System and method for detecting concentration of sulfur trioxide

Abstract

The invention relates to the technical field of environmental monitoring, and discloses a system and a method for detecting the concentration of sulfur trioxide. The method comprises the following steps: injecting a barium chloride solution into a tank body of the sulfur trioxide absorption device, and introducing protective gas; under the condition of constant temperature, a gas sample containing sulfur trioxide is extracted from a flue gas pipeline through a gas inlet component of the sampling device, then the gas sample is conveyed into the filtering device to be filtered, and then the filtered gas sample is conveyed into the sulfur trioxide absorption device to be in contact reaction with the barium chloride solution; liquid from the sulfur trioxide absorption device firstly enters the volumetric apparatus to measure the volume, and then enters the detection device to detect the concentration of barium ions in the liquid. The detection method can effectively and repeatedly detect the concentration of sulfur trioxide in the flue gas, and is high in analysis speed, short in detection process, high in accuracy and high in result credibility.

Description

Technical Field

[0001] The present invention relates to the technical field of environmental monitoring, and in particular to a system and method for detecting sulfur trioxide concentration. Background Art

[0002] Measuring the concentration of sulfur trioxide in the flue gas of coal-fired power plants has always been a difficult problem. This is because: 1. The chemical properties of sulfur trioxide are active and it easily reacts with other substances; 2. The concentration of sulfur trioxide in general flue gas is relatively small compared to sulfur dioxide. When testing sulfur trioxide with traditional testing methods (such as the controlled condensation method), condensed water often appears in the condenser tube. Condensed water can significantly absorb sulfur dioxide and interfere with the test; 3. Sulfur trioxide combines with water vapor in the flue gas to produce sulfuric acid. When the temperature drops, sulfuric acid easily condenses. The condensed sulfuric acid will react with the flue and measuring pipeline; 4. The development of sulfur trioxide sampling instruments and monitoring instruments on the market is relatively lagging, and the technical levels are uneven. At present, the testing methods for sulfur trioxide are mainly divided into controlled condensation method, spiral tube method, isopropyl alcohol method, German Pantuo sulfur trioxide tester method, salt absorption method, and cotton plug method. However, there is no unified and widely recognized method for detecting sulfur trioxide in flue gas. Summary of the Invention

[0003] The present invention aims to overcome the existing problems of sulfur trioxide in flue gas, such as low concentration, high activity, difficulty in detection, and susceptibility to pipeline corrosion. By providing a system and method for detecting sulfur trioxide concentration, the system overcomes the unstable nature of sulfur trioxide by directly bringing it into full contact with an acidic barium chloride solution to determine its concentration. Furthermore, the system utilizes novel pipeline materials to avoid sulfur trioxide adsorption, dissolution, and corrosion, thereby reducing measurement errors.

[0004] In order to achieve the above object, the first aspect of the present invention provides a sulfur trioxide concentration detection system, which includes a sampling device, a filtering device, a sulfur trioxide absorption device, a capacity device and a detection device arranged in sequence along the flow direction of the logistics, wherein: The sampling device includes a heating device and an air intake component, wherein the heating device is arranged in the air intake component, and one end of the air intake component extends into the flue gas duct for extracting a gas sample containing sulfur trioxide; The filtering device is used to filter the gas sample from the sampling device, and includes a transversely arranged shell and a filter assembly arranged in the shell, the filter assembly includes a cone structure, the tip of the cone structure faces the air inlet end of the shell, the bottom of the cone structure faces the air outlet end of the shell, and a heating resistor plate is provided on the periphery of the cone structure. A plurality of mesh partitions arranged along the radial direction and quartz sand filled between the mesh partitions are provided in the cavity of the cone structure; The sulfur trioxide absorption device includes a vertically arranged tank body and a gas distribution component arranged in the middle of the tank body. A filter membrane is provided on the inner surface of the bottom of the tank body. The gas sample from the filtering device enters the tank body through the gas distribution component and contacts and reacts with the barium chloride solution contained in the tank body. The reaction mixture is filtered by the filter membrane and discharged from the bottom of the tank body and enters the container. The volumetric device is used to measure the volume of the liquid from the sulfur trioxide absorption device; The detection device is used to sample the liquid in the container and detect the barium ion concentration therein; Wherein, the materials of the cone structure and the mesh separator are MOFs materials.

