Energy-saving process for solvent recovery in butadiene rubber production process

Abstract

The invention relates to an energy-saving process for recovering a solvent in a butadiene rubber production process, which comprises the following steps of: in the butadiene rubber production process, removing water from a solvent, butadiene and a crude solvent recovered by condensation which are flashed from a rubber solution tank through a solvent dehydrating tower, and then removing heavy component impurities in the solvent and recovering the solvent and butadiene by adopting two-effect or three-effect rectification; wherein the first solvent de-heavy tower is used for recovering butadiene and part of the solvent, and the second solvent de-heavy tower or the second solvent de-heavy tower and the third solvent de-heavy tower are used for recovering the solvent and removing heavy components. According to the invention, a butadiene recovery tower is omitted, butadiene and the solvent are recovered through the first solvent de-heavy tower, and the recovered butadiene and the solvent are mixed with the second solvent de-heavy tower or the second solvent de-heavy tower and the third solvent de-heavy tower and then cyclically enter a polymerization kettle of a polymerization unit, so that the use amount of steam and circulating water in the recovery process of the solvent and butadiene can be reduced; the energy consumption is reduced; meanwhile, through flow optimization, a butadiene recovery tower system is omitted, the number of equipment is reduced, and the construction investment is saved.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical industry and relates to an energy-saving process for solvent recovery in the production process of butadiene rubber. Background Art

[0002] In the production process of butadiene rubber, the polymerization reaction conversion rate is affected by the quality of the polymerization raw materials and the polymerization process conditions. The single-pass conversion rate of the polymerization reaction reaches 80%-90%. Among them, the unreacted 10%-20% butadiene is flashed out in the glue tank and recycled to the polymerization kettle after refining; the butadiene polymerization process is completed by solution polymerization. The polymerization reaction requires a large amount of solvent. The solvent is stripped out in the flash evaporation and condensation section of the glue tank and then recycled to the polymerization kettle after refining in the solvent refining section.

[0003] The existing butadiene production process uses solvent dehydration tower, solvent deweighting tower and butadiene recovery tower for solvent recovery and refining; or the solvent dehydration tower and solvent deweighting tower are combined into one tower, and the solvent is extracted from the side line; or the solvent deweighting tower uses two-effect or three-effect distillation. At present, the function of the solvent dehydration tower is to separate the butadiene from the solvent in the recovered crude solvent and remove the water and light component impurities in the recovered solvent; during the solvent dehydration process, butadiene, water, light components of the solvent and other impurities are removed from the top of the tower. The material at the top of the solvent dehydration tower enters the butadiene recovery tower to complete the separation of butadiene and solvent; the task of the solvent deweighting tower is to remove the heavy component impurities in the recovered solvent. Because the solvent dehydration tower of the existing process technology not only dehydrates, but also separates the butadiene from the solvent in the crude solvent, the reflux volume of the solvent dehydration tower is very large, and the steam and circulating water consumption of the dehydration tower is large, resulting in high energy consumption of solvent refining. Summary of the invention

[0004] The invention aims to provide an energy-saving process for solvent recovery in the production process of butadiene rubber, wherein butadiene and a solvent are recovered together through a solvent deweighting tower, butadiene is not recovered separately, so that the amount of steam and circulating water used in the process of recovering the solvent and butadiene can be reduced, energy consumption can be reduced, and thus production costs can be reduced; at the same time, through process optimization, a butadiene recovery tower system is eliminated, the number of equipment is reduced, and construction investment is saved.

[0005] The invention discloses an energy-saving process for solvent recovery in the production process of butadiene rubber. In the production process of butadiene rubber, the solvent flashed out from the rubber liquid tank, butadiene and the crude solvent recovered by condensation are dehydrated in a solvent dehydration tower, and then a double-effect or triple-effect distillation is adopted to remove heavy component impurities in the solvent and recover the solvent and butadiene. The first solvent dehydration tower is used to recover butadiene and part of the solvent, and the second solvent dehydration tower or the second solvent dehydration tower and the third solvent dehydration tower are used to recover the solvent and remove the heavy component.

