CN111239091A - Dissolved oxygen sensor calibration device and calibration method based on fluorescence quenching principle - Google Patents
Dissolved oxygen sensor calibration device and calibration method based on fluorescence quenching principle Download PDFInfo
- Publication number
- CN111239091A CN111239091A CN202010110028.6A CN202010110028A CN111239091A CN 111239091 A CN111239091 A CN 111239091A CN 202010110028 A CN202010110028 A CN 202010110028A CN 111239091 A CN111239091 A CN 111239091A
- Authority
- CN
- China
- Prior art keywords
- gas
- dissolved oxygen
- calibration
- closed container
- sensor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 title claims abstract description 107
- 239000001301 oxygen Substances 0.000 title claims abstract description 107
- 229910052760 oxygen Inorganic materials 0.000 title claims abstract description 107
- 238000000034 method Methods 0.000 title claims abstract description 65
- 238000010791 quenching Methods 0.000 title claims abstract description 27
- 230000000171 quenching effect Effects 0.000 title claims abstract description 27
- 239000007789 gas Substances 0.000 claims description 124
- 238000004891 communication Methods 0.000 claims description 14
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 12
- OLBVUFHMDRJKTK-UHFFFAOYSA-N [N].[O] Chemical compound [N].[O] OLBVUFHMDRJKTK-UHFFFAOYSA-N 0.000 claims description 7
- 229910052757 nitrogen Inorganic materials 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 5
- 239000000919 ceramic Substances 0.000 claims description 3
- 229920001296 polysiloxane Polymers 0.000 claims description 3
- 229910001220 stainless steel Inorganic materials 0.000 claims description 3
- 239000010935 stainless steel Substances 0.000 claims description 3
- 238000004806 packaging method and process Methods 0.000 claims description 2
- 238000003860 storage Methods 0.000 claims description 2
- 238000005259 measurement Methods 0.000 description 25
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 21
- 239000000243 solution Substances 0.000 description 20
- 230000008569 process Effects 0.000 description 13
- 230000008901 benefit Effects 0.000 description 8
- 230000005540 biological transmission Effects 0.000 description 8
- 239000012153 distilled water Substances 0.000 description 4
- 239000003153 chemical reaction reagent Substances 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000007613 environmental effect Effects 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- 229920006395 saturated elastomer Polymers 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 238000003912 environmental pollution Methods 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 230000002572 peristaltic effect Effects 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 230000008054 signal transmission Effects 0.000 description 2
- 238000009423 ventilation Methods 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- 238000012935 Averaging Methods 0.000 description 1
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- 239000007832 Na2SO4 Substances 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical group O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 238000005273 aeration Methods 0.000 description 1
- 238000009360 aquaculture Methods 0.000 description 1
- 244000144974 aquaculture Species 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 238000009529 body temperature measurement Methods 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000012824 chemical production Methods 0.000 description 1
- QVFWZNCVPCJQOP-UHFFFAOYSA-N chloralodol Chemical compound CC(O)(C)CC(C)OC(O)C(Cl)(Cl)Cl QVFWZNCVPCJQOP-UHFFFAOYSA-N 0.000 description 1
- 150000001869 cobalt compounds Chemical class 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 229910001882 dioxygen Inorganic materials 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- -1 salt ions Chemical class 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 229920002379 silicone rubber Polymers 0.000 description 1
- 239000004945 silicone rubber Substances 0.000 description 1
- 229910052938 sodium sulfate Inorganic materials 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 230000009897 systematic effect Effects 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
- G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
- G01N21/64—Fluorescence; Phosphorescence
- G01N21/6428—Measuring fluorescence of fluorescent products of reactions or of fluorochrome labelled reactive substances, e.g. measuring quenching effects, using measuring "optrodes"
- G01N21/643—Measuring fluorescence of fluorescent products of reactions or of fluorochrome labelled reactive substances, e.g. measuring quenching effects, using measuring "optrodes" non-biological material
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/27—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands using photo-electric detection ; circuits for computing concentration
- G01N21/274—Calibration, base line adjustment, drift correction
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
- G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
- G01N21/64—Fluorescence; Phosphorescence
- G01N21/6428—Measuring fluorescence of fluorescent products of reactions or of fluorochrome labelled reactive substances, e.g. measuring quenching effects, using measuring "optrodes"
- G01N2021/6432—Quenching
Landscapes
- Health & Medical Sciences (AREA)
- Physics & Mathematics (AREA)
- Immunology (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- General Physics & Mathematics (AREA)
- Biochemistry (AREA)
- Pathology (AREA)
- General Health & Medical Sciences (AREA)
- Analytical Chemistry (AREA)
- Molecular Biology (AREA)
- Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Optics & Photonics (AREA)
- Engineering & Computer Science (AREA)
- Mathematical Physics (AREA)
- Theoretical Computer Science (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Investigating, Analyzing Materials By Fluorescence Or Luminescence (AREA)
Abstract
The invention provides a dissolved oxygen sensor calibration device and a calibration method based on a fluorescence quenching principle. On the premise of controllable cost, the invention reduces operation links, shortens calibration time, simultaneously meets the requirements of national relevant standards in terms of calibration precision, and solves the problems of high cost, low efficiency, low precision, poor stability and the like of the current calibration method for the dissolved oxygen sensor based on the fluorescence quenching principle to a certain extent.
