A neutralization and acidification device for p-cresol production

Abstract

The utility model relates to the technical field of chemical production, concretely relates to a neutralization acidification device for p-methyl phenol production, including neutralization reation kettle, the upper portion of neutralization reation kettle is equipped with tail gas outlet, tail gas outlet passes through tail gas conveying pipeline and communicates with acidifier, is equipped with tail gas collection system on tail gas conveying pipeline, and tail gas collection system includes tail gas collection pipeline, and one end of tail gas collection pipeline communicates branch of tail gas conveying pipeline, and the other end of tail gas collection pipeline is connected with the air inlet of roots blower, and the air outlet of roots blower is communicated with gas drying system through booster gas pipeline, and the outlet of gas drying system is connected with sulfuric acid production system;Sulfuric acid production system passes through sulfuric acid conveying pipeline and communicates with the acidification inlet of acidifier.The device can effectively collect and recycle surplus sulfur dioxide gas in the neutralization reaction process, realize its reuse in the acidification reaction or byproduct conversion link, reduce the consumption of flake caustic soda, improve the economy and clean level of p-methyl phenol production.

Description

Technical Field

[0001] This utility model relates to the field of chemical production technology, specifically to a neutralization and acidification device for the production of p-methylphenol. Background Technology

[0002] p-Cresol is an important fine chemical intermediate, widely used in the synthesis of pharmaceuticals, pesticides, fragrances, dyes, antioxidants, polymerization inhibitors, ultraviolet absorbers, fuel additives, and rubber additives, and is a crucial raw material for the fine chemical industry. The main synthetic methods for p-cresol include the toluene sulfonation alkali fusion method, the phenol methylation method, the isopropyltoluene method, and the p-toluidine method. In China, the toluene sulfonation alkali fusion method is commonly used for industrial production of p-cresol. This process includes sulfonation, neutralization, alkali fusion, acidification, and distillation. First, toluene is sulfonated to obtain p-toluenesulfonic acid, which is then neutralized to produce sodium p-toluenesulfonate. Sodium p-toluenesulfonate and sodium hydroxide are then heated and melted together to produce sodium p-cresol, which is subsequently acidified to obtain crude p-cresol. Finally, distillation yields p-cresol.

[0003] During the neutralization stage, excess sulfur dioxide is generated during the reaction of p-toluenesulfonic acid and sodium sulfite to produce sodium p-toluenesulfonate. This excess sulfur dioxide is typically neutralized by adding caustic soda flakes, producing sodium sulfite. This neutralization method not only results in significant consumption of caustic soda flakes, increasing production costs, but also causes large fluctuations in system alkalinity, affecting the stability of subsequent alkali fusion and acidification reactions. Utility Model Content

[0004] To address the technical problems of high caustic soda consumption and high production costs caused by excess sulfur dioxide generated during the neutralization stage in existing p-cresol production processes, this invention provides a neutralization and acidification device for p-cresol production. This device can effectively collect and recycle excess sulfur dioxide gas during the neutralization reaction, enabling its reuse in acidification reactions or by-product conversion stages. This significantly reduces caustic soda consumption and improves the overall economic efficiency and cleanliness of p-cresol production.

[0005] The specific technical solution is as follows: A neutralization and acidification device for the production of p-methylphenol includes a neutralization reactor with a tail gas outlet at the top. The tail gas outlet is connected to an acidifier via a tail gas conveying pipe. A tail gas collection system is provided on the tail gas conveying pipe, which includes a tail gas collection pipe. One end of the tail gas collection pipe is connected to a branch of the tail gas conveying pipe, and the other end of the tail gas collection pipe is connected to the inlet of a Roots blower. The outlet of the Roots blower is connected to a gas drying system via a pressurized gas pipe. The outlet of the gas drying system is connected to a sulfuric acid production system. The sulfuric acid production system is connected to the acidification inlet of the acidifier via a sulfuric acid conveying pipe.

[0006] The aforementioned device, through the present invention, achieves the effective collection and reuse of sulfur dioxide in the neutralization tail gas by setting up a tail gas collection system, a gas drying system, and a sulfuric acid production system between the neutralization reactor and the acidifier. Excess sulfur dioxide generated during the neutralization stage enters the tail gas collection system via a tail gas conveying pipeline, is pressurized by a Roots blower, and then sent to the gas drying system for dehumidification. It is then introduced into the sulfuric acid production system to be converted into sulfuric acid. The resulting sulfuric acid is returned to the acidifier via a conveying pipeline for subsequent acidification reactions.

