Patent ID: 8664437

Claim:
A process for producing (meth)acrylic acid, comprising the step of repeating a crystallization operation n times, wherein n is an integer of 2 or more, to produce purified (meth)acrylic acid from crude (meth)acrylic acid, wherein a (meth)acrylic acid solution is crystallized and the crystallized (meth)acrylic acid is melted to obtain a (meth)acrylic acid melt in the crystallization operation; wherein a constant amount A k of the (meth)acrylic acid solution is subjected to the k th crystallization operation, wherein k is an integer 1 or more and n−1 or less, and the (meth)acrylic acid melt obtained by the k th crystallization operation is utilized as the (meth)acrylic acid solution for the k+1 th crystallization operation without being discharged from a crystallizer or is transferred from the crystallizer to a k+1 th storage tank for storing the (meth)acrylic acid solution to be used in the k+1 th crystallization operation in accordance with the following Rules (1) or (2): Rule (1): when an amount of the (meth)acrylic acid melt obtained by the k th crystallization operation is B k and an amount of the (meth)acrylic acid solution stored in the k+1 th storage tank is A k+1 −B k or more, the (meth)acrylic acid melt obtained by the k th crystallization operation is not discharged from the crystallizer and the (meth)acrylic acid solution from the k+1 th storage tank is added to the (meth)acrylic acid melt obtained by the k th crystallization operation to be utilized as the (meth)acrylic acid solution for the k+1 th crystallization operation; and Rule (2): when the amount of the (meth)acrylic acid solution stored in the k+1 th storage tank is less than A k+1 −B k , the (meth)acrylic acid melt obtained by the k th crystallization operation is transferred to the k+1 th storage tank from the crystallizer.