Automatic DPD residual chlorine titration analyzer and analysis method

Abstract

The invention discloses an automatic DPD residual chlorine titration analyzer and an analysis method, the automatic DPD residual chlorine titration analyzer comprises a control and data processing unit, and the control and data processing unit comprises a microprocessor, a man-machine interaction module, a data storage module and a data transmission module; a stirrer is arranged in the reaction tank; the sample input unit comprises a sample input pipe and a liquid inlet electromagnetic valve arranged on the sample input pipe; the titrant conveying unit comprises a DPD developing reagent injector and a buffering agent injector, the DPD developing reagent injector is connected to a DPD developing reagent storage barrel through a DPD developing reagent conveying pipeline and a DPD developing reagent peristaltic pump, and the buffering agent injector is connected to a buffering agent storage barrel through a buffering agent conveying pipeline and a buffering agent peristaltic pump; the photoelectric signal detection unit comprises a transmitting circuit and a receiving circuit; the waste liquid treatment unit comprises a waste liquid barrel. The device is high in detection efficiency, high in detection precision, good in environmental protection property and convenient to popularize and use.

Description

Technical Field

[0001] The invention belongs to the technical field of water treatment, and in particular relates to an automatic DPD residual chlorine titration analyzer and an analysis method. Background Art

[0002] In the field of water treatment and public health, accurate measurement of residual chlorine content in water is crucial to ensure water quality safety. The traditional manual DPD titration method has problems such as complex operation, long time consumption, and susceptibility to human factors. Therefore, the development of an automated DPD residual chlorine titration analyzer is of great significance to improve detection efficiency and accuracy.

[0003] However, the automated DPD residual chlorine titration analyzer in the prior art still has defects and shortcomings such as low integration, insufficient detection accuracy, insufficient detection efficiency, and great difficulty in operation, which limit its popularization and use. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide an automated DPD residual chlorine titration analyzer for the above-mentioned deficiencies in the prior art, which has simple operation, high detection efficiency, high detection accuracy, good environmental protection and is easy to promote and use.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: an automated DPD residual chlorine titration analyzer, characterized in that it comprises:

[0006] Control and data processing unit, including:

[0007] A microprocessor for executing a preset titration program;

[0008] The human-computer interaction module includes a touch screen and operation buttons, which are used to receive parameters input by the user and start the titration program, and to display the titration results; the touch screen and operation buttons are connected to the microprocessor;

[0009] A data storage module, connected to the microprocessor, for storing titration results;

[0010] A data transmission module, connected to the microprocessor, for transmitting data to an external device;

[0011] A reaction tank, wherein a stirrer is arranged in the reaction tank and the stirrer is connected to an output end of a microprocessor;

[0012] A sample input unit, comprising a sample input tube and a liquid inlet solenoid valve arranged on the sample input tube, wherein the liquid inlet solenoid valve is connected to a microprocessor;

[0013] The titrant delivery unit comprises a DPD colorimetric reagent injector and a buffer injector arranged above the reaction tank, wherein the DPD colorimetric reagent injector is connected to a DPD colorimetric reagent storage barrel through a DPD colorimetric reagent delivery pipeline and a DPD colorimetric reagent peristaltic pump arranged on the DPD colorimetric reagent delivery pipeline, and the buffer injector is connected to the buffer storage barrel through a buffer delivery pipeline and a buffer peristaltic pump arranged on the buffer delivery pipeline; the push rod of the DPD colorimetric reagent injector is driven by a first stepper motor, the push rod of the buffer injector is driven by a second stepper motor, the output shaft of the first stepper motor is connected to the push rod of the DPD colorimetric reagent injector through a first connecting rod, the output shaft of the second stepper motor is connected to the push rod of the DPD colorimetric reagent injector through a second connecting rod, the output end of the microprocessor is connected to a stepper motor driver, and the first stepper motor and the second stepper motor are both connected to the output end of the stepper motor driver;

[0014] The photoelectric signal detection unit comprises a transmitting circuit and a receiving circuit, wherein the transmitting circuit is connected to the output end of the microprocessor, and the receiving circuit is connected to the input end of the microprocessor;

[0015] The waste liquid treatment unit comprises a waste liquid barrel, which is connected to the water outlet of the reaction tank through a waste liquid collecting pipe and a liquid outlet solenoid valve arranged on the waste liquid collecting pipe; the liquid outlet solenoid valve is connected to a microprocessor.

