A fully automatic COD analysis device

Abstract

The present invention provides a fully automatic chemical oxygen demand analyzer, comprising a condensation module, a heating module, a sample tube module, a linear module, a stepper motor, an outer box, a color sensor, a light source, and an automatic controller, wherein the condensation module comprises a condensation tube disc and a condensation water pipeline; the sample tube module comprises a sample tube turntable, the surface of which is provided with two or more circles of sample tube jacks, and each sample tube jack vertically corresponds to the jack of the condensation tube disc; the surface of the heating module is provided with two or more circles of hole-shaped heating holes, each heating hole is provided with a heating block, wherein each heating hole vertically corresponds to each sample tube jack to accommodate the sample tube. Since the sample tube or sample cup is fixed in the vertical direction, the condensation module cools the condensation tube according to the instruction, and the heating module performs cold heating on the sample tube or sample cup, and the condensation tube and the heating module are separated from the sample tube respectively through the linear module, thereby realizing simultaneous or differentiated high-throughput processing of the titration sample.

Description

Technical Field

[0001] The invention relates to a chemical oxygen demand (COD) measuring instrument in the field of environmental protection detection, and in particular to a fully automatic chemical oxygen demand analyzer capable of realizing high-throughput sample tube digestion and titration, belonging to the field of analytical chemistry detection. Background Art

[0002] Chemical oxygen demand (COD) refers to the mass concentration of oxygen corresponding to the strong oxidant potassium dichromate consumed by dissolved substances and suspended matter in water under certain conditions, measured in mg / L. It is a comprehensive indicator of reducing substances in water. If the COD in water is too high, it means that organic pollution is very serious, which will destroy the balance of the environment and biological communities and cause water deterioration. Therefore, COD is an important parameter of sewage treatment plants and an important indicator of environmental monitoring.

[0003] Traditional chemical oxygen demand is divided into permanganate method (also known as permanganate index) and potassium dichromate method according to different oxidizing agents. Corresponding national standards have also been established. The current national standard corresponding to the permanganate index is "GB11892-1989 Determination of water quality permanganate index", and the current national standard for the determination of chemical oxygen demand by potassium dichromate method is "HJ828-2017 Determination of chemical oxygen demand in water quality - dichromate method" (hereinafter referred to as "HJ 828-2017 Standard"). According to the standard method, the existing determination scheme is manual determination throughout the process, requiring users to equip reflux devices, heating devices, acid burettes and other manual operation equipment (see pages 3-4 of the standard for details), and perform manual reagent addition, high temperature reflux digestion, manual color endpoint titration and other steps according to the standard requirements (see pages 4-5 of the standard for details). It can be widely used in the determination of chemical oxygen demand in surface water, domestic sewage and industrial wastewater, and has the advantages of wide test range, good reproducibility, strong interference removal, high accuracy and precision, etc., but there are still the following problems in use:

[0004] (1) This method strictly stipulates the test steps, such as heating digestion time, solution acidity, amount of oxidant and catalyst, and other condition indicators. When using manual method for measurement, different testers will inevitably produce test errors.

[0005] (2) This method is time-consuming, requires a large number of reagents and tools, is labor-intensive, and is inefficient when measuring large quantities of samples.

[0006] (3) The reagents encountered during the experiment are harmful to the human body. The gases released due to high-temperature digestion during the experiment also have a certain negative impact on the health of the test personnel.

[0007] (4) This method strictly stipulates that heavy metal reagents (such as mercuric sulfate and potassium dichromate standard solution) should be added to the digestion bottle (i.e., conical flask) and shaken well with explosion-proof glass beads. Low-boiling point reagents (such as silver sulfate-sulfuric acid solution) should be added slowly from the top of the condenser to prevent the escape of low-boiling point organic matter. This determines that different reagents should be added in different ways, so different liquid addition devices need to be set up.

[0008] According to the requirements of the above standards, semi-automatic instruments and equipment that solve part of the user's work have appeared on the market. For example, Fu Congyu (Research on Automatic Titration Device for Chemical Oxygen Demand, Contemporary Chemical Research, Issue 3, 2019) designed and developed a COD automatic titration device. The device uses a color sensor to simulate the human eye to identify the color of the solution, and intelligently adjusts the titration speed according to the color, so as to accurately and quickly determine the titration end point. The titration device consists of a titration cell, a syringe, a color sensor and an electromagnetic stirring motor, which are connected by a capillary made of polytetrafluoroethylene and a three-way solenoid valve. The titration cell is placed on the AC stirring motor and has a built-in stirrer. The syringe is located above the titration cell and is connected to the three-way solenoid valve through a capillary. The three-way solenoid valve is connected to the ammonium ferrous sulfate standard solution through a capillary when it is open, and is inserted into the titration cell through a capillary when the three-way solenoid valve is open. The color sensor is fixed at a height of 10 cm below the titration cell. During use, the three-way valve is switched to port a, and the injection pump draws the standard solution of ammonium ferrous sulfate; the indicator is added to the cooled solution to be tested after digestion and then transferred to the titration cell; the electromagnetic stirring motor is turned on; the three-way valve is switched to port b, and the injection pump starts titrating at a certain speed. When the color sensor senses the target color, it outputs a signal and the injection pump stops working; the consumption of ammonium ferrous sulfate is output to the computer software, and the software calculates and displays the measurement results. However, the device mainly realizes the automatic titration of a limited number of sample tubes by modifying the pipelines and electromagnetic valves for injection, liquid addition and titration, and cannot realize the condensation and titration of high-throughput or large-scale sample tubes.