Description
Technical Field
The invention belongs to the technical field of measurement, and relates to a dissolved oxygen sensor calibration device and a calibration method based on a fluorescence quenching principle.
Background
Molecular oxygen dissolved in water is called dissolved oxygen. The method for accurately and quickly measuring the concentration of the dissolved oxygen in the water has important significance in a plurality of fields such as chemical production, medical treatment and health, environmental monitoring, aquaculture and the like. The concentration of dissolved oxygen in water has a certain relationship with the oxygen partial pressure in the air above the water surface, the temperature of water and the concentration of salt ions in the water body. The dissolved oxygen sensor based on the fluorescence quenching principle is a measuring device for detecting and representing the dissolved oxygen condition of water by utilizing the difference of fluorescence quenching characteristics of special compounds under different oxygen concentrations, and compared with the traditional dissolved oxygen detection modes such as an iodometry method, an electrode method and the like, the dissolved oxygen sensor has the remarkable advantages of simple operation, long service life, convenience in maintenance, small influence of environmental conditions and the like, and is one of mainstream devices for measuring dissolved oxygen at present.
Because the sensor measures the concentration of dissolved oxygen by a relatively precise optical means, the actual use requirement can be met only by calibrating before delivery and after replacing optical components such as a fluorescent film and the like. The currently common calibration method is a "two-point method", that is, zero calibration and full-scale calibration are performed on the sensor respectively. When zero point is calibrated, excessive Na is added2SO3Dissolving in distilled water (sometimes adding small amount of cobalt compound as catalyst), stirring, and making into Na2SO3A supersaturated solution. In this process, Na2SO3Reacting with oxygen dissolved in water to generate Na2SO4Finally, oxygen is removed completely to obtain the oxygen-free water solution. The sensor is immersed in the solution for measurement, the zero error of the sensor can be measured, and the minimum value of the measuring range is calibrated. When the full scale is calibrated, firstly, the environmental temperature is controlled to keep constant (generally 25 +/-0.5 ℃), then air is introduced into distilled water by an air pump, and the distilled water is continuously stirred, so that the concentration of dissolved oxygen in the water body reaches saturation. Stopping aeration, and continuing stirringAnd (3) 30 min. After the concentration of the dissolved oxygen is stable, the sensor is immersed in the solution for measurement, the full-scale error of the sensor can be measured, and the maximum value of the range is calibrated.
The calibration is carried out by utilizing a two-point method, and the solution needs to be prepared, and links such as the stability of the concentration of the dissolved oxygen need to be waited for exist, so the operation is more complicated, the consumed time is longer, and the calibration efficiency is lower. Na consumed for preparing oxygen-free aqueous solution during zero calibration2SO3The amount is very large, the implementation cost of calibration is improved, and meanwhile, Na is added2SO3The solution brings certain harm to operators, and the residual waste liquid has great pollution to the environment. In addition, the two-point method only calibrates the maximum value and the minimum value in the range, and cannot verify the measurement accuracy of other points in the range, which easily causes systematic errors.
In addition to the most common two-point calibration, some literature describes a class of "hybrid methods". The operator first needs to formulate saturated N2And O2And controlling the flow rate of the two solutions by a peristaltic pump, and mixing the two solutions in different proportions to obtain solutions containing dissolved oxygen with different concentrations for calibrating the sensor. Another way is to mix high purity N2And O2Mixing the mixture by a gas mixer at different flow rate ratios, and introducing distilled water to obtain solution containing dissolved oxygen with different concentrations for calibrating the sensor. The method also has the problems of long time consumption, high cost and unstable concentration, and meanwhile, the calibration result is influenced by the precision of equipment such as a flow valve, a peristaltic pump, a gas mixer and the like, and the final result hardly meets the requirement of accurate calibration, so that a dissolved oxygen sensor calibration device and a calibration method based on the fluorescence quenching principle are urgently needed.
