Ammonia water absorption refrigeration system with ammonia water concentration real-time monitoring function

Abstract

The utility model discloses an ammonia water absorption type refrigerating system with an ammonia water concentration real-time monitoring function, which adopts an on-line ammonia water concentration detection system constructed by matching a high-precision conductivity sensor with a PLC (Programmable Logic Controller) control system, and breaks through the technical bottleneck of traditional manual sampling detection or off-line detection with strong hysteresis. The concentration detection error can be controlled within an extremely small range, the problems of low precision, slow response and the like of a traditional detection method are effectively solved, and dynamic and accurate monitoring of the ammonia water concentration is realized. The PLC control system can dynamically adjust the heating power of the generator, the flow of the solution pump, the reflux ratio of the rectifying tower and other parameters based on concentration data, so that the ammonia water solution is always at the optimal concentration, the energy loss caused by concentration imbalance of the system is effectively reduced, meanwhile, the crystallization and corrosion risks caused by abnormal concentration of equipment are reduced, and the service life of the equipment is prolonged.

Description

Technical Field

[0001] This utility model relates to the field of ammonia absorption refrigeration systems, specifically to an ammonia absorption refrigeration system with real-time ammonia concentration monitoring function. Background Technology

[0002] Absorption refrigeration systems are devices that achieve refrigeration by converting heat through the absorption and evaporation of a solution, and they occupy an important position in industrial and civil refrigeration fields. Ammonia water, as the core working fluid in absorption refrigeration systems, is widely used in small and medium-sized refrigeration units due to its high absorption efficiency and good thermophysical properties. The concentration of ammonia water is a key parameter affecting the system's refrigeration performance and operating efficiency; its accuracy directly relates to whether the system can achieve stable and efficient operation.

[0003] Currently, mainstream ammonia concentration detection technologies on the market, such as gravity methods, chemical titration methods, and conductivity methods, have revealed many limitations in practical applications. These traditional detection methods generally suffer from complex operating procedures, slow response speeds, and susceptibility to environmental interference, making it difficult to meet the requirements of modern refrigeration systems for detection accuracy and real-time performance. Utility Model Content

[0004] To address the aforementioned problems, the purpose of this invention is to provide an ammonia absorption refrigeration system with real-time ammonia concentration monitoring. This ammonia absorption refrigeration system has a real-time ammonia concentration detection device, which can detect the concentration of ammonia solution in the system in real time and accurately, thereby providing a basis for system operation control and better improving system operating efficiency and stability.

[0005] This utility model discloses an ammonia absorption refrigeration system with real-time ammonia concentration monitoring function, comprising: a generator, a distillation column, a condenser, a subcooler, an expansion valve, an evaporator, an absorber, and a heat exchanger. The generator is located at the bottom of the distillation column, and the top outlet of the distillation column is connected to the condenser. The condenser, the subcooler, the expansion valve, the evaporator, the absorber, the cold side of the heat exchanger, and the distillation column are sequentially connected. The outlet of the generator is connected to the hot side inlet of the heat exchanger, and the hot side outlet of the heat exchanger is connected to the absorber. The ammonia absorption refrigeration system further includes: a first conductivity sensor. The system comprises: a first conductivity sensor, a second conductivity sensor, and a third conductivity sensor; a third conductivity sensor, the first conductivity sensor, the second conductivity sensor, and the third conductivity sensor; and a PLC control system, wherein the first conductivity sensor, the second conductivity sensor, and the third conductivity sensor are connected to the PLC control system to transmit conductivity detection signals to the PLC control system.

[0006] Optionally, the ammonia absorption refrigeration system further includes a solution pump located between the absorber and the heat exchanger to drive the working fluid to flow to the heat exchanger, and the probe of the first conductivity sensor extends into a first pipeline connecting the solution pump and the heat exchanger.

[0007] Optionally, the first end of the first pipeline is connected to the outlet of the solution pump, the second end of the first pipeline is connected to the cold side inlet of the heat exchanger, and the probe of the first conductivity sensor is disposed near the first end of the first pipeline.

[0008] Optionally, the ammonia absorption refrigeration system further includes a second pipeline, the first end of which is connected to the outlet of the generator and the first end of which is connected to the hot side inlet of the heat exchanger. The probe of the second conductivity sensor extends into the second pipeline and is positioned near the first end of the second pipeline.

