Rudnick & Enners have installed a containerised “compact pelletising” wood pellet plant solution for an Austrian sawmill client. The plant was supplied turnkey plug'n'play requiring only minimal site preparation to create a flat surface.
Rudnick & Enners Gmbh, a German company specialised in the development and manufacturer of components and turnkey systems for pellet plants, sawmill equipment and wood processing solutions has announced the successful installation of its containerised “compact pelletising” wood pellet plant solution for an Austrian sawmill client.
Site and size constraints
The client processes locally sourced spruce and wanted to use wood residues from its sawmill operations, but had only a small space available for pellet production and storage. Furthermore pellet production capacity was limited to a maximun of 1 tonne per hour. Rudnick & Enners was awarded the contract to supply its compact pellet plant concept. The scope of the turnkey order included complete engineering, final layout, supply of full machinery and full commissioning and operational staff training.
A key feature is that the pellet plant does not require a building to house the plant or even a concrete foundation as a flat surface will suffice. It is entirely modular with all the equipment fitted into 20 ft containers that are connected to each other and form the housing for the plant. Only external utility connections are needed. This approach reduces capital costs and the installation footprint, lower energy costs due to short conveying distances while increasing mobility.

Single belt dryer
A wheeled loader loads wet sawdust and wood chips produced by the sawmill into a buffer bin designed in 20 ft container and fitted with a hydraulic push floor. A 4 kW power supply guarantees trouble-free operation 24 hours per day. An integrated chain conveyor transfers wet feedstock from the buffer bin to a rotating screener to separate fine and coarse fractions in order to feed homogenous sized material to a low temperature single belt dryer.
Developed by SwissCombi in collaboration with Rudnick & Enners the 2 m wide belt dryer is equipped with a fine mesh polyester belt that keeps dust emissions under 8 mg/Nm3. This eliminates the need for additional dust separation equipment. Complete with a fan plus corresponding hot water-to-air heat exchangers, the incoming material is dried from about 50 percent moisture content down to around 10 percent on exiting the dryer. With available hot water of about 100° C feeding temperature a process drying temperature of about 90° C can be achieved and a return flow temperature of about 80° C.
The homogenously dried sawdust or wood chips are transferred upwards by bucket elevator and then by a tube belt conveyor into a buffer storage bin on top. Ultrasonic sensors monitor and regulate the product level in the buffer bin. A screw conveyer feeds a 75 kW direct drive hammer mill that mills the material into a 0–10 mm size fraction. A starch dosing unit, a cyclone followed by a rotary valve and humidity mixer are stations that the material passes en route to the next process stage. Before pelletising, the material rests in a maturity bunker to ensure homogenous moisture content of 10-12 percent. A mixer with water injection is installed on top of a 75 kW CPM pellet press. The entire process operation and control is done from a single cabinet utilising its own PLC.
Local markets first
The pellets are transferred to a 275 m3 storage silo which is fitted with level sensors. When unloading, a chain trough conveyor followed by weighing cells take the pellets to a rotating screen to separate fines and broken pellets from the final product. The pellets are ENplus certified and are sold in bulk via distributors as well as to the local market.
4760/AS