In-situ humidity measuring device based on laser absorption principle

Abstract

The utility model belongs to the field of environment monitoring, and discloses an in-situ humidity measuring device based on a laser absorption principle, which comprises a main machine shell, a probe rod, a laser emitting part, a laser receiving part, an optical fiber circulator and a detection air chamber, the laser emitting part and the laser receiving part are arranged on the main machine shell, one end of the probe rod is connected with the main machine shell, and the other end of the probe rod is connected with the optical fiber circulator. One end of the probe rod is provided with the detection gas chamber, the probe rod is covered with the probe filter outside the detection gas chamber, the optical fiber circulator is arranged in an inner cavity of the probe rod, the laser emission part is connected with a first port of the optical fiber circulator, and the detection gas chamber is connected with a second port of the optical fiber circulator. And the laser receiving part is connected with a third port of the optical fiber circulator. The device can be used for measuring the humidity of gas in an industrial flue with the characteristic of high dust content.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the field of environmental monitoring, concretely is a kind of in-situ humidity measuring device based on laser absorption principle. BACKGROUND

[0002] Humidity is a common gas associated with combustion process in industrial process, and is also an important parameter for industrial process optimization, process flow control and product quality assurance. The measuring instruments of traditional electrolytic method, resistance-capacitance method and cold mirror method are well applied in traditional conventional environment, but industrial process has the characteristics of high dust, so that the instruments of traditional method have certain gap with actual industrial application demand in measurement precision, service life and adaptability, and it is difficult to meet the online continuous detection of trace water in complex environment of industrial process. SUMMARY

[0003] The utility model discloses in order to solve the defect and insufficient of above-mentioned prior art, provide a kind of in-situ humidity measuring device based on laser absorption principle, the utility model can be used in the humidity measurement of gas in industrial flue with the characteristics of high dust.

[0004] To achieve the above object, the technical scheme adopted by the utility model is as follows:

[0005] An in-situ humidity measuring device based on laser absorption principle, comprising a host shell, a probe rod, a laser emitting part, a laser receiving part, an optical fiber circulator and a detection gas chamber, the laser emitting part and the laser receiving part are arranged in the host shell, one end of the probe rod is connected with the host shell, the detection gas chamber is arranged at one end of the probe rod, a probe filter is arranged outside the detection gas chamber on the probe rod, the optical fiber circulator is arranged in the inner cavity of the probe rod, the laser emitting part is connected with the first port of the optical fiber circulator, the detection gas chamber is connected with the second port of the optical fiber circulator, and the laser receiving part is connected with the third port of the optical fiber circulator.

[0006] Preferably, one end of the probe rod away from the detection gas chamber is sealed, and the end is provided with a probe backflush pipe interface, and the probe backflush pipe interface is communicated with the inner cavity of the probe rod.

[0007] Preferably, a probe backflush control electromagnetic valve is arranged on the host shell, and the probe backflush control electromagnetic valve is connected with the probe backflush pipe interface.

[0008] Preferably, the probe filter is in the shape of a cylindrical body with no bottom at one end, the bottomless end of the probe filter is connected with the probe rod, and the detection gas chamber is located in the probe filter as a whole.

[0009] Preferably, a constant-temperature heating module for heating the detection gas chamber is arranged in the probe filter.

[0010] Preferably, the filtering accuracy of the probe filter is below 2 μm.

[0011] Preferably, the probe rod is externally coaxially connected with a mounting flange.

[0012] Preferably, the laser emitting part comprises a laser, a laser wavelength tuning and temperature control module, the laser wavelength tuning and temperature control module is used for heating the laser and controlling the output wavelength of the laser, and a tail fiber of the laser is connected with the first port of the fiber ring through a fiber coupler.

[0013] Preferably, the laser receiving part comprises a signal acquisition and data processing module, a photoelectric coupler and a photoelectric detector, the photoelectric detector is connected with the third port of the fiber ring through an electric coupler, and the signal acquisition and data processing module is connected with the photoelectric detector.

[0014] Preferably, the detection gas chamber is a reflective fiber coupling gas chamber.

