CN220419159U - On-line monitoring gas analyzer - Google Patents

Abstract

The utility model relates to the field of gas monitoring equipment, in particular to an online monitoring gas analyzer. The laser reflection device comprises a base, an upper cover, a laser emission component, a laser receiving component and a laser reflection component, wherein a pipe fitting is arranged in a space formed by encircling the base and the upper cover, the pipe fitting is provided with an air inlet and an air outlet, and the pipe fitting comprises an emission end, a receiving end and a reflection end; the laser transmitting assembly is arranged towards the transmitting end, the laser receiving assembly is arranged towards the receiving end, the laser reflecting assembly is arranged towards the reflecting end, and the laser reflecting assembly receives laser emitted by the laser transmitting assembly and reflects the laser to the laser receiving assembly; the base and/or the upper cover are/is provided with heating plates. The utility model provides the optical air chamber which has stable structure, deformation resistance, difficult pollution, easy debugging, longer optical path, higher resolution, no interference from background gas, good response of specific laser wavelength and convenient maintenance.

Description

On-line monitoring gas analyzer

Technical Field

The utility model relates to the field of gas monitoring equipment, in particular to an online monitoring gas analyzer.

Background

In industrial fields such as coal-fired power plants, aluminum plants, steel plants, smelting plants, garbage power plants, cement plants, chemical plants, glass plants, etc., pollution of harmful gases (e.g., NH3, HCl, HF, CO, CO2, etc.) generated during combustion is becoming an increasing problem. The gases have great harm to human health, and excessive inhalation of ammonia can cause the too high concentration of ammonia in blood, thereby triggering trigeminal reflex, causing cardiac arrest and respiratory arrest and threatening life. Long-term contact with low concentration hydrogen chloride can cause dry skin and color change, and can also cause symptoms such as cough, headache, insomnia, dyspnea, palpitation, and gastralgia. High concentration of hydrogen fluoride inhalation can irritate the mucous membranes of the eyes and respiratory tract, and in severe cases bronchitis, pulmonary oedema and even asphyxia can occur. Carbon monoxide can cause hypoxia, which when combined with hemoglobin reduces the amount of oxygenated hemoglobin in plasma, affecting oxygen transport, leading to hypoxia and hypoxia. The low concentration carbon dioxide stimulates the respiratory center, and the high concentration has anesthetic effect on the central nervous system, can inhibit respiration, and causes a series of central nervous system poisoning symptoms. These gases also cause serious environmental pollution, such as hydrogen fluoride has strong toxicity to plants, and can be damaged by exposure to high fluorine air for several weeks, and short exposure can cause acute injury, impeding photosynthesis and respiratory function. In order to protect the health of the human body and prevent environmental pollution, industry is actively conducting continuous on-line monitoring of these harmful gases.

Currently, tunable semiconductor laser absorption spectroscopy (TDLAS) is widely used in the detection of stationary source gases. The basic principle of the technology is that the tested gas passes through a gas chamber, the laser beam with specific wavelength passes through the gas in the gas chamber, and the concentration of the tested gas is determined by analyzing the attenuation information of the laser intensity according to the proportional relation between the attenuation degree of the laser intensity and the concentration of the gas. The tunable laser spectrum absorption technology is a novel detection technology which has high sensitivity and high resolution and can monitor gas on line in real time. The core component is a distributed feedback laser, the output wavelength is changed by adjusting the current of the laser, the laser wavelength is enabled to sweep the absorption peak of the gas to be detected, and then the signal of the absorption peak and the signal of the non-absorption peak of the gas to be detected are compared through a second harmonic detection method, so that the concentration of the gas to be detected is reversely pushed. The method has high resolution.

However, when the measured gas is introduced into the gas chamber, due to the presence of water gas in the test environment, they may interact with the measured gas, affecting the accuracy of the measurement result; moreover, because the interference of the water vapor cannot be controlled and eliminated, errors or deviations can be caused; in addition, the existence of moisture can cause light path attenuation, optical element pollution or absorption change, so that the measurement result is inconsistent or fluctuates greatly.

Disclosure of Invention

The utility model mainly aims at the problems and provides an online monitoring gas analyzer, which aims at solving the problems of reducing the influence of water vapor on the measurement of the measured gas and improving the accuracy and stability of the measurement result.