[0006] This energy-saving process eliminates the butadiene recovery tower (the butadiene recovery tower is used to recover butadiene in the solvent alone), and butadiene and solvent are recovered together through the solvent degravation tower 1. After recovery, the recovered solvent is mixed with the solvent recovered by the solvent degravation tower 2 or the solvent degravation tower 2 and the solvent degravation tower 3, and then circulated into the polymerization kettle of the polymerization unit, which can reduce the use of steam and circulating water in the process of solvent and butadiene recovery, thereby reducing energy consumption. At the same time, through process optimization, the butadiene recovery tower system is eliminated, the number of equipment is reduced, and construction investment is saved.

[0007] The energy-saving process for solvent recovery of the present invention is further described below: The equipment for solvent removal and double-effect distillation in the production of butadiene rubber adopts energy-saving technology of solvent recovery such as Figure 1 As shown, the process is as follows: The crude solvent containing butadiene flashed out from the glue tank and the crude solvent recovered by condensation enter the middle of the solvent dehydration tower, where the water in the crude solvent is removed. Part of the solvent, butadiene and water come out from the top of the solvent dehydration tower, which are condensed by the dehydration tower condenser, and the condensate flows into the dehydration tower reflux tank. In the reflux tank, the oil phase and the water phase are separated, the water phase is discharged into the sewage system, and the oil phase is sent to the solvent dehydration tower as reflux through the dehydration tower reflux pump. The dehydration tower kettle is the solvent that has been dehydrated, which is sent to the solvent dehydration tower by pressure difference. In the solvent de-weighting tower 1, part of the solvent and butadiene removed from the heavy components are evaporated from the top of the tower. The solvent and butadiene vapor phase evaporated from the top of the tower enter the cooler of the de-weighting tower 1 for condensation and cooling, and then flow into the reflux tank. The solvent and butadiene mixture in the reflux tank is partially sent to the top of the solvent de-weighting tower 1 as reflux by the reflux pump of the de-weighting tower 1. Part of the butadiene solvent mixture is mixed with the refined solvent from the reflux pump of the solvent de-weighting tower 2 and sent to the refined solvent tank as a qualified refined solvent and butadiene mixture, and then recycled to the polymerization unit. The bottom of the solvent de-weighting tower 1 contains the solvent containing the heavy components, which is pumped to the solvent de-weighting tower 2 by the bottom liquid pump of the de-weighting tower 1.

[0008] In the solvent de-weighting tower 2, the solvent removed from the heavy component is evaporated from the top of the tower, and the solvent vapor evaporated from the top of the tower enters the solvent de-weighting tower 1 reboiler as its heat source. The vapor phase is condensed in the de-weighting tower 1 reboiler. The condensate is heat-exchanged with the dehydration tower feed solvent in the solvent second preheater, and then cooled by the de-weighting tower 2 cooler and flows into the de-weighting tower 2 reflux tank. The solvent in the reflux tank is partially sent back to the top of the solvent de-weighting tower 2 as reflux by the de-weighting tower 2 reflux pump, and part of it is mixed with the refined solvent and butadiene mixture from the solvent de-weighting tower 1 reflux pump and sent to the refined solvent tank and then to the polymerization unit for recycling. The bottom of the solvent de-weighting tower 2 contains the solvent containing the heavy component, which is sent to the residual liquid recovery tower by differential pressure to further recover the solvent.

[0009] The equipment for solvent removal and triple-effect distillation in the production of butadiene rubber adopts energy-saving technology of solvent recovery such as Figure 2 As shown, the process is as follows: The crude solvent containing butadiene flashed out from the glue tank and the crude solvent recovered by condensation enter the middle of the solvent dehydration tower, where the water in the crude solvent is removed. Part of the solvent, butadiene and water come out from the top of the solvent dehydration tower, which are condensed by the dehydration tower condenser, and the condensate flows into the dehydration tower reflux tank. In the reflux tank, the oil phase and the water phase are separated, the water phase is discharged into the sewage system, and the oil phase is sent to the solvent dehydration tower as reflux through the dehydration tower reflux pump. The dehydration tower kettle is the solvent that has been dehydrated, which is sent to the solvent dehydration tower by pressure difference. In the solvent de-weighting tower 1, part of the solvent and butadiene removed from the heavy component are evaporated from the top of the tower. The solvent and butadiene vapor phase evaporated from the top of the tower enter the cooler of the de-weighting tower 1 for condensation and cooling, and then flow into the reflux tank. The solvent and butadiene mixture in the reflux tank is partially sent to the top of the solvent de-weighting tower 1 as reflux by the reflux pump of the de-weighting tower 1. Part of the butadiene solvent mixture is mixed with the refined solvent from the reflux pump of the solvent de-weighting tower 2 and the reflux pump of the de-weighting tower 3, and then sent to the refined solvent tank as a qualified refined solvent and butadiene mixture, and then recycled to the polymerization unit. The bottom of the solvent de-weighting tower 1 contains the solvent containing the heavy component, which is pumped to the solvent de-weighting tower 2 by the bottom liquid pump of the de-weighting tower 1.

