Sulfur trioxide gas standard generation device and generation method

Abstract

The invention discloses a sulfur trioxide gas standard generation device and method, a gas dilution mixing system inputs double gas sources and can realize accurate regulation and control of reaction gas concentration and flow, and the outlet end of the gas dilution mixing system is connected with a sulfur trioxide generation system; the sulfur trioxide generation system comprises a reaction furnace, a quartz reaction tube and a heater, the quartz reaction tube is arranged in the reaction furnace, the quartz reaction tube is filled with composite catalytic particles, the outer side of the quartz reaction tube is coated with a heating sleeve, and the heater is embedded in the upper part in the reaction furnace; the outlet end of the quartz reaction tube is respectively connected with a detection system and a collection condensation system through a heat-preservation vaporization system, the output end of the collection condensation system is connected with the detection system, and the output end of the detection system is connected with a tail gas absorption system. The problems of lack of SO3 standard gas and poor stability at present can be effectively solved, a reliable standard substance is provided for accurate monitoring of sulfur trioxide gas, and the performance and the quantity value traceability of detection equipment are improved.

Description

Technical Field

[0001] This invention relates to the field of environmental protection technology, and in particular to a standard sulfur trioxide gas generator and generation method. Background Technology

[0002] Sulfur trioxide (SO3) gas plays a crucial role in many industrial sectors, including chemical, energy, and environmental protection. It is an indispensable raw material, particularly in the synthesis of products such as detergents, leather, pharmaceuticals, petroleum, and energy. However, SO3 gas itself is highly corrosive and irritating, posing a significant threat to the environment and human health. SO3 leaks not only lead to air pollution and acid rain but can also cause occupational diseases such as chronic bronchitis and emphysema. Furthermore, leaks pose a significant safety risk of fire and explosion. Therefore, real-time monitoring of SO3 gas concentration is crucial for protecting worker health, production safety, and environmental protection. For example, monitoring SO3 concentration in the flue gas of coal-fired power plants not only helps assess the pollution level of these plants but also provides data support for environmental protection measures such as desulfurization and dust removal.

[0003] However, the extremely high reactivity of SO3 gas presents significant challenges in its preparation and storage as a standard gas. Currently, there is a lack of internationally recognized SO3 standard gases, which hinders the performance verification and metrological traceability of SO3 gas detection equipment. Therefore, developing SO3 gas standard materials or SO3 gas standard generators is crucial to solving the current challenges in performance verification and metrological traceability of detection equipment. Summary of the Invention

[0004] The purpose of this invention is to provide a standard apparatus and method for the stable preparation of sulfur trioxide gas, thereby solving the aforementioned problems in the prior art.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] This invention discloses a sulfur trioxide gas standard generating device, comprising a gas dilution and mixing system, a sulfur trioxide generating system, a heat preservation vaporization system, a detection system, a collection and condensation system, and a tail gas absorption system. The gas dilution and mixing system receives dual gas sources and can achieve precise control of the concentration and flow rate of the reactant gases. The outlet end of the gas dilution and mixing system is connected to the sulfur trioxide generating system. The sulfur trioxide generating system includes a reactor, a U-shaped quartz reaction tube, and a heater. The U-shaped quartz reaction tube is disposed inside the reactor and filled with composite catalytic particles. A heating jacket is wrapped around the outside of the U-shaped quartz reaction tube and is connected to a temperature controller. The heater is embedded in the hollow area at the upper part of the reactor. The outlet end of the U-shaped quartz reaction tube is connected to the detection system and the collection and condensation system respectively through the heat preservation vaporization system. The output end of the collection and condensation system is connected to the detection system, and the output end of the detection system is connected to the tail gas absorption system.

[0007] Furthermore, the composite catalytic particles are prepared by a granulation process using a vanadium-based catalyst, a silica support, and an additive. The mass ratio of the vanadium-based catalyst to the silica support is 1:5 to 1:10, and the mass fraction of the additive is 0.5% to 3%.

[0008] Furthermore, the method for filling the composite catalyst particles is to mix the granulated catalyst particles with a diluent at a volume ratio of 1:1 to 1:3, and then preheat and dry them under a nitrogen atmosphere before reacting.

