Abstract: A system and method for removing nitrogen from natural gas using two fractionating columns, that may be stacked, and a plurality of separators and heat exchangers, with horsepower requirements that are 50-80% of requirements for prior art systems. The fractionating columns operate at different pressures. A feed stream is separated with a vapor portion feeding the first column to produce a first column bottoms stream that is split into multiple portions at different pressures and first column overhead stream that is cooled and separated into vapor and liquid portions to control subcooling of the vapor portion prior to feeding the second column. Heat exchange between first column and second column streams provides first column reflux and reboil heat for a second column ascending vapor stream. Three sales gas streams are produced, each at a different pressure.

Abstract: Processing schemes and arrangements for the catalytic cracking of a heavy hydrocarbon feedstock and obtaining light olefins substantially free of carbon dioxide via amine treatment and employing fractionation processing are provided.

Abstract: The present invention concerns a process for recovering lower carbon olefins from MTO or DTO product gas. Said process primarily comprises the product gas compressing, pre-deethanizing, demethanizing and ethylene recovering apparatus, depropanizing column, ethylene rectification column, propylene rectification column and the like. In addition, the process of the present invention needs no independent ethylene cooling system, and the ethylene recovery rate may achieve 99.5%.

Abstract: A process for the recovery and purification of ethylene and optionally propylene from a stream containing lighter and heavier components that employs an ethylene distributor column and a partially thermally coupled distributed distillation system.

Abstract: A process for the high-yield recovery of ethylene and heavier hydrocarbons from the gas produced by pyrolysis of hydrocarbons in which the liquid products resulting from the fractionated condensation of a cracking gas for the recovery of almost all the ethylene, are supplied to a distillation column, called a de-ethanizer, at different intermediate levels. At the top of the de-ethanizer the vapor of the column distillate is treated directly in an acetylene hydrogenation reactor, the effluent containing virtually no acetylene being separated by a distillation column called a de-methanizer, into an ethylene- and ethane-enriched tail product, while the head product is recycled by compression or treated for subsequent recovery of ethylene.

Abstract: A method for cooling a process stream in which one of a plurality of open-loop refrigerant streams is cooled by indirect heat exchange with other of the open-loop refrigerant streams in a refrigerant heat exchanger to yield a cooled primary refrigerant stream. The process stream is cooled by indirect heat exchange with a process refrigerant stream in a separate process heat exchanger, wherein the process refrigerant stream comprises at least a portion of the cooled primary refrigerant stream. The method is particularly useful in large process plants which require multiple parallel heat exchangers to cool the process stream.

Abstract: A system and process for the recovery of ethylene and propylene from a gas stream, such as a refinery offgas stream. The process comprises withdrawing, cooling, and recovering an overhead vapor stream from a single distillation column. The process includes withdrawing a liquid C3+, C4+, C5+ or C6+ bottoms product stream and recycling a portion of the bottoms steam to maintain an overhead column condenser at temperature refrigeration levels of above −140° F. and withdrawing a vapor side stream rich in propylene or ethylene-propylene.

Abstract: C2 and C3 hydrocarbons, particularly ethylene and propylene, are recovered from refinery or petrochemical plant gas mixtures by cooling and fractionating a feed gas mixture containing these hydrocarbons and lighter components. Refrigeration for the process is provided by a closed-loop gas expander refrigeration process cycle which preferably uses nitrogen as the recirculating refrigerant. Cooling and fractionation may be effected in a dephlegmator.

Abstract: A process for recovering olefins from a gas stream containing olefins and hydrogen. The process comprises compressing the gas stream in at least one compression stage to form a compressed gas stream, contacting the compressed gas stream with a membrane at conditions effective to obtain a permeate stream rich in hydrogen and a retentate stream depleted in hydrogen, and introducing the permeate stream into a pressure swing adsorption system at conditions effective to obtain a nonadsorbed stream rich in hydrogen and a desorbed stream comprising olefins.

