In the production process of infrared temperature measurement technologyProduct quality controlAnd monitoring, online fault diagnosis and safety protection of equipment and energy conservation have played an important role.In the past 20 years, non-contactInfrared body thermometerThe technology has developed rapidly, the performance has been improved, the function has been enhanced, the variety has been increased, and the scope of application has also been expanded.Compared with the contact temperature measurement method, infrared temperature measurement has the advantages of fast response time, non-contact, safe use and long service life.Non contactInfrared temperature instrumentIt includes three series: portable, online and scanning, and is equipped with various options and computer software. In each series, there are various models and specifications.Among various types of thermometers with different specifications, it is very important for users to correctly select the infrared thermometer model.
In 1672, people found sunlight（white light）It is composed of various colors of light. At the same time,NewtonThe famous conclusion that monochromatic light is simpler in nature than white light is made.The sunlight (white light) is decomposed into red, orange, yellow, green, cyan, blue, purple and other colors by using a beam splitting prismMonochromatic light。In 1800, the British physicist FW.Hershel Infrared ray was discovered when studying various colored light from the point of view of heat.When studying the heat of various colored lights, he deliberately blocked the only window of the darkroom with a dark board, and opened a rectangular hole on the board, in which a light splitting prism was installed.When sunlight passes through the prism, it is decomposed into colored light bands, and thermometers are used to measure the heat contained in different colors of light bands.In order to compare with the ambient temperature, Herschel uses several thermometers near the color light band as comparison thermometers to measure the ambient temperature.During the experiment, he accidentally found a strange phenomenon: a branch placed outside the red light bandthermometer, higher than other indoor temperatures.After repeated tests, this so-called high temperature zone with the most heat is always located outside the red light at the edge of the light band.So he announced that in addition to visible light, there is also an invisible "hot wire" in the radiation from the sun. This invisible "hot wire" is located outside the red light, called infrared light.Infrared is an electromagnetic wave withradio wavesWith the same essence as visible light, the discovery of infrared light is a leap in human understanding of nature, which has opened up a new broad road for the research, utilization and development of infrared technology.
The wavelength of infrared ray ranges from 0.76 μ m to 100 μ m. According to the wavelength range, it can be divided into four categories: near infrared ray, mid infrared ray, far infrared ray and very far infrared ray. Its position in the continuous spectrum of electromagnetic wave isradio wavesAndvisible lightArea between.Infrared radiation is one of the most widespreadelectromagnetic waveRadiation is based on the fact that any object will generate its own molecules and atoms' irregular movement in a conventional environment, and constantly radiate thermal infrared energy. The more intense the movement of molecules and atoms, the greater the radiation energy. On the contrary,radiationThe smaller the energy.
Objects whose temperature is above absolute zero will radiate infrared ray due to their molecular motion.Use an infrared detector to detect objectsradiationThe power signal of is converted intoelectrical signalThen, the output signals of the imaging device can completely one-to-one simulate the spatial distribution of the temperature on the surface of the scanned object, which is processed by the electronic system and transmitted to the display screen to obtain the thermal image corresponding to the thermal distribution on the surface of the object.By using this method, remote thermal state image imaging, temperature measurement and analysis of the target can be realized.[1]
development
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In 1800, the British physicist FW. Herschel foundinfraredSince then, it has opened up a broad road for human beings to apply infrared technology.staythe Second World WarChinese, for GermanInfrared image tubeAsPhotoelectric converterActivenight vision sightAnd infrared communication equipment, laying the foundation for the development of infrared technology.
After World War II, the first generation of infrared imaging device for military use, called FLIR, was first developed by the United States after nearly a year of explorationmechanical systemInfrared radiation scanning of the measured target.Photonic detectors receive two-dimensional infrared radiation signs, and form video image signals after photoelectric conversion and a series of instrument processing.The original form of this system is a non real-time automatic temperature distribution recorder. Later, with the development of InSb and Ge mercury doped photodetectors in the 1950s, high-speed scanning and real-time display of target thermal images began to appear.
In the early 1960s, Sweden successfully developed the second generation infrared imaging device, which added the function of temperature measurement on the basis of the infrared vision system. It is calledInfrared thermal imager。
At first, for reasons of confidentiality, it was also limited to military use in developed countries. The thermal imaging device put into use can detect the target of the other party, camouflage target and high-speed moving target in the dark or thick curtain clouds.Due to the support of national funds, the research and development cost invested is very high, and the cost of instruments is also very high.Later, considering the practicability in the development of industrial production, combined with the characteristics of industrial infrared detection, the cost of the instrument was reduced.Measures such as reducing the production cost and improving the image resolution by reducing the scanning speed are gradually developed into the civil field according to the civil requirements.
