Materials in Pilot-or Full-Scale Applications

In full-scale applications very fast corrosion (formation of holes over the course of weeks, especially at improper welds) has been observed in off-gas piping, even when made from stainless steel. The problem is most evident when aerosols, for example containing chloride, escape from the reactor into the pipes where they form a very corrosive wet film. But corrosion may also occur in stainless steel pilot or full-scale reactors, especially when treating waste waters. Such reactors are best made of stainless steel because of the possibility to operate them at elevated pressures, e. g. 200-600 kPa, which can readily be achieved with commercially available ozone generators (Masschelein, 1994). 

PVC is a very inexpensive material that can be used for lab-scale ozone reactors, however, it is slowly but progressively attacked by ozone. Bubble columns or tube reactors can easily be constructed from PVC tubes. Generally, gas tightness is best achieved by welding, but it can only be operated at ambient pressure (Pabs =100 kPa). Its use in full-scale applications has seldom been reported (see Table A 3-5). 

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