At present the biomass is the only energy resource that could be in near future utilized for the objectives the Czech Republic previews for year 2010. It means to reach a 6% share of energy renewable sources from total energy consumption and at the same time 8% of electric energy production from those sources. From the purposefully grown biomass can be used the energy herbs and wood species. An advantage of the energy herbs compared with the wood species is lower costs for growing and consequent processing. The energy herbs biomass can be directly used for combustion in form of chopped material or pressed into the bales or it can be further processed into briquettes or pellets. Through the briquettes production there is achieved the standard form of that fuel for its further utilization in the combustion device. This processing enables to achieve a significant volume contraction and thus also matter and utilized energy density increasing (PLÍŠTIL 2003;PLÍŠTIL, NOVÁKOVÁ 2003;.As the mechanical properties of the standardized fuels in form of briquettes concerns, the most important are the volume weight and mechanical strength. These parameters depend on the used material, its structure, water content and compaction pressure. The basic standard for this process is the Austrian ÖNORM M 7135 and German DIN 51731. These documents are valid for wood and bark extrusions. For the material volume weight is determined the value ρ > 1,000 kg/m 3 . If the briquettes are of circular section type then their diameter is from 20 to 120 mm and length till 400 mm. The legal regulation in the Czech Republic for the wood briquettes requirements is the Decree 357/2000 specifying demands for fuel quality from the point of view of atmosphere protection. Nevertheless this decree does not present requirements for the fuel mechanical properties. The briquette mechanical ABSTRACT:The measuring has proved that the energy herbs can be pressed into the form of compact briquettes. It regards 9 varieties of the energy crops, i.e. coriander, crambe, saphlor, sorrel, sorghum, reed canary grass, knotweed, barley straw and rapeseed straw. These energy crops are disintegrated by the grinding mill ŠV 15 (manufacturer Stoza, Ltd.) before the pressing. The fraction size is given by the mesh size of circular cross section of diameter 15 mm. All the crops have constant moisture content during the measuring and uniform diameter 65 mm of the resulting briquettes. The biomass moisture ranges from 9 to 11%. The pressing is conducted by the briquette press HLS 50 (manufacturer Briklis, Ltd.). The measuring results have shown the highest volume weight in following energy herbs: coriander, saphlor, rapeseed straw, sorghum, sorrel and knotweed. The lowest volume weight was found in these crops: reed canary grass, crambe and barley straw. The measuring proved that the highest force for the briquette disintegration is necessary for knotweed, saphlor, sorrel, sorghum and coriander. The lowest force for the briquette disintegration needs the reed canary grass, barl...