[0009] Furthermore, the gas dilution and mixing system includes a gas source, a pressure reducing valve, and a standard gas dilution device. The two gas sources are respectively connected to the standard gas dilution device through the pressure reducing valve. The standard gas dilution device includes a control module, a mass flow controller, a solenoid valve drive module, a power supply module, a communication module, and a display module. The mass flow controller controls the flow rate of the reactant gas according to the concentration value set by the control module. Through dynamic gas mixing technology, the concentration and flow rate of the reactant gas are precisely controlled, thereby achieving the purpose of preparing the target gas concentration.

[0010] Furthermore, the heat-insulating vaporization system includes heat-insulating pipes and a three-way valve. The inlet of the three-way valve is connected to the outlet end of the U-shaped quartz reaction tube, and the two outlets of the three-way valve are respectively connected to the detection system and the collection and condensation system. The heat-insulating pipes are connected between the outlet end of the U-shaped quartz reaction tube and the three-way valve, between the three-way valve and the detection system, and between the three-way valve and the collection and condensation system.

[0011] Furthermore, the insulated pipe has a double-layer vacuum insulation sleeve structure, with a carbon steel pipe lined with polytetrafluoroethylene and an outer layer covered with an aluminum silicate insulation layer.

[0012] Furthermore, the collection and condensation system includes a multi-stage condensation device and a quantitative capture module. The multi-stage condensation device uses segmented temperature control technology to achieve rapid liquid solidification of sulfur trioxide. The quantitative capture module performs quantitative analysis of sulfur trioxide in the condensation products by weighing or ion chromatography.

[0013] Furthermore, the multi-stage condensation device includes a first condenser, a second condenser, and a third condenser. The first condenser, the second condenser, and the third condenser are all serpentine condensers, and each section is independently temperature-controlled. A sulfur trioxide adsorption membrane is provided at each outlet end to prevent sulfur trioxide from escaping.

[0014] Furthermore, quartz wool with a particle size of 4μm is added to the tail ends of the first condenser, the second condenser, and the third condenser to improve the separation efficiency of acid mist.

[0015] The present invention also provides a method for generating a sulfur trioxide gas standard, using the aforementioned sulfur trioxide gas standard generating apparatus, comprising the following steps:

[0016] Two gas sources are pressure-stabilized by pressure reducing valves before entering the standard gas dilution device. The flow rate of each gas is precisely adjusted by the control module according to the set concentration value, and the gases are mixed in the mixing chamber to achieve dynamic preparation of the target gas concentration. The mixed gas is then transported to the U-shaped quartz reaction tube in the reactor for reaction through the outlet of the mixing chamber. After the reaction, the gas is evenly dispersed and fully mixed by the heat preservation vaporization system, and then enters the detection system through a three-way valve to achieve real-time gas composition detection. The other gas enters the collection and condensation system, where sulfur trioxide is directionally condensed and quantitatively analyzed through segmented temperature control. The collection and condensation system is connected to the detection system through multi-stage condensation pipes, and the outlet of the detection system is connected to the tail gas absorption system to ensure safe emission.

[0017] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0018] The sulfur trioxide gas standard generating device and method of this invention, through the design of a vanadium-based composite catalyst, enables the efficient and rapid oxidation of sulfur dioxide to sulfur trioxide. A U-shaped quartz tube enhances mass transfer efficiency, and integrated dynamic gas distribution and multi-parameter online monitoring ensure gas stability and traceability. Combined with segmented condensation and quantitative capture technology, dual verification of SO3 calibration is achieved, providing a high-precision solution for SO3 detection equipment calibration and method identification. Simultaneously, this invention effectively solves the current problems of insufficient and unstable SO3 standard gases, thus providing reliable standard materials for accurate monitoring of sulfur trioxide gas, improving the performance and traceability of detection equipment, promoting the improvement of SO3 gas detection accuracy, contributing to the standardization development in environmental protection, industrial safety, and health management, and providing reliable data support and technical assurance for relevant enterprises. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the sulfur trioxide gas standard generator of the present invention.

