Mitsubishi Chemical Corporation

Mitsubishi Petrochemical Company Limited

Hirochika Hosaka

Shuhei Yada

Yoshiro Suzuki

Yasushi Ogawa

Kimikatsu Jinno

Masayasu Goriki

Kenji Takasaki

Yasuyuki Sakakura

Teruo Saito

Yasuhiko Samura

Mitsuo Nakamura

Masahiko Yamagishi

Kenji Yoshinaga

Toshiko Nakamura

An object of the present invention is to provide a method for vapor phase catalytic oxidation which is almost free of variations in reaction states in respective reaction tubes of the fixed bed multi-tube heat-exchanger type reactor. Provided is a method for vapor phase catalytic oxidation for obtaining a reaction product gas by using a fixed bed multi-tube heat-exchanger type reactor provided with a plurality of reaction tubes and by feeding a raw material gas inside the reaction tubes packed with a catalyst, wherein the method comprises: adjusting pressure losses of the respective reaction tubes so that the pressure losses of the respective reaction tubes after catalyst packing is within &#xb1;20% of an average pressure loss of the reaction tubes by: packing an inert substance at a raw material gas inlet portion of the reaction tubes or removing and re-packing the catalyst packed, for a reaction tube having a pressure loss lower than the average pressure loss of the reaction tubes; and removing and re-packing the catalyst packed, for a reaction tube having a pressure loss higher than the average pressure loss of the reaction tubes.

Method for vapor phase catalytic oxidation

In the stopping and starting operations of a distillation column used for producing (meth)acrylic acids according to the present invention, upon stopping the operation of the distillation column, the heating of a reboiler attached thereto is interrupted and then the reboiler is rapidly cooled; and/or upon starting the operation of the distillation column for production of the (meth)acrylic acids, an inner wall surface of the distillation column is heated to a temperature higher than a condensation temperature of the (meth)acrylic acids and the operation of the distillation column is started under the heated condition. According to the present invention, it is possible to early and safely stop the operation of the distillation column while preventing the occurrence of polymerization within the distillation column, and stably perform an operation for distillation of acrylic monomers for a long period of time.

Process for producing (meth)acrylic acids and process for distilling the same

An oxidation reactor includes a reactor body, a manhole nozzle projecting from the reactor body, and a partition plate separating an inside of the manhole nozzle and an inside of the reactor body from each other. In an oxidation reactor including the reactor body and a nozzle projecting from the reactor body, there is provided a means for feeding an inert gas into the nozzle. In a process for producing (meth)acrylic acids by subjecting propane, propylene or isobutylene to catalytic gas-phase oxidation reaction in an oxidation reactor for producing (meth)acrolein or (meth)acrylic acid, the above oxidation reactor is used as the oxidation reactor. In a method for analyzing an easily-polymerizable compound by introducing a gas containing the easily-polymerizable compound into an analyzing apparatus through a sampling tube, a double tube is used as the sampling tube, and a heating medium is fed into an outer tube of the double tube. According to these methods, the oxidation reaction can be stably conducted, and the reaction product gas can be prevented from being condensed and polymerized in the sampling tube, so that an on-line analysis can be performed at a high accuracy for a long period of time.

Oxidation reactor, process for producing (meth)acrylic acids, and method for analyzing easily-polymerizable compounds

A multitube reactor, wherein tubes having smaller tolerance between a nominal size and actual sizes are used as reaction tubes to stably perform a high yield reaction for a long period, a catalyst is filled into the reaction tubes so that the catalyst layer peak temperature portions of the reaction tubes are not overlapped with the connection sites thereof with baffles to effectively prevent hot spots from occurring and stably perform a reaction for a long period without the clogging of the reaction tubes, a heat medium and raw material gas are allowed to flow in the direction of a countercurrent and a specified type of catalyst is filled into the reaction tubes so that activity is increased from the inlet of the raw material gas to the outlet thereof to prevent the autooxidation of products so as to prevent equipment from being damaged due to the reaction, and, at the time of starting, gas with a temperature of 100 to 400&#xb0; C. is led to the outside of the reaction tubes to increase the temperature of the reaction tubes and, a heat medium, which is solid at the room temperature, is heated to circulate to the outside of the reaction tubes to efficiently start up the reactor without affecting the activity of the catalyst.

Multitube reactor, vapor phase catalytic oxidation method using the multitube reactor, and start up method applied to the multitube reactor

In an apparatus capable of distilling and refining an easily polymerizable substance, piping is performed so that when a strainer in action is switched to a backup strainer, the strainer can be switched after removing air in the backup strainer to replace air in the backup strainer with a discharge liquid of a pump. According to the apparatus, switching the strainers installed on an upstream side of the pump for extracting a liquid of a vacuum distillation column, which distills and refines the easily polymerizable substance, can be performed with no trouble during operation of the distillation column. When the apparatus includes a device for measuring a differential pressure between an upstream side and a downstream side of the strainer in action, two or more strainers installed in parallel can be switched at proper times and the easily polymerizable substance can be produced efficiently.

