Question

describe Urea production and how remove the the undesired products in details ? please answering without handwriting

Answer 1

Process of Urea Production :

Urea is mainly obtained from ammonia and carbon dioxide. Both ammonia and carbon dioxide are introduced in a reactor at a high temperature and pressure and the urea formation occurs through the following steps :

2NH3 + CO = HH2COOHHM (ammonium cordoamate) 2 PM CỘNH • HO+ NH₃CONI (urea)

Urea also contains unreacted ammonia, carbon dioxide and ammonium carbamate. On reducing the pressure and applying heat, NH2COONH4 decomposes into NH3 AND CO2. This ammonia and carbon dioxide can be recycled. The urea solution is further concentrated to produce molten urea, and granulated for use as fertiliser and feedstock.

Removal of Undesired Products :

The major impurities that are generated during the production of urea include the unconsumed reactants like ammonia, carbon dioxide and ammonium carbamate. These can be removed by firstly, reducing the pressure and heating the solution, so the ammonium carbamate can decompose to NH3 and CO2. Some amount of CO2 and NH3 is lost at this stage. On further reducing the pressure, more amount of ammonia and carbon dioxide is lost. At the end, at the least pressure, the mixture of urea is dissolved in water and remains free from impurities.

Also at every stage the unconsumed reactants are dissolved in a solution of water and recycled in the second reactor. The extra ammonia post its purification can be used as a feedstock for the primary reactor.