In the mid-1960s, the first industrial real-time imaging system (THV) was developedliquid nitrogenCooling, powered by 110V power supply voltage, weighs about 35kg, so the portability in use is very poor. After several generations of improvement of the instrument, the infrared thermal imager developed in 1986 no longer needs liquid nitrogen or high-pressure gas, but uses thermoelectric cooling, which can be powered by batteries;The full function thermal imager launched in 1988 integrates temperature measurement, modification, analysis, image acquisition and storage, and weighs less than 7kg. The function, accuracy and reliability of the instrument have been significantly improved.
In the mid-1990s, the United States first successfully developed a new infrared thermal imager (CCD) that was converted from military technology (FPA) to civilian use and commercialized. It is a condensing imaging device with focal plane array structure. Its technical functions are more advanced. When measuring temperature on site, it only needs to aim at the target to capture images, and store the above information on the PC card in the machine to complete all operations,The setting of various parameters can be returned to indoor software to modify and analyze the data, and finally the test report can be obtained directly. Due to the technical improvement and structural change, the complex mechanical scanning has been replaced, and the weight of the instrument has been less than two kilograms. In use, like a hand-held camera, it can be easily operated by one hand.
Today,Infrared thermographyThe system has been widely used in electric power, fire protection, petrochemical, medical and other fields.Infrared thermal imagerIt is playing an important role in the development of the world economy.[1]
Thermal imager
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The infrared thermal imager usesInfrared detectorOptical imaging objective lens and opto mechanical scanning system (advanced focal plane technology omits the opto mechanical scanning system) receive the infrared radiation energy distribution of the measured target and reflect it on the photosensitive element of the infrared detectoroptical system andInfrared detectorThere is an opto mechanical scanning mechanism (the focal plane thermal imager does not have this mechanism) to scan the infrared thermal image of the measured object, and focus on the unit or sub unitPhotodetectorThe infrared radiant energy is converted into electrical signal by the detector, and the infrared thermal image is displayed through the TV screen or monitor after amplification, conversion or standard video signal.This thermal image corresponds to the thermal distribution field on the surface of the object;Essentially, all parts of the measured target objectinfrared radiationBecause the signal of the thermal image distribution map is very weak, it lacks hierarchy and stereoscopic sense compared with the visible image. Therefore, in order to judge the infrared thermal distribution field of the measured target more effectively in the actual action process, some auxiliary measures are often used to increase the practical functions of the instrument, such as image brightness and contrast control, real standard correction, pseudo color rendering and other technologies.[1]
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Infrared thermal imagers are generally spectroscopic scanning imaging systems and non scanning imaging systems.The opto mechanical scanning imaging system uses unit or multi element (the number of elements is 8, 10, 16, 23, 48, 55, 60, 120, 180 or more) photoconductive or photovoltaic infrared detectors. When using unit detectors, the speed is slow, mainly because the frame amplitude response time is not fast enough. Multi element array detectors can be used as high-speed real-time thermal imagers.Non scanning imaging thermal imagers, such as the focal plane thermal imager of array staring imaging launched in recent years, belong to a new generation of thermal imaging devices, which are much better than the opto mechanical scanning thermal imager in performance, and have the trend to gradually replace the opto mechanical scanning thermal imager.Its key technology is that the detector is composed ofMonolithic integrated circuitComposition, the whole field of vision of the measured object is focused on it, and the image is clearer and more convenient to use. The instrument is very compact and light, and has the functions of automatic focusing image freezing, continuous amplification, point temperature, line temperature, isothermal and voice annotation images. The instrument uses a PC card, with a storage capacity of up to 500 images.