[0010] In the solvent de-weighting tower 2, the solvent removed from the heavy component is evaporated from the top of the tower, and the solvent vapor evaporated from the top of the tower enters the solvent de-weighting tower 1 reboiler as its heat source. The vapor phase is condensed in the de-weighting tower 1 reboiler. The condensate is heat-exchanged with the dehydration tower feed solvent in the solvent second preheater, and then cooled by the de-weighting tower 2 cooler and flows into the de-weighting tower 2 reflux tank. The solvent in the reflux tank is partially sent back to the top of the solvent de-weighting tower 2 by the de-weighting tower 2 reflux pump as reflux, and part of it is mixed with the refined solvent and butadiene mixture from the solvent de-weighting tower 1 reflux pump and the refined solvent from the de-weighting tower 3 reflux pump and then sent to the refined solvent tank and then recycled to the polymerization unit. The tower kettle of the solvent de-weighting tower 2 is the solvent containing the heavy component, which is pumped to the de-weighting tower 3 by the tower kettle of the de-weighting tower 2.

[0011] In the solvent de-weighting tower, the solvent removed from the heavy component is evaporated from the top of the tower, and the solvent vapor evaporated from the top of the tower enters the reboiler of the solvent de-weighting tower 2 as its heat source. After the vapor phase is condensed and cooled in the reboiler of the solvent de-weighting tower 2, it flows into the reflux tank of the solvent de-weighting tower 2. The solvent in the reflux tank is partially sent back to the top of the solvent de-weighting tower 3 by the reflux pump of the heavy de-weighting tower 3 as reflux, and part of it is mixed with the mixture of the fine solvent and butadiene from the reflux pump of the solvent de-weighting tower 1 and the fine solvent from the reflux pump of the heavy de-weighting tower 2 as the refined solvent, and then sent to the refined solvent tank and then to the polymerization unit for recycling. The bottom of the solvent de-weighting tower 3 contains the solvent containing the heavy component, which is sent to the residual liquid recovery tower by differential pressure to further recover the solvent.

[0012] Features and effects of the present invention The energy-saving process of the present invention eliminates the butadiene recovery tower (the butadiene recovery tower is used to recover butadiene in the solvent alone), butadiene and the solvent are recovered together through the first solvent de-weighting tower, and after recovery, the recovered solvent is mixed with the solvent recovered through the second solvent de-weighting tower or the second solvent de-weighting tower and the third solvent de-weighting tower and then circulated into the polymerization kettle of the polymerization unit, which can reduce the amount of steam and circulating water used in the process of recovering the solvent and butadiene, thereby reducing energy consumption; at the same time, through process optimization, the butadiene recovery tower system is eliminated, the number of equipment is reduced, and the project construction investment is saved. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 , one Energy-saving process flow chart of solvent recovery in the production process of butadiene rubber by solvent decomposition and two-effect distillation In the figure: 1-solvent dehydration tower, 2-solvent dehydration tower condenser, 3-dehydration tower reflux tank, 4-solvent dehydration tower reboiler, 5-solvent dehydration tower reflux pump, 6-solvent dehydration tower, 7-feed first heater, 8-solvent dehydration tower condenser, 9-solvent dehydration tower reflux tank, 10-solvent dehydration tower reflux pump, 11-solvent dehydration tower reboiler, 12-solvent dehydration tower bottom liquid pump, 13-solvent dehydration tower, 14-feed second heat exchanger, 15-solvent dehydration tower cooler, 16-solvent dehydration tower reflux tank, 17-solvent dehydration tower reflux pump, 18-solvent dehydration tower reboiler.

