Method for controlling fresh water generation apparatus by estimating filtration property, method for determining presence of trouble in fresh water generation apparatus, fresh water generation apparatus, program for operating fresh water generation apparatus, program for determining presence of trouble in fresh water generation apparatus, and recording medium

Patent metadata

Field	Value
Publication number	US-12415736-B2
Application number	US-202117798982-A
Country	US
Kind code	B2
Filing date	Feb 12, 2021
Priority date	Feb 14, 2020
Publication date	Sep 16, 2025
Grant date	Sep 16, 2025

Abstract

The present invention relates to a method of controlling a fresh-water production apparatus for treating a raw water in stages by N-stage (N is a natural number of 2 or larger) water treatment methods, the method including: a filtration-characteristic prediction step; a filtration-characteristic deviation assessment step; a filtration-characteristic deviation assessment step; a cyclic prediction calculation step; a control condition recording step; a cyclic prediction calculation step; and a control condition recording step, in which the fresh-water production apparatus is controlled on the basis of the control condition recording step for the (n−1)-th stage water treatment method and the control condition recording step for the n-th stage water treatment method.

First claim

The invention claimed is:

1. A method of controlling a fresh-water production apparatus for treating a raw water in stages by N-stage (N is a natural number of 2 or larger) water treatment methods, the method comprising:
a filtration-characteristic prediction step for an n-th stage (n is any natural number of 2 to N) water treatment method, wherein a filtration characteristic of the n-th stage water treatment method is predicted from a predicted input condition for the n-th stage;
a filtration-characteristic prediction step for an (n−1)-th stage water treatment method, wherein a filtration characteristic of the (n−1)-th stage water treatment method is predicted from a predicted input condition for the (n−1)-th stage;
a filtration-characteristic deviation assessment step for the n-th stage water treatment method, wherein a deviation between a predicted filtration characteristic of the n-th stage water treatment method and the filtration characteristic of the n-th stage water treatment method is assessed;
a filtration-characteristic deviation assessment step for the (n−1)-th stage water treatment method, wherein a deviation between a predicted filtration characteristic of the (n−1)-th stage water treatment method and the filtration characteristic of the (n−1)-th stage water treatment method is assessed; and
a step group A or a step group B,
wherein the step group A comprises:
a cyclic prediction calculation step for the (n−1)-th stage water treatment method, wherein when the deviation has occurred in the filtration-characteristic deviation assessment step for the (n−1)-th stage water treatment method, the predicted input condition for the (n−1)-th stage water treatment method is changed and a prediction calculation is repeated until the deviation between the predicted filtration characteristic of the (n−1)-th stage water treatment method and the filtration characteristic of the (n−1)-th stage water treatment method decreases to or below a specified value;
a control condition recording step for the (n−1)-th stage water treatment method, wherein a control condition for the (n−1)-th stage water treatment method is determined from a final input condition obtained in the cyclic prediction calculation step for the (n−1)-th stage water treatment method and is recorded;
a cyclic prediction calculation step for the n-th stage water treatment method, wherein the predicted input condition for the n-th stage water treatment method is changed on the basis of the control condition for the (n−1)-th stage water treatment method and a prediction calculation is repeated until the deviation between the predicted filtration characteristic of the n-th stage water treatment method and the filtration characteristic of the n-th stage water treatment method decreases to or below a specified value; and
a control condition recording step for the n-th stage water treatment method, wherein a control condition for the n-th stage water treatment method is determined from a final input condition obtained in the cyclic prediction calculation step for the n-th stage water treatment method and is recorded,
and wherein the step group B comprises:
a cyclic prediction calculation step for the n-th stage water treatment method, wherein when the deviation has occurred in the filtration-characteristic deviation assessment step for the n-th stage water treatment method, the predicted input condition for the n-th stage water treatment method is changed and a prediction calculation is repeated until the deviation between the predicted filtration characteristic of the n-th stage water treatment method and the filtration characteristic of the n-th stage water treatment method decreases to or below a specified value;
a control condition recording step for the n-th stage water treatment method, wherein a control condition for the n-th stage water treatment method is determined from a final input condition obtained in the cyclic prediction calculation step for the n-th stage water treatment method and is recorded;
a cyclic prediction calculation step for the (n−1)-th stage water treatment method, wherein the predicted input condition for the (n−1)-th stage water treatment method is changed on the basis of the control condition for the n-th stage water treatment method and a prediction calculation is repeated until the deviation between the predicted filtration characteristic of the (n−1)-th stage water treatment method and the filtration characteristic of the (n−1)-th stage water treatment method decreases to or below a specified value; and
a control condition recording step for the (n−1)-th stage water treatment method, wherein a control condition for the (n−1)-th stage water treatment method is determined from a final input condition obtained in the cyclic prediction calculation step for the (n−1)-th stage water treatment method and is recorded,
wherein the fresh-water production apparatus is controlled on the basis of the control condition recording step for the (n−1)-th stage water treatment method and the control condition recording step for the n-th stage water treatment method, and
wherein at least any of the N-stage water treatment methods is a membrane separation method and the membrane separation method employs at least one kind of a separation membrane selected from the group consisting of a microfiltration membrane, an ultrafiltration membrane, and a reverse osmosis membrane.

2. The method of controlling a fresh-water production apparatus according to claim 1 , further comprising an operation mode selection step for selecting an operation mode, wherein the input condition for filtration-characteristic prediction for each of the N-stage water treatment methods are changed on the basis of the operation mode selected in the operation mode selection step.

3. The method of controlling a fresh-water production apparatus according to claim 1 , wherein when the deviation has occurred simultaneously in the filtration-characteristic deviation assessment step for the (n−1)-th stage water treatment method and the filtration-characteristic deviation assessment step for the n-th stage water treatment method, the calculation of the control condition for the (n−1)-th stage water treatment method is preferential.

4. The method of controlling a fresh-water production apparatus according to claim 1 , wherein the fresh-water production apparatus has a treatment flow including any of the following:
some of a treated water obtained by the (n−1)-th stage water treatment method is mixed with a treated water obtained by the n-th stage water treatment method;
some of the treated water obtained by the n-th stage water treatment method is mixed with the raw water or with the treated water obtained by the (n−1)-th stage water treatment method;
some or all of a discharged water from the n-th stage water treatment method is mixed with the raw water or with the treated water obtained by the (n−1)-th stage water treatment method; and
some or all of the discharged water from the n-th stage water treatment method is used as a cleaning water for the (n−1)-th stage water treatment method.

5. The method of controlling a fresh-water production apparatus according to claim 1 , wherein the filtration characteristic is at least one kind of a parameter selected from the group consisting of differential pressure, pure-water permeability, and salt permeability.

6. The method of controlling a fresh-water production apparatus according to claim 1 , wherein when the (n−1)-th stage water treatment method is a membrane separation method employing a separation membrane which is a microfiltration membrane or an ultrafiltration membrane, then the control condition for the (n−1)-th stage water treatment method is at least one condition selected from the group consisting of the fo

Assignees

• Toray Industries

Inventors

• Tomioka Kazunori
• Hagawa Kazuki
• Hamada Hiroshi

Classifications

• C02F2303/16

  Regeneration of sorbents, filters · CPC title

• C02F2301/08

  Multistage treatments, e.g. repetition of the same process step under different conditions · CPC title

• C02F2209/44

  Time · CPC title

• C02F2209/006

  comprising a software program or a logic diagram · CPC title

• C02F2209/001

  Upstream control, i.e. monitoring for predictive control · CPC title