The main part of the pressed biofuels are lignocellulose materials of plant origin. Properties of the input material are given by requirements of a proper device, usually a pressing mechanism. The pressing mechanism for briquettes and pellets production put high demands on the input particles size. Maximum admissible size of particles is in range of decades of mm 3 for briquette pressing mechanisms and in mm 3 for pellet pressing mechanisms.This size can be reached in practice by mechanical adaptations. The desintegration is a technology, where basic alternations of machinery and materials using, technology and working organization (ŠÁLYOVÁ 2000) are made. The dimensional adaptations of wood are usually necessary. Advantage of these operations is mainly in simple manipulation and easier determination and description of such adapted raw material. Nevertheless, mechanical adaptation needs higher amount of energy (SOUČEK 2000).The lignocellulose materials are highly heterogenous with physical properties changing in dependence upon influence of ambient effects. These effects are mainly temperature, humidity, air flow which are factors having impact on dry matter content in material and velocity of its drying or moisturizing (KAFKA 1989).Each lignocellulose material consists of dry matter s and water (total moisture) W t r . s + W t r = 100% (1) Water content in the lignocellulose materials useable as fuel is lower than 50% (CENEK 2001).To assess other important properties, we present also instantaneous dry matter content in following points of the article for presentation of measured of laboratory found-out values.The energy consumption of biomass desintegration was investigated in Sweden in 1989. The tested machines was cone-screw chipper Sasmo HP-30 (Finland), involuted single-disc chunker, research prototype (USDA, Forest Service, USA) and double-disc chunker, research prototype (Sweden). Desintegrated matter was Aspen and Red Maple. Moisture content of desintegrated matter was about 30%. The average energy consumption of desintegration was 0.61 kWh/m 3 (Aspen, average output particle length 6.4 mm); 0.92 kWh/m 3 (Aspen, average output particle length 9.5 mm); 0.92 kWh/m 3 (Red Maple, average output particle length 6.4 mm); 1.19 kWh/m 3 (Red Maple, average output particle length 9.5 mm -DANIELSSON 1990).Economy and energy balance of desintegration was investigated in the framework of the research activity of South Bohemia Uversity in České Budějovice (CELJAK 1999). The investigated process was the poplar chips production. Cost of chipping (poplar chips, moisture 50%) was 152.00 CZK per ton (energy consumption 71.80 kWh/t). Total cost of chips production (plant production, harvesting, chipping, hauling and storaging) was 1,280.60 CZK per ton. The combustion heat of investigated chips was 18.3 MJ/kg and calorific value of final product (poplar chips, moisture 17%) was 14.7 MJ/kg.The scope of measurements was to determine the course of energy consumption for crushing of chosenThe research results presented in this a...

Short rotation coppice (SRC) plantations of fast growing trees in Czech Republic may be grown on approximately 120,000 ha in future, as indicated in the Czech Action Plan for Biomass. Until now, 2,800 ha of SRC were established using predominantly poplar non-native hybrid clone Max-4. The aim of this experiment and article is evaluation of promising domestic clones of willow species and their natural hybrids, to discover their yield parameters and fuel characteristics in field conditions. The experiment was established in Průhonice in 2005 and it was harvested two times in triennial rotation (2008, 2011). For the test of fuel properties biomass was used from three willow species: common osier (Salix viminalis) S-337, Smith’s willow (S.× smithiana) S-218 and white willow (S. alba). Mean hectare yield of biomass in oven dry tonnes (o.d.t) of all the observed clones after first harvest was 3.9 o.d.t/ha/year, and after second harvest 10.4 o.d.t/ha/year. Observed willow clones had comparable or better yields as well as selected fuel properties (content of ash, melting point) in comparison with poplar clones used in the experiment.

Ivanova T., Havrland B., Hutla P., Muntean A., 2012. Drying of cherry tree chips in the experimental biomass dryer with solar collector. Res. Agr. Eng., 58: 16-23.Drying significantly influences the process of a biomass conversion into the renewable energy source as well as quality of solid biofuels (briquettes, pellets). The research is focused on monitoring and evaluation of the drying process in the case of cherry tree chips drying in experimental biomass dryer with solar collector. The dryer has been conceived as a result of the project which was realized at the State Agrarian University of Moldova. Technological and construction specifics of the biomass dryer are described in the paper. The moisture content of the cherry tree chips was observed in dependence of the drying time and at different locations of the drying chamber. The drying process in the biomass layer was found as non-uniform. Further parameters such as relative air humidity and the air temperature were measured and analysed, as well. It was concluded that the experimental biomass dryer with solar collector can work well in the conditions of the Central Moldova during the sunny period of the year.

Cotton dust is a waste produced in the cotton spinning mill. This matter in mixture with grain straw and additive of brown coal was used for heat briquettes production. Mechanical properties, energy and emission parameters were investigated during their incineration. The blended briquettes and those with coal additive have better use properties as compared with briquettes produced from pure cotton dust.

