Ammonia escape detection device based on TDLAS (tunable diode laser absorption spectroscopy)

Abstract

The utility model relates to an ammonia escape detection device based on TDLAS (Tunable Diode Laser Absorption Spectroscopy), which comprises a laser transmitting and receiving unit, an analyzer and an in-situ sampling probe connected with the laser transmitting and receiving unit, the in-situ sampling probe comprises a first connecting pipe, a second connecting pipe, a first sampling pipe, a mounting gas chamber and a second sampling pipe which are connected in sequence, one end of the first connecting pipe is communicated with an irradiation opening of the laser transmitting and receiving unit, one end of the second connecting pipe extends into the flue, and sealing glass is arranged in one end of the second connecting pipe; a plurality of sample inlets are formed in the outer wall of the second sampling tube; one end, far away from the second sampling tube, of the first sampling tube is communicated with a sample outlet; a filtering assembly and a reflecting assembly are sequentially arranged in the mounting gas chamber in the flowing direction of the sampled gas. The device has the advantages of being convenient to install, accurate in measurement and the like.

Description

Technical Field

[0001] The utility model relates to an ammonia detection device, in particular to an ammonia escape detection device based on TDLAS, belonging to the technical field of smoke detection. Background Art

[0002] With the application of denitrification technology in thermal power plants, flue gas denitrification mostly adopts the SCR process selective catalytic reduction method. In a reactor equipped with a catalyst, the flue gas and the injected ammonia undergo a reduction reaction under the action of the catalyst to generate harmless N2 and H2O, achieving the purpose of removing nitrogen oxides. However, since the amount of ammonia sprayed cannot be accurately controlled, the unreacted ammonia will have a greater impact on the air preheater and other post-furnace equipment. In order to ensure the normal operation of downstream equipment, the limit value of ammonia escape is below 3ppm. Monitoring the ammonia content in flue gas requires ammonia escape detection equipment. At present, the most reliable and accurate ammonia escape detection equipment on the market is the laser ammonia escape detection equipment.

[0003] The basic principle of ammonia escape detection equipment currently used in the market is basically based on LasIR gas analyzers based on TDLAS (tunable diode laser absorption spectroscopy, abbreviated as: laser method) technology, which usually adopts extraction and penetration methods; 1. Extraction detection is to use a sampling pipeline to extract flue gas from the flue and then enter the analysis instrument for analysis, but this method will make the sampling pipeline too long, the thermal insulation of the sampling pipeline cannot be guaranteed, and the adsorption of ammonia by the sampling pipeline and the smoke inside it will cause inaccurate measurement results; 2. Penetration detection is to set a laser transmitting end and a laser receiving end on both sides of the flue, and the laser passes through the measured gas in the flue for analysis and measurement. In the actual operation process, due to external interference factors such as vibration and thermal expansion, the position of the laser transmitting end and the laser receiving end may be offset, so that the light is not on the same axis, resulting in inaccurate measurement of the ammonia escape rate. In addition, the influence of impurities such as smoke in the flue gas will also affect the accuracy of the measurement.

[0004] Therefore, it is necessary to design an ammonia escape detection device based on TDLAS with accurate measurement. Utility Model Content

[0005] The utility model mainly aims at the above-mentioned problems existing in the prior art and provides an ammonia escape detection device based on TDLAS.

[0006] The purpose of this utility model is mainly achieved through the following solutions:

[0007] The ammonia escape detection device based on TDLAS comprises a laser emitting and receiving unit and an analyzer electrically connected to the laser emitting and receiving unit, and the detection device also comprises an in-situ sampling probe connected to the laser emitting and receiving unit; the in-situ sampling probe comprises a first connecting tube, a second connecting tube, a first sampling tube, an installation air chamber and a second sampling tube connected in sequence, one end of the first connecting tube is connected to the irradiation port of the laser emitting and receiving unit, one end of the second connecting tube extends into the flue, and a sealing glass is arranged inside the end of the second connecting tube close to the first sampling tube; a plurality of sampling ports are arranged on the outer wall of the second sampling tube, and a sampling port is connected to the end of the first sampling tube away from the second sampling tube; a filter assembly and a reflection assembly are arranged in sequence in the installation air chamber along the flow direction of the sampled gas, and the laser emitted from the emitting end of the laser emitting and receiving unit enters the receiving end of the laser emitting and receiving unit after being reflected by the reflection assembly.

