Multi-point constant-temperature calibration device and method for calibrating hydrogeological temperature sensor

Abstract

The invention discloses a multi-point constant-temperature calibration device and method for calibrating a hydrogeological temperature sensor, belongs to the technical field of ocean equipment and is used for calibrating the temperature sensor, the calibration device comprises a main tank, an auxiliary tank, a coolant liquid supplementing tank, a cooling-water machine, a seawater tank and a water purifier, a water outlet pipe of the main tank is connected with the water inlet end of the cooling-water machine and a drainage pump, and a water outlet pipe of the auxiliary tank is connected with a water outlet pipe of the seawater tank; the water outlet end of the water cooler and the water outlet end of the seawater tank are connected with a water inlet pipe; the water inlet end of the water purifier is connected with a platinum resistor insertion hole. When in use, the large heater is started for heating, after the temperature is approximately reached, the large heater stops working, the small heater keeps the temperature fluctuation within the stable time of the temperature measuring bridge to be less than or equal to 0.0005 DEG C, the working reference platinum resistance thermometer is used for measuring the temperature, and the measured data of the CTD temperature sensor is recorded; a temperature sensor to be calibrated is placed in the working area, and an A DEG C temperature point experiment is completed.

Description

Technical Field

[0001] The invention discloses a multi-point constant temperature calibration device and method for calibrating a hydrogeological temperature sensor, belonging to the technical field of marine equipment. Background Art

[0002] Effective temperature calibration is the key to improving the current actual temperature measurement accuracy. In order to further improve the accuracy of ocean temperature measurement, the development of effective and reliable ocean temperature calibration technology is the international trend to improve the level of temperature measurement. The metrological calibration of ocean temperature sensors can be achieved through the comparison method. By developing high-stability and high-uniformity seawater constant temperature equipment, standard points can be freely selected to meet certain calibration level requirements. The short-term stability of existing constant temperature baths in China within the ocean temperature range is usually only 2mK to 5mK at most, which brings great measurement errors to the calibration of temperature sensors and cannot meet the high-level metrology requirements of ocean temperature. Therefore, it is necessary to develop a new type of high-stability precision constant temperature bath to provide technical support for solving the long-term drift problem of ocean temperature sensors.

[0003] Some of the thermostatic baths in the prior art use magnetic coupling stirring technology. The advantage of this technology is to ensure the spatial uniformity of the temperature field, but the disadvantage is that the temperature control cycle is too long. Another part of the thermostatic baths uses a bottom speed-regulated jet stirring method and a submersible pump direct stirring method. The bottom speed-regulated jet stirring method easily forms a dead zone due to the jet angle problem, the water body is not fully stirred, and the temperature field uniformity is too poor. The submersible pump stirs the water body too violently and has a large thermal effect, which has a relatively large impact on the temperature control. Summary of the invention

[0004] The present invention provides a multi-point constant temperature calibration device and method for calibrating a hydrogeological temperature sensor, which solves the problems of long temperature control period, inaccurate temperature control and easy formation of dead zone in bottom speed-regulated jet stirring of the constant temperature bath used in the multi-point calibration device in the prior art.

[0005] A multi-point constant temperature calibration device for calibrating a hydrogeological temperature sensor, comprising a main tank, an auxiliary tank, a coolant replenishing tank, a chiller, a seawater tank and a pure water machine;

[0006] The main tank includes a main tank shell, a mixing zone sleeve, a mixing zone and a working zone. The mixing zone sleeve is inserted from the top of the main tank shell into the working zone. The mixing zone is arranged inside the mixing zone sleeve. A main tank stirring motor is arranged at the top of the mixing zone. The bottom of the main tank stirring motor is connected to the main tank stirring motor middle axis and two three-blade paddles in sequence downward. A reducer is arranged at the top of the main tank stirring motor middle axis. A middle axis fixing device perpendicular to the main tank stirring motor middle axis is arranged between the two three-blade paddles. A plurality of small heaters are arranged along the length direction of the main tank stirring motor middle axis. The main tank stirring motor middle axis is inserted into the mixing zone. A plurality of main tank refrigeration coils are arranged along the vertical direction of the main tank stirring motor middle axis. Two large heaters and two temperature sensors are arranged in the working zone. The large heater is arranged at the bottom of the working zone. The temperature sensor is arranged in the middle of the working zone. A thermistor protection titanium tube is arranged in the working zone and inserted from the top of the main tank downward. A thermistor is arranged in the thermistor protection titanium tube. A water outlet pipe, a water inlet pipe, a sensor connection plug and a platinum resistor insertion hole are arranged at the top of the main tank shell.

