Plasters are traditional surface finish materials in timber buildings. Today, the lack of fire performance data and design guidelines place such ecological materials at a disadvantage since plaster is not considered as a fire protection material for timber. This study aims to provide an up-to-date overview of performed fire tests accompanied by investigations on thermal properties of selected ready-mix clay and lime plasters. Design parameters of plasters for the fire design of timber structures are proposed following the safety philosophy of EN 1995-1-2. Numerical heat transfer simulations provide sufficient agreement with furnace test results for undercoat clay plaster. The mechanical fastening system of a plaster (e.g. reed mat) on timber demonstrates paramount importance when determining the charring rate of timber and the fall-off time of plaster. The structural integrity and fire performance of plasters should be further investigated due to their various recipes and numerous fastening systems on timber. Further research in full-scale is needed to confirm the recommended design parameters.
Oxy-fuel combustion is considered as one of the promising carbon capture and storage (CCS) technologies for coal-fired boilers.In oxy-fuel combustion, the combustion gases are oxygen and the recirculating flue gas, and the main components of the combustion gas are O 2 , CO 2 and H 2 O [1].The paper presents the results of the calculation of the flue gas amount during combustion of oil shale using oxy-fuel technology in a circulated fluidized bed (CFB) mode.The calculations were performed for different oil shale heating values and different recycled flue gas (RFG) ratios.Oxy-fuel combustion with flue gas recycling was found to enable the decrease of the extent of carbonate minerals decomposition (ECD), thereby increasing the amount of heat released per 1 kg of fuel.To minimize ECD, the recycled flue gas ratio should be maintained at a level higher than 0.7.This condition allows an increase of the partial pressure of CO 2 over the equilibrium state line of calcite decomposition reaction at the bed temperature.The decrease of ECD was observed up to CO2-min 0.28.k = The decrease of CO2 k leads to an additional increase in the amount of heat released during oil shale combustion per 1 kg and, depending on the mean lower heating value (LHV), the heat can be increased up to 0.34 MJ/kg.A comparison with the bituminous and anthracite coals revealed that the specific emission of CO 2 per input fuel energy for oil shale is expected to be even smaller compared with those of the considered coals.
The main difference of biomethane in comparison to natural gas is its higher concentration of compounds conducive to corrosion and a higher risk of corrosion to steel piping. During the last decade, high-volume injection of biomethane into a transmission network through a steel piping for natural gas has become more actual in the EU, meaning the focus on related problems is fairly recent. In general, the approach to the biomethane injection has been limited to an assumption that when mixed with natural gas, the amount of corrosion inducing compounds stays below the risk level. The objective of the current article is to systematise prior scientific research regarding the corrosive effects of H2S and NH3 on natural gas piping systems manufactured of carbon steel. A simplified methodology will be developed for the verification of information and based on that, the corrosion-sensitivity to H2S and NH3 found in biomethane of the main steel brand used in Estonian gas piping will be checked.
Oil shale (OS) is a low-calorific-value fossil fuel. Today, Estonia’s OS usage is the largest in the world. Approximately 76 % of the electricity is produced from Ca-rich OS. Yearly, approximately 12 million tons of OS is used for power generation utilizing pulverized combustion (PC) and circulating fluidized bed combustion (CFBC) technologies that produce nearly 6 million tons of Ca-rich ash. Estonian kukersite OS consists about one third of carbonate minerals, mainly calcite. Therefore, in addition to the combustion of organic carbon, the carbonaceous minerals decompose and release additional CO2. The extent of decomposition of carbonaceous minerals depends on combustion technology. Using oxy-fuel CFBC technology alters ash properties, including decomposition of carbonate minerals. By means of aqueous carbonation of Ca-rich ash, CO2 can be stored safely and leakage-free for very long time. In order to understand the changing CO2 sequestration potential, oil shale ashes were produced at a 60 kWth CFBC facility in oxy-fuel mode. The ash was treated with water and CO2 in order to mimic the ash treatment technology currently in use in the industry. The ash bound 81 kgCO2/tash it means that 6 % of the CO2 emitted would be bound at the ash fields. Due to decreased decomposition of carbonates, when using oxy-fuel CFBC, the CO2 specific emission of combustion would decrease by 5 % compared to regular CFBC and 19 % compared to PF. Decreased CO2 production would result in reduced CO2 transportation and further utilization or storage cost.
