Ammonia injection proves effective and inexpensive means for reducing nitreous oxides (NOx)emissions for preheater or long dry kiln processes and other waste incinerators.....
Because of environmental and safety concerns Anhydrous ammonia is being replaced with the more friendly Ammonium hydroxide or Aqua Ammonia solution 15-29% concentration or liquid urea solution.
In majority of applications 19% Aqua ammonia has proven to most cost effective.
In remote locations, melting of urea prills and conversion to urea solution is also acceptable.
In most utility applications and other waste burning installations having lower stack temperatures, the urea solution is more economical but it is further converted in a batch reactor into ammonia gas which is further mixed with air and then injected into the gas stream.
The batch process is economical as it produces only the required ammount of ammonia gas without additional storage and handling facilities.
For emissions control in the cement industry, the solutions may be injected into the Calciner exit duct.... or kiln duct riser....or directly into the kiln...