An annular divided wall column for the cryogenic rectification of air or constituents of air is provided. The annular divided wall column includes a first annular column wall and a second annular column wall disposed within the first annular column wall to define an annulus column region and an interior core column region. The present annular divided wall column further includes structured packing elements disposed within at least the annulus column region as well as a ring-shaped cantilevered collector; and a ring-shaped distributor disposed in the annulus column region above or below the plurality of structured packing elements. The thermal expansion and contraction of the second annular column wall in a radial direction and in an axial direction is independent of the thermal expansion and contraction of the first annular column wall in the radial and axial directions.

The present invention relates to a toluene diisocyanate purification method enabling acquisition of a product having a small amount of dimers in a final product by means of using a reactive dividing wall column during toluene diisocyanate preparation. More particularly, according to the present invention, in order to obtain a product having a small amount of dimers in accordance with a reversible reaction of a monomer and a dimer, a purification procedure is designed by means of applying the temperature, pressure, time of stay and the like of a reactive dividing wall column as appropriate particular conditions, a reboiler having short time of stay and high heat transfer rate is used, and thus a dimerization reaction is inhibited and the purity and yield of the product are enhanced. Therefore, high-purity toluene diisocyanate can be purified and obtained.

Processes and systems for separating a mixture of three or more chemical components into multiple product streams each enriched in one of the components are provided herein. In some aspects, the present invention relates to processes for the separation of a chemical mixture including at least a heavy key component, an intermediate key component, and a light key component to form a product stream enriched in the light key component, a product stream enriched in the intermediate key component, and a product stream enriched in the heavy key component. Systems described herein may include one or more thermally coupled distillation columns including, for example, a dividing wall column, or a plurality of distillation columns arranged in a thermally integrated configuration.

Disclosed is a vapor splitter including: a chimney tray dividing an internal space of a housing into an upper space and a lower space; a chimney provided on the chimney tray to enable the upper space and the lower space to communicate with each other; a cap covering the chimney with a gap therebetween such that a gas discharge hole is formed so that gas, coming out through the chimney, can be transferred to the upper space through the gas discharge hole; a liquid feeding unit for feeding liquid to the upper space; and a liquid discharging unit for discharging the liquid out of the upper space. The size of the gas discharge hole is adjusted by controlling the height of the liquid collected on the chimney. Further disclosed is a method of adjusting a vapor split ratio using the vapor splitter.

A process for preparing an aromatic polyamine mixture including 4,4-methylenedi(phenylamine) and higher homologues of MDA is provided. The process includes steps of (i) reaction of aniline with formaldehyde by means of an acid catalyst to form a crude product mixture (I), (ii) neutralization of the crude product mixture (I) and removal of the salts formed; (iii) isolation of aniline; (iv) distillation of the resulting crude product mixture so as to separate off (iv-1) a mixture (II) of MDA isomers (II-1) containing from 8 to 20% by weight of 4,4-methylenedi(phenylamine) and not more than 0.3% by weight of secondary components (II-2) and (iv-2) a low boiler mixture of at least 55% by weight of secondary components (II-2) and MDA isomers (II-1); and (v) recirculation of the mixture (II).

Process for isolating pure 1,3-butadiene from a crude C.sub.4 fraction by extractive distillation using a selective solvent, wherein (a) the crude C.sub.4 fraction is introduced into a predistillation column, a first low boiler fraction comprising C.sub.3-hydrocarbons is taken off as overhead stream, a gaseous C.sub.4 fraction is taken off as side stream and a first high boiler fraction is taken off as bottom stream, (b) the gaseous C.sub.4 fraction is brought into contact with a selective solvent in at least one extraction column, giving an overhead fraction comprising butanes and butenes and a bottom fraction comprising 1,3-butadiene and selective solvent, (c) crude 1,3-butadiene is desorbed from the bottom fraction in at least one stripping column, with a stripped selective solvent being obtained and the stripped selective solvent being recirculated to the extraction column, and (d) at least part of the crude 1-3-butadiene is fed to a pure distillation column and a second high boiler fraction is separated off and a gaseous purge stream is taken off. Gaseous purge streams from the columns which are necessary in order to keep the concentration of molecular oxygen below a predetermined concentration limit are consolidated with output streams which are in any case provided for discharging other components in the process. The recirculation of the second high boiler fraction to a lower section of the predistillation column creates a further degree of freedom in operation of the pure distillation column.

The invention relates to the use of a column with a separating wall as a purification/finishing column in a (meth)acrylic acid recovery method based on the use of two distillation columns in the absence of external organic solvent. The method according to the invention improves the energy balance for the method while improving the technical quality of the (meth)acrylic acid recovered. The method according to the invention further produces polymer-grade (or glacial) (meth)acrylic acid compatible with the production of high-molecular weight acrylic acid polymers.

Disclosed is a 1,3-butadiene separation and recovery method which can reduce the amount of 1,3-butadiene polymer produced when 1,3-butadiene is separated and recovered from a mixed fluid containing 1,3-butadiene. The method includes an extractive distillation step of performing extractive distillation of the mixed fluid to obtain a fraction containing crude 1,3-butadiene, and a dividing wall distillation step of performing dividing wall distillation of the fraction containing crude 1,3-butadiene to obtain a fraction containing an impurity having a higher boiling point than 1,3-butadiene, a fraction containing an impurity having a lower boiling point than 1,3-butadiene, and a fraction containing high-purity 1,3-butadiene.

Aspects of the present invention relate to systems and processes for obtaining desired mercaptans or thiophenes from a feed stream containing a mixture of mercaptans, thiophenes and other components. In one aspect of the invention, a system for separating one or more components from a feed stream of mixed mercaptans includes one or more distillation columns in connection with a feed containing mercaptans, the distillation column having a rectification section, a stripping section, and a feed side section separated from a side draw section by a dividing wall that extends from the rectification section to the stripping section. The distillation column further being in connection with a condenser and a reboiler; and a distillate stream, a side drawn stream, and a bottoms stream.

Method for concentrating components through a distillation column are disclosed. A process stream is provided containing hydrocarbons, carbon dioxide, and water. The process stream is passed into the distillation column at a bottom portion of the distillation column. The process stream is fractionally distilled in the distillation column, forming an overhead vapor stream, a middle fluid stream, and a bottoms liquid stream. The middle fluid stream is removed from a middle location of the distillation column. The bottoms liquid stream is removed from the distillation column. The overhead vapor stream is removed from the distillation column. The middle fluid stream consists of a first portion of the carbon dioxide and a first portion of the hydrocarbons. The bottoms liquid stream consists of a second portion of the hydrocarbons as a first phase and substantially all the water as a second phase.