[0009] Optionally, the ammonia absorption refrigeration system further includes a third pipeline, the first end of which is connected to the outlet of the distillation column, the second end of which is connected to the inlet of the condenser, and the probe of the third conductivity sensor extends into the third pipeline and is positioned near the first end of the third pipeline.

[0010] Optionally, the first conductivity sensor, the second conductivity sensor, and the third conductivity sensor are all installed on the corresponding pipeline by welding; the output signals of the first conductivity sensor, the second conductivity sensor, and the third conductivity sensor are 4-20mA current signals; and / or, the first conductivity sensor, the second conductivity sensor, and the third conductivity sensor are all corrosion-resistant conductivity sensors.

[0011] Optionally, the solution pump has a flow control valve for controlling the flow rate, the PLC control system is signal-connected to the control unit of the ammonia absorption refrigeration system, and the control unit is signal-connected to the flow control valve to adjust the flow rate of the solution pump.

[0012] Optionally, the generator has a power adjustment switch for adjusting the heating power, the PLC control system is signal-connected to the control unit of the ammonia absorption refrigeration system, and the control unit is signal-connected to the power adjustment switch to adjust the heating power of the generator.

[0013] Optionally, the absorber has a cooling water switch for adjusting the cooling water volume, the PLC control system is signal-connected to the control unit of the ammonia absorption refrigeration system, and the control unit is signal-connected to the cooling water switch to adjust the cooling water volume of the absorber.

[0014] Optionally, the distillation column has a reflux regulating switch for adjusting the reflux ratio, the PLC control system is signal-connected to the control unit of the ammonia absorption refrigeration system, and the control unit is signal-connected to the reflux regulating switch to adjust the reflux ratio of the distillation column.

[0015] The ammonia absorption refrigeration system provided in this embodiment features real-time ammonia concentration monitoring. It employs an online ammonia concentration detection system built with a high-precision conductivity sensor and a PLC control system. This overcomes the bottlenecks of traditional manual sampling or offline detection technologies with significant lag, minimizing concentration detection errors and effectively solving problems such as low accuracy and slow response in traditional methods. This enables dynamic and accurate monitoring of ammonia concentration. Based on concentration data, the PLC control system dynamically adjusts parameters such as generator heating power, solution pump flow rate, and distillation column reflux ratio to maintain the optimal ammonia solution concentration. This effectively reduces energy loss due to concentration imbalance and lowers the risk of crystallization and corrosion caused by abnormal concentration, extending equipment lifespan. Furthermore, the system's ability to automatically adapt to changing operating conditions reduces the frequency of manual intervention and lowers maintenance costs, ensuring efficient and long-term operation of the ammonia absorption refrigeration system. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of an ammonia absorption refrigeration system with real-time ammonia concentration monitoring function according to an embodiment of this utility model.

[0017] Figure label:

[0018] Generator 1, Distillation Column 2, Condenser 3, Subcooler 4, Expansion Valve 5, Evaporator 6, Fan Coil Unit 7, Absorber 8, Solution Pump 9, Heat Exchanger 10, First Conductivity Sensor 11, Second Conductivity Sensor 12, Third Conductivity Sensor 13, Chilled Water Pump 14, PLC Control System 15 Detailed Implementation

[0019] The embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0020] The following is based on Figure 1 This invention describes an ammonia absorption refrigeration system with real-time ammonia concentration monitoring function.

[0021] like Figure 1 As shown, the ammonia absorption refrigeration system with real-time ammonia concentration monitoring function includes a generator 1, a distillation column 2, a condenser 3, a subcooler 4, an expansion valve 5, an evaporator 6, an absorber 8, and a heat exchanger 10.

[0022] The generator 1 is located at the bottom of the distillation column 2, and the top outlet of the distillation column 2 is connected to the condenser 3. The condenser 3, subcooler 4, expansion valve 5, evaporator 6, absorber 8, cold side of heat exchanger 10, and distillation column 2 are connected in sequence. The outlet of the generator 1 is connected to the hot side inlet of the heat exchanger 10, and the hot side outlet of the heat exchanger 10 is connected to the absorber 8.

[0023] The ammonia absorption refrigeration system also includes: a first conductivity sensor 11, a second conductivity sensor 12, a third conductivity sensor 13, and a PLC control system 15.

