Smooth lauter speed adjustment
Measuring 8.6 m in diameter and weighing close to 21.5 t, the lauter tun is the heart of the brew house. The liquid and solid parts of the mash are separated in a fully automated process. As the spent grain settles on the floor of the vat, it forms a natural filter layer. A special raking machine loosens this layer in order to ensure an optimum flow of the beer wort. Thus, the wort quality improves and raw materials are used efficiently. Pressure sensors at the bottom of the vessel detect the spent grain’s consistency, and the drive adjusts the machine’s speed accordingly. This intelligent control system enables flow rates between 9 and 14 liters per minute and square meter. Next, the spent grain is removed: the machine is gradually lowered and the flat bars mounted on its six arms push the spent grain out of the tun through a hatch. This step is also fully automatic. If too much mass accumulates, the lowering process stops, and the speed is adjusted. Thus, the tun can be emptied in as little as six minutes. In order to process the material as gently as possible, the spent grain is loosened at a low speed. But when the spent grain is removed, high speeds are required so the vessel can be emptied as quickly as possible. Thus, the clouding of the spent grain is minimal, and the flow is very efficient. To check whether the system is running smoothly, the speeds, current consumption, and the motor temperature are centrally monitored continuously. Both tasks are handled by a custom-tailored NORD drive unit based on a splined hollow shaft. The drive is a combination of a motor, an industrial gear unit, and a helical bevel gear unit. It has a maximum torque of 96,000 Nm and can continuously regulate the circumferential speed from one to one hundred meters per minute – while providing a constant torque.