Novel sulfur trioxide preparation process suitable for sulfonation reaction

Abstract

The invention discloses a novel sulfur trioxide preparation process suitable for sulfonation reaction, and relates to the technical field of sulfur trioxide preparation, and the novel sulfur trioxide preparation process comprises the following steps: obtaining air separation oxygen and sulfur; feeding the air-separated oxygen and sulfur into an incinerator or a cracking furnace for reaction to generate sulfur dioxide; feeding sulfur dioxide into an isothermal reactor, and converting the sulfur dioxide into sulfur trioxide; cooling the sulfur trioxide to obtain industrial-grade sulfuric acid; industrial-grade sulfuric acid is conveyed to the sulfonation reaction unit to participate in sulfonation reaction; tail gas generated by sulfonation reaction is sent back to the incinerator or the cracking furnace, unreacted sulfur dioxide is recycled, and organic matter liquid drops are decomposed; the degassing equipment discharges non-condensable gas and moisture, and the non-condensable gas is discharged after being subjected to alkali washing by a sodium hydroxide solution. Redundant links such as air drying and electric demisting are omitted, the raw material utilization rate and product value are increased, energy consumption and environmental protection cost are reduced, and sulfonation reaction requirements can be stably met.

Description

Technical Field

[0001] This invention relates to the field of sulfur trioxide preparation technology, and more specifically, to a novel process for preparing sulfur trioxide suitable for sulfonation reactions. Background Technology

[0002] Sulfur trioxide is an indispensable core raw material in the industrial production of sulfonation reactions. Traditional sulfur trioxide preparation processes typically use sulfur and dry air as raw materials, burning them to generate sulfur dioxide, which is then converted into sulfur trioxide in a reactor. Finally, after condensation and dilution, it is sent to the sulfonation reaction unit. This process has long been used in the chemical production field. However, with increasingly stringent environmental requirements, greater pressure to control production costs, and higher demands for continuous production, its inherent process defects have gradually become apparent, making it difficult to meet the high-efficiency, economical, and environmentally friendly requirements of modern industrial production. Therefore, there is an urgent need to develop an optimized new process for sulfur trioxide preparation to solve the problems existing in traditional processes.

[0003] Traditional processes require a dedicated air drying stage to remove moisture from the air, which not only increases the initial investment cost of drying equipment but also incurs continuous consumable costs due to the need for regular desiccant replacement. Furthermore, downtime for drying system maintenance leads to production interruptions, affecting continuous capacity release and further increasing operating costs and production risks. In addition, the drying air used in traditional processes contains nitrogen and other impurities that cannot participate in the reaction, diluting the reaction system concentration and potentially interfering with the conversion of sulfur dioxide to sulfur trioxide. Moreover, insufficient air purity leads to incomplete sulfur combustion, resulting in raw material waste and reduced overall raw material utilization. Summary of the Invention

[0004] In order to overcome the above-mentioned defects of the prior art, the present invention provides a new process for preparing sulfur trioxide suitable for sulfonation reaction, so as to solve the problems mentioned in the background art.

[0005] This application provides a novel process for preparing sulfur trioxide suitable for sulfonation reactions, comprising the following steps:

[0006] S1: Obtain air separation of oxygen and sulfur;

[0007] S2: Air-separated oxygen and sulfur are fed into an incinerator or pyrolysis furnace to react and generate sulfur dioxide.

[0008] S3: Sulfur dioxide is fed into an isothermal reactor and converted into sulfur trioxide within the reactor;

[0009] S4: Sulfur trioxide is cooled to obtain industrial-grade sulfuric acid;

[0010] S5: Industrial-grade sulfuric acid is transported to the sulfonation reaction unit to participate in the sulfonation reaction;

[0011] S6: The tail gas produced by the sulfonation reaction is sent back to the incinerator or pyrolysis furnace. The organic droplets in the tail gas are burned and decomposed into carbon dioxide and water in the incinerator or pyrolysis furnace, and unreacted sulfur dioxide in the tail gas is recovered at the same time.

[0012] S7: The non-condensable gas and moisture accumulated in the circulation system are discharged through the degassing equipment. The non-condensable gas discharged from the degassing equipment is treated with alkaline washing and desulfurization before being discharged in compliance with standards.

[0013] In some embodiments of this application, the water content of the air-separated oxygen in step S1 is ≤0.1%.

[0014] In some embodiments of this application, the concentration of sulfur dioxide at the outlet of the incinerator or pyrolysis furnace in step S2 is controlled at 3% to 5%.