[0007] The auxiliary tank includes an auxiliary tank shell, a cold medium storage tank body and a bottom cavity, wherein the bottom cavity is arranged inside the auxiliary tank shell, the outer bottom of the cold medium storage tank body, an auxiliary tank stirring motor is arranged on the top of the cold medium storage tank body, the bottom of the auxiliary tank stirring motor is connected downward in sequence to the auxiliary tank stirring motor middle axis and a plurality of three-blade paddles, a plurality of auxiliary tank heaters are arranged along the length direction of the auxiliary tank stirring motor middle axis, the auxiliary tank stirring motor middle axis is inserted into the cold medium storage tank body, a plurality of auxiliary tank refrigeration coils are arranged along the vertical direction of the auxiliary tank stirring motor middle axis, an auxiliary tank refrigerant outlet connected to a constant flow pump is arranged on the top of the auxiliary tank shell, an auxiliary tank refrigerant inlet is arranged on the side of the auxiliary tank shell, and a liquid level sensor and a temperature control sensor are arranged in the cold medium storage tank body.

[0008] Preferably, a refrigeration assembly is provided at the bottom of the auxiliary tank refrigeration coil, and the refrigeration assembly includes an expansion valve, a drying filter, an evaporator and a low-temperature compressor in sequence according to the connection order, and a fan is also provided on one side of the evaporator.

[0009] Preferably, the water outlet pipe is connected to the water inlet of the chiller and the drainage pump respectively, the water outlet of the chiller and the water outlet of the seawater tank are both connected to the water inlet pipe, and the water inlet of the pure water machine is connected to the platinum resistor insertion hole;

[0010] The auxiliary tank refrigerant outlet is connected to the main tank refrigerant inlet, and the main tank refrigerant outlet and the coolant replenishing tank are both connected to the auxiliary tank refrigerant inlet.

[0011] A multi-point constant temperature calibration method for calibrating a hydrogeological temperature sensor, using the multi-point constant temperature calibration device for calibrating a hydrogeological temperature sensor, including parameter setting, temperature control, and system alarm:

[0012] The parameter setting includes: after the calibration device is powered on, the temperature control device software is initialized, and the human-computer interaction screen sends a start command, the calibration device performs temperature measurement and temperature control according to the parameter settings when it was last shut down, and actually collects the resistance value of the thermistor, combines it with the calculation formula, and substitutes it into the temperature coefficient to calculate the current measured temperature value. After the collection is completed, the measured temperature, target temperature, resistance value, temperature coefficient, and temperature control parameters are transmitted back to the human-computer interaction screen and displayed;

[0013] If the original parameters are continued to be used without updating the settings, the operator does not perform any operations, and the calibration device gradually reaches thermal equilibrium;

[0014] If relevant parameters need to be adjusted, the temperature coefficient needs to change 6 coefficients at the same time. After the setting is completed, the corresponding changes will be displayed when the human-computer interaction screen refreshes the data in the next cycle, and the calibration device gradually reaches thermal equilibrium.

[0015] Preferably, temperature control includes: setting the temperature of the large heater to be more than 2°C lower than the target temperature of the working area; if the set temperature of the large heater is higher than the actually measured temperature, turning on the large heater; when heating up, the temperature of the cold medium storage tank is lower than the target temperature of the working area; when the actual temperature of the working area is 0.2°C lower than the target temperature, the large heater stops working, and the small heater outputs power according to the internal temperature difference, maintaining the temperature fluctuation within the stabilization time of the temperature measuring bridge ≤0.0005°C; measuring the temperature with a working reference platinum resistance thermometer, and recording the measurement data of the CTD temperature sensor; when the temperature of the working area reaches A°C, placing the temperature sensor to be calibrated inside the working area to complete the A°C temperature point experiment.

[0016] Preferably, after the A℃ temperature point experiment is completed, the next temperature point AN℃ is controlled, the refrigeration component and the chiller are started, and after the working area temperature drops to the set temperature point, the refrigeration component and the chiller are turned off, the temperature fluctuation is kept ≤0.0005℃ within the stabilization time of the temperature measuring bridge, the working reference platinum resistance thermometer is used to measure the temperature, the measurement data of the CTD temperature sensor is recorded, and then the next temperature point is controlled until the temperature measurement work of all temperature points is completed.

[0017] Preferably, the system alarm includes: if a certain temperature point does not meet the temperature fluctuation requirement for a long time, the calibration device will alarm;

[0018] When the working area temperature continues to rise or fall with a deviation greater than the set temperature of 2°C, the calibration device will alarm. If no operation is detected within 10 minutes after the alarm, the data and fault status will be stored and the calibration device will shut down.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: the stirring method adopts a variable-speed dual-impeller stirring method on the end cover, which can more quickly ensure the uniformity of the temperature inside the tank body; the present invention proposes a coordinated method of fine temperature control and rapid temperature control, and adopts a temperature control method combining the main tank-auxiliary tank-refrigerator, a mode in which rapid heating and rapid cooling complement each other with fine temperature control; the temperature control algorithm of the present invention adopts an improved PID algorithm to realize the combined temperature control of the agitator and the thyristor. Among them, the agitator is responsible for small-amplitude rapid temperature control, the thyristor is responsible for large-amplitude temperature control, and the stirring and thyristor temperature control are realized based on two sets of PID parameters respectively.