[0007] Furthermore, the acidifier has a first air inlet at the top and a second air inlet at the bottom. The exhaust gas delivery pipe has a first branch pipe and a second branch pipe at its end. The first branch pipe is connected to the first air inlet, and the second branch pipe is connected to the second air inlet. By providing independent air inlets at the top and bottom of the acidifier, and supplying gas separately through branch pipes of the exhaust gas delivery pipe, stratified distribution and thorough mixing of the gas within the acidifier can be achieved. This promotes uniform acidification reaction and avoids problems such as airflow deviation and incomplete local reactions caused by a single air inlet, thereby improving acidification efficiency and product purity.

[0008] Furthermore, a Venturi metering valve is installed on the first branch pipe, and a circulation pump is installed on the second branch pipe. By installing a Venturi metering valve on the upper branch pipe, the flow rate of the exhaust gas entering the upper air inlet can be precisely controlled, achieving quantitative control of the distribution ratio of the acidification reaction gas; the circulation pump installed on the lower branch pipe can enhance the gas flow and mixing intensity in the lower part, promote the contact and mass transfer between the reaction liquid and the gas, and improve the acidification reaction rate and the overall stability of the system.

[0009] Furthermore, the gas drying system includes a concentrated sulfuric acid drying tower. The lower part of the drying tower has an inlet connected to a pressurized gas pipeline, and the upper part has an outlet connected to the feed inlet of the sulfuric acid production system via a drying gas channel. By incorporating a concentrated sulfuric acid drying tower into the gas drying system, the strong dehydrating properties of concentrated sulfuric acid are utilized to dry and dehumidify the pressurized gas, effectively removing water vapor and trace impurities from the exhaust gas and ensuring stable reaction conditions in the sulfuric acid production process.

[0010] Furthermore, the exhaust outlet is connected to the exhaust gas delivery pipeline through a condenser. The condenser uses circulating water for condensation, which is used to cool and separate the neutralized exhaust gas, removing water vapor and condensable components, making the exhaust gas composition entering the exhaust gas delivery pipeline more stable.

[0011] Furthermore, the pressurized gas pipeline is connected to a compressed air pipeline, which is equipped with a ball valve. By connecting the compressed air pipeline to the pressurized gas pipeline, compressed air can be supplemented as needed during system operation to adjust the gas ratio and pressure in the exhaust gas, enhancing the stability and controllability of the airflow. This ensures that the gas entering the gas drying system and sulfuric acid production system has a constant flow rate and pressure, improving the reliability of system operation and the controllability of the reaction process.

[0012] Furthermore, the pressurized gas pipeline is equipped with a gas flow meter, a temperature measuring meter, and a pressure measuring meter to detect the gas flow, temperature, and pressure, monitor the gas operating status in real time, and achieve precise control and dynamic adjustment of the system operating status. This helps to prevent abnormal gas flow, excessively high temperature, or pressure fluctuations from causing instability to the subsequent sulfuric acid production system, thereby improving the safety of system operation.

[0013] Furthermore, a check valve is installed on the pressurized gas pipeline to prevent gas backflow when the Roots blower trips, effectively improving the safety and stability of the device and extending the service life of the blower and pipeline components.

[0014] Furthermore, the exhaust gas collection pipe is equipped with a PTFE-lined ball valve, which has a polytetrafluoroethylene (PTFE) lining structure and excellent resistance to acid and alkali corrosion. It is used to cut off the gas passage when the equipment is under maintenance or malfunctions.

[0015] The beneficial effects of this utility model are as follows: By incorporating a tail gas collection system, a gas drying system, and a sulfuric acid production system between the neutralization reactor and the acidifier, a closed-loop recycling path for sulfur dioxide tail gas was constructed, achieving efficient recovery and resource reuse of sulfur dioxide in the tail gas during the neutralization stage. The tail gas, pressurized by a Roots blower, enters a concentrated sulfuric acid drying tower for deep dehumidification, and is then introduced into the sulfuric acid production system to generate sulfuric acid. The resulting sulfuric acid is returned to the acidifier as a reaction feedstock, reducing the consumption of caustic soda flakes and purchased sulfuric acid, significantly improving the resource utilization rate and economic efficiency of the production process, while simultaneously reducing sulfur dioxide emissions and environmental pollution, demonstrating significant energy conservation, emission reduction, and green manufacturing effects. The overall unit features a compact structure, strong functional linkage, and high control precision, ensuring both the stability of continuous production and the safety and environmental friendliness of the system. Attached Figure Description

[0016] To more clearly illustrate the technical solution of this utility model, the drawings used in the description will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the neutralization and acidification device for the production of p-methylphenol according to this utility model.

