Online analysis of hydrogen sulfide and ammonia - help

[Dirtwater]

Wet chemical scrubbers are used to treat foul air (primarily ammonia and hydrogen sulfide) emitted throughout a wastewater treatment plant. Currently utilise electrochemical sensors to provide continual online monitoring of ammonia and hydrogen sulfide.

The sensors are not used for control purposes. The sensor data is used for monitoring concentration trends and to provide alarms for the operators. The alarm set points are; High NH3 - 10ppm, High High NH3 - 15ppm, High H2S - 75 ppm, High High H2S - 100 ppm.

Having concerns with the long term reliability of the sensors. Two major concerns are build up of condensate and the interference of sulfide with the ammonia sensors.

Has anyone experienced similar concerns or suggest alternative methods for continual online analysis of ammonia and hydrogen sulfide.

Cheers

 

[dicksewerrat]

Test the sensors twice a year by using a handheld monitor. There are probably some at the plant for confined space entry. Also contact the manufacturer for ideas, and/or maintenance schedule. Check NIOSH for OSHA limits on exposure to make sure you are not out of compliance with OSHA.