JPH0656370B2 - Continuous alkali or acid concentration measuring method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for measuring the alkali or acid concentration of a sample solution. More specifically, the present invention uses an acidic or alkaline gas as a reagent, measures the amount of heat generated when the gas is dissolved and neutralized in the sample solution by the temperature difference before and after the reaction, The present invention relates to a method for introducing an acidic or alkaline reagent gas into a reaction zone in a method for measuring an acid concentration.

[Description of Prior Art]

Conventional methods and devices for continuously measuring the concentration of alkali or acid in a sample solution are disclosed in Japanese Examined Patent Publication No. 49-16516 and Japanese Examined Patent Publication No.
The method and apparatus disclosed in Japanese Patent Laid-Open No. 56-48062 have been adopted.

These measuring methods and devices should be satisfactory in practice, because the devices are extremely complicated and expensive, and the drawbacks such as the well-known titrator such as the need to prepare a sample solution to a known concentration are eliminated. It goes without saying that it was proposed as the research and development result of the measuring method and the measuring device.

That is, in Japanese Examined Patent Publication No. 49-16516, an acidic or alkaline gas is used as a reagent, and the amount of heat generated when the gas is dissolved and neutralized in a sample solution is measured by the temperature difference before and after the reaction. Characteristic method for measuring alkali or acid concentration of sample solution, temperature controller for continuously controlling the temperature of the sample solution and the reagent gas, the sample solution inlet and the reagent gas inlet A reaction part having a mouth and a blending zone sufficient to complete the reaction,
A gas-liquid separator having an excess reagent gas outlet and a reaction solution outlet, a temperature detector for measuring the sample before the reaction and the temperature after the reaction, and the obtained temperature difference before and after the reaction, the alkali of the sample solution. Alternatively, there has been proposed a continuous alkali or acid concentration measuring device which is used for measuring the alkali or acid concentration of the sample solution, which is composed of an indicator for converting the concentration into an acid and giving an instruction.

In JP-B-56-48062, an acidic or alkaline reagent gas and a sample solution are continuously supplied to a reaction zone, and the alkali or acid concentration of the sample solution is determined from the temperature difference between the sample solution before and after the reaction zone. In the continuous alkali or acid concentration measuring method for measuring the concentration of a sample solution, 0.1 to 3 times the volume of the aqueous medium is introduced into the reaction zone together with the reagent gas and the sample solution. A formula measurement method has been proposed.

However, the continuous alkali or acid concentration measuring method and measuring device disclosed in Japanese Examined Patent Publication No. 49-16516,
As long as the supply of the sample solution is not stopped, continuous measurement of the alkali or acid concentration is possible, but the secondary reaction is carried out because the reagent gas in the lower part of the reaction zone is dissolved and neutralized by bubbling. When the supply of the sample solution is temporarily interrupted, the reaction product thus generated stays in the reaction zone for a long time, so that precipitation of the reaction product occurs in the sample solution and the reaction product There is a drawback that it causes troubles such as clogging of the reaction tube due to solidification. For example, when carbon dioxide gas is used as a reagent gas and a sodium hydroxide aqueous solution is used as a sample solution, a sodium carbonate aqueous solution is usually obtained as a reaction product. When the supply is interrupted, the reaction between the aqueous solution of sodium carbonate and carbon dioxide proceeds to precipitate sodium bicarbonate, which adheres to the reaction tube and interferes with the next analysis. That there is.

In the continuous alkali or acid concentration measuring method disclosed in Japanese Patent Publication No. 56-48062, even if the supply of the sample solution is temporarily stopped, the aqueous medium is constantly supplied to the reaction zone, so that the reagent by bubbling is used. Since the reaction product generated in the secondary reaction that occurs as a result of the dissolution of the gas in the sample solution and the neutralization reaction does not stay in the reaction zone for a long time, it does not hinder the continuous measurement of the alkali or acid concentration. However, there is a drawback in that the sensitivity of the sample solution to changes in concentration is lowered by supplying the sample solution to the reaction zone together with the aqueous medium.

