Heat recovery distillation equipment and distillation process for polyols

Abstract

The invention discloses a heat recovery distillation device and a distillation process for polyols, and relates to the technical field of polyol distillation. The invention includes a premixed kettle, a multi-combination kettle, a low vacuum condensation component, a high vacuum condensation component, a transfer tank one, a condensate storage tank, a vacuum pump system, a dehydration tower, a high-water alcohol storage tank, a lithium bromide unit, a dealcoholization tower, a lightness removal tower, a waste liquid weighing component, a liquid phase feed preheater, a detection component, and a transfer tank two. The present invention introduces the heat from the top of the dehydration tower into the heat source pipe of the lithium bromide unit. Since the lithium bromide unit uses steam to heat the internal generator, the top heat is recovered by hot water, and the recovery efficiency is high, and the heat is used to generate steam for heating the lithium bromide unit, and the heat recovery efficiency is high. By using the dehydration tower, the dealcoholization tower and the lightness removal tower, the final product ethylene glycol and 1,4-butanediol content are ≥99.4%GC, and the water content is ≤0.55%, which greatly improves the distillation purity.

Description

Technical Field

[0001] The invention relates to the technical field of polyol distillation, and in particular to heat recovery distillation equipment and a distillation process for polyol. Background Art

[0002] Polyols are the main raw materials for preparing polyurethane adhesives. Their properties vary due to their different molecular structures. Polyols are generally soluble in water. Most polyols are viscous liquids or crystalline solids with high boiling points, strong solubility for polar substances, low toxicity and volatility.

[0003] At present, in the distillation process of polyols, the heat of the gas phase at the top of the tower is relatively large, and the heat is usually discharged directly without heat recovery. The patent with the authorization announcement number CN213192560U discloses a dehydration device for a polyol separation distillation tower. The patent is also unable to recover the heat of the gas phase at the top of the tower. In the distillation process of polyols, lithium bromide absorption refrigerators are usually used to provide a low-temperature cooling source or refrigeration capacity to help the distillation tower fractionation, especially when it is necessary to control the temperature gradient in the tower. The existing lithium bromide absorption refrigerators are used. The water is heated into steam by a heat source tube. The generator is heated by the heated steam, and the water in the solution inside it is continuously vaporized. As the water is continuously vaporized, the concentration of the lithium bromide aqueous solution in the generator continues to increase and enters the absorber. The water vapor enters the condenser and is cooled by the cooling water and condensed into liquid water. When the water in the condenser enters the evaporator through the throttle valve, it expands rapidly and vaporizes, absorbing the heat of the refrigerant water in the evaporator, thereby achieving the purpose of cooling and refrigeration. A separate heating source is required to provide heat, and the heat generated by distillation cannot be used, so the energy utilization rate is low. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a heat recovery distillation device and a distillation process for polyols.

[0005] In order to achieve the above-mentioned purpose, the present invention specifically adopts the following technical solutions:

[0006] Heat recovery and distillation equipment for polyols, including premixing kettle, multi-combination kettle, low vacuum condensation component, high vacuum condensation component, transfer tank 1, condensate storage tank, vacuum pump system, dehydration tower, high moisture alcohol storage tank, lithium bromide unit, dealcoholization tower, light removal tower, waste liquid weighing component, liquid feed preheater, detection component, transfer tank 2;

[0007] The plurality of groups of synthesis reactors are simultaneously connected to the premixing reactor through a material pump, the synthesis reactor is connected to a low vacuum condensation assembly through a low vacuum steam pipe, the synthesis reactor is connected to a high vacuum condensation assembly through a high vacuum steam pipe, the low vacuum condensation assembly and the high vacuum condensation assembly are both connected to a condensate storage tank through a transfer tank 1, the exhaust port on the top of the condensate storage tank is connected to a vacuum pump system through a vacuum buffer tank, and the exhaust port of the vacuum pump system is connected to an external incineration device;

