The XIA-Xylexpo Innovation Award in the Sustainability category was given to the SMU dust extractor battery by Spänex, based in Uslar, Germany.
Before illustrating the proposal received by the award secretariat, I think it is useful to make a premise. There are two applicable European safety standards for chip and dust extraction systems for woodworking machinery: EN 12779 of 2016 for chip and dust extraction systems with fixed installation, and EN 16770 of 2018 for systems for indoor installation, with filtered air recycling (fixed or movable).
The EN 16770 standard applies to dust extractor with nominal flow capacity up to 8 thousand cubic meters per hour (the value is nominal as it is based on a conventional average speed of 20 meters per second across the entire section of the air intake opening). In practice, this means that indoor dust extractors so far available in the market can be used only up to a maximum of 10 thousand cubic meters per hour. For higher flow rates, the inevitable choice so far was a filtering unit installed outdoor, much more expensive, as outdoor filtering systems need longer suction lines, air return systems, access ladders and maintenance platforms. All these additional costs can be avoided with dust extractors for indoor installation.
Furthermore, there are situations where the necessary conditions for the outdoor installation of dust extraction systems with more than 10 thousand cubic meters/hour capacity cannot be complied with; for instance, when you don’t have a large enough safety area for the opening of anti-explosion release hatches. The alternative solution of placing the filtering system indoor and equip it with flameless pressure discharge devices is not viable sometimes, also for structural reasons. So, a different solution was needed.
Based on this premise, Spänex developed an innovative concept and designed a system based on their “Smu” dust extractors, specifically for applications with the conditions described above.
According to the extraction volume requirements, two, three or four “Smu” extractors, each with up to 10 thousand cubic meter/hour flow capacity, are installed side-by-side to create an extraction battery offering an airflow of 20, 30 or 40 thousand cubic meters per hour. As a result, the filtering systems for fixed outdoor installation in this performance class can be replaced by dust extractors mounted indoors.
For instance, an extraction center with two “Smu 100” units with a total flow rate of 20 thousand cubic meters per hour is 25 percent cheaper than a standard filtering plant for outdoor installation.
At Xylexpo 2022, an extraction system with two “Smu 100” units was up and running at the Weinig Holz-Her booth, with a SHB briquetting press installed under it (see picture on the right/left).
The “Smu” extractors, complying with the European standard EN 16770, were tested by the German institute “Dguv” and obtained the German mark “GS” and the test certificate “H3” for their minimum content of residual dust. This means that all the working safety and security requirements are met.
Let’s review the technological features of this system and its benefits. Each compact “Smu” extractor by Spänex is a full-featured separation station, consisting of an extraction and filtering chamber, a ventilator cell and a container. The ventilator is located on the filtered air side and provided with a high-performance impeller that ensures the highest efficiency. The next-generation energy-saving electric motors are in IE3 efficiency class as standard (IE4 optionally), with inverter-controlled speed to adjust the extraction power as required (according to the machines in operation).
To overcome the pressure drops in the woodworking machines and in the piping, the suction intakes of the extractors feature high suction pressure values. Soundproofing is very effective, reducing noise emissions to ideal levels, to such an extent that no additional external silencers are necessary.
The high separation efficiency of the tested filtering material ensures residual dust in the air below 0.1 milligrams per cubic meter. The compressed air cleaning system “Jet Pulse System” of the “Smu” ensures effective while delicate cleaning of the filtering elements, with low compressed air consumption, resulting into long operating life. The accurate design of “Smu”, combined with the special filtering elements, has resulted into compact enclosure dimensions, with consequently small installation footprint and height.
The piping on the side of dust-laden air is designed to guarantee the required flow rate for each connected machine, whatever the number of machines simultaneously in operation. The suction intakes of the connection lines are provided with gate valves, which are opened and closed automatically by the control system. The latter maintains optimal values for the transportation speed of chips and dust inside the piping, so as to avoid material deposits.
The extracted chips and dust are temporarily stored into the containers of the “Smu” extractors, and then transferred – via outlets and rotary valves (decoupling elements) – to a screw or pneumatic conveyor system, which takes the material to a larger container, or an outdoor silo, under which a briquetting machine is normally installed. The productivity of the latter is set according to the volume of material to be disposed of. Spänex also manufactures briquetting presses (typo “Shb”) for chip and dust flow rates between 0.5 and 2 cubic meters per hour.
The briquettes are burned to heat the factory.
The extraction plant operates smoothly and reliably thanks to its electric control system, which can be equipped, upon request, with a remote maintenance module, directly connected to the Spänex headquarters.
The speed control by means of inverters (variable frequency drives) delivers the exact extraction power required in each moment. The speed of the two, three or four fans of “Smu” is adjusted according to the integrated controller, to achieve the required combination of flow rate and extraction pressure. As the operating mode and time of each machine can vary also at full capacity, this feature is very important to minimize energy consumption. In the case of pneumatic conveyors, also the temporary storage of extracted materials into the “Smu” containers helps reduce the electricity bill.
by Matteo Simonetta
