Sodium chloride concentration detection device based on weighing measurement

Abstract

The utility model provides a sodium chloride concentration detection device based on weighing measurement. The sodium chloride concentration detection device comprises a reaction cup and a volumetric flask, the volumetric flask inputs a solution into the reaction cup through the direct-current peristaltic pump, a magneton is arranged in the reaction cup, a stirring motor is arranged at the bottom of the reaction cup, a magnetic impeller is mounted on a rotating shaft of the stirring motor, a glass electrode and a silver electrode are further inserted into the reaction cup, and the volumetric flask is arranged on the weighing storage tray. The glass electrode and the silver electrode output micro signals which are amplified, the magnetic stirring motor and the direct-current peristaltic pump are respectively connected with the controller, and the gravity sensor is directly connected with an engineering computer in an RS485 communication mode. According to the utility model, the weighing device is adopted to weigh the silver nitrate volumetric flask, so that the bottom volume and the change speed of a solution can be monitored in real time, the weighing device is isolated from the reaction cup, the stirrer is prevented from influencing the weighing result of the weighing device, and the electrode is amplified by the amplifier, so that a high-frequency signal can be eliminated.

Description

Technical Field

[0001] This utility model relates to a sodium chloride concentration detection device based on weighing measurement. Background Technology

[0002] Sodium chloride is a common inorganic salt widely used in production, medicine, scientific research, and daily life. In many fields, it is necessary to detect the sodium chloride content, such as water treatment, pharmaceuticals, and food processing. Traditional methods for detecting sodium chloride include boiling titration, flame photometry, and fluorescence methods, but these methods have drawbacks such as complexity, time consumption, and large errors.

[0003] Currently, automatic sodium chloride titration and detection equipment uses potentiometric titration, which is inefficient and involves cumbersome steps. During titration, a certain amount of standard solution needs to be added, and the volume of the standard solution and the potential of the test solution must be manually recorded until the solution potential no longer changes significantly. The data is then compiled, and the titration endpoint is determined manually by calculating the potential difference, volume difference, first derivative, and second derivative, thereby estimating the chloride ion content.

[0004] Because traditional detection methods are too inefficient, there is an urgent need in the market for a fully automated rapid chloride ion detection instrument that can automatically titrate, detect, and store and process data. Utility Model Content

[0005] To solve the above-mentioned technical problems, this utility model provides a sodium chloride concentration detection device based on weighing measurement.

[0006] This utility model is achieved through the following technical solution.

[0007] This utility model provides a sodium chloride concentration detection device based on weighing, comprising a reaction cup and a volumetric flask. The volumetric flask is used to pump solution into the reaction cup via a DC peristaltic pump. A magnetic stir bar is installed inside the reaction cup, and a stirring motor is located at the bottom of the reaction cup. A magnetic impeller is mounted on the shaft of the stirring motor. A glass electrode and a silver electrode are also inserted into the reaction cup. The volumetric flask is placed on a weighing pan, which is fixed to a weighing frame. The weighing frame is mounted on top of a gravity sensor, and the gravity sensor base is fixed to the housing. The glass electrode and silver electrode are connected to a controller via a signal amplifier, a magnetic stirring motor, and a DC peristaltic pump, respectively. The gravity sensor is directly connected to an engineering computer via RS485 communication.

[0008] The top opening of the volumetric flask is sealed by a cap, and the liquid extraction tube extends through the center of the cap into the bottom of the volumetric flask. The liquid extraction tube is connected to the inlet of the peristaltic pump.

[0009] The reaction cup is open, and the burette extends into the reaction cup and is connected with the outlet of the peristaltic pump.

[0010] The controller is also connected with the display screen and the industrial computer respectively.

[0011] The reaction cup is arranged in the aluminum disc, the aluminum disc is arranged on the support plate, and the fixing plate is arranged below the support plate.

[0012] The controller comprises a single-chip microcomputer, an AD conversion circuit and a signal amplifier connected in sequence, the signal amplifier is connected with the glass electrode and the silver electrode respectively, the single-chip microcomputer is connected with the direct-current peristaltic pump, the stirring motor and the industrial computer, and the industrial computer is further connected with the gravity sensor.

