JP2003190950A - Changeover method for ion exchange tank and water treatment apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To remove a dissolved solid effectively after fully utilizing ion exchange capacity of each ion exchange tank. <P>SOLUTION: This water treatment apparatus comprises a plurality of ion exchange tanks (12a, 12b and 12c) filled with ion exchange resins, a hardness leak sensor (14) provided on the downstream side of the ion exchange tanks to measure the hardness of cleaned water, a raw water hardness meter (16) arranged on the upstream side of the ion exchange tanks to measure the hardness of supplied raw water, flowmeters (18a, 18b and 18c) for measuring water injection amounts, changeover valves (22a, 22b and 22c) for controlling the injection of water and the stop of water supply with respect to the respective ion exchange tanks and a control unit (24) for monitoring the hardness of cleaned water, hardness of raw water and the injection amounts of cleaned water and raw water and performing the on-off operation of the changeover valves, when the hardness of cleaned water exceeds set hardness or the integrated value of the hardness of raw water and the injection amounts reaches the ion exchange capacities of the ion exchange tanks, to successively change over the ion exchange tanks. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for switching ion exchange tanks and a water treatment device for producing soft water or pure water (purified water) used for supplying water, cleaning water for semiconductors, or the like.

[0002]

2. Description of the Related Art So-called raw water such as ground water, river water or tap water is used in addition to suspended solids such as dust, mud and microorganisms having a relatively large particle size, as well as in the geology of the water sampling site and liberation from piping. It contains impurities that are caused by dissolved solid substances (dissolved ionic substances: metal ions such as calcium ions and magnesium ions). If this raw water is used directly for water supply or cleaning water for semiconductor substrates, the piping of the equipment may become blocked or dirty,
It produces scale, sludge and corrosion in the boiler and also contaminates semiconductor substrates. Therefore, it cannot be used as it is, and in order to use it as boiler feed water, etc., pretreatment to remove these impurities from raw water is necessary.

Of these impurities, suspended solids are removed by filtration or coprecipitation using a flocculant. On the other hand, an ion exchange method is widely known as a general method for removing dissolved solids.

FIG. 3 shows a conventional example of a water treatment device for producing purified water. This water treatment device removes dissolved solids from raw water from which suspended solids have been removed by an ion exchange method. The conventional water treatment apparatus shown in the figure has three ion exchange tanks (52a, 52b, 52c) connected in parallel and filled with an ion exchange resin, and raw water after removing suspended solids into each ion exchange tank. Water pipes that can be supplied (53)
And an extraction pipe (55) for taking out the purified water from which the dissolved solids have been removed in the ion exchange tank and guiding it to a tank (not shown), and three switching valves (62a, 62a, for controlling the injection / stopping of the raw water into each ion exchange tank). 62b and 62c).
In addition, three flowmeters (58) for measuring the amount of water injected into each ion exchange tank are provided in the branched water supply pipe on the upstream side of each ion exchange tank.
a, 58b, 58c) is provided with a hardness leak sensor (54) for measuring the hardness of purified water at the position where the extraction pipes on the downstream side of each ion exchange tank converge. The flow meter and the hardness leak sensor are electrically connected to the control device (64), and the control device opens and closes the switching valve by monitoring a signal from the flow meter and the hardness leak sensor.

In this water treatment device, first, the switching valve (62a) located on the downstream side of the ion exchange tank (52a) is released, and at the same time, the switching valve (62a) located on the downstream side of the other ion exchange tanks (52b, 52c). After closing 62b and 62c), the raw water from which suspended solids have been removed from the water supply pipe is sent to the ion exchange tank (52a) to remove dissolved solids from the raw water.

The integrated value of the water injection amount measured by the flow meter (58a) on the upstream side of the ion exchange tank (52a) and the preset average hardness of the raw water is the ion exchange capacity of the ion exchange tank (52a). That is, when the maximum amount of ion exchange that can be performed in one ion exchange tank is reached, the control device closes the switching valve (62a) located on the downstream side of the ion exchange tank (52a), and at the same time The switching valve (62b) located on the downstream side of the exchange tank (52b) is opened, and water is poured into the ion exchange tank (52b). In this way, the ion exchange tanks used are sequentially switched to purify the raw water.

