CN216622150U - Formaldehyde concentration measuring device - Google Patents
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- CN216622150U CN216622150U CN202123057931.XU CN202123057931U CN216622150U CN 216622150 U CN216622150 U CN 216622150U CN 202123057931 U CN202123057931 U CN 202123057931U CN 216622150 U CN216622150 U CN 216622150U
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Abstract
The utility model relates to the field of air quality measuring devices, and provides a formaldehyde concentration measuring device which comprises a light source, a gas concentration detection cavity, an optical system for coupling and reflecting light, a spectrometer and a calculating unit, wherein the optical system is arranged on two sides of the gas concentration detection cavity; one end of the gas concentration detection cavity is provided with a gas inlet, and the other end of the gas concentration detection cavity is provided with a gas outlet; light emitted by the light source enters the gas concentration detection cavity after passing through an optical system arranged on one side of the gas concentration detection cavity; the output end of the optical system arranged at the other end of the gas concentration detection cavity is connected with the input end of the spectrometer through an optical fiber, and the output end of the spectrometer is connected with the input end of the calculation unit. The method is based on the optical cavity enhanced absorption spectrum technology, and the concentration of formaldehyde in the air in the environment to be detected is determined by measuring the spectrum of light passing through the cavity without the gas to be detected and the spectrum of light passing through the cavity with the gas to be detected.
Description
Technical Field
The utility model relates to the field of air quality measuring devices, in particular to a formaldehyde concentration measuring device.
Background
Formaldehyde is a colorless and pungent gas, and mainly comes from various adhesives, such as artificial boards, floors, newly-placed furniture and the like. Many of the newly-decorated indoor air is free of large amounts of formaldehyde gas. In 2004, the world health organization issued reports on carcinogenic formaldehyde, raising formaldehyde to the highest risk level of carcinogenic substances. Nowadays, the influence of indoor formaldehyde on human body is also receiving much attention because of frequent malignant injury events caused by harmful gases such as indoor formaldehyde. Therefore, the detection of formaldehyde concentration in a room is also a very hot technique.
The current means for detecting indoor formaldehyde concentration mainly comprise a chemical method, a power-free simple monitor and an instrumental analysis method. The classical chemical method has high sensitivity and strong anti-interference performance, but needs sampling and is brought back to a laboratory for analysis, and the measurement result cannot be directly obtained on site. The unpowered simple monitor is ideal, mainly depends on formaldehyde vapor diffusion in the environment to adsorb and sample, but the reliability of the unpowered simple monitor needs to be researched. The instrument analysis principle is the main development direction of an indoor formaldehyde monitoring method, and the existing formaldehyde concentration detector mainly adopts an air suction pump matched with a rotating motor to suck gas and then adopts a formaldehyde sensor to detect the formaldehyde concentration. The monitoring method has the advantages of high sensitivity, accurate quantification, rapid detection and convenient market popularization and application. However, the existing formaldehyde concentration detector is generally large in size and difficult to carry at any time when the formaldehyde concentration measuring operation is carried out.
SUMMERY OF THE UTILITY MODEL
The utility model provides a formaldehyde concentration measuring device for overcoming the defects that a formaldehyde concentration detector in the prior art is large in size and difficult to carry at any time for formaldehyde concentration measuring operation.
In order to solve the technical problems, the technical scheme of the utility model is as follows:
a formaldehyde concentration measuring device comprises a light source, a gas concentration detection cavity, an optical system for coupling and reflecting light, a spectrometer and a calculating unit, wherein the optical system is arranged on two sides of the gas concentration detection cavity; one end of the gas concentration detection cavity is provided with a gas inlet, and the other end of the gas concentration detection cavity is provided with a gas outlet; light emitted by the light source enters the gas concentration detection cavity after passing through the optical system arranged on one side of the gas concentration detection cavity; the output end of the optical system arranged at the other end of the gas concentration detection cavity is connected with the input end of the spectrometer through an optical fiber, and the output end of the spectrometer is connected with the input end of the calculation unit.
