KR20240016689A - Ndir sensor having multiple channel and toc measuring system including the same - Google Patents

Abstract

The present invention discloses an NDIR sensor and TOC measurement system. More specifically, the present invention relates to a multi-channel NDIR sensor that measures gas concentration by receiving infrared light irradiated to a sample gas using an infrared light source through a plurality of detectors, and a TOC measurement system including the same.
According to an embodiment of the present invention, the NDIR sensor is equipped with two or more filters of different wavelength bands and corresponding detectors, and the concentration value of the measured gas sample is corrected by analyzing a plurality of detection signals generated through each detector. By doing so, there is an effect of measuring the CO ₂ concentration contained in the sample more accurately.

Description

NDIR sensor having multiple channels and TOC measurement system including same {NDIR SENSOR HAVING MULTIPLE CHANNEL AND TOC MEASURING SYSTEM INCLUDING THE SAME}

The present invention relates to an NDIR sensor and a TOC measurement system, and in particular, to an NDIR sensor having multiple channels for measuring gas concentration by receiving infrared light irradiated to a sample gas using an infrared light source through a plurality of detectors, and TOC measurement including the same. It's about the system.

Due to various environmental problems, including abnormal climate changes such as global warming, the occurrence of water pollutants such as green algae in rivers and lakes is increasing, and the need for their management is increasingly emerging.

In general, representative indicators for evaluating water quality include Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), and Total Organic Carbon (TOC). Among these, BOD measurement uses microorganisms as sensors, so its performance may be reduced by toxic substances, and it has the disadvantage of making it difficult to accurately measure organic matter in the presence of non-decomposable substances. In addition, COD measurement has a large analysis error depending on the nature of the contaminant, and has the disadvantage of being affected by interfering substances such as chlorine. Accordingly, the TOC measurement method, which analyzes the degree of contamination by measuring the amount of organic carbon contained in water, has recently been in the spotlight.

The TOC measurement method can be applied not only to rivers and lakes, but also to wastewater treatment plants and water purification fields, and its scope of application is expanding to include cooling water in pharmaceutical, semiconductor, and power generation fields that require pure water.

In addition, in order to reduce costs and secure high sensitivity for TOC measurement methods, related organizations are focusing on the development of TOC measurement systems, and are applying the Fabry-Perot (FPI) method to the existing single-light dual-wavelength analysis method to provide the same optical path. The development of detectors with measurement methods is being activated.

As the main component installed in the TOC measurement system to detect gas concentration, the Non-Dispersive InfraRed (NDIR) sensor measures the concentration by using the characteristic of gas molecules to absorb light (infrared rays) of a specific wavelength. It is a sensor that determines gas concentration by measuring light absorption. Here, since specific gas molecules have the characteristic of absorbing only light in a specific wavelength range, light of various wavelengths is radiated to the gas molecule, and only the light in the wavelength range absorbed by the targeted gas molecule can be filtered out and measured. there is.

Accordingly, NDIR has the advantage of being simpler and less expensive than the dispersion method, as it only requires attaching an optical filter that transmits only the relevant wavelength to the optical detector, and has high gas selectivity and measurement reliability.

Figure 1 is a diagram showing the internal structure of a non-dispersive infrared sensor (NDIR) according to the prior art. The conventional NDIR sensor 1 includes an infrared light source 3, a waveguide 5, a filter 7, and a detector 9. It consists of

The infrared light source 3 emits infrared rays, and the emitted infrared rays are transmitted to the detector 9 through the waveguide 5. Air gas flows into the waveguide 5, and the infrared light emitted from the infrared light source 3 travels and passes through the air gas flowing into the waveguide 5. Here, the infrared light may contact the gas while traveling through the waveguide 5, and when the infrared light contacts the gas in the air, the wavelength band corresponding to the natural vibration of the gas is absorbed by the gas.

In addition, the waveguide 5 transmits the infrared light emitted from the infrared light source 3 to the detector 9, and between the waveguide 5 and the detector 9, there is a filter 7 that passes part of the wavelength band of the infrared light. More than one is deployed. Here, the filter 7 can pass only wavelength bands according to its characteristics, and the detector 9 can detect infrared rays in a specific wavelength band that have passed through the filter.

Accordingly, the detector 9 can measure the concentration of gas contained in the air using the intensity of infrared light that has passed through a plurality of filters. Specifically, as the gas in the air selectively absorbs a specific wavelength band of infrared rays, the detector 9 measures how much of the infrared component corresponding to the specific wavelength band is absorbed by the gas after passing through the air. The concentration of gases present in the air can be measured. In other words, the higher the concentration of a specific gas, the lower the intensity of infrared rays corresponding to the specific wavelength band. On the other hand, the lower the concentration of the gas in the air, the greater the intensity of infrared rays corresponding to the specific wavelength band.

Through this structure, the NDIR sensor 1 can measure the concentration of a specific gas, and the TOC measurement system gasifies the sample and measures its CO ₂ concentration using the mounted NDIR sensor to measure the total organic carbon ( TOC) can be measured.

However, the NDIR sensor used in this total organic carbon system is a dedicated sensor that can only measure CO ₂ , and cannot measure other types of gases such as COS, CO, CH4, etc. in addition to CO ₂ , and other gases included in the sample. In order to detect a component, there is a limitation in having to use as many NDIR sensors as there are types.

In particular, in a sensor using an infrared light source, the output of the detector must always be constant for an infrared light source of uniform intensity and a gas of constant concentration. If the device of the mounted detector deteriorates, changes in the internal temperature of the waveguide, or changes in surrounding environmental variables occur, the identity of the output signal of the infrared sensor measured for an infrared light source of uniform intensity and a gas of constant concentration is guaranteed. If this is not done, the reliability of not only the sensor but also the entire TOC measurement system will be lowered.

Therefore, a correction technology that can identify and control the characteristics of the elements mounted on the NDIR sensor must be secured, and furthermore, a means to obtain precise sensor measurement results is required.

Registered Patent Publication No. 10-2114557 (Publication date: 2020.05.18.)