[0008] Preferably, one end of the first connecting pipe connected to the second connecting pipe is detachably fixedly connected to the outer wall of the flue through a connecting flange on its outer wall.

[0009] Preferably, the sealing glass is a plane lens made of high temperature resistant glass, and the sealing glass can block the sampling gas in the first sampling tube.

[0010] Preferably, a sampling pump is installed on the outer wall of the second sampling tube, the air inlet of the sampling pump is connected to the first sampling tube, and the air outlet of the sampling pump is connected to the sample outlet.

[0011] Preferably, the filter assembly adopts a sintered filter element and can be detachably installed in the installation air chamber.

[0012] Preferably, the reflective component is a total reflection prism and is made of high temperature resistant glass.

[0013] Preferably, a plurality of the laser emitting and receiving units and the in-situ sampling probes are provided along the length direction of the flue.

[0014] Therefore, compared with the prior art, the utility model has the following advantages:

[0015] (1) The utility model integrates the laser transmitting and receiving unit and the in-situ sampling probe into an integrated structure, which not only facilitates the installation and disassembly of the entire device, but also overcomes the problem of light rays not being on the same axis due to external interference factors such as vibration and thermal expansion, thereby ensuring the stability and reliability of the ammonia escape rate measurement;

[0016] (2) The utility model can isolate the sampling gas in the first sampling tube by providing a sealing glass, thereby ensuring that the laser can pass through smoothly and preventing the impact and corrosion of the smoke on the laser transmitting and receiving unit, thereby increasing the service life of the device;

[0017] (3) The utility model can filter out impurities such as smoke and dust by setting a filter component. On the one hand, it can prevent impurities such as smoke and dust from blocking the optical path of the laser, and on the other hand, it can prevent impurities such as smoke and dust from accumulating on the surface of the reflective component and the sealing glass, thereby ensuring the smooth flow of the laser optical path, and thus accurately measuring the ammonia escape rate in the flue;

[0018] (4) The utility model realizes ammonia concentration monitoring at multiple points by installing multiple groups of laser transmitting and receiving units and in-situ sampling probes on the flue, and can accurately measure the distribution of ammonia escape and the ammonia escape rate in the flue. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of the utility model;

[0020] Figure 2 It is an installation schematic diagram of the utility model.

[0021] Illustration: 1-laser transmitting and receiving unit, 2-analyzer, 3-first connecting tube, 4-second connecting tube, 5-first sampling tube, 6-installation gas chamber, 7-second sampling tube, 8-irradiation port, 9-sealing glass, 10-inlet, 11-outlet, 12-filtering assembly, 13-reflecting assembly, 14-transmitting end, 15-receiving end, 16-connecting flange, 17-sampling pump, 18-flue. DETAILED DESCRIPTION

[0022] The technical solution of the utility model is further described in detail below through specific embodiments and in combination with the accompanying drawings. It should be understood that the implementation of the utility model is not limited to the following embodiments, and any form of modification and / or change made to the utility model will fall within the protection scope of the utility model.

[0023] In the present invention, unless otherwise specified, all parts and percentages are weight units, and the equipment and raw materials used can be purchased from the market or are commonly used in the field. The methods in the following embodiments, unless otherwise specified, are conventional methods in the field. The components or equipment in the following embodiments, unless otherwise specified, are universal standard parts or components known to those skilled in the art, and their structures and principles are known to those skilled in the art through technical manuals or conventional experimental methods.

[0024] Embodiment 1:

[0025] like Figure 1As shown, the utility model provides a technical solution, an ammonia escape detection device based on TDLAS, including a laser emitting and receiving unit 1 and an analyzer 2 electrically connected to the laser emitting and receiving unit 1. The analyzer 2 adopts an instrument of the prior art, such as the Laslr ammonia laser gas analyzer produced by Suzhou Qiandu Analytical Instrument Co., Ltd.