[0014] CWS - Circulating Cooling Water LS - Low Pressure Steam.

[0015] Figure 2 , one Energy-saving process flow chart of solvent recovery in the production process of butadiene rubber by three-effect distillation In the figure: 1-solvent dehydration tower, 2-solvent dehydration tower condenser, 3-dehydration tower reflux tank, 4-solvent dehydration tower reboiler, 5-solvent dehydration tower reflux pump, 6-solvent dehydration tower, 7-feed first heater, 8-solvent dehydration tower condenser, 9-solvent dehydration tower reflux tank, 10-solvent dehydration tower reflux pump, 11-solvent dehydration tower reboiler, 12-solvent dehydration tower bottom liquid pump, 13-solvent dehydration tower, 14-feed second heat exchanger, 15-solvent dehydration tower cooler, 16-solvent dehydration tower reflux tank, 17-solvent dehydration tower reflux pump, 18-solvent dehydration tower reboiler, 19-solvent dehydration tower bottom liquid pump, 20-solvent dehydration tower, 21-solvent dehydration tower reboiler, 22-hot water heater, 23-solvent de-weighting three-tower cooler, 24-solvent de-weighting three-tower reflux tank, 25-solvent de-weighting three-tower reflux pump CWS-circulating cooling water LS-low pressure steam HW-low temperature hot water DETAILED DESCRIPTION

[0016] The present invention is further described below in conjunction with the accompanying drawings, but does not constitute a further limitation of the present invention. Example

[0017] An annual production plant of 100,000 tons of nickel-based butadiene rubber, energy-saving process flow for solvent recovery, such as Figure 1 shown.

[0018] The crude solvent containing butadiene flashed out from the glue tank and washed with alkali is mixed with the crude solvent recovered by condensation, and then passes through the first feed heater (7) to exchange heat with the gas phase at the top of the solvent dehydration tower (6) and the second feed heat exchanger (14) to exchange heat with the condensate at the top of the solvent dehydration tower (2), and then enters the middle part of the solvent dehydration tower (1). In the solvent dehydration tower (1), water in the crude solvent is removed. Part of the solvent, butadiene and water are discharged from the top of the solvent dehydration tower (1), which are condensed by the solvent dehydration tower condenser (2). The condensate flows into the solvent dehydration tower reflux tank (3). In the solvent dehydration tower reflux tank (3), the oil phase and the water phase are separated, the water phase is discharged into the sewage system, and the oil phase is sent to the solvent dehydration tower (1) as reflux through the solvent dehydration tower reflux pump (5). The solvent dehydration tower kettle is the solvent that has been dehydrated, which is sent to the solvent dehydration tower (6) by pressure difference. In the solvent de-weighting tower (6), part of the solvent and butadiene removed from the heavy components are evaporated from the tower top. The solvent and butadiene vapor phase evaporated from the tower top enters the first feed heater (7) and then is condensed and cooled by the solvent de-weighting tower condenser (8) before flowing into the solvent de-weighting tower reflux tank (9). The solvent and butadiene mixture in the solvent de-weighting tower reflux tank (9) is partially sent to the top of the solvent de-weighting tower (6) as reflux by the solvent de-weighting tower reflux pump (10) of the solvent de-weighting tower. Part of the butadiene solvent mixture is mixed with the refined solvent from the solvent de-weighting tower reflux pump (17) of the second solvent de-weighting tower and sent to the refined solvent tank as a qualified refined solvent and butadiene mixture, and then recycled to the polymerization unit. The bottom of the solvent de-weighting tower (6) contains the solvent containing the heavy components, which is sent to the solvent de-weighting tower (13) by the solvent de-weighting tower bottom liquid pump (12).

[0019] In the solvent dehydration tower (13), the solvent removed from the heavy component is evaporated from the top of the tower. The solvent vapor evaporated from the top of the tower enters the solvent dehydration tower reboiler (11) as its heat source. The vapor phase is condensed in the solvent dehydration tower reboiler (11). The condensate is heat-exchanged with the solvent feed of the solvent dehydration tower (1) in the second feed heat exchanger (14), and then cooled by the solvent dehydration tower cooler (15) and flows into the solvent dehydration tower reflux tank (16). The solvent in the solvent dehydration tower reflux tank is partially sent back to the top of the solvent dehydration tower (13) by the solvent dehydration tower reflux pump (17) as reflux, and partially as fine solvent is mixed with the fine solvent and butadiene mixture from the solvent dehydration tower reflux pump (10) and sent to the fine solvent tank and then recycled to the polymerization unit. The bottom of the solvent dehydration tower (13) contains the solvent containing the heavy component, which is sent to the residual liquid recovery tower by differential pressure to further recover the solvent.

