AS™–Series Ammonia Scrubber
Perma Pure Ammonia Scrubbers are designed to remove ammonia from a gas stream to protect the analyzer from clogging due to the formation of ammonium salts. Ammonia is a highly reactive gas. It is sometimes added to stack gases to reduce the nitrogen oxide content of the gases by conversion to nitrogen and water (the DeNOx process). When present in gas samples, ammonia will readily react with other components such as sulfur dioxide in the sample to form ammonium salts. This salt is relatively low-boiling, so it is present as a gas at the higher temperatures in the stack and in the heated line. When the sample cools down while passing through our dryer, it precipitates out as a solid, clogging the dryer or analyzer. For this reason, we recommend installing an ammonia scrubber inside our system to prevent damage to our dryers and to the analyzers downstream.
Principle of Operation
The Perma Pure ammonia scrubber consists of a polysulfone or stainless steel shell housing filled with a housing filled with a phosphoric based scrubbing media and inert ceramic burl saddles. The water vapor in the sample activates the scrubbing media to produce phosphoric acid. The phosphoric acid then reacts with the ammonia in an acid-base neutralization reaction producing a phosphate of ammonia. This compound is a solid even at elevated temperatures, and deposits immediately within the ammonia scrubber as a visible salt residue. For proper operation, the ammonia scrubber should be kept at a temperature above the sample dew point to avoid the loss of water-soluble analytes. For this reason, Perma Pure now offers a heated ammonia scrubber which can be placed in the sample path.
