JP2845698B2 - Method and apparatus for measuring anions contained in condensate in condensate circulation system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for measuring anions in condensate upstream or downstream of a condensate desalination unit in a condensate circulation system in a thermal power plant or a nuclear power plant. to a method and apparatus for rapid measurement of anion concentration of condensate water to be used for operation monitoring, etc. condensate demineralizer.

[0002]

2. Description of the Related Art A condensate circulating system in a thermal power plant or a nuclear power plant generates electricity by driving a turbine with steam generated by a steam generator such as a boiler, and the steam discharged from the turbine is converted into water by a condenser. The condensate is operated in a cycle in which iron oxide fine particles (cladding) and various impurity ions contained in the condensate are removed by a condensate demineralizer, and the treated water is circulated again to the steam generator.

[0003] In such a cycle, various water treatments are performed in order to suppress corrosion in the system, but most of the once-through boiler type plants of thermal power plants in recent years have a conversion of condensate into ammonium ions as ammonium ions. About pH 9.3 to 9.5 by containing about 1 to 2 ppm of ammonium hydroxide
Volatile substance treatment to control condensate is performed.

[0004] Volatile material treatment of such condensate circulation system as water quality management, traces of Na, Cl, measurements such as SO ₄ is required. This is because these N
This is because, if ions of a, Cl, and SO ₄ leak, their accumulation may lead to obstacles such as scale, corrosion, and carryover of each system such as a boiler and a turbine. Since the solubility of impurities in steam increases as the temperature and pressure of steam increase, power generation equipment that needs to operate under more severe conditions, such as recent supercritical pressure plants and future ultra-supercritical pressure plants, has this impurity. Is a problem that causes adverse effects such as damage due to precipitation and adhesion to turbine blades and the like.

As a method for measuring these trace amounts of Na, Cl and SO ₄ ions, a flameless atomic absorption method or an ion chromatography method is used as a method for measuring Na ions, and a method for measuring Cl and SO ₄ ions is used as a method for measuring Cl and SO ₄ ions. , Ion chromatography (JIS K 0101, JIS K
0556) is generally used. In particular, 10ppb
When the following trace amounts of Cl and SO ₄ ions are measured by ion chromatography, the sample is sent to a concentration column containing an anion exchange resin, and Cl and S in the sample are removed.
A concentration column method in which O ₄ is adsorbed on an anion exchange resin and concentrated is generally used.

However, it is intended to measure trace amounts (about several ppb) of impurity ions, particularly chloride ions, by ion chromatography using the condensed column using condensate containing a large amount of ammonium hydroxide of 1 to 2 ppm as a sample. Then, the concentration step in the concentration column is affected by the coexisting ammonium hydroxide, and there is a problem of a decrease in sensitivity such that the peak of chloride ions is reduced. For example, when a chlorine ion concentration of 1 ppb is detected in sample water containing no ammonium hydroxide, and when 1.1 ppm of ammonium hydroxide is contained in the sample water, the measured chlorine ion concentration becomes 0.6 ppb. Will be.

For this reason, when measuring a small amount of anions using the condensate containing ammonium hydroxide as a sample water, it is necessary to eliminate the influence of ammonium hydroxide contained in the sample water. No such problem has been pointed out in the field of the invention.

In general, the removal of non-measurement target ions which affect the measurement sensitivity by the ion chromatography method, which is different from the present invention and has completely different types and concentrations of the ions to be removed, is described by a semiconductor. In the technical field of manufacturing, a proposal has been made in Japanese Patent Application Laid-Open No. 4-132965. This is because the sample water contains a high concentration of alkali metal ions and alkaline earth metal ions, and the background fluctuations and the like that appear when the sample water contains high concentrations of alkali metal ions or alkaline earth metal ions are eliminated. Excluding).

However, in the present invention for the purpose of controlling the quality of condensate water in the condensate circulation system, ammonium hydroxide which affects the measurement accuracy of trace anions in the condensate water is removed from the sample water flowing into the separation column. In some cases, the measurement sensitivity of trace anions cannot be improved, as is clear from the test examples described later.

[0010] This means that, when a small amount of anions in condensed water containing ammonium hydroxide are measured by ion chromatography, the sensitivity is not reduced due to fluctuations in the background.