[0020] Compared with the traditional method, the present invention can save 4.5t / h of low-pressure steam consumption and 130t / h of circulating water consumption. The process of the present invention reduces energy consumption by about 25% compared with the traditional process. Example

[0021] The annual production capacity of 120,000 tons of rare earth butadiene rubber production equipment, the energy-saving process of solvent recovery, such as Figure 2 shown.

[0022] The crude solvent containing butadiene flashed from the glue tank is mixed with the crude solvent recovered by condensation, and then enters the middle of the solvent dehydration tower (1) after heat exchange with the gas phase at the top of the solvent dehydration tower (6) through the first feed heater (7) and heat exchange with the condensate at the top of the solvent dehydration tower (2) through the second feed heat exchanger (14). In the solvent dehydration tower (1), water in the crude solvent is removed. Part of the solvent, butadiene and water are discharged from the top of the solvent dehydration tower (1). They are condensed by the solvent dehydration tower condenser (2). The condensate flows into the solvent dehydration tower reflux tank (3). In the solvent dehydration tower reflux tank (3), the oil phase and the water phase are separated, the water phase is discharged into the sewage system, and the oil phase is sent to the solvent dehydration tower (1) as reflux through the dehydration tower reflux pump (4). The solvent dehydration tower kettle is the dehydrated solvent, which is sent to the solvent dehydration tower (6) by pressure difference. In the solvent de-weighting tower (6), part of the solvent and butadiene removed from the heavy components are evaporated from the tower top. The solvent and butadiene vapor phase evaporated from the tower top enter the first feed heater (7) and then are condensed and cooled by the solvent de-weighting tower condenser (8) before flowing into the solvent de-weighting tower reflux tank (9). The solvent and butadiene mixture in the solvent de-weighting tower reflux tank (10) is partially sent to the top of the solvent de-weighting tower (6) as reflux by the solvent de-weighting tower reflux pump (10) of the solvent de-weighting tower. Part of the butadiene solvent mixture is mixed with the refined solvent from the solvent de-weighting tower reflux pump (25) of the second solvent de-weighting tower and sent to the refined solvent tank as a qualified refined solvent and butadiene mixture, and then recycled to the polymerization unit. The bottom of the solvent de-weighting tower (6) contains the solvent containing the heavy components, which is sent to the solvent de-weighting tower (13) by the solvent de-weighting tower bottom liquid pump (12).

[0023] In the solvent de-weighting tower (13), the solvent from which the heavy components are removed is evaporated from the top of the tower. The solvent vapor evaporated from the top of the tower enters the solvent de-weighting tower reboiler (11) as its heat source. The vapor phase is condensed in the solvent de-weighting tower reboiler (11). The condensate is heat-exchanged with the dehydration tower feed in the solvent second heater (14), and then cooled by the solvent de-weighting tower cooler (15) before flowing into the solvent de-weighting tower reflux tank (16). The solvent in the solvent de-weighting tower reflux tank (16) is partially sent back to the top of the solvent de-weighting tower (13) by the solvent de-weighting tower reflux pump (17) as reflux, and partially mixed as refined solvent with the refined solvent and butadiene mixture from the solvent de-weighting tower reflux pump (10) and the refined solvent from the solvent de-weighting tower reflux pump (25) as refined solvent, and then sent to the refined solvent tank and then to the polymerization unit for recycling. The bottom of the second solvent de-weighting tower (13) contains the solvent containing the heavy component, which is transported to the third solvent de-weighting tower (20) by the bottom pump (19) of the second solvent de-weighting tower.