[0026] The detection device also includes an in-situ sampling probe connected to the laser emitting and receiving unit 1; the emitting end 14 and the receiving end 15 of the laser emitting and receiving unit 1 are integrated in a shell, and the in-situ sampling probe is composed of a first connecting tube 3, a second connecting tube 4, a first sampling tube 5, an installation air chamber 6 and a second sampling tube 7 connected in sequence, the first connecting tube 3, the second connecting tube 4, the first sampling tube 5, the installation air chamber 6 and the second sampling tube 7 are coaxially arranged, one end of the first connecting tube 3 is connected to the irradiation port 8 of the laser emitting and receiving unit 1 (shell), one end of the second connecting tube 4 extends into the flue 18 and is sealed and connected to the inner wall of the flue 18, and a sealing glass 9 is installed inside the end of the second connecting tube 4 close to the first sampling tube 5; a plurality of sampling ports 10 are evenly opened on the outer wall of the second sampling tube 7, and a sampling port 11 is connected to the end of the first sampling tube 5 away from the second sampling tube 7. The sampled gas enters from the sampling port 10 and exits from the sampling port 11; a filter assembly 12 and a reflective assembly 13 are sequentially arranged in the installation chamber 6 along the flow direction of the sampled gas; the laser emitted from the transmitting end 14 of the laser emitting and receiving unit 1 is reflected by the reflective assembly 13 and enters the receiving end 15 of the laser emitting and receiving unit 1; the filter assembly 12 can filter impurities such as smoke dust in the flue gas; the filtered sampled gas enters the left side of the installation chamber 6 and the first sampling tube 5 (measurement cavity), and enters the flue 18 through the sampling port 11 after the measurement is completed; during the measurement process, the laser emitted from the transmitting end 14 of the laser emitting and receiving unit enters the measurement cavity, is absorbed by the gas, reaches the reflective assembly 13 at the front end of the measurement cavity to realize reflection, is absorbed by the gas again, reaches the laser receiving end 15 in the laser emitting and receiving unit to realize photoelectric detection, and is finally transmitted to the analyzer to realize concentration analysis.

[0027] Embodiment 2:

[0028] like Figure 1 As shown, the utility model provides another technical solution, an ammonia escape detection device based on TDLAS, which is different from Example 1 in that one end of the first connecting pipe 3 connected to the second connecting pipe 4 is detachably fixedly connected to the outer wall of the flue 18 through the connecting flange 16 of the outer wall, which facilitates the installation and disassembly of the entire detection device.

[0029] Embodiment 3:

[0030] like Figure 1As shown, the utility model provides another technical solution, an ammonia escape detection device based on TDLAS, which is different from Example 1 in that the sealing glass 9 is a flat lens made of high-temperature resistant glass. The sealing glass 9 can block the sampling gas in the first sampling tube 5. While ensuring that the laser can pass through smoothly, it can also avoid the impact and corrosion of the smoke on the laser transmitting and receiving unit, thereby improving the service life of the device.

[0031] Embodiment 4:

[0032] like Figure 1 As shown, the utility model provides another technical solution, an ammonia escape detection device based on TDLAS, which is different from Example 1 in that a sampling pump 17 is fixedly installed on the outer wall of the second sampling tube 7 by bolts, and the air inlet of the sampling pump 17 is connected to the first sampling tube 5, and the air outlet of the sampling pump 17 is connected to the sample outlet 11. Through the setting of the sampling pump 17, a negative pressure can be formed inside the measuring cavity, thereby facilitating the inhalation of the flue gas in the flue 18 into the measuring cavity.

[0033] Embodiment 5:

[0034] like Figure 1 As shown, the utility model provides another technical solution, an ammonia escape detection device based on TDLAS, which is different from Example 1 in that the filter component 12 adopts a sintered filter element and can be detachably installed in the installation air chamber 6. The sintered filter element is a multi-layer metal sintered mesh, which adopts multi-layer stainless steel mesh through special lamination and pressing to ensure the reliability of filtration.

[0035] Embodiment 6:

[0036] like Figure 1 As shown, the utility model provides another technical solution, an ammonia escape detection device based on TDLAS, which is different from Example 1 in that the reflection component 13 is a total reflection prism made of high temperature resistant glass, and its end face is an isosceles right triangle.