The invention patent with the patent application number of 201310637434 discloses a calibration method and a device of a dissolved oxygen sensor, which have the advantages of high calibration precision, simple structure and convenient operation, and adopt combined gas (N)2And O2Mixed gas) calibration replaces solution calibration, solves the problem of influence of unstable oxygen concentration in the solution on measurement error, and is prepared according to the design proportionThe combined gas obtains different oxygen concentrations with higher precision, simplifies the proportioning process of different oxygen concentrations in the solution, improves the precision of the oxygen concentration, saves the calibration time, and adopts N as the combined gas2And O2The mixed gas can not cause atmospheric pollution when being diffused into the air, meanwhile, the calibration process does not need any chemical reagent, the harm to the human body and the secondary pollution to the tested liquid are avoided, the whole set of dissolved oxygen sensor device only needs one set of closed container, and the prepared mixed gas with different concentrations makes the standard device simpler, the operation is more convenient, and the standard device has good application prospect. However, the calibration device described in the patent comprises precision components such as a standard thermometer, a ball valve and the like, so that the size, the deployment difficulty and the use cost of the device are increased; the standard thermometer can only realize single-point temperature measurement, and certain errors easily exist in measurement; in the calibration process, the ball valve needs to be manually controlled to be opened and closed, so that the operation is complicated and human errors are easily introduced; the pressure used during calibration is as high as 5-8MPa, so that the method has great danger and is easy to cause waste of experimental gas; the dissolved oxygen concentration conversion is performed by a table look-up method, the error is more than 5%, and the flexibility is limited.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a dissolved oxygen sensor calibration device and a calibration method based on a fluorescence quenching principle, which reduce operation links and shorten calibration time on the premise of controllable cost, and simultaneously meet the requirements of national relevant standards on calibration precision. The invention solves the problems of high cost, low efficiency, low precision, poor stability and the like of the current calibration method for the dissolved oxygen sensor based on the fluorescence quenching principle to a certain extent.
The invention provides the following technical scheme:
the utility model provides a dissolved oxygen sensor calibration device based on fluorescence quenching principle, includes a plurality of gas cylinders, is equipped with the main valve on the gas cylinder, and the main valve connects gradually relief pressure valve and manometer, and the exit end of relief pressure valve passes through the pipeline and connects with sealed container, installs a plurality of temperature sensor in the sealed container, and the sealed container other end is connected with the host computer.
Preferably, the plurality of gas cylinders are filled with oxygen-nitrogen mixture gas in different proportions.
In any of the above schemes, preferably, the number of the gas cylinders is multiple.
In any of the above schemes, preferably, the number of the gas cylinders is not less than 5.
In any of the above embodiments, preferably, a container cover is detachably provided on the upper portion of the closed container.
In any of the above schemes, preferably, the joint of the closed container and the container cover is sealed by a silica gel ring.
In any of the above schemes, preferably, the casing of the closed container is made of glass and/or plastic material, and the thickness is larger than 2.5 mm.
In any of the above aspects, preferably, a plurality of temperature sensors are installed in the closed casing.
In any of the above embodiments, preferably, 3 to 5 temperature sensors are installed in the closed container.
In any of the above embodiments, preferably, the temperature sensor is fixed to an inner wall of the closed casing by silicone rubber.
In any of the above aspects, preferably, the closed container is connected to an upper computer through a data transmission line.
In any of the above schemes, preferably, the two sides of the closed container are respectively provided with an air inlet and an air outlet, the air inlet is connected with the outlet end of the pressure reducing valve through a pipeline, and the air outlet is connected with the one-way valve.
In any of the above embodiments, preferably, the closed container is provided with a cable outlet.
In any of the above solutions, preferably, the cable outlet is sealed by a conical ring.
In any of the above schemes, preferably, the pipeline is any one of a stainless steel pipe, a ceramic pipe, a silicone tube and a plastic tube.
In any of the above schemes, preferably, the upper computer is a computer system capable of directly or indirectly receiving and displaying the output result of the sensor.
The invention also discloses a method for calibrating by adopting the calibrating device, which comprises the following steps;
s1: preparing a plurality of standard gases with different component proportions by using high-purity oxygen and nitrogen, and packaging the standard gases in each gas cylinder;
s2: placing a sensor to be calibrated in a closed container, connecting the sensor to a power supply, connecting the sensor to an upper computer through a communication assembly, and closing a container cover;
s3: connecting the gas cylinder packaged with the gas with the specific component and prepared in the step S1 with a closed container through a pipeline, and starting to calibrate the sensor;
s4: and (5) sequentially replacing the gas cylinders filled with the standard gas with other component proportion, and repeating the calibration operation in the step S3 until the calibration is completed.
Preferably, the oxygen and nitrogen used for preparing the standard gas in the step S1 have a purity of not less than 99.9%.
In any of the above embodiments, preferably, in step S1, not less than 5 kinds of standard gases are prepared according to the oxygen concentration gradient.
In any of the above embodiments, the uncertainty of the component concentration of the finally prepared oxygen-nitrogen mixed standard gas in step S1 is preferably 1% or less.
In any of the above embodiments, it is preferable that the oxygen-nitrogen mixed standard gas finally prepared in step S1 has a filling pressure of not less than 5 MPa.
In any of the above embodiments, in step S2, the power supply is an internal power supply of the device with a storage battery and/or an external power supply connected by a wired connection, and the communication module includes a wireless communication unit and a wired communication unit connected by a signal cable.
In any of the above schemes, preferably, the wireless communication component is a wireless communication component based on a WLAN, LoRa, NB-IoT, and bluetooth common communication protocol.