[0009] Chinese invention application CN201810059775.4, "A laboratory COD automatic analysis robot", discloses the use of automated mechanical devices to achieve automatic analysis of the entire process from sample addition to digestion reflux and color titration, solving the application needs of full automation. However, the mechanical anthropomorphic scheme used in this scheme uses multiple mechanical gripper groups, multiple sets of mobile liquid adding arms and other mechanical control components. In the actual production and application process, there are deficiencies such as difficulty in mechanical structure design and high failure rate of the whole machine, greater difficulty in production and assembly, and low reliability of the whole machine; and the glass magic mouth transfer coordination in the scheme is prone to data deviation caused by loose coordination, component damage caused by collisions during coordination, and other faults.

[0010] Chinese invention patent application 202010197092.2, "A fully automatic chemical oxygen demand analyzer and its workflow" discloses an analyzer containing an automatic titration unit, wherein the automatic titration unit includes a lower liquid adding component and a lower transmission mechanism as well as a detection unit, a light source bracket, a magnetic stirring mechanism, an optical sensor, etc., wherein the lower transmission mechanism includes a lower base slide; the lower base slide can be slidably mounted on the guide rail of the lower liquid adding transmission mechanism; the lower base slide is mounted with a lower liquid adding arm; a plurality of reagent channels can be arranged on the lower liquid adding arm; the magnetic stirring mechanism is also mounted on the lower base slide; when the lower liquid adding component moves to a certain digestion drop position, the magnetic stirring mechanism is located just below the digestion drop position, and the reagent channel outlet of the lower liquid adding arm is located just above the digestion drop position. The lower base slide and the lower liquid adding arm of the device have relatively complex structures, and the titration position to be titrated can only move horizontally, which affects the titration speed.

[0011] Chinese patent application CN201110204582.1, titled "A COD fully automatic online monitoring system and monitoring method thereof", discloses a monitoring device comprising an electric injector, an optical quantitative device, a multi-channel adapter, and a reaction pool. During operation, the optical quantitative device generates negative pressure by pumping air through the electric injector, thereby driving the assay liquid and various reaction reagents into the optical quantitative device through the injection channel of the multi-channel adapter, and then the gas is pressed into the electric injector, so that the liquid in the optical quantitative device enters the reaction pool one by one for digestion reaction. During the reaction, the detection electrode arranged in the reaction pool monitors the current change value of the solution in real time, thereby determining the reaction endpoint. After the reaction is completed, the electric injector is used to pump air again, so that the waste liquid flows to the waste liquid pool through the multi-channel adapter and the waste liquid flow path. Although the invention is relatively simple, its shortcomings are: it is necessary to additionally set up an optical quantitative device similar to a buffer tank. If all the reaction solutions are accommodated at one time, the digestion reaction will occur prematurely, generating harmful gases and heat that are difficult to control; if the reaction solutions are added and transferred one by one, excessive residues of the reaction solutions will occur; the invention utilizes the change value of the current signal monitored in the reaction tank, which is completely different from the existing titration tank device, and is therefore not conducive to the improvement and application of the existing COD detector; in addition, the invention adopts potentiometric titration for determination, which is substantially different from the detection standard of the present invention, wherein high pressure and high temperature are used for rapid digestion, and only the absorption, reagent addition, titration analysis, etc. of a single sample can be completed, and large-scale multi-channel cyclic rapid analysis in the laboratory cannot be realized.

[0012] Chinese invention patent application CN201510416372.7, invention name "A method and device for measuring constant volume liquid inlet for COD detection" discloses a device that can automatically determine the volume of solution and reduce the cumulative error of liquid extraction. The invention point is to combine the principle of laser triangulation distance measurement with linear stepper motor positioning and horizontal moving rod technology to achieve high-precision, flexible and random, continuous constant volume liquid extraction, thereby ensuring the accuracy of solution volume measurement, and changing the disadvantages of traditional mechanical fixed volume liquid extraction, with high effect. Chinese patent application CN201521028392.9, invention name "Chemical oxygen demand detector" discloses a detector including a sampling pump, a multi-way valve, a high-temperature and high-pressure digestion chamber, and a controller. The improvement over the existing measuring instrument is that a high-pressure solenoid valve is set in the multi-way valve and the digestion chamber, which can switch the liquid flow path according to the computer instruction to prevent the impact of high-pressure gas on the multi-way valve. In addition, a high-pressure solenoid valve is also set at the waste liquid outlet at the bottom of the digestion chamber to facilitate the automatic discharge of waste liquid.

[0013] Chinese invention patent application 202010181373.9, "A COD analysis device", discloses a COD analysis device, which includes a housing, a condensation reflux mechanism located at the upper part of the housing, a sample turntable located at the lower part of the housing corresponding to the position of the condensation reflux mechanism, a driving mechanism located at the lower part of the sample turntable for driving the sample turntable to rotate, a heating module located below the sample turntable for sample heating, a lifting mechanism for lifting the heating module, and a detection device for sample detection. The device embodies a sample turntable and a condenser turntable with two layers, wherein the heating module at the bottom of the sample turntable can lift the sample turntable up until it docks with the condenser. Then, a rotary condenser liquid adding arm (first rotating arm) and a burette liquid adding arm (second rotating arm) are respectively provided, wherein the liquid adding arm can be set to different rotation angles as needed to achieve liquid adding distances of different distances. In addition, a color sensor or a photoelectric sensor is provided on the second liquid adding arm for monitoring. However, the device does not fully comply with the operating specifications of the "HJ 828-2017 Standard", namely: (1) In order to simplify the structure of the device, the device can only add heavy metal reagents and light boiling point reagents through the condenser filling arm; (2) Because the heating module is fixedly connected to the sample tray and drives it to connect and disconnect from the condenser, after the heating time is over, the heating module cannot be directly detached from the sample tray. It can only wait for the internal heat of the heating module to gradually disappear before the heating module can drive the sample tray to move to the titration position. Otherwise, if the heating module drives the sample turntable to detach from the condenser, it will cause the high-temperature liquid in the digestion bottle to splash, affecting the detection accuracy. Therefore, the design of this heating module fixedly connected to the sample tray prolongs the cooling time of the digestion solution, which is not conducive to the needs of rapid detection.