The present invention relates to a non-dispersive infrared sensor and a total organic carbon (TOC) measurement system, which measures the concentration of CO ₂ contained in a sample using an infrared light source and detector, and measures the surrounding environment such as deterioration of the NDIR sensor element and temperature. The challenge is to provide NDIR sensors and TOC measurement systems that minimize the impact of changes in circumstances and ensure uniform measurement results.

In order to solve the above-described problem, an NDIR sensor with multiple channels according to an embodiment of the present invention includes a light source emitting infrared light, a light entering part and a light exiting part opening at both ends, and the light source is disposed. An optical waveguide that configures an optical path so that the light traveling through the light entrance part passes through the sample gas filled inside and reaches the light exit part, and a first and A second filter, first and second detectors for generating detection signals by receiving light from different channels that have passed through the first and second filters, respectively, and receiving detection signals from the two channels to determine the target material through the average value. It may include an analysis device that calculates a concentration value, and corrects and outputs the concentration value if the average value is greater than or equal to a threshold.

The analysis device includes an A/D converter that receives first and second detection signals, which are analog waveforms, from the first and second detectors and converts them into digital waveforms, and noise existing in the first and second detection signals of the digital waveform. A noise removal unit that compensates for the linearity of the first and second detection signals by reducing the signal, an average value calculation unit that calculates the average value of the first and second detection signals from which the noise has been removed, and a preset value if the average value is greater than or equal to a threshold value. It may include a correction unit that corrects the concentration value by multiplying it by a correction coefficient.

The correction unit is connected to a temperature sensor installed on one side of the optical waveguide, and can increase or decrease the size of the correction coefficient in response to the temperature measured by the temperature sensor.

The optical waveguide may further include a heat dissipation pattern whose outer surface protrudes at a certain height in the vertical direction to form a concavo-convex shape.

The NDIR sensor may include a control device connected to a temperature sensor installed on the outer surface of the optical waveguide, and the control device may be further connected to a cooler that cools the light source in response to the temperature measured from the temperature sensor.

The NDIR sensor includes a rotatable first disk on which the first and second filters are mounted, and a rotatable second disk disposed in parallel with the first disk and on which the first and second detectors are mounted, As one or both of the first and second disks rotate, the light emitting part of the optical waveguide, the first or second filter, and the first or second detector can be arranged in a line, respectively.

In addition, in order to solve the above-described problem, a TOC measurement system including an NDIR sensor with multiple channels according to an embodiment of the present invention includes a syringe for mixing and delivering a sample, and a syringe and the syringe through a plurality of ports. A rotary valve connecting one or more solution supply units and a sample supply unit, a fluid in each pipe connected to the rotary valve, an MFC that controls the movement of gas, an oxygen valve that supplies 0 ₂ gas to the MFC, and stored inside the syringe. A UV-reactor that generates sample gas by receiving fluid, removing inorganic carbon and oxidizing the remaining organic carbon to generate carbon dioxide, a moisture removal unit that removes moisture inside the generated carbon dioxide, and a UV-reactor that allows light of a specific wavelength band to pass through. It includes first and second filters, and first and second detectors that generate detection signals by receiving light of different channels that have passed through the first and second filters, respectively, and receives the detection signals to detect the target material. It includes an NDIR sensor that calculates a concentration value for, wherein the NDIR sensor receives detection signals from two channels and calculates the concentration value for the target material through an average value. If the average value is greater than a threshold, the NDIR sensor calculates the concentration value for the target substance. It may include an analysis device that corrects and outputs the output.

In the NDIR sensor, the optical waveguide further includes a heat dissipation pattern whose outer surface protrudes at a certain height in the vertical direction to form a concavo-convex shape, is connected to one port of the rotary valve through which coolant is transferred, and the convexity of the heat dissipation pattern is connected to one port of the rotary valve. It may further include cooling pipes wound within the shape.

The rotary valve may connect the cooling pipe to the sample supply unit or solution supply unit when transferring a sample or solution in which a chemical reaction is activated at a high temperature during the sample gas generation process.

According to an embodiment of the present invention, two or more filters of different wavelength bands and corresponding detectors are mounted on the NDIR sensor, and the concentration value of the measured gas sample is corrected by analyzing the two detection signals generated through each detector. , it has the effect of more accurately measuring the CO ₂ concentration contained in the sample.

Figure 1 is a diagram showing the structure of a conventional NDIR sensor.
Figure 2 is a diagram showing the structure of an NDIR sensor with multiple channels according to an embodiment of the present invention.
Figure 3 is a diagram showing the structure of an analysis device used in an NDIR sensor with multiple channels according to an embodiment of the present invention.
4 to 5 are diagrams showing the structure of an NDIR sensor with multiple channels according to an embodiment of the present invention.
Figure 6 is a diagram showing the structure of a TOC measurement system including an NDIR sensor with multiple channels according to an embodiment of the present invention.

The present invention as described above will be described in detail through the attached drawings and examples.

It should be noted that the technical terms used in the present invention are only used to describe specific embodiments and are not intended to limit the present invention. In addition, the technical terms used in the present invention, unless specifically defined in a different sense in the present invention, should be interpreted as meanings generally understood by those skilled in the art in the technical field to which the present invention pertains, and are not overly comprehensive. It should not be interpreted in a literal or excessively reduced sense. Additionally, if the technical term used in the present invention is an incorrect technical term that does not accurately express the idea of the present invention, it should be replaced with a technical term that can be correctly understood by a person skilled in the art. In addition, general terms used in the present invention should be interpreted according to the definition in the dictionary or according to the context, and should not be interpreted in an excessively reduced sense.

Additionally, as used in the present invention, singular expressions include plural expressions unless the context clearly dictates otherwise. In the present invention, terms such as “consists of” or “comprises” should not be construed as necessarily including all of the various components or steps described in the invention, and some of the components or steps are included. It may not be possible, or it should be interpreted as including additional components or steps.

