Influence of raw material properties on the quality of solid biofuel and energy consumption in briquetting process

ArticleThe present paper is related to a pressing process research of raw materials with different density in order to investigate impact of biomass density on a formation of monolithic structure and the briquette’s strength. Another focus of the study is an influence of raw materials particles’ size on agglomeration process and quality of final product. Different biomass materials like two varieties of miscanthus, industrial hemp and apple wood were selected for experimental purposes of this research. Mechanical durability which represents one the main indicator of briquettes’ mechanical quality (strength) was determined. The research was conducted using hydraulic piston briquetting press. For assessment of briquetting efficiency during the whole process energy consumption was measured. One of the most important factors that can affect briquetting process is the temperature of pressing chamber which was registered as well. The main goal of the research was practical study of possibilities for increasing production efficiency and quality of briquettes on hydraulic piston briquetting press with respect to optimization of particles’ size of raw materials and use of raw materials the most appropriate density

Using of high-speed mills for biomass disintegration

ArticleThe need for mechanical disintegration of biomass is very current topic with regard to the requirements of an agrarian sector, beside the importance of a material’s moisture content reduction to be used in further applications. The drawbacks of commonly applied devices are the limited use of moist biomass and high energy consumption for disintegration. In collaboration with LAVARIS company, there were tested two high-speed mills LAV 400/1R with single rotor (used for a first milling) and LAV 300/2R with double rotors (used for a second milling), which were primarily designed for crushing of concrete, rubber and construction waste. The goal of the new technical solution was a disintegration of biomass on example of pine sawdust and miscanthus together with examination of simultaneous drying in order to achieve a desired fraction (particle size) and moisture content of biomass material. Experimental tests on highspeed mills have shown the following results: in case of pine sawdust about 98% of output particle size after passing through the first and second milling was smaller than 1.5 mm, and smaller than 1 mm for miscanthus (sieve analysis method was used for determination), i.e. significant reduction was achieved comparing to initial particle size. Moisture content of the materials after disintegration (first and second) decreased from 37.08% to 8.55% for pine sawdust and from 24.43% to 7.19% for miscanthus. Based on the results, it can be concluded that the mechanical disintegration of biomass by high-speed mills has a great potential to become an effective part of raw materials’ pre-treatment technology, not only in agriculture, but also in production of different types of biofuels

Ozone treatment of stored potato tubers

During storage, potato tubers are susceptible to different pathogen, which can attack the skin and flesh of the tubers. The most serious damage can be caused by rot inducing bacteria and fungi. A possible way to prevent microbial damage may be the use of ozone in the air ventilated through the stored tubers. However, the tubers can undergo qualitative changes, e.g. dehydration and loss of starch content. This article presents the results of a five-month experiment in which ozone concentration of 5 mg m-3 was periodically introduced in some of the stored potato tubers of the cultivar ‘Dali’. All potato tubers were stored in closed storage boxes with a metal frame and wood panels in the floor and walls (ground area 1.6×1.2 m, height 0.95 m) which were continuously aerated using the ambient air in a potato warehouse. There was 900 kg of tubers stored in the box. At the end of the experiment, the ozonated variant was compared with the control (not treated). The ozone-treated tubers had 2.95 times lower incidence of infection by rot and the number of microorganisms on healthy tubers was lower than the control. The ozone-treated tubers were less frequently dehydrated. The water loss was higher in control by 0.86 %. There was no significant difference in silver scurf manifestation or in the starch content between the two variants