Method for continuously producing polybasic acid ester by utilizing trimellitic anhydride byproduct light component

Abstract

The invention discloses a method for continuously producing polybasic acid ester by using a trimellitic anhydride byproduct light component, and relates to the technical field of reaction kettles. The method comprises the following steps: constructing a device for continuously producing polyacid ester, wherein the device comprises a dissolving kettle, a continuous reactor, a flash tank, a dealcoholization tower, a dealcoholization tower condenser, a flash tank condenser, an alcohol-water separation tank and a finished product tank; a feeding stage; an initial temperature rise stage; a reactor preparation stage; a feeding stage; a reaction stage; a flash tank evaporation stage; a dealcoholization tower preparation stage; a dealcoholization tower refining stage; sampling and detecting. The device has the advantages that continuous production is realized through the constructed device for continuously producing polybasic acid ester, the flash tank is arranged between the continuous reactor and the dealcoholization tower, and isooctanol which is subjected to flash evaporation, energy consumption reduction and condensation separation enters the dissolving kettle again to be recycled, so that the conversion rate of raw materials and the yield of products are effectively improved, and the production cost is reduced. The catalyst is recycled, hazardous waste is reduced, and the economical efficiency of the device is improved.

Description

Technical Field

[0001] The present invention relates to the field of organic synthetic chemical industry, and particularly relates to a method for continuously producing polyacid esters by using light components by-produced from partial anhydride. Background Art

[0002] Trimellitate plasticizers have extremely excellent heat resistance, migration resistance, electrical insulation properties, etc., and combine the advantages of polyester plasticizers and monomer plasticizers. Their compatibility, processability, and low-temperature properties are all better than those of polyester plasticizers. Due to the good insulation performance, low volatility, and small migration of trioctyl trimellitate, it is widely used in wire and cable, automotive interior materials, heat-resistant wire coatings, high-performance polyesters, waterproof coatings for copper wires used in motors and electrical machines, and high-grade plastic products, as well as other products such as sheets, films, and gaskets that require heat resistance and durability.

[0003] The light components by-produced from partial anhydride and isooctanol are mixed in a certain proportion and react under appropriate temperature, pressure, and catalyst to produce polyacid esters. Its production process is simple, the operation is convenient, the production process is safe and controllable, and the price is lower than that of polyester plasticizers. It not only has the comprehensive durability of polymeric plasticizers but also has good low-temperature properties of monomeric plasticizers. At present, the plasticizer industry has developed into a plasticizer based on petrochemical industry with phthalate as the core, which is widely used in the plastic and paint industries.

[0004] At present, the production of trioctyl trimellitate and the by-production of trimellitic anhydride mainly adopt continuous, semi-continuous, and batch production processes. Compared with the continuous production process, the batch process and semi-continuous process generally have many deficiencies, such as complex operation, high labor intensity, low output per unit time, large fluctuations in product quality, waste of raw materials, high energy consumption, and low product yield. The present invention provides a production process corresponding to the device, which can continuously produce trioctyl trimellitate with high conversion rate, recycle the catalyst and solvent, high operation efficiency, automated equipment, safety and environmental protection, low energy consumption, high product yield, stable quality, and high purity, and has significant economic and social benefits. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for continuously producing polyacid esters by using light components by-produced from partial anhydride, which can solve the problems of discontinuous process flow, large waste of raw materials, low conversion rate of raw materials and product yield, and high energy consumption in the processing of producing polyacid esters in the prior art.

[0006] To solve the above technical problem, the technical solution of the present invention is as follows: including the following steps:

[0007] S1. Construct a device for continuously producing polyacid esters. The device includes a dissolution kettle, a continuous reactor, a flash tank, a de-alcoholization tower, a de-alcoholization tower condenser, a flash tank condenser, an alcohol-water separation tank, and a finished product tank;

[0008] The bottom discharge port of the dissolution kettle is connected to the feed port of the continuous reactor through a conveying pipeline a. The discharge port of the continuous reactor is connected to the top feed port of the flash tank through a conveying pipeline b. The gas-phase outlet at the top of the flash tank is connected to the flash tank condenser through a conveying pipeline c. The flash tank condenser is connected to an alcohol-water separation tank. The discharge port at the bottom of the flash tank is connected to the de-alcoholization tower through a conveying pipeline d. The gas-phase outlet at the top of the de-alcoholization tower is connected to the de-alcoholization tower condenser. The de-alcoholization tower condenser is also connected to the alcohol-water separation tank. The alcohol-water separation tank is connected to the dissolution kettle through a conveying pipeline e. The discharge port at the bottom of the de-alcoholization tower is connected to the dissolution kettle through a conveying pipeline f. The de-alcoholization tower is connected to a finished product tank;