Additionally, terms including ordinal numbers, such as first, second, etc., used in the present invention may be used to describe components, but the components should not be limited by the terms. Terms are used only to distinguish one component from another. For example, a first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component without departing from the scope of the present invention.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the attached drawings. However, identical or similar components will be assigned the same reference numbers regardless of the reference numerals, and duplicate descriptions thereof will be omitted.

Additionally, when describing the present invention, if it is determined that a detailed description of related known technologies may obscure the gist of the present invention, the detailed description will be omitted. In addition, it should be noted that the attached drawings are only intended to facilitate easy understanding of the spirit of the present invention, and should not be construed as limiting the spirit of the present invention by the attached drawings.

Figure 2 is a diagram showing the structure of an NDIR sensor with multiple channels according to an embodiment of the present invention.

Referring to FIG. 2, a non-dispersive infrared sensor (NDIR; 100) according to an embodiment of the present invention is a sensor that measures the concentration of a gaseous sample using infrared rays. As is known, the frequency of infrared rays is in a range similar to the natural frequency of the molecules constituting the material, so when infrared rays hit a material, an electromagnetic resonance phenomenon occurs, the energy of the light wave is effectively absorbed, and strong heat is emitted. Materials in the liquid or gaseous state have the property of strongly absorbing infrared rays of unique wavelengths for each material. Accordingly, the NDIR sensor 100 according to an embodiment of the present invention can measure the concentration of the target material using the characteristics of infrared rays described above. That is, the concentration of the target material can be measured by injecting the target material into the optical waveguide 130 in the form of a gas and measuring the decrease in light intensity at a specific wavelength.

In detail, the NDIR sensor 100 according to an embodiment of the present invention includes a light source 110 that emits infrared light, a light entering part and a light exit part opening at both ends, and a mouth where the light source 110 is disposed. An optical waveguide 130 that configures an optical path so that the light passing through the light emitter passes through the sample gas filled inside and reaches the light exit section, and a first light guide disposed in the light exit section of the optical waveguide to pass light of a specific wavelength band. and second filters 161 and 162. First and second detectors 191 and 192 generate detection signals by receiving light of different channels that have passed through the first and second filters, respectively, and transmit the detection signals. It may include an analysis device 500 that receives and calculates a concentration value for the target substance, and corrects and outputs the concentration value when the deviation between detection signals of different channels is greater than a threshold.

The light source 110 is equipped with a predetermined infrared light-emitting element and can irradiate infrared light in one direction. The emitted infrared light (L1, L2) passes through the optical path inside the optical waveguide 150 and is incident on the first and second filters (161, 162), and is filtered at a specific wavelength through the first and second filters (161, 162). It may be band-filtered and incident on the light-receiving element mounted on the detectors 191 and 192.

Here, the light emitting element mounted on the light source 110 is an infrared lamp, and an element that emits continuous light of 0㎛ ~ 10㎛ can be used, and one end of the optical waveguide 130 is exposed to the outside of the optical waveguide 130. It may be arranged to face the light entering portion formed in .

The optical waveguide 130 may be made of a metal material such as metallic copper (Cu) or copper-zinc (Cu-Zn) alloy (brass), and may have an empty cylindrical structure with a certain length, and may have a hollow cylindrical structure on one side of the sample. An injection part into which gas is introduced and an outlet part through which sample gas after the detection procedure is discharged may be formed. In addition, both ends are opened and the light source 110 and the first and second detectors 191 and 192 are arranged to face each other, so that there is a light entrance part through which light enters the inside and a light entrance part through which light goes outside. A light exit portion, which is a path, may be formed.

According to an embodiment of the present invention, the optical waveguide 130 of the NDIR sensor 100 is formed to a length such that the optical path formed inside is as large as possible, and the infrared light (L1, L2) is fully reflected through the optical waveguide. In addition to being configured to reflect from the inner surface of the light source 130 toward the light emitting portion, the light source 110 may be disposed outside the optical waveguide 130 to be advantageous for heat dissipation.

Meanwhile, the quantitative calculation of the sample gas in the NDIR sensor is based on the Beer-Lambert law according to Equation 1 below. This is a basic law of light attenuation and indicates that the amount of light absorbed by the target material varies depending on the wavelength.

Here, I ₀ is the initial light intensity, ε (specific absorptivity) is the molecular extinction coefficient, c (concentration) is the concentration of the gas, l (optical length) is the optical path length from the light source to the detector, and α (absorption). coefficient) represents the absorption coefficient depending on the concentration of gas, and β represents the proportionality constant.

According to Equation 1 above, it can be seen that the energy (I) of the infrared light measured by the detector is exponentially inversely proportional to the concentration of the gas (c) and the distance passing through the infrared gas (l). Accordingly, In order to improve the sensitivity of the NDIR sensor 100, there are methods of increasing the initial incident light amount or lengthening the optical path to increase the number of hydroxide molecules that react to infrared light.

Additionally, the optical waveguide 130 may be formed with an injection portion into which sample gas containing the target material is injected and an discharge portion through which the sample gas containing the target material is discharged to the outside. Infrared light (L1, L2) is absorbed by the target material when a target material is present in the sample gas, and the light intensity in the wavelength band corresponding to the material is reduced, and the infrared light (L1, L2) has reduced light sensitivity to the target material. ) can be received by a detector to measure the concentration of the target material.

Additionally, according to an embodiment of the present invention, a metal layer with high light reflectance may be coated on the inner surface of the optical waveguide 130. The metal layer may be made of a metal that has a high reflectivity for incident infrared light, and gold (Au) may be used as such metal.

Subsequently, the infrared light (L1, L2) traveling along the optical path is absorbed at a specific wavelength by CO ₂ contained in the sample gas, and is transmitted to the outside through a light exit portion formed on the upper or lower side of the other side of the optical waveguide 130. It goes out into the light.

The first and second filters 161 and 162 are optical members that pass only light in a specific wavelength band, and limit the wavelength according to the characteristics of the target material to be measured, thereby allowing only infrared light having a wavelength band corresponding to the characteristics of the target material to be measured. Let it be incident on this detector.