[0011]

In the measurement of the concentration of anions contained in the condensate in the condensate circulation system, the concentration of the anion is extremely small, that is, the ppb level or less. is there. That is, for this type of concentration, a concentration column filled with an anion exchange resin is usually used, but the anion exchange resin filled in the concentration column gradually deteriorates as it is used, and together with this, ammonium hydroxide is used. It has been found that the ability to adsorb anions, especially chloride ions, in condensate containing water significantly decreases with time so that the effect on measurement accuracy cannot be ignored. If the concentration state of chloride ions varied due to such deterioration over time of the anion exchange resin, the addition of a concentration step for improving sensitivity resulted in a decrease in measurement accuracy, and both were satisfied. High sensitivity and high precision measurement cannot be realized.

In view of the above problems, the present inventors have studied in more detail a method capable of realizing highly sensitive and accurate measurement of trace anions in condensate in a condensate circulation system. In the course of the study, we focused on the following. That is, in the concentration step for improving the sensitivity when measuring trace chlorine ions in the condensed water sample having a high pH because of containing ammonium hydroxide, in the concentration step, Cl ⁻ is supplied by the anion exchange resin (R-OH) of the concentration column. The following adsorption reaction occurs.

[0013] ^{R-OH + Cl - → R} -Cl + OH - ... R-Cl + NH 4 OH → R-OH + NH 4 Cl ... In other words, the anion exchange resin is a condensate sample water Cl
^- The adsorbs as Equation, to condensate water sample contains ammonium hydroxide, adsorbed Cl as formula ^- pushed by the OH ion, because thus desorbed from the anion exchange resin total Cl of該復water sample water ^- can not be adsorbing, this is the point that causes deteriorating the measurement accuracy. Note that other anions such as S
O ₄ ^2- has almost no problem of such anion extrusion.

[0014] Apart from this, if the concentration of ammonium hydroxide in the condensed sample water fluctuates, this also causes fluctuations in the amount of adsorption (variation in the concentration state), and
The adsorption capacity of the anion exchange resin deteriorates with time as described above. Incidentally, when the typical thermal power plant condensate circulation system condensate of (pH 9.4 by the presence of hydroxide ammonium Um) and a sample water, which was this contains chlorine ions, for example 1 ppb, which Is as shown in Table 1 below, and the peak area decreases to about 10% / month, when the peak area is measured by ion chromatography and the length of the use period of the anion exchange resin from the time of new use. .

[0015] Cl is actually concentrated adsorbed trapped in the anion exchange resin from these things ^- amount, Cl contained in the condensate water sample under the influence of various factors mentioned above ^- a portion of only However, the ratio also becomes an inconsistent amount.

[0016]

[Table 1]

Chlorine ions concentrated in this concentration column are flowed out of the column as an eluent, and are sequentially led to a separation column of an ion chromatograph, a suppressor attached if necessary, and a detector. Simply adding an anion concentration step to the ion chromatography method as described above causes variation in concentration, and accurate measurement cannot be performed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned state of the art, and has been developed in a condensate circulation system of a power generation facility for circulating condensate containing a large amount of ammonium hydroxide. It is an object of the present invention to provide a method and an apparatus capable of measuring anions, particularly chloride ions, with high accuracy and high sensitivity by using an ion chromatograph with water as a sample water.

[0019]

In order to achieve the above object of the present invention, the inventor has completed the present invention described in each of the claims.

One of the features of the present invention is a method for measuring condensate containing ammonium hydroxide at a predetermined position in a condensate circulation system as sample water and measuring anions in the sample water with an ion chromatograph. Replacing ammonium ions in the sample water with hydrogen ions, and adsorbing anions in the water from which the ammonium ions have been removed.
After the concentration step of concentrating, and the concentrated anions are eluted by the eluate from this concentration step, the anions of a plurality of components contained in the eluate are separated from the upstream of the continuous liquid flow from downstream to A method of measuring anions contained in condensate, comprising: a separation step of separating the separated anions; and a detection step of sequentially detecting the concentration of each separated anion.

