A device for recovering sodium sulfate using p-methylphenol by-product
By employing a sodium sulfate recovery unit based on p-methylphenol byproducts through steps such as pulping, iron removal, decolorization, concentration, and centrifugation, the problem of low sodium sulfate purity has been solved, achieving the recovery of high-purity sodium sulfate and reducing energy consumption, thereby lowering production costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- JINNENG CHEM (QIHE) CO LTD
- Filing Date
- 2025-05-07
- Publication Date
- 2026-07-21
AI Technical Summary
In existing technologies, the low purity of sodium sulfate byproducts leads to high processing costs and affects the production of p-cresol. Improving the purity of sodium sulfate and reducing production costs is a challenge.
An apparatus, comprising a pulping tank, a filter, a decolorizing kettle, a leaf filter, an evaporator, a centrifuge, a fluidized bed dryer, and a packaging machine, is used to recover high-purity sodium sulfate through pulping, iron removal, decolorization, concentration, and centrifugation. It also utilizes waste steam and condensate to reduce energy consumption and achieve zero emissions of waste carbon.
This approach achieves high-purity recovery of byproducts, reduces processing costs, improves economic efficiency, reduces energy consumption and waste carbon treatment costs, and increases the profit margin of p-methylphenol.
Smart Images
Figure CN224524714U_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of p-cresol production technology, and particularly relates to a device for recovering sodium sulfate using p-cresol byproducts. Background Technology
[0002] Currently, the domestic production process for p-cresol and phenol uses the toluene-sulfuric acid sulfonation-alkali fusion method. This involves reacting sulfuric acid with toluene to produce p-toluenesulfonic acid. The p-toluenesulfonic acid then undergoes an acid-base neutralization reaction with sodium sulfite produced during alkali fusion, generating a sodium p-toluenesulfonate solution. The sodium sulfonate then reacts with caustic soda flakes in an alkali fusion reactor to produce sodium p-cresolphenolate and sodium sulfite. The sodium p-cresolphenolate is then acidified with sulfur dioxide produced during neutralization to obtain crude phenol. This crude phenol is then processed through dehydration, continuous purification, crystallization, and distillation to obtain p-cresol.
[0003] The neutralization reaction involves the acid-base neutralization of p-toluenesulfonic acid with sodium sulfite produced by alkali fusion, generating a sodium p-toluenesulfonate solution. Since p-toluenesulfonic acid contains 4-10% sulfuric acid, during the reaction, the sulfuric acid reacts with sulfurous acid to produce sodium sulfate, sulfur dioxide, and water. During the drying process of the sodium sulfonate, a large amount of this sodium sulfate precipitates due to the common ion effect. This portion of sodium sulfate contains impurities such as sodium p-toluenesulfonate, sodium p-methylphenol, sodium sulfite, and insoluble matter, severely affecting its usability.
[0004] Currently, the main methods for processing this portion of sodium sulfate are as follows:
[0005] (1) During the drying process of sodium sulfonate, sodium sulfate is packaged and stored through sedimentation and centrifugation. This portion of sodium sulfate contains sodium phenolate, sodium p-toluenesulfonate, and other impurities, making it unusable by customers. Currently, this portion of sodium sulfate can only be disposed of as hazardous waste, which incurs high disposal costs.
[0006] (2) By reducing the concentration of sodium sulfonate, sodium sulfate is prevented from precipitating and is carried into the sodium sulfonate during the drying process, and finally removed by alkali fusion of sodium sulfite. This process severely affects the alkali fusion reaction in the production of p-cresol, resulting in high consumption of p-cresol, toluene, and caustic soda flakes, and the sodium sulfite content produced is around 75%, which cannot be processed.
[0007] Improving the purity of sodium sulfate, reducing sales pressure, and lowering the production cost of p-cresol are ongoing challenges for the p-cresol industry. Summary of the Invention
[0008] The purpose of this invention is to provide a device for recovering sodium sulfate using p-methylphenol byproducts, in order to solve the problems existing in the prior art.
