Portable non-dispersive infrared gas analyzer for low concentration gas measurement and measurement method thereof

Abstract

The present invention relates to a portable non-dispersive infrared gas analysis device for measuring low-concentration gases. It first removes moisture and corrosive gases in an external pretreatment filter unit, performs further purification in an internal dust filter unit and an internal moisture filter unit, and measures the gas concentration in an NDIR sensor unit. A pump unit is placed downstream of the sensor to protect the pump from corrosive gases, and an external flow meter unit is installed at the outlet side to verify the normal operation of the equipment in real time. Furthermore, it applies an adaptive measurement algorithm that calculates the moving average of the measured values ​​and immediately outputs the actual measured value when the change exceeds a preset fluctuation rate, thereby ensuring both measurement stability and rapid response. According to the present invention, it is possible to precisely measure low-concentration gases of 0.3 ppm or less, use them stably for a long period even in corrosive gas environments, and provide a portable device that can be used immediately at semiconductor factory sites.

Description

Technology Field

[0001] The present invention relates to a gas measuring device using a non-dispersive infrared (NDIR) method, and more specifically, to a portable gas analysis device and a measurement method equipped with an optimized gas flow arrangement structure and an adaptive measurement algorithm for measuring low-concentration greenhouse gases generated in semiconductor processes. Background Technology

[0002] Non-Dispersive Infrared (NDIR) is a method for measuring gas concentration by utilizing the characteristic that gas molecules absorb infrared radiation of a specific wavelength. It is known to have higher accuracy and a longer lifespan compared to electrochemical or semiconductor sensors. An NDIR gas sensor consists of an infrared light source, a photodetector, and an optical waveguide. The gas concentration is calculated by measuring the degree to which the gas to be measured is introduced into the optical waveguide and absorbs infrared radiation of a specific wavelength.

[0003] Korean Registered Patent Publication No. 10-0574616 (Registration Date: April 20, 2006) relates to an "NDIR gas sensor" and proposes an optical cavity structure composed of two concave mirror surfaces. However, this patent focuses only on the structure of the optical system and does not specifically disclose the overall arrangement structure of the gas measurement system or the gas pretreatment method.

[0004] Korean Published Patent Application No. 10-2011-0034330 (Publication Date: April 6, 2011) relates to a "non-dispersive infrared (NDIR) carbon dioxide (CO2) gas sensor" and presents an algorithm for compensating for fluctuations in measurement values ​​due to temperature. However, this patent focuses only on temperature compensation and does not address a method for rapidly detecting sudden changes in gas concentration.

[0005] Korean Registered Patent Publication No. 10-0838255 (Registration Date: June 6, 2008) relates to a "self-temperature-compensated non-dispersive infrared gas sensor" and proposes a method to eliminate changes in output voltage due to changes in ambient temperature by using a differential amplifier circuit. However, this patent is also limited to the temperature compensation circuit and does not disclose the configuration or arrangement of the entire gas measurement system.

[0006] Korean Registered Patent Publication No. 10-1842799 (Registration Date: March 20, 2018) relates to "a method for calculating a correction factor of NDIR and a method for measuring gas concentration of NDIR using the calculated correction factor," and presents a method for accurately measuring concentration using a correction factor under conditions where interfering gas is present. However, this patent focuses only on the correction of interfering gas and does not address hardware configuration for measuring low-concentration gas or gas flow optimization.

[0007] Conventional NDIR gas measuring devices have the following problems.

[0008] First, it is difficult to accurately measure low-concentration gases at the 0.3 to 1.0 ppm level required in semiconductor processes. This is because various noise factors generated during the measurement process are not properly eliminated.

[0009] Second, there is a problem where pumps are rapidly damaged in environments containing corrosive gases. In conventional technology, pumps are often placed during the initial stage of gas inflow, leading to direct exposure to untreated corrosive gases and a shortened lifespan.

[0010] Third, it is difficult to simultaneously satisfy both measurement stability and response speed. There is a trade-off: performing average processing to ensure measurement stability slows down the response speed, while outputting real-time measurements for a faster response increases noise and degrades stability.

[0011] Fourth, it is difficult to check in real time whether the equipment is operating normally. Even if problems such as filter clogging or pump failure occur, there is a lack of means to detect them immediately, which may result in inaccurate measurements being output for a long time.

[0012] Fifth, it fails to meet the mobility and convenience required in semiconductor manufacturing sites. Existing precision gas analysis equipment is large, heavy, and relies on external power sources, presenting limitations that make it difficult to use while moving to various measurement points.

[0013] Therefore, there is a need to develop a new gas measuring device that can simultaneously satisfy the accurate measurement of low-concentration gases required in semiconductor process sites and the stable operation of equipment. Prior art literature

[0014] Korean Registered Patent Publication No. 10-0574616 (Registration Date: April 20, 2006) Korean Published Patent Publication No. 10-2011-0034330 (Publication Date: April 6, 2011) Korean Registered Patent Publication No. 10-0838255 (Registration Date: June 6, 2008) Korean Registered Patent Publication No. 10-1842799 (Registration Date: March 20, 2018) The problem to be solved

[0015] The present invention is intended to solve the problems of the aforementioned prior art, and its purpose is as follows.

