JPS58215550A - Method and apparatus for continuous measurement of sulfur ion in seawater - Google Patents

Abstract

PURPOSE:To measure continuously a sulfur ion in seawater and to grasp the aging change of its concentration, by mixing the seawater with an antioxidant for sulfur ion without aerating the seawater to be measured and measuring continuously the electric potential of an electrode by a reference electrode and a sulfur ion selecting electrode arranged in a flow passage of this mixed solution to find the activity of the sulfur ion. CONSTITUTION:Seawater to be measured is passed through a piping 2 for sampling seawater and the seawater is sampled continuously from the piping 2 by an injecting pump 4 serviceable for extremely small quantity. On the other hand, an antioxidant 9 for sulfur ion i.e. an aqueous solution containing 0.1-6N sodium hydroxide, 0.01-1M ascorbic acid and 0.001-0.01M ethylenediamine tetraacetic acid is supplied continuously to a mixing and stirring part 14 by an injection pump 10. The seawater sent from the pump 4 is mixed with the antioxidant 9 sent from the pump 10 without aerating said seawater and a uniformly mixed solution is made. An electrode cell 20 provided with a reference electrode 16 and a sulfur ion selecting electrode 18 is arranged on a flow passage of the downstream side of this mixed solution and the electrode electric potential is measured continuously by both electrodes 16, 18 and then, the activity of the sulfur ion is found.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to sulfur in seawater! The present invention relates to a method and apparatus for continuously measuring (S2-) ions.

Generally, thermal power plants use high-temperature, high-pressure steam generated by burning fuel such as coal or heavy oil to rotate a steam turbine, and the rotational force rotates a generator to generate electricity. On the other hand, the steam that has passed through the turbine undergoes heat exchange in a condenser and is returned to water. By the way, while brass pipes are usually used as cooling pipes (heat exchange pipes) for this condenser,
Since seawater, which is easily handled by hand, is used as the cooling water, there is an inherent problem in that the brass tubes are severely corroded by sulfur (82-) ions in the cooling seawater. Therefore, when operating a thermal power plant, the first condition is strict detection of the quality of cooling seawater, especially sulfur ions, and appropriate anti-corrosion measures are taken depending on the concentration. When detecting sulfur ions, it is desirable to obtain extremely precise and continuous measurement data of sulfur ions in their natural state, unaffected by oxidation. Incidentally, in recent years, titanium tubes have been adopted as the cooling tubes, and although in this case the influence of sulfur ions is small, it has the disadvantage of high cost.
Currently, brass pipes are still widely used.

Now, the conventional method for measuring sulfur ions in seawater is to immediately filter the collected seawater to remove suspended solids in the seawater, and then quantify it by spectrophotometry (JIS).
-to-0101) Kaaluka, in this method the lower limit of emplacement is 0
．． 02 mg/n and filtration, oxidation of sulfur ions is unavoidable, resulting in a low sulfur ion concentration.

In addition, a method in which a sulfur ion antioxidant is added to collected seawater and fixed, and then fixed using a sulfur ion selective electrode method in a batch method, the sensitivity is about 1
However, there was a drawback in that it was impossible to constantly monitor sulfur ions, which fluctuate due to changes in natural conditions.

Furthermore, zinc, cadmium, etc. are added to the collected seawater,
A method of fixing sulfur ions as sulfides, separating them by filtration, and quantifying them by titration (JIS-01, 02)
However, this method had the disadvantage that it was complicated to operate and lacked sufficient sensitivity, making constant monitoring impossible.

The present invention has been developed in view of the above circumstances, and is characterized by continuously measuring sulfur ions contained in seawater and understanding changes in the concentration over time. This method enables the seawater to be continuously drawn from seawater to be measured without exposing it to the atmosphere.
A channel through which the mixed liquid is further circulated after being mixed with a predetermined sulfur ion antioxidant to form a uniform mixed liquid.''
The sulfur ion activity is determined by continuously measuring the electrode potential using a reference electrode and a sulfur ion selective electrode placed at the second electrode.

Furthermore, in order to effectively implement such a technique, the present invention provides the following features:
(1) A seawater introduction means that continuously introduces a predetermined amount of seawater into the seawater to be measured without contacting the atmosphere, and (2) An antioxidant supply that continuously supplies a predetermined amount of sulfur ion antioxidant. (3) a mixing means for mixing the seawater and the sulfur ion antioxidant introduced and supplied from the seawater introducing means and the antioxidant supplying means, respectively, without exposing them to the atmosphere; and (4) the mixing means. (5) an electrode cell having a reference electrode and a sulfur ion selective electrode arranged on a flow path on the downstream side and brought into contact with the mixed liquid formed by the mixing means; A device is used which includes potential difference detection means that are connected to each other and detect the potential difference between the two electrodes.