[0008] The condensate storage tank is connected with the feed port of the dehydration tower through the front preheater, the synthesis kettle is connected with the feed port of the dehydration tower through the gas connection pipe, the gas outlet at the top of the dehydration tower is connected with the lithium bromide unit, the gas phase discharged from the gas outlet is used as the heat source of the lithium bromide unit, the discharge port of the dehydration tower is connected with the feed port of the high-moisture alcohol storage tank, the discharge port of the high-moisture alcohol storage tank is connected with the feed port of the dealcoholization tower through the alcohol guide pipe, the discharge port of the dealcoholization tower is connected with the feed port of the light-removing tower, the waste liquid discharge port at the bottom of the light-removing tower is connected with the waste liquid weighing component, the discharge port of the light-removing tower is connected with the feed port of the detection component, the liquid outlet of the detection component is simultaneously connected with the feed ports of the transfer tank 2, the dehydration tower and the liquid phase feed preheater, and the liquid outlet of the liquid phase feed preheater is connected with the feed port of the detection component.

[0009] Furthermore, the dehydration tower adopts a plate tower structure, a packing structure is adopted inside the tower, and the dehydration tower is a structure that is wide at the top and narrow at the bottom.

[0010] Furthermore, the lithium bromide unit is connected to a vacuum system and an overflow port, and the vacuum system is used to increase the inlet pressure. If the pressure is too high, the pressure is released through the overflow port.

[0011] Furthermore, the dehydration tower, the dealcoholization tower and the lightness removal tower are all made of 316L stainless steel in contact with the materials.

[0012] Furthermore, the low vacuum condensation assembly and the high vacuum condensation assembly are both composed of a group of condensers and a group of traps.

[0013] Furthermore, the working pressure of the lightness removal tower is 8-12 kPaA.

[0014] Furthermore, the waste liquid weighing assembly consists of a waste liquid barrel and a waste liquid weighing module.

[0015] Furthermore, it also includes a pure water reflux tank, which is connected to the dehydration tower.

[0016] Furthermore, the dehydration tower, the dealcoholization tower and the lightness removal tower are all heated by a reboiler.

[0017] The heat recovery distillation process of polyols comprises the following steps:

[0018] S1. Batching: 1,4-butanediol and ethylene glycol in the tank area are pumped into the premixing kettle through a feed pump, the premixing kettle is started for stirring, low-pressure steam is used for heating, and the temperature is slowly raised to 95°C. Adipic acid in the ton bag is put into the premixing kettle through a crane. After all the raw materials are added, nitrogen is introduced as a protective gas, and the temperature is continued to be raised by low-pressure steam to 110°C, and then the pressurized materials are pumped to the synthesis kettle;

[0019] S2, esterification stage: the material in the synthesis reactor is heated to 230°C by heat transfer oil, and the esterification reaction begins when the temperature reaches 140°C. The material undergoes esterification reaction and dehydration, and the water vapor and the escaped small molecular alcohol enter the dehydration tower through the gas-to-gas connection pipe, and the duration is 11 hours;

[0020] S3, ester exchange stage: after the esterification stage, vacuum is applied for 6 hours. Under vacuum conditions, small molecular esters and alcohols undergo ester exchange reactions to generate large molecular esters, and water and part of small molecular alcohols are removed. The steam generated by the reaction is divided into two paths, namely low vacuum steam and high vacuum steam. The low vacuum steam is introduced into the low vacuum condensation component through the low vacuum steam pipe, and the high vacuum steam is introduced into the high vacuum condensation component through the high vacuum steam pipe. The two paths of steam pass through the transfer tank 1 respectively, and then merge into one path to enter the condensate storage tank, and finally enter the dehydration tower through the front preheater pump. The non-condensable gas is introduced into the incineration equipment through the vacuum buffer tank under the action of the vacuum pump system for incineration;

[0021] S4, distillation system: under normal pressure, water, non-condensable gas and light components enter the lithium bromide unit from the top of the dehydration tower to condense, and after gas-liquid separation, the non-condensable gas is collected through pipelines to the incineration equipment for incineration. The lithium bromide unit is connected to a vacuum system and an overflow port. The vacuum system is used to increase the inlet pressure; if the pressure is too high, the pressure is released through the overflow port, and the high-water alcohol and light components enter the dealcoholization tower;

[0022] In the dealcoholization tower, water and small-molecule alcohol are separated under normal pressure after being heated by a reboiler. The water extracted from the top of the dealcoholization tower is condensed and then enters the sewage treatment equipment in the factory for treatment and then discharged into the sewage network of the park. The small-molecule alcohol is pumped to the light-removal tower.