In particular, the NDIR sensor 100 according to an embodiment of the present invention is a sensor for measuring the concentration of carbon dioxide (CO ₂ ) as a target material in a sample, and the first and second filters 161 and 162 are the target in feed gas. An optical filter that passes only 4.26㎛ infrared light, which is a wavelength band that has the property of being absorbed in response to the concentration of the material, can be used.

The first and second detectors 191 and 192 may detect infrared light incident through the first and second filters 161 and 162, respectively, and output an electrical signal according to the intensity of the light. . Thermal sensing elements such as pyroelectric, bolometer, and thermopile may be used as the first and second detectors 191 and 192, and these elements detect incident infrared heat energy. Infrared rays can be detected by converting the physical properties of materials that change depending on the amount into electrical signals.

According to this structure, the first and second detectors 191 and 192 output detection signals with different voltage levels depending on the concentration of the substance to be detected. For example, as an optical filter that passes only the 4.26㎛ wavelength band is used, the detection signals output from the first and second detectors 191 and 192 detected through two channels are all at the same level. In particular, depending on the concentration of CO ₂ in the gas sample, the infrared component with a wavelength of 4.26㎛ is absorbed by the gas in the optical waveguide 130 and less light is received, so the output signal level of the two channels also appears small, and these output signals are transmitted to the analysis device. It is input to (500) and the concentration value is calculated corresponding to the level of the output signal.

In particular, according to an embodiment of the present invention, since both the first and second filters 161 and 162 have the same characteristics, the detection signals output from the first and second detectors 191 and 192 must also be the same. , output signals of different levels may be input to the analysis device 500, and the analysis device 500 is characterized in that it calculates the concentration value based on the average value of the two output signals.

This is due to deterioration of the detector or change in device characteristics even though the output signals are detected from two detectors with the same characteristics. In the present invention, by adding at least two or more identical filters and detectors to the NDIR sensor 100, any one Even if deterioration occurs in the device, accuracy above a certain level can be guaranteed.

The analysis device 500 receives a detection signal and calculates a concentration value for the target substance. It receives detection signals from different channels through the first and second detectors 191 and 192, and detects at least two or more detection signals. The concentration value for CO ₂ can be calculated and provided by calculating the average value through a converter, subtractor, etc., or by correcting it using a correction coefficient (k).

Additionally, the analysis device 500 can correct the concentration value by multiplying the average value by the correction coefficient (k) when the deviation between the two detection signals of different channels is greater than a threshold.

In addition, the analysis device 500 may be further connected to a temperature sensor 600 installed on one surface of the optical waveguide 230, especially at a location where the temperature rise rate is high, and then detect the temperature measured from the optical waveguide 230. You can input the results and refer to them when correcting the concentration value.

According to the above-described structure, the NDIR sensor according to an embodiment of the present invention is an optical sensor that measures CO ₂ contained in sample gas using infrared light, and applies a detection structure that is robust against deterioration of some elements, changes in characteristics, etc. The reliability of the sensor can be improved.

Hereinafter, an analysis device used in an NDIR sensor with multiple channels according to an embodiment of the present invention will be described in detail with reference to the drawings.

Figure 3 is a diagram showing the structure of an analysis device used in an NDIR sensor with multiple channels according to an embodiment of the present invention.

Referring to FIG. 3, the analysis device 500 according to an embodiment of the present invention includes an A/D converter 510 that receives first and second detection signals, which are analog waveforms, from a detector and converts them into digital waveforms. A noise removal unit 520 that compensates for the linearity of the first and second detection signals by reducing the noise existing in the first and second detection signals, and calculates the average value of the first and second detection signals from which the noise has been removed. It may include an average value calculation unit 530 that calculates the average value, and a correction unit 540 that corrects the preset concentration value by multiplying it by a correction coefficient if the average value is greater than or equal to a threshold value.

The A/D converter 510 can convert the analog waveform detection signal transmitted from the first and second detectors into a digital waveform. Additionally, before analog-to-digital conversion, a low-level detection signal can be amplified above a certain level through an amplifier.

The noise removal unit 520 can attenuate a noise signal that may be added to the detection signal of the digital waveform during the conversion process by the A/D converter 510. In particular, errors may occur during analysis as the detection signal is amplified to the level of noise, and the noise removal unit 520 minimizes the occurrence of such errors.

The average value calculation unit 530 may calculate an average value for the detection signal by the first detector and the detection signal by the second detector. In an embodiment of the present invention, the first and second detectors are sensing means that output a detection signal corresponding to infrared light incident through a filter for the same wavelength band, and the detection signal at the same voltage level must be output, but less than the threshold. The error can be ignored, and the concentration of the target substance is calculated through the average value.

The correction unit 540 calculates the difference between detection signals of different channels received from the first and second detectors, and when this deviation is above a certain level, that is, above the threshold, the concentration value is calculated using a preset correction coefficient (k). can be corrected.

This is because an error occurs in the detection signal of the detector due to a measurement error such as device deterioration. Such measurement error can be caused not only by deterioration of the device itself but also by temperature changes around the detector, and the correction unit 540 contains the device characteristics. The correction coefficient (k) according to change or temperature change is set in the form of a look-up table (LUT), and the correction procedure can be performed by extracting the correction coefficient (k) from the LUT and multiplying it by the average value according to the current situation.

To this end, the correction unit 540 may be connected to an NDIR sensor, particularly the temperature sensor 600 installed on the optical waveguide, and the temperature value measured therefrom may be referred to when extracting the correction coefficient (k).

Additionally, the analysis device 500 may be further connected to a separate display device 550, and may display the CO ₂ concentration value calculated by the correction unit 540 in the form of a graph and numerical data.

Hereinafter, the technical idea of the present invention will be described in detail through various modifications of the optical waveguide mounted on the NDIR sensor of the present invention with reference to the drawings.

Figure 4 is a diagram showing the structure of an NDIR sensor with multiple channels according to an embodiment of the present invention.