[0024] In the solvent de-weighting tower (20), the solvent removed from the heavy component is evaporated from the tower top. The solvent vapor evaporated from the tower top enters the solvent de-weighting tower reboiler (21) as its heat source. The vapor phase is condensed in the solvent de-weighting tower reboiler (21). The condensate is heat-exchanged with hot water in the hot water heater (22). After cooling through the solvent de-weighting tower cooler (23), it flows into the solvent de-weighting tower reflux tank (24). The solvent in the solvent de-weighting tower reflux tank (24) is partially sent back to the top of the solvent de-weighting tower (20) by the solvent de-weighting tower reflux pump (25) as reflux, and partially as refined solvent, mixed with the refined solvent and butadiene mixture from the solvent de-weighting tower 1 reflux pump (10) and the refined solvent (17) from the solvent de-weighting tower 2 reflux pump, and then sent to the refined solvent tank and then to the polymerization unit for recycling. The bottom of the solvent de-weighting tower (20) contains the solvent containing the heavy component, which is sent to the residual liquid recovery tower by differential pressure to further recover the solvent.

[0025] Compared with the traditional process, this invention can save 5.4t / h of low-pressure steam consumption and 156t / h of circulating water consumption. The process of the present invention reduces energy consumption by about 35% compared with the traditional process.

Claims

1. An energy-saving process for solvent recovery in the production process of butadiene rubber, wherein in the production process of butadiene rubber, the solvent flashed out from the glue tank, butadiene and the crude solvent recovered by condensation are dehydrated in a solvent dehydration tower, and then heavy impurities in the solvent are removed by double or triple distillation, and the solvent and butadiene are recovered, characterized in that: The first solvent de-weighting tower is used to recover butadiene and part of the solvent, and the second solvent de-weighting tower or the second solvent de-weighting tower and the third solvent de-weighting tower are used to recover the solvent and remove the heavy components.

2. The energy-saving process for solvent recovery in the production process of butadiene rubber according to claim 1, characterized in that The function of the solvent dehydration tower is only to remove water, not butadiene.

3. The energy-saving process for solvent recovery in the production process of butadiene rubber according to claim 1, characterized in that The butadiene rubber production process is a nickel-based butadiene rubber production process or a rare earth butadiene rubber production process.

4. The energy-saving process for solvent recovery in the production process of butadiene rubber according to claim 1, characterized in that The solvent is n-hexane, cyclohexane, cyclopentane and a mixture of cyclohexane and n-hexane.

5. The energy-saving process for solvent recovery in the production process of butadiene rubber according to claim 1, characterized in that The crude solvent containing butadiene flashed out from the glue tank and the crude solvent recovered by condensation enter the middle part of the solvent dehydration tower.

6. The energy-saving process for solvent recovery in the production process of butadiene rubber according to claim 1, characterized in that What comes out from the top of the solvent dehydration tower are part of the solvent, butadiene and water, which are condensed through the dehydration tower condenser, and the condensate flows into the dehydration tower reflux tank. In the reflux tank, the oil phase and the water phase are separated, the water phase is discharged into the sewage system, and the oil phase is pumped to the solvent dehydration tower as reflux through the dehydration tower reflux pump.

7. The energy-saving process for solvent recovery in the production process of butadiene rubber according to claim 1, characterized in that The dehydration tower kettle is the solvent for removing moisture, which is sent to the solvent degravation tower by pressure difference.

8. The energy-saving process for solvent recovery in the production process of butadiene rubber according to claim 1, characterized in that When the heavy component impurities in the solvent are removed by two-effect distillation, in the solvent de-weighting tower, part of the solvent and butadiene removed by the heavy component are evaporated from the top of the tower, the solvent and butadiene vapor phase evaporated from the top of the tower enter the cooler of the de-weighting tower to be condensed and cooled, and then flow into the reflux tank, the solvent and butadiene mixture in the reflux tank is partially sent to the top of the solvent de-weighting tower as reflux by the reflux pump of the de-weighting tower, part of the butadiene solvent mixture is mixed with the refined solvent from the reflux pump of the solvent de-weighting tower to the refined solvent tank as a qualified refined solvent and butadiene mixture, and then recycled to the polymerization unit; the bottom of the solvent de-weighting tower is the solvent containing the heavy component, which is sent to the solvent de-weighting tower by the bottom liquid pump of the de-weighting tower; the heavy component impurities in the solvent are removed by distillation by two-effect co-current distillation or two-effect counter-current distillation.