[0015] In some embodiments of this application, the feed ratio of sulfur and air separation oxygen in step S2 is controlled at 1:3 to 1:5.

[0016] In some embodiments of this application, the conversion temperature in step S3 is controlled at 420°C to 450°C.

[0017] In some embodiments of this application, the temperature of the cooling process in step S4 is controlled at 40°C to 60°C, and the cooling time is controlled at 30 minutes to 60 minutes.

[0018] In some embodiments of this application, the industrial-grade sulfuric acid obtained after cooling treatment in step S4 has a mass fraction ≥98%.

[0019] In some embodiments of this application, the delivery pressure of industrial-grade sulfuric acid into the sulfonation reaction unit in step S5 is controlled at 0.08 MPa to 0.12 MPa.

[0020] In some embodiments of this application, the combustion temperature of organic droplets in the exhaust gas in step S6 is controlled at 800°C to 1000°C.

[0021] In some embodiments of this application, the alkaline washing desulfurization treatment in step S7 uses a sodium hydroxide solution with a mass concentration of 15% to 20%, and the alkaline washing time is controlled to be 15 to 25 minutes.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] 1. By replacing the air in the traditional process with air-separated oxygen, the air drying step in the traditional process is eliminated. This not only reduces the initial investment in drying equipment and the cost of consumables such as desiccant replacement, but also avoids the loss of production capacity due to the downtime of the drying system for maintenance, ensuring the continuous and stable operation of the process and improving the overall production efficiency. At the same time, the purity of air-separated oxygen is higher than that of traditional dried air, which can prevent nitrogen, impurity gases and other gases from entering the reaction system, making the sulfur burn more completely and reducing the waste of raw materials caused by incomplete combustion.

[0024] 2. Replacing the multi-stage adiabatic converter used in the traditional process with an isothermal reactor improves the conversion efficiency of sulfur dioxide to sulfur trioxide, while reducing impurity generation and increasing the purity of sulfur trioxide and subsequent products.

[0025] 3. By adjusting the cooling process, nicotinic acid in the traditional process can be converted into industrial-grade sulfuric acid, which can be sold directly to generate additional revenue, improve the economic value of the product, and solve the problem of low product value in the traditional process.

[0026] 4. The tail gas recirculation system designed in this invention returns the sulfonation reaction tail gas to the incinerator, allowing unreacted sulfur dioxide to re-participate in the reaction, forming a closed-loop raw material cycle, improving raw material utilization and reducing raw material waste; at the same time, organic droplets in the tail gas decompose at high temperature, avoiding the accumulation of impurities that affect the reaction purity. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are only some embodiments recorded in this invention, and those skilled in the art can obtain other drawings based on these drawings.

[0028] Figure 1 This is a flow chart of the traditional sulfur trioxide preparation process;

[0029] Figure 2 The present invention provides a process flow diagram for the preparation of sulfur trioxide;

[0030] Figure 3 A comparison chart of energy consumption between the traditional process and the process of this invention;

[0031] Figure 4 A comparison chart of the cost structure of the traditional process and the process of this invention;

[0032] Figure 5 This is a comparison chart of the product benefits between the traditional process and the process of this invention;

[0033] Figure 6 Comparison chart of sulfur trioxide conversion rates in Examples 1-11 provided for this invention;

[0034] Figure 7 Comparison chart of sulfonated product qualification rates for Examples 1-11 provided by the present invention;

[0035] Figure 8 Comparison chart of sulfur dioxide concentration in exhaust gas after treatment in Examples 1-11 of this invention;

[0036] Figure 9 Comparison chart of energy consumption per ton of sulfur trioxide in Examples 1-11 provided by the present invention;

[0037] Figure 10 Comparison chart of unreacted sulfur dioxide recovery rates in Examples 1-11 provided by the present invention;

[0038] Figure 11 Comparison chart of sulfur trioxide conversion rates of Example 1 and Comparative Examples 1-3 provided by the present invention;

[0039] Figure 12 Comparison chart of sulfonated product qualification rates of Example 1 and Comparative Examples 1-3 provided for this invention;

[0040] Figure 13 Comparison chart of sulfur dioxide concentration in exhaust gas after treatment in Example 1 and Comparative Examples 1-3 provided for the present invention;

[0041] Figure 14 Comparison chart of energy consumption per ton of sulfur trioxide in Embodiment 1 and Comparative Examples 1-3 provided for this invention;

[0042] Figure 15 Comparison chart of unreacted sulfur dioxide recovery rates in Example 1, Comparative Examples 1-3 provided by the present invention. Detailed Implementation

[0043] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] To enable those skilled in the art to better understand the present application, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0045] See attached document Figure 1The traditional sulfur trioxide preparation process, which is associated with sulfonation reaction, uses sulfur and dry air as raw materials. It suffers from problems such as redundant processes, low product value, high environmental pressure, and high energy consumption.

