Measurement of Foam Height in Cylindroconical Fermenters using a Laser-Based Distance Sensor

Osamu Ogane, F. Yokoyama, T. Katsumata, Y. Tateisi, and I. Nakajima. Poster presented at the MBAA 111th Anniversary Convention, Minneapolis, Minnesota, September, 1998.

Abstract
Determination of the maximum foam height produced during fermentation is a prerequisite for a fermentation tank design and is also necessary to set the fermenter free head space when a difficult set of brewing conditions is used. We have developed a device for the continuous and accurate measurement of the distance between the foam and the top of the fermenter, thus making quantification of foam height possible. The standard type of non-contact devices, which use ultrasonic waves, were capable of measuring a sensor-foam distance of 30cm in laboratory-scale experiments, but were not suitable for determining a distance of several meters as required in the brewery. As foam absorbs acoustic wavelengths, we found it was possible to measure a distance of several meters to the foam using a laser-based sensor. This system has the following characteristics: The distance between the sight glass and the foam in the cylindroconical fermenter is measured by a non-contact device. It is possible to measure the foam height continuously during fermentation. It is possible to measure the foam height to an accuracy of millimeters. This device is fixed to the top of the sight glass to measure foam height. When used in the cylindroconical fermenters, it was found that the formation and disappearance of the foam and the maximum foam height could be measured.
Keywords: foam, fermentation, laser measurement  

Sintesis
La determinacion de la altura maxima a la que llegara la espuma durante la fermentacion es un pre-requisito basico para el diseflo de tanques de fermentacion y tambien es necesario para determinar el espacio libre que debe quedar en el tanque cuando se usan condiciones dificiles cerveceras. Nosotros hemos desarrollado un aparato para la medicion continua y exacta de la distancia entre la espuma y cl tope del fermentador, por to tanto haciendo la cuantificacion de la altura de la espuma posible. Los tipos estandard de aparatos sin contacto, los cuales usan ondas ultrasonicas, fueron capaces de medir una distancia entre sensor y espuma de 30em en experimentos de laboratonio, pero no fucron capaces de determinar una distancia de vatios metros come, es requerido en la cerveceria. Corno la espuma absorve ondas acusticas, nonotros encontramos que era posible medir distancias de varios metros en la espuma utilizando, un sensor de laser. Este sistema tiene las siguientes caracteristicas: 1. La distancia entre la mirilla y la espuma en cl fermentador cilindroconico es medida por un aparato que no hace contacto. 2. Es posible medir la altura de la espuma continuamente durante la fermentacion. 3. Es posible medir la altura de la espuma a una exactitud de milimetros. Este aparato esta fijado arriba de la mirilla para rnedir la altura de la espuma. Cuando es usado en los fermentadores cilindro?conicos, se encontro que la formacion y desaparicion de la espuma y la altura maxima de la espuma puede ser medida.