In the technical scheme, gas to be measured enters a cavity from a gas inlet arranged in a gas concentration detection cavity, a light source emits stable and continuous near ultraviolet light, light rays enter the gas concentration detection cavity after forming parallel light through an optical system, the light rays are reflected for multiple times in a resonant cavity formed by the optical system arranged on two sides of the gas concentration detection cavity, transmitted light rays leave the resonant cavity through the optical system on the other side of the gas concentration detection cavity and are output through optical fibers, after formaldehyde gas in the cavity fully absorbs the incident light rays, the absorbed light rays are analyzed by a spectrometer, and finally data measured by the spectrometer are input into a calculation unit for data processing such as fitting calculation and the like, so that the formaldehyde content in indoor atmosphere is measured, and the online accurate measurement of the indoor formaldehyde concentration is realized. This technical scheme is based on light intensity reinforcing absorption spectrum technique, through the spectrum of measuring light through the chamber that does not contain the gas that awaits measuring to and light is through being full of the spectrum in the chamber of the gas that awaits measuring, and then the survey waits to detect the concentration of formaldehyde in the environment air.
Preferably, the optical system includes a first convex lens, a first high-reflectivity lens, a second convex lens and an optical filter, which are coaxially arranged along the optical axis direction. The first convex lens and the first high-reflectivity lens are arranged on one side of the gas concentration detection cavity, and emergent light rays of the light source are input into the gas concentration detection cavity through the first convex lens and the first high-reflectivity lens; the second high-reflectivity lens, the second convex lens and the optical filter are arranged on the other side of the gas concentration detection cavity, and emergent rays of the light source are output to the gas concentration detection cavity through the second high-reflectivity lens, the second convex lens and the optical filter; the first high-reflectivity lens and the second high-reflectivity lens are oppositely arranged to form a resonant cavity.
In this preferred scheme, first high reflectivity lens and the high reflectivity lens of second set up in opposite directions and form the resonant cavity, and first convex lens are used for getting into the resonant cavity behind the parallel light with incident ray, and light makes a round trip to reflect at the intracavity, and all can have a small part light to transmit out the resonant cavity through the high reflectivity lens of second during every turn reflection, through the gathering of second convex lens again, through optical fiber output behind the band-pass of light filter, utilize the spectrometer to gather and record the light intensity signal of output end at last.
As a preferred scheme, the device also comprises a first bracket and a second bracket, wherein the light source and the center of the first convex lens are coaxially fixed on the first bracket, and the first high-reflectivity lens is arranged on the first bracket through the translation adjusting bracket; the second high-reflectivity lens is arranged on the second support through the translation adjusting frame, and the centers of the second convex lens and the optical filter are coaxially fixed on the second support.
In this preferred scheme, first support and second support are used for erectting light source and optical system, and wherein first high reflectance lens and second high reflectance lens set up on first support, second support through translation alignment jig respectively for adjust the high reflectance lens in X direction and the ascending direction in Y direction.
As the preferred scheme, first support and second support are cavity structures, and the inboard that hugs closely first high reflectivity lens and second high reflectivity lens respectively on first support and the second support is provided with the sweep gas air inlet, and the sweep gas air inlet is connected with the sweep gas cylinder.
In the preferred scheme, when the device works and is idle, the purging gas in the gas cylinder enters the cavity through the purging gas inlet, and the purging gas is continuously introduced to purge the high-reflectivity mirror surface, so that the reflecting mirror is protected from being polluted or abraded.
Preferably, the purge gas inlet is provided with a mass flow controller.
In the preferred scheme, the sweeping gas with a certain flow rate is controlled by the mass flow controller to continuously blow into the formed gas film so as to protect the high-reflectivity mirror surfaces on the two sides of the resonant cavity.
As preferred scheme, connect through the bellows between first support, the second support and the gas concentration detection chamber, communicate between bellows and the gas concentration detection chamber.
In this preferred scheme, gas concentration detection chamber and bellows cavity for the gas that awaits measuring produces through the light path and fully absorbs.
As a preferred scheme, a particulate filter containing a filter membrane is arranged at the front end of the gas inlet of the gas concentration detection cavity; and a mass flow meter and an air pump are arranged at an air outlet of the gas concentration detection cavity.
In this preferred scheme, the gas that awaits measuring gets into the gas concentration through the air inlet after the filter membrane filters and detects the intracavity, avoids air impurity to get into the detection that the gas concentration detected the chamber and influence the light intensity signal. The small-sized air pump is used for pumping the gas in the gas concentration detection cavity. During actual measurement, the air suction pump can continuously suck out air from the air concentration detection cavity, the air inlet continuously extracts the air to be measured from the environment to be measured under the action of pressure, and the air to be measured enters the optical resonant cavity and fully absorbs incident light.
