CN112129959A

CN112129959A - Full-automatic chemical oxygen demand analyzer based on different liquid transfer flow paths

Info

Publication number: CN112129959A
Application number: CN202011021364.XA
Authority: CN
Inventors: 刘盼西; 刘丰奎; 郝俊; 刘向东; 赵东; 牛军; 王美彩
Original assignee: Shanghai Anjie Environmental Protection Science & Technology Co ltd
Current assignee: Shanghai Anjie Zhichuang Technology Co ltd
Priority date: 2020-09-25
Filing date: 2020-09-25
Publication date: 2020-12-25
Anticipated expiration: 2040-09-25
Also published as: CN113311177B; CN113311177A; CN112129959B

Abstract

The invention provides a full-automatic chemical oxygen demand analyzer based on different liquid transfer flow paths, which comprises a sample digestion reflux flow path, a reagent adding flow path, and a sample loading washing flow path, a digestion reflux washing flow path, a titration cell washing flow path and a reagent adding washing flow path which can be selected. The full-automatic chemical oxygen demand analyzer can ensure that sewage with high impurity content and reaction solution respectively and smoothly enter a target pipeline under the control of a computer or an automatic controller, realize the effect of accurate quantitative sample adding by matching with an injection pump, clean the pipeline in time and recycle a digestion solution sample to be measured. On the basis, the analyzer also comprises an online automatic cooling module, wherein the module introduces a spiral reaction coil, combines the design concept of a cylindrical cooling conductor and a controllable semiconductor cooling fin connected with the tail end, has the effect of rapid heat dissipation, and can realize online automatic analysis.

Description

Full-automatic chemical oxygen demand analyzer based on different liquid transfer flow paths

Technical Field

The invention relates to a Chemical Oxygen Demand (COD) tester in the field of environmental protection detection, in particular to a full-automatic COD analyzer for realizing liquid transfer analysis based on a flow path system, belonging to the field of analytical chemistry detection.

Background

Chemical-Oxygen-Demand (COD), which is abbreviated as COD, refers to the mass concentration of Oxygen in mg/L corresponding to the dissolved substances in water and the potassium dichromate which is a strong oxidant consumed by suspended substances under certain conditions. It is a comprehensive index for representing the reductive substances in the water body. The COD in the water body is too high, which indicates that the organic pollution is serious, and the balance of the environment and the biological community is damaged, so that the water body is deteriorated. Therefore, COD is an important parameter of sewage treatment plants and an important index for environmental monitoring.

The traditional chemical oxygen demand is divided into a permanganate method (also called permanganate index) and a potassium dichromate method according to different oxidation reagents, corresponding national standards are correspondingly established, the current national standard corresponding to the permanganate index is GB11892-1989 determination of water quality permanganate index, the current national standard for determining the chemical oxygen demand by the potassium dichromate method is HJ828-2017 determination of water quality chemical oxygen demand, the whole course of the current determination scheme of the standard method is manual determination, a user is required to be provided with a reflux device, a heating device, an acid burette and the like (detailed on pages 3-4 of the standard), manual operation equipment is required to be provided for manual reagent addition, high-temperature reflux digestion, manual color final drip infusion and the like according to standard requirements (detailed on page 45 of the standard), the process operation is complicated, the risk of chemical reagent damage to experimenters is high (clear warning on the first page of the standard: mercury sulfate used in the method is extremely toxic, the experimenter should avoid direct contact therewith. The sample pretreatment process should be carried out in a fume hood), the experimental result is easily influenced by the subjective level of operators, and the like.

According to the requirements of the above standards, semi-automatic instruments and devices for solving part of the work of users appear in the market, such as the chinese invention application CN201810059775.4, "a laboratory COD automatic analysis robot", which discloses the use of an automatic mechanical device to realize the automatic analysis of the whole process of adding a sample into a digestion reflux and color titration, and meets the application requirements of full automation. However, according to the mechanical anthropomorphic scheme adopted by the scheme, a plurality of mechanical control parts such as a plurality of mechanical clamping jaw groups and a plurality of sets of movable liquid adding arms are adopted, and in the actual production and application process, the defects of high mechanical structure design difficulty and complete machine fault rate, high production and assembly difficulty, low complete machine reliability and the like exist; and the glass magic mouth in the scheme is transferred and matched, so that data deviation caused by loose matching and component damage caused by collision in the matching process are easily caused.

Unlike the research direction of designing an automated mechanical apparatus to perform analytical measurement of COD, other research directions have emerged in recent years. For example, chinese patent application CN200810062267.8, entitled "a water quality on-line monitoring method and system" discloses a monitoring device including a pump, a liquid storage unit, a reaction-detection unit, and a multi-channel direction selection valve, wherein the liquid storage unit is a liquid storage ring of an annular pipeline, one end of which is communicated with an injection pump or a plunger pump, and the other end is communicated with the multi-channel direction selection valve. The direction selecting valve has several sample feeding channels communicated with the liquid to be detected, the reaction reagent and the cleaning liquid separately and also has analysis channel leading to the reaction-detection chamber via solenoid valve. When the selection valve is adjusted to a certain sampling channel, the injection pump pumps the solution to be detected, the reaction reagent and the like into the liquid storage ring, and when the selection valve is adjusted to the analysis channel, the injection pump drives the solution into the reaction-detection chamber through the analysis channel and the electromagnetic valve to finish reaction and analysis detection. After the detection is finished, the injection pump pumps the waste liquid back to the liquid storage ring and moves the waste liquid into the waste liquid pool through the waste discharge channel of the direction selection valve. Although the invention can realize that different reagent solutions respectively pass through the sample feeding channel and enter and exit the reaction-detection device through the multi-channel direction selecting valve, avoids the arrangement of excessive mechanical devices and has better practicability, the invention has the following defects: the device is lack of a special digestion device, a liquid storage ring is additionally arranged as the digestion device, a water sample to be detected and a reaction reagent are mixed and stored in the liquid storage ring in advance, and the water sample is easy to react in the liquid storage ring instead of a reaction chamber in advance to generate harmful gas and heat and is difficult to control; the reaction reagent solution additionally remains in the liquid storage ring, which brings inconvenience to the cleaning process; the device does not set up titration outfit and can't accurate judgement reaction terminal point, has consequently influenced actual detection effect. In addition, the applicable standard of the invention is based on the HJT 399-2007 water quality chemical oxygen demand determination rapid digestion spectrophotometry, high-pressure high-temperature rapid digestion is adopted, only the absorption, reagent addition, titration analysis and the like of a single sample can be completed, and the large-batch multi-channel circulation rapid analysis in a laboratory cannot be realized.

Chinese patent application CN201110204582.1, entitled COD full-automatic on-line monitoring system and monitoring method thereof, discloses a monitoring device comprising an electric injector, an optical quantitative device, a multi-way adapter and a reaction tank. In the operation process, the electric injector is used for pumping air to enable the optical quantitative device to generate negative pressure, so that the measuring liquid and various reaction reagents are driven to enter the optical quantitative device through a sample introduction channel of the multi-way adapter, then gas is pressed in through the electric injector, and the liquid in the optical quantitative device enters the reaction cell one by one to carry out digestion reaction. In the reaction process, a detection electrode arranged in the reaction cell monitors the current change value of the solution in real time, so that the reaction end point is determined. After the reaction is finished, the electric injector is used for pumping air again, so that the waste liquid flows to the waste liquid pool through the multi-way adapter and the waste liquid flow path. Although the invention is simpler, the defects are as follows: an optical quantitative device similar to a buffer pool needs to be additionally arranged, and if all reaction solutions are contained at one time, digestion reaction is caused in advance, harmful gas and heat are generated, and the control is difficult; if the reaction solution is added and transferred one by one, excessive residue of the reaction solution is caused; the invention utilizes the change value of the monitoring current signal in the reaction tank, which is completely different from the prior titration tank device, thereby being not beneficial to the improvement and the application of the prior COD detector; in addition, the method adopts a potentiometric titration method for determination, and has substantial difference with the detection standard of the invention, wherein the high-pressure high-temperature rapid digestion is adopted, so that only the absorption, reagent addition, titration analysis and the like of a single sample can be completed, and the large-batch multichannel circulation rapid analysis in a laboratory cannot be realized.