[0021] Explanation of reference numerals in the attached diagram: 1. Gas dilution and mixing system; 2. Pressure reducing valve; 3. Solenoid valve; 4. Mixing chamber; 5. Pressure gauge; 6. Insulation box display module; 7. Reaction temperature control module; 8. Reactor temperature control module; 9. Reactor; 10. U-shaped quartz reaction tube; 11. Filter; 12. Three-way valve; 13. Sulfur trioxide generation system; 14. Insulation vaporization system; 15. Detection system; 16. First condenser; 17. Second condenser; 18. Third condenser; 19. Collection and condensation system; 20. Tail gas absorption system. Detailed Implementation

[0022] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0023] In the description of this invention, it should be understood that the terms "length," "width," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0024] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0025] The technical solutions provided by the various embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0026] Example 1

[0027] like Figure 1 As shown, the sulfur trioxide gas standard generating device of this embodiment 1 includes a gas dilution and mixing system 1, a sulfur trioxide generating system 13, a heat preservation vaporization system 14, a detection system 15, a collection and condensation system 19, and a tail gas absorption system 20. The gas dilution and mixing system 1 is equipped with dual gas sources and achieves precise control of the concentration and flow rate of the reactant gas through dynamic gas distribution technology. The gas dilution and mixing system 1 integrates dynamic gas distribution technology, supports dual gas source input, and achieves precise control of concentration and flow rate over a wide range. A pressure gauge is installed at the outlet end of the gas dilution and mixing system 1 and connected to the sulfur trioxide generating system 13.

[0028] The sulfur trioxide generation system 13 includes a reactor 9, a U-shaped quartz reaction tube 10, and a heater. The U-shaped quartz reaction tube 10 is located inside the reactor 9 and is filled with composite catalytic particles. The outside of the U-shaped quartz reaction tube 10 is covered with a heating jacket, which is connected to a temperature controller. A heater is embedded in the hollow area at the top of the reactor 9 for local rapid heating when disassembling the reaction tube joint, avoiding thermal stress damage. It can be combined with a gradient temperature control module to improve the catalytic oxidation efficiency of sulfur dioxide.

[0029] At this time, the outlet end of the U-shaped quartz reaction tube 10 is connected to the detection system 15 and the collection and condensation system 19 through the heat-insulating vaporization system 14. After the reaction, the gas is evenly dispersed through the heat-insulating vaporization system 14 and diverted to the detection system 15 through the three-way valve 12. The SO2 / SO3 concentration is detected online and feedback is provided for calibration. Alternatively, the gas is diverted to the collection and condensation system 19 for segmented temperature control and directional capture of the product. Quantitative analysis can be performed by gravimetric method or ion chromatography. The output end of the collection and condensation system 19 is connected to the detection system 15. The output end of the detection system 15 is connected to the tail gas absorption system 20. The tail gas treatment system absorbs and neutralizes unreacted gas and residues with alkaline solution to ensure that the emissions meet environmental protection requirements.

[0030] The composite catalytic particles are prepared by granulation of a vanadium-based catalyst, a silica support, and an additive. Different sizes of catalysts are prepared through granulation, with a catalyst loading mass of 100-1000 mg, a catalyst particle size of 0.5-2 mm, a vanadium-based catalyst to silica support mass ratio of 1:5-1:10, and an additive mass fraction of 0.5%-3%. Preferably, the vanadium-based catalyst is vanadium pentoxide, and the additive is cesium.

[0031] At this point, the composite catalyst particles are filled by mixing the granulated catalyst particles with quartz sand diluent at a volume ratio of 1:1 to 1:3, and fixing them with quartz wool. The quartz wool is then used to fill and fix the mixed particles in layers, forming an axially gradient catalytic bed. This allows the gas to diffuse uniformly radially, reducing the bypass rate to ≤5%, while preventing excessive gas resistance and maintaining a gas flow pressure drop ≤5 kPa. The reaction is then carried out under a nitrogen atmosphere, preheated and dried at 200°C for 12 hours. The U-shaped quartz reaction tube 10 is heated and kept at a temperature by a temperature controller. Using SO2 and O2 as reaction gases, the reaction temperature can be controlled between 400-500°C, achieving high conversion rates and rapid equilibrium with relatively little catalyst.