[0046] Traditional processes require air pretreatment through drying to remove moisture and prevent equipment corrosion and reaction interference. However, the drying system requires regular replacement of the desiccant. Sulfur and dry air are then burned in an incinerator to generate sulfur dioxide at a concentration of 8%–11%. After waste heat recovery, this sulfur dioxide is fed into a traditional multi-stage adiabatic converter. This converter is affected by air impurities, resulting in significant fluctuations in conversion efficiency. It requires monthly maintenance, and the sulfur trioxide yield is only maintained at 98%–99%. After conversion, the 7%–11% sulfur trioxide gas is cooled and condensed to remove impurities, generating nicotinic acid. Nicotinic acid has very little market demand and high storage costs. Finally, dry air is added to dilute the sulfur trioxide concentration to 3%–5% before being fed into the sulfonation reaction unit. The sulfonation reaction tail gas contains unreacted sulfur dioxide and organic droplets, which must be removed by a dedicated electrostatic precipitator before alkaline desulfurization. The resulting desulfurization waste must be handled by a specialized company.

[0047] See attached document Figure 2 To address the problems of the aforementioned traditional processes, this application provides a novel process for preparing sulfur trioxide suitable for sulfonation reactions. Using air-separated oxygen and sulfur as raw materials, sulfur trioxide is prepared through pure oxygen combustion and flue gas recirculation. The specific steps include:

[0048] S1: Obtain air separation oxygen and sulfur. The water content of the air separation oxygen is ≤0.1%, and no additional drying treatment is required.

[0049] S2: Sulfur and air separation oxygen are fed into the incinerator at a mass ratio of 1:4. The temperature inside the incinerator is controlled at 850℃. Sulfur dioxide is generated by combustion, and the sulfur dioxide concentration at the outlet of the incinerator is stabilized at 3% to 5%.

[0050] S3: The sulfur dioxide generated in step S2 is fed into a novel isothermal reactor, and the temperature inside the reactor is controlled at 430℃ to achieve the conversion of sulfur dioxide to sulfur trioxide, with a conversion efficiency of 99.5%.

[0051] S4: Cool the sulfur trioxide generated in step S3, controlling the cooling temperature at 50°C and the cooling time at 45 minutes, to convert the sulfur trioxide into industrial-grade sulfuric acid with a mass fraction ≥98%.

[0052] S5: The industrial-grade sulfuric acid obtained in step S4 is fed into the sulfonation reaction unit at a conveying pressure of 0.1 MPa to participate in the sulfonation reaction and meet the sulfur trioxide requirements of the sulfonation reaction.

[0053] S6: The tail gas produced by the sulfonation reaction is sent back to the incinerator, where the organic droplets in the tail gas are burned and decomposed into carbon dioxide and water at 850°C. At the same time, unreacted sulfur dioxide in the tail gas is recovered, with a recovery efficiency of 95%.

[0054] S7: The non-condensable gases (mainly carbon dioxide) and moisture accumulated in the circulating system are discharged through the degassing equipment. The non-condensable gases are desulfurized by alkaline washing with a sodium hydroxide solution of 18% by mass for 20 minutes. After treatment, the sulfur dioxide concentration in the tail gas is ≤30mg / m³, which meets the emission standards.

[0055] The process described in this application differs from the traditional process, as shown in the table below:

[0056] Comparison Dimensions Traditional crafts The process of this invention Differences Process It includes three redundant processes: air drying, electrostatic precipitator, and alkaline desulfurization. Cancel the above 3 steps The equipment footprint has been reduced from 120 square meters in the traditional process to 84 square meters, a reduction of 30%; equipment maintenance workload has been reduced from 80 man-hours per month in the traditional process to 40 man-hours, a reduction of 50%. Raw material type Air (must be dry) + sulfur Air separation oxygen (water content ≤0.1%) + sulfur By eliminating the drying system, the purity of raw materials is improved, and the impurity content of sulfur trioxide products is reduced from 0.5% in the traditional process to 0.1%. core reactor Traditional multi-stage adiabatic converter Novel isothermal reactor The new reactor has an 80% higher conversion efficiency than the traditional converter (90% efficiency for the traditional converter, 99.5% efficiency for the new reactor); the maintenance cycle has been extended from once a month for the traditional process to once every three months. Product morphology Nicotinic acid (95% by mass) Industrial grade sulfuric acid (mass fraction ≥ 98%) The market price of nicotinic acid is -200 yuan / ton (discount required), while the market price of industrial-grade sulfuric acid is 800 yuan / ton, increasing the value of each ton of product by 1000 yuan. Exhaust gas treatment methods Electrostatic precipitator + alkaline desulfurization (generating desulfurization waste residue) Exhaust gas recirculation + degassing and alkaline washing (no solid waste) Traditional processes generate 5 tons of desulfurization waste residue per month, while the new process generates no solid waste; the workload for exhaust gas treatment is significantly reduced. Operating costs (tons of sulfur trioxide) higher lower The cost per ton has been significantly reduced, resulting in a clear cost advantage. Environmental compliance The desulfurization waste needs to be treated, and the sulfur dioxide concentration in the tail gas is 80 mg / m³. No solid waste, sulfur dioxide concentration in exhaust gas ≤30mg / m³ It meets the Class II standard (sulfur dioxide concentration ≤ 50 mg / m³) in GB16297-1996 "Integrated Emission Standard for Air Pollutants".

[0057] See attached document Figure 3 Regarding energy consumption: In the traditional process, the energy consumption of air drying is 300 kWh / ton, the energy consumption of electrostatic precipitator is 150 kWh / ton, the energy consumption of alkaline desulfurization is 100 kWh / ton, and the energy consumption of other processes is 450 kWh / ton, with a total energy consumption of 1000 kWh / ton; In the new process, there is no energy consumption in air drying, electrostatic precipitator, or alkaline desulfurization, and the energy consumption of other processes is 700 kWh / ton. The total energy consumption is reduced by 30% compared to the traditional process. When the annual production capacity is 10,000 tons, the annual electricity cost savings (calculated at 0.6 yuan / kWh) reach 180,000 yuan.

[0058] See attached document Figure 4 In terms of cost structure: In the traditional process, drying consumables account for 8%, electricity cost for electrostatic precipitator accounts for 5%, desulfurization agent and waste residue treatment accounts for 18%, raw material cost accounts for 50%, and other costs account for 19%; In the new process, raw material cost accounts for 75%, alkaline washing desulfurization cost accounts for 3%, and other costs account for 22%. There are no costs for drying consumables, electricity cost for electrostatic precipitator, or desulfurization waste residue treatment. The cost structure is more optimized and the ability to resist market fluctuations is stronger.

[0059] See attached document Figure 5 In terms of product revenue: the price of nicotinic acid remained in the range of -200 yuan / ton to -150 yuan / ton throughout the year, with no obvious upward trend; the price of industrial grade sulfuric acid remained in the range of 750 yuan / ton to 850 yuan / ton throughout the year, with an average price 1,000 yuan / ton higher than that of nicotinic acid, and the quarterly price fluctuation range was only 5%, with revenue stability significantly better than that of nicotinic acid.

[0060] Compared with traditional processes, the new process in this application has the following improvements:

[0061] 1. The process is streamlined, eliminating three redundant steps: air drying, electrostatic precipitator, and alkaline desulfurization. This significantly reduces equipment investment and lowers maintenance workload and costs.

[0062] 2. Product value-added: Converting nicotinic acid, which is difficult to monetize, into high-demand industrial-grade sulfuric acid. Based on an annual production capacity of 10,000 tons of sulfur trioxide (converted to sulfuric acid), the annual additional revenue will increase by 8 million yuan.

[0063] 3. Environmental upgrade, no solid waste generated, significantly reduced exhaust gas treatment pressure, meets the latest environmental standards, and avoids secondary pollution;

[0064] 4. Reduced energy consumption: Total energy consumption is reduced by 30% compared to traditional processes. At the same time, system stability is improved, and the product qualification rate of sulfonation reaction increases from 95% in traditional processes to 98%, reducing the loss of defective products.

[0065] For sulfonation reaction production lines, the embodiments of this application can ensure a stable supply of 4% sulfur trioxide, reduce reaction abnormalities caused by fluctuations in raw material concentration, and significantly reduce the overall cost of the production line. In terms of market promotion, it is suitable for chemical enterprises that require sulfur trioxide, such as sulfonation reaction and sulfuric acid production, with a short investment payback period and both environmental and economic benefits.