Rice straw is potentially an appropriate feedstock material for biofuel production, since a huge amount of this postharvest residue is generated every year. The transformation of such agricultural biomass into densified products with a higher energy value and their subsequent combustion is associated with several questions. One of them is that rice straw exhibits a large formation of ash during combustion; thus, it is essential to know the nature of its ash melting behavior. Generally, during the combustion of straw biomass, ash sintering occurs in relatively low temperatures, resulting in the damaging of heating equipment. This negative aspect can be overcome by the addition of calcium-based additives. This paper aimed to study the ash melting behavior at a laboratory scale and to determine the ash melting points of rice straw mixed with calcium carbonate (CaCO3) and calcium hydroxide (Ca(OH)2) in different proportional ratios. The standardly produced ash samples from the rice straw obtained from Cambodia were constantly heated up in a muffle furnace, and characteristic temperatures of ash melting, i.e., shrinkage, deformation, hemisphere, and flow temperature, were recorded. The results showed that increasing the additive ratio did not bring linear growth of the melting temperatures. The addition of 1% CaCO3 showed an optimal positive impact of higher ash melting temperatures, and thus a better ability to abate the sintering of the rice straw ash.

Abstract:In accordance with the technical standard ČSN EN 13229 "Inset appliances for heating including open fires fired by solid fuels -Requirements and test methods" was performed the basic assessment of thermal efficiency and emission parameters of prototype of combustion accumulation stove SK-2 with upper after-burning and nominal heat output of 8 kW. Verified gradually were the bio-briquettes of diameter 65 mm from mixture of wheat straw and 20% m/m of brown coal, wheat straw and 5% m/m of brown coal, wheat straw, mixture of wheat straw and 10% m/m of water and molasses solution, Ecobiopal created with the fermented blend of 33% m/m of digested clean water plant sludge and 67% m/m of wood chopped material, blend of wheat straw and 15% m/m of sugar beet pulp, mixture of timothy hay and 25% m/m of brown coal, timothy grass hay, meadow hay, mixture of meadow hay and 25% m/m of brown coal. The lowest CO emissions, when the limit value of 3000 mg/m 3 N at 13% of O 2 has not been exceeded, determined for more strict 1 st class and the highest efficiency at nominal heat performance, i.e. higher or equal to 70% (Class I) have been reached by the briquettes produced from mixture of wheat straw and 15% m/m of sugar beet pulp, timothy hay and mixture of meadow hay with addition of 25% m/m of brown coal. Further were measured NO x and HCl emissions. NO x values were significantly lower than limit values determined for similar combustion of solid biofuel. Higher differences of HCl emissions correlate with various Cl content in fuels. Only the wheat straw briquettes with share of 25% m/m of brown coal have exceeded the limit value by 16%. Other fuels have shown considerably lower values. The results have proved better heat-technical and emission parameters of blended briquettes and are significant also for solid biofuels and solid recovered fuels standardization as well as for increasing efficiency method detection and ecological parameters optimization including HCl emissions.

Southeast Asia currently faces a huge increase in energy consumption and serious environmental issues. A widely underutilized and still unexplored potential of these countries lies in residual biomass. In the present research, the production quantities and energy yields of the most abundant agricultural byproducts in Vietnam, i.e., rice straw, rice husks, sugarcane bagasse and sugarcane trash, were calculated. Total crop yield, residues ratio and net calorific values of the wet basis biomass served as input parameters for the calculations. Moreover, the results were found for individual regions and provinces of the country. The findings show that the production of paddy rice straw is an enormous 97 million tons per year with an energy potential of over 380 TWh, as well as another 9 million tons yearly and 35 TWh in the case of rice husks. More than half of rice biomass production is concentrated in the Mekong River Delta region. Harvesting and processing of sugarcane annually generates about 5 million tons of bagasse and over 3.5 million tons of sugarcane trash with the total energy potential of about 27 TWh, which is primarily available in the central regions of Vietnam. The detailed laboratory determination of fuel-energy properties of studied materials, such as gross and net calorific value, volatile matter, ash and moisture content and contents of chemical elements was also carried out. Based on the research results and literature analysis, the possibilities of biofuel production and energy utilization of the above-mentioned residues are discussed.