Metering Wood Waste to Boilers Georgia Pacific Dimensional Lumber Mill in Pineland, TX

General Description

Georgia Pacific in Pineland, TX is a dimensional lumber mill that produces structural lumber such as two-by-fours and two-by-sixes that are used for commercial and residential construction. The Pineland mill has been in existence since 1910 and was purchased by Georgia Pacific from Temple Inland in 2013.

Wood waste in the form of wood chips, shavings and sawdust is a byproduct of the lumber making process. Georgia Pacific utilizes the wood waste to fuel boilers for generation of electricity to power plant operations. Georgia Pacific was having continuous problems with an existing boiler feed system. Wood waste was not properly discharging to the boilers causing interruption of the process. Working with Motion Industries and Georgia Pacific, KWS provided a cost-effective, long-term solution to the boiler feed problems.

Design Parameters

1. Product Type – Wood Waste (Wood Chips, Shavings and Saw Dust)
2. Material Density – 30 to 35 Lbs. per Cubic Foot
3. Conveyor System Capacity – 4,500 Cubic Feet per Hour
4. Moisture Content – 35 to 50-Percent Moisture
5. Duty – 16 Hours per Day, 6 Days per Week

KWS Advantages

A team of engineers from Motion Industries and KWS visited the Pineland mill and met with the Georgia Pacific Boiler/Kiln Supervisor to review the application and determine the exact needs of the plant. There were many problems with existing boiler feed system that caused interruption to the flow of wood waste to the boilers. Wood waste would build up on the discharge side of the hoppers causing bridging and rat-holing. When the system was shut down, wood waste would still discharge from the hoppers into the system. The existing system was either under or over feeding the boilers. The Georgia Pacific Boiler/Kiln Supervisor just wanted a system that worked consistently.

While onsite, the team gathered dimensional information on the existing equipment to determine solutions and recommended a new feed screw design that would resolve the problems.

Special Features

The existing boiler feed system consisted of a four independent screw feeders that were flood-loaded. The existing screws were incorrectly designed as full-pitch, causing the uneven discharge of wood waste to the boilers. After careful review of the application, KWS recommended mass-flow type feeder screws to replace the full-pitch screws. The mass-flow screw design would eliminate all of the current problems. The mass-flow screw design eliminates bridging and rat-holing in the hopper and promotes consistent flow of bulk materials.

After examining the wood waste and the torque generated by the existing drive units, KWS offered an extremely heavy-duty design with 3-bolt drilling, heavy-wall pipe and ¾-inch thick flights. Breaker bars were also added to the discharge end of each screw to promote even discharge of wood waste. Once installed, these new KWS screws would probably last the lifetime of the plant and require zero maintenance.

KWS also added a strike off plate on each screw feeder to eliminate the unwanted discharge of wood waste when the screw feeders were not operating. The strike off plates were adjustable so Georgia Pacific could “fine tune” the discharge rate from each screw feeder.