Exhaust gas detection equipment and detection method

Abstract

The invention discloses exhaust gas detection equipment and a detection method. One end of a sampling pipe is connected with a discharge pipe to collect gas discharged by a flue, and standard gas is introduced into the sampling pipe for primary dilution; gas in the sampling pipe is introduced into the pretreatment high-temperature box for heating, and nitrogen is introduced for secondary dilution before heating; meanwhile, nitrogen is introduced into the pretreatment high-temperature box for three-stage dilution, the gas subjected to three-stage dilution is detected through an infrared spectrum analyzer, and the detected gas is conveyed into the flue again through a discharge pipe; and comprehensive gas is introduced into the discharge pipe for leakage-proof detection. The standard gas is used for carrying out primary dilution on the sampling gas, then the nitrogen is used for further carrying out secondary dilution and tertiary dilution on the sampling gas in two paths, the dilution ratio of the nitrogen is the product number of the secondary dilution and the tertiary dilution, and compared with traditional standard gas primary dilution and nitrogen secondary dilution, the nitrogen consumption is less, and the detection cost can be greatly reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of VOCs detection, and more specifically, to an exhaust gas detection device and a detection method. Background Art

[0002] Organic compounds that have high saturated vapor pressure, low boiling point, small molecular weight under standard conditions and are easily volatile at room temperature are one of the main pollutants in the atmosphere. Volatile organic compounds participate in the formation of ozone and secondary aerosols in the atmospheric environment, and have an important impact on regional atmospheric ozone pollution and PM2.5 pollution. This type of volatile organic compound has a special odor that is uncomfortable to people, and is toxic, irritating, teratogenic and carcinogenic. In particular, benzene, toluene and formaldehyde can cause great harm to human health. Volatile organic compounds are important precursors to urban haze and photochemical smog, and are mainly derived from coal chemical industry, petrochemical industry, fuel coating manufacturing, solvent manufacturing and use, and other processes.

[0003] With the strengthening of environmental awareness, enterprises will also carry out harmless treatment before the emission of volatile organic gases. In order to better deal with volatile organic waste gas, it will be detected online before and after emission using infrared spectrometer. However, the infrared spectrometer is limited in detecting the concentration of volatile organic gases, so it is necessary to introduce standard gas and nitrogen for dilution. In conventional operation, the nitrogen source has only one outlet connected to the sampling tube for collecting volatile organic waste gas, which consumes a large amount of nitrogen and has a high detection cost. Summary of the invention

[0004] The technical problem to be solved by the present invention is that in the traditional volatile organic waste gas detection process, the nitrogen consumption is large and the online detection cost is high, so a low-cost exhaust gas detection device and detection method are provided.

[0005] The technical solution adopted by the present invention to solve its technical problem is: An exhaust gas detection device includes a gas divider, a pretreatment high temperature box, an infrared spectrometer, a sampling tube and an exhaust pipe; One end of the sampling tube is connected to the smoke exhaust pipe, and the other end is connected in sequence to the first air inlet of the gas divider, the first air inlet of the pretreatment high temperature box, the air inlet of the infrared spectrometer, and then connected to the exhaust pipe, and the exhaust pipe is connected to the smoke exhaust pipe; The second air inlet and the third air inlet of the gas divider are connected to the standard gas source and the nitrogen source respectively, the second air outlet corresponding to the second air inlet on the gas divider is connected to the sampling tube, the third air outlet and the fourth air outlet corresponding to the third air inlet on the gas divider are connected, the third air outlet is connected to the sampling tube, and the fourth air outlet is connected to the pretreatment high temperature box.

[0006] Preferably: the gas divider is provided with a first air duct, a second air duct, a third air duct and a fourth air duct, the two ends of the first air duct correspond to the first air inlet and the first air outlet respectively, the sampling tube is connected from the first air inlet and connected from the first air outlet, and the first air duct, the third air duct and the fourth air duct are respectively installed with a first mass flow controller, a second mass flow controller and a third mass flow controller.

[0007] Preferably: the pretreatment high temperature box comprises a filter, an air pump and a gas mixing tank which are sequentially connected to the sampling tube, and the fourth gas outlet on the gas divider is connected to the gas path of the gas mixing tank.