[0024] The detection point of the first conductivity sensor 11 is located on the pipeline at the outlet side of the absorber 8, and is used to detect the outlet conductivity of the absorber 8 in real time. The detection point of the second conductivity sensor 12 is located on the pipeline at the outlet side of the generator 1, and is used to detect the outlet conductivity of the generator 1 in real time. The detection point of the third conductivity sensor 13 is located on the pipeline at the outlet side of the distillation column 2, and is used to monitor the outlet conductivity of the distillation column 2 in real time.

[0025] The first conductivity sensor 11, the second conductivity sensor 12, and the third conductivity sensor 13 are connected to the PLC control system 15 to transmit the conductivity detection signal to the PLC control system 15.

[0026] When an ammonia absorption refrigeration system is in operation, it uses an ammonia solution as the working fluid and achieves refrigeration through heat exchange and changes in solution concentration.

[0027] After the system starts, the ammonia solution at the bottom of generator 1 is heated by a heat source. Since the boiling point of ammonia is lower than that of water, the ammonia in the ammonia solution quickly evaporates into high-temperature, high-pressure ammonia gas. The ammonia solution with reduced concentration flows out from the outlet of generator 1 and enters the hot side inlet of heat exchanger 10. In heat exchanger 10, the high-temperature dilute ammonia solution transfers heat to the cold side solution. After its own temperature decreases, it flows into absorber 8.

[0028] The high-temperature, high-pressure ammonia gas generated in generator 1 rises to distillation column 2, where it undergoes distillation and purification to further separate residual moisture, resulting in a higher purity ammonia gas exiting from the top outlet of column 2. The high-purity ammonia gas then enters condenser 3, where it releases heat to a cooling medium (such as water or air), condensing into liquid ammonia. This liquid ammonia then flows into subcooler 4, where it is further cooled to become subcooled liquid ammonia.

[0029] When subcooled liquid ammonia passes through expansion valve 5, its pressure drops instantaneously, causing throttling and expansion, transforming it into a low-temperature, low-pressure gas-liquid two-phase mixture, which then enters evaporator 6. In evaporator 6, the low-temperature, low-pressure ammonia absorbs heat from the surrounding medium (such as air or water), rapidly evaporating into ammonia gas, thus achieving a cooling effect. The resulting low-temperature refrigerant is transported through connecting pipes to terminal equipment such as fan coil units 7, providing cooling to users. The ammonia gas exiting evaporator 6 enters absorber 8, where it is absorbed by a dilute ammonia solution flowing from heat exchanger 10, reforming into a concentrated ammonia solution. The heat released during absorption is carried away by the cooling medium. The entire process continuously circulates, providing a sustained cooling function.

[0030] Meanwhile, the first conductivity sensor 11, the second conductivity sensor 12, and the third conductivity sensor 13 in the system monitor the outlet conductivity of the absorber 8, the outlet conductivity of the generator 1, and the outlet conductivity of the distillation column 2 in real time, respectively, and transmit the conductivity detection signals to the PLC control system 15, so that the PLC control system 14 can calculate the ammonia solution concentration at each detection point according to the preset conductivity-concentration function relationship.

[0031] If the concentration deviates from the set value, the PLC control system 15 can adjust the concentration of the ammonia solution by adjusting parameters such as the flow rate of the solution pump 9, the heating power of the generator 1, the cooling water volume of the absorber 8, or the reflux ratio of the distillation column 2, so as to ensure the efficient and stable operation of the system.

[0032] The ammonia absorption refrigeration system provided in this embodiment of the invention has a real-time ammonia concentration monitoring function. It adopts an online ammonia concentration detection system constructed with a high-precision conductivity sensor and a PLC control system, which breaks through the bottleneck of traditional manual sampling detection or offline detection technology with strong lag. It can control the concentration detection error within a very small range, and improve the detection accuracy by more than 30% compared with traditional methods. It effectively solves the problems of low accuracy and slow response of traditional detection methods, and realizes dynamic and accurate monitoring of ammonia concentration.

[0033] Based on concentration data, the PLC control system can dynamically adjust parameters such as generator heating power, solution pump flow rate, and distillation column reflux ratio to maintain the ammonia solution at its optimal concentration. This effectively reduces energy loss caused by concentration imbalances and lowers the risk of crystallization and corrosion due to abnormal concentrations, extending equipment lifespan. Furthermore, the system's ability to automatically adapt to changing operating conditions reduces the frequency of manual intervention, lowers maintenance costs, and ensures the efficient and long-term operation of the ammonia absorption refrigeration system.