Infrared thermal TV isInfrared thermal imagerOne of.Infrared thermal TV is set byPyroelectric camera tube(PEV) receives the infrared radiation on the surface of the measured target object, and converts the invisible thermal image of the thermal radiation distribution in the target into a video signal. Therefore, the pyroelectric camera tube is the optical key device of the infrared thermal television. It is a real-time imaging, wide spectrum imaging (with good frequency response to 3~5 μ m and 8~14 μ m) thermal imaging device with medium resolution, mainly composed of lensThe target surface and the electron gun are composed of three parts.Its technical function is to focus and image the infrared radiation line of the measured target to the pyroelectric camera tube through the lens, and use the normal temperature thermal television detector andelectron beamScanning and target imaging technology.[1]
Main parameters of thermal imager
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1. Working band;Operating band refers to the response of the selected infrared detector in the infrared thermal imagerwavelengthThe area is generally 3-5 μ m or 8-12 μ m.
2. Detector type;Detector type refers to one usedInfrared device。It is a photoconductive or photovoltaic infrared detector using single or multi-component (8, 10, 16, 23, 48, 55, 60, 120, 180, etc.) elements, including lead sulfide (PbS), lead selenide (PnSe), indium telluride (InSb), mercury cadmium telluride (HgCdTe), lead tin telluride (PbSnTe), germanium doped (Ge: X) and silicon doped (Si: X).
3. Scanning mode;Generally, it is China's standard television system,PAL system。
4. Display mode;It refers to whether the screen display is black and white or false color.
5. Temperature measurement range;It refers to the range of the lowest and highest temperature values of the measured temperature.
6. Temperature measurement accuracy;fingerInfrared thermal imagerThe percentage of the ratio between the maximum error of temperature measurement and the instrument range.
7. Maximum working time;The infrared thermal imager allows continuous working time.[2]
Infrared thermometry
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1. Types of infrared temperature measuring instruments
Infrared temperature instrumentThere are three main types of devices: infrared thermal imager, infrared thermal television, and infrared thermometer (spot thermometer).In the 1960s, China successfully developed the first infrared thermometer, and since the early 1980s, it has successively produced small target, long-distance thermometers suitable for the characteristics of electric power production, such as Xiguang IRT-1200D, HCW-III, HCW-V;YHCW-9400;WHD4015 (double aiming, target D 40mm, up to 15m), WFHX330 (optical aiming, target D 50mm, up to 30m).PM-20, 30, 40, 50 and HAS-201 thermometers manufactured in the United States;Sweden AGA TPT20, 30, 40, 50, etc. are also widely used.DL － 500E can be applied to 110 ～ 500kV substation equipment with clear image and accurate temperature.Infrared thermal imagers mainly include Japanese TVS － 2000, TVS － 100, American PM － 250, Swedish AGA － THV510, 550, 570.The domestic infrared thermal imager has been successfully developed in Kunming, and its localization has been realized.
Understanding the working principle, technical indicators, environmental working conditions, operation and maintenance of infrared thermometers is the basis for users to correctly select and use infrared thermometers.The optical system gathers the infrared radiation energy of the target in its field of view. The size of the field of view is determined by the optical parts and position of the thermometer.The infrared energy is focused on the photoelectric detector and converted into the corresponding electrical signal.The signal is converted into the temperature value of the measured target after being corrected by the amplifier and signal processing circuit according to the internal algorithm of the instrument and the target emissivity.In addition, the environmental conditions of the target and the thermometer, such as temperature, atmosphere, pollution, interference and other factors, should also be taken into account to affect the performance indicators and the correction methods.
All objects whose temperature is higher than absolute zero are constantly emitting infrared radiation energy to the surrounding space.The size of the infrared radiation energy of an object and its distribution by wavelength are closely related to its surface temperature.Therefore, the surface temperature of an object can be measured accurately by measuring its infrared energy, which is the objective basis of infrared radiation temperature measurement.
Blackbody radiationLaw: Blackbody is an idealized radiator, which absorbs radiation energy of all wavelengths, has no reflection and transmission of energy, and its surface emissivity is 1.It should be pointed out that there is no real blackbody in nature, but in order to understand and obtain the distribution law of infrared radiation, the appropriate model must be selected in theoretical research, which isPlonkThe quantized oscillator model of body cavity radiation is proposed, thus the Planck's law of blackbody radiation is derived, that is, the spectral radiance of blackbody expressed by wavelength, which is the starting point of all infrared radiation theories, so it is calledBlackbody radiation law 。
Influence of object emissivity on radiation thermometry: almost all actual objects in nature are not black bodies.In addition to the radiation wavelength and the temperature of the object, the radiation amount of all actual objects is also related to the material type, preparation method, thermal process, surface state and environmental conditions of the object.Therefore, in order toBlackbody radiation law Applicable to all actual objects, a proportional coefficient related to material properties and surface state, namely emissivity, must be introduced.This coefficient represents the closeness between the thermal radiation of the actual object and the blackbody radiation, and its value is between zero and less than 1.According to the radiation law, as long as the emissivity of the material is known, the infrared radiation characteristics of any object can be known.
