SU1718098A1 - For automatic measurement of hydrogen ion concentration - Google Patents

Abstract

The invention relates to a technique for the continuous automatic measurement of the concentration of hydrogen ions of solutions in apparatus at high temperatures and pressures, and can be applied in various parts of the industry. The aim of the invention is to expand the scope and improve accuracy. This goal is achieved by testing the solution after throttling, cooling is subjected to electrodialysis, then after measuring the hydrogen concentration using a conventional method, it is sent to a comparative cell of a differential sensor with metal oxide electrodes, where the solutions are compared with the same parameters. The readout is taken according to the pH meter, corrected for the amount of sample movement delayed at zero potential difference between the metal oxide sensor electrodes. 1 il. Yo

Description

The invention relates to a technique for the continuous automatic measurement of the hydrogen ion concentration (pH) of solutions in apparatus at high temperatures and pressures, and can be applied in various industries, such as power engineering.

Methods are known and, on their basis, a device for continuous automatic measurement of the pH of solutions in apparatus at high temperatures and pressures, which contains a series-connected first choke, a cooler, a second choke, a sensor with glass measuring and comparative electrodes, a flow meter (pump) , a sensor with metal oxide electrodes separated by a porous, for example, ceramic, partition wall; Electrodes of the sensor with glass electrode and sensor with metal oxide electrodes are connected to the input doubling the motor potentiometer.

However, this device has insufficient accuracy associated with the procedure for the summation of two independent measurements. The measurement errors of two such sensors are also summarized. In addition, an additional dynamic error is possible due to the inconsistency of the sample supply of the standardized (measured by the sensor with glass and comparative electrodes) solution in

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comparative sensor cell with metal oxide electrodes.

Closest to the proposed device for automatically measuring the pH of solutions in high pressure and high pressure apparatuses is a device consisting of a series of first drops, a cooler, a second drop, an electrodialysis cell with two electrodes separated by a porous partition, sensor.) with glass measuring and comparative electrodes, prompting the flow rate of the sample solution (pump) and sensor with metal oxide electrodes separated by a porous partition. Moreover, the sensor electrodes with glass and comparative electrodes are connected via a high-resistance transducer to an electronic automatic potentiometer (secondary device), and the sensor electrodes with metal oxide electrodes control the process of electrodialysis of a sample of a solution in an electrodialysis cell through a zero-indicator and control unit.

However, the known device has insufficient accuracy due to dynamic errors due to inconsistencies in the supply of the standardized sample solution to the cell comparing the sensor with metal oxide electrodes.

The purpose of the invention is to expand the scope and increase the accuracy of measurement.

This goal is achieved by the fact that the device additionally includes an adjustable time lag unit, a control unit for the start of operation of the secondary device, a converter unit and a counter. sample feed, solution. Moreover, the latter is connected via a converter unit and an adjustable delay unit to a secondary device, which is connected from the starting unit of the secondary device, connected to a null-indicator device.

The drawing shows a block diagram of the proposed device.

The device contains an apparatus 1 with a high-temperature coolant or solution for technological purposes, throttling devices 2, a refrigerator 3, an electrodialysis cell 4, divided by a porous partition 5 into two spaces. electrodes b, sensor 7 with glass measuring and comparative electrodes, the outputs of the latter are connected to the yen with the input of a high-resistance converter 8, which, through the &

an adjustable lag is associated with a secondary device 10, for example, an electronic automatic potentiometer. Sensor with metal oxide electrodes 11

It contains two metal oxide electrodes 12, one of which is directly in the measuring solution, and the other is connected to the measuring solution through a porous, for example, ceramic, septum 13.

The electrodes 12 of the sensor with metal oxide electrodes 11 are connected to a zero-indicator device 14. The latter controls the electrodialysis cell in an electrodialysis cell 4 by means of the regulator 15. The booster flow rate cooled and standardized (measured by the sensor 7) sample solution, for example plunger pump 16, is equipped rev counter,

0 registering the supply of the amount of liquid (the sample sample supplying counter 17), the latter, through the converter-control unit 18, controls the operation of the adjustable delay unit 9. The system has a switch-on unit 19 for switching on the secondary device 10 from the zero-indicator device 4.

The device works as follows.

