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Contenido archivado el 2022-12-27

PRODUCTION OF AMMONIUM NITRATE WITHOUT EXTERNAL HEAT CONTRIBUTION AND WITH GENERATION OF PURE STEAM

Objetivo

To demonstrate the feasibility of a new process for ammonium nitrate production by reaction between nitric acid and ammonia. It is foreseen that this process will not require external heat contribution and will allow a particularly high nitrogen efficiency (more than 99,8%). It is also forecast that it will provide solution to problems caused by liquid and gaseous effluents in this kind of production : there will be no gaseous effluents, and the greatest part of the liquid ones are recovered in a sufficiently pure from, to be utilizable as process water in other production units.

The project was to be operated in the amonium nitrate production plant of the firm UCB in Ostende (Belgium). The nitric acid, previously preheated up to 100 C is reacted with liquid ammonia, previously evaporated, in a pressure reactor (3 kg/cm2) effective. An 80% ammonium nitrate solution, at a 180 C temperature is obtained. A part of reaction heat causes a part of the water which dilutes nitric acid to evaporate in form of steam polluted by some entrained ammonia and ammonium nitrate, which correspond to a 0,5% of the overall nitrogen in the system which is lost. The ammonium nitrate solution is condensed by vacuum evaporation up to a final 95% concentration. A boiler, which is incorporated in the reactor allows the heat excess of the reactor to be turned into pure steam at a 5 kg/cm2 effective pressure.
The steam produced in the reactor is treated in a counterflow washing column where a water ammonium nitrate solution with a light controlled nitric acid excess, which has to absorb free ammonia, is used. Nearly all the ammonium nitrate entrained by the steam is eliminated by this treatment, as the steam produced after this depuration phase, contains only 0.1 % of nitric acid and 0.1 % of ammonium nitrate (concentrations are, before treatment, 0.35 % and 0.70 % respectively). The ammonium nitrate concentration for the solution allowed to circulate in the washing tower has to reach 60 % to make it possible to recycle to reactor without an excessive additional energy consumption. The steam after having been purified is used to preheat nitric acid and boiler water and to heat the vacuum evaporator. It will be possible to reach for each operating condition, a stable equilibrium condition so that the steam excess is null and that all the heat excess of the process is turned into pure steam at 5 kg/cm2 effective pressure. Gaseous effluents will not be produced because there will be no excess of steam. Condensate will contain only 0.1 % nitric acid and 0.1 % ammonium nitrate concentration and will be directly usable for other processes for example nitric acid synthesis.
The washing tower and the connected devices to be installed in Ostende would allow to produce 165 tonnes a day ammonium nitrate and free ammonia polluted steam. The production capacity of the unit would be 220,000 tonnes of 100 % ammonium nitrate per year. Energy saving attainable per year are thought to be the following ones :
Ammonium nitrate 410,6 TOE per year
Nitric acid (to be subtracted) 143,6 TOE per year
Pure steam 144,3 TOE per year
Overall energy savings 411,3 TOE per year
Water saving per year is estimated to be 1,200,000 FB.

Convocatoria de propuestas

Data not available

Régimen de financiación

DEM - Demonstration contracts

Coordinador

UNION CHIMIQUE BELGE SA
Aportación de la UE
Sin datos
Dirección

Bruxelles
Bélgica

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Coste total
Sin datos