[0066] In the future, the cost of oxygen for air separation can be further reduced by building its own air separation equipment; at the same time, the degassing system will be upgraded to be automated, and a PLC control system will be used to automatically match the non-condensable gas emission with the alkaline washing desulfurization parameters, reducing manual operation and achieving unattended operation.

[0067] The process of this application will be described in detail below with reference to specific embodiments.

[0068] Example 1

[0069] The new process for preparing sulfur trioxide suitable for sulfonation reaction provided in Example 1 has the following specific steps:

[0070] Raw material preparation: Obtain 250 kg of industrial-grade sulfur with a moisture content of 0.08% and 1000 kg of air separation oxygen (mass ratio 1:4).

[0071] Sulfur dioxide generation: Oxygen and sulfur are fed into the incinerator, and the furnace temperature is controlled at 850℃. Sulfur dioxide is generated by combustion, and the sulfur dioxide concentration at the incinerator outlet is measured to be 4%.

[0072] Sulfur trioxide conversion: Sulfur dioxide was fed into a novel isothermal reactor, the reactor temperature was controlled at 430℃, and the reaction was carried out for 2 hours. The sulfur trioxide conversion rate was 99.5% after sampling and testing.

[0073] Sulfuric acid preparation: Sulfur trioxide was cooled at a controlled temperature of 50°C for 45 minutes to obtain 1200 kg of industrial-grade sulfuric acid with a mass fraction of 98.5%.

[0074] Sulfonation reaction: Industrial-grade sulfuric acid is fed into the sulfonation reaction unit at a conveying pressure of 0.1 MPa to participate in the sulfonation reaction. After the reaction, the pass rate of the sulfonated products is 98.2%.

[0075] Tail gas recirculation: The tail gas from the sulfonation reaction is returned to the incinerator. The combustion and decomposition rate of organic droplets in the tail gas is 100%, and the recovery rate of unreacted sulfur dioxide is 95%.

[0076] Degassing and emission: 200 kg of non-condensable gas and 50 kg of water are discharged through the degassing equipment. The non-condensable gas is then washed with an 18% sodium hydroxide solution for 20 minutes. After treatment, the sulfur dioxide concentration in the tail gas is 28 mg / m³, which meets the emission standards.

[0077] Statistical analysis of the process operation data of Example 1 shows that the energy consumption per ton of sulfur trioxide (converted to sulfuric acid) is 700 kWh, which is 30% lower than that of traditional processes, and no solid waste is generated, which meets the requirements of sulfonation reaction production lines for high efficiency, economy and environmental protection.

[0078] Example 2

[0079] Example 2 follows essentially the same process steps as Example 1, with the only difference being that the feed ratio of sulfur to oxygen in step S2 is 1:3. Specific operating results: the sulfur dioxide concentration at the incinerator outlet was 3.2%, the sulfur trioxide conversion rate was 99.2%, the sulfonated product qualification rate was 97.8%, the unreacted sulfur dioxide recovery rate in the tail gas was 94%, and the sulfur dioxide concentration in the treated tail gas was 30 mg / m³.

[0080] Example 3

[0081] Example 3 follows essentially the same process steps as Example 1, with the only difference being that the feed ratio of sulfur to oxygen in step S2 is 1:5. Specific operating results: the sulfur dioxide concentration at the incinerator outlet was 4.8%, the sulfur trioxide conversion rate was 99.6%, the sulfonated product qualification rate was 98.3%, the unreacted sulfur dioxide recovery rate in the tail gas was 96%, and the sulfur dioxide concentration in the treated tail gas was 27 mg / m³.

[0082] Example 4

[0083] Example 4 follows essentially the same process steps as Example 1, with the only difference being that the conversion temperature of the isothermal reactor in step S3 is 420℃. Specific operating results: sulfur trioxide conversion rate was 99.0%, sulfonated product qualification rate was 97.5%, and the sulfur dioxide concentration in the treated tail gas was 31 mg / m³.

[0084] Example 5

[0085] Example 5 follows essentially the same process steps as Example 1, with the only difference being that the conversion temperature of the isothermal reactor in step S3 is 450℃. Specific operating results: sulfur trioxide conversion rate was 99.7%, sulfonated product qualification rate was 98.5%, and the sulfur dioxide concentration in the treated tail gas was 26 mg / m³.

