JPS6111647A - Concentration meter - Google Patents

Abstract

PURPOSE:To measure without the addition of a harmful substance by collecting the distilled component with heating the sample sampled by the fixed quantity sampling mechanism of a sample inside a evaporating can and by measuring the conductivity of the collected liquid thereof with a conductivity measuring cell. CONSTITUTION:An evaporation can 1 having cleaning mechanism, a distillater and collection part 2 having a fixed quantity pouring mechanism of pure water and clenning mechanism and a fixed quantity sampling mechanism 13 of a sample are provided. Conductivity is measured by a conductivity measuring cell by introducing the collected liquid from which the distilled component was collected by heating within the evaporation can 1 the sample sampled by the fixed quantity sampling mechanism 13 of the sample. There is thus no necessity of adding a harmful component to towers and tanks sort of a plant and a concentration meter suitable for the measurement of concentration of volatile component of a free hydrochloric acid and nitric acid, etc. in the sample including salt is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a concentration meter that determines the concentration of components in a liquid sample from measured conductivity values.

[Prior art and its problems]

Concentrators that measure salt or acid concentrations in a sample from conductivity measurements have the advantage of being able to measure without adding reagents to the sample, but when two or more types of solutes are present, Measurement becomes extremely difficult as the contributions cannot be distinguished.

Strong acid aqueous solutions such as nitric acid and hydrochloric acid have a large degree of dissociation and contain hydrogen ions with high equivalent conductivity, so they are suitable for use with a concentration meter that measures conductivity. There was a problem in that it could not be applied to the measurement of acid concentration because it contains a large amount of salt and the salt concentration fluctuates.

Titration is generally used to measure the acid concentration of samples containing such salts, but in this method, the titrant contains an alkali metal and a masking agent depending on the type of salt is mixed in. , it is difficult to return the measuring tube waste liquid to the sampling point. Particularly when the sample contains radioactive materials, there is a problem in that the treatment of this waste liquid becomes a major hindrance.

[Purpose of the invention]

The purpose of the present invention is to solve the above-mentioned problems of the prior art, and to be able to measure the concentration of volatile components such as free hydrochloric acid and nitric acid in samples containing salts without adding components, which are harmful to towers and tanks of plants. Our goal is to provide a suitable concentration meter.

[Summary of the invention]

The concentration meter according to the present invention uses a quantitative sampling mechanism to inject a fixed amount of sample into an evaporator, heats it at a temperature lower than the decomposition temperature of salt, and then pours the distillate into a fixed amount of pure water for collection. to be collected. This allows the contribution of salt to the conductivity measurements to be removed.

By setting the amount of pure water for collection to be sufficiently larger than the amount of distilled liquid, the amount of collection liquid is assumed to be constant, and the concentration of the component in the sample is determined from the measured value of the conductivity of the collection liquid.

〔Effect of the invention〕

The present invention is particularly effective for samples in which acids with relatively low boiling points, such as nitric acid and hydrochloric acid, and their O salts coexist.

Taking a solution containing a strong acid and its salt as an example, since only the free acid in the sample is distilled out, it can be applied as an acid concentration meter even to samples containing a large amount of salt. Furthermore, since the distillate is diluted in a large amount of pure water, conductivity can be measured at a constant temperature regardless of fluctuations in sample liquid temperature, and temperature compensation for conductivity is not necessary. Furthermore, since the measurement groove waste liquid is simply pure water added to the sample, there is no harm in returning the waste liquid to the sampling point.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a configuration diagram of a densitometer according to the present invention.

The evaporator 1 is made of a corrosion-resistant material such as tantalum, and has a sample and carrier gas inlet of 1 m and a carrier gas outlet of 1 m.
b, has a pure water supply port 1c and a drain port 1d, the outflow port 1b is connected to the distillate collection unit 2 via piping, and the pure water supply port 1c is connected to an external pure water supply (not shown) via an on-off valve 3. source and drain port 1
d are connected to drain pipes 5 via on-off valves 4, respectively. The distillate collection unit 2 has an exhaust port 2a opened via an on-off valve 6, a pure water inlet 2b connected to a pure water quantitative injection mechanism, for example, a piston cylinder 7, and a flow connected to an on-off valve 8. It has an inlet 2d connected to the outlet 2c and the outlet 1b, and the piping exiting from the outlet 2C is a flow path that passes through the detector 11 by switching the flow path switchers 9 and 10 on the downstream side of the on-off valve 8. The structure allows switching between the bypass flow path 12 and the bypass flow path 12. The sample quantitative collection mechanism 13 is composed of flow path switches 13a, 13b and a replacement pipe 13C, and forms a part of the sample circulation pipe 14, so that the inside of the replacement pipe 13C can be replaced with a sample. Similarly, pure water quantitative sampling mechanism 15
It is constructed of flow path switching devices 15a, 15b and replacement piping 15C, and forms a part of circulation piping 17 exiting from pure water storage tank 16, so that the inside of replacement piping 15C can be replaced with pure water. Furthermore, the flow path switching device 15b is connected to a gas supply source, for example, compressed air 19, via an on-off valve 18. In the initial state, the on-off valve 3゜4.8.18 is closed, the on-off valve 6 is open, and the flow path switches 9 and 10 are in the bypass flow path 1.
The detector 11 is opened to the second side and is filled with pure water.

