Abstract: A method for effective preventing polymerization of acrylic acid during an azeotropic dehydration distillation in an acrylic acid manufacturing process and thus enabling an stable operation of the azeotropic dehydration column over an extended period of time. A method for preventing the polymerization of acrylic acid in an acrylic acid production process, wherein acrylic acid is separated in an azeotropic dehydration column from an acrylic acid aqueous solution fed therein, the method comprising withdrawing from the bottom of the azeotropic dehydration column a bottom effluent containing 50% or more of glyoxal (including the hydrates thereof) contained in the acrylic acid aqueous solution fed into the azeotropic dehydration column.

Abstract: A method for the absorption of (meth)acrylic acid and/or (meth)acrolein and an apparatus thereof which, in an absorption column adapted to cause an (meth)acrylic acid and/or (meth)acrolein-containing gas obtained in consequence of catalytic gas phase oxidation to come into countercurrent contact with a solvent, contemplate using a packing of relatively high efficiency in absorption disposed on the upstream side of the flow of a liquid containing the solvent and a packing and/or trays of relatively low performance of forming polymerization disposed on the downstream side thereof, in the column.

Abstract: A method for inhibiting polymerization during transportation, storage and/or production of (meth)acrylic acid or an ester thereof includes adding an N-oxyl compound and water to a vinyl compound; or dissolving an N-oxyl compound in water and adding the solution to a vinyl compound in a process of recovering, purifying, and/or synthesizing of the vinyl compound. The method can effectively inhibit polymerization of the vinyl compound.

Abstract: The present invention provides a column treating method by use of a distillation column and so on, which method enables to effectively remove solid impurities such as precipitates and polymers contained or produced in a treating fluid, and to thereby stably operate the column treatment. Solid impurities in a treating fluid can be removed by carrying out: step (a) of drawing out the treating fluid from a drawing out outlet (16) at the column bottom of the treatment column (10) outside the treatment column (10), step (b) of removing solid impurities from the treating fluid, drawn out in step (a), by a strainer (40), and step (c) of returning the treating fluid, from which the solid impurities are removed in step (b), to a returning inlet (18) of the treatment column, with advancing physical and/or chemical treatment of the treating fluid in the treatment column (10).

Abstract: A method for the decomposition of a Michael type adduct of an acrylic acid and/or an acrylic ester represented by the following formula [I] or [II] is disclosed, wherein decomposing the Michael type adduct in the presence of at least one copper salt and at least one metal salt selected from the group consisting of an alkali metal salt and an alkaline earth metal salt into an acrylic acid and/or an acrylic ester and/or an alcohol.

Abstract: A distillation apparatus is provided with a distillation tower, a reboiler, a bottom outflow pipe for drawing a liquid from the bottom of the distillation tower, and a pot provided between the bottom of the distillation tower and the bottom outflow pipe. A part of the drawn liquid is discharged to the outside of the distillation apparatus while the rest is flowed to the reboiler. The pot has a cross-sectional area smaller than a cross-sectional area of the distillation tower and larger than a cross-sectional area of the bottom outflow pipe.

Abstract: This method of preventing polymerization of methacrylic acid inn the process of its production is characterized by comprising using, in a refining column, a combination of N-nitrosophenylhydroxylamine or salt thereof with an N-oxyl compound, an N-hydroxy-,2,2,6,6-tetramethylpiperidine compound and a 2,2,6,6-tetramethylpiperidine compound. In this method, N-nitrosophenylhydroxylamine or a salt thereof rises inside a refining column under splitting part thereof to effectively inhibit polymerization of (meth)acrylic acid or the like. The above polymerization in both vapor and liquid phases can be inhibited more effectively by the combined use of the compounds mentioned above.

Abstract: According to the present invention, a tank for storing an easily polymerizable compound, the tank fitted with a liquid inlet pipe 3, a liquid draw-off pipe 4 and a liquid recirculating pipe 5, is characterized in that, assuming terminal ends of the individual pipes 3-5 are located at the same height, the apex angle formed by a line joining the central points of the end openings of the pipe 3 and the pipe 4 at the central point of a horizontal cross section of the tank, or the apex angle formed by a line joining the central points of the pipe 5 and the pipe 4 at the central point of the horizontal cross section of the tank, is equal to or larger than 90°. A method of storing an easily polymerizable compound of the invention utilizes the aforementioned tank for storing the polymerizable compound.

Abstract: In an apparatus provided with a plate type heat exchanger as a heater and/or a cooler and operated to treat a gas containing an easily blocking substance, a method for preventing the plate type heat exchanger from being blocked is disclosed which is characterized by i) setting the width of a flow path on a plate of the plate type heat exchanger in the apparatus in a range of 6-25 mm and ii) setting the average flow rate of the gas passing the plate type heat exchanger in the apparatus per unit cross-sectional area of the flow path on the plate in the range of 3-15 m/s. In the exchange of heat of an easily blocking substance by the use of a plate type heat exchanger, a method for preventing the plate type heat exchanger from blockage is disclosed which has the plate type heat exchanger provided in the port for introducing a gas containing an easily blocking substance with a gas dispersion plate.

Abstract: A storing device is disclosed having a gas-sealing device and/or a heating device provided for a pipe connecting a storing tank for an easily polymerizable and/or coagulating liquid substance and a liquid sealing implement-protecting device. A method for the control of the pressure in the storing device is also disclosed. This invention contemplates protecting a storing device against deformation and fracture.