[0014] In addition, the current screw-in type liquid adding arm usually has only one liquid adding hole for digestion solution. If the liquid adding speed is too fast, it may rapidly impact the sample liquid and cause liquid splashing. If it is too slow, or if manual addition is strictly carried out in accordance with the standard of "HJ 828-2017 Determination of Chemical Oxygen Demand of Water Quality - Dichromate Method", the liquid adding speed will be too slow and it will be difficult to ensure the liquid adding efficiency. At the same time, this liquid adding arm is limited by the rotation axis and can only be suitable for sample addition of a single-circle sample plate.

[0015] Therefore, there is a need for a fully automatic chemical oxygen demand analyzer that strictly complies with the "HJ 828-2017 Standard" and can achieve rapid cooling of the digestion solution and high-throughput liquid addition titration. Summary of the invention

[0016] The first principle of the present invention is to fix the condensation module and the heating module on a pair of vertically moving linear modules, which can move toward and against each other to combine and separate. Since the sample tube or sample cup is fixed in the vertical direction, the condensation module cools the condenser tube according to the instruction, and the heating module heats and cools the sample tube or sample cup, and the condenser tube and the heating module are separated from the sample tube respectively, so that the sample tube digestion liquid can be separated from the heating module immediately, thereby increasing the cooling speed. Among them, each condenser tube, sample tube / sample cup can also correspond to a set of linear modules, and each heating module adopts an independent parallel heating structure, so as to realize the digestion, catalysis, cooling, separation of the condenser tube and the sample tube, and simultaneous or differentiated high-throughput processing of titration samples.

[0017] The second principle of the present invention is to set up two disc-type structures to accommodate condensers and sample tubes, wherein the condenser disc socket corresponds vertically to the socket of the sample tube turntable, and two or more circles of sockets can be set. At the same time, unlike the existing design of only setting up one liquid adding arm or liquid adding tube, two liquid adding arms are creatively set up, namely the first liquid adding arm for filling low-boiling point reagents and the second liquid adding arm for filling digestion liquid. Among them, the first liquid adding arm is fixed above the axis of the condenser disc, and two or more liquid adding ports are arranged on it, so that two or more circles of condenser / sample tubes can be filled with liquid. In order not to prevent the heating module from contacting the sample turntable, the second liquid adding arm is not fixed on the axis of the sample turntable, but is arranged on the outside of the edge of the sample turntable. Since the two or more circles of sockets of the sample turntable and the condenser disc are arranged at intervals, the second liquid adding arm uses the correspondence between the radius difference between the inner and outer circles and the rotation angle of the liquid adding arm to realize the addition of liquid to the sample tubes on the two or more circles of sockets.

[0018] The third principle of the present invention is that, based on the above principle, the liquid adding head of the second liquid adding arm is provided with 6 liquid adding capillaries, which are evenly distributed on the circumference and spaced a certain distance from each other to avoid mixing of reagents. At the same time, the head of each liquid adding capillaries is subjected to inner diameter shrinkage treatment, so that when the liquid is pumped out at high speed, the residual liquid of the reagent is effectively prevented from hanging on the head of the reagent tube and affecting the amount of reagent added.

[0019] The fourth principle of the present invention is to set an empty position recognition function for the sample tube installation position on the basis of the above principles to prevent misoperation such as adding liquid, cooling or heating without placing the sample tube. At the same time, the various heating blocks of the heating module are connected in parallel and automated control is adopted, so that the testing of a small amount or full amount of samples can be flexibly arranged, and misoperation caused by empty sample tubes can be avoided.

[0020] The fifth principle of the present invention is to integrate all the above modules into an analyzer for COD determination on the basis of the above principles, and to achieve the effects of automatic control and determination.

[0021] Therefore, the first object of the present invention is to provide a fully automatic chemical oxygen demand analyzer, comprising a condensation module, a heating module, a sample tube module, a linear module, a stepper motor, an outer box, a color sensor, a light source, and an automatic controller, wherein:

[0022] (1) The condensation module includes a condenser disc, a condensing water pipeline, and a cold water container, wherein the surface of the condenser disc is provided with two or more circles of condenser plug holes; the condenser is provided with a water inlet at the upper end and a water outlet at the lower end, which are connected to the chiller through the condensing water pipeline, thereby forming a cooling circuit;

[0023] (2) The sample tube module includes a sample tube turntable, the surface of which is provided with two or more circles of sample tube insertion holes, and each sample tube insertion hole vertically corresponds to the insertion hole of the condenser tube disk;

[0024] (3) The heating module is a disk with a diameter slightly larger than or equal to that of the sample tube turntable, and has two or more circles of hole-shaped heating holes on its surface, each of which is provided with a heating block, wherein each heating hole vertically corresponds to each sample tube insertion hole to accommodate the sample tube;

[0025] (4) The linear module includes a coupling, an upper slider, a lower slider, an upper lead screw, and a lower lead screw, wherein the upper slider is fixed to the condensation module, the lower slider is fixed to the heating module, the coupling is arranged in the middle of the condensation tube disc and the sample tube turntable, the upper lead screw and the lower lead screw respectively pass through the upper slider and the lower slider and are connected by the coupling, and since the upper and lower lead screws have different rotation directions, when the stepper motor connected to the shaft end of the upper end of the upper lead screw rotates, the upper and lower lead screws respectively drive the upper and lower sliders to move toward or in the opposite direction, thereby driving the condensation module and the heating module to vertically approach or separate the sample tube at the same time;

