JP2010194479A - Pure-water production apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pure-water production apparatus which effectively decomposition remove residual chlorine in a raw water to as low concentration as possible with a reducing agent without requiring of an active-carbon tower treatment as a pretreatment. <P>SOLUTION: The pure-water production apparatus includes a cation exchange tower 1 and an anion exchange tower 3 at least in order to keep a reducing-agent supplying pipe 64 for decomposing free chlorine remaining in the raw water connected to a raw-water supplying passage 61 connected to the cation exchange tower, wherein the apparatus is connected with an automatic analyzer 4 having the function of arranging a sampling pipe 65 for analyzing free chlorine in a passage 62 between the cation exchange tower and the anion exchange tower, collecting a constant amount of sample to measure a chlorine concentration by a spectrophotometer, and outputting its result as a measuring signal, and a reducing-agent supplying amount controller 5 which makes the result that is calculated as a necessary reducing-agent amount in the automatic analyzer 4, a control signal, to control the amount of the reducing agent supplied from a reducing-agent supplying pipe 64. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pure water production apparatus.

  When pure water is produced from industrial water, it is filtered after injecting hypochlorite into industrial water for removal of soluble iron and manganese and sterilization, and this is supplied to pure water production equipment as raw water It is common to do. That is, free chlorine derived from hypochlorite oxidizes and degrades the ion exchange resin used in the deionized water device, so before supplying it to the deionized water device, a reducing agent (sulfite) is injected to remove the free chlorine. Neutralize.

  By the way, according to the knowledge of the present inventors, free chlorine cannot be neutralized theoretically even though sufficient sulfite is injected due to low water temperature or due to fluctuations in the concentration of organic substances in water. A trace amount of free chlorine may remain. This is considered to be caused by a decrease in the reaction rate between free chlorine and sulfite. And this trace amount of free chlorine degrades an ion exchange resin. In particular, when the anion exchange tower is a multilayer of a weak base resin and a strong base resin, the weak base resin has a cation exchange ability such as a carboxyl group, releases sodium after regeneration with caustic soda, and is washed with water. Sexually deteriorates. As a result, the regeneration time becomes longer and the amount of water collected per day is reduced. In order to cope with such a problem, it is conceivable to increase the injection rate of sulfite to increase the reaction rate, but this leads to an increase in drug cost and an increase in sulfate ion, which is a by-product of neutralization. There is a drawback that causes hypertrophy.

  On the other hand, as a pure water production apparatus considering the use of a reducing agent, in a pure water production apparatus in which raw water is passed through an activated carbon tower and then passed through an ion exchange resin tower, a reducing agent reaction tank is provided in front of the activated carbon tower. It is installed, a redox potential meter is installed in the effluent line from the activated carbon tower, and means for controlling the amount of reducing agent injected into the reducing agent reaction tank according to the measured value of the redox potential meter is provided. An apparatus for producing pure water is proposed (Patent Document 1).

  However, although the above-mentioned method for performing the activated carbon tower treatment has an advantage that the free chlorine hardly remains in the raw water supplied to the pure water production apparatus, there is a problem that the activated regeneration of the activated carbon is costly. .

JP 2001-187398 A

  This invention is made | formed in view of the said situation, The objective is to provide the pure water manufacturing apparatus excellent in the removal performance of the residual chlorine in raw | natural water, without requiring an activated carbon tower process.

  That is, the gist of the present invention includes at least the cation exchange tower (1) and the anion exchange tower (3) arranged in sequence, and the raw water supply flow path (61) connected to the cation exchange tower (1) has a raw material. A flow path between a cation exchange column (1) and an anion exchange column (3) in a pure water production apparatus to which a reducing agent supply pipe (64) for decomposing free chlorine remaining in water is connected. (62) is provided with a sampling pipe (65) for analyzing free chlorine, and a fixed amount of sample is collected by a metering pump in the sampling pipe (65), and a fixed amount of coloring reagent is added thereto and mixed. Color is developed, guided to a spectrophotometer, the absorbance is measured, the chlorine concentration is determined from the measured value of the absorbance and the calibration curve, and an automatic analyzer (4) equipped with a function for outputting the result as a measurement signal is connected to automatically The analyzer (4) has a measurement signal from it. And the amount of reducing agent supplied from the reducing agent supply pipe (64) by outputting the result as a control signal. A pure water production apparatus characterized by connecting a reducing agent supply amount control device (5) having a function of controlling the water content.

  According to the present invention, no activated carbon tower treatment as a pretreatment is required, and even when the water temperature is low (in winter), residual chlorine in raw water is efficiently decomposed and removed to the lowest possible concentration with a reducing agent. An apparatus for producing pure water improved so as to be able to be provided is provided.