[0008] Preferably: the pipeline connecting the sampling pipe between the pretreatment high temperature box and the infrared spectrometer is set as a heating pipeline.

[0009] Preferably: it also includes a heat exchanger pipe, one end of which is connected to a heat exchanger gas source, and the other end is connected to a discharge pipe.

[0010] Preferably: a fourth mass flow controller is installed on the display manifold.

[0011] Preferably, a bypass pipeline is also included, one end of which is connected to the heating pipeline, and the other end of which is connected to the discharge pipe.

[0012] Preferably: a float flowmeter is installed on the pipeline between the infrared spectrometer and the discharge pipe.

[0013] A method for detecting exhaust gas, Use sampling tubes to collect flue gas emissions and introduce standard gas to verify the accuracy of the detection equipment; The gas in the sampling tube is connected to a pre-treatment high temperature box for heating, and nitrogen is introduced for primary dilution before heating; At the same time, nitrogen is introduced into the pretreatment high temperature box for secondary dilution. The gas after secondary dilution is detected by infrared spectrometer. After the detection, the gas is re-transported to the flue through the exhaust pipe; The exhaust gas is introduced into the discharge pipe through the gas divider (2).

[0014] Preferably: the sampling gas coming out of the pretreatment high temperature box is divided into two paths, one path is passed into the infrared spectrometer for detection, and the sampling gas exceeding the detection amount of the infrared spectrometer flows directly into the exhaust pipe from the other path, and then is re-delivered to the flue by the exhaust pipe.

[0015] The beneficial effects of the present invention are as follows: after the standard gas enters the equipment, it circulates to verify the accuracy of the equipment, and then nitrogen is used in two ways to further perform primary dilution and secondary dilution on the sampled gas. The dilution multiple of the nitrogen is the product of the primary dilution and the secondary dilution. Compared with the traditional primary dilution, the amount of nitrogen used is less, and the detection cost can be greatly reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a flow chart for the detection of exhaust gas; Figure 2 A schematic diagram of the exhaust gas detection equipment; In the figure: 1. machine body; 2. gas divider; 3. pretreatment high temperature box; 31. filter; 32. air pump; 33. gas mixing tank; 4. infrared spectrometer; 5. sampling tube; 6. discharge pipe; 7. exhaust pipe; 8. heating pipeline; 9. display pipe; 10 bypass pipeline. DETAILED DESCRIPTION

[0017] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application may be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0018] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meanings as commonly understood by ordinary technicians in the technical field to which this application belongs.

[0019] In the present invention, unless otherwise specified, the directions used, such as "up" and "down", usually refer to the directions shown in the drawings, or to the vertical, perpendicular or gravity directions; similarly, for ease of understanding and description, "left" and "right" usually refer to the left and right shown in the drawings; "inside" and "outside" refer to the inside and outside relative to the outline of each component itself, but the above-mentioned directions are not used to limit the present invention.

[0020] according to Figure 1-2As shown, a detection device for exhaust gas includes a body 1 made of a metal frame and a gas divider 2, a pretreatment high temperature box 3, an infrared spectrometer 4, a sampling tube 5 and an exhaust pipe 6 installed on the body 1. The first air inlet of the gas divider 2, the first air inlet of the pretreatment high temperature box 3, and the air inlet of the infrared spectrometer 4 are connected through the sampling tube 5 to form an air path. The free part of one end of the sampling tube 5 is used to connect with the exhaust pipe 7, and the free part of the other end is connected with the exhaust pipe 6. One end of the exhaust pipe 6 is used to connect with the exhaust pipe 7, so that the sampled volatile organic gas forms a closed-loop air path. The second air inlet and the third air inlet on the gas divider 2 are connected to the standard gas source and the nitrogen source respectively. The second air outlet corresponding to the second air inlet on the gas divider 2 is connected to the sampling tube 5. The third air outlet and the fourth air outlet corresponding to the third air inlet on the gas divider 2 are connected. The third air outlet is connected to the sampling tube 5, and the fourth air outlet is connected to the pretreatment high temperature box 3.