[0016] The first objective of the present invention is to provide a gas analysis device capable of accurately measuring low-concentration gases.

[0017] The second objective of the present invention is to provide a gas analysis device having an optimized gas flow arrangement structure that can extend the life of a pump even in a corrosive gas environment.

[0018] The third objective of the present invention is to provide a gas analysis device equipped with an adaptive measurement algorithm capable of simultaneously satisfying measurement stability and a fast response speed.

[0019] The fourth objective of the present invention is to provide a gas analysis device capable of verifying the normal operation of equipment in real time.

[0020] The fifth objective of the present invention is to provide a portable gas analysis device that can be used while moving at a semiconductor process site.

[0021] The sixth objective of the present invention is to provide a gas analysis device in which the sensor module is easily replaceable so as to be able to respond to the measurement of various types of gases. means of solving the problem

[0022] A portable non-dispersive infrared gas analyzer for measuring low-concentration gases according to the present invention for achieving the above objective comprises the following configuration.

[0023] The present invention comprises a housing including an inlet into which a gas to be measured is introduced. The housing is made of aluminum to ensure rigidity, and each component is fixed inside in an optimized arrangement.

[0024] The housing is provided with an external pretreatment filter unit that primarily pretreats gas introduced from the inlet. The external pretreatment filter unit is formed as a transparent container structure so that the condition of the internal filling material can be visually checked, and a hole penetrating vertically is formed in the center of the container, and the space surrounding the hole is filled with activated alumina, silica gel, or a mixture thereof. The external pretreatment filter unit has a structure in which gas introduced through the upper inlet passes between the filling materials, moves downward, collects in the side space, and is discharged through the side outlet. This structure allows the gas to come into sufficient contact with the filling materials to effectively remove some of the moisture and corrosive gases.

[0025] The device is equipped with an internal dust filter that removes dust from the gas passing through the external pretreatment filter. The internal dust filter collects fine particulate impurities to protect the downstream sensor.

[0026] The device is equipped with an internal moisture filter that further removes moisture from the gas passing through the internal dust filter. The internal moisture filter further removes residual moisture not removed by the external pretreatment filter, thereby minimizing the humidity of the gas entering the sensor and improving measurement accuracy.

[0027] The device is equipped with an NDIR sensor unit that measures the concentration of gas passing through the built-in moisture filter unit. The NDIR sensor unit includes an infrared light source, an optical waveguide, an optical detector, and a signal processing circuit, and, for example, a dual-beam non-dispersive infrared sensor module may be used. The NDIR sensor unit is formed with a replaceable module structure depending on the type of gas to be measured, and can respond to the measurement of various gases such as CF4, N2O, NF3, CO2, CH4, and THC.

[0028] A pump unit is provided to suck in the gas that has passed through the NDIR sensor unit and transfer it to an outlet. The pump unit may be composed of a diaphragm pump, for example, the SC3704PM-DC12V model may be used. One of the key features of the present invention is that the pump unit is positioned downstream of the NDIR sensor unit. Through this arrangement, the pump comes into contact with the gas that has passed through the external pretreatment filter unit, the internal dust filter unit, and the internal moisture filter unit, thereby preventing damage to the pump caused by corrosive gases and significantly extending the lifespan of the pump.

[0029] An external flow meter is provided, positioned at the downstream end of the pump unit, to display the flow rate of the discharged gas. The external flow meter has a flow rate scale marked inside a transparent container, allowing the user to visually check the gas flow rate. The external flow meter functions as a means to check the normal operation status of the equipment in real time. During normal operation, a flow rate of approximately 1 liter per minute (1L / min) is maintained, and if a problem such as filter clogging, pump failure, or flow path blockage occurs, the flow rate decreases, allowing the user to immediately recognize the abnormality.

[0030] A data processing unit is provided to calculate the gas concentration by processing the signal output from the NDIR sensor unit. The data processing unit includes a microcontroller unit (MCU), an analog-to-digital converter (ADC), and a communication module. The data processing unit implements an adaptive measurement algorithm, which ensures measurement stability by calculating and outputting a moving average of the measured value under normal circumstances, but stops the average processing and immediately outputs the actual measured value when a new measured value is detected to change by more than a preset fluctuation rate (e.g., ±1.0%) compared to the previous measured value. Through this algorithm, measurement stability and a fast response speed can be achieved simultaneously, and the maximum value can be captured within 10 seconds in situations of rapid concentration changes, such as gas leakage.

[0031] A first display unit is provided to display the measured gas concentration. The first display unit is composed of an LCD screen and displays the measured gas concentration as a constant with 3 digits and 1 decimal place (e.g., 999.9 ppm) or a constant with 4 digits (e.g., 1234 ppm).

[0032] A second display unit is provided, which is formed separately from the first display unit and displays the battery status. The second display unit displays the remaining battery charge, current output voltage, and charging status, and indicates that charging is required if the battery voltage drops below a preset value. Through this dual display structure, the user can simultaneously monitor the gas concentration and the equipment status.

[0033] A battery unit is provided to supply power to each of the above components. The battery unit is composed of a lithium-ion battery (DC 12V, 10200mAh) and can operate continuously for about 30 hours when fully charged, allowing for long-term use in the field.

