High-temperature strong-alkali liquid material pH online monitoring control system

Abstract

The utility model relates to a high-temperature strong-alkali liquid material pH on-line monitoring control system which comprises a sample guiding pipeline, the sample guiding pipeline is connected with a top tube pass feeding port of an immersion type heat exchanger, a tube pass bottom discharging port of the immersion type heat exchanger is connected with a lower portion feeding port of a measuring cylinder, and the heat exchanger is cooled through low-temperature water circulation. A discharge hole in the upper part of the measuring cylinder is connected with a sample return pipe which is connected to the middle lower part of the stripping tower. In the industry, the problems that the service life of a pH probe is too short and the pH analysis value is too low and distorted generally exist in the online pH monitoring and analysis process of high-temperature and strong-alkali materials. After the monitoring system is put into use, the online pH analysis precision can be improved, the service life of the pH probe is effectively prolonged, and the liquid caustic soda addition amount of the system is accurately controlled.

Description

Technical Field

[0001] The utility model belongs to the field of online analytical instruments for chemical production, and is particularly suitable for an online pH monitoring and control system for high-temperature strong alkali liquid materials. Background Art

[0002] In order to stably monitor and control the pH of production materials during production operations, chemical companies widely install and apply online pH meters in various chemical production devices. However, strong alkaline materials C (H + )=Kw / C(OH - ), due to the increase in temperature, the Kw value increases, C(OH - ) remains unchanged, so C(H + ) increases, the pH value decreases, and the pH meter's built-in temperature compensation calculation accuracy is not enough, resulting in a large gap between the online measured pH value and the actual analyzed pH value. At the same time, in a high temperature and strong alkaline environment, the pH meter electrode membrane will age and be damaged, shortening the service life of the electrode; the electrode's response speed will slow down, affecting the real-time measurement; at the same time, it will affect the electrode's potential, resulting in increased measurement errors; extreme high temperature and strong alkaline conditions can even directly damage the pH meter's circuits and electronic components, causing instrument failure. Summary of the invention

[0003] In view of the problems existing in the online monitoring of the pH value of high-temperature strong alkaline liquid materials in the above-mentioned chemical industry production, the utility model provides an online monitoring and control system for the pH value of high-temperature strong alkaline liquid materials, and its technical solution is as follows: it includes a sample introduction pipeline, the sample introduction pipeline is connected to the feed port of the top tube side of the immersed heat exchanger, the bottom discharge port of the tube side of the immersed heat exchanger is connected to the lower feed port of the measuring cylinder, and the heat exchanger is used, the upper discharge port of the measuring cylinder is connected to the sample return pipe, and the sample return pipe is connected to the middle and lower part of the stripping tower.

[0004] The material inlet pipeline of the immersed heat exchanger is provided with a needle valve, and a gate valve is provided at the connection between the return sample pipeline and the stripping tower, so as to facilitate the maintenance and calibration of the pH online analysis system.

[0005] The immersed heat exchanger adopts 10°C low-temperature water circulation to cool down and transfer heat.

[0006] A low-temperature water recovery stop valve is arranged at the low-temperature water return pipe connected to the upper part of the shell side of the heat exchanger.

[0007] A low-temperature water inlet stop valve is arranged at the low-temperature water inlet pipe connected to the lower part of the shell side of the heat exchanger.

[0008] The temperature of the material entering the measuring cylinder is controlled at about 30°C by adjusting the opening of the stop valve.

[0009] The effect of the utility model is that the temperature is reduced by heat transfer, and after the material temperature is stably lowered, the pH is monitored online, so the analysis accuracy is significantly improved, and at the same time, the service life of the pH probe is effectively extended, the amount of liquid alkali added to the system is accurately controlled, and the process control of the device system is stabilized. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a schematic diagram of the overall structure of the utility model.

[0011] In the figure: 1. Sample introduction pipeline; 2. Immersed heat exchanger; 3. Heat exchanger and measuring tube connecting pipe; 4. Thermometer; 5. Measuring tube; 6. Sample return pipe; 7. Low-temperature water inlet pipe; 8. Low-temperature water return pipe; 9. Stripping tower; 10. Low-temperature water inlet stop valve; 11. Low-temperature water recovery stop valve; 12. Feed needle valve; 13. pH meter. DETAILED DESCRIPTION

[0012] The utility model is further described in detail below based on the drawings and embodiments.