[0009] The technical solution adopted by this utility model to solve its technical problem is:
[0010] An apparatus for recovering sodium sulfate using p-methylphenol byproducts includes a pulping tank, which is sequentially connected via pipes to a filter, a decolorizing kettle, a leaf filter, an evaporator, and a centrifuge. The centrifuge is sequentially connected to a fluidized bed dryer and a packaging machine. The liquid output end of the centrifuge is connected in parallel to a high-whiteness mother liquor tank and a low-whiteness mother liquor tank. The high-whiteness mother liquor tank is connected to the liquid inlet of the evaporator, and the low-whiteness mother liquor tank is connected to the pulping tank. The condensate output end of the evaporator is connected to a condensate tank, and the condensate tank is connected to the pulping tank.
[0011] Furthermore, the pulping tank is a tank with an agitator, and a steam pipe is fixed on the pulping tank. The steam pipe input end is connected in parallel with a recovery steam valve and a new steam valve. The steam pipe output end passes through the pulping tank and extends into the lower part of the pulping tank. A pulping pump is installed on the pipe at the output end of the pulping tank. The steam input end of the evaporator is connected in parallel with a recovery steam valve and a new steam valve. The recovery steam valves on the pulping tank and the evaporator are connected to a recovery steam pipeline, and the new steam valves on the pulping tank and the evaporator are connected to a new steam pipeline.
[0012] Furthermore, the decolorizing kettle is a tank with an agitator and a jacket, and a carbon slurry pump is installed on the pipeline at the output end of the decolorizing kettle.
[0013] Furthermore, a receiving cart is installed at the bottom of the solid phase output end of the leaf filter.
[0014] Furthermore, mother liquor valves are installed on the two parallel pipes connected to the liquid phase output end of the centrifuge, and high-whiteness mother liquor pumps and low-whiteness mother liquor pumps are installed on the output pipes of the high-whiteness mother liquor tank and the low-whiteness mother liquor tank, respectively.
[0015] Furthermore, a condensate pump is installed on the pipe at the output end of the condensate tank, and a new water pipe is connected to the input end of the condensate tank, with a new water valve installed on the new water pipe.
[0016] This utility model has the following beneficial effects:
[0017] 1. This utility model can convert by-products into high-purity Class I premium sodium sulfate, thus turning waste into treasure. It not only reduces the processing cost of by-products but also brings additional economic benefits and increases the profit margin of p-methylphenol.
[0018] 2. By recycling and reusing waste steam and condensate, the cost of sodium sulfate recovery is further reduced, and energy consumption is lowered.
[0019] 3. Activated carbon is blended with coal, achieving zero emissions of waste carbon and reducing the cost of waste carbon treatment.
[0020] 4. Reusing the mother liquor increases the yield of sodium sulfate. Attached Figure Description
[0021] Figure 1 This is a schematic diagram of the structure of this utility model.
[0022] Figure 2 This is a process flow diagram of the application of this utility model.
[0023] The components include: 1. Pulping tank; 2. Filter; 3. Decolorizing kettle; 4. Leaf filter; 5. Evaporator; 6. Centrifuge; 7. Fluidized bed dryer; 8. Packaging machine; 9. High whiteness mother liquor tank; 10. Low whiteness mother liquor tank; 11. Condensate tank; 12. Steam pipe; 13. Recovered steam valve; 14. New steam valve; 15. Pulping pump; 16. Recovered steam pipeline; 17. New steam pipeline; 18. Carbon slurry pump; 19. Receiving trolley; 20. Mother liquor valve; 21. High whiteness mother liquor pump; 22. Low whiteness mother liquor pump; 23. Condensate pump; 24. New water pipeline; 25. New water valve. Detailed Implementation
[0024] To make the objectives, technical solutions, and advantages of this utility model clearer, the following detailed description is provided in conjunction with specific embodiments and accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the utility model and are not intended to limit the scope of the utility model.