FIG. 1 is an explanatory view of an example of a preferred embodiment of the pure water production apparatus of the present invention.

  Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

In the pure water production apparatus of the present invention, the raw water is filtered after injecting hypochlorite (sodium hypochlorite) into industrial water or the like. The amount of free chlorine remaining in the raw water is generally 0.1 to 1 ppm. Here, free chlorine means residual chlorine existing in water as dissolved gas (Cl ₂ ), hypochlorous acid (HOCl), and hypochlorite ions (OCl ⁻ ).

  The basic configuration of the pure water production apparatus of the present invention includes a cation exchange tower (1) and an anion exchange tower (3) arranged in sequence, and a raw water supply channel (61) connected to the cation exchange tower (1). ) Is connected to a reducing agent supply pipe (64) for decomposing free chlorine remaining in the raw water. The pure water production apparatus shown in the figure includes a cation exchange column (1) and an anion exchange column (3). And a decarbonation tower (2).

  The cation exchange tower (1) is filled with a cation exchange resin, and it may be a single bed type of strong acid cation exchange resin or a multi-layer bed type filled with weak acid cation exchange resin. Good. Examples of the strongly acidic cation exchange resin include Diaion (registered trademark: the same shall apply hereinafter) UBK series manufactured by Mitsubishi Chemical Corporation. Examples of the weak acid cation exchange resin include Diaion WK series manufactured by Mitsubishi Chemical Corporation. Etc.

  The anion exchange tower (3) is packed with an anion exchange resin. However, even if it is a single-bed type of strong basic anion exchange resin, it is a multi-bed type packed with weak basic anion exchange resin. May be. Examples of the strongly basic anion exchange resin include Diaion UBA series manufactured by Mitsubishi Chemical Corporation, and examples of the weakly acidic anion exchange resin include Diaion WA series manufactured by Mitsubishi Chemical Corporation. The recovery of the pure water is performed from the pure water extraction channel (63) provided at the bottom of the anion exchange tower (3).

The decarboxylation tower (2) may be of any system as long as it can remove HCO ₃ contained in the cation-exchanged treated water (acidic water). Usually, air is blown from the bottom of the tower, but aeration method for removing HCO ₃ as CO ₂ is employed, it is possible to use a membrane degasser for separating CO _2. As the membrane deaerator, for example, a device having a structure in which a porous hydrophobic membrane is used to separate a gas phase and a liquid phase and a decompression pipe is connected to the gas phase side can be used. By removing HCO ₃ as CO ₂ in the decarboxylation tower (2), the ion load of the anion exchange resin in the anion exchange tower (3) can be reduced.

  As the reducing agent from the reducing agent supply pipe (64), an aqueous solution of sulfite (specifically, sodium sulfite) is generally used. The concentration of sulfite in the aqueous solution is usually 1 to 10% by weight. Reference numeral (71) denotes a valve provided in the reducing agent supply pipe (64).

  The pure water production apparatus of the present invention is provided with a sampling pipe (65) for analyzing free chlorine in the flow path (62) between the cation exchange tower (1) and the anion exchange tower (3), and the sampling pipe ( In 65), a fixed amount of sample is collected with a metering pump, and a fixed amount of color-developing reagent is added to and mixed with this to develop color, and the spectrophotometer is used to measure the absorbance. From the measured absorbance value and the calibration curve, An automatic analyzer (4) having a function of obtaining a chlorine concentration and outputting the result as a measurement signal is connected to the automatic analyzer (4), the measurement signal from the automatic analyzer (4), a chlorine concentration prepared in advance and a reducing agent. Reducing agent supply having a function of calculating a necessary amount of reducing agent based on a relational expression with the amount, outputting the result as a control signal, and controlling the amount of reducing agent supplied from the reducing agent supply pipe (64) A quantity control device (5) is connected.

  The installation position of the sampling pipe (65) is not limited as long as it is a flow path (62) between the cation exchange tower (1) and the anion exchange tower (3), but the decarboxylation tower (2) When provided, the flow path (62b) after the decarbonation tower (2) is preferable to the flow path (62a) before the decarbonation tower (2). Reference numeral (72) denotes a valve provided in the sampling pipe (65).

  The measuring method of the chlorine concentration employed in the automatic analyzer (4) is a method known as a colorimetric method, and diethyl-p-phenylenediamine is particularly suitable as the color developing reagent. With these coloring reagents, it is possible to measure residual chlorine at a very low concentration in the order of ppb. The measurement absorption wavelength varies depending on the coloring reagent, but it is preferable to select a wavelength around 540 nm in the case of diethyl-p-phenylenediamine and around 440 nm in the case of o-tolidine. The calibration curve is data indicating the relationship between various chlorine concentrations and absorbances, and is obtained in advance according to the above colorimetric method.