Abstract: Disclosed are methods of and means for producing ethylene by chilling the ethylene plant demethanizer heat exchange train with a refrigerated stream or streams from a cryogenic natural gas plant effective to provide ethylene level refrigeration, by condensing the ethylene distillation tower overhead with ethylene level refrigeration stream or streams from the cryogenic natural gas plant, by refluxing the ethylene plant demethanizer distillation column with a predominantly liquid methane mixture from the cryogenic natural gas plant, and by combinations thereof. Significant advantages in capital and operating costs associated with ethylene production.

Abstract: A process for the recovery of ethane, ethylene, propane, propylene and heavier hydrocarbon components from a hydrocarbon gas stream is disclosed. In recent years, the preferred method of separating a hydrocarbon gas stream generally includes supplying at least a portion of the gas stream to a work expansion device, then directing the work expanded stream to a distillation column at a mid-column feed point below an upper rectification section. The top column feed above the upper rectification section is typically a condensed and subcooled gaseous stream, frequently comprised of a gas stream that would otherwise feed the work expansion device. In the process disclosed, the work expanded stream is further cooled prior to feeding the distillation column at the mid-column feed point, so that a lesser volume of top column feed is required to maintain the column overhead temperature at a temperature whereby the major portion of the desired components is recovered.

Abstract: A refrigeration system for an ethylene plant uses a low pressure demethanizer and a binary refrigerant comprising a mixture of methane and ethylene or methane and ethane. The refrigeration composition may be constant throughout the system or separators may be used to divide the refrigerant into a methane-rich binary refrigerant and an ethylene- or ethane-rich binary refrigerant.

Abstract: A process for recovering olefins from a cracking effluent containing olefins and hydrogen. The process comprises compressing the cracking effluent in at least one compression stage to form a compressed cracking effluent, contacting the compressed cracking effluent with a membrane at conditions effective to obtain a permeate stream rich in hydrogen and a retentate stream depleted in hydrogen, and introducing the permeate stream into a pressure swing adsorption system at conditions effective to obtain a nonadsorbed stream rich in hydrogen and a desorbed stream comprising olefins.

Abstract: This invention comprises a method of producing ethylene rich product streams from a pressurized charge gas mixture of olefins and other components received from olefin generation/preparation processes. The method of this invention may eliminate the need for cryogenic fractional distillation and other special separation equipment operating at temperatures below -55.degree. F., and thus also potentially eliminate the refrigeration and heat exchange equipment needed to achieve those low temperatures. Alternatively, the method of this invention may eliminate the need for a circulating lean oil absorbant material, and thus also potentially eliminate the heat exchange equipment and reduces the refrigeration and fractional distillation load required to manage that material.

Abstract: The present invention is an improvement in the combined fractionation steps of deethanization and C2 splitting for ethylene and ethane separation. Theoretical stages are added to the rectification section of a deethanizer above a liquid or vapor sidedraw. Polymer grade ethylene product up comprising to 30 percent of the ethylene in the deethanizer feed is obtained in an overhead stream according to the present invention. Lesser recovery at the same ethylene purity or higher recovery at lower ethylene purity are obtained varying recovery or numbers of additional stages in the rectification. An overall reduction in total cold utilities for the overhead condensers for the deethanizer and downstream C2 splitter are obtained in practicing the present invention.

Abstract: A process for the recovery of ethane, ethylene, propane, propylene and heavier hydrocarbon components from a hydrocarbon gas stream is disclosed. The stream is divided into first and second streams, and the second stream is expanded to the fractionation tower pressure and supplied to the column at a mid-column feed position. A recycle stream is withdrawn from the tower overhead after it has been warmed and compressed, and is combined with the first stream. The combined stream is cooled to condense substantially all of it, and is thereafter expanded to the fractionation tower pressure and supplied to the fractionation tower at a top column feed position. The pressure of the compressed recycle stream and the quantities and temperatures of the feeds to the column are effective to maintain the column overhead temperature at a temperature whereby the major portion of the desired components is recovered.

Abstract: The present invention provides an improved method for recovering high purity olefins from cracked gas effluents or other parafin/olefin gaseous mixtures by use of a chemical absorption process.