[0032] Furthermore, reactor 9 is a high-temperature open reactor. An M-type heater is placed in the hollow area at the top of reactor 9 to heat the hollow area, which facilitates the disassembly of the reaction pipe joints without the need to wrap the heating belt. It adopts the structure of furnace wire sintered fiber furnace and dual thermocouples for temperature control and display. The temperature measuring and display thermocouples are inserted into the catalyst from top to bottom, which has the advantages of high temperature resistance, good heating stability and temperature uniformity. The reactor 9 is equipped with a heat preservation box display module 6, a reaction temperature control module 7, and a reactor temperature control module 8. The reactor 9 has dimensions of 150mm (length) * 150mm (width) * 200mm (height). The reactor temperature is RT ~ 1200℃, and the constant temperature zone is ~ 40mm. The U-shaped quartz reaction tube 10 has an outer diameter of 8mm, an inner diameter of 6mm, and a height of 170mm. The distance between the centers of the two quartz tubes is 30mm. One side has a concave lower end and is equipped with stainless steel connectors at both ends. It adopts an O-ring soft sealing method. The catalyst loading is 1-5ml, and the temperature control precision of the heating jacket is < ±1℃.

[0033] In addition, the sulfur trioxide generating system 13 also includes thermocouples, and uses dual thermocouples for temperature control and display. The thermocouples have an outer diameter of 1.5 mm and a probe length of 400 mm.

[0034] In this embodiment, the gas dilution and mixing system 1 includes a gas source, a pressure reducing valve 2, and a standard gas dilution device. The two gas sources are connected to the standard gas dilution device through the pressure reducing valve 2 and corrosion-resistant pipelines, respectively. The standard gas dilution device includes a control module, a mass flow controller, a solenoid valve drive module, a power supply module, a communication module, and a display module. The flow rates of each gas are precisely adjusted by the control module according to the set concentration value and sent into the mixing chamber 4 for mixing via the solenoid valve 3. The dynamic gas distribution technology achieves precise control of the concentration and flow rate of the reactant gas, thereby achieving the purpose of preparing the target gas concentration. The gas sources are high-purity SO2 / N2 mixed gas sources, high-purity O2, NO2 or O3 gas sources, and high-purity N2 gas sources. The SO2 / N2 high-pressure mixed gas, O2, NO2 or O3 high-pressure gas, and N2 high-pressure gas can be directly connected to the input terminal of the standard gas dilution device. The flow rate of the gas is controlled by setting the concentration value through the parameter control module, realizing the mixing of SO2 and O2, NO2 or O3 in different proportions and at different concentrations and flow rates. The flow meter is calibrated, and the concentration of the mixed gas is accurately controllable. At this point, the gas dilution and mixing system 1 employs dynamic gas mixing technology. By adjusting the concentration and flow rate of the reactant gases, it achieves precise mixing of reactant gases in different proportions. Its measurement range is 1-10000 mL / min, and the relative expanded uncertainty is no greater than 0.5%. Specifically, in the high-purity SO2 / N2 mixed gas, the SO2 concentration is 100-1000 ppm, the O2 is high-purity oxygen, and the purity of the high-purity gas is no less than 99.999%.

[0035] The insulated vaporization system 14 includes insulated pipes and a three-way valve 12, maintaining a preset temperature throughout, ranging from 150-250℃. The inlet of the three-way valve 12 is connected to the outlet of the U-shaped quartz reaction tube 10, and the two outlets of the three-way valve 12 are connected to the detection system 15 and the collection and condensation system 19, respectively. By operating the three-way valve 12, the reaction products can be selectively introduced into the condenser or directly introduced into the detection system 15 for detection while in an insulated state (the pipeline is insulated throughout). Insulated pipes are connected between the outlet of the U-shaped quartz reaction tube 10 and the three-way valve 12, between the three-way valve 12 and the detection system 15, and between the three-way valve 12 and the collection and condensation system 19. Preferably, the three-way valve 12 uses FFKM sealing material, has 3mm compression fittings at both ends, withstands a pressure of 17.2MPa, and has a maximum operating temperature of 230℃.

[0036] In addition, the heat preservation vaporization system 14 also includes a filter 11, which is located at the inlet end of the three-way valve 12.

[0037] Specifically, the insulated pipe has a double-layer vacuum insulation sleeve structure, with a carbon steel pipe lined with polytetrafluoroethylene, which has extremely low surface adsorption energy and strong chemical inertness, effectively reducing gas adsorption and corrosion. The insulation temperature of the insulated pipe is 120-200℃, with a temperature control accuracy of <±1℃. The outer layer is covered with an aluminum silicate insulation layer, and the temperature uniformity of the inner wall of the pipeline is ≥95%.

