Patents by Inventor Ramakrishnan Ramachandran
Ramakrishnan Ramachandran has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 5670125Abstract: A gas mixture comprised of nitric oxide and, optionally an inert gas, and containing small amounts of nitrogen dioxide, and perhaps moisture and sulfur dioxide, is purified by passing the gas stream through a bed of zeolite having a silica to alumina ratio not greater than about 200. The concentration of nitrogen dioxide, sulfur dioxide and moisture in the gas stream are reduced to about 1 ppm or less as the gas mixture passes through the bed of zeolite.Type: GrantFiled: September 25, 1995Date of Patent: September 23, 1997Assignee: The BOC Group, Inc.Inventors: Lien-Lung Sheu, Ramakrishnan Ramachandran, Theodore R. Galica
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Patent number: 5620501Abstract: Selected strongly adsorbed gaseous impurities are removed from a gas stream by pressure swing adsorption in an adsorption system which includes a single adsorption vessel, a gas storage vessel and a single gas pump. Feed gas is pumped at a selected adsorption pressure cocurrently through the adsorption vessel, which contains an adsorbent that selectively adsorbs the selected impurity or impurities. The less strongly adsorbed components of the gas mixture pass out the adsorption vessel through the nonadsorbed gas outlet end of the adsorption vessel. When the adsorbed gas front reaches a certain point in the adsorption vessel, the adsorption step is terminated and gas is countercurrently transferred from the adsorption vessel to a gas storage vessel, optionally with use of the gas pump. The adsorption vessel is then countercurrently evacuated by use of the pump and a selected gas-enriched product is recovered and sent to storage or further processed in downstream treatment operations.Type: GrantFiled: August 15, 1995Date of Patent: April 15, 1997Assignee: The BOC Group, Inc.Inventors: Satish S. Tamhankar, Ramakrishnan Ramachandran
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Patent number: 5565089Abstract: Coke deposits are removed from particulates by combustion in a regenerator by a process in which air is initially used as the oxidant. The combustion gas is subjected to a separation process to remove nitrogen therefrom, and the remaining carbon dioxide-enriched gas stream is recycled to the regenerator together while substantially pure oxygen is introduced into the regenerator. As the level of carbon dioxide in the system increases, the amount of air being introduced into the regenerator is gradually reduced and, in compensation, the amount of oxygen flowing to the regenerator is gradually increased. Eventually, part or all of the air is replaced by oxygen and carbon dioxide recycle gas, and the level of oxygen and carbon dioxide are regulated to maintain the desired temperature in the regenerator.Type: GrantFiled: September 30, 1994Date of Patent: October 15, 1996Assignee: The BOC Group, Inc.Inventors: Ramakrishnan Ramachandran, Raghu K. Menon
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Patent number: 5560817Abstract: Hydrocarbon fluid catalytic cracking (FCC) plants are debottlenecked by replacing air feed to the cracking catalyst regenerator with oxygen and carbon dioxide exhaust from the catalyst regenerator and removing methane and hydrogen from the wet gas stream leaving the main fractionator overhead receiver prior to its introduction into a wet gas compressor system. Nitrogen is removed from the exhaust gas and methane and hydrogen are removed from the wet gas in the same pressure swing adsorption (PSA) plant. During air replacement, exhaust gas is processed in the PSA plant and when the desired amount of nitrogen is removed from the exhaust gas, feed of exhaust gas to the PSA plant is terminated and flow of wet gas to the PSA plant is initiated.Type: GrantFiled: September 30, 1994Date of Patent: October 1, 1996Assignee: The BOC Group, Inc.Inventors: Raghu K. Menon, Ramakrishnan Ramachandran
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Patent number: 5532384Abstract: Hydrocarbon derivatives are produced by contacting a hydrocarbon with oxygen obtained from an air separation unit in the presence of a partial oxidation reaction catalyst. After separation of the hydrocarbon derivative from the reactor effluent, unreacted hydrocarbon is recovered from the effluent by adsorbing the unreacted hydrocarbon onto an adsorbent at superatmospheric pressure and removing the adsorbed hydrocarbon from the adsorbent by depressurizing said adsorbent and purging the adsorbent with nitrogen obtained from the air separation unit. The recovered unreacted hydrocarbon is recycled to the partial oxidation reactor.Type: GrantFiled: May 9, 1994Date of Patent: July 2, 1996Assignee: The BOC Group, Inc.Inventors: Arthur Shirley, Ramakrishnan Ramachandran