Preferably, the device further comprises a main power supply and a constant current source, and the output end of the main power supply is electrically connected with the power supply end of the light source through the constant current source. The main power supply and the constant current source provide constant current voltage for the light source.
As the preferred scheme, the device still includes the constant temperature module, and the constant temperature module includes temperature sensor, controller, control switch and refrigeration subassembly, and temperature sensor is connected with the light source, and temperature sensor's output is connected with the input of controller, and the output and the control switch of controller are connected, and control switch and refrigeration subassembly constitute the return circuit, and the refrigeration subassembly closely laminates with the light source.
In the preferred scheme, the temperature sensor is used for monitoring the temperature of the light source, and the controller judges whether to send a refrigeration instruction according to whether the monitored temperature value exceeds a set value; when the controller sends a refrigeration instruction, namely the controller sends a signal to the control switch, the control switch is closed, and the refrigeration assembly works and cools the light source. The whole constant temperature control is carried out by adopting PID instructions.
Preferably, the device further comprises a heat radiation fan, and the main power supply is electrically connected with the heat radiation fan.
In this preferred scheme, radiator fan is used for further discharging the heat that light source and refrigeration subassembly during operation produced, avoids during operation refrigeration subassembly because of overheated and damage.
Compared with the prior art, the technical scheme of the utility model has the beneficial effects that: the utility model is composed of optical devices with small volume and light weight, and the concentration of formaldehyde in the air in the environment to be detected is further determined by measuring the spectral information of light rays in the cavity filled with the gas to be detected, thereby meeting the requirement of portability while ensuring high detection accuracy and having the advantages of safety, high efficiency, reliability and stability.
Drawings
Fig. 1 is a schematic structural view of a formaldehyde concentration measuring apparatus of example 1.
Fig. 2 is a schematic structural view of the formaldehyde concentration measuring apparatus of example 2.
Fig. 3 is a schematic structural view of the formaldehyde concentration measuring apparatus of example 3.
Fig. 4 is a schematic circuit diagram of the formaldehyde concentration measuring apparatus of embodiment 3.
The system comprises a light source 1, a gas concentration detection cavity 2, a gas inlet 201, a gas outlet 202, an optical system 3, a first convex lens 301, a first high-reflectivity lens 302, a second high-reflectivity lens 303, a second convex lens 304, a light filter 305, a spectrometer 4, a calculation unit 5, a first support 6, a purge gas inlet 601, a mass flow controller 602, a second support 7, a purge gas inlet 701, a mass flow controller 702, a corrugated pipe 8, a total power supply 9, a constant current source 10, a constant temperature module 11, a temperature sensor 1101, a controller 1102, a control switch 1103, a refrigeration component 1104 and a cooling fan 12.
Detailed Description
The drawings are for illustrative purposes only and are not to be construed as limiting the patent;
for the purpose of better illustrating the embodiments, certain features of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product;
it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.
The technical solution of the present invention is further described below with reference to the accompanying drawings and examples.
Example 1
The present embodiment provides a formaldehyde concentration measuring device, as shown in fig. 1, which is a schematic structural diagram of the formaldehyde concentration measuring device of the present embodiment.
The formaldehyde concentration measuring device provided by the embodiment comprises a light source 1, a gas concentration detection cavity 2, an optical system 3 for coupling and reflecting light, a spectrometer 4 and a calculating unit 5, wherein the optical system 3 is arranged on two sides of the gas concentration detection cavity 2; one end of the gas concentration detection cavity 2 is provided with a gas inlet 201, and the other end of the gas concentration detection cavity 2 is provided with a gas outlet 202; light emitted by the light source 1 enters the gas concentration detection cavity 2 after passing through the optical system 3 arranged on one side of the gas concentration detection cavity 2; the output end of the optical system 3 arranged at the other end of the gas concentration detection cavity 2 is connected with the input end of the spectrometer 4 through an optical fiber, and the output end of the spectrometer 4 is connected with the input end of the calculating unit 5.