[0013] The signal amplifier comprises an amplification chip U5, the IN+ and IN- pins of the amplification chip U5 are connected with resistors R5 and R6 respectively, the resistors R5 and R6 are connected with the 3 and 4 pins of the pin bank, the 1 pin of the pin bank is connected with the power supply VCC through a short circuit R11, the 2 pin is connected with the ground terminal GND, the power supply VCC and the ground terminal GND are connected with a capacitor C14, the two RG pins of the amplification chip U5 are connected with a sliding resistor R4, the +VS pin is connected with the power supply VCC and grounded through a capacitor C12, and the REF pin is connected with the OUT2 pin and the IN2- pin of an operational amplifier U6.

[0014] The IN1+ pin of the operational amplifier U6 is connected with a resistor R9, the resistor R9 is connected with the OUTPUT pin of the amplifier U5, the IN1- and OUT1 pins of the operational amplifier U6 are connected with the CH1 pin of an AD conversion chip U2, the VEE / GND pin is connected with a resistor R8, the resistor R8 is connected with a sliding resistor R10, the sliding resistor R10 is connected with a resistor R7, the resistor R7 is connected with the power supply VCC, and the IN2+ pin is connected with the sliding end of the sliding resistor R10; the VEE / GND pin is also connected with the -VS pin of the amplification chip U5 and the VOUT pin of a voltage inverter U4 respectively.

[0015] The VDD pin of the voltage inverter U4 is connected with the power supply VCC, the NC and GND pins are grounded, the capacitor C7 is connected between the CAP+ and CAP-, the VDD pin is also connected with the ground through the capacitor C11 and the capacitor C15 in parallel, the VOUT pin is also connected with a capacitor C8, and the capacitor C8 is connected with the COM pin of the AD conversion chip U2.

[0016] The AD conversion circuit comprises the AD conversion chip U2, the VCC, SHDN# and VREF pins of the AD conversion chip are connected with the power supply VCC and grounded through the capacitor C4, the MODE and GND pins are grounded, and the DCLK, CS#, DIN and DOUT pins are connected with the P3.4, P3.5, P3.6 and P3.7 pins of the single-chip microcomputer U1 respectively.

[0017] The RST pin of the single-chip microcomputer U1 is connected with the paster switch KEY1 and the resistor R1 respectively, the paster switch KEY1 is connected with the power supply VCC, the resistor R1 is connected with the double-pole double-throw self-locking switch SW1, the 3-pin and 6-pin of the self-locking switch SW1 are connected with the 1-pin and 4-pin of the pin header H1 respectively, the 2-pin of the self-locking switch SW1 is grounded, the 5-pin is connected with the power supply VCC, and the light-emitting diode LED1 and the resistor R3 are connected in parallel between the 2-pin and the 5-pin of the self-locking switch SW1;

[0018] The RXD pin and the TXD pin of the single-chip microcomputer U1 are connected with the 2-pin and the 3-pin of the pin header H1 respectively, and the pin header H1 is connected with the upper computer;

[0019] The XTAL2 pin and the XTAL1 pin of the single-chip microcomputer U1 are connected with the crystal oscillator X1, the T2EX pin and the T2 pin are connected with the 1B pin and the 2B pin of the transistor array U3, and the 1C pin and the 2C pin of the transistor U3 are connected with the direct current peristaltic pump and the stirring motor respectively;

[0020] The P0.4~P0.7 pin of the single-chip microcomputer U1 is connected with the liquid crystal screen and the row resistance respectively, and the row resistance is connected with the power supply VCC.