[0086] Example 6

[0087] The process steps of Example 6 are basically the same as those of Example 1, with the only difference being that the cooling temperature in step S4 is 40°C and the cooling time is 30 minutes. Specific operating results: the industrial-grade sulfuric acid mass fraction is 98.1%, the sulfonation product qualification rate is 97.6%, and the sulfur dioxide concentration in the treated tail gas is 29 mg / m³.

[0088] Example 7

[0089] The process steps of Example 7 are basically the same as those of Example 1, with the only difference being that the cooling temperature in step S4 is 60°C and the cooling time is 60 minutes. Specific operating results: the industrial-grade sulfuric acid mass fraction is 98.7%, the sulfonation product qualification rate is 98.4%, and the sulfur dioxide concentration in the treated tail gas is 25 mg / m³.

[0090] Example 8

[0091] The process steps in Example 8 are basically the same as those in Example 1, with the only difference being that the conveying pressure in step S5 is 0.08 MPa. Specific operational results: the sulfonated product qualification rate was 97.7%, there was no leakage during the industrial-grade sulfuric acid conveying process, and the system showed good stability.

[0092] Example 9

[0093] Example 9 follows essentially the same process steps as Example 1, with the only difference being that the conveying pressure in step S5 is 0.12 MPa. Specific operational results: the sulfonated product qualification rate was 98.6%, the conveying efficiency of industrial-grade sulfuric acid was improved, and there were no abnormal pressure fluctuations in the system.

[0094] Example 10

[0095] Example 10 follows essentially the same process steps as Example 1, with the only difference being the use of a 15% sodium hydroxide solution in step S7 and an alkaline washing time of 15 minutes. Specific operational results: The sulfur dioxide concentration in the treated exhaust gas was 32 mg / m³, meeting environmental emission standards, and no excessive waste liquid was generated during the alkaline washing process.

[0096] Example 11

[0097] Example 11 follows essentially the same process steps as Example 1, with the only difference being the use of a 20% sodium hydroxide solution in step S7 and an alkaline washing time of 25 minutes. Specific operational results: The sulfur dioxide concentration in the treated tail gas was 24 mg / m³, demonstrating excellent desulfurization performance and no waste of sodium hydroxide.

[0098] Comparative Example 1

[0099] Comparative Example 1 uses a traditional sulfur trioxide preparation process, with the following specific steps:

[0100] Air drying: Air is dried by passing it through a drying system to remove moisture.

[0101] Sulfur dioxide generation: Dry air and sulfur are fed into the incinerator at a ratio of 1:5 and burned to generate sulfur dioxide with a concentration of 9%.

[0102] Sulfur trioxide conversion: Sulfur dioxide is fed into a traditional multi-stage adiabatic converter, and the temperature fluctuation is controlled within 420℃-450℃, with a sulfur trioxide conversion rate of 90%.

[0103] Condensation treatment: Sulfur trioxide is condensed to produce nicotinic acid with a mass fraction of 95%;

[0104] Dilution and delivery: Nicotinic acid is diluted to a concentration of 4% and then sent to the sulfonation reaction unit;

[0105] Exhaust gas treatment: Organic liquid droplets in the exhaust gas are removed by an electrostatic precipitator, followed by alkaline desulfurization, producing desulfurization waste residue;

[0106] Emissions: The sulfur dioxide concentration in the treated exhaust gas is 80 mg / m³, meeting emission standards. Operational results: Energy consumption per ton of sulfur trioxide is 1000 kWh, the sulfonation product qualification rate is 95%, 5 tons of desulfurization waste residue are generated per month, and nicotinic acid needs to be disposed of at a discount.

[0107] Comparative Example 2

[0108] The process steps of Comparative Example 2 are basically the same as those of Example 1, the only difference being that the tail gas recirculation in step S6 is not set, and the sulfonation reaction tail gas is directly discharged after alkaline washing and desulfurization. Specific operating results: the recovery rate of unreacted sulfur dioxide is 0, the amount of tail gas to be treated increases by 60% compared with Example 1, the sulfur dioxide concentration in the treated tail gas is 45 mg / m³, the energy consumption per ton of sulfur trioxide increases to 780 kWh, and the qualification rate of sulfonated products is 96.0%.