[0015] The utility model has the following beneficial effects:

[0016] In the utility model, the laser emitting part can emit laser of preset wavelength, the laser intensity is absorbed by water vapor in the detection gas chamber, resulting in the change of light intensity emission; the laser receiving part can receive the reflected light signal of the detection gas chamber and convert the light signal into electric signal, and the electric signal is processed and the humidity is calculated. In the utility model, the fiber ring is used to realize the signal connection of the laser emitting part, the laser receiving part and the detection gas chamber. The probe rod of the utility model is externally covered with a probe filter at the detection gas chamber, when the dust concentration of the measured gas is high, the measured gas passes through the probe filter and enters the detection gas chamber, the dust of the measured gas is filtered by the probe filter and is intercepted on the filter, the gas entering the detection gas chamber is relatively clean, and the pollution of the gas chamber is reduced. It can be seen that the utility model can be used for the humidity measurement of the gas in the industrial flue with high dust. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical scheme in the embodiment of the utility model, the drawings needed to be used in the embodiment description will be briefly introduced, obviously, the drawings in the following description are only some embodiments of the utility model, and other drawings can be obtained according to these drawings without paying creative labor for the ordinary skilled in the art.

[0018] Figure 1 It is the use state diagram of the in-situ humidity measurement device based on the laser absorption principle in the embodiment of the utility model.

[0019] In the figure: 1, main machine shell, 2, probe rod, 3, probe filter, 4, laser, 5, laser wavelength tuning and temperature control module, 6, fiber coupler, 7, fiber circulator, 8, detection gas chamber, 9, constant temperature heating module, 10, photoelectric coupler, 11, photoelectric detector, 12, signal acquisition and data processing module, 13, probe back flushing control electromagnetic valve, 14, probe back flushing pipe interface, 15, mounting flange, 16, industrial gas pipeline. DETAILED DESCRIPTION

[0020] To make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model will be clearly and completely described below in combination with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, rather than all the embodiments. The components of the embodiments of the utility model shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the utility model provided in the drawings is not intended to limit the scope of the claimed utility model, but only represents selected embodiments of the utility model. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the utility model.

[0021] REFERENCE Figure 1 The in-situ humidity measuring device based on the laser absorption principle comprises a main machine shell 1, a probe rod 2, a laser emitting part, a laser receiving part, a fiber circulator 7 and a detection gas chamber 8. The laser emitting part and the laser receiving part are arranged in the main machine shell 1. One end of the probe rod 2 is connected to the main machine shell 1. The detection gas chamber 8 is arranged at one end of the probe rod 2. A probe filter 3 is arranged outside the detection gas chamber 8 on the probe rod 2. The fiber circulator 7 is arranged in the inner cavity of the probe rod 2. The laser emitting part is connected to the first port of the fiber circulator 7. The detection gas chamber 8 is connected to the second port of the fiber circulator 7. The laser receiving part is connected to the third port of the fiber circulator 7. In use, the probe rod 2 is inserted into the industrial gas pipeline 16, so that the detection gas chamber 8 is located in the industrial gas pipeline 16. When the gas in the industrial gas pipeline 16 flows through the detection gas chamber 8, the dust in the gas is filtered out by the probe filter 3. The gas and the moisture therein pass through the probe filter 3 and enter the detection gas chamber 8. The laser emitting part emits laser of a preset wavelength. The laser emitted by the laser emitting part enters the detection gas chamber 8 through the first port and the second port of the fiber circulator 7. The laser intensity entering the detection gas chamber 8 is absorbed by the water vapor in the detection gas chamber, resulting in a change in the light intensity emission. Then the laser enters the laser receiving part through the second port and the third port of the fiber circulator 7. The laser receiving part converts the light intensity signal into a current or voltage signal, and processes the current or voltage signal and calculates the humidity.

[0022] As the preferred embodiment of the utility model, in the embodiment, one end of the probe rod 2 away from the detection gas chamber 8 is sealed, and the end is provided with a probe backflush pipe interface 14, and the probe backflush pipe interface 14 is communicated with the inner cavity of the probe rod 2. The probe backflush pipe interface 14 can backflush the probe filter 3, and the filtering effect of the probe filter 3 is ensured.

[0023] As the preferred embodiment of the utility model, in the embodiment, the main machine shell 1 is provided with a probe backflush control electromagnetic valve 13, and the probe backflush control electromagnetic valve 13 is connected with the probe backflush pipe interface 14. In the embodiment, the probe backflush control electromagnetic valve 13 can be used to control the backflush of the probe filter 3.

