JP2000317208A - Continuous gas extractor and continuous analyzer for analyzing free carbonic acid and dissolved inorganic carbonic acid in water using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a continuous gas extractor for continuously and instantaneously extracting all amount of gas dissolved in water and a continuous analyzer for analyzing free carbonic acid and dissolved carbonic acid in water using the gas extractor. SOLUTION: This continuous analyzer for analyzing dissolved carbonic acid in sample water is constituted of a mixing vessel 32 for mixing 0.3-10 ml/min sample water with 50-1,000 ml/min air, an extraction tube 33 which is connected to the mixing vessel and helically formed from a reaction tube made of Teflon (registered trade mark) having a 0.5-10 mm inside diameter and a >=0.5 m length and a separator 34 connected to the extraction tube 33. And a continuous gas extractor 31 for instantaneously extracting all amount of gas dissolved in sample water during discharge air, a continuous analyzer for analyzing free carbonic acid in sample water, supplying a specific amount within a range of sample water and air not containing carbon dioxide to the mixing vessel 32 and leading the exhaust air of the separator 34 through a dehumidifying device 41 to an infrared ray CO2 analyzer, and a pretreatment section adding a certain amount of acid to the sample water so as to control the pH of the sample water to 3 or less are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an extractor for continuously extracting gas dissolved in water, particularly carbon dioxide, and a continuous analyzer for free carbon dioxide in water and inorganic carbon dioxide dissolved in water.

[0002]

2. Description of the Related Art In recent years, the trend of carbon dioxide in the atmosphere has become a problem in connection with global warming, and in this connection, carbon dioxide in water, especially in seawater, has become a problem. Carbon dioxide in seawater must be analyzed throughout the day and night and throughout the seasons. Carbon dioxide in seawater is carbonate ion,
Dissolves in the form of bicarbonate, hydrated and free carbonic acid. In addition, they are made organic by the action of carbonates, bicarbonates and microorganisms.

Conventionally, a bubbling method has been used for extracting free carbonic acid in water. FIG. 5 is a system diagram of the bubbling method, and includes a bubbler 1, an air purifier 2, and a CO ₂ analyzer 3. The bubbler 1 includes a container 4, an air supply pipe 5, and an air discharge pipe 6. The air supply pipe 5 reaches near the bottom surface of the container 4, has a closed end, and has a number of small holes 7 formed near it. The air purifier 2 has a blower 8 and a purifier 9 for charging a decarbonating agent and controlling the flow rate. The CO ₂ analyzer 3 includes a dehumidifier 10 and an infrared CO ₂ analyzer 11. A certain amount of sample water 12 is collected in the container 4, and a constant flow rate of air containing no carbon dioxide gas is guided from the supply pipe 5 to near the bottom of the container 4, and the sample water 1 is foamed from the small holes 7.
The free carbonic acid released into the sample water 2 is extracted by air, dehumidified by a dehumidifier 10 and analyzed by an infrared CO ₂ analyzer.

In order to analyze dissolved inorganic carbonic acid in water,
The sample water is adjusted to pH 3 or less with phosphoric acid or the like, and carbonate ions and bicarbonate ions are converted to free carbonic acid. In order to analyze the total dissolved organic carbon in water, the sample water is irradiated with ultraviolet rays or the like to decompose organic substances in the water into dissolved inorganic carbonic acid, and then to pH 3 or less with phosphoric acid or the like. Is converted to free carbonic acid, and the dissolved inorganic carbon previously determined is subtracted from the calculated value.

[0005]

In the above-mentioned bubbling method, it takes about 5 minutes to quantitatively extract dissolved gas in water, and the operations are (a) introduction of sample water and (b)
It is difficult to continuously automate high-speed response such as setting of bubbler and (c) supply and stop of air. The amount of carbon dioxide gas calculated from the CO ₂ concentration in the air measured by the infrared CO ₂ analyzer is calculated by the total bubbling time. There is a problem that a complicated calculation for integrating over (about 5 minutes) is required.

SUMMARY OF THE INVENTION An object of the present invention is to provide a continuous gas extractor in which the total amount of dissolved gas in water is continuously and instantaneously extracted, and to extract free carbonic acid in water into the air by using the same. It is an object of the present invention to provide a continuous analyzer for free carbonic acid which can easily calculate the free carbonic acid in water from the concentration of carbonic acid gas in the extracted gas.