In order to achieve the above purpose, the utility model provides an on-line monitoring gas analyzer, which comprises a base, an upper cover, a laser emitting assembly, a laser receiving assembly and a laser reflecting assembly, wherein a pipe fitting is arranged in a space formed by encircling the base and the upper cover, the pipe fitting is provided with an air inlet and an air outlet, and the pipe fitting comprises an emitting end, a receiving end and a reflecting end; the laser transmitting assembly is arranged towards the transmitting end, the laser receiving assembly is arranged towards the receiving end, the laser reflecting assembly is arranged towards the reflecting end, and the laser reflecting assembly receives laser emitted by the laser transmitting assembly and reflects the laser to the laser receiving assembly; the base and/or the upper cover are/is provided with heating plates.

Further, the base and/or the upper cover are/is further provided with a cover plate for covering the heating plate.

Further, the pipe fitting is an M-shaped air chamber steel pipe, is formed by welding 4 steel pipes, is made of stainless steel, and is plated with fluorine on the inner layer.

Further, the pipe fitting is provided with five windows, each window is provided with a window sheet, the five window sheets and the pipe fitting are enclosed to form a cavity, and the window sheets are a combination body formed by a plane lens, a heat insulation sheet and a plane lens base; the plane lens is fixed on one side of the plane lens base through an adhesive, the heat insulation sheet is arranged on the other side of the plane lens base, the window sheets are respectively fixed on five positions at two ends of the M-shaped air chamber steel pipe through screws, and an O-shaped sealing ring is arranged between the window sheets and the M-shaped air chamber steel pipe.

Further, the laser emission subassembly includes first convex lens, lens holder, laser instrument base, laser instrument circuit board, first fixed plate and first regulating block, first regulating block passes through the dish spring and installs on first fixed plate, threaded hole has been seted up on the first fixed plate, the threaded hole is provided with first adjust knob, first adjust knob wear out the threaded hole support hold in first regulating block, the laser instrument circuit board sets up on the laser instrument base, the laser instrument sets up on the laser instrument circuit board, the laser instrument base mount is in on the first regulating block, be provided with the lens holder on the laser instrument base, be provided with first convex lens on the lens holder.

Further, the laser receiving assembly comprises a photocell plate, a photocell base and a second convex lens, wherein the photocell plate and the second convex lens are arranged on the photocell base.

Further, the laser reflection assembly comprises a second fixed plate, a second adjusting block and a reflecting mirror, wherein the second adjusting block is installed on the second fixed plate through a disc spring, a threaded hole is formed in the second fixed plate, a second adjusting knob is arranged in the threaded hole, the second adjusting knob penetrates out of the threaded hole to be propped against the second adjusting block, and the reflecting mirror is arranged on the second adjusting block.

Further, a heat dissipation cavity is arranged in the laser base and corresponds to the lamination position of the laser circuit board, the heat dissipation cavity extends from the laser base to the outside to form an air inlet end and an air outlet end, and the air inlet end and the air outlet end are provided with air nozzles.

Further, the laser receiving device also comprises a transmitting end light shield, a reflecting end light shield and a receiving end light shield, wherein the transmitting end light shield is arranged on the laser transmitting assembly, the reflecting end light shield is arranged on the laser reflecting assembly, and the receiving end light shield is arranged on the laser receiving assembly.

Further, the device also comprises a filter and a jet pump, wherein an air pipe is arranged between the filter and the air inlet, and an air pipe is arranged between the jet pump and the air outlet.

The technical scheme of the utility model has the following advantages: the instrument comprises a base, an upper cover, a laser emitting assembly, a laser receiving assembly and a laser reflecting assembly. A closed space is formed between the base and the upper cover, wherein a pipe fitting is arranged, the pipe fitting is provided with an air inlet and an air outlet, and the pipe fitting comprises a transmitting end, a receiving end and a reflecting end. In the instrument, the laser emitting assembly is disposed toward the emitting end, the laser receiving assembly is disposed toward the receiving end, and the laser reflecting assembly is disposed toward the reflecting end. The laser transmitting assembly transmits laser to the transmitting end, and the laser is reflected by the laser reflecting assembly and transmitted to the laser receiving assembly. Thus, when the tested gas enters the pipe fitting from the gas inlet, the gas analysis is performed through the transmission and reflection processes of the laser. In addition, the base and/or the upper cover are/is also provided with a heating plate. Through the effect of heating plate, the gas in the pipe fitting can heat up to target temperature to reduce the influence of aqueous vapor to the gas measurement that is surveyed, improve measuring accuracy.