[0026] (5) The fixed end of the first liquid adding arm is connected to the center of the condenser disc, and two or more liquid adding holes are provided on the extending arm. When the first liquid adding arm rotates about the center, the two or more liquid adding holes can pass directly above each condenser tube opening; a hollow pipeline is provided inside the first liquid adding arm, and the pipeline is connected to the catalyst container;

[0027] (6) The fixed end of the second liquid adding arm is connected to the outer side of the edge of the sample turntable, and the rotating end thereof uses different rotation angles to add liquid to each sample tube on two or more circles of the sockets;

[0028] (7) The outer box is a closed box with an exhaust pipe and a top exhaust fan on the top, which can exhaust the harmful gases generated during digestion by top exhaust;

[0029] (8) A color sensor and a light source are provided in the vertical direction of the fixed end of the second liquid-adding arm, wherein the light source emits light to the sample tube to be tested as the liquid-adding arm rotates, and the color sensor receives the light reflected or scattered in the sample tube (i.e., sample bottle, titration bottle), thereby completing color detection.

[0030] In one embodiment, each heating block in the heating module is connected in parallel, and a single or multiple heating holes are controlled by an automatic controller to heat the sample tubes contained therein. In a specific embodiment, an independent PCB small board is provided under each heating block for control. In a preferred embodiment, the bottom of the heating module is divided into several areas, each of which is provided with several whole PCB boards (e.g., circuit boards), so that each independent PCB lower board is integrated into the whole PCB board, and regional or overall heating of all heating blocks is achieved. In order to prevent high temperature from affecting the operator and internal heat from radiating outwards to cause uneven heating, a heating zone protective plate is also provided on the outer edge of the heating module. In a more preferred embodiment, the heating block is a ceramic heating block or a ceramic heating sheet, and a temperature switch is provided to prevent the heating temperature from exceeding 300°C.

[0031] In another embodiment, the inner diameter of the liquid adding hole heads of the first liquid adding arm and the second liquid adding arm is shrunk to only 0.5-1 mm, which can effectively prevent the residual liquid of the reagent from hanging on the liquid adding hole heads and affecting the amount of reagent added.

[0032] In another embodiment, the head of the second liquid-adding arm is provided with 6 liquid-adding holes, which are evenly distributed on the circumference and are separated by a certain distance to avoid mixing of reagents.

[0033] In any of the above embodiments, an adjacent color sensor and a light source are provided in the vertical direction of the fixed end of the second liquid-adding arm, wherein the light source emits light to the sample tube to be tested as the liquid-adding arm rotates, and the color sensor receives the light reflected or scattered in the sample tube, thereby completing the color detection.

[0034] In a specific embodiment, when the color sensor detects that there is no change in the light source, it predicts that no sample tube is placed in the socket, and feeds back the detection signal to the automatic controller, the software program instructs the sample tube turntable to rotate directly, skips the detection position, and stops the liquid adding arm for titration, wherein the software program is the fully automatic chemical oxygen demand (COD) analyzer analysis software system V1.0 software, and its copyright number is software registration number 2020SR0537238.

[0035] In a specific embodiment, a camera is provided at the center of the liquid adding end of the second liquid adding arm. The camera rotates with the liquid adding arm and can capture the entire process of liquid adding and titration. The video can be displayed on an electronic screen or computer for observation or retrospection.

[0036] In any of the above embodiments, the sample tube turntable can rotate horizontally under the control of the automatic controller, and simultaneously cooperate with the rotation angle of the rotating end of the second liquid adding arm to speed up the sample adding process of the second liquid adding arm.

[0037] In any of the above embodiments, the digestion tube adopts a serpentine inner tube to ensure sufficient condensation and reflux during the heating digestion process.

[0038] In any of the above embodiments, the automatic controller is a computer or a mobile phone, which is connected to the device via WIFI or Bluetooth, and according to the preset program software, the digestion and titration process can be monitored in real time or remotely.

[0039] In a specific embodiment, the program software is the fully automatic chemical oxygen demand (COD) analyzer analysis software system V1.0 software, and its copyright number is software registration number 2020SR0537238.

[0040] In any of the above embodiments, the outer box body is provided with an upper door and a lower door, wherein the panel of the upper door is inlaid with an electronic display screen and is provided with a large-area plexiglass observation window; the lower door is used to open and close the chiller and the storage room; and a drawer for storing reagents or test tools is provided between the upper door and the lower door.

[0041] In any of the above embodiments, the exhaust duct on the upper part of the box and the top exhaust fan can be connected to an external exhaust system. The air duct design adopts a side cooling fan to blow air from the outside to the inside and exhaust air from the top, so that harmful gases enter the exhaust system from the top and are discharged from the laboratory.

[0042] In any of the above embodiments, the box is a floor-standing device, and a roller with a fixing plate is provided at the bottom, which can facilitate fixing work and moving and pushing;

[0043] In any of the above embodiments, the front of the box is also provided with a water chiller storage room, a water storage barrel storage room, a digestion solution storage room, a catalyst storage room, a waste liquid storage room, a titration solution storage room, etc., which can be used to place various containers and are connected to the condenser and the sample tube through pipelines; a reagent tube holder is provided on the side. In a specific embodiment, a liquid level sensor or an overflow sensor is provided on the container to control the water level of the container and prevent overflow or vacancy.

[0044] In any of the above embodiments, the box body is provided with a heating zone protection plate in the direction of the heating module facing the operator.