A feature of the apparatus of the present invention for realizing the above method is that a condensate containing ammonium hydroxide at a predetermined position in a condensate circulation system is used as sample water, and an anion in the sample water is measured by an ion chromatograph. An ammonium ion removal device for replacing ammonium ions in the sample water with hydrogen, an anion concentration column connected downstream of the ammonium ion removal device , and a liquid flow from the anion concentration column flowing from the top of the column. A separation column in which anions of a plurality of components in the liquid flow are separated from each other in an enriched zone from upstream to downstream of the liquid flow to flow out from the end of the column; A detection device for sequentially detecting the concentration of ions, and a flow of an eluent for eluting anions through the anion concentration column and the separation column. In the place that forms the structure that was a stage.

In the present invention, the ammonium ions in the sample water, which is the condensate of the condensate circulation system, are removed by replacing them with hydrogen ions.
As described above, when measuring a small amount of anions contained in condensate water for the purpose of water quality control of the condensate circulation system, it is necessary to concentrate the anions, and in particular, anions to the anion exchange resin used in the concentration step. This is because the adsorption state of chloride ions is affected by the presence of ammonium hydroxide in the sample water, and is also affected by changes in the adsorption capacity of the anion exchange resin and the like in relation to the presence of ammonium hydroxide. The effect of ammonium hydroxide in the anion concentration step can be eliminated for the first time by the above configuration of the present invention in which ammonium ions are removed from the sample water before the concentration step.

As a method for replacing ammonium ions with hydrogen ions, for example, a method using a cation exchange membrane,
A method using a cation exchange resin can be exemplified,
Thus, as shown in FIG. 2 and the following formula, ammonium ions (NH ₄ ⁺ ) in the sample water are adsorbed, and instead, H ⁺ ions are released, which are combined with OH ⁻ ions to form water (H ₂ O), and the sample water Can remove ammonium ions.

RH + NH ₄ OH → R—NH ₄ + H ₂ O When the method of replacing ammonium ions with hydrogen ions is performed using a cation exchange resin, for example, the H-type cation exchange is performed. The sample water is passed through the column packed with the resin, and the reaction of the above formula is performed.When the adsorption of ammonium ions reaches saturation, the water is stopped to regenerate the cation exchange resin. However, it is necessary to provide a plurality of columns filled with cation exchange resin in parallel, and to switch the water flow to another column when the adsorption reaches saturation, to perform continuous ammonium ion removal operation. Can be.

When a cation exchange membrane is used,
A cylindrical body is formed with a cation exchange membrane, and sample water is allowed to penetrate from one inner end to the other end of the cylindrical body, whereby ammonium ion (N
H ₄ ⁺ ) is adsorbed and water is generated, and an acid solution such as sulfuric acid, which ion-exchanges (NH ₄ ⁺ ) adsorbed on the cation exchange membrane into hydrogen ions, is flown outside the cylindrical body. Then, an ammonium ion removing device configured to be discharged as (NH ₄ ) ₂ SO _{4 out} of the system as in the following formula can be used.

R—NH ₄ + H ₂ SO ₄ → R—H + (NH ₄ ) ₂ SO ₄ ... In this case, ammonium ions can be removed by continuously passing sample water, and ammonium ions can be removed. The pH of the sample water flowing out of the removal device becomes neutral around 7.

As another example using a cation exchange membrane, sample water flows through one end from the inside to the other end of a cylinder formed of the cation exchange membrane, and pure water flows outside the cylinder. Further, a method may be employed in which an electrode is provided outside the cylindrical body, pure water is electrolyzed by an electric current, and ammonium ions adsorbed on the cation exchange membrane are ion-exchanged by hydrogen ions generated thereby.

The concentration column used for concentrating anions in the sample water from which ammonium ions have been removed is constituted by packing a known anion exchange resin used in a conventional ion chromatograph, and this column is used. When a predetermined volume of sample water is passed from the top to the end of the sample, anions contained therein are adsorbed on the anion exchange resin. At this time, since the ammonium hydroxide in the sample water has been removed as described above, all the anions, particularly chloride ions, will also be adsorbed without being pushed out of the column, and therefore, the measurement by this anion concentration It is possible to prevent a decrease in accuracy in increasing the sensitivity of the result. Note that a plurality of concentration columns may be provided in parallel so that the flow of water can be switched. In addition, the volume of the sample water that passes through the concentration column may be either the one that controls the water flow capacity or the one that controls the water flow time. The point is to accurately grasp the concentration ratio of the anion to be measured. If possible.