Drawings

FIG. 1 is a schematic diagram of an explosion structure of an on-line monitoring gas analyzer according to the present utility model.

FIG. 2 is a schematic view of an M-type air chamber according to the present utility model.

FIG. 3 is a schematic view of a light ray direction according to the present utility model.

Fig. 4 is a schematic perspective view of a laser emitting assembly according to the present utility model.

Fig. 5 is a schematic diagram of an exploded view of a laser emitting assembly according to the present utility model.

Fig. 6 is a schematic perspective view of a laser reflection assembly according to the present utility model.

Fig. 7 is a schematic diagram of an exploded view of a laser reflector assembly according to the present utility model.

Fig. 8 is a schematic perspective view of a laser receiving assembly according to the present utility model.

Fig. 9 is a schematic diagram of an exploded view of a laser receiving assembly according to the present utility model.

In the figure: 1. a base; 2. an upper cover; 3. a laser emitting assembly; 4. a laser receiving assembly; 5. a laser reflection assembly; 6. a pipe fitting; 7. a heating sheet; 8. a cover plate; 9. a planar lens; 10. a heat insulating sheet; 11. a planar lens base; 12. an O-shaped sealing ring; 13. an air tap; 14. a transmitting end light shield; 15. a reflective end mask; 16. a receiving end hood; 17. a filter; 18. a jet pump; 301. a first convex lens; 302. a lens holder; 303. a laser base; 304. a laser; 305. a laser circuit board; 306. a first fixing plate; 307. a first adjustment block; 308. a first adjustment knob; 401. a photovoltaic panel; 402. a photocell base; 403. a second convex lens; 501. a second fixing plate; 502. a second adjustment block; 503. a reflecting mirror; 504. a second adjustment knob; 601. an air inlet; 602. an air outlet; 603. a transmitting end; 604. a receiving end; 605. and a reflective end.

Detailed Description

The following describes in further detail the embodiments of the present utility model with reference to the drawings and examples. The following examples are illustrative of the utility model and are not intended to limit the scope of the utility model.

In the description of the present utility model, it should be understood that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present utility model and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present utility model. Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present utility model, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present utility model will be understood in specific cases by those of ordinary skill in the art.

The utility model relates to an on-line monitoring gas analyzer, as shown in fig. 1-9. The instrument includes: the device comprises a base 1, an upper cover 2, a laser emitting assembly 3, a laser receiving assembly 4 and a laser reflecting assembly 5; a pipe fitting 6 is arranged in a space formed by the base 1 and the upper cover 2 in a surrounding way, and the pipe fitting 6 is provided with an air inlet 601 and an air outlet 602; the tube member 6 includes an emitting end 603, a receiving end 604, and a reflecting end 605; the laser emission subassembly 3 sets up towards transmitting end 603, and the laser receiving subassembly 4 sets up towards receiving end 604, and the laser reflection subassembly 5 sets up towards reflecting end 605, and the laser reflection subassembly 5 receives the laser that comes from the transmission of laser emission subassembly 3 and reflects the laser to the laser receiving subassembly 4, and base 1 and/or upper cover 2 are provided with heating plate 7, and the aqueous vapor in pipe fitting 6 is got rid of in the heating of accessible heating plate 7, avoids causing the influence to the measured gas measurement.

In order to further improve the heating efficiency, a plurality of groups of heating plates 7 can be arranged, each group is composed of two plates, one plate is arranged on the upper cover 2, the other plate is arranged under the base 1, the upper cover 2 and the base 1 are made of materials with high heat conductivity, such as aluminum alloy, the heating plates 7 enable air chambers in the pipe fitting 6 to be heated, the heating temperature is up to 180 ℃, and through the use of the heating plates 7, the influence of water and air on the measurement of the measured air is reduced, and the measurement accuracy is improved. It should be noted that the protection scope of the present utility model is not limited to 180 degrees heating temperature and the materials of the upper cover 2 and the base 1 are aluminum alloys.

