Ammonia-urea integrated process and plant
AssigneeCasale SA
InventorsFrancesco Nettuno, Luca Rugnone, Raffaele Ostuni
Life of this patent
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Abstract
A process for the production of ammonia and urea in an ammonia-urea integrated plant comprising an ammonia section and a tied-in urea section, wherein a hydrocarbon is reformed to produce ammonia make-up synthesis gas; said make-up gas is purified by shift conversion and removal of carbon dioxide; carbon dioxide is removed from the make-up gas by a first and a second CO2 removal sections;the first section removes CO2 by absorption with a suitable medium, and the second section removes CO2 by washing with a carbamate solution taken from the urea section; the make-up gas is reacted to produce ammonia; the CO2 removed from the make-up gas and at least part of the ammonia are used to produce urea.
Claims15
1) A process for the production of ammonia and urea in an ammonia-urea integrated plant comprising:
- reforming a hydrocarbon source obtaining a make-up gas containing hydrogen and nitrogen, wherein said make-up gas after purification is converted into ammonia,
- at least part of the synthesized ammonia provides the ammonia feed of a urea synthesis process, said urea synthesis process also receiving a carbon dioxide feed,
- the urea synthesis process comprising the reaction of ammonia and carbon dioxide in a urea synthesis section to form a urea aqueous solution, and subsequent treatment of said solution in a urea recovery section,
- wherein the purification of the make-up gas comprises removal of CO2 by means of a first step of CO2 removal in a first CO2 removal unit and a second step of CO2 removal in a second CO2 removal unit, which are carried out in series or in parallel, said first and second CO2 removal units not being said urea synthesis section,
- one of said first and second CO2 removal steps comprises washing CO2-containing make-up gas with a carbamate solution taken from said urea recovery section,
- and said carbon dioxide feed of the urea synthesis process comprises at least part of the carbon dioxide separated from said CO2 removal steps.
13) An ammonia-urea integrated plant comprising an ammonia section and a urea section, the ammonia section comprising:
- a reforming section for conversion of a hydrocarbon source into a raw make-up gas comprising hydrogen and carbon monoxide,
- a purification section of said raw make-up gas including a CO2-removal section,
- a high-pressure ammonia synthesis loop for conversion of the purified make-up gas into ammonia,
- a urea section comprising a urea synthesis section where carbon dioxide and ammonia react to form an aqueous solution of urea, and a urea recovery section where said aqueous solution of urea is concentrated and a carbamate solution is obtained,
- wherein:
- said CO2-removal section comprises a first CO2 removal unit and a second CO2 removal unit arranged in series or in parallel, said first and second CO2 removal units not being said urea synthesis section,
- the plant comprises a line feeding at least part of said carbamate solution to one of said CO2 removal units, wherein the carbamate solution acts as a washing medium to remove CO2 from the make-up gas.
15) A method for revamping the ammonia section of an ammonia-urea integrated plant, said ammonia section comprising:
- a reforming section fed with a hydrocarbon source,
- a purification section comprising a CO2 absorption section,
- the method comprising:
- installation of a second CO2-removal section in addition to the existing CO2 removal section, and operating by washing with a carbamate solution,
- provision of a flow line for feeding said second CO2-removal section with a stream of carbamate solution taken from the urea section, and preferably of a further line to feed said second CO2-removal section also with gaseous or liquid ammonia, said existing CO2 removal section not being said urea section.
Dependencies are inferred from the claim text.