The invention discloses a device capable of automatically fixing the volume of solution and reducing the accumulated error of liquid taking, and the invention is characterized in that the invention combines the laser triangulation distance measuring principle with the linear stepping motor positioning and horizontal moving rod technology to realize high-precision, flexible, random and continuous constant volume liquid taking, thereby ensuring the precision of the liquid volume measurement, changing the defect of the traditional mechanical fixed volume liquid taking and having higher effect. The Chinese patent application CN201521028392.9, the invention name "chemical oxygen demand detector" discloses a detector which comprises a sampling pump, a multi-way valve, a high-temperature high-pressure digestion chamber and a controller. Compared with the existing measuring instrument, the improved measuring instrument is characterized in that a high-pressure electromagnetic valve is arranged in the multi-way valve and the digestion chamber, and a liquid flow path can be opened and closed according to computer instructions so as to prevent high-pressure gas from impacting the multi-way valve. In addition, a high-pressure electromagnetic valve is also arranged at a waste liquid outlet at the bottom of the digestion chamber, so that the waste liquid can be automatically discharged conveniently.

As the closest prior art, Chinese patent application CN201810957798.7, "multi-parameter water quality detector and use method" discloses a water quality tester comprising a peristaltic pump, a plurality of digesters and a multi-way electromagnetic valve, wherein the peristaltic pump is connected with a quantitative ring tube. Since the volume of the quantitative loop is a predetermined volume, quantitative extraction and quantitative sampling of a liquid in a target container selected at will can be performed. Under the regulation and control of a programmable controller, the device enables various standards and reagents to enter a quantitative ring pipe through a multi-way electromagnetic valve and enter a digestion device for reaction under the drive of a peristaltic pump. If too much mixed reaction solution enters the quantitative loop, the mixed reaction solution is discharged from a waste liquid outlet of the electromagnetic valve V1 before entering the digester under the control of the controller. After the reaction is finished, the waste liquid in the digester flows out from the bottom of the digester, and is discharged at a pipeline outlet V3 before entering the multi-way electromagnetic valve under the action of the peristaltic pump. The invention combines the technologies of quantitative ring pipes, multi-way electromagnetic valves, peristaltic pumps and programmable controllers, can realize bidirectional circulating flow of sample adding and unidirectional discharge of redundant solution and waste liquid, and has the advantages of simple and convenient operation, safety and reliability. Although the invention can select target solution to be detected from a plurality of digesters for detection, the defects are as follows: (1) when the liquid in the target container is driven into the dosing loop LC, a photosensor G1 located downstream of the dosing loop provides a feedback signal to the programmable controller after detecting the presence of the target liquid in the second connecting tube L2 at the outlet end of the loop. The controller instructs the liquid to be transferred into the digester according to the preset time. The dosage mode is characterized in that the solution amount transferred into the digestion device is calculated according to time and flow speed rather than accurate volume, and metering errors are caused easily due to factors such as pipeline blockage, time delay and overlong flow path; (2) after digestion is completed in the digestion device, the light is emitted to the light receiving unit by the emitting light source through the liquid in the digestion tube, and after the light receiving unit receives the photoelectric signal, the measured value of the water sample to be measured is obtained through the programmable controller, so that the titration metering process of the digestion solution is lacked; (3) the invention utilizes the flow path design of a single power source, a peristaltic pump and a quantitative ring tube, and has great limitation when a multi-channel switching valve is switched to quantitatively sample a reagent, so that the reagent can only be accurately quantified according to the volume of the quantitative ring tube, or the quantitative ring can only be used as a volume pipeline, for example, the reagent is pre-pumped into the quantitative ring (incomplete filling and inaccurate quantification) and then reversely pushed into a reaction container on the right side. Because of the quantitative mode, the quantitative volume is fixed every time, if the quantitative volume is adjusted, the quantitative ring can only be used as a container for quantitative determination, and the quantitative ring can only depend on the rotation speed and time of the peristaltic pump for quantitative determination. Therefore, the system limits the reagent taking amount, and also limits the condition that the reagent cannot be accurately quantitatively added, so that the precision is greatly reduced, and the accurate quantification capability is lost. (4) Aiming at the sewage as a detection object, as the water sample contains more particles, silt and other substances which can damage the injection pump, the injection pump and the peristaltic pump can not be introduced to carry out combination so as to realize the accurate quantitative capability. .

In view of the above disadvantages of the prior art, the present invention is still suitable for detecting COD in a water sample according to the standard of "determination of chemical oxygen demand for water quality by fast digestion spectrophotometry" of HJT 399-2007. Moreover, the prior art chemical oxygen demand analyzer lacks an on-line rapid cooling means for rapid, controlled and accurate cooling of the solution to be titrated. Meanwhile, an in-situ digestion component is also lacked, so that the digestion bottle can be leached and transferred in real time without being disassembled and transferred, the condenser pipe and the digestion bottle are thoroughly cleaned, and the minimum residue of the in-situ digestion system is realized.

Therefore, compared with the conventional COD (chemical oxygen demand) measuring instrument, the device can be firstly applied to the existing national standard GB11892-1989 determination of water quality permanganate index for determining chemical oxygen demand by using the potassium permanganate standard, the existing national standard HJ828-2017 determination of water quality chemical oxygen demand by using the potassium dichromate method, and the latest industrial standard HJ828-2017 determination of water quality chemical oxygen demand by using the dichromate method, and can be secondly applied to the polluted water sample to be measured with a large amount of impurities, and the measuring instrument can realize the online rapid transfer of the water sample to be measured and the addition of a reaction reagent, and has the effects of accurately quantifying sample addition and no pipeline blockage. And the analyzer can also realize the rapid cooling and transfer of the digestion solution, improve the automatic analysis efficiency of the whole machine, and realize the effects of in-situ transfer and automatic titration analysis of a liquid flow path. Finally, the measuring instrument has the advantages of simple structure and convenient operation, is beneficial to modularized production and assembly, reduces the production, assembly and maintenance cost, and replaces the existing high-precision titration device or is directly used for producing and measuring a detector for Chemical Oxygen Demand (COD).

Disclosure of Invention

The first invention principle of the invention is to provide a chemical oxygen demand tester which can be applied to the current national standard GB11892-1989 determination of water quality permanganate index for determining chemical oxygen demand by potassium permanganate standard, the current national standard HJ828-2017 determination of water quality chemical oxygen demand for determining chemical oxygen demand by potassium dichromate method, and the latest industry standard HJ828-2017 determination of water quality chemical oxygen demand by dichromate method, compared with the prior art, the tester redesigns a sample digestion reflux flow path, a titration reagent adding flow path and a washing flow path, thereby improving the connection relationship of liquid transfer pipelines among all parts, wherein: a plurality of multi-channel switching valves are introduced into a sewage sample and reagent solution transfer pipeline and a sample to be detected, a bidirectional peristaltic pump is used, and sewage and reaction solution with high impurity content smoothly enter a target pipeline respectively under the control of a computer or an automatic controller. Meanwhile, the effect of accurate quantitative sample adding is realized by matching with an injection pump. And various pure water washing pipeline designs are introduced, so that the pipeline can be cleaned in time and a digestion solution sample to be measured can be recycled.