Thus, according to the present invention, sulfur (82+) ions, which corrode brass pipes for condensers in seawater used as cooling seawater, can be removed in their natural state without being subjected to oxidation. It has become possible to measure continuously and extremely precisely, and it has also made it possible to elucidate the effects of sulfur ions on problems such as corrosion of brass pipes, and also to clarify the effects of sulfur ions in seawater as a natural phenomenon. Since dynamic changes can be ascertained, excellent effects can be achieved, such as making it possible to take effective maintenance measures, especially for condenser pipes at power plants.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the method and apparatus for continuously measuring sulfur ions in seawater according to the present invention will be described in detail with reference to the drawings showing examples thereof.

First, in FIG. 1, seawater to be measured collected by a lifting pump (not shown) such as a submersible pump is passed through a seawater sampling piping 2, and the seawater is pumped from this piping 2 by a seawater sampling microinjection pump 4. are collected continuously.

Incidentally, if necessary, it is also possible to provide a switching valve 6 in the upstream pipe line of the pump 4 and to periodically supply the calibration liquid from the calibration liquid supply mechanism 8 by this HALPRO.

On the other hand, sulfur ion antioxidants 9, such as 01-6N sodium hydroxide, 001-IM ascorbic acid and 0
．． An aqueous solution containing 0.001 to 0.01 M ethylenediaminetetraacetic acid is continuously supplied by an injection pump 0 to a mixing and stirring section (mixing means) 14 via a switching valve 12.

This mixing/stirring section 14 mixes the seawater sent from the microinjection pump 4 and the sulfur ion antioxidant II agent 9 sent from the injection pump 10 without exposing them to the atmosphere to form a uniform liquid mixture. be.

In addition, to give an example of the mixing ratio of both liquids at this time, the amount of sulfur ion antioxidant 9 is about 3 Hl/min with respect to the flow rate of seawater of 10 mJ/ln.

The flow path on the downstream side of the mixed solution is provided with a reference electrode 16 and a sulfur ion selection electrode 18 (which indicates the concentration of 82- ions in the solution through electrode potential) as shown in FIG. An electrode cell 20 is arranged, and the electrode potential is continuously measured by both electrodes 16, 18, so that the sulfur ion activity can be determined. In addition, the electrode cell 20 shown in FIG. 2 is provided with a stirring mechanism 21 in order to further improve the uniformity of the mixed liquid, in which a small electromagnetic stirrer with a hollow shaft 22 serving as a liquid feeding nozzle is provided. 24 is provided, and a rotary stirring element 26 driven by the stirring element 24 is rotated in the mixed liquid close to the bottom of the sulfur ion selection electrode 18. Then, the mixed liquid is brought into contact with the reference electrode 16 and the temperature sensor 28 in the flow path 27 in the electrode cell 20, and then the seawater is collected through the pipe 29 into the drainage pipe 31 which is separate from the pipe 2. It is discharged to.

The reference electrode 16 and the sulfur ion selection electrode 18 are connected to an ion meter 30 (potential difference detection means) as shown in FIG. 1, and the ion meter 30 displays the sulfur ion activity as a potential difference. After arithmetic processing is performed based on a predetermined calibration curve and the signal from the temperature sensor 28, the sulfur ion concentration is recorded by a recorder 32 (recording means). Alternatively, the display device 35 of the microcomputer 33 calculates, for example, an hourly average value from the instantaneous concentration value after arithmetic processing, and the result is illustrated or displayed as a weekly, monthly, or yearly take, or printed out.

In addition, the electrode cleaning liquid supply mechanism 34 for periodically cleaning the electrode part is used for cleaning the electrode part for about 1 minute to 10 minutes at an arbitrary period of about 1 hour to 6 hours, as shown by the valley in FIG. An electrode cleaning liquid such as a hydrochloric acid aqueous solution is injected into the electrode cell 20 via the switching valve 12 and the mixing/stirring section 14 for an arbitrary period of time to clean the electrode. However, since seawater contains various metals, non-metals, inorganic and organic substances, if these adhere to and cover the sensitive part of the electrode, it will significantly reduce the sensitivity. This is because it is necessary to periodically clean the electrodes to remove the substances that cover them.

In addition, the calibration liquid supply mechanism 8 periodically supplies a sulfur ion aqueous solution with a standard concentration in order to calibrate devices, instruments, etc. during operation of this device and to accurately detect sulfur ion concentration. Therefore, this calibration operation is generally performed about once a month.

Furthermore, the operations of the seawater sampling microinjection pump 4, the sulfur ion antioxidant injection pump 10, the cleaning liquid supply mechanism 34, etc. are controlled by a controller 36 (control means). That is, when the electrode cleaning liquid supply mechanism 34 is activated and a predetermined cleaning liquid is being supplied to the electrode cell 20, the operation of the injection pumps 4 and 10 is stopped.

