Urea fertilizer manufacturing process flowsheet design

Process steps of Snamprogetti urea fertilizer manufacturing

Sequence of operations:

Urea formation and High-pressure unit:

  • CO2 and NH3 are primary inputs, urea is formed in this unit at 158-160 kg/cm2 pressure.
  • Passivation air is added to carbon dioxide stream to prevent corrosion of reactor.
  • Compressed CO2 and high pressure NH3, both fed to urea reactor.
  • Product from urea reactor is sent to stripper for H.P.decomposition, and released gases recycled.
  • Solution from stripper fed to medium pressure unit.

Medium pressure unit:

  • Ammonia sent by feed pump to urea reactor and to carbamate condenser.
  • Liquid ammonia enters into the top section of the absorber.
  • Solution from M.P. decomposer fed to low pressure section.

Low-pressure unit:

  • L.P decomposition and vacuum preconcentrator gives urea solution.
  • Ammonia preheating and low pressure condensing is done.
  • Urea solution from preconcentrator sent to vacuum concentration.

Vacuum preconcentrator:

  • To concentrate urea solution to 70% by removing water from solution.
  • Heat provided by the heat content of MP and LP decomposer overheads.
  • Operates under vacuum vapor escapes from top. Solution let out from bottom.

Vacuum concentration:

  • Urea solution from L.P section is input, water removed from solution in this section.
  • Water from the solution is separated in two vacuum concentrators.
  • Vacuum system creates vacuum draws in and condenses water vapor.
  • Urea melt from the second concentrator is sent to the Prilling section.


  • Vacuum concentrated urea melt sent to prilling tower.
  • Urea melt sprayed from prill bucket to form prills.
  • Urea prills collected and sent to the bagging plant.
Process flowsheet design of urea manufacturing:

Conceptual process flowsheet is shown with main unit operations.

Urea fertilizer manufacturing process flowsheet 2D sketch drawing

Chemical process flowsheet drawing of urea industry

Equipments used in urea fertilizer manufacturing process flowsheet design:

  • Autoclave reactor
  • absorber
  • evaporator
  • prilling tower