Abstract: A centrifugal pump (100) for processing molten urea having: an inlet (102) adapted to receive molten urea at a suction pressure; a delivery outlet (104) adapted to allow an output of molten urea at a delivery pressure greater than the suction pressure; and an intermediate outlet (103) adapted to allow an output of molten urea at an intermediate pressure greater than the suction pressure and lower than the delivery pressure.

Abstract: A process is described, having a low-energy consumption and reduced ammonia consumption for the production of high-purity melamine, through the pyrolysis of urea, and the relative plant.

Abstract: A process is described, having a low-energy consumption and reduced ammonia consumption for the production of high-purity melamine, through the pyrolysis of urea, and the relative plant.

Abstract: The present invention refers to a tube heat exchange assembly comprising a tube plate (101) that has a first face which, in use conditions, is facing inside a heat exchange chamber (140), and a second face opposite to said first face and which, in use conditions, is facing outside said heat exchange chamber (140), at least one through hole (103) which passes through the thickness of said tube plate (101) and at least one heat exchange tube (100) which passes through said through hole (103) and is operatively associated with a supply circuit of a heat exchange fluid, wherein said tube heat exchange assembly further comprises at least one sleeve (200) opened at the opposite ends and fixed to said tube plate (101) and to said tube (100), said sleeve (200) being housed in said hole (103) and fitted on said tube (100) at a section of the latter wherein it crosses the thickness of the tube plate (101), wherein furthermore said sleeve (200) protrudes beyond said first face of the tube plate (101), so that a first

Abstract: It is described the use of urea containing formaldehyde in a process for the production of melamine by the pyrolysis of urea, which can be applied both to a high-pressure process and to a low-pressure process.

Abstract: The present invention relates to an improved process for the purification of melamine obtained by synthesis from urea which comprises the following steps: a) bringing raw melamine containing impurities of polycondensates and other by-products of the synthesis reaction, into solution, obtaining a solution/suspension in which the insoluble products are dispersed; b) subjecting the solution/suspension thus obtained to treatment to remove the CO2 dissolved, reducing its concentration to values lower than 0.5% by weight; c) treating the solution/suspension obtained in step b), having a content of CO2 lower than 0.5% by weight, with ammonia in a quantity ranging from 1 to 15%, preferably from 3 to 9% by weight, at a temperature ranging from 110 to 180° C., preferably from 130 to 140° C.; d) putting the solution leaving step c) in contact with a solid catalyst, under the same conditions as step c). The present invention also relates to the equipment for effecting said process.

Abstract: A low-energy-consumption process is described for the production of high-purity melamine, through the pyrolysis of urea, by the collection and purification of the melamine in aqueous solution produced in the pyrolysis reactor, and its separation by crystallization. The present invention also relates to the equipment for effecting the above process.

Abstract: The present invention relates to an improved process for the purification of melamine obtained by synthesis from urea which comprises the following steps: a) bringing raw melamine containing impurities of polycondensates and other by-products of the synthesis reaction, into solution, obtaining a solution/suspension in which the insoluble products are dispersed; b) subjecting the solution/suspension thus obtained to treatment to remove the CO2 dissolved, reducing its concentration to values lower than 0.5% by weight; c) treating the solution/suspension obtained in step b), having a content of CO2 lower than 0.5% by weight, with ammonia in a quantity ranging from 1 to 15%, preferably from 3 to 9% by weight, at a temperature ranging from 110 to 180° C., preferably from 130 to 140° C.; d) putting the solution leaving step c) in contact with a solid catalyst, under the same conditions as step c). The present invention also relates to the equipment for effecting said process.

Abstract: A process for the production of high-purity melamine by pyrolysis of urea at high pressure, wherein the liquid phase output from the pyrolysis reactor is sent to a downstream post-reactor, and wherein the anhydrous gaseous phase from the pyrolysis reactor and from the post-reactor are subjected to washing with molten urea for the recovery of the melamine. The purified liquid exiting the post-reactor is treated in a quenching column, in order to eliminate polycondensates, while the quenching column output is cooled. A high purity melamine is then separated by crystallization from a mother liquor, the greater part of which is recycled to the quenching column, thereby enabling a costless recovery of ammonia and melamine. The remaining mother liquor is treated for the separation of oxidized products of pyrolysis and is then sent back to the quenching column, thereby realizing the complete recovery of the melamine.

Abstract: Process for the production of high-purity melamine with high yields by means of pyrolysis of urea at a temperature comprised between 360 and 420° C.

Abstract: Method and apparatus for applying encoded data on the balance stripe of sound track, the data for providing information for editing an associated film without recording the data on the film. The present invention teaches an apparatus for applying code for synchronizing sound on a single strip of the sound track with an associated film. The apparatus includes a code box for generating the code, which relates the position of the film relative to the sound track. The code box is coupled to an editing flatbed for providing pulses related to the movement of the sound track. A sound module is coupled to the code box for applying the code to the balance stripe.