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Patent number: 5514204Abstract: A gas mixture comprised of nitric oxide and, optionally an inert gas, and containing small amounts of nitrogen dioxide, and perhaps moisture and sulfur dioxide, is purified by passing the gas stream through a bed of metal cation-free silica, alumina, or zeolite. The concentration of nitrogen dioxide, sulfur dioxide and moisture in the gas stream are significantly reduced as the gas mixture passes through the bed of adsorbent.Type: GrantFiled: July 7, 1994Date of Patent: May 7, 1996Assignee: The BOC Group, Inc.Inventors: Lien-Lung Sheu, Ramakrishnan Ramachandran, Theodore R. Galica
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Patent number: 5488185Abstract: An ethene stream which contains ethane as an impurity or a propene stream which contains propane as an impurity is hydrated with water vapor in the presence of a hydration catalyst to produce ethanol or isopropanol, respectively. After removal of the alcohol the gaseous product stream is subjected to adsorption, thereby producing an ethene-enriched stream or a propene-enriched stream. The ethene-enriched stream or the propene-enriched stream is recycled to the hydration reactor.Type: GrantFiled: April 22, 1994Date of Patent: January 30, 1996Assignee: The BOC Group, Inc.Inventors: Ramakrishnan Ramachandran, Loc H. Dao
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Patent number: 5470925Abstract: An ethylene stream which contains ethane as an impurity or a propylene stream which contains propane as an impurity is contacted with a polymerization catalyst thereby producing a polymer product containing unreacted ethylene or propylene and the corresponding alkane. A gas mixture containing ethylene or propylene and the corresponding alkane is separated from the polymer product and subjected to adsorption at a temperature of 50.degree. to 200.degree. C. in a bed of adsorbent which selectively adsorbs alkenes, thereby adsorbing substantially all of the propylene or ethylene from the gas mixture. The ethylene or propylene is desorbed from the adsorbent and recycled to the polymerization zone. The process is operated on a low per pass conversion with recycle of unreacted monomer. In the system of the invention the adsorption unit may be upstream or downstream of the polymerization reactor.Type: GrantFiled: April 22, 1994Date of Patent: November 28, 1995Assignee: The BOC Group, Inc.Inventors: Ramakrishnan Ramachandran, Loc H. Dao
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Patent number: 5468459Abstract: A per-fluorocarbon containing gas is treated by contacting per-fluorocarbon contained within the gas with calcium hydride at a temperature in a range of between about 450 and 900.degree. C. The calcium hydride can be contained in a bed mixed with silicon or calcium oxide and such bed can be used in conjunction with a downstream bed of calcium oxide to remove any hydrogen fluoride produced. Also, an upstream bed of calcium fluoride can be used to treat acid gases in case of semiconductor processing applications of the present invention.Type: GrantFiled: February 28, 1995Date of Patent: November 21, 1995Assignee: The BOC Group, Inc.Inventors: Satish S. Tamhankar, Ramakrishnan Ramachandran
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Patent number: 5466837Abstract: An ethylene stream which contains ethane as an impurity or a propylene stream which contains propane as an impurity is subjected to adsorption at a temperature of 50.degree. to 200.degree. C. in a bed of adsorbent which selectively adsorbs ethylene or propylene, thereby adsorbing substantially all of the ethylene or propylene. The purified ethylene or propylene stream is then subjected to partial oxidation in the presence of oxygen and, optionally ammonia to produce various partial oxidation products. The process is operated on a low per pass conversion with recycle of unreacted ethylene or propylene. In the system of the invention the adsorption unit may be upstream or downstream of the partial oxidation reactor.Type: GrantFiled: April 22, 1994Date of Patent: November 14, 1995Assignee: The BOC Group, Inc.Inventors: Ramakrishnan Ramachandran, Loc H. Dao