Adsorbed on the anion exchange resin in the concentration column
The concentrated anions are eluted from this column by an eluent (eluent: for example, a mixture of sodium carbonate and sodium bicarbonate).

The separation of the anion in the present invention is, for example,
The water sent from the concentration column is passed through a separation column filled with a known anion exchange resin used in a conventional ion chromatograph, and the anion exchange of a plurality of anions contained in the water is performed. This is accomplished by separating the enriched zone from upstream to downstream of the running water eluted due to differences in affinity for the resin. When separating the zones enriched with anions of multiple components, generally, the enriched zone of each anion should be such that it does not interfere with the measurement of the concentration of these anions in the flow of the eluate. It is desirable to be separated.

In the present invention, a suppressor can be provided after the anion separation step. The suppressor is used for converting an eluent (eluent) used for eluting anions from an anion concentration column or a separation column into a substance having low conductivity,
It can be configured using an apparatus having the same configuration as the above-mentioned ammonium ion removing apparatus using a cation exchange membrane.
In this apparatus, for example, when sodium carbonate is used as an eluent as shown in FIG. 3, low-conductivity carbonic acid is generated in the water passing through the suppressor, while the counter ion of Cl ^{− in} the sample water is formed . Changes from Na ⁺ to H ⁺ , and becomes HCl having a high conductivity and flows out.

As described above, the anion separated into each component can be measured as the anion concentration as the electric conductivity by passing the anion through, for example, an electric conductivity cell which is a detecting device according to the flow of the flowing water.

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to the embodiments shown in the drawings.

FIG. 1 shows an example of a schematic configuration of a measuring apparatus for measuring anions contained in condensate water according to the present invention. In FIG. 1, reference numeral 1 denotes a sample pump, and a water inlet side thereof. The pipe is connected to a predetermined position of a condensate circulation system of a thermal power plant (not shown) (for example, an inflow pipe to a condensate desalination apparatus and / or a treated water outflow pipe from the condensate desalination apparatus). The condensate flowing through the condensate circulation system contains about 1 to 2 ppm of ammonium hydroxide and may contain a small amount of anions, for example, about 1 ppb or less of chloride ions, depending on the use condition, as described above. It is.

The outlet pipe of the sample pump 1 is connected to an ammonium ion removal column 2 (ammonium ion
ON removal device) . As shown in FIG. 2, the ammonium ion removal column 2 of the present example
A cylindrical cation exchange membrane 202 is assembled so as to penetrate the axial center of the elongated columnar cylindrical body 201,
Sample water is passed through the inside of the tube from one end to the other end, and sulfuric acid is passed through the outside of the tube.

[0036] This device, of NH ₄ OH and trace Cl ^-
When the sample water containing (another anion is omitted for convenience) and sulfuric acid are passed as described above, the reaction of the above formula takes place between the sample water and the cation exchange membrane 202. The reaction of the above formula is carried out between the cation exchange membrane and sulfuric acid flowing outside the cylinder, and NH ₄ ⁺ contained in the sample water is converted into (NH ₄ ) ₂ SO _{4 in} the form of (NH ₄ ) ₂ SO ₄ . it is discharged out of the system, while the downstream end of the cation exchange membrane, trace amounts of Cl ^- as it contains NH ₄ sample water OH has been removed is discharged.

In this example, the sample water flowing out of the ammonium ion removal column 2 is passed to the concentration column 4 through a hexagonal switching valve 3 whose flow state is set to the state indicated by the solid line in FIG.

The concentrating column 4 is configured as a column packed with a known anion exchange resin used in a conventional ion chromatograph, and converts Cl ⁻ (anion) in the sample water to be passed through to the anion exchange resin. Adsorb to resin,
Carrier water is discharged out of the system. A predetermined volume of sample water is passed through the concentration column 4 to adsorb Cl ⁻ contained in the volume of the sample water into the concentration column 4.
As an example of a standard apparatus, the concentration ratio is about 2 ml for a concentration column having a full water volume of about 2 ml in order to improve the sensitivity by about 400 times for detecting Cl ^{− of} 1 ppb or less. The flow rate may be about 10 minutes at / min. During this time, the eluent is supplied from the eluent pump 5 to the system below the separation column described later.