[0016] In the above-mentioned automated DPD residual chlorine titration analyzer, the inner wall of the reaction tank is coated with an anti-corrosion material, and a temperature control module for controlling the temperature in the reaction tank at a constant temperature is arranged in the reaction tank.

[0017] The above-mentioned automated DPD residual chlorine titration analyzer, the transmitting circuit includes a digital transistor Q1, a signal amplifier U1, a MOS tube Q2, a MOS tube Q3 and a transmitting tube LED, the first interface of the digital transistor Q1 is connected to the PWM signal output end of the microprocessor, the second interface of the digital transistor Q1 is grounded, the third interface of the digital transistor Q1 is connected to the first interface of the MOS tube Q2, and is connected to the first voltage output end VCC1 of the power supply through the resistor R1, the second interface of the MOS tube Q2 is connected to the second voltage output end VCC2 of the power supply, and the third interface of the MOS tube Q2 is connected in series The resistor R4 and the resistor R5 are connected to the positive input terminal of the signal amplifier U1, and the connection end of the resistor R4 and the resistor R5 is connected to the first voltage output terminal VCC1 of the power supply. The negative input terminal of the signal amplifier U1 is connected to the first voltage output terminal VCC1 of the power supply through the resistor R2. The capacitor C1 is connected between the negative input terminal and the output terminal of the signal amplifier U1. The negative input terminal and the third interface of the signal amplifier U1 are both connected to the first interface of the MOS tube Q3. The second interface of the MOS tube Q3 is connected to the positive electrode of the transmitting tube LED and is grounded through the capacitor C3. The negative electrode of the transmitting tube LED is grounded.

[0018] The above-mentioned automated DPD residual chlorine titration analyzer, the receiving circuit includes a receiving tube LED, a signal amplifier U2 and an ADC, the positive electrode of the receiving tube LED is connected to the negative input terminal of the signal amplifier U2 through a resistor R6, and is connected to the output terminal of the signal amplifier U2 through a parallel resistor R7 and a capacitor C2, the negative electrode of the receiving tube LED is grounded, the positive input terminal of the signal amplifier U2 is grounded, the output terminal of the signal amplifier U2 is connected to the input terminal of the ADC, and the output terminal of the ADC is connected to the input terminal of the microprocessor.

[0019] In the above-mentioned automated DPD residual chlorine titration analyzer, the microprocessor comprises an ARM microprocessor.

[0020] The present invention also discloses a residual chlorine titration analysis method of the above-mentioned automatic DPD residual chlorine titration analyzer, which comprises the following steps:

[0021] Step S1, the microprocessor controls the liquid inlet solenoid valve to open, and the water sample to be tested enters the reaction tank through the water inlet. When the water sample has entered the reaction tank, the microprocessor controls the solenoid valve to close;

[0022] Step S2, the microprocessor controls the DPD colorimetric reagent peristaltic pump and the buffer peristaltic pump to start, under the pumping action of the DPD colorimetric reagent peristaltic pump, the DPD colorimetric reagent enters the DPD colorimetric reagent syringe through the DPD colorimetric reagent delivery pipeline, and the microprocessor drives the first stepper motor through the stepper motor driver to drive the push rod of the DPD colorimetric reagent syringe to move downward to drip, so that the precise DPD colorimetric reagent is added to the reaction pool; under the pumping action of the buffer peristaltic pump, the buffer enters the buffer syringe through the buffer delivery pipeline, and the microprocessor drives the second stepper motor through the stepper motor driver to drive the push rod of the buffer syringe to move downward to drip, so that the precise buffer is added to the reaction pool;