[0038] The detection system 15 uses infrared absorption to detect SO2 and is calibrated with standard SO2 gas to ensure accuracy. After the SO2 detector reading stabilizes, a weighing experiment is conducted on the condenser. The condenser is initially weighed, and then weighed again after a stabilization period. The amount of sulfur trioxide collected is calculated by comparing the change in the condenser's weight. The condenser is designed with multi-stage temperature control and is equipped with an SO3 adsorption membrane to prevent SO3 gas escape. By monitoring the reduction in SO2 and combining theoretical calculations, the amount of SO3 produced can be estimated and compared with the actual collected SO3 mass to verify the efficiency and accuracy of the collection system. Furthermore, ion chromatography can be used for further quantitative analysis of the collected SO3, ensuring a high degree of accuracy in SO3 determination. The detection system 15 enables precise quantitative analysis of SO2 and SO3, ensuring the reliability of gas sampling and analysis results.

[0039] In this embodiment, the collection and condensation system 19 includes a multi-stage condensation device and a quantitative capture module. The multi-stage condensation device uses segmented temperature control technology to achieve rapid liquid solidification of sulfur trioxide, effectively improving collection efficiency and reducing secondary volatilization. The temperature control module can precisely adjust the condensation temperature of each stage, optimize the condensation behavior of SO3, and ensure product stability. The quantitative capture module performs high-precision determination of the sulfur trioxide content in the condensed product by weighing or ion chromatography. The system adopts a modular design and can be applied to SO3 capture needs under different working conditions. It has the advantages of simple operation, high recovery efficiency, and high measurement accuracy.

[0040] Specifically, the multi-stage condenser includes a first condenser tube 16, a second condenser tube 17, and a third condenser tube 18. All three tubes are serpentine condensers, with independent temperature control for each section. A sulfur trioxide adsorption film is installed at each outlet to prevent sulfur trioxide escape. Preferably, each condenser tube has a spiral diameter of 2cm, an inner diameter of 3mm, a length of 25cm, and a pitch of 1cm. The rear end connects to a condenser tank with a volume of 100ml, and is covered by a flexible insulation sleeve with a temperature range of -40℃ to RT.

[0041] Meanwhile, quartz wool with a particle size of 4μm is added to the tail ends of the first condenser tube 16, the second condenser tube 17 and the third condenser tube 18 to improve the separation efficiency of acid mist.

[0042] The sulfur trioxide gas standard generator of this embodiment 1 provides a high-precision, stable and reliable standard gas dilution and delivery scheme. It has the advantages of high automation, strong controllability of gas concentration and wide applicability. It can be widely used in industrial gas analysis and related research fields, and is particularly suitable for standardized metrology applications.

[0043] The sulfur trioxide gas standard generator of this embodiment 1 includes the following process when in use:

[0044] (1) Air tightness test:

[0045] In accordance with the requirements of the pressure test and leakage test of the pipeline system in the "Code for Construction and Acceptance of Steel Pipeline Engineering for Toxic and Flammable Media in Petrochemical Industry" (SH3501-2011), the airtightness of the equipment was checked, including the pipelines, joints, and valves.

[0046] (2) Gas mass flow meter calibration:

[0047] The gas mass flow meter included in the generating device was calibrated in accordance with the "Verification Procedure for Soap Film Flow Meters" (JJG586-2006).

[0048] (3) Calibration of SO2 and SO3 detection systems:

[0049] SO2 / N2 and O2 are connected to the inlet of the standard gas dilution device. The parameters such as the ratio, concentration and flow rate of the mixed gas at the outlet are controlled by adjusting the flow rate and the concentration of the reactant gas. The parameters and flow rate are set with reference to the concentration range of the sulfur trioxide generation system 13 and the concentration of sulfur dioxide to be detected. The outlet of the standard gas dilution device is connected to the SO2 and SO3 detection system 15 for spectral calibration.

[0050] (4) Catalyst preparation and drying:

[0051] A vanadium pentoxide catalyst and a silica support are combined. The vanadium pentoxide mass fraction is 10%, the particle size is 1mm, and the catalyst is mixed with quartz sand as a diluent. The volume ratio of catalyst to quartz sand is 1:3. The mixture is filled into a reaction tube and fixed with quartz wool. Under a nitrogen atmosphere, the temperature is increased to fully activate and dry the catalyst. The outlet end of the reaction tube is insulated and connected to a detection system 15 to detect the moisture content of the pipeline.

