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Drying speciality hem-fir and WRC products

https://library.fpinnovations.ca/en/permalink/fpipub7665
Author
Oliveira, Luiz C.
Lazarescu, Ciprian
Star, Phil
Date
March 2015
Edition
52668
Material Type
Research report
Field
Wood Manufacturing & Digitalization
In partnership with the BC COASTAL FOREST INDUSTRY fpinnovations.ca FPInnovations
Author
Oliveira, Luiz C.
Lazarescu, Ciprian
Star, Phil
Contributor
BC Coastal Forest Industry
Date
March 2015
Edition
52668
Material Type
Research report
Physical Description
24 p.
Sector
Wood Products
Field
Wood Manufacturing & Digitalization
Research Area
Advanced Wood Manufacturing
Subject
Drying
Hem-Fir
Kilns
Steam
Temperature
Location
Vancouver, British Columbia
Language
English
Abstract
This project evaluated a number of opportunities to coastal producers related to kiln drying issues such as drying practices related to high-value products, drying with superheated steam vacuum and internal core temperature monitoring for large timbers during the heat-up phase. In summary, this project included several laboratory studies to evaluate the using superheated steam/vacuum (SS/V) for drying 7/8”x 6, green western red cedar lumber, and 8x8 and 5x(5,6,7,8,9,10,12) Douglas-fir timbers. SS/V drying yielded faster drying schedules when compared to the results obtained in industrial conventional kilns. The results obtained from the SS/V drying of WRC indicated the potential benefits of technology for drying specialty products especially when compared to drying times obtained with conventional drying (longer than 7 days). However, the results obtained also emphasize the importance of green sorting that is, sorting prior to drying to optimize drying times and reduce the variation of final moisture content. For large cross section Douglas-firs the drying times were between 3 and 14 days depending on the severity of the drying schedule and initial moisture content distribution. The influence of moisture content and cross section during the early and late stages of the heating process were evaluated on 5x5, 6x6 and 8x8 Douglas fir timbers. Thermodynamic equilibrium was reached after 20 hours regardless of moisture content or cross section size. The knowledge is intended to be used to design conventional drying schedules for large cross section timbers.
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Multi-modal approach to kiln drying of BC coastal lumber products

https://library.fpinnovations.ca/en/permalink/fpipub52669
Author
Oliveira, Luiz C.
Lazarescu, Ciprian
Date
June 2016
Material Type
Research report
Field
Wood Manufacturing & Digitalization
Scientist, Drying & Energy Group, Lumber Manufacturing In partnership with the BC COASTAL FOREST
Author
Oliveira, Luiz C.
Lazarescu, Ciprian
Contributor
BC Coastal Forest Industry
Date
June 2016
Material Type
Research report
Physical Description
31 p.
Sector
Wood Products
Field
Wood Manufacturing & Digitalization
Research Area
Advanced Wood Manufacturing
Subject
Drying
Lumber
Kilns
Productivity
Costs
Location
Vancouver, British Columbia
Language
English
Abstract
BC Coastal mills will need to diversify the drying technologies currently used and consider new approaches in order to improve productivity, reduce drying costs, regain competiveness and continue to play a significant role in the increasingly stringent quality market for forest products. New demands for drying are related to energy efficiency, low environmental impact and of course, quality of the final product. The specific objectives of the project were: (1) to improve the conventional drying of 4.5” x 4.5” Douglas-fir lumber, (2) to evaluate the superheated steam/vacuum (SS/V) drying of 4.5” x 4.5” Douglas-fir lumber, (3) to develop a green sorting strategy for hem-fir lumber and (4) to determine the time required to reach 56°C in the core of 5¼ x 5¼ lumber using the requirements of CFIA PI-07 Heat Treatment schedule Option D - Generic Phytosanitary Heat Treatment Schedule, Heat Treatment with Moisture Reduction. The results showed that the drying time in conventional drying of 4.5” x 4.5” Douglas-fir lumber can be reduced by up to 25% without compromising the quality of the lumber. This can be achieved by increasing the temperature in the final drying stages and using lower relative humidity at the beginning of the drying process. In addition, final moisture content (MC) variation was reduced from 6.2% to 3.9%. Reductions of drying times from 26% to 41% were observed when drying 4.5” x 4.5” Douglas-fir under SS/V drying. Quality of the lumber at the end of drying was better when compared to the quality of the lumber at the end of conventional drying. In addition, specimens exhibited less final MC variation. Based on drying rate measurements of green hem-fir lumber dried to 9.0% MC, a new database was developed which in turn was incorporated into OASiS 2.0 software to evaluate different pre-sorting scenarios. Pre-sorting simulations allow end users to estimate the impact of kiln productivity, final MC distribution and drying degrade. The results showed that different correlations between the time to reach 19.0% MC and initial weight or initial MC could be established. The best correlation with an R square of 0.77 was made between initial weight and MC. After performing several simulations with the new database an optimum cut-off point of 65% yielded the best results in terms of potential increase of productivity and quality of the final product. Wood heating rate test results showed that CFIA Option D may be extended for 5¼ x 5¼ lumber as long as the dry-bulb = 71°C (= 160°F) for 36 hours at the end of the heat treatment. Total heat treatment time required, including the time required to reach 71°C (160°F), is 72 hours.
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