Preferably, the base 1 and/or the upper cover 2 are further provided with a cover plate 8 which encloses the heating plate 7.

Preferably, the pipe fitting 6 is a 6 inch M-shaped air chamber steel pipe formed by welding 4 pipes, is made of stainless steel, and is covered with a fluorine-plated layer on the inner layer. The design effectively protects the inner layer of the air chamber from being corroded by the gas, reduces the adsorption of the detected gas, and can well protect the inner layer of the air chamber from being damaged when cleaning pollutants.

The M-shaped air chamber steel pipe is formed by welding 4 steel pipes, and the included angle between every two steel pipes can be adjusted according to requirements. The design can ensure that laser light emitted by the laser is focused through the convex lens and propagates along the first steel pipe, and the laser light is just hit at the center of the first reflecting mirror. Then the reflection of the first reflecting mirror propagates in the second steel pipe, and the reflection is precisely hit at the center of the second reflecting mirror again. The propagation mode is continued in turn until the last steel tube, and then the steel tube is focused by a convex lens and is precisely hit at the center of the photocell. The design enables light to completely propagate in a preset direction, so that the accuracy of measurement is improved.

In some embodiments, the length of 1 steel pipe is 700mm, light is repeatedly turned back in the M-shaped air chamber, the total optical path length can reach 2800mm-3000mm, the detection offline can be effectively reduced, the detection resolution is improved, and the method is particularly suitable for measuring low-concentration gas.

In some embodiments, a near infrared tunable laser is used to emit a single line spectrum of wavelengths absorbed only by the gas under test, avoiding background gas cross interference. The accuracy and the resolution of measurement are greatly improved by matching with a tunable semiconductor laser absorption spectrum technology and a multi-turn-back air chamber, and the detection lower limit can be below 0.1 ppm.

In some embodiments, the air inlet 601 and the air outlet 602 are disposed at the same end position of the first and fourth steel pipes, respectively. The air outlet 602 and the air inlet 601 are connected with the M-shaped air chamber steel pipe by adopting a straight-through cutting sleeve and a sealing adhesive tape.

Preferably, as shown in fig. 2, the pipe fitting 6 has five windows, each window is provided with a window sheet, the five window sheets and the pipe fitting 6 enclose a cavity, and the window sheets are a combination formed by a plane lens 9, a heat insulation sheet 10 and a plane lens base 11; the plane lens 9 is fixed on one side of the plane lens base 11 through an adhesive, the heat insulation sheet 10 is arranged on the other side of the plane lens base 11, the window sheets are respectively fixed on five positions at two ends of the M-shaped air chamber steel pipe through screws, and an O-shaped sealing ring 12 is arranged between the window sheets and the M-shaped air chamber steel pipe.

Preferably, the air inlet 601 and the air outlet 602 are arranged at the position far away from the plane lens 9, so that the pollution of air to the lens is effectively reduced, the power of the adopted laser is more than 10mw, the service life of the laser is more than 3 years, and the service life of the instrument is prolonged.

Preferably, the planar lens 9 is adopted, the coating layer is arranged on the inner side, the coating layer can be effectively protected from being corroded by gas, and the coating can be well protected from being damaged when pollutants are cleaned.

As shown in fig. 4 and 5, the laser emitting assembly 3 includes a first convex lens 301, a lens holder 302, a laser base 303, a laser 304, a laser circuit board 305, a first fixing plate 306 and a first adjusting block 307, the first adjusting block 307 is mounted on the first fixing plate 306 through a disc spring, a threaded hole is formed in the first fixing plate 306, a first adjusting knob 308 is disposed in the threaded hole, the first adjusting knob 308 penetrates through the threaded hole to abut against the first adjusting block 307, the laser circuit board 305 is disposed on the laser base 303, the laser 304 is disposed on the laser circuit board 305, the laser base 303 is mounted on the first adjusting block 307, the lens holder 302 is disposed on the laser base 303, and the first convex lens 301 is disposed on the lens holder 302.