Next, the switching valve 3 is switched to the flow state shown by the broken line in the figure, and the eluent is allowed to flow from the eluent pump 5 to the concentration column 4, and the Cl ⁻ (anion) adsorbed and concentrated in the column 4. Is eluted and introduced from the top of the separation column 6 connected to the subsequent stage. This separation column 6 is filled with a known OH ^- type anion exchange resin having a low exchange capacity, which is used in a conventional ion chromatograph apparatus. Therefore, sample water is passed through this separation column. With the effluent from the end of the column, each anion in the sample water has a small affinity with a certain relationship according to the difference with the affinity with the anion exchange resin.
Conversely, those with a higher affinity flow out of the column slowly. Speaking it in and SO ₄ ^2- in the relationship one case, the affinity of the small Cl ^{- -} Cl that may be included in the sample water to flow out quickly, large SO affinity Conversely ₄ ^2- is discharged slowly.

The separated anions are output in the order of coming out of the separation column 6 and the suppressor 7 connected to the subsequent stage.
Column. As shown in FIG. 3, the structure of the suppressor 7 in this example is a cylindrical strong acidic cation exchange membrane 702 so as to penetrate the axial center of the elongated columnar cylinder 701.
The effluent from the separation column is passed through the inside of the cylinder so as to penetrate from one end to the other end. On the other hand, sulfuric acid as a removal liquid is passed from the removal liquid pump 8 to the outside of the cylinder. You. The reaction of the following formula is carried out between the water and the strongly acidic cation exchange membrane 702, and the reaction of the following formula is carried out between the strongly acidic cation exchange membrane 702 and sulfuric acid flowing outside the cylinder. conducted with sodium carbonate injected into the system as the eluent is converted to carbonate low conductivity, Na ⁺ is
It is discharged out of the system as sodium sulfate . On the other hand, a small amount of Cl ^- is removed from the downstream end of the cation exchange membrane into H 2 of high conductivity.
Water containing Cl is discharged.

[0041]

Embedded image

Then, each anion in the sample water is separated in running water, and the water converted into an acid having a high conductivity is passed through the conductivity cell 9 and can be sequentially measured by the conductivity meter 10. The measurement result of the conductivity meter 10 is sent to the computer 11 and, for example, is compared with a calibration curve measured using a standard solution whose concentration is known in advance.
For example, it is possible to measure the concentration of chloride ions contained in the current condensed water sample. Since the elution time of each anion is given as a fixed value depending on the type of anion exchange resin packed in the separation column, etc., all of the above operations may be performed as an automated operation according to a sequence program, for example. Of course you can.

According to the present embodiment, the step of removing ammonium ions and the step of removing eluate (eluent) components can be performed while continuously passing water, respectively.
Accordingly, by providing the concentration column and the like so as to be switchable in a plurality of series (two series when the concentration time and the measurement operation time after the concentration are substantially the same), the sample water from the condensate system is substantially always continuously supplied. A measurement can be made.

In the above apparatus, an ammonium ion removal column 2 is provided at the first stage to remove ammonium ions from the sample water before concentration. Since the problem that the part cannot be adsorbed on the anion exchange resin is eliminated, the accuracy is prevented from lowering. Also, there is no problem that the ammonium ion lowers the measurement sensitivity especially of chlorine ion at the time of measurement, and the whole is high. The effect that sensitivity and highly accurate measurement can be realized is obtained.

Test Example 1 Using the apparatus shown in FIG. 1, the chlorine ion concentration in a sample water containing a large amount of ammonium hydroxide and containing a small amount of chloride ion was measured under the following conditions.

In addition, an ammonium ion removal color
The chlorine ion concentration in the sample water was measured in the same manner as described above, except that the sample water was directly passed through the concentration column, bypassing the system 2 .