The main factors affecting emissivity are: material typeSurface roughness, physical and chemical structure, material thickness, etc.
When measuring the temperature of a target with an infrared radiation thermometer, first measure the infrared radiation of the target in its band range, and then calculate the temperature of the measured target with the thermometer.The monochromatic thermometer is proportional to the radiation in the band;The two-color thermometer is proportional to the radiation ratio of the two wavebands.
Infrared system: Infrared thermometer is composed ofoptical system 、Photodetector、signal amplifierandsignal processing , display output, etc.The optical system gathers the infrared radiation energy of the target in its field of view. The size of the field of view is determined by the optical parts of the thermometer and their positions.The infrared energy is focused on the photodetector and transformed into the correspondingelectrical signal。The signal passes through the amplifier and signal processing circuit, andalgorithmAnd target emissivity are converted into the temperature value of the measured target.[2]
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In order to obtain accurate temperature readings, the distance between the thermometer and the test target must be within an appropriate range. The so-called "spot size" is the area of the measuring point of the thermometer.The farther you are from the target, the larger the spot size.The ratio of distance to light spot size, or D: S.On the laser collimator type thermometer, the laser point is above the target center, with an offset distance of 12mm (0.47 inch).
When determining the measurement distance, ensure that the target diameter is equal to or greater than the size of the measured light spot.The distance between "object 1" and the measuring instrument is positive, because the size of the target is slightly larger than the measured point.The distance of "object 2" is too far, because the target is smaller than the size of the measured light spot, that is, the thermometer is also measuring the background object, thus reducing the accuracy of the reading.[2]
(1) Performance indicators, such as temperature range, spot size, working wavelength, measurement accuracy, window, display and output, response time, protection accessories, etc;
(2) Environment and working conditions, such as ambient temperature, window, display and output, protective accessories, etc;
(3) Other options, such as ease of use, maintenance and calibration performance and price, also have a certain impact on the selection of thermometers.
With the development of technology,Infrared temperature instrumentThe best design and new progress provide users with various functions and multi-purpose instruments, expanding the choice.Other options, such as ease of use, maintenance and calibration performance, and price.When selecting the thermometer model, first determine the measurement requirements, such as the measured target temperature, the measured target size, the measured distance, the measured target material, the target environment, response speed, measurement accuracy, portable or online, etc;Select the instrument model that can meet the above requirements from the comparison of existing thermometers of various models;Select the best combination of performance, function and price among many models that can meet the above requirements.[2]
Key points for use
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1. Determine the temperature measurement range
Determine the temperature measurement range: the temperature measurement range is the most important performance index of the thermometer.The range of some thermometers can reach - 50 ℃ -+3000 ℃, but this cannot be determined byInfrared temperature instrumentTo complete.Each type of thermometer has its own specific temperature range.Therefore, the measured temperature range of users must be accurate and comprehensive, neither too narrow nor too wide.according toBlackbody radiation law In the short wave band of the spectrum, the change of radiation energy caused by temperature will exceed the change of radiation energy caused by emissivity error. Therefore, short wave should be selected as far as possible when measuring temperature.Generally speaking, the narrower the temperature measurement range is, the higher the resolution of the output signal of monitoring temperature is, and the accuracy reliability is easy to solve.If the temperature measurement range is too wide, the temperature measurement accuracy will be reduced.For example, if the measured target temperature is 1000 ℃, first determine whether it is online or portable, and if it is portable.There are many models meeting this temperature, such as 3iLR3, 3i2M, 3i1M.If the measurement accuracy is the main factor, it is better to select the 2M or 1M model, because if the 3iLR model is selected, its temperature measurement range is very wide, and its high-temperature measurement performance will be poor;If the user needs to take care of the low temperature target in addition to measuring the 1000 ℃ target, he has to choose 3iLR3.