As shown in fig. 8 and 9, the laser receiving assembly 4 includes a photocell plate 401, a photocell base 402, and a second convex lens 403, and the photocell plate 401 and the second convex lens 403 are mounted on the photocell base 402.

As shown in fig. 6 and 7, the laser reflection assembly 5 includes a second fixing plate 501, a second adjusting block 502 and a reflecting mirror 503, the second adjusting block 502 is mounted on the second fixing plate 501 through a disc spring, a threaded hole is formed in the second fixing plate 501, a second adjusting knob 504 is disposed in the threaded hole, the second adjusting knob 504 penetrates out of the threaded hole to abut against the second adjusting block 502, and the reflecting mirror 503 is disposed on the second adjusting block 502.

In the above embodiment, the first adjusting block 307 and the second adjusting block 502 are designed to be adjustable, and the three-dimensional space positions of the laser 304 and the mirror 503 are adjusted by adopting the fine adjustment knob (i.e. the first adjusting knob 308 and the second adjusting knob 504) on the special process adjusting assembly to control the spot position, so that the spot position is just converged on the center position of the mirror 503 and the photocell plate 401, thereby improving the measurement accuracy.

In the above embodiment, two convex lenses (i.e., the first convex lens 301 and the second convex lens 403) are provided, one is fixed on the lens holder 302 by an adhesive and then fixed on the laser base 303 by a rotating screw, and is disposed right in front of the laser 304 to focus the incident light. The other is secured to the photocell base 402 by an adhesive to focus the reflected light.

As shown in fig. 5, a heat dissipation cavity is disposed in the laser base 303, the heat dissipation cavity is disposed corresponding to the bonding position of the laser circuit board 305, the heat dissipation cavity extends from the laser base 303 to the outside to form an air inlet end and an air outlet end, the air inlet end and the air outlet end are provided with air nozzles 13, compressed gas is purged to enter from the air inlet end, and the air outlet end flows out, so that the temperature of the laser emission component is reduced, the influence of high temperature on the laser wavelength is reduced, and the measurement accuracy is improved.

The preferred design also includes an emitter end shield 14, a reflector end shield 15, and a receiver end shield 16. The transmitting end light shield 14 is installed on the laser transmitting assembly 3, the reflecting end light shield 15 is installed on the laser reflecting assembly 5, and the receiving end light shield 16 is installed on the laser receiving assembly 4. The existence of the light shields effectively protects the laser emitting component, the laser receiving component and the laser reflecting component from being wetted by rainwater, so that the light shields can adapt to rainy day environments.

The preferred design also includes a filter 17 and a jet pump 18. An air pipe is provided between the filter 17 and the air inlet 601, and an air pipe is also provided between the jet pump 18 and the air outlet 602.

The filter 17 is designed with high filtering accuracy and can effectively filter out dust particles with the size of 0.2 microns. The filter element is detachable, convenient to replace and clean, and the time required by maintenance and replacement is greatly shortened.

The jet pump 18 is made of stainless steel, and is powered by a compressed air source to pump the sampled air through an air chamber, so that the instrument can be ensured to stably run for a long time.

Preferably, no light treatment is carried out on the inner wall of the M-shaped air chamber, so that interference caused by stray light can be reduced, and measurement accuracy is improved.

Preferably, all machining parts are subjected to internal stress relieving treatment, so that the influence on the light propagation angle caused by internal deformation is avoided, and the stability is improved.

Preferably, the convex lens and the reflecting mirror are of an open type design, the M-shaped air chamber main body and the window sheet are of a separable design, and the plane lens, the reflecting mirror, the first convex lens, the second convex lens and the M-shaped air chamber main body can be cleaned and maintained rapidly and effectively, so that the workload of later maintenance is reduced.

The working process of the utility model is as follows:

the single line spectrum emitted by the laser 304 and only absorbed by the gas is focused by the first convex lens 301, propagates in the M-type gas chamber, is reflected for multiple times, and is focused by the second convex lens 403 to strike the photocell plate 401. In the process, the air tap 13 for laser heat dissipation cools the laser emission component 3 through blowing compressed gas, dust in the measured gas is filtered by the filter 17, and the compressed gas source enters the jet pump 18 to generate power to extract the measured gas and pass through the air chamber, so that the instrument can be ensured to stably run for a long time. The measured gas absorbs the laser beam to cause the laser intensity to be attenuated, the laser intensity attenuation is in direct proportion to the content of the measured gas, and the measured gas concentration can be obtained by measuring the laser intensity attenuation information.

