R. Kobyłecki

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.

Instrumentation and Measurements

The calibration of capacitors at the National Physical Laboratory in Britain is discussed in a paper by Rayner and Ford.1 Their primary standard of reactance is a standard inductor which is used to calibrate capacitors with a Carey-Foster Bridge. Then a precision Schering Bridge is used for comparing capacitors with an error of ± 1 in 10,000 and ± .00002 in power factor. L. H. ford2 has measured the effect of humidity on the capacitance end power factor of precision air capacitors and notes that changes in capacitance of 3 in 10,000 are noted at relative humidity of 65%. This is more than the amount predicted by the change in the dielectric constant of air by the water vapor. The power factor also increases at relative humidity above 40% reaching 0.00008 at 65% R.H. The measurements were made so as to eliminate the effect of insulators. New standards of very small capacitance from 0.001 to 100 F were developed by Moon and Sparks3 in which they placed the measuring electrode at the bottom of a well with the guard electrode surrounding it and much closer to the opposite electrode.

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.

Effect of Fuel Type on Formation of Agglomerates in a Large Scale Pressurized Fluidized Bed Combustor

The paper investigates agglomerate formation in the world biggest pressurized fluidized bed combustor at Karita Power Station, Japan. It was found that significant amount of agglomerates was formed at an increased boiler load bringing about a significant decrease of bed density. The agglomerates had a glassy-like molten surface and consisted of a mixture of ash from char fines and limestone particles. The main components found in the agglomerate cross-section were Ca, Al and Si oxides, all quite uniformly distributed. Agglomerate formation occurred particularly when the unit was fired with a porous Blair Athol coal that was found to produce a porous char. Firing the boiler with other coal (Nanton) that produced less porous char prevented the formation of agglomerates and enabled to maintain stable operation of the combustor. A model was developed to calculate the horizontal distribution of char surface temperature in the PFBC based on a quasi-steady heat balance for a burning char by taking into consideration the distribution of volatiles above fuel feeding nozzles, as well as char porosity. In order to take into consideration the effect of porosity on combustion of a porous char a completely new expression to estimate the reaction rate was proposed. The calculation results indicated that the agglomerates were mainly formed due to the combustion of highly porous Blair Athol chars in the poorly fluidized areas in the bed, where air-to-fuel ratio became larger. The combustion rate of less porous Nanton char was much slower then that of the Blair Athol. Accordingly, combustion temperature of its char was lower bringing about no formation of agglomerates.Copyright

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.