Abstract: An in-situ modernization method is provided for a reactor of the type having a plurality of spaced apart perforated plates disposed within a hollow cylindrical vessel wherein the plates are perforated and spaced from the vessel wall to define an annular gap between the periphery of each plate and the vessel wall. The method includes the steps of providing a substantially annular baffle to substantially close the gap while leaving an opening with the openings of adjacent plates being diametrically opposed to each other. Alternatively, the annular gap may be substantially closed by an annular baffle and an enlarged opening is provided in each plate with the openings of adjacent plates being diametrically opposed to each other.

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: Urea is formed by the synthesis of ammonia with carbon dioxide at high pressure and temperature in an internal space of reactors through which flow a liquid phase cocurrently with a gas phase. The reactors are divided into compartments to avoid excessive mixing of the entire liquid phase and to allow the intermittent redistribution of the gas in bubbles of a suitable size for increasing the transfer of heat and mass between the two phases. At each passage from one compartment to the next, the liquid phase and the gas phase are made to flow on separate routes and are distributed in each compartment with a continuous, permanent, and even flow.

Abstract: An improved process for urea production as well as a method of retrofitting a pre-existing urea plant based on the Stamicarbon process are disclosed. According to the invention, a high-yield reactor with partial removal of the reaction heat and a urea recovery section of the solution leaving the high-yield reactor, are added to the pre-existing urea plant, means being provided for recycling unreacted ammonia and carbon dioxide vapors as well as a carbamate solution obtained in the urea recovery section to the pre-existing reactor.

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: A method for in-situ modernization of a reactor for carrying out heterogeneous exothermic synthesis reactions, in particular of the so-called lozenge type including an external shell (2), calls for prearrangement within the shell (2) of a plurality of superimposed catalyst beds (12, 13, 14) supported at a pre-set distance by means of support elements (22, 23, 24) rested on or fixed to, e.g. by welding, a plurality of annular shoulders (8a, 8b, 8c) pre-existing in the reactor.

Abstract: A method for in-situ modernization of a reactor for urea synthesis at high pressure and temperature of the type wherein a co-current flow of a gaseous phase and a liquid phase takes place, comprising a vertical tubular shell (2) in which is supported a plurality of horizontal perforated plates (6a-6f), calls for the step of providing on at least one of the perforated plates (6a-6f) a plurality of structurally independent caps (8) having at the top a plurality of holes (11) and forming with the plate a plurality of lateral apertures (13). Advantageously, the holes (11) and the apertures (13) define respective preferential paths of the gaseous phase and the liquid phase respectively, to achieve intimate mixing thereof.

Abstract: An improved process for urea production as well as a method of retrofitting a pre-existing urea plant based on the Stamicarbon process are disclosed. According to the invention, a high-yield reactor with partial removal of the reaction heat and a urea recovery section of the solution leaving the high-yield reactor, are added to the pre-existing urea plant, means being provided for recycling unreacted ammonia and carbon dioxide vapors as well as a carbamate solution obtained in the urea recovery section to the pre-existing reactor.

Abstract: An improved process for urea production as well as a method of retrofitting a pre-existing urea plant based on the Stamicarbon process are disclosed. According to the invention, a high-yield reactor with partial removal of the reaction heat and a urea recovery section of the solution leaving the high-yield reactor, are added to the pre-existing urea plant unreacted ammonia and carbon dioxide vapors as well as a carbamate solution obtained in the urea recovery section are recycled to the pre-existing reactor.

Abstract: Process and apparatus for the revamping of urea production plants for the synthesis of ammonia (NH3) and carbon dioxide, with a stripping section with NH3, in which the process carries out with differentiated yields, a majority reaction a) between highly pure reagents and a reaction b) between less pure substantially recycled reagents. According to the invention, the urea solution is now fed upstream the stripping section and a reactor with heat removal is utilized. Advantageously, the production capacity of the existing reactor is reduced, with respect to the projected one, in a quantity of 35% to 5%, preferably from 20% to 10%, in favor of the capacity of the "once-through" reactor.

Abstract: A method for "in-situ" modernization of a reactor for effecting heterogeneous exothermic synthesis reactions, especially of the so-called Kellogg type, including the preliminary step of providing at least three radial or axial-radial catalyst beds (11, 12, 13), includes the steps of providing a first gas/gas heat exchanger (18) between the first (11) and second (12) catalyst beds and a second gas-gas heat exchanger (29) in the third catalyst bed (13). Thanks to the provision of two exchangers (18, 29) for cooling of the gases flowing between the catalyst beds by means of indirect heat exchange, the present modernization method allows to achieve a reactor with a high conversion yield.