[0052] (5) Adjustment of reactant gas concentration and flow rate:

[0053] Ensure the entire apparatus is dry. Switch to N2 as the reaction gas. Connect SO2 / N2 and O2 to the inlet of the standard gas dilution device, where the SO2 / N2 concentration is 2000 ppm and the O2 is pure oxygen. Control the parameters such as the ratio, concentration, and flow rate of the SO2 / N2 and O2 mixed gas at the outlet by adjusting the reaction gas concentration on the control panel of the standard gas dilution device. For example, if the SO2 concentration at the outlet is 500 ppm, the total gas flow rate is 100 mL / min. A high-concentration 2000 ppm reaction gas SO2 can be used first to saturate the catalyst adsorption. Then, raise the reactor temperature to the reaction temperature of 500℃. Combined with the heat preservation vaporization system 14, the gas at the outlet of the reaction tube is fully vaporized until it reaches the detection system 15.

[0054] (6) SO3 setting and verification:

[0055] The detection system 15 calculates the SO2 concentration based on infrared absorption spectroscopy and is calibrated using standard SO2 gas. After calibration, the SO2 reading displayed by the analyzer is the SO2 concentration value after catalytic oxidation, from which the conversion rate and molar amount can be calculated. After the reaction stabilizes, the mass change of the condenser before and after a period of time is collected. The condenser uses multi-segment temperature control condensation and is equipped with an SO2 adsorption membrane to prevent SO3 escape. For ease of weighing, the three sections of the condenser are continuous and detachable. The amount of SO3 is verified by calibration using ion chromatography.

[0056] (7) SO3 tail gas absorption and emission:

[0057] To ensure complete treatment of the gas after the reaction, the outlet of the detection system 15 absorbs the gas after the reaction through an alkaline solution and then discharges it into the air, thoroughly removing residual SO2 and SO3 from the reaction gas and avoiding pollution or damage to the environment and equipment.

[0058] In practical application, the sulfur trioxide gas standard generator of Example 1 uses standard gases SO2 / N2 for analyzer calibration. High-purity SO2 / N2 and high-purity N2, with a purity of 99.999%, are connected to the inlet of the standard gas dilution device. The outlet of the standard gas dilution device is connected to the SO2 / SO3 detection system 15, controlling the outlet flow rate at 500 mL / min and the SO2 concentration at 200 ppm. The analyzer's spectral calibration is performed using the detected sulfur dioxide concentration as a reference.

[0059] A vanadium pentoxide catalyst and a silica support were combined, with vanadium pentoxide having a mass fraction of 10% and a particle size of 1 mm. Then, a cesium additive with a mass fraction of 1% was added, along with a diluent, quartz sand, and mixed. The volume ratio of catalyst to quartz sand was 1:3. The mixture was then filled into a reaction tube and fixed at both ends with quartz wool. Under a nitrogen atmosphere, the catalyst was fully activated and dried by raising the temperature to 200°C for 12 hours. The outlet end of the reaction tube was insulated and connected to a detection system 15 to detect the moisture content of the pipeline.

[0060] The catalyst is saturated with a high-concentration (5000 ppm) SO2 reaction gas. The inlets of the dilution device are then connected to SO2 / N2 and O3 reaction gases, respectively. The purity of SO2 / N2 is 99.999%, and the purity of O3 / N2 is 99.999%. The total flow rate after mixing is 1000 mL / min, and the SO2 concentration is 200 ppm. The mixed gas is then delivered to the quartz reaction tube in reactor 9 through the outlet. The reaction temperature is 300℃, and the sulfur trioxide is uniformly vaporized and fully mixed under a constant temperature environment (160℃) in the heat preservation vaporization system 14. A three-way valve 12 connects to a detection system 15 for real-time gas composition detection and to a condensation system. The condensation system is connected to the detection system 15 via a first condenser tube 16, a second condenser tube 17, and a third condenser tube 18. The outlet of the detection system 15 is connected to a tail gas absorption device to ensure safe emissions. The O3 reaction gas can be replaced with NO2 oxidizing gas. The reaction temperature is 300℃, and the heat preservation temperature is 150℃.

