Z. Bis

The Investigation of Mercury Contents in Polish Coal Samples

Abstract This paper presents the results of the investigation associated with the determination of mercury content in Polish hard coal and lignite samples. Those coals are major fuels used for electricity generation in Poland. The results indicated that the average content of mercury in the coal samples was roughly about 100 ng/g. Apart from the determination of the mercury contents a detailed ultimate and proximate analysis of the coal samples was also carried out. The relationships between the mercury content and ash, as well as fixed carbon, volatile matter, sulfur, and high heating value of the coal samples were also established. Furthermore, the effect of coal enrichment was also investigated, and it was found that the enrichment process enabled the removal of up to 75% of the coal mercury from the samples. W niniejszej pracy przedstawiono wyniki badań zawartości rtęci w polskich węglach kamiennych i brunatnych. Wyżej wymienione paliwa są głównymi paliwami używanymi do produkcji energii elektrycznej w Polsce. Wyniki wykazały, że średnia zawartość rtęci w badanych próbkach węgli wynosi około 100 ng/g. Oprócz badań zawartości rtęci przeprowadzono także analizę techniczną i elementarną próbek węgli. Zestawiono zależności pomiędzy zawartością rtęci a zawartością popiołu, fixed carbonu, części lotnych, siarki oraz ciepłem spalania. Przedstawiono także wyniki badań wpływu wzbogacania węgla na zawartość rtęci. Stwierdzono, że w wyniku procesu wzbogacania możliwe było usunięcie prawie 75% rtęci zawartej w wyjściowym paliwie.

BIOCHAR TO IMPROVE THE QUALITY AND PRODUCTIVITY OF SOILS

The paper presents the results of research focused on the investigations of the possibilities to use biochar to improve the quality and productivity of soils. Biochar is a material similar to the commonly known charcoal obtained from the thermolysis process (a process similar to dry distillation of wood). The structure and technical properties of biochar depend on the type of biomass which is produced and the thermal decomposition process conditions: process time, temperature and atmosphere. It was found that a positive effect of biochar on the soil properties is manifested through the improvement of soil fertility, better water retention, improvement of the cation exchange, and the regulation of the pH. The biochar used in the present study was obtained by autothermal thermolysis of biomass at 300 °C. Three types of biochars of different origin were used. The biochar samples were subjected to ultimate and proximate analysis, as well as structural and porosimetric investigations. The experimental research were also conducted on the experimental test field and gave a positive effect of the presence of biochar on soil quality and plant yield. Biochar introduced into soil allows for longterm storage of carbon. The introduction of biochar to soil has a positive effect on plant growth, higher dose resulted in an increase in biochar and plant mass.

Evaluation of structure and particle velocity distribution in circulating fluidised beds

Abstract This paper deals with the complex problem of how to evaluate the parameters of the structure in circulating fluidised beds. Some aspects of this problem have arisen from the introduction of circulating fluidised bed boilers. The distributions of particle concentration and particle velocity reflect the random behaviour of particles in a combustion chamber. The level of particle velocity—while the boiler is in operation—has an impact on the combustion process, kinetics and heat transfer, and also on the erosion processes on the heat surfaces. A linear combination of double Maxwellian distributions has been assumed to describe a component of the distribution of particle velocity. This assumption allows us to calculate statistical moments in a different way, e.g. the mean particle velocity, granular temperature, etc. Additionally, the local structure of a circulating fluidised bed has been presented.

EMISSION OF MERCURY FROM POLISH LARGE-SCALE UTILITY BOILERS

The article presents the results of investigations focused on the determination of mercury content in gas and solid samples. The emission of Hg was the result of coal combustion. The investigations were carried out in the selected power generation facilities operated with pulverized coal and circulating fluidized bed boilers. Analysis was carried out for the flue gases, as well as fuel and sorbent samples and the by-products of the combustion process (fly ash, slag, bottom ash, and the products of wet desulfurization technology). The determination of mercury content in solid samples was carried out using Lumex RA-915+ spectrometer with RP-91C attachment. The measurements of the mercury concentration in the flue gases were performed according to the cold vapor technique. The analysis of the results indicated that the main source of mercury is coal, but significant concentration was also determined for the biomass co-combusted in one of the facilities. Considerable amounts were also determined in fly ash and wet FGD (flue gas desulfurization) samples.

Properties of Graphite Sinters for Bipolar Plates in Fuel Cells

Fuel cell is an electrochemical device which transforms chemical energy stored in fuel directly into electrical energy. The only by-products of this conversion are water and heat. The factors which affect the intensity of electrochemical processes include properties of the materials used for fuel cell components and its working environment. Due to insignificant emissions of pollutants during energy production combined with high efficiency of these generators, and silent operation, fuel cells are an alternative to technologies of energy production from fossil fuels.