Drvna Industrija (Jun 2010)
Analysis of Drying Process Quality in Conventional Dry-Kilns
Abstract
This paper presents testing results of drying quality in a conventional dry kiln. Testing is based on a new methodology that will show the level of success of the drying process management by analyzing the quality of drying process in a conventional dry kiln, using a scientifi cally improved version of the check list in everyday practical applications. A company that specializes in lamel and classic parquet production was chosen so as to verify the new testing methodology. A total of 56 m3 of oak and hornbeam boards dried in a kiln were intended for use in parquet production. The length of the boards was 600-2000 mm, the width was 140-160 mm, and they were 30 mm thick. Before kiln testing, a checklist was made, according to methods of kiln operation control applied in the USA and Europe, with some modifi cations and changes of individual parts for adjustment to the technology and method of operation applied in Croatia. The evaluation was made so that each subcategory in the check list was rated from 5 to 1, i.e. from the highest to the lowest score. Three methods were used for the purpose of testing: visual check, measuring with instruments and interview of the dryer attendant. After the testing, analysis and systematization of all gathered data was carried out. The data were entered in a summarized check list, and the average results were provided for each tested category and for the whole kiln. The obtained results clearly show which parts of dry kiln, i.e. of drying process, failed to meet the test requirements. All subcategories rated 1 or 2 must be improved, while those rated 3 or 4 need to be analyzed once again in order to be improved. The parts of kiln and drying process related to fans and electric motors, stack placement, climatic conditions in the control room, moisture content control, and ability to develop and learn were far below the expectations. Only the part of the dry kiln which relates to the position of air routers and barriers to the passage of air under stack was rated as excellent (5). Other categories were rated as good enough, but required repeated analysis and improvement. The used evaluation system proved to be an extremely useful, fast and reliable way to check the dry-kiln operation in production conditions, based on scientific research and laboratory work.
