Grovkrossning av stubbar
en produktivitetsstudie
The Swedish parliament has decided that Sweden should increase its usage of renewable fuel sources to a level of 50% of the total energy consumption in Sweden by the year 2020. One way to reach that goal may be to increase the usage of stumps as a bio-fuel. In Sweden stump harvesting is possible on about 5-10% of the total harvested area and thus contribute with 1,3 - 2,6 TWh per year. An increase stump harvest doesn't come without its drawbacks for the environment. When harvesting stumps a tracked excavator is used to pry the stumps from the ground and then cut the stumps into smaller pieces. Storing stumps makes for cleaner and dryer stump wood. Shredding of stumps is increasingly used to get higher payloads on the trucks used to haul the stumps and thus increasing the economically feasible transport distances. The goal of this master thesis was to examine the productivity of a Doppstadt 3060 W and to perform a market research regarding shredders and grinders.To calculate productivity of the shredder, the machine was filmed during work. After that a direct continuous time study was carried out. The crushed parts of the stumps was measured at the heating plant. The market research was carried out by methodic structuring of available information.The productivity of the shredder Doppstadt 3060 W amounted to a mean value of 19,25ton/E0h. The machines of the market research was divided into shredders and grinders and in sub categories; mobile, semi-mobile and stationary.