Abstract: A falling-film process and apparatus for the cocurrent evaporation of a solution is disclosed. The process utilizes a tube-bundle heat exchanger in which the upper ends of the individual tubes of the tube-bundle are closed. Apertures, preferably in the form of slots, are formed adjacent the closed-end of the individual tubes. A liquid heel is maintained above the highest of said apertures and flows into the interior of the tubes through said apertures. Upon entering the tubes the liquid and any vapor released therefrom flows cocurrently in a downward direction. The vapors released from the liquid are recycled to a point above the liquid heel through conduit means separate from the individual tubes.

Abstract: A process for the displacement to the gaseous phase, at 80-250 Kg/cm.sup.2, of the excess NH.sub.3 contained in an aqueous urea solution, coming, at 150.degree.-230.degree. C., from a former stripping, isobaric with the urea synthesis, and containing also CO.sub.2 as ammonium carbamate. The CO.sub.2 is, at most, 25% b.w. of the urea, and the displacement is performed by means of a CO.sub.2 stripping within a falling-film exchanger, hereinafter called the CO.sub.2 stripper, isobaric too with said synthesis. The amount of carbamate leaving the bottom of said CO.sub.2 stripper is substantially equal to the amount of carbamate entering the same stripper. The global NH.sub.3 :CO.sub.2 ratio, in the solution entering the CO.sub.2 stripper, is from 2 to 8 b.w. and heat is supplied only to the uppermost portion of the pipes of the CO.sub.

Abstract: A process for synthesizing ammonia is disclosed comprising the steps of generating the synthesis gas from hydrocarbons by the primary reforming of said hydrocarbon with steam and by the secondary reforming of the resulting gaseous mixture with oxygen; subjecting a portion of the starting hydrocarbon mixed with the steam to a tertiary reforming in which the necessary heat is provided by the gaseous reaction mixture leaving the secondary reforming; causing the ammonia synthesis to occur at low pressure with drying of the gas sent to the synthesis reactor by employing a molecular sieve; causing the ammonia contained in the reacted gas to be absorbed by water; and subjecting the ammonia solution so obtained to a distillation which may be a conventional distillation step or one effected by means of two distillation columns operating at different pressures.

Abstract: In an integrated flexible installation for producing ammonia and urea, the improved method which consists in that a portion of the gaseous stream comprising carbon dioxide, hydrogen and nitrogen is fed to a complementary decarbonation area and then admixed with a portion of a similar, but non-decarbonated stream of gas prior to entering the carbon-dioxide-absorption unit. Liquid ammonia is recovered from a portion of the ammoniated aqueous solution used for abating the ammonia and sent to a distillation column to recover liquid ammonia therefrom.

Abstract: A process for distilling ammoniacal solutions is disclosed comprising the utilization of two distillation columns operating at different pressures, the ammoniacal solution to be distilled being sent--after being mixed with the ammoniacal vapors flowing from the top of the column operating at the lower pressure--to the column operating at the higher pressure, from the bottom of which the partially distilled ammoniacal solution is sent to the column operating at the lower pressure; the liquid ammonia being recovered at the top of the column operating at the higher pressure while the residual ammoniacal solution is withdrawn from the bottom of the column operating at the lower pressure.

Abstract: In an integrated or combined process for the production of ammonia and urea, the improvement consisting in that the absorption of CO.sub.2 from the raw gas going to the synthesis reactor for ammonia is carried out with an absorption apparatus which is divided into two sections, one being of the plate type and the other of the thin film type. The predominant fraction of CO.sub.2 is stripped in the thin-film section, the remainder in the adiabatic plate section.

Abstract: An improved isobaric double-recycle process is disclosed for synthesizing urea with the formation of ammonium carbamate as an intermediate, comprising effecting reaction between ammonia and carbon dioxide at high NH.sub.3 :CO.sub.2 molar ratios, a heat-treatment of the synthesis product at substantially the same pressure as that of the synthesis step and in the presence of a stripping gas, and two distinct isobaric recycles of the residual substances and of the substances in excess released from said synthesis product, said process being characterized in that:(a) said heat-treatment of the synthesis product is carried out in two consecutive stages which are isobaric or substantially isobaric with respect to the synthesis step, in the first of which stages said synthesis product is heated, whereby substantially all the residual ammonium carbamate is decomposed and the decomposition products are displaced together with part of the excess NH.sub.3, while in the second stage the remaining part of the NH.sub.

Abstract: In a sea water desalination apparatus, the improvement consisting in the fact that the levels of sea water and fresh water in the several stages of the multistage installation are regulated by a device comprising a plurality of piezometric tubes in combination with cylindrical sleeves surrounding these tubes and having slots so proportioned as to give a preselected pressure drop.

Abstract: In an ammonia synthesis column, the combination of a tube bundle heat exchanger and a boiler with two superposedly arranged catalyst beds permits to recover considerable amounts of reaction heat, the flow of the gases being reacted running in a radial direction.

Abstract: Dimethyl ether is prepared by feeding a mixture of CO, CO.sub.2 and H.sub.2, wherein the quantity of CO is in excess of the stoichiometric value, to a reactor containing a methyl alcohol synthesis catalyst, such as a copper base or chrome-zinc base catalyst, and a methyl alcohol dehydration catalyst, such as alumina, whereby methyl alcohol is formed as an intermediate product which is transformed into dimethyl ether in the same reactor at a temperature in the range of 220.degree. to 400.degree. C and a pressure in the range of 30 to 500 kg/cm.sup.2.

Abstract: A method is disclosed for removing acidic gaseous components from natural gases, this method comprising an initial desulfurization stage employing a selective solvent, then removing carbon dioxide by low temperature distillation, the carbon dioxide providing the cooling effect required for such a condensation, recovering the solvent, absorbing the residual carbon dioxide with the regenerated solvent and recycling the CO.sub.2 -laden solvent to the desulfurization stage.

Abstract: A sea water desalination system which is composed by a compact and self-contained unit, each unit comprising several evaporation stages, means being provided for recycling the condensates and for dissipating the pressure differential existing between the brine-containing tub and the tube plate of each individual stage.

Abstract: A novel apparatus for the desalination of sea water is described. The apparatus comprises a column of a plurality of superposed cylindrical sections, each section including two film evaporators; two basins interconnected between said cylindrical sections; a restriction for passing brine from basin to basin, siphon tubes for withdrawing the condensed water from each section and accessory preheating means and inlet and outlet tubes.