PDF Publication Title:
Text from PDF Page: 007
General Technical Report FPL–GTR–287 Figure 4. Charge of thick slabs stacked in single layers between heating platens. Figure 6. Charge of lumber hand-loaded and stickered for drying in a cyclical vacuum kiln. Figure 5. Loading 4-in.-thick white oak live-edge slabs into a vacuum kiln. These large slabs require the use of a forklift for the slabs and hand-loading of the aluminum platens between each slab. Figure 7. Mechanized, automated loading system at a large-scale drying operation (photo used with permission from Vacutherm, Inc., Barre, Vermont, USA). aluminum platens through which the hot water circulates to heat the lumber. After drying, the lumber and platens are unstacked by hand. Hand loading and unloading the kiln is time-consuming and can present some safety concerns. Other types of vacuum kilns, such as the cyclical vacuum kiln shown in Figure 6, also require hand loading plus the use of stickers for proper airflow. Larger operations use a mechanized, automated loading system to build and unbuild the kiln charges (Fig. 7). As the loading system unloads one dry cart, it simultaneously loads a second cart with green lumber using platens from the dry cart. After the new charge is assembled, the cart is pushed into the vacuum chamber for drying. There are challenges associated with integrating a vacuum kiln into the drying process. The size of the pressure vessel determines capacity and, as with other types of kilns, available sizes are limited by the manufacturer. Some manufacturers produce vacuums kilns that can dry from a few hundred to more than 10,000 board feet (0.7 to 24 m3) of lumber per charge. A manufacturing plant must take into consideration the challenges of just-in-time material flow. For example, the schedule of a conventional kiln that holds 50,000 board feet (118 m3) of hard maple lumber takes 10 days and can dry five truckloads in that time. The schedule of a smaller 10,000-board foot (24 m3) vacuum kiln charge of hard maple lumber takes 2 days and can dry one truckload in that time. Although this ends up to be the same amount of production, the logistics of delivery, kiln loading and unloading, and shipping are different. Production and shipping schedules must be adjusted to accommodate the quicker turnover of smaller loads. High capital outlay and the potential for high maintenance costs have been a barrier for wood manufacturers to invest in vacuum drying. However, depending on particular circumstances, operational costs might be reduced because of energy efficiency and shorter drying times compared with conventional steam kilns. Each vacuum kiln system is unique and requires an advanced understanding of the operation. Overall drying variability is a potential concern. Without knowledge of the 4PDF Image | Understanding Vacuum Drying Technologies for Commercial Lumber
PDF Search Title:
Understanding Vacuum Drying Technologies for Commercial LumberOriginal File Name Searched:
fpl_gtr287-final.pdfDIY PDF Search: Google It | Yahoo | Bing
5,000 BF Shipping Container Lumber Dry Kiln For Quality Lumber The 5,000 BF container kiln consists of one 40 foot high-cube aluminum shipping container... More Info
Shipping Container Lumber Dry Kilns by Global Energy Global Energy designed and developed the container kiln back in 1991. The purpose is to give access to portable sawmill owners, furniture makers, and small business the value added profit of dry kiln lumber and quality hardwoods... More Info
Vacuum Kiln Conversion Kit for Lumber and Wood Dry Kilns Convert your existing conventional dry kiln into a fast drying vacuum kiln. Similar to vacuum bagging in the boat building and aircraft industry, we have come up with a proprietary process which allows you to build a very simple vacuum kiln at a fraction of the price, and without the intensive conventional metal chamber structure... More Info
Vacuum Pump Cart System for Bagging Clamping Wood Drying and more Vacuum Cart with 2HP Pump and Dual Pistons with multiple multiplex vacuum ports and liquid reservoir... More Info
Vacuum Bagging Basics Vacuum bagging is a method of clamping, which has traditionally been used in the composites industry, but can also be used for vacuum drying materials, including wood products... More Info
CONTACT TEL: 608-238-6001 Email: greg@globalmicroturbine.com (Standard Web Page)