In this embodiment, the optical system 3 includes a first convex lens 301, a first high-reflectivity lens 302, a second high-reflectivity lens 303, a second convex lens 304, and an optical filter 305, which are coaxially disposed along the optical axis direction. The first convex lens 301 and the first high-reflectivity lens 302 are arranged on one side of the gas concentration detection cavity 2, and light emitted by the light source 1 sequentially passes through the first convex lens 301 and the first high-reflectivity lens 302 and is input into the gas concentration detection cavity 2; the second high-reflectivity lens 303, the second convex lens 304 and the optical filter 305 are arranged on the other side of the gas concentration detection chamber 2, and emergent light rays sequentially pass through the second high-reflectivity lens 303, the second convex lens 304 and the optical filter 305 to be emitted from the gas concentration detection chamber 2; the first high reflectivity mirror 302 and the second high reflectivity mirror 303 are oppositely disposed to form a resonant cavity.
Further, a filter membrane is arranged in the air inlet 201 of the gas concentration detection chamber 2 in the present embodiment; the gas outlet 202 of the gas concentration detection chamber 2 is provided with a small-sized suction pump.
In a specific embodiment, an LED near ultraviolet high-power light source 1 with a central wavelength of 325nm and a full width at half maximum of 15nm, which is corresponding to a formaldehyde absorption peak, is adopted, the rated current is 600mA, and the rated power is 3120 mW. The LED light source 1 can reduce the volume of the light source 1, and has the advantages of safety, high efficiency, reliability and stability.
In a specific embodiment, the gas concentration detection chamber 2 has a chamber length of 42.3 cm. The effective length of the gas concentration detection cavity 2 is short, the inner diameter of the cavity is small, the volume of the cavity filled with gas to be detected is small, the buffering time before indoor measurement can be effectively shortened, the resolution efficiency of real-time measurement of the system is improved, and the performance of real-time measurement of the system is improved.
During installation, incident light rays are changed into a group of parallel light rays by adjusting the positions of the light source 1 and the first convex lens 301, and the incident light rays are ensured to be vertically incident to the optical resonant cavity and coaxial with the optical resonant cavity. The first high-reflectivity lens 302 and the second high-reflectivity lens 303 (the reflectivity factory value is greater than 99.9%) form an optical resonant cavity, and the first high-reflectivity lens 302 and the second high-reflectivity lens 303 are coaxial in center, perpendicular to a bus, and opposite in reflection surface.
Before actual measurement, small flows of high-purity nitrogen (> 99.999%) and high-purity helium (> 99.999%) flow into the cavity in sequence, spectral data of the high-purity nitrogen and the high-purity helium are recorded, and the spectral data are used for calibrating the actual reflectivity of the reflector.
At the in-process of the indoor formaldehyde concentration of actual measurement, the aspiration pump lasts work, and the aspiration pump can constantly follow intracavity suction gas, and the gas flow rate is controlled by the mass flow meter before the aspiration pump, and under the effect of pressure, the gas inlet constantly extracts the gas that awaits measuring from the indoor air, and the gas that awaits measuring gets into gas concentration and detects 2 insides and fully absorb incident light.
The stable and continuous near ultraviolet light emitted by the light source 1 is changed into parallel light through the first convex lens 301 and then enters the optical resonant cavity, the light coaxial with the optical resonant cavity is transmitted into the optical resonant cavity through the first high-reflectivity lens 302 and reflected back and forth in the cavity, the effective length of the optical resonant cavity is fully utilized, the space propagation path of the light is greatly prolonged, the formaldehyde in the optical cavity can be ensured to fully absorb the incident light, and the measurement accuracy is improved.
In each reflection, a small part of light is transmitted out of the resonant cavity through the second high-reflectivity lens 303, and then is converged by the second convex lens 304 and then enters the optical filter 305. The filter 305 in this embodiment is specially processed to allow only light with a wavelength below 390nm to pass through, and light with other wavelength ranges returns back in the original path in a total reflection manner. The transmitted light through the filter 305 is coupled into the spectrometer 4 through an optical fiber, and the spectrometer 4 analyzes the absorbed light. The core diameter of the optical fiber in this example was 400. mu.m. The spectrometer 4 sends the acquired spectral data to the calculating unit 5 for fitting calculation to obtain the formaldehyde concentration of the environment to be measured.
