Abstract: A method for producing polyacrylic acid includes a combined process of an acrylic acid production process and a polyacrylic acid production process. The acrylic acid production process includes the steps of catalytically oxidizing propylene and/or propane in a gaseous phase to generate reaction product, absorbing the reaction product in a solvent, and purifying acrylic acid from an acrylic acid aqueous solution containing the solvent by purification. The polyacrylic acid production process includes the step of utilizing heat medium recovered in the acrylic acid production process to purify polyacrylic acid from the acrylic acid aqueous solution or from acrylic acid.

Abstract: A shell-and-tube heat exchanger for handling an easily polymerizable substance is disclosed, which is characterized by having no part for stagnation of said process fluid on the surfaces for contact with the process fluid. By eliminating undulations from the inner surfaces of the heat transfer tubes, it is made possible to prevent the easily polymerizable substance from polymerizing and, at the same time, prevent adhesion of a polymer to the surfaces. Thus, the efficiency of heat exchange is enhanced and the protracted continuous operation is realized.

Abstract: A method for stopping a purifying column handling an easily polymerizing compound-containing solution is disclosed, which method is characterized by lowering the inner oxygen concentration of the column below the limit of oxygen concentration by supplying an inert gas to the column while the concentration of the gas of easily polymerizing compound is in the range of 100% to the lower limit of the flammable range in volume % of the purifying column or by further supplying a reflux liquid thereby cooling the interior of the column at a rate in the range of 0.01-10° C./min. This invention enjoys exceptionally high economic value in respect that it is capable of preventing the easily polymerizing compound from the occurrence of polymerization in the purifying column, precluding the interior of the purifying column from being clogged by adhesion of a polymer, and moreover avoiding the possibility of explosion.

Abstract: Disclosed is a process for treating wastes discharged from an acrylic acid production process and a consecutive polyacrylic acid production process in which at least one waste selected from the group consisting of waste oil, waste water, and waste gas from said acrylic acid production process, and waste water and/or waste gas from said polyacrylic acid production process are combusted simultaneously.

Abstract: This invention relates to a storage tank for a viscous oil containing easily polymerizable compounds. The storage tank of the present invention for storing viscous oil containing easily polymerizable compounds comprises a bottom plate, a side wall, a draw-off pipe and an inlet pipe. The bottom plate slopes downwardly toward the draw-off pipe, and an angle of downward inclination of the bottom plate is a gradient of at least 1/200. It becomes possible because of the storage tank to effectively prevent polymerization of easily polymerizable compounds contained in waste oil within the storage tank, and clogging of a pipe is suppressed considerably.

Abstract: The present invention provides an apparatus for handling an easily polymerizable compound such as (meth)acrylic acid which includes a tubular member that is furnished to a side wall of the apparatus and opened to the inside of the apparatus, specifically, for example, an apparatus and a method which effectively inhibit the polymerization of (meth)acrylic acid in a distillation column for (meth)acrylic acid wherein the distillation column has such as an inlet or outlet of gas or liquid, a manhole, or a tube into which an instrument is inserted. The tubular member (e.g. an inlet or outlet, a manhole, a tube into which an instrument is inserted) is set so as to have a downward gradient (&agr;) in the range of 3° to 70° toward the inside of the apparatus.

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: For use in a process for the production of (meth)acrylic acid comprising at least a step for the reaction of (meth)acrylic acid by catalytic gas phase oxidation and a step for the absorption thereof, a method for preventing an effluent gas pipe from blocking is disclosed, which method is characterized by causing part or the whole of the gas discharged from the step for absorption, while being circulated via the effluent gas pipe to the step for the reaction or being discarded, to be subjected to temperature elevation and application of pressure and/or mist separation. Particularly by setting the temperature of the waste gas from the absorption column at a level in the range of 30-70° C.

