What was disposed of in the past is now recovered as a valuable fuel: sawdust, wood chips and shavings are a great sustainable source of energy – provided they are pressed into briquettes. Companies operating in the various sectors of the timber industry are therefore well advised to find an optimised method to turn their sawdust and chips into something more valuable. Briquetting is one of the most cost-effective options, as it offers a range of advantages over other solutions such as wood pellets. A study carried out by the Technical University of Graz in 1996 shows clearly that the amount of energy required for the collection of the wood material and the forming of the briquettes is only about half that necessary to form wood pellets – while both forms of fuel contain of course the same energy.
When choosing a briquetting unit, it is important to take into account a number of criteria in order to find the most cost-effective solution: Apart from the initial acquisition costs, factors such as the output rate, the energy consumption and the reliability of the unit as well as the quality of the briquettes and the after-sales service offered by the manufacturer are equally important. Another aspect to be considered is the space requirement of the machine and the size and shape of the end product.
Single-briquette press principle for wood waste quantities of 10,000 kg/month and more
For small carpentry shops that produce around 10,000 kg of wood waste per month, we recommend installing a low-cost briquetting unit based extrusion technology. 'If the amount of wood waste exceeds this limit, it is however more economical to use a high-quality briquetting unit that forms individual briquettes without using any bonding agents or other additives,' says Roland Ruf, engineer and head of the R&D department of RUF GmbH Firma Ruf.
This is exactly the type of machine available from RUF GmbH, the briquetting specialist based in Zaisertshofen, Germany. The RUF units produce quality briquettes in a simple and highly efficient process. If requested, the machine can be fitted to produce your logo on every briquette. The briquetting process is extremely simple: An extraction system transports the woodchips and sawdust from the wood processing point to the press, which is started automatically as soon as a sufficient amount of material has been collected. Depending on the requirements and the type and quantity of wood waste, the RUF produce easy-to-handle rectangular briquettes. The actual capacity of the units varies from 30 kg/h to 1500 kg/h, whereby hydraulic units with power consumption rating of 4 to 90 kW are used. RUF machines produce handy rectangular briquettes of 150 x 60 mm, while larger units produce briquettes of up to 260 x 100 mm in size. The length of the briquettes is also variable within given limits. Briquettes with the above dimensions can be easily stacked and packed for dispatch.
As the wood is pressed into briquettes under huge pressure but without using any bonding agent, the briquettes are a natural product conforming to the environmental requirements laid down in DIN 51731 and ÖNorm M 7135. RUF briquettes are thus a clean solid fuel that can be burnt in nearly any type of solid fuel burner or stove. All that is left behind is a small amount of ash.
Another significant advantage of the single briquette press principle of the RUF machines is their compact size. The units thus require only minimum floor space. Depending on the model, 1.4 m2 to around 8 m2 is enough space for their installation. Behind the press, the warm briquettes are collected in a container that must be replaced and emptied from time to time. Alternatively RUF machines can be equipped with an automatic packing system.
Briquetting machines applying the extrusion method require roughly the same floor space. There is however a caveat: 'If the extruded wood bar is to have the same density and quality as a briquette produced in a RUF machine, it would have to leave the machine at an extremely high temperature,' explains the engineer Roland Ruf. As a consequence, the machine must be equipped with a separate cooling section of up to 50 metres in length. Only after the bar has passed this section can it be cut into round blocks for storage. The space required by the additional equipment normally exceeds that needed for the machine itself.
The choice of machine must also be based on the type of shavings or dust and the density of the material. Briquetting machines by other manufacturers might not be able to process very find dust or rather large wood chips. If the bulk density of the material varies considerably, it might be necessary make some manual adjustment to the process. RUF units on the other hand automatically adjust the settings to suit the actual bulk density and can process any type of wood waste, from the finest sawdust to 50 mm chips.