[0109] Comparative Example 3

[0110] The process steps of Comparative Example 3 and Example 1 are basically the same, the only difference being that a traditional multi-stage adiabatic converter is used instead of the new isothermal reactor in step S3. Specific operating results: sulfur trioxide conversion rate was 90%, temperature fluctuation during conversion was ±10℃, sulfonated product qualification rate was 95.5%, sulfur dioxide concentration in the treated tail gas was 40 mg / m³, and energy consumption per ton of sulfur trioxide increased to 750 kWh.

[0111] The key performance indicators of Examples 1-11 and Comparative Examples 1-3 were tested, and the results are shown in the table below:

[0112] Serial Number Process type Sulfur trioxide conversion rate (%) Qualification rate of sulfonated products (%) Sulfur dioxide concentration in the treated exhaust gas (mg / m³) Energy consumption per ton of sulfur trioxide (kWh) Unreacted sulfur dioxide recovery rate (%) Does it generate solid waste? Example 1 New process (1:4 feed ratio) 99.5 98.2 28 700 95 no Example 2 New process (1:3 feed ratio) 99.2 97.8 30 705 94 no Example 3 New process (1:5 feed ratio) 99.6 98.3 27 695 96 no Example 4 New process (420℃ conversion) 99.0 97.5 31 710 95 no Example 5 New process (450℃ conversion) 99.7 98.5 26 690 95 no Example 6 New process (cooling at 40℃) 99.5 97.6 29 702 95 no Example 7 New process (cooling at 60℃) 99.5 98.4 25 698 95 no Example 8 New process (0.08MPa conveying) 99.5 97.7 28 700 95 no Example 9 New process (0.12MPa conveying) 99.5 98.6 28 699 95 no Example 10 New process (15% alkali solution) 99.5 98.2 32 700 95 no Example 11 New process (20% alkali solution) 99.5 98.2 24 700 95 no Comparative Example 1 Traditional crafts 90.0 95.0 80 1000 0 yes Comparative Example 2 No exhaust gas recirculation 99.5 96.0 45 780 0 no Comparative Example 3 Traditional converter 90.0 95.5 40 750 95 no

[0113] The following conclusions can be drawn from the above data comparison:

[0114] Examples 1-11 all employed the novel process of this application, and all performance indicators were superior to those of Comparative Examples 1-3. Specifically, the sulfur trioxide conversion rate was 9.0%-9.7% higher than that of Comparative Examples 1 and 3 using traditional processes; the sulfonated product qualification rate was increased by 2.2%-3.6%; the sulfur dioxide concentration in the treated tail gas was reduced by 48 mg / m³-56 mg / m³; energy consumption per ton of sulfur trioxide was reduced by 220 kWh-310 kWh; no solid waste was generated; and the unreacted sulfur dioxide recovery rate reached 94%-96%, significantly improving resource utilization.

[0115] Examples 1-3 show that when the feed ratio of sulfur and air separation oxygen is in the range of 1:3 to 1:5, a high reaction rate and product qualification rate can be guaranteed. Among them, the sulfur trioxide conversion rate and tail gas treatment effect are the best when the feed ratio is 1:5, and the overall performance is more balanced when the feed ratio is 1:4, which is suitable for large-scale industrial production.

[0116] Examples 4 and 5 show that the conversion temperature of the isothermal reactor is in the range of 420℃ to 450℃. The higher the temperature, the higher the conversion rate of sulfur trioxide, and the higher the qualification rate of sulfonated products. At the same time, the energy consumption is slightly reduced, indicating that this temperature range can give full play to the performance advantages of the new isothermal reactor.

[0117] Examples 6 and 7 show that industrial-grade sulfuric acid with a mass fraction ≥98% can be prepared when the cooling temperature is between 40°C and 60°C and the cooling time is between 30 minutes and 60 minutes. Among them, the sulfuric acid mass fraction is the highest under the cooling conditions of 60°C and 60 minutes, and the promoting effect on the subsequent sulfonation reaction is more obvious.

[0118] Examples 8 and 9 show that the system operates stably without abnormal fluctuations when the conveying pressure is in the range of 0.08MPa to 0.12MPa. The higher the pressure, the slightly higher the pass rate of sulfonated products. The pressure can be flexibly adjusted according to the actual conveying distance and equipment load capacity in production.

[0119] Examples 10-11 show that sodium hydroxide solution concentrations of 15%-20% and alkaline washing times of 15-25 minutes can meet the requirements for tail gas desulfurization. Among them, a 20% concentration and a 25-minute alkaline washing time result in the best desulfurization effect, while the combination of an 18% concentration and a 20-minute washing time can control the cost of alkaline solution consumption while ensuring the desulfurization effect, making it a better parameter selection.