On the basis of the second invention principle, an online automatic control cooling component is introduced, so that rapid cooling and transfer of digestion liquid are realized, and the automatic analysis efficiency of the whole machine is improved.

Therefore, the first object of the present invention is to provide a chemical oxygen demand measuring apparatus with automatic liquid transfer and accurate quantification, which comprises a sample digestion reflux flow path and a reagent adding flow path, and is characterized in that:

(1) the sample digestion reflux flow path comprises a sample injector, a first three-way valve, a two-way peristaltic pump, a second three-way valve, a quantitative ring, a second multi-channel switching valve, a digestion device, a cooling module, a titration cell and a liquid transfer pipeline for connecting all the parts, wherein the sample injector is connected with a first port of the first three-way valve through the liquid transfer pipeline and is sequentially connected with the two-way peristaltic pump, a first port of the second three-way valve, the quantitative ring and the second multi-channel switching valve through a second port of the first three-way valve to be communicated with the digestion device, a third port of the first three-way valve is sequentially connected with the cooling module and the titration cell through the liquid transfer pipeline, so that a sample to be tested is driven to be transferred into the digestion device from the sample injector, the quantitative ring and the second multi-channel switching valve through the two-way peristaltic pump, and can also flow back to the first three-, finally, the mixture enters a titration cell;

(2) the reagent adding flow path comprises an injection pump, a first multi-channel switching valve, a digestion reagent container, a display indicator container, a titration solution container and transfer pipelines for connecting all the parts, wherein the injection pump is connected with a common port of the first multi-channel switching valve, the display indicator container, the titration solution container and the digestion reagent container are respectively communicated with a plurality of distribution ports of the first multi-channel switching valve, so that the display indicator and the titration solution are added into a titration tank through respective distribution ports, digestion reagents (such as an oxidant, a catalyst, a masking agent and the like) are communicated with a third port of a second three-way valve, a quantitative ring and the second multi-channel switching valve through different distribution ports and finally communicated with a digestion device, and therefore, the injection pump enables the display indicator and the titration solution to enter the first multi-channel switching valve and accurately added into the titration tank through extracting and pushing the reagents, and enables the digestion reagents to sequentially enter the, A third port of the second three-way valve, a quantitative ring and a second multi-channel switching valve are accurately added into the digestion device finally;

in one embodiment, the multi-channel switching valve is comprised of a switching valve head, a line connector, a rotary power device, etc., wherein the switching valve head typically has one common port and a plurality of distribution ports to achieve a one-to-many switching mode; the pipeline connector is used for connecting an external pipeline with each port on the switching head; the rotating power device realizes the accurate connection of the public port and the distribution port by rotating the valve core inside the switching valve head under the instruction of a computer or an automatic controller. In a specific embodiment, the internal channels of the multi-channel switching valve are 6-16 channels, and the number of channels can be increased or decreased, so as to increase or decrease the types of the transferred reagents and liquids and correspondingly decrease or increase the transfer speed of the reagents and liquids. In another embodiment, the common port and the dispensing port can serve as both an inlet and an outlet for the reagents.

In another embodiment, after the peristaltic pump fills the dosing ring with the sample, the syringe pump precisely pumps and pushes the digestion reactant (e.g., oxidant, catalyst, masking agent, etc.) through the first multi-way switching valve, through the third port of the second three-way valve, into the dosing ring, and drives the digestion reactant and the sample together through the second multi-way switching valve into the digester. In other embodiments, wherein the syringe pump may precisely push air through the first multi-channel switching valve, the third port of the second three-way valve, the dosing ring, the second multi-channel switching valve after digestion reagents are added to the digester, such that the remaining liquid of the sample digestion reflux flow path is added to the digester.

In any of the above embodiments, wherein the chemical oxygen demand meter further comprises a wash flow path.

In one embodiment, the wash flow path comprises a sample loading wash flow path, a digestion reflux wash flow path, a titer cell wash flow path, a reagent addition wash flow path, wherein:

the method comprises the following steps that firstly, a sample adding and washing flow path comprises a sample adding device water purifier, a first three-way valve, a peristaltic pump, a second three-way valve, a quantitative ring, a second multi-channel switching valve and a liquid transfer pipeline between waste liquid pools, wherein the peristaltic pump drives pure water of the sample adding device to wash the flow path and discharge waste liquid to the waste liquid pools so as to prevent digestion liquid from being polluted in the process of flowing back to a titration cell, and/or the peristaltic pump pumps excessive samples into the quantitative ring and discharges the samples to the waste liquid pools through the second multi-channel switching valve;

a digestion reflux washing flow path, which comprises a syringe pump, a pure water container connected with a distribution port of the first multi-channel switching valve, a third multi-channel switching valve and a liquid transfer pipeline between the digestion devices, so that the syringe pump adds pure water into the digestion devices along the flow path for washing, and finally the peristaltic pump recovers and transfers the washed digestion liquid to a titration cell through the sample digestion reflux flow path;

a titration cell washing flow path, which comprises an injection pump, a pure water container connected with a distribution port of the first multi-channel switching valve, the first multi-channel switching valve and a liquid transfer pipeline between the titration cells, so that the injection pump adds pure water into the titration cell for washing, and finally the peristaltic pump transfers the waste liquid to the waste liquid pool through the sample digestion reflux flow path and the second multi-channel switching valve;

and the reagent adding and washing flow path comprises an injection pump, a pure water container connected with a distribution port of the first multi-channel switching valve, a liquid transfer pipeline between the first multi-channel switching valve and the waste liquid pool, so that after the injection pump injects pure water into the first multi-channel switching valve for washing, the waste liquid is transferred to the waste liquid pool through the first multi-channel switching valve. In a specific embodiment, the flow path further comprises liquid transfer lines between the above components and the digestion reagent vessel, the display indicator vessel, the titrant vessel, such that the syringe pump washes the liquid transfer lines between the vessels and the waste liquid is transferred to the waste liquid reservoir via the first multi-channel switching valve.

In any of the above embodiments, the dosing ring cooperates with the peristaltic pump and the syringe pump to achieve accurate dosing of the liquid into the digester.

In any of the above embodiments, a plurality of digestion devices are correspondingly arranged on the downstream flow paths of the plurality of distribution ports of the second and third multi-channel switching valves, so as to perform a plurality of digestion processes at intervals in sequence, and flow back to the titration cell in sequence for titration, thereby maximally improving the efficiency of the whole system.

The second object of the present invention is to provide an on-line automatically controlled chemical oxygen demand measuring instrument, which comprises the chemical oxygen demand measuring instrument of any one of the above aspects, wherein the common port and the distribution port of each multi-channel switching valve are switched by a computer or an automatic controller to determine the transfer direction and the addition amount of the sample, the reagent, the pure water and the waste liquid, and the cooling module is an on-line automatically controlled cooling module controlled by the computer or the automatic controller.

