The AMNIT process for production of concentrated ammonium nitrate solutions combines high thermal efficiency, low maintenance cost, optimal environmental compatibility and operating safety. The reaction of ammonia with nitric acid occurs, without production of any process vapour, in a pressurized recycle flow loop. The recycle solution, in which a slight amount of free ammonia is maintained, supplies heat to the various exchangers of the loop, for the final AN concentration to 97.5% which is suitable for the major part of granulation processes. The free ammonia in the production off-take is neutralized before pressure reduction and subsequent concentration steps. A specific feature of the AMNIT process is the self-regulating auto-thermal pre-concentration step. No external heat supply is required. The high thermal efficiency is combined with ease of operation and low maintenance. Efficient pH controls achieve a liquid effluent with the most stringent conditions of pollution control.
All the significant features and benefits of the original CARNIT process, which started up in 1990 have been maintained: absence of corrosion, low maintenance cost and high on stream times of 99+%,for a capacity of 2750 tpd in a single process line. The production rate can be varied between 30% and 100% of design capacity.
This paper has been presented during the Asian Nitrogen & Syngas Conference 2013 in Singapore.