[0045] In any of the above embodiments, the analyzer is an analyzer suitable for the HJ828-2017 standard.

[0046] Technical Effects

[0047] 1. The present invention strictly follows the requirements of HJ828-2017. In order to achieve the slow addition of the low-boiling-point reagent (silver sulfate-sulfuric acid solution) from the upper end of the condenser and the slow addition of the digester from the upper end of the burette (i.e., the sample tube or sample bottle), the present invention uses a linear module to close and separate the three modules (condensation module, addition module, sample tube module), so that the heating module can be separated from the sample cup / sample bottle / sample tube as soon as possible to stop heating, while ensuring that the upper end of the sample tube is not too far away from the condenser, thus overcoming the disadvantage that the heating module and the sample tube module are directly separated from the condenser and the sample splashes.

[0048] 2. The present invention improves the fixing method of the second liquid adding arm, that is, it is arranged outside the edge of the sample tube turntable, so that it will not hinder the condenser disc from docking downward with the sample tube turntable.

[0049] 3. The present invention improves the liquid adding port of the first liquid adding arm, and adopts multiple liquid adding ports, which are matched with two or more circles of condensing tubes, so as to realize the simultaneous addition of samples to two or more circles of condensing tubes, thereby improving the addition efficiency.

[0050] 4. In order to add samples to sample cups / sample bottles / sample tubes / burettes / titration bottles arranged in two or more circles at the same time, the present invention improves the liquid adding method of the second liquid adding arm, that is, through the swing arm angle of the second liquid adding arm and the inner and outer circle radius difference between the inner and outer circles of the sample tube, and in conjunction with the rotation of the sample tube turntable, the liquid adding process such as titration of two or more circles of sample tubes / sample bottles can be achieved by one liquid adding hole.

[0051] 5. The sample tube of the present invention can rotate but cannot be raised or lowered vertically, while the condenser disc and the heating module cannot rotate but can be raised or lowered vertically. The automatic controller controls the moving position of the sample tube to correspond vertically to the condenser tube and the heating hole. This ensures that each group of condensers, sample tubes, and accelerating holes are in the same straight line direction, and only the condenser tube and the heating module are moved at the same time, thus avoiding defects such as liquid splashing or missing caused by the movement of the sample tube, conforming to the operating specifications of the HJ828 standard, and facilitating the rapid cooling of the liquid in the sample tube.

[0052] 6. The present invention sets 6 liquid adding holes on the liquid adding head of the second liquid adding arm. The inside of these 6 liquid adding holes is a capillary tube, which is evenly distributed on the circumference and is separated by a certain distance to avoid mixing of reagents. This design avoids the situation that the diameter of the liquid adding hole is too large, and the high-temperature liquid is easily splashed by the large-diameter liquid when adding the titrant. At the same time, the dispersed capillary design can add high-speed liquid, thereby ensuring the sample addition speed.

[0053] 7. The single heating hole and heating block in the heating module of the present invention have a heating speed much faster than that of the entire heating block due to the small size of the heating block.

[0054] 8. The present invention provides an independent PCB board at the bottom of each heating block to control the heating block, and the heating block can be heated independently under the action of an automatic controller.

[0055] 9. The present invention can also be provided with several areas at the bottom of the entire heating module, and several independent PCB small boards under the large PCB boards can be connected to the large PCB board to control different areas of the heating block, so as to achieve individual heating of the heating block, or heating of the sub-areas, or even heating of the whole. This is very beneficial when the sample quantity is small and it is not necessary to heat all the sample positions.

[0056] 10. The present invention provides a camera at the head of the second liquid adding arm. The camera rotates with the liquid adding arm and can shoot the entire process of liquid adding and titration. The video can be displayed on an electronic screen or a computer for observation or retrospection.

[0057] 11. The present invention is provided with a color sensor and a light source at the fixed end of the second liquid adding arm, and cooperates with the self-developed analysis software system V1.0 software (copyright number is software registration number 2020SR0537238), so as to realize the monitoring of empty or blank liquid of sample tubes and burettes, that is, empty position recognition and empty cup recognition functions, to prevent the erroneous operation of adding reagents when the sample cup is not placed or the test reagents and catalysts are not placed in the sample cup.

[0058] 12. In the COD measuring instrument of the present invention, the reagent container is equipped with a waste liquid overflow sensor and a pure water liquid level sensor, so it has a liquid level detection function to prevent the liquid level from being too low or overflowing.

[0059] 13. The COD measuring instrument of the present invention does not need to transfer the sample during the test process, and the sample is always in one sample cup. The valves and pipelines are also avoided from being shared, and different channels use independent pipelines and valves.

[0060] 14. The two or more circles of sample positions used in the present invention, in combination with corresponding condensers and heating holes, can measure a large number of samples with high throughput in a limited space.

[0061] 15. The COD measuring instrument of the present invention is a closed box with an exhaust pipe and a top exhaust fan on the upper part, which can be easily connected to the customer's exhaust system. The side cooling fan is used in the air duct design to blow air from the outside to the inside and exhaust air from the top, so as to collect harmful gases generated in the experiment as much as possible, and enter the exhaust system from the top and be discharged out of the laboratory along with the exhaust system.

[0062] 16. In order to ensure sufficient condensation and reflux during the heating digestion process, the digestion tube of the present invention adopts a serpentine inner tube.

[0063] 17. The COD measuring instrument of the present invention is a floor-standing design, which does not need to occupy a laboratory bench and can be easily moved by only pushing it during transportation.

[0064] 18. The panel of the outer box of the COD measuring instrument of the present invention is inlaid with an electronic screen, which can display the progress of the experiment and other information you want to know, such as the image displayed by the titration arm camera. A large-area organic glass observation window is provided on the box, and the experimental process can also be directly observed. It also has a video storage and viewing function.

