Energy-efficient mixed C4-tetraene separation unit

Abstract

This invention discloses a low-energy-consumption mixed C4 alkane-olefin separation device, comprising: a C4 evaporator or tank, an extractive distillation column for separating alkane and olefin, and a stripping column. The inlet of the extractive distillation column is connected to the top outlet of the C4 evaporator or tank, the stripping column is connected to the bottom of the extractive distillation column, and the top of the stripping column is connected to the inlet of a C4 olefin reflux tank. A chilled water system is also connected between the top of the stripping column and the inlet of the C4 olefin reflux tank to cool the C4 olefins before reflux. By installing a chilled water system at the top of the stripping column, this invention allows for lower-pressure operation within the stripping column, reducing overall energy consumption, optimizing the process flow, and simplifying the number of equipment. Furthermore, the separation effect of olefins cooled to low temperatures by chilled water under low pressure is better, improving the recovery rate and purity of C4 alkane and C4 olefin.

Description

Technical Field

[0001] This utility model belongs to the field of chemical technology, specifically relating to a mixed C4 alkylene separation device that reduces energy consumption. Background Technology

[0002] Mixed C4 is mainly a byproduct of units such as oil refining catalytic cracking (FCC), ethylene steam cracking, and methanol-to-olefins (MTO).

[0003] The main components of mixed C4 hydrocarbons are small amounts of C3 hydrocarbons, n-butane, isobutane, 1-butene, isobutene, cis / trans-2-butene, and small amounts of C5 hydrocarbons. FCC mixed C4 hydrocarbons have a higher alkane content, while ethylene vapor cracking and MTO mixed C4 hydrocarbons have a higher olefin content. Since the boiling points and relative volatility of C4 alkanes and C4 olefins are similar, conventional separation techniques are generally ineffective. Therefore, extractive distillation is currently the primary method for efficient separation of mixed C4 hydrocarbons. The extraction solvents used are mainly acetonitrile series solvents, morpholine and N-formylmorpholine series solvents, methyl ethyl ketone series solvents, sulfolane series solvents, and N-methylpyrrolidone series solvents.

[0004] Patent CN103502188A proposes using a mixture of N-methylpyrrolidone and water as a solvent to separate C4-alkanes and C4-olefins via extractive distillation, but only studies the separation effect of the N-methylpyrrolidone method. Patent CN108929188A proposes using a composite solvent of sulfolane, benzene, and toluene to extract and separate C4-alkanes and C4-olefins, but only studies the separation effect of the sulfolane method. Patent CN101417913A proposes using a mixture of ionic liquid, N-formylmorpholine, and methyl ethyl ketone as a solvent to separate C4-alkanes and C4-olefins via extractive distillation, but does not consider energy recovery. These inventions mainly study the separation effects of different extractants, without considering process optimization and energy recovery, and cannot achieve energy-efficient separation. Furthermore, the technology of separating mixed C4-alkanes using N-methylpyrrolidone solution has not yet been applied in China, and in-depth research is urgently needed on how to use this technology in an energy-efficient manner. Utility Model Content

[0005] This invention addresses the technical problems of cumbersome process flow, high energy consumption, and low recovery rate in existing alkene separation devices, and aims to provide a mixed C4 alkene separation device that reduces energy consumption.

[0006] The energy-saving mixed C4 tetroxide separation device of this invention includes:

[0007] A C4 evaporation tower or tank, having a mixed C4 feed inlet;

[0008] An extractive distillation column for separating alkanes and alkenes, wherein the inlet of the extractive distillation column is connected to the top outlet of a C4 evaporator or tank;

[0009] A stripping column, wherein the stripping column is connected to the bottom of the extractive distillation column, and the top of the stripping column is connected to the inlet of a C4 olefin reflux tank, characterized in that a chilled water system for cooling the C4 olefins before reflux is also connected between the top of the stripping column and the inlet of the C4 olefin reflux tank.