[0023] In the light-removal tower, after being heated by a reboiler, small-molecule alcohols containing a certain amount of water are extracted from the top of the light-removal tower under vacuum conditions of 8-12kPaA and stored in a special storage tank in the tank area for subsequent production of polyols. The light component non-condensable gas is collected through a pipeline to the incineration equipment for incineration, and the residual liquid at the bottom of the kettle is discharged into the waste liquid weighing component for treatment after enrichment;

[0024] S5. Inspection: The finished diol discharged from the outlet of the light-removal tower enters the inspection component. If it is qualified, it enters the transfer tank 2. If it is unqualified, it enters the liquid feed preheater. The finished diol in the liquid feed preheater is evaporated and then tested by the inspection component again. If it is qualified, it enters the transfer tank 2. If it is still unqualified, it enters the dehydration tower for reprocessing. The two transfer tanks 2 are shared. The finished diol enters the tank area for collection through the transfer tank 2;

[0025] S6, analysis and cooling: After the hydroxyl value and acid value of the material in the synthesis reactor are tested to be qualified, the heating is stopped and the material is cooled to 160°C. During the sampling and testing process, a small amount of sample is refluxed for production;

[0026] S7, Filtration: The materials in the synthesis reactor are filtered through a filter and sent to the polyol preparation reactor under nitrogen pressure for standby use.

[0027] The beneficial effects of the present invention are as follows:

[0028] 1. The present invention introduces the heat from the top of the dehydration tower into the heat source pipe of the lithium bromide unit. Since the lithium bromide unit uses steam to heat the internal generator, the top heat is recovered by hot water with high recovery efficiency. In addition, the heat is used to generate steam to heat the lithium bromide unit, with high heat recovery efficiency.

[0029] 2. The present invention uses a dehydration tower, a dealcoholization tower and a lightness removal tower in combination, so that the final product ethylene glycol and 1,4-butanediol content is ≥99.4% GC and the water content is ≤0.55%, which greatly improves the distillation purity. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the equipment for the batching and esterification stages of the present invention;

[0031] Figure 2 is a schematic diagram of the equipment for the transesterification stage of the present invention;

[0032] Figure 3 It is a schematic diagram of the dehydration tower equipment of the distillation system of the present invention;

[0033] Figure 4 It is a schematic diagram of the dealcoholization tower and lightness removal tower equipment of the distillation system of the present invention;

[0034] Figure 5 It is a schematic diagram of the equipment in the detection stage of the present invention.

[0035] Figure numerals: 1. premixing kettle; 2. synthesis kettle; 201. low vacuum steam pipe; 202. high vacuum steam pipe; 203. gas-to-gas connection pipe; 3. low vacuum condensation assembly; 4. high vacuum condensation assembly; 5. transfer tank one; 6. condensate storage tank; 7. vacuum buffer tank; 8. vacuum pump system; 9. dehydration tower; 901. pre-preheater; 10. reboiler; 11. high-water alcohol storage tank; 1101. alcohol guide pipe; 12. lithium bromide unit; 13. pure water reflux tank; 14. dealcoholization tower; 15. lightness removal tower; 16. waste liquid weighing assembly; 17. liquid feed preheater; 18. detection assembly; 19. transfer tank two. DETAILED DESCRIPTION