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Patent number: 5463137Abstract: A propylene stream which contains propane as an impurity is contacted with carbon monoxide and hydrogen in the presence of a hydroformylation catalyst thereby producing a product stream containing butyraldehyde and/or n-butyl alcohol, unreacted propylene and propane. A gas mixture containing propylene and propane is separated from the product stream and subjected to adsorption at a temperature of 0.degree. to 250.degree. C. in a bed of adsorbent which selectively adsorbs propylene, thereby adsorbing substantially all of the propylene from the gas mixture. The propylene is desorbed from the adsorbent and recycled to the reaction zone. The process is operated on a low per pass conversion with recycle of unreacted propylene. In the system of the invention the propylene adsorption unit may be upstream or downstream of the hydroformylation reactor.Type: GrantFiled: April 22, 1994Date of Patent: October 31, 1995Assignee: The BOC Group, Inc.Inventors: Ramakrishnan Ramachandran, Loc H. Dao
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Patent number: 5417742Abstract: Perfluorocarbons are recovered from gas streams by subjecting the gas stream to an adsorption process in a bed of one or more energetically homogeneous adsorbents such as silicon-rich adsorbents of the FAU structure, silicon-rich adsorbents of the BEA structure, silicon-rich adsorbents of the MOR structure. The adsorption process is preferably pressure swing adsorption or temperature swing adsorption.Type: GrantFiled: December 3, 1993Date of Patent: May 23, 1995Assignee: The BOC Group, Inc.Inventors: Satish S. Tamhankar, Ramakrishnan Ramachandran, Martin Bulow, Theodore R. Galica
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Patent number: 5365011Abstract: Method of separating a gaseous alkene from a gaseous alkane by a pressure swing adsorption process unit alone or in combination with the distillation column wherein the alkene is preferentially adsorbed onto a bed of 4A zeolite at a temperature of about 50.degree. to about 200.degree. C.Type: GrantFiled: May 5, 1993Date of Patent: November 15, 1994Assignee: The BOC Group, Inc.Inventors: Ramakrishnan Ramachandran, Loc H. Dao
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Patent number: 5322927Abstract: Polyolefins are produced by a process which includes the steps of: polymerizing an olefin in a reaction zone; removing unreacted olefin from the polymer in a flash chamber and recycling the unreacted olefin to the reaction zone; stripping unreacted olefin from the polymer by passing a stripping gas through the polymer in a stripping zone; passing the unreacted olefin from the stripping zone at superatmospheric pressure through an adsorbent which selectively adsorbs olefins; depressurizing the adsorbent to produce a substantially pure olefin and recycling the substantially pure olefin to the reaction zone; purging the adsorbent bed with a nonadsorbable gas to remove residual unreacted olefin from the adsorbent; and passing the purge gas-unreacted olefin to the stripping zone to be used as stripping gas.Type: GrantFiled: September 2, 1992Date of Patent: June 21, 1994Assignee: The BOC Group, Inc.Inventors: Ramakrishnan Ramachandran, Virginia Malik
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Patent number: 5278319Abstract: An improved process is provided for the production of a partial oxidation product by the vapor phase reaction of a hydrocarbon with substantially pure oxygen in the presence of a suitable catalyst. In the improved process, the partial oxidation product is removed, carbon dioxide and excess carbon monoxide, present in the reactor effluent as by-products, are also removed and the remaining gaseous effluent, comprised mainly of carbon monoxide and unreacted hydrocarbon, is recycled to the reactor. The concentration of carbon monoxide throughout the system is maintained sufficiently high to prevent the formation of a flammable mixture in the reactor or associated equipment.Type: GrantFiled: April 14, 1992Date of Patent: January 11, 1994Assignee: The BOC Group, Inc.Inventors: Ramakrishnan Ramachandran, Loc Dao, Donald L. MacLean
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Patent number: 5268497Abstract: A process for the production of an ethylenically unsaturated nitrile from a hydrocarbon feed stream comprised of a mixture of an alkene and an alkane by reaction with an oxygen-containing gas and ammonia. The alkene is converted to unsaturated nitrile by reaction with the oxygen and ammonia in the presence of a suitable catalyst in an ammoxidation reactor; the nitrile product is recovered from the product stream; some of the byproduct carbon oxides and some of the inert gas introduced into the system with the reactants are removed from product stream and the remainder of this stream, now rich in unreacted alkene and alkane, and containing the rest of the byproduct gases and inert gases is introduced into a reactor which contains a catalyst that causes alkane contained in the gas stream to convert to the corresponding alkene. The effluent from the dehydrogenation reactor is recycled to the ammoxidation reactor.Type: GrantFiled: February 24, 1992Date of Patent: December 7, 1993Assignee: The BOC Group, Inc.Inventor: Ramakrishnan Ramachandran
