Edge Dryers
A common problem on many paper and board machines is lack of drying capacity on the sheet edges. This may be just due to poor drying or more commonly, the sheet being run to the edge of the cylinders to maximise production. Whatever the cause, Compact Engineering has a solution available from their range of dryers that are capable of eliminating even the wettest of wet edges. The units are compact, yet powerful and are engineered to fit into the machine without interfering with normal machine operation.
Depending on the amount of water that needs to be removed and where on the machine the dryers are installed, the edge dryers consist of a frame with the appropriate number of emitters fitted to more than cover the width of the wet edge. The emitters will be controlled in 75mm or 150mm wide zones to allow the drying rate to refelct the variation in drying requirements. The emitters for light drying duties will be taken from the Apollo range. Where the drying duty is high due to the speed of the machine, the weight of the paper and the severity of the wet edge a Corona or a Titan dryer will be used.
The frames are fitted onto the paper machine framing using specially designed retraction equipment that pull the dryers away from the sheet surface, cooling to touch within seconds of switching off the power minimising the risk of fire.
Compact edge dryers will remove a wet streak of 3.5% above the set point down to the desired sheet moisture average. On heavy weight sheets it is advisable to dry the sheet evenly from both sides to avoid curl and this is easily achieved by installing edge dryers on the top and bottom cylinders.
Eliminating wet streaks using Compact edge dryers means that the paper machine speed can be increased as the sheet no longer needs to be over-dried to compensate for the wet edges. Increasing the machine speed and improving the product quality gives short payback times on invested capital.