Determination of target size
Infrared temperature instrumentAccording to the principle, it can be divided into monochrome thermometers and two-color thermometers (radiation colorimetric thermometers).For the monochrome thermometer, the area of the measured object shall be full of the field of view of the thermometer when measuring temperature.It is recommended that the size of the measured object exceed 50% of the field of view.If the target size is smaller than the field of view, the background radiation energy will enter the optoacoustic symbol of the thermometer to interfere with the temperature measurement reading, causing errors.On the contrary, if the target is larger than the field of view of the thermometer, the thermometer will not be affected by the background outside the measurement area.For colorimetric thermometers, if the field of view is not full, and there are smoke, dust, and barriers on the measurement path, which have attenuation on the radiation energy, the measurement results will not be significantly affected.For small targets in motion or vibration, colorimetric thermometers are the best choice.This is due to the small diameter and flexibility of light rays, which can transmit radiant energy through curved, blocked and folded channels.
For some thermometers, the temperature is determined by the ratio of the radiant energy in the band of two independent wavelengths.Therefore, when the measured target is small, not full of the scene, and there is smoke, dust, and barriers on the measurement path that attenuate the radiation energy, the measurement results will not be affected.Even when the energy is reduced by 95%, the required temperature measurement accuracy can still be guaranteed.For small targets that are in motion or vibration;Sometimes the target moves in the field of view, or may partially move out of the field of view. Under this condition, the best choice is to use a two-color thermometer.If it is impossible to aim directly between the thermometer and the target, and the measurement channel is bent, narrow, blocked, etc., the two-color optical fiber thermometer is the best choice.This is due to its small diameter and flexibility, which can transmit light radiation energy in curved, blocked and folded channels. Therefore, it can measure targets that are difficult to approach, in poor conditions or close to electromagnetic fields.
The distance coefficient is determined by the ratio of D: S, that is, the ratio of the distance D between the probe of the thermometer and the target to the diameter of the measured target.If the thermometer must be installed far away from the target due to environmental conditions, and it is necessary to measure small targets, a thermometer with high optical resolution should be selected.The higher the optical resolution, that is, the higher the D: S ratio, the higher the cost of the thermometer.RaytekInfrared temperature instrumentD: S ranges from 2:1 (low distance coefficient) to more than 300:1 (high distance coefficient).If the thermometer is far away from the target and the target is small, the thermometer with high distance coefficient should be selected.For thermometers with fixed focal length, the minimum position of the light spot is at the focal point of the optical system, and the light spot near and far from the focal point will increase.There are two distance coefficients.Therefore, in order to accurately measure the temperature at the distance close to and far from the focus, the size of the measured target should be larger than the spot size at the focus. The zoom thermometer has a minimum focus position, which can be adjusted according to the distance to the target.If D: S is increased, the received energy will be reduced. If the receiving aperture is not increased, the distance coefficient D: S is difficult to be increased, which will increase the instrument cost.
4. Determine wavelength range
The emissivity and surface characteristics of the target material determine thespectrumThe corresponding wavelength is low or variable for high reflectivity alloy materialsEmissivity。In high temperature area, measureMetallic materialsThe best wavelength of is near infrared, which can be 0.8~1.0μm。1.6 μ m, 2.2 μ m and 3.9 μ m can be selected for other temperature zones.Since some materials are transparent at a certain wavelength, infrared energy will penetrate these materials, so special wavelength should be selected for this material.For example, 1.0 μ m, 2.2 μ m and 3.9 μ m (the measured glass must be very thick, otherwise it will penetrate) wavelengths are selected for measuring the internal temperature of glass;5.0 μ m for measuring glass surface temperature;8~14 μ m is suitable for low temperature measurement.As measuredPolyethylene plastic3.43 μ m for film, 4.3 μ m or 7.9 μ m for polyester, and 8-14 μ m for thicker than 0.4 mm.For example, 4.64 μ m narrow band is used for measuring CO in the flame and 4.47 μ m for measuring NO2 in the flame.
5. Determine response time
Response time representationInfrared temperature instrumentFor the measured temperature changereaction rate , defined as the time required to reach 95% of the energy of the final reading, which is related toPhotodetector, signal processing circuit and time constant of display system.Some infrared thermometers have a response time of 1ms, which is much faster than the contact thermometry.If the target'sMovement speedFast response infrared thermometers should be selected when fast heating targets are measured or quickly heated, otherwise the measurement accuracy will be reduced if the signal response is not enough.However, not all applications require fast response infrared thermometers.For static or target thermal process with thermal inertia, the response time of the thermometer can be relaxed.Therefore, the response time of the infrared thermometer should be selected according to the situation of the measured target.The response time is determined mainly according to the movement speed and temperature change speed of the target.The response time of thermometers can be relaxed for static targets or targets with thermal inertia, or the speed of existing control equipment is limited.