[0021] The beneficial effect of the utility model lies in: the weighing device is used for weighing silver nitrate volumetric flask, the bottom end amount of solution and its change speed can be monitored in real time, the weighing device and the reaction cup are isolated, the weighing result of the weighing device is avoided from being influenced by the stirrer, the electrode is amplified through the amplifier, and high frequency signal can be eliminated. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 It is the structural schematic diagram of the utility model;

[0023] Figure 2 It is the circuit principle schematic diagram of the utility model;

[0024] Figure 3 It is the titration control interface schematic diagram of the utility model;

[0025] Figure 4 It is the data processing interface schematic diagram of the utility model;

[0026] Figure 5 It is the signal amplifier principle schematic diagram of the utility model;

[0027] Figure 6 It is the control and AD conversion circuit principle schematic diagram of the utility model;

[0028] Figure 7 It is the implementation design structural diagram of the utility model;

[0029] In the figure: 1 - agitator support, 2 - stirring motor, 3 - fixed plate, 4 - magnetic impeller, 5 - support plate, 6 - aluminum disc, 7 - magnetic sub, 8 - reaction cup, 9 - burette, 10 - electrode fixed plate, 11 - glass electrode, 12 - silver electrode, 13 - liquid taking pipe, 14 - peristaltic pump outlet, 15 - peristaltic pump inlet, 16 - weighed setting disc, 17 - weighing stand, 18 - gravity sensor, 19 - base, 20 - volumetric flask, 21 - fixed ring, 22 - liquid taking pipe support, 23 - peristaltic pump fixed cover, 24 - direct current peristaltic pump, 25 - signal amplifier, 26 - controller, 27 - display screen, 28 - industrial computer. DETAILED DESCRIPTION

[0030] The research on the automatic titration and detection equipment for sodium chloride is to solve the defects of the traditional method and improve the accuracy, automation and efficiency of sodium chloride detection. In modern production and scientific research, computer program control and titration instrument linkage are adopted to realize automatic reagent addition, automatic data recording, automatic result calculation and other functions, which has the advantages of high automation degree, high precision and simple operation.

[0031] In addition, the research on the automatic titration and detection equipment for sodium chloride is also closely related to digitization and intelligentization. In the field of digitization, data is automatically collected and processed by using sensors and instruments to realize production digitization, informatization and networking. In the aspect of intelligentization, a large amount of data is analyzed and interacted by deep learning technology to realize intelligent control and optimization. Therefore, the research on the automatic titration and detection equipment for sodium chloride also conforms to the trend of digitization and intelligentization.

[0032] The utility model discloses a set of automatic titration reaction type measuring instrument for sodium chloride detection which is designed by combining glass electrode and silver electrode, ADS7841 analog-digital conversion chip, gravity sensor, magnetic stirrer, signal amplifier and peristaltic pump. The measuring instrument has the characteristics of high detection efficiency, wide application range, convenient experimental system operation, data storage and processing, realizes automatic detection experiment and improves the determination precision and efficiency of chlorides. The utility model improves and innovates the traditional manual titration and manual recording experiment mode; the acid-base burette drops 0.05g in the original manual titration, the weighing precision is 0.01g by the gravity sensor weighing design, the titration end of the flow titration hose is connected with the lower straight connector, the titration solution reaches 0.02g, and the titration precision is effectively enhanced, which is the best choice for instrument replacing manual operation.

[0033] The technical scheme of the utility model will be further described below, but the scope of protection is not limited to the description.

[0034] A kind of sodium chloride concentration detection device based on weighing measurement, the application accurately controls the titration weight of silver nitrate standard titration solution by direct current peristaltic pump 24 in cooperation with weighing system, industrial computer 28 communicates with controller by USB serial port, uses the 485 communication protocol of RS-485 interface and communicates with weighing system, the operation titration of real-time accurate variable frequency drive peristaltic pump starts quickly, slow titration when near end point, silver nitrate standard titration solution is extracted into reaction cup 8.

[0035] Gravity sensor and magnetic stirring damping device design, weighing is fixed on the base of device, self-designed weighing support 17 and weighing setting disc 16, silver nitrate standard titration solution flask 20 is placed on the weighing disc to weigh;Reaction cup 8 is placed in the aluminum disc 6 of magnetic stirrer, magnetic sub 7 is placed in the reaction cup, and magnetic stirrer is designed below the aluminum disc to accelerate the reaction, the stirrer motor is fixed in the stirring motor clamping groove, the stirring device is fixed on the bottom plate of the device, gravity sensor and magnetic stirrer are in two different areas, so as not to affect the weighing of the torque of stirrer.

