A spark ignition internal combustion engine performs ignition within a fixed ignition crank angle range. This allows continual monitoring of the state of the paper production process andor its energy efficiency combined with efforts to develop the manners of running the paper machine and its dryer section in a more favourable direction. At least the first section has a dedicated first measuring device for measuring a web tension of the printing material web in the first section. A drain is located in the bottom of at least one of the catch pans.