[0005] Preferably, in the sulfur trioxide absorption device, the gas distribution member is a hollow sphere with a plurality of holes on its surface.

[0006] Preferably, the system further comprises a gas cylinder for supplying protective gas into the tank.

[0007] Preferably, the system further comprises a flushing bottle for conveying flushing liquid into the tank body, and a spray head disposed in the tank body and connected to the flushing bottle.

[0008] Preferably, the gas pipelines between the sampling device and the filtering device and between the filtering device and the sulfur trioxide absorption device are made of titanium alloy.

[0009] Preferably, a flow meter and a vacuum pump are arranged on the gas pipeline between the filtering device and the sulfur trioxide absorption device.

[0010] Preferably, the detection device includes an inductively coupled plasma optical emission spectrometer.

[0011] Preferably, the detection device further includes a calculation module, which can calculate and output the concentration of SO3 in the flue gas according to the following formula:

[0012] in, C SO3 —SO3 concentration in flue gas, in mg / m 3 ; ρ1—barium ion concentration in barium chloride solution before absorbing SO3, in mg / L; V1—the volume of barium chloride solution before absorbing SO3, in mL; ρ2—barium ion concentration in barium chloride solution after absorbing SO3, in mg / L; V2—the volume of barium chloride solution before absorbing SO3, in mL; V—the volume of SO3 introduced into the barium chloride solution, in L, obtained by multiplying the flow rate set by the flow meter and the introduction time; M—Ba relative atomic mass; N—SO3 relative molecular mass.

[0013] Preferably, the MOFs material is selected from at least one of IRMOFs, ZIFs and MILs.

[0014] A second aspect of the present invention provides a method for detecting sulfur trioxide concentration, which is implemented in the system described above and comprises the following steps: S1. Injecting barium chloride solution into the tank of the sulfur trioxide absorption device and introducing protective gas; S2. Under constant temperature conditions, extracting a gas sample containing sulfur trioxide from the flue gas duct through the air intake component of the sampling device, then delivering the gas sample to the filtering device for filtration, and then delivering the filtered gas sample to the sulfur trioxide absorption device for contact reaction with the barium chloride solution; S3. The liquid from the sulfur trioxide absorption device first enters the capacity container to measure the volume, and then enters the detection device to detect the barium ion concentration therein.

[0015] Preferably, in step S1, the protective gas is at least one of nitrogen and an inert gas.

[0016] Preferably, the pH value of the barium chloride solution is less than 6.5, and the concentration is 0.1-1 mol / L.

[0017] Preferably, in step S2, the constant temperature is 200-260°C.

[0018] Preferably, in step S2, the reaction time is 10-15 min.

[0019] The sulfur trioxide concentration detection system described in the present invention maintains a constant temperature during transportation, and utilizes MOFs as filter components and titanium alloy as piping material, thereby preventing sulfur trioxide adsorption, dissolution, and corrosion, thus circumventing its unstable nature. Furthermore, the system optimizes the structure of device components to ensure direct and sufficient contact between sulfur trioxide and the acidic barium chloride solution, reducing measurement errors. The detection method described in the present invention, based on this system, can effectively and repeatedly detect sulfur trioxide concentration in flue gas, with rapid analysis speed, a short detection process, high accuracy, and highly reliable results. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1Schematic diagram of an exemplary sulfur trioxide concentration detection system.