[0034] A communication unit is provided for transmitting gas concentration data from the above data processing unit to the outside. The communication unit is configured to selectively use at least one method among UART, RS485 Modbus, or 4 to 20 mA analog output.

[0035] The gas analysis device of the present invention having such a configuration is arranged so that gas flows in the order of an external pretreatment filter unit, an internal dust filter unit, an internal moisture filter unit, an NDIR sensor unit, a pump unit, and an external flow meter unit, thereby providing an optimized structure in which impurities are sequentially removed at each stage, the pump comes into contact with the pretreated gas, and finally, the flow rate is checked to determine whether normal operation is possible.

[0036] The present invention also provides a method for measuring gas using the gas analysis device. The method comprises the steps of introducing a gas to be measured into an inlet, removing moisture and corrosive gas in a first step in an external pretreatment filter unit, removing fine particles in an internal dust filter unit, further removing residual moisture in an internal moisture filter unit, measuring the gas concentration in an NDIR sensor unit, calculating the final concentration by applying an adaptive algorithm in a data processing unit, discharging the measured gas in a pump unit, and determining whether normal operation is being performed by checking the flow rate in an external flow meter unit. Effects of the invention

[0037] The portable non-dispersive infrared gas analysis device and the measurement method for low-concentration gas of the present invention have the following effects.

[0038] First, through a multi-stage filtering structure and optimized circuit design, low-concentration gases at the 0.3 ppm level can be accurately measured. This enables precise exhaust gas monitoring required in semiconductor process scrubbers.

[0039] Second, by placing the pump downstream of the NDIR sensor unit, the pump comes into contact only with the pre-treated gas, thereby preventing damage caused by corrosive gases. During the actual development process, it was confirmed that when the pump was placed upstream, it corroded within 3 to 4 days, but after being placed downstream, it operated normally for more than 1 month.

[0040] Third, through an adaptive measurement algorithm, stability is ensured by processing average values ​​under normal conditions, and a fast response speed is provided by immediately outputting actual values ​​when concentration changes, thereby simultaneously satisfying the conflicting requirements of measurement stability and response speed.

[0041] Fourth, by placing an external flow meter immediately before the outlet, the user can visually check the flow rate, thereby immediately detecting abnormal situations such as filter clogging or pump failure. This prevents inaccurate measurement values ​​from being output and improves the reliability of the equipment.

[0042] Fifth, through an adaptive measurement algorithm, measurement stability is ensured using a moving average during normal operation, and if the gas concentration changes rapidly by more than ±1.0%, it outputs immediately to provide a fast response speed within 10 seconds.

[0043] Sixth, the battery-powered method and compact, lightweight structure (400×220×180mm, 3.8kg) provide convenience for use while moving to various measurement points in the semiconductor process site.

[0044] Seventh, the NDIR sensor unit is configured in a module replacement manner, allowing a single device to handle the measurement of various gases such as CF4, N2O, NF3, CO2, CH4, and THC, making it highly versatile.

[0045] Eighth, user convenience is improved as gas concentration and battery status can be checked simultaneously through the dual display.

[0046] Ninth, the transparent container structure and ease of replacement of the external pre-treatment filter unit make maintenance simple, and the filter replacement time can be determined visually. Brief explanation of the drawing

[0047] FIG. 1 is a block diagram showing the overall configuration of a portable non-dispersive infrared gas analyzer for measuring low-concentration gas according to one embodiment of the present invention. FIG. 2 is a cross-sectional view showing the structure of an external pretreatment filter unit according to one embodiment of the present invention. FIG. 3 is a flowchart illustrating the operation of an adaptive measurement algorithm according to one embodiment of the present invention. FIG. 4 is a circuit diagram showing a circuit configuration according to one embodiment of the present invention. FIG. 5 is a photograph showing the exterior of a gas analysis device according to one embodiment of the present invention. Specific details for implementing the invention

[0048] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. However, the technical concept of the present invention is not limited to some of the described embodiments but can be implemented in various different forms, and within the scope of the technical concept of the present invention, one or more of the components among the embodiments may be selectively combined and substituted.

[0049] In addition, terms used in the embodiments of the present invention (including technical and scientific terms) may be interpreted in a meaning that is generally understood by those skilled in the art to which the present invention belongs, unless explicitly and specifically defined otherwise. Terms that are commonly used, such as terms defined in advance, may be interpreted in consideration of their meaning in the context of the relevant technology.

[0050] Furthermore, the terms used in the embodiments of the present invention are for describing the embodiments and are not intended to limit the present invention. In this specification, the singular form may include the plural form unless specifically stated otherwise in the text, and terms such as "comprising" or "comprising" do not exclude the presence or addition of one or more other components in addition to the mentioned components.

[0051] In addition, terms such as first, second, A, B, (a), (b), etc., may be used when describing the components of the embodiments of the present invention. These terms are used merely to distinguish the components from other components and are not intended to limit the essence, order, or sequence of the components.

[0052] And, where it is stated that a component is 'connected,' 'coupled,' or 'connected' to another component, it should be understood that the component is not only directly connected, coupled, or connected to the other component, but that a third component may be 'connected,' 'coupled,' or 'connected' between the component and the other component. Here, 'connection,' 'coupled,' or 'connected' may include not only physical connections but also electrical or telecommunication connections.