[0025] Example 1:
[0026] like Figure 1 As shown, an apparatus for recovering sodium sulfate using p-methylphenol byproducts includes a pulping tank 1. The pulping tank 1 is connected in sequence via pipes to a filter 2, a decolorizing kettle 3, a leaf filter 4, an evaporator 5, and a centrifuge 6. The centrifuge 6 is connected in sequence to a fluidized bed dryer 7 and a packaging machine 8. The liquid phase output end of the centrifuge 6 is connected in parallel to a high-whiteness mother liquor tank 9 and a low-whiteness mother liquor tank 10. The high-whiteness mother liquor tank 9 is connected in a pipe to the liquid inlet end of the evaporator 5, and the low-whiteness mother liquor tank 10 is connected in a pipe to the pulping tank 1. The condensate output end of the evaporator 5 is connected to a condensate tank 11, and the condensate tank 11 is connected in a pipe to the pulping tank 1.
[0027] The pulping tank 1 is a tank equipped with a stirrer. A steam pipe 12 is fixed on the pulping tank 1. The input end of the steam pipe 12 is connected in parallel with a recovery steam valve 13 and a new steam valve 14. The output end of the steam pipe 12 passes through the pulping tank 1 and extends into the lower part of the pulping tank 1. A pulping pump 15 is installed on the output end of the pulping tank 1. The steam input end of the evaporator 5 is connected in parallel with a recovery steam valve 13 and a new steam valve 14. The recovery steam valves 13 on the pulping tank 1 and the evaporator 5 are connected together to a recovery steam pipeline 16. The new steam valves 14 on the pulping tank 1 and the evaporator 5 are connected together to a new steam pipeline 17. The recovery steam pipeline 16 contains low-pressure steam such as waste steam and drying waste steam recovered in the workshop. When pulping the pulping tank 1, high-pressure supersaturated steam is not required, so costs can be reduced by using recovered steam.
[0028] The decolorizing kettle 3 is a tank with a stirrer and a jacket, and a carbon slurry pump 18 is installed on the pipe at the output end of the decolorizing kettle 3.
[0029] A receiving cart 19 is provided at the bottom of the solid phase output end of the leaf filter 4.
[0030] Mother liquor valves 20 are installed on the two parallel pipes connected to the liquid phase output end of centrifuge 6. High whiteness mother liquor pump 21 and low whiteness mother liquor pump 22 are installed on the output pipes of high whiteness mother liquor tank 9 and low whiteness mother liquor tank 10, respectively.
[0031] A condensate pump 23 is installed on the pipe at the output end of the condensate tank 11, and a fresh water pipe 24 is connected to the input end of the condensate tank 11. A fresh water valve 25 is installed on the fresh water pipe 24.
[0032] Example 2:
[0033] like Figure 2 As shown, this embodiment is based on the structure of Example 1, specifically a method for recovering sodium sulfate using p-methylphenol byproducts, including the following steps:
[0034] (1) Pulping: Add 200 kg of by-product and 1 t of water to pulping tank 1. Prioritize using the steam condensate recovered from condensate tank 11 for pulping; if insufficient, open new water valve 25 to use fresh water. Introduce steam through steam pipe 12 to raise the temperature to 45°C, ensuring complete dissolution of the by-product. When introducing steam through steam pipe 12 to raise the temperature, prioritize opening the recovered low-pressure steam valve 13 on pulping tank 1 to use the recovered steam; if insufficient, open new steam valve 14 to use fresh steam.
[0035] (2) Iron removal: Add 30% liquid alkali to the pulping tank 1 to adjust the pH to 8, so that the iron ions in the sodium sulfate form iron hydroxide precipitate. The pulping liquid is pumped into the filter 2 through the pulping pump 15 to remove insoluble substances and iron hydroxide precipitate, and the filtrate is obtained.