[0023] Step S3, the microprocessor controls the agitator to start, so that the added DPD color developing reagent and buffer are fully stirred in the water sample to be tested;

[0024] Step S4, the photoelectric signal detection unit monitors the absorbance change of the titration reaction and transmits the monitoring signal to the microprocessor;

[0025] Step S5, the microprocessor analyzes the titration result, controls the human-computer interaction module to display it, records it in the data storage module, and determines the titration end point according to the monitoring signal and stops the titration;

[0026] Step S6: The microprocessor controls the liquid outlet solenoid valve to open, and the tested water sample flows to the waste liquid barrel through the water outlet and the waste liquid collection pipe for waste liquid collection.

[0027] In the above-mentioned residual chlorine titration analysis method of the automated DPD residual chlorine titration analyzer, before starting step S1, flushing is first performed, and then rinsing is performed; the specific process is:

[0028] Step A1, the microprocessor controls the liquid inlet solenoid valve and the liquid outlet solenoid valve to open, and uses clean water or distilled water to wash the pipeline to play a cleaning role;

[0029] Step A2: Rinse the DPD colorimetric reagent delivery pipeline and the buffer delivery pipeline with standard solution, drain the washing solution, ensure that the residual liquid in the DPD colorimetric reagent delivery pipeline and the buffer delivery pipeline is standard solution, and avoid the subsequent addition of standard solution being diluted by the residual washing solution. Rinse 2 to 3 times.

[0030] In the above-mentioned residual chlorine titration analysis method of the automated DPD residual chlorine titration analyzer, in step S2, the push rod of the DPD colorimetric reagent injector moves downward to drip liquid, and the push rod of the buffer injector moves downward to drip liquid, and the dripping speed is fast at the beginning and slows down near the end point.

[0031] Compared with the prior art, the present invention has the following advantages:

[0032] 1. The automatic DPD residual chlorine titration analyzer of the present invention has a novel and reasonable structural design and a fully automated operation process, which significantly improves the detection efficiency and reduces the operation time.

[0033] 2. The automated DPD residual chlorine titration analyzer of the present invention realizes a high-precision measurement system through the design of the sample input unit, the titrant delivery unit, the control and data processing unit, and the photoelectric signal detection unit, thereby ensuring the accuracy and reliability of the results, and the measurement accuracy reaches ±0.01 mg / L.

[0034] 3. The automated DPD residual chlorine titration analyzer of the present invention has an integrated data processing system, which facilitates the storage and analysis of results and improves data processing efficiency.

[0035] 4. The automated DPD residual chlorine titration analyzer of the present invention has a user-friendly operation interface, which simplifies the operation process and reduces the difficulty of operation, so that non-professionals can also operate it easily.

[0036] 5. The automated DPD residual chlorine titration analyzer of the present invention is an environmentally friendly waste liquid treatment system, which reduces the impact of chemical waste liquid on the environment and meets environmental protection requirements.

[0037] 6. The residual chlorine titration analysis method of the automated DPD residual chlorine titration analyzer of the present invention has high detection efficiency, high detection accuracy, good environmental protection, and is easy to promote and use.

[0038] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is the principle diagram of the automatic DPD residual chlorine titration analyzer of the present invention;

[0040] Figure 2 is a circuit schematic diagram of the transmitting circuit of the present invention;

[0041] Figure 3 4 is a circuit schematic diagram of the receiving circuit of the present invention. DETAILED DESCRIPTION

[0042] Example 1

[0043] like Figure 1 As shown, the automated DPD residual chlorine titration analyzer of this embodiment comprises:

[0044] Control and data processing unit, including:

[0045] A microprocessor for executing a preset titration program;

[0046] The human-computer interaction module includes a touch screen and operation buttons, which are used to receive parameters input by the user and start the titration program, and to display the titration results; the touch screen and operation buttons are connected to the microprocessor;

[0047] A data storage module, connected to the microprocessor, for storing titration results;

