Abstract: A process for synthesis of urea and a related reaction section of a urea plant, where: ammonia and carbon dioxide are reacted in a liquid phase in a first reaction zone (S1) and heat (Q1) is withdrawn from said first reaction zone to promote the formation of ammonium carbamate, the liquid product (103) from said first reaction zone is then passed to a second reaction zone (S2) distinguished from said first reaction zone, and heat (Q2) is added to said second reaction zone to promote the decomposition of ammonium carbamate into urea and water, where the liquid phase in at least one of said first reaction zone and second reaction zone is kept in a stirred condition. A downflow reactor for carrying out the above process is also disclosed.

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: 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: A process for the production of granules or pellets containing filamentous fungi is described comprising the steps of selecting and growing filamentous fungi in a suitable culture medium for a predetermined amount of time, adding a gelling agent and at least one carrier to said culture medium, so as to obtain a mixture, subjecting said mixture to gelling through contact, drop by drop, with a solution containing a calcium salt thus obtaining gelled pellets or granules containing said filamentous fungi and drying said gelled pellets or granules to a moisture content of 13-18%.

Abstract: Plant for urea production from ammonia and carbon dioxide having a so-called high-pressure section which comprises a synthesis reactor and a condensation unit (7, 107) positioned inside the reactor, all substantially operating at the same pressure.

Abstract: A process for ammonia -urea production where: liquid ammonia produced in an ammonia section is fed to a urea section directly at the ammonia synthesis pressure, and where the liquid ammonia is purified at high pressure with the steps of: cooling the liquid ammonia (20) obtaining a cooled liquid ammonia stream (21), separating a gaseous fraction (22) comprising hydrogen and nitrogen from said cooled liquid ammonia, obtaining purified liquid ammonia (23) at a high pressure, and reheating said purified liquid ammonia (23) after separation of said gaseous fraction, obtaining a reheated purified ammonia (24) having a temperature suitable for feeding to the urea synthesis process. The application also deals with an ammonia -urea plant comprising an ammonia cooler, a liquid-gas separator and an ammonia re-heater and with a method for revamping existing ammonia -urea plants.

Abstract: A process for production of a granular urea product in a fluidized-bed where: small droplets (10) of fresh urea melt are contacted with a cooling medium to form solid particles, said solid particles (11) are contacted with droplets of urea melt (12) which are larger than said germ particles, the solid particles and said droplets forming together larger solid particles (13), and said solid particles further increasing their size step by step and upon contact with droplets of urea melt, until the solid particles reaches a given size, and said solid particles are then subject to a further growing process by contact with liquid droplets now smaller than the solid particles, until a desired size of the granular product is reached.

Abstract: A process for preparation of a granular urea product by granulating a urea solution in a fluidized bed, where the granulation process takes place along a substantially longitudinal growth path, from a granulation starting end (1s) to a product discharge end (1E) of said fluidized bed, and said urea solution enters the fluidized bed by means of several urea inputs (2A, 2B, 2C) taken from a main urea feed (2), where an additive (6) is mixed with said urea solution said additive has a non-uniform concentration in said urea inputs, so that at least two of said urea inputs have a different concentration of additive.

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: A stripper (SN) for carbamate decomposition and ammonia plus carbon dioxide recovery from a urea solution (U) is realized with a shell-and-tube heat exchanger, where a liquid falling film of urea solution and a counter-current gaseous flow of a stripping medium fed to a bundle of surface-heated tubes (6); the stripping medium such as carbon dioxide is distributed into the tubes (6) by a plurality of gas risers (32); the gas risers are preferably associated to a perforated tray (30) in the bottom chamber (11) of the stripper. Revamping of a conventional CO2 stripper is also disclosed.

Abstract: A reactor for two-phase reaction, in particular for urea synthesis at high pressure and temperature of the type wherein a co-current flow of a gaseous phase and a liquid phase takes place, comprises a substantially cylindrical vertical external shell (2) in which is supported a plurality of superimposed horizontal perforated plates (6a-6e) in mutually spaced relationship and at least one opening (12a-12e) for liquid flow being defined in correspondence of each of the perforated plates. Advantageously the openings (12a-12e) for liquid flow are mutually offset so as to obtain a substantially zigzag preferential flow path for the liquid phase in the reactor.