[0061] The detection system 15 calculates the SO2 concentration based on infrared absorption spectroscopy and is calibrated using standard SO2 gas. The SO2 reading displayed by the detection system 15 is the SO2 concentration value after catalytic oxidation, from which the conversion rate and molar amount can be calculated. After the reaction stabilizes, the mass change of the condenser tube before and after a period of time is collected. The condenser tube is three continuous and detachable sections, with its tail end connected to a condenser tank. The amount of SO3 is verified by calibrating the condenser tube and condenser tank based on the mass changes before and after the reaction, combined with ion chromatography. To ensure complete gas treatment after the reaction, the outlet of the detection system 15 absorbs the gas after the reaction through an alkaline solution before venting, thoroughly removing residual SO2 and SO3 from the reaction gas and avoiding pollution or damage to the environment and equipment.

[0062] Example 2

[0063] The sulfur trioxide gas standard generation method of this embodiment 2, using the aforementioned sulfur trioxide gas standard generation device, includes the following steps:

[0064] Two gas sources are pressure-stabilized by pressure reducing valve 2 and then enter the standard gas dilution device. The flow rate of each gas is precisely adjusted by the control module according to the set concentration value and mixed in the mixing chamber 4 to achieve dynamic preparation of the target gas concentration. The mixed gas is delivered to the U-shaped quartz reaction tube 10 in the reactor 9 through the outlet end of the mixing chamber 4 for reaction. After the reaction, the gas is evenly dispersed and fully mixed by the heat preservation vaporization system 14, and then enters the detection system 15 through the three-way valve 12 to realize real-time gas composition detection. The other one enters the collection and condensation system 19, which realizes the directional condensation and quantitative analysis of sulfur trioxide through segmented temperature control. The collection and condensation system 19 is connected to the detection system 15 through multi-stage condensation pipes. The outlet end of the detection system 15 is connected to the tail gas absorption system 20 to ensure safe emission.

[0065] This invention employs the principle of catalytic oxidation. Within a certain temperature range, sulfur dioxide, oxygen, nitrogen dioxide, or ozone undergo catalytic oxidation under the action of a catalyst to produce sulfur trioxide. Simultaneously, it utilizes composite particles of vanadium-based catalyst and silica support, with the addition of cesium additives. By optimizing reaction kinetics through temperature control, a high sulfur dioxide conversion rate of ≥90% is achieved with low catalyst loading, significantly reducing raw material costs. The U-shaped quartz reaction tube and segmented temperature-controlled condenser adopt a modular and detachable structure, enabling stable SO3 output and accurate quantification. It is applicable to both SO2 and NO2 or O3 reactions, allowing for multi-method verification of SO3 accuracy, and features easy maintenance and adaptability to various scenarios.

[0066] The sulfur trioxide gas standard generating device and generating method of the present invention can not only improve the shortcomings of existing sulfur trioxide gas detection technology, but also provide a broader market prospect for the promotion and application of sulfur trioxide gas monitoring instruments, and promote continuous innovation and technological progress in the environmental protection industry and related fields.

[0067] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A standard sulfur trioxide gas generator, characterized in that, The system includes a gas dilution and mixing system (1), a sulfur trioxide generating system (13), a heat preservation and vaporization system (14), a detection system (15), a collection and condensation system (19), and a tail gas absorption system (20). The gas dilution and mixing system (1) receives dual gas sources and can achieve precise control of the concentration and flow rate of the reactant gas. The outlet end of the gas dilution and mixing system (1) is connected to the sulfur trioxide generating system (13). The sulfur trioxide generating system (13) includes a reactor (9), a U-shaped quartz reaction tube (10), and a heater. The U-shaped quartz reaction tube (10) is installed in the reactor (9). The U-shaped quartz reaction tube (10) is filled with composite catalytic particles. The U-shaped quartz reaction tube (10) is covered with a heating jacket. The heating jacket is connected to a temperature controller. The heater is embedded in the hollow area at the top of the reactor (9). The outlet end of the U-shaped quartz reaction tube (10) is connected to the detection system (15) and the collection and condensation system (19) respectively through the heat preservation vaporization system (14). The output end of the collection and condensation system (19) is connected to the detection system (15). The output end of the detection system (15) is connected to the tail gas absorption system (20).

