System for recovering phthalic anhydride from 1, 4-dihydroxy anthraquinone production mother liquor

Abstract

The utility model belongs to the technical field of production of chemical intermediates, and particularly discloses a system for recovering phthalic anhydride from 1, 4-dihydroxy anthraquinone production mother liquor, which comprises a flocculent precipitation system, a hot melting neutralization system and a crystallization separation system, the flocculation precipitation system comprises a mother liquor cooling kettle and a first filter press, the hot dissolution neutralization system comprises a hot dissolution kettle and a second filter press, the crystallization separation system comprises a crystallization kettle, a centrifugal machine and a drying machine, the input end of the crystallization kettle is communicated with a sulfuric acid feeding tank, the output end of the crystallization kettle is communicated with the centrifugal machine, and the material output end of the centrifugal machine is communicated with the input end of the drying machine. The output end of the dryer communicates with a finished product collecting tank; the filter cake output end of the first filter press is communicated with the input end of the hot dissolving kettle, and the filtrate output end of the second filter press is communicated with the input end of the crystallization kettle. According to the device disclosed by the utility model, the phthalic anhydride is recycled after decoloring and flocculating, neutralizing and dissolving, crystallizing and separating the phthalic anhydride, centrifuging and drying in sequence, so that the phthalic anhydride in the mother liquor is prevented from being wasted.

Description

Technical Field

[0001] This invention belongs to the field of chemical intermediate production technology, specifically a system for recovering phthalic anhydride from the mother liquor of 1,4-dihydroxyanthraquinone production. Background Technology

[0002] 1,4-Dihydroxyanthraquinone is an orange powder and an important dye intermediate, also known as the orange intermediate. Currently, domestic production of 1,4-dihydroxyanthraquinone mainly employs the hydroquinone process and the p-chlorophenol process. Both methods involve reacting with phthalic anhydride as a raw material, followed by a series of separation processes to obtain the finished 1,4-dihydroxyanthraquinone. In actual production, to promote the forward reaction, an excess of phthalic anhydride is intentionally added. This results in a large amount of phthalic anhydride mixed in the mother liquor after production, which is then treated along with the wastewater, leading to waste. Therefore, a system for recovering phthalic anhydride from the 1,4-dihydroxyanthraquinone production mother liquor needs to be designed. Utility Model Content

[0003] To address the above technical problems, this utility model provides a system for recovering phthalic anhydride from the mother liquor of 1,4-dihydroxyanthraquinone production, which solves the problem of waste caused by the non-recovery and utilization of phthalic anhydride in the mother liquor.

[0004] To solve the above technical problems, the technical solution of this utility model is: a system for recovering phthalic anhydride from the mother liquor of 1,4-dihydroxyanthraquinone production, including a flocculation precipitation system, a hot dissolution neutralization system, and a crystallization separation system;

[0005] The flocculation and sedimentation system includes a mother liquor cooling tank and a first filter press. The input end of the mother liquor cooling tank is connected to a mother liquor tank and a flocculant feeding tank, respectively. The output end of the mother liquor cooling tank is connected to the input end of the first filter press through a pipeline.

[0006] The hot dissolution neutralization system includes a hot dissolution kettle and a second filter press. The input end of the hot dissolution kettle is connected to an ammonia water feeding tank, and the output end of the hot dissolution kettle is connected to the input end of the second filter press through a pipeline.

[0007] The crystallization separation system includes a crystallization kettle, a centrifuge, and a dryer. The input end of the crystallization kettle is connected to a sulfuric acid feeding tank, the output end of the crystallization kettle is connected to the centrifuge, the material output end of the centrifuge is connected to the input end of the dryer, and the output end of the dryer is connected to a finished product collection tank.

[0008] The filter cake output end of the first filter press is connected to the input end of the hot dissolving kettle, and the filtrate output end of the second filter press is connected to the input end of the crystallization kettle.

[0009] Furthermore, material conveying pumps are installed in the pipeline between the mother liquor cooling tank and the first filter press, and in the pipeline between the hot dissolving tank and the second filter press.

[0010] Furthermore, the input end of the hot dissolving kettle is also connected to an activated carbon feeding tank.

[0011] This utility model has the following advantages compared with the prior art:

[0012] 1. This utility model, by sequentially setting up a flocculation sedimentation system, a hot dissolution and neutralization system, and a crystallization and separation system, decolorizes, flocculates, neutralizes and dissolves, and crystallizes and separates phthalic anhydride from the mother liquor produced by 1,4-dihydroxyanthraquinone. After centrifugation and drying, the phthalic anhydride is recovered and reused, avoiding the phenomenon of unrecovered phthalic anhydride in the final mother liquor being directly discharged, preventing the waste of phthalic anhydride in the mother liquor, and reducing the raw material cost of production.

