JPS63182569A - Temperature controller for flow type analyzer - Google Patents

Abstract

PURPOSE:To control the temp. of a test liquid to a constant temp. with high accuracy and to improve the accuracy of an analysis by providing a thermostatic chamber for a piping just before supply of the test liquid to a detection part in a thermostatic chamber as well. CONSTITUTION:Water 11, standard phosphoric acid soln. 12, electrolyte 13, etc., of a measurement part 25 are supplied through a mixing pipe by metering pumps 17, 18 to the detection part 21 in the thermostatic chamber 22 for the detection part, by which a flow analysis is executed. The thermostatic chamber for the piping including the pipe 19 just before said chamber 22 is also provided. The temp. of the test liquid is controlled to the constant temp. with the higher accuracy than in the case in which said chamber is not provided. The accuracy of the analysis is thus improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a temperature control device for a flow type analyzer in which a test liquid continuously flows through a detection section of the analyzer.

[Conventional technology]

If the analyzer changes its output under the influence of temperature,
To obtain correct measured values, it is necessary to perform temperature correction on the detected output using a conversion formula that takes into account the influence of temperature, or to control the temperature of parts affected by temperature, such as the detection section, to a constant temperature.

However, temperature correction can be used when the effect of temperature on the analyzer can be expressed as a conversion formula, but it can be used, for example, when chemical reactions and electrode reactions are combined and the reaction rate increases above a certain temperature. It is difficult to correct using a conversion formula in the case of an analyzer in which the temperature of the analyzer is the same, and in such a case, it is necessary to control the temperature of the analyzer.

This invention relates to this temperature control. - In a flow type analyzer, the test liquid continuously flows through the detection section, so in order to make accurate measurements, it is necessary to keep the temperature around the detection section constant. At the same time, it is necessary to keep the temperature of the test solution constant. This temperature control is easy when the analyzer is installed indoors because the temperature changes are small, but it becomes difficult when the analyzer is used outdoors where the temperature changes rapidly. Conventionally, as shown in Figure 3, only the detection part is placed in a constant temperature bath with air as the heat medium, or the detection part and the piping connected to the detection part are placed in a constant temperature bath with liquid as the heat medium. .

The analyzer, which consists of a detection unit, recorder, pump, chemical tank, etc., was housed in a constant temperature bath.

[Problem that the invention seeks to solve]

However, in the above-mentioned conventional technology, when only the detection part is placed in a thermostatic chamber, the temperature of the test liquid changes with the temperature inside the analyzer, so even if the temperature around the detection part is constant, the temperature inside the detection part remains constant. The disadvantage is that the temperature of the liquid is not necessarily constant, which reduces the accuracy of analysis. Also,
If the detection part and the piping connected to the detection part are placed in a constant temperature bath using liquid as a heat medium, the temperature can be controlled well, but it may not be possible to use it if the structure of the detection part is not suitable for a liquid immersion structure. In addition, even if an immersion structure was possible, it would be inconvenient to take it out from the heat medium liquid during maintenance.

Furthermore, when the entire analyzer is housed in a thermostatic chamber, in order to control temperature fluctuations within 1'c, it is necessary to cut off heat transfer from the outside world, so the insulation material must be sufficiently thick. The entire analyzer has become very large. Moreover, if there is a heat source such as a heater or a lamp inside the analyzer, it is difficult to control the temperature within I'C.

This invention has been made in view of the above-mentioned points, and its purpose is to meet the requirements of consistency of the heat medium with the detection section, ease of maintenance of the detection section, and miniaturization of the analyzer itself. The flow-type analyzer is designed to satisfy the above requirements, and also enables high analysis accuracy by precisely controlling the temperature of the test liquid inside the detection part to a constant value even in cases where the temperature inside the analyzer chamber changes significantly. An object of the present invention is to provide a temperature control device.

[Means for solving problems]

According to the present invention, the above object is achieved in a flow type analyzer in which a test liquid continuously flows through the detection section 21 of the analyzer.
A constant temperature bath 22 for the detection section that houses the detection section 21 and controls the temperature of the detection section to a predetermined value, and a piping 19 just before the detection section that sends a test liquid to the detection section, This is achieved by including a constant temperature bath 20 for piping that controls the temperature of the test liquid flowing therein to a predetermined value.