[0065] 19. The COD measuring instrument of the present invention can be connected to WIFI, or connected to a computer or mobile phone via Bluetooth, so as to realize remote monitoring of the experimental status.

[0066] 20. The COD measuring instrument of the present invention is fully automated and can work unattended. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Figure 1 : Schematic diagram of a COD analyzer including a sample tube digestion and titration device.

[0068] Figure 2 : Structural diagram of the sample tube digestion and titration device and the first liquid adding arm, wherein the second liquid adding arm is not shown.

[0069] Figure 3 : Stereoscopic view of the second liquid adding arm.

[0070] Figure 4 : Test picture of sample tube module.

[0071] Figure 5 : Top view of the sample tube module.

[0072] Figure 6 : Diagram of the internal structure of the heating module.

[0073] legend:

[0074] 1. Top exhaust fan, 2. Upper door, 3. Observation window, 4. Condenser, 5. Condensation module, 6. Linear module, 7. Sample tube or sample cup, 8. Sample tube turntable, 9. Heating zone protection plate, 10. Lower door, 11. Drawer, 12. Chiller, 13. Water storage bucket, 14. First liquid adding arm, 15. Electronic screen, 16. Second liquid adding arm, 17. Reagent connector, 18. Side cooling fan air inlet, 19. Reagent rack, 20. Coupling, 21. Upper lead screw, 22. Lower slider, 23. Upper and lower fixed blocks (23.1 is the upper fixed block, 23.2 is the lower fixed block), 24. Upper slider, 25. Lower lead screw, 26 Heating module (in order to effectively keep warm, the outer shell of heating module 26 is a heat insulation cover), 27. Camera (with 6 liquid adding holes distributed around it), 28.1 The first liquid adding head of the first liquid adding arm, 28.2 The second liquid adding head of the first liquid adding arm, 29. A single PCB board, 30. A whole PCB board, 31. Heating holes, 32. Heating zone protection plate, 33. Stepper motor. DETAILED DESCRIPTION

[0075] The following embodiments can enable those skilled in the art to more fully understand the present invention, but the present invention is not limited to the scope of the embodiments.

[0076] like Figure 1-2 A device for digestion and titration of a sample tube for COD determination is shown, comprising a condensation module (5), a heating module (26), a sample tube module, a stepping motor (33), and a linear module (6), wherein:

[0077] The condensation module (5) comprises a condenser disc, a condensation water pipeline (not shown), and a cold water container (not shown), wherein the surface of the condenser disc is provided with two or more circles of condenser (4) insertion holes; the condenser (4) is provided with a water inlet at the upper end and a water outlet at the lower end, and is connected to a chiller (12) through a condensation water pipeline, thereby forming a cooling circuit (not shown);

[0078] The sample tube module comprises a sample tube turntable (8), the surface of which is provided with two or more circles of sample tube (7) insertion holes, and each sample tube (7) insertion hole vertically corresponds to the insertion hole of the condenser tube disk;

[0079] The heating module (26) is a disk with a diameter slightly larger than or equal to that of the sample tube turntable (8), and is provided with two or more circles of hole-shaped heating holes (31) on its surface;

[0080] The linear module (6) comprises a coupling (20), an upper slider (24), a lower slider (22), an upper lead screw (21), and a lower lead screw (25), wherein the upper slider (24) is fixed to the condensation module (5), and the lower slider (22) is fixed to the heating module (26). The coupling (20) is arranged in the middle of the upper and lower lead screws of the condensation tube disc and the sample tube turntable (8). The upper lead screw (21) and the lower lead screw (25) pass through the upper slider (24) and the lower slider (22) respectively and are connected through the coupling (20). Due to the different rotation directions of the upper and lower lead screws, when the stepping motor (33) connected to the shaft end of the upper end of the upper lead screw rotates, the upper and lower lead screws respectively drive the upper and lower sliders to move towards or in the opposite direction, thereby driving the condensation module (5) and the heating module (26) to simultaneously vertically approach or separate the sample tube (7);

[0081] The fixed end of the first liquid adding arm (14) is connected to the center of the condenser disc, and two or more liquid adding holes are provided on the extended arm. When the first liquid adding arm (14) rotates around the center, the two or more liquid adding holes can pass directly above the openings of each condenser (4); a hollow pipeline is provided inside the first liquid adding arm (14), and the pipeline is connected to the catalyst container;

[0082] The fixed end of the second liquid adding arm (16) is connected to the outer side of the edge of the sample tube turntable (8) (not shown).

[0083] in, Figure 1 The display linear module (6) starts to operate, driving the condensation module (5) to move downward and the heating module (26) to move upward, until the condensation module (5) and the heating module (26) have moved close to the sample tube turntable (8) and reached the limit position; Figure 2 The linear module (6) shown drives the heating module (26) and the condensation module (5) to separate from the sample tube turntable (8) through a bidirectional screw structure.

[0084] Figure 3 As shown, a camera (27) is provided at the center of the head of the second liquid adding arm (16). The camera (27) rotates with the liquid adding arm and can shoot the entire process of liquid adding and titration. The video can be displayed on an electronic screen (15) or a computer or a mobile phone for observation or review. Six liquid adding holes are provided around the camera (27), which are evenly distributed on the circumference and are all separated by a certain distance to avoid mixing of reagents.

[0085] Figure 4 The fixed end of the first liquid-adding arm (14) is connected to the center of the condenser disc, and two liquid-adding holes are provided on the extending arm, namely the first liquid-adding hole (28.1) and the second liquid-adding hole (28.2). When the first liquid-adding arm (14) rotates around the center, the two liquid-adding holes can pass directly above each condenser tube opening; a hollow pipeline is provided inside the first liquid-adding arm (14), and the pipeline is connected to the catalyst container (not shown).