The calculation process of the calculation unit 5 in one embodiment is given below for illustrative purposes and is not to be construed as limiting the present patent.
Firstly, before actual measurement, small-flow high-purity nitrogen gas (> 99.999%) and high-purity helium gas (> 99.999%) are introduced into a cavity in sequence, spectral data of the high-purity nitrogen gas and the high-purity helium gas are recorded, and the spectral data are used for calibrating the actual reflectivity R (lambda) of a reflector. The calculation formula is as follows:
wherein d is the distance between the inner surfaces of two high reflection lenses in the optical cavity, IN2(lambda) and IHe(λ) represents the spectral intensity, σ, measured when the optical cavity is filled with nitrogen or helium, respectivelyRaly,N2(λ) is the Rayleigh scattering cross-sectional area of nitrogen, σRaly,He(λ) is the Rayleigh scattering cross-sectional area of helium, nN2And nHeRespectively representMolecular number density of nitrogen and helium.
The spectrum of the high-purity nitrogen gas is taken as a reference spectrum I0(λ), the measured spectrum is the sampled spectrum I (λ). Actual reflectivity R (lambda) and effective cavity length d at known high reflectivity lenseseffThen, the extinction coefficient α (λ) is calculated. Finally, the calculating unit 5 calculates the concentration of the indoor formaldehyde gas through data fitting.
The extinction coefficient alpha (lambda) includes the absorption of the gas to be measured in the gas detection chamber (the number density n of molecules of the gas)iAnd absorption cross section σiSummation of products), rayleigh scattering a of the mediumralyAnd mie scattering alphamieThree moieties of which alpharalyAnd alphamieA multiple order function fit of the wavelengths may be used. Fitting the absorption cross section sigma of the gas to be measured by least square methodHCHOThe concentration n of the gas to be measured can be obtained by the absorption coefficient alpha (lambda)HCHO. The formaldehyde gas has characteristic absorption near 325nm, and the absorption section sigma of the formaldehyde gasHCHOIt is known that the concentration of formaldehyde in indoor air can therefore be accurately determined by optical cavity enhanced absorption spectroscopy. The fitting equation is as follows:
in the formula, σi(lambda) and niRespectively, the absorption cross-sectional area and the molecular number density of the ith gas.
In the embodiment, an optical resonant cavity is formed by a pair of high-reflectivity lenses and a cavity frame, an LED light source 1 with the central wavelength of 325nm is used as a light source 1, a spectrometer 4 is used as a detector, a light cavity enhanced absorption spectrum technology is adopted, and light rays incident into a gas concentration detection cavity 2 are reflected for multiple times through a pair of reflection lenses with the reflectivity of more than 99.9%, so that incident light can be fully absorbed by formaldehyde in the gas concentration detection cavity 2, and the accuracy of measurement is improved. And finally, introducing the spectral information measured by the spectrometer 4 into the calculating unit 5, and performing data processing such as fitting calculation and the like, so as to measure the formaldehyde content in the indoor atmosphere and realize the online accurate measurement of the indoor formaldehyde concentration.
The embodiment utilizes the optical cavity enhanced absorption spectrum technology, namely, the effective gas absorption optical path is prolonged and the size of the instrument is optimized by introducing the optical cavity, so that the portable function of the instrument is realized, and the portable optical cavity has the characteristics of portability, high efficiency, high stability and low cost.
Example 2
The present embodiment provides a formaldehyde concentration measuring apparatus, as shown in fig. 2, which is a schematic structural diagram of the formaldehyde concentration measuring apparatus of the present embodiment.
The formaldehyde concentration measuring device provided by the embodiment comprises a light source 1, a gas concentration detection cavity 2, an optical system 3 for coupling and reflecting light, a spectrometer 4 and a calculating unit 5, wherein the optical system 3 is arranged on two sides of the gas concentration detection cavity 2; one end of the gas concentration detection cavity 2 is provided with a gas inlet 201, and the other end of the gas concentration detection cavity 2 is provided with a gas outlet 202; light emitted by the light source 1 enters the gas concentration detection cavity 2 after passing through the optical system 3 arranged on one side of the gas concentration detection cavity 2; the output end of the optical system 3 arranged at the other end of the gas concentration detection cavity 2 is connected with the input end of the spectrometer 4 through an optical fiber, and the output end of the spectrometer 4 is connected with the input end of the calculating unit 5.