For some reason, before the integrated value reaches the ion exchange capacity, the ion exchange capacity of the ion exchange resin in the ion exchange tank may be lowered and some ions to be removed may be leaked. A hardness leak sensor (54) is provided on the downstream side of the ion exchange tank to detect the hardness of the purified water, and when the value exceeds the set hardness, the ion exchange tank is switched in preference to the above. That is, the hardness leak sensor has a role as a safety device that guarantees the hardness of purified water at a certain value or less.

In the ion exchange tank after use, an operation of treating the ion exchange resin with a chemical to restore the exchange capacity, that is, regeneration is performed.

[0009]

As described above, in the conventional water treatment apparatus, the ion exchange tank is mainly based on the integrated value of the water injection amount measured by the flow meter and the preset average hardness of the raw water. Was being switched. Here, the average hardness of raw water means the average value of the hardness of groundwater, river water, etc. in the area throughout the year.

However, since the hardness of the raw water is affected by the season and other times, the actual hardness of the raw water sometimes falls below the average hardness. In such a case, switching to the next ion exchange tank was performed even though the amount of raw water injected did not reach the ion exchange capacity of the ion exchange tank. If the switching is performed at an early stage, the cost for producing the purified water will increase, and also the regeneration of the ion exchange resin will have to be frequently performed, resulting in a large human and time burden.

The present invention has been made in consideration of these circumstances, and effectively utilizes the respective ion exchange tanks to the full ion exchange capacity to remove dissolved solids, thereby supplying water or washing water for semiconductors. Ions that reduce the manufacturing cost of soft water and pure water (purified water) used and also reduce the number of times of regeneration of the ion exchange resin to reduce the regenerant and drainage load as well as human and time burden. An object of the present invention is to provide a method for switching the exchange tank and a water treatment device using the switching method.

[0012]

In order to solve the above problems, the present invention provides a method for switching ion exchange tanks by switching a plurality of ion exchange tanks filled with an ion exchange resin to remove dissolved solids. Switching the ion exchange tank when the integrated value of the raw water hardness of the upstream side of the ion exchange tank and the amount of water injected reaches the ion exchange capacity of the ion exchange tank.
A method of switching an ion exchange tank is provided.

According to this ion exchange tank switching method, even when the actual hardness of the raw water is lower than the average hardness, the ions in each ion exchange tank are determined by the volume of the ion exchange tank and the exchange capacity / density of the ion exchange resin. Since the water is poured into the ion exchange tank until the exchange capacity and the integrated value of the measured raw water hardness and the amount of injected water become equal, the ion exchange can be performed up to the full ion exchange capacity of the ion exchange tank.

Here, it is preferable that the purified water hardness of the purified water on the downstream side of the ion exchange tank is measured, and when the measured value exceeds the set hardness, the ion exchange tank is switched preferentially.

For some reason, when the flow of raw water passing between the ion-exchange resins becomes uneven and the diffusion of the raw water becomes non-uniform or the hardness of the raw water changes suddenly, the ions to be removed leak. Therefore, the hardness of the purified water is measured by the hardness leak sensor, and when the measured value exceeds the set hardness, the ion exchange tank is switched in preference to the above. As a result, the hardness of purified water can be guaranteed to be a certain value or less.

In order to carry out the above-mentioned ion exchange tank switching method, the present invention purifies a plurality of ion exchange tanks (12a, 12b, 12c) filled with an ion exchange resin and purified water on the downstream side of the ion exchange tanks. A hardness leak sensor (14) for measuring the water hardness, a raw water hardness meter (16) for measuring the raw water hardness of the feed water upstream of the ion exchange tank, and a flow meter (18a, 18b, 18c) for measuring the water injection amount, Switching valve (22a, 22b, which controls water injection / water stoppage to each ion exchange tank)
22c) and the purified water hardness, raw water hardness, and water injection amount are monitored, and when the purified water hardness exceeds the set hardness, or when the integrated value of the raw water hardness and water injection amount reaches the ion exchange capacity of the ion exchange tank. Also provided is a water treatment device comprising a control device (24) for opening and closing the switching valve to switch the ion exchange tank.