In any of the above schemes, preferably, in step S2, the upper computer is a computer system capable of directly or indirectly receiving and displaying the output result of the sensor.
In any of the above schemes, in the step S3, the tube is preferably one of a stainless steel tube, a ceramic tube, a silicone tube, and a plastic tube.
In any of the above embodiments, preferably, in step S3, the method for calibrating a sensor using an oxygen-nitrogen mixed standard gas with a specific composition includes the following steps:
(1) opening a valve and a pressure reducing valve of a gas cylinder filled with standard gas, and introducing the standard gas into the closed container through a pipeline to fill the interior of the container with the standard gas;
(2) closing the pressure reducing valve, reading the readings of the temperature sensor in the container through the upper computer, and waiting until the temperature is constant;
(3) reading and recording gas components, temperature and the readings of the dissolved oxygen sensor through an upper computer, calculating the theoretical dissolved oxygen concentration value at the current temperature, and establishing the functional relation between the readings of the sensor and the dissolved oxygen concentration.
In any of the above schemes, preferably, in the step (1), the standard gas is introduced into the closed container through the pipeline at the pressure of 0.1-0.3MPa for about 40 s.
In any of the above schemes, preferably, the relation of the saturated dissolved oxygen of the water in the step (3) is DOf＝(P/P0) (468/(31.6+ T)), wherein DOfThe maximum concentration of oxygen which can be dissolved in water, P is the partial pressure of oxygen in air during measurement, P0Is the oxygen partial pressure in the standard atmosphere and T is the temperature at which measurement is made.
Advantageous effects
The invention discloses a dissolved oxygen sensor calibration device and a calibration method based on a fluorescence quenching principle, which have the following advantages:
(1) by using N2And O2The mixed standard gas replaces the traditional solution to calibrate the dissolved oxygen sensor, so that the problems of long time consumption and poor precision caused by unstable oxygen concentration in each solution in the traditional method are solved;
(2) the complicated solution preparation and waiting process is avoided, the operation difficulty is obviously reduced, the time required by the calibration of the sensor is effectively shortened, and the calibration efficiency is improved;
(3) the calibration process only needs to use N2And O2The problems of harm of chemical reagents to operators and environmental pollution in the traditional calibration are avoided;
(4) compared with various calibration methods commonly used in the industry, the method has remarkable advantages in operation cost and use flexibility, is easy to deploy in a large scale, and has good application prospect.
Drawings
FIG. 1 is a schematic structural diagram of a dissolved oxygen sensor calibration device based on a fluorescence quenching principle according to the present invention;
FIG. 2 is a graph showing the measurement results of the sensors according to the different calibration methods in example 3;
FIG. 3 is a graph comparing the results of gas consumption using different calibration methods in example 4;
fig. 4 shows the measurement accuracy of the sensor in example 4 using different calibration methods.
The reference numbers are as follows:
1. the gas cylinder, 2, gas cylinder main valve, 3, relief pressure valve, 4, gas pressure gauge, 5, gas transmission pipeline, 6, closed container, 7, air inlet, 8, gas vent, 9, check valve, 10, temperature sensor, 11, cable outlet, 12, data transmission line, 13, host computer.
Detailed Description
In order to further understand the technical features of the present invention, the present invention is described in detail with reference to the specific embodiments below.
Example 1
As shown in figure 1, the invention discloses a dissolved oxygen sensor calibration device based on a fluorescence quenching principle, which comprises a plurality of gas cylinders 1 filled with oxygen-nitrogen mixed gas in different proportions, wherein each gas cylinder is provided with a main valve 2 which is connected with a pressure reducing valve 3 and a pressure gauge 4 to control the pressure of an outlet; the outlet end of the pressure reducing valve 3 is connected to a closed container 6 through a pipeline 5; the closed container 6 is internally provided with 3-5 temperature sensors 10 which are connected with an upper computer 13 through a data transmission line 12.
The number of the gas cylinders 1 corresponds to the number of the calibration points determined in the previous period. The closed container 6 is provided with an air inlet 7 and an air outlet 8; wherein, the gas inlet 7 is connected with the outlet end of the pressure reducing valve 3 through a pipeline 5 and is used for sending the gas in the gas bottle 1 into the closed container 6; the exhaust port 8 is connected with a one-way valve 9 and used for exhausting original gas in the closed container 6 and preventing external gas from entering to influence calibration precision.
The closed container 6 is also provided with a cable outlet 11 for providing a power supply and signal transmission path based on a wired mode for the dissolved oxygen sensor to be calibrated and the built-in temperature sensor 10 when necessary. Specifically, the dissolved oxygen sensor to be measured in the application is horizontally placed in the closed container 6, and can be fixed by adopting an adhesive to prevent the dissolved oxygen sensor from shaking if necessary; a plurality of temperature sensors 10 are fixed to the side wall of the closed vessel 6 at intervals of 5-10 cm; the power supply and signal transmission cables of the dissolved oxygen sensor to be detected and the temperature sensor 10 are led out through the cable outlet 11.