Abstract: A method of manufacturing (meth)acrylic acid includes:

Abstract: Medicinal compositions for oral use to be used as preparations for oral administration showing little scatter in the concentration of a compound, which is insoluble or slightly soluble in water and shows a CCR5 antagonism, or its salt in blood, having very high oral absorbability and being useful in preventing and treating various HIV infections in humans, characterized in that the above-described compound or its salt is dissolved or dispersed in a carrier containing at least one constituent selected from among amphipathic substances, alcohols and lipids.

Abstract: The object of this invention to provide an improved arrangement that enables to prevent adhesion of polymer on or around the inner wall of a purification apparatus directly equipped on the outer wall thereof with an attachment such as a support by suppressing local temperature lowering inside the apparatus due to the existence of the attachment. The present invention provides a purification apparatus comprising an attachment directly mounted on an outer wall of the apparatus; and a covering material made of a low heat conductive material which partly or entirely covers the outer wall of the apparatus, and which partly or entirely covers the attachment.

Abstract: A method of manufacturing (meth)acrylic acid includes: a reaction step of carrying out a catalytic gas-phase oxidation reaction; an absorbing step of absorbing (meth)acrylic acid from a (meth)acrylic-acid-containing mixed gas prepared in the reaction step; a refinement step of separating, refining, and recovering (meth)acrylic acid from a (meth)acrylic-acid-containing liquid prepared in the absorbing step; and a recirculation step of recirculating (meth)acrylic acid contained in a vent gas produced in the refinement step to the absorbing step and/or the refinement step.

Abstract: This invention concerns a method for absorbing acrylic acid, characterized by supplying an acrylic acid-containing reaction gas component obtained by the reaction of catalytic gas phase oxidation to an acrylic acid absorption column and advancing a high boiling inert hydrophobic organic liquid into counter-flow contact with said reaction gas in said acrylic acid absorption column with the mass flow rate of the organic liquid fixed in the range of 0.2-7.0 times the mass flow rate of the acrylic acid in the reaction gas thereby absorbing acrylic acid in said organic liquid and obtaining an acrylic acid-containing solution including a low boiling substance in the range of 0.7-7.5 wt % based on the weight of bottom liquid of absorption column.

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: A shell-and tube reactor including at least one reaction tube with a measuring means, substantially same solid particles being filled in the reaction tubes with or without the measuring means, a length of the filled solid particle layer, and a pressure drop thereof while passing a gas through the reaction tube, per each reaction tube, being substantially the same, respectively. By measuring the temperature of the catalyst particle layer, such a temperature as a representative can be gasped.

Abstract: A solid substance removing device comprising a body provided with a fluid inlet pipe and a fluid outlet pipe and a filtering part disposed between the fluid inlet pipe and the fluid outlet pipe inside said body, the filtering part having (a) a thickness in the range of 5-500 mm, (b) a percentage of voids in the range of 60-99.5 vol. %, and (c) a contact surface area in the range of 100-2000 m2/m3. Owing to the construction described above, it is made possible to facilitate removal of the solid substance and, at the same time, prevent new generation of a polymer during the production of an easily polymerizing substance.

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 %.

Abstract: A method for distilling a raw material liquid containing (meth)acrylic acid substantially free from azeotropic solvents, collected with a collection agent from a mixed gas obtained by gas phase catalytic oxidation reactions which includes feeding to a distillation column the raw material liquid which temperature is substantially equal to that of the entrance place in the column.

Abstract: The present invention provides a process for producing a water-absorbent resin of which the residual monomer content and the extractable content are low. The process for producing a water-absorbent resin comprises the step of polymerizing at least one monomer component including acrylic acid and/or its salt as major components to produce a water-absorbent resin that is a neutralized salt, and this process is characterized in that the acrylic acid is a product obtained by catalytic gas phase oxidation of propylene and/or propane and has a protoanemonin content of not more than 10 ppm, and in that the resultant water-absorbent resin has a neutralization ratio of not less than 50 mol %.