[0036] Gravity sensor uses 2DC senior UEr19.0 intelligent gravity sensor of Xiamen Nuosheng Measurement and Control Technology Co., Ltd., can realize 1200Hz A / D sampling rate, and has 300000 24-bit AD resolution.

[0037] With controller 26 as control center, the whole working principle is, the titration flow of silver nitrate standard titration solution of direct current peristaltic pump 24 and the motor speed of magnetic stirrer are controlled by 2-way PWM signal output by controller 26 through darlington tube to accelerate solution reaction.Glass electrode 11 and silver electrode 12 are inserted into reaction solution, for detecting potential signal in reaction solution, when silver nitrate standard titration solution is absorbed from liquid taking hose by direct current peristaltic pump 24, it is dropped into reaction solution from titration hose, and chemical reaction occurs with the reaction solution to be measured, the potential change of electrode detection reaction process is sent to controller for AD analog conversion after the detected signal is amplified by signal amplifier.

[0038] The titration device part is designed with a water baffle to prevent external liquid from flowing into the gravity sensor from the device shell during the experiment, causing inaccurate detection data. The liquid taking position is designed with a straight-through liquid taking pipe 13 for fixing the infusion hose to prevent shaking of the hose due to magnetic stirring, which may generate torsion and interfere with the experiment. The liquid taking position is also designed with a liquid taking pipe support 22 for fixing the liquid taking pipe 13, so that the hose is empty in the silver nitrate titration solution capacity bottle 20 during liquid taking, eliminating the influence of hose torsion on experimental data. An LCD 1602 liquid crystal display screen 27 is also designed on the upper surface of the instrument shell, which mainly functions to display the solution potential change AD module conversion value and the speed of the magnetic stirrer and the titration speed of the peristaltic pump in real time during the reaction titration, facilitating direct observation of the reaction by the operator.

[0039] The weighing device is designed to be fixed on the base of the device, with a self-designed weighing support column and a weighing disc. The standard titration solution is placed on the weighing disc for weighing. The reaction cup is placed on an aluminum disc above the magnetic stirrer, which is designed in the reaction cup to accelerate the reaction. The stirrer motor is fixed on the card holder, and the entire stirring device is fixed on a separate partition base to ensure the isolation of the gravity sensor and the magnetic stirrer to prevent the influence of the stirrer torsion on the weighing.

[0040] The entire software function is divided into weighing and controller real-time communication and control with the PC end 28 to achieve precise timing control of the flow. The controller communicates and controls with the PC end in real time to achieve reaction solution potential signal recognition and curve display, as well as control functions of the direct current peristaltic pump and the magnetic stirrer. The software control task is divided into weighing control and recording, magnetic stirrer speed control, and precise timing peristaltic pump flow control. The solution containing chloride 10 ml, acetone 25 ml, and nitric acid 0.2 ml is added to the reaction cup in sequence, and after the preparation is complete and the mixture is evenly mixed, the silver nitrate standard solution is titrated quickly for solution reaction. Before reaching the titration endpoint, the silver nitrate standard solution is titrated slowly. The solution potential signal AD module conversion value is collected in real time, the time scanning curve is updated and displayed in real time, and the data analysis and data management work are completed by the host computer control program precise timing control.

[0041] The signal amplification module can amplify the voltage signal by 0~1000 times, eliminate high-frequency noise signals, amplify the electrode potential signal of the device to within 5V that the controller can receive, and perfectly amplify and output the electrode potential signal of the device.

[0042] Signal acquisition, display and control circuit: through ADS7841 chip, 12-bit high-precision analog-digital conversion of electrode detection signal is carried out, the resolution reaches 1.22 mv, PWM is used to drive the direct current motor of the peristaltic pump and the magnetic stirrer through Darlington tube ULN2003A, and then the data refresh display is carried out through LCD1602 liquid crystal display screen.

[0043] During the whole automatic titration process, variable frequency flow control is designed to obtain the reaction characteristics of the titration end point, and the titration speed is slowed down near the titration end point, so as to more accurately weigh and control the flow.

