JPS60129103A - Apparatus for preparing extremely pure water - Google Patents

Abstract

PURPOSE:To prevent contamination of a membrane module and excessive increase of concentrated water and to control the quantity of water to be produced by controlling a valve for controlling the quantity of concentrated water depending on the returned quantity of the concentrated water and the discharged quantity of the concentrated water, and controlling also the number of revolution of a pressurizing pump. CONSTITUTION:Flow rate in a return pipe 10 of concentrated water and flow rate in a discharging pipe 11 of the concentrated water are measured with flowmeters 14, 15. The values of the total quantity of the concentrated water and the set value of the quantity of concentrated water operated by an operator 16 are compared, and the difference is outputted from a signal generator 17. The difference is controlled by the degree of opening of a control valve 11 for the quantity of the concentrated water by a controller 18. Necessary quantity of water to be produced is operated by an operator 21 by operating the quantity of extremely pure water to be used at use point 7 from the quantity in the feed water pipe 6 and return water pipe 8. The quantity of discharged water of the pressurizing pump 2 is measured and the difference between it and the necessary quantity of water to be produced is outputted from a signal generator 23. The number of revolution of the pressurizing pump 2 is controlled by a controller 24 basing on the difference signal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an ultrapure water production apparatus for the semiconductor manufacturing industry or the pharmaceutical bioindustry, and particularly to control of the amount of ultrapure water produced.

[Background of the invention]

FIG. 1 shows a system diagram of a typical ultrapure water production device, in which ions are removed and the ninth-order pure water is stored in an intermediate tank 1, is pressurized by a pressure pump 2, and is heated by a germicidal lamp 3. The resin is sent to an ion exchange resin tower 4, where fungi and ions are removed.

Next, the fine particles are filtered in an ultrapolar membrane module device (or reverse osmosis membrane module device) 5 to obtain ultrapure water.
The ultrapure water is sent to a use point 7 via a water supply line 6. Further, unused ultrapure water that has passed through the use point 7 is returned to the intermediate tank 1 via a return line 8. On the other hand, a part of the concentrated water in the ultrapolar membrane module device 5 is discharged to the outside via the concentrated water drainage line 9, and the remaining concentrated water is discharged through the concentrated water return line 10 to the intermediate temperature 1. will be returned to.

In this ultrapure water production equipment, when the amount of ultrapure water used at use point 7 changes, an operation is performed to control the amount of produced water from the perspective of energy saving, and generally the rotation speed of the pressure pump 2 is controlled. It has been adopted. The amount of produced water increases or decreases depending on the increase or decrease in the rotation speed of the pressure pump 2.

However, when the rotation speed of the pressurizing pump 2 is lowered to reduce the amount of water produced, the amount of concentrated water in the membrane module also decreases as the amount of water produced decreases, and the flow rate in the membrane module temporarily decreases, causing the amount of concentrated water to decrease. A problem arises in that the contained fine particles adhere to the membrane surface and contaminate the membrane. Furthermore, when increasing the number of revolutions of the pressure pump 20 to increase the amount of produced water, there is a problem that the amount of concentrated water increases as the amount of produced water increases.

[Important of invention]

An object of the present invention is to provide an ultrapure water production apparatus that does not cause contamination of membrane modules and can control the amount of produced water without increasing the amount of concentrated water.

[Summary of the invention]

In controlling the rotation speed of the pressure pump, if the amount of concentrated water is controlled to be constant, contamination of the membrane module and excessive amount of concentrated water can be prevented. Therefore, the present invention calculates the total amount of concentrated water based on the flow rate of the concentrated water return line and the concentrated water drainage line, compares this total concentrated water amount with a set concentrated water amount, and uses the difference signal to calculate the concentrated water return line and the concentrated water drainage line. The amount of concentrated water is controlled at a constant level by controlling the opening degree of the concentrated water volume control valve installed in the system, and the required amount of produced water is calculated based on the amount of produced water and the amount of unused water, and this is compared with the amount of water discharged by the pressurizing pump. The number of rotations of the pressurizing tube is controlled based on the differential signal.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG.

FIG. 2 shows a system diagram of the ultrapure water production apparatus according to the present invention,
Items with the same reference numerals as in FIG. 1 represent the same or equivalent items. This ultrapure water production apparatus includes a concentrated water amount control valve 11 provided in a concentrated water return line 10, a concentrated water amount control means 12 that controls the concentrated water amount control valve 11,
A control means 13 for controlling the rotation speed of the pressurizing pump 20 is provided.

