Natural gas a high content source of hydrogen and carbon is used for the production of ammonia and urea in the 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).
High-pressure-regenerator-and-co2 |
Block diagram of Ammonia and Urea production from Natural Gas |
- Hydrogenation is done as the first step to add hydrogen and convert the sulphur compound free from sulphur producing hydrogen sulfide.
- This H2S is removed by adsorption technique using adsorption beds.
- The gas is sent to the steam reforming section where all hydrocarbon is 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.
- Carbon monoxide is converted to carbon dioxide and hydrogen by water shift reaction.
- 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 an ammonia synthesis reactor which used iron as catalyst.
- The so produced Ammonia and Carbon dioxide are used as raw materials for urea synthesis.
Flow Sheet of Urea
Snamprogetti-urea-process-description
Haldor-topsoe-process-flow-sheet
Block-diagram-of-ammonia-production
Plant layout