In the following description, a structure that minimizes the influence of heat generated from a light source through optical means that focuses infrared light emitted from the light source on the diffraction film will be described.

Referring to FIG. 4, the NDIR sensor 200 according to an embodiment of the present invention is formed with first and second light sources 211 and 212 that emit infrared light, and a light input portion and a light exit portion that are open at both ends. and an optical waveguide 230 that configures an optical path so that the light traveling through the light entering part where the first and second light sources 211 and 212 are disposed passes through the sample gas filled therein to reach the light exiting part. First and second filters 261 and 262, which are disposed in the light emitting portion of the waveguide 230 and allow light of a specific wavelength band to pass, and light of different channels passing through the first and second filters 261 and 262, respectively. First and second detectors 291 and 292 that receive light and generate a detection signal, receive the detection signal and calculate the concentration value for the target material, and if the deviation between the detection signals of different channels is more than a threshold, the concentration value is calculated. Input the analysis device 500 that corrects and outputs the output, the temperature sensor 600 installed on the outer surface of the optical waveguide 230 to measure temperature, and the temperature value of the NDIR sensor 200 measured by the temperature sensor 600. It may include a receiving control device 630 and a cooler 650 that lowers the temperature of the first and second light sources 212 and 212 below a certain level through control by the control device 630 according to the temperature measurement result. there is.

In detail, the first and second light sources 211 and 212 are equipped with predetermined infrared light-emitting elements and can irradiate infrared light L1 and L2 in one direction, respectively. The emitted infrared light passes through the optical path inside the optical waveguide 130, is filtered into a specific wavelength band through the first and second filters 261, 262, and can be incident on the first and second detectors 291, 292. there is.

In particular, according to an embodiment of the present invention, the first and second light sources 211 and 212 are configured to emit infrared light L1 and L2 emitted through various optical lenses or films, respectively, to corresponding first and second detectors ( 291, 292), and according to this configuration, deviations due to changes in the characteristics of not only the detector but also the light source can be corrected through the analysis device 500, which will be described later.

The optical waveguide 230 may have the same structure as the above-described embodiment, and is filled with sample gas inside, and as an optical path is formed, infrared light incident from the light incident part is totally reflected and is emitted to the light exit part along the optical path. make it possible

The first and second filters 261 and 262 are optical members that pass only light in a specific wavelength band, and limit the wavelength according to the characteristics of the target material to be measured, thereby allowing only infrared light having a wavelength band corresponding to the characteristics of the target material to be measured. Let it be incident on this detector.

In addition, the first and second detectors 291 and 292 detect infrared light incident through the first and second filters 261 and 262, respectively, and output an electrical signal according to the intensity of the light. You can.

In addition, according to the above-described structure, the infrared light L1 passing through the first filter 261 is incident on the first detector 291, and the infrared light L2 passing through the second filter 262 is incident on the second detector 291. Although the structure incident on the detector 292 is exemplified, a structure that allows the state of each detector to be determined using mechanical means that can change the corresponding structure can be applied.

In detail, the first and second filters 261 and 262 and the first and second detectors 291 and 292 are respectively rotatable and are coupled to the first and second disks 265 and 295 arranged side by side. Initially, the first filter 261 and the first detector 291 may be arranged in a line along with the light emitting part of the optical waveguide, and the second filter 262 and the second detector 292 may be arranged in a line. there is. Afterwards, when it is desired to change the position and structure of the filter and detector, the second filter 262 and the first filter 291 are connected to the light emitting unit by rotating the first disk 265 and fixing the second disk 295. and the first filter 261 and the second filter 292 may be arranged in line.

Alternatively, by fixing the first disk 265 and rotating the second disk 295, the first filter 261 and the second disk 292 are arranged in line with the light emitting portion, and the second filter 262 and The first disks 291 can be arranged in a row.

According to this variable structure using a rotating disk, filters and detectors can be arranged in a total of four types of combinations, and the measurer can judge the characteristics of each component by changing the arrangement structure of the filter and detector depending on the intention and obtain accurate results. CO ₂ measurement results can be obtained.

For example, the NDIR sensor 200 is a detection signal output from the first and second detectors 291 and 292, as well as errors due to deterioration of the elements mounted on the detector, as well as the first and second filters 261 and 262. The results may also vary depending on deterioration, etc.

In order to overcome this problem, according to one embodiment of the present invention, when the detection signal output from the detector in the initial state has a difference greater than a threshold value, the first disk 295 is rotated so that the second filter 296 is connected to the first filter 296. Change the arrangement to correspond to the detector 261 and proceed with the detection procedure again to compare the newly measured detection signal with the previous detection signal to identify the component where the problem actually occurred and take action.

The analysis device 500 receives a detection signal and calculates a concentration value for the target substance. It receives detection signals from different channels through the first and second detectors 291 and 292, and detects at least two or more detection signals. The concentration value for CO ₂ can be calculated and provided by calculating the average value through a converter, subtractor, etc., or by correcting it using a correction coefficient (k).

Additionally, the analysis device 500 can correct the concentration value by multiplying the average value by the correction coefficient (k) when the deviation between the two detection signals of different channels is greater than a threshold.

In addition, the analysis device 500 may be further connected to a temperature sensor 600 installed on one surface of the optical waveguide 230, especially at a location where the temperature rise rate is high, and then detect the temperature measured from the optical waveguide 230. You can input the results and refer to them when correcting the concentration value.

The temperature sensor 600 may be placed at a location capable of measuring the temperature change of the NDIR sensor 200, preferably on one surface of the optical waveguide 230, and measures the temperature of the optical waveguide 230 to measure the temperature of the optical waveguide 230. (230) The temperature applied to the detector 291, including the inside, can be detected. This temperature sensor 600 can be electrically connected to the analysis device 500 and the control device 630, which will be described later, to transmit temperature measurement results.

The control device 630 receives the measurement result of the current temperature of the optical waveguide 230 transmitted from the temperature sensor 600, and is disposed in the first and second light sources 211 and 212 when the temperature increases above a certain level. By controlling the cooler 650, errors due to temperature can be minimized.