Thus, by adopting the present invention, the sulfur ion activity of seawater can be continuously measured by continuously collecting seawater without exposing it to the atmosphere, whereas conventionally seawater was collected and brought back and analyzed batchwise. This enabled measurements to be made with great precision. Moreover, it is possible to clearly understand the fluctuations of sulfur ions in seawater, which is a natural phenomenon, as changes over time, as shown in Figure 3, or as fluctuations over a long period of days, as shown in Figure 4. This made it possible to take effective maintenance measures for condenser pipes, etc.

In addition, by inserting the electrodes of a dissolved oxygen meter and a pH meter into the flow path of seawater that is fed to this measuring device,
This embodiment can be provided with a function that allows the sulfur ion activity, dissolved oxygen concentration, and pH to be grasped simultaneously, continuously, and comprehensively.

In the above description, installation of a cleaning liquid supply mechanism 34 that supplies cleaning liquid for cleaning both electrode parts, installation of a controller 36 that controls the mechanism 34 and both injection pumps 4 and 10, and furthermore, Although the installation of the recorder 32 for recording the sulfur ion concentration or the display device t35 of the microcomputer 33, etc., the present invention is not necessarily limited to this, and the present invention is not limited to this. It is also possible to omit it.

In addition, it goes without saying that various modifications and improvements can be made to the present invention based on the knowledge of those skilled in the art without departing from the spirit thereof.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of the method and apparatus for continuous measurement of sulfur ions in seawater according to the present invention, FIG. 2 is an enlarged cross-sectional view of the electrode cell portion, and FIG. This is a graph showing an example of the temporal change in the sulfur ion concentration (mV) recorded by the recorder of the device, and Figure 4 is an hourly average obtained by data processing the instantaneous sulfur ion concentration values in Figure 3. This is a graph printed out as a value. 4: Micro-injection pump for seawater collection 9: Sulfur ion antioxidant 10: Injection pump 14: Mixing stirring section 16: Reference electrode 18: Sulfur ion selection electrode 20: Electrode cell 30: Ion meter 32: Recorder 3
3: Microcomputer 34: Cleaning liquid supply mechanism 35: Display device 36: Controller Applicant: Chuyukai Metal Industry Co., Ltd.

Claims (6)

[Claims] (1) Continuously measure sulfur ions contained in seawater,
Using a method that makes it possible to understand changes in the concentration over time, the seawater to be measured is continuously drawn from seawater and mixed with a specified sulfur ion antioxidant without exposing it to the atmosphere. After forming a mixed solution, the electrode potential is continuously measured using a reference electrode and a sulfur ion selective electrode placed on the flow path through which the mixed solution is made to flow, thereby determining the sulfur ion activity. A method for continuously measuring sulfur ions in seawater. (2) The claim that the sulfur ion antioxidant is an aqueous solution containing 0.1-6N sodium hydroxide, 0.01-IM ascorbic acid, and 0.001-0.01M ethylenediaminetetraacetic acid. The method described in paragraph 1. (3) seawater introduction means that continuously introduces a predetermined amount of seawater to be measured from seawater without contacting the atmosphere, and an antioxidant supply means that continuously supplies a predetermined amount of sulfur ion antioxidant; a mixing means for mixing the seawater and the sulfur ion antioxidant introduced and supplied from the seawater introducing means and the antioxidant supplying means, respectively, without exposing them to the atmosphere; disposed on a flow path downstream of the mixing means; an electrode cell having a reference electrode and a sulfur ion selective electrode that are brought into contact with the mixed liquid formed by the mixing means; and an electrode cell that is connected to the reference electrode and the sulfur ion selective electrode, respectively, and that controls the potential difference between the two electrodes. A device for continuously measuring sulfur ions in seawater, comprising: a potential difference detection means for detecting sulfur ions in seawater. (4) A cleaning liquid supply mechanism for supplying a cleaning liquid capable of cleaning each electrode portion of the reference electrode and the sulfur ion selective electrode is connected to the flow path leading to the electrode cell. Apparatus described in section. (5) A control means is provided for controlling each of the seawater introduction means, the antioxidant supply means, and the cleaning liquid supply mechanism, and the cleaning liquid supply mechanism is operated by the control means to supply a predetermined cleaning liquid to the electrode cell. 5. The apparatus according to claim 4, wherein the operation of the seawater introducing means and the antioxidant supplying means is stopped when the seawater is in the inlet. (6) A recording means is connected to the potential difference detection means, and based on the signal output from the potential difference detection means,
4. The device according to claim 3, wherein sulfur ion activity or sulfur ion concentration is continuously recorded.