Industrial Tests Of Thick Veneer Slicing And Drying Technology

Author : Randall C. Zenke
Publisher :
ISBN 13 :
Total Pages : 178 pages
Book Rating : 4.:/5 (36 download)

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Download or read book Emission, Energy, and Production Efficiency of a Radio-frequency Assisted Gas-fired Veneer Dryer written by Randall C. Zenke and published by . This book was released on 1992 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt: The drying of wood is required in most forest products manufacturing operations. Depending on the wood species, dimensions, drying temperatures, and drying duration, the amount of emissions and energy consumption can greatly affect the operating cost, environment, and quality of wood dried. As such, the forest products industry continues to explore the use of new technologies to address these points of concern. A study was done to evaluate the addition of a radio-frequency (RF) heating system to a natural gas-fired conventional veneer dryer as a means to reduce emissions, reduce energy consumption, and improve productivity while maintaining material quality. To establish the benefits of RF-assisted drying, a study comparison was made for drying wood veneer in a RF-assisted dryer and a conventional dryer. The study was conducted at Western Veneer and Slicing in White City, Oregon. This plant was selected because both types of dryers, an RF-assisted dryer manufactured by Production Machinery, Inc. and a conventional dryer manufactured by Amitec, were located at the same site and were used for drying the same type of material. Two comparison drying tests were conducted, one using sliced ponderosa pine and the other using rotary peeled Douglas-fir. The sliced veneer was selected because it was the type of material used by the White City plant and the rotary veneer was used because it is of the type used in the plywood industry. The parameters measured for each drying run were material flows, drying rates, emission rates, dryer operating conditions, exhaust conditions, and electrical and natural gas consumption. It was found that although the RF-assisted dryer was able to successfully dry the sliced veneer as it was designed to do, it was not properly "tuned" to efficiently dry the rotary veneer. Therefore, the results of this study should only be made for the sliced veneer studies. The study found that the RF-assisted dryer was able to reduce total emissions comprised of particulate, organic, and inorganic components. The emissions reduction was 16% based on a total throughput basis (dry material plus redry) and 36% based on a dried production basis. Whereas, energy use for the RF-assisted dryer in terms of Btu/lb of water extracted was found to be approximately 15% higher, which was due mainly to over-venting of the exhaust system. It was recommended that the exhaust be damped to provide comparative energy use to the conventional dryer. The RF-assisted dryer was also found to be more productive in that its redry rate, the amount of veneer that needed to be redried, was lower; likewise, the variance of veneer moisture was lower. The aesthetic quality of the RF dried veneer was described by the experienced veneer graders employed by White City Veneer and Slicing as being better in terms of brightness and brittleness, however we were unable to quantify this difference. It can be concluded that the RF-assisted system for the study conditions appears to be an improvement over the conventional system in terms of emissions, productivity, and maintaining veneer quality.