[0007]

According to the present invention, there is provided a recording medium having a size of 0.3 to 10 mm.
ml / min sample water and 50-1000 ml / min
And a mixer for mixing the sample water with air, one end of which is connected to the mixer to guide a mixed fluid of the sample water and the air.
５5.0 mm, a spiral Teflon extraction tube having a length of 0.3 m or more, and a separator connected to the other end of the communication tube and separating the mixed fluid into drainage and exhaust. The feature is a continuous gas extractor.

According to the present invention, the sample water and the air mixed in the mixer proceed at a high speed in the extraction tube with the gas phase and the liquid phase separated, and the liquid phase (water) and the gas flow. The phase boundaries fluctuate violently, and the dissolved gases in the liquid phase are extracted into the gas phase. Thereby, the dissolved gas is quantitatively extracted by the separator.

If the inner diameter of the extraction tube is less than 0.5 mm, it is difficult for water to flow down the extraction tube at high speed due to the viscosity of the water. If the inner diameter of the extraction tube exceeds 5.0 mm, quantitative extraction becomes difficult, and the supply amounts of sample water and air increase in order to obtain a high speed in the extraction tube. From these facts, the above-mentioned range of the inner diameter of the extraction tube was experimentally obtained by the present inventors. The length of the extraction tube, when the inner diameter of the extraction tube is in the above range,
If it is 0.3 m or more, the dissolved gas is almost quantitatively extracted by the separator. The upper limit of the length of the extraction tube is not particularly limited, but is preferably 5.0 m or less.

The inventors have experimentally determined the supply amounts of the sample water and air when the inner diameter of the extraction tube is set to the above range. The material of the extraction tube is preferably a Teflon tube because it is not corroded by sample water, particularly acidic sample water, and is not damaged and easy to handle. In order to make the shape compact, the extraction tube is processed into a spiral shape.

[0011] The present invention also relates to a method for supplying a sample water from a means for supplying a constant flow rate of a sample water within a range of 0.3 to 10 ml / min to a mixer of the continuous gas extractor;
and supplying air from a means for supplying a constant flow rate of carbon dioxide-free air within a range of ml / min, and guiding exhaust gas from the separator to an infrared carbon dioxide gas analyzer via a dehumidifier. It is a continuous analyzer of free carbonic acid in water.

According to the present invention, carbon dioxide-free air is used to extract free carbonic acid in water. Carbon dioxide-free air is easily obtained by passing the air through a layer of soda lime or silica gel. The exhaust gas from the separator passes through a dehumidifier, and the concentration of carbon dioxide is measured by an infrared CO ₂ analyzer. An infrared CO ₂ analyzer can accurately and continuously analyze the concentration of carbon dioxide in a gas. Further, in the present invention, the concentration of carbon dioxide in the extracted gas is proportional to the amount of free carbon in the sample water.

Further, the present invention is characterized in that a predetermined amount of acid is added to the continuous analyzer for free carbonic acid in water and a pretreatment unit for adjusting the pH of the sample water to 3 or less is added. It is an analyzer.

According to the present invention, a fixed amount of acid is added to the sample water in the pretreatment section to lower the pH to 3 or less, so that the dissolved inorganic carbonic acid in the sample water is changed to free carbonic acid. As a result, the dissolved inorganic carbonic acid is analyzed as an amount proportional to the carbon dioxide in the extracted gas. Further, if a pretreatment unit for irradiating the sample water with ultraviolet rays is added, the total dissolved carbon amount in the water can be continuously measured, and if the dissolved inorganic carbon amount is subtracted therefrom, the dissolved organic carbon amount can be continuously measured.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to embodiments.

FIG. 1 is a system diagram of a continuous analyzer 20 of dissolved inorganic carbonic acid in water according to one embodiment of the present invention.

