Vapor and liquid flow control for aseptic packages

One of our customers, a manufacturer of food packaging equipment, was looking for a solution to supply hydrogen peroxide in into their aseptic sterilization process of food packaging. As a solution, Bronkhorst supplied multiple vapor-generating systems consisting of liquid flow controllers, gas flow controllers and a temperature-controlled mixing and evaporation device. 

Food products are often sterilized as a final step in the process. In aseptic sterilization the foods have been sterilized outside the packaging. This can be done by steam sterilization. After that, the foods are placed in the aseptic packages that have been sterilized previously in a separate way. The last step is sealing the packages under sterile conditions.

Vapor solution for aseptic packages

The solution consists of two Bronkhorst vapor-generating systems (CEM - Controlled Evaporation and Mixing systems) - one side for PET bottles, cartons or pouches and another side for caps. The hydrogen peroxide (35% H₂O₂ in water) is injected as a vapor for better concentration control. The vapor condenses at the inside surfaces of the packaging, where the H₂O₂ in the liquid phase performs its sterilizing action. In a subsequent drying step, the condensate is removed using hot air supplied by a gas mass flow controller, after which the dry and aseptically sterilized packaging is ready to be filled with liquid or cream.

The vapor-generating CEM systems each consist of a liquid mass flow controller (thermal LIQUI-FLOW or Coriolis-based mini CORI-FLOW), a EL-FLOW Select mass flow controller for air as a carrier gas (and for drying afterwards), and a temperature-controlled mixing and evaporation device. 
The hydrogen peroxide is dosed accurately in the range of 200 (for caps) to 2000 (for cartons and pouches) g/h of H₂O₂ solution, and the flow of drying air is typically around 100 l/min. The liquid, gas and temperature controllers communicate easily with PLC’s for an optimum integration in the customer’s systems. 

Alternative: Coriolis based liquid flow controllers

As an alternative, use of the mini CORI-FLOW flow controller has the advantage that - in addition to its medium-independent mass flow - the density of the dosed medium is measured. As hydrogen peroxide will eventually decompose into water and oxygen, the physical properties of the dosed H₂O₂ solution are not constant over time. Therefore, this device is able to monitor the concentration and, hence, the quality of the hydrogen peroxide dosing. 

Due to the fact that hydrogen peroxide is injected in a controlled way so that not too much will be supplied, the costs of this sterilizing agent are reduced. Using this solution, the aseptic sterilization process is well-monitored and traceable, contributing to the extension of the shelf-life of food products.