[0021] Reference numerals 1. Sampling device; 2. Filter device; 21. Housing; 22. Filter assembly; 23. Heating resistor plate; 24. Mesh partition; 25. Quartz sand; 3. Sulfur trioxide absorption device; 31. Tank body; 32. Gas distribution component; 33. Filter membrane; 34. Air hole; 35. Nozzle; 4. Capacitor; 5. Detection device; 6. Flow meter; 7. Vacuum pump; 8. Gas cylinder; 9. Rinse bottle. DETAILED DESCRIPTION

[0022] The following is a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0023] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0024] Figure 1 An exemplary sulfur trioxide concentration detection system according to the present invention is shown, which includes a sampling device 1, a filtering device 2, a sulfur trioxide absorption device 3, a container 4 and a detection device 5 arranged in sequence along the flow direction of the material flow, wherein: The sampling device 1 includes a heating device and an air intake component. The heating device is arranged in the air intake component, and one end of the air intake component extends into the flue gas duct to extract a gas sample containing sulfur trioxide; The filtering device 2 is used to filter the gas sample from the sampling device 1, and includes a transversely arranged housing 21 and a filtering assembly 22 arranged in the housing 21. The filtering assembly 22 includes a cone structure, the tip of the cone structure faces the air inlet end of the housing 21, and the bottom of the cone structure faces the air outlet end of the housing 21. A heating resistor plate 23 is provided on the periphery of the cone structure, and a plurality of radially arranged mesh partitions 24 and quartz sand 25 filled between the mesh partitions 24 are provided in the cavity of the cone structure. The sulfur trioxide absorption device 3 includes a vertically arranged tank body 31 and a gas distribution member 32 arranged in the middle of the tank body 31. A filter membrane 33 is provided on the inner surface of the bottom of the tank body 31. The gas sample from the filtering device 2 enters the tank body 31 through the gas distribution member 32 and contacts and reacts with the barium chloride solution contained in the tank body 31. The reaction mixture is filtered by the filter membrane 33 and discharged from the bottom of the tank body 31 and enters the container 4. The capacity vessel 4 is used to measure the volume of the liquid from the sulfur trioxide absorption device 3; The detection device 5 is used to sample the liquid in the container 4 and detect the barium ion concentration therein; The cone structure and the mesh separator 24 are made of MOFs material.

[0025] In this exemplary embodiment, the filter assembly 22 may include a hollow cone structure made of MOFs material, the tip of the hollow cone structure is toward the air inlet end of the shell 21, and the bottom end of the cone structure is toward the air outlet end of the shell 21. The outer surface of the hollow cone structure is provided with a plurality of heating resistor plates 23, and the interior of the hollow cone structure is provided with a plurality of mesh partitions 24 arranged along the radial direction and quartz sand 25 filled between the mesh partitions 24. The plurality of mesh partitions 24 and the hollow cone structure can be a whole or a separate structure with independent configuration.

[0026] In this exemplary embodiment, in the sulfur trioxide absorption device 3 , in order to allow the gas sample from the filtering device 2 to fully contact the barium chloride solution in the sulfur trioxide absorption device 3 so that sulfur trioxide can be completely absorbed, the gas distribution member 32 can be a hollow sphere with a plurality of holes on the surface.

[0027] In a more preferred embodiment, in the sulfur trioxide absorption device 3, in order to make the gas sample from the filtering device 2 contact with the barium chloride solution in the sulfur trioxide absorption device 3 more complete and the absorption of sulfur trioxide more thorough, the gas distribution component 32 can be configured as a hollow sphere with 15-25, more preferably 20, circular holes distributed on the surface, wherein the diameter of the hollow sphere is 3-5 cm, and the diameter of the circular hole is 0.2-0.7 cm.

[0028] In a preferred embodiment, in order to prevent the gas distribution component 32 from being corroded by sulfur trioxide in the gas sample, thereby damaging the device structure and affecting the accuracy of sulfur trioxide concentration detection, the material of the hollow ball is selected from at least one of PVC, titanium alloy and stainless steel, preferably PVC.

[0029] In this exemplary embodiment, the system may further include a gas cylinder 8 for supplying protective gas into the tank body 31, and a gas hole 34 disposed in the tank body 31 and connected to the gas cylinder 8. During the sulfur trioxide detection process, the gas valve on the gas cylinder 8 is opened to provide an inert atmosphere inside the tank body 31.