[Effect]

A constant temperature bath 19 for the piping is provided in addition to the constant temperature bath 22 for the detection part, so even if the temperature inside the chamber changes greatly, the temperature of the test liquid is controlled to a constant temperature by the constant temperature bath 19 for the piping, so that the influence of the temperature change is reduced. It disappears. Also, a constant temperature bath 22 for the detection part and a constant temperature bath 20 for piping.
Since these are independent, there is a constant temperature bath 22 for the detection part.
The heat medium that is most suitable for the detection part can be used.
Maintenance of the detection unit also becomes easier. Furthermore, since it is only necessary to provide a heat insulator for each thermostatic chamber, the entire analyzer can be made smaller.

〔Example〕

Next, embodiments of the present invention will be described based on the drawings. A flow type analyzer will be explained using a total phosphorus analyzer as an example. The total phosphorus analyzer includes an oxidation processing section (not shown) that oxidizes and decomposes phosphorus compounds in the wastewater and converts them into phosphoric acid, and a reduction section that reduces noise by reducing interfering compounds in the oxidation and decomposition processing solution. (not shown), phosphoric acid is reacted with an electrolytic solution containing molybdenum to form a phosphorous molybdenum complex, which is led to an electrolytic cell which is the detection section 21, and the complex is electrochemically reduced. It consists of a measuring section (see Fig. 1) that determines the amount of phosphorus based on the magnitude of the reduction current.

The oxidative decomposition treatment of the phosphorus compounds in the waste liquid is carried out by making the waste liquid acidic with a pH of 3 or less, and heating it to a temperature of 80° C. or more while aerating ozone. In this oxidative decomposition treatment, phosphorus compounds are oxidized to lyorthophosphoric acid by ozone.

At this time, the chlorine ions contained in the water are also CIO.

It is oxidized to C and reduced in the electrolytic cell which is the detection part of the measuring part 25 to give a disturbing current.
Only IO, is returned. This reduction can be carried out using a reducing agent of sodium sulfite.

The effluent, in which all the phosphorus compounds in the waste water have been converted into phosphoric acid and the interfering CIO has been reduced and removed, is supplied to the measuring section 25 of the analyzer as shown in FIG.

The drainage liquid is supplied to the measuring section 25 by suction using the metering pump 17. The waste liquid is passed through a filter 14 to remove suspended solids therein. The metering pump 18 sucks the waste liquid sucked by the metering pump 17 and a predetermined amount of the electrolyte 13.

The electrolytic solution 13 is an acidic molybdic acid solution, which is a mixed reagent of sodium molybdate, sulfuric acid, and ethanol, and has a pH of 1.
Adjusted below. The drained liquid and the acidic molybdic acid liquid as the electrolyte are thoroughly mixed in the mixing tube 19 to form a test liquid. At this time, phosphoric acid and molybdic acid react to form a phosphomolybdenum complex [PM. (Vl), 204°Co3- is formed. The mixing tube 19 is a coil of stainless steel tube or thin-walled Teflon tube. The constant temperature bath 20 for piping is this mixing pipe 19
The temperature of the test liquid flowing inside the mixing tube 19 is controlled to a predetermined value. Water or silicone oil is used as the heat medium and is thoroughly stirred with a magnetic stirrer.

A test solution containing a phosphomolybdenum complex and controlled at a predetermined temperature is sent to an electrolytic cell, which is a detection section 21. The detection section 21 is an electrolytic cell as shown in FIG. The test liquid passes through the flow path 38 and reaches the electrolytic cell. In the electrolytic cell, carbon fibers are packed inside a diaphragm cylinder 32 as a working electrode 33, and a spiral platinum wire is arranged as a counter electrode 34 outside the diaphragm cylinder 32. Further, a silver-silver chloride reference electrode 35 is attached to a glass outer cylinder 36 arranged concentrically outside the diaphragm cylinder 32.

The space between the diaphragm cylinder 32 and the glass outer cylinder 36 is filled with the electrolytic solution 13. A lead carbon rod 37 is connected to a working electrode 33 made of carbon fiber and a voltage is applied thereto. The test solution flows inside the diaphragm cylinder 32 and is subjected to constant potential electrolysis.

The working electrode 33 made of carbon fiber is the silver-silver chloride reference electrode 3
5, and the electrolytic reduction current flowing between the working electrode 33 and the counter electrode 34 is recorded. Potentiometer stand 23 is used to operate constant potential electrolysis.
The reduction current is converted into voltage and input to the recorder 24. The reduction reaction of the phosphomolybdenum complex at the working electrode 33 is based on equation (1).