[0021] After the standard gas enters the equipment, it circulates to verify the accuracy of the equipment. Nitrogen is then used in two ways to further dilute the sampled gas in the first and second stages. The dilution factor of nitrogen is the product of the first and second stages of dilution. Compared with traditional first-stage dilution, less nitrogen is used and the detection cost can be reduced a lot.

[0022] according to Figure 1-2 As shown, the gas divider 2 is provided with a first airway, a second airway, a third airway and a fourth airway, the two ends of the first airway correspond to the first air inlet and the first air outlet respectively, the sampling tube 5 is connected from the first air inlet and connected from the first air outlet, and the first airway, the third airway and the fourth airway are respectively installed with a first mass flow controller, a second mass flow controller and a third mass flow controller. The fourth mass flow controller is installed on the comprehensive pipe 9, one end of the comprehensive pipe 9 is connected to the comprehensive gas source, and the other end is connected to the discharge pipe 6. The comprehensive gas is used to detect whether the overall gas path is leaking online better and faster. If there is a leak in the gas path pipeline, the tracer gas concentration at the leak will be significantly higher than that in other parts, so that it can be quickly detected by the pipeline gas leak detector. The comprehensive gas in this application includes helium, nitrogen or argon, and helium is preferred.

[0023] according to Figure 1-2 As shown, valves for controlling the gas flow rate are provided at the front and rear ends of the first mass flow controller, the second mass flow controller, the third mass flow controller and the fourth mass flow controller. The pretreatment high temperature box 3 includes a box body and a filter 31, an air pump 32 and a gas mixing tank 33 installed in the box body. The filter 31 is connected to the first air outlet of the gas divider 2, the air pump 32 is connected to the filter 31, the gas mixing pipe is connected to the air pump 32, the infrared spectrometer 4 is connected to the gas mixing tank 33, and the fourth air outlet on the gas divider 2 is connected to the gas path of the gas mixing tank 33.

[0024] according to Figure 1-2 As shown, an electric heating device for heating the sampled gas, such as an electric heating wire, is provided in the box body of the pretreatment high-temperature box 3. The heating device can be installed on the inner wall of the box body, or can be provided in the gas mixing tank 33, right or spirally wound on the gas pipeline, and the sampling tube 5 is connected to the pretreatment high-temperature box 3 and the infrared spectrometer 4. The pipeline is provided as a heating pipeline 8. The heating pipeline 8 is provided to protect the temperature of the gas when passing from the gas mixing tank 33 to the infrared spectrometer 4, and is composed of thermal insulation cotton wrapped outside the tube wall.

[0025] according to Figure 1-2 As shown, a straight bypass pipe 10 is also provided at the air inlet of the infrared spectrometer 4, one end of the bypass pipe 10 is connected to the heat tracing pipe 8, and the other end is connected to the discharge pipe 6. A float flowmeter is installed on the pipeline between the infrared spectrometer 4 and the discharge pipe 6 and above the infrared spectrometer 4. The gas flowing out of the mixing tank 33 flows to the infrared spectrometer 4 while flowing into the discharge pipe 6 from the bypass pipe 10, thereby avoiding excessive gas flowing into the infrared spectrometer 4 or too fast flow rate to affect the actual detection effect. In addition, because the detection equipment is always online detection, the setting of the bypass pipe 10 is also convenient for the inspection and maintenance of the infrared spectrometer 4.

[0026] A method for detecting exhaust gas, The gas discharged from the flue is collected by using the sampling tube 5, and the standard gas is introduced to verify the accuracy of the detection equipment; The gas in the sampling tube 5 is connected to the pretreatment high temperature box 3 for heating, and nitrogen is introduced for primary dilution before heating; At the same time, nitrogen is introduced into the pretreatment high temperature box 3 for secondary dilution, and the gas after secondary dilution is detected by infrared spectrometer 4, and the gas after detection is re-transported to the flue through exhaust pipe 6; Open the valve on the tracer tube and introduce the tracer gas into the discharge pipe 6 through the gas divider (2).