Therefore, the inventors of the present invention described above in the method and apparatus for continuously measuring the alkali or acid concentration in the sample solution disclosed in Japanese Patent Publication No. 49-16516 and Japanese Patent Publication No. 56-48062. As a result of repeated research and development to eliminate the drawbacks, first, in the application of Japanese Patent Application No. 63-42142, "an acidic or alkaline reagent gas and a sample solution are continuously supplied to the reaction zone, In a continuous alkali or acid concentration measuring method for measuring the alkali or acid concentration of a sample solution from the temperature difference between the sample solution before and after the zone, a sample solution layer and a reagent gas layer are respectively formed from the sample solution and the reagent gas at the lower part of the reaction zone. While alternately forming and, the reaction tube is raised to dissolve the reagent gas in the sample solution and to carry out a neutralization reaction ”. .

[Problems to be Solved by the Invention]

However, Japanese Patent Application No. 63-42142 (Japanese Patent Application Laid-Open No. 1-21)
7251) In the continuous alkali or acid concentration measuring method in the specification, even if the supply of the sample solution is temporarily stopped,
Since the reaction product resulting from the dissolution of the reagent gas in the sample solution and the neutralization reaction does not accumulate in the reaction zone, it is possible to continuously measure the alkali or acid concentration of the sample solution. If the supply or the supply of the reagent gas is reduced, the reagent gas inlet to the reaction zone may be blocked by the precipitation of the reaction product, which may interfere with the continuous measurement of the alkali or acid concentration of the sample solution. .

Therefore, an object of the present invention is to provide a sample solution even when the supply of the sample solution is temporarily stopped, or when the supply of the reagent gas is once stopped and then re-supplied or the supply of the reagent gas is reduced. Enables continuous measurement of alkali or acid concentration of
Another object of the present invention is to provide a method of using an acidic gas or an alkaline gas, and sensitively measuring the amount of heat generated when the gas is dissolved and neutralized in a sample solution with an inexpensive and extremely simple device.

[Means for Solving the Problems]

That is, the invention is pre-humidified, and
An excessive amount of the neutralizing reagent gas and the sample solution with respect to the sample solution are continuously supplied to a vertical reaction tube covered with a heat insulating material in a fixed amount, respectively, and the above-mentioned reaction is performed in the lower part of the reaction zone of the reaction tube. While alternately forming a reagent gas layer and a sample solution layer from a reagent gas and a sample solution respectively, the reaction tube is raised,
Dissolving the reagent gas in the sample solution and performing the neutralization reaction to calculate the amount of heat generated from the temperature difference between the inlet and the outlet of the reaction tube to continuously measure the alkali or acid concentration of the sample solution. And a method for measuring an alkali or acid concentration of a sample solution.

[Detailed description of each requirement of the present invention]

Hereinafter, the present invention will be described in detail with reference to the drawings showing an example of an apparatus used in the present invention.

