Abstract: A method for starting up a distilling column destined to handle an easily polymerizing compound-containing solution characterized by supplying at the start of the operation of the distilling column a polymerization inhibitor to the bottom liquid of the distilling column having a temperature of not higher than 80° C. Further, by supplying a reflux liquid through the top of the distilling column or the middle stage of the column prior to the start of the temperature elevation of the distilling column, thereby preventing the polymerization of the easily polymerizing compound more effectively.

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 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: 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: In the purification of an easily polymerizable compound such as (meth)acrylic acid by the use of a purification column adapted to withdraw a liquid from the middle portion of the column, a novel liquid withdrawing tray adapted to prevent the compound from polymerization effectively and permit the purification to be stably performed for a long time, a purification column using this tray, and a method for purifications using this purification column are provided. The liquid withdrawing tray for the purification column is composed of a liquid receiving plate and a liquid withdrawing tube for withdrawing the liquid from the liquid receiving plate.

Abstract: In the purification of an easily polymerizable compound such as (meth)acrylic acid by the use of a purification column adapted to withdraw a liquid from the middle portion of the column, a novel liquid withdrawing tray adapted to prevent the compound from polymerization effectively and permit the purification to be stably performed for a long time, a purification column using this tray, and a method for purifications using this purification column are provided. The liquid withdrawing tray for the purification column is composed of a liquid receiving plate and a liquid withdrawing tube for withdrawing the liquid from the liquid receiving plate.

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: A method for starting up a distilling column destined to handle an easily polymerizing compound-containing solution characterized by supplying at the start of the operation of the distilling column a polymerization inhibitor to the bottom liquid of the distilling column having a temperature of not higher than 80° C. Further, by supplying a reflux liquid through the top of the distilling column or the middle stage of the column prior to the start of the temperature elevation of the distilling column, thereby preventing the polymerization of the easily polymerizing compound more effectively.

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.