One of ammonium nitrate in the production process is the pressure and granulation
( A ) atmospheric pressure and three-stage evaporation in granulation
This process is the use of certain manufacturers , features are: raw dilute nitric acid concentration of 42 to 45% ( dilute nitric acid without preheating ) ; ammonia gas purity> 99% , preheated to 40 ~ 60 ℃ and in atmospheric pressure. carried out , the outlet concentration and 64 % or higher, the temperature of 115 ~ 125 ℃. evaporator section at 40 ~ 140MM Hg to 0.2kg/cm2 in the steam heating and evaporation , after some evaporation , concentration of up to 78 ~ 85% Sec evaporator under atmospheric pressure and evaporated to 4 ~ 8kg/cm2 steam heating, the secondary evaporator , the solution concentration of 90 to 92 %. In the three sections of the evaporator 140 ~ 240mm Hg to 8kg/cm2 steam heating, the solution evaporated to a concentration of more than 98.2% . By centrifugal spray granulator in spray granulation tower granulation . Then , by the belt conveyors in the transport process of cooling , the final weighing and packaging.
One , three stage vacuum evaporator generally use electric pumps, and a condenser and attachments atmosphere .
( B) the pressure in the evaporation and granulation period
This process is characterized by :
1 , and in the system : the ammonia gas is preheated to a temperature above 80 ℃, dilute nitric acid concentrations above 53% , and the operating temperature 135 ~ 140 ℃, and using the partial thermal evaporation , and the outlet concentration of up to 85 ~ 95 %.
Ammonia gas pipeline is equipped with automatic pressure regulating device , and in the use of PH or acidity, automatically adjust the feed amount of acid .
2, the evaporation system : film evaporator 85 and ~ 95% of the loaded solution was pumped to the prilling tower , and evaporated to 99.5% . The two vacuum evaporation using a steam jet pump , the use of steam are 1.1MPa, to automatically adjust the valve. After evaporation of liquid mixture after separation , to the centrifugal granulator granulation. After evaporation of the steam is pumped into the separation surface condenser cooling water through indirect condensation pumping gas condensed steam from the primary jet pump further condensed into the middle of the condenser , the last non-condensed gas is pumped out through the vent steam jet Sec . Two condenser condensate flow to the liquid seal groove , into the sewer .
3 ebullient cooling and granulation : The melt flow to the tank by a motor -driven centrifugal granulation , a centrifugal force , and the liquid droplets at the outlet from the bottom of the column in countercurrent contact with the incoming air , cooling and crystallization, a diameter 1 to 3 mm granular products, by natural air cooling tower granulation suction material from 175 ℃ 90 ℃ fall down to the tower on the belt by a cooling drum ( or catch powder added ) , and finally automatic weighing scale and packaging.