The cooler 650 is disposed adjacent to the first and second light sources 211 and 212, and can cool the heat generated from the light source by operating under the control of the control device 630. The cooler 650 may be a mechanical cooling device combining a heat sink and a fan, or a thermoelectric element applied with the Peltier effect that lowers the temperature of the contact surface with the light source according to the control voltage of the control device 630.

According to the above-described structure, in addition to the concentration value correction function through the analysis device, measurement error due to heat generated from the light source can be minimized through the cooling function of the light source when the temperature rises through the temperature sensor.

In the following description, a structure that easily dissipates heat applied to the optical waveguide 350 by forming a plurality of heat dissipation patterns with concave-convex cross-sections on the outer surface of the optical waveguide 350 will be described.

Figure 5 is a diagram showing the structure of an NDIR sensor with multiple channels according to an embodiment of the present invention.

Referring to FIG. 5, a light source 310 emitting infrared light, a light entering part and a light exiting part opening at both ends are formed, and a sample is filled with light passing through the light entering part where the light source 310 is placed. An optical waveguide 330 that configures an optical path to pass through the gas and reach the light exit section, and first and second filters 361 and 362 that are disposed in the light exit section of the optical waveguide 330 and allow light of a specific wavelength band to pass through. , first and second detectors (391, 392) that generate detection signals by receiving light of different channels that have passed through the first and second filters (361, 362), respectively, and receive the detection signals to detect the target material. An analysis device (500) that calculates the concentration value, but corrects and outputs the concentration value if the deviation between the detection signals of different channels is greater than a threshold, and a temperature sensor (600) installed on the outer surface of the optical waveguide 330 to measure the temperature. ), and a control device 630 that receives the temperature value of the NDIR sensor 200 measured by the temperature sensor 600, and the control device 630 surrounds the outer surface of the optical waveguide 330. It is further connected to a cooling water supply unit 670 that supplies cooling water to the pipes, and supplies coolant to the pipes (CB) according to the temperature measured by the temperature sensor 600.

In addition, the optical waveguide 330 may further include a heat dissipation pattern 335, the outer surface of which protrudes at a certain height in the vertical direction and forms a concavo-convex shape, and the pipe CB has the heat dissipation pattern 335. It can be wound inside the yaw shape.

In detail, the light source 310 is equipped with a predetermined infrared light-emitting element and can irradiate infrared light (L1, L2) in one direction. The emitted infrared light (L1, L2) passes through the optical path inside the optical waveguide 330 and is incident on the first and second filters (361, 362), and is specified by the first and second filters (361, 362). It may be filtered into a wavelength band and incident on a light receiving element mounted on the detector 320.

The detector 320 may detect infrared light incident through a filter 360, which will be described later, and output an electrical signal according to the intensity of the light.

The optical waveguide 330 may have the same structure as the first embodiment described above, and is filled with sample gas inside, and as an optical path is formed, infrared light incident from the light incident part is totally reflected and flows to the light exit part along the optical path. So that it can be released as .

In particular, according to the third embodiment of the present invention, a plurality of heat dissipation patterns 335 whose cross-sections are repeated in a concave-convex shape may be formed on the outer surface of the optical waveguide 330.

These heat dissipation patterns 335 may be circular, square, or polygonal when viewed from the side of the optical waveguide 330, and may be formed in multiple numbers spaced apart at regular intervals.

Additionally, the heat dissipation pattern 335 may be formed in a longitudinal direction perpendicular to the optical waveguide 330, or may be formed in a diagonal direction inclined at a predetermined angle. The diagonally inclined structure can secure a larger heat dissipation area without expanding the overall thickness of the optical waveguide 330.

In addition, in the concave portion formed in each heat dissipation pattern 335, a cooling pipe (CB) mounted on the TOC measurement system and connected to the coolant supply part may be combined in a wound form in a certain area, especially adjacent to the light source 310, Through this structure, the temperature of the optical waveguide 350 can be absorbed and kept lower.

The first and second filters 361 and 362 limit the wavelength according to the characteristics of the target material to be measured, so that only infrared light with a wavelength band corresponding to the characteristics of the target material is incident on the detectors 390 and 392. .

The analysis device 500 receives a detection signal and calculates a concentration value for the target substance. It receives detection signals from different channels through the first and second detectors 390 and 392, and detects at least two or more detection signals. The concentration value for CO ₂ can be calculated and provided by calculating the average value through a converter, subtractor, etc., or by correcting it using a correction coefficient (k).

Additionally, the analysis device 500 can correct the concentration value by multiplying the average value by the correction coefficient (k) when the deviation between the two detection signals of different channels is greater than a threshold.

In addition, the analysis device 500 may be further connected to a temperature sensor 600 installed on one surface of the optical waveguide 330, especially at a location where the temperature rise rate is high, and then detect the temperature measured from the optical waveguide 330. You can input the results and refer to them when correcting the concentration value.

The temperature sensor 600 may be placed at a location capable of measuring the temperature change of the NDIR sensor 300, preferably on one surface of the optical waveguide 330, and measures the temperature of the optical waveguide 330 to measure the temperature of the optical waveguide 330. (330) The temperature applied to the detector 391, including the inside, can be detected. This temperature sensor 600 is electrically connected to the control device 630 and can transmit temperature measurement results.

The control device 630 may receive the current temperature measurement result of the optical waveguide 330 transmitted from the temperature sensor 600. In particular, according to an embodiment of the present invention, the control device 630 may be further connected to a separate coolant supply unit 670, and when the temperature measurement result is received and the temperature rises above a certain level, the control device 630 controls the coolant supply unit 670. By supplying cooling water to the cooling pipe (CB) wound around the optical waveguide 330, the temperature of the optical waveguide 330 can be quickly lowered.

Hereinafter, a TOC measurement system according to an embodiment of the present invention, which is equipped with an NDIR sensor having the above-described structure and measures total organic carbon, will be described in detail.