0 A sample of the solution from the apparatus 1 passes sequentially through the first choke 2, the cooler 3, the second choke 2, and the parameters of the solution (temperature and pressure) are reduced to the limits sufficient for

normal operation of the electrodialysis cell 4 and a sensor with a glass measuring and comparative electrodes 7. Next, the sample enters the electrodialysis cell 4, on the electrodes 6 of which by

0 a current regulator 15 applies a potential difference, the polarity and the value of which depends on the polarity and the value of the potential difference between the metal oxide electrodes 12 in the differential

5 high-temperature sensor with metal oxide electrodes 11, fixed by a zero-indicator device. The purpose of the subsystem consisting of a high-temperature metal oxide sensor 11

0 by electrodes 12, a zero-indicator device 14 and a regulator 15, such that by electrodialysis in one of the spaces of electrodialysis 4, acidification or alkalinization of a solution of the solution, i.e.

5, to bring the pH value of the sample to the pH of the solution in the apparatus, which is recorded on the zero-indicator device 14 with zero potential difference.

If the space in the electrodialysis jse 4 is connected to the sensor 7. is

As a result of the regulation of the cathode regulator 15, then on the electrode 6 in the given space (left in the figure relative to the partition 5) the reaction of the electron transfer to the hydrogen ions will occur

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and the pH of the solution will increase.

If this space is anodic, then the electrode 6 will react

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and the pH of the solution will decrease.

In this situation, two cases are possible. Firstly, the accuracy of this subsystem is such that in all time ranges of the subsystem's operation, the value of zero potential between the electrodes 12 is maintained with deviations not exceeding the allowable ones. In this case, the pH value recorded by sensor 7 with glass measuring and comparative electrodes with a high-resistance converter 8 and, subsequently, on the secondary device 10, will correspond to the true pH value in the apparatus. Secondly, the control subsystem does not support the potential difference across the electrodes 12 with the required accuracy. Sensor 11 with metal oxide electrodes 12 due to large delays in the subsystem: electrodialyzer 4, sensor 7, pump 16, high-temperature sensor 11, usually outputs a potential difference that fluctuates relative to zero, But only at zero potential difference will the pH value of the solution in the apparatus coincide with that given same conditions for temperature and pressure of the solution breakdown. The purpose of block 19 is to turn on the device 10 (or only its indicator and recording devices) only when the potential difference on the zero-indicator device 14 is zero (with some error). The device 10 records the pH value with a lag of time

,

where L is the length of the delay line of the transmitter 7 to the metal oxide electrode 11;

V is the rate of movement of the solution along the delay line),

those. That which the sensor 7, together with the converter 8, has already registered and has been recorded in the memory of the clean delay unit 9. The delayed reading time in block 9 is set by the regulator block 18 on the basis of measurements, for example, of the speed of operation of the plunger pump 16 5 by the sensor 17, (It is also possible to install the sensor 17 of the flow velocity directly into the sample stream).

Thus in the device by the joint operation of the block 19, including

0 the secondary indicating and recording device 10 only for the period of time of the zero value of the potential difference outputted by the sensor 11, and the operation of the measurement solution flow rate sensor co5, together with the conversion control unit 18, determine the value of the delay value in block 9 with the output of the pH values 10. Apply recording the pH values given by block 8 to

0 block 9, for example, on a magnetic drum or magnetic tape of a closed circuit, the rotation of which by block 18 is synchronized with the operation of pump 16, and the distance between the recording and

5, the read head is set proportionally to the length of the delay line of the transmitter 7 before the sample solution enters the comparative cell of sensor 11. The signal on the magnetic drum or magnetic tape of a closed circuit can be recorded in digital form, previously converted using an analog-digital converter. After the read head must be installed

5 erasing head to clear the field for a new entry.

The technical and economic efficiency of the proposed device in comparison with the known one consists in expanding the device's ability to extend control to solutions with a small buffer capacity, for example, desalinated water, which is often used as a heat carrier in power units.

Claims (1)

5 Formula izob. eteny A device for automatically measuring the concentration of hydrogen ions, containing successively included first choke, cooler, second 0 choke, electrodynamic cell containing electrodes separated by a porous membrane, a sensor with a glass indicator and comparative electrodes, a solution sample flow booster and a sensor 5 with metal oxide electrodes separated by a porous partition, the sensor electrodes with glass and comparative electrodes being connected via a converter to the secondary device, and the sensor electrodes with metal oxide electrodes are connected to the input: a zero-indicator device, the output of which is connected to the input of the regulating unit, the output of the latter is connected to the electrodialysis cell electrodes, characterized in that, in order to expand the field of application and increase the accuracy of measurement, the device additionally contains an adjustable delay unit start control block operation of the secondary device, the converter-regulating unit and the sample delivery counter of the solution, the counter of supplying the sample solution through the converter-regulating unit and the adjustable delay unit connected to the secondary device, which is connected from the starting device of the secondary device connected to the zero-indicator device. Ј9-n