Method for producing ultrapure water and apparatus for producing ultrapure water

Abstract

The present invention provides a method and apparatus for producing ultrapure water that suppresses the temporary increase of iron (Fe), calcium (Ca), and fine particles in the water. [Solution] A method for producing ultrapure water, comprising a step of treating water to be treated with one or more water treatment devices and adjusting the temperature of the water to be treated, wherein the water treatment device includes a plate-type heat exchanger for adjusting the temperature of the water to be treated, the plate-type heat exchanger has a first frame 11 and a second frame 12 and a plurality of heat transfer plates 4 between the first frame and the second frame, and in the step of adjusting the temperature, a heat transfer medium is supplied to the plate-type heat exchanger, water to be treated is introduced from the first frame side and water to be treated is discharged from the second frame side to perform heat exchange with the heat transfer medium, and the differential pressure between the introduction pressure and discharge pressure of the water to be treated in the plate-type heat exchanger is 0.05 MPa or more and 0.3 MPa or less.

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