FIG. 1 is a flow chart showing an example of a continuous alkali or acid concentration measuring device. In the figure, 1 is a quantitative device for flowing a constant flow rate of the sample solution, and a quantitative pump or the like can be used. Reference numeral 2 denotes a metering device for flowing a constant flow rate of the reagent gas, which is composed of a pressure reducing valve 17, a flow meter 18, and the like. The temperature control unit 3 controls the temperature of the sample solution in advance. A thin tube in the form of a coil is arranged in the box-shaped tank 19, and the box-shaped tank 19 is filled with a heat medium (for example, water) from the inlet 20. Commonly known heat exchangers can be used, such as heat exchangers that can be used. The temperature is adjusted in advance by the temperature controller 3, and the quantification device 1
Of the sample solution and the reagent gas from the quantification device 2
Constant temperature bath 4 to keep the temperature the same (for example, a device that heats or cools the internal air if necessary, and circulates the heated or cooled air to keep the temperature in the bath uniform and constant)
Will be introduced respectively. The reagent gas is stored in the constant temperature bath 4
Introduced into the humidifier 22 filled with an aqueous medium (for example, water) described later, which is previously introduced from the inlet 23,
After being humidified, it exits the humidifier 22 and is introduced into one of the coiled thin tubes. On the other hand, the sample solution is introduced into the other of the coiled thin tubes in the constant temperature bath 4. The reagent gas and the sample solution whose temperature is adjusted to the same temperature in the constant temperature bath 4 in this manner are then introduced into the reaction section 5, respectively. FIG. 2 shows an enlarged vertical sectional front view of the reaction section 5. In FIG. 2, the humidified and temperature-controlled reagent gas passes through the humidifier 22 and then one of the thin tubes in a coil shape in the constant temperature bath 4, and enters the reagent gas inlet 10 through the reagent gas inlet 10. It contacts and reaches the reaction tube 9 while alternately forming the sample solution layer and the reagent gas layer. On the other hand, the temperature-adjusted sample solution passes through the sample solution inlet 7 through the coiled one of the other thin tubes in the constant temperature bath 4, and the temperature is measured by the pre-reaction temperature detector 8 to contact with the reagent gas. Then, it reaches the reaction tube 9 while alternately forming the sample solution layer and the reagent gas layer. Below the reaction zone in the reaction tube 9,
While the sample solution layer and the reagent gas layer are alternately formed, the reaction zone in the reaction tube 9 rises, a part of the reagent gas is dissolved in the sample solution, the neutralization reaction is immediately performed, and the sample solution layer and the reagent are formed. The temperature of the gas layer rises. The excess reagent gas and sample solution after the reaction are in a gas-liquid mixed state and rise to the upper part inside the reaction tube 9, and the temperature is measured by the temperature detector 11 after the reaction attached to the upper part of the reaction tube 9, and the upper part of the reaction tube is measured. It is delivered to the outlet 12. The gas-liquid mixture delivered from the upper outlet 12 of the reaction tube is separated into an excess reagent gas and a reacted sample solution in the gas-liquid separation unit 6, and the excess reagent gas is discharged from the upper outlet 13 of the gas-liquid separation unit.
The reacted sample solution is discharged to the gas-liquid separation section lower outlet 14. In this way, the temperature before and after the contact of the reagent gas with the sample solution is measured by the temperature detector 8 and the temperature detector 11, respectively, and differentially taken out by the temperature difference measuring device 15. Further, from this temperature difference, the scale 16 calibrated with the alkali or acid concentration in advance is attached, so that the alkali or acid concentration in the sample solution can be directly visually observed.

In FIG. 1, the reaction section 5 and the gas-liquid separation section 6
Are stored in a constant temperature bath 4 so as not to be affected by the ambient temperature, and in FIG. 2 as well, the reaction section 5 is further covered with a heat insulating material such as foamed styrene or urethane foam.

Further, in FIG. 1, the temperature of the sample solution is adjusted in advance before using the quantification device 1, but the quantification device 1
If there is no hindrance to the use of, the temperature control may be performed in the box tank 19 after using the quantification device 1. In that case, the box-shaped tank 19 may be housed in the constant temperature tank 4 or may be installed outside the constant temperature tank 4. Further, it is stated that the pre-humidification of the reagent gas is performed by bubbling the reagent gas in an aqueous medium filled in the humidifying device 22 provided in the constant temperature bath 4, but the pre-humidification of the reagent gas is performed. The method is not limited to the method of bubbling the reagent gas in the aqueous medium, and a commonly used humidification method such as a method of blowing steam into the reagent gas may be used. As shown in FIG. 1, in the case of humidification with an aqueous medium, when the aqueous medium is water, the humidifying device 22 is installed in the box-shaped tank 1.
You may store it in 9.