[0036] To make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0037] like Figure 1-Figure 5 As shown, the heat recovery and distillation equipment of polyols includes a premixing kettle 1, a multi-combination kettle 2, a low vacuum condensation component 3, a high vacuum condensation component 4, a transfer tank 1 5, a condensate storage tank 6, a vacuum pump system 8, a dehydration tower 9, a high-water alcohol storage tank 11, a lithium bromide unit 12, a dealcoholization tower 14, a lightness removal tower 15, a waste liquid weighing component 16, a liquid feed preheater 17, a detection component 18, and a transfer tank 2 19;

[0038] The multi-combination synthesis kettle 2 is simultaneously connected to the premixing kettle 1 through a material pump, the synthesis kettle 2 is connected to the low vacuum condensation component 3 through a low vacuum steam pipe 201, the synthesis kettle 2 is connected to the high vacuum condensation component 4 through a high vacuum steam pipe 202, the low vacuum condensation component 3 and the high vacuum condensation component 4 are both connected to the condensate storage tank 6 through a transfer tank 5, the exhaust port on the top of the condensate storage tank 6 is connected to the vacuum pump system 8 through a vacuum buffer tank 7, and the exhaust port of the vacuum pump system 8 is connected to the external incineration equipment;

[0039] The condensate storage tank 6 is connected to the feed port of the dehydration tower 9 through the preheater 901, the synthesis reactor 2 is connected to the feed port of the dehydration tower 9 through the gas connection pipe 203, the gas outlet at the top of the dehydration tower 9 is connected to the lithium bromide unit 12, the gas phase discharged from the gas outlet is used as the heat source of the lithium bromide unit 12, the discharge port of the dehydration tower 9 is connected to the feed port of the high-water alcohol storage tank 11, and the discharge port of the high-water alcohol storage tank 11 is connected to the dealcohol tower 14 through the alcohol guide pipe 1101. The feed port of the dealcoholization tower 14 is connected to the feed port of the light-removing tower 15, the waste liquid outlet at the bottom of the light-removing tower 15 is connected to the waste liquid weighing component 16, the discharge port of the light-removing tower 15 is connected to the feed port of the detection component 18, the liquid outlet of the detection component 18 is simultaneously connected to the feed ports of the transfer tank 19, the dehydration tower 9 and the liquid-phase feed preheater 17, and the liquid outlet of the liquid-phase feed preheater 17 is connected to the feed port of the detection component 18.

[0040] The synthesis reactor 2 can be provided with nine groups, and the nine groups of synthesis reactors 2 share a set of distillation system. The 1,4-butanediol and ethylene glycol in the tank area are pumped into the premixing reactor 1 through a material pump, and then pumped into the synthesis reactor 2 after mixing. The materials in the synthesis reactor 2 undergo esterification reaction, and the materials undergo esterification reaction and dehydration. The water vapor and the escaped small molecular alcohol enter the dehydration tower 9 through the gas-connected pipe 203. After the esterification stage is completed, the vacuum is drawn for 6 hours. Under vacuum conditions, the small molecular ester and the alcohol undergo ester exchange reaction to generate large molecular ester, and water and part of the small molecular alcohol are removed. The steam to be generated is divided into two paths, namely low vacuum steam and high vacuum steam. The low vacuum steam is introduced into the low vacuum condensation component 3 through the low vacuum steam pipe 201, and the high vacuum steam is introduced into the high vacuum condensation component 4 through the high vacuum steam pipe 202. The two steam paths pass through the transfer tank 5 respectively, and then merge into one path to enter the condensate storage tank 6, and finally enter the dehydration tower 9 through the front preheater 901 pump. The non-condensable gas is introduced into the incineration equipment through the vacuum buffer tank 7 under the action of the vacuum pump system 8, which can greatly increase the esterification yield;