[0020] The experiment of the present invention shows that the fluctuation of spatial temperature control within 180 minutes can be 0.0004°C, and the uniformity of spatial temperature field can be 0.0005°C. The device can further provide testing and calibration for serialized CTD products, help the research and development, and production of related marine instruments and equipment, enable production personnel to analyze and evaluate the measurement performance and long-term stability of CTD, etc., improve the efficiency of test and product conversion, reduce the research and development cost of marine instruments, accelerate the productization process, and promote the development of my country's marine instrument industrialization. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural diagram of the present invention;

[0022] Figure 2 The structural diagram of the main slot;

[0023] Figure 3 The structural diagram of the auxiliary tank;

[0024] Figure 4 It is a logical structure diagram of the temperature control of the present invention;

[0025] The reference numerals include: 1-main tank stirring motor, 2-reducer, 3-main tank housing, 4-auxiliary tank stirring motor, 5-auxiliary tank refrigerant outlet, 6-constant flow pump, 7-auxiliary tank housing, 8-large heater, 9-thermistor, 10-mixing zone sleeve, 11-three-blade propeller, 12-central axis fixing device, 13-temperature sensor, 15-main tank refrigeration coil, 16-small heater, 17-thermistor protection titanium tube, 18-auxiliary tank refrigerant inlet, 19-water outlet pipe, 20-sensor connection plug, 21-water inlet Tube, 22-Platinum resistor insertion hole, 23-Liquid level sensor, 24-Cold medium storage tank, 25-Main tank stirring motor shaft, 26-Auxiliary tank refrigeration coil, 27-Expansion valve, 28-Drying filter, 29-Fan, 30-Evaporator, 31-Low-temperature compressor, 32-Temperature control sensor, 33-Auxiliary tank heater, 34-Auxiliary tank stirring motor shaft, 35-Coolant replenishing tank, 36-Main tank, 37-Auxiliary tank, 38-Chiller, 39-Seawater tank, 40-Pure water machine, 41-Drain pump. DETAILED DESCRIPTION

[0026] The specific implementation of the present invention is further described below in conjunction with specific embodiments:

[0027] A multi-point constant temperature calibration device for calibrating a hydrogeological temperature sensor, comprising a main tank 36, an auxiliary tank 37, a coolant replenishing tank 35, a chiller 38, a seawater tank 39 and a pure water machine 40;

[0028] The main tank 36 includes a main tank shell 3, a mixing zone sleeve 10, a mixing zone and a working zone. The mixing zone sleeve 10 is inserted from the top of the main tank shell 3 into the working zone. The mixing zone is arranged inside the mixing zone sleeve 10. A main tank stirring motor 1 is arranged at the top of the mixing zone. The bottom of the main tank stirring motor 1 is connected to the main tank stirring motor central axis 25 and two three-blade paddles 11 in sequence downward. A reducer 2 is arranged at the top of the main tank stirring motor central axis 25. A central axis fixing device 12 perpendicular to the main tank stirring motor central axis 25 is arranged between the two three-blade paddles 11. A plurality of small adding devices are arranged along the length direction of the main tank stirring motor central axis 25. Heater 16, the main tank stirring motor central axis 25 is inserted into the mixing zone, and a plurality of main tank refrigeration coils 15 are arranged along the vertical direction of the main tank stirring motor central axis 25; two large heaters 8 and two temperature sensors 13 are arranged in the working area, the large heater 8 is arranged at the bottom of the working area, the temperature sensor 13 is arranged in the middle of the working area, a thermistor protection titanium tube 17 inserted downward from the top of the main tank 36 is arranged in the working area, the thermistor protection titanium tube 17 is provided with a thermistor 9, and a water outlet pipe 19, a water inlet pipe 21, a sensor connection plug 20 and a platinum resistor insertion hole 22 are arranged at the top of the main tank shell 3;

[0029] The auxiliary tank 37 includes an auxiliary tank shell 7, a cold medium storage tank body 24 and a bottom cavity, wherein the bottom cavity is arranged inside the auxiliary tank shell 7, the outer bottom of the cold medium storage tank body 24, an auxiliary tank stirring motor 4 is arranged on the top of the cold medium storage tank body 24, the bottom of the auxiliary tank stirring motor 4 is connected downward in sequence to the auxiliary tank stirring motor middle axis 34 and a plurality of three-blade paddles 11, a plurality of auxiliary tank 37 heaters 33 are arranged windingly along the length direction of the auxiliary tank stirring motor middle axis 34, the auxiliary tank stirring motor middle axis 34 is inserted into the cold medium storage tank body 24, a plurality of auxiliary tank refrigeration coils are arranged along the vertical direction of the auxiliary tank stirring motor middle axis 34, an auxiliary tank refrigerant outlet 5 connected to a constant flow pump 6 is arranged on the top of the auxiliary tank shell 7, an auxiliary tank refrigerant inlet 18 is arranged on the side of the auxiliary tank shell 7, and a liquid level sensor 23 and a temperature control sensor 32 are arranged in the cold medium storage tank body 24.