[0048] A data transmission module, connected to the microprocessor, for transmitting data to an external device;

[0049] A reaction tank, wherein a stirrer is arranged in the reaction tank and the stirrer is connected to an output end of a microprocessor;

[0050] In a specific implementation, the output terminal of the microprocessor is connected to a relay for connecting or disconnecting a power supply circuit of the stirrer; the stirring speed of the stirrer is adjustable to ensure the consistency of the reaction conditions;

[0051] A sample input unit, comprising a sample input tube and a liquid inlet solenoid valve arranged on the sample input tube, wherein the liquid inlet solenoid valve is connected to a microprocessor;

[0052] In specific implementation, the liquid inlet control accuracy can reach the microliter level;

[0053] The titrant delivery unit comprises a DPD colorimetric reagent injector and a buffer injector arranged above the reaction tank, wherein the DPD colorimetric reagent injector is connected to a DPD colorimetric reagent storage barrel through a DPD colorimetric reagent delivery pipeline and a DPD colorimetric reagent peristaltic pump arranged on the DPD colorimetric reagent delivery pipeline, and the buffer injector is connected to the buffer storage barrel through a buffer delivery pipeline and a buffer peristaltic pump arranged on the buffer delivery pipeline; the push rod of the DPD colorimetric reagent injector is driven by a first stepper motor, the push rod of the buffer injector is driven by a second stepper motor, the output shaft of the first stepper motor is connected to the push rod of the DPD colorimetric reagent injector through a first connecting rod, the output shaft of the second stepper motor is connected to the push rod of the DPD colorimetric reagent injector through a second connecting rod, the output end of the microprocessor is connected to a stepper motor driver, and the first stepper motor and the second stepper motor are both connected to the output end of the stepper motor driver;

[0054] In specific implementation, the delivery accuracy of the DPD colorimetric reagent syringe and the buffer syringe can reach 0.1 microliter, ensuring the accurate delivery of the DPD colorimetric reagent and the buffer;

[0055] The photoelectric signal detection unit comprises a transmitting circuit and a receiving circuit, wherein the transmitting circuit is connected to the output end of the microprocessor, and the receiving circuit is connected to the input end of the microprocessor;

[0056] The waste liquid treatment unit includes a waste liquid barrel, which is connected to the water outlet of the reaction pool through a waste liquid collection pipe and a liquid outlet solenoid valve arranged on the waste liquid collection pipe; the liquid outlet solenoid valve is connected to a microprocessor. By setting up the waste liquid treatment unit, the environmental protection and safety of the experimental process can be ensured.

[0057] In this embodiment, the inner wall of the reaction pool is coated with anti-corrosion material, and a temperature control module for controlling the temperature in the reaction pool at a constant temperature is provided in the reaction pool.

[0058] During specific implementation, the temperature control accuracy is 0.1°C.

[0059] In this embodiment, Figure 2 As shown, the transmitting circuit includes a digital transistor Q1, a signal amplifier U1, a MOS tube Q2, a MOS tube Q3 and a transmitting tube LED, the first interface of the digital transistor Q1 is connected to the PWM signal output end of the microprocessor, the second interface of the digital transistor Q1 is grounded, the third interface of the digital transistor Q1 is connected to the first interface of the MOS tube Q2, and is connected to the first voltage output end VCC1 of the power supply through the resistor R1, the second interface of the MOS tube Q2 is connected to the second voltage output end VCC2 of the power supply, and the third interface of the MOS tube Q2 is connected to the second voltage output end VCC2 of the power supply through the resistor R4 and the resistor R5 in series. R5 is connected to the positive input terminal of the signal amplifier U1, the connection end of the resistor R4 and the resistor R5 is connected to the first voltage output terminal VCC1 of the power supply, the negative input terminal of the signal amplifier U1 is connected to the first voltage output terminal VCC1 of the power supply through the resistor R2, a capacitor C1 is connected between the negative input terminal and the output terminal of the signal amplifier U1, the negative input terminal and the third interface of the signal amplifier U1 are both connected to the first interface of the MOS tube Q3, the second interface of the MOS tube Q3 is connected to the positive electrode of the transmitting tube LED and is grounded through the capacitor C3, and the negative electrode of the transmitting tube LED is grounded.