[0041] Under normal pressure conditions, water, non-condensable gas and light components enter the lithium bromide unit 12 from the top of the dehydration tower 9 for condensation. After gas-liquid separation, the non-condensable gas is collected through a pipeline to the incineration equipment for incineration. The lithium bromide unit 12 is connected to a vacuum system and an overflow port. The vacuum system is used to increase the inlet pressure. If the pressure is too high, the pressure is released through the overflow port. The high-water alcohol and light components enter the dealcoholization tower 14 and are heated by the reboiler 10. Under normal pressure conditions, water is separated from small-molecule alcohol. The water extracted from the top of the dealcoholization tower 14 enters the sewage treatment equipment in the factory after condensation and is discharged into the park sewage network. The small-molecule alcohol is pumped to the light-removal tower 15 and heated by the reboiler 10. Under vacuum conditions, the small-molecule alcohol containing a certain amount of water is discharged from the dehydration tower 14. The top of the light-removal tower 15 is extracted and stored in a special storage tank in the tank area for the subsequent production of polyols. The light component non-condensable gas is collected through a pipeline to the incineration equipment for incineration. The residual liquid at the bottom of the kettle is discharged into the waste liquid weighing component 16, and is processed after enrichment. The finished diol discharged from the discharge port of the light-removal tower 15 enters the detection component 18. If it is qualified, it enters the transfer tank 2 19. If it is unqualified, it enters the liquid feed preheater 17. The finished diol in the liquid feed preheater 17 is evaporated and then tested by the detection component 18 again. If it is qualified, it enters the transfer tank 2 19. If it is still unqualified, it enters the dehydration tower 9 for reprocessing. The two transfer tanks 2 19 are shared. The finished diol enters the tank area through the transfer tank 2 19 for collection;

[0042] The operating pressure of the light-removal tower 15 is about 8-12 kPaA, and the average alcohol processing capacity can reach 1600 kg / h and the maximum is 2800 kg / h. In the process of alcohol production, water ≥3%, ethylene glycol ≤97%, 1,4-butanediol ≤97%, and a trace amount of tetrahydrofuran are contained. The top liquid outlet continuously produces a mixed alcohol solution that meets the requirements, and the bottom liquid outlet intermittently discharges high boiling products. Finally, the ethylene glycol and 1,4-butanediol content of the mixed alcohol solution is ≥99.4% GC, and the water content is ≤0.55%. The purity is greatly improved. The content is ≥99.4% GC, which means that the purity of ethylene glycol and 1,4-butanediol is very high. GC refers to gas chromatography analysis. The water content is less than or equal to 0.55%, which means that its water content is low, which meets the requirements for raw materials in industrial applications.

[0043] On the basis of the above embodiments, the dehydration tower 9 adopts a plate tower structure, a packing structure is adopted in the tower, the dehydration tower 9 is a structure that is wide at the top and narrow at the bottom, and a variable diameter tower. The upper half of the dehydration tower 9 is a distillation section with a large load, so a larger tower diameter is set, and the lower half is a stripping section with a small load, so a smaller tower diameter is set, and the distillation effect is good.

[0044] On the basis of the above embodiment, the lithium bromide unit 12 is also connected to a vacuum system and an overflow port, and the vacuum system is used to increase the inlet pressure. If the pressure is too high, the pressure is released through the overflow port, and the operation is stable.

[0045] On the basis of the above embodiment, the dehydration tower 9, the dealcoholization tower 14 and the lightness removal tower 15 are all made of 316L stainless steel in contact with the materials, which has good corrosion resistance and strong mechanical properties.

[0046] On the basis of the above embodiments, the low vacuum condensation component 3 and the high vacuum condensation component 4 are both composed of a group of condensers and a group of collectors, and the condensation effect is good.

[0047] On the basis of the above embodiment, it is also included that the working pressure of the lightness removal tower 15 is 8-12 kPaA.

[0048] On the basis of the above embodiment, the waste liquid weighing component 16 is further comprised of a waste liquid barrel and a waste liquid weighing module, the waste liquid is collected by the waste liquid barrel, and the waste liquid weighing module weighs the waste liquid.

[0049] Furthermore, it also includes a pure water reflux tank 13 , which is connected to the dehydration tower 9 .

[0050] Furthermore, the dehydration tower 9 , the dealcoholization tower 14 , and the lightness removal tower 15 are all heated by the reboiler 10 .

