1/2019
Gases produced during remediation of soil contami-nated by petrochemical sludge
The article deals with the development of gaseous components when heating contaminated soil with petrochemical sewage sludge from the so-called lagoons in which these wastes were deposited in the past. Laboratory experiments and analyzes show that this material decomposes at the temperatures attainable in the inlet to the pressure generators in which they are co-gasified with brown coal by mixture of steam and oxygen. Major development of toxic flammable and explosive gases containing mainly carbon monoxide, methane, hydrogen, saturated and unsaturated hydrocarbons C2-C4, hydrogen sulfide, organic sulfur components at the temparatures applied in the dispensing inlets of the pressure gasifier (2,7 MPa).
Product Gas Measurement in Fluidized Bed steam Gasification of Rice Husks
As the common agricultural feedstock, rice husks can be a sustainable biofuel option with significant calorific value (16-17 MJ/kg) and ash deforming temperature recorded above 1450 °C. The research determines product gas on the 100 kW dual fluidized bed steam gasifier performance of rice husks pellets at temperatures between 760 and 810 °C. Pure steam was used as a gasification agent at a steam/fuel ratio of 0.87 kg.kg-1, dry basis. Calcite with mainly CaCO3 in compositions was used as bed material for the reactor. Significant H2 content was de-termined with high quantity of CO2 and CH4 in product gas, while CO level was relatively low. Due to the considerable sulfur and nitrogen contents of this fuel, values of the impurities NH3 and H2S in the producer gas was detected. It is also shown that the majority of sulfur was released in the gasification zone and, therefore, no further cleaning of the flue gas was necessary. Ethylene, ethane and propane were also formed but only in amounts below 2 % vol. dry gas. Specific product gas yield reached 1.2 Nm3.kg-1, dry basis.
Biomethane liquefaction – technology and future potential
Liquid biomethane (LBM) may represent, under certain conditions, a competitive renewable energy resource and a promising biofuel for transport. LBM, with its carbon neutral footprint, is produced through the upgrading and liquefaction of biogas obtained by anaerobic digestion of organic material. Use of LBM is advantageous in reducing greenhouse gas emissions and ensuring a more sustainable environment. Given its importance, the LBM is constantly increasing, hence more biogas liquefaction plants will be installed in the future. This paper describes two small-scale biogas liquefaction plants: single mixed refrigerant process and nitrogen expander process. In addition, it shows the present and future production potential of biomethane and liquefied biomethane in Europe.
Health risk from exposure to hydrogen sulphide generated by reclamation activities in the Mydlovary
Reclamation activities at the area of former uranium ore processing plant situated in the South Bohemian Region lead to emissions of hydrogen sulphide. Emissions were generated in the reclaimed impoundment and started being perceived as strong unpleasant smell by citizens of the nearby Mydlovary village during 2017. In order to identify the source of smell and to evaluate risks to human health from the exposure, the atmogeochemical survey together with measurements of the outdoor air were conducted directly at the reclaimed area, at its boundary and inside the Mydlovary village. The source of hydrogen sulphide emissions was identified in western part of currently reclaimed lagoon K IV/R. Based on the results measured calculations of noncarcinogenic human health risk were performed showing relatively low values of hazard quotient for hydrogen sulphide for the village territory. Further studies concerning the source of the hydrogen sulphide inside the lagoon were drawn.
Oxidation stability measurements of FAME, diesels and their mixtures with Rancimat and PetroOxy meth
Rancimat (according to EN 15751) and PetroOxy (according to ASTM D7545) are the most used methods for determination of oxidation stability of diesel, biodiesel and their mixtures nowadays. The correlation between these two methods is often discussed with the summary that the correlation depends on the sample composition. The effect of test temperature on oxidation stability studied with both methods is discussed at standard diesel fuels (according to EN 590), diesel fuels with 10 and 30 % (V/V) FAME and pure FAME and paraffinic diesel fuels (according to EN 15940) in the temperature range between 80 and 140 °C. Different processes of evaluated quantities were observed for both methods and different samples. The parameters (activation energy and frequency factor) were calculated from Arrhenius equation describing the dependence of reaction rate on the temperature. These parameters depend on the method and on the diesel composition. The difference between samples and methods is in order of magnitude for frequency factor and up to 30 kJ.mol-1 for activation energy. A mathematical model is suggested and discussed for the reciprocal conversion between Rancimat and PetroOxy methods. The suggested model converts the results of both methods accurately, but the conversion is possible only for one fuel type with certain oxidation stability.