[0060] In this embodiment, Figure 3 As shown, the receiving circuit includes a receiving tube LED, a signal amplifier U2 and an ADC (analog-to-digital converter). The positive electrode of the receiving tube LED is connected to the negative input terminal of the signal amplifier U2 through a resistor R6, and is connected to the output terminal of the signal amplifier U2 through a parallel resistor R7 and a capacitor C2. The negative electrode of the receiving tube LED is grounded, the positive input terminal of the signal amplifier U2 is grounded, the output terminal of the signal amplifier U2 is connected to the input terminal of the ADC, and the output terminal of the ADC is connected to the input terminal of the microprocessor.

[0061] In specific implementation, the transmitting tube LED and the receiving tube LED both use high-sensitivity photodiodes with a detection wavelength range of 400-700 nanometers, which can monitor the color changes in the reaction pool in real time.

[0062] In this embodiment, the microprocessor includes an ARM microprocessor.

[0063] Example 2

[0064] The residual chlorine titration analysis method of the automated DPD residual chlorine titration analyzer of this embodiment comprises the following steps:

[0065] Step S1, the microprocessor controls the liquid inlet solenoid valve to open, and the water sample to be tested enters the reaction tank through the water inlet. When the water sample has entered the reaction tank, the microprocessor controls the solenoid valve to close;

[0066] Step S2, the microprocessor controls the DPD colorimetric reagent peristaltic pump and the buffer peristaltic pump to start, under the pumping action of the DPD colorimetric reagent peristaltic pump, the DPD colorimetric reagent enters the DPD colorimetric reagent syringe through the DPD colorimetric reagent delivery pipeline, and the microprocessor drives the first stepper motor through the stepper motor driver to drive the push rod of the DPD colorimetric reagent syringe to move downward to drip, so that the precise DPD colorimetric reagent is added to the reaction pool; under the pumping action of the buffer peristaltic pump, the buffer enters the buffer syringe through the buffer delivery pipeline, and the microprocessor drives the second stepper motor through the stepper motor driver to drive the push rod of the buffer syringe to move downward to drip, so that the precise buffer is added to the reaction pool;

[0067] In specific implementation, the microprocessor controls the push rods of the DPD color reagent syringe and the buffer syringe to move linearly up and down at a uniform speed. The upward movement is for liquid replenishment and addition; the downward movement is for dripping;

[0068] Step S3, the microprocessor controls the agitator to start, so that the added DPD color developing reagent and buffer are fully stirred in the water sample to be tested;

[0069] Step S4, the photoelectric signal detection unit monitors the absorbance change of the titration reaction and transmits the monitoring signal to the microprocessor;

[0070] Step S5, the microprocessor analyzes the titration result, controls the human-computer interaction module to display it, records it in the data storage module, and determines the titration end point according to the monitoring signal and stops the titration;

[0071] Step S6: The microprocessor controls the liquid outlet solenoid valve to open, and the tested water sample flows to the waste liquid barrel through the water outlet and the waste liquid collection pipe for waste liquid collection.

[0072] In this embodiment, before step S1 starts, flushing is performed first, and then rinsing is performed; the specific process is:

[0073] Step A1, the microprocessor controls the liquid inlet solenoid valve and the liquid outlet solenoid valve to open, and uses clean water or distilled water to wash the pipeline to play a cleaning role;

[0074] Step A2: Rinse the DPD colorimetric reagent delivery pipeline and the buffer delivery pipeline with standard solution, drain the washing solution, ensure that the residual liquid in the DPD colorimetric reagent delivery pipeline and the buffer delivery pipeline is standard solution, and avoid the subsequent addition of standard solution being diluted by the residual washing solution. Rinse 2 to 3 times.