[0030] In this exemplary embodiment, the system may further include a rinse bottle 9 for delivering a rinse liquid into the tank body 31, and a spray head 35 disposed in the tank body 31 and connected to the rinse bottle 9. After the sulfur trioxide detection process is completed, the valve on the rinse bottle 9 is opened, and the rinse liquid from the rinse bottle 9 is flushed through the spray head 35 to rinse the solid precipitates deposited on the inner wall of the tank body 31.

[0031] In this exemplary embodiment, in order to reduce the unstable decomposition of sulfur trioxide gas during material transmission, the gas pipelines between the sampling device 1 and the filtering device 2 and between the filtering device 2 and the sulfur trioxide absorption device 3 can be made of titanium alloy.

[0032] In this exemplary embodiment, in order to provide negative pressure to drain the sulfur trioxide-containing gas sample from the sampling device 1 and measure its total volume, a flow meter 6 and a suction pump 7 may be arranged on the gas pipeline between the filtering device 2 and the sulfur trioxide absorption device 3 .

[0033] In this exemplary embodiment, in order to more accurately measure the barium ion concentration in the barium chloride solution remaining in the sulfur trioxide absorption device 3 after the absorption of sulfur trioxide is completed, the detection device 5 may include an inductively coupled plasma optical emission spectrometer.

[0034] In this exemplary embodiment, the detection device 5 may further include a calculation module, which can calculate and output the concentration of SO3 in the flue gas according to the following formula:

[0035] in, C SO3 —SO3 concentration in flue gas, in mg / m 3 ; ρ1—barium ion concentration in barium chloride solution before absorbing SO3, in mg / L; V1—the volume of barium chloride solution before absorbing SO3, in mL; ρ2—barium ion concentration in barium chloride after absorbing SO3, in mg / L; V2—the volume of barium chloride solution before absorbing SO3, in mL; V—the volume of SO3 introduced into the barium chloride solution, in L, obtained by multiplying the flow rate set by the flow meter and the introduction time; M—Ba relative atomic mass; N—SO3 relative molecular mass.

[0036] In the present invention, the MOFs material can be at least one of IRMOFs, ZIFs, and MILs, preferably IRMOFs. When the MOFs material is one of the aforementioned materials (especially the preferred materials), the gas pipeline has enhanced corrosion resistance, preventing sulfur trioxide from adhering to the gas pipeline to form sulfuric acid, thereby improving the accuracy of sulfur trioxide concentration detection.

[0037] The method for detecting sulfur trioxide concentration of the present invention can be used in Figure 1 The exemplary sulfur trioxide concentration detection system shown is implemented in the method comprising the following steps: S1, injecting barium chloride solution into the tank 31 of the sulfur trioxide absorption device 3 and introducing protective gas; S2. Under constant temperature conditions, extracting a gas sample containing sulfur trioxide from the flue gas duct through the air intake component of the sampling device 1, then delivering the gas sample to the filtering device 2 for filtration, and then delivering the filtered gas sample to the sulfur trioxide absorption device 3 for contact reaction with the barium chloride solution; S3. The liquid from the sulfur trioxide absorption device 3 first enters the container 4 to measure the volume, and then enters the detection device 5 to detect the barium ion concentration therein.

[0038] In the present invention, in step S1, the protective gas may be at least one of nitrogen and an inert gas, preferably nitrogen.

[0039] In the method of the present invention, the pH value of the barium chloride solution can be less than 6.5, preferably 6-6.5; the concentration can be 0.1-1 mol / L, preferably 0.5-0.8 mol / L. In the method of the present invention, when the pH value and concentration of the barium chloride solution are within the above ranges (especially within the preferred ranges), the detection of sulfur trioxide concentration is more accurate.

[0040] In the method of the present invention, in step S2, the constant temperature may be 200-260° C., preferably 250-260° C. In the method of the present invention, when the constant temperature is within the above range (especially within the preferred range), the instability of sulfur trioxide can be better avoided.

[0041] In the method of the present invention, step S2 may further include using the flow meter 6 to continuously record the flow rate of the sulfur trioxide-containing gas sample and record the time of conveying the sulfur trioxide-containing gas sample to calculate the total volume of the sulfur trioxide-containing gas sample.