[0013] 2. By setting up an activated carbon feeding tank and adding activated carbon to the hot dissolution kettle, the organic phase that is insoluble in hot water can be adsorbed during the hot water dissolution process and removed after subsequent solid-liquid separation by pressure filtration, thereby further improving the purity of the recovered phthalic anhydride. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the connection relationship of this utility model.

[0015] In the diagram: 1. Mother liquor cooling tank, 2. First filter press, 3. Mother liquor feeding tank, 4. Flocculant feeding tank, 5. Hot dissolving tank, 6. Second filter press, 7. Ammonia water feeding tank, 8. Crystallization tank, 9. Centrifuge, 10. Dryer, 11. Sulfuric acid feeding tank, 12. Finished product collection tank, 13. Material conveying pump. Detailed Implementation

[0016] The present invention will be further described below with reference to the accompanying drawings.

[0017] like Figure 1 The system shown is for recovering phthalic anhydride from the mother liquor of 1,4-dihydroxyanthraquinone production, including a flocculation precipitation system, a thermal dissolution neutralization system, and a crystallization separation system.

[0018] The flocculation and sedimentation system includes a mother liquor cooling tank 1 and a first filter press 2. The input end of the mother liquor cooling tank 1 is connected to a mother liquor feeding tank 3 and a flocculant feeding tank 4. The mother liquor feeding tank 3 and the flocculant feeding tank 4 add mother liquor and decolorizing flocculant to the mother liquor cooling tank 1 respectively. The output end of the mother liquor cooling tank 1 is connected to the input end of the first filter press 2 through a pipeline.

[0019] The hot dissolution neutralization system includes a hot dissolution kettle 5 and a second filter press 6. The input end of the hot dissolution kettle 5 is connected to an ammonia water feeding tank 7. The ammonia water feeding tank 7 adds dilute ammonia water to the hot dissolution kettle 5 to neutralize the solution and adjust the pH to neutral. If necessary, hot dilute ammonia water can also be added to accelerate the dissolution rate. The output end of the hot dissolution kettle 5 is connected to the input end of the second filter press 6 through a pipeline.

[0020] The crystallization separation system includes a crystallization kettle 8, a centrifuge 9, and a dryer 10. The input end of the crystallization kettle 8 is connected to a sulfuric acid feeding tank 11, which adds sulfuric acid required for acidification into the crystallization kettle 8. The output end of the crystallization kettle 8 is connected to the centrifuge 9, and the material output end of the centrifuge 9 is connected to the input end of the dryer 10. The output end of the dryer 10 is connected to a finished product collection tank 12.

[0021] The flocculation sedimentation system, the hot dissolution neutralization system, and the crystallization separation system are connected sequentially. Specifically, the filter cake output end of the first filter press 2 is connected to the input end of the hot dissolution kettle 5, and the filtrate output end of the second filter press 6 is connected to the input end of the crystallization kettle 8.

[0022] In this embodiment, the mother liquor cooling vessel 1, the hot dissolving vessel 5, and the crystallization vessel 8 are all jacketed reaction vessels commonly used in the chemical industry. Cold water is circulated in the jackets of the mother liquor cooling vessel 1 and the crystallization vessel 8 to exchange heat, thereby reducing the temperature inside the crystallization vessel 8 and accelerating the crystallization of phthalic anhydride. Steam is circulated in the jacket of the hot dissolving vessel 5 to exchange heat, thereby increasing the temperature inside the hot dissolving vessel 5 and accelerating the dissolution of ammonium phthalate.

[0023] In this embodiment, both the first filter press 2 and the second filter press 6 are diaphragm filter presses, model XMAZG / 1500-U, and the dryer 10 is a vacuum double cone dryer, model SZG-2000.

[0024] In order to facilitate the transfer of materials in the mother liquor cooling tank 1 and the hot dissolving tank 5 to the corresponding diaphragm filter press for solid-liquid separation, material conveying pumps 13 are installed in the pipeline between the mother liquor cooling tank 1 and the first filter press 2, and in the pipeline between the hot dissolving tank 5 and the second filter press 6.

[0025] In order to adsorb and remove immiscible liquid organic substances in the hot dissolving kettle 5 and further decolorize them, the input end of the hot dissolving kettle 5 is also connected to an activated carbon feeding tank. Before the material enters the hot dissolving kettle 5, activated carbon is added into the hot dissolving kettle 5 through the activated carbon feeding tank, and then the material is added, and adsorption is carried out by the activated carbon.