In order to prevent external gas from entering and influencing the calibration precision, the cable outlet 11 is sealed by a conical ring.
The invention provides a dissolved oxygen sensor calibration device based on a fluorescence quenching principle, which comprises the following functional implementation processes:
according to experimental conditions and practical application requirements, determining the number of the calibration points and the approximate interval of the dissolved oxygen concentration corresponding to each calibration point, preparing standard gases with different proportions required by each calibration point by using high-purity oxygen and nitrogen, and filling the standard gases into the gas cylinder 1. The gas cylinder 1 is connected with a main valve 2, a pressure reducing valve 3 and a pressure gauge 4 to provide necessary gas pressure conditions for the calibration process; the outlet end of the pressure reducing valve 3 is connected to a gas inlet 7 arranged on the shell surface of the closed container 6 through a gas pipeline 5, and the standard gas in the gas cylinder 1 is sent into the closed container 6. The surface of the closed container 6 is also provided with an exhaust port 8 which is connected with a one-way valve 9 and used for exhausting the original gas in the closed container 6 and preventing the external gas from entering to influence the calibration precision. Since the measurement result of the dissolved oxygen concentration is greatly influenced by the temperature, 3-5 temperature sensors 10 are installed in the closed container 6 for measuring the temperature of the calibration environment. The power supply and signal cables of the temperature sensor and the dissolved oxygen sensor to be calibrated are led out through a cable outlet 11, wherein a data transmission line 12 is connected with an upper computer 13 to read data returned by the sensor in real time, and the cable outlet 11 is sealed by adopting a conical ring to ensure air tightness.
During calibration, the sensor is placed in the closed container 6 and is connected with the power supply and the communication assembly through the cable outlet 11, so that the sensor can work normally and can communicate with the upper computer 13 normally through the signal cable 12. Selecting a gas cylinder 1 with a specific component as required, connecting all parts and checking the gas tightness; opening a main valve 2 of the gas cylinder, adjusting a reducing valve 3 according to the indication number on a barometer 4 to maintain the outlet pressure at 0.1-0.3MPa, and allowing the standard gas in the gas cylinder to enter a closed container 6 through a pipeline 5 and a gas inlet 7; the ventilation is continued for about 40 seconds, so that the inside of the closed container 6 is filled with the standard gas, the original gas is discharged through the gas outlet 8 and the check valve 9, and then the pressure reducing valve 3 is closed. In the process, the temperature sensor 10 and the dissolved oxygen sensor transmit the measurement results to the upper computer 13 through the signal cable 12. An operator reads the readings of the temperature sensors 10 in the container through the upper computer 13; and (5) waiting for about 5min until the readings of the two sensors tend to be stable, and reading and recording the gas components in the used gas cylinder 1, the temperature during calibration and the readings of the dissolved oxygen sensor. And (4) closing the gas cylinder main valve 2, sequentially replacing the gas cylinders 1 with different components, and repeating the operation until the calibration is completed.
Example 2
The invention also provides a method for calibrating the dissolved oxygen sensor calibration device based on the fluorescence quenching principle of the embodiment 1, which specifically comprises the following implementation steps:
s1: according to experimental conditions and practical application requirements, determining the number of calibration points and the approximate interval of the dissolved oxygen concentration corresponding to each calibration point, wherein the total number of the calibration points is not less than 5, preparing standard gases with different proportions required by each calibration point by using high-purity oxygen and nitrogen, filling the standard gases into a gas cylinder 1, and the filling pressure is not lower than 5 MPa;
s2: opening a sealing cover of the closed container 6, putting a dissolved oxygen sensor to be calibrated and a temperature sensor 10 into the container, connecting a power supply and a communication assembly (an external power supply line and a data transmission line 12 are led out from a cable outlet 11), ensuring that the dissolved oxygen sensor and the communication assembly can normally work and normally communicate with an upper computer 13, and then closing a container cover;
s3: connecting the gas cylinder 1 filled with the standard gas prepared in the S1 and the gas inlet of the closed container 6 by using the gas transmission pipeline 5, and starting to calibrate the sensor, specifically comprising the following steps:
(1) opening the main valve 2 of the gas cylinder, adjusting a pressure reducing valve 3 connected with the main valve, introducing standard gas into a closed container 6 through a gas transmission pipeline 5, observing and controlling outlet pressure through a pressure gauge 4, and maintaining the gas pressure within the range of 0.1-0.3 MPa; the residual gas in the closed container 6 can not be completely discharged due to too small air pressure, the calibration precision and the data consistency are influenced, the air tightness of the closed container 6 can be damaged due to too large air pressure, and meanwhile, the gas is wasted; continuously ventilating for about 40s to ensure that the inside of the closed container 6 is filled with standard gas, and the original gas is exhausted through an exhaust port 8 and a one-way valve 9;
(2) closing the pressure reducing valve 3 and stopping ventilation; reading the readings of the temperature sensors 10 in the closed container 6 through an upper computer 13; because the measurement result of the dissolved oxygen sensor is greatly influenced by the temperature, the temperature of each point in the closed container 6 is kept constant for about 5min, and the dissolved oxygen sensor obtains a stable measurement result;
(3) reading and recording the used gas components, the temperature during calibration and the reading number of the dissolved oxygen sensor through an upper computer 13; the theoretical value of the dissolved oxygen concentration is calculated by utilizing the gas components and the temperature data, and the functional relation between the sensor readings and the dissolved oxygen concentration is established, wherein the method comprises the following steps:
it is known that the saturated dissolved oxygen of water in a specific gas environment and temperature approximately conforms to the relationship: DOf＝(P/P0) (468/(31.6+ T)), wherein DOfThe maximum concentration of oxygen which can be dissolved in water, P is the partial pressure of oxygen in air during measurement, P0Is the oxygen partial pressure in the standard atmosphere and T is the temperature at which measurement is made.
