Innovative Ammonia Control - Case study


Courtesy of Catalytic Products International (CPI)

Ammonia has increasingly become more of a regulatory concern. Ammonia emissions into the atmosphere have been linked to the formation of fine particulate matter, while ammonia emissions in wastewater are restricted because of the negative affect the chemical has on rivers, lake, and aquifers.

Many sources of biofuels contain ammonia or can create ammonia during processing.

The following case study describes how Catalytic Products International solved an ammonia discharge problem for a leading refinery.

The Problem
A wastewater stream in a bio-refinery contained significant amounts of ammonia, Volatile Organic Compounds (VOC) and mercaptans. The water had been used in the facility’s boiler trains. The corrosivity of the wastewater was damaging the boiler trains, resulting in unplanned outages and costly repairs. Management decided another means of treating the wastewater stream was required; one that ensured the contaminants were destroyed and that offensive odors associated with the waste stream were eliminated.

Further, the new control system needed to be simple to operate and both capital and O/M costs should be minimized. Further complicating the application is the fact that gaseous fuels were not available at the facility.

Accordingly, the only energy source that could be used was electricity.

The Solution
Catalytic Products International designed a unique, integrated solution that started with a countercurrent stripping tower to remove VOC, ammonia, and mercaptans from the wastewater stream. After stripping, the gases flow into a custom-designed, electric catalytic oxidizer. A special catalyst that oxidizes both VOCs and ammonia is used. VOCs are converted to carbon dioxide and water, while some – but not all – of the ammonia is converted to nitrogen oxides (NOx).

The exhaust gas stream is then directed to a second catalyst. Residual ammonia and NOx react on the catalyst surface to form elemental nitrogen (N2) and water. Thus, both ammonia emissions and NOx emissions are minimized. Both catalyst beds are protected from sulfides (which accompany mercaptans and which can damage the catalysts used) through the use of a disposable “guard bed” that precedes the two catalysts.

The system met all performance criteria. The wastewater stream met local discharge requirements and the exhaust gas from the process met all permit and regulatory limits. Further, objectionable odors were eliminated. As ammonia discharges continue to attract the attention of regulators and policy-makers, these kinds of innovative solutions will become even more important as bio-fuel markets grow.

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