[0030] A refrigeration assembly is provided at the bottom of the auxiliary tank refrigeration coil, and the refrigeration assembly includes an expansion valve 27, a drying filter 28, an evaporator 30 and a low-temperature compressor 31 in the order of connection. A fan 29 is also provided on one side of the evaporator 30.

[0031] The water outlet pipe 19 is connected to the water inlet of the chiller 38 and the drainage pump 41 respectively, the water outlet of the chiller 38 and the water outlet of the seawater tank 39 are both connected to the water inlet pipe 21, and the water inlet of the pure water machine 40 is connected to the platinum resistor insertion hole 22;

[0032] The auxiliary tank coolant outlet 5 is connected to the main tank coolant inlet, and the main tank coolant outlet and the coolant replenishing tank 35 are both connected to the auxiliary tank coolant inlet 18 .

[0033] A multi-point constant temperature calibration method for calibrating a hydrogeological temperature sensor, using the multi-point constant temperature calibration device for calibrating an ocean temperature sensor 13, including parameter setting, temperature control, and system alarm:

[0034] The parameter setting includes: after the calibration device is powered on, the temperature control device software is initialized, and the human-computer interaction screen sends a start command, the calibration device performs temperature measurement and temperature control according to the parameter settings when it was last shut down, and actually collects the resistance value of the thermistor 9, combines the calculation formula, and substitutes the temperature coefficient to calculate the current measured temperature value. After the collection is completed, the measured temperature, target temperature, resistance value, temperature coefficient, and temperature control parameters are sent back to the human-computer interaction screen and displayed;

[0035] If the original parameters are continued to be used without updating the settings, the operator does not perform any operations, and the calibration device gradually reaches thermal equilibrium;

[0036] If relevant parameters need to be adjusted, the temperature coefficient needs to change 6 coefficients at the same time. After the setting is completed, the corresponding changes will be displayed when the human-computer interaction screen refreshes the data in the next cycle, and the calibration device gradually reaches thermal equilibrium.

[0037] Temperature control includes: setting the temperature of the large heater 8 to be more than 2°C lower than the target temperature of the working area. If the set temperature of the large heater 8 is higher than the actual measured temperature, turn on the large heater 8. When the temperature rises, the temperature of the cold medium storage tank 24 is lower than the target temperature of the working area. When the actual temperature of the working area is 0.2°C lower than the target temperature, the large heater 8 stops working, and the small heater 16 outputs power according to the internal temperature difference, keeps the temperature fluctuation within the stable time of the temperature measuring bridge ≤0.0005°C, measures the temperature with a working reference platinum resistance thermometer, and records the measurement data of the CTD temperature sensor 13. When the temperature of the working area reaches A°C, place the temperature sensor 13 to be calibrated inside the working area to complete the A°C temperature point experiment.

[0038] After the A℃ temperature point experiment is completed, the next temperature point AN℃ is controlled, the refrigeration component and the chiller 38 are started, and after the working area temperature drops to the set temperature point, the refrigeration component and the chiller 38 are turned off, and the temperature fluctuation within the stabilization time of the temperature measuring bridge is maintained at ≤0.0005℃. The working reference platinum resistance thermometer is used to measure the temperature, and the measurement data of the CTD temperature sensor 13 is recorded. Then the next temperature point is controlled until the temperature measurement work of all temperature points is completed.

[0039] System alarms include: If a certain temperature point does not meet the temperature fluctuation requirements for a long time, the calibration device will alarm;

[0040] When the working area temperature continues to rise or fall with a deviation greater than the set temperature of 2°C, the calibration device will alarm. If no operation is detected within 10 minutes after the alarm, the data and fault status will be stored and the calibration device will shut down.