Abstract: An apparatus for the preparation and supply of a polymerization inhibitor which constantly effects stable supply of a polymerization inhibitor solution adjusted to a prescribed concentration and enables a compound handled at the next step to be prevented from polymerization is provided. The apparatus for the preparation and supply of a polymerization inhibitor has at least two tanks and a stirring device, a liquid level detector, a polymerization inhibitor input port, a concentration-adjusting liquid input port, and a polymerization inhibitor solution feed opening, each being installed in at least one of said tanks.

Abstract: A method and apparatus for preventing contamination of a substrate or a substrate surface, and particularly relates to prevention of contamination of raw materials, semi-finished products, base materials of products and substrate surface in a high-tech industry such as in the production of semiconductors and liquid crystals. A gas coming into contact with a base material or substrate is purified by dust removing means and adsorption and/or absorption means so that the concentration of fine particles in the gas is below class 1,000 and a non-methane hydrocarbon concentration is below 0.2 ppm. Thereafter, the base material or the substrate surface is exposed to this gas.

Abstract: An object of this invention is to provide a method for producing acrylic acid that enables to suppress adverse influence of byproducts during distillation and to accomplish long-term continuous operation of the acrylic acid production apparatus. This invention is directed to a method for producing (meth)acrylic acid comprising the step of isolating (meth)acrylic acid from a liquid containing (meth)acrylic acid by distillation wherein the liquid contains glyoxal (including its hydrate) in a concentration of 0.1 mass % or less.

Abstract: This invention relates to a method for preventing (meth)acrylic acid from polymerizing during the course of distillation. The method provides for refining (meth)acrylic acid by a procedure including the steps of feeding a mixed gas obtained by catalytic gas phase oxidation of propylene and/or acrolein with a molecular oxygen-containing gas or a mixed gas obtained by catalytic gas phase oxidation of at least one compound of isobutylene, t-butyl alcohol, or methacrolein with a molecular oxygen-containing gas, to a (meth)acrylic acid collection column, collecting a (meth)acrylic acid-containing solution from the mixed gas, and feeding the (meth)acrylic acid-containing solution to a distillation column while maintaining the total concentration of aldehydes of 2-4 carbon atoms and acetone in the solution at a level of not more than 2000 ppm based on the amount of (meth)acrylic acid.

Abstract: A method for producing an organic acid and/or an organic acid ester which utilizes a steam system permitting stable production of an organic acid and/or an organic acid ester and realizing a high thermal efficiency constantly relative to the waste heat generated in the process of the production is provided. More particularly, this invention concerns a method for the production of an organic acid and/or an organic acid ester, wherein heat generated in the process for producing an organic acid and/or an organic acid ester is recovered in the form of steam, and the steam is used in any of the following forms: {circle over (1)} thermal energy, {circle over (2)} dynamic energy, and {circle over (3)} electrical energy in the process for producing an organic acid and/or an organic acid ester.

Abstract: A method for the decomposition of a Michael type adduct, characterized by causing a Michael type adduct to react in the presence of an N-oxyl compound thereby decomposing the Michael type adduct into acrylic acid and/or the acrylic ester and/or the alcohol and a method for the production of acrylic acid and/or the acrylic ester, characterized by comprising a step of recovering a Michael type adduct formed in the process for the production of acrylic acid or acrylic ester and a step of decomposing the recovered Michael type adduct by the method of decomposition mentioned above. This invention, therefore, allows promotion of efficient utilization of the raw materials.

Abstract: A perforated tray without downcomer having only a small deviation between the opening ratio based on the diameter of a column and the actual opening ratio and a perforated tray column without downcomer formed by disposing such perforated trays without downcomer are provided. The perforated trays without downcomer are characterized by having a ratio of (A)/(B) in the range of 1.1-1.5, wherein A denotes the opening ratio found from the standard pitch between centers of holes and (B) denotes the opening ratio based on the diameter of a column.

Abstract: The present invention provides a column treating method by use of a distillation column and so on, which method enables to effectively remove solid impurities such as precipitates and polymers contained or produced in a treating fluid, and to thereby stably operate the column treatment. Solid impurities in a treating fluid can be removed by carrying out: step (a) of drawing out the treating fluid from a drawing out outlet (16) at the column bottom of the treatment column (10) outside the treatment column (10), step (b) of removing solid impurities from the treating fluid, drawn out in step (a), by a strainer (40), and step (c) of returning the treating fluid, from which the solid impurities are removed in step (b), to a returning inlet (18) of the treatment column, with advancing physical and/or chemical treatment of the treating fluid in the treatment column (10).

Abstract: A method for producing an unsaturated carboxylic ester is provided, which can prevent the raw material compounds and the product of the reaction from splashing and adhering on the inner wall of the reaction vessel and succumbing to polymerization on the inner wall. Specifically, it is characterized by the fact that the difference between the outer periphery of the reaction vessel heated by the heating means and the reaction solution in temperature is not higher than 80° C.

Abstract: The present invention provides an apparatus for producing (meth)acrylic acid and a process for producing (meth)acrylic acid with this apparatus wherein the apparatus enables to produce (meth)acrylic acid stably for a long period of time by effectively inhibiting the polymerization of (meth)acrylic acid in its production process (for example, in a reboiler). At least a part of the apparatus is made of a nickel-chromium-iron alloy with a molybdenum content of 3 to 20 mass %, but not including 3 mass %, or with a molybdenum content of 1 to 4 mass % and a copper content of 0.5 to 7 mass %.