectly spherical, and it is thin-walled and filled with gases (mainly CO2, N2). Because of their low density, particle size and sphericity, cenospheres can be easily fluidised even at low flow rates of the fluidising medium. Moreover, the application of acoustic waves during the fluidisation of cenospheres removes the apparent effect of double stationary states and moves the minimum fluidisation velocity into lower gas flow rates.
Fluidization is a two phase process involves on the suspension powdery solid layer in the stream ... more Fluidization is a two phase process involves on the suspension powdery solid layer in the stream of fluid (gas or liquid) flowing vertically from the bottom of the column. Intensive mixing occurs in bed and developed interfacial contact area creates the high heat and mass transfer coefficients. Nature of thefluidized bed allows to create a very good environment for the processes such as drying, combustion or conducting catalytic chemical reactions. The purpose of the research was to determine the influence of changing the fluidizing medium velocity to the process of mixing taking place inside the bed of different weights and grain size. The range of the research included the study of heterogeneity of porosity, creation and association of bubbles of different sizes and shapes. The research was conducted in a laboratory reactor with bubbles, atmospheric fluidized bed in the form of quartz sand of varying particle size and weight. The air given through perforated gas distributor was fl...
Combustion and Flame, 2019
A fluidised bed of low-density (< 0.9 g/cm 3) hollow microspheres (cenospheres) was used for the ... more A fluidised bed of low-density (< 0.9 g/cm 3) hollow microspheres (cenospheres) was used for the combustion of selected liquid and solid fuels. It was proven that with such a fluidised bed, these materials burned inside the bed, not on its surface. For the purpose of some experiments the cenospheres with a nanometric, catalytic layer of iron oxide was prepared by original method using fluidised bed and Fe(CO) 5 as a Fe 2 O 3 precursor. The combustion was examined in the temperature range of 40 0-70 0 °C. When the inert fluidised bed was heated to 700 °C, ∼90% of the carbon of the degraded samples reacted to CO 2 (93% for paraffin wax, and 84% for paraffin oil and glycerol). When the process was performed in the catalytic bed, ∼90% of the conversion to CO 2 of the carbon contained in glycerol and paraffin fuels was achieved at 500 °C. The acoustic analysis confirmed that combustion takes place either just in the bubbles (inert bed) or both on the surface of particles and in the bubbles (catalytic bed). The analysis of acoustic signals showed that the explosions occurring in the bed do not form a deterministic pattern.
PJCT, 2008
Reduction of carbon dioxide emission through the sorption in situ using a fluidised bed reactor T... more Reduction of carbon dioxide emission through the sorption in situ using a fluidised bed reactor The paper discusses the possibility of using the reversible reaction CaCO3 ↔ CaO + CO2 for the cyclic capture and release of CO2 directly inside a fluidised bed combustor. This could lead to the lowering of CO2 emissions into the atmosphere, as part of an effort to mitigate the greenhouse effect associated with the rising atmospheric CO2 concentrations resulting from obtaining energy from burning fossil fuels. An enrichment coefficient E has been introduced and defined as a measure of the production of CO2 (on calcining CaCO3) or its removal (on carbonation of CaO) with respect to the level associated with fuel combustion alone. The observations made on the effect of introducing an additional external stream of CO2 on the efficiency of the chemical capture process have been described. Through an appropriate control of the temperature inside the reactor it is possible to change the value o...
Combustion and Flame, 2002
A laboratory size quartz reactor has been used to burn methane, LPG (liquid petroleum gas) and ar... more A laboratory size quartz reactor has been used to burn methane, LPG (liquid petroleum gas) and aromatic hydrocarbon vapors in a bubbling fluidized bed. Most measurements and observations were made for lean mixtures of fuel and air with quartz sand in the bed, but in some experiments NO, NO2, or CCl4 were introduced with the fuel, the stoichiometry was varied or the bed material changed. The quantities monitored were the bed temperature at two levels and the freeboard concentrations of O2, CO2, CO, NO, NO2, and in some runs, ...
Environment Protection Engineering, 2006
Much of air pollution is due to burning of fossil fuels, but some purpose-produced biofuels and b... more Much of air pollution is due to burning of fossil fuels, but some purpose-produced biofuels and biowastes can be burned very cleanly. Historic towns should maintain high standards of air purity, but deriving all heat and power from burning of biomass cannot be feasible, but using some biowastes can help locally, with savings on energy transport and flue gas cleaning systems. It can also contribute to reducing greenhouse emissions. This has been demonstrated, eg, at Niepołomice where several types of waste have been effectively and ...
Archivum Combustionis, 2010
Polymers are used to produce plastics and nowadays there are lots of everyday usage products made... more Polymers are used to produce plastics and nowadays there are lots of everyday usage products made from polymers. Consequently there are lots of waste polymers in municipal solid waste as well. Combustion of waste polymers is a very practical method for the total disposal of them from the environment but although the typical chemical composition of natural fuels, polymers are very specific fuels and it is not easy to burn them giving complete combustion products, that are CO2 and H2O. In the following work the method of the ...
Combustion and Flame, 1999
Acoustic effects accompany the combustion of gaseous fuels in bubbling fluidized beds of inert ma... more Acoustic effects accompany the combustion of gaseous fuels in bubbling fluidized beds of inert materials. In an exploratory study of this effect, using a laboratory-size fluidized bed in which a mixture of propane and butane was burned, the bed's temperature was monitored continuously and the acoustic effects were recorded. The temperature ranges over which combustion was "noisy" and "quiet" were identified; the acoustic signals were shown to fall into a number of characteristic patterns, which can yield information about the character of the combustion process, in relation to "mini-explosions" in bubbles of the combustible mixture rising through the bed, their intensity and frequency. The results could be used to develop a new method of controlling the operation of fluidized beds burning a gaseous fuel.