ammonium nitrate

Production of concentrated 99.8-wt % ammonium nitrate solutions. The Carnit Process, which requires no external heat supply, combines a high energy efficiency with ease of operation and low capital cost. The process can be optimized either to produce clean 5 bar steam for export, or to use a dilute nitric acid feed.

Description: Nitric acid and ammonia gas are reacted in a high-recycle flow system, where the operating pressure is kept higher than the vapor pressure of the solution. There is no production of process vapor. Temperature control is achieved by adjusting the recycle ratio and cooling the solution recycle flow in a series of exchangers. The hot recycle solution leaves the reactor at a temperature of 185-190℃ and flows first to the final concentration exchanger where it supplies the heat for production of the 99.8-wt % product solution. Other exchangers in the loop are the evaporator which produces the 95-wt % solution and a steam kettle for clean 5 bar export steam. The solution in the loop is kept slightly ammoniacal. The free ammonia in the production offtake is neutralized by a small additional nitric acid injection before pressure reduction. A specific feature of the Carnit Process is the self-regulating combination of the adiabatic flash upon pressure reduction with an isobaric concentration step where the flashed vapors supply the heat of evaporation. There is no gaseous effluent; AN content of the liquid effluent is of the order of 400 ppm wt. Energy selfsufficiency of the process can be achieved with a minimum acid concentration of 45 wt %; with higher acid concentrations export steam becomes available.

Raw materials and utilities per ton of AN 100%:

Electric power cooling water (ΔT = 10℃) B.F.W Steam 5 bar Effluent (condensate) Ammonium nitrate loss in effluent

1.85 18 133 127 523 0.2

kWh m 3 kg kg kg kg