Method for stopping purifying column

• US 20020027067A1
• Filed: 07/09/2001
• Published: 03/07/2002
• Est. Priority Date: 07/21/2000
• Status: Active Grant

• Current Assignee: Nippon Shokubai Company Limited
• Original Assignee: Nippon Shokubai Company Limited
• Inventors: Matsumoto, Yukihiro, Nakahara, Sei, Hamamoto, Kei, Inada, Misao
• Granted Patent: US 6,613,196 B2
• Time in Patent Office: Days
• US Class Current: 203/8
• CPC Class Codes: B01D 3/14 Fractional distillation or use of a fractionation or rectification column
• CPC Class Codes: B01D 3/343 the substance being a gas
• CPC Class Codes: C07C 51/44 by distillation
• CPC Class Codes: C07C 57/04 Acrylic acid; Methacrylic acid
• CPC Class Codes: Y10S 203/07 Start up or shut down
• CPC Class Codes: Y10S 203/22 Accessories

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.

Claims

1. A method for stopping a purifying column handling an easily polymerizing compound-containing solution, characterized by lowering the inner oxygen concentration of said column below the limit of oxygen concentration by supplying an inert gas to said 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.

2. A method according to claim 1, wherein said inert gas is a gas having an oxygen concentration below said limit or nitrogen gas.

3. A method according to claim 1, wherein nitrogen gas is supplied as an inert gas till at least 20 vol. % of the total inner volume of said column and then air is supplied.

4. A method according to claim 1, wherein the interior of said column is further cooled at a rate in the range of 0.01 to 10°

C./min.

5. A method according to claim 4, wherein the interior of said column is cooled by the supply of an inert gas or a reflux liquid.

6. A method according to claim 5, wherein said ref lux liquid contains a polymerization inhibitor.

7. A method according to any of claims 1 to 6, wherein said easily polymerizing compound is (meth)acrylic acid or an ester thereof.