Abstract: A system for analysis of vent gas of a urea plant, comprising: a Raman spectroscope; a sampling conduit that connects the spectroscope to a main pipe of the urea plant configured to convey a sample stream to be analysed to the spectroscope; and a temperature-adjusting device, operated by a temperature controller and acting on at least one thermal treatment portion of the conduit configured to adjust the temperature of the sample stream circulating in the conduit.

Abstract: A plant for recovering metals and/or metal oxides from industrial process waste, in particular oil product refining waste, comprises a furnace; a feed line connected to a main inlet of the furnace and configured to feed the furnace with a solid waste containing metals, in particular in oxide form; an outlet line, connected to a solid phase outlet of the furnace and configured to draw a metal-enriched solid phase out of the furnace; the furnace is a belt conveyor furnace having a belt conveyor closed in a loop with a substantially horizontal configuration and having a top face, which receives the waste to treat and conveys it between two longitudinal opposite ends of the belt conveyor furnace respectively provided with the main inlet and the solid phase outlet.

Abstract: A counter-current cross-flow heat exchanger for heating a first gas and cooling a second gas, includes modules in fluid communication with one another, each module being positioned on a plane, the planes mutually overlapping. Conduits allow entry and exit of the first and second gases into and out of the exchanger. Each module has heat exchange plates, with heating and cooling faces. The plates are orthogonal to the module plane and parallel to define alternating heating and cooling spaces. The first gas crosses each heating space with a direction substantially parallel to the plane of each module and the second gas crosses each cooling space with a direction substantially orthogonal to the plane of each module. The cooling spaces between adjacent modules are in direct fluid communication. The heating spaces between adjacent modules are in fluid communication with one another by conduits/conveyors, creating a serpentine path.

Abstract: A duplex stainless steel for use in a urea production plant and/or in a urea production process, containing in weight percentage (% w): C 0.03 or less; Si 0.5 or less; Mn 2.5 or less; Cr from more than 30.0 to 35.0; Ni from 5.5 to 8.0; Co from 0.01 to 0.8; Mo from 2.0 to 2.5; W 2.5 or less; N from 0.3 to 0.6; Cu 1.0 or less; and having one or more of: Ca 0.0040 or less; Mg 0.0040 or less; one or more rare-earth elements in a total amount of 0.1 or less; the balance being Fe and impurities; and satisfying the relationship: Z=1.062 (Ni+Co)+4.185 Mo is between 14.95 and 19.80.

Abstract: An integrated process for production of urea and urea-ammonium sulphate (“UAS”) comprises: a urea synthesis step carried out in a urea synthesis reactor; a recovery and concentration step, wherein a urea solution produced in the urea synthesis step is progressively concentrated in at least one recovery section and in a concentration section, recovering unreacted ammonia and carbon dioxide and water from said urea solution; a step of producing ammonium sulphate by reaction of sulphuric acid and ammonia in an ammonium sulphate production apparatus; a step of mixing said ammonium sulphate with concentrated urea coming from the concentration section to produce a UAS mixture; in the ammonium sulphate production step, at least a part of the ammonia is provided by at least one off-gas containing ammonia and recovered from the recovery and concentration step.

Abstract: A counter-current cross-flow heat exchanger for heating a first gas and cooling a second gas, includes modules in fluid communication with one another, each module being positioned on a plane, the planes mutually overlapping. Conduits allow entry and exit of the first and second gases into and out of the exchanger. Each module has heat exchange plates, with heating and cooling faces. The plates are orthogonal to the module plane and parallel to define alternating heating and cooling spaces. The first gas crosses each heating space with a direction substantially parallel to the plane of each module and the second gas crosses each cooling space with a direction substantially orthogonal to the plane of each module. The cooling spaces between adjacent modules are in direct fluid communication. The heating spaces between adjacent modules are in fluid communication with one another by conduits/conveyors, creating a serpentine path.

Abstract: A urea synthesis reactor is provided that comprises a casing extending along an axis and a first and a second inlet tube inserted through respective through openings of the casing and respectively connected, inside the casing, to a light phase distributor and to a heavy phase distributor configured to feed the reactor with a light phase containing carbon dioxide and a heavy phase containing ammonia, respectively; the light phase distributor comprises one or more tubular elements extending and/or distributed over the cross-section of the reactor and about the axis and provided with intake holes spaced apart from one another, so as to distribute said light phase in a plurality of intake points distributed transversely in the reactor and about the axis.

Abstract: A method of removing ammonia from a continuous vent gas stream of a urea plant, in particular of a medium-pressure section of a urea plant, includes a step of removing ammonia from the continuous vent gas stream of the urea plant using a controlled-combustion process including at least a first lean, oxygen-poor combustion step performed in the presence of an understoichiometric amount of oxygen acting as the sole comburent, and in a reducing atmosphere of hydrogen.

Abstract: An integrated process for production of urea and urea-ammonium sulphate (“UAS”) comprises: a urea synthesis step carried out in a urea synthesis reactor; a recovery and concentration step, wherein a urea solution produced in the urea synthesis step is progressively concentrated in at least one recovery section and in a concentration section, recovering unreacted ammonia and carbon dioxide and water from said urea solution; a step of producing ammonium sulphate by reaction of sulphuric acid and ammonia in an ammonium sulphate production apparatus; a step of mixing said ammonium sulphate with concentrated urea coming from the concentration section to produce a UAS mixture; in the ammonium sulphate production step, at least a part of the ammonia is provided by at least one off-gas containing ammonia and recovered from the recovery and concentration step.