Figure 6 is a diagram showing the structure of a TOC measurement system including an NDIR sensor with multiple channels according to an embodiment of the present invention.

Referring to FIG. 6, the TOC measurement system 1000 according to an embodiment of the present invention includes a syringe 1100 for mixing and delivering a sample, a syringe 1100 through a plurality of ports, and one or more solution supply units ( 1300) and a rotary valve 1200 connecting the sample supply unit 1350, an MFC 1400 that controls the movement of fluid and gas in each pipe connected to the rotary valve 1300, and 0 ₂ gas is supplied to the MFC 1400. An oxygen valve (1500) that supplies oxygen, a UV-reactor (1600) that receives the fluid contained within the syringe (1100), removes inorganic carbon, oxidizes the remaining organic carbon to generate carbon dioxide, and generates sample gas, and generates carbon dioxide. A moisture removal unit 1700 that removes internal moisture, first and second filters that pass light in a specific wavelength band, and light in different channels that pass through the first and second filters, respectively, are received and detected. It includes first and second detectors that generate signals, and an NDIR sensor 100 that receives a detection signal and calculates a concentration value for the target substance, and the NDIR sensor 100 transmits two channels of detection signals. It may include an analysis device 500 that receives the concentration value for the target substance and calculates the concentration value through the average value, but corrects the concentration value and outputs the concentration value if the average value is more than a threshold value.

Additionally, the NDIR sensor 100 may be equipped with a temperature sensor 600 that measures the temperature of the optical waveguide.

In detail, the syringe 1100 serves to preprocess the sample that is the subject of analysis for measuring total organic carbon and transport it to each component. To this end, the syringe may be made of ceramic material to minimize damage from reagents or heat, and liquid, gas, etc. can be injected or discharged into the syringe as the coupled plunger moves up and down.

The rotation valve 1200 may be connected to be rotatable at the bottom of the syringe 1100 in the forward or reverse direction depending on the number of ports mounted thereon. As an example, in the case of a rotary valve 1200 having 10 ports, it can be rotated 36° at a time and may have a structure that can be connected to any one of each port when rotated.

Here, the 10 ports of the rotary valve 1200 include ports for transferring various fluids, including a blockage port, UV system connection port, sample port, phosphoric acid port, standard solution port, distilled water port, and air port. . Accordingly, the rotary valve 1200 can transfer different fluids, including samples, distilled water, phosphoric acid, NaOH, and standard solutions, one by one into the interior of the syringe 1100 as the syringe 1100 moves up and down.

In particular, one of the plurality of pipes connected to the rotary valve 1200 may be connected to surround a portion of the outer surface of the optical waveguide of the NDIR sensor 100, and this cooling pipe (CB) is connected to the rotary valve 1200. ) The NDIR sensor 100 can be cooled by periodically transferring distilled water or separate cooling water depending on the port connection.

In addition, it is connected to the above-described rotary valve 1200 and 10 ports, respectively, and may include a supply unit 1300 and a sample supply unit 1350 that supply distilled water, phosphoric acid, NaOH, and standard solutions to the syringe 1100. .

The MFC 1400 may be installed in a pipe that bypasses the supply pipe through which oxygen gas is supplied toward the oxygen valve 1500 and the connection pipe connecting the rotary valve 1200 and the UV-reactor 1600.

The oxygen valve 1500 is provided in a line that supplies oxygen gas toward the rotary valve 1200 and serves to remove inorganic carbon by supplying oxygen gas to the inside of the syringe 1100.

The UV-reactor 1600 receives the fluid contained in the syringe 1100 by rotating the rotary valve 1200, removes the inorganic carbon, and oxidizes the remaining organic carbon to generate carbon dioxide.

The moisture removal unit 1700 is connected to the gas injection unit and the UV reactor 1600 of the NDIR sensor 100 and serves to protect the sensor by removing moisture from the gas flowing into the NDIR sensor 100 and releasing it to the outside. .

Hereinafter, the driving process of the TOC measurement system including the NDIR sensor according to the above-described structure will be described.

First, the syringe 1100 supplies solutions to generate gas samples such as distilled water, phosphoric acid, and NaOH from each solution supply unit 1300, and liquid samples from the sample supply unit 1350 through each port of the rotary valve 1200. will be transferred to.

At this time, the rotary valve 1200 is placed at the initial blocked position and can be rotated by 36° in the forward or reverse direction during measurement to move to a total of 10 ports, so that the fluid and syringe corresponding to each port are connected, and the syringe (1100) ) Each fluid can be transported by up and down movement.

When the measurement starts, in the initialization stage, the rotary valve 1200 moves to the blocked position and the syringe 1100 moves to the starting position. When the rotary valve 1200 rotates in the forward direction and the port changes, the syringe 1100 moves to the closed position. It is connected to the sample supply unit 1350, and then the syringe 1100 moves upward to transfer the sample therein.

Then, when the rotary valve 1200 sequentially moves at a predetermined angle in the forward direction from the position connected to the sample supply unit 1350, the syringe 1100 and each solution supply unit 1300 are connected to each other, and the syringe 1100 is moved to the upper part. By moving to , various prepared solutions such as phosphoric acid can be transferred to the inside of the syringe (1100).

At this time, the mixer mounted on the syringe 1100 is operated so that the sample and the solution can be mixed inside the syringe 1100.

In addition, in order to remove inorganic carbon generated during the process of mixing the sample and the solution, the rotary valve 1200 can move in the forward direction at a predetermined angle, and the oxygen valve 1500 is opened to allow oxygen into the inside of the syringe 1100. Gas may enter.

Here, although not shown, a separate auxiliary valve may be installed in the pipe connecting the rotary valve 1200 and the oxygen valve 1500 to control the amount of oxygen gas supplied into the syringe 1100.

Next, the Mass Flow Controller (MFC) 1400 is turned on to remove CO ₂ present inside the flow path formed through the piping. After the TOC measurement task is completed, the MFC 1400 may be turned off.