[0086] Figure 5 The fixed end of the second liquid adding arm (16) is connected to the outer side of the edge of the sample turntable, and the rotating end thereof uses different rotation angles to add liquid to each sample tube (7) on the two or more circles of the plug hole. The sample tube turntable (8) can be horizontally rotated under the control of the automatic controller, and at the same time cooperates with the rotation angle of the rotating end of the second liquid adding arm (16) to speed up the sample adding process of the second liquid adding arm (16).

[0087] Figure 6 It is a heating module (26) with an open upper cover. Each heating block (not shown) in the heating module (26) is connected in parallel, and an automatic controller is used to control the heating blocks of a single or multiple heating holes (31) to heat the contained sample tube (7). In a specific embodiment, an independent PCB board (29) is provided under each heating block for control. The bottom of the heating module (26) is divided into several areas, each of which is provided with several whole PCB boards (30), so that each independent PCB board (29) is integrated into the whole PCB board (30), and regional or overall heating of all heating blocks is achieved. In order to prevent high temperature from affecting the operator and internal heat from radiating outward to cause uneven heating, a heating zone protection plate (32) is also provided on the outer edge of the heating module. The heating block is a ceramic heating block or a ceramic heating plate, and is provided with a temperature switch to prevent the heating temperature from exceeding 300°C.

[0088] The method of using the device of the present invention is as follows:

[0089] In the determination of chemical oxygen demand, the tester prepares the reagents and pure water used in the experiment, and sets the corresponding parameters through a computer connected to the instrument. Before starting the experiment, pure water can be drawn to flush the condenser tube (4) through the first liquid adding arm (14).

[0090] like Figure 1As shown, the tester places the sample to be tested on the sample position of the sample tube turntable (8), clicks to start the test, and the second liquid adding arm (16) rotates to a fixed liquid adding position, wherein the liquid adding positions of the inner circle and the outer circle sample tubes (7) are two different fixed positions; the sample tube turntable (8) rotates to turn the sample tubes (7) to the fixed liquid adding positions in turn, and the second liquid adding arm (16) adds digestion agents (such as potassium dichromate and mercuric sulfate) in the sample cup in turn, and the magnetic stirring device (not shown) rotates continuously during the addition. After all samples have been added, the second liquid adding arm (16) is reset, and the linear module (6) starts to operate to drive the condensation module (5) to move downward and the heating module (26) to move upward, until the condensation module (5) and the heating module (26) have moved close to the sample tube turntable (8) and reached the limit position, the condensation tube (4) and the upper part of the sample tube (7) are embedded one by one, and the heating holes (31) on the heating block are embedded one by one with the bottom of the sample tube (7), and the first liquid adding arm (14) rotates to each sample position in turn to add catalyst (such as sulfuric acid-silver sulfate). After all sample cups have been added, the instrument starts heating and digestion. During the whole process, the outer tube of the condensation tube (4) is connected to the chiller (12) for condensation and reflux to ensure that the liquid vaporized by heat is condensed and refluxed to the sample cup.

[0091] like Figure 2 As shown, after the heating digestion reaches the specified time, the heating block stops heating, the linear module (6) drives the condensation module (5) upward and the heating module (26) downward to move a short stroke, the bottom of the sample cup is separated from the heating block, and the sample cup and the condenser tube (4) are no longer tightly fitted. At this time, the side cooling fan (18) starts to work, and the first liquid adding arm (14) rotates again to add pure water to each sample position. After the pure water is added, the linear module (6) continues to work until the condensation module (5) rises to the upper limit and the heating module (26) drops to the lower limit. The sample tube turntable (8) starts to rotate, and the magnetic stirring device continues to rotate to promote the cooling of the sample as soon as possible.

[0092] The second liquid adding arm (16) rotates again to a fixed liquid adding position, wherein the liquid adding positions of the inner circle and the outer circle are two different fixed positions respectively, and the sample tube turntable (8) turns the sample to the fixed liquid adding position in turn for titration.

[0093] After the test is completed, the sample tube turntable (8) is reset, the linear module (6) works again, the condenser (4) and the sample cup are engaged again, and the first liquid adding arm (14) adds pure water to each sample position in turn to clean the condenser (4) and dilute the sample.

[0094] The linear module (6) works again, and the condenser tube (4) rises to the upper limit position, and the sample cup can be taken out for cleaning.

[0095] The above describes the specific embodiments of the invention. It should be understood that the invention is not limited to the above specific embodiments, and the devices and structures not described in detail should be understood to be implemented in a common manner in the art; those skilled in the art can make various modifications or modifications within the scope of the claims, and make some simple deductions, deformations or substitutions, which does not affect the essence of the invention.