In one embodiment, the on-line automatic control cooling module comprises a heat exchange coil, a cooling conductor, a semiconductor refrigeration sheet, a heat dissipation assembly, a temperature sensor or a temperature probe from a digestion liquid output end, wherein the heat exchange coil and the cooling conductor are enclosed in a heat insulation shell of the cooling module, the heat exchange coil is a spiral heat exchange coil and is wound on the surface of a cylindrical cooling conductor, an inlet pipe of the spiral heat exchange coil is communicated with the digestion liquid output end, and an outlet pipe of the spiral heat exchange coil is communicated with a downstream sample pool to be detected;

the upper end face of the cooling conductor is provided with a conductor upper end socket which is used for contacting the refrigerating end of the semiconductor refrigerating piece so as to transfer heat to the semiconductor refrigerating piece conveniently; the lower end face of the conductor is provided with a lower end socket of the conductor for fixing and insulating heat;

the refrigerating end of the semiconductor refrigerating sheet is attached to the cooling conductor, and the heating end of the semiconductor refrigerating sheet is connected with the radiating assembly;

the temperature sensor or the temperature probe arranged in the heat insulation shell can send the real-time temperature of the cooling conductor to a computer host or a controller so as to automatically regulate and control the refrigerating effect of the semiconductor refrigerating sheet. In a preferred embodiment, the temperature sensor comprises a resistive temperature sensor, a thermocouple, an IC temperature sensor, a thermistor.

In any of the above embodiments, the lower contact end of the cooling conductor and the heat exchange coil is provided with a lower heat insulation conductor end enclosure used for fixing the heat exchange coil to be not moved, the upper contact end of the lower heat insulation conductor end enclosure is provided with a conductor upper end enclosure, the conductor upper end enclosure is made of metal or other materials with excellent heat exchange effect materials and is attached to the refrigeration end of the semiconductor refrigeration piece, so that the refrigeration ends of the cooling conductor, the heat exchange coil and the semiconductor refrigeration piece are sealed in the heat insulation shell, and the heating end of the semiconductor refrigeration piece protrudes out of the heat insulation shell, so that abnormal heat exchange is avoided. In another specific embodiment, the surface of cooling conductor is equipped with the heliciform slot of equidistance range, can increase the area of contact heat conduction after the heat exchange coil pipe of being convenient for imbeds the slot, and the heat exchange coil pipe of being convenient for simultaneously is fixed on cooling conductor. In a preferred embodiment, the upper end face of the cooling conductor is provided with a first inlet, a first outlet and a curved groove of the heat exchange coil, so that the heat exchange coil can enter the curved groove from the first inlet and then go out from the first outlet, and then can be wound downwards along the groove on the surface of the cooling conductor, thereby avoiding the pipe diameter of the coil from exceeding the horizontal plane and the cylindrical surface of the upper end face. In another preferred embodiment, the lower end surface of the cooling conductor is provided with a second inlet, a second outlet and a curved groove of the heat exchange coil, so that the heat exchange coil wound to the bottom enters the curved groove from the second inlet and then goes out from the second outlet, thereby preventing the diameter of the coil from exceeding the horizontal plane and the cylindrical surface of the lower end surface.

In a specific embodiment, the conductor upper end enclosure is provided with a heat insulation gasket for fixing the upper end enclosure, and the lower end enclosure is made of a heat insulation material and is provided with a screw for fixing the lower end enclosure. The refrigeration device has the functions of firmly installing the refrigeration end, preventing the heat of the hot end from being radiated to the cold end and reducing the refrigeration efficiency; simultaneously, let the cooling conductor keep away from the lagging casing, the air conditioning that prevents to give off reduces the lagging casing temperature to cause condensation, condensate, cause the operational risk and the trouble of whole module.

In any of the above embodiments, the heat dissipation assembly can dissipate heat of the whole cooling module in addition to the semiconductor cooling fins, and includes but is not limited to heat dissipation fins for realizing passive heat dissipation, heat dissipation fin combination fans for active heat dissipation, metal cold head heat conduction copper pipe heat dissipation fins and fans for active heat dissipation, and water cooling head heat conduction pipe heat dissipation fins and fans for active heat dissipation.

In any of the above embodiments, the heat exchange coil is selected from metal, plastic, glass, quartz, and polymer material pipes with excellent heat exchange effect.

In any of the above embodiments, the heat insulation housing is provided with a metal plate heat insulation housing and/or a heat insulation ceramic plate for heat insulation, and the housing is filled with a heat insulation foaming agent, so that the heat insulation performance of the device can be greatly improved.

In any of the above embodiments, when solid heat conduction is adopted, the temperature-reducing conductor may be a metal cylinder or a polymer cylinder having excellent heat exchange effect. In any of the above embodiments, when a solid-liquid heat conduction mode is adopted, the heat conduction solution is adopted in the sealed cavity of the cooling conductor to conduct and control heat and temperature, such as heat conduction oil, heat conduction liquid, pure water, other water and composite solution. In a preferred embodiment, when solid-liquid heat transfer is used, the heat exchange coil is immersed directly in the heat transfer solution of the cooling conductor.

In any of the above embodiments, the cooling module is controlled by a computer host or a controller, and when the computer host or the controller can preset a program to automatically control the cooling effect of the semiconductor chilling plate and control the cooling effect of the cooling assembly on the semiconductor chilling plate and the whole cooling module.

In any of the above embodiments, modular cooling modules of various sizes may be provided according to the specifications of existing chemical oxygen demand meters, so as to directly replace the cooling module of the digester in the existing meters. In a preferred embodiment, the inlet of the heat exchange coil of the cooling module is in communication with the output of a digester in an existing meter, and the outlet is in communication with a sample cell to be tested (i.e., a titer cell) in a color titration apparatus downstream of the meter.

The technical effects are as follows:

(1) compared with the sample adding scheme that a peristaltic pump is matched with a quantitative ring in the prior art, the sample with high impurity content is added into the quantitative ring in advance by the peristaltic pump, so that the effect of rough precision measurement is achieved. Then draw and promote the prestore liquid of ration ring through the syringe pump and carry out the accurate application of sample to avoid directly using the syringe pump and the sewage impurity that brings blocks up and damage the syringe pump and lead to the precision to descend, exert peristaltic pump and ration ring simultaneously and do not receive the influence that impurity blockked up, can guarantee that the precision of application of sample flow path is stable for a long time. (2) And the independently arranged third multi-channel switching valve can add and transfer the leaching pure water into different containers, recover the leaching solution through different multi-channel switching valves for titration, and collect the leaching waste liquid to the waste liquid container.

(3) The bidirectional peristaltic pump can drive a sample to be added into the digestion device, and can also drive digestion liquid and leacheate to flow back into the titration cell, so that the flow path design is simplified.

(4) The design of the multi-flow path system can realize flexible addition and backflow of various samples and reaction reagents, and can also realize that a plurality of digestion devices sequentially carry out a plurality of digestion processes at intervals and the primary transfer of various digestion solutions, so that the current titration reaction can be measured, the next sample digestion process can be carried out at the same time, the measurement efficiency of the whole system is improved to the maximum extent, and the time is saved.

(5) All liquid transfer is realized through a closed pipeline flow path, manual intervention is not needed in the whole flow path, functions of sample addition, reagent addition, digestion reflux, automatic titration and the like can be automatically realized, mechanical moving parts are not needed, and the system reliability is high.

(6) Through the ingenious design of the liquid transfer pipeline, the part of pipelines of the digestion reflux passage and the reagent adding passage form a pipeline of a washing flow path, so that waste liquid is washed and transferred, the structure is simplified, and the instrument cost is saved.