[0054] <실시예 1>

[0055] With reference to FIGS. 1 to 5, a portable non-dispersive infrared gas analysis device for measuring low-concentration gas according to the first embodiment of the present invention (hereinafter referred to as the "gas analysis device") will be described.

[0056] FIG. 1 is a block diagram showing the overall configuration of a gas analysis device (100) according to the present embodiment. Referring to FIG. 1, the gas analysis device (100) of the present embodiment includes a housing (110), an external pretreatment filter unit (120), an internal dust filter unit (130), an internal moisture filter unit (140), an NDIR sensor unit (150), a pump unit (160), an external flow meter unit (170), a data processing unit (180), a first display unit (191), a second display unit (192), a battery unit (195), and a communication unit (198).

[0057] The housing (110) is formed of aluminum material and, in this embodiment, has a black surface finish. The size of the housing (110) is approximately 400 mm (width) x 220 mm (height) x 180 mm (thickness), and the weight is approximately 3.8 kg. A handle (111) is formed on the upper part of the housing (110) so that the user can easily carry and move the equipment. A first display unit (191) and a second display unit (192) are arranged on the front of the housing (110), and a gas inlet (112) and a gas outlet (113) are formed on the side. Inside the housing (110), each component is firmly fixed through a fixing member (e.g., bracket, screw, or adhesive).

[0058] Looking at the gas flow arrangement structure of the present embodiment, the gas to be measured flows in the order of external pretreatment filter section (120) → internal dust filter section (130) → internal moisture filter section (140) → NDIR sensor section (150) → pump section (160) → external flow meter section (170) → outlet (113). This arrangement is an optimized structure so that the gas is sequentially pretreated and introduced into the sensor, discharged by the pump after measurement, and finally the flow rate can be checked.

[0059] FIG. 2 is a cross-sectional view showing the structure of an external pretreatment filter unit (120) according to the present embodiment. Referring to FIG. 2, the external pretreatment filter unit (120) is formed as a transparent cylindrical container (121), and a central hole (122) that penetrates vertically is formed in the center of the container (121). A filler (123) is filled in the space surrounding the central hole (122). As the filler (123), activated alumina, silica gel, or a mixture thereof may be used. In the present embodiment, activated alumina was used, and it was confirmed that its moisture removal ability is superior to that of silica gel.

[0060] Gas is introduced through the upper inlet (124) and descends along the central hole (122) while passing through the filler (123). During this process, some of the moisture and corrosive gases contained in the gas are removed by adsorption or reaction with the filler (123). The gas that reaches the bottom is collected in the side space (125) and then discharged through the side outlet (126). Through the structure of the transparent container (121), the user can visually check the color change or degree of contamination of the filler (123), making it easy to determine when to replace the filter.

[0061] The external pretreatment filter unit (120) is detachably fixed to the housing (110) by a screw connection method, so that when replacing the filter, it is easy to replace the entire container (121) or only the filling material (123).

[0062] The internal dust filter section (130) is placed inside the housing (110) and consists of a filter medium that captures fine particles. For example, a dust filter made of non-woven fabric can be used, and the pore size can effectively remove fine dust at the level of several micrometers.

[0063] The internal moisture filter section (140) is positioned at the rear end of the internal dust filter section (130) and further removes residual moisture that was not removed by the external pretreatment filter section (120). For example, a filter containing a desiccant such as silica gel or zeolite may be used. Through this dual moisture removal structure, the humidity of the gas entering the NDIR sensor section (150) can be minimized to improve measurement accuracy.

[0064] The NDIR sensor unit (150) includes an infrared light source (151), an optical waveguide (152), a photodetector (153), and a signal processing circuit (154). In this embodiment, a dual-beam NDIR sensor module is used, and for example, the Z-800 model (product of ELT SENSOR) can be used.

[0065] The infrared light source (151) emits infrared light in the wavelength range absorbed by the gas to be measured. For example, in the case of measuring CF4 gas, a light source emitting infrared light in the wavelength range of about 7.8 μm is used. The light source (151) operates in a pulse driving mode, and in this embodiment, pulses are applied at 2-second intervals to output measurement values.

[0066] The optical waveguide (152) provides a path for infrared rays emitted from the light source (151) to pass through the gas to be measured and reach the photodetector (153). Inside the optical waveguide (152), an inlet for gas to enter and an outlet for gas to exit are formed, and in this embodiment, a one-touch fitting with an outer diameter of 6 mm is used.

[0067] The photodetector (153) detects infrared rays passing through the gas and converts them into an electrical signal. For example, a thermopile-type detector can be used.

[0068] The signal processing circuit (154) amplifies and filters the electrical signal output from the photodetector (153). Referring to FIG. 4, the signal processing circuit (154) includes a reference voltage generator, a digital-to-analog converter (DAC), an amplifier, and an analog-to-digital converter (ADC).

[0069] The NDIR sensor unit (150) is configured in a module replacement manner, so that the sensor module can be replaced depending on the type of gas to be measured. For example, CF 4, It can handle the measurement of various gases such as N2O, NF3, CO2, CH4, and THC. This allows a single device to measure a wide range of gases, making it highly versatile.