[0051] The heat recovery distillation process of polyols comprises the following steps:

[0052] S1, batching: 1,4-butanediol and ethylene glycol in the tank area are pumped into the premixing kettle 1 through the feed pump, the premixing kettle 1 is started for stirring, low-pressure steam is used for heating, and the temperature is slowly raised to 95°C, and the adipic acid in the ton bag is put into the premixing kettle 1 through the crane. After all the raw materials are added, nitrogen is introduced as a protective gas, and the temperature is continued to be raised by low-pressure steam to 110°C, and then the material is pumped to the synthesis kettle 2;

[0053] S2, esterification stage: the material in the synthesis reactor 2 is heated to 230°C by heat transfer oil, and the esterification reaction begins when the temperature reaches 140°C. The material undergoes esterification reaction and dehydration, and the water vapor and the escaped small molecular alcohol enter the dehydration tower 9 through the gas-to-gas connection pipe 203, and the duration is 11 hours;

[0054] S3, transesterification stage: after the esterification stage, vacuum is applied for 6 hours. Under vacuum conditions, small molecular esters and alcohols undergo transesterification reactions to generate large molecular esters, and water and part of small molecular alcohols are removed. The steam generated by the reaction is divided into two paths, namely low vacuum steam and high vacuum steam. The low vacuum steam is introduced into the low vacuum condensation component 3 through the low vacuum steam pipe 201, and the high vacuum steam is introduced into the high vacuum condensation component 4 through the high vacuum steam pipe 202. The two paths of steam pass through the transfer tank 5 respectively, and then merge into one path to enter the condensate storage tank 6, and finally enter the dehydration tower 9 through the front preheater 901 pump. The non-condensable gas is introduced into the incineration equipment through the vacuum buffer tank 7 under the action of the vacuum pump system 8 for incineration;

[0055] S4, distillation system: under normal pressure, water, non-condensable gas and light components enter the lithium bromide unit 12 from the top of the dehydration tower 9 for condensation. After gas-liquid separation, the non-condensable gas is collected through a pipeline to the incineration equipment for incineration. The lithium bromide unit 12 is connected to a vacuum system and an overflow port. The vacuum system is used to increase the inlet pressure. If the pressure is too high, the pressure is released through the overflow port, and the high-water alcohol and light components enter the dealcoholization tower 14.

[0056] In the dealcoholization tower 14, water and small molecule alcohol are separated under normal pressure after being heated by the reboiler 10. The water extracted from the top of the dealcoholization tower 14 is condensed and then enters the sewage treatment equipment in the factory for treatment and then discharged into the sewage network of the park. The small molecule alcohol is pumped to the light removal tower 15;

[0057] In the light removal tower 15, after being heated by the reboiler 10, the small molecular alcohol containing a certain amount of water under the vacuum condition of 8-12kPaA is extracted from the top of the light removal tower 15 and stored in a special storage tank in the tank area for subsequent production of polyols. The light component non-condensable gas is collected through a pipeline to the incineration equipment for incineration, and the residual liquid at the bottom of the kettle is discharged into the waste liquid weighing component 16 for treatment after enrichment;

[0058] S5, detection: the finished diol discharged from the outlet of the lightness removal tower 15 enters the detection component 18, and if it is qualified, it enters the transfer tank 2 19, and if it is unqualified, it enters the liquid feed preheater 17. The finished diol in the liquid feed preheater 17 is evaporated and then tested by the detection component 18 again. If it is qualified, it enters the transfer tank 2 19, and if it is still unqualified, it enters the dehydration tower 9 for reprocessing. The two transfer tanks 2 19 are shared. The finished diol enters the tank area through the transfer tank 2 19 for collection;

[0059] S6, analysis, cooling: After the hydroxyl value and acid value of the material in the synthesis reactor 2 are tested to be qualified, the heating is stopped and the material is cooled to 160°C. During the sampling and testing process, a small amount of sample is refluxed for production;

[0060] S7, Filtration: The material in the synthesis reactor 2 is filtered through a filter and sent to the polyol preparation reactor under nitrogen pressure for standby use.