The water treatment apparatus of the present invention removes dissolved solids from the raw water from which suspended solids have been removed by the ion exchange method. Purified water hardness detected by a hardness leak sensor,
The raw water hardness measured by the raw water hardness meter and the water injection amount measured by the flow meter are monitored by the control device, and when the purified water hardness exceeds the set hardness or the integrated value of the raw water hardness and the water injection amount is the ion exchange in the ion exchange tank. When the capacity is reached, the switching valve is opened / closed by a command from the control device.
That is, the switching valve that controls the water injection of the ion exchange tank that has been used up to that point is closed, and the switching valve of the other ion exchange tank is opened and water is injected into this to perform ion exchange.
In this way, the ion exchange tanks are sequentially switched to purify the raw water. By monitoring the purified water hardness detected by the hardness leak sensor with the control device, the hardness of the purified water can be guaranteed to be a certain value or less.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below with reference to the drawings. In addition, in each figure, the common part is denoted by the same reference numeral, and the duplicated description will be omitted. FIG. 1 is a conceptual diagram showing the configuration of the first embodiment of the water treatment device of the present invention.

Since the water treatment apparatus of this embodiment produces soft water or pure water (purified water) used for boiler feed water, semiconductor cleaning water, etc., like the conventional water treatment apparatus, it is used for ground water, river water or It is used to remove dissolved solids from so-called raw water such as tap water. In addition, suspended solids having a relatively large particle size are previously removed from raw water by filtration and coprecipitation using a coagulant. The case where the water treatment device of the present invention is used to purify boiler feed water will be described below.

The water treatment apparatus 10 of the present embodiment has three ion exchange tanks 12a, 12b and 12c connected in parallel and filled with an ion exchange resin, and raw water after removing suspended solids into the respective ion exchange tanks. Water supply pipe 13 that can supply water, an extraction pipe 15 that takes out purified water from which dissolved solids have been removed in an ion exchange tank and leads to a tank (not shown), and three control pipes that control the injection / stopping of raw water to each ion exchange tank. Switching valves 22a, 22
b and 22c. In addition, three flowmeters 18a, 18b, 18c for measuring the amount of water injected into each ion exchange tank are provided in the branched water supply pipe on the upstream side of each ion exchange tank.
However, a hardness leak sensor 14 for measuring the hardness of purified water is provided at the position where the extraction pipes on the downstream side of each ion exchange tank converge. Further, a raw water hardness meter 16 for measuring the hardness of raw water is attached to the water supply pipe 13. Here, the hardness is the amount of calcium ions and magnesium ions in the target water converted to the corresponding calcium carbonate and expressed in ppm, and the hardness leak sensor is, for example, potassium chloride. The potential difference between the reference potential and the measured potential of the calcium ion electrode,
When this exceeds the potential difference set during calibration, an alarm signal is sent to detect the hardness leak of purified water.
In addition, the basic structure of the raw water hardness meter is almost the same as that of the hardness leak sensor, but the hardness leak sensor is that the hardness of the raw water is measured at regular intervals and the measured hardness is transmitted to the control device as a raw water hardness signal. Differs from its function.

Hardness leak sensor 14, flowmeters 18a, 1
8b, 18c and the raw water hardness meter 16 are electrically connected to the controller 24, which monitors the alarm signal from the hardness leak sensor, the flow rate signal from the flow meter, the raw water hardness signal from the raw water hardness meter, Switching valve 2 if constant
2a, 22b, 22c are opened and closed.

In this water treatment device 10, first, the switching valve 22a located downstream of the ion exchange tank 12a is opened, and the switching valves 22b and 22c located downstream of the ion exchange tanks 12b and 12c are closed. The raw water from which the suspended solids have been removed from the water supply pipe 13 is sent to the ion exchange tank 12a by a pump (not shown) to bring the ion exchange resin into contact with the raw water and perform ion exchange to remove the dissolved solids from the raw water. .

In the present embodiment, the integrated value of the water injection amount measured by the flow meter 18a on the upstream side of the ion exchange tank 12a and the raw water hardness measured by the raw water hardness meter 16 is the ion exchange tank 12a.
When the ion exchange capacity of a is reached, the ion exchange tank 1 that has been used until then is instructed by the controller 24.
The switching valve 22a for controlling the water injection of 2a is closed, and the switching valve 22b of the other ion exchange tank 12b is opened and water is injected into this to perform ion exchange. By repeating the same operation in the ion exchange tank 12c, the ion exchange tanks are sequentially switched to purify the raw water.