[0018] The components include: 1. Neutralization reactor; 11. Tail gas outlet; 2. Condenser; 3. Tail gas conveying pipeline; 31. First branch pipe; 311. Venturi metering valve; 32. Second branch pipe; 321. Circulating pump; 4. Tail gas collection system; 41. Tail gas collection pipeline; 411. PTFE-lined ball valve; 42. Roots blower; 43. Pressurized gas pipeline; 431. Gas flow meter; 432. Thermometer; 433. Pressure gauge; 434. Check valve; 5. Concentrated sulfuric acid drying tower; 51. Gas inlet; 52. Gas outlet; 53. Drying gas pipeline; 6. Sulfuric acid production system; 61. Sulfuric acid conveying pipeline; 7. Acidifier; 71. Acidification inlet; 72. First air inlet; 73. Second air inlet; 8. Compressed air pipeline; 81. Ball valve. Detailed Implementation

[0019] To make the objectives, features, and advantages of this utility model more apparent and understandable, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings of the specific embodiments. Obviously, the embodiments described below are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this patent, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this patent.

[0020] Example 1: A neutralization and acidification device for the production of p-methylphenol The device includes a neutralization reactor 1, with a tail gas outlet 11 at its upper part. The tail gas outlet 11 is connected to a tail gas delivery pipeline 3 via a condenser 2. The condenser 2 uses circulating water as the cooling medium to condense and dehumidify the neutralized tail gas, making the tail gas composition entering the tail gas delivery pipeline 3 more stable. A tail gas collection system 4 is connected to the middle of the tail gas delivery pipeline 3. The tail gas collection system 4 includes a tail gas collection pipe 41, one end of which is connected to a branch of the tail gas delivery pipeline 3, and the other end of which is connected to the air inlet of a Roots blower 42. A PTFE-lined ball valve 411 is installed on the tail gas collection pipe 41, with a PTFE lining structure. The air outlet of the Roots blower 42 is connected to a gas drying system via a pressurized gas pipeline 43.

[0021] The gas drying system includes a concentrated sulfuric acid drying tower 5. The lower part of the concentrated sulfuric acid drying tower 5 has an inlet 51, which is connected to a pressurized gas pipeline 43. The upper part of the concentrated sulfuric acid drying tower 5 has an outlet 52, which is connected to the feed inlet of the sulfuric acid production system 6 through a drying gas channel. The output end of the sulfuric acid production system 6 is connected to the acidification inlet 71 of the acidifier 7 through a sulfuric acid conveying pipeline 61, forming a loop for tail gas conversion and acidification reaction.

[0022] The acidifier 7 has a first air inlet 72 at the top and a second air inlet 73 at the bottom. The exhaust gas delivery pipe 33 has a first branch pipe 31 and a second branch pipe 32 at the end, which are connected to the first air inlet 72 and the second air inlet 73 respectively. A venturi metering valve 311 is installed on the first branch pipe 31 to adjust the upper air intake volume; a circulation pump 321 is installed on the second branch pipe 32 to enhance the lower gas flow and mixing effect.

[0023] In addition, the pressurized gas pipeline 43 is connected to a compressed air pipeline 8, which is equipped with a ball valve 81 for adjusting the gas ratio and pressure. The pressurized gas pipeline 43 is equipped with a gas flow meter, thermometer 432, and pressure gauge 433 to monitor the gas operating status in real time. A check valve 434 is also installed on the pressurized gas pipeline 43 to prevent backflow of gas when the fan stops, ensuring equipment safety.