[0061] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A heat recovery and distillation device for polyols, comprising a premixing kettle (1), characterized in that: It also includes a plurality of integrated kettles (2), a low vacuum condensation component (3), a high vacuum condensation component (4), a transfer tank 1 (5), a condensate storage tank (6), a vacuum pump system (8), a dehydration tower (9), a high-water alcohol storage tank (11), a lithium bromide unit (12), a dealcoholization tower (14), a lightness removal tower (15), a waste liquid weighing component (16), a liquid feed preheater (17), a detection component (18), and a transfer tank 2 (19); A plurality of groups of the synthesis reactors (2) are simultaneously connected to the premixing reactor (1) via a material pump; the synthesis reactor (2) is connected to a low vacuum condensation assembly (3) via a low vacuum steam pipe (201); the synthesis reactor (2) is connected to a high vacuum condensation assembly (4) via a high vacuum steam pipe (202); the low vacuum condensation assembly (3) and the high vacuum condensation assembly (4) are both connected to a condensate storage tank (6) via a transfer tank (5); an exhaust port at the top of the condensate storage tank (6) is connected to a vacuum pump system (8) via a vacuum buffer tank (7); and an exhaust port of the vacuum pump system (8) is connected to an external incineration device; The condensate storage tank (6) is connected to the feed port of the dehydration tower (9) through the preheater (901), the synthesis reactor (2) is connected to the feed port of the dehydration tower (9) through the gas connection pipe (203), the gas outlet at the top of the dehydration tower (9) is connected to the lithium bromide unit (12), the gas phase discharged from the gas outlet is used as the heat source of the lithium bromide unit (12), the discharge port of the dehydration tower (9) is connected to the feed port of the high-moisture alcohol storage tank (11), and the discharge port of the high-moisture alcohol storage tank (11) is connected to the dealcohol tower (14) through the alcohol guide pipe (1101). ), the discharge port of the dealcoholization tower (14) is connected to the feed port of the light-removal tower (15), the waste liquid discharge port at the bottom of the light-removal tower (15) is connected to the waste liquid weighing component (16), the discharge port of the light-removal tower (15) is connected to the feed port of the detection component (18), the liquid outlet of the detection component (18) is simultaneously connected to the feed ports of the transfer tank 2 (19), the dehydration tower (9) and the liquid-phase feed preheater (17), and the liquid outlet of the liquid-phase feed preheater (17) is connected to the feed port of the detection component (18).

2. The heat recovery distillation equipment for polyols according to claim 1, characterized in that: The dehydration tower (9) adopts a plate tower structure, and a filler structure is adopted inside the tower. The dehydration tower (9) is a structure that is wide at the top and narrow at the bottom.

3. The heat recovery distillation equipment for polyols according to claim 1, characterized in that: The lithium bromide unit (12) is connected to a vacuum system and an overflow port. The vacuum system is used to increase the inlet pressure. If the pressure is too high, the pressure is released through the overflow port.

4. The heat recovery distillation equipment for polyols according to claim 1, characterized in that: The dehydration tower (9), the dealcoholization tower (14) and the lightness removal tower (15) are all made of 316L stainless steel in contact with the material.

5. The heat recovery distillation equipment for polyols according to claim 1, characterized in that: The low vacuum condensation component (3) and the high vacuum condensation component (4) are both composed of a group of condensers and a group of traps.

6. The heat recovery distillation equipment for polyols according to claim 1, characterized in that: The working pressure of the lightness removal tower (15) is 8-12 kPaA.

7. The heat recovery distillation equipment for polyols according to claim 1, characterized in that: The waste liquid weighing component (16) consists of a waste liquid barrel and a waste liquid weighing module.

8. The heat recovery and distillation equipment for polyols according to claim 1, characterized in that: It also includes a pure water reflux tank (13), which is connected to the dehydration tower (9).

9. The heat recovery distillation equipment for polyols according to claim 1, characterized in that: The dehydration tower (9), the dealcoholization tower (14), and the lightness removal tower (15) are all heated by a reboiler (10).

