Abstract: A system and method for determining the environmental impact of a process is disclosed in which resources are categorized into distinct Environmental Performance Indicators (“EPI's”), some of which are value EPIs that are derived based on the amount of the resource used per Finished Product Volume (FPV), which is representative of the amount of product that is produced by the process; and others are percentage EPIs that represent a measure of efficiency, and are derived from the amount of renewable resources used as a percentage of total resources used. A graphical representation of the EPIs allows a quick visual interpretation of the environmental friendliness of a particular process or group of processes, and allows a visual comparison between two different processes.

Abstract: Butadiene is recovered from a hydrocarbon fraction containing it together with butenes and acetylene hydrocarbons by introducing said fraction into a first extractive distillation column, feeding aqueous acetonitrile into said column above the introduction point of said fraction and extracting a vapor stream containing butadiene below said introduction point; feeding said vapor stream into a second extractive distillation column, feeding aqueous acetonitrile above the introduction point of said vapor stream and recovering a vapor stream consisting essentially of butadiene at the top of said second column; and rectifying this last vapor stream to recover pure butadiene.

Abstract: Nitric acid having a concentration of at least 98% by weight is obtained from a gaseous stream resulting from catalytic oxidation of ammonia and containing nitrogen oxide and steam, by flowing said stream in an oxidation and condensation column in countercurrent with a stream of nitric acid at 40-60 wt.%, recovering nitrogen peroxide at the top of the column, liquefying said peroxide, bringing it into contact with aqueous nitric acid, oxygen and air in a chemical absorption stage, and distilling the resulting superazeotropic nitric acid. A part of the nitric acid discharged from the oxidation column is directly recycled and the remainder is recycled after distillation to give azeotropic acid and remove water, a part of the latter being used for the chemical absorption.

Abstract: Saline water is desalted by flowing it in two evaporation stages in series in the form of a film falling on the inside of heat-exchange tubes. The pressure and temperature in the second evaporation stage are lower than in the first stage. The steam evolved in the second stage is compressed and delivered to the first stage where it condenses on the tubes, whereas the steam evolved in the first stage is fed in the second stage where it condenses on the tubes. The condensation heat of the steam is used for vaporizing said saline water from said film. This technique allows a production of 15-50 cu.m/hr of soft water, instead of a production of 15-20 cu.m/hr usually obtained by conventional thermocompression techniques.

Abstract: Nitric acid having a concentration of at least 98 wt.% is produced from nitrogen peroxide by absorbing the latter in superazeotropic nitric acid, distilling the resulting solution so as to recover nitric acid at a concentration of at least 98 wt.% and nitrogen peroxide, liquefying the latter and reacting it in a first stage with aqueous nitric acid (70-80% wt.%) and air and delivering the resulting superazeotropic nitric acid, together with the solution, to the distillation column. Nitrogen peroxide and oxygen unreacted in the first stage are contacted with nitric acid at 68-75 wt.% in a second stage, thus to produce said aqueous nitric acid fed to the second stage. The said nitric acid at 68-75 wt.% and the superazeotropic acid used for the absorption are extracted from the bottom part of the distillation column.

Abstract: Nitric acid having a concentration of at least 98 wt.% is prepared by recovering in liquid state nitrogen peroxide from a gaseous flow containing the same, by absorption in nitric acid, heating of the resulting solution and liquefaction of the gaseous peroxide evolved, followed by a first chemical absorption of a fraction of the liquid peroxide with nitric acid at 70-80% and air and distillation of the resulting concentrated nitric acid. The gaseous products discharged from said first absorption and comprising unreacted peroxide and air are contacted with nitric acid and water in a second chemical absorption stage, thereby to produce the nitric acid used in the first absorption. The remaining fraction of liquid peroxide is delivered to the distillation column, discharged at the top thereof and recycled to the liquefaction stage, while nitric acid is extracted at the bottom of the distillation column and recycled to the second absorption stage.

Abstract: A thermocompression apparatus for desalting saline water, wherein: the evaporator tubes extend vertically above the separating chamber for steam and non-evaporated water and have their lower ends opening into the separating chamber through a lower header plate; the upper ends of the evaporator tubes extend through an upper header plate into a plenum chamber overlying the latter, said plenum chamber being arranged to provide a pool of saline water submerging the upper ends of the evaporator tubes; and each of said upper ends having means therein arranged to receive saline water from the pool and to discharge it in the form of falling film on the inner surface of its respective evaporator tube, whereby the said film and the steam produced therefrom flow co-currently downwardly in the tubes towards the separating chamber.

Abstract: A multistage flash-evaporator for producing soft water from a saline water, comprising a shell forming a pair of lobes enclosing therebetween a spinal portion in symmetrical arrangement with respect to a vertical longitudinal mid-plane. The top and bottom walls of the spinal portion are, in cross-sectional shape, circular arcs having their centres of curvature on the said mid-plane, while the lobes are polycentric curves each of which has its centres of curvature on a plane parallel to the mid-plane. A specifically shaped hood arrangement in the shell is provided to define in each stage a condensation chamber centrally located between a pair of evaporation chambers.