MORGAN lumber turns up the heat
MORGAN lumber turns up the heat
For this mill, the Counter-Flow Kiln has removed the bottleneck and vastly improved the energy efficiency and grade yield of its products.
In response to a bottleneck at its dry kilns, Morgan Lumber of Red Oak, Virginia recently invested in USNR’ s Counter-Flow Dry Kiln, Green Fuel Burner and Kiln Boss controls.
Don Bright, mill manager, explained the thought process behind the selection of the new direct-fired kiln.“ The continuous process seemed like the most cost-effective way to get the increase in production we required. It’ s a noticeable improvement in the quality of drying, and it’ s a significant increase in the efficiency of drying.”
Don did have some trepidation when it came to the Green Fuel Burner, however.“ I was really concerned about going from steam to directfired. We bag shavings for the equestrian market and I knew it would be a real problem if we had ash in those shavings. When we went to
“ I’ m extremely satisfied with the system’ s performance. We’ re using 40 % less sawdust per 1,000 board feet to dry our lumber. We’ re using 14 % less electricity. We get a better grade yield, and it’ s produced noticeably less drying defect.” the direct-fired kiln I really spent a lot of time researching it, finding out what was available, and what we could do to reduce the amount of ash on the lumber.”
Ultra-clean burn
To make sure ash would never be an issue, USNR engineers recommended some changes to the system’ s design that are proving positive to produce an ultra-clean burn. Don explains,“ USNR nailed it. We made some changes in the burner and we have zero ash problem. It was a home run!”
Easy, effective operation
Don appreciates the ease and effectiveness of operating the continuous kiln design.“ With the continuous kiln we can make small adjustments as we go, so it is easier to fine-tune the drying process.” With the new system, fine adjustments can be made to the tram speed, kiln temperature, and after only a few hours the lumber can be checked and further adjustments can be made to attain the optimal balance of quality and efficiency. Don also noted that with the Kiln Boss control system it is easy to change the drying recipe, even from home.
Don said,“ I’ m extremely satisfied with the system’ s performance. We’ re using 40 % less sawdust per 1,000 board feet to dry our lumber. We’ re using 14 % less electricity. And speaking of quality, our standard deviation with the old batch
The Counter-Flow Kiln concept
The Counter-Flow Kiln consists of a central heating chamber along with large conditioning chambers on each end. The kiln operates continuously. This process produces lumber with less stress and a tighter moisture distribution than traditional batch processes. It uses a staging and loading system to keep packages moving through the kiln continuously and automatically, with the capability to process lumber at different rates on each track based on product dimensions and kiln conditions.
The Counter-Flow Kiln design was developed by USNR’ s Jacksonville, Florida team and Andy Pollard of Pollard Lumber, at Appling, Georgia. The original design called for a structure three times the length of a traditional batch kiln using equal-size heating and conditioning chambers. Subsequent design optimization based on field experience allowed USNR to shorten the conditioning chambers without compromising performance, reducing the total length( and cost) of the system.
Theory behind the design
The theory behind the design was unique at the time it was developed. Loads of lumber are run side-by-side on a double track in opposite directions through the kiln. This creates an opportunity to let the hot lumber exiting the kiln on one track give up some of its heat to the green, cool lumber entering the kiln on the other track. At the same time the green lumber gives up some of its moisture to help equalize the final moisture content, in effect conditioning the dry lumber. This transfer of heat and mass results in an overall energy saving, the lumber suffers less degrade due to the equalizing and conditioning, and the continuous movement of the lumber offers higher production in terms of board feet dried per hour. The goal was simple: dry more lumber in less time and with less energy.
kiln was 3.2 average per year, this year we’ re averaging right at 2. That is huge. We get a better grade yield, and it’ s produced noticeably less drying defect.”
ISSUE 3- 2013 | Millwide INSIDER 21