For measurement, the flow path switching device 1 of the sample quantitative collection mechanism 13
3 a+ 13 bH and the flow path switchers 15a and 15b of the pure water quantitative sampling mechanism 15 are switched, and the replacement piping 13C,
Replace the inside of 15C with the sample and pure water, respectively. Then, when the flow path switching devices Ja, 13b, 15a, and 15b are switched and the on-off valve 18 is opened, the sample and pure water, which have been quantitatively separated, are pushed into the evaporator 1 by air pressure. The sample remaining in the pipe is washed away by the subsequent purified water, which is effective for quantitative performance and for preventing cross-contamination during repeated measurements. If the evaporator 1 is heated in advance to a set temperature and a certain amount of pure water is injected into the distillate collection section 2 using the piston cylinder 7, the pure water and sample that have entered the evaporator 1 will begin to evaporate. , is blown out from the inlet 2 d along with the air flow and collected by the pure water in the distillate collection section 2 . It is more preferable to lower the inlet port 2d below the level of the pure water injected in advance, since stirring can also be performed by blowing out air. When the distillation is completed, the on-off valve 8 is opened, the on-off valve 6 is closed, and a portion of the collected liquid is drained by air pressure through the bypass flow path 12. Then, the flow path switching devices 7 and 8 are simultaneously switched to the detector 11. Replace the inside with collection liquid. The excess collection liquid is completely drained through the bypass flow path 12 by switching the flow path switching devices 7 and 8 at the same time again. After measuring the conductivity of the collection liquid in the detector 11, the on-off valve 8
, open the on-off valve 6, inject pure water into the exudate collection section 2 using the piston cylinder 7, and perform the same operation to clean the exudate collection section 2 with pure water and clean the detector. 1
Perform pure water replacement in 1. Next, the on-off valves 8 and 18 are closed, and the on-off valve 3 is opened to overpressurize pure water from the pure water supply port IC to dissolve and remove the residue in the evaporator 1. One measurement is completed by the above operation, and by repeating this, continuous measurements can be performed.

If the ratio of the amount of pure water injected into the distillate collection section 2 and the amount of sample and pure water injected into the evaporator 1 is set large, the proportion of the amount of distillate in the total collected liquid will be sufficiently small. The error in determining the amount of volatile components in the sample from the measured conductivity of the collected liquid is small. In addition, if the temperature of the pure water for collecting distillate is kept constant, the temperature increase due to contamination with distillate will be small.
Even when the sample liquid temperature fluctuates rapidly, it is possible to reduce errors caused by temperature compensation. Furthermore, since nothing other than pure water is added to the sample, there is no harm in returning the analysis sample to the sampling point. This concentration meter is particularly effective for samples containing a mixture of acids and their salts that volatilize at relatively low temperatures, such as nitric acid and hydrochloric acid, but since some nitrates thermally decompose at low temperatures, It is preferable to maintain the temperature below the thermal decomposition temperature of the salt, and it is even more preferable to add a temperature control mechanism that measures the temperature of the evaporator and adjusts the heating.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a densitometer according to the present invention. 1. Evaporator 2. ... Distillate collection section 3.・
...On-off valve 4, ...On-off valve 5. ...Drainage piping 6
．． ...Opening/closing valve 7,...7 piston cylinder 8.・・・
・On-off valve, 9. ...Flow path switch IQ, ...Wave path switch 11, ...Detector 1z...Bypass flow path 13, ...Sample quantitative collection mechanism 14. ...Sample circulation piping 15, ...Pure water quantitative sampling mechanism 16. ...
Pure water storage tank 17,... Circulation piping 1 &... Open/close valve
19. ...Compressed air agent Patent attorney Nori Chika
Yu (1 other person)

Claims (2)

[Claims] (1) In a concentration meter that determines the concentration of components in a sample by measuring the conductivity of a liquid sample, an evaporator having a cleaning mechanism, a distillate collection unit having a pure water metering mechanism and a cleaning mechanism, A quantitative sample collection mechanism, and conductivity measurement in which the sample collected by the quantitative sample collection mechanism is heated in the evaporator to collect distilled components, and then a collection liquid is introduced to measure the conductivity. A densitometer characterized by comprising a cell. (2) The concentration meter according to claim 1, wherein the evaporator has a temperature detection mechanism for controlling the temperature of the evaporator.