[0036] (3) Decolorization: After the filtrate is fed into the decolorization kettle 3, sulfuric acid is added to adjust the pH to 3, so that the sodium sulfite in the filtrate is converted into sodium sulfate, sodium p-toluenesulfonate is converted into p-toluenesulfonic acid, and sodium p-toluene is converted into p-toluenephenol. Then, activated carbon is added at 1.2% of the filtrate mass. After decolorization at 80°C for 30 minutes, the filtrate is fed into the leaf filter 4 through the carbon slurry pump 18 to obtain decolorized liquid and waste carbon. The decolorized liquid is fed into the circulation tank of the evaporator 5, and the waste carbon falls into the receiving car 19 at the bottom and is sent to the coal blending unit.
[0037] (4) Concentration: After the decolorizing liquid enters the evaporator 5, liquid alkali is added to adjust the pH to 8. The liquid is concentrated under negative pressure at -80 to -99 kPa until the solid content (the proportion of the precipitated solid to the total mass of sodium sulfate slurry) is 20%, and sodium sulfate slurry is obtained. During negative pressure concentration, the recovery steam valve 13 on the evaporator 5 is opened first to use the recovered low-pressure steam. If the recovery is insufficient, the new steam valve 14 is opened to use the new steam.
[0038] (5) Centrifugation: Centrifuge 6 is used to centrifuge the sodium sulfate slurry to obtain sodium sulfate solid with a water content of 4% and a purity of 99.8% and mother liquor. The mother liquor with a whiteness of ≥90% is fed into the high whiteness mother liquor tank 9 and then recycled to the concentration step through the high whiteness mother liquor pump 21. The mother liquor with a whiteness of <90% is fed into the low whiteness mother liquor tank 10 and then recycled to the pulping step through the low whiteness mother liquor pump 22.
[0039] (6) Drying: Sodium sulfate solid is dried in a fluidized bed dryer 7 until the water content is less than 0.05%, and then packaged in a packaging machine 8 to obtain the finished product.
[0040] Example 3:
[0041] like Figure 2 As shown, this embodiment is based on the structure of Example 1, specifically a method for recovering sodium sulfate using p-methylphenol byproducts, including the following steps:
[0042] (1) Pulping: Add 500 kg of by-product and 1 t of water to pulping tank 1. Prioritize using the steam condensate recovered from condensate tank 11 for pulping; if insufficient, open new water valve 25 to use fresh water. Introduce steam through steam pipe 12 to raise the temperature to 100°C, ensuring complete dissolution of the by-product. When introducing steam through steam pipe 12 to raise the temperature, prioritize opening the recovered steam valve 13 on pulping tank 1 to use the recovered low-pressure steam; if insufficient, open new steam valve 14 to use fresh steam.
[0043] (2) Iron removal: Add 30% liquid alkali to the pulping tank 1 to adjust the pH to 13, so that the iron ions in the sodium sulfate form iron hydroxide precipitate. The pulping liquid is pumped into the filter 2 through the pulping pump 15 to remove insoluble substances and iron hydroxide precipitate, and the filtrate is obtained.
[0044] (3) Decolorization: After the filtrate is fed into the decolorization kettle 3, sulfuric acid is added to adjust the pH to 1, so that the sodium sulfite in the filtrate is converted into sodium sulfate, sodium p-toluenesulfonate is converted into p-toluenesulfonic acid, and sodium p-toluene is converted into p-toluenephenol. Then, activated carbon is added at 0.7% of the filtrate mass. After decolorization at 95°C for 30 minutes, the filtrate is fed into the leaf filter 4 through the carbon slurry pump 18 to obtain decolorized liquid and waste carbon. The decolorized liquid is fed into the circulation tank of the evaporator 5, and the waste carbon falls into the receiving car 19 at the bottom and is sent to the coal blending unit.