[0041] The functions of some structures of the present invention and the detailed processes in the control logic are further described below. The overall structure of the present invention is as follows: Figure 1 , the arrow indicates the direction of liquid flow, the main tank 36 is the experimental constant temperature tank, and the auxiliary tank 37 is the auxiliary tank 37. The refrigeration component is only set at the bottom of the auxiliary tank 37, and is connected to the refrigeration system of the main tank 36 through a pipeline. The auxiliary tank 37 provides a rapid cooling cold source for the main tank 36, and the auxiliary tank 37 provides a constant flow and constant temperature working medium for the precise temperature control of the main tank 36. The agitator adopts a three-blade propeller 11 and a dispersion disk double-layer stirring structure. The three-blade propeller 11 ensures the flow of water, and the dispersion disk is responsible for increasing energy dissipation. The temperature control of the main tank 36 adopts an improved PID algorithm to realize the joint temperature control of the agitator and the thyristor. Among them, the agitator is responsible for small-scale rapid temperature control, and the thyristor is responsible for large-scale temperature control. The stirring and thyristor temperature control are realized based on two sets of PID parameters. The sensor bracket is welded with titanium tubes, and each titanium tube is processed with perforations to prevent the tube from deforming under pressure; the sensor bracket design can clamp 3-6 SBE3 sensors. The main tank 36 and the auxiliary tank 37 are connected by a pump and a conveying pipeline. The pipeline is a multi-layer composite pipe with a polyurethane insulation layer to minimize the loss of cold during the conveying process. The temperature range of the main tank 36 is relatively wide, and the temperature control accuracy requirement is relatively high. Therefore, the main and auxiliary tank 37 structures are adopted. The auxiliary tank 37 maintains a fixed temperature difference with the experimental temperature of the main tank 36, providing a stable constant temperature and constant flow fixed cold source for the temperature control of the main tank 36. If the temperature control accuracy requirement of the main tank 36 is not high and the room temperature conditions allow, you can try not to open the auxiliary tank 37, and the metering pump directly controls the flow of the refrigerant tank, thereby controlling the temperature of the main tank 36.

[0042] The auxiliary tank 37 adopts a single-cylinder design. The cooled working medium is pumped into the main tank 36 after stirring to cool it quickly. The auxiliary tank 37 needs to be installed on a special stainless steel bracket to increase the liquid level, which is conducive to the output of the medium and convenient for installation and maintenance. When the system is installed, according to the principle of communicating vessels, in order to make the working medium of the auxiliary tank 37 flow into the rapid cooler of the main tank 36 through the magnetic pump, the transportation of the cooling working medium between the auxiliary tank 37 and the main tank 36 should take into account two aspects: the flow resistance should be small, the pipeline should be insulated and the transportation distance should be shortened as much as possible. The cold medium flowing from the auxiliary tank 37 to the main tank 36 is controlled by the solenoid valves installed on their respective pipelines. The auxiliary tank 37 usually rises and falls synchronously with the main tank 36, and is about 5 to 6°C lower than the main tank 36. Reasonable thermal structure design is the key to the high-precision multi-point constant temperature measurement device for marine instrument calibration. The performance evaluation of the constant temperature tank mainly depends on two indicators: temperature fluctuation and temperature uniformity. Temperature fluctuation is the change of temperature over time; temperature uniformity is the change of temperature over position. Usually, the temperature fluctuation mainly depends on the sensitivity, stability and ability of the control system to suppress temperature changes, that is, the "temperature control quality" and the design of the thermal structure of the thermostatic bath, such as the stability of the temperature sensor 13, the thermal insulation performance of the bath, the sampling position, etc. The structure of the main bath 36 is as follows Figure 2 The functional description of each component of the main slot 36 is shown in Table 1.

[0043] Table 1

[0044]

[0045] The main slot 36 control module in the main slot 36 system adopts an intelligent controller. The temperature control program is written in C++. The controller adopts PID+fuzzy control. Thermistor 9 is used as a temperature control sensor. Thermistor 9 sensor is calibrated in the range of -5 to 40°C. The temperature resolution of -1 to 40°C is -30 to -4.0KΩ / °C. The sensor resistance corresponding to 0.00005°C is 1.5 to 0.2Ω. The working current is 2μA, which is converted into a voltage of 3 to 0.4μV. The input sensitivity of the current IC amplifier is usually greater than 0.1μV, and the conversion accuracy of the 24-bit A / D converter is 2.5×10 -23, when the effective number of bits is 16, the conversion accuracy is 0.04μV, which is less than 3~0.4μV corresponding to 0.00005℃. The temperature resolution reaches 0.00005℃. The temperature control accuracy reaches ±0.0005℃. The preamplifier A / D conversion technology meets the requirement of 0.00005℃ input sensitivity. After the main tank 36 system sets the temperature control temperature, the system will run automatically. The heater in the main tank 36 and the auxiliary tank 37 provide fast temperature rise and fall functions. When approaching the set temperature, the system will automatically switch to the temperature control state. The compiled PID temperature control algorithm will automatically adjust the cooling capacity and thyristor output of the constant flow pump 6 in the auxiliary tank 37 to make the system reach a balanced state of heat and cold. The stirring method of the main tank 36 adopts a variable-speed double-impeller stirring method on the end cover, which can more quickly ensure the uniformity of the temperature inside the tank. Through many temperature control experiments and careful analysis of the temperature control process data, the PID control algorithm and thermal inertia are accurately matched, and reasonable PID adjustment time and reasonable P\I\D values ​​are obtained.