6. Signal processing function
Since discrete processes (such as part production) are different from continuous processesInfrared temperature instrumentMultiple signal processing functions (such as peak holding, valley holding and average value) are available. For example, when measuring the temperature of bottles on the conveyor belt, peak holding is required, and its temperature output signal is transmitted to the controller.Otherwise, the thermometer reads the lower temperature between bottles.If usedpeak valueKeep, set the response time of the thermometer to be slightly longer than the time interval between bottles, so that at least one bottle is always being measured.
7. Environmental conditions considerations
The environmental conditions where the thermometer is located have a great impact on the measurement results, which should be considered and properly solved, otherwise the temperature measurement accuracy will be affected or even damaged.When the ambient temperature is high and there is dust, smoke and steam, the protective sleeve, water coolingAir cooling system, air blower and other accessories.These accessories can effectively solve the environmental impact and protect the thermometer to achieve accurate temperature measurement.When determining accessories, standardized services shall be required as far as possible to reduce installation costs.When smoke, dust or other particles reduce the measurement energy signal under noise, electromagnetic field, vibration or difficult to access environmental conditions, or other harsh conditions, the optical fiber two-color thermometer is the best choice.Colorimetric thermometer is the best choice.In case of noise, electromagnetic field, vibration and inaccessible environmental conditions, or other severe conditions, light colorimetric thermometers should be selected.
In sealed or dangerous material applications (such as containers or vacuum boxes), thermometers observe through windows.The material must have sufficient strength and be able to pass the working wavelength range of the thermometer used.It is also necessary to determine whether the operator also needs to observe through the window, so it is necessary to select appropriate installation location and window materials to avoid mutual influence.In low temperature measurement applications, Ge or Si materials are usually used as windows, which are impervious to visible light and cannot be used by the human eye to observe the target through the window.If the operator needs to pass through the window target, optical materials that transmit both infrared radiation and visible light shall be used. For example, optical materials that transmit both infrared radiation and visible light, such as ZnSe or BaF2, shall be used as window materials.
When there is flammable gas in the working environment of the thermometer, the intrinsically safe type can be selectedInfrared temperature instrumentSo as to carry out safety measurement and monitoring in a certain concentration of flammable gas environment.
In the case of harsh and complex environmental conditions, the system with separate temperature measuring head and display can be selected for easy installation and configuration.The signal output form matching the current control equipment can be selected.
8. Calibration of Infrared Radiation Thermometer
The infrared thermometer must be calibrated to display the temperature of the measured target correctly.Generally, the calibration cycle of infrared temperature measurement is one year. It is recommended to use a blackbody furnace with cavity shape and emissivity of 0.995 to accurately calibrate the infrared thermometer.If the thermometer used is out of tolerance during use, it shall be returned to the manufacturer or the maintenance center for recalibration.[2]
application
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The subminiature temperature calibrator has overcome the technical difficulties caused by the miniaturization to the maximum extent, enabling the user to carry it to every corner of the industrial site to carry out on-site calibration for the temperature probe that needs inspection, maintenance and calibration, avoiding the trouble of disassembling it back to the laboratory for comparison calibration and reinstalling the original system,It can greatly improve work efficiency, save time, improve the availability of equipment and systems, and provide excellent maintenance and calibration means for on-site automatic control engineers.
AIKOM series subminiature temperature calibrator has changed the traditional temperature calibration mode. It has a wide range of applications, covering every link of temperature measurement and calibration in the industrial field, and provides an adjustable analog temperature sourceProduct quality assurance, prevention of misoperation of automatic protection setting value in industrial process and fault finding provide important inspection means.Especially for the fixed value inspection of temperature switch, it can be fast, accurate and convenient. Its application fields involve:
Electric power: temperature protection and signal transmission of coal-fired power plants, gas-fired heating power plants, hydropower stations, nuclear power plants, regional heating pipe networks, large power transformers, etc.
Metallurgy: aluminum plant, copper plant, steel plant, etc.
General industry: refrigerator factory, air conditioning factory, refrigerator factory, brewery, pharmaceutical factory, automobile factory.