Sample water: ammonium hydroxide (NH ₄
A standard solution having a Cl ⁻ concentration of 1 ppb and a pH of 9.4 containing 1100 ppb as

Concentration flow rate: Sample water was passed through a concentration column at 2 ml / min for 10 minutes for concentration.

Step: After concentration, 4 mM Na ₂ C was added to the concentration column.
O ₃ / 4mMNaHCO allowed ₃ by flowing eluant eluted anions adsorbed and concentration, measured by the electric conductivity in the electric conductivity meter was passed through a separation column, a suppressor.

As shown in FIG. 4, the results show the results of a test in which ammonia was removed. FIG. 4A shows the results of a test in which ammonia was not removed.
It was confirmed that the measurement sensitivity was approximately three times that of (b).

Test Example 2 The ammonium ion removal column 2 of the apparatus shown in FIG. 1 was provided between the concentration column and the separation column, and the concentration of chloride ion was measured under the same test conditions as in Test Example 1.

The result is as shown in FIG. 5, and only the same measurement sensitivity as shown in FIG. 4 (b) was obtained.

[0053]

According to the present invention, sample water is extracted from the condensate circulating system of a power generation facility that circulates condensate containing a large amount of ammonium hydroxide, and the sample water contained in the sample water is, for example, 1 ppb. There is an effect that it is possible to measure a small amount of anion concentration with high sensitivity and high accuracy without being affected by ammonium hydroxide contained in a large amount in sample water.

Further, according to the present invention, even if the anion exchange resin used for the concentration of anions for measuring a small amount of anions in the sample water deteriorates with time and its adsorption capacity changes, or Even if the concentration of ammonium hydroxide in the sample water changes, it does not affect the measurement accuracy.
From this point, highly accurate measurement can be realized.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of an embodiment of an apparatus for measuring anions in condensate water according to the present invention,

FIG. 2 shows the ammonium ion removal color used in the embodiment.
Diagram for explaining the structure and principles of beam,

FIG. 3 is a diagram for explaining the configuration and principle of a suppressor used in the embodiment;

FIG. 4 is a diagram showing the results of Test Example 1,

FIG. 5 is a diagram showing the results of Test Example 2.

[Explanation of symbols]

1 ... sample pump, 2 ... ammonium ion removal column , 3 ... switching valve, 4 ... concentration column, 5
... eluent pump, 6 ... separation column, 7 ... suppressor, 8 ... remover pump, 9 ... conductivity cell, 10 ... conductivity meter, 11 ... computer.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01N 30/88 G01N 30/02 G01N 30/08 G01N 30/14

Claims (3)

(57) [Claims] 1. A method for measuring condensate containing ammonium hydroxide at a predetermined position in a condensate circulation system as sample water, and measuring anions in the sample water with an ion chromatograph. A step of removing by replacing with hydrogen ions, a concentration step of adsorbing and concentrating anions in the water from which the ammonium ions have been removed, and a step of eluting the concentrated anions with an eluate from the concentration step, A separation step of separating anions of a plurality of components contained in the liquid into enriched zones from upstream to downstream of a continuous liquid flow, and detection for sequentially detecting the concentration of each separated anion. And a method for measuring anions contained in condensate in a condensate circulation system. 2. A device for measuring condensate containing ammonium hydroxide at a predetermined position in a condensate circulation system as sample water and measuring anions in the sample water with an ion chromatograph, wherein ammonium ions in the sample water are measured. An ammonium ion removing device for replacing with hydrogen ions, an anion enrichment column connected downstream of the ammonium ion removing device , and a liquid flow from the anion enrichment column flowing from the top of the column, A separation column that separates the component anions from the upstream to the downstream of the liquid stream into a zone enriched with each and flows out from the end of the column, and a detection unit that sequentially detects the concentration of each anion being separated. Condensing means for flowing an eluent for elution of anions into the anion concentration column and the separation column. Measuring device of anions contained in the condensate of the ring system. 3. An ammonium ion removing device according to claim 2, wherein the ammonium ion removing device for replacing ammonium ions in the sample water with hydrogen ions allows the sample water to penetrate and flow from one end to the other end of the inside of the cylinder made of a cation exchange membrane. A measuring device for measuring anions contained in the condensate of the condensate circulation system, wherein an acid solution is caused to flow outside the cylindrical body.