[0024] As the preferred embodiment of the utility model, in the embodiment, the probe filter 3 can adopt the following structure: the shape of the probe filter 3 is a cylindrical shape with one end without bottom, filter holes are arranged in the bottom and the side wall of the probe filter 3, the end without bottom of the probe filter 3 is connected with the probe rod 2, and the detection gas chamber 8 is located in the probe filter 3 as a whole.

[0025] As the preferred embodiment of the utility model, in the embodiment, the probe filter 3 is provided with a constant-temperature heating module 9 for heating the detection gas chamber 8. The constant-temperature heating module can be used to control the temperature of the detection gas chamber, and the system needs to be preheated before measurement, and the measurement is started after the set temperature is reached, so that the influence of the temperature change of the measured gas on the detection gas chamber is excluded, and the temperature adaptability of the device is improved. When the laser principle is used for humidity measurement, the measured is the gaseous humidity, and when the gas contains liquid water, the measurement result is affected. The heating module can also vaporize water to prevent liquid water from polluting the gas chamber and affecting the measurement result.

[0026] As the preferred embodiment of the utility model, in the embodiment, the filtering precision of the probe filter 3 is below 2 μm. The main functions are as follows: 1. The high-precision filter can remove the solid particles and liquid in the flue gas, prevent these impurities from entering the optical gas chamber, and thus protect the equipment in the optical gas chamber from pollution and damage; 2. By filtering the impurities in the flue gas, the purity of the gas entering the optical gas chamber is ensured, the measurement error is reduced, and the measurement precision is improved.

[0027] As the preferred embodiment of the utility model, in the embodiment, the probe rod 2 is coaxially connected with a mounting flange plate 15 outside. The mounting flange plate 15 is used to facilitate the fixed installation of the utility model and the industrial gas pipeline 16.

[0028] As the preferred embodiment of the utility model, in the embodiment, the laser emitting part can adopt the following structure: specifically comprising a laser 4, a laser wavelength tuning and temperature control module 5, the laser wavelength tuning and temperature control module 5 is connected with the laser 4, the laser wavelength tuning and temperature control module 5 is used to control the working temperature of the laser 4 and control the output wavelength of the laser 4, so that the output wavelength of the laser is located at the central wavelength of the absorption spectrum line of the measured gas, the pigtail of the laser 4 is connected with the first port of the optical fiber circulator 7 through the optical fiber coupler 6.

[0029] As the preferred embodiment of the utility model, in the embodiment, the laser receiving part can adopt the following structure: specifically comprising a signal acquisition and data processing module 12, an optoelectronic coupler 10 and a photodetector 11, the photodetector 11 is connected with the third port of the optical fiber circulator 7 through the electric coupler 10, and the signal acquisition and data processing module 12 is connected with the photodetector 11.

[0030] Embodiment

[0031] The embodiment is an in-situ humidity measuring device based on the laser absorption principle, which is mainly composed of a host part and a probe rod part. The host part includes a host shell 1, and the inside is mainly provided with a laser emitting part and a laser receiving part. The laser emitting part includes a laser 4, a laser wavelength tuning and temperature control module 5 and an optical fiber coupler 6. The laser receiving part includes an optoelectronic coupler 10, a photodetector 11 and a signal acquisition and data processing module 12. A probe backblowing control electromagnetic valve 13 is also arranged. A probe filter 3, a detection gas chamber 10, a constant temperature heating module 9, a probe backblowing pipe interface 14 and a mounting flange 15 are arranged on the equipment probe rod 2. The laser 4 is installed on the laser wavelength tuning and temperature control module 5, and the output wavelength of the laser output light source can be controlled in real time. The laser emitted is connected with the first port of the optical fiber circulator 7 through the optical fiber coupler 6, and then connected to the detection gas chamber 8 through the second port of the optical fiber circulator 7. The detection gas chamber 8 can be controlled at constant temperature through the constant temperature heating module 9. The laser light intensity is absorbed by water vapor in the detection gas chamber, causing the light intensity emission to change. The third connecting end of the optical fiber circulator 7 is connected with the optoelectronic coupler 10, and the photodetector 11 is installed on the optoelectronic coupler, converting the light intensity signal into current or voltage mode, which is transmitted to the signal acquisition and data processing module 12 through the wire for signal processing and humidity calculation. The probe backblowing electromagnetic valve 13 is connected to the probe backblowing pipe interface 14 through the air pipe, and the filter of the probe is backblown through the electromagnetic valve control. The whole equipment is directly installed on the gas pipeline through the mounting flange 15 for in-situ measurement. The detection gas chamber (8) adopts a reflective optical fiber coupling gas chamber.