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Patent number: 5264608Abstract: A process for the production of an ethylenically unsaturated nitrile from a hydrocarbon feed stream comprised of a mixture of an alkene and an alkane by reaction with an oxygen-containing gas and ammonia. The alkene is converted to unsaturated nitrile by reaction with the oxygen and ammonia in the presence of a suitable catalyst in a first ammoxidation reactor; the nitrile product is recovered from the product stream; some of the byproduct carbon oxides and some of the inert gas introduced into the system with the reactants are removed from product stream and the remainder of this stream, now rich in unreacted alkene and alkane, and containing the rest of the byproduct gases and inert gases is introduced with additional oxygen-containing gas and ammonia into a second ammoxidation reactor which contains a catalyst that catalyzes reaction between the alkane, oxygen and ammonia to produce additional unsaturated nitrile.Type: GrantFiled: February 24, 1992Date of Patent: November 23, 1993Assignee: The BOC Group, Inc.Inventor: Ramakrishnan Ramachandran
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Patent number: 5262547Abstract: Petrochemicals are produced by the vapor phase reaction of a hydrocarbon with substantially pure oxygen in the presence of a suitable catalyst. In the improved process, the principal product is removed, carbon monoxide, present in the reactor effluent as a byproduct, is oxidized to carbon dioxide and part of the gaseous effluent, comprised mainly of carbon dioxide and unreacted hydrocarbon, is recycled to the reactor. Removal of carbon monoxide from the recycle stream reduces the hazard of a fire or explosion in the reactor or associated equipment. The use of carbon dioxide as the principal diluent increases heat removal from the reactor, thereby increasing the production capacity of the reactor.Type: GrantFiled: October 15, 1991Date of Patent: November 16, 1993Assignee: The BOC Group, Inc.Inventors: Ramakrishnan Ramachandran, Arthur I. Shirley, Lien-Lung Sheu
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Patent number: 5229089Abstract: A process for separating methane from an oxygen-containing gas mixture which contains methane at a concentration greater than the upper explosive gas mixture limit by pressure swing adsorption without producing an explosive gas mixture. The process includes the steps of feeding the gas mixture into an adsorber which contains an adsorbent which preferentially adsorbs methane until the desired production pressure is attained in the adsorber and then stopping the flow of feed gas into the adsorber and charging methane product gas at the production pressure cocurrently into the adsorber while simultaneously withdrawing nonadsorbed product gas from the nonadsorbed product end of the adsorber. The desorbed product stream is enriched in methane relative to the feed stream and the concentration of methane in the nonadsorbed product stream is less than the minimum flammable mixture concentration.Type: GrantFiled: November 6, 1991Date of Patent: July 20, 1993Assignee: The BOC Group, Inc.Inventors: Ramakrishnan Ramachandran, Arthur I. Shirley
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Patent number: 5179215Abstract: An improved process is provided for the production of a petrochemical by the vapor phase reaction of a hydrocarbon with an oxygen-containing gas in the presence of a suitable catalyst to produce a flammable gaseous product stream comprising the desired petrochemical, unreacted hydrocarbon, oxygen, carbon monoxide and carbon dioxide. In the improved process, a cooled or liquefied inert gas is injected as a quench fluid into the gaseous product stream exiting the hydrocarbon oxidation reactor, thereby cooling the stream to a temperature below the autoignition temperature of the flammable components of the stream, the petrochemical is recovered from the gaseous product and unreacted hydrocarbon is removed from the gaseous product and recycled to the reactor.Type: GrantFiled: February 27, 1991Date of Patent: January 12, 1993Assignee: The BOC Group, Inc.Inventors: Ramakrishnan Ramachandran, Donald L. MacLean