2. The sulfur trioxide gas standard generator according to claim 1, characterized in that, The composite catalytic particles are prepared by granulation process of vanadium-based catalyst, silica support and additives. The mass ratio of vanadium-based catalyst to silica support is 1:5-1:10 and the mass fraction of additives is 0.5%-3%.

3. The sulfur trioxide gas standard generator according to claim 2, characterized in that, The composite catalyst particles are filled by mixing the granulated catalyst particles with a diluent in a volume ratio of 1:1 to 1:3, and then preheating and drying them under a nitrogen atmosphere before reacting.

4. The sulfur trioxide gas standard generator according to claim 1, characterized in that, The gas dilution and mixing system (1) includes a gas source, a pressure reducing valve (2), and a standard gas dilution device. The two gas sources are respectively connected to the standard gas dilution device through the pressure reducing valve (2). The standard gas dilution device includes a control module, a mass flow controller, a solenoid valve drive module, a power supply module, a communication module, and a display module. The mass flow controller controls the flow rate of the reaction gas according to the concentration value set by the control module. Through dynamic gas mixing technology, the concentration and flow rate of the reaction gas are precisely controlled, thereby achieving the purpose of preparing the target gas concentration.

5. A sulfur trioxide gas standard generator according to claim 1, characterized in that, The heat-insulating vaporization system (14) includes heat-insulating pipes and a three-way valve (12). The inlet of the three-way valve (12) is connected to the outlet end of the U-shaped quartz reaction tube (10). The two outlets of the three-way valve (12) are respectively connected to the detection system (15) and the collection and condensation system (19). The heat-insulating pipes are respectively connected between the outlet end of the U-shaped quartz reaction tube (10) and the three-way valve (12), between the three-way valve (12) and the detection system (15), and between the three-way valve (12) and the collection and condensation system (19).

6. A sulfur trioxide gas standard generator according to claim 5, characterized in that, The insulated pipe has a double-layer vacuum insulation sleeve structure, with a carbon steel pipe lined with polytetrafluoroethylene and an outer layer covered with an aluminum silicate insulation layer.

7. A sulfur trioxide gas standard generating device according to any one of claims 1-6, characterized in that, The collection and condensation system (19) includes a multi-stage condensation device and a quantitative capture module. The multi-stage condensation device uses segmented temperature control technology to achieve rapid liquid solidification of sulfur trioxide. The quantitative capture module performs quantitative analysis of sulfur trioxide in the condensation products by weighing or ion chromatography.

8. A sulfur trioxide gas standard generator according to claim 7, characterized in that, The multi-stage condensation device includes a first condenser (16), a second condenser (17), and a third condenser (18). The first condenser (16), the second condenser (17), and the third condenser (18) are all serpentine condensers, and each section is independently temperature-controlled. A sulfur trioxide adsorption membrane is provided at each outlet end to prevent sulfur trioxide from escaping.

9. A sulfur trioxide gas standard generator according to claim 8, characterized in that, Quartz wool with a particle size of 4 μm is added to the tail ends of the first condenser (16), the second condenser (17) and the third condenser (18) to improve the separation efficiency of acid mist.

10. A method for generating a standard sulfur trioxide gas, characterized in that, The sulfur trioxide gas standard generator according to any one of claims 1-9 comprises the following steps: Two gas sources are pressure-stabilized by pressure reducing valve (2) and then enter the standard gas dilution device. The flow rate of each gas source is precisely adjusted by the control module according to the set concentration value and mixed in the mixing chamber (4) to achieve dynamic preparation of the target gas concentration. The mixed gas is transported to the U-shaped quartz reaction tube (10) in the reactor (9) through the outlet end of the mixing chamber (4) for reaction. After the reaction, the gas is evenly dispersed and fully mixed by the heat preservation vaporization system (14), and then enters the detection system (15) through the three-way valve (12) to realize real-time gas composition detection. The other one enters the collection and condensation system (19) to realize the directional condensation and quantitative analysis of sulfur trioxide through segmented temperature control. The collection and condensation system (19) is connected to the detection system (15) through multi-stage condensation pipes. The outlet end of the detection system (15) is connected to the tail gas absorption system (20) to ensure safe emission.

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