As the sample solution whose concentration can be measured by the method of the present invention, sodium hydroxide, potassium hydroxide, barium hydroxide, ammonium hydroxide, sodium carbonate, potassium carbonate, barium carbonate, sodium bicarbonate, ammonia,
Examples thereof include alkaline solutions containing one or more organic bases and the like, and acidic solutions containing one or more hydrochloric acid, sulfuric acid, nitric acid, organic acids and the like.

In order to complete the dissolution and neutralization reaction of the reagent gas and the sample solution in the reaction zone, the sample solution layer and the reagent gas layer which are alternately formed at the lower part of the reaction zone are 0.02 to 4 mm and 0.01 to 2 mm, respectively. Is preferably a thin film layer of.

Needless to say, the respective flow rates of the sample solution and the reagent gas in the reaction zone are important factors for alternately forming the sample solution thin film layer and the reagent gas thin film layer in the lower portion of the reaction zone.

Further, the flow rate of the reagent gas is theoretically equal to or higher than the equivalence, but the reaction zone is raised while the sample solution thin film layer and the reagent gas thin film layer are alternately formed under the reaction zone to complete the reaction. Therefore, a flow rate of 0.7 to 4.5 times the equivalent weight, preferably 0.8 to 4.0 times the equivalent weight is selected. To further explain, in order to complete the dissolution and the neutralization reaction of the reagent gas in the sample solution in the reaction zone while alternately forming the reagent gas thin film layer and the sample solution thin film layer in the lower part of the reaction zone, It is necessary to use an appropriate tube diameter for the reaction tube 9 according to the set supply amounts of the sample solution and the reagent gas, and the reaction tube 9 has a constant volume in order to quickly detect the concentration fluctuation in the sample solution. is necessary. Therefore, the reaction tube 9
If the tube diameter is selected, the length of the reaction tube 9 is naturally determined. For example, when the tube diameter of the reaction tube 9 is reduced to form an elongated tube, a reagent gas layer and a sample solution layer are alternately formed, but a thin film layer is not formed, and the reaction is discharged from the reaction tube 9 incompletely. Therefore, the temperature detection is unstable. On the contrary, when the diameter of the reaction tube 9 is increased to a short reaction tube, the reagent gas is bubbled in the sample solution in the lower part of the reaction zone, the reaction proceeds, and the secondary reaction (for example, the sample solution is sodium hydroxide). When the solution and the reagent gas are carbon dioxide gas, sodium carbonate is changed to sodium bicarbonate) and the reagent gas is further required in excess. When the supply of the sample solution is interrupted at this time, a liquid pool is formed in the reaction layer 9 and the secondary reaction is more likely to occur. When the sample solution is a sodium hydroxide solution and the reagent gas is carbon dioxide gas, the precipitation occurs. It should be noted that the substance (crystals of sodium bicarbonate) may clog the reaction tube 9 and interfere with continuous measurement.

As described above, the flow rate of the sample solution in the reaction tube 9 in the method of the present invention is 0.25 to 35.3 cm / min, preferably
0.85-4.50 cm / min, and reagent gas flow rate is 6.3-884
cm / min, preferably 28 to 176 cm / min.

The diameter of the reaction tube 9 is 4 to 15 mmΦ, preferably 6 to
8 mmΦ, and the ratio of the length of the reaction tube 9 to the tube diameter is 30 to 200, preferably 35 to 60.
Is desirable.

Therefore, the supply amount of the sample solution in the method of the present invention is
2 to 20 ml / min, preferably 3 to 9 ml / min, and the supply amount of the reagent gas is 50 to 500 Nml / min, preferably 100 to 350 Nml / min.
It is desirable to be min.

The reagent gas preferably has high purity, but a gas diluted with an inert gas can be used. However, if the purity is too low, a temperature difference will occur between the sample solution thin film layer and the reagent gas thin film layer after the reaction, temperature detection will become unstable, and the measurement sensitivity will decrease, so be careful when using a low purity gas. Requires.

