Preventing sulfide contamination in the brewery

Prior to filling, beer bottles are purged with CO₂ to remove air and protect the taste against oxidation. In the fermentation process, yeast consumes sugar and expels a large amount of CO₂, which can be reclaimed and used for this bottle purging purpose. Unfortunately, fermentation often also produces toxic, odorous sulfides that can foam up into the piping and contaminate the reclaimed CO₂.

In order to continue using the great resource of CO₂ by-product yet avoid contaminating the bottled beer with foul-smelling toxins, the reclaimed gas is run through sulfide removal skids. However, sulfide breakthrough can occur if the gas does not spend enough time in the scrubber. Employees are sometimes tasked with sniff-testing the reclaimed CO₂, but this is an unhealthy practice and is too discrete to vigilantly prevent product contamination. An automatic, continuous analysis solution is required in order to immediately divert contaminated CO₂ from use in bottling as well as provide feedback control for the sulfur removal processing time.

The Applied Analytics OMA Process Analyzer can be used to continuously measure concentrations of hydrogen sulfide (H₂S) and dimethyl sulfide in the fermentation by-product gas. This system uses a full-spectrum UV-vis spectrophotometer to detect the absorbance of sulfides in the reclaimed CO₂ stream, an ideal method as CO₂ has zero absorbance in the UV spectrum. The OMA provides fast-response alarms to high-concentration threshold, which allows immediate diversion of contaminated CO₂.

For this application, the OMA is typically multiplexed to automatically cycle analysis between multiple sampling points. This maximises system value by allowing one unit to monitor the raw fermentation gas entering the reclamation system, gas coming off the acid aldehyde scrubbers and the bottling gas coming off of the sulfur removal beds - all with sample stream switching at user-defined intervals.

Using the OMA system, a brewery enables intelligent CO₂ reclamation which continuously prevents sulfide contamination of the beer product.