[0070] The arrangement structure of the pump section (160), which is one of the key features of the present invention, will be explained. In the prior art, the pump was often placed at the front or in the middle of the external pretreatment filter section. In such a structure, the pump comes into direct contact with untreated corrosive gas, causing the diaphragm or valve inside the pump to corrode. In fact, when the pump was placed at the front during the development process, the pump rusted and stopped working within 3 to 4 days in a corrosive gas environment.

[0071] In the present invention, the pump unit (160) is positioned at the rear end of the NDIR sensor unit (150). In this structure, the pump unit (160) comes into contact with the gas that has passed through the external pretreatment filter unit (120), the internal dust filter unit (130), and the internal moisture filter unit (140), thereby preventing damage caused by corrosive gas. In fact, it was confirmed that the pump operated normally for more than one month after being positioned at the rear end, which means the pump lifespan was extended by more than 10 times.

[0072] The pump unit (160) is composed of a diaphragm pump, and in this embodiment, the SC3704PM-DC12V model was used. The pump unit (160) operates by receiving DC 12V power from the battery unit (195), and the current consumption is about 100mA during normal operation and about 700mA during peak operation.

[0073] The external flow meter (170) is positioned at the rear end of the pump unit (160), that is, immediately before the outlet (113). The external flow meter (170) has a flow scale marked inside a transparent container, allowing the user to visually check the gas flow rate. During normal operation, a flow rate of approximately 1 liter per minute (1L / min) is maintained. If a problem occurs, such as the external pre-treatment filter unit (120), the internal dust filter unit (130), or the internal moisture filter unit (140) becoming clogged, the pump unit (160) malfunctioning, or the flow path becoming blocked, the flow rate decreases, allowing the user to immediately recognize the abnormality. This prevents inaccurate measurement values ​​from being output and improves the reliability of the equipment.

[0074] With reference to FIG. 3, an adaptive measurement algorithm, which is another key feature of the present invention, will be described. FIG. 3 is a flowchart illustrating the operation of the adaptive measurement algorithm.

[0075] The data processing unit (180) receives a measurement value from the NDIR sensor unit (150) (S10). The measurement value is received at 2-second intervals.

[0076] The data processing unit (180) basically calculates a moving average of the last N (e.g., N=5) measurements (S20). This allows for the removal of measurement noise and the output of stable measurements.

[0077] The data processing unit (180) determines whether the new measurement value has changed by more than a preset rate of change compared to the previous average value (S30). In this embodiment, the rate of change is set to ±1.0%. For example, if the previous average value is 100 ppm, if the new measurement value is 101 ppm or more or 99 ppm or less, it is determined that the rate of change has exceeded the standard.

[0078] If the fluctuation rate exceeds the standard (S30: yes), the data processing unit (180) stops the average processing and outputs the new measurement value as the final concentration (S50). This allows for rapid detection of sudden changes in gas concentration.

[0079] Next, the data processing unit (180) switches to an immediate output mode (S51). In the immediate output mode, each measurement value is output in real time without averaging, allowing for rapid tracking of concentration changes.

[0080] In the immediate output mode, the data processing unit (180) determines whether the concentration change has stabilized (S60). For example, if the fluctuation rate is maintained below a standard for three consecutive times or more, it is determined that it has stabilized.

[0081] When the change in concentration stabilizes (S60: Yes), the data processing unit (180) returns to the average processing mode (S61). This allows measurement stability to be restored while simultaneously removing noise.

[0082] If the change in concentration has not stabilized (S60: No), the data processing unit (180) immediately maintains the output mode (S62). This allows for the output of real-time measurements while the concentration continues to change, thereby maintaining fast responsiveness.

[0083] When the change in concentration stabilizes (S60: Yes), switch back to the average processing mode (S20).

[0084] Through this adaptive measurement algorithm, stability is ensured by processing average values ​​under normal conditions, and a fast response speed can be provided by immediately outputting actual measured values ​​in the event of rapid concentration changes, such as gas leaks. Actual test results confirmed that the maximum value can be captured within 10 seconds when the gas concentration changes rapidly.

[0085] Referring to FIG. 4, the circuit configuration will be described. FIG. 4 is a circuit diagram showing the circuit configuration according to the present embodiment.

[0086] The battery unit (195) includes a lithium-ion battery (DC 12V, 10200mAh) and can operate continuously for about 30 hours when fully charged. The battery unit (195) supplies an appropriate voltage to each component through a step-down converter.

[0087] The power supply is separated into digital power, analog power, and lamp power, minimizing noise interference between each circuit.

[0088] The data processing unit (180) receives a digital signal output from the signal processing circuit (154) of the NDIR sensor unit (150) and converts it into a gas concentration. The data processing unit (180) includes a microcontroller unit and performs an adaptive measurement algorithm.

[0089] The communication unit (198) is configured to selectively use at least one of UART, RS485 Modbus, or 4 to 20 mA analog output. For example, when using RS485 Modbus, it operates with Function Code 3, Initial Address 0x0050 (changeable), and 2-Wire Modbus RTU Mode.

[0090] FIG. 4 schematically illustrates the electrical connection relationships between the power supply unit, the signal processing circuit of the NDIR sensor unit, the data processing unit, and the communication unit, and the detailed circuit configuration is within a range that can be easily implemented by a person skilled in the art.