[0042] In the method of the present invention, in step S2, the reaction time can be 10-15 minutes, preferably 12-13 minutes. In the method of the present invention, when the reaction time is within the above range (especially within the preferred range), the reaction between the sulfur trioxide and the barium chloride solution is more thorough.

[0043] In some embodiments, the method for detecting the sulfur trioxide concentration may further include: a calculation module in the detection device 5 receives liquid volume data from the container 4, barium ion concentration data obtained by the detection device 5, and total volume data of the sulfur trioxide-containing gas sample, and calculates the concentration of sulfur trioxide in the sulfur trioxide-containing gas sample.

[0044] In some embodiments, the method for detecting the sulfur trioxide concentration may further include: after the detection of the barium ion concentration in the detection device 5 is completed, closing the gas cylinder 8 and opening the flushing bottle 9 to remove the barium sulfate precipitate attached to the inner wall of the tank body 31, and removing the residual material in the capacity container 4 and the tank body 31.

[0045] In some embodiments, the method for detecting the sulfur trioxide concentration may include: injecting a barium chloride solution with a pH value of less than 6.5 and a concentration of 0.1-1 mol / L into the tank body 31 of the sulfur trioxide absorption device 3 and introducing nitrogen and / or inert gas therein through a gas cylinder 8; extracting a gas sample containing sulfur trioxide from the flue gas duct through the air intake component of the sampling device 1 under a constant temperature of 200-260°C, then delivering the gas sample to the filtering device 2 for filtration, and then delivering the filtered gas sample to the sulfur trioxide absorption device 3 to be mixed with the barium chloride solution. The contact reaction is carried out for 12-13 minutes, and the flow rate and delivery time of the sulfur trioxide-containing gas sample are recorded simultaneously. After the reaction is completed, the liquid from the sulfur trioxide absorption device 3 first enters the container 4 to measure the volume, and then enters the detection device 5 to detect the barium ion concentration therein. The calculation module in the detection device 5 receives the liquid volume data from the container 4, the barium ion concentration data obtained by the detection device 5, and the total volume data of the sulfur trioxide-containing gas sample, and calculates the concentration of sulfur trioxide in the sulfur trioxide-containing gas sample.

[0046] The following examples further illustrate the sulfur trioxide concentration detection system and method of the present invention. The examples are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operating processes, but the scope of protection of the present invention is not limited to the following examples.

[0047] The following examples are all in Figure 1 The sulfur trioxide concentration detection system shown in the figure is implemented, and the system includes a sampling device 1, a filtering device 2, a sulfur trioxide absorption device 3, a capacity device 4 and a detection device 5 arranged in sequence along the flow direction of the logistics, wherein, The sampling device 1 includes a heating device and an air intake component. The heating device is arranged in the air intake component, and one end of the air intake component extends into the flue gas duct to extract a gas sample containing sulfur trioxide; The filtering device 2 is used to filter the gas sample from the sampling device 1, and includes a transversely arranged housing 21 and a filtering assembly 22 arranged in the housing 21. The filtering assembly 22 is a cone structure, with the tip of the cone structure facing the air inlet end of the housing 21 and the bottom of the cone structure facing the air outlet end of the housing 21. A heating resistor plate 23 is provided on the periphery of the cone structure, and a plurality of radially arranged mesh partitions 24 and quartz sand 25 filled between the mesh partitions 24 are provided in the cavity of the cone structure. The sulfur trioxide absorption device 3 includes a vertically arranged tank body 31 and a gas distribution member 32 arranged in the middle of the tank body 31. A filter membrane 33 is provided on the inner surface of the bottom of the tank body 31. The gas sample from the filtering device 2 enters the tank body 31 through the gas distribution member 32 and contacts and reacts with the barium chloride solution contained in the tank body 31. The reacted mixture is filtered by the filter membrane 33 and discharged from the bottom of the tank body 31 and enters the container 4. The gas distribution member 32 is a hollow sphere with 20 circular holes with a diameter of 0.5 cm distributed on the surface. The diameter of the hollow sphere is 4 cm and the material is PVC. The capacity vessel 4 is used to measure the volume of the liquid from the sulfur trioxide absorption device 3; The detection device 5 is an inductively coupled plasma optical emission spectrometer equipped with a calculation module, which is used to sample the liquid in the container 4 and detect the barium ion concentration therein; The system further includes a gas cylinder 8 for supplying protective gas into the tank body 31 and a gas hole 34 provided in the tank body 31 and connected to the gas cylinder 8; The system further comprises a flushing bottle 9 for delivering flushing liquid into the tank body 31 and a spray head 35 disposed in the tank body 31 and connected to the flushing bottle 9; The system further includes a flow meter 6 and a vacuum pump 7 disposed on the gas pipeline between the filtering device 2 and the sulfur trioxide absorption device 3; Wherein, the material of the cone structure and the mesh partition 24 is IRMOFs; The gas pipelines between the sampling device 1 and the filtering device 2 and between the filtering device 2 and the sulfur trioxide absorption device 3 are made of titanium alloy.

