Book on the public policy towards disability presents in a comprehensive manner the main system solutions for supporting disabled people in Poland. Selected problems related to the public ...interventions in the area of disability were also presented, and possible institutional adjustments were indicated.
Hungary and Poland are often placed in the same analytical framework from the period of their ‘negotiated revolutions’ to their autocratic turn. This article aims to look behind this apparent ...similarity focusing on opposition behaviour. The analysis demonstrates that the executive–parliament power structure, the vigour of the extra-parliamentary actors, and the opposition party frame have the strongest influence on opposition behaviour, and they provide the sources of difference between the two country cases: in Hungary an enforced power game and in Poland a political game constrain opposition opportunities and opposition strategic behaviour.
Energy plays a crucial role in the modern world. The acquisition and consumption of energy is unfortunately associated not only with economic development or the facilitation of everyday life, but ...also with a negative impact on the environment. To prevent these, measures are being taken which are part of a broad programme referred to as sustainable energy development (SED). A special place among energy consumers is occupied by households, as access to energy is a fundamental factor affecting the quality of life. The aim of this paper is to look at and assess the current situation of the household sector in the EU energy market in the context of SED and to point out similarities and differences between EU countries. The analysis considers factors based on SED indicators: final energy consumption per capita, energy prices offered to households, and the share of renewable energy in household energy consumption. The k-means method was used as a research tool. The results obtained indicate first of all that the EU countries are highly differentiated in terms of the analysed factors. It can be said that these differences result not only from the wealth of a given country, geographical location, or natural possibilities to use renewable energy sources, but mainly from the energy policies implemented in individual countries.
Unsaturated hydrocarbons: ethylene, propylene and acetylene are released into the mine atmosphere as a result of the self-heating of coal. Their concentrations in the mine air is one of the ...indicators for assessing the degree of development of coal self-heating process. The sorption capacity of coals with respect to hydrocarbons may cause their concentrations to decrease in the mine air, which may affect the correct self-heating assessment. This phenomenon is particularly important in the case of coals with a significant sorption capacity.
The paper presents the results of studies on sorption of unsaturated hydrocarbons: ethylene, propylene and acetylene carried out on six samples of Polish hard coals taken from the exploited coal seams. High-porous coals with a well-accessible pore system, large specific surface values, low metamorphism and high oxygen content are characterized by the highest sorption capacities. The hydrocarbon sorbed in the largest amount is acetylene, which is due to the smallest size of the acetylene molecule and its high reactivity. The amount of the sorption of ethylene and propylene is lower than that of acetylene and depends on the properties of the coals. Coals with high sorption capacities adsorb larger amounts of propylene than ethylene. For less sorbent coals, the opposite is true.
The volume of sorbed hydrocarbons decreases with the increase of the sorption temperature from 298 to 373 K. The temperature has the greatest influence on the volume of sorbed acetylene, the smaller the ethylene. The gas that is the least sensitive to the temperature increase is propylene.
On the basis of desorption studies, it has been found that the lowest degree of desorption from coals is displayed by propylene. Higher degrees of desorption were found for acetylene. Ethylene is desorbed the most from coals.
The concentration of ethylene in the mine atmosphere is the most frequently used indicator of temperature increase in coal in the self-heating process.
Ethylene is an unsaturated hydrocarbon that is released into the atmosphere of a mine as a result of an increase in the temperature of coal caused by the self-heating process. The content of ethylene ...in mine air is one of the indicators for assessing the degree of the coal self-heating process. Sorption capacities of hard coals with respect to ethylene may be the reason for the decrease in its concentration in mine air, which may affect the accuracy of self-heating process assessment. This phenomenon may be particularly important in the case of coals with significant sorption capacities. This paper presents the results of ethylene sorption studies carried out on six samples of bituminous coals collected from currently operational coal seams in Polish mines. The coals under analysis are characterized by varying sorption capacity with regard to ethylene. The highest sorption capacities were reported for low rank, high-porosity coals with easily accessible pore structure, high specific surface area values, and high oxygen content. The interactions between the electron-donor (and electron-acceptor) centers of coal surface and π electrons of double bonds in gas-sorbed molecules are significant in the process of ethylene sorption. Coals with low oxygen content and more nonpolar surface structure, low porosity, and compact internal structures are characterized by low ethylene sorption capacity. On the basis of desorption studies, ethylene is a gas which once adsorbed mostly desorbs from coals. The percentage of desorbed gas increases with increasing temperature and it is higher for coals with high sorption capacities. Some of the undesorbed ethylene molecules remain in the coal structure. They are permanently bonded to the surface of coals, and their number depends on the type of coals and their sorption capacities.