[0091] The first display unit (191) is composed of an LCD screen and displays the measured gas concentration. The display format is a constant with 3 digits and 1 decimal place (e.g., 999.9 ppm) or a constant with 4 digits (e.g., 1234 ppm).

[0092] The second display unit (192) is composed of an LCD screen and displays the remaining battery level, current output voltage, and charging status. The second display unit (192) monitors the battery voltage in real time and indicates that charging is required when the voltage drops below a preset value (e.g., 10.5V).

[0093] Referring to FIG. 5, the appearance of the gas analysis device (100) will be described. FIG. 5 is a photograph showing the appearance of the gas analysis device.

[0094] A first display unit (191) is positioned on the upper front of the housing (110), and a second display unit (192) is positioned on the lower side thereof. The first display unit (191) displays a concentration value such as "CF4" or the type of gas being measured and "0.0 ppm". The second display unit (192) displays information such as a battery level bar graph and "12V 100%".

[0095] An external pretreatment filter unit (120) is protruded and positioned on the side of the housing (110). The internal filling material (123) can be visually inspected through the transparent container (121) of the external pretreatment filter unit (120). A handle (111) is formed on the upper part of the housing (110), and a gas inlet (112) is located therein. A gas outlet (113) is located on the bottom surface of the housing (110), and an external flow meter unit (170) is extended and positioned to the side.

[0096] Looking at the internal configuration, an external pre-treatment filter unit (120), an internal dust filter unit (130), an internal moisture filter unit (140), an NDIR sensor unit (150), a pump unit (160), a battery unit (195), and a circuit board are arranged inside the housing (110). The external pre-treatment filter unit (120) is a transparent cylindrical container, so the white filling inside can be seen. The internal dust filter unit (130) and the internal moisture filter unit (140) are arranged in the form of small filter cartridges in front of the NDIR sensor unit (150). The NDIR sensor unit (150) is characterized by a gold-colored optical waveguide, and a pump unit (160) is arranged behind it.

[0097] To explain the gas inflow and outflow path, the gas to be measured flows in through the inlet (112) and enters the upper inlet (124) of the external pretreatment filter unit (120). The gas passes through the filling material (123) inside the external pretreatment filter unit (120) and descends, after which it is discharged through the side outlet (126).

[0098] The gas that passes through the external pretreatment filter section (120) moves to the internal dust filter section (130) through a tube. The gas that passes through the internal dust filter section (130) moves to the internal moisture filter section (140).

[0099] The gas that passes through the built-in moisture filter section (140) flows into the optical waveguide (152) of the NDIR sensor section (150). Inside the optical waveguide (152), the gas absorbs infrared rays, and the concentration is measured.

[0100] The gas passing through the NDIR sensor unit (150) moves to the pump unit (160). The pump unit (160) sucks in the gas and transfers it to the external flow meter unit (170). The gas passing through the external flow meter unit (170) is finally discharged through the outlet (113).

[0101] Through this gas flow path, the gas is sequentially pretreated and introduced into the sensor, discharged by a pump after measurement, and an optimized structure is implemented to finally verify the flow rate.

[0102] The method for measuring gas using the gas analysis device (100) of the present embodiment is as follows.

[0103] First, the user turns on the gas analyzer (100) by pressing the rocker switch (S100).

[0104] When the gas analyzer (100) is turned on, an initialization process is performed (S110). During the initialization process, the battery status is checked, the sensor is warmed up (e.g., 10 to 20 minutes), and zero point calibration is performed.

[0105] When initialization is complete, the gas analyzer (100) enters a measurement standby state (S120).

[0106] The user connects a tube to the gas inlet (112) to introduce the gas to be measured (S130). For example, the tube can be connected to the outlet of a semiconductor scrubber.

[0107] The gas to be measured is introduced through the inlet (112) and enters the external pretreatment filter section (120) (S140). In the external pretreatment filter section (120), some of the moisture and corrosive gases contained in the gas are removed by the filler (123).

[0108] The gas that passes through the external pretreatment filter unit (120) moves to the internal dust filter unit (130) to remove fine particles (S150).

[0109] The gas that passes through the internal dust filter section (130) moves to the internal moisture filter section (140) to further remove residual moisture (S160).

[0110] The gas that has passed through the internal moisture filter section (140) flows into the NDIR sensor section (150) (S170). In the NDIR sensor section (150), the gas absorbs infrared rays as it passes through the optical waveguide (152), and the photodetector (153) detects the transmitted infrared rays and converts them into an electrical signal.

[0111] The signal processing circuit (154) amplifies and filters the electrical signal output from the photodetector (153) and converts it into a digital signal (S180).

[0112] The data processing unit (180) receives a digital signal and converts it into a gas concentration (S190). In this process, a correction function based on the Beer-Lambert law is used.

[0113] The data processing unit (180) applies an adaptive measurement algorithm (S200). As previously explained with reference to FIG. 3, a moving average is calculated to ensure stability in normal circumstances, and when a sudden change in concentration is detected, the actual value is output immediately.

[0114] The data processing unit (180) displays the final concentration on the first display unit (191) (S210). For example, it is displayed as "CF4125.3 ppm".