As the reagent gas used in the method of the present invention,
Examples thereof include acidic gas such as carbon dioxide gas, hydrogen chloride gas, sulfurous acid gas and nitric oxide gas, and alkaline gas such as ammonia and methylamine. It is necessary to appropriately select these reagent gases according to the target component whose concentration in the solution to be measured is to be measured. In the measurement of the alkali concentration in an alkaline sample solution using an acidic reagent gas, which is a preferred embodiment, for example, in the case of measuring only the concentration of sodium hydroxide in an alkaline aqueous solution system in which sodium hydroxide and sodium carbonate coexist, a reagent gas is used. Is preferably a weak acid gas such as carbon dioxide gas, and when a strong acid gas such as hydrogen chloride gas is used, it also reacts with sodium carbonate, making accurate measurement impossible.

In addition, in the method of the present invention, when the humidifying device 22 is previously humidified with the aqueous medium by using the aqueous medium, as described above, the reagent gas may be bubbled in the aqueous medium. However, an automatic replenishment humidifier using the capillary principle (for example, the reagent gas part and the aqueous medium part are separated by a ceramic filter or a permeable resin membrane to prevent the reagent gas from dissolving in the aqueous medium part, and only the aqueous medium is ceramic). A device adapted to be automatically replenished to the reagent gas portion through a filter or a capillary tube of a permeable resin membrane) may be used.

That is, in the case where the reagent gas is not humidified by using the aqueous medium in advance, if the supply of the reagent gas is once stopped and then resupplied or the supply of the reagent gas is reduced, the reaction part 5
In, the sample solution introduced from the sample solution inlet 7 flows into the reagent gas inlet 10 in reverse, and the reagent gas is dissolved and neutralized in the sample gas at the reagent gas inlet 10 to deposit a reaction product and dry. As a result, the reagent gas inlet 10 may be blocked, which may interfere with continuous measurement of the alkali or acid concentration of the sample solution.

Water is usually used as the aqueous medium for humidifying the reagent gas, but it is not suitable for the neutralization reaction between the reagent gas and the sample solution, such as water-soluble organic solvents such as methanol, ethanol, butanol, and neutral salts such as salt. It is also possible to use water which contains active substances.

The degree of humidification of the reagent gas is 30 to 150%, preferably 50 to 130%, and more preferably 80 to 100% in relative humidity.

There is no problem with the supply temperature of the reagent gas and the sample solution pre-humidified as described above as long as the temperature at which the neutralization reaction occurs rapidly, but considering the ease of temperature adjustment, it is desirable to be around room temperature. Further, when there is a difference in the supply temperature between these, the temperature difference before and after the reaction may be small, and the measurement sensitivity may be lowered. Therefore, it is preferable that the supply temperatures of the reagent gas and the sample solution are the same in advance. A resistance thermometer is usually used to detect the temperature, but a thermocouple element, a thermistor element, or the like can also be used. As a means for obtaining the temperature difference, a differential resistance type thermometer is used in FIG. 1, but another method, for example, after amplifying the potential difference of each thermocouple, the subtracter obtains the temperature difference. You can also As thermocouple, copper-constantan, chromel-
Known thermocouples such as alumel, iron-constantan and the like can be used.

In order to convert the temperature difference between the inlet and the outlet of the reaction tube 9 which is differentially taken out by the temperature difference measuring device 15 into the alkali or acid concentration of the sample solution, the concentration of the sample solution can be measured by the method of the present invention. For all combinations with the reagent gas used by the method of the present invention, the temperature difference between the inlet and the outlet of the reaction tube is previously measured by the method of the present invention by using several kinds of sample solutions having known alkali or acid concentrations. Then, the relationship between this temperature difference and the alkali or acid concentration of the sample solution may be obtained.

As described in detail above, according to the present invention, the reaction product in the sample solution in the measuring method previously proposed by the present inventors in the specification of Japanese Patent Application No. 63-42142 (JP-A-1-217251) is used. In addition to the effect of preventing clogging of the reaction tube, the reagent gas inlet can also be prevented from clogging because a pre-humidified reagent gas is introduced into the reaction zone, and the alkali or acid concentration of the sample solution can be maintained accurately. It is possible to measure it.