Temperature element manufacturer: platinum resistance, thermocouple and compensation wire cable, temperature switchTemperature sensormanufacturer.
Transportation: aircraft maintenance at the airport, large transport power system maintenance, ocean shipping are used as in service maintenance measurement means.
Aikom products are mainly launched in four models of two series (PD-1000/PD-2000) in the Chinese market.PD-1025 is characterized bySemiconductor refrigeration technologyUnder the ambient temperature of 20 ℃, the minimum temperature can reach - 25 ℃, and the high temperature can reach 105 ℃.PD － 2300 is characterized by deep effective size of the tank, 24V DC heating element, good safety and small electrostatic impact, use of internal fan cooling without external compressed air, use of conical tank and heat transfer sleeve, extremely small thermal resistance, fast heat transfer, special compensation of temperature field, and temperature range from ambient temperature to 400 ℃.
The feature of the PD － 2800 is that it can provide a high temperature source of 720 ℃, with fast temperature rising and falling speed, convenient use, simple operation, economic and practical, especially suitable for industrial field use.However, since the "肒肒肒肒肒肒肒肒肒肒肒肒肒肒肒36?BR>PD － 2600 is the latest high-accuracy, high stability and high temperature tank launched by Aikom. The calibrated accuracy is plus or minus 0.3 ℃ full scale nonlinear error.It can also purchase a software to realize ten stage programmable temperature rise and fall rate control, and to simulate and realize the actual industrial process flow.The 1-5V process voltage signal can also be input to change the set value of the tank temperature control unit to form a loop control.In a word, it is a powerful computer program-controlled small portable thermostatic bath, and it is a representative work of excellent performance among similar products in the world.
The infrared imaging detection technology can be used for non-contact detection of running equipment, photographing the distribution of its temperature field and measuring the temperature value of any part, so as to diagnose various external and internal faults. It has the advantages of real-time, telemetry, intuitive and quantitative temperature measurement, and is used to detect power plants, substations andTransmission lineThe operating equipment and electrified equipment of are very convenient and effective.
The infrared temperature recording method is used to detect online electrical equipment by thermal imager.Infrared thermography is a new technology used in industry for nondestructive detection, testing equipment performance and mastering its operating state.Compared with traditional temperature measurement methods (such as thermocouples, wax chips with different melting points, etc. placed on the surface or inside the body of the measured object), the thermal imager can detect the temperature of the hot spot in real time, quantitatively, and online within a certain distance. Through scanning, it can also draw a thermal image of the temperature gradient of the equipment in operation. Moreover, it has high sensitivity, is not subject to electromagnetic interference, and is convenient for on-site use.It can detect thermal faults of electrical equipment with 0.05 ℃ high resolution in a wide range of - 20 ℃~2000 ℃, and reveal such problems as heating of wire joints or clamps, and local hot spots in electrical equipment.
Infrared diagnosis technology of charged equipment is a new subject.It is a comprehensive technology that uses the heating effect of charged equipment and special equipment to obtain the infrared radiation information sent from the equipment surface, and then judge the equipment condition and defect nature.[2]
Factory application
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Temperature, pressure, current, voltage, etc. are familiar to peopleBasic physical quantity。In the industrial field, it has a great impact on product quality, whole process control, etc. Among these basic physical quantities, it is much more difficult to measure and calibrate the temperature.This is because the influence of the "insulation" and "heat transfer" of the temperature system itself is very complex, which results in the large volume of the temperature measurement calibration system, the long stability time required, and the difficulty in improving the accuracy.It is not like the pressure system, as long as the leakage of the pressure transmission pipeline is ensured, the internal and external pressures can not affect each other, so it is easy to realize the rapid transmission of pressure. The stability time only takes a few milliseconds and the measurement accuracy can easily reach more than a few thousandths.