[0048] Unless otherwise specified, the experimental methods in the following examples are conventional methods in the art.

[0049] Unless otherwise specified, the experimental materials used in the following examples are commercially available.

[0050] Example 1 (1) injecting a barium chloride solution with a pH value of 6.0 and a concentration of 0.8 mol / L into the tank 31 of the sulfur trioxide absorption device 3 and introducing nitrogen gas into the tank 31 through the gas cylinder 8; (2) Under the constant temperature of 210°C, the air was taken from the gas storage containing 50mg / m 3 A gas sample containing sulfur trioxide is extracted from a gas storage tank for a sulfur trioxide gas sample, and then transported to the filtering device 2 for filtration to remove solid particles such as smoke and dust. The filtered gas sample is then transported to the sulfur trioxide absorption device 3 to contact and react with the barium chloride solution for 12 minutes. The flow rate of the sulfur trioxide-containing gas sample is recorded as 20 L / min, and the transport time is 15 minutes; (3) After the reaction is completed, the valve at the bottom of the tank 31 is opened to guide the liquid in the sulfur trioxide absorption device 3 into the container 4 to measure the volume, and then into the detection device 5 to detect the barium ion concentration therein. The concentration of sulfur trioxide in the sulfur trioxide-containing gas sample is obtained by the calculation module to be 49.9 mg / m 3 .

[0051] Example 2 This example is implemented according to the method described in Example 1, except that in step (1), the pH value of the barium chloride solution is 6.3 and the concentration is 0.7 mol / L.

[0052] The concentration of sulfur trioxide in the sulfur trioxide-containing gas sample obtained by the calculation module is 49.9 mg / m 3 .

[0053] Example 3 This example is implemented according to the method described in Example 1, except that in step (1), the pH value of the barium chloride solution is 6.5 and the concentration is 0.6 mol / L.

[0054] The concentration of sulfur trioxide in the sulfur trioxide-containing gas sample obtained by the calculation module is 49.7 mg / m 3 .

[0055] Example 4 This embodiment is implemented in accordance with the method described in Example 1, except that in step (2), at a constant temperature of 200°C, the air inlet component of the sampling device 1 is taken from a gas containing 20 mg / m 3 A gas sample containing sulfur trioxide is extracted from the gas storage tank of the sulfur trioxide gas sample, and then transported to the filtering device 2 for filtration to remove solid particles such as smoke and dust. The filtered gas sample is then transported to the sulfur trioxide absorption device 3 to contact and react with the barium chloride solution for 12 minutes. The flow rate of the sulfur trioxide-containing gas sample is recorded as 20 L / min, and the transport time is 15 minutes.

[0056] The concentration of sulfur trioxide in the sulfur trioxide-containing gas sample obtained by the calculation module is 19.8 mg / m 3 .