The foregoing is merely a preferred embodiment of the present utility model, and it should be noted that it will be apparent to those skilled in the art that modifications and variations can be made without departing from the technical principles of the present utility model, and these modifications and variations should also be regarded as the scope of the utility model.

Claims (10)

1. The on-line monitoring gas analyzer is characterized by comprising a base, an upper cover, a laser emission component, a laser receiving component and a laser reflection component, wherein a pipe fitting is arranged in a space formed by encircling the base and the upper cover, the pipe fitting is provided with an air inlet and an air outlet, and the pipe fitting comprises an emission end, a receiving end and a reflection end; the laser transmitting assembly is arranged towards the transmitting end, the laser receiving assembly is arranged towards the receiving end, the laser reflecting assembly is arranged towards the reflecting end, and the laser reflecting assembly receives laser emitted by the laser transmitting assembly and reflects the laser to the laser receiving assembly; the base and/or the upper cover are/is provided with heating plates.

2. The on-line monitoring gas analyzer of claim 1, wherein the base and/or upper cover are further provided with a cover plate that encloses the heater chip.

3. The on-line monitoring gas analyzer of claim 1, wherein the tube is an M-cell steel tube, formed by welding 4 steel tubes, made of stainless steel, and having an inner layer of fluorine plating.

4. The on-line monitoring gas analyzer of claim 3, wherein the tube has five windows, each window is provided with a window sheet, five window sheets and the tube enclose a chamber, and the window sheets are a combination formed by a planar lens, a heat insulating sheet and a planar lens base; the plane lens is fixed on one side of the plane lens base through an adhesive, the heat insulation sheet is arranged on the other side of the plane lens base, the window sheets are respectively fixed on five positions at two ends of the M-shaped air chamber steel pipe through screws, and an O-shaped sealing ring is arranged between the window sheets and the M-shaped air chamber steel pipe.

5. The on-line monitoring gas analyzer of claim 1, wherein the laser emission assembly comprises a first convex lens, a lens holder, a laser base, a laser circuit board, a first fixing plate and a first adjusting block, wherein the first adjusting block is mounted on the first fixing plate through a disc spring, a threaded hole is formed in the first fixing plate, the threaded hole is provided with a first adjusting knob, the first adjusting knob penetrates through the threaded hole to abut against the first adjusting block, the laser circuit board is arranged on the laser base, the laser is arranged on the laser circuit board, the laser base is mounted on the first adjusting block, the laser base is provided with the lens holder, and the lens holder is provided with the first convex lens.

6. The on-line monitoring gas analyzer of claim 1, wherein the laser receiving assembly comprises a photocell plate, a photocell base, and a second convex lens, the photocell plate and the second convex lens being mounted on the photocell base.

7. The on-line monitoring gas analyzer of claim 1, wherein the laser reflection assembly comprises a second fixed plate, a second adjusting block and a reflecting mirror, the second adjusting block is mounted on the second fixed plate through a disc spring, a threaded hole is formed in the second fixed plate, a second adjusting knob is arranged in the threaded hole, the second adjusting knob penetrates out of the threaded hole to be abutted against the second adjusting block, and the reflecting mirror is arranged on the second adjusting block.

8. The on-line monitoring gas analyzer of claim 5, wherein a heat dissipation cavity is disposed in the laser base, the heat dissipation cavity is disposed corresponding to the bonding position of the laser circuit board, the heat dissipation cavity extends from the laser base to the outside to form an air inlet end and an air outlet end, and the air inlet end and the air outlet end are provided with air nozzles.

9. The on-line monitoring gas analyzer of claim 1, further comprising a transmitting end mask mounted on the laser transmitting assembly, a reflecting end mask mounted on the laser reflecting assembly, and a receiving end mask mounted on the laser receiving assembly.

10. The on-line monitoring gas analyzer of claim 1, further comprising a filter and a jet pump, wherein a gas tube is disposed between the filter and the gas inlet, and wherein a gas tube is disposed between the jet pump and the gas outlet.