Further, the formaldehyde concentration measuring device provided by the embodiment further includes a first bracket 6 and a second bracket 7, the light source 1 and the center of the first convex lens 301 are coaxially fixed on the first bracket 6, and the first high-reflectivity lens 302 is arranged on the first bracket 6 through a translation adjusting bracket; the second high-reflectivity lens 303 is arranged on the second support 7 through a translation adjusting frame, and the second convex lens 304 and the filter 305 are coaxially fixed on the second support 7 in the center.
The first support 6 and the second support 7 are used for erecting the light source 1 and the optical system 3, and the first high-reflectivity lens 302 and the second high-reflectivity lens 303 are respectively arranged on the first support 6 and the second support 7 through the translation adjusting frame and are used for adjusting the directions of the high-reflectivity lenses in the X direction and the Y direction.
The first support 6 and the second support 7 in this embodiment are cavity structures, the first support 6 and the second support 7 are respectively provided with a purging gas inlet 601, 701 close to the inner sides of the first high-reflectivity lens 302 and the second high-reflectivity lens 303, the purging gas inlet 601, 701 is connected with a purging gas cylinder for continuously introducing purging gas for purging the high-reflectivity lens surface, and the reflector is protected from being polluted or abraded.
Furthermore, the first support 6, the second support 7 and the gas concentration detection chamber 2 are connected through a corrugated pipe 8, and the corrugated pipe 8 is communicated with the gas concentration detection chamber 2. Wherein the gas concentration detection chamber 2 and the bellows 8 are hollow, so that the gas to be detected is fully absorbed through the light path. In this embodiment, the gas concentration detection chamber 2 and the bellows 8 are made of PFA, and the inner diameter of the gas concentration detection chamber 2 is 10.0 mm.
Further, the purge gas inlets 601 and 701 in this embodiment are respectively provided with mass flow controllers 602 and 702 for controlling the flow rate and flow rate of the purge gas.
In the specific implementation process, the first support 6 and the second support 7 adopt stainless steel cavity frames, so that the stability of lens installation and the adjustability of the direction of the mirror surface are ensured. The light source 1 is fixed at the foremost end of the first bracket 6, and output light directly penetrates through each group of lenses to enter the cavity; the first convex lens 301 and the second convex lens 304 are respectively fixed on the first bracket 6 and the second bracket 7 in a central coaxial manner; the first high-reflectivity lens 302 and the second high-reflectivity lens 303 are carried and fixed on the first support 6 and the second support 7 in sequence through the translation adjusting frame, the position of the reflecting lens is changed by adjusting the distance between the convex lens and the reflecting mirror, the direction of the reflecting mirror surface is changed by adjusting the two thread pairs of the translation adjusting frame in the X direction and the Y direction, and the mounting stability of the lenses and the adjustability of the direction of the mirror surface are ensured. In addition, the present embodiment can maximize the light intensity entering the optical fiber by adjusting the position of the second convex lens 304.
The mass flow controllers 602 and 702 control the flow of high purity nitrogen (> 99.999%) to continuously blow into the first support 6 and the second support 7, and form a gas film in the first support 6 and the second support 7 to protect the high reflectivity mirrors on both sides of the resonant cavity from contamination or abrasion. In addition, the mass flow controllers 602 and 702 control the air inflow of the purge gas to be 0.1L/min during the detection, and the sampling time resolution of the spectrometer 4 is set to be 60 s.
The present embodiment can adjust the optical path to the optimal position by observing the intensity of the signal received by the spectrometer 4, that is, the received optical signal is strongest and the signal lost by the optical path is smallest.
Example 3
The present embodiment provides a formaldehyde concentration measuring device, as shown in fig. 3, which is a schematic structural diagram of the formaldehyde concentration measuring device of the present embodiment.
