The results obtained show that it is possible to reduce the ammonia emission by using the ammonia abatement system based on urea-formaldehyde (UF).
The system is sensitive to the type of urea-formaldehyde (UF). Free formaldehyde is the active component. If not easily available due to a too stable molecular structure, the efficiency will be lower. The maximum possible efficiency we found
was a reaction of 40% of the free formaldehyde.
The ammonia abatement system is cost free. All the ammonia reacted with formaldehyde to hexamethylene tetramine is recycled to the pre-evaporator were it decomposes again to formaldehyde and ammonia. The formaldehyde is then used
as the standard urea additive.
Methods of analysis should be discussed among parties and confronted with those of the actual plant site and the external surveyor prior to final process design.