Urea is one important raw materials for the NPK fertilizer production line
.In the international market, urea with a particle diameter of more than 2 mm is called large-grain urea, and small-particle urea has a particle size of about 1.5 mm. The difference in particle size is due to the difference between the granulation process and the equipment after the urea is produced in the plant.
There are many differences between large granular urea and small granular urea, and large granular urea on the market is more expensive than small granular urea. Many people wonder what are the advantages of large particle urea, why is the price more expensive?
The five advantages of large particle urea versus small particle urea are as follows:
1. Low dust content, high compressive strength, good fluidity, can be transported in bulk, not easy to be broken and agglomerated, suitable for mechanized fertilization.
2, Technology advantages. due to different processing requirements on the concentration of urine, generally the reduction of biuret content in large granular urea products, which is beneficial to crops.
3. Internationally, it is believed that large-grain urea plays a role in controlling agricultural non-point source pollution. According to data published in Germany in 2006, as the urea particle size increases, ammonia volatilization loss decreases significantly, nitrification and N2O emissions are delayed, and NOx release is also reduced.
4. The content of biuret in general large-particle urea products is reduced. Urea is molecular nitrogen. They are directly absorbed by crops and can be absorbed in large amounts after being converted into ammonium nitrogen in the soil.
5, the specific surface is smaller, the dissolution rate is slightly slower after being applied to the soil and the single weight is larger, and it can be submerged in the deeper soil in the paddy field to reduce the volatilization loss.
Large particle urea production process:
1) Part of the fine-grained urea is metered and sent to the drum granulator
2) A part of the urea is continuously added to the urea melter, and the steam is supplied by the steam (heat transfer oil) boiler to melt the urea into a liquid state (or to withdraw the branch pipe from the pipe of the prilling tower).
3) After pressurizing through a special pump, the urea slurry is atomized and sprayed onto the curtain in the drum granulator, so that the fine urea uniformly forms a thick curtain on one side of the granulator, and the drum is made.The granulator has an inclined angle. As the granulation rotates uninterruptedly, the fine material of the bed continuously moves forward, and the continuous coating grows into a product of the required particle range.
4) Transfer to the cooler, the cooled particles are at a temperature of 40 to 50 °C.
5) Delivered to the finished screening machine, the fine particles after sorting are directly returned to the drum granulator to participate in coating into balls, and the large particles after sorting are pulverized by the urea crusher machine
and then returned to the drum granulator.
6) The qualified products after sorting enter the automatic packaging scale for weighing, packaging and storage.
7) In order to reduce the pollution to the environment, the urea dust needs to be washed by the dust remover; after the washing, the concentration of the dilute urea solution reaches 30~40%, and then sent to the urea evaporation system, the dust content of the air after dust removal is less than 30mg/m.