(7) Spiral reaction coil pipe in the online quick cooling module, the design concept of the controllable semiconductor cooling fin of cylinder cooling conductor and end-to-end connection is united, the defect that the contact area is limited and the heat can not be uniformly dissipated due to the fact that the cooling fin directly contacts with the reaction coil pipe is overcome, the defect that the space is crowded and abnormal heat exchange occurs due to the fact that the heating end is placed in a sealed heat-insulation shell is avoided, meanwhile, the contact area of the planar cooling fin and the cylindrical cooling conductor is increased, the effect of quick heat dissipation is achieved, the cooling area and the uniform heat dissipation of the reaction coil pipe contacting with the cooling conductor are greatly improved, the speed of cooling a boiling sample to the room temperature is greatly accelerated, and the automatic analysis and determination speed is greatly improved.

(8) Spiral reaction coil pipe can not only realize quick heat exchange among the cooling module, can also utilize the Coriolis force of the in-process of marcing to carry out the stirring that rolls in the pipeline, realizes the even heat dissipation of liquid in the pipeline, improves cooling efficiency.

(9) The spiral reaction coil can also utilize Coriolis force in the advancing process, fully reduce the dead volume cavity of refrigeration process, transfer to the downstream after ensuring all liquid heat exchanges and detect the container, reduce liquid and remain, the device of being convenient for washs.

(10) The cooling module is operated by a computer host or a controller, and can automatically send instructions according to a preset program, so that the manual operation and monitoring steps are saved, and the relative reliability of the cooling module can be ensured by refrigerating in the same environment;

(11) the online cooling module can realize the refrigeration process of liquid from boiling to normal temperature within 1 minute, and reduce the temperature of a sample to a specified range, and the consistency of conditions ensures that the obtained experimental data are relatively stable.

(12) The invention can simultaneously carry out on-line automatic control on liquid flow path transfer distribution and cooling dosage form by a computer or an automatic controller, can sequentially carry out digestion, cooling and titration determination on a plurality of samples, can detect a plurality of sewage samples by matching with the design of various washing flow paths, saves time, has no mutual pollution, and is particularly suitable for emergency tasks or field determination.

Drawings

FIG. 1: the invention is an overall flow diagram.

FIG. 2: the invention is a work flow chart.

FIG. 3: the invention relates to a product object diagram.

FIG. 4: the invention relates to a cooling module work flow chart.

FIG. 5: a cross-sectional view of the cooling module.

FIG. 6: a perspective view of the heat exchange coil and the temperature reduction conductor inside the cooling module.

FIG. 7: a perspective view of the cooling module.

Legend: 1: sample injector 2: first three-way valve 3: the bidirectional peristaltic pump 4: second three-way valve 5: quantitative ring 6: second multi-channel switching valve 7: cooling module 8: a titration cell 9: first multi-channel switching valve 10: the injection pump 11: third multi-channel switching valve 12: digestion device 13, display indicator container 14: a pure water container 15: digestion reaction reagent container 16: waste liquid container

Detailed Description

In order to make the technical means, the characteristics, the purposes and the functions of the invention easy to understand, the invention is further described with reference to the specific drawings.

Example 1 structural composition of chemical oxygen demand measuring apparatus

The chemical oxygen demand tester comprises a sample digestion reflux flow path, a titration reagent adding flow path and a washing flow path, wherein the sample digestion reflux flow path comprises a sample injector, a first three-way valve, a two-way peristaltic pump, a second three-way valve, a quantitative ring, a second multi-channel switching valve, a digestion device, a cooling module, a titration cell and a liquid transfer pipeline for connecting all components, wherein the sample injector is connected with a first port of the first three-way valve through the liquid transfer pipeline and is sequentially connected with the two-way peristaltic pump, a first port of the second three-way valve, the quantitative ring and the second multi-channel switching valve through a second port of the first three-way valve to be communicated with the digestion device, a third port of the first three-way valve is sequentially connected with the cooling module and the titration cell through the liquid transfer pipeline, so that a sample to be tested is driven to be transferred from the sample injector, the quantitative ring and the second multi-channel switching valve, or the waste water flows back to the first three-way valve from the primary path of the digester, is connected with the cooling module from a third port of the first three-way valve, and finally enters the titration cell.

A second multi-channel switching valve: by switching different distribution ports, samples to be detected from the measuring ring are distributed to condensation positions of different digestion devices, digestion channel number and digestion efficiency are improved, extra parts introduced by separate sample introduction are reduced, and complexity is reduced. As shown in fig. 1, the 16 channels (i.e., the distribution port 16) in the valve diagram are only examples, and the number of channels may be increased or decreased, so as to improve or sacrifice the performance of part of the system, for example, to decrease the number of channels to 12 channels, and the system may still achieve the purpose of parallel resolution of 11-12 channels, etc. The valve can also use a two-position three-way valve and the like to form a valve group to realize the function. The above is all within the scope of protection of the present patent application.

A digestion device: the device is used for realizing digestion condensation reflux of a sample reagent, consists of a digestion pipe and a condensation reflux pipe (condensation position), is connected by adopting a ground port or other forms, and condenses water vapor and the like evaporated in the boiling digestion process of the sample and the reagent on the inner wall of the condensation pipe and refluxes. The condensing pipe adopts air cooling, water cooling and other modes.

And (3) quantitative ring: the device is used for accurately quantifying the sample by the peristaltic pump. The conventional quantitative ring has the advantage of accurate quantification and has the defect that the quantitative volume is fixed and cannot be adjusted.

First and second three-way valves for peristaltic pump flow path regulation: by switching the port of the valve and matching with the steering transformation of the peristaltic pump, the work of sample injection, pipeline cleaning, sample transfer after digestion, sample transfer after titration and the like can be realized.

Cooling module for use in sample transfer process: the rapid cooling in the sample transfer process can be realized, the time for cooling the sample to room temperature is reduced, and the measurement efficiency is improved. Preferably an on-line rapid cooling module, and the cooling speed and time of the digestion solution can be adjusted by a computer or an automatic controller.

A multifunctional titration cell: the multifunctional titration cell is used for digesting and cooling a sample for automatic titration, a color developing agent and a titration reagent can be automatically added through the injection pump, and liquid stirring and automatic camera shooting component recording reading of titration color change and color end point recognition can be carried out under the control of a computer or an automatic controller in the process. The components include, but are not limited to, a magnetic stirring function, an LED light source, an EGB color recognition module, a camera, temperature acquisition, a liquid feeding nozzle, a titration nozzle, and the like.

The reagent adding flow path comprises an injection pump, a first multi-channel switching valve, a digestion reagent container, a display indicator container, a titration solution container and a transfer pipeline for connecting all the parts, wherein the injection pump is connected with a common port (namely 0 position) of the first multi-channel switching valve, the display indicator container, the titration solution container and the digestion reagent container are respectively communicated with a plurality of distribution ports of the first multi-channel switching valve, so that the display indicator and the titration solution are added into the titration cell through the respective distribution ports, and digestion reagents (such as oxidant, catalyst, masking agent and the like) are communicated with a third port of a second three-way valve, a quantitative ring and the second multi-channel switching valve through different distribution ports and are finally communicated with a digestion device, therefore, the injection pump enables the display indicator and the titration solution to enter the first multi-channel switching valve and be accurately added into the titration cell by pumping and pushing the, and enabling the digestion reagent to sequentially enter the first multi-channel switching valve, the third port of the second three-way valve, the quantitative ring and the second multi-channel switching valve, and finally accurately adding the digestion reagent into the digestion device.