10. A heat recovery distillation process for polyols, using the heat recovery distillation equipment for polyols as described in claims 1 to 9, characterized in that: The following steps are involved: S1. Batching: 1,4-butanediol and ethylene glycol from the tank area are pumped into the premixing kettle (1) through a feed pump, the premixing kettle (1) is opened for stirring, low-pressure steam is used for heating, and the temperature is slowly raised to 95° C. Adipic acid in a ton bag is added into the premixing kettle (1) through a crane. After all the raw materials are added, nitrogen is introduced as a protective gas, and the temperature is continued to be raised by low-pressure steam until 110° C., and then the materials are pumped and pressed into the synthesis kettle (2); S2, esterification stage: the material in the synthesis reactor (2) is heated to 230°C by heat transfer oil. When the temperature reaches 140°C, the esterification reaction begins. The material undergoes esterification reaction and dehydration. The water vapor and the escaped small molecular alcohol enter the dehydration tower (9) through the gas-to-gas connection pipe (203). The duration is 11 hours. S3, transesterification stage: After the esterification stage, the vacuum is drawn for 6 hours. Under vacuum conditions, small molecular esters and alcohols undergo transesterification reactions to generate large molecular esters, and water and part of small molecular alcohols are removed. The steam generated by the reaction is divided into two paths, namely low vacuum steam and high vacuum steam. The low vacuum steam is introduced into the low vacuum condensation component (3) through the low vacuum steam pipe (201), and the high vacuum steam is introduced into the high vacuum condensation component (4) through the high vacuum steam pipe (202). The two steam paths pass through the transfer tank 1 (5) respectively, and then merge into one path to enter the condensate storage tank (6), and finally enter the dehydration tower (9) through the front preheater (901) pump. The non-condensable gas is introduced into the incineration equipment through the vacuum buffer tank (7) under the action of the vacuum pump system (8) for incineration; S4, distillation system: under normal pressure, water, non-condensable gas and light components enter the lithium bromide unit (12) from the top of the dehydration tower (9) for condensation. After gas-liquid separation, the non-condensable gas is collected through a pipeline to the incineration equipment for incineration. The lithium bromide unit (12) is connected to a vacuum system and an overflow port. The vacuum system is used to increase the inlet pressure. If the pressure is too high, the pressure is released through the overflow port, and the high-water alcohol and light components enter the dealcoholization tower (14); In the dealcoholization tower (14), water and small-molecule alcohol are separated under normal pressure after being heated by the reboiler (10). The water extracted from the top of the dealcoholization tower (14) is condensed and then enters the sewage treatment equipment in the factory for treatment and then discharged into the sewage network of the park. The small-molecule alcohol is pumped to the light-removal tower (15); In the light-removal tower (15), after being heated by the reboiler (10), the small molecular alcohol containing a certain amount of water is extracted from the top of the light-removal tower (15) under the vacuum condition of 8-12 kPaA and stored in a special storage tank in the tank area for subsequent production of polyols. The light component non-condensable gas is collected through a pipeline to the incineration equipment for incineration, and the residual liquid at the bottom of the kettle is discharged into the waste liquid weighing component (16) for treatment after enrichment. S5. Inspection: The finished diol discharged from the outlet of the lightness removal tower (15) enters the inspection component (18). If it is qualified, it enters the transfer tank 2 (19). If it is unqualified, it enters the liquid phase feed preheater (17). The finished diol in the liquid phase feed preheater (17) is evaporated and then inspected again by the inspection component (18). If it is qualified, it enters the transfer tank 2 (19). If it is still unqualified, it enters the dehydration tower (9) for reprocessing. The two transfer tanks 2 (19) share one another. The finished diol enters the tank area for collection through the transfer tank 2 (19); S6, analysis and cooling: After the hydroxyl value and acid value of the material in the synthesis reactor (2) are tested to be qualified, the heating is stopped and the material is cooled to 160°C. During the sampling and testing process, a small amount of sample is refluxed for production; S7, Filtration: The material in the synthesis reactor (2) is filtered through a filter and sent to the polyol preparation reactor under nitrogen pressure for standby use.

Images