[0032] Specifically, the device is directly installed on a gas pipeline by a flange during measurement for in-situ measurement. During measurement, the temperature of the laser is set to 37.35 DEG C by a laser wavelength tuning and temperature control module, the working current is set to 60-80mA, the wavelength scanning range of the laser is controlled by a tuning current so that the wavelength of the laser scans the absorption peak of the water molecules, and in the present scheme, the wavelength is 1392nm. After photoelectric amplification by a laser wavelength receiving module, a laser wavelength absorption curve is formed.

[0033] The optical path structure in the device is that the light emitted by the laser is connected with the first port of the optical fiber coupler and the optical fiber circulator, then enters the detection gas chamber through the second port of the optical fiber circulator, is reflected by the reflecting mirror of the detection gas chamber, is connected with the photoelectric coupler through the third port of the optical fiber circulator, and the photoelectric detector is installed on the photoelectric coupler to convert the light intensity signal into a current or voltage signal and transmit the signal to the signal acquisition and data processing module through a wire for signal processing and humidity calculation.

[0034] The detection gas chamber adopts a non-contact measurement design, no chemical reaction occurs between the laser and the gas during testing, the detection gas chamber end and the electrical control end are connected through an optical fiber, no electricity, radiation or electromagnetic interference exists in the detection gas chamber end, and the detection gas chamber is safe. Protective films are coated on the optical elements of the gas chamber, and the gas chamber has good transmittance, corrosion resistance and wiping resistance.

[0035] The system needs to be preheated before measurement, the preheating time is generally 30min, the set temperature of the detection gas chamber constant temperature heating module is set to 350 DEG C, the temperature control accuracy is ±1 DEG C, and measurement is started after the set temperature is reached. In order to reduce random errors and improve the signal-to-noise ratio, all the measured data are averaged for 20 times.

[0036] When the dust concentration in the measured gas is high, the dust in the measured gas is filtered by the probe filter when the measured gas enters the detection gas chamber, the dust is intercepted on the filter, the gas entering the detection gas chamber is relatively clean, the pollution of the gas chamber is reduced, and after a period of use, the dust intercepted on the probe filter becomes more and more thick, which may cause the filter to be blocked, so that the measured gas cannot enter the detection gas chamber. The control panel controls the opening of the probe back-blowing electromagnetic valve, dry and clean compressed air is connected to the probe back-blowing pipe interface through a gas pipe, the back-blowing gas enters the probe rod to blow off the dust attached to the filter. During back-blowing, the pressure of the back-blowing gas is 0.3-0.5MPa, a pulse back-blowing mode is adopted, and the back-blowing time is greater than 30s.

[0037] In conclusion, the device is based on the laser absorption principle, is single-ended and installed in-situ, is convenient to maintain, has high measurement accuracy, and has strong environmental adaptability.

[0038] The device has the advantages that:

[0039] 1. The non-contact laser absorption measurement method is adopted. The reflective fiber-coupled gas chamber in this device is designed to be high temperature resistant and corrosion resistant, which greatly improves the environmental adaptability of the device.

[0040] 2. This design uses a fiber optic circulator for the optical path. Light can only be emitted from the laser, pass through the fiber optic circulator, enter the detector chamber, and finally be absorbed by the detector. The light propagates in one direction along the optical path, thus enabling bidirectional optical signal transmission on a single fiber. It has high isolation and low insertion loss, reducing the amount of fiber used while improving signal accuracy.