[0009] S2. Feeding stage: In the dissolution kettle, introduce nitrogen. When the oxygen content is lower than 4%, respectively put into the dissolution kettle the light component residue of phthalic anhydride by-product, isooctanol, and a catalyst. The catalyst is tetra-isopropyl titanate;

[0010] S3. Initial heating stage: Heat and raise the temperature of the dissolution kettle. The dissolution kettle is heated to 80 - 100 °C and kept stirring at this temperature for 1 hour to completely dissolve the light component residue of phthalic anhydride by-product in isooctanol;

[0011] S4. Reactor preparation stage: Preheat the continuous reactor in advance. When the temperature is preheated to 180 °C, reserve it for use;

[0012] S5. Feeding stage: Open the bottom valve of the dissolution kettle, start the delivery pump, and feed into the continuous reactor through the conveying pipeline a;

[0013] S6. Reaction stage: Control the reaction feed rate during reaction feeding. Control the feeding time for each kettle to be 1.5 - 2.5 hours, and the residence time of the reaction materials in the continuous reactor is 2 hours;

[0014] S7. Flash tank evaporation stage: Open the heat transfer oil valve of the flash tank. When the temperature rises to 190 - 220 °C, open the vacuum pump to evacuate the flash tank. When the pressure drops to -90 kPa, feed from the continuous reactor into the flash tank through the conveying pipeline b. The gas phase in the flash tank is condensed by the flash tank condenser and enters the alcohol-water separation tank for separation. The waste water directly goes to waste water treatment, and the isooctanol enters the dissolution kettle for recycling through overflow via the conveying pipeline e. When the liquid level in the flash tank starts to rise, open the vacuum pump of the de-alcoholization tower to evacuate;

[0015] S8. Preparation stage of the alcohol stripping column: When the vacuum of the alcohol stripping column drops to -90 kPa and the liquid level of the flash tank reaches 60%, start the transfer pump to feed the alcohol stripping column through the transfer pipeline d.

[0016] S9. Refining stage of the alcohol stripping column: When the liquid level of the bottom of the alcohol stripping column rises to 30%, open the bottom of the column for heating and start alcohol stripping. The gas phase of the alcohol-water mixture at the top of the column is condensed by the condenser of the alcohol stripping column and then enters the alcohol-water separation tank for separation. The wastewater goes directly to the wastewater treatment, and the isooctanol enters the dissolution kettle through the overflow via the transfer pipeline e for recycling. A small amount of the heavy phase at the bottom of the column is quantitatively pumped into the dissolution kettle through the transfer pipeline f to recycle the catalyst contained therein.

[0017] S10. Sampling and testing: Take samples from the sampling port of the finished product outlet pipeline in the middle of the alcohol stripping column. After the samples are qualified, open the valve of the outlet pipeline in the middle of the column, and the esterification liquid in the alcohol stripping column is discharged to the finished product tank.

[0018] Further, in the step S1, the alcohol-water separation tank is connected with an alcohol-water separation tank buffer tank, and the alcohol-water separation tank buffer tank is arranged on the transfer pipeline e; the transfer pipeline a is connected with a pressure stabilizing tank.

[0019] Further, in the step S2, the molar ratio of the phthalic anhydride by-product light component residue to the isooctanol is 1:(3.2 - 4.6).

[0020] Further, in the step S2, the tetra-isopropyl titanate accounts for 0.04 - 0.12% of the mass of the phthalic anhydride by-product light component residue.

[0021] Further, in the step S6, during the reaction stage, the temperature of the 1st - 6th sections of the continuous reactor is controlled at 160 - 210 °C, and the temperature of the 7th - 12th sections is controlled at 190 - 220 °C.

[0022] Further, in the step S9, the temperature at the top of the alcohol stripping column is controlled at 120 - 150 °C, and the temperature at the bottom of the column is controlled at 190 - 220 °C.

[0023] Further, in the step S10, the qualified indexes of the sampled product are colority ≤ 40, acid value (calculated as KOH) / (mg / g) ≤ 0.15, volume resistivity / (109 Ω·m) ≥ 10, and moisture ≤ 0.1%.

[0024] The advantages of the present invention are as follows: continuous production is achieved through the constructed device for continuously producing polyacid esters. Through dissolution in the dissolution kettle, the catalyst is stirred and mixed together, and then the reaction is continuously carried out in the tubular reactor to achieve continuous reaction. A flash tank is arranged between the continuous reactor and the alcohol stripping tower, and flash evaporation is adopted to reduce energy consumption. The isooctanol separated by condensation is recycled back into the dissolution kettle, effectively improving the conversion rate of raw materials and the yield of products. The catalyst is recycled, reducing hazardous waste and improving the economic efficiency of the device. During the process of recovering the by-product of phthalic anhydride, it has extremely high value.

[0025] In the reaction stage, the continuous reactor as a whole is controlled in two sections. After segmentation, the temperature distribution in the tubular reactor is controlled, which is beneficial to the stable progress of the reaction and saves energy consumption. In the preparation stage of the alcohol stripping tower and the refining stage of the alcohol stripping tower, the liquid level of the flash tank and the bottom liquid level of the alcohol stripping tower are controlled respectively to ensure continuous and stable operation. If the liquid level is too high or too low, it is not conducive to safe operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic structural diagram of the device for continuously producing polyacid esters of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0027] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. The following embodiments can enable those skilled in the art to understand the present invention more comprehensively, but do not limit the present invention within the scope of the described embodiments.

[0028] As Figure 1 shown, the following technical solutions are adopted in this specific embodiment: A method for continuously producing polyacid esters by using the light components of phthalic anhydride by-products, comprising the following steps:

[0029] S1. Construct a device for continuously producing polyacid esters, which includes a dissolution kettle 1, a continuous reactor 2, a flash tank 3, an alcohol stripping tower 6, an alcohol stripping tower condenser 7, a flash tank condenser 4, an alcohol-water separation tank 5 and a finished product tank 8.

[0030] The bottom discharge port of the dissolution kettle 1 is connected to the feed port of the continuous reactor 2 through a conveying pipeline a. The discharge port of the continuous reactor 2 is connected to the top feed port of the flash tank 3 through a conveying pipeline b. The gas phase outlet at the top of the flash tank 3 is connected to the flash tank condenser 4 through a conveying pipeline c. The flash tank condenser 4 is connected to an alcohol-water separation tank 5. The discharge port at the bottom of the flash tank 4 is connected to the alcohol stripping tower 6 through a conveying pipeline d. The gas phase outlet at the top of the alcohol stripping tower 6 is connected to the alcohol stripping tower condenser 7. The alcohol stripping tower condenser 7 is also connected to the alcohol-water separation tank 5. The alcohol-water separation tank 5 is connected to the dissolution kettle 1 through a conveying pipeline e. The discharge port at the bottom of the alcohol stripping tower 6 is connected to the dissolution kettle 1 through a conveying pipeline f. The alcohol stripping tower 6 is connected to a finished product tank 8.

[0031] The alcohol-water separation tank 5 is connected to an alcohol-water separation tank buffer tank 9, and the alcohol-water separation tank buffer tank 9 is arranged on the conveying pipeline e; the conveying pipeline a is connected to a pressure stabilizing tank 10, and the pressure of the continuous reactor 2 is maintained through the pressure stabilizing tank 10.

[0032] Delivery pumps are respectively installed on the delivery pipeline a, the delivery pipeline d, the delivery pipeline e, and the delivery pipeline f.

[0033] S2. Feeding stage: In the dissolving kettle 1, nitrogen is introduced. When the oxygen content is lower than 4%, phthalic anhydride by-product light component residue, isooctanol and a catalyst are respectively added into the dissolving kettle 1. The catalyst is tetra-isopropyl titanate, the phthalic anhydride is trimellitic anhydride, and the molar ratio of the phthalic anhydride by-product light component residue to isooctanol is 1:(3.2 - 4.6); tetra-isopropyl titanate accounts for 0.04 - 0.12% of the mass of the phthalic anhydride by-product light component residue.

[0034] S3. Initial heating stage: Heat and raise the temperature of the dissolving kettle 1. The temperature of the dissolving kettle is raised to 80 - 100 °C, and stirring is maintained at this temperature for 1 hour to completely dissolve the phthalic anhydride by-product light component residue in isooctanol.

[0035] S4. Reactor preparation stage: Preheat the continuous reactor 2 in advance. When the temperature is preheated to 180 °C, it is standby.

[0036] S5. Feeding stage: Open the bottom valve of the dissolving kettle 1, start the delivery pump, and feed the continuous reactor 2 through the delivery pipeline a.

[0037] S6. Reaction stage: Control the reaction feeding speed during reaction feeding, control the feeding time per kettle to be 1.5 - 2.5 hours, the residence time of the reaction materials in the continuous reactor 2 is 2 hours, in the 1 - 6 sections of the continuous reactor, the temperature is controlled at 160 - 210 °C, and in the 7 - 12 sections, the temperature is controlled at 190 - 220 °C. The continuous reactor is a tubular reactor. The reactor is 12 meters long, with a total of 12 reactors, and one reactor is one section. The temperature is controlled in sections, which is conducive to the stable progress of the reaction and energy conservation.

[0038] S7. Evaporation stage of the flash tank: First, nitrogen replacement is carried out on the flash tank 3. When the oxygen content is lower than 4%, stop passing nitrogen. Open the heat transfer oil valve of the flash tank 3. When the temperature rises to 190 - 220 °C, open the vacuum pump to evacuate the flash tank 3. When the pressure drops to -90 kPa, feed into the flash tank 3 from the continuous reactor 2 through the transfer pipeline b. The gas phase in the flash tank 3 is condensed by the flash tank condenser 4 and enters the alcohol-water separation tank 5 for separation. The wastewater goes directly to wastewater treatment, and isooctanol enters the dissolution kettle 1 through overflow via the transfer pipeline e for recycling. When the liquid level of the flash tank 3 starts to rise, nitrogen replacement is carried out on the alcohol stripping column 6 first. When the oxygen content is lower than 4%, stop passing nitrogen. Open the vacuum pump of the alcohol stripping column 6 to evacuate.

[0039] S8. Preparation stage of the alcohol stripping column: When the vacuum of the alcohol stripping column 6 drops to -90 kPa and the liquid level of the flash tank 3 reaches 60%, start the transfer pump to feed into the alcohol stripping column 6 through the transfer pipeline d.

[0040] S9. Refining stage of the alcohol stripping column: When the liquid level in the bottom of the alcohol stripping column 6 rises to 30%, open the bottom for heating to start alcohol stripping. The top temperature of the alcohol stripping column 6 is controlled at 120 - 150 °C, and the bottom temperature is controlled at 190 - 220 °C. The gas phase of the alcohol-water mixture at the top of the column is condensed by the alcohol stripping column condenser 7 and then enters the alcohol-water separation tank 5 for separation. The wastewater goes directly to wastewater treatment, and isooctanol overflows to the buffer tank 9 of the alcohol-water separation tank and enters the dissolution kettle 1 through the transfer pipeline e for recycling. A small amount of heavy phase at the bottom is quantitatively pumped into the dissolution kettle 1 through the transfer pipeline f to recycle the catalyst contained therein. After producing 8 - 10 batches, it is filled into barrels.

[0041] S10. Sampling and testing: Sampling is taken from the sampling port of the finished product discharge pipeline in the middle of the alcohol stripping column 6. After the sampling is qualified, open the valve of the discharge pipeline in the middle of the column, and the esterification liquid in the alcohol stripping column 6 is discharged to the finished product tank 8; the qualified indicators of the sampled product are colority ≤ 40, acid value (calculated as KOH) / (mg / g) ≤ 0.15, volume resistivity / (109 Ω·m) ≥ 10, and water content ≤ 0.1%.

[0042] Example 1:

[0043] A method for continuously producing polyacid esters using the light components by-produced from phthalic anhydride, comprising the following steps:

[0044] S1. Construct a device for continuously producing polyacid esters, which includes a dissolution kettle 1, a continuous reactor 2, a flash tank 3, an alcohol stripping column 6, an alcohol stripping column condenser 7, a flash tank condenser 4, an alcohol-water separation tank 5, and a finished product tank 8.

[0045] The bottom discharge port of the dissolving kettle 1 is communicated with the feeding port of the continuous reactor 2 through the conveying pipeline a. The discharging port of the continuous reactor 2 is communicated with the top feeding port of the flash evaporation tank 3 through the conveying pipeline b. The gas-phase outlet at the top of the flash evaporation tank 3 is communicated with the flash evaporation tank condenser 4 through the conveying pipeline c. The flash evaporation tank condenser 4 is connected with an alcohol-water separation tank 5. The discharging port at the bottom of the flash evaporation tank 4 is communicated with the de-alcoholization tower 6 through the conveying pipeline d. The gas-phase outlet at the top of the de-alcoholization tower 6 is communicated with the de-alcoholization tower condenser 7. The de-alcoholization tower condenser 7 is also connected with the alcohol-water separation tank 5. The alcohol-water separation tank 5 is communicated with the dissolving kettle 1 through the conveying pipeline e. The discharging port at the bottom of the de-alcoholization tower 6 is communicated with the dissolving kettle 1 through the conveying pipeline f. The de-alcoholization tower 6 is connected with a finished product tank 8.

[0046] The alcohol-water separation tank 5 is communicated with an alcohol-water separation tank buffer tank 9, and the alcohol-water separation tank buffer tank 9 is arranged on the conveying pipeline e; the conveying pipeline a is connected with a pressure stabilizing tank 10.

[0047] Conveying pumps are respectively installed on the conveying pipeline a, the conveying pipeline d, the conveying pipeline e, and the conveying pipeline f.

[0048] S2. Feeding stage: In the dissolving kettle 1, nitrogen is introduced. When the oxygen content is lower than 4%, phthalic anhydride by-product light component residue, isooctanol and a catalyst are respectively added into the dissolving kettle 1. The catalyst is tetra-isopropyl titanate. The phthalic anhydride is trimellitic anhydride. The molar ratio of the phthalic anhydride by-product light component residue to isooctanol is 1:3.8; tetra-isopropyl titanate accounts for 0.08% of the mass of the phthalic anhydride by-product light component residue.

[0049] S3. Initial heating stage: Heat and raise the temperature of the dissolving kettle 1. The temperature of the dissolving kettle 1 is raised to 80 - 100 °C and kept stirring at this temperature for 1 hour to completely dissolve the phthalic anhydride by-product light component residue in isooctanol.

[0050] S4. Reactor preparation stage: Preheat the continuous reactor 2 in advance. When the temperature is preheated to 180 °C, it is reserved for use.

[0051] S5. Feeding stage: Open the bottom valve of the dissolving kettle 1, start the conveying pump, and feed the material into the continuous reactor 2 through the conveying pipeline a.

[0052] S6. Reaction stage: Control the reaction feeding speed during the reaction feeding. Control the feeding time per kettle to be 1.5 - 2.5 hours. The residence time of the reaction material in the continuous reactor 2 is 2 hours. The temperature in the 1 - 6 sections of the continuous reactor 2 is controlled at 170 - 200 °C, and the temperature in the 7 - 12 sections is controlled at 190 - 210 °C.

[0053] S7. Evaporation stage of the flash tank: First, the flash tank 3 is purged with nitrogen. When the oxygen content is lower than 4%, stop purging nitrogen. Open the heat transfer oil valve of the flash tank 3. When the temperature rises to 200 °C, open the vacuum pump to evacuate the flash tank 3. When the pressure drops to -90 kPa, feed materials from the continuous reactor 2 to the flash tank 3 through the transfer pipeline b. The gas phase in the flash tank 3 is condensed by the flash tank condenser 4 and enters the alcohol-water separation tank 5 for separation. The wastewater is directly sent to wastewater treatment, and isooctanol overflows to the buffer tank 9 of the alcohol-water separation tank and enters the dissolution kettle 1 for recycling through the transfer pipeline e. When the liquid level of the flash tank 3 starts to rise, the alcohol stripping column 5 is first purged with nitrogen. When the oxygen content is lower than 4%, stop purging nitrogen. Open the vacuum pump of the alcohol stripping column 5 to evacuate it;

[0054] S8. Preparation stage of the alcohol stripping column: When the vacuum of the alcohol stripping column 5 drops to -90 kPa and the liquid level of the flash tank 3 reaches 60%, start the transfer pump to feed materials to the alcohol stripping column 6 through the transfer pipeline d;

[0055] S9. Refining stage of the alcohol stripping column: When the liquid level of the bottom of the alcohol stripping column 6 rises to 30%, open the bottom of the column for heating to start alcohol stripping. The top temperature of the alcohol stripping column 6 is controlled at 130 °C, and the bottom temperature is controlled at 200 °C. The gas phase of the alcohol-water mixture at the top of the column is condensed by the alcohol stripping column condenser 7 and then enters the alcohol-water separation tank 5 for separation. The wastewater is directly sent to wastewater treatment, and isooctanol overflows to the buffer tank 9 of the alcohol-water separation tank and enters the dissolution kettle 1 for recycling through the transfer pipeline e. A small amount of heavy phase at the bottom of the column is quantitatively pumped into the dissolution kettle 1 through the transfer pipeline f to recycle the catalyst contained therein;

[0056] S10. Sampling and testing: Sampling is taken from the sampling port of the finished product discharge pipeline in the middle of the alcohol stripping column 6. After the sampling is qualified, open the valve of the discharge pipeline in the middle of the column, and the esterification liquid in the alcohol stripping column 6 is discharged to the finished product tank 8; The indicators of the sampled product are colority 40, acid value (calculated as KOH) / (mg / g) 0.08, volume resistivity / (109 Ω·m) 15, and water content 0.05%.

[0057] Example 2:

[0058] This Example 2 is the same as other steps of Example 1, except that: S2. Feeding stage: The molar ratio of the by-product light component residue of trimellitic anhydride to isooctanol is 1:4.2; Tetraisopropyl titanate accounts for 0.10% of the mass of the by-product light component residue of trimellitic anhydride;

[0059] S6. Reaction stage: In sections 1-6 of the continuous reactor 2, the temperature is controlled at 180 - 210 °C, and in sections 7-12, the temperature is controlled at 200 - 220 °C;

[0060] S9. Refining stage of the alcohol stripping column: The top temperature of the alcohol stripping column 6 is controlled at 120 °C, and the bottom temperature is controlled at 210 °C;

[0061] S10. Sampling and testing: The indicators of the sampled product are chromaticity 20, acid value (calculated as KOH) / (mg / g) 0.03, volume resistivity / (109Ω·m) 20, and moisture 0.02%.

[0062] Example 3:

[0063] This Example 3 is the same as Example 1 in other steps, except that: S2. Feeding stage: The molar ratio of trimellitic anhydride by-product light component residue to isooctanol is 1:4.0; tetra-isopropyl titanate accounts for 0.09% of the mass of trimellitic anhydride by-product light component residue;

[0064] S6. Reaction stage: In sections 1-6 of continuous reactor 2, the temperature is controlled at 190-200°C, and in sections 7-12, the temperature is controlled at 200-210°C;

[0065] S9. Refining stage of the alcohol removal tower: The top temperature of the alcohol removal tower 6 is controlled at 125°C, and the bottom temperature is controlled at 210°C;

[0066] S10. Sampling and testing: The indicators of the sampled product are chromaticity 25, acid value (calculated as KOH) / (mg / g) 0.06, volume resistivity / (109Ω·m) 17, and moisture 0.03%.