The formaldehyde concentration measuring device provided by the embodiment comprises a light source 1, a gas concentration detection cavity 2, an optical system 3 for coupling and reflecting light, a spectrometer 4 and a calculating unit 5, wherein the optical system 3 is arranged on two sides of the gas concentration detection cavity 2; one end of the gas concentration detection cavity 2 is provided with a gas inlet 201, and the other end of the gas concentration detection cavity 2 is provided with a gas outlet 202; light emitted by the light source 1 enters the gas concentration detection cavity 2 after passing through the optical system 3 arranged on one side of the gas concentration detection cavity 2; the output end of the optical system 3 arranged at the other end of the gas concentration detection cavity 2 is connected with the input end of the spectrometer 4 through an optical fiber, and the output end of the spectrometer 4 is connected with the input end of the calculating unit 5.
Further, the formaldehyde concentration measuring device in the embodiment further includes a main power supply 9, a constant current source 10, and a constant temperature module 11. Wherein, the output end of the main power 9 is electrically connected with the power supply end of the light source 1 through the constant current source 10, and the main power 9 and the constant current source 10 provide the voltage of the constant current for the light source 1. The main power supply 9 is used for outputting two voltages of 220V and 12V for the circuit, and the constant current source 10 is used for realizing constant current control. Fig. 4 is a schematic diagram of a circuit structure of the formaldehyde concentration measuring device of the present embodiment.
The constant temperature module 11 comprises a temperature sensor 1101, a controller 1102, a control switch 1103 and a refrigeration assembly 1104, wherein the temperature sensor 1101 is connected with the light source 1, the output end of the temperature sensor 1101 is connected with the input end of the controller 1102, the output end of the controller 1102 is connected with the control switch 1103, the control switch 1103 and the refrigeration assembly 1104 form a loop, and the refrigeration assembly 1104 is tightly attached to the light source 1. The temperature sensor 1101 is configured to monitor a temperature of the light source 1, and the controller 1102 determines whether to issue a refrigeration instruction according to whether the monitored temperature value exceeds a set value; when the controller 1102 sends a refrigeration instruction, that is, the controller 1102 sends a signal to the control switch 1103, the control switch 1103 is closed, and the refrigeration component 1104 works and cools down the light source 1.
Furthermore, the formaldehyde concentration measuring device in this embodiment further includes a cooling fan 12, the main power supply is electrically connected to the cooling fan, and the cooling fan is used for further discharging heat generated by the light source and the refrigeration component during operation, so as to avoid the refrigeration component from being damaged due to overheating during operation.
In the specific implementation process, the light source 1 is fixed in an aluminum block, the rear side of the aluminum block is tightly attached to the refrigeration component 1104, the refrigeration component 1104 in the embodiment adopts a peltier refrigeration piece, and the control switch 1103 adopts a Solid State Relay (SSR). A heat radiation fan 12 is additionally arranged at the rear part of the aluminum block, and a red copper heat radiator with a fan is adopted in the embodiment. The edge of the light source 1 is inserted into a temperature sensor 1101, and the detected temperature is processed and displayed by a controller 1102, and the controller 1102 in this embodiment employs a PID (proportional-integral-derivative) controller 1102. In order to realize constant current control, a constant current source 10 is adopted to ensure that the current of the branch where the light source 1 is located is constant. Meanwhile, the PID controller 1102 presets a specified temperature (24.0 ℃ +/-0.1 ℃), and when the temperature of the light source 1 exceeds the preset temperature, the PID controller 1102 transmits an electric signal to the control switch 1103, so that a branch where the refrigeration assembly 1104 is located is switched on, and the refrigeration assembly 1104 starts to work; when the temperature of the light source 1 is reduced to below the preset temperature, the branch where the refrigeration component 1104 is located is disconnected and refrigeration is not realized any more, the temperature of the light source 1 slowly rises back, constant temperature control over the light source 1 is realized, the temperature of the light source 1 is ensured to be stabilized within 24.0 +/-0.1 ℃ and single-wavelength near ultraviolet light (central wavelength 325nm) is emitted, and after the light source 1 is stabilized, the light intensity and the spectral distribution of incident light and transmitted light are also kept stable.
The same or similar reference numerals correspond to the same or similar parts;
the terms describing positional relationships in the drawings are for illustrative purposes only and are not to be construed as limiting the patent;
it should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.