Acetylene is a mine air component in addition to other hydrocarbons: ethylene, propylene, propane and ethane. Increased acetylene concentrations in the mine atmosphere are associated with its ...emission from a coal deposit at elevated temperatures caused by the self-heating of coal. This study investigates the sorption capacity of hard coals with respect to acetylene, and the acetylene volume is related to the proportion between carbon and oxygen as well as to moisture and porosity levels. The largest amounts of acetylene are adsorbed by low-rank coals with high oxygen content, highly porous and characterized by large specific surface areas and high moisture content. Higher rank coals displaying lower porosity tend to adsorb significantly smaller amounts of acetylene. These coals have a compact structure, and their behavior is non-polar due to the presence of a layer of chain hydrocarbons surrounding the aromatic coal polymer. The analysis of desorption isotherms indicates that the process of acetylene adsorption is irreversible. Desorption isotherms do not coincide with adsorption isotherms, forming an open hysteresis loop. Certain amounts of acetylene held more firmly to the coal structure are likely to remain there, their actual quantities depending on the coal type. The adsorption of acetylene is a polar process, involving the electron-donor and electron-acceptor centers' interactions with dipolar molecules of acetylene. The heat of the adsorption of acetylene based on the Clausius–Clapeyron equation ranges from 15 to 27kJ/mol, depending on the type of coal and the degree of coverage.
In the consequence of acetylene adsorption, its concentration in mine air is reduced, which undermines the reliability of the self-heating hazard assessments.
•The studies on acetylene adsorption were performed on 6 samples of hard coals.•The largest amounts of acetylene are adsorbed by low-rank coals.•The process of acetylene adsorption is irreversible.•Acetylene adsorption can lead to a decrease in its concentration in mine air.
The analysis of the results of sorption absorbency of hard coals with respect to gases relevant in assessing the fire hazard (carbon monoxide, carbon dioxide, hydrogen, ethylene, propylene, and ...acetylene) was the aim of this study. Hard coals adsorb carbon dioxide and acetylene in the highest amount, and ethylene and propylene in a slightly smaller amount. The adsorption of carbon monoxide and hydrogen is very small. The amounts of adsorbed gases depend on the metamorphism degree of hard coals as well as on their porosity. Hard coals of high porosity with good accessibility of internal surface, of low metamorphism degree and of higher oxygen content are characterized by greater adsorption capacity. Fire gases generated from the self-heating center may be the subject to adsorption on hard coals, which results in the lower gas concentration at the measuring points and as a consequence in the change of fire indicators calculated on their basis. This phenomenon applies in particular to hard coals with high sorption absorbency and to the situation in which the self-heating center and the point of measurement of concentrations is considerably distant, which causes greater contact of the emitted gas with coal matter, and more possible intensification of the adsorption process.
Fire indicators are used to assess the development of the process of self-heating of coal. Gases, the concentration of which is the part of the particular fire indicator, should have a similar adsorption capacity. Indicators constructed on the basis of a very different adsorption capacity can be a source of errors due to the observed adsorption process.
•Sorption measurements of CO, CO2, H2, C2H4, C3H6, and C2H2 were conducted on hard coals.•Low-rank coals of high oxygen content and porosity sorb the largest amounts of gases.•Process of sorption may cause a decrease in concentration of those gases in mine air.•Fire indices should be constructed based on gases of similar sorbability.
The paper presents the results of chromatographic analyses of gas desorbed from freshly extracted different rank coal samples both, in the atmosphere of nitrogen and air. Samples in which coal ...remained in contact with nitrogen had higher concentrations of methane, ethane, propane, carbon dioxide, and hydrogen than in samples with air. On the other hand, samples in air found higher concentrations of carbon monoxide, ethylene, and propylene. When coal was in contact with nitrogen, the gaseous components present in the gas sample under investigation came mainly from natural desorption, whereas when coal was in contact with air, the oxidation of coal also occurred. In the process of natural desorption, mainly methane is emitted into the atmosphere of the mine along with the accompanying saturated hydrocarbons: ethane, propane and carbon dioxide. Diverse desorption of saturated hydrocarbons from the structure of coals results from the heterogeneity of hard coal and different content of hydrocarbons in the coal structure. No clear relationship was found between the content of desorbed hydrocarbons in the gas sample and the physicochemical properties of the tested coals.
Carbon monoxide, ethylene and propylene are released as a result of contact of coal with oxygen from the air. The highest values of concentrations of carbon monoxide, ethylene and propylene were determined in gas samples desorbed from coals with the lowest, among the tested ones, degree of metamorphism and easily accessible internal pore structure.
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