Abstract: A process is described for the industrial synthesis of urea, making the ammonia (NH3) and the carbon dioxide (CO2) react, in at least one reaction space, at high pressures and temperatures and recycling at least in part the unreacted products obtained in a recycle section, characterized by: a) a synthesis reaction between reactants of high purity; and b) a synthesis reaction between less pure reactants, substantially recycled by the so-called recycle section.The corresponding new plant includes a reactor (R1) of high yield "once through"), a reactor (R2) of lower yield and a section of recovery and recycle.The application of the process to preexisting plants requires the simple addition of a reactor of high yield and of pumping devices.

Abstract: A process is described for the industrial synthesis of urea, making the ammonia (NH3) and the carbon dioxide (CO2) react, in at least on reaction space, at high pressures and temperatures and recycling at least in part the unreacted products obtained in a recycle section, characterized by: a) a synthesis reaction between reactants of high purity; and b) a synthesis reaction between less pure reactants, substantially recycled by the so-called recycle section. The corresponding new plant includes a rector (R1) of high yield ("once through"), a reactor (R2) of lower yield and a section of recovery and recycle. The application of the process to preexisting plants requires the simple addition of a reactor of high yield and of pumping device.

Abstract: In a process of producing urea in which ammonia and carbon dioxide are reacted in a first reaction space (E-1, R-1) the unreacted carbamate present in the reaction mixture is subjected to a thermal decomposition treatment, so as to obtain ammonia and carbon dioxide which are sent to a second reaction space (R-2) in which they react with a solution of recycled carbamate coming from an urea recovery section (3). Advantageously, the regulation of the temperature and of the ammonia/carbon dioxide molar ratio in the second reaction space (R-2) is carried out by respectively regulating the temperature of the recycled carbamate solution and the temperature of the thermal decomposition treatment of the residual carbamate leaving the first reaction space (E-1, R-1).

Abstract: In a process of producing urea in which ammonia and carbon dioxide are reacted in a first reaction space (E-1, R-1) the unreacted carbamate present in the reaction mixture is subjected to a thermal decomposition treatment, so as to obtain ammonia and carbon dioxide which are sent to a second reaction space (R-2) in which they react with a solution of recycled carbamate coming from an urea recovery section (3). Advantageously, the regulation of the temperature and of the ammonia/carbon dioxide molar ratio in the second reaction space (R-2) is carried out by respectively regulating the temperature of the recycled carbamate solution and the temperature of the thermal decomposition treatment of the residual carbamate leaving the first reaction space (E-1, R-1).

Abstract: A process is described for the industrial synthesis of urea, making the ammonia (NH3) and the carbon dioxide (CO2) react, in at least one reaction space, at high pressures and temperatures and recycling at least in part the unreacted products obtained in a recycle section, characterized by: a) a synthesis reaction between reactants of high purity; and b) a synthesis reaction between less pure reactants, substantially recycled by the so-called recycle section.The corresponding new plant includes a reactor (R1) of high yield ("once through"), a reactor (R2) of lower yield and a section of recovery and recycle.The application of the process to preexisting plants requires the simple addition of a reactor of high yield and of pumping devices.

Abstract: Process for the hydrolysis of urea contained in the process water from plants for the synthesis of urea consisting of the thermic treatment of the water containing urea and of the removal by stripping of the compounds from decomposition of the urea (CO.sub.2 and NH.sub.3) in a series of stages in series with superimposed flow.The equipment is a vertical column with superimposed modules with weirs which penetrate in two successive modules and give the solution a rising movement.

Abstract: Process for the industrial synthesis of urea, by reacting ammonia (NH.sub.3) and carbon dioxide (CO.sub.2) in at least one reaction space, at high pressures and temperatures and by recirculating at least part of the non-reacted products obtained in a recovery section, characterized by the fact that the following takes place : a synthesis reaction A) between highly pure reagents, and a synthesis reaction B) between less pure reagents, substantially recycled from the said recovery section, the reaction A) being either of adiabatic type A1) or with partial reaction heat removal A2).

Abstract: A system for the passivation of metal surfaces, and more especially those of stainless steel, titanium, etc., in equipment used for chemical processes, where elements and compounds are formed which have a corrosive action, in particular where temperature and pressure are higher than ambient conditions. In the system the main passivating agent is oxygen (air) combined with at least a second auxiliary agent, characterized by the fact that the latter is ozone (03).