The utilitarian objective of the thesis was to develop a construction and a prototype of a ring granulator for production of 25mm diameter pellets of grain plants and rape. The scientific objective of the thesis was to determine the impact of the straw variety and moisture on efficiency and energy consumption of the pellets production process at three accepted for the research rotational speeds of the head of a granulator. The research proved that both the variety of straw used for production of pellets as well as its moisture and the rotational speed of the head of the granulator has a significant impact on efficiency and the specific energy consumption and the pellets quality determined as bulk density and calorific value. At speeds of the head of the granulator amounting to 25, 38 and 45rpm, the highest efficiencies amounting respectively: 0.58, 0.68 and 0.67t·h-1 were obtained at pelleting rape straw and they were significantly higher than efficiencies obtained at pelleting wheat, rye and rape straw. At the investigated varieties of straw and rotational speeds of the granulator head, the highest efficiency was obtained at pelleting straw of 10% moisture while the lowest at pelleting straw of 26% moisture. The research proved that both the straw variety and moisture had a crucial impact on the specific energy consumption at all the researched rotational speeds of the granulator head. At the rotational speeds of the granulartor head of 25, 38 and 45rpm it was reported that the lowest specific energy consumption amountig to respectively: 16.0, 19.3 and 23.7kWh·t-1 occurred at pelleting rape straw while the lowest amounting to respectively: 21.6, 24.9 and 29.3kWh·t-1 at pelleting maize straw. Significantly the lowest specific energy consumption at all the researched rotational speeds of the granulator head and straw varieties were reported at its moisture within 16.2-20.9% and above this value of straw moisture the specific energy consumption significantly increased. The highest average value of bulk density of the pellets (663.7kg∙m-3) produced of straw varieties, used in the research, were obtained at the rotational speed of the granualtor head amounting to 38rpm. It was found that mean values of bulk density of pellets produced from the straw varieties used in the research at rotational speeds of the granualtor head, accepted for the research, in majority of cases differed significantly between each other. The highest bulk density characterised pellets produced of maize straw (655.5kg∙m-3), whereas a significantly lower bulk density characterised pellets of wheat straw (622.2kg∙m-3). Whereas, bulk densities of pellets produced of rape straw (612.8kg∙m-3) and rye straw (609.4kg∙m-3) did not differ significantly at the level of significance of α=0.05. It was found that the calorific value of pellets produced of rye and rape straw did not differ significantly and was significantly higher than the calorific value of pellets produced of maize and wheat straw. Moreover, it was found that pellets produced of straw of the highest researched moisture amounting to 26% were characterised with the lowest calorific value. The most advantageous results concerning the specific energy consumption, efficiency and pellets quality were obtained at the speed of the granualtor head amounting to 38rpm. Indeed, at the head speed of 45rpm efficiency of the granulator was slightly higher, however, also the specific energy consumption was higher and the bulk density of the pellets was lower at the head speed amounting to 38 pm.
Uniwersytetu Przyrodniczego w Lublinie