[0057] Example 5 This embodiment is implemented in accordance with the method described in Example 1, except that in step (2), at a constant temperature of 260°C, the air inlet component of the sampling device 1 is taken from a gas containing 30 mg / m 3 A gas sample containing sulfur trioxide is extracted from the gas storage tank of the sulfur trioxide gas sample, and then transported to the filtering device 2 for filtration to remove solid particles such as smoke and dust. The filtered gas sample is then transported to the sulfur trioxide absorption device 3 to contact and react with the barium chloride solution for 12 minutes. The flow rate of the sulfur trioxide-containing gas sample is recorded as 20 L / min, and the transport time is 15 minutes.

[0058] The concentration of sulfur trioxide in the sulfur trioxide-containing gas sample obtained by the calculation module is 29.9 mg / m 3 .

[0059] Example 6 This embodiment is implemented in accordance with the method described in Example 1, except that, in step (2), the air intake component of the sampling device 1 extracts a gas sample containing sulfur trioxide from the flue gas duct of the coal-fired power plant for detection.

[0060] The concentration of sulfur trioxide in the sulfur trioxide-containing gas sample obtained by the calculation module is 33.5 mg / m3 At the same point, the SO3 concentration in the flue gas was measured using the method in the "Controlled Condensation Method for SO3 Test in Flue Gas of Thermal Power Plants" (DL / T 1990-2019) and was 33.2 mg / m 3 .

[0061] Comparative Example 1 (1) injecting a barium chloride solution with a pH value of 6.0 and a concentration of 1 mol / L into the tank 31 of the sulfur trioxide absorption device 3 and introducing nitrogen gas into the tank 31 through the gas cylinder 8; (2) Extract the gas containing 30mg / m 3 A sulfur trioxide gas sample was heated to 300° C. and then passed into a serpentine condenser tube for condensation at 70° C. The flow rate of the condensed sulfur trioxide gas sample was recorded as 20 L / min and the delivery time was 15 min. (3) The absorbent is introduced into the serpentine condenser, and then the mixed liquid is introduced into the sulfur trioxide absorption device 3 for contact reaction. The valve at the bottom of the tank 31 is opened to guide the liquid of the sulfur trioxide absorption device 3 into the container 4 to measure the volume, and then into the detection device 5 to detect the barium ion concentration therein. The concentration of sulfur trioxide in the sulfur trioxide-containing gas sample is obtained by the calculation module to be 27.6 mg / m 3 .

[0062] Test Example 1 The concentrations of sulfur trioxide in Examples 1-6 and Comparative Example 1 were calculated by the calculation module in the detection device 5 , and the results are shown in Table 1.

[0063] Table 1

[0064] As can be seen from Table 1, by adopting the technical solution described in the present invention, Examples 1-5 can accurately measure the sulfur trioxide concentration in a gas sample containing sulfur trioxide of known concentration. Compared with Comparative Example 1, the sulfur trioxide loss generated during the detection process is effectively reduced, which leads to inaccurate detection results. When Example 6 is used to detect the sulfur trioxide concentration in the flue gas duct of a coal-fired power plant, the detection result is basically the same as the detection result obtained by the method in the "Controlled Condensation Method for SO3 Test in Flue Gas of Thermal Power Plant" (DL / T1990-2019), and the result obtained due to less loss during the detection process is higher than the result obtained in DL / T 1990-2019, indicating that the system and method described in the present invention can be well applied in practical applications.

