Vaporisation System for Hydrogen Peroxide-Air Mixtures
For sterilisation and room decontamination processes in the food and pharmaceutical industries, hydrogen peroxide is primarily used. Due to its strong oxidative effect and the formation of radicals, hydrogen peroxide has a very high kill rate for the complete spectrum of microorganisms.
For this purpose, an aqueous solution of hydrogen peroxide is used, which is supplied to a sterile carrier air flow in the form of finely atomised micro droplets. The resulting aerosol is introduced into an evaporator heated to > 200°C, where it is transferred into the gas phase and transported to the site of action.
As hydrogen peroxide tends to break down into water and oxygen in particular in highly concentration solutions under the effects of light and water when in contact with metal surfaces, the challenge is to maintain an almost uniform concentration of the mixture until it reaches the site of action.
In order to limit catalytic disintegration, stabilisers are added to commercial hydrogen peroxide solutions, causing severe contaminations of the evaporators used so far. This requires maintenance and cleaning processes that are time-consuming and costly.
In addition, the process requires consistent steam quality without the formation of droplets or condensates, because otherwise the product to be treated can contaminated with hydrogen peroxide and rendered unacceptable.
These challenges inspired us to develop our novel vaporisation system PeroxEvaporator.
Design and function of the PeroxEvaporator
Using our multiphysical simulations, the current design of the evaporator emerged from an iterative development process.
The evaporator consists of an inner part with a flow channel and a cylindrical outer sheath. Both components form a sealed press fit during the hot operating state, but can be separated for cleaning purposes after cooling.
The aerosol enters the evaporator at the upper end and is introduced into the flow channel. The channel design allows evaporation over a long channel section. This allows the aerosol to warm up slowly, resulting in a reduced deposition of stabilisers at the channel surface.
The up-and-down channel layout ensures thorough mixing of the aerosol and prevents droplet formation.
The constructive design of the outlet side releases H2O2-containing steam in an eddy current, resulting in good distribution and thorough mixing as well as optimal flow conditions of the medium.
An overall small design of the evaporator allows the formation of the H2O2 steam near the site of action and shows high energy efficiency at the same time.
Advantages at a glance
The PeroxEvaporator is patented under publication number DE 10 2017 215 200.