[0075] In this embodiment, when the push rod of the DPD colorimetric reagent syringe moves downward to drip liquid and the push rod of the buffer syringe moves downward to drip liquid in step S2, the dripping speed is fast at the beginning and slows down near the end point.

[0076] In specific implementation, when the color of the solution changes suddenly, the titration is stopped, and if the color does not change within 30 seconds, this moment is determined as the titration endpoint and the titration is stopped.

[0077] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent structural change made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. An automated DPD residual chlorine titration analyzer, characterized in that: include: Control and data processing unit, including: A microprocessor for executing a preset titration program; The human-computer interaction module includes a touch screen and operation buttons, which are used to receive parameters input by the user and start the titration program, and to display the titration results; the touch screen and operation buttons are connected to the microprocessor; A data storage module, connected to the microprocessor, for storing titration results; A data transmission module, connected to the microprocessor, for transmitting data to an external device; A reaction tank, wherein a stirrer is arranged in the reaction tank and the stirrer is connected to an output end of a microprocessor; A sample input unit, comprising a sample input tube and a liquid inlet solenoid valve arranged on the sample input tube, wherein the liquid inlet solenoid valve is connected to a microprocessor; The titrant delivery unit comprises a DPD colorimetric reagent injector and a buffer injector arranged above the reaction pool, wherein the DPD colorimetric reagent injector is connected to a DPD colorimetric reagent storage barrel through a DPD colorimetric reagent delivery pipeline and a DPD colorimetric reagent peristaltic pump arranged on the DPD colorimetric reagent delivery pipeline, and the buffer injector is connected to the buffer storage barrel through a buffer delivery pipeline and a buffer peristaltic pump arranged on the buffer delivery pipeline; the push rod of the DPD colorimetric reagent injector is driven by a first stepper motor, the push rod of the buffer injector is driven by a second stepper motor, the output shaft of the first stepper motor is connected to the push rod of the DPD colorimetric reagent injector through a first connecting rod, the output shaft of the second stepper motor is connected to the push rod of the DPD colorimetric reagent injector through a second connecting rod, the output end of the microprocessor is connected to a stepper motor driver, and the first stepper motor and the second stepper motor are both connected to the output end of the stepper motor driver; The photoelectric signal detection unit comprises a transmitting circuit and a receiving circuit, wherein the transmitting circuit is connected to the output end of the microprocessor, and the receiving circuit is connected to the input end of the microprocessor; The waste liquid treatment unit comprises a waste liquid barrel, which is connected to the water outlet of the reaction tank through a waste liquid collecting pipe and a liquid outlet solenoid valve arranged on the waste liquid collecting pipe; the liquid outlet solenoid valve is connected to a microprocessor.

2. The automated DPD residual chlorine titration analyzer according to claim 1, characterized in that: The inner wall of the reaction pool is coated with anti-corrosion material, and a temperature control module for controlling the temperature in the reaction pool at a constant temperature is arranged in the reaction pool.

3. The automated DPD residual chlorine titration analyzer according to claim 1, characterized in that: The transmitting circuit includes a digital transistor Q1, a signal amplifier U1, a MOS tube Q2, a MOS tube Q3 and a transmitting tube LED. The first interface of the digital transistor Q1 is connected to the PWM signal output end of the microprocessor, the second interface of the digital transistor Q1 is grounded, the third interface of the digital transistor Q1 is connected to the first interface of the MOS tube Q2, and is connected to the first voltage output end VCC1 of the power supply through a resistor R1, the second interface of the MOS tube Q2 is connected to the second voltage output end VCC2 of the power supply, and the third interface of the MOS tube Q2 is connected to the first interface of the MOS tube Q2 through a resistor R4 and a resistor R5 in series. 5 is connected to the positive input terminal of the signal amplifier U1, the connection end of the resistor R4 and the resistor R5 is connected to the first voltage output terminal VCC1 of the power supply, the negative input terminal of the signal amplifier U1 is connected to the first voltage output terminal VCC1 of the power supply through the resistor R2, a capacitor C1 is connected between the negative input terminal and the output terminal of the signal amplifier U1, the negative input terminal of the signal amplifier U1 and the third interface are both connected to the first interface of the MOS tube Q3, the second interface of the MOS tube Q3 is connected to the positive electrode of the transmitting tube LED and is grounded through the capacitor C3, and the negative electrode of the transmitting tube LED is grounded.

