Casale Sa

Urea Casale Sa

Andrea Scotto

Federico Zardi

Simone Gamba

Paolo Bertini

Serena Gabbiadini

Ermanno Filippi

Enrico Rizzi

Marco Badano

Matteo Fumagalli

Gabriele Di Carlo

Stefano Reggiori

Damiano Visciotti

A process for the purification of a melamine melt () containing melamine and by-products, comprising the steps of: (a1) In quenching of said melamine melt; (a2) decomposition of by-products with alkali, providing an alkaline aqueous solution of melamine (); (b) stripping of said alkaline aqueous solution of melamine (); (c) crystallization of melamine with a first alkali-containing solution () and separation of solid melamine () from a mother liquor (); (d) treatment of said mother liquor, providing a waste water stream () containing carbonates; (e) decomposition of at least part of the carbonates contained in said waste water stream () into carbon dioxide and alkali, providing a second alkali-containing aqueous solution (); (f) recycle of at least part of said alkali-containing aqueous solution () to at least one of said steps (a1), (a2) and (c).

Process for melamine purification

Plant for the synthesis of melamine starting from urea, wherein the stream of offgas containing NH3 and CO2 produced by the synthesis of melamine is converted into urea in a dedicated urea plant.

Plant for the synthesis of melamine with offgas recovery in a tied-in urea plant

Combined apparatus () for the synthesis of urea from ammonia and carbon dioxide, comprising an internal wall () which delimits two coaxial zones () inside the apparatus, operating respectively as reaction () and condensation () zones, and optionally also comprising a stripping zone and/or a scrubber integrated in the same apparatus.

Combined apparatus for the synthesis of urea

Method for solidifying a chemical product () which is in melt form, comprising the following steps: subjecting a first stream () of said chemical product to a prilling stage, with production of prills () of varying diameter; feeding said prills () to a screening device, which separates them according to their diameter into at least a first fraction () and a second fraction (), the average diameter of the prills of said first fraction () being smaller than the average diameter of the prills of said second fraction (); subjecting a second stream () of said chemical product and the first fraction () of prills to a granulation stage, with the production of granules ().

Production of a solid chemical product

A process for the purification of a melamine melt () containing melamine and by-products, comprising the steps of: (a1) quenching of said melamine melt; (a2) decomposition of by-products with alkali, providing an alkaline aqueous solution of melamine (); (b) stripping of said alkaline aqueous solution of melamine (); (c) crystallization of melamine with a first alkali-containing solution () and separation of solid melamine () from a mother liquor (); (d) treatment of said mother liquor, providing a waste water stream () containing carbonates; (e) decomposition of at least part of the carbonates contained in said waste water stream () into carbon dioxide and alkali, providing a second alkali-containing aqueous solution (); (f) recycle of at least part of said alkali-containing aqueous solution () to at least one of said steps (a1), (a2) and (c).

A process for the finishing of urea comprising: (a) removing water from an aqueous urea solution in a first evaporation and condensation section, obtaining a urea melt; (b) subjecting said urea melt to a finishing treatment comprising granulation and resulting in solid urea and air contaminated with urea dust and ammonia; (c) subjecting said contaminated air to acid scrubbing, producing an aqueous solution comprising urea and ammonium salts; (d) subjecting at least part of said aqueous solution to evaporation in a second evaporation section, obtaining a liquid stream comprising urea and ammonium salts and a gaseous stream; (e) condensing said gaseous stream in a second condensation section, obtaining a recycle aqueous stream; (f) using at least a part of said recycle aqueous stream for the scrubbing of contaminated air; (g) converting at least a portion of said liquid stream comprising urea and ammonium salts into solid particles, and (h) using said solid particles as seeds for the granulation; a corresponding urea plant and method of revamping a urea plant are also disclosed.

Urea finishing process with acid scrubbing

Plant for the synthesis of urea, comprising: a synthesis section comprising at least one reactor, a compressor for supplying COto said synthesis section, a gas turbine for the operation of said COcompressor and a heat recovery steam generator; the heat source of said heat recovery steam generator consists of the exhaust gases of said gas turbine, and at least one steam flow produced by said heat recovery steam generator is used as heat source for at least one component of said urea plant.

Plant for urea production

A method for revamping a self-stripping urea plant comprising the installation of a new CO2-stripping synthesis section (), wherein at least part of the aqueous urea solution () leaving said new section () is directed to the existing low pressure recovery section () of the self-stripping plant, by-passing the existing self-stripping high-pressure section () and medium pressure treatment section ().

Method for revamping a self-stripping urea plant

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 () obtaining a cooled liquid ammonia stream (), separating a gaseous fraction () comprising hydrogen and nitrogen from said cooled liquid ammonia, obtaining purified liquid ammonia () at a high pressure, and reheating said purified liquid ammonia () after separation of said gaseous fraction, obtaining a reheated purified ammonia () 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.

Process and plant for ammonia-urea production

A process and a related plant for the synthesis of urea, where a solution () comprising urea is obtained in a synthesis section (), said solution is treated in a recovery section (), and an aqueous solution () comprising mainly urea and water, which is obtained from said recovery section, is concentrated by means of contact with a water-selective membrane.

Concentration of the urea solution in a process for the synthesis of urea

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

Method for the modernization of a urea production plant

A process and a related plant layout for producing urea are disclosed, wherein the high-pressure loop () comprises a synthesis reactor (), a thermal stripper (), a condenser (), and an adiabatic COstripper () disposed upstream said thermal stripper, separating a vapour phase () containing ammonia from the urea solution () discharged from the reactor, and recycling said vapour phase to the reactor. The adiabatic stripper () can be incorporated in a reactor () having a top reaction zone and a bottom adiabatic stripping zone. A revamping method for a conventional urea plant in accordance with the inventive process is also disclosed.

Growing community of inventors

Breganzona, Switzerland

Andrea Scotto