Air Products and Chemicals, Inc.

Lee J Howard

Howard C Rowles

Mark Julian Roberts

Christopher Francis Harris

Glenn E Kinard

Gene A Lucadamo

Richard Alan Wright

Robert Newton Davis

Randy James Nickel

Bruce Moodie Hill

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 stream 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.

Method for providing refrigeration to parallel heat exchangers

Dephlegmator system without headers, collectors, or distributors at the bottom end of feed circuits in plate and fin exchangers operating in condensing or rectifying service. Each dephlegmator is installed within a pressure vessel, thereby eliminating the need for headers, collectors, or distributors at the bottom end of the feed circuits. In an alternative embodiment of the invention, upper and lower segments of the pressure vessel are isolated by a mid-vessel seal between the vessel and dephlegmator walls, and headers or collectors are not required at the upper and lower ends of the feed circuits.

Dephlegmator system and process

C,and C,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.

Nitrogen refrigerated process for the recovery of C2&plus; Hydrocarbons

A high purity methane product is recovered from a feed gas mixture containing methane and one or more hydrocarbons heavier than methane by cooling, condensing, and rectifying the feed in a dephlegmator. The high purity methane product, containing at least 98 mole % methane, can be liquefied and stored for use as a fuel for internal combustion engines. A hydrocarbon product containing components heavier than methane is also recovered. Methane recovery and C.sub.2.sup.+ hydrocarbon product purity can be improved by the use of a combined stripping heat exchanger and feed gas cooler. External refrigeration is utilized and can be supplemented in part by autorefrigeration provided by vaporizing dephlegmator liquid.

Production of refrigerated liquid methane

Nitrogen is removed from a pressurized feed gas mixture containing nitrogen and methane by cooling, partial condensation, and rectification in one or more dephlegmators. Autorefrigeration is provided by pressure letdown of selected process streams and external refrigeration is not required.

Dephlegmator process for nitrogen removal from natural gas

Hydrocarbons are recovered from the product purge gas in an alkene polymerization process by absorption of heavier hydrocarbons from the purge gas by an intermediate hydrocarbon stream to yield a vapor rich in inert gas and alkene monomer. Alkene monomer is condensed and rectified by dephlegmation at low temperatures from the inert gas, flashed and vaporized to provide refrigeration for the condensation step, and recycled to the polymerization process. The intermediate hydrocarbon from the absorption step is recycled to the polymerization process. Optionally a portion of the inert gas is reused for purge gas.

Recovery of hydrocarbons from polyalkene product purge gas

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.

Olefin recovery from olefin-hydrogen mixtures

Hydrocarbons are recovered from the product purge gas in an alkene polymerization process by absorption of heavier hydrocarbons from the purge gas by an intermediate hydrocarbon stream to yield a vapor rich in inert gas and alkene monomer. Alkene monomer is condensed at low temperatures from the inert gas, flashed and vaporized to provide refrigeration for the condensation step, and recycled to the polymerization process. The intermediate hydrocarbon from the absorption step is recycled to the polymerization process. Optionally a portion of the inert gas is reused for purge gas.

A closed-loop mixed refrigerant cycle provides efficient low-level refrigeration for recovering ethylene from a mixed gas feed. Compressed mixed refrigerant vapor is condensed at -20.degree. F. to -50.degree. F. and is subcooled to -175.degree. F. to -225.degree. F. by indirect heat exchange with cold H.sub.2, methane, and expander streams from elsewhere in the ethylene plant. A portion of the subcooled refrigerant may be flashed to provide additional subcooling of the main mixed refrigerant stream. Subcooled mixed refrigerant is subsequently flashed to provide very low temperature level refrigeration for feed condensation and demethanizer overhead condenser duties. The invention allows advantageous operation of the feed chilling train at pressures between 150 and 400 psia.

Mixed refrigerant cycle for ethylene recovery

Refrigeration is provided in an ethylene recovery plant by an open-loop mixed refrigeration cycle which utilizes components present in the ethylene-containing feed gas as the mixed refrigerant. Refrigeration is provided by subcooled mixed refrigerant at -175.degree. to -225.degree. F. for the demethanizer overhead condenser and for initial cooling and condensation of the ethylene-containing feed gas. Overall ethylene recoveries of up to 99.9% can be achieved at reduced power consumption compared with conventional ethylene recovery cycles. In addition, significant capital savings can be realized due to the simplification of equipment with the open-loop mixed refrigerant cycle, which can be operated advantageously at pressures between 150 and 400 psia.

Open loop mixed refrigerant cycle for ethylene recovery

A closed-loop mixed refrigerant cycle provides efficient low-level refrigeration for recovering ethylene from a mixed gas feed. Compressed mixed refrigerant vapor is condensed at -20.degree. F. to -50.degree. F. and is subcooled to -175.degree. F. to -225.degree. F. by indirect heat exchange with cold H.sub.2, methane, and expander streams from elsewhere in the ethylene plant. A portion of the subcooled refrigerant may be flashed to provide additional subcooling of the main mixed refrigerant stream. Subcooled mixed refrigerant is subsequently flashed to provide very low temperature level refrigeration for feed condensation and demethanizer overhead condenser duties.

Refrigeration is provided in an ethylene recovery plant by an open-loop mixed refrigeration cycle which utilizes components present in the ethylene-containing feed gas as the mixed refrigerant. Refrigeration is provided by subcooled mixed refrigerant at -175.degree. to -225.degree. F. for the demethanizer overhead condenser and for initial cooling and condensation of the ethylene-containing feed gas. Overall ethylene recoveries of up to 99.9% can be achieved at reduced power consumption compared with conventional ethylene recovery cycles. In addition, significant capital savings can be realized due to the simplification of equipment with the open-loop mixed refrigerant cycle.

Ethylene-containing feed gas to a cryogenic ethylene recovery system is cooled and condensed, prior to fractionation, by an improved method which utilizes a combination of one or more partial condensers followed by one or more dephlegmators. The improved method simplifies heat exchange equipment and reduces capital cost, and is particularly suited for processing a pressurized precooled feed gas from ethane cracking which contains less than about 1 mole % of propane plus propylene.

Precooling for ethylene recovery in dual demethanizer fractionation

A process and apparatus for separating selected C.sub.4 olefinic products from combinations thereof with lower boiling point compounds comprises partially condensing a stream containing said products and compounds, atmospherically separating said partially condensed stream to yield gas and liquid streams, stipping said liquid stream to yield stripper overhead gas and stripper bottoms liquids, and recovering said C.sub.4 olefinic and paraffinic products from said stripper bottoms liquid, all at selected temperatures and pressures adapted to produce a high recovered percentage of said desired C.sub.4 olefinic and paraffinic product.

Method for olefinic separation

The invention provides a liquids recovery process useful for the separation and recovery of C.sub.3.sup.+ liquid hydrocarbons from gas mixtures containing high concentrations of lighter components such as are produced by the dehydrogenation of liquefied petroleum gases or by the catalytic cracking of heavy oils. The recovery process employs an absorption refrigeration cycle to supply high level refrigeration to the process; the absorption cycle utilizes low pressure steam or a heated fluid derived from secondary heat recovery of a process flue gas to effect heating in the absorption refrigeration cycle.

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Allentown, PA, United States of America

Lee J Howard