[PMO(Vl)12040ko'-+2e
-[PMo(V)Jo(Vl)+oO4o] '--
−−−−−−−−−−−・−−−−−−−−−−−−(
11 (The reduction current due to the reaction of equation 11 is proportional to the phosphorus concentration, so the phosphoric acid concentration can be determined from the value of this reduction current. The calibration curve is created using water 11 and phosphoric acid standard solution 12 in Figure 1. The inflow of waste liquid is stopped by operating the three-way valves 15 and 16.

The reduction reaction of phosphomolybdenum complexes in electrolytic cells is affected by temperature. FIG. 2 shows an example of the reduction current. Therefore, it is necessary to control the electrolytic cell to a predetermined temperature using a constant temperature bath 22 for the detection section.

In an electrolytic cell as shown in FIG. 4, a constant temperature bath 22 for a detection section using air as a heat medium is used. By using air as a heat medium, short circuits between the counter electrode 34, lead carbon rod 37, and silver-silver chloride reference electrode 35 can be prevented (temperature can be controlled, and the electrolytic cell can be easily disassembled for maintenance). can be done.

By providing a constant temperature bath 20 for the piping that houses the mixing tube 19, the temperature of the test solution in the detection section 21 can be maintained at a predetermined temperature even if the internal temperature of the total phosphorus analyzer changes greatly. Increases accuracy. Constant temperature chamber 20 especially for piping
When the heat medium used is a liquid, the heat exchange capacity is greater than when air is used as the heat medium, so the length of the mixing tube 19 can be shortened, and the accuracy of temperature control is improved. Providing the constant temperature bath 20 for piping not only absorbs fluctuations in the internal temperature, but also eliminates the effects of high-temperature treatment of the waste liquid in the oxidation processing section and reduction processing section provided before the measurement section 25. . Furthermore, as mentioned above, two thermostatic chambers are provided for the detection section and for the piping, so air can be selected as the heating medium for the detection section and water for the piping, allowing for matching of the heating medium to the electrolytic cell. It becomes possible to select the optimal heat medium for each thermostatic chamber in terms of performance, ease of maintenance of the detection part, and temperature controllability of the sample liquid in the piping.

If constant temperature baths are provided independently in the detection section 21 and the mixing tube 19, only a small amount of heat insulating material is required, and the entire analyzer can be made smaller than in the case where the temperature of the entire analyzer is controlled.

〔Effect of the invention〕

According to the present invention, in a flow type analyzer in which a test liquid continuously flows through a detection section of the analyzer, a constant temperature for the detection section that houses the detection section and controls the temperature of the detection section to a predetermined value is provided. The temperature of the flow-type analyzer is controlled by a tank and a constant hot water bath for the piping, which houses the piping just before the detection part that sends the test liquid to the detection part, and controls the temperature of the test liquid flowing inside the piping to a predetermined value. Since the device has been configured, even if the temperature inside the analyzer chamber changes, the temperature of the test liquid inside the detection section can be maintained at a predetermined value by eliminating the effect of the change in the thermostat for the piping, and as a result, the accuracy of analysis is improved. . Furthermore, it is possible to use the optimal heat medium for each of the thermostatic chamber for the detection section and the thermostatic chamber for the piping, which has the effect of making it easier to maintain the detection section and shortening the length of piping just in front of the detection section. It will be done.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a temperature control device according to an embodiment of the present invention, Fig. 2 is a temperature characteristic diagram of electrolytic reduction current of a phosphomolybdenum complex, Fig. 3 is a block diagram of a conventional temperature control device, and Fig. 4 FIG. 2 is a cross-sectional view of an electrolytic cell that is a detection section. 19: Mixing pipe, 20: Constant temperature bath for piping, 21: Detection part,
22: Constant temperature bath for the detection part. 0 10 20 30' 40 hot water counterfeit (0C) Fig. 2 25 regulation section

Claims (1)

[Scope of Claims] 1) In a flow type analyzer in which a test liquid continuously flows through a detection section of the analyzer, a detection section that houses the detection section and controls the temperature of the detection section to a predetermined value. and a constant temperature bath for the piping that accommodates the piping just before the detection part that sends the test liquid to the detection part and controls the temperature of the test liquid flowing inside the piping to a predetermined value. Temperature control device for flow type analyzers. 2) In the temperature control device according to claim 1, the flowchart is characterized in that the heating medium of the constant temperature bath for the detection section is gas, and the heating medium of the constant temperature bath for piping is liquid. Temperature control device for mold analyzer.