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: Fluid bed granulation process comprising the step of cooling the granules in a cooling fluid bed (F2). At least part of the fluidizing air coming out from said cooling fluid bed (F2) is fed into the granulation fluid bed (F1).

Abstract: In order to produce granules granulometrically polidispersed in a very little range, a fluid bed granulation process of the type comprising the steps of preparing a fluid bed of seeds (S1) of the substance to be granulated, having a free surface (P) substantially horizontal; and feeding a continuous flow (L) of a fluid comprising a growth liquid, provides in the fluid bed for a continuous vortex (V) with a substantially horizontal axis, in which an upper zone (Z1) of seeds wetting and evaporation of possible solvent contained in the flow (L) and a lower zone (Z2) of solidification/consolidation of the growth liquid are identified.

Abstract: A process and a plant for the preparation of an acqueous solution of urea suitable for use in a SCR process for nitrogen oxides removal, wherein the urea solution from the recovery section of a urea plant is subject to at least one step of evaporation, separating a vapour stream containing water and ammonia, and obtaining a concentrated and substantially ammonia-free solution, and said concentrated solution is diluted to the concentration of urea suitable for use in the SCR process.

Abstract: A culture medium for filamentary fungi comprising at least one carbon source chosen from the group consisting of molasses, malt extract and sucrose and at least one organic nitrogen source chosen from yeast extract and corn steep liquor is described; a method for producing filamentary fungi, in particular nematophagus fungi on an industrial scale, comprising the step of seeding conidia of such fungi in the aforementioned culture medium and maintaining such a culture medium at a temperature of 23-30° C. for a time of 5-10 days to determine the reproduction and growth of the fungi is also described.

Abstract: A process for high-pressure, liquid phase conversion of urea into melamine is disclosed, where molten urea is fed to a first reaction zone (S1) where the melamine melt is under mechanical agitation, and a heat input (Q1) is provided to maintain the endothermic reaction, and the liquid is then passed to a second reaction zone (S2) kept at a lower temperature and where further agitation is provided. Embodiments of plants adapted to carry out the process are also disclosed, including multiple stirred reactors in cascade and a single reactor with multiple internal compartments defining said first and second reaction zones.

Abstract: The present invention concerns process for obtaining melamine at high purity characterized by comprising the steps of:—quenching a melamine melt, deprived of off-gases of the melamine synthesis and containing melamine impurities such as ammeline, ammelide and polycondensates, with an aqueous solution comprising ammonia under conditions such to substantially convert polycondensates into melamine, obtaining a melamine solution substantially free of polycondensates, recovering melamine from said melamine solution by melamine crystallisation, obtaining melamine crystals and a melamine crystallization mother liquor,—treating said crystallization melamine mother liquor under conditions such to convert at least a portion of its ammeline content into ammelide and melammine, obtaining a treated mother liquid having at least a reduced ammeline content.

Abstract: Method for carbamate condensation of a carbon dioxide/ammonia gaseous phase in a liquid phase in a condensation unit of the so-called submerged type comprising a heat exchange tube bundle having a predetermined number of tubes intended for carbamate condensation, wherein the gaseous phase and the liquid phase are fed contemporaneously and independently to each of the tubes intended for condensation.

Abstract: A fluid bed granulation process and apparatus, wherein a suitable fluid bed of a particulate material is maintained in a granulator (1) fed by an input flow (F) comprising a growth liquid (L) and by a flow (S1) of seeds adapted to promote the granulation, and wherein a part (F2) of said input flow (F) is taken upstream the feeding of the fluid bed, and used in a seeds generator (33), to produce the seeds for the fluid bed.

Abstract: A vibrating and rotating prilling bucket (15) for granulation of a fluid substance (U), said bucket (15) comprising a perforated side wall (15a) and vibrating devices (51, 52) arranged to deliver a force with constant direction (A-A). In a preferred embodiment, the vibrating unit comprise two counter-rotating vibrators delivering rotating forces which balance each other perpendicularly to said constant direction (A-A).

Abstract: A process for producing urea is disclosed, wherein liquid ammonia and carbon dioxide are reacted in a high-pressure synthesis section (100), and at least part of the carbon dioxide is fed to said synthesis section (100) in liquid phase. A plant operating according to said process and a method for modernizing existing plants accordingly are also disclosed.

Abstract: The present invention regards a process for the production of an aqueous solution comprising urea for use in the removal of nitrogen oxides from combustion gas or fumes, the process being characterised in that it comprises the steps of: -subjecting at least a part of a urea-concentrated aqueous solution comprising residual free ammonia, obtained directly from or downstream of a recovery section of a plant for the production of urea, to washing with carbon dioxide, so obtaining a first vapour phase comprising carbon dioxide and optionally ammonia and a urea-concentrated aqueous solution comprising carbamate and essentially lacking in free ammonia, and -diluting said urea-concentrated aqueous solution comprising carbamate and essentially lacking in free ammonia with water until the desired concentration of urea in aqueous solution is reached.

Abstract: Fluid bed granulation process comprising the steps of: -forming a fluid bed of seeds (S1) of a chosen substance, -feeding said fluid bed with a continuous fluid flow (L) comprising a growth liquid, -inducing and maintaining a continuous vortex (V) in said fluid bed, the vortex (V) having a substantially horizontal axis, characterized in that said fluid flow (L) is fed into predetermined first zones (Z1) of said fluid bed, said first zones (Z1) being alternated to second zones (Z2) of said fluid bed in which said fluid flow (L) is not fed.

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: A fluid bed granulation process of a predetermined substance comprises the steps of: forming, through a fluidification. air flow of predetermined flow rate, a fluid bed of granules of said substance to be granulated fed to it in the form of seeds,—feeding said fluid bed with a continuous flow of a growth substance (or liquid).

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 method for modernizing a urea production plant including a urea synthesis reactor, a stripping unit and at least one condensation unit. The method includes providing: means in the condensation unit for substantially condensing at least a portion of a flow comprising ammonia and carbon dioxide in vapor phase leaving the stripping unit; a second stripping unit; means for feeding a first portion of a reaction mixture flow comprising urea, carbamate and free ammonia in aqueous solution leaving the reactor to the first stripping unit; means for feeding a second portion of the reaction mixture flow leaving the reactor to the second stripping unit; and means for feeding at least a portion of a flow comprising ammonia and carbon dioxide in vapor phase leaving the second stripping unit directly to the synthesis reactor. A de-bottlenecking of the high-pressure section downstream of the synthesis reactor may be achieved, improving production capacity.

Abstract: A process for obtaining finished granules of a predetermined substance in a granulation fluid bed (F1) of the so-called vertical growth type, the bed being formed and maintained by a respective flow of fluidification air, comprises a transfer phase by falling of the finished granules in a pressurized space below the granulation bed and a recovery phase of the finished granules from the pressurized space.

Abstract: A method for revamping a conventional self-stripping urea plant is disclosed, where a minor portion (18a) of the carbon dioxide feed is fed to the stripper (7) and used as a stripping agent. In further embodiments, another carbamate condenser is installed, or the conventional horizontal shell-and-tube carbamate condenser (6) is replaced with a vertical submerged unit.