[0044] The host computer adopts a producer and consumer multithreaded programming mode, sets up a one-key automation to complete the whole determination process according to the determination experiment principle, controls the speed of the magnetic stirrer in turn, records the weight of the standard silver nitrate titration solution in real time, quickly titrates the standard silver nitrate solution to react with the solution, and controls the variable frequency flow of the slow standard silver nitrate solution titration before reaching the titration end point; the host computer collects and displays the curves of the change of the reaction solution potential and the weight of the standard silver nitrate titration solution in real time, automatically determines the reaction end point, automatically processes data, manages data and realizes remote monitoring function of mobile terminal; in addition to one-key automation to complete the task, individual liquid discharge, debugging and diagnosis operation functions of a single device are set.

[0045] The host computer is controlled by LabVIEW program, as shown in Figure 3 The control interface displayed on the display screen is shown in the figure, which is composed of data storage address setting, serial port selection, original parameter setting, manual operation and magnetic stirrer speed control area from top to bottom. During the experiment, the speed of the magnetic stirrer is set, the "official test titration" button is clicked, the standard silver nitrate solution is automatically and quickly dropped into the reaction cup, slow titration is carried out when reaching the titration end point according to the set value, and the whole titration process is automatically stopped when titrating to the set end point value, at the same time, the right side of the interface program records the curves of the change of the AD potential value of the reaction solution and the titration mass of silver nitrate with time in real time during the whole titration process; the speed of the magnetic stirrer is adjusted to zero, and the "end running" button is clicked, so that the whole process data acquisition and data saving work can be completed.

[0046] As shown in Figure 4 The data processing subprogram is opened by clicking the main program "data processing" button, the left part of the program is the data operation part, the right part is the AD potential value and silver nitrate titration mass data curve playback part, the concentration of the titrated silver nitrate standard solution, the conversion constant of the mass and volume of the standard titration solution and the volume of the detection solution are input during the operation process, and the process results and Nacl concentration during the whole test process can be output by clicking the "import" button.

Claims

1. A gravimetric-based sodium chloride concentration detection device comprising a reaction cup (8) and a volumetric flask (20), characterized in that: The capacity bottle (20) inputs solution into the reaction cup (8) through the direct current peristaltic pump (24), the reaction cup (8) is provided with a magnetic sub (7), the bottom of the reaction cup (8) is provided with a stirring motor (2), the magnetic impeller (4) is installed on the rotating shaft of the stirring motor (2), the glass electrode (11) and the silver electrode (12) are inserted into the reaction cup (8), the capacity bottle (20) is placed on the weighing object plate (16), the weighing object plate (16) is fixed on the weighing stand (17), the weighing stand (17) is installed on the upper end of the gravity sensor (18), and the gravity sensor base (19) is fixed on the cabinet shell; the glass electrode (11) and the silver electrode (12) are connected with the controller (26) through the signal amplifier (25), the magnetic stirring motor (2) and the direct current peristaltic pump (24) respectively, and the gravity sensor (18) is directly connected with the engineering computer (28) in an RS485 communication mode.

2. The sodium chloride concentration detection device based on a weighing measurement according to claim 1, characterized in that: The top opening of the capacity bottle (20) is closed through a cover, the liquid taking pipe (13) penetrates through the center of the cover and extends into the bottom of the capacity bottle (20), and the liquid taking pipe (13) is connected with the peristaltic pump inlet (15).

3. The sodium chloride concentration detection device based on a weighing measurement according to claim 1, characterized in that: The reaction cup (8) is open, and the burette (9) extends into the reaction cup (8), and the burette (9) is connected with the peristaltic pump outlet (14).

4. The sodium chloride concentration detection device based on a weighing measurement according to claim 1, characterized in that: The controller (26) is also connected with the display screen (27) and the industrial computer (28) respectively.

5. The sodium chloride concentration detection device based on gravimetric measurement according to claim 1, characterized in that: The reaction cup (8) is placed in the aluminum plate (6), the aluminum plate (6) is arranged on the supporting plate (5), and the fixed plate (3) is arranged below the supporting plate (5).