4. The automated DPD residual chlorine titration analyzer according to claim 1, characterized in that: The receiving circuit includes a receiving tube LED, a signal amplifier U2 and an ADC. The positive electrode of the receiving tube LED is connected to the negative input terminal of the signal amplifier U2 through a resistor R6, and is connected to the output terminal of the signal amplifier U2 through a resistor R7 and a capacitor C2 connected in parallel. The negative electrode of the receiving tube LED is grounded, the positive input terminal of the signal amplifier U2 is grounded, the output terminal of the signal amplifier U2 is connected to the input terminal of the ADC, and the output terminal of the ADC is connected to the input terminal of the microprocessor.

5. The automated DPD residual chlorine titration analyzer according to claim 1, characterized in that: The microprocessor comprises an ARM microprocessor.

6. A residual chlorine titration analysis method of the automated DPD residual chlorine titration analyzer as claimed in claim 1, characterized in that: The method comprises the following steps: Step S1, the microprocessor controls the liquid inlet solenoid valve to open, and the water sample to be tested enters the reaction tank through the water inlet. When the water sample has entered the reaction tank, the microprocessor controls the solenoid valve to close; Step S2, the microprocessor controls the DPD colorimetric reagent peristaltic pump and the buffer peristaltic pump to start, under the pumping action of the DPD colorimetric reagent peristaltic pump, the DPD colorimetric reagent enters the DPD colorimetric reagent syringe through the DPD colorimetric reagent delivery pipeline, and the microprocessor drives the first stepper motor through the stepper motor driver to drive the push rod of the DPD colorimetric reagent syringe to move downward to drip, so that the precise DPD colorimetric reagent is added to the reaction pool; under the pumping action of the buffer peristaltic pump, the buffer enters the buffer syringe through the buffer delivery pipeline, and the microprocessor drives the second stepper motor through the stepper motor driver to drive the push rod of the buffer syringe to move downward to drip, so that the precise buffer is added to the reaction pool; Step S3, the microprocessor controls the agitator to start, so that the added DPD color developing reagent and buffer are fully stirred in the water sample to be tested; Step S4, the photoelectric signal detection unit monitors the absorbance change of the titration reaction and transmits the monitoring signal to the microprocessor; Step S5, the microprocessor analyzes the titration result, controls the human-computer interaction module to display it, records it in the data storage module, and determines the titration end point according to the monitoring signal and stops the titration; Step S6: The microprocessor controls the liquid outlet solenoid valve to open, and the tested water sample flows to the waste liquid barrel through the water outlet and the waste liquid collection pipe for waste liquid collection.

7. The residual chlorine titration analysis method of the automated DPD residual chlorine titration analyzer according to claim 6, characterized in that: Before step S1 begins, flushing is performed first, and then rinsing is performed; the specific process is as follows: Step A1, the microprocessor controls the liquid inlet solenoid valve and the liquid outlet solenoid valve to open, and uses clean water or distilled water to wash the pipeline to play a cleaning role; Step A2: Rinse the DPD colorimetric reagent delivery pipeline and the buffer delivery pipeline with standard solution, drain the washing solution, ensure that the residual liquid in the DPD colorimetric reagent delivery pipeline and the buffer delivery pipeline is standard solution, and avoid the subsequent addition of standard solution being diluted by the residual washing solution. Rinse 2 to 3 times.

8. The residual chlorine titration analysis method of the automated DPD residual chlorine titration analyzer according to claim 6, characterized in that: In step S2, when the push rod of the DPD color developing reagent syringe moves downward to drip liquid, and when the push rod of the buffer syringe moves downward to drip liquid, the dripping speed is fast at the beginning and slows down near the end point.

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