[0046] The auxiliary tank 37 uses two controllers, one of which is a Pt100 temperature sensor 13 with a temperature resolution of 0.1°C, which displays and controls the temperature of the auxiliary tank 37; the other is a submersible pressure sensor that displays the liquid level of the refrigerant tank. The transportation of the cooling medium between the auxiliary tank 37 and the main tank 36 must take into account two aspects: the flow resistance must be small, the pipeline must be insulated, and the transportation distance must be shortened as much as possible. The cold medium flowing from the auxiliary tank 37 to the main tank 36 is controlled by solenoid valves installed on their respective pipelines. The refrigerant will be lost during use, and at this time it needs to be replenished from the coolant replenishment tank 35 by opening the metering pump and the solenoid valve. The structure of the auxiliary tank 37 is as follows Figure 3 The functional description of each component of the auxiliary slot 37 is shown in Table 2.

[0047] Table 2

[0048]

[0049] The refrigerator is a high-power compressor, which is connected to the inside of the main tank 36 through a pipeline. There are two pipelines inside the main tank 36 connected to the refrigerator, one pipeline is a water inlet, and the other pipeline is a water outlet, which is mainly used to quickly cool the seawater inside the main tank 36. The seawater tank 39 contains a filtration system, which is mainly used to store seawater with a fixed salinity value and provide seawater to the main tank 36 through a control valve. The pure water machine 40 is mainly used to manufacture and store pure water, and provides pure water to the main tank 36 through a control valve. The coolant replenishing tank 35 mainly provides coolant for the auxiliary tank 37. When the liquid level of the auxiliary tank 37 is lower than the internal liquid level sensor 23, the coolant replenishing tank 35 will trigger the pump of the coolant replenishing tank 35 to automatically replenish the liquid. When the liquid reaches a specified height, the replenishment will automatically stop. This can effectively avoid the dry burning of the heater inside the auxiliary tank 37, which will cause damage to the heater equipment, and ensure that a continuous and uninterrupted cold source is provided for the main tank 36.

[0050] The temperature control logic of the present invention is as follows Figure 4 The temperature control of the whole device is achieved by the joint temperature control of the main tank 36 and the auxiliary tank 37. The refrigerator is only involved in the cooling process. The whole device finally achieves a temperature control range of -2 to 40°C for the main tank 36, and the temperature control fluctuation reaches the level of ±0.0005°C / 15min. The temperature control uniformity reaches the level of ±0.0005°C.

[0051] The temperature control of the main tank 36 is realized by PID+ fuzzy algorithm. The temperature feedback depends on the thermistor 9 inside the main tank 36 body. The coefficient of the thermistor 9 conversion temperature is AF, which is a coefficient obtained through measurement and needs to be changed once a year. The control circuit board of the tank body will automatically use the built-in formula to convert the collected signal into temperature data and display it in real time. There are two groups of heaters inside the temperature-controlled main tank 36, one group is a small heater 16, and the other group is a large heater 8. The small heater 16 is used for fine temperature control, and the large heater 8 is used for rapid heating process. The switch temperature of the large heater 8 is set through the control screen. The control screen is connected to the PCB circuit board, and the temperature signal of the PCB circuit board comes from the thermistor 9 inside the main tank 36 body. The lower end of the PCB circuit board is connected to the small heater 16 through a thyristor. The large heater 8 inside the main tank 36 directly controls the switch of the power supply to realize startup and shutdown, and the logic of opening and closing is based on the set temperature value. The working state of the auxiliary tank 37 is selected by the operator to open or close. The auxiliary tank 37 provides a fixed cold source inside the water tank. The output cold temperature can be set on the human-computer interaction screen with a control accuracy of ±0.1°C. The circulating bath temperature is generally set to be about 5°C lower than the target temperature of the water tank. After setting the target temperature of the circulating bath, the operator clicks the circulating bath start button on the human-computer interaction screen to turn on the corresponding relay function. The refrigerator is similar to the function of the large heater 8. When the target temperature is significantly lower than the measured temperature, it is used to quickly achieve the purpose of cooling. The control method is that the operator controls the power on and off through the buttons on the human-computer interaction screen.

[0052] During the operation of the auxiliary tank 37, the internal cold medium will be lost, so the upper and lower limits of the liquid level need to be input in the control. When the data measured by the internal liquid level sensor 23 is less than the lower limit of the liquid level, the liquid replenishing pump of the auxiliary tank 37 is started. After starting to work for a period of time, when the set height of the liquid level is reached, the liquid replenishing pump of the auxiliary tank 37 is turned off.