[0045] (4) Concentration: After the decolorizing liquid enters the evaporator 5, liquid alkali is added to adjust the pH to 7. The liquid is concentrated under negative pressure at -80 to -99 kPa until the solid content (the proportion of the precipitated solid to the total mass of sodium sulfate slurry) is 65%, and sodium sulfate slurry is obtained. During negative pressure concentration, the recovery steam valve 13 on the evaporator 5 is opened first to use the recovered low-pressure steam. If the recovery is insufficient, the new steam valve 14 is opened to use the new steam.
[0046] (5) Centrifugation: Centrifuge 6 is used to centrifuge the sodium sulfate slurry to obtain sodium sulfate solid with a water content of 10% and a purity of 99.6% and mother liquor. The mother liquor with a whiteness of ≥90% is fed into the high whiteness mother liquor tank 9 and then recycled to the concentration step through the high whiteness mother liquor pump 21. The mother liquor with a whiteness of <90% is fed into the low whiteness mother liquor tank 10 and then recycled to the pulping step through the low whiteness mother liquor pump 22.
[0047] (6) Drying: Sodium sulfate solid is dried in a fluidized bed dryer 7 until the water content is less than 0.05%, and then packaged in a packaging machine 8 to obtain the finished product.
[0048] Example 4:
[0049] like Figure 2 As shown, this embodiment is based on the structure of Example 1, specifically a method for recovering sodium sulfate using p-methylphenol byproducts, including the following steps:
[0050] (1) Pulping: Add 300 kg of by-product and 1 t of water to pulping tank 1. Prioritize using the steam condensate recovered from condensate tank 11 for pulping; if insufficient, open new water valve 25 to use fresh water. Introduce steam through steam pipe 12 to raise the temperature to 80°C, ensuring complete dissolution of the by-product. When introducing steam through steam pipe 12 to raise the temperature, prioritize opening the recovered steam valve 13 on pulping tank 1 to use the recovered low-pressure steam; if insufficient, open new steam valve 14 to use fresh steam.
[0051] (2) Iron removal: Add 30% liquid alkali to the pulping tank 1 to adjust the pH to 10, so that the iron ions in the sodium sulfate form iron hydroxide precipitate. The pulping liquid is pumped into the filter 2 through the pulping pump 15 to remove insoluble substances and iron hydroxide precipitate, and the filtrate is obtained.
[0052] (3) Decolorization: After the filtrate is fed into the decolorization kettle 3, sulfuric acid is added to adjust the pH to 2, so that the sodium sulfite in the filtrate is converted into sodium sulfate, sodium p-toluenesulfonate is converted into p-toluenesulfonic acid, and sodium p-toluene is converted into p-toluenephenol. Then, activated carbon is added at 1% of the filtrate mass. After decolorization at 80°C for 30 minutes, the filtrate is fed into the leaf filter 4 through the carbon slurry pump 18 to obtain decolorized liquid and waste carbon. The decolorized liquid is fed into the circulation tank of the evaporator 5, and the waste carbon falls into the receiving car 19 at the bottom and is sent to the coal blending unit.
[0053] (4) Concentration: After the decolorizing liquid enters the evaporator 5, liquid alkali is added to adjust the pH to 7.5. The solid content (the proportion of the precipitated solid to the total mass of sodium sulfate slurry) is concentrated under negative pressure at -80 to -99 kPa to obtain sodium sulfate slurry. When concentrating under negative pressure, the recovery steam valve 13 on the evaporator 5 is opened first to use the recovered low-pressure steam. If it is insufficient, the new steam valve 14 is opened to use new steam.
[0054] (5) Centrifugation: Centrifuge 6 is used to centrifuge the sodium sulfate slurry to obtain sodium sulfate solid with a water content of 6% and a purity of 99.7% and mother liquor. The mother liquor with a whiteness of ≥90% is fed into the high whiteness mother liquor tank 9 and then recycled to the concentration step through the high whiteness mother liquor pump 21. The mother liquor with a whiteness of <90% is fed into the low whiteness mother liquor tank 10 and then recycled to the pulping step through the low whiteness mother liquor pump 22.