[0010] Preferably, the chilled water system is a chilled water condenser with a temperature of -10℃ to 10℃, and more preferably, the chilled water system is a chilled water condenser with a temperature of -5℃ to 5℃.

[0011] Preferably, the top of the analytical column is at atmospheric pressure or low pressure, and more preferably, the pressure at the top of the analytical column is 0.01 MPaG to 0.4 MPaG, more preferably 0.05 MPaG to 0.1 MPaG.

[0012] Preferably,

[0013] The extractive distillation column has an extractive distillation intermediate reboiler.

[0014] The bottom of the C4 evaporator or tank has a C4 evaporator-reboiler;

[0015] The bottom of the stripping column is connected to the upper part of the extractive distillation column. The bottom of the stripping column is first connected to the intermediate reboiler of the extractive distillation column for heat exchange, then to the C4 evaporator reboiler for heat exchange, and finally connected to the upper part of the extractive distillation column after temperature control by a lean solvent cooler.

[0016] Preferably, the top of the extractive distillation column is connected to the inlet of the C4 alkane reflux tank, the reflux branch of the outlet of the C4 alkane reflux tank is connected to the upper part of the extractive distillation column, and the outlet of the C4 alkane reflux tank is also connected to an alkane extraction branch.

[0017] Preferably, a circulating cooling water system is connected between the top of the extractive distillation column and the inlet of the C4 alkane reflux tank to cool the separated and refluxed C4 alkane.

[0018] Preferably, the circulating cooling water system is a circulating cooling water condenser.

[0019] Preferably, the reflux branch of the outlet of the C4 olefin reflux tank is connected to the upper part of the stripping tower, and the outlet of the C4 olefin reflux tank is also connected to an olefin extraction branch.

[0020] Preferably,

[0021] The bottom of the stripping column is equipped with a stripping column reboiler;

[0022] The bottom of the extractive distillation column is equipped with an extractive distillation column reboiler;

[0023] A lean solvent cooler is provided before the solvent inlet at the top of the extractive distillation column.

[0024] Preferably,

[0025] The bottom of the analytical column is equipped with a lean solvent circulation pump;

[0026] The C4 evaporator or tank is a C4 evaporator or a C4 evaporator.

[0027] The positive and progressive effects of this utility model are as follows:

[0028] 1) This invention, by installing a public utility chilled water system at the top of the stripping column, allows the stripping column to operate at a lower pressure, reducing the stripping temperature throughout the column and thus decreasing the amount of steam used for heating the stripping column bottom, thereby reducing the energy consumption of the unit. Simultaneously, the separation effect of olefins cooled to a low temperature by chilled water under low pressure is better, improving the recovery rate and purity of C4 alkanes and C4 olefins. Furthermore, due to the lower operating pressure of the stripping column, the rich solvent in the extractive distillation column bottom can directly enter the stripping column under pressure difference, eliminating the need for a transfer pump.

[0029] 2) The N-methylpyrrolidone solution used in this invention as the extraction solvent has excellent separation effect. Therefore, both the extraction distillation column and the stripping column can be a single column to meet the separation of mixed C4 alkylenes, which further optimizes the process flow and simplifies the number of equipment.

[0030] 3) This invention can achieve efficient energy utilization by reusing the heat of the lean solvent. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the energy-saving mixed C4 tetroxide separation device of Example 1;

[0032] Figure 2 This is a schematic diagram of a conventional mixed C4 tetroxide separation device for Comparative Example 1.

[0033] The diagram shows the following labels: C4 evaporator or tank V1; extractive distillation column T2; stripping column T3; C4 alkane reflux tank V2; C4 olefin reflux tank V3; C4 evaporator reboiler E1; extractive distillation column bottom reboiler E2; circulating cooling water condenser E3; stripping column reboiler E4; chilled water condenser E5; lean solvent cooler E6; extractive distillation column intermediate reboiler E7; lean solvