System and process method for efficiently recovering DBP solvent in maleic anhydride production

Abstract

The invention relates to the technical field of maleic anhydride solvent recovery, in particular to a system and a process method for efficiently recovering a DBP solvent in maleic anhydride production. The system comprises a desorption tower, a tail gas washing tower, an extraction tower and a rectifying tower, the desorption tower is provided with a rich solvent feed line, a desorption discharge line and a liquid outlet line connected to the vertical shell-and-tube reboiler, and the desorption discharge line is in heat exchange connection with the rich solvent feed line through a feed preheater; a feed line at the top of the extraction tower is communicated with a desorption discharge line, and a DBP solvent discharge line and an extractant DMI circulating feed line are arranged at the bottom of the extraction tower; a second crude maleic anhydride extraction line is arranged at the top of the rectifying tower; the bottom of the rectifying tower is communicated with an extractant DMI circulating feeding line; one part of the extracting agent in the tower kettle enters the extraction tower for recycling after being cooled, and the other part of the extracting agent returns to the bottom of the rectifying tower in a gas-phase form to participate in rectification after being preheated. By arranging the extraction tower and the rectifying tower, the operation temperature of the system is reduced, the decomposition of DBP in maleic anhydride and the generation of tar are reduced, and the blockage and shutdown of the device are avoided as much as possible.

Description

Technical Field

[0001] The invention relates to the technical field of maleic anhydride solvent recovery, in particular to a system and process method for efficiently recovering DBP solvent in maleic anhydride production. Background Art

[0002] In the production of maleic anhydride, the DBP (dibutyl phthalate) solvent recovery process is a key step in ensuring efficient maleic anhydride recovery and solvent recycling. The process mainly includes two core steps: absorption and desorption: Absorption stage: using DBP solvent to absorb maleic anhydride in the reaction tail gas to achieve initial enrichment of the target product; Desorption stage: Maleic anhydride is desorbed from the DBP solvent by heating, and the crude maleic anhydride is sent to the refining tower for purification, while the lean solvent DBP is sent to the lean liquid refining unit, where it is returned to the absorption tower for recycling after impurities are removed.

[0003] However, the current process has serious technical defects in the desorption stage, which directly affects the long-term stable operation of the system: 1) DBP high-temperature decomposition: The operating temperature at the bottom of the desorption tower reaches as high as 199°C. After being superheated to 215°C in a heat exchanger, it enters the post-flash tower to further remove a small amount of maleic anhydride from the desorption tower bottom material. Under these conditions, DBP is prone to thermal decomposition, producing small-molecule byproducts such as phthalic anhydride and butanol. These substances further polymerize to form high-molecular-weight tar. Despite vacuum operation to reduce the bottom temperature, DBP decomposition cannot be completely avoided and continues to accumulate in the system, eventually leading to pipeline blockages and even unplanned downtime.

[0004] 2) Energy loss and impurity accumulation: The high temperature carried by the discharge from the desorption tower kettle cannot be positively utilized, resulting in energy waste. In addition, the light components extracted from the top of the desorption tower require additional treatment, and the decomposition products remaining in the lean solvent at the bottom of the tower may reduce the absorption efficiency, forming a vicious cycle.

[0005] In summary, the insufficient thermal stability of DBP has become a core bottleneck restricting the efficient operation of maleic anhydride recovery processes. Effectively inhibiting DBP decomposition, reducing tar formation, and fully utilizing the energy exchange during maleic anhydride production are key technical challenges that need to be addressed. Summary of the Invention

[0006] The purpose of the present invention is to provide a system and process for efficiently recovering DBP solvent in maleic anhydride production, thereby reducing the operating temperature of the system as much as possible, reducing the decomposition of DBP and the generation of tar in maleic anhydride, and avoiding device blockage and shutdown as much as possible.

[0007] In order to achieve the above technical effects, the present invention discloses a system for efficiently recovering DBP solvent in maleic anhydride production, the system comprising a desorption tower, a tail gas scrubber, an extraction tower and a distillation tower; The desorption tower is provided with a rich solvent feed line, a desorption discharge line and a liquid outlet line connected to a vertical shell and tube reboiler; the desorption discharge line is connected to the rich solvent feed line for heat exchange, and the rich solvent from the absorption unit is heated to 160-170° C. after heat exchange with the discharge from the desorption tower kettle, and then enters the desorption tower through the rich solvent feed line; the discharge from the desorption tower kettle is cooled to 70-90° C. after heat exchange, and then enters the extraction tower through the desorption discharge line; the solution in the desorption tower kettle is transported to the top of the vertical shell and tube reboiler by a pressure pump on the liquid outlet line for forced circulation, and the solution is heated to 190-200° C. by steam, and the gas phase returns to the bottom of the desorption tower; The top feed line of the extraction tower is connected to the desorption discharge line, and the top discharge line of the extraction tower is connected to the distillation tower; the bottom of the extraction tower is provided with a DBP solvent discharge line and an extractant DMI circulation feed line; A second crude maleic anhydride extraction line is provided at the top of the distillation tower; one portion is connected to the crude anhydride storage tank, and the other portion returns to the top of the distillation tower to participate in distillation; the bottom of the distillation tower is connected to the extractant DMI circulation feed line; one portion of the extractant in the distillation tower kettle enters the extraction tower for recycling after cooling, and the other portion is preheated and returned to the bottom of the distillation tower in the form of gas to participate in distillation.

[0008] As a preferred technical solution, the vertical shell and tube reboiler is arranged outside the tower kettle, its feed port is connected to the bottom of the desorption tower through a liquid outlet line, and its discharge port is communicated with the lower part of the desorption tower.

[0009] As a preferred technical solution, the desorption tower kettle is connected to a desorption discharge line, and the desorption discharge line and the rich solvent feed line are jointly connected to a feed preheater for heat exchange.

[0010] As a preferred technical solution, the material discharged from the top of the desorption tower is cooled in a condenser and then subjected to gas-liquid separation, the gas phase enters the tail gas washing tower, and the liquid phase returns to the desorption tower as reflux.

[0011] As a preferred technical solution, the top feed line of the extraction tower is connected to the condenser outlet.

[0012] As a preferred technical solution, it also includes an extractant DMI storage tank and a feeding pipeline, and the feeding pipeline is connected to the extractant DMI circulation feed line.

[0013] As a preferred technical solution, a first crude maleic anhydride production line is provided on the upper portion of the desorption tower, which is connected together with the second crude maleic anhydride production line of the distillation tower to the crude anhydride storage tank.

[0014] As a preferred technical solution, an extractant DMI storage tank connected to an extractant circulation feed line is further provided outside the extraction tower for replenishing the extractant.

[0015] The present invention also discloses a process for utilizing the above-mentioned system for efficiently recovering DBP solvent in maleic anhydride production, comprising the following steps: S1, the rich solvent from the absorption unit exchanges heat with the discharge from the desorption tower kettle and heats up to temperature T1, and then enters the middle of the desorption tower; S2, the solution in the desorption tower kettle is transported to the top of the vertical shell and tube reboiler via a pressure pump, heated to temperature T2 by steam to form a liquid film evaporation, the gas phase returns to the bottom of the desorption tower for heat and mass transfer, and the heavy components gradually accumulate in the liquid phase; at the same time, the crude maleic anhydride product is sampled from the upper side of the desorption tower; the top discharge of the desorption tower is mainly acrylic acid and a small amount of maleic anhydride, which is cooled to temperature T3 by a condenser for gas-liquid separation, the gas phase enters the tail gas scrubber, and the liquid phase returns to the top of the desorption tower to participate in heat and mass transfer; S3, the desorption tower kettle discharge is cooled to temperature T4 and then fed into the top of the extraction tower as a dispersed phase, and is countercurrently contacted with the circulating extractant DMI entering from the bottom of the tower for mass transfer, and the extractant containing maleic anhydride is obtained at the top of the tower, and the DBP solvent is separated at the bottom of the tower; S4. The maleic anhydride extractant at the top of the extraction tower is sent to a distillation tower for separation, and a crude maleic anhydride product is obtained at the top of the tower. A portion of the extractant in the bottom of the tower is cooled to a temperature T5 and then circulated to the extraction tower, and the remaining portion is vaporized and returned to the distillation tower for distillation.

[0016] As a preferred technical solution, the T1 is 160-170°C, and / or the T2 is 190-200°C, and / or T3 is 92-98°C, and / or T4 is 70-90°C, and / or T5 is 70-90°C.

[0017] The beneficial effects of the present invention are: 1. By replacing the traditional post-flash tower with a combined extraction and distillation tower system, the operating temperature of the tower bottom is significantly reduced, effectively inhibiting the decomposition of the DBP solvent at high temperatures, reducing the formation of by-products such as phthalic anhydride and butanol, and high-molecular tar, thereby avoiding device blockage and unplanned shutdown problems.

[0018] 2. The heat exchange design of the desorption tower kettle discharge and the rich solvent feed fully utilizes the thermal energy of high-temperature materials, reduces energy waste, and improves the overall energy efficiency of the system.

[0019] 3. The desorption tower adopts a vertical shell and tube reboiler, which greatly improves the heat transfer efficiency through the characteristics of rapid liquid film evaporation and short residence time, while avoiding the decomposition of DBP under long-term high temperature.

[0020] 4. The extraction tower uses DMI as the extractant, achieving efficient separation of maleic anhydride and DBP at low temperatures (70-90°C). The distillation tower further purifies the maleic anhydride and recovers the extractant for recycling, ensuring the DBP solvent recovery rate while reducing the risk of impurity accumulation.

[0021] 5. By adding tail gas scrubbers and extractant replenishing facilities, the non-condensable gas treatment and solvent loss compensation mechanisms have been improved, ensuring the stability of long-term operation and process continuity.

[0022] In summary, the present invention solves the core problems of DBP high-temperature decomposition, tar clogging and high energy consumption in traditional maleic anhydride production through innovative system design and process optimization, and significantly improves solvent recovery efficiency and device operation reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the process flow of the present invention.

[0024] In the figure: 1. Desorption tower; 11. Desorption discharge line; 12. Rich solvent feed line; 13. Feed preheater; 14. Liquid discharge line; 15. Vertical shell and tube reboiler; 16. Crude anhydride storage tank; 17. First crude maleic anhydride production line; 18. First condenser; 19. Condenser; 2. Tail gas scrubber; 21. Vacuum system; 22. Rich solvent storage tank; 3. Extraction tower; 31. Feed line; 32. Discharge line; 33. DBP solvent discharge line; 34. Extractant circulation feed line; 35. Extractant DMI storage tank; 36. Feed pipeline; 37. Cooler; 4. Distillation tower; 41. Second crude maleic anhydride production line. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0026] Example 1 like Figure 1 As shown, the present invention provides a system for efficiently recovering DBP solvent in maleic anhydride production, the system comprising a desorption tower 1, a tail gas washing tower 2, an extraction tower 3 and a distillation tower 4; The rich solvent from the absorption unit exchanges heat with the discharge from the bottom of desorption tower 1 and then enters desorption tower 1 after being heated. The solution in the bottom of desorption tower 1 is heated by a vertical shell and tube reboiler 15, and the solution is evaporated. The vapor phase returns to desorption tower 1 to transfer heat and mass with the liquid phase material from the top of the tower. The light component is discharged from the top of the tower, and the crude maleic anhydride product can be produced in the side line. The heavy component (DBP containing maleic anhydride) gradually accumulates in the liquid phase and is discharged from the bottom of desorption tower 1. The discharge from the bottom of desorption tower 1 and the rich solvent feed undergo heat exchange in a preheater and cooling in a cooler before entering the top of extraction tower 3 as the dispersed phase. The circulating extractant DMI enters the tower from the bottom as the continuous phase and flows between the trays through a riser. The dispersed phase exists in the form of droplets and conducts mass transfer with the continuous phase. The discharge from the top of extraction tower 3 is the extractant plus maleic anhydride, which enters the distillation tower 4. The discharge from the bottom of extraction tower 3 is the DBP solvent, which is refined in the solvent regeneration unit and then reused. Distillation tower 4 separates the extractant DMI and maleic anhydride from extraction tower 3, producing a crude maleic anhydride product at the top of the tower. A portion, along with the maleic anhydride product from desorption tower 1, is fed to crude anhydride storage tank 16 for refining, while the remaining portion is condensed and returned to the top of the distillation tower. The extractant discharged from the bottom of distillation tower 4 is cooled in a cooler and then returned to extraction tower 3 for recycling. Extractant replenishment facilities are provided to compensate for losses during long-term operation.

[0027] The above technical solution improves the recovery effect of DBP solvent in maleic anhydride production from two aspects: First, it is well known that the liquid phase residence time is long and the gas phase residence time is short during the distillation process, and the thermal reaction mainly occurs in the liquid phase; reducing the thermal reaction is mainly achieved by lowering the heating temperature of the heat-sensitive substance in the distillation equipment and shortening the heating time.

[0028] Second, the reboiler 15 of the desorption tower 1 in the present invention adopts a vertical shell and tube type. The pump installed on the liquid outlet line pumps the solution from the bottom of the reboiler into the tube side. The liquid flows upward in the tube and absorbs the heat of the shell side heating medium at the same time. The temperature gradually increases. When the liquid temperature reaches the boiling point, part of the liquid vaporizes to form a vapor-liquid two-phase flow. The vaporization process is accompanied by volume expansion, which drives the mixture to flow upward, realizing forced circulation. The vapor-liquid mixture is discharged from the top of the reboiler and returns to the desorption tower.

[0029] Third, in addition, compared with other reboilers, the vertical shell and tube reboiler 15 has a high heat transfer coefficient. The material flows through the inner wall of the evaporation tube at one time and stays on the tube wall for a very short time to be heated. The DBP in the tube has no time to decompose, which is particularly suitable for the purification of heat-sensitive materials.

[0030] Second, in the existing process, the discharge temperature of the desorption tower 1 bottom is 200°C. It is superheated to 215°C in a heat exchanger before entering the post-flash tower to further remove the small amount of maleic anhydride in the desorption tower 1 bottom material. Experimental results on the thermal sensitivity of DBP show that at 215°C, the DBP solution darkens in color and produces an oily substance. In actual industrial plants, DBP solvents are prone to decomposition when subjected to excessively high operating temperatures for long periods of time, reacting with byproducts from other reactions to form high-molecular-weight tar.

[0031] Therefore, the present invention changes the post-flash tower into an extraction tower 3 + a distillation tower 4, and in the present invention, the rich solvent from the absorption unit is heat-exchanged with the discharge from the bottom of the desorption tower 1 to raise the temperature to 160-170°C, and then enters the middle of the desorption tower 1; the solution in the bottom of the desorption tower 1 is pressurized by a pump and sent to the top of the vertical shell and tube reboiler 15, and the material is heated to 190-200°C by steam; the discharge from the bottom of the desorption tower 1 is heat-exchanged and cooled to 70-90°C before entering the top of the extraction tower 3. This temperature range is neither lower than the freezing point of maleic anhydride nor affects the extraction effect.

[0032] Since extraction does not require too high a temperature, the presence of the extraction tower 3 effectively lowers the operating temperature of the tower kettle, reduces the decomposition loss of DBP, and avoids the reaction with by-products of other reactions to generate high-molecular tar substances, which may cause the device to be blocked and shut down.

[0033] In addition, in order to fully realize the function of the desorption tower 1, the bottom of the desorption tower 1 is connected to the desorption discharge line 11 through the discharge port, and the desorption discharge line 11 and the rich solvent feed line 12 are jointly connected to the feed preheater 13 for heat exchange. After the heat exchange, the rich solvent is heated to 160~170℃ and enters the desorption tower 1. The discharge from the tower bottom (mainly maleic anhydride and DBP) is cooled to 70~90℃ after heat exchange and enters the extraction tower 3; the desorption tower 1 is also provided with a liquid outlet connected to the liquid outlet line 14 at the bottom. The solution in the kettle is pressurized by the pressure pump on the liquid outlet line and is transported to the top of the vertical shell and tube reboiler 15. The solution is heated to 190~200℃ by steam in the reboiler and continuously evaporates and returns to the desorption tower 1, and undergoes heat exchange and mass transfer with the liquid phase material from the top. A first crude maleic anhydride extraction line 17, connected to a crude anhydride storage tank 16, is installed on one side of the upper portion of the desorption tower 1. The crude maleic anhydride leaves the desorption tower 1 through a discharge pump installed on the first crude maleic anhydride extraction line 17 and enters the crude anhydride storage tank 16. The discharge from the top of the desorption tower 1 is primarily acrylic acid and a small amount of maleic anhydride. After being cooled to 92-98°C in a condenser 18, the gas-liquid separation takes place. The non-condensable gas enters the tail gas scrubber 2 from the bottom, while the liquid phase is returned to the desorption tower 1 via a reflux pump.

[0034] The absorption solvent from the solvent recovery unit enters tail gas scrubber 2 from the top, where the gas and liquid phases meet in countercurrent flow, achieving mass transfer and recovering the small amount of maleic anhydride contained in the non-condensable gas. The tail gas from the top of tail gas scrubber 2 enters vacuum system 21, and the maleic anhydride-containing material at the bottom of the tower is recycled back to rich solvent storage tank 22.

[0035] To better achieve the function of separating maleic anhydride and DBP in extraction tower 3, a feed line 31 and a discharge line 32 are provided at the top of extraction tower 3. Feed line 31, containing maleic anhydride and DBP, is connected to the outlet of condenser 19. After extraction, maleic anhydride containing extractant DMI is transported to distillation tower 4 via discharge line 32 for separation. A DBP solvent discharge line 33 and a DMI recycling feed line 34 are provided at the bottom of extraction tower 3. DBP solvent discharge line 33 transports DBP recovered from maleic anhydride to the regeneration unit, while extractant recycling feed line 34 cools the extractant from distillation tower 4 through a cooler 37 and then feeds it back to extraction tower 3 for recycling. To compensate for the loss of extractant after long-term operation, a DMI storage tank 35 is also provided outside the extraction tower, connected to extractant recycling feed line 34 via a feed line 36. This tank is used to replenish extractant to the DMI recycling feed line 34. The amount of extractant replenished can be adjusted according to actual operating conditions.

[0036] In order to better realize the function of the distillation tower 4 to separate the extractant DMI and maleic anhydride, a second crude maleic anhydride production line 41 connected to the crude anhydride storage tank 16 is provided at the top of the distillation tower 4. After gas-liquid mass and heat transfer in the distillation tower 4, the maleic anhydride separated from the extractant is condensed into a liquid phase through the condenser, and a part of it is sent to the crude anhydride storage tank 16 through the second crude maleic anhydride production line 41, and the other part returns to the top of the distillation tower 4 to participate in distillation; a part of the extractant in the bottom of the distillation tower 4 is cooled by the cooler 37 and enters the extraction tower 3 for recycling, and the other part enters the preheater for preheating, and then returns to the bottom of the distillation tower 4 in the form of gas phase to participate in distillation.

[0037] Example 2 According to the device of Example 1, this embodiment discloses a production process for efficiently recovering DBP solvent in maleic anhydride production, comprising the following steps: S1, the rich solvent from the absorption unit exchanges heat with the discharge from the desorption tower 1 kettle and heats up to 165°C, and then enters the middle part of the desorption tower 1; The solution in the kettle of S2 and desorption tower 1 is pressurized by a pressure pump and then transported to the top of a vertical shell-and-tube reboiler 15, where it is heated to 192°C by steam. The solution evaporates continuously, and the gaseous material returning to the bottom of the desorption tower 1 undergoes heat and mass transfer (heat exchange and mass transfer) with the liquid material from the top of the tower, causing the heavy components to gradually accumulate in the liquid phase. The crude maleic anhydride product can be side-sampled from the upper portion of the desorption tower 1 and enters the crude anhydride storage tank 16. The discharge from the top of the desorption tower 1 is mainly acrylic acid and a small amount of maleic anhydride. After being cooled to 95°C by a condenser, it is subjected to gas-liquid separation, and the gaseous phase enters the tail gas scrubber 2, while the liquid phase returns to the top of the desorption tower 1 via a reflux pump to participate in heat and mass transfer. S3, the discharge from the bottom of the desorption tower 1 includes a maleic anhydride solution containing DBP. This material and the rich solvent are cooled to 80°C after passing through a preheater and a cooler, and then enter the extraction tower 3 from the top. As a dispersed phase, it exists in the form of droplets, first forming a liquid layer on the tower plate, and after accumulating a certain amount of energy, it passes through the sieve holes and enters the next tower plate. The bottom of the extraction tower 3 is introduced into the circulating extractant DMI from the distillation tower 4. They flow between the tower plates through the riser and transfer mass with the dispersed phase. After extraction, the extractant and maleic anhydride are sent from the top of the tower to the distillation tower 4 for separation; the DBP separated from the maleic anhydride is sent from the bottom of the tower to the regeneration unit; S4: After heat and mass transfer between the gas and liquid phases within the distillation tower 4, the maleic anhydride separated from the extractant is condensed into a liquid phase in a condenser. A portion is sent to the crude anhydride storage tank 16, and the remaining portion returns to the top of the distillation tower 4 to participate in distillation. A portion of the extractant in the bottom of the distillation tower 4 is cooled to 75°C in a cooler 37 before being recycled into the extraction tower 3. The remaining portion is preheated in a preheater and returned to the bottom of the distillation tower 4 in the vapor phase to participate in distillation. An extractant replenishment tank 35 is provided within the device, and extractant is replenished via pipeline 36 to compensate for DMI loss during long-term operation.

[0038] Although the present invention has been described above with reference to exemplary embodiments, various modifications may be made thereto and equivalent components may be substituted without departing from the scope of the present invention. In particular, the various features of the embodiments disclosed herein may be combined with one another in any manner, provided no structural conflicts exist. The omission of an exhaustive description of these combinations in this specification is solely for the sake of space and resource conservation. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but encompasses all technical solutions within the scope of the claims.

Claims

1. A system for efficiently recovering DBP solvent in maleic anhydride production, characterized by: The system includes a desorption tower, an exhaust gas scrubber, an extraction tower and a distillation tower; The desorption tower is provided with a rich solvent feed line, a desorption discharge line and a liquid outlet line connected to a vertical shell and tube reboiler; the desorption discharge line is connected to the rich solvent feed line for heat exchange, and the rich solvent from the absorption unit is heated to 160-170° C. after heat exchange with the discharge from the desorption tower kettle, and then enters the desorption tower through the rich solvent feed line; the discharge from the desorption tower kettle is cooled to 70-90° C. after heat exchange, and then enters the extraction tower through the desorption discharge line; the solution in the desorption tower kettle is transported to the top of the vertical shell and tube reboiler by a pressure pump on the liquid outlet line for forced circulation, and the solution is heated to 190-200° C. by steam, and the gas phase returns to the bottom of the desorption tower; The top feed line of the extraction tower is connected to the desorption discharge line, and the top discharge line of the extraction tower is connected to the distillation tower; the bottom of the extraction tower is provided with a DBP solvent discharge line and an extractant DMI circulation feed line; A second crude maleic anhydride extraction line is provided at the top of the distillation tower; one portion is connected to the crude anhydride storage tank, and the other portion returns to the top of the distillation tower to participate in distillation; the bottom of the distillation tower is connected to the extractant DMI circulation feed line; one portion of the extractant in the distillation tower kettle enters the extraction tower for recycling after cooling, and the other portion is preheated and returned to the bottom of the distillation tower in the form of gas to participate in distillation.

2. The system for efficiently recovering DBP solvent in maleic anhydride production according to claim 1, wherein: The vertical shell and tube reboiler is arranged outside the tower kettle, the feed port of the reboiler is connected to the bottom of the desorption tower through a liquid outlet line, and the discharge port is communicated with the lower part of the desorption tower.

3. The system for efficiently recovering DBP solvent in maleic anhydride production according to claim 1, wherein: The desorption tower kettle is connected to a desorption discharge line, and the desorption discharge line and the rich solvent feed line are connected to a feed preheater for heat exchange.

4. The system for efficiently recovering DBP solvent in maleic anhydride production according to claim 1, wherein: The material discharged from the top of the desorption tower is cooled in a condenser and then separated into gas and liquid. The gas phase enters the tail gas washing tower, and the liquid phase returns to the desorption tower as reflux.

5. The system for efficiently recovering DBP solvent in maleic anhydride production according to claim 4, wherein: The top feed line of the extraction column is communicated with the condenser outlet.

6. The system for efficiently recovering DBP solvent in maleic anhydride production according to claim 2, wherein: The system also includes an extractant DMI storage tank and a feeding pipeline, wherein the feeding pipeline is connected to the extractant DMI circulation feed line.

7. The system for efficiently recovering DBP solvent in maleic anhydride production according to claim 1, wherein: A first crude maleic anhydride production line is provided on the upper portion of the desorption tower, and the first crude maleic anhydride production line and the second crude maleic anhydride production line of the distillation tower are connected together to the crude anhydride storage tank.

8. The system for efficiently recovering DBP solvent in maleic anhydride production according to claim 1, wherein: The extraction tower is also provided with an extractant DMI storage tank connected to an extractant circulation feed line for replenishing the extractant.

9. A process for efficiently recovering DBP solvent in maleic anhydride production using the system according to any one of claims 1 to 8, characterized in that: The steps include: S1, the rich solvent from the absorption unit exchanges heat with the discharge from the desorption tower kettle and heats up to temperature T1, and then enters the middle of the desorption tower; S2, the solution in the desorption tower kettle is transported to the top of the vertical shell and tube reboiler via a pressure pump, heated to temperature T2 by steam to form liquid film evaporation, the gas phase returns to the bottom of the desorption tower for heat and mass transfer, and the heavy components gradually accumulate in the liquid phase; at the same time, the crude maleic anhydride product is collected from the upper side of the desorption tower; the top discharge of the desorption tower is mainly acrylic acid and a small amount of maleic anhydride, which is cooled to temperature T3 for gas-liquid separation, the gas phase enters the tail gas scrubber, and the liquid phase returns to the top of the desorption tower to participate in heat and mass transfer; S3, the desorption tower kettle discharge is cooled to temperature T4 and then fed into the top of the extraction tower as a dispersed phase, and is countercurrently contacted with the circulating extractant DMI entering from the bottom of the tower for mass transfer, and the extractant containing maleic anhydride is obtained at the top of the tower, and the DBP solvent is separated at the bottom of the tower; S4. The maleic anhydride extractant at the top of the extraction tower is sent to a distillation tower for separation, and a crude maleic anhydride product is obtained at the top of the tower. A portion of the extractant in the bottom of the tower is cooled to temperature T5 and then circulated to the extraction tower, and the remaining portion is vaporized and returned to the distillation tower to participate in distillation. The extractant DMI is regularly replenished to maintain system balance.

10. The process for efficiently recovering DBP solvent in maleic anhydride production according to claim 9, characterized in that: The T1 is 160-170°C, and / or the T2 is 190-200°C, and / or T3 is 92-98°C, and / or T4 is 70-90°C, and / or T5 is 70-90°C.

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