ProTect

The consistent dewatering performance of a press felt is the basis for permanently high paper quality and machine efficiency. Contamination or wear reduce felt performance. In a worst case scenario, a highly stressed felt can tear and cause an unscheduled shut down with the associated machine damage. To avoid these problems, paper manufacturers measure the condition of the felts at regular intervals, focusing above all on felt moisture and permeability. Any irregularities identified during such measurements indicate age-related wear or defects in the felt. On the basis of this data, service technicians can accurately predict the remaining service life of the felt.

However, the problem with this is that this kind of measuring work is generally done manually with the machine running. In addition, the felt supplier's service technicians or the mill's own machine operators are often working in areas of the machine where they are exposed to a relatively high safety risk. If the felt tears during the measurement there is an immediate risk of injury. In the event of an accident, the consequences for the individual affected, but also for the plant operator, can be serious. For safety reasons many companies and legislators have meanwhile banned manual measurements.

In the case of compact machines like those used for tissue production there is another problem, because measuring points are often hard to reach or not accessible at all. This makes it harder to obtain reliable data about the condition of the felt.

Nevertheless, these measurements are an extremely important tool for paper manufacturers to ensure efficient production, so abandoning them is not an option. Voith's ProTect system therefore offers a safe alternative to manual measurements. ProTect consists of a carriage and the desired number of cross-beams in stainless steel. For the measurement as such the paper manufacturer only needs one carriage. This means that measurements can be taken at various measurement positions at no extra cost. This reduces the investment in the system. One advantage is that ProTect can be used with all commercially available manual measuring devices from different manufacturers. The scope of supply of the system includes various adapters.

In countless paper machines worldwide ProTect is already delivering reliable data. At paper manufacturer UPM, for example, where the system is used at several production sites. The improved workplace safety was the main deciding factor, explains Rainer Eichner, General Production Manager at UPM Schongau, adding: “Workplace safety is always our priority. We systematically rule out avoidable risks. With ProTect we can carry out press felt measurements safely and reliably at various points in the press section, even in areas that are difficult to access.”

The UPM mill in Schongau was the first site within the company to use the Voith system. Initially, four felt locations were equipped. The results of this one-year test phase were impressive, so another seven locations at various machines in Schongau were fitted with the cross beams. At every measuring point the measuring device is used once or twice a week. And the positive experiences were also passed on within the UPM Group. Meanwhile, four UPM sites in Germany and another in Austria are using ProTect. Worldwide, more than 100 measuring positions are in operation on around 50 machines. The results are consistently positive. To date there has not been any accident on account of a felt tear, so it is hardly surprising that there is growing demand for the system.

Another reason for the success of ProTect is that it is easy to use. This not only virtually rules out incorrect measurements but is also an additional safety factor. As soon as the operator has secured the measuring device in the rail of the cross beam all they have to do is press a button. The carriage and measuring device travel automatically at a steady speed to the end of the cross beam and back. Alternatively, the service technician can also control the system remotely. The stainless steel cross beams can be installed at locations that are not accessible for manual measurements. There is even a lot of flexibility in respect of the angle of installation, which increases the number of possible measuring points and provides the analysis on a broader range of data. As a result, more accurate predictions can be made about the remaining service life of the felt.

On request, Voith can also adapt the ProTect system to the precise needs of the customer. For a Swedish paper manufacturer, for instance, two positions can be measured using just one cross beam. This gives staff better access to the machine during maintenance works. The longest cross beam supplied to date is 12,45 meters long and is ensuring more safety at a paper mill in southern Germany.

An additional benefit of the semi-automated measurement is that ProTect supplies more accurate data than manual monitoring, which cannot always be carried out consistently due to different modes of operation. In new machines supplied by Voith all the necessary connections for installing a ProTect system are already provided. This cuts the installation time in the event of a retrofit. In addition, ProTect is designed so that upgrades can be readily integrated, because Voith is continuing to refine the safety system and is already working on modules that will extend the range of applications for it.