Abstract: In an integrated process for urea and melamine production, urea is produced in a urea plant (10) comprising a high pressure urea synthesis section (11) from which an aqueous solution comprising urea, ammonium carbamate and ammonia is obtained and a urea recovery section (21) operating at low pressure, and melamine is produced in a melamine plant (40) wherein off-gases resulting as by-products of the melamine synthesis are discharged from said plant at a medium pressure and recycled to the high-pressure urea synthesis section (11).

Abstract: In an integrated process for urea and melamine production, urea is produced in a urea plant (10) comprising a high pressure urea synthesis section (11) from which an aqueous solution comprising urea, ammonium carbamate and ammonia is obtained and a urea recovery section (21) operating at low pressure, and melamine is produced in a melamine plant (40) wherein off-gases resulting as by-products of the melamine synthesis are discharged from said plant at a medium pressure and recycled to the high-pressure urea synthesis section (11).

Abstract: A process for urea production from ammonia and carbon dioxide, made to react at a predetermined high pressure in an appropriate synthesis reactor (112), from the reaction between NH3 and CO2 being obtained a reaction mixture comprising urea, ammonium carbamate and free ammonia in aqueous solution, from which a recovery of ammonium carbamate and ammonia is carried out with their subsequent recycle to the synthesis reactor (112), said recovery from the reaction mixture taking place through operative steps of decomposition of the ammonium carbamate into NH3 and CO2 and of their stripping and a subsequent operative step of their recondensation into ammonium carbamate that is recycled to the synthesis reactor, the said reaction mixture obtained from the reaction between ammonia and carbon dioxide being pumped to the operative steps of decomposition and stripping.

Abstract: A process for urea production from ammonia and carbon dioxide, in which part of the aqueous solution comprising urea, ammonium carbamate and ammonia obtained in a urea synthesis section is subjected to dissociation in a treatment section operating at a predetermined medium pressure for the recovery of the ammonium carbamate and of the ammonia contained in it, comprises the steps of subjecting the urea aqueous solution resulting from the aforementioned dissociation step to decomposition in a low pressure urea recovery section and of using at least a part of the condensed steam, obtained by indirect thermal exchange with a second part of said aqueous solution comprising urea, ammonium carbmate and ammonia in a high-pressure stripping unit, as a heating fluid for the dissociation of the first part of the aqueous solution comprising urea, ammonium carbmate and ammonia in the medium-pressure treatment section.

Abstract: A process for urea production comprises a first process step in which ammonia (7) and carbon dioxide (6) are obtained, subjecting natural gas (1) to reforming treatments (12, 14), and a second step of urea (8a) production from such ammonia (7) and from carbon dioxide, through a formation of a solution comprising urea and ammonium carbamate in a urea synthesis reactor (20) and a subsequent decomposition of the ammonium carbamate and. urea recovery, the process comprises the steps of:—treating combustion smokes (5) comprising carbon dioxide with an aqueous solution (9a) comprising a part (7b) of such ammonia (7), obtaining an aqueous ammonium carbamate solution (9c);—supplying the solution (9c) thus obtained to the second process step.

Abstract: In an integrated process for urea and melamine production, urea is produced in a urea plant (10) comprising a high pressure urea synthesis section (11) from which an aqueous solution comprising urea, ammonium carbamate and ammonia is obtained and a urea recovery section (21) operating at low pressure, and melamine is produced in a melamine plant (40) wherein off-gases resulting as by-products of the melamine synthesis are discharged from said plant at a medium pressure and recycled to the high-pressure urea synthesis section (11).

Abstract: A process for urea production from ammonia and carbon dioxide, in which part of the aqueous solution comprising urea, ammonium carbamate and ammonia obtained in a urea synthesis section is subjected to dissociation in a treatment section operating at a predetermined medium pressure for the recovery of the ammonium carbamate and of the ammonia contained in it, comprises the steps of subjecting the urea aqueous solution resulting from the aforementioned dissociation step to decomposition in a low pressure urea recovery section and of using at least a part of the condensed steam, obtained by indirect thermal exchange with a second part of said aqueous solution comprising urea, ammonium carbmate and ammonia in a high-pressure stripping unit, as a heating fluid for the dissociation of the first part of the aqueous solution comprising urea, ammonium carbmate and ammonia in the medium-pressure treatment section.

Abstract: A process for urea production from ammonia and carbon dioxide, in which part of the aqueous solution comprising urea, ammonium carbamate and ammonia obtained in a urea synthesis section is subjected to dissociation in a treatment section operating at a predetermined medium pressure for the recovery of the ammonium carbamate and of the ammonia contained in it, comprises the step of subjecting the urea aqueous solution resulting from the aforementioned dissociation step to decomposition in a low pressure urea recovery section.

Abstract: A process for urea production from ammonia and carbon dioxide, in which part of the aqueous solution comprising urea, ammonium carbamate and ammonia obtained in a urea synthesis section is subjected to dissociation in a treatment section operating at a predetermined medium pressure for the recovery of the ammonium carbamate and of the ammonia contained in it, comprises the step of subjecting the urea aqueous solution resulting from the aforementioned dissociation step to decomposition in a low pressure urea recovery section.

Abstract: A process for urea production from ammonia and carbon dioxide, made to react at a predetermined high pressure in an appropriate synthesis reactor (112), from the reaction between NH3 and CO2 being obtained a reaction mixture comprising urea, ammonium carbamate and free ammonia in aqueous solution, from which a recovery of ammonium carbamate and ammonia is carried out with their subsequent recycle to the synthesis reactor (112), said recovery from the reaction mixture taking place through operative steps of decomposition of the ammonium carbamate into NH3 and CO2 and of their stripping and a subsequent operative step of their recondensation into ammonium carbamate that is recycled to the synthesis reactor, the said reaction mixture obtained from the reaction between ammonia and carbon dioxide being pumped to the operative steps of decomposition and stripping.