Filtering device and measuring system for measuring nitrogen oxides in flue gas by electrochemical method

Abstract

The utility model relates to the technical field of nitrogen oxide measurement, in particular to a filtering device and a measuring system for measuring nitrogen oxide in flue gas by an electrochemical method. The filtering device comprises a filtering bottle, filtering cotton, an air inlet pipe and an air outlet pipe; the filter bottle comprises a bottle body and a bottle cap, the bottle body is filled with alkali liquor, the filter cotton is mounted in the bottle cap, and a set distance is formed between the bottom of the filter cotton and the liquid level of the alkali liquor; the air inlet pipe is inserted into the filter bottle, the lower end of the air inlet pipe is located below the liquid level of alkali liquor, the air outlet pipe is inserted into the filter bottle, and the lower end of the air inlet pipe is located in the filter cotton. According to the utility model, the problems of measurement result error and reduction of electrode catalyst activity caused by sulfur dioxide when nitric oxide in industrial flue gas is measured by using an electrochemical method are solved.

Description

Technical Field

[0001] The utility model relates to the technical field of nitrogen oxide measurement, in particular to a filtering device and a measuring system for measuring nitrogen oxide in flue gas by an electrochemical method. Background Art

[0002] In the steel, chemical, electric power and other industries, it is necessary to measure the nitrogen oxide content in the flue gas. At present, in order to avoid large errors, the ultraviolet laser method is often used for measurement. However, due to the high price of the laser method and the need for more auxiliary equipment, it is usually used in the total exhaust CEMS detection system. X , the related auxiliary equipment cannot be reduced, and a separate room is required to arrange the CEMS cabinet, which increases the floor space of the project site. At the same time, the cost of equipment for laser measurement is much higher than that of electrochemical method, so it cannot be applied on a large scale.

[0003] Electrochemical measurement of nitrogen oxides (NOx) usually uses electrochemical sensors, one of the commonly used sensors is the redox electrode (ORR). However, redox electrodes are susceptible to interference from sulfur dioxide (SO2) when measuring NOx. This interference causes NO X The error in the measurement results. At the same time, SO2 will form a covering layer on the electrode surface, causing the current to decrease, making the measurement result lower. As time accumulates, the activity of the electrode catalyst will be reduced. Utility Model Content

[0004] In view of the deficiencies in the prior art, the purpose of the embodiments of the utility model is to provide a filtering device for measuring nitrogen oxides in flue gas by an electrochemical method, so as to solve the problem that sulfur dioxide causes measurement errors and reduces the activity of electrode catalysts when measuring nitrogen oxides in industrial flue gas by an electrochemical method.

[0005] In order to achieve the above purpose, the embodiment of the utility model provides the following technical solutions:

[0006] A filtering device for measuring nitrogen oxides in flue gas by an electrochemical method, comprising: a filter bottle, filter cotton, an air inlet pipe and an air outlet pipe; the filter bottle comprises a bottle body and a bottle cap, the bottle body is filled with alkali solution, the filter cotton is installed in the bottle cap, and the bottom of the filter cotton is at a set distance from the alkali solution surface; the air inlet pipe is inserted into the filter bottle, and the lower end of the air inlet pipe is located below the alkali solution surface, and the air outlet pipe is inserted into the filter bottle, and the lower end of the air inlet pipe is located in the filter cotton.

[0007] Optionally, the air inlet pipe has a smoke inlet, which is connected to a smoke detection port; the air outlet pipe has a smoke outlet, which is connected to an electrochemical detector.

[0008] Optionally, the alkali solution is calcium carbonate, calcium hydroxide, sodium carbonate or sodium hydroxide.

[0009] Optionally, an alkali solution adding inlet and an alkali solution emptying outlet are provided on the side wall of the bottle body, and the alkali solution adding inlet is located on the upper side of the alkali solution emptying outlet.

[0010] Optionally, an alkali solution addition valve is provided on the alkali solution addition inlet, and an alkali solution emptying valve is provided on the alkali solution emptying outlet.

[0011] Optionally, the filter bottle is made of high borosilicate glass.

[0012] Optionally, the filter cotton is made of synthetic fiber.

[0013] The embodiment of the utility model further provides a measuring system for measuring nitrogen oxides in industrial flue gas, wherein the measuring system comprises the filtering device for measuring nitrogen oxides in flue gas by the electrochemical method as described above.

[0014] Optionally, an electrochemical detector is also included, the upper end of the air inlet pipe is connected to the flue detection port, and the upper end of the air outlet pipe is connected to the electrochemical detector.

[0015] Optionally, a smoke extraction device is also included, and the smoke extraction device is arranged on the air outlet pipe between the electrochemical detector and the filter bottle.