[0053] The device is equipped with a seawater input control module. When the measured seawater level is less than 0, the discharge pump is turned off. When the measured seawater level is greater than 0, the discharge pump is turned on. In addition, the system is equipped with seawater capacity and ratio settings. When the system calculates the input volume of seawater and pure water, the salinity value of seawater is fixed, so the volume ratio can be automatically calculated according to the salinity value to control the working conditions of the seawater and pure water start-up pumps.

[0054] A pure water control module is set in the device. When the seawater of the device is used for a period of time, the internal seawater is first discharged, and then the internal maintenance is carried out. A very important part of the maintenance is to use pure water for anti-corrosion cleaning. At this time, the pure water control module is started. When the control program detects that the actual liquid level is less than the upper limit of the liquid level, the discharge pump is turned off. When the actual liquid level is greater than the upper limit of the liquid level, the discharge pump is turned on.

[0055] In order to realize the cooling process of temperature control in the above device, a refrigerator control program is set in the control system. When the temperature control main tank 36 drops from a high temperature control point to a low temperature point, in order to realize rapid cooling, the refrigerator needs to be started, and a signal instruction is sent to the PLC control circuit of the refrigerator through the PCB circuit board. At this time, the refrigerator starts to work. When the temperature value inside the temperature tank approaches the target temperature (the absolute value difference is 0.01°C), the refrigerator automatically shuts down. The temperature control main tank 36 and the auxiliary tank 37 further realize fine temperature control. The refrigerator does not participate in the work when the temperature rises during the temperature control of the whole device, but only participates in the cooling process of temperature control.

[0056] The present invention realizes a temperature control range of -2°C to 40°C, and realizes a temperature control fluctuation of ±0.0005°C / 15min in the main tank 36. The temperature control uniformity reaches ±0.0005°C. The temperature control points mainly used in the application of the marine field are 0°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, and 35°C. In actual work, the heating process is carried out first. When the temperature inside the main tank 36 reaches 35°C, the temperature sensor 13SBE3 to be calibrated is placed inside the main tank 36 body. After the experiment at the 35°C temperature point is completed, the control of the next temperature point 30°C is carried out. At this time, in order to achieve rapid cooling, the refrigerator needs to be started. When the temperature reaches 30°C±0.01°C, the refrigerator is turned off and enters a fine temperature control process. The fine temperature control is mainly achieved by the small heater 16 inside the main tank 36 and the auxiliary tank 37. During the whole process of fine temperature control, the auxiliary tank 37 is always in working state, and the temperature of the auxiliary tank 37 is lower than the target temperature set in the main tank 36. When the actual temperature in the main tank 36 is 0.2°C lower than the target temperature, the large heater 8 at the bottom of the main tank 36 stops working, and the small heater 16 will output power according to the internal temperature difference.

[0057] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A multi-point constant temperature calibration device for calibrating a hydrogeological temperature sensor, characterized in that: It includes main tank, auxiliary tank, coolant replenishment tank, chiller, seawater tank and pure water machine; The main tank includes a main tank shell, a mixing zone sleeve, a mixing zone and a working zone. The mixing zone sleeve is inserted from the top of the main tank shell into the working zone. The mixing zone is arranged inside the mixing zone sleeve. A main tank stirring motor is arranged at the top of the mixing zone. The bottom of the main tank stirring motor is connected to the main tank stirring motor middle axis and two three-blade paddles in sequence downward. A reducer is arranged at the top of the main tank stirring motor middle axis. A middle axis fixing device perpendicular to the main tank stirring motor middle axis is arranged between the two three-blade paddles. A plurality of small heaters are arranged along the length direction of the main tank stirring motor middle axis. The main tank stirring motor middle axis is inserted into the mixing zone. A plurality of main tank refrigeration coils are arranged along the vertical direction of the main tank stirring motor middle axis. Two large heaters and two temperature sensors are arranged in the working zone. The large heater is arranged at the bottom of the working zone. The temperature sensor is arranged in the middle of the working zone. A thermistor protection titanium tube is arranged in the working zone and inserted from the top of the main tank downward. A thermistor is arranged in the thermistor protection titanium tube. A water outlet pipe, a water inlet pipe, a sensor connection plug and a platinum resistor insertion hole are arranged at the top of the main tank shell. The auxiliary tank includes an auxiliary tank shell, a cold medium storage tank body and a bottom cavity, wherein the bottom cavity is arranged inside the auxiliary tank shell, the outer bottom of the cold medium storage tank body, an auxiliary tank stirring motor is arranged on the top of the cold medium storage tank body, the bottom of the auxiliary tank stirring motor is connected downward in sequence to the auxiliary tank stirring motor middle axis and a plurality of three-blade paddles, a plurality of auxiliary tank heaters are arranged along the length direction of the auxiliary tank stirring motor middle axis, the auxiliary tank stirring motor middle axis is inserted into the cold medium storage tank body, a plurality of auxiliary tank refrigeration coils are arranged along the vertical direction of the auxiliary tank stirring motor middle axis, an auxiliary tank refrigerant outlet connected to a constant flow pump is arranged on the top of the auxiliary tank shell, an auxiliary tank refrigerant inlet is arranged on the side of the auxiliary tank shell, and a liquid level sensor and a temperature control sensor are arranged in the cold medium storage tank body.