[0115] At the same time, the data processing unit (180) can transmit concentration data to an external device through the communication unit (198) (S220). For example, data can be transmitted to a semiconductor process control system via RS485 Modbus communication.

[0116] The gas passing through the NDIR sensor unit (150) is sucked in by the pump unit (160) and transferred to the external flow meter unit (170) (S230).

[0117] The external flow meter (170) displays the flow rate of the gas (S240). The user visually checks the external flow meter (170) to see if the flow rate is within the normal range (e.g., 0.8 to 1.2 L / min).

[0118] If the flow rate is within the normal range (S250: Yes), it is determined that the measurement is proceeding normally.

[0119] If the flow rate is outside the normal range (S250: No), the user recognizes that filter replacement or equipment inspection is required (S260).

[0120] The gas that passes through the external flow meter (170) is finally discharged through the outlet (113) (S270).

[0121] Through the above process, the gas analysis device (100) of the present embodiment can accurately measure low-concentration gas, extend pump life, simultaneously satisfy measurement stability and response speed, and verify normal operation in real time.

[0122] The results of evaluating the performance by applying the gas analysis device (100) of this embodiment to CF4 gas measurement are as follows.

[0123] Measurement range: 0.5~50ppm (In the case of this embodiment, it can be manufactured with other measurement ranges)

[0124] Accuracy: ±3% FS (0–40% range), ±5% FS (41–100% range)

[0125] Response time: T63 ≤ 25 seconds, T90 ≤ 40 seconds (Recommended flow rate 500~2000cc / min)

[0126] Resolution: 0.5 ppm

[0127] Minimum detection limit: 0.3 ppm (Test report from an accredited institution available)

[0128] ZERO Repeatability: 0.5ppm (@25℃, 0ppm)

[0129] SPAN Repeatability: ±2.0ppm (@25℃, 100ppm)

[0130] Long-term stability: ZERO DRIFT 1% FS / month (@25℃, after zero calibration)

[0131] Stabilization time: 10 seconds (based on initial output), 20 minutes (based on accuracy)

[0132] Output period: 2-second intervals

[0133] Lifespan: 4 years (based on clean air)

[0134] As a result of the above performance evaluation, it was confirmed that the gas analysis device (100) of the present embodiment sufficiently satisfies the low-concentration gas measurement performance required in a semiconductor process scrubber.

[0135] <실시예 2>

[0136] This embodiment is mostly the same as Example 1, but is characterized by using silica gel as the filling material (123) of the external pretreatment filter part (120).

[0137] Silica gel has excellent moisture adsorption capabilities, making it effective in high-humidity environments. However, since its lifespan may be somewhat shorter than that of activated alumina, it is advisable to set a short replacement cycle.

[0138] Other configurations and operations are the same as in Example 1, so a detailed description is omitted.

[0139] <실시예 3>

[0140] This embodiment is mostly the same as Example 1, but is characterized by using a mixture of activated alumina and silica gel as the filler (123) of the external pretreatment filter part (120).

[0141] When using a mixture of activated alumina and silica gel, the advantages of both materials can be utilized. For example, silica gel can be placed at the top to primarily adsorb moisture, and activated alumina can be placed at the bottom to further remove residual moisture and corrosive gases.

[0142] Other configurations and operations are the same as in Example 1, so a detailed description is omitted.

[0143] <실시예 4>

[0144] This embodiment is mostly the same as Example 1, but is characterized by replacing the sensor module of the NDIR sensor unit (150) with one for measuring N2O gas.

[0145] Since N2O gas absorbs infrared light in the wavelength range of about 4.5 μm, a sensor module equipped with a light source and an optical filter suitable for this is used. The replacement of the sensor module can be performed by a simple operation of opening the housing (110) and detaching the connector.

[0146] Other configurations and operations are the same as in Example 1, so a detailed description is omitted.

[0147] <실시예 5>

[0148] This embodiment is mostly the same as Embodiment 1, but is characterized by being linked with a semiconductor process control system using RS485 Modbus communication through a communication unit (198).

[0149] When using RS485 Modbus communication, measured gas concentration data can be requested and received using Function Code 3. The Initial Address is 0x0050 and can be changed as needed. The communication method is 2-Wire Modbus RTU Mode.

[0150] The semiconductor process control system can receive gas concentration data in real time from the gas analysis device (100) of the present embodiment to monitor the processing efficiency of the scrubber or generate a gas leak alarm.

[0151] Other configurations and operations are the same as in Example 1, so a detailed description is omitted.

[0152] <실시예 6>

[0153] This embodiment is mostly the same as Embodiment 1, but is characterized by using a 4-20mA analog output through the communication unit (198).

[0154] When using a 4~20mA analog output, the gas concentration is converted into a current value and output. For example, if the measurement range is 0~50ppm, 4mA is output at 0ppm and 20mA is output at 50ppm.

[0155] Analog output is widely used in industrial settings because it is easy to integrate with PLCs (Programmable Logic Controllers) or DCSs (Distributed Control Systems).

[0156] Other configurations and operations are the same as in Example 1, so a detailed description is omitted.

[0157] <변형예>

[0158] The technical concept of the present invention is not limited to the embodiments described above, and various modifications are possible.

