Paliva (Fuels) is a scientific journal issued quarterly by the Faculty of Environmental Technology, ICT Prague. Fuels publishes papers on a broad range of topics covering exploitation, processing, upgrading, and utilization of various types of fuels, and power engineering.

1/2024

4/2012

The effect of temperature on the structure of paraffinic particles in crude oil

Paraffinic particles present in crude oil are the main constituent of pipeline wall deposits and tank bottom sludge formed at ambient and low temperatures. These phenomena negatively affect transport and storage of crude oil. For proper prediction of crude oil behaviour, its properties must be determined in laboratory. Correct sample handling is very important to avoid changes in the structure of paraffinic solid phase to ensure reproducibility and accuracy of results. The structure of paraffinic particles in crude oil samples subjected to temperature changes was studied using polarized light microscopy. The temperature changes simulated sample handling and storage between sampling and laboratory measurements. The results show that cooling and re-heating of the sample to its original temperature leads to the recovery of the structure of paraffinic particles, while the heating and subsequent cooling leads to their irreversible changes.

Silica – Traditional Refractory for Coke Oven Batteries

The paper introduces a new type of silica bricks, acquaints with technology of production and with achieved properties of silica material. Material density is one of the determining factors affecting resistance of silica material. Dense material is more resistant against diffusion of aggressive atmosphere elements in furnaces and has increased thermal conductivity and abrasion resistance which are characteristics of the material required especially by coke industry.

The influence of temperature and flowrate on the reading of the gas meters without temperature compe

In the Czech Republic large proportion of the gas consumption is metered by gas meters without the temperature compensation. Standard billing procedure estimate of metered gas temperature is based solely on the atmospheric temperature. This article evaluates the additional effects of gas temperature at meter inlet and of the gas flowrate. The experiments were run with the G4 size gas meter at the ambient temperatures in range of -10 to +25 °C and flowrates covering the operating range of gas meter. The measured temperatures were expressed as dimensionless temperature and its relationship with the gas flowrate was found by regression as straight line. The evaluation of the gas temperature taking in account the flowrate is suggested. The comparison of the new method with the current standard billing procedure has shown temperature difference ranging from -0,4 to +1,1 °C.

Research and Development of CO2 Capture and Storage Technologies in fossil Fuel Power Plants

This paper deals with calculation procedure that has been performed in order to evaluate suitability of a post-combustion CCS technology application in a recent power plant in the Czech Republic. The ammonia CO₂ absorption method and its advantages and disadvantages are described. The technology scheme with key components of the ammonia CCS has been analyzed and more detailed data are provided for each basic component, especially for energy consumption for cooling and compression. The impact of the incorporation of the CCS technology into a 250 MWe power plant fired by pulverized lignite coal was evaluated. The calculations are based on available operation input data of the power plant. Main parameters (e.g. net power output, efficiency or consumptions) are compared for the recent situation and after CCS installation. The main impacts of the ammonia CCS technology application are the decrease of electric efficiency by 11 %, the decrease of net electricity production by 62 MWe, and an increase of wastewater amount and need of consumables. The decrease of efficiency and net electricity production is particularly caused by high energy demands of compression of CO₂ and cooling of CO₂ – ammonia absorber. Also important is the increase of cooling water consumption for the absorbing stage.

Impact of Conical Pressing Chamber on the Final Quality of Solid Biofuels in Briquetting Machines

In this paper we analyze the impact of conicalness (an important structural parameter of pressing chambers) on the quality of briquettes made from solid biofuels. Besides the known impacts of the technological parameters of the pressing process on the quality of the briquettes, it is also important to pay attention to the structural parameters of the pressing chamber. A theoretical analysis of pressing chamber conicalness is presented. An experiment aimed at detecting the impact of conicalness on the quality of the briquettes was performed. The results show that increasing the conicalness of the pressing chamber improves the quality of the final briquettes. The conicalness of the pressing chamber influences significantly the construction of briquetting machine.

Co-gasification of brown coal and woody biomass in the fluidized bed

The work is focused on the gasification of brown coal in a fluidized bed in the integrated gasification combined cycle. The usual gasification medium is a mixture of oxygen and water vapor. The specific objective of the study was to examine the influence of water vapor and waste carbon dioxide in the gasification agent and the effect of the addition of waste wood biomass to the brown coal on the quality (composition, purity, yield, and calorific value) of producer gas.