Abstract: A method of column control includes: passing a feed stream and a make-up stream through a column; withdrawing an overhead fraction from the column; purging at least a portion of the overhead fraction; cooling at least a portion of the overhead fraction in a heat exchanger and passing it through a reflux drum; withdrawing a purge stream and a distillate stream from the reflux drum, wherein the distillate stream has a constant flow rate; recycling at least a portion of the distillate stream back to the column; and passing at least a portion of the distillate stream to a downstream process.

Abstract: A system and method for removing nitrogen and producing a high pressure methane product stream and an NGL product stream from natural gas feed streams where at least 90%, and preferably at least 95%, of the ethane in the feed stream is recovered in the NGL product stream. The system and method of the invention are particularly suitable for use with feed streams in excess of 5 MMSCFD and up to 300 MMSCFD and containing around 5% to 80% nitrogen. The system and method preferably combine use of strategic heat exchange between various process streams with a high pressure rectifier tower and the ability to divert all or a portion of a nitrogen rejection unit feed stream to optionally bypass a nitrogen fractionation column to reduce capital costs and operating expenses.

Abstract: The present invention relates to a column (1) for thermal treatment of fluid mixtures, having a cylindrical, vertically aligned column body (2) which forms a column cavity (3), having a sequence of vertically spaced-apart dual-flow mass transfer trays (8) which are mounted in the column cavity (3) and which have orifices for passage of liquid and gas in countercurrent, and having at least one gas entry orifice (5) disposed below the lowermost of the sequence of dual-flow mass transfer trays (8). It is a characteristic feature of the column of the invention that a gas distribution tray (9) which is disposed between the lowermost of the sequence of dual-flow mass transfer trays (8) and the gas entry orifice (5) has orifices (32) for vertical passage of gas which can be introduced into the column cavity (3) via the gas entry orifice (5), the orifices (32) being formed so as to bring about equal gas distribution over the column cross section.

Abstract: A process for extracting isoprene from a pyrolysis gas mixture or a C5 fraction wherein isoprene is purified by plural extractive distillations in the presence of a polar solvent and cyclopentadiene is effectively removed and recycled as a feedstock without being converted into its dimer, dicyclopentadiene. The isoprene recovered from the process described is more than 99.5% pure.

Abstract: A polyurethane is dyed with an aqueous solution of an acid dye compound, a quaternary ammonium compound selected from soluble tetrabutylammonium compounds and tetrahexylammonium compounds, and, optionally, an water-soluble organic solvent.

Abstract: Extractive distillation for recovering aromatic hydrocarbons employs an extractive distillation column with a novel overhead system including a partial condenser. The process enables (i) efficient removal of heavy non-aromatics, particularly C8 naphthenic compounds, from the EDC bottom stream to increase the purity of aromatic products, especially of the mixed xylenes and (ii) reduction (or better control) of benzene loss to the raffinate product stream to maintain its quality as a gasoline blend stock and, as a result, enhance benzene recovery in the aromatic products. Feedstock includes a full-range feedstock, such as pyrolysis gasoline, or a narrow-range feedstock, such as reformate.

Abstract: A method of separating propylene oxide from a mixture (M) comprising 5 to 50 percent by weight propylene oxide and 50 to 85 percent by weight methanol, said method comprising (i) introducing said mixture (M) into an extractive distillation column; (ii) additionally introducing a polar solvent into said extractive distillation column; (iii) distilling propylene oxide overhead from said extractive distillation column at a bottoms temperature of from 40 to 70° C. and at a pressure of from 300 to 750 mbar.

Abstract: Propylene oxide is recovered through the use of an additive in a distillation solution, resulting in suppressed side reactions and reduced loss of product. Propylene oxide is produced by oxidizing ethylbenzene in a liquid phase with molecular oxygen to a obtain a reaction liquid containing ethylbenzene hydroperoxide; distilling the reaction liquid to obtain a concentrated solution of ethylbenzene hydroperoxide; further mixing and reacting the concentrated solution with propylene to obtain a mixed solution containing propylene oxide; and distilling the mixed solution to separate and recover propylene oxide. At least one compound selected from aliphatic saturated alcohols having 2 to 4 carbon atoms, allyl alcohol, saturated aliphatic hydrocarbons having 6 or 7 carbon atoms, benzene, ethers, ketones, nitriles, amines, pyridines, diamines, and aminoalcohols is added to the mixed distillation solution in an amount of 0.01-100 parts by weight per 100 parts by weight of propylene oxide.