[0159] For example, in addition to activated alumina and silica gel, zeolite, activated carbon, or a combination thereof can be used as the filler (123) of the external pretreatment filter section (120).

[0160] The pump unit (160) may use a piston pump, a rotary vane pump, or other pumps suitable for gas transfer in addition to a diaphragm pump.

[0161] In the adaptive measurement algorithm of the data processing unit (180), the variation rate standard can be adjusted to ±0.5%, ±2.0%, etc., in addition to ±1.0% according to the user's requirements.

[0162] The NDIR sensor unit (150) can use a single beam method or other NDIR sensor structures in addition to the dual beam method.

[0163] The battery unit (195) may use a lithium polymer battery, a nickel-hydrogen battery, or other rechargeable batteries in addition to a lithium-ion battery.

[0164] The communication unit (198) can use various wired or wireless communication methods such as CAN communication, Ethernet, Wi-Fi, and Bluetooth in addition to UART, RS485 Modbus, and 4-20mA analog output.

[0165] As described above, the gas analysis device and measurement method of the present invention provide excellent effects that allow for accurate measurement of low-concentration gases through an optimized gas flow arrangement structure and an adaptive measurement algorithm, while also extending pump life and verifying normal operation in real time.

[0166] Although preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention as defined in the following claims also fall within the scope of the present invention. Explanation of the symbols

[0167] 100: Gas analyzer 110: Housing 111: Handle 112: Gas inlet 113: Gas outlet 120: External pretreatment filter unit 121: Transparent container 122: Central Hall 123: Filling 124: Upper entrance 125: Side space 126: Side Exit 130: Built-in dust filter 140: Built-in moisture filter 150: NDIR sensor section 151: Infrared light source 152: Optical waveguide 153: Photodetector 154: Signal Processing Circuit 160: Pump section 170: External flow meter unit 180: Data processing unit 191: First display unit 192: Second display unit 195: Battery section 198: Communications Department

Claims

Claim 1 A housing including an inlet into which a gas to be measured flows; an external pretreatment filter unit that primarily pretreats the gas flowing in from the inlet; an internal dust filter unit that removes dust from the gas passing through the external pretreatment filter unit; an internal moisture filter unit that further removes moisture from the gas passing through the internal dust filter unit; an NDIR sensor unit that measures the concentration of the gas passing through the internal moisture filter unit; a pump unit that sucks in the gas passing through the NDIR sensor unit and transports it to an outlet; an external flow meter unit positioned downstream of the pump unit that displays the flow rate of the discharged gas so that a user can visually confirm it, thereby enabling detection of abnormalities in the external pretreatment filter unit, the internal dust filter unit, the internal moisture filter unit, or the pump unit; a data processing unit that processes a signal output from the NDIR sensor unit to calculate the gas concentration; and a battery unit that supplies power to each component of the gas analysis device.The external pretreatment filter unit comprises a transparent container, a central hole formed vertically penetrating the center of the container, a filling space formed on the outer side of the central hole through which gas passes, and activated alumina filled in the filling space to adsorb corrosive gases and moisture, wherein gas flows into the upper part of the container, passes through the filling space, and is discharged from the lower part, and the user can visually check the condition of the internal filling through the transparent container, the internal moisture filter unit is composed of a desiccant filter and forms a double moisture removal structure together with the activated alumina of the external pretreatment filter unit, the NDIR sensor unit is formed as a replaceable module structure depending on the type of gas to be measured, and the pump unit is located between the NDIR sensor unit and the discharge port, arranged so that the incoming gas flows into the pump unit after passing through the external pretreatment filter unit, the internal dust filter unit, and the internal moisture filter unit, thereby preventing corrosion of the diaphragm or valve of the pump unit by corrosive gases and extending the lifespan of the pump unit, and the data processing unit A portable non-dispersive infrared gas analyzer for measuring low-concentration gases, characterized by performing an adaptive measurement algorithm that calculates and outputs a moving average of the measured values, but stops the average processing and immediately outputs the new measured value when it is detected that the new measured value changes by more than a preset rate of change compared to the previous measured value, wherein the preset rate of change is ±1.0%, and the battery unit is configured such that the gas analyzer can operate portablely without an external power source. Claim 2 delete Claim 3 delete Claim 4 delete Claim 5 A method for measuring low-concentration gas using a gas analysis device of claim 1, characterized by comprising: a step of first pre-treating an incoming gas in an external pre-treatment filter unit; a step of removing dust in an internal dust filter unit; a step of removing moisture in an internal moisture filter unit; a step of measuring the gas concentration in an NDIR sensor unit; a step of sucking in and discharging the gas after it passes through the sensor in a pump unit; and a step of measuring the discharge gas flow rate in an external flow meter unit to determine whether it is operating normally. Claim 6 A method for measuring low-concentration gas according to claim 5, wherein the step of measuring the gas concentration comprises: a step of obtaining a measurement value from an NDIR sensor unit; a step of calculating a moving average of the measurement value; a step of calculating a rate of change by comparing a new measurement value with a previous measurement value; a step of outputting the moving average as the final concentration when the rate of change is ±1.0% or less; and a step of immediately outputting the new measurement value as the final concentration when the rate of change exceeds ±1.0%.

Images