According to the water treatment apparatus of the present invention, the actual hardness is used instead of the average hardness of the raw water, and the ion exchange is performed by pouring water into the ion exchange tank until the integrated value of this and the water injection amount becomes equal. Ion exchange is possible up to the full ion exchange capacity of each ion exchange tank, which is determined by the volume of the ion exchange tank and the ion exchange capacity and density of the ion exchange resin, and each ion exchange tank can be utilized to the maximum extent.

In order to cope with the case where the ion exchange capacity of the ion exchange resin in the ion exchange tank becomes low and the ions to be removed are leaked before the integrated value reaches the ion exchange capacity for some reason, the hardness is to be dealt with. The leak sensor 14 detects the hardness of the purified water, and when the hardness exceeds the set hardness, it sends an alarm signal to the control device 24. The control device 24 receiving the alarm signal switches to the next ion exchange tank even if the integrated value is less than the ion exchange capacity of the ion exchange tank. This ensures that the hardness of purified water is below a certain value.

FIG. 2 is a conceptual diagram showing the configuration of the second embodiment of the water treatment device of the present invention. In the water treatment device of the present embodiment, instead of the three switching valves 22 provided in the water treatment device of the first embodiment, a three-way valve 32 is provided at the branch portion of the water supply pipe.
In addition, instead of the three flowmeters 18a, 18b, 18c provided in the branched water supply pipe, one flowmeter 38 is provided in front of the branched portion. Even with such a configuration, the ion exchange tanks can be switched as needed as in the first embodiment, and the amount of raw water injected into each ion exchange tank is measured to perform ion exchange. The tanks can be switched.

The present invention is not limited to the above-mentioned embodiments, and it goes without saying that various modifications can be made without departing from the gist of the present invention. For example, the above-mentioned water treatment device is exemplified as one including three ion exchange tanks, but the number of ion exchange tanks is not limited to this, and may be two or four or more.

[0028]

As described above, according to the ion exchange tank switching method and the water treatment apparatus of the present invention, the dissolved solids are removed by effectively utilizing each ion exchange tank to the full ion exchange capacity. , Reducing the production cost of soft water and pure water (purified water) used for water supply and semiconductor washing water, etc., and reducing the number of times the ion exchange resin is regenerated reduces the regenerant and drainage load, and The time burden can also be reduced.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a configuration of a first embodiment of a water treatment device of the present invention.

FIG. 2 is a conceptual diagram showing the configuration of a second embodiment of the water treatment device of the present invention.

FIG. 3 is a conceptual diagram showing a configuration of a conventional water treatment device.

[Explanation of symbols]

10 Water treatment equipment 12a, 12b, 12c Ion exchange tank 13 Water supply pipe 14 Hardness leak sensor 15 Extraction tube 16 Raw water hardness tester 18a, 18b, 18c Flowmeter 22a, 22b, 22c switching valve 24 Control device 30 water treatment equipment 32 three-way valve 38 Flowmeter

Claims (3)

[Claims] 1. A method for switching ion exchange tanks, wherein a plurality of ion exchange tanks filled with an ion exchange resin are switched to remove dissolved solids, wherein the raw water hardness of the feed water upstream of the ion exchange tank and the amount of water injected. The ion exchange tank is switched when the integrated value of the ion exchange tank reaches the ion exchange capacity of the ion exchange tank. 2. The purified water hardness of the purified water on the downstream side of the ion exchange tank is measured, and when the measured value exceeds the set hardness, the ion exchange tank is switched preferentially. The method for switching the ion exchange tank according to. 3. A plurality of ion exchange tanks (12a, 12b, 12c) filled with an ion exchange resin, and a hardness leak sensor (14) for measuring the purified water hardness of purified water on the downstream side of the ion exchange tanks. A raw water hardness meter (16) for measuring the raw water hardness of the feed water on the upstream side of the ion exchange tank, and a flow meter (18a, 18a,
18b, 18c), a switching valve (22a, 22b, 22c) for controlling water injection / stopping of water in each of the ion exchange tanks, and purified water hardness, raw water hardness and water injection amount are monitored, and the purified water hardness is set to a predetermined hardness. Or the integrated value of the raw water hardness and the water injection amount reaches the ion exchange capacity of the ion exchange tank, the control device (24) for opening and closing the switching valve to switch the ion exchange tank. A water treatment device characterized by the above.