[0055] (6) Drying: Sodium sulfate solid is dried in a fluidized bed dryer 7 until the water content is less than 0.05%, and then packaged in a packaging machine 8 to obtain the finished product.
[0056] The working principle of this utility model is as follows:
[0057] First, the byproducts are dissolved, and the pH is adjusted to alkaline to cause iron ions to precipitate as ferric hydroxide, which is then removed by filtration. Next, the pH is adjusted to acidic using sulfuric acid, converting sodium sulfite to sodium sulfate, sodium p-toluenesulfonate to p-toluenesulfonic acid, and sodium p-toluene to p-toluenephenol in the filtrate. Activated carbon adsorbs p-toluenesulfonic acid and p-toluenephenol, thereby increasing the purity of the sodium sulfate. After adjusting the pH to alkaline, the sodium sulfate is concentrated to precipitate, and further centrifuged and dried to obtain a high-purity sodium sulfate product.
[0058] The above embodiments are merely descriptions of preferred embodiments of the present invention and are not intended to limit the concept and scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the design concept of the present invention should fall within the protection scope of the present invention.
[0059] The technologies, shapes, and structures not described in detail in this utility model are all known technologies.
Claims
1. An apparatus for recovering sodium sulfate from p-methylphenol byproducts, characterized in that, The system includes a pulping tank, which is connected in sequence to a filter, a decolorizing kettle, a leaf filter, an evaporator, and a centrifuge via pipes. The centrifuge is connected in sequence to a fluidized bed dryer and a packaging machine. The liquid phase output end of the centrifuge is connected in parallel to a high-whiteness mother liquor tank and a low-whiteness mother liquor tank. The high-whiteness mother liquor tank is connected to the liquid inlet end of the evaporator, and the low-whiteness mother liquor tank is connected to the pulping tank. The condensate output end of the evaporator is connected to a condensate tank, and the condensate tank is connected to the pulping tank.
2. The apparatus for recovering sodium sulfate from p-methylphenol byproducts according to claim 1, characterized in that, The pulping tank is a tank with a stirrer. A steam pipe is fixed on the pulping tank. A steam recovery valve and a new steam valve are connected in parallel to the steam pipe input end. The steam pipe output end passes through the pulping tank and extends into the lower part of the pulping tank. A pulping pump is installed on the pipe at the output end of the pulping tank. A steam recovery valve and a new steam valve are connected in parallel to the steam input end of the evaporator. The steam recovery valves on the pulping tank and the evaporator are connected to a steam recovery pipeline. The new steam valves on the pulping tank and the evaporator are connected to a new steam pipeline.
3. The apparatus for recovering sodium sulfate from p-methylphenol byproducts according to claim 1, characterized in that, The decolorizing kettle is a tank with a stirrer and a jacket, and a carbon slurry pump is installed on the pipe at the output end of the decolorizing kettle.
4. The apparatus for recovering sodium sulfate from p-methylphenol byproducts according to claim 1, characterized in that, The leaf filter has a receiving cart at the bottom of its solid output end.
5. The apparatus for recovering sodium sulfate from p-methylphenol byproducts according to claim 1, characterized in that, The two parallel pipes connected to the liquid output end of the centrifuge are each equipped with a mother liquor valve, and the output pipes of the high whiteness mother liquor tank and the low whiteness mother liquor tank are respectively equipped with a high whiteness mother liquor pump and a low whiteness mother liquor pump.
6. The apparatus for recovering sodium sulfate from p-methylphenol byproducts according to claim 1, characterized in that, A condensate pump is installed on the pipe at the output end of the condensate tank, and a new water pipe is connected to the input end of the condensate tank, with a new water valve installed on the new water pipe.