Patent ID: 6340451
Filing Date: 2002-01-22
Classification: C01C,C07C,Y02P

Abstract:
Method for the simultaneous modernisation of a plant for ammonia production and a plant for urea production, the plant for ammonia production comprising a section for the production of raw ammonia synthesis gas comprising carbon monoxide, hydrogen and nitrogen, a carbon monoxide conversion section, a decarbonation section, a methanation section, a compression section of the ammonia synthesis gas and an ammonia synthesis section, provided in series, the plant for urea production comprising a compression section of carbon dioxide, a urea synthesis section and a urea recovery section, said method being characterised in that it comprises the steps of:providing a carbamate synthesis section and a carbamate decomposition section; providing means for feeding a compressed raw ammonia synthesis gas flow comprising carbon dioxide, hydrogen and nitrogen to said carbamate synthesis section; providing means for feeding a portion of a flow comprising ammonia, hydrogen and nitrogen obtained in said ammonia synthesis section to said carbamate synthesis section; providing means for feeding at least part of a flow comprising carbamate in aqueous solution coming from said urea recovery section to said carbamate decomposition section; providing means for feeding a flow comprising ammonia and carbon dioxide in vapour phase obtained in said decomposition section to said urea synthesis section; providing means for feeding a flow comprising diluted carbamate in aqueous solution obtained in said carbamate decomposition section to said carbamate synthesis section; providing means for feeding a gas flow comprising hydrogen and nitrogen obtained in said carbamate synthesis section to said ammonia synthesis section; providing means for feeding a flow comprising carbamate in aqueous solution obtained in said carbamate synthesis section to said carbamate decomposition section and/or to said urea synthesis section.