Wort Stripping: An Innovative Option for the Controlled Reduction of Unwanted Aromatics Featuring Optimised Trickle-Film Formation and Stripping Gas Utilisation
MBAA TQ doi:10.1094/TQ-48-2-0420-01 |
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Roland Feilner. Krones AG, Research and Development.
Abstract
There is a huge variety of different wort
stripping systems on the market at present, utilising highly disparate
technologies in order to reduce the amount of unwanted aromatics such as
dimethyl sulphide (DMS), which are formed post-boil primarily during the
whirlpool rest period. Many of these systems achieve the desired reduction
by generating large surface areas in the form of thin-film stripping.
These processes are integrated in the copper, a separate tank or directly
in the whirlpool. In this way, the reduction in free DMS is currently
running at approximately 40%. Other vendors utilise pressure reduction or
thermal end-treatment. A new concept featuring a reduced footprint, easy
retrofit options and without the use of vacuum or thermal energy is
described below. The innovative design enables the entire internal surface
area of the external stripping tank to be covered with an even, turbulent
trickle film. Besides generating an efficient, uniform and turbulent
layer, a stripping gas control function is provided for maintaining the
driving gradient between the gas and liquid phases and for influencing the
quantity of the substances to be expelled. This allows a DMS reduction
rate of up to approximately 70% to be achieved.
Keywords: dimethyl sulphide, DMS, thin film
stripping, whirlpool, wort stripping
S�ntesis
Existe una gran variedad de m�todos para el
�stripping� (eliminaci�n de vol�tiles), utilizando tecnolog�as muy
dispares para reducir la concentraci�n de arom�ticos indeseados (dimetil
sulfuro, DMS, por ejemplo) formados despu�s de la cocci�n, en el descanso
en el whirlpool. Muchos de estos sistemas consiguen la reducci�n deseada
mediante la generaci�n de grandes superficies en la forma de �stripping�
en capa fina, bien sea integrado a la paila de cocci�n, en un tanque
separado o directamente en el whirlpool; se consigue una reducci�n de
cerca de 40 % del DMS libre. Otros fabricantes utilizan una reducci�n de
la presi�n o un tratamiento termal final. Aqu� se describe un nuevo
concepto dejando una �huella� menor y opciones f�ciles de modificar, sin
utilizar el vac�o o energ�a t�rmica. El dise�o novedoso permite que se
cubra totalmente la superficie interna del tanque externo con una capa
muy ligera, uniforme y turbulenta. Adem�s de generar una capa uniforme,
turbulenta y muy eficiente, se tiene una funci�n de control del gas de
arrastre para mantener constante el gradiente motriz entre las fases
l�quida y gaseosa, controlando as� la cantidad de vol�tiles expulsadas. De
esta manera se consigue una reducci�n de hasta 70 % del DMS libre.
Palabras claves: Arrastre en capa fina, dimetil sulfuro, DMS,
�stripping� de mosto, whirlpool