Claims (10)
1. The formaldehyde concentration measuring device is characterized by comprising a light source (1), a gas concentration detection cavity (2), an optical system (3) for coupling and reflecting light, a spectrometer (4) and a calculating unit (5), wherein:
the optical system (3) is arranged on two sides of the gas concentration detection cavity (2);
one end of the gas concentration detection cavity (2) is provided with a gas inlet (201), and the other end of the gas concentration detection cavity (2) is provided with a gas outlet (202);
the light emitted by the light source (1) enters the gas concentration detection cavity (2) after passing through the optical system (3) arranged on one side of the gas concentration detection cavity (2); the output end of an optical system (3) arranged at the other end of the gas concentration detection cavity (2) is connected with the input end of the spectrometer (4) through an optical fiber, and the output end of the spectrometer (4) is connected with the input end of the calculation unit (5).
2. The formaldehyde concentration measuring device according to claim 1, wherein the optical system (3) comprises a first convex lens (301), a first high-reflectivity lens (302), a second high-reflectivity lens (303), a second convex lens (304) and an optical filter (305) which are coaxially arranged along the optical axis direction; wherein the first convex lens (301) and the first high-reflectivity lens (302) are arranged on one side of the gas concentration detection cavity (2), and the second high-reflectivity lens (303), the second convex lens (304) and the optical filter (305) are arranged on the other side of the gas concentration detection cavity (2); the first high-reflectivity lens (302) and the second high-reflectivity lens (303) are oppositely arranged to form a resonant cavity.
3. The formaldehyde concentration measuring device according to claim 2, further comprising a first bracket (6) and a second bracket (7), wherein the light source (1) and the first convex lens (301) are coaxially fixed on the first bracket (6) at the center, and the first high-reflectivity lens (302) is arranged on the first bracket (6) through a translation adjusting bracket; the second high-reflectivity lens (303) is arranged on a second support (7) through a translation adjusting frame, and the centers of the second convex lens (304) and the optical filter (305) are coaxially fixed on the second support (7).
4. The formaldehyde concentration measuring device according to claim 3, wherein the first bracket (6) and the second bracket (7) are cavity structures, the first bracket (6) and the second bracket (7) are respectively provided with a purge gas inlet (601, 701) closely attached to the inner sides of the first high-reflectivity lens (302) and the second high-reflectivity lens (303), and the purge gas inlet (601, 701) is connected with a purge gas cylinder.
5. The formaldehyde concentration measuring device according to claim 4, wherein the purge gas inlet (601, 701) is provided with a mass flow controller (602, 702).
6. The formaldehyde concentration measuring device according to claim 4, wherein the first support (6), the second support (7) and the gas concentration detection chamber (2) are connected through a corrugated pipe (8), and the corrugated pipe (8) is communicated with the gas concentration detection chamber (2).
7. The formaldehyde concentration measuring device according to claim 1, wherein a particulate filter having a filter membrane is provided at a front section of the gas inlet (201) of the gas concentration detection chamber (2); and a mass flow meter and an air pump are arranged at an air outlet (202) of the gas concentration detection cavity (2).
8. The formaldehyde concentration measuring device according to any one of claims 1 to 7, further comprising a main power supply (9) and a constant current source (10), wherein an output end of the main power supply (9) is electrically connected with a power supply end of the light source (1) through the constant current source (10).
9. The formaldehyde concentration measuring device according to claim 8, further comprising a constant temperature module (11), wherein the constant temperature module (11) comprises a temperature sensor (1101), a controller (1102), a control switch (1103) and a refrigeration component (1104), the temperature sensor (1101) is connected with the light source (1), the output end of the temperature sensor (1101) is connected with the input end of the controller (1102), the output end of the controller (1102) is connected with the control switch (1103), and the control switch (1103) and the refrigeration component (1104) form a loop; the refrigeration assembly (1104) is tightly attached to the light source (1).
10. The formaldehyde concentration measuring device according to claim 9, further comprising a heat radiation fan (12), wherein the main power supply (9) is electrically connected to the heat radiation fan (12).
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| CN115586114A (en) * | 2022-11-24 | 2023-01-10 | 珩辉光电测量技术(吉林)有限公司 | Atmospheric environment micro-nano particulate particle size measuring device based on scattering spectrometry |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115586114A (en) * | 2022-11-24 | 2023-01-10 | 珩辉光电测量技术(吉林)有限公司 | Atmospheric environment micro-nano particulate particle size measuring device based on scattering spectrometry |
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