[0067] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for continuously producing polybasic acid esters by using a light component as a by-product of partial anhydride, characterized in that: The following steps are involved: S1. Constructing a device for continuously producing polybasic acid esters, the device comprising a dissolving kettle, a continuous reactor, a flash tank, a dealcoholization tower, a dealcoholization tower condenser, a flash tank condenser, an alcohol-water separation tank and a finished product tank; The bottom discharge port of the dissolving kettle is communicated with the feed port of the continuous reactor through a conveying pipeline a, the discharge port of the continuous reactor is communicated with the top feed port of the flash tank through a conveying pipeline b, the gas phase outlet at the top of the flash tank is communicated with the flash tank condenser through a conveying pipeline c, the flash tank condenser is connected with an alcohol-water separation tank, the discharge port at the bottom of the flash tank is communicated with a dealcoholization tower through a conveying pipeline d, the gas phase outlet at the top of the dealcoholization tower is communicated with the dealcoholization tower condenser, the dealcoholization tower condenser is also connected with the alcohol-water separation tank, the alcohol-water separation tank is communicated with the dissolving kettle through a conveying pipeline e, the discharge port at the bottom of the dealcoholization tower is communicated with the dissolving kettle through a conveying pipeline f, and the dealcoholization tower is connected with a finished product tank; S2, feeding stage: nitrogen is introduced into the dissolving kettle, and when the oxygen content is lower than 4%, the light component residue of the partial anhydride byproduct, isooctyl alcohol and a catalyst are respectively added into the dissolving kettle, wherein the catalyst is tetraisopropyl titanate; S3, initial heating stage: heating the dissolving kettle to 80-100°C and maintaining stirring at this temperature for 1 hour to completely dissolve the light component residue of the partial anhydride byproduct in isooctyl alcohol; S4, reactor preparation stage: preheat the continuous reactor in advance, and when the temperature is preheated to 180°, it is ready for use; S5, feeding stage: open the bottom valve of the dissolving kettle, start the delivery pump, and feed the continuous reactor through the delivery pipe a; S6, reaction stage: control the reaction feed rate during reaction feeding, control the feeding time of each kettle to be 1.5-2.5 hours, and the residence time of the reaction materials in the continuous reactor is 2 hours; S7, flash tank evaporation stage: open the thermal oil valve of the flash tank, when the temperature rises to 190-220°C, turn on the vacuum pump, evacuate the flash tank, when the pressure drops to -90kpa, feed the flash tank from the continuous reactor through the delivery pipe b, the gas phase in the flash tank is condensed by the flash tank condenser and enters the alcohol-water separation tank for separation, the waste water is directly used for waste water treatment, the isooctyl alcohol is recycled by overflowing through the delivery pipe e into the dissolving kettle, when the liquid level of the flash tank begins to rise, turn on the dealcoholization tower vacuum pump, evacuate; S8, dealcohol tower preparation stage: when the vacuum of the dealcohol tower drops to -90kpa and the liquid level of the flash tank reaches 60%, start the delivery pump to feed the dealcohol tower through the delivery pipeline d; S9, dealcoholization tower refining stage: when the liquid level of the dealcoholization tower kettle rises to 30%, the tower kettle is opened for heating to start dealcoholization, the gas phase of the alcohol-water mixture at the top of the tower is condensed by the dealcoholization tower condenser, and then enters the alcohol-water separation tank for separation, the waste water is directly used for waste water treatment, the isooctyl alcohol is recycled by overflowing through the conveying pipe e, and a small amount of heavy phase at the bottom of the tower is quantitatively pumped into the dissolving kettle through the conveying pipe f to recycle the catalyst contained therein; S10, sampling and testing: sampling is performed from the sampling port of the finished product discharge pipeline in the dealcoholization tower. After the sampling is qualified, the discharge pipeline valve in the tower is opened, and the esterified liquid in the dealcoholization tower is discharged to the finished product tank.

2. The method for continuously producing polybasic acid esters by using the light component of partial anhydride as a byproduct according to claim 1, characterized in that: In the step S1, the alcohol-water separation tank is connected to an alcohol-water separation tank buffer tank, and the alcohol-water separation tank buffer tank is arranged on the delivery pipeline e; the delivery pipeline a is connected to a pressure stabilizing tank.

3. The method for continuously producing polybasic acid esters by using the light component as a by-product of partial anhydride according to claim 1, characterized in that: In the step S2, the molar ratio of the partial anhydride byproduct light component residue to isooctyl alcohol is 1:(3.2-4.6).

4. The method for continuously producing polybasic acid esters by using the light component produced as a byproduct of partial anhydride according to claim 1, characterized in that: In the step S2, the tetraisopropyl titanate accounts for 0.04-0.12% of the mass of the light component residue of the partial anhydride byproduct.

5. The method for continuously producing polybasic acid esters by using the light component produced as a byproduct of partial anhydride according to claim 1, characterized in that: In step S6, during the reaction stage, the temperature of sections 1-6 of the continuous reactor is controlled at 160-210°C, and the temperature of sections 7-12 is controlled at 190-220°C.

6. The method for continuously producing polybasic acid esters by using the light component produced as a byproduct of partial anhydride according to claim 1, characterized in that: In step S9, the temperature at the top of the dealcoholization tower is controlled at 120-150°C, and the temperature at the bottom of the tower is controlled at 190-220°C.

7. The method of claim 1 for continuously producing polybasic acid esters by using a light component as a byproduct of partial anhydride, characterized in that: In the step S10, the qualified indicators of the sampled product are chromaticity ≤ 40, acid value (in terms of KOH) / (mg / g) ≤ 0.15, volume resistivity / (109Ω.m) ≥ 10, and moisture ≤ 0.1%.

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