The sample water, for example, seawater is supplied to the switching valve 21
After that, the liquid is fed to the liquid-liquid mixer 23 at a constant flow rate, for example, 2 ml / min, by the constant-rate liquid sending pump 22. On the other hand, the phosphoric acid (H ₃ PO ₄ ) solution having a concentration of 0.5 mol / l is supplied at a constant flow rate, for example, 1 ml by the liquid sending pump 30.
/ Min to the liquid-liquid mixer 23. Since it has been confirmed in advance that seawater and the phosphoric acid solution have a pH of 3 or less and 2 in the present embodiment when mixed at a ratio of 2: 1 (volume), At the outlet of the mixer 23, the seawater has a pH of 3 or less, and the carbonate ions and bicarbonate ions in the seawater are considered to be free carbonic acid. The pH-adjusted seawater is sent to the gas-liquid mixer 32. The gas-liquid mixer 32 is supplied with air from which a carbon dioxide gas has been removed from the blower 26 via the soda lime layer 27 and the silica gel layer 28 by controlling the gas flow controller 29 at a constant flow rate, for example, 200 ml / min. And the two are thoroughly mixed.

FIG. 2 is a perspective view of the continuous gas extractor 31 according to one embodiment of the present invention. The continuous gas extractor 31 includes a gas-liquid mixer 32, an extraction pipe 33, and a gas-liquid separator 34. In the extraction pipe 33, the gas phase 36 flows down at a high speed in a state where the gas phase 36 narrows between the liquid phases 35, and the contact surface between the liquid phase 35 and the gas phase 36 flows violently, so that the liquid phase ( Free carbonic acid in the (seawater) 35 is extracted into the gas phase (air) 36. This extraction is quantitatively completed by the time the gas-liquid mixture reaches the gas-liquid separator 34. Extraction tube 33
Is, for example, 1/16 ″ inside diameter (1.59 mm), 1 outside diameter
/ 8 "(3.175 mm) 1 m long Teflon reaction tube formed into a spiral shape. Gas-liquid separator 34
Has a cylindrical portion 37 and a truncated cone portion 38 whose cross-sectional areas are sufficiently larger than the reaction tube, and the liquid level is in the cylindrical portion 37 and the drain pipe 3
The configuration is such that bubbles in the seawater sufficiently float in the gas phase while the seawater flows down to 9, and an exhaust pipe 40 is connected to the gas phase. The gas phase 36 in the extraction pipe 33 is collected in the gas phase of the gas-liquid separator 34 and sent to the exhaust pipe.

The exhaust pipe 40 is provided with a calcium chloride layer and a magnesium perchlorate layer (these layers do not absorb carbon dioxide).
Infrared CO ₂ analyzer 4 through a dehumidifier 41
2 and the concentration of carbon dioxide in the exhaust gas is analyzed.

FIG. 3 shows the concentration of sodium carbonate in water and
This water was used as the dissolved inorganic carbonic acid continuous analyzer 20 of the above embodiment.
5 is a graph showing the relationship between the output of the infrared CO ₂ analyzer and the output (concentration of carbon dioxide in exhaust gas). FIG. 3 shows that there is a linear relationship between the two.

The switching valve 21 in FIG. 1 switches between sample water, standard water 1 containing more than the amount of dissolved inorganic carbonic acid in the sample water, and standard water 2 containing less than the amount of dissolved inorganic carbonic acid, and measures the dissolved inorganic carbonic acid in those waters. In addition, the measurement value of the dissolved inorganic carbonic acid in the sample water is corrected, and the correction may be performed several times a day.

FIG. 4 is a graph showing the relationship between the length and the amount of extraction when a Teflon tube having an inner diameter of 1/16 "and an outer diameter of 1/8" is used for the extraction tube 33. The length of the extraction tube 33 is set to 0.
Almost all (95% or more) is extracted at 5 m, and hardly changes at 1 m or more. The flow rate of water in this test was 3
ml / min, and the flow rate of air was 200 ml / min.

The continuous gas extractor of the present invention can be used not only for continuous analysis of free carbonic acid in water but also for extraction of a gas which is easily dissolved in water, such as ammonia gas and cyan gas. For example, the extracted ammonia gas was absorbed in a dilute sulfuric acid solution, and the change in the conductivity of the absorption solution was measured to quantify the amount of ammonia. Cyan gas was absorbed in a sodium hydroxide solution, and the cyan concentration in the absorbing solution was determined by an ion-selective electrode. Further, the continuous analyzer for free carbonic acid in water of the present invention performs a pretreatment of irradiating the sample water with ultraviolet rays, and subtracts the dissolved inorganic carbon amount from the total dissolved carbon amount in the water and the dissolved organic carbon amount from the total dissolved carbon amount. The amount could be analyzed. This is based on the fact that sulfuric acid sodium persulfate is added to the pretreatment and then ultraviolet rays are irradiated to dissolve dissolved organic carbon to form dissolved inorganic carbonic acid.

