The Brunner-Hildebrand HCK continuous kiln dryer is the answer to the increasing demand for continuous kiln lumber drying technology, especially in the expanding marketplace of the softwood industry.
The Brunner-Hildebrand HCK continuous kiln dryer operates in unidirectional mode with lumber package motion through the kiln in longitudinal orientation. This is a big advantage in terms of mill workflow with a clear distinction between the wet side and dry side. Forklift transport is reduced to a minimum, and there is no mingling of wet and dry lumber storage.
The Brunner-Hildebrand HCK continuous kiln dryer is divided in length into several drying zones. The number and size of the drying zones are designed according to the customer’s desired output. The kilns are rail-loaded and may operate on a single rail or with up to six rails, depending on customer specifications. Roofing may be added in front and behind to shelter lumber from rain and snow.
With some degree of simplification, the Brunner-Hildebrand HCK continuous kiln dryer may be thought of as a series of batch kilns placed next to each other with lumber flow breaching through the side walls of the individual chambers. Each drying zone is tightly controlled in terms of temperature, air speed and relative humidity; all the parameters are adapted to actual lumber moisture content.
Air speed generated by heavy-duty axial fans is controlled by variable frequency controllers with periodic reversal of flow direction. This eliminates wet spots and results in a homogenous final moisture content of the lumber.
Brunner-Hildebrand’s HTT (Hildebrand Turbo Technology) system raises air speed to the maximum without the need for overly large fans that use a lot of power. The system consists of aluminum baffles that are periodically moved in a vertical direction, shutting certain sections of the lumber stacks off from the air flow. This increases air velocity in the sections that are still exposed to the air flow while air speed is reduced to almost zero in the baffled sections. This creates a recurring conditioning effect that results in minimized spread of final moisture content distribution.
The rail lumber carts are moved through the HCK continuous kiln dryer by powerful hydraulic pusher units inserted into the concrete foundation at the kiln entrance. Hydraulic power is sized for pushing the entire lumber load forward through the kiln. Indexing of the carts is performed in full automatic mode with surveillance by a comprehensive set of photoelectric sensors and end switches.
The lumber carts feature the Hildebrand Weight Precision Technology system. Wireless weight measuring bars weigh the entire stack of lumber on the cart and record the weight and moisture loss over time. This provides much more precise moisture content control with hundreds of boards or more determining the current average moisture content.
With a multi-rail HCK continuous kiln dryer, companies can even dry lumber of different dimensions in one continuous kiln by simply running different throughput rates for each track. With Brunner-Hildebrand’s special feature, the Kiln Prime Zone (KPZ), this even works for lumber dimensions with differing final target moisture content.
With Brunner-Hildebrand’s game-changing GreenKilns technology, individual drying zones of the HCK continuous kiln dryer cooperate in a thermal compound system. Excess heat from one drying zone is extracted and routed to another drying zone that needs additional heat. With this technology, up to 25 percent of thermal consumption may be saved and reused for lumber drying in an eco-friendly way.
A leading sawmill group in Eastern Europe recently chose Brunner-Hildebrand to supply four HCK continuous kiln dryers featuring GreenKilns, HTT, HWPT and individual zone control as described above. Installation is scheduled to begin in the near future.
(For more information about Brunner-Hildebrand HCK continuous kiln dryers, visit www.bhl-drykilns.com or call (615) 301-8721.)