Moreover, it is cheaper than well-known titrators,
It has various advantages such as simple operation principle and no need for preparation of reagents, and in particular, as described above, it is suitable for a continuous analysis method because it does not cause clogging of the reaction tube body and the reagent gas inlet of the reaction tube.

Further, if the detected value obtained by the method of the present invention is used for the opening / closing operation of the alkali or acid concentration control valve, the alkali or acid concentration can always be automatically kept within a specific range. Furthermore, the method of the present invention can be widely used not only for the above-mentioned neutralization reaction accompanied by an exothermic reaction, but also for the measurement of a reaction between a gas and a solution or a liquid which causes other exothermic reaction or endothermic reaction.

[Examples and Comparative Examples]

Next, the method of the present invention will be specifically described with reference to examples and comparisons.

Example 1 In the step of hydrolyzing 11-cyanoundecanoic acid with sodium hydroxide to produce dodecanedioic acid-Na salt,
The sodium hydroxide concentration in the circulating liquid of the dodecanedioic acid-Na salt reaction tank was continuously analyzed by the method of the present invention, using the apparatus shown in FIG. 1 as an industrial analyzer. Dodecanedioic acid-Na salt and sodium hydroxide (1.5 to 3.5% by weight) coexist in the alkaline aqueous solution in the circulating liquid, and carbon dioxide is used as the reagent gas in order to measure only the sodium hydroxide concentration thereunder. Gas was used. The purpose of this measurement is to make the concentration of coexisting sodium hydroxide within the range of 1.0 to 2.0% by weight based on the dodecanedioic acid-Na salt produced by hydrolyzing 11-cyanoundecanoic acid with sodium hydroxide. To adjust the supply of sodium hydroxide. Second
The reaction tube consisting of the components shown in the figure is 8 mmΦ x 300 mm (made of Teflon), a resistance thermometer (temperature measuring body) is used to detect the temperature, and the concentration scale is displayed on the scale 16 to measure the temperature difference. The temperature difference differentially taken out by the vessel 15 was converted to a sodium hydroxide concentration of 0 to 5% by weight in advance and calibrated. The flow rate of the sample solution was 8.5 ml / min, and carbon dioxide gas as a reagent gas (purity 99%)
Was measured by supplying water after humidifying (relative humidity 100%) in water in advance from a carbon dioxide gas cylinder at a flow rate of 160 Nml / min.

As a result, the measurement sensitivity was good, and the measurement error was 2% or less of the total sodium hydroxide concentration scale, and the accuracy was extremely high.

Further, in order to continue the continuous supply of carbon dioxide gas, the carbon dioxide gas cylinder was replaced in two months. At that time, the supply of carbon dioxide gas was once stopped and re-supplied, but the reaction tube 9 due to precipitation and solidification of the reaction product Not to mention the inside, there was no trouble of blocking the carbon dioxide gas inlet portion (reagent gas inlet 10) to the reaction tube 9.

Furthermore, the concentration of sodium hydroxide, which is the measurement purpose, is 1.0
It was also possible to adjust the supply of sodium hydroxide so that it was within the range of ~ 2.0% by weight.

Comparative Example 1 The procedure of Example 1 was repeated except that carbon dioxide gas (purity 99%) was not previously humidified with water (relative humidity 100%). The carbon dioxide gas flow rate of 160 Nml / min was supplied and read, and the carbon dioxide gas cylinder was replaced in 1.5 months. At that time, when the carbon dioxide gas supply was stopped and re-supplied, the carbon dioxide gas stopped flowing after about 8 hours. The neutralization reaction in the reaction tube 9 stopped. After dismantling the device for inspection,
No abnormality was found in the reaction tube 9, but the carbon dioxide gas inlet (reagent gas inlet 10) was blocked.

Example 2 The same procedure as in Example 1 was carried out except that the carbon dioxide gas flow rate was reduced from 160 Nml / min to 100 Nml / min. As a result, the measurement sensitivity was good, and the measurement error was 2% or less of the total sodium hydroxide concentration scale, and the accuracy was extremely high.