[0041] 3. Since parameters in gas absorption spectra, such as line intensity, linewidth, and molecular density number, are temperature-dependent and change with temperature variations, this device incorporates a constant-temperature heating module at the probe to control the temperature of the detection chamber. The system requires preheating before measurement to reach the set temperature, thus eliminating the influence of temperature changes on the detection chamber and improving the device's temperature adaptability. When using laser technology for humidity measurement, the measured humidity is in the gaseous state. The presence of liquid water in the gas can affect the measurement results. The heating module also vaporizes the water, preventing liquid water from contaminating the chamber and affecting the measurement results.

[0042] 4. The probe filter at the front end of the probe can filter dust in high-dust gas environments, preventing dust from entering the gas chamber and contaminating the chamber, thus affecting the measurement results. Simultaneously, the device controls the probe backflushing solenoid valve, allowing the probe to be periodically backflushed with dry compressed air using a rod, preventing dust from clogging the probe filter during prolonged use and ensuring the measured gas can enter the gas chamber for measurement.

[0043] Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of this utility model.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of this utility model and not to limit it. Although the utility model has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of this utility model. Any modifications or equivalent substitutions that do not depart from the spirit and scope of this utility model should be covered within the protection scope of the claims of this utility model.

Claims

1. A device for in-situ humidity measurement based on the principle of laser absorption, characterized in that, The application relates to a laser gas detector, which comprises a main machine shell (1), a probe rod (2), a laser emitting part, a laser receiving part, a fiber optic circulator (7) and a detection gas chamber (8), wherein the laser emitting part and the laser receiving part are arranged in the main machine shell (1), one end of the probe rod (2) is connected with the main machine shell (1), the detection gas chamber (8) is arranged at one end of the probe rod (2), a probe filter (3) is arranged on the probe rod (2) outside the detection gas chamber (8), the fiber optic circulator (7) is arranged in the inner cavity of the probe rod (2), the laser emitting part is connected with the first port of the fiber optic circulator (7), the detection gas chamber (8) is connected with the second port of the fiber optic circulator (7), and the laser receiving part is connected with the third port of the fiber optic circulator (7).

2. The in-situ humidity measuring device based on the laser absorption principle according to claim 1, characterized in that, One end of the probe rod (2) far away from the detection gas chamber (8) is sealed, and the end is provided with a probe back-blowing pipe interface (14) which is communicated with the inner cavity of the probe rod (2).

3. The in-situ humidity measuring device based on the laser absorption principle according to claim 2, characterized in that, A probe back-blowing control electromagnetic valve (13) is arranged on the main machine shell (1) and connected with the probe back-blowing pipe interface (14).

4. The in-situ humidity measuring device based on laser absorption principle according to any one of claims 1-3, characterized in that, The probe filter (3) is in the shape of a bottomless cylinder, the bottomless end of the probe filter (3) is connected with the probe rod (2), and the detection gas chamber (8) is located in the probe filter (3) as a whole.

5. The in-situ moisture measurement device based on laser absorption principle according to any one of claims 1-3, characterized in that, A constant-temperature heating module (9) for heating the detection gas chamber (8) is arranged in the probe filter (3).

6. The in-situ moisture measurement device based on laser absorption principle according to any one of claims 1-3, characterized in that, The filtering precision of the probe filter (3) is below 2 microns.

7. The in-situ humidity measurement device based on laser absorption principle according to claim 1, characterized in that, An installation flange (15) is coaxially connected outside the probe rod (2).

8. The in-situ humidity measuring device based on laser absorption principle according to claim 1, characterized in that, The laser emitting part comprises a laser (4) and a laser wavelength tuning and temperature control module (5), the laser wavelength tuning and temperature control module (5) is connected with the laser (4), the laser wavelength tuning and temperature control module (5) is used for heating the laser (4) and controlling the output wavelength of the laser (4), and the tail fiber of the laser (4) is connected with the first port of the fiber optic circulator (7) through a fiber coupler (6).

9. The in-situ humidity measurement device based on laser absorption principle according to claim 1, characterized in that, The laser receiving part comprises a signal acquisition and data processing module (12), a photoelectric coupler (10) and a photoelectric detector (11), the photoelectric detector (11) is connected with the third port of the fiber optic circulator (7) through the photoelectric coupler (10), and the signal acquisition and data processing module (12) is connected with the photoelectric detector (11).

10. The in-situ humidity measuring device based on laser absorption principle according to claim 1, characterized in that, The detection gas chamber (8) is a reflective fiber coupling gas chamber.

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