Abstract: In a cryogenic condensation scheme used for benzene removal in a process for liquefying natural gas, two series connected separation columns are provided with a feedstream precooled in a heat exchanger to a temperature that will at least condense the benzene component. In the first column, benzene is absorbed and vapor/liquid is separated with the liquid passed to the second column. The second column provides an overhead vapor stream conserved for processing to LNG, and a bottoms stream comprising NGL. The cooling for condensation of gaseous feed in the heat exchanger is controlled by automatically manipulating bypass flow around the heat exchanger responsive to measured vapor flow from the second separation column. Accordingly, the amount of liquid condensed is responsive to the flow rate of vapor withdrawn overhead from the second separation column.

Abstract: The present invention provides one or more sidedraws, from the stripping section of a column, of a heavy key component in the presence of a desirable heavier than heavy key component. In addition, the present invention provides one or more sidedraws, from the rectification section of a column, of a light key component in the presence of a desirable lighter than light key component. In prior art columns, an inherent remixing of the components to be separated in downstream columns occurs near the top or bottom of refluxed or reboiled columns respectively. In the prior art, a re-separation of the remixed components from an upstream column must be done in downstream columns. The present invention eliminates or reduces, according to desired optimization, the remixing by removal of the heavy or light key components in the sidedraw stream.

Abstract: The present invention is an improvement in the combined fractionation steps of deethanization and C2 splitting for ethylene and ethane separation. Theoretical stages are added to the rectification section of a deethanizer above a liquid or vapor sidedraw. Polymer grade ethylene product up comprising to 30 percent of the ethylene in the deethanizer feed is obtained in an overhead stream according to the present invention. Lesser recovery at the same ethylene purity or higher recovery at lower ethylene purity are obtained varying recovery or numbers of additional stages in the rectification. An overall reduction in total cold utilities for the overhead condensers for the deethanizer and downstream C2 splitter are obtained in practicing the present invention.

Abstract: Olefins are recovered from thermally cracked gas or fluid catalytic cracking off gas by cooling the gas to condense a portion of the hydrocarbons, removing hydrogen from the noncondensed gas, and condensing the remaining hydrocarbons in a cold condensing zone using a dephlegmator which operates above about -166.degree. F. This mode of operation minimizes the amount of methane in the condensate which is further processed in demethanizer column(s) and permits the condensation of ethylene at warmer temperatures than possible using a partial condenser in the cold condensing zone. The use of a dephlegmator at temperatures above about -166.degree. F. minimizes or eliminates the formation and accumulation of unstable nitrogen compounds in the ethylene recovery system. Hydrogen is removed from the noncondensed gas in a process selected from polymeric membrane permeation, adsorptive membrane permeation, or pressure swing adsorption.

Abstract: The present invention is a process of high efficiency rectification zone separation of cracked or other ethylene-containing gas chilled primarily by two closed mixed refrigerant loops and at least part of the dephlegmated overhead gas. The composition of the mixed refrigerants is optimally chosen to obtain an extremely close approach between the process condensation temperatures in the high efficiency rectification zone and the temperature of the chilling streams. An approach of about 3.degree. F. to 8.degree. F. can be achieved for the full condensation curve in the high efficiency rectification zone operating with either ethane or naphtha derived cracked gas. Highly reliable and stable operation is obtained by closed refrigeration loops in the present invention, in addition to reducing high efficiency rectification zone design cost.

Abstract: A process, apparatus and control methodology for transferring loads between drivers in adjacent refrigeration cycles in a cascaded refrigeration process has been developed thereby enabling more efficient driver operation. Load transfer is effected by cooling the higher boiling point refrigerant liquid prior to flashing via an indirect heat transfer with the lower boiling point refrigerant vapor in a adjacent cycle prior to compression of said stream.

Abstract: A process for the high-yield recovery of ethylene and heavier hydrocarbons from the gas produced by pyrolysis of hydrocarbons in which the liquid products resulting from the fractionated condensation of a cracking gas for the recovery of almost all the ethylene, are supplied to a distillation column, called a de-ethanizer, at different intermediate levels. At the top of the de-ethanizer the vapor of the column distillate is treated directly in an acetylene hydrogenation reactor, the effluent containing virtually no acetylene being separated by a distillation column called a de-methanizer, into an ethylene- and ethane-enriched tail product, while the head product is recycled by compression or treated for subsequent recovery of ethylene.