6. The sodium chloride concentration detection device based on gravimetric measurement according to claim 1, characterized in that: The controller (26) comprises a single-chip microcomputer, an AD conversion circuit and a signal amplifier connected in sequence, the signal amplifier (25) is connected with the glass electrode (11) and the silver electrode (12) respectively, the single-chip microcomputer is connected with the direct current peristaltic pump (24), the magnetic stirring motor (2) and the industrial computer (28), and the industrial computer (28) is also connected with the gravity sensor (18).

7. The sodium chloride concentration detection device based on gravimetric metrology according to claim 6, characterized in that: The signal amplifier comprises an amplification chip U5, the IN+ and IN- pins of the amplification chip U5 are connected with resistors R5 and R6 respectively, the resistors R5 and R6 are connected with the 3 and 4 pins of the pin array, the 1 pin of the pin array is connected with the power supply VCC through the short circuit R11, the 2 pin is connected with the ground end GND, the capacitor C14 is connected between the power supply VCC and the ground end GND, the two RG pins of the amplification chip U5 are connected with the sliding resistor R4, the +VS pin is connected with the power supply VCC and grounded through the capacitor C12, and the REF pin is connected with the OUT2 pin and the IN2- pin of the operational amplifier U6. The IN1+ pin of the operational amplifier U6 is connected with the resistor R9, the resistor R9 is connected with the OUTPUT pin of the amplifier U5, the IN1- and OUT1 pins of the operational amplifier U6 are connected with the CH1 pin of the AD conversion chip U2, the VEE / GND pin is connected with the resistor R8, the resistor R8 is connected with the slide resistor R10, the slide resistor R10 is connected with the resistor R7, the resistor R7 is connected with the power supply VCC, the IN2+ pin is connected with the slide end of the slide resistor R10; the VEE / GND pin is also connected with the -VS pin of the amplifier chip U5 and the VOUT pin of the voltage inverter U4 respectively; The VDD pin of the voltage inverter U4 is connected with the power supply VCC, the NC and GND pins are grounded, the capacitor C7 is connected between the CAP+ and CAP- pins, the VDD pin is also connected with the ground through the capacitor C11 and the capacitor C15 in parallel, the VOUT pin is also connected with the capacitor C8, and the capacitor C8 is connected with the COM pin of the AD conversion chip U2.

8. The sodium chloride concentration detection device based on gravimetric measurement according to claim 6, characterized in that: The AD conversion circuit comprises the AD conversion chip U2, the VCC, SHDN#, and VREF pins of the AD conversion chip are connected with the power supply VCC, and are all connected with the capacitor C4 and grounded, the MODE and GND pins are grounded, the DCLK, CS#, DIN, and DOUT pins are connected with the P3.4, P3.5, P3.6, and P3.7 pins of the single-chip microcomputer U1 respectively.

9. The sodium chloride concentration detection device based on gravimetric metrology according to claim 8, characterized in that: The RST pin of the single-chip microcomputer U1 is connected with the patch switch KEY1 and the resistor R1 respectively, the patch switch KEY1 is connected with the power supply VCC, the resistor R1 is connected with the double-pole double-throw self-locking switch SW1, the 3 and 6 pins of the self-locking switch SW1 are connected with the 1 and 4 pins of the pin header H1 respectively, the 2 pin of the self-locking switch SW1 is grounded, the 5 pin is connected with the power supply VCC, and the light-emitting diode LED1 and the resistor R3 are also connected in parallel between the 2 and 5 pins of the self-locking switch SW1; The RXD and TXD pins of the single-chip microcomputer U1 are connected with the 2 and 3 pins of the pin header H1 respectively, and the pin header H1 is connected with the upper computer; The XTAL2 and XTAL1 pins of the single-chip microcomputer U1 are connected with the crystal oscillator X1, the T2EX and T2 pins are connected with the 1B and 2B pins of the transistor array U3, and the 1C and 2C pins of the transistor U3 are connected with the direct-current peristaltic pump (24) and the stirring motor (2) respectively; The P0.4~P0.7 pins of the single-chip microcomputer U1 are connected with the liquid crystal screen and the row resistor respectively, and the row resistor is connected with the power supply VCC.

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