2. The multi-point constant temperature calibration device for calibrating a hydrogeological temperature sensor according to claim 1, characterized in that: A refrigeration assembly is provided at the bottom of the auxiliary tank refrigeration coil. The refrigeration assembly includes an expansion valve, a drying filter, an evaporator and a low-temperature compressor in a connection order. A fan is also provided on one side of the evaporator.

3. The multi-point constant temperature calibration device for calibrating a hydrogeological temperature sensor according to claim 2, characterized in that: The water outlet pipe is connected to the water inlet of the chiller and the drainage pump respectively, the water outlet of the chiller and the water outlet of the seawater tank are both connected to the water inlet pipe, and the water inlet of the pure water machine is connected to the insertion hole of the platinum resistor; The auxiliary tank refrigerant outlet is connected to the main tank refrigerant inlet, and the main tank refrigerant outlet and the coolant replenishing tank are both connected to the auxiliary tank refrigerant inlet.

4. A multi-point constant temperature calibration method for calibrating a hydrogeological temperature sensor, characterized in that: A multi-point constant temperature calibration device for calibrating a hydrogeological temperature sensor as described in any one of claims 1 to 3 is used, including parameter setting, temperature control, and system alarm: The parameter setting includes: after the calibration device is powered on, the temperature control device software is initialized, and the human-computer interaction screen sends a start command, the calibration device performs temperature measurement and temperature control according to the parameter settings when it was last shut down, and actually collects the resistance value of the thermistor, combines it with the calculation formula, and substitutes it into the temperature coefficient to calculate the current measured temperature value. After the collection is completed, the measured temperature, target temperature, resistance value, temperature coefficient, and temperature control parameters are transmitted back to the human-computer interaction screen and displayed; If the original parameters are continued to be used without updating the settings, the operator does not perform any operations, and the calibration device gradually reaches thermal equilibrium; If relevant parameters need to be adjusted, the temperature coefficient needs to change 6 coefficients at the same time. After the setting is completed, the corresponding changes will be displayed when the human-computer interaction screen refreshes the data in the next cycle, and the calibration device gradually reaches thermal equilibrium.

5. The multi-point constant temperature calibration method for calibrating a hydrogeological temperature sensor according to claim 4, characterized in that: Temperature control includes: setting the temperature of the large heater to be more than 2°C lower than the target temperature of the working area. If the set temperature of the large heater is higher than the actual measured temperature, turn on the large heater. When heating up, the temperature of the cold medium storage tank is lower than the target temperature of the working area. When the actual temperature of the working area is 0.2°C lower than the target temperature, the large heater stops working, and the small heater outputs power according to the internal temperature difference, keeping the temperature fluctuation within the stabilization time of the temperature measuring bridge ≤0.0005°C. The working reference platinum resistance thermometer is used to measure the temperature, and the measurement data of the CTD temperature sensor is recorded. When the temperature of the working area reaches A°C, the temperature sensor to be calibrated is placed inside the working area to complete the A°C temperature point experiment.

6. The multi-point constant temperature calibration method for calibrating a hydrogeological temperature sensor according to claim 5, characterized in that: After the A℃ temperature point experiment is completed, control the next temperature point AN℃, start the refrigeration component and the chiller, and after the working area temperature drops to the set temperature point, turn off the refrigeration component and the chiller, keep the temperature fluctuation within the stabilization time of the temperature measuring bridge ≤ 0.0005℃, measure the temperature with the working reference platinum resistance thermometer, record the measurement data of the CTD temperature sensor, and then control the next temperature point until the temperature measurement of all temperature points is completed.

7. The multi-point constant temperature calibration method for calibrating a hydrogeological temperature sensor according to claim 6, characterized in that: System alarms include: If a certain temperature point does not meet the temperature fluctuation requirements for a long time, the calibration device will alarm; When the working area temperature continues to rise or fall with a deviation greater than 2°C from the set temperature, the calibration device will alarm. If no operation is detected within 10 minutes after the alarm, the data and fault status will be stored and the calibration device will shut down.

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