Wort Boiling by Batch Rectification�Possibilities for Reducing Required Evaporation
MBAA TQ doi:10.1094/TQ-46-1-0208-01 |
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Dr.-Ing. Marcus Hertel (1,2), and Prof.
Dr.-Ing. Karl Sommer (2). 1. Hertel GmbH Constructiones Cerevisiae,
Gst�ttengasse 31, 5020 Salzburg, Austria. 2. TU M�nchen-Weihenstephan,
Lehrstuhl f�r Maschinen- und Apparatekunde, Am Forum 2, D-85350
Freising-Weihenstephan, Germany.
Abstract
Today, energy costs are very high and are predicted to rise further.
Because approx. 2,260 kJ is required to evaporate 1 L of wort (or its
water content), it is advantageous to reduce total evaporation during wort
boiling. The total evaporation required to achieve the target
concentration in cast-out wort is a property of the solution and is
determined by the vapor-liquid equilibrium of unwanted flavors in wort and
starting concentration in the kettle-up wort. Thus, total evaporation
cannot be reduced by existing wort-boiling systems, although this is often
asserted. It was theorized that the only way to possibly reduce the
required overall evaporation is by fractional distillation or
rectification. To test this theory, a new wort-boiling system was
constructed using the basics of evaporation and rectification. In this new
rectification wort-boiling system, a side stream of wort is constantly
drawn from the wort kettle and fed into a rectification column connected
to the kettle. Thus, the evaporating vapor and recirculating wort are in
direct contact, which concentrates unwanted flavors in the vapor. Because
of this, the discharged steam has a concentration of unwanted flavors that
is much higher than that produced by normal boiling systems. Test trials
were performed with the new wort-boiling system, and its evaporation
efficiency was determined. Results of the measurements showed that an
equal reduction of unwanted flavors was achieved with approx. 50% less
overall evaporation than that required by a normal wort-boiling system.
The evaporation efficiency, thus, was doubled. Using this new system, it
is possible to reduce the required overall evaporation during batch
processing of wort boiling by as much as 50%. If the boiling time is also
reduced, the resulting wort has lower thermal stress and a desirable wort
protein profile. The required rectification column can be added to nearly
any existing wort-boiling system.
Keywords: efficiency engineering, wort
boiling
S�ntesis
Los costos de la energ�a son hoy en d�a muy altos y se pronostica que
subir�n a�n m�s. La reducci�n del tiempo total de evaporaci�n del mosto
ser�a muy conveniente debido a que cada litro de agua evaporada consume
m.�.m. 2.260 kJ. La evaporaci�n total necesaria para alcanzar la
concentraci�n deseada del mosto final es una propiedad de la soluci�n y es
determinada por la concentraci�n inicial del mosto (paila llena) y por el
equilibrio de arom�ticos indeseables en el vapor y el l�quido, por lo que
la evaporaci�n total no puede ser reducido por sistemas de cocci�n de
mosto actuales, contrariamente a lo que algunos fabricantes sostienen. Se
ha dicho que en teor�a s�lo se podr�a reducir la evaporaci�n total
mediante una rectificaci�n o una destilaci�n fraccionada. Para intentar
verificar este supuesto, se construy� un sistema de cocci�n de mosto
usando los conocimientos b�sicos de la evaporaci�n y de la rectificaci�n.
En este sistema, se lleva una corriente parcial de mosto de la paila de
cocci�n para alimentar una columna de rectificaci�n conectada a la paila.
De esta manera se consigue que el vapor desprendido est� en contacto
directo con el mosto en recirculaci�n, lo que concentra los arom�ticos
indeseados en el vapor de manera que el vapor desprendido tenga una
concentraci�n mucho mayor de arom�ticos indeseados de lo que se puede
conseguir con un sistema normal de cocci�n. Se determin� la eficiencia de
la evaporaci�n del nuevo sistema de cocci�n. Los resultados demuestran que
se puede conseguir una misma reducci�n de arom�ticos indeseados con 50 %
menos evaporaci�n total que con sistemas convencionales de cocci�n, o lo
que es lo mismo, se dobl� la eficiencia de evaporaci�n. Este nuevo m�todo
hace posible reducir en hasta 50 % la evaporaci�n total necesaria en un
proceso por lotes. Esta reducci�n del tiempo de evaporaci�n reduce la
carga t�rmica a que se somete el mosto, impartiendo al mosto un perfil
proteico m�s deseable. La columna de rectificaci�n se puede adaptar a casi
cualquier tipo de sistema de cocci�n existente.
Palabras claves:
cocci�n de mosto, ingenier�a eficiente