[0016] One or more technical solutions provided in the embodiments of the present utility model have at least the following technical effects or advantages:

[0017] When the utility model is used, the filter device for measuring nitrogen oxides in flue gas by electrochemical method makes the flue gas contact with alkali solution after entering the filter bottle, and then the SO2 component in the flue gas is removed by the alkali solution, and then the NO is detected by electrochemical method. X , avoiding the measurement error caused by sulfur dioxide on nitrogen oxides detection, reducing the impact on the activity of electrode catalysts, extending the service life, and solving the problem of electrochemical detection of NO X At the same time, the utility model sets a filter cotton at a certain distance from the alkali liquid surface on the bottle cap, and arranges the inlet of the air outlet pipe in the filter cotton to filter the alkali liquid droplets, thereby preventing the alkali liquid droplets from entering the electrochemical detector to cause measurement errors and damage the equipment.

[0018] Additional advantages of the present invention will be given in the following description, and some will become apparent from the following description or will be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation on the present invention.

[0020] Figure 1 It is a schematic diagram of a filtering device for measuring nitrogen oxides in flue gas by an electrochemical method provided in an embodiment of the utility model;

[0021] In the figure: 1. filter bottle; 2. air outlet pipe; 3. air inlet pipe; 4. filter cotton; 5. alkali solution adding valve; 6. alkali solution adding inlet; 7. alkali solution emptying valve; 8. alkali solution emptying outlet.

[0022] In order to show the positions of various parts, the distances or sizes between them are exaggerated and the schematic diagram is for reference only. DETAILED DESCRIPTION

[0023] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those of ordinary skill in the art to which the present invention belongs. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0024] Due to the high cost of laser measurement, the electrochemical method is used to measure nitrogen oxides (NOx). One of the commonly used sensors is the redox electrode (ORR). However, the redox electrode is easily interfered by sulfur dioxide (SO2) when measuring NOx. This interference is mainly because the redox potential of SO2 is close to that of NOx, which makes them compete on the electrode, so that SO2 can be oxidized on the redox electrode, generating a current signal, resulting in NO X The error of the measurement results. At the same time, SO2 will generate sulfate on the electrode surface, forming a covering layer, thereby reducing the effective surface area of ​​the electrode. This will cause the current to decrease, resulting in a low measurement result. Over time, the accumulation will cause the electrode catalyst to deactivate.

[0025] Based on the above problems, the utility model proposes a filtering device, which is mainly used to solve the problem of using electrochemical method to measure NO in flue gas in industries such as steel, chemical industry, and electric power. X The problem of large data errors.

[0026] like Figure 1As shown, in one embodiment of the utility model, a filtering device for measuring nitrogen oxides in flue gas by an electrochemical method is proposed, comprising: a filter bottle 1, filter cotton 4, an air inlet pipe 3 and an air outlet pipe 2; the filter bottle 1 comprises a bottle body and a bottle cap, the bottle body is filled with alkali solution, the filter cotton 4 is installed in the bottle cap, and the bottom of the filter cotton 4 has a set distance from the alkali solution surface; the air inlet pipe 3 is inserted into the filter bottle 1, and the lower end of the air inlet pipe 3 is located below the alkali solution surface, the air outlet pipe 2 is inserted into the filter bottle 1, and the lower end of the air inlet pipe 3 is located in the filter cotton 4.

[0027] When the filter device for measuring nitrogen oxides in flue gas by electrochemical method is used, the flue gas first contacts with alkali solution after entering the filter bottle 1, and then the SO2 component in the flue gas is removed by the alkali solution, and then the NO is detected by electrochemical method. X , avoiding the measurement error caused by sulfur dioxide on nitrogen oxides detection, reducing the impact on the activity of electrode catalysts, extending the service life, and solving the problem of electrochemical detection of NO X It cannot be applied to industrial flue gas containing SO2. Compared with the traditional laser method, it does not require a separate building to arrange the flue gas detection device, which saves the project space and reduces the single parameter NO X The cost of testing instruments reduces the purchase cost of instruments.

[0028] In addition, after the flue gas is passed into the alkali solution, the flue gas bubbles explode on the surface of the alkali solution after the reaction, and a certain amount of alkali solution droplets will be generated to enter the flue gas outlet together with the flue gas. The utility model arranges filter cotton 4 at a certain distance from the alkali solution surface on the bottle cap, and arranges the inlet of the air outlet pipe 2 in the filter cotton 4, so as to filter the alkali solution droplets, thereby preventing the alkali solution droplets from entering the electrochemical detector to cause measurement errors and damage to the equipment.

[0029] The air inlet 3 has a smoke inlet, which is connected to the smoke detection port; the air outlet 2 has a smoke outlet, which is connected to the electrochemical detector. Figure 1 The middle arrow indicates the flow direction of the flue gas. The flue gas to be tested in the flue is first passed through the air inlet pipe 3 into the alkaline solution in the filter bottle 1. The alkaline solution can be calcium carbonate, calcium hydroxide, sodium carbonate or sodium hydroxide, etc. The alkaline solution reacts with sulfur dioxide, and the flue gas after removing sulfur dioxide is passed through the air outlet pipe 2 to the electrochemical detector for detection.