[0027] The detection method of the present invention can not only further reduce the detection cost and the usage of nitrogen, but also has higher detection safety. On the one hand, before performing volatile organic waste gas detection, the gas path of the detection equipment is detected using standard gas to detect whether the path is smooth and whether there is leakage. On the other hand, the gas path is detected online at all times using tracer gas to avoid gas path leakage that cannot be quickly repaired, affecting the normal detection of volatile organic waste gas. This is because once the detection equipment is installed in the volatile organic waste gas treatment process device and the detection equipment stops working, the volatile organic waste gas cannot be transported normally, thereby causing the entire production line to be unable to work normally, resulting in greater economic losses.

[0028] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0029] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein.

[0030] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An exhaust gas detection device, characterized in that: It comprises a gas divider (2), a pretreatment high temperature box (3), an infrared spectrometer (4), a sampling tube (5) and a discharge tube (6); One end of the sampling tube (5) is used to be connected to the smoke exhaust pipe (7), and the other end is connected in sequence to the first air inlet of the gas divider (2), the first air inlet of the pretreatment high temperature box (3), the air inlet of the infrared spectrometer (4), and then connected to the exhaust pipe (6), and the exhaust pipe (6) is used to be connected to the smoke exhaust pipe (7); The second air inlet and the third air inlet of the gas divider (2) are connected to a standard gas source and a nitrogen source respectively; the second air outlet corresponding to the second air inlet on the gas divider (2) is connected to a sampling tube (5); the third air outlet and the fourth air outlet corresponding to the third air inlet on the gas divider (2); the third air outlet is connected to the sampling tube (5); and the fourth air outlet is connected to a pretreatment high temperature box (3).

2. The exhaust gas detection device according to claim 1, characterized in that: The gas divider (2) is provided with a first air channel, a second air channel, a third air channel and a fourth air channel, the two ends of the first air channel correspond to a first air inlet and a first air outlet respectively, the sampling tube (5) is connected from the first air inlet and connected from the first air outlet, and the first air channel, the third air channel and the fourth air channel are respectively installed with a first mass flow controller, a second mass flow controller and a third mass flow controller.

3. The exhaust gas detection device according to claim 2, characterized in that: The pretreatment high temperature box (3) comprises a filter (31) connected to the sampling tube (5), an air pump (32) and a gas mixing tank (33) in sequence, and the fourth gas outlet on the gas divider (2) is connected to the gas circuit of the gas mixing tank (33).

4. The exhaust gas detection device according to claim 3 is characterized in that: The pipeline connecting the sampling pipe (5) to the pretreatment high temperature box (3) and the infrared spectrometer (4) is configured as a heating pipeline (8).

5. The exhaust gas detection device according to claim 4 is characterized in that: Also includes A heat treatment pipe (9) is provided, one end of which is connected to a heat treatment gas source, and the other end of which is connected to a discharge pipe (6).

6. The exhaust gas detection device according to claim 5, characterized in that: A fourth mass flow controller is installed on the display tube (9).

7. The exhaust gas detection device according to claim 6, characterized in that: It also includes a bypass pipeline (10), one end of which is connected to the heating pipeline (8) and the other end of which is connected to the discharge pipe (6).

8. The exhaust gas detection device according to claim 7, characterized in that: A float flow meter is installed on the pipeline between the infrared spectrometer (4) and the discharge pipe (6).

9. A method for detecting exhaust gas, characterized in that: The gas discharged from the flue is collected by using a sampling tube (5), and standard gas is introduced to verify the accuracy of the detection equipment; The gas in the sampling tube (5) is connected to the pretreatment high temperature box (3) for heating, and nitrogen is introduced for primary dilution before heating; At the same time, nitrogen is introduced into the pretreatment high temperature box (3) for secondary dilution, and the gas after secondary dilution is detected by an infrared spectrometer (4). After the detection, the gas is re-transported to the flue through an exhaust pipe (6); The exhaust gas is introduced into the discharge pipe (6) through the gas divider (2).

10. The detection method according to claim 9, characterized in that: The sampled gas coming out of the pretreatment high temperature box (3) is divided into two paths, one of which is passed into the infrared spectrometer (4) for detection, and the sampled gas exceeding the detection amount of the infrared spectrometer (4) directly flows into the discharge pipe (6) from the other path, and is then transported back to the flue through the discharge pipe (6).

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