Pasteurisation is a heat treatment with the purpose of improving the microbiological stability of the beverage in order to prolong its shelf life. While reducing the number of harmful microorganisms, uniform and gentle treatments are required to maintain the original taste and appearance of the beverage.
The cold beer enters the regenerative zone of the plate heat exchanger and is gently pre-heated by the already pasteurised product. In the heating zone, the beer is then heated up to the request pasteurisation temperature and held in the holding tube during the requested pasteurisation time. The pasteurised beer is then cooled down in the regenerative zone and if required, cooled in the cooling zone to the requested filling temperature. The regenerative zone counts up to 96% of the heating and cooling demand and makes the system run at the most economical costs.
A frequency-controlled pump at the inlet of the heat exchanger regulates the flow, while a second pump between the regenerative and the heating zone raises the pressure up to 14 bar in order to keep the CO2 in the liquid. A back pressure valve at the outlet of the heat exchanger and a pressurised buffer tank make sure that constant pressure is maintained in the system and no CO2 is lost.
Flash Pasteurisation is typically installed in front of the filler and the filler speed often varies considerably. To keep the required pasteurisation units (PU) within tight limits, DENWEL uses intelligent control in combination with a buffer tank, capable to match variations in filler demand. If the filling capacity decreases, the flow has to be reduced, too.
Lower flow means longer holding time and therefore the pasteurisation temperature has to be decreased to keep the same PU. The system reduces the flow according to the heat exchanger temperature characteristics and increases the level in the buffer tank. When the filling capacity increases again, the level in the buffer tank will be lowered and the nominal pasteurization values will be re-established. This way any over- and under-pasteurisation can be avoided and gentle and consistent treatment is guaranteed.