In addition, there was no trouble of blocking the carbon dioxide gas inlet (reagent gas inlet 10) to the reaction tube 9 as well as the inside of the reaction tube 9 due to precipitation and solidification of the reaction product.

Furthermore, the concentration of sodium hydroxide, which is the measurement purpose, is 1.0
It was also possible to adjust the supply of sodium hydroxide so that it was within the range of ~ 2.0% by weight.

Comparative Example 2 Carbon dioxide gas (purity 99%) was not previously humidified with water (relative humidity 100%), and the flow rate of carbon dioxide gas was 160%.
The same procedure as in Example 1 was carried out except that the amount of Nml / min was reduced to 100 Nml / min. After about 8 hours, carbon dioxide gas stopped flowing and the neutralization reaction in the reaction tube 9 stopped. When the apparatus was disassembled for inspection in the same manner as in Comparative Example 1, no abnormality was found in the reaction tube 9, but blockage of the carbon dioxide gas inlet portion (reagent gas inlet 10) was observed.

[Explanation of effects]

As described above, the method of the present invention, when the supply of the reagent gas is temporarily stopped and re-supplied or the supply of the reagent gas is reduced while the prescribed amount of the sample solution is supplied, the reagent of the measuring device is used. The sample solution flows back to the gas inlet, and the reagent gas inlet is clogged due to precipitation, solidification, and drying of the reaction product due to the neutralization reaction between the reagent gas and the sample solution at the reagent gas inlet, and the sample solution However, there is a problem that it interferes with continuous measurement of alkali or acid concentration. Japanese Patent Application No. 63-42142 (Japanese Patent Application Laid-Open No. 1-217251) previously proposed by the present inventors.
In contrast to the continuous alkali or acid concentration measuring method described in the specification, when the reagent gas supply is interrupted or the supply amount is reduced, the sample solution flows back to the reagent gas inlet, and Even if the reaction product is deposited by the wa
In order to use the reagent gas by previously humidifying it with an aqueous medium, for example, the reaction product deposited at the reagent gas inlet is dissolved in the aqueous medium and then supplied to the reaction tube, which causes clogging of the reagent gas inlet. The present invention is effective in providing a continuous alkali or acid concentration measuring method.

[Brief description of drawings]

FIG. 1 is a flow chart showing an example of a continuous alkali or acid concentration measuring device used in the method of the present invention. FIG. 2 is an enlarged schematic vertical sectional front view of the reaction part 5 in FIG. 1; quantification device, 2; quantification device, 3; temperature control unit, 4; constant temperature bath, 5; reaction unit, 6; gas-liquid separation unit, 7; sample solution inlet, 8; pre-reaction temperature detector, 9; reaction Tube, 10; Reagent gas inlet, 11; Post-reaction temperature detector, 12; Reaction tube upper outlet, 13; Gas-liquid separating section upper outlet, 14; Gas-liquid separating section lower outlet, 15; Temperature difference measuring device, 16; Scale, 17; pressure reducing valve, 18; flow meter, 19; box tank, 20; heat medium inlet,
21; heat medium outlet, 22; humidifier, 23; aqueous medium inlet, 24; aqueous medium outlet.

Claims (1)

[Claims] 1. A neutralizing reagent gas, which has been pre-humidified and is in excess relative to the sample solution, and the sample solution are continuously supplied to a vertical reaction tube covered with a heat insulating material in a constant amount. And a reagent gas layer and a sample solution layer are alternately formed from the reagent gas and the sample solution in the lower part of the reaction zone of the reaction tube, and the reaction tube is raised to form a sample solution of the reagent gas. A sample solution characterized by continuously calculating the alkali or acid concentration of the sample solution by calculating the amount of heat generated by the dissolution in water and the neutralization reaction from the temperature difference between the inlet and outlet of the reaction tube. Method for measuring alkali or acid concentration.