[0024]

As described above, according to the first aspect of the present invention, a sample mixed with air in a mixer by a reaction tube having an inner diameter of 0.5 to 5.0 mm and a length of 0.3 m or more. The dissolved gas in the water can be continuously extracted into the air. Further, since the extraction tube is constituted by a reaction tube made of Teflon processed into a spiral shape, handling is easy and compact.

According to the present invention as set forth in claim 2, free carbon dioxide in water is quantitatively extracted with air containing no carbon dioxide gas using the continuous gas extractor, and the extracted carbon dioxide is extracted with an infrared CO ₂ analyzer. Can be analyzed continuously.

According to the third aspect of the present invention, since a pretreatment unit for adding a certain amount of acid to a certain amount of sample water to lower the pH to 3 or less is added, the dissolved inorganic carbonate in the sample water is added. Is converted to free carbonic acid, and dissolved inorganic carbonic acid in water can be continuously analyzed.

[Brief description of the drawings]

FIG. 1 is a system diagram of a dissolved inorganic carbonic acid continuous analyzer 20 according to an embodiment of the present invention.

FIG. 2 shows a continuous gas extractor 3 according to an embodiment of the present invention.
1 is a perspective view of FIG.

3 is a graph showing the relationship between the amount of dissolved inorganic carbonic acid in water and the output of an infrared CO ₂ meter 42 using a dissolved inorganic carbonic acid continuous analyzer 20. FIG.

FIG. 4 shows an extraction pipe 33 of a continuous gas extractor 31 with an inner diameter of 1/1.
It is a graph which shows the relationship between length and extraction amount at the time of using a 6 "Teflon tube.

FIG. 5 is a sectional view of a conventional gas extractor (bubble) 1;

[Explanation of symbols]

REFERENCE SIGNS LIST 20 continuous underwater dissolved inorganic carbonic acid analyzer 22 fixed-quantity liquid sending pump for sample water 23 liquid-liquid mixer 25 fixed-quantity liquid sending pump for acid 31 continuous gas extractor 32 gas-liquid mixer 33 extraction tube 34 separator 41 dehumidifier 42 Infrared CO ₂ meter

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takeshi Nozaki 383-7 Ozu Bean, Tsukuba City, Ibaraki Prefecture (72) Inventor Setsuko Kudo 208F, 208 Sanma-dori, Nanyo-shi, Yamagata 10F term (reference) 2G057 AB02 2G059 AA01 BB01 CC04 DD01 DD04 HH01 4D011 AA15 AC04

Claims (3)

[Claims] 1. A sample water of 0.3 to 10 ml / min,
A mixer for mixing 50 to 1000 ml / min of air, one end of which is connected to the mixer, for guiding a mixed fluid of the sample water and air, an inner diameter of 0.5 to 5.0 mm, a length of 0.3 m or more A continuous gas extractor comprising: a Teflon-made extraction pipe formed in a spiral shape; and a separator connected to the other end of the communication pipe and separating the mixed fluid into drainage and exhaust. 2. A sample water from a means for supplying a constant flow rate of sample water within a range of 0.3 to 10 ml / min to the mixer of the continuous gas extractor according to claim 1, and 50 to 1000 ml / min. And supplying air from a means for supplying a constant flow of carbon dioxide-free air within the range of (a), and directing exhaust air from the separator according to claim 1 to an infrared carbon dioxide analyzer via a dehumidifier. A continuous analyzer for free carbonic acid in water characterized by the following. 3. A dissolved inorganic substance in water, characterized in that a predetermined amount of an acid is added to the continuous analyzer for free carbonic acid in water according to claim 2, and a pretreatment unit for adjusting the pH of the sample water to 3 or less is added. Carbonic acid continuous analyzer.