The U2A® Process - A Safe Alternative to Hazardous Anhydrous and Aqueous Ammonia

WAHLCO’s Urea to Ammonia (U2A®) generation system is a patented process that effectively converts urea to ammonia on site “on demand” and eliminates the transportation, transfer and storage of significant volumes of toxic ammonia.

The U2A® System basically reverses the process used to make urea. A urea solution is fed into a reactor, where it is heated under pressure to decompose to a gas mixture of ammonia, carbon dioxide and water vapor. This gas mixture is then piped to the point of use.

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The U2A® Advantages

The WAHLCO U2A® Urea to Ammonia system offers a process driven supply of ammonia eliminating the dangers and costs associated with the transport and bulk storage of ammonia on site. A readily available commodity, Urea is non-toxic, stable, non-flammable, and is not subject to regulations governing toxic or hazardous materials.

Original, safe, reliable and cost effective:

  • WAHLCO has the most urea to ammonia experience than competitors.
  • The system is much easier and less expensive to permit.
  • Urea based ammonia systems ELIMINATE the possibility of transportation related ammonia spills, liability and costs.
  • Process converts urea to ammonia on site.
  • Produces ammonia on demand.
  • Aqueous ammonia is significantly more expensive to operate than a urea based ammonia system. Based on capital cost + 5 years operating life, 19% aqueous ammonia costs are nearly 20% higher than those of the equivalent urea based system.
  • Low Energy consumption and cost – uses low energy steam.
  • Complete Conversion of Urea to Ammonia.
  • Rapid load following.
  • One unit can supply multiple boilers.
  • Equipment redundancy.
  • Urea contaminants removed by blowdown.
  • Hydrolysis completely converts to ammonia — No impact on SCR NOx efficiency
  • Hydrolyzers from 6 to 3500 lb/hr ammonia
  • Equipment fabricated and custom built in WAHLCO’s own shop.
  • Achieved ISO 9001:2008 Certification February 2012.

The U2A® Design Features

  • No natural gas needed
  • No vaporizer nozzles
  • Electric and steam heated models
  • DCS integrated and simple process control
  • Skid mounted-modular equipment
  • Highly reliable–catalyst free operation
  • Patented process*
  • Complete conversion of Urea
  • Quick response to load variations
  • No carryover to SCR
  • No catalyst contamination
  • Quick ROI and lower operating costs (vs Aqueous Ammonia)

*Covered by U.S. patents 6,077,491; 6,322,762; 6,436,359 and 6,506,350; European and Asian patents issued or pending

How Does U2A® Work?

  • Urea is dissolved in deionized water
  • Solution of 40-50% urea is pumped into a heated in-line reactor at a controlled flow rate
  • Equilibrium conditions are maintained in the reactor
  • Reactor produces a gaseous mixture of ammonia, carbon dioxide and water vapor
  • Simple control of pressure, reactor heat and liquid to meet process dynamics
  • Reactor off-take gas is further diluted with air
  • Same mass and volume flow rates at the AIG

Typical U2A® Process

Applications and Markets

To date, WAHLCO has supplied over 35 U2A® units with capacities ranging from 6 lb/hr to 3500 lb/hr of ammonia production. Most of these units are installed at coal fired power plants to supply ammonia to a Selective Catalytic Reduction system to reduce Nitrous Oxide emissions or for Selective Non Catalytic Reduction processes.

Other applications include SCRs at refineries, paper plants and other industries. The systems have also been installed to supply ammonia for Flue Gas Conditioning.


  • SCR-Selective catalytic reduction
  • SNCR-Selective non-catalytic reduction
  • Flue gas conditioning


  • Power generation
  • Refineries
  • Boilers-incinerators
  • Cogen facilities
  • Universities
  • Hospitals
  • Waste to energy/biomass
  • Cement plants
  • Pulp & paper
  • Mining
  • Waste water
  • HRSG

Power generating plant operating since 2000

Electric U2A® System

Steam Headed AFCU Skid