  The functions of the automatic analyzer (4) and the reducing agent supply amount control device (5) are programmed and performed by a computer, and the automatic analyzer (4) and the reducing agent supply amount control device (5) The specific configuration can be easily constructed by those skilled in the art using conventional automatic control technology and computer technology. Reference numerals (81) and (82) are transmission paths for the measurement signal and the control signal in the automatic analyzer (4) and the reducing agent supply amount controller (5), respectively.

  The pure water production method using the pure water production apparatus of the present invention is performed according to a conventional method. When the ion exchange capacity is lowered, the ion exchange resin is regenerated, and when the ion exchange resin is deteriorated, the exchange is performed.

  EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited to a following example, unless the summary is exceeded.

Example 1:
As a pure water production apparatus, one having the same structure as that shown in FIG. 1 was used.

  As the cation exchange column (1), a multi-layer bed type cation exchange column (inner diameter 1000 mm × length 2500 mm) filled with “Diaion WK40L” 550L and “Diaion UBK110” 1350L was used in this order from the top.

  As the anion exchange column (3), a multi-layer bed type cation exchange column (inner diameter 1000 mm × length 2500 mm) packed with “Diaion WA30L” 750L and “Diaion UBA12A” 750L was used in this order from the top.

  An aeration type decarboxylation tower was used as the decarboxylation tower (2).

As raw water, industrial water (free chlorine 0.5 ppm) filtered after injecting hypochlorite was used, and the water flow rate was set to 25.5 m ³ / h.

The amount of the sodium sulfite aqueous solution (concentration 5 wt%) supplied from the reducing agent supply pipe (64) to the raw water supply flow path (61) is the same as that of the automatic analyzer (4) of the diethyl-p-phenylinediamine colorimetric method. It controlled by the reducing agent supply amount control apparatus (5). As a result, chlorine in the flow path (62) was measured with high accuracy, supply control of the amount of reducing agent was automatically performed, and stable operation could be performed over a long period of time. Incidentally, the amount of sodium sulfite supplied was 2.3 times the chemical equivalent ratio to Cl ₂ .

  The regeneration time of the anion exchange tower (3) was initially less than 1 hour, but in the winter, the washing time of the anion exchange tower (3) started to increase, and exceeded 3 hours in the third month. The cause was a sodium leak from “Diaion WA30L”. Analysis of free chlorine in the anion exchange column (3) showed 0.07 ppm of free chlorine. In another test, it was confirmed that sodium leak occurred when water containing 0.07 ppm of free chlorine was passed through a column packed with “Diaion WA30L”.

  Thereafter, “Diaion WA30L” was replaced and the operation was resumed. In winter, 0.07mg-Cl / L of free chlorine was detected again in the anion exchange column (3), so the sulfite injection amount was increased until no free chlorine was detected and the operation continued. did. The sodium leak from “Diaion WA30L” did not occur, and the regeneration time extension of the anion exchange column (3) was not observed.

1: Cation Exchange Tower 2: Decarboxylation Tower 3: Anion Exchange Tower 4: Automatic Analyzer 5: Reducing Agent Supply Amount Control Device 61: Raw Water Supply Channel 62: Channel 63: Pure Water Extraction Channel 64: Reductant Supply Piping 65: Sampling piping

Claims (1)

  At least the cation exchange tower (1) and the anion exchange tower (3) arranged sequentially are included, and the raw water supply channel (61) connected to the cation exchange tower (1) decomposes free chlorine remaining in the raw water. In a pure water production apparatus to which a reducing agent supply pipe (64) is connected, the flow path (62) between the cation exchange column (1) and the anion exchange column (3) is used for free chlorine analysis. The sample collection pipe (65) is provided, and a fixed amount of sample is collected in the sample collection pipe (65) by a metering pump, and a fixed amount of coloring reagent is added and mixed with this to produce a spectrophotometer. An automatic analyzer (4) having a function of measuring the absorbance, obtaining the chlorine concentration from the absorbance measurement value and the calibration curve, and outputting the result as a measurement signal is connected to the automatic analyzer (4). Measurement signal and chlorine concentration prepared in advance A reducing agent supply amount control device (5) having a function of calculating a necessary reducing agent amount based on the relational expression with the reducing agent amount and controlling the amount of reducing agent supplied from the reducing agent supply pipe (64). An apparatus for producing pure water characterized by comprising:

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