The oxygen partial pressure is obtained by multiplying the atmospheric pressure by the mole fraction of oxygen, and the volume fraction of the air is similar to that of an ideal gas in measurement and can be used for replacing the mole fraction, and in natural atmosphere, the volume fraction of the oxygen is about 20.95 percent;
the temperature measured in the vessel during calibration was 20 ℃ assuming an oxygen content of 15% (V/V) in the standard gas;
using the above formula, it can be determined that under the condition that the dissolved oxygen concentration of the water body is (15%/20.95%) (468/(31.6+20)) -6.494 mg/L, that is, at 20 ℃, the measurement result of the sensor under the gas environment containing 15% oxygen is equivalent to the measurement result in the water containing 6.494mg/L oxygen;
when other types of standard gases and different temperatures are used, the method can be adopted for conversion to obtain the theoretical value of the dissolved oxygen concentration in water at the corresponding temperature, and further the functional relation between the measured value of the sensor and the dissolved oxygen concentration is established. For example, the fluorescence intensity values measured by the sensor under each dissolved oxygen concentration are recorded, each point is fitted to obtain a standard curve of the fluorescence intensity relative to the change of the dissolved oxygen concentration, the relation is stored in the sensor, and the dissolved oxygen concentration in the sample to be measured can be obtained by calculating the measured fluorescence intensity through the functional relation obtained in the calibration process during actual measurement. The method can effectively improve the calibration precision of the sensor.
S4: and (5) sequentially replacing the gas cylinders 1 filled with the standard gas with other component proportion, and repeating the calibration step in the step S3 until the calibration is completed.
The invention utilizes N2And O2The mixed standard gas replaces the traditional solution to calibrate the dissolved oxygen sensor, thereby solving the problems of long time consumption and poor precision caused by unstable oxygen concentration in each solution in the traditional calibration method.
Example 3
This example is a comparative experiment: calibrating three dissolved oxygen sensors with the same model and service life based on a fluorescence quenching principle by respectively using a two-point calibration method, a gas mixing method and the calibration method provided by the invention which are commonly used in the industry; after calibration is finished, the same standard sample is detected for multiple times by using three sensors under the conditions of constant temperature and constant pressure, the interval between two detections is 10min, and the measurement result of each sensor is recorded; the calibration effect of the Hash commodity-level high-precision dissolved oxygen sensor is compared by taking the Hash commodity-level high-precision dissolved oxygen sensor as a standard reference, and the measurement result is shown in FIG. 2.
Therefore, compared with several calibration methods commonly used in the industry, the calibration method provided by the invention has significant advantages in the accuracy and repeatability of the measurement result. The calibration method provided by the invention can effectively solve the problems of low precision and poor stability in the traditional calibration process.
Example 4
This example is a comparative experiment: respectively calibrating two dissolved oxygen sensors with the same model and service life based on the fluorescence quenching principle for multiple times, wherein one of the sensors uses the calibration method related in the invention patent with the patent application number of 201310637434, and the other sensor uses the calibration method provided by the invention; measuring the standard gas consumption in each calibration process by using a gas flow sensor; then, the two sensors are used for detecting different samples for multiple times and averaging, the calibration effects are compared by taking the Hash commodity-level high-precision dissolved oxygen sensor as a standard reference, and the measurement results are shown in fig. 3 and 4. It can be seen that, also as a gas-based sensor calibration method, the present invention has a significant advantage in the consumption of standard gas compared to other methods. On the premise that the measurement accuracy of the calibrated sensor is equal to or better than that of a control group, the cost of calibration operation is effectively reduced. Meanwhile, the complex solution preparation and waiting process is avoided, the operation difficulty is obviously reduced, the time required by the calibration of the sensor is effectively shortened, the calibration efficiency is improved, the problems of harm of chemical reagents to operators and environmental pollution in the traditional calibration are avoided, and the method has obvious advantages in operation cost and use flexibility.
