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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  |  VIEW ARTICLE

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

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