Abstract: A system for analysis of vent gas of a urea plant, comprising: a Raman spectroscope; a sampling conduit that connects the spectroscope to a main pipe of the urea plant configured to convey a sample stream to be analysed to the spectroscope; and a temperature-adjusting device, operated by a temperature controller and acting on at least one thermal treatment portion of the conduit configured to adjust the temperature of the sample stream circulating in the conduit.

Abstract: A urea synthesis reactor is provided that comprises a casing extending along an axis and a first and a second inlet tube inserted through respective through openings of the casing and respectively connected, inside the casing, to a light phase distributor and to a heavy phase distributor configured to feed the reactor with a light phase containing carbon dioxide and a heavy phase containing ammonia, respectively; the light phase distributor comprises one or more tubular elements extending and/or distributed over the cross-section of the reactor and about the axis and provided with intake holes spaced apart from one another, so as to distribute said light phase in a plurality of intake points distributed transversely in the reactor and about the axis.

Abstract: A plant for recovering metals and/or metal oxides from industrial process waste, in particular oil product refining waste, comprises a furnace; a feed line connected to a main inlet of the furnace and configured to feed the furnace with a solid waste containing metals, in particular in oxide form; an outlet line, connected to a solid phase outlet of the furnace and configured to draw a metal-enriched solid phase out of the furnace; the furnace is a belt conveyor furnace having a belt conveyor closed in a loop with a substantially horizontal configuration and having a top face, which receives the waste to treat and conveys it between two longitudinal opposite ends of the belt conveyor furnace respectively provided with the main inlet and the solid phase outlet.

Abstract: A method of removing ammonia from a continuous vent gas stream of a urea plant, in particular of a medium-pressure section of a urea plant, includes a step of removing ammonia from the continuous vent gas stream of the urea plant using a controlled-combustion process including at least a first lean, oxygen-poor combustion step performed in the presence of an understoichiometric amount of oxygen acting as the sole comburent, and in a reducing atmosphere of hydrogen.

Abstract: A process for the direct synthesis of urea from ammonia and carbon dioxide with increased corrosion resistance, comprising, in the high-pressure synthesis section, a reaction step in a vertical reactor fed with at least one stream of fresh carbon dioxide containing a passivating agent and a decomposition-stripping step of the non-converted reagents, wherein the gas-liquid mixture collected at the head of the reactor is separated into a gaseous stream and a liquid stream fed to the tail and head of the stripper, respectively.

Abstract: A urea reactor tray having a base plate; and a number or quantity of hollow cup-shaped members, which project vertically from the base plate along respective substantially parallel axes perpendicular to the base plate, and have respective substantially concave inner cavities communicating with respective openings formed in the base plate; the tray having a number or quantity of first cup-shaped members, each of which extends axially between an open top end having the opening, and a closed bottom end, and has a lateral wall with through holes substantially crosswise to the axis, and a bottom wall which closes the closed bottom end and has no holes.

Abstract: Tube-bundle equipment of the falling liquid film type, comprising a vertical cylindrical body closed at the ends and divided into at least an upper section, an intermediate section and a lower section by means of two perforated tube sheets arranged transversally to support the tubes forming the bundle, wherein each of said tubes is surmounted, on the upper end, by a ferrule, for the inlet and distribution of the liquid in the form of a film, which comprises in the upper part, one or more openings for the outlet of vapors, at an intermediate height one or more openings, preferably tangential, for the inlet of the liquid and below, a circular base for resting on said tube from which an internal cylindrical section, inserted in the tube for a length varying from 10 to 200 mm, protrudes downwards together with an outer metallic strip for a length of at least 2 mm, so that, in the circular area defined between said outer metallic strip and said protruding cylindrical section, there is a gasket, inserted between sa

Abstract: A process for the direct synthesis of urea from ammonia and carbon dioxide with increased corrosion resistance, comprising, in the high-pressure synthesis section, a reaction step in a vertical reactor fed with at least one stream of fresh carbon dioxide containing a passivating agent and a decomposition-stripping step of the non-converted reagents, wherein the gas-liquid mixture collected at the head of the reactor is separated into a gaseous stream and a liquid stream fed to the tail and head of the stripper, respectively.

Abstract: A process for the direct synthesis of urea from ammonia and carbon dioxide at high pressures and temperatures, with the formation of ammonium carbamate as intermediate, comprising a decomposition step of the ammonium carbamate and stripping of the gases formed, operating substantially at the same pressure as the synthesis step, wherein the recycled liquid streams are fed, at least partially, to the same decomposition and stripping step after being preheated by heat exchange with a stream included in the high-pressure synthesis cycle.

Abstract: A urea reactor tray having a base plate; and a number or quantity of hollow cup-shaped members, which project vertically from the base plate along respective substantially parallel axes perpendicular to the base plate, and have respective substantially concave inner cavities communicating with respective openings formed in the base plate; the tray having a number or quantity of first cup-shaped members, each of which extends axially between an open top end having the opening, and a closed bottom end, and has a lateral wall with through holes substantially crosswise to the axis, and a bottom wall which closes the closed bottom end and has no holes.

Abstract: A process for the direct synthesis of urea from ammonia and carbon dioxide at high pressures and temperatures, with the formation of ammonium carbamate as intermediate, comprising a decomposition step of the ammonium carbamate and stripping of the gases formed, operating substantially at the same pressure as the synthesis step, wherein the recycled liquid streams are fed, at least partially, to the same decomposition and stripping step after being preheated by heat exchange with a stream included in the high-pressure synthesis cycle.