Abstract: In a method of modernizing a heterogeneous exothermic synthesis reactor (1) of the type comprising an external shell (2), in which at least one catalytic bed (15, 16, 17) is supported, the catalytic bed (15, 16, 17) is connected to an external boiler (21), for generating high pressure steam, by means of a reacted gas outlet nozzle (4) and a conduit (29) extending in said nozzle (4) thereby forming an annular airspace (30). Advantageously, the airspace (30) defines an outlet flowpath of the gases cooled in the boiler (21) which avoids overheating of the nozzle (4).

Abstract: Method for the protection of the internal walls of the shell of Braun type converters, transformed into axial-radial reactors with insertion of a cartridge and a cylindrical perforated wall, characterized by the fact that cooling gas is circulated (FLU) at temperatures between 250.degree. and 300.degree. C. in the airspace (I) between cartridge (C) and (P).

Abstract: Improved process to convert in situ conventional reactors with four catalytic beds with axial flow and with intermediate quenching (Kellogg reactor), Third and fourth original beds are combined thus obtaining a reactor with three beds through which the synthesis gas now flows with a substantially radial flow.

Abstract: Reactors for the catalytic conversion of carbon monoxide into carbon dioxide are advantageously modified in situ from axial flow reactors into substantially radial flow reactors, and more particularly into axial-radial flow reactors. To this end at least an external cylindrical wall perforated for its whole length and an internal wall preferably perforated for most of its length are inserted inside the conventional reactor shell and cartridge.

Abstract: A process to modernize existing urea plants which use a stripping with carbon dioxide, and to increase urea yields and flexibility under overload conditions while at the same time reducing energy consumption, corrosion phenomena and possible risks of explosive mixtures. The plant includes: a passivation stage with the introduction of an oxidizing agent and reduction of the air fed to the system; a medium pressure distillation stage of the products leaving the stripping section, and a condensation of the products of the distillation, effected in a pre-evaporation phase to concentrate at low pressure the urea solution.The modernized plant, includes at the start at least a reactor, a scrubber, a condenser, a stripper and the evaporators, includes also a passivation section, a medium pressure distillation section, and a distillation section with double-effect technique.

Abstract: Synthesis gas is reacted in several catalytic beds having axial-radial or radial flow. Reacted gas is collected at an outlet of a final catalytic bed and is transferred to a reaction heat recovery system situated at a top of a reactor. The reactor includes three catalytic beds, two or more beds having inverted, curved bottoms. A first quenching system is located in the reactor and includes a distributor situated inside a first, upper bed at a location immediately under an unperforated portion of an internal wall of that bed. A gas/gas heat exchanger is located centrally within one or more of two upper beds located within the reactor. A water pre-heater or boiler is located inside an upper bottleneck portion of a shell of the reactor and is fed with reacted gas collected from a lowermost catalytic bed.

Abstract: In a process for exothermic and heterogeneous synthesis, for example of ammonia, in which the synthesis gas is reacted in several catalytic beds with axial-radial or only radial flow, the reaction gas is collected at the outlet from the last catalytic bed but one and is transferred to a system for heat recovery external to the reactor, and is re-introduced into the last catalytic bed.

Abstract: A system for modernizing exothermic heterogeneous reactors used in the synthesis of ammonia, methanol and the like, which include a pressure shell, a wall for forming an airspace, a wall or cartridge for containing a catalyst bed, and catalyst-containing basket. An airspace-forming wall is formed of a single piece substantially the whole axial length of the reactor. A bed forming wall is distinct from, and unconnected to, the airspace forming wall, and it constitutes independent modules, each module containing at least one catalyst bed and each module resting either on an underlying module or on an extension of an inside gas distribution collector. The bed forming walls contain the catalyst and distribute gas therethrough. A portion of the catalyst contacts the airspace-forming wall.

Abstract: Improved process for heterogeneous synthesis and related reactors according to which the synthesis catalyst is distributed in three catalytic beds either axial-radial or radial, control of the temperature between beds being effected by means of fresh quench gas between the first and the second bed and by means of indirect cooling with an exchanger between the second and the third bed of the gas leaving the second bed, using fresh gas which is heated inside the tubes of said exchanger.

Abstract: The energy consumption of conventional reactors for heterogeneous synthesis, e.g., ammonia synthesis and methanol synthesis, wherein the synthesis gas flows substantially axially through catalyst beds, is substantially reduced by inserting in at least one catalyst bed: two concentric cylindrical substantially perforated walls to laterally delimit the bed; a bottom closure between these walls; and optionally a diaphragm on top of the bed. Optionally also, a catalyst granulometry gradient may be employed in the upper part of the bed. An upper minor portion of at least one of the cylindrical walls may be unperforated. The synthesis gas now traverses the bed substantially radially.

Abstract: A reactor for heterogeneous synthesis with reduced energy consumption. The reactor includes two cylindrical walls that are at least partly perforated and which annularly deliminate the catalytic beds. An outer wall (Fe) has height (Hi) and a diameter (Di) that is slightly smaller than diameter (Dc) of cartridge (C). An internal, cylindrical wall (Fi) has a height (H'i) and a diameter (D'i) much smaller than diameter (Di). The diameter (D'i) is about equal to diameter (Dt) of a central tube (T) which is an outlet for reacted gas (RG). The top of the cylindrical wall (Fi) is closed by a cover (CO) and is located at a distance (D) from the upper edge of the external wall of the basket (Fe). The basket is closed at its bottom by a tapered wall (PR).

Abstract: A process for the production of urea from ammonia and carbon dioxide via synthesis where the urea formation takes place in a synthesis zone (or zones) in which an excess of free ammonia is kept to favor high conversions, said synthesis zone (or zones) being followed by an ammonia separation and direct recycle to the reaction step, where the urea solution from said reaction zone (or zones) is intimately contacted for a short duration time with a minor portion of the fresh CO.sub.2. The separation step is followed by a CO.sub.2 stripping step where the residual carbamate is removed using a countercurrent fresh CO.sub.2 stream.