Davy International Aktiengesellschaft

Davy Powergas Gmbh

Davy Mckee Aktiengesellschaft

Gerhard Keunecke

Herbert Krimphove

Lars Hellmer

Lothar Sterck

Anton Klopfer

Ghazi R Al-Muddarris

Adolf Stauffer

Rainer Lell

Reinhard Pachaly

Manfred Albers

V Rao Vangala

A process is provided for the continuous separation of slightly volatile components from a crude phthalic acid anhydride wherein a portion of the crude phthalic acid anhydride is compressed and heated before being reintroduced into a flash evaporator.

Process for the continuous separation of slightly volatile components

A process is provided for the production of hydrogen and sulphur from a gas containing hydrogen sulphide. Such a process comprises passing the gas through a cracking zone at a temperature of from about 850.degree. C. to 1600.degree. C., cooling the cracked gas to a temperature of from about 110.degree. C. to 150.degree. C., and separating the condensed elemental sulphur. The uncracked hydrogen sulphide is separated and returned to the cracking zone; the remaining gas is withdrawn as hydrogen-rich gas.

Process for producing hydrogen and sulphur from hydrogen sulphide

Phthalic anhydride is continuously separated from the reaction gas mixture formed by the catalytic oxidation of o-xylene and/or naphthalene, by treating said rection gas mixture in at least two absorption stages with organic absorbents. The absorbent employed in the first absorption stage is a mixture of phthalic anhydride and benzoic acid. The absorbent employed in the subsequent absorption stage(s) contains maleic anhydride and may also contain phthalic anhydride.

Process for continuously separating phthalic anhydride from the reaction

In a process for the production of phthalic anhydride comprising a stage of catalytic oxidation of a mixture of o-xylene or naphthalene and air, a stage of separation of the crude phthalic anhydride from the reaction gas by cooling, and a stage of purification of the crude phthalic anhydride by rectification under vacuum, said vacuum being maintained by at least one jet pump, the improvement which comprises employing compressed air as the operating medium for said jet pump, and recycling resultant compressed air loaded with the exhaust gas to a process gas upstream of the phthalic anhydride separation stage, said process gas being any gas leading to the separation stage, preferably the gas between the oxidation stage and the separation stage.

Jet pump exhaust recycle in production of phthalic anhydride

An improved process is provided for the recovery and storage of maleic anhydride from maleic anhydride-containing gases. Such gases are scrubbed with a water or maleic acid scrubbing solution in a scrubbing zone to form a maleic acid-containing solution. This maleic acid-containing solution is then concentrated and dehydrated in an evaporation zone and a dehydration zone, respectively, to form maleic anhydride. The maleic anhydride so formed is then purified by distillation in a distillation zone. The evaporation, dehydration, and distillation steps are all carried out under a vacuum maintained by withdrawing gases containing organic and water vapor from said evaporation, dehydration and distillation zones using jet pumps propelled by pressurized air. The vapor-containing gases so removed are admixed with the pressurized air pump propellant streams, and this mixture is then introduced into the scrubbing zone for the maleic anhydride-containing gases. Vapor-containing gases may also be sucked by the jet pumps from maleic anhydride storage vessels, and such vapor-containing gases may also then be introduced into the scrubbing zone.

Process for the recovery of maleic anhydride from gases containing

A process for utilization of the reaction heat generated by the catalytic oxidation of o-xylene with air to phthalic anhydride in a tubular reactor, which heat is partially carried away from the reactor by the reaction gas and partially by fused salt used as a cooling medium. Water is heated by heat exchange with the hot reaction gas, evaporated by heat exchange with the fused salt and the steam is superheated and expanded in a condensation turbine coupled with the feed air compressor. The hot reaction gas is used successively to heat, or evaporate, a heat carrier liquid serving for the heating of the phthalic anhydride distillation, and the pressurized water. Low pressure steam can be generated by heat exchange of pressurized water with the reaction gas and used for heating the feed air and/or o-xylene. Preferably, the evaporation and superheating of the heated pressure water is effected in two fused salt cooling stages; the compressed air is successively heated by heat exchange with low pressure steam generated by cooling of the reaction gas and with the high pressure steam generated by cooling of the fused salt; and, the heating liquid and the pressurized water are heated in a two-stage heat exchanger.

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Geyen, Germany

Gerhard Keunecke