Apparatus and method for handling easily polymerizable substance, apparatus for extracting liquid from apparatus under reduced pressure, and process for producing easily polymerizable substance

The invention provides a process for producing and/or purifying acrylic acid or methacrylic acid or an ester of any of these, wherein mixtures of high-boiling heavy ingredients (high-boiling matter mixtures) discharged from individual step units are classified by the content therein of (meth)acrylic acid and/or of the dimer thereof and handled. According to the invention, even when high-boiling matters which have been discharged from distillation columns, high-boiling-matter cracking reactors, and the like in a plant for producing (meth)acrylic acid and/or an ester thereof and are alike in liquid nature are mixed with each other in the same tank, no polymer precipitation occurs. The handling and storage thereof are hence easy. Consequently, tanks can be united into one, and the process is extremely advantageous in reducing the construction cost and the area necessary for equipment.

Process for producing (meth)acrylic acid compound

The storage tank of the invention for an easily polymerizable compound is a storage tank having an acceptance piping and a delivery piping and is characterized by having a circulation line which directly connects the acceptance piping to the delivery piping or having circulation lines which respectively connect the acceptance piping to the storage tank and the storage tank to the delivery piping; the method of storing of the invention is characterized by storing an easily polymerizable compound in the storage tank while circulating the compound in the storage tank through the circulation line(s); the method of pipe jointing and apparatus therefor of the invention are a method of jointing pipes fitted to a handling apparatus in a production apparatus, storage apparatus, or the like for the purpose of transporting a corrosive liquid, the method being characterized in that the pipes are jointed with flanges, bolts, and nuts made of a material having resistance to corrosion by the corrosive liquid; the process for (meth)acrylic acid compound production of the invention is a process for producing and/or purifying a (meth)acrylic acid compound, and is characterized in that the temperature of a purified (meth)acrylic acid compound obtained which is being supplied to a storage tank is regulated so as to be not higher than the temperature of the purified (meth)acrylic acid compound residing in the storage tank; and the process of the invention for producing an easily polymerizable compound which is a (meth)acrylic acid compound is characterized in that the temperature of a (meth)acrylic acid compound-containing liquid which has been discharged as an off-specification product and is being supplied to a storage tank is regulated so as to be not higher than the temperature of the off-specification liquid stored in the storage tank.

Storage tank for easily polymerizable compound and method of storage

A storage tank for an easily polymerizable compound has acceptance piping and delivery piping with a circulation line directly connecting the acceptance piping to the delivery piping or with circulation lines respectively connecting the acceptance piping to the storage tank and the storage tank to the delivery piping. A method of storing an easily polymerizable compound in the storage tank includes circulating the compound in the storage tank through the circulation line(s), where the compound can be (meth)acrylic acid being produced and/or purified with the temperature of purified (meth)acrylic acid being supplied to or removed from the storage tank being regulated to not be higher than the temperature thereof in the tank. A method of joining pipes for-transporting a corrosive liquid using flanges, bolts, and nuts made of a material having resistance to corrosion by the corrosive liquid.

The present invention provides a process for catalytic vapor phase oxidation which prevents runaway reaction or early deterioration of a catalyst, in the production of (meth)acrylic acid or the like from propylene or isobutylene by the catalytic vapor phase oxidation process using a multi-tubular reactor, which can lead to the production thereof constantly in high yield for a long period of time. Further, the present invention provides a process for catalytic vapor phase oxidation wherein raw material gas is introduced for oxidation into reaction tubes of a multi-tubular reactor which is equipped with, as arranged within the shell of the reactor, a plurality of reaction tubes having a catalyst packed therein and a plurality of baffle plates for changing the direction of the flow of a heating medium introduced into the shell, characterized in that the temperature of the catalyst packed in a reaction tube which is not connected with at least one baffle plate is measured at plural points in the direction of an axis of the reaction tube.

Process for catalytic vapor phase oxidation

A method for transporting an easily polymerizable liquid by a pipeline having branches, wherein among pipelines branched at a branch point, one pipeline which may not be used over a long period of time, is provided with a valve to close the pipeline, within 500 mm from the branch point.

Method for transporting easily polymerizable liquid by pipeline

An object of the present invention is to provide a method of vapor phase catalytic oxidation which is capable of: efficiently removing heat of reaction; preventing the formation of hot spots; and efficiently providing a desired product. The invention provides a method of vapor phase catalytic oxidation of a substance to be oxidized with a gas containing molecular oxygen by means of a multitubular reactor, wherein the method comprises: performing a reaction of vapor phase catalytic oxidation under such conditions that a heat transfer coefficient of the heat medium isW/(m&#xb7;K) or higher.

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Yokkaichi, Japan

Hirochika Hosaka