Block diagram of Urea and Ammonia Process

Natural gas a high content source of hydrogen and carbon is used for production of ammonia and urea in chemical process industry. By a block diagram this process can be explained and present the unit operations involved in the process. There are two main sections which are operated individually and produce ammonia and urea without any dependence. Urea is formed from carbon dioxide and ammonia. These are produced in the ammonia section using natural gas and atmospheric air (which contain 79% nitrogen by volume).
Block diagram of ammonia and urea processed from natural gas
Block diagram of Ammonia and Urea production from Natural Gas

  1. Hydrogenation is done as first step to add hydrogen and convert the sulphur compound free from sulphur producing hydrogen sulfide.
  2. This H2S is removed by adsorption technique using adsorption beds.
  3. The gas is sent to steam reforming section where all hydrocarbon are cracked to methane and Hydrogen. Then these are burned on the catalyst bed by supplying compressed air which produces carbon dioxide, carbon monoxide, nitrogen, hydrogen and steam.
  4. Carbon monoxide is converted to carbon dioxide and hydrogen by water shift reaction.
  5. Finally carbon dioxide is removed by absorption using hot potassium carbonate solution ( G.V solution), leaving the gas with Nitrogen and Hydrogen which are used for Ammonia production in a ammonia synthesis reactor which used iron as catalyst.
  6. The so produced Ammonia and the Carbon dioxide are used as raw materials for urea synthesis.
Flow Sheet of Urea
Plant layout