Claims

1. A fully automatic chemical oxygen demand analyzer, comprising a condensation module, a heating module, a sample tube module, a linear module, a stepper motor, an outer box, a color sensor, a light source, and an automatic controller, wherein: (1) The condensation module includes a condenser disc, a condensing water pipeline, and a cold water container, wherein the surface of the condenser disc is provided with two or more circles of condenser plug holes; the condenser is provided with a water inlet at the upper end and a water outlet at the lower end, which are connected to the chiller through the condensing water pipeline, thereby forming a cooling circuit; (2) The sample tube module includes a sample tube turntable, the surface of which is provided with two or more circles of sample tube insertion holes, and each sample tube insertion hole vertically corresponds to the insertion hole of the condenser tube disk; (3) The heating module is a disk with a diameter slightly larger than or equal to that of the sample tube turntable, and has two or more circles of hole-shaped heating holes on its surface, each of which is provided with a heating block, wherein each heating hole vertically corresponds to each sample tube insertion hole to accommodate the sample tube; wherein, Each heating block in the heating module is connected in parallel, and an automatic controller is used to control a single or multiple heating holes to heat the sample tubes contained therein, and an independent PCB small board is provided under each heating block to control heating; and / or, the bottom of the heating module is divided into several areas, each of which is provided with several whole PCB boards, so that each independent PCB lower board is integrated into the whole PCB board, and regional or overall heating of all heating blocks is achieved; wherein, in order to prevent high temperature from affecting the operator and internal heat from radiating outwards to cause uneven heating, a heating zone protection plate is also provided on the outer edge of the heating module; (4) The linear module includes a coupling, an upper slider, a lower slider, an upper lead screw, and a lower lead screw, wherein the upper slider is fixed to the condensation module, the lower slider is fixed to the heating module, the coupling is arranged in the middle of the condensation tube disc and the sample tube turntable, the upper lead screw and the lower lead screw respectively pass through the upper slider and the lower slider and are connected by the coupling, and since the upper and lower lead screws have different rotation directions, when the stepper motor connected to the shaft end of the upper end of the upper lead screw rotates, the upper and lower lead screws respectively drive the upper and lower sliders to move toward or in the opposite direction, thereby driving the condensation module and the heating module to vertically approach or separate the sample tube at the same time; (5) The fixed end of the first liquid adding arm is connected to the center of the condenser disc, and two or more liquid adding holes are provided on the extending arm. When the first liquid adding arm rotates about the center, the two or more liquid adding holes can pass directly above each condenser tube opening; a hollow pipeline is provided inside the first liquid adding arm, and the pipeline is connected to the catalyst container; (6) The fixed end of the second liquid-adding arm is connected to the outer side of the edge of the sample turntable. The head of the liquid-adding arm is provided with 6 liquid-adding holes, which are evenly distributed on the circumference and are all separated by a certain distance to avoid mixing of reagents; the rotating end thereof uses different rotation angles to add liquid to each sample tube on two or more circles of the sockets, wherein the swing arm angle of the second liquid-adding arm and the inner and outer circle radius difference between the inner and outer circles of the sample tube, combined with the rotation of the sample tube turntable, thereby realizing a second liquid-adding arm titrating and adding liquid to two or more circles of sample tubes / sample bottles; The inner diameter of the liquid adding hole heads of the first liquid adding arm and the second liquid adding arm is reduced to only 0.5-1 mm, which can effectively prevent the residual liquid of the reagent from hanging on the liquid adding hole heads and affecting the amount of reagent added; and / or, A camera is provided at the center of the liquid adding end of the second liquid adding arm. The camera rotates with the liquid adding arm and can shoot the whole process of liquid adding and titration. The video can be displayed on an electronic screen or a computer for observation or retrospection; and / or, An adjacent color sensor and a light source are arranged in the vertical direction of the fixed end of the second liquid adding arm, wherein the light source emits light to the sample tube to be tested as the liquid adding arm rotates, and the color sensor receives the light reflected or scattered in the sample tube, thus completing the color detection; (7) The outer box is a closed box with an exhaust pipe and a top exhaust fan on the top, which can exhaust the harmful gases generated during digestion by top exhaust; (8) A color sensor and a light source are provided in the vertical direction of the fixed end of the second liquid-adding arm, wherein the light source emits light to the sample tube to be tested as the liquid-adding arm rotates, and the color sensor receives the light reflected or scattered in the sample tube, thereby completing the color detection.

2. The analyzer according to claim 1, wherein: The outer box body is provided with an upper door and a lower door, wherein the panel of the upper door is inlaid with an electronic display screen and is provided with a large-area organic glass observation window; the lower door is used to open and close the chiller and the storage room; a drawer for storing reagents or test tools is provided between the upper door and the lower door.

3. The analyzer according to claim 2, wherein the exhaust pipe on the upper part of the box and the top exhaust fan can be connected to an external exhaust system, and the air duct design adopts a side cooling fan to blow air from the outside to the inside and exhaust air from the top, so that harmful gases enter the exhaust system from the top and are discharged from the laboratory; the box is a floor-standing device, and a roller with a fixing plate is provided at the bottom, which can be convenient for fixing and moving; and / or, the front of the box is also provided with a chiller storage room, a water bucket storage room, a digestion solution storage room, a catalyst storage room, a waste liquid storage room, a titration solution storage room, etc., which can place various containers and are connected to the condenser and sample tube through pipelines; a reagent tube holder is provided on the side.

4. The analyzer according to claim 3, wherein the container is provided with a liquid level sensor or an overflow sensor to control the water level of the container and prevent overflow or emptiness.

5. The analyzer according to claim 4, wherein when the color sensor detects that there is no change in the light source, it predicts that no sample tube is placed in the jack, and feeds back the detection signal to the automatic controller, and the software program instructs the sample tube turntable to rotate directly, skips the detection position, and stops the liquid adding arm for titration, wherein the software program is the fully automatic chemical oxygen demand (COD) analyzer analysis software system V1.0 software, and its copyright number is software registration number 2020SR0537238.

6. The analyzer according to claim 5, wherein the sample tube turntable can rotate horizontally under the control of the automatic controller, and cooperate with the rotation angle of the rotating end of the second liquid adding arm to speed up the sample adding process of the second liquid adding arm.

7. The analyzer according to claim 5 or 6, wherein the automatic controller is a computer or a mobile phone, connected to the device via WIFI or Bluetooth, and according to a preset program software, real-time monitoring or remote monitoring of the digestion and titration process is achieved; and / or, the analyzer is a device applicable to the HJ828-2017 standard.

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