U2A™ is an innovative, patented system (US Patent No. 6,077,491, and others issued and pending) which generates ammonia on-site for use as a reagent in various processes, especially utility SCR and SNCR systems, etc.
Both anhydrous and aqueous ammonia have been classified by the EPA as regulated toxic substances. Hazards from exposure vary from minor discomfort, to toxic poisoning and asphyxiation. Therefore ammonia restrictions, or even prohibition laws in some areas, have been enacted by local authorities. Sometimes these measures are put into place after other ammonia storage and delivery systems are installed, forcing the end user to replace the entire system.
To counter this risk and improve the safety for plant personnel and the surrounding community, Hamon offers a Urea-to-Ammonia system, U2A™, that produces ammonia by a method that avoids the hazards of ammonia transportation, transfer, and storage. In addition, there are economic benefits versus using unregulated lower concentrations of aqueous ammonia.
In the U2A™ urea to ammonia system, urea (considered a benign chemical) is transported to the site in either dry or solution form, or as urea liquor (the purest urea form available) and mixed with water to form a 40-50% aqueous solution for processing.
This solution is then fed to an in-line reactor vessel constructed in 316L stainless steel. In the hydrolysis reactor, heat from condensing stem or electric heaters is applied to the reactor solution which supports the overall endothermic hydrolysis of urea to form ammonia.
The reactor is designed so that throughout the operating range of a particular application the temperature range is typically 280-310°F (138-154°C). The heat input is controlled to maintain an essentially constant reactor gas pressure within this temperature range, or alternatively to allow pressure to follow temperature. The gas pressure provides the driving force for the delivery of ammonia gas to the downstream SCR or SNCR process. The urea to ammonia conversion rate is exponentially proportional to the temperature of the reactor solution. As ammonia demand varies, the heat is controlled to maintain the reactor pressure within its control parameters.
The product gas is a mixture of ammonia (NH3), carbon dioxide (CO2) and water vapor (H2O) and is especially suited for utility SCR or SNCR applications, but may be considered for any application where ammonia is required.
The U2A™ ammonia generation system provided exceptional turn down (better than 20/1), minimal ammonia inventory, and safe, reliable operation. U2A™ systems are in place on more than 15,000 MW of utility NOx control systems in the U.S. and in Europe.