[0120] The comparison between Comparative Example 2 and Example 1 shows that the exhaust gas recirculation process is the key to improving resource utilization, reducing energy consumption and exhaust gas treatment pressure. After the process is eliminated, not only is all the unreacted sulfur dioxide lost, but the amount of exhaust gas treated also increases significantly, energy consumption rises, and product qualification rate decreases.

[0121] The comparison between Comparative Example 3 and Example 1 highlights the advantages of the isothermal reactor in the present application. Traditional multi-stage adiabatic converters are affected by temperature fluctuations and air impurities, resulting in lower conversion efficiency than isothermal reactors, which leads to increased energy consumption and decreased product qualification rate. This further proves the necessity of upgrading the core equipment in the process of the present application.

[0122] In summary, the novel sulfur trioxide preparation process applicable to sulfonation reactions proposed in this application demonstrates advantages in reaction efficiency, product quality, environmental performance, and energy consumption control through reasonable setting of process parameters and optimization of core equipment and process design. It is particularly suitable for sulfonation reaction production lines with high requirements for sulfur trioxide supply stability and environmental protection, and has broad prospects for industrial application.

[0123] In conclusion, the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A novel process for preparing sulfur trioxide suitable for sulfonation reactions, characterized in that, Includes the following steps: S1: Obtain air separation of oxygen and sulfur; S2: Air-separated oxygen and sulfur are fed into an incinerator or pyrolysis furnace to react and generate sulfur dioxide. S3: Sulfur dioxide is fed into an isothermal reactor and converted into sulfur trioxide within the reactor; S4: Sulfur trioxide is cooled to obtain industrial-grade sulfuric acid; S5: Industrial-grade sulfuric acid is transported to the sulfonation reaction unit to participate in the sulfonation reaction; S6: The tail gas produced by the sulfonation reaction is sent back to the incinerator or pyrolysis furnace. The organic droplets in the tail gas are burned and decomposed into carbon dioxide and water in the incinerator or pyrolysis furnace, and unreacted sulfur dioxide in the tail gas is recovered at the same time. S7: The non-condensable gas and moisture accumulated in the circulation system are discharged through the degassing equipment. The non-condensable gas discharged from the degassing equipment is treated with alkaline washing and desulfurization before being discharged in compliance with standards.

2. The novel process for preparing sulfur trioxide suitable for sulfonation reaction according to claim 1, characterized in that, The water content of the oxygen in step S1 is ≤0.1%.

3. The novel process for preparing sulfur trioxide suitable for sulfonation reaction according to claim 1, characterized in that, In step S2, the concentration of sulfur dioxide at the outlet of the incinerator or pyrolysis furnace is controlled at 3% to 5%.

4. The novel process for preparing sulfur trioxide suitable for sulfonation reaction according to claim 1, characterized in that, In step S2, the feed ratio of sulfur and air separation oxygen is controlled at 1:3 to 1:

5.

5. A novel process for preparing sulfur trioxide suitable for sulfonation reaction according to claim 1, characterized in that, In step S3, the conversion temperature is controlled at 420℃~450℃.

6. A novel process for preparing sulfur trioxide suitable for sulfonation reaction according to claim 1, characterized in that, In step S4, the temperature of the cooling process is controlled at 40℃~60℃, and the cooling time is controlled at 30 minutes~60 minutes.

7. A novel process for preparing sulfur trioxide suitable for sulfonation reaction according to claim 1, characterized in that, The industrial-grade sulfuric acid obtained after cooling treatment in step S4 has a mass fraction ≥98%.

8. A novel process for preparing sulfur trioxide suitable for sulfonation reaction according to claim 1, characterized in that, In step S5, the delivery pressure of the industrial-grade sulfuric acid into the sulfonation reaction unit is controlled at 0.08 MPa to 0.12 MPa.

9. A novel process for preparing sulfur trioxide suitable for sulfonation reaction according to claim 1, characterized in that, In step S6, the combustion temperature of the organic droplets in the exhaust gas is controlled at 800℃~1000℃.

10. A novel process for preparing sulfur trioxide suitable for sulfonation reaction according to claim 1, characterized in that, The alkaline washing desulfurization treatment in step S7 uses a sodium hydroxide solution with a mass concentration of 15% to 20%, and the alkaline washing time is controlled between 15 and 25 minutes.

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