The foregoing shows and describes the general principles, essential features, and associated advantages of the present invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are intended as illustrations of the principles of the invention, but that various changes and modifications may be made without departing from the spirit and scope of the invention, and the invention is to be accorded the scope of the claims appended hereto. The scope of the invention is defined by the appended claims and equivalents thereof. The above embodiments are only illustrative and not restrictive, and any insubstantial modifications made by those skilled in the art based on the present invention shall fall within the scope of the present invention.
Claims (10)
1. A dissolved oxygen sensor calibration device based on fluorescence quenching principle is characterized in that: the gas cylinder temperature control device comprises a plurality of gas cylinders (1), wherein a main valve (2) is arranged on each gas cylinder (1), the main valve (2) is sequentially connected with a pressure reducing valve (3) and a pressure gauge (4), the outlet end of the pressure reducing valve (3) is connected with a closed container (6) through a pipeline (5), a plurality of temperature sensors (10) are installed in the closed container (6), and the other side of the closed container (6) is connected with an upper computer (13).
2. The dissolved oxygen sensor calibration device based on fluorescence quenching principle as claimed in claim 1, wherein: the plurality of gas cylinders (1) are filled with oxygen-nitrogen mixture gas in different proportions.
3. The dissolved oxygen sensor calibration device based on the fluorescence quenching principle as claimed in claim 2, wherein: a plurality of temperature sensors (10) are installed in the closed container (6).
4. The dissolved oxygen sensor calibration device based on fluorescence quenching principle as claimed in claim 3, wherein: and an air inlet (7) and an air outlet (8) are respectively arranged on two sides of the closed container (6), the air inlet (7) is connected with the outlet end of the pressure reducing valve (3) through a pipeline (5), and the air outlet (8) is connected with a one-way valve (9).
5. A method of calibration using the calibration apparatus of any one of claims 1-4, wherein: comprises the following steps;
s1: preparing a plurality of standard gases with different component proportions by using high-purity oxygen and nitrogen, and packaging the standard gases in each gas cylinder (1);
s2: placing a sensor to be calibrated in a closed container (6), connecting a power supply, connecting the sensor to an upper computer (13) through a communication assembly, and closing a container cover;
s3: connecting the gas cylinder (1) which is prepared in the step S1 and is packaged with the gas with the specific component and the closed container (6) by using a pipeline (5), and starting to calibrate the sensor;
s4: and (5) replacing the gas cylinders (1) filled with the standard gas with other component proportions in sequence, and repeating the calibration operation in the step S3 until the calibration is completed.
6. The method for calibrating the dissolved oxygen sensor calibration device based on the fluorescence quenching principle as claimed in claim 5, wherein: the purity of the oxygen and the nitrogen used for preparing the standard gas in the step S1 is not lower than 99.9%.
7. The method for calibrating the dissolved oxygen sensor calibration device based on the fluorescence quenching principle as claimed in claim 5, wherein: in step S2, the power supply is an internal power supply of the device with a storage battery and/or an external power supply connected by a wired connection, and the communication assembly includes a wireless communication unit and a wired communication unit connected by a signal cable.
8. The method for calibrating the dissolved oxygen sensor calibration device based on the fluorescence quenching principle as claimed in claim 5, wherein: in the step S3, the pipeline (5) is any one of a stainless steel pipe, a ceramic pipe, a silicone tube, and a plastic tube.
9. The method for calibrating the dissolved oxygen sensor calibration device based on the fluorescence quenching principle as claimed in claim 5, wherein: in step S3, the method for calibrating a sensor using an oxygen-nitrogen mixed standard gas having a specific composition specifically includes the following steps:
(1) opening a valve of the gas bottle (1) filled with standard gas and a pressure reducing valve (3), and introducing the standard gas into the closed container (6) through a pipeline (5) to ensure that the interior of the closed container (6) is filled with the standard gas;
(2) closing the pressure reducing valve (3), reading the reading of the temperature sensor (10) in the container through an upper computer (13), and waiting until the temperature is constant;
(3) reading and recording gas components, temperature and the readings of the dissolved oxygen sensor through an upper computer (13), calculating the theoretical dissolved oxygen concentration value at the current temperature, and establishing the functional relation between the readings of the sensor and the dissolved oxygen concentration.