[0024] The above-mentioned device is used in the neutralization and acidification stage of the p-methylphenol production process as follows: Start the circulating water system of condenser 2 and turn on the Roots blower 42. The tail gas generated from the neutralization reactor 1 is cooled and dehumidified by condenser 2 before entering the tail gas delivery pipeline 3. The condensate from the tail gas condensation enters the sodium sulfite tank. At this time, open the connection between the tail gas collection system 4 and the sulfuric acid production system 6, and check that all valves and instruments are in normal working condition. The sulfur dioxide tail gas generated from the neutralization reaction is partially sent directly to the acidifier 7 via tail gas delivery pipeline 3, and partially enters the Roots blower 42 via tail gas collection pipeline 41. After pressurization, it is sent to the concentrated sulfuric acid drying tower 5. The tail gas pressure and flow rate are kept stable by adjusting the outlet pressure of the Roots blower 42 and the opening of the ball valve 81 on the compressed air pipeline 8. The pressurized gas enters from the inlet 51 at the bottom of the concentrated sulfuric acid drying tower 5, and comes into countercurrent contact with the concentrated sulfuric acid in the tower for dehumidification and impurity removal. The dried gas is then introduced into the sulfuric acid production system 6 via the outlet 52 and the drying gas pipeline 53, where it is converted into sulfuric acid under catalytic conditions. The generated sulfuric acid is returned to the acidifier 7 via sulfuric acid transport pipeline 61 for subsequent acidification reaction.

[0025] The first branch pipe 31 and the second branch pipe 32 at the end of the exhaust gas delivery pipe 3 supply gas to the first air inlet 72 at the top and the second air inlet 73 at the bottom of the acidifier 7, respectively. The sulfur dioxide gas flow in the upper part is regulated by the Venturi metering valve 311 to achieve precise gas ratio; the sulfur dioxide gas flow in the lower part is enhanced by the circulating pump 321 to strengthen gas-liquid mixing and reaction mass transfer. Through the layered air intake design, the acidification reaction can be made more uniform and complete, improving acidification efficiency and product purity.

[0026] During system operation, the gas operating status is monitored in real time by gas flow meter 431, thermometer 432, and pressure gauge 433. Based on the changes in these values, the speed of the Roots blower 42 or the compressed air supply is automatically adjusted to ensure stable system operation within the set parameter range. When the blower stops, the check valve 434 prevents gas backflow, ensuring safe equipment operation.

[0027] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A neutralization and acidification apparatus for the production of p-methylphenol, comprising a neutralization reactor, wherein the upper part of the neutralization reactor is provided with a tail gas outlet, and the tail gas outlet is connected to an acidifier through a tail gas conveying pipe, characterized in that, The exhaust gas conveying pipeline is equipped with an exhaust gas collection system, which includes an exhaust gas collection pipe. One end of the exhaust gas collection pipe is connected to a branch of the exhaust gas conveying pipeline, and the other end of the exhaust gas collection pipe is connected to the air inlet of the Roots blower. The air outlet of the Roots blower is connected to the gas drying system via a pressurized gas pipeline. The outlet of the gas drying system is connected to the sulfuric acid production system. The sulfuric acid production system is connected to the acidification inlet of the acidifier via a sulfuric acid conveying pipeline.

2. The neutralization and acidification apparatus for p-methylphenol production as described in claim 1, characterized in that, The acidifier has a first air inlet at the top and a second air inlet at the bottom. The exhaust gas delivery pipe has a first branch pipe and a second branch pipe at the end. The first branch pipe is connected to the first air inlet and the second branch pipe is connected to the second air inlet.

3. The neutralization and acidification apparatus for p-methylphenol production as described in claim 2, characterized in that, A Venturi metering valve is installed on the first branch pipe, and a circulation pump is installed on the second branch pipe.

4. The neutralization and acidification apparatus for p-methylphenol production as described in claim 1, characterized in that, The gas drying system includes a concentrated sulfuric acid drying tower. The lower part of the concentrated sulfuric acid drying tower is equipped with an air inlet, which is connected to a pressurized gas pipeline. The upper part of the concentrated sulfuric acid drying tower is equipped with an air outlet, which is connected to the feed inlet of the sulfuric acid production system through a drying gas channel.

5. The neutralization and acidification apparatus for p-methylphenol production as described in claim 1, characterized in that, The exhaust outlet is connected to the exhaust gas delivery pipeline via a condenser.

6. The neutralization and acidification apparatus for p-methylphenol production as described in claim 1, characterized in that, The pressurized gas pipeline is connected to a compressed air pipeline, and a ball valve is installed on the compressed air pipeline.

7. The neutralization and acidification apparatus for p-methylphenol production as described in claim 1, characterized in that, The pressurized gas pipeline is equipped with a gas flow meter, a temperature measuring instrument, and a pressure measuring instrument.

8. The neutralization and acidification apparatus for the production of p-methylphenol as described in claim 1, characterized in that, A check valve is installed on the pressurized gas pipeline.

9. A neutralization and acidification apparatus for the production of p-methylphenol as described in claim 1, characterized in that, The exhaust gas collection pipe is equipped with a PTFE-lined ball valve.

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