Let's take a look at a high-precision and highly stable temperature measurement system. It is impossible to ensure its "adiabatic", that is, to completely prevent heat transfer.People usually make a large enough volume think that the temperature field gradient of a small volume at its internal mass center is sufficiently balanced when it reaches thermal equilibrium, which is one of the important reasons why the volume of the temperature calibration source is huge.In addition, the heat transmission of a temperature system is also very complex, which is often completed by heat conduction, convection and radiation. It can be imagined that it is almost impossible to make its temperature suddenly change and reach the thermal balance at one time. This is the conventional temperature calibration source. In order to ensure a certain uniformity of the temperature field, the device is large in size and takes a long time to rise and fall,The inspection, maintenance and calibration of the temperature measurement system in the industrial field are time-consuming, laborious and expensive, and the impact is caused by multiple disassembly and assembly of the temperature probeSystem reliability。
Industry hopes to have a small and light elephantPressure calibratorThe same portable temperature correction source (thermostat), however, this small portableTemperature calibratorThe disadvantages of poor uniformity and stability of temperature field caused by volume reduction must be overcome. To make temperature rise and fall stable in a relatively short time, there must be close cooperation between heating and cooling, which can reduce the time of temperature rise and fall. Cooling and heating in a miniaturized constant temperature bath also affect the uniformity of temperature field,The portable temperature corrector with ultra small volume, certain accuracy and fast temperature rise and fall is a field application instrument that has been eagerly explored and developed in the field of temperature measurement technology for many years.
Infrared detection technologyIt is a key promotion project of national scientific and technological achievements during the Ninth Five Year Plan period. Infrared detection is an online monitoring (uninterruptible) high-tech detection technology, which integrates photoelectric imaging technologycomputer technology、image processingThe technology is integrated to receive the infrared ray (infrared radiation) emitted by the object and display its thermal image on the fluorescent screen, so as to accurately judge the temperature distribution on the surface of the object. It has the advantages of accuracy, real-time and speed.Any object, due to the movement of its own molecules, constantly radiates infrared heat energy, thus forming a certain temperature field on the surface of the object, commonly known as "thermal image".The infrared diagnosis technology is to measure the temperature of the equipment surface and the distribution of the temperature field by absorbing this infrared radiation energy, so as to judge the heating condition of the equipment.There are many test equipment applying infrared diagnostic technology, such asInfrared temperature instrument, infrared thermal TV, infrared thermal imager, etc.Like infrared thermal TVInfrared thermal imagerAnd other equipment utilizationThermal imaging technologyTransforming this invisible "thermal image" into a visible image makes the test effect intuitive and has high sensitivity. It can detect subtle changes in the thermal state of the equipment, accurately reflect the internal and external heating conditions of the equipment, and has high reliability. It is very effective for discovering hidden dangers of the equipment.
The infrared diagnosis technology can reliably predict the early fault defects and insulation performance of electrical equipment, making the traditional electrical equipmentPreventive testMaintenance (preventive test was introduced in the 1950sFormer Soviet UnionIt is also the development direction of modern electric power enterprises.In particular, the development of large units and ultra-high voltage is related to the reliable operation of the power systempower gridStability, put forward higher and higher requirements.With the continuous development, maturity and improvement of modern science and technology, infrared condition monitoring and diagnosis technology has the characteristics of long-distance, non-contact, non sampling, non disassembly, and accurate, fast, intuitive, real-time online monitoring and diagnosis of most faults of electrical equipment (it can cover almost all kinds of fault detection of electrical equipment).It is highly valued by the domestic and foreign power industry (an advanced condition based maintenance system widely used in the late 1970s abroad), and has developed rapidly.The application of infrared detection technology is of great significance in improving the reliability and effectiveness of electrical equipment, improving the economic benefits of operation, and reducing maintenance costs.It is a good means widely used in the field of predictive maintenance, and can also make the maintenance level and equipment health level to a higher level.[2]
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To measure the temperature, align the instrument with the object to be measured, press the trigger to read the temperature data on the LCD of the instrument, and ensure that the ratio of distance to spot size and the field of view are arranged.
1. Only the surface temperature is measured, and the infrared thermometer cannot measure the internal temperature.
2. The wavelength is above 5um and cannot be transmittedquartz glassFor temperature measurement, the glass has special reflection and transmission characteristics, and accurate infrared temperature readings are not allowed.However, the temperature can be measured through the infrared window.It is better not to use infrared thermometers to measure the temperature of bright or polished metal surfaces (stainless steel, aluminum, etc.).
3. Locate hot spots and discoverhotspotThe instrument aims at the target, and then scans up and down on the target until the hot spot is determined.
4. Pay attention to environmental conditions: steam, dust, smoke, etc.It blocks the optical system of the instrument and affects the accurate temperature measurement.
5. Ambient temperature: if the thermometer is suddenly exposed to the ambient temperature difference of 20 ℃ or higher, the instrument is allowed to adjust to the new ambient temperature within 20 minutes.[2]
