Technical information

Annual capacity:
25,000–100,000 m³ (11–42 MMBF)

Dimension mix:
16–75 mm

Door system:
Vertical doors

Fans:
2–4 axial fans/zone

Heat recovery:
Air/air or air/fluid

Spraying/steaming system:
High-pressure hot water or steam

In the 3-zone kiln, an additional zone is added to the two zones found in FB and OTC kilns. This extra zone functions purely as a conditioning zone, making it possible to achieve even higher quality, even at very high capacity.

Lumber types and capacity Since both FB and OTC kilns can be equipped with a conditioning zone, this results in a capacity of up to 100,000 m³ (42 MMBF). The kiln is suitable for all dimensions with a target moisture content of 8–18 percent.

Advantages of the conditioning zone With a third zone, continuous kilns can also be used for drying to lower moisture contents, something often associated with batch kilns. The conditioning zone is equipped with fans, heating coils, pressure frames, spraying/steaming equipment and its own ventilation. A door is mounted between the conditioning zone and zone 2, which means that the climate can be regulated separately from the rest of the kiln. Normally, the zone has two package positions, which – depending on feed intervals – provides a conditioning time of 4–8 hours.

Two smiling Valutec workers looking into the camera.

A sustainable choice. From design to operation.

Valutec continuously develops energy-efficient solutions for lumber drying. This includes well-insulated kilns, heat recovery systems and a wide range of energy-saving features in the Valmatics 4.0 control system. The kilns are built in stainless steel rather than aluminum, to maximize service life and minimize CO₂ footprint. With well-designed kilns, heat recovery and intelligent controls, we ensure a more sustainable drying process.

Principle

After the regular drying process, the lumber enters a conditioning zone where the climate is adjusted to reduce stresses in the wood. Axial fans circulate air through heating coils and across the lumber.

As an industry leader in lumber drying, we embrace the innovative opportunities offered at the very forefront of research. This allows us to consistently deliver solutions that meet the high standards we set for our products. Through a combination of knowledge, experience and a world-leading research department, we have developed a wide range of technical solutions.

Fans

Axial fans optimized for operating conditions to ensure maximum efficiency. Diameters range from 1,400 to 1,600 mm, with adjustable or fixed blades. For operating temperatures above 90 °C, motors are equipped with air cooling, supplied by an external cooling fan.

Doors

Rigid door leaves in aluminum or stainless steel, built from the same high-quality elements and joint system as the kiln construction. Insulated with mineral wool and fitted with profiled cover sheets for excellent heat and sound insulation. The elements are held together by an outer frame with sealing strips, and pivot-mounted pins provide effective locking against the door frame. Door lifting with electric vertical winch.

Efficient motors

Valutec continuous kilns are equipped with synchronous reluctance motors as standard. Their efficiency meets the IE5 classification – three steps above the current EU requirement of IE2 – enabling energy savings of up to 25%. Permanently lubricated bearings keep motor temperatures 10–20 °C lower, providing up to four times longer service life compared to IE2 motors, while minimizing CO₂ emissions.

Pressure frames

Pressure frames ensure minimal deformation of the top lumber layer. A stainless steel, stable guided frame allows fixed cylinders and a fully tiltable design without risk of jamming. Provides up to 2 tons of pressure per package. Equipped with stainless steel piston rods with Viton seals and stainless steel tubes with fittings. Also available in a scissor version for integration into existing kilns.

Flaps

Both our own experience and independent research show that sufficient air volume – and thus air velocity – through the lumber packages is crucial for optimal results. This is achieved through good aerodynamics, high-performance fans with sufficient capacity, and efficient sealing devices. To minimize energy loss and unnecessary moisture variation, Valutec offers a well-developed system of sealing flaps around the lumber load:

Fixed side and roof flaps with EPDM rubber or polyamide cloth
Adjustable side flaps with manual control mechanism
Roof flaps integrated with pressure frames

Spraying/steaming system

Designed to minimize checking, ensure controlled moisture distribution and even out moisture gradients.

High-pressure hot water spraying (HTVVB)
Preheated water is pressurized and atomized through separate nozzles. The higher water temperature facilitates evaporation, providing efficient humidification of the circulating air.

Steaming (Relax process)
The system uses steam to create a controlled climate during heating and conditioning. As the steam condenses on the lumber surfaces, it delivers very fast heating.

Valutec places great emphasis on safety and offers the market’s safest kilns. Most of Valutec’s safety solutions are controlled via a dedicated safety PLC located in the kiln’s machine room.

Safety doors

The kiln is equipped with safety doors. If a door is opened during operation, the system shuts down immediately.

Automatic feeding system

The kiln’s lumber feeding system is fully automated. Lumber is loaded onto wagons that move through the kiln. Entry and exit are equipped with light beams or radar.

Doors

The kiln doors are designed for maximum robustness and are operated by dual motors and gears.

Wet bulb bath

When the wet bulb bath is opened, the air intake is automatically shut off to prevent the risk of burns during cloth replacement.

Manhole

The manhole is equipped with a safety switch. If the hatch is opened during operation, the kiln shuts down immediately. It can be opened both from the inside and outside.

Light beams/radar

Light beams/radar eliminate accident risks by stopping the kiln in case of unauthorized entry. They are easy to use and contribute to a safe working environment.

Valutec offers a range of options for your kiln, designed to increase energy efficiency and maximize final product quality. Contact us for recommendations on the options best suited to your production.

Interior of Valutec’s lumber kiln with heat exchanger for energy recovery.

Heat recovery

Air/air
Valutec’s air-to-air heat exchanger (VÅV) is a counterflow unit that recovers energy from the exhaust air to preheat the intake air. For continuous kilns, energy recovery typically reaches 15–20% within normal temperature ranges. The compact design is virtually maintenance-free. The exhaust fan is placed next to the exchanger, with two standard sizes available depending on air volume.

Air/fluid
Valutec’s air-to-fluid heat exchanger recovers energy from the exhaust air by transferring it to the intake air. The exhaust air passes through a coil where the energy is transferred to a heated glycol circuit, which is pumped to a coil that heats the intake air to the kiln.

The construction is compact, fully stainless steel, and virtually maintenance-free, apart from the power supply to the circulation pump. For normal temperature ranges, energy recovery reaches about 15–20% for continuous kilns and 8–15% for batch kilns, depending on geographic location and lumber type. By transferring recovered energy to other consumers – such as intake air for other kilns, building heating, or ground heating – recovery levels can be significantly increased.