An injection pump: the device can be used for extracting and transferring reagents, accurately and quantitatively adding the potassium dichromate solution, the silver sulfate-sulfuric acid solution, the mercury sulfate and other reagents into a digestion condenser tube, and also can be used for accurately and quantitatively adding a ferrocyanide indicator, ammonium ferrous sulfate and other solutions into a titration cell. As COD is mainly used for measuring sewage, wastewater and the like, a sample is rich in various impurities and particulate matters. The plunger of the injection pump is usually made of quartz tube and polytetrafluoroethylene, if the injection pump is used for quantitative addition of a sample, particles (the main component is silicon dioxide) rich in the sample can cause abrasion of the injector and cause faults of components and a system, if the peristaltic pump is used for quantitative addition only in a timing and constant speed scheme, the fatigue effect of the peristaltic pump tube can cause gradual deviation of quantitative precision, and secondary calibration is needed when the peristaltic pump tube is replaced. Therefore, a peristaltic pump is used for adding a sewage sample to be detected into the quantitative ring in advance, then the digestion reagent and the like are extracted through the injection pump and pushed to the quantitative ring flow path and finally added into the digestion device, so that the sample and the reaction reagent can be accurately and quantitatively added, and the phenomena of abrasion and blockage of the injector and reduction of the precision of the peristaltic pump cannot occur.

A first multi-channel switching valve: the switching connection between the injector and different ports can be realized, the reuse of the injector is achieved, the using amount of the injector is reduced, the complexity of a system is reduced, and the manufacturing cost is reduced. As shown in fig. 1, the 16 channels of the valve are only examples, and the number of channels can be increased or decreased, so as to improve or sacrifice the performance of part of the system, for example, the number of channels, i.e. the number of reagent types, can be decreased, and the system can still operate although the same batch measurement of high and low concentration cannot be compatible. The valve can also use a two-position three-way valve and the like to form a valve group to realize the function. The above is all within the scope of protection of the present patent application.

If automated cleaning of the analyzer is required, the chemical oxygen demand meter further comprises a wash flow path, for example comprising a sample loading wash flow path, a digestion reflux wash flow path, a titer cell wash flow path, a reagent addition wash flow path, wherein:

the sample adding and washing flow path comprises a sample injector water purifier, a first three-way valve, a peristaltic pump, a second three-way valve, a quantitative ring, a second multi-channel switching valve and a liquid transfer pipeline between waste liquid pools, wherein the peristaltic pump drives pure water of the sample injector to wash the flow path and discharge waste liquid to the waste liquid pools so as to prevent the digestion liquid from being polluted in the process of flowing back to the titration pools;

If the digestion solution needs to be cooled on line, the chemical oxygen demand tester also comprises a chemical cooling module, a heat exchange coil, a cooling conductor, a semiconductor refrigeration sheet, a heat dissipation assembly, a temperature sensor or a temperature probe, wherein the heat exchange coil and the cooling conductor are sealed in a heat insulation shell of the cooling module, the heat exchange coil is a spiral heat exchange coil and is wound on the surface of a cylindrical cooling conductor, an inlet pipe of the spiral heat exchange coil is communicated with the output end of the digestion solution, and an outlet pipe of the spiral heat exchange coil is communicated with a downstream sample pool to be tested; the upper end face of the cooling conductor is provided with a conductor upper end socket which is used for contacting the refrigerating end of the semiconductor refrigerating piece so as to transfer heat to the semiconductor refrigerating piece conveniently; the lower end face of the conductor is provided with a lower end socket of the conductor for fixing and insulating heat; the refrigerating end of the semiconductor refrigerating sheet is attached to the cooling conductor, and the heating end of the semiconductor refrigerating sheet is connected with the radiating assembly; the temperature sensor or the temperature probe arranged in the heat insulation shell can send the real-time temperature of the cooling conductor to a computer host or a controller so as to automatically regulate and control the refrigerating effect of the semiconductor refrigerating sheet. The temperature sensor comprises a resistance type temperature sensor, a thermocouple, an IC temperature sensor and a thermistor.

The up end of cooling conductor is equipped with heat exchange coil's first entry and first export and crooked slot, and the heat exchange coil of being convenient for gets into crooked slot back from first entry, goes out from first export again, and the slot on following cooling conductor surface twines downwards afterwards to avoid the coil pipe diameter to surpass the horizontal plane and the cylindrical surface of up end. In another preferred embodiment, the lower end surface of the cooling conductor is provided with a second inlet, a second outlet and a curved groove of the heat exchange coil, so that the heat exchange coil wound to the bottom enters the curved groove from the second inlet and then goes out from the second outlet, thereby preventing the diameter of the coil from exceeding the horizontal plane and the cylindrical surface of the lower end surface.

The conductor upper head is provided with a heat insulation gasket for fixing the upper head, and the lower head is made of heat insulation material and is provided with a screw for fixing the lower head. The refrigeration device has the functions of firmly installing the refrigeration end, preventing the heat of the hot end from being radiated to the cold end and reducing the refrigeration efficiency; simultaneously, let the cooling conductor keep away from the lagging casing, the air conditioning that prevents to give off reduces the lagging casing temperature to cause condensation, condensate, cause the operational risk and the trouble of whole module.

The heat dissipation assembly can dissipate heat of the whole cooling module besides the semiconductor refrigeration sheet, and includes, but is not limited to, heat dissipation fins for realizing passive heat dissipation, heat dissipation fin combination fans for active heat dissipation, metal cold head and heat conduction copper tube and heat dissipation fins and fans for active heat dissipation, and water cooling head and cooling conduit and heat dissipation fins and fans for active heat dissipation.

The heat exchange coil is selected from metal, plastic, glass, quartz and high polymer material pipelines with excellent heat exchange effect.

The heat insulation shell and/or the heat insulation ceramic plate made of metal plates are/is used for isolating heat, and the shell can be filled with heat insulation foaming agent, so that the heat insulation performance of the device can be greatly improved.

When a solid heat conduction mode is adopted, the cooling conductor can be a metal cylinder or a polymer cylinder with excellent heat exchange effect. When a solid-liquid heat conduction mode is adopted, heat and temperature are conducted and controlled by adopting a heat conduction solution in a sealed cavity of the cooling conductor, such as heat conduction oil, heat conduction liquid, pure water, other water and a composite solution.

The cooling module is regulated and controlled by the computer host or the controller, and when the computer host or the controller can preset programs, the refrigerating effect of the semiconductor refrigerating sheet can be automatically regulated and controlled, and the heat dissipation effect of the heat dissipation assembly on the semiconductor refrigerating sheet and the whole cooling module is controlled.

Modular cooling modules of various sizes can be arranged according to the specification of the existing chemical oxygen demand measuring instrument so as to directly replace the cooling module of the digestion device in the existing measuring instrument. In a preferred embodiment, the inlet of the heat exchange coil of the cooling module is in communication with the output of a digester in an existing meter, and the outlet is in communication with a sample cell to be tested in a color titration device downstream of the meter.