The concentrated water amount control means 12 is an arithmetic unit that calculates the total amount of concentrated water by receiving signals from a flow meter 14 that measures the amount of water in the concentrated water return line 10 and a flow meter 15 that measures the amount of water in the concentrated water drainage line 9. 16, a signal generator 17 that compares the total amount of concentrated water calculated by the calculator 16 and the set amount of concentrated water, and outputs the difference as a signal, and the signal generator 1
and a controller 18 that controls the valve opening degree of the concentrated water amount regulating valve 11 based on a signal from 7. The control means 13 includes a flowmeter 19 that measures the amount of produced water in the water supply line 6 and a flowmeter 2 that measures the amount of returned water in the return line 8.
0, calculates the amount of ultrapure water used at the nearest point 7, and calculates the required amount of produced water by adding the required amount of produced water, and calculates the amount of water discharged from the pressure pump 2. , a signal generator 23 that receives a signal from the flow meter 22 and a signal from the arithmetic unit 21, compares the required production water amount with the pressurizing pump discharge amount, and outputs the difference as a signal; The controller 24 controls the rotation speed of the pressure pump 2 based on a signal from a signal generator 23.

In the ultrapure water production apparatus according to the present invention, when a difference occurs between the total concentrated water amount and the set concentrated water amount, the concentrated water amount control means 12
controls the opening degree of the concentrated water amount regulating valve 11 to keep the concentrated water amount constant, and the control means 13 controls the rotation speed of the pressurizing pump 20 according to the difference between the required production water amount and the pressurizing pump discharge amount. Therefore, the amount of water corresponding to the amount used at use point 7 can be produced without contaminating the membrane module.
The energy saving effect is fully demonstrated.

Further, since the concentrated water amount control and the pressure pump rotation speed control are mutually independent, the configuration of the control system is simple and highly reliable control can be performed.

〔Effect of the invention〕

As described above, according to the present invention, the amount of produced water can be controlled without contaminating the membrane module and without increasing the amount of concentrated leaves.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing a conventional ultrapure water production apparatus, and FIG. 2 is a system diagram showing an ultrapure water production apparatus according to the present invention. DESCRIPTION OF SYMBOLS 1... Intermediate tank, 2... Pressure pump, 5... Ultrafiltration %-r=joule it, 6... Water supply line, 7
...Use point, 8...Return line, 9...
Concentrated water drainage line, 10... Concentrated water return line, 11
... Concentrated water amount control valve, 12... Concentrated water amount control means,
13... Control means, 16... Arithmetic unit, 17... Signal generator, 18... Controller, 21... Arithmetic unit, 23
...signal generator, 24...controller. 1st mouth

Claims (1)

[Claims] An intermediate tank that stores primary pure water, a pressure pump that extracts and pressurizes the primary pure water in the intermediate tank, and a membrane module device that produces ultrapure water by filtering the pressurized primary pure water. , a water supply line that sends ultrapure water to the point of use, a return line that returns unused ultrapure water that has passed through the point of use to the intermediate tank, and a concentration line that returns a portion of the concentrated water from the membrane module device to the intermediate tank. In an ultrapure water production apparatus equipped with a water return line and a concentrated water drainage line for discharging a portion of the concentrated water to the outside, a concentrated water volume control valve provided in the concentrated water return line and control of the concentrated water volume control valve are provided. a concentrated water amount control means for controlling the rotation speed of the pressurizing pump; and a control device for controlling the rotation speed of the pressurizing pump. The calculation unit and the calculation unit 7'
(A signal generator that compares the total amount of concentrated water and a set amount of concentrated water and outputs the difference as a signal, and a controller that controls the valve of the concentrated water amount adjustment valve based on the difference signal from the signal generator. The control means calculates the amount of ultrapure water used at the point of use based on the flow rate of the water supply line and the return line, and calculates the required amount of produced water by adding the amount of water returned to the intermediate tank. A computing unit, a signal generator that compares the required production water volume calculated by the computing unit with the discharge water volume of the pressurizing pump, and outputs the difference signal, and a signal generator that outputs the difference signal from the difference signal. An ultrapure water production device characterized by comprising a controller that controls the rotation speed of a pressure pump.