10. The method for calibrating the dissolved oxygen sensor calibration device based on the fluorescence quenching principle as claimed in claim 9, wherein: and (2) in the step (1), standard gas is introduced into the closed container (6) through the pipeline (5) at the pressure of 0.1-0.3 MPa.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010110028.6A CN111239091A (en) | 2020-02-23 | 2020-02-23 | Dissolved oxygen sensor calibration device and calibration method based on fluorescence quenching principle |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010110028.6A CN111239091A (en) | 2020-02-23 | 2020-02-23 | Dissolved oxygen sensor calibration device and calibration method based on fluorescence quenching principle |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN111239091A true CN111239091A (en) | 2020-06-05 |
Family
ID=70866956
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010110028.6A Pending CN111239091A (en) | 2020-02-23 | 2020-02-23 | Dissolved oxygen sensor calibration device and calibration method based on fluorescence quenching principle |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111239091A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113866362A (en) * | 2021-09-28 | 2021-12-31 | 明石创新(烟台)微纳传感技术研究院有限公司 | Intelligent efficient accurate oxygen measuring instrument calibration and compensation method |
| CN113916849A (en) * | 2021-09-10 | 2022-01-11 | 山东省科学院海洋仪器仪表研究所 | Calibration method and calibration device for optical dissolved oxygen sensor |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103616481A (en) * | 2013-12-03 | 2014-03-05 | 南京南瑞集团公司 | Calibration method and device for dissolved oxygen sensor |
| CN104330530A (en) * | 2014-10-29 | 2015-02-04 | 核工业北京化工冶金研究院 | Dissolved oxygen (DO) testing device and DO testing method |
| CN104515761A (en) * | 2014-12-20 | 2015-04-15 | 国家海洋局第二海洋研究所 | High-precision optical dissolved oxygen sensor calibration method and device |
| CN110082488A (en) * | 2019-04-19 | 2019-08-02 | 山西省计量科学研究院 | A kind of dissolved oxygen metering calibrating installation and method |
-
2020
- 2020-02-23 CN CN202010110028.6A patent/CN111239091A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103616481A (en) * | 2013-12-03 | 2014-03-05 | 南京南瑞集团公司 | Calibration method and device for dissolved oxygen sensor |
| CN104330530A (en) * | 2014-10-29 | 2015-02-04 | 核工业北京化工冶金研究院 | Dissolved oxygen (DO) testing device and DO testing method |
| CN104515761A (en) * | 2014-12-20 | 2015-04-15 | 国家海洋局第二海洋研究所 | High-precision optical dissolved oxygen sensor calibration method and device |
| CN110082488A (en) * | 2019-04-19 | 2019-08-02 | 山西省计量科学研究院 | A kind of dissolved oxygen metering calibrating installation and method |
Non-Patent Citations (1)
| Title |
|---|
| 崔树军: "环境监测", 中国环境出版社, pages: 99 * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113916849A (en) * | 2021-09-10 | 2022-01-11 | 山东省科学院海洋仪器仪表研究所 | Calibration method and calibration device for optical dissolved oxygen sensor |
| CN113866362A (en) * | 2021-09-28 | 2021-12-31 | 明石创新(烟台)微纳传感技术研究院有限公司 | Intelligent efficient accurate oxygen measuring instrument calibration and compensation method |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN108663347B (en) | Multi-parameter interference compensation correction system and method for optical dissolved oxygen sensor | |
| CN104515761B (en) | High-precision optical dissolved oxygen sensor calibration method and device | |
| CN111239091A (en) | Dissolved oxygen sensor calibration device and calibration method based on fluorescence quenching principle | |
| CN208537414U (en) | Optical dissolved oxygen sensor multi-parameter interference compensation corrects system | |
| CN103616481A (en) | Calibration method and device for dissolved oxygen sensor | |
| CN203519455U (en) | Device for measuring content of carbonate in mineral | |
| CN212646564U (en) | Acidimeter electrode and acidimeter | |
| CN112504910A (en) | Evaluation device and evaluation method for anaerobic biochemical effect of wastewater | |
| CN105628481B (en) | A kind of tissue oxygen detection calibration titer configuration device and calibration method | |
| CN115586316B (en) | Water quality analyzer inspection and calibration method | |
| CN111380828A (en) | Method for detecting residual quantity of hydrogen peroxide in water | |
| CN115015476B (en) | Automatic copper ammonia solution oxygen measuring instrument based on integrated gas-liquid flow passage module and testing method | |
| CN114594229B (en) | Flow-through soil respiration monitor and respiration rate calculation method | |
| CN113884645A (en) | Device is prepared to methane henry constant standard in experimental water | |
| JPH0711502B2 (en) | Calibration method of measuring device and calibration instrument | |
| CN204314220U (en) | For the device of optical dissolved oxygen sensor high-precision calibrating | |
| CN114858654A (en) | Aluminum ash metal content detection device and detection method | |
| CN107663163B (en) | Is used for13Raw material gas filling method for C-urea synthesis | |
| RU2552598C1 (en) | Device for reproduction and transmission of mass concentration units of oxygen and hydrogen in liquid media | |
| CN212379385U (en) | Dissolved oxygen sensor calibration device | |
| CN218824179U (en) | Gas instrument calibrating device under sub-vacuum environment | |
| CN111812089A (en) | Mineralization of CO by organic carbon in soil2Device and method for continuously measuring release amount | |
| CN112630373A (en) | Gas load measuring device and application thereof, and CO2Method for measuring load | |
| CN214503581U (en) | Full-automatic biochemical oxygen demand measuring instrument | |
| CN100535639C (en) | Available chlorine determination solution and colorimetric determination tube therefor |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| RJ01 | Rejection of invention patent application after publication | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20200605 |