[0013] Example 1

[0014] A pH online monitoring and control system for high-temperature strong alkaline liquid materials, wherein a sample introduction pipeline 1 is connected to the top tube side of a heat exchanger 2, a low-temperature water inlet pipeline 7 is arranged at the lower part of the shell side of the heat exchanger 2, 10°C low-temperature desalted water is used for heat transfer and cooling, a low-temperature water return pipeline 8 is arranged at the upper part of the shell side of the heat exchanger 2, the bottom of the tube side of the heat exchanger 2 is connected to the lower feed port of a measuring cylinder 5 through a pipeline 3, the upper discharge port of the measuring cylinder 5 is connected to a sample return pipe 6, and the sample return pipe 6 is connected to the lower middle part of a stripping tower 9.

[0015] The measuring tube 5 is sealed and connected to the probe of the pH meter 13 through a flange to continuously perform pH analysis on the sampled material. The analysis value signal is transmitted to the DCS control system through the pH meter 13 transmitter, and the opening of the liquid alkali flow regulating valve is automatically adjusted to control the amount of alkali added to achieve the purpose of adjusting the pH.

[0016] A needle valve 12 is provided at the connection between the sample introduction pipeline 1 and the top pipe of the heat exchanger 2 .

[0017] A low-temperature water recovery stop valve 11 is provided at the low-temperature water return pipe 8 connected to the upper part of the shell side of the heat exchanger 2.

[0018] A low-temperature water inlet stop valve 10 is provided at a low-temperature water inlet pipe 7 connected to the lower part of the shell side of the heat exchanger 2.

[0019] A field thermometer 4 is provided on a pipe 3 connecting the bottom of the tube of the heat exchanger 2 and the lower feed port of the measuring cylinder 5.

[0020] Example 2

[0021] The system described in Example 1 is used, and its operation process is as follows:

[0022] The material to be analyzed online is diverted through the sample tube 1 and led to the immersed heat exchanger 2 for heat exchange and cooling to about 30°C, and then flows into the measuring tube 5 for pH analysis. After the analysis is completed, the material enters the stripping tower 9 through the return sample tube 6 for recycling.

[0023] The temperature control of the analyzed material can be adjusted by controlling the flow rate of the sample material and the flow rate of the low-temperature water through the opening of the needle valve 12, the low-temperature water inlet stop valve 10, and the low-temperature water recovery stop valve 11.

[0024] When the chemical plant system is shut down or the pH analysis control system is overhauled and maintained, the needle valve 12 and the stop valve 14 should be closed to cut out the pH analysis control system.

Claims

1. A high-temperature strong alkaline liquid material pH online monitoring and control system, characterized in that: The sample introduction pipeline (1) is connected to the top tube side of the heat exchanger (2), a low-temperature water inlet pipeline (7) is arranged at the lower part of the shell side of the heat exchanger (2), a low-temperature water return pipeline (8) is arranged at the upper part of the shell side of the heat exchanger (2), the bottom of the tube side of the heat exchanger (2) is connected to the lower feed port of the measuring cylinder (5) through the pipeline (3), the upper discharge port of the measuring cylinder (5) is connected to the sample return pipe (6), and the sample return pipe (6) is connected to the lower middle part of the stripping tower (9).

2. The high-temperature strong alkaline liquid material pH online monitoring and control system according to claim 1 is characterized in that: The measuring cylinder (5) is sealed and connected with the probe of the pH meter (13) through a flange, and the analyzed numerical signal is transmitted to the DCS control system through the transmitter of the pH meter (13), so as to realize automatic adjustment of the opening of the liquid alkali flow regulating valve to control the amount of alkali added.

3. The high-temperature strong alkaline liquid material pH online monitoring and control system according to claim 1 is characterized in that: A needle valve (12) is provided at the connection between the sample introduction pipeline (1) and the top pipe of the heat exchanger (2).

4. The high-temperature strong alkaline liquid material pH online monitoring and control system according to claim 1 is characterized in that: A low-temperature water recovery stop valve (11) is provided at the low-temperature water return pipe (8) connected to the upper part of the shell side of the heat exchanger (2).

5. The high-temperature strong alkaline liquid material pH online monitoring and control system according to claim 1 is characterized in that: A low-temperature water inlet stop valve (10) is provided at a low-temperature water inlet pipe (7) connected to the lower part of the shell side of the heat exchanger (2).

6. The high-temperature strong alkaline liquid material pH online monitoring and control system according to claim 1 is characterized in that: The bottom of the tube side of the heat exchanger (2) is connected to the lower feed port of the measuring cylinder (5) through a pipeline (3), and a field thermometer (4) is arranged on the pipeline (3).

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