Fibrous hemp (Felina 32, USO 31, Finola) and fibrous nettle processing and usage of pressed biofuel for energy purposes

There were investigated three varieties of fibrous hemp – Felina 32, USO 31 and Finola and one sort of fibrous nettle. Before granulation, plants were chopped and milled, and were determined chaff and mill fractional composition. Produced pellet humidity ranged from 9.98% to 8.87%, and pellet density reached 1171.7 kg m−3 DM of USO 31 variety. The ash contents of the fibrous hemp and fibrous nettle pellet reached 3.58% and 6.6%, and the net calorific values were 17.37 MJ kg−1 and 16.93 MJ kg−1 DM, respectively. The composition of determined fibrous plant chemical elements ranged within these limits: carbon – 45–48%; hydrogen – 1.0–1.5%, nitrogen – 5–6% and oxygen – 41–43%. Determined ash melting temperatures ranged from IT – 733–673 °C to FT – 863–859 °C. Pellets disintegration force varied from 992 N for Felina 32 till 1338 N for fibrous nettle. Harmful emissions were also estimated, it ranged – CO2 – 3.1–5.0%, CO – 411.7–1410.8 ppm, NOx – 88.0–117.3 ppm and unburnt hydrocarbons CxHy – 26.0–127.9 ppm have been determined when burning of granules. Determined emissions were within the permissible limits. Coefficient of energy efficiency of granulated biofuel, when biomass moisture content was decreased by 20%, was 2.83.