Abstract: An azeotropic distillation method for separating diamondoids from a near-boiling solvent. The method is particularly useful for recovering diamondoids extracted from a produced natural gas stream via hydrocarbon solvent injection.

Abstract: Methyl formate is removed from impure propylene oxide by contacting the impure propylene oxide in a treating zone with a basic ion exchange resin for a period of time sufficient to convert the methyl formate to formic acid and methanol, and by withdrawing a substantially methyl formate-free treated propylene oxide product from the treating zone.

Abstract: An impure propylene oxide feedstock contaminated with from about 50 to about 1000 ppm of methanol and from about 0 to about 1 wt. % of acetone is charged to the lower half of an extractive distillation column containing at least about 25 theoretical plates and an extractive distillation agent consisting essentially of a blend of acetone and water (acetone/water blend) containing about 20 to about 30 wt. % of acetone and, correspondingly, about 80 to about 70 wt. % of water is charged to the tower at a point 4 to 7 theoretical stages above the impure propylene oxide feed point; the extractive distillation agent being introduced into the extractive distillation column in the ratio of said feedstock to said extractive distillation agent of from about 5:1 to about 20:1, whereby an overhead distillate fraction is obtained consisting essentially of propylene oxide contaminated with not more than about 60 ppm of methanol, not more than about 0.02 wt. % of acetone and not more than about 0.3 wt. % of water.

Abstract: Acetone cannot be completely removed from acetone-methanol mixtures by distillation because of the presence of the minimum boiling azeotrope. Acetone can be readily separated from methanol by using extractive distillation in which the extractive agent is a higher boiling oxygenated, nitrogenous and/or sulfur-containing organic compound or a mixture of two or more of these. Typical examples of effective agents are: Glycerine, 1,5-Pentanediol, Dimethylsulfoxide, n-Hexanol, Dioctyl phthalate and N,N-Dimethylacetamide.

Abstract: The present invention relates to a process for removing cyanides from a crude acetonitrile stream. Caustic and formaldehyde are added to an aqueous acetonitrile stream that contains cyanide. The formaldehyde "kills" the cyanides and provides a waste stream that can be conveniently disposed of.

Abstract: A process for isolating butadiene, with the aid of a selective solvent, from a C.sub.4 -hydrocarbon mixture which contains butadiene and small amounts of styrene and may contain oxygen, hydrocarbons more soluble than butadiene in the selective solvent and hydrocarbons less soluble than butadiene in the selective solvent, in which process the C.sub.4 -hydrocarbon mixture is separated by extractive distillation into a distillate which contains the less soluble hydrocarbons, a stream of butadiene and a stream containing the more soluble hydrocarbons, and in which a mixture of styrene and C.sub.4 -hydrocarbons is removed from the C.sub.4 -hydrocarbon mixture in a distillation zone upstream of the extractive distillation, the top product of the said distillation zone being fed to the extractive distillation.

Abstract: An improved process for recovering phenol from phenol-water mixtures by distillation is provided by carrying out the distillation in a manner which avoids the normal phenol-water azeotropic limitation by introducing a ketone-hydrocarbon mixture into the upper section of a fractional distillation column used for the recovery. Mixtures of benzene or lower alkyl substituted benzene with lower ketones are employed in the process.

Abstract: Acetylenic hydrocarbons are removed from a C.sub.4 - or C.sub.5 - hydrocarbon mixture containing a C.sub.4 - or C.sub.5 - diolefin respectively. The feedstock (e.g. a C.sub.4 - or C.sub.5 - cut from an ethylene plant) is extractively distilled to remove paraffins and mono-olefins in the raffinate, using acetonitrile (ACN), dimethyl formamide (DMF), furfural, acetone, dimethylacetamide or N-methyl-2-pyrrolidone mixed with 0-12 weight percent water as the extraction solvent. The bottoms from this first extractive distillation is subjected to a second extractive distillation in which virtually acetylenes-free solvent is used. Isoprene is withdrawn as the distillate with substantially reduced acetylenes content. The bottoms of the second extractive distillation is split three ways. Two streams are handled conventionally (recycle and heavies removal). The third is stripped free of acetylenes so that it may be used as solvent in the second extractive distillation.

Abstract: In a process of extractive distillation, the combination of operating with two liquid phases in at least the uppermost trays of the column, preferably while maintaining the column operation at substantially an optimum reflux ratio, results in increased efficiencies and minimum requirements for selective solvent.