A 250-m-long medium-pressure conveyor line was designed for 10,000 kg/h of dry sawdust and wood chips. The blower unit is located in a soundproof housing, and to separate the material, Scheuch Ligno installed a round filter with a rotary valve. The sawdust and wood chips are then weighed on a belt scale before being pressed into pellets in the pellet mill. A second, 350-m-long medium-pressure conveyor line transports a maximum of 17,500 kg/h of wet sawdust and wood shavings. Here, the blower unit is located outside. The material is separated over the maximum permissible installation height by means of a silo filter with a pressure-controlled ventilation fan. These byproducts, too, are processed into pellets.
“The aim of these systems was to transport sawdust and wood shavings over a longer distance to the adjacent pellet mill. We compared the solution proposed by Scheuch Ligno with conveyor belts and industrial trucks and decided that it is suitable for our requirements,” CEO Ernest Schilliger explains. “We have implemented several projects with Scheuch Ligno in recent years. The reason for this ongoing collaboration is certainly the professional handling of orders by Scheuch Ligno, but also the reliability of their solutions.”
Suitable pipe bends were selected for both medium-pressure conveyor lines. For the dry sawdust and wood chips, round pipe bends were chosen as their large bend radius and a long service lifetime makes them the ideal solution. For the wet byproducts, which are more aggressive, special bends with wear protection were selected. The advantage of these bends is that the back can be easily replaced if it is worn.
Two chip extraction systems for the new CLT plant
A real showcase project was carried out in 2019: Schilliger Holz built a brand-new CLT factory in Küssnacht for panels which are up to 14 m long and 3.4 m wide. For this production facility, Scheuch Ligno built two chip extraction systems with respective air volumes of 165,000 m³/h and 130,000 m³/h, and installed highly efficient extraction fans with closed impellers with motor outputs of 450 kW. These two systems are characterized by their good sound insulation which is achieved through sound-insulated pipes, return air silencers and sound insulation housings. Scheuch Ligno took over the entire assembly work, installed the electrical infrastructure, and put the systems into operation on time. Despite the limited space available, everything was implemented as planned. “We already knew Scheuch Ligno from a previous project and therefore included them in the planning. The solution they offered for our requirements convinced us,” Schilliger says.
Contract awarded for the CLT factory in France, too
In 2023, Scheuch Ligno was also awarded the contract for the extraction system of Schilliger’s CLT factory at the Volgelsheim site in France. A 19-year-old filter which had been used in two-shift operation was modernized on the inside and thus made fit for at least another 19 years. Scheuch Ligno converted the entire filter head to a modern PLC cleaning system and equipped all fans with frequency converters and negative pressure control.
Expertise and innovation since 1861
In addition to its three sawmills in Haltikon/CH, Perlen/CH and Volgelsheim/FR, Schilliger Holz also operates planing mills, glued timber and panel factories for mass timber and large-format panels (CLT), drying plants and a pressure impregnation plant. A fiberboard factory is currently under construction. Highly qualified employees and specialists in the areas of timber engineering, timber construction, surface technology, production and logistics are ready to take on various challenges. In addition, an in-house fleet of various special vehicles ensures distribution at home and abroad. Schilliger Holz’s customers include primarily the construction and packaging industries in Switzerland, France and Italy. Schilliger Holz exports wood products to Europe, the Middle East, Asia and North America.
Safe and efficient over any distance
The conveyor unit is an essential component of every chip extraction system and has a decisive influence on the operational safety and availability of the entire production facility. It is the lifeblood of the system, so to speak, and ensures smooth operation, especially in complex, interlinked production units. Scheuch Ligno has always been known for its reliable conveying systems. The uncompromising design with a focus on performance and availability is one pillar of the company’s philosophy. Pneumatic conveying systems transport the material, such as sawdust, wood chips, dust or pellets, from the feed unit to a storage facility or a separation system. At the feeding point, a rotary valve (pressure barrier and protective system) feeds the material into the conveying air flow which carries it through the conveyor pipe.
Depending on the project requirements, the type and quantity of material and the length of the conveying line, low- or medium-pressure conveying systems are used. Low-pressure systems are designed with a direct or indirect positioning of the fan, depending on whether the fan is installed in front of or behind the feeding point. They are available both with and without a closed circular pipeline. “With our comprehensive know-how, we always offer customers the most efficient solution for every application,” Scheuch Ligno states.
Medium-pressure conveying systems – the most important components
Medium-pressure conveying systems (MP conveying systems) are a cost-effective choice when materials need to be conveyed over long distances and/or in large quantities. They involve indirect transport – the blower unit is positioned upstream of the material feed unit.
Key components of an MP conveying system are the rotary piston blower, which is highly efficient but keeps energy costs low, the material feed unit with a very robust rotary valve and a T-injector for effective material acceleration as well as the flow-optimized pipe system. Thick-walled steel pipes and special bends with wear protection and a large bend radius ensure long service lifetimes and high operational safety.
Material separation with filtration
If a closed circular pipeline system cannot be used, a filter system is used at the end of the conveying path. The project-specific requirements are decisive for the selection of the separator to be used. Scheuch Ligno’s comprehensive product portfolio offers the best economic solution for every application:
Round filter with pressure-shock-resistant casing and rotary valve:
- large quantities of material
- ATEX-tested (certified) filling of closed silos
- largely pressure-free filling of silos via the rotary valve
- silo decoupling by means of ATEX-certified rotary valve
Filter with panel design with a solid structure and rotary valve:
- large air volumes
- ATEX-tested (certified) filling of closed silos
- largely pressure-free filling of silos via the rotary valve
- distribution of material to multiple silos or containers
- silo decoupling by means of ATEX-certified rotary valve
Silo filter (direct injection) with high compression strength:
- large quantities of material
- positive pressure inside the silo
- low installation height
- specifically for MP transport and large quantities of material
- certification for backfire and explosion decoupling available
Powerful extraction and dust removal systems
Efficient and resource-saving production processes are becoming increasingly important. Scheuch Ligno’s innovative air pollution control technologies and processes make a significant contribution to this. The company develops individual system layouts for every specific requirement and offers every customer the economically best solution, for craft businesses and industrial companies alike. The aim is to increase efficiency and reduce operating costs. Scheuch Ligno offers everything from a single source: from consulting and project planning to production, logistics, assembly and commissioning as well as system servicing and emission measurements.