Then, after the inorganic carbon is removed, the rotary valve 1200 can be connected to the solution supply unit 1300 for supplying NaOH by rotating in the reverse direction at a predetermined angle, and at the same time, the syringe 1100 moves upward and rotates. The valve 1200 rotates in the forward direction at a predetermined angle and is positioned at the blocked position to mix the received fluid.

As the mixing process progresses, the rotary valve 1200 moves again in the forward direction, and the syringe 1100 moves downward to transfer the mixed fluid inside the syringe 1100 to the UV-reactor 1600. there is.

Next, the UV reactor 1600 decomposes organic carbon to generate CO ₂ . At this time, the generated CO ₂ passes through the moisture removal unit 1700 through oxygen gas control in the MFC 1400 and moisture is removed.

Afterwards, CO ₂ is transferred to the NDIR sensor 100 and converted into a TOC measurement value. The NDIR sensor 100 uses non-dispersive infrared rays, and the UV-reactor 1600 detects the concentration of CO ₂ , which is then used to calculate TOC contained in the sample.

In addition, the analysis device mounted on the NDIR sensor 100 compares the detection signals input from the two channels and calculates the average value if the deviation is less than the threshold, and if the deviation is more than the threshold, a correction coefficient (k) is added to the difference value of the detection signals input from the two channels. ) By performing correction using ), the occurrence of errors due to device deterioration, etc. can be minimized.

In addition, when CO ₂ is detected from a gas sample, the NDIR sensor 100 performs temperature measurement in real time from a temperature sensor installed in the optical waveguide and reflects it in the correction coefficient (k), or lowers the temperature of the light source through a control device or cools it. The temperature of the optical waveguide can be lowered by supplying cooling water through the pipe (CB).

Although many details are described in detail in the above description, this should be interpreted as an example of a preferred embodiment rather than limiting the scope of the invention. Therefore, the invention should not be determined by the described embodiments, but by the scope of the patent claims and their equivalents.

100, 200, 300: NDIR sensor 110, 211, 212, 220: light source
130, 230, 330: optical waveguide 161, 261, 361: first filter
162, 262, 362: second filter 191, 291, 390: first detector
192, 292, 392: second detector 500: analysis device
510: A/D converter 520: Noise removal unit
530: average value calculation unit 540: correction unit
550: display device 600: temperature sensor
630: Control device 650: Cooler
670: Cooling water supply unit

Claims (9)

A light source emitting infrared light;
An optical waveguide is formed with a light entering part and a light exiting part opened at both ends, and configures an optical path so that light traveling through the light entering part where the light source is disposed passes through a sample gas filled therein and reaches the light emitting part;
First and second filters disposed at the light exit portion of the optical waveguide and allowing light of a specific wavelength band to pass through;
First and second detectors that generate detection signals by receiving light of different channels that have passed through the first and second filters, respectively; and
An analysis device that receives detection signals from two channels and calculates the concentration value for the target substance through the average value, and corrects and outputs the concentration value if the average value is above the threshold.
NDIR sensor including. According to claim 1,
The analysis device is,
An A/D converter that receives first and second detection signals, which are analog waveforms, from the first and second detectors and converts them into digital waveforms;
a noise removal unit that reduces noise existing in the first and second detection signals of the digital waveform and compensates for the linearity of the first and second detection signals;
an average value calculation unit that calculates the average value of the first and second detection signals from which noise has been removed; and
If the average value is above the threshold, a correction unit corrects by multiplying the preset concentration value by a correction coefficient.
NDIR sensor including. According to claim 2,
The correction unit,
An NDIR sensor connected to a temperature sensor installed on one side of the optical waveguide and increasing or decreasing the size of the correction coefficient in response to the temperature measured from the temperature sensor. According to claim 1,
The optical waveguide is,
An NDIR sensor whose outer surface further includes a heat dissipation pattern that protrudes at a certain height in the vertical direction and forms a concavo-convex shape. According to claim 1 or 4,
The NDIR sensor is,
It includes a control device connected to a temperature sensor installed on the outer surface of the optical waveguide,
The control device is,
The NDIR sensor is further connected to a cooler that cools the light source in response to the temperature measured from the temperature sensor. According to claim 1,
a first rotatable disk on which the first and second filters are mounted; and
A second disk disposed in parallel with the first disk, equipped with the first and second detectors, and rotatable,
The first and second disks,
An NDIR sensor that arranges the light emitting part of the optical waveguide, the first or second filter, and the first or second detector in a line as one or both are rotated. A syringe that mixes and delivers samples;
a rotary valve connecting the syringe to one or more solution supply units and a sample supply unit through a plurality of ports;
MFC controlling the movement of fluid and gas within each pipe connected to the rotary valve;
An oxygen valve supplying 0 ₂ gas to the MFC;
a UV-reactor that receives the fluid contained within the syringe, removes inorganic carbon, oxidizes the remaining organic carbon, and generates carbon dioxide to generate sample gas;
A moisture removal unit that removes moisture inside the generated carbon dioxide; and
It includes first and second filters that pass light of a specific wavelength band, and first and second detectors that generate detection signals by receiving light of different channels that pass through the first and second filters, respectively, It includes an NDIR sensor that receives the detection signal and calculates a concentration value for the target substance,
The NDIR sensor is,
A TOC measurement system comprising an analysis device that receives detection signals from two channels and calculates a concentration value for the target material through the average value, and corrects and outputs the concentration value when the average value is greater than a threshold. According to claim 7,
In the NDIR sensor, the optical waveguide further includes a heat dissipation pattern whose outer surface protrudes at a certain height in the vertical direction to form a concavo-convex shape,
A cooling pipe connected to a port of the rotary valve through which cooling liquid is transferred and wound inside the yaw shape of the heat dissipation pattern.
TOC measurement system further comprising: According to claim 8,
The rotary valve is,
A TOC measurement system that connects the cooling pipe and the contained sample supply or solution supply when transferring a sample or solution in which a chemical reaction is activated at a high temperature during the sample gas generation process.

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