Abstract: A tube isothermal chemical reactor (1), comprising a vessel (2) with a central axis (A-A), and an annular tube heat exchanger (40) embedded in a catalytic reaction space, the exchanger (40) comprising a plurality of concentric ranks (10, 11) of tube packs (10a), each of said tube packs comprising parallel tubes (30), a respective heat-exchange fluid feeder (20) and a respective heat-exchange fluid collector (21).

Abstract: System for supporting a plate heat exchanger (10, 100, 200) inside an isothermal chemical reactor (1), comprising a circumferential ring structure (40) fixed at least to top radial sides (19s) of the plates (11), said structure being formed as a single or double ring.

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 producing a synthesis gas containing hydrogen and nitrogen, suitable for production of ammonia, wherein a raw synthesis gas (13) obtained by reforming of a natural gas feedstock is purified in a cryogenic separator (CS), and a portion of purified gas (16) is expanded and used as a cooling medium in the same separator, said expanded portion (16) being then re-introduced in the main stream of purified synthesis gas. A suitable apparatus and revamping of conventional plants according to the invention are also disclosed.

Abstract: A process for producing ammonia synthesis gas, where a natural gas feedstock (10) is reformed in a primary steam reformer (12) and in a secondary reformer (14) at a pressure of at least 35 bar; the product syngas (16) at the output of the secondary reformer is cooled and subject to catalytic medium-temperature shift, converting the CO into CO2 and H2; downstream said medium-temperature shift, the carbon dioxide is removed from the syngas by physical absorption.

Abstract: A system (8; 9; 50) is described of walls for catalytic beds of synthesis reactors (1), in which there is a wall (14) in direct contact with a catalytic bed (7) for containing it, said wall (14) having a plurality of portions (17) permeable to the gases and a plurality of portions (19; 54; 55) impermeable to the gases, said portions (17) permeable to the gases being equipped with slits (18; 52, 53; 60; 70) of a size such as to allow the free passage of the synthesis gases through them but not the passage of the catalyst, in which the slits are obtained with milling, water cutting or electro-erosion processing.

Abstract: Method and apparatus for carrying out highly exothermic catalyzed reactions, like so-called oxidative reactions, in pseudo-isothermal conditions, for example the reaction for producing nitric acid and the reaction for producing formaldehyde.

Abstract: An internal start-up heater (10) for an ammonia reactor (1), comprising longitudinal heating members (16) and a supporting structure for said heating members (16), the structure comprising plates (20A-20D) with parallel beams (22A-22D) in contact with said heating members (16), wherein the plates are arranged in plate sets formed by at least a first and a second plate having differently arranged supporting beams.

Abstract: An isothermal chemical reactor (1) comprising an array of radially arranged plate-like heat exchange elements (11) inside a reaction space, each element comprising feeding and collecting ducts and a bundle of parallel tubes (15) defining channels (12) for a heat exchange medium, the tubes (15) having an elongated cross section and being disposed with a variable orientation relative to the radial direction of the reactor, so that inner tubes near the axis of the reactor have the cross-section major axis aligned with said radial direction, and outer tubes have the same axis perpendicular to the radial direction. The preferred structure of a plate-like heat exchange element is also disclosed.

Abstract: A system (8; 9; 50) is described of walls for catalytic beds of synthesis reactors (1), in which there is a wall (14) in direct contact with a catalytic bed (7) for containing it, said wall (14) having a plurality of portions (17) permeable to the gases and a plurality of portions (19; 54; 55) impermeable to the gases, said portions (17) permeable to the gases being equipped with slits (18; 52, 53; 60; 70) of a size such as to allow the free passage of the synthesis gases through them but not the passage of the catalyst, in which the slits are obtained with milling, water cutting or electro-erosion processing.

Abstract: A process for producing ammonia synthesis gas from a hydrocarbon-containing feedstock, with steps of primary reforming, secondary reforming with an oxidant stream, and further treatment of the synthesis gas including shift, removal of carbon dioxide and methanation, wherein the synthesis gas delivered by secondary reforming is subject to a medium-temperature shift (MTS) at a temperature between 200 and 350° C., and primary reforming is operated with a steam-to-carbon ratio lower than 2. A corresponding method for revamping an ammonia plant is disclosed, where an existing HTS reactor is modified to operate at medium temperature, or replaced with a new MTS reactor, and the steam-to-carbon ratio in the primary reformer is lowered to a value in the range 1-5-2, thus reducing inert steam in the flow rate trough the equipments of the front-end.

Abstract: Isothermal vertical reactor (1) for a chemical reaction, comprising a shell (2) with internal gas-permeable walls (16, 18) defining an inlet distribution chamber (17) and a product collecting chamber (19), an open-top catalytic bed between said gas-permeable walls, and a tube heat exchanger (5) embedded in said catalytic bed, the tube heat exchanger (5) comprising a bundle of U-tubes, where an inlet (14) is disposed to direct a fresh charge in an upper chamber (21) over the catalytic bed and the U-shaped top portion of the tube bundle; a portion (F1) of the fresh charge passes through the catalytic bed with a mixed axial-transversal flow, and another portion (F2) of the fresh charge enters the inlet gas-distribution chamber (17) and passes through the catalytic bed with a substantially transversal flow.

