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