Example 2 assay procedure according to the invention

As shown in FIGS. 1-2, the assay procedure of the present invention is as follows:

adding a sample to be tested: the sample in the sample injector passes through the first three-way valve, the quantitative ring is filled with the sample through the peristaltic pump, and then the digestion reaction reagent (such as an oxidant, a catalyst, a masking agent and the like) and the like are accurately pumped and pushed by the injection pump to enter the digestion device together with the sample, for example, the digestion reaction reagent is transferred to the digestion device through the No. 14 position of the first switching valve, the second three-way valve, the quantitative ring and the second switching valve by the injection pump for digestion. Then, the injection pump accurately pumps air, the air is pushed in the original path, and the residual liquid in the flow path is pushed into a digestion device for digestion. Excess sample is pumped through the 16-channel port through the second multi-channel switching valve into the waste container.

Cleaning the sample addition flow path: after all the digestion reaction reagents are pushed to the digestion device, pure water is injected into the digestion device through the peristaltic pump by the sample injector along the same flow path, then the pipeline is cleaned by the pure water of the sample injector, the wastewater is transferred to the waste liquid pool from the No. 16 outlet of the second multi-channel switching valve, then the sample injection needle on the sample injector is lifted, the peristaltic pump continues to pump air, and the pure water in the pipeline is emptied through the No. 16 channel port. Therefore, interference of impurities which are not digested during backflow of the digestion liquid can be avoided. Meanwhile, the pollution caused when the oxidant is transferred to the digestion device can be avoided.

Adding a digestion reaction reagent and the like: and adjusting the second multi-channel switching valve to a position from 1 to n (corresponding to the subsequent n digestion condenser pipes), removing the digestion reaction reagent and the like by an injection pump, passing through a position from 14 of the first multi-channel switching valve, a third port of the second three-way valve, a quantitative ring and a position from 0 of the second multi-channel switching valve, and respectively pushing the reagent into the digestion device from the corresponding position from 1 to 15.

Digestion and reflux: after digestion is finished, reverse peristaltic motion of the peristaltic pump is used for driving digestion liquid to reversely flow back, and the digestion liquid passes through the No. 1-15 inlet, the No. 0 outlet, the quantitative ring, the second three-way valve, the peristaltic pump, the first three-way valve and the cooling module of the second multi-channel switching valve. The digestion solution is in the cooling module, and after cooling is completed, the digestion solution is transferred to the titration cell.

Cleaning the digestion solution and recycling the residual digestion solution: after pure water is pumped from the pure water container by the injection pump, the pure water enters the No. 0 inlet of the third multi-channel switching valve through the No. 15 position of the first multi-channel switching valve. And then respectively transferring the pure water to 1-n digestion devices through No. 1-n outlets for washing, reversely creeping the washing liquid through a peristaltic pump, and reversely refluxing the washing liquid containing a small amount of digestion liquid to the cooling module until the washing liquid enters the titration cell.

Adding indicator and titration solution: the syringe pump accurately pumps the color indicator (such as ferron) through the first multi-channel switching valve, and then injects the color indicator into the titration cell from a distribution port of the switching valve. In the same manner, the syringe pump can accurately draw a titration solution (e.g., ferrous ammonium sulfate, etc.) and inject it into the titration cell through different dispensing ports, followed by automatic titration for color determination.

Discharging titration waste liquid: after the titration test is completed, the injection pump pushes the titration waste liquid to pass through the sample digestion reflux flow path until the distribution port 16 of the second multi-channel switching valve enters the waste liquid pool. Simultaneously with or after the discharge of the titration waste liquid, the syringe pump may push the pure water of the pure water container into the titration cell for washing and discharge to the waste liquid cell along the same flow path as described above.

Cleaning reagent addition flow path: the syringe pump can also wash the remaining liquid in the first multi-channel switching valve and/or the reagent addition flow path by injecting air or pure water, and finally discharge the liquid to the waste liquid tank through the distribution port 16 of the first multi-channel switching valve.

Example 3 on-line fast Cooling of digestion solution in Cooling Module

As shown in fig. 5-7, the cooling device consists of a main body of a cubic thermal insulating case and a protruding heat dissipating member. The outermost layer of the main body of the heat-insulating shell is a heat-insulating shell, and a cylindrical cooling conductor is arranged in the middle of the main body of the heat-insulating shell. The cooling conductor can be a metal cylinder or a polymer cylinder with excellent heat exchange effect, the surface of the cooling conductor is provided with spiral grooves which are arranged at equal intervals, so that the heat exchange coil (not shown) can be conveniently embedded into the grooves to increase the contact heat conduction area, and meanwhile, the heat exchange coil is conveniently fixed on the cooling conductor. Meanwhile, the upper end face/lower end face of the cooling conductor is respectively provided with a first inlet/second inlet and a first outlet/second outlet of the heat exchange coil and a bent groove. The heat exchange coil enters the curved groove from the first inlet of the upper end face of the cooling conductor, and then is wound downwards along the groove on the surface of the cooling conductor 6 from the first outlet until the heat exchange coil enters the curved groove from the second inlet of the lower end face, and then the heat exchange coil is discharged from the second outlet until a sample connected with the downstream is connected to a sample inspection pool.

As shown in fig. 5, the upper end surface of the cooling conductor is provided with a conductor upper end socket for contacting the refrigerating end of the semiconductor peltier refrigerating plate, so that heat can be conveniently transferred to the semiconductor refrigerating plate, and a heat-insulating closed heat-preserving shell can be conveniently formed; the lower end face is provided with a conductor lower end socket for fixing and insulating heat. The heating end of the Peltier refrigerating sheet is contacted with the heat dissipation cold head or the heat dissipation assembly.

One side of the lower end of the cooling conductor is provided with a temperature sensor which can send the real-time temperature of the cooling conductor to a computer host or a controller so as to automatically regulate and control the refrigerating effect of the semiconductor refrigerating sheet.

As shown in fig. 5, the liquid to be cooled from the digester passes through a first inlet of a heat exchange coil (not shown) into the upper end face of the temperature reduction conductor, winds around the groove from the first outlet downwards along the groove 7 on the surface of the conductor until entering a second inlet of the lower end face, and then exits from the second outlet after internally surrounding the groove and enters a downstream sample cell to be tested.

The working principle of the solid cooling conductor is shown in figure 4: liquid to be cooled enters a cooling conductor (not shown) through a connecting pipeline and a heat exchange coil under the driving of a power device, and in the contact process of the liquid in the heat exchange coil and the cooling conductor, heat is conducted away, is transferred to a heat dissipation assembly through a semiconductor refrigeration sheet, and is discharged out of the device. Meanwhile, the temperature probe (temperature sensor) monitors the temperature of the cooling conductor in real time and sends information to a computer host or a controller. The computer host or the controller realizes temperature control by adjusting the working current (voltage) of the semiconductor refrigerating sheet according to the received information, so that the liquid is effectively cooled finally, and the cooled liquid is driven to enter a subsequent pipeline or container.

The working principle of the cooling conductor involving the heat-conducting solution is basically as shown in fig. 4: the power device is arranged at the downstream end of the cooling device and can generate negative pressure driving force after being started. The heat exchange coil is immersed in the heat-conducting solution in a winding spiral manner, in the contact process of liquid in the heat exchange coil and the cooling conductor, heat is conducted away and is transferred to the heat dissipation assembly through the semiconductor refrigeration sheet, and the temperature of the cooling conductor is monitored in real time by the temperature probe (temperature sensor) outside the heat discharging device and information is sent to the computer host or the controller. The computer host or the controller realizes temperature control by adjusting the working current (voltage) of the semiconductor refrigerating sheet according to the received information, so that the liquid is effectively cooled finally, and the cooled liquid is driven to enter a subsequent pipeline or container.