Abstract: A steam cooled chemical reactor (1) comprising a vertical vessel (2), a plate heat exchanger embedded in a catalytic bed, to cool the catalytic bed by evaporation of a cooling water flow, wherein a water inlet and a steam outlet are located underneath the heat exchanger, and the plates and related piping are arranged so that the path of the cooling flow comprises a first ascending path from bottom to top of the catalytic bed, and a second descending path from top to the bottom of catalytic bed, and wherein internal evaporation channels of the plates provide the second descending or the first ascending path, and water upcomers or respectively steam downcomers provide the other of said first and second path.

Abstract: An ammonia plant is disclosed, where ammonia purge gas (20), is sent to a cryogenic recovery unit, said recovery unit comprising means of cooling (102, 202, 302, 402, 502) and a high-pressure phase separator (103, 203, 303, 403, 503) operating at loop pressure; inside said unit the purge gas (20) is cooled to a cryogenic temperature, and a partial liquefaction of methane and argon is achieved; the high-pressure phase separator separates the cooled stream into a gaseous stream and a bottom liquid; the gaseous stream is reheated in a passage of a heat exchanger; the unit is then capable to export a gaseous stream (123, 223, 323, 423, 523) containing nitrogen and hydrogen at loop pressure, that can be reintroduced at the suction side of the circulator (4) of the loop.

Abstract: A process for producing ammonia synthesis gas from the reforming of hydrocarbons with steam in a primary reformer (1) equipped with a plurality of externally heated catalytic tubes and then together with air in a secondary reformer (2) is characterized in that the reaction of said hydrocarbons with said steam in said primary reformer (1) is performed at an operating pressure of more than 35 bar in the catalytic tubes, in that air is added to said secondary reformer in excess over the nitrogen amount required for ammonia synthesis and in that the excess of nitrogen is removed downstream the secondary reformer preferably by cryogenic separation or by molecular sieves of the TAS or PSA type. This process allows to obtain high synthesis gas production capacities and lower investment and energy costs.

Abstract: The present invention concerns an isothermal reactor (1) comprising a pressure vessel (2) closed at the opposite ends by respective bottoms (3, 4), a reaction zone (9) in said pressure vessel (2) in which at least one catalytic basket (10) is positioned, and at least one heat exchange unit (13) embedded in said at least one catalytic basket (10), each heat exchange unit (13) comprising a plurality of heat exchangers (14) each having an inner chamber intended to be crossed by an operating heat exchange fluid, the reactor being characterized in that it comprises means (17, 18) for picking up samples of operating heat exchange fluid from groups (16) of pre-established exchangers in each heat exchange unit (13), so as to ascertain the possible existence of damaged exchangers (14) in said groups (16) of exchangers through analysis of respective samples of operating heat exchange fluid.

Abstract: A method for modernizing an ammonia synthesis loop (1) with a first converter (10) and a second converter (11) in series, the first converter (10) comprises a cartridge with one or more catalyst beds, the second converter (11) comprises a catalyst bed in direct contact with said vessel, the method comprising the steps of removing the second converter, and boosting the first converter by replacing the cartridge with a high-efficiency cartridge comprising a plurality of adiabatic catalyst beds and inter-bed heat exchangers, or an isothermal catalyst bed, and by reducing the concentration of inerts in said first converter.

Abstract: Plate type heat exchanger (20,120) for a isothermal chemical reactor (60), of the type comprising a substantially box-shaped flattened body (22), defining an internal chamber (24) and equipped with an inlet connection (28) and an outlet connection (29) for a first flow of a heat exchanger operative fluid into and from said chamber (24), at least one supplying-distributing device (26, 126) of a second fluid flow, associated with said body (22) and in fluid communication with the internal chamber (24) thereof, in order to regulate the temperature of said operative fluid, said at least one supplying-distributing device (26,126) being supported inside said internal chamber (24) and in fluid communication therewith.

Abstract: A process and related equipment for producing ammonia synthesis gas are disclosed, wherein a raw syngas (13) is purified in a cryogenic section (CS) and a nitrogen-rich liquid stream (30) is separated from the raw syngas flow during purification and HN ratio adjustment, and wherein the pressure of said liquid stream (30) is reduced in a turbine (60) to enhance net refrigerative effect for the cryogenic section. Embodiments wherein chilling is also provided by a low-pressure or high-pressure syngas expander are also disclosed.

Abstract: A process and a related equipment for making ammonia make-up synthesis gas are disclosed, where: a hydrocarbon feedstock is reformed obtaining a raw ammonia make-up syngas stream; said raw syngas is purified in a cryogenic purification section refrigerated by a nitrogen-rich stream produced in an air separation unit; the nitrogen-rich stream at output of said cryogenic section is further used for adjusting the hydrogen/nitrogen ratio of the purified make-up syngas; an oxygen-rich stream is also produced in said air separation unit and is fed to the reforming section.