[0037] Embodiment 7:

[0038] like Figure 1 , 2 As shown, the utility model provides another technical solution, an ammonia escape detection device based on TDLAS, which is different from Example 1 in that a plurality of laser transmitting and receiving units 1 and in-situ sampling probes are evenly arranged along the length direction of the flue 18 to realize ammonia concentration monitoring at multiple points in the flue.

[0039] The ammonia escape detection device based on TDLAS provided by the utility model integrates the laser emitting and receiving unit and the in-situ sampling probe into an integrated structure, which not only facilitates the installation and disassembly of the entire device, but also overcomes the problem that the light is not on the same axis due to external interference factors such as vibration and thermal expansion, thereby ensuring the stability and reliability of the ammonia escape rate measurement; the sampling gas can be blocked in the first sampling tube by the provided sealing glass, and while ensuring that the laser can pass smoothly, the impact and corrosion of the laser emitting and receiving unit caused by the flue gas can be avoided, thereby improving the service life of the device; impurities such as smoke can be filtered out by the provided filtering component, which can prevent the impurities such as smoke from blocking the optical path of the laser on the one hand, and prevent the impurities such as smoke from accumulating on the surface of the reflecting component and the sealing glass on the other hand, thereby ensuring the smoothness of the laser optical path, and then accurately measuring the ammonia escape rate in the flue; ammonia concentration monitoring at multiple points is realized by multiple groups of laser emitting and receiving units and in-situ sampling probes provided on the flue, and the distribution of ammonia escape in the flue and the ammonia escape rate can be accurately measured.

[0040] It should be understood that this embodiment is only used to illustrate the present invention and is not used to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. An ammonia escape detection device based on TDLAS, comprising a laser emitting and receiving unit (1) and an analyzer (2) electrically connected to the laser emitting and receiving unit (1), characterized in that: The detection device further comprises an in-situ sampling probe connected to the laser emitting and receiving unit (1); the in-situ sampling probe comprises a first connecting tube (3), a second connecting tube (4), a first sampling tube (5), an installation air chamber (6) and a second sampling tube (7) which are connected in sequence; one end of the first connecting tube (3) is connected to an irradiation port (8) of the laser emitting and receiving unit (1); one end of the second connecting tube (4) extends into a flue (18); and a sealing glass (9) is provided inside an end of the second connecting tube (4) close to the first sampling tube (5); a plurality of sampling ports (10) are provided on an outer wall of the second sampling tube (7); an end of the first sampling tube (5) away from the second sampling tube (7) is connected to a sampling port (11); a filter assembly (12) and a reflection assembly (13) are sequentially provided in the installation air chamber (6) along a flow direction of the sampled gas; laser light emitted from a transmitting end (14) of the laser emitting and receiving unit (1) enters a receiving end (15) of the laser emitting and receiving unit (1) after being reflected by the reflection assembly (13).

2. The ammonia escape detection device based on TDLAS according to claim 1, characterized in that: One end of the first connecting pipe (3) connected to the second connecting pipe (4) is detachably fixedly connected to the outer wall of the flue (18) via a connecting flange (16) on its outer wall.

3. The ammonia escape detection device based on TDLAS according to claim 1, characterized in that: The sealing glass (9) is a plane lens and is made of high temperature resistant glass. The sealing glass (9) can block the sampled gas in the first sampling tube (5).

4. The ammonia escape detection device based on TDLAS according to claim 1, characterized in that: A sampling pump (17) is installed on the outer wall of the second sampling tube (7); an air inlet of the sampling pump (17) is connected to the first sampling tube (5); and an air outlet of the sampling pump (17) is connected to the sample outlet (11).

5. The ammonia escape detection device based on TDLAS according to claim 1, characterized in that: The filter assembly (12) adopts a sintered filter element and can be detachably installed in the installation air chamber (6).

6. The ammonia escape detection device based on TDLAS according to claim 1, characterized in that: The reflection component (13) is a total reflection prism and is made of high temperature resistant glass.

7. The ammonia escape detection device based on TDLAS according to claim 1, characterized in that: The laser emitting and receiving units (1) and the in-situ sampling probes are provided in plurality along the length direction of the flue (18).

Images