[0030] like Figure 1As shown, an alkali solution adding inlet 6 and an alkali solution emptying outlet 8 are provided on the side wall of the bottle body, and the alkali solution adding inlet 6 is located on the upper side of the alkali solution emptying outlet 8. Further, an alkali solution adding valve 5 is provided on the alkali solution adding inlet 6, and an alkali solution emptying valve 7 is provided on the alkali solution emptying outlet 8, and the amount of alkali solution in the filter bottle 1 is controlled by the alkali solution adding valve 5 and the alkali solution emptying valve 7.

[0031] The filter bottle 1 can be made of corrosion-resistant materials such as high borosilicate glass to contain alkali solution, and the alkali solution can be alkali solution such as CaCO3, Ca(OH)2, Na2CO3, NaOH, etc.; the filter cotton 4 can be made of corrosion-resistant materials such as synthetic fibers. Of course, it can be understood that in addition to the several alkali solutions mentioned in this embodiment, other chemical substances can also be used to remove SO2. The filter bottle 1, the filling of alkali solution, and the discharge of alkali solution can all be adjusted.

[0032] Based on the above-mentioned filtering device, the embodiment of the utility model also provides a measurement system for measuring nitrogen oxides in industrial flue gas by electrochemical method, the measurement system also includes an electrochemical detector and a flue gas extraction device, the upper end of the air inlet pipe 3 is connected to the flue detection port, and the upper end of the air outlet pipe 2 is connected to the electrochemical detector. The flue gas extraction device is arranged on the air outlet pipe 2 between the electrochemical detector and the filter bottle 1.

[0033] Measurement process:

[0034] The flue gas extraction device of the electrochemical detector is started, so that the air part above the alkali solution bottle forms a negative pressure, so that the flue gas is sucked into the bottle through the flue gas inlet pipe 3. After the flue gas enters the bottle, it first contacts the alkali solution. After the SO2 in the flue gas contacts the alkali solution, it reacts to generate CaSO3 or Na2SO3. After the reaction, the flue gas bubbles explode on the surface of the alkali solution, and a certain amount of alkali solution droplets will be generated to enter the flue gas outlet together with the flue gas. After reaching the flue gas outlet, they are filtered by the filter cotton 4 to avoid entering NO X Inside the analyzer. After the flue gas reacts with the alkali solution, the SO2 component is removed, avoiding the impact on the detection of nitrogen oxides.

[0035] Although the above describes the specific implementation methods of the utility model in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the utility model. Technical personnel in the relevant field should understand that on the basis of the technical solution of the utility model, various modifications or deformations that can be made by technical personnel in this field without creative work are still within the scope of protection of the utility model.

Claims

1. A filtering device for measuring nitrogen oxides in flue gas by electrochemical method, characterized in that: include: Filter bottle, filter cotton, air inlet pipe and air outlet pipe; The filter bottle comprises a bottle body and a bottle cap, wherein the bottle body is filled with alkali solution, the filter cotton is installed in the bottle cap, and a set distance is set between the bottom of the filter cotton and the surface of the alkali solution; The air inlet pipe is inserted into the filter bottle, and the lower end of the air inlet pipe is located below the liquid level of the alkali solution; the air outlet pipe is inserted into the filter bottle, and the lower end of the air inlet pipe is located in the filter cotton.

2. The filter device for measuring nitrogen oxides in flue gas by electrochemical method according to claim 1, characterized in that: The air inlet pipe has a smoke inlet connected to a smoke detection port; the air outlet pipe has a smoke outlet connected to an electrochemical detector.

3. The filter device for measuring nitrogen oxides in flue gas by electrochemical method according to claim 1, characterized in that: The alkali solution is calcium carbonate, calcium hydroxide, sodium carbonate or sodium hydroxide.

4. The filter device for measuring nitrogen oxides in flue gas by electrochemical method according to claim 1, characterized in that: An alkali solution adding inlet and an alkali solution emptying outlet are arranged on the side wall of the bottle body, and the alkali solution adding inlet is located on the upper side of the alkali solution emptying outlet.

5. The filter device for measuring nitrogen oxides in flue gas by electrochemical method according to claim 4, characterized in that: The alkali solution addition inlet is provided with an alkali solution addition valve, and the alkali solution emptying outlet is provided with an alkali solution emptying valve.

6. The filter device for measuring nitrogen oxides in flue gas by electrochemical method according to claim 1, characterized in that: The filter bottle is made of high borosilicate glass.

7. The filter device for measuring nitrogen oxides in flue gas by electrochemical method according to claim 1, characterized in that: The filter cotton is made of synthetic fiber.

8. A measuring system for measuring nitrogen oxides in industrial flue gas, characterized in that: The measuring system comprises a filtering device for measuring nitrogen oxides in flue gas by an electrochemical method as described in any one of claims 1 to 7.

9. The measuring system according to claim 8, characterized in that It also includes an electrochemical detector, the upper end of the air inlet pipe is connected to the flue detection port, and the upper end of the air outlet pipe is connected to the electrochemical detector.

10. The measuring system according to claim 9, characterized in that It also includes a smoke extraction device, which is arranged on the air outlet pipe between the electrochemical detector and the filter bottle.

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