[0026] The specific working process of this utility model is as follows:

[0027] The acidic mother liquor from the production of 1,4-dihydroxyanthraquinone is added to the mother liquor cooling kettle 1 via the mother liquor feeding tank 3. Simultaneously, decolorizing flocculant is added to the mother liquor cooling kettle 1 via the flocculant feeding tank 4. Under the continuous heat exchange of cold water within the jacket of the mother liquor cooling kettle 1, the temperature inside the kettle decreases, accelerating the formation of flocculation and precipitation of the organic phase. After a period of time, the material in the mother liquor cooling kettle 1 is pumped to the first filter press 2 via the material transfer pump 13 for initial solid-liquid separation. The filtrate is sent to wastewater treatment. The filter cake from the first filter press 2 is then fed into the hot dissolving kettle 5. Simultaneously, hot dilute ammonia is added to the hot dissolving kettle 5 via the ammonia feeding tank 7 to neutralize the material and adjust the pH. Under the continuous heat exchange of steam within the jacket of the hot dissolving kettle 5, the temperature inside the kettle rises and is maintained at approximately 95 degrees Celsius. The hot water in the kettle dissolves the phthalic anhydride in the filter cake, while simultaneously activating... Carbonized charcoal can adsorb organic components in the liquid phase that are insoluble in water. After adjusting the pH to neutral and keeping it at a certain temperature for a period of time, the material in the hot dissolving kettle 5 is transported to the second filter press 6 through the material conveying pump 13 on the corresponding pipeline for the second solid-liquid separation. After this filtration, the small amount of filter cake obtained is mainly composed of 1,4-dihydroxyanthraquinone. The filter cake can be recovered for further purification and product recovery. The filtrate is mainly composed of phthalic anhydride dissolved in hot water, hydrolyzed phthalic anhydride and ammonium salt formed by ammonia water. The filtrate obtained from the second filtration is taken and put into the crystallization kettle 8. After acidification by adding sulfuric acid through the sulfuric acid feeding tank 11, phthalic anhydride is crystallized and separated. The material that has been crystallized in the crystallization kettle 8 is put into the centrifuge 9 for centrifugation. After centrifugation, the liquid enters the wastewater treatment. The solid material after centrifugation is taken and put into the dryer 10. After drying, the phthalic anhydride product is obtained and placed in the finished product collection tank 12 for temporary storage, waiting for recycling and reuse.

Claims

1. A system for recovering phthalic anhydride in a 1,4-dihydroxyanthraquinone production mother liquor, characterized by: The system comprises a flocculation and precipitation system, a hot dissolving and neutralization system, and a crystallization and separation system. The flocculation and precipitation system comprises a mother liquor cooling kettle (1) and a first filter press (2), the input end of the mother liquor cooling kettle (1) is connected with a mother liquor feeding tank (3) and a flocculant feeding tank (4), and the output end of the mother liquor cooling kettle (1) is connected with the input end of the first filter press (2) through a pipeline. The hot dissolving and neutralization system comprises a hot dissolving kettle (5) and a second filter press (6), the input end of the hot dissolving kettle (5) is connected with an ammonia water feeding tank (7), and the output end of the hot dissolving kettle (5) is connected with the input end of the second filter press (6) through a pipeline. The crystallization and separation system comprises a crystallization kettle (8), a centrifugal machine (9), and a drying machine (10), the input end of the crystallization kettle (8) is connected with a sulfuric acid feeding tank (11), the output end of the crystallization kettle (8) is connected with the centrifugal machine (9), the output end of the centrifugal machine (9) is connected with the input end of the drying machine (10), and the output end of the drying machine (10) is connected with a finished product collecting tank (12). The filter cake output end of the first filter press (2) is connected with the input end of the hot dissolving kettle (5), and the filtrate output end of the second filter press (6) is connected with the input end of the crystallization kettle (8).

2. The system for recovering phthalic anhydride in a 1,4-dihydroxyanthraquinone production mother liquor according to claim 1, characterized by: Material conveying pumps (13) are installed in the pipelines between the mother liquor cooling kettle (1) and the first filter press (2) and between the hot dissolving kettle (5) and the second filter press (6).

3. The system for recovering phthalic anhydride in a 1,4-dihydroxyanthraquinone production mother liquor according to claim 1, characterized by: The input end of the hot dissolving kettle (5) is also connected with an activated carbon feeding tank.

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