Fukthalt i GROT - påverkande faktorer
This study was carried out at the request of the bio energy company Naturbränsle. The company handles annually 750 000 m3 of chips from logging residues from a large area, from Östergötland in the south to Härjedalen in the north. In that area, about 50 bio fuel plants are customers. When Naturbränsle deliver chips from logging residues to their customers, the moisture content varies from 30 % to 60 %. The aim of the study was to sort out the affecting factors on the moisture content in the chips during handling and storage processes. The data was collected from 38 objects. The objective was to be able to steer handling and storage processes to get a homogeneous and low level of moisture content in the chips. This leads to a higher energy level in the chips. The entrepreneurs that forwarded the logging residues were interviewed. In the interview they gave their opinion on what they think is important when handling logging residues. It has been examined if precipitation during the time logging residues were forwarded to be storied affects the moisture content in the chips. Data from SMHI was connected to the occasion when the logging residues were forwarded and put together to be storied in a covered pile. It has been examined if the point of time when the forwarding and chipping was performed had an effect on the moisture content in the chips from logging residues. The moisture content was measured in the bio fuel plants when the chips were delivered. When the moisture content had been measured it was connected with the data that were collected from the field work and the data from SMHI. To examine which of the variables that had the highest affection on the moisture content correlation- and regression analyses were made.
The result indicated that the factors which affected the moisture content the most were those that are season related, such as point of time when the forwarding and chipping is performed. Logging residues were affected by the seasons in the way that they dried between April-August, and then they increased in moisture content in the autumn. During winter the moisture content neither increased nor decreased. According to the result it is possible to preserve low moisture content from dry seasons such as spring and summer.
Keywords: Moisture content, affecting factors, point of time for forwarding and chipping.