Table of Contents
Influence of temperature on the filter cake resistance in a lauter tun
M. Hennemann, M. Gastl and T. Becker
High temperatures are maintained in a lauter tun to reduce the filtration time. The temperature affects the flow rate through the changing viscosity. In addition, the sedimentation behaviour of the particles also depends on the temperature. Changes in the settling velocity are assumed to affect the filter cake resistance and thus the flow rate. The influence of temperature (range: 40 - 78 °C) on cake formation was investigated. Calculations of the settling velocity revealed a higher settling rate at higher temperatures due to a reduction in the density and viscosity of the liquid. The effect was confirmed for larger particles by performing a sedimentation test, but smaller particles were hindered from settling at higher temperatures. Fine particles remained in suspension because of thermal convection, providing buoyancy to counteract the gravitational sedimentation. The hindered particle settling explained the lower filter cake resistance at high temperatures and thus the higher flow rate.
Descriptors: filter cake resistance, lautering, sedimentation, temperature, viscosity
BrewingScience, 74 (July/August 2021), pp. 100-106
