In the surface treatment center of SIAG in Chrudim in the Czech Republic towers and nacelles for wind turbines are manufactured. We supplied 2 blast units, 2 complete coating lines and a free-space coating cabin for SIAG.
The process begins with the blasting of the workpiece surfaces. Two blast cabins with identical dimensions are available for this purpose. The workroom's internal dimensions encompass a length of 38 meters, a width of 7.5 meters and a height of 6.5 meters. Two workers wearing a full complement of protective clothing implement the manual blasting process. Rust, scale and burrs are removed using steel shot as the blasting abrasive. At 650 Lux, the workpiece is very well illuminated from the side and from above, making it possible to continuously evaluate the workpiece surface.
Two pressure pots are used, each with a capacity of 200 litres. Blasting hoses with lengths of 40 metres facilitate all of the required work positions. The 12-mm blasting nozzle operates at a pressure of about 6 bar. The extraction ducts, which are installed at staggered locations in the interior of the cabin and protected behind impact deflectors, remove the dust-laden air from the cabin. Fresh air enters through the roof. In order to give workers a continuously clear view of the workpieces, 90,000 m3 of air must be circulated and filtered every hour.
The telescopic painting and drying cabin extends to the appropriate length in order to cover the waiting tower section. The ventilation unit is designed primarily as a vertical system. To accomplish this, 10 long-range nozzles are installed in the roof elements and these nozzles introduce filtered and pre-warmed air on a segment-by-segment basis.
When coating interior surfaces, a longitudinal ventilation system is of course essential. In this case, the control system opens the ceiling air inlets on one side of the cabin while closing the floor flaps on the other side of the cabin. An additional Venturi nozzle located at the pipe entrance supports the flow of air inside the pipe. Our proven impact separator extracts the contaminated air emitted from the workpiece. The impact surfaces collect and retain as much as 70% of the particulates in the exhaust air. The coating mist passes through a downstream filter, bringing the over filtration efficiency to 97%. The two-stage cleaning system results in a filter mat service life that is significantly longer than that usually possible in conventional grated-floor systems.
To facilitate the drying process, the cabin is placed in a zero-pressure state and switched to re-circulation mode. Only a portion of the airflow -- amounting to 5 to 10% - is replaced by fresh air during solvent removal. The drying temperature in the cabin is now about 50° C.
In an adjacent part of the hall, a free-hand coating station was installed to accommodate workpieces with a wide range of dimensions. The ten long-range nozzles were installed here in a way that preserves the full functionality of the indoor crane. The useful ventilation-related area here measures 14 x 7 meters. Depending on the workpiece, four sections can be activated. The pre-warmed fresh air reaches the coating technician in a precisely targeted way and removes the contaminated air from the hall. The flow behavior has been calculated in such a way that the air volume of 50,000 m3/h is circulated in an extremely small space, leaving the adjacent workstations completely unaffected. The in-floor extraction system implemented here also uses the heavy-duty impact separator developed by us.
Негізгі бет Ғылым және технология SLF Oberflächentechnik GmbH at SIAG Czech Republic - English
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