9. The energy-saving process for solvent recovery in the production process of butadiene rubber according to claim 1, characterized in that When the heavy component impurities in the solvent are removed by double-effect distillation, the solvent for removing the heavy component is evaporated from the top of the solvent dehydration tower, and the solvent vapor evaporated from the top of the tower enters the reboiler of the solvent dehydration tower as its heat source. The vapor phase is condensed in the reboiler of the dehydration tower, and the condensate is heat-exchanged with the dehydration tower feed solvent in the second solvent preheater, and then cooled by the second dehydration tower cooler and flows into the reflux tank of the second dehydration tower. The solvent in the reflux tank is partially sent back to the top of the second solvent dehydration tower by the reflux pump of the second dehydration tower as reflux, and part of it is mixed with the mixture of the fine solvent and butadiene from the reflux pump of the first solvent dehydration tower as fine solvent and sent to the fine solvent tank and then to the polymerization unit for recycling; the tower bottom of the second solvent dehydration tower is the solvent containing the heavy component, which is sent to the residual liquid recovery tower by differential pressure to further recover the solvent.

10. The energy-saving process for solvent recovery in the production process of butadiene rubber according to claim 1, characterized in that When triple-effect distillation is used to remove heavy impurities from the solvent: In the solvent de-weighting tower 1, part of the solvent and butadiene removed from the heavy component are evaporated from the tower top, and the solvent and butadiene vapor phase evaporated from the tower top enter the cooler of the de-weighting tower 1 for condensation and cooling, and then flow into the reflux tank, and part of the solvent and butadiene mixture in the reflux tank is sent to the top of the solvent de-weighting tower 1 as reflux by the reflux pump of the de-weighting tower 1, and part of the butadiene solvent mixture is mixed with the refined solvent from the reflux pump of the solvent de-weighting tower 2 and the reflux pump of the de-weighting tower 3, and then sent to the refined solvent tank as a qualified refined solvent and butadiene mixture, and then recycled to the polymerization unit; the bottom of the solvent de-weighting tower 1 is the solvent containing the heavy component, which is sent to the solvent de-weighting tower 2 by the bottom liquid pump of the de-weighting tower 1; In the second solvent de-weighting tower, the solvent removed from the heavy component is evaporated from the top of the tower, and the solvent vapor evaporated from the top of the tower enters the reboiler of the first solvent de-weighting tower as its heat source. The vapor phase is condensed in the reboiler of the first de-weighting tower. The condensate is heat-exchanged with the dehydration tower feed solvent in the second solvent preheater, and then cooled by the second de-weighting tower cooler and flows into the reflux tank of the second de-weighting tower. The solvent in the reflux tank is partially sent back to the top of the second solvent de-weighting tower by the reflux pump of the second de-weighting tower as reflux, and part of it is mixed with the mixture of the fine solvent and butadiene from the reflux pump of the first solvent de-weighting tower and the fine solvent from the reflux pump of the third de-weighting tower as refined solvent, and then sent to the refined solvent tank and then recycled to the polymerization unit. The bottom of the second solvent de-weighting tower contains the solvent containing the heavy component, which is pumped to the third de-weighting tower by the bottom of the second de-weighting tower; In the solvent de-weighting tower, the solvent removed from the heavy component is evaporated from the tower top, and the solvent vapor evaporated from the tower top enters the reboiler of the solvent de-weighting tower No. 2 as its heat source. After the vapor phase is condensed and cooled in the reboiler of the heavy componenting tower No. 2, it flows into the reflux tank of the heavy componenting tower No.

2. The solvent in the reflux tank is partially sent back to the tower top of the solvent de-weighting tower No. 3 by the reflux pump of the heavy componenting tower No. 3 as reflux, and partially as the refined solvent mixed with the refined solvent and butadiene mixture from the reflux pump of the solvent de-weighting tower No. 1 and the refined solvent from the reflux pump of the heavy componenting tower No. 2 and sent to the refined solvent tank and then to the polymerization unit for recycling; the tower bottom of the solvent de-weighting tower No. 3 contains the solvent containing the heavy component, which is sent to the residual liquid recovery tower by differential pressure to further recover the solvent; The heavy impurities in the solvent are removed by distillation using three-effect downstream distillation or three-effect countercurrent distillation.

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