[0065] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A sulfur trioxide concentration detection system, characterized in that: The system comprises a sampling device (1), a filtering device (2), a sulfur trioxide absorption device (3), a capacity device (4) and a detection device (5) which are sequentially arranged along the flow direction of the material flow, wherein: The sampling device (1) comprises a heating device and an air intake component, wherein the heating device is arranged in the air intake component, and one end of the air intake component extends into the flue gas duct for extracting a gas sample containing sulfur trioxide; The filtering device (2) is used to filter the gas sample from the sampling device (1), and comprises a housing (21) arranged transversely and a filtering assembly (22) arranged in the housing (21), wherein the filtering assembly (22) comprises a cone structure, the tip of the cone structure faces the air inlet end of the housing (21), the bottom of the cone structure faces the air outlet end of the housing (21), a heating resistor plate (23) is arranged on the periphery of the cone structure, and a plurality of mesh partitions (24) arranged radially and quartz sand (25) filled between the mesh partitions (24) are arranged in the cavity of the cone structure; The sulfur trioxide absorption device (3) comprises a vertically arranged tank body (31) and a gas distribution component (32) arranged in the middle of the tank body (31); a filter membrane (33) is arranged on the inner surface of the bottom of the tank body (31); a gas sample from the filtering device (2) enters the tank body (31) through the gas distribution component (32) and contacts and reacts with the barium chloride solution contained in the tank body (31); the reaction mixture is filtered by the filter membrane (33), discharged from the bottom of the tank body (31) and enters the container (4); The volumetric device (4) is used to measure the volume of the liquid from the sulfur trioxide absorption device (3); The detection device (5) is used to sample the liquid in the container (4) and detect the barium ion concentration therein; Wherein, the material of the cone structure and the mesh partition (24) is MOFs material.

2. The system according to claim 1, wherein: In the sulfur trioxide absorption device (3), the gas distribution component (32) is a hollow sphere with a plurality of holes on the surface.

3. The system according to claim 1 or 2, characterized in that The system further comprises a gas cylinder (8) for supplying protective gas into the tank (31).

4. The system according to claim 1, 2 or 3, characterized in that The system further comprises a flushing bottle (9) for conveying flushing liquid into the tank body (31) and a spray head (35) disposed in the tank body (31) and connected to the flushing bottle (9).

5. The system according to any one of claims 1 to 4, characterized in that: The gas pipelines between the sampling device (1) and the filtering device (2) and between the filtering device (2) and the sulfur trioxide absorption device (3) are made of titanium alloy; and / or, A flow meter (6) and a vacuum pump (7) are arranged on the gas pipeline between the filtering device (2) and the sulfur trioxide absorption device (3).

6. The system according to any one of claims 1 to 5, characterized in that: The detection device (5) includes an inductively coupled plasma emission spectrometer.

7. The system according to claim 1 or 6, characterized in that The detection device (5) further includes a calculation module, which can calculate and output the concentration result of SO3 in the flue gas according to the following formula: in, C SO3 —SO3 concentration in flue gas, in mg / m 3 ; ρ1—barium ion concentration in barium chloride solution before absorbing SO3, in mg / L; V1—the volume of barium chloride solution before absorbing SO3, in mL; ρ2—barium ion concentration in barium chloride after absorbing SO3, in mg / L; V2—the volume of barium chloride solution before absorbing SO3, in mL; V—the volume of SO3 introduced into the barium chloride solution, in L, obtained by multiplying the flow rate set by the flow meter and the introduction time; M—Ba relative atomic mass; N—SO3 relative molecular mass.

8. The system according to any one of claims 1 to 7, characterized in that: The MOFs material is selected from at least one of IRMOFs, ZIFs and MILs.

9. A method for detecting sulfur trioxide concentration, characterized in that: The method is implemented in the system according to any one of claims 1 to 8, and the method comprises the following steps: S1, injecting barium chloride solution into the tank (31) of the sulfur trioxide absorption device (3) and introducing protective gas; S2. Under constant temperature conditions, extracting a gas sample containing sulfur trioxide from the flue gas duct through the air intake component of the sampling device (1), then transporting the gas sample to the filtering device (2) for filtration, and then transporting the filtered gas sample to the sulfur trioxide absorption device (3) for contact reaction with the barium chloride solution; S3. The liquid from the sulfur trioxide absorption device (3) first enters the container (4) to measure the volume, and then enters the detection device (5) to detect the barium ion concentration therein.

10. The method according to claim 9, characterized in that In step S1, the protective gas is at least one of nitrogen and an inert gas; and / or, The pH value of the barium chloride solution is less than 6.5, and the concentration is 0.1-1 mol / L; and / or, In step S2, the constant temperature is 200-260° C.; and / or, In step S2, the reaction time is 10-15 minutes.

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