Claims

1. The chemical oxygen demand measuring instrument based on different liquid transfer flow paths comprises a sample digestion reflux flow path and a reagent adding flow path, and is characterized in that:

(2) the reagent adding flow path comprises an injection pump, a first multi-channel switching valve, a digestion reagent container, a display indicator container, a titration solution container and transfer pipelines for connecting all the parts, wherein the injection pump is connected with a common port of the first multi-channel switching valve, the display indicator container, the titration solution container and the digestion reagent container are respectively communicated with a plurality of distribution ports of the first multi-channel switching valve, so that the display indicator and the titration solution are added into a titration tank through respective distribution ports, and the digestion reagent is communicated with a third port of a second three-way valve, a quantitative ring and the second multi-channel switching valve through different distribution ports and finally communicated with a digestion device, therefore, the injection pump enables the display indicator and the titration solution to enter the first multi-channel switching valve and be accurately added into the titration tank through extracting and pushing the reagent, and the digestion reagent sequentially enters the first multi-channel switching valve, And a third port of the second three-way valve, a quantitative ring and a second multi-channel switching valve are accurately added into the digester finally.

2. The cod meter of claim 1, wherein the multi-channel switching valve is comprised of a switching valve head, a pipe connector, a rotary power unit, etc., wherein the switching valve head generally has one common port and a plurality of distribution ports to realize a one-to-many switching mode; the pipeline connector is used for connecting an external pipeline with each port on the switching head; the rotating power device realizes the accurate connection of the public port and the distribution port by rotating the valve core inside the switching valve head under the instruction of a computer or an automatic controller; or the internal channels of the multi-channel switching valve are 6-16 channels, and the number of the channels can be increased or decreased, so that the types of the transferred reagents and liquid are increased or decreased, and the transfer speeds of the reagents and the liquid are correspondingly decreased or increased; alternatively, the common port and the dispensing port may serve as both an inlet and an outlet for the reagent.

3. The chemical oxygen demand measuring instrument according to any one of claims 1 to 3, wherein, when the peristaltic pump fills the quantitative ring with the sample, the syringe pump precisely pumps and pushes the digestion reaction reagent into the quantitative ring through the third ports of the first multi-channel switching valve and the second three-way valve, and drives the digestion reaction reagent and the sample together into the digestion device through the second multi-channel switching valve, and/or the quantitative ring cooperates with the peristaltic pump and the syringe pump to achieve precise liquid addition into the digestion device.

4. The chemical oxygen demand meter of claim 4, wherein the syringe pump precisely pushes air through the first multi-channel switching valve, the third port of the second three-way valve, the dosing ring, and the second multi-channel switching valve after the digestion reagent is added to the digester, so that the remaining liquid of the sample digestion reflux flow path is added to the digester.

5. The chemical oxygen demand measuring instrument of any one of claims 1 to 4, wherein the chemical oxygen demand measuring instrument further comprises a wash flow path comprising a sample addition wash flow path, a digestion reflux wash flow path, a titration cell wash flow path, a reagent addition wash flow path, wherein:

a reagent adding and washing flow path which comprises an injection pump, a pure water container connected with a distribution port of the first multi-channel switching valve, a first multi-channel switching valve and a liquid transfer pipeline between the waste liquid pools, so that after the injection pump injects pure water into the first multi-channel switching valve for washing, the waste liquid is transferred to the waste liquid pools through the first multi-channel switching valve; preferably, the flow path further comprises liquid transfer lines between the above components and the digestion reagent vessel, the display indicator vessel, the titrant vessel, such that the syringe pump washes the liquid transfer lines between the vessels and the waste liquid is transferred to the waste liquid reservoir via the first multi-channel switching valve.

6. The chemical oxygen demand measuring instrument according to any one of claims 1 to 5, wherein a plurality of digesters are provided in the downstream flow path of the plurality of distribution ports of the second and third multi-channel switching valves, respectively, to perform a plurality of digestion processes at intervals in sequence, and to sequentially flow back to the titration cell for titration, thereby maximizing the overall system efficiency.

7. An on-line automatically controlled chemical oxygen demand measuring instrument comprising the chemical oxygen demand measuring instrument according to any one of claims 1 to 6, wherein the common port and the distribution port of each multi-channel switching valve are switched by a computer or an automatic controller to determine the transfer direction and the addition amount of the sample, the reagent, the pure water and the waste liquid, and the cooling module is an on-line automatically controlled cooling module controlled by the computer or the automatic controller.

8. The on-line automatically controlled chemical oxygen demand meter of claim 7, wherein the on-line automatically controlled cooling module comprises a heat exchange coil, a cooling conductor, a semiconductor cooling fin, a heat dissipation assembly, a temperature sensor or a temperature probe from the digestion liquid output end, wherein the heat exchange coil and the cooling conductor are enclosed in a heat preservation shell of the cooling module,

the heat exchange coil is a spiral heat exchange coil and is wound on the surface of the cylindrical cooling conductor, an inlet pipe of the heat exchange coil is communicated with the output end of the digestion solution, and an outlet pipe of the heat exchange coil is communicated with a downstream sample pool to be detected;

the temperature sensor or the temperature probe arranged in the heat insulation shell can send the real-time temperature of the cooling conductor to a computer host or a controller so as to automatically regulate and control the refrigerating effect of the semiconductor refrigerating sheet.

9. The on-line automatically controlled chemical oxygen demand tester as claimed in claim 8, wherein the lower contact end of the cooling conductor and the heat exchange coil is provided with a lower heat insulation conductor sealing head for fixing the heat exchange coil without moving, and the upper contact end is provided with a conductor upper sealing head, which is made of metal or other materials with excellent heat exchange effect and is attached to the refrigerating end of the semiconductor chilling plate, so that the refrigerating ends of the cooling conductor, the heat exchange coil and the semiconductor chilling plate are sealed in the heat-insulating shell, and the heating end of the semiconductor chilling plate protrudes out of the heat-insulating shell to avoid abnormal heat exchange; and, the surface of cooling conductor is equipped with the heliciform slot of equidistance range, can increase the area of contact heat conduction after the heat exchange coil of being convenient for imbeds the slot, and the heat exchange coil of being convenient for is fixed on the cooling conductor simultaneously.

10. The automated on-line cod controller according to claim 9, wherein the upper end surface of said cooling conductor is provided with a first inlet and a first outlet of the heat exchanging coil and a curved groove, so that the heat exchanging coil enters the curved groove from the first inlet, then exits from the first outlet, and then winds down the groove on the surface of the cooling conductor, thereby preventing the diameter of the coil from exceeding the horizontal surface and the cylindrical surface of the upper end surface; and/or, the lower terminal surface of cooling conductor is equipped with heat exchange coil's second entry and second export and crooked slot, and the heat exchange coil who is convenient for twine the bottom gets into crooked slot back from the second entry, goes out from the second export again to avoid the coil pipe diameter to surpass the horizontal plane and the cylindrical surface of terminal surface down.

11. The on-line automatically controlled chemical oxygen demand measuring instrument of claim 10, wherein the cooling conductor may be a metal cylinder or a polymer cylinder having an excellent heat exchange effect when a solid heat conduction means is employed; and/or when a solid-liquid heat conduction mode is adopted, heat and temperature are conducted and controlled by adopting a heat conduction solution in the sealed cavity of the cooling conductor, and the preferred heat exchange coil is directly immersed in the heat conduction solution of the cooling conductor.