[0034] In some embodiments, the subcooler 4 has two independent heat exchange channels, one hot and one cold. Figure 1 For example, the outlet of condenser 3 is connected to the cold side inlet of subcooler 4, the cold side outlet of subcooler 4 is connected to expansion valve 5, the outlet of evaporator 6 is connected to the hot side inlet of subcooler 4, and the hot side outlet of subcooler 4 is connected to absorber 8.

[0035] The high-temperature liquid ammonia flowing from condenser 3 is piped into the cold-side inlet of subcooler 4. Within the cold-side channel, the liquid ammonia exchanges heat with the hot-side fluid. Because the hot-side fluid carries the low-temperature energy of the ammonia gas exiting evaporator 6, the high-temperature liquid ammonia on the cold side continuously releases heat during its flow, further reducing its temperature and forming subcooled liquid ammonia. After releasing its heat, the subcooled liquid ammonia flows out from the cold-side outlet of subcooler 4 and is connected to expansion valve 5 via a pipe to continue the subsequent refrigeration cycle.

[0036] The low-temperature, low-pressure ammonia gas discharged from evaporator 6 serves as the heat exchange medium on the hot side of subcooler 4, flowing into the heat exchange channel from the hot-side inlet. Inside the hot-side channel, the low-temperature ammonia gas absorbs the heat released by the high-temperature liquid ammonia on the cold side, raising its own temperature and forming ammonia gas with a certain degree of superheat. This process not only avoids the problem of poor absorption efficiency due to excessively low temperature when the ammonia gas enters absorber 8, but also effectively utilizes the waste heat within the system, achieving efficient energy recovery. The heated ammonia gas flows out from the hot-side outlet of subcooler 4 and finally enters absorber 8, where it is absorbed by the dilute ammonia solution.

[0037] like Figure 1 As shown, the ammonia absorption refrigeration system also includes a refrigeration loop for cold energy transfer and terminal cooling. This loop is equipped with a chilled water pump 14, which drives the circulation of the circulating medium (usually water) within the loop. The refrigeration loop connects the evaporator 6 and the fan coil unit 7 (terminal heat exchange equipment). The low-temperature, low-pressure ammonia solution absorbs heat and evaporates in the evaporator 6, cooling the circulating medium flowing through the evaporator heat exchange tubes. The cooled, low-temperature circulating water flows through the refrigeration loop to the fan coil unit 7, where it exchanges heat with the indoor air. The heated circulating water then returns to the inlet of the evaporator 6, forming a continuous refrigeration cycle.

[0038] Preferably, the first conductivity sensor 11, the second conductivity sensor 12, and the third conductivity sensor 13 are all high-precision conductivity sensors, characterized by fast response and high stability, and can provide accurate conductivity data in a short time.

[0039] Optionally, the first conductivity sensor 11, the second conductivity sensor 12, and the third conductivity sensor 13 are all installed on the corresponding pipelines by welding. For example, sufficient space is cut at the sampling location, and the sensors are directly welded to the pipelines at both ends.

[0040] Preferably, the probes of the first conductivity sensor 11, the second conductivity sensor 12, and the third conductivity sensor 13 should be positioned to avoid dead corners and turbulent areas to ensure the standardization of the sample solution.

[0041] Optionally, the output signals of the first conductivity sensor 11, the second conductivity sensor 12, and the third conductivity sensor 13 are 4-20mA current signals, and the conductivity of the solution can be directly calculated based on the upper and lower limits of the range.

[0042] Preferably, the first conductivity sensor 11, the second conductivity sensor 12, and the third conductivity sensor 13 are all corrosion-resistant conductivity sensors that can resist corrosion from ammonia solution during long-term use.

[0043] In some specific embodiments, with Figure 1For example, the ammonia absorption refrigeration system also includes a solution pump 9, which is located between the absorber 8 and the heat exchanger 10 to drive the working fluid to flow to the heat exchanger 10. The probe of the first conductivity sensor 11 extends into the first pipeline connecting the solution pump 9 and the heat exchanger 10.

[0044] Specifically, the first end of the first pipeline is connected to the outlet of the solution pump 9, the second end of the first pipeline 9 is connected to the cold side inlet of the heat exchanger 10, and the probe of the first conductivity sensor 11 is set near the first end of the first pipeline 9, that is, near the outlet of the solution pump 9. This can avoid the influence of turbulence and make the detection results more accurate.

[0045] In other embodiments, the detection site of the first conductivity sensor 11 may be located between the bottom outlet of the absorber 8 and the inlet of the solution pump 9.

[0046] In some specific embodiments, with Figure 1 For example, the ammonia absorption refrigeration system also includes a second pipeline. The first end of the second pipeline is connected to the outlet of the generator 1 and the first end of the second pipeline is connected to the hot side inlet of the heat exchanger 10. The probe of the second conductivity sensor 12 extends into the second pipeline and is set near the first end of the second pipeline, that is, near the outlet of the generator 1. This can avoid the influence of turbulence and make the detection results more accurate.

[0047] In some specific embodiments, with Figure 1 For example, the ammonia absorption refrigeration system also includes a third pipeline. The first end of the third pipeline is connected to the outlet of the distillation column 2, and the second end of the third pipeline is connected to the inlet of the condenser 3. The probe of the third conductivity sensor 13 extends into the third pipeline and is set near the first end of the third pipeline, that is, near the outlet of the distillation column 2. This can avoid the influence of turbulence and make the detection results more accurate.

[0048] After the first conductivity sensor 11, the second conductivity sensor 12, and the third conductivity sensor 13 transmit the conductivity detection signals to the PLC control system 15, the PLC control system 15 can obtain the solution concentration based on the functional relationship between the concentration and conductivity of the ammonia solution within the range obtained through experimental testing. The PLC control system 15 can feed back the obtained ammonia concentration value to the control unit of the refrigeration system. The control unit adjusts the system operation according to the obtained ammonia concentration value to ensure that the system is in the optimal working state, thereby improving refrigeration efficiency and extending the service life of the equipment. The conductivity-concentration functional relationship is a curve relationship between conductivity and concentration plotted using conductivity data of ammonia solutions of different concentrations under laboratory conditions.

[0049] In some embodiments, the solution pump 9 has a flow control valve for controlling the flow rate, and the PLC control system 15 is signal-connected to the control unit of the ammonia absorption refrigeration system so as to feed back the ammonia concentration value to the control unit of the refrigeration system. The control unit is signal-connected to the flow control valve to adjust the flow rate of the solution pump 9, thereby adjusting the ammonia solution concentration.

[0050] Specifically, the control unit adjusts the flow rate of the solution pump 9 based on the outlet concentration of the absorber 8 fed back by the PLC control system 15.

[0051] In some embodiments, the generator 1 has a power adjustment switch for adjusting the heating power, and the control unit is signal-connected to the power adjustment switch to adjust the heating power of the generator 1 according to the feedback ammonia concentration, thereby adjusting the ammonia solution concentration.

[0052] Specifically, the control unit adjusts the heating power of generator 1 based on the outlet concentration of generator 1 fed back by the PLC control system 15.

[0053] In some embodiments, the absorber 8 has a cooling water switch for adjusting the cooling water volume, and the control unit is connected to the cooling water switch signal to adjust the cooling water volume of the absorber 8 according to the feedback ammonia concentration, thereby adjusting the ammonia solution concentration.

[0054] Specifically, the control unit adjusts the cooling water volume of the absorber 8 based on the outlet concentration of the absorber 8 fed back by the PLC control system 15.

[0055] In some embodiments, the distillation column 2 has a reflux regulating switch for adjusting the reflux ratio, and the control unit is connected to the reflux regulating switch signal to adjust the reflux ratio of the distillation column 2 according to the feedback ammonia concentration, thereby adjusting the ammonia solution concentration.

[0056] Specifically, the control unit adjusts the reflux ratio of distillation column 2 based on the outlet concentration of distillation column 2 fed back by the PLC control system 15.

[0057] In practical applications, the ammonia absorption refrigeration system provided by this invention can monitor ammonia concentration in real time, avoiding the errors and slow response problems existing in traditional detection methods. Through linkage with a PLC control system, the overall performance, reliability, and accuracy of the absorption refrigeration system can be improved, energy consumption reduced, and equipment lifespan extended.

[0058] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0059] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0060] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0061] In this utility model, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0062] In this utility model, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this utility model. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0063] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. An ammonia absorption refrigeration system with real-time ammonia concentration monitoring function, characterized in that, include: The system comprises a generator, a distillation column, a condenser, a subcooler, an expansion valve, an evaporator, an absorber, and a heat exchanger. The generator is located at the bottom of the distillation column, and the top outlet of the distillation column is connected to the condenser. The condenser, the subcooler, the expansion valve, the evaporator, the absorber, the cold side of the heat exchanger, and the distillation column are sequentially connected. The outlet of the generator is connected to the hot side inlet of the heat exchanger, and the hot side outlet of the heat exchanger is connected to the absorber. The ammonia absorption refrigeration system also includes: A first conductivity sensor, the detection point of the first conductivity sensor is located on the pipeline on the outlet side of the absorber, for real-time detection of the outlet conductivity of the absorber; The second conductivity sensor has its detection point located on the pipeline at the outlet side of the generator, and is used to detect the outlet conductivity of the generator in real time. A third conductivity sensor, wherein the detection point of the third conductivity sensor is located on the pipeline at the outlet side of the distillation column, is used to monitor the outlet conductivity of the distillation column in real time; and In the PLC control system, the first conductivity sensor, the second conductivity sensor, and the third conductivity sensor are signal-connected to the PLC control system so as to transmit the conductivity detection signal to the PLC control system.

2. The ammonia absorption refrigeration system according to claim 1, characterized in that, It also includes a solution pump located between the absorber and the heat exchanger for driving the working fluid to flow to the heat exchanger, and the probe of the first conductivity sensor extends into a first pipeline located between the solution pump and the heat exchanger.

3. The ammonia absorption refrigeration system according to claim 2, characterized in that, The first end of the first pipeline is connected to the outlet of the solution pump, the second end of the first pipeline is connected to the cold side inlet of the heat exchanger, and the probe of the first conductivity sensor is positioned near the first end of the first pipeline.

4. The ammonia absorption refrigeration system according to claim 1, characterized in that, It also includes a second pipeline, the first end of which is connected to the outlet of the generator and the first end of which is connected to the hot side inlet of the heat exchanger. The probe of the second conductivity sensor extends into the second pipeline and is positioned near the first end of the second pipeline.

5. The ammonia absorption refrigeration system according to claim 1, characterized in that, It also includes a third pipeline, the first end of which is connected to the outlet of the distillation column, the second end of which is connected to the inlet of the condenser, and the probe of the third conductivity sensor extends into the third pipeline and is positioned near the first end of the third pipeline.

6. The ammonia absorption refrigeration system according to claim 1, characterized in that, The first conductivity sensor, the second conductivity sensor, and the third conductivity sensor are all installed on their respective pipelines by welding. The output signals of the first conductivity sensor, the second conductivity sensor, and the third conductivity sensor are 4-20mA current signals; and / or The first conductivity sensor, the second conductivity sensor, and the third conductivity sensor are all corrosion-resistant conductivity sensors.

7. The ammonia absorption refrigeration system according to claim 2, characterized in that, The solution pump has a flow control valve for controlling the flow rate. The PLC control system is signal-connected to the control unit of the ammonia absorption refrigeration system. The control unit is signal-connected to the flow control valve to adjust the flow rate of the solution pump.

8. The ammonia absorption refrigeration system according to claim 1, characterized in that, The generator has a power adjustment switch for adjusting the heating power. The PLC control system is signal-connected to the control unit of the ammonia absorption refrigeration system. The control unit is signal-connected to the power adjustment switch to adjust the heating power of the generator.

9. The ammonia absorption refrigeration system according to claim 1, characterized in that, The absorber has a cooling water switch for adjusting the cooling water volume. The PLC control system is signal-connected to the control unit of the ammonia absorption refrigeration system. The control unit is signal-connected to the cooling water switch to adjust the cooling water volume of the absorber.

10. The ammonia absorption refrigeration system according to claim 1, characterized in that, The distillation column has a reflux regulating switch for adjusting the reflux ratio. The PLC control system is signal-connected to the control unit of the ammonia absorption refrigeration system. The control unit is signal-connected to the reflux regulating switch to adjust the reflux ratio of the distillation column.

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