LP Houlton was faced with some aging equipment when they were getting ready to convert their OSB line to an LSL production line. 

The decision was made that much of the existing equipment on the wood drying side would be re-used or re-tooled.  This included the air abatement system consisting of a GEO WESP and a Huntington RTO.

The RTO was constructed primarily of carbon steel and was showing its age due to the high moisture content associated with a gas stream after a WESP.  LP knew they were facing some significant repair and maintenance bills which would include replacing the combustion chamber (with stainless steel), complete replacement of the heat recovery media, and repairs to coldface, internal insulation and ductwork.

LP contacted MEGTEC for a quote on a new RTO and found that the latest technology in RTOs would provide some secondary benefits such as reduced moving parts, lower fuel consumption and, most importantly, the unit would be designed to take advantage of newer, lower pressure drop ceramics. Some of LP’s existing equipment could also be re-used. The basic RTO housing and valve(s) could be replaced with new, while re-using some components that typically account for up to 25% of a greenfield installation.  The components that could be re-used included the RTO stack (110 foot tall stainless steel); two main draft fans and motors; two main fan Variable Frequency Drives (VFD’s); the wiring between the MCC room and the RTO; and existing power feeds and transformers.

Unfortunately, the frequency drives for the motors were obsolete and hard to repair so LP opted to replace them with new Allen Bradley drives. Also, a damaged fan wheel was replaced with a new one.

The new RTO housing, VFDs and fan wheel were installed in the winter of 2007-2008 and have been on line since February 2008.  The MEGTEC RTO uses a patented valve that allowed the twenty one (21) flow control valves of the older RTO to be replaced with only one switch valve.  This greatly reduced the number of actuators, limit switches and bearings that are associated with that many valves.  The new RTO was supplied with other advancements over the older unit which included:

• Low pressure drop structured packing

• Higher heat recovery for 20% reduction in fuel consumption

• Oversized heat recovery bed which would accommodate structured OR random packing

• Large hinged access door for the burner chamber

• Air Gas Ratio Control (AGRC) system in which the PLC controls air and gas flow to the burner

• Single large hinged access door for the valve manifold

• Clean out ports and a highly re-cleanable heat recovery bed

• Stainless steel combustion chamber

• Raised housing which reduced footprint by 30%

• Water dropout sump before RTO

• On line bakeout

• Heated valve sealing that ensures MACT compliance

• Pallet-size loading doors on top of flat roof

LP also contracted MEGTEC to fabricate and install the enclosure system for the new press.