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A method for efficiently producing (meth)acrylic acid by crystallization using a plurality of crystallizers to purify (meth)acrylic acid and a refrigerator for supplying both of a cooling medium and a heating medium, while the refrigerator is stably operated for supplying media having a proper tempe

A method for efficiently producing (meth)acrylic acid by crystallization using a plurality of crystallizers to purify (meth)acrylic acid and a refrigerator for supplying both of a cooling medium and a heating medium, while the refrigerator is stably operated for supplying media having a proper temperature and the temperature of the crystallizers is maintained.

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1. A method for producing (meth)acrylic acid, comprising the steps of at least crystallizing (meth)acrylic acid and melting the (meth)acrylic acid crystal obtained in the crystallization step;wherein:two or more crystallizers are employed;(1) when the crystallization step and the melting step are co

1. A method for producing (meth)acrylic acid, comprising the steps of at least crystallizing (meth)acrylic acid and melting the (meth)acrylic acid crystal obtained in the crystallization step;wherein:two or more crystallizers are employed;(1) when the crystallization step and the melting step are concurrently carried out in separate crystallizers, a cooling medium is supplied to a crystallizer for carrying out the crystallization step to crystallize (meth)acrylic acid and a heating medium is supplied to the other crystallizer for carrying out the melting step to melt the (meth)acrylic acid crystal from a refrigerator; and(2) when the crystallization step is carried out before the melting step is carried out, the temperature of a heating medium to be returned to the refrigerator is decreased to be lower than a set temperature for the melting step before the crystallization step is carried out. 2. The method according to claim 1, wherein when only the melting step is carried out after completion of the crystallization step, a cooling load on the refrigerator is reduced in comparison with a cooling load for the crystallization step. 3. The method according to claim 1, wherein in (2), before the crystallization step is carried out, the temperature of the heating medium to be returned to the refrigerator is lowered in a range of not less than 5° C. and not more than 35° C. lower than the set temperature for the melting step. 4. The method according to claim 2, wherein when only the melting step is carried out, a cooling load on the refrigerator is set at a range of not less than 10% and not more than 40% of a rated capacity of the refrigerator. 5. The method according to claim 1, further comprising the steps of dehydrating glycerin or β-methylglycerin to obtain (meth)acrolein and oxidating the (meth)acrolein to obtain (meth)acrylic acid. 6. The method according to claim 1, further comprising the step of dehydrating hydroxypropionic acid or 2-methylhydroxypropionic acid to obtain (meth)acrylic acid. 7. A method for producing a hydrophilic resin, comprising the step of polymerizing a monomer component containing (meth)acrylic acid produced by the method according to claim 1. 8. A method for producing a water-absorbing resin, comprising the step of polymerizing a monomer component containing (meth)acrylic acid produced by the method according to claim 1. 9. The method according to claim 2, wherein in (2), before the crystallization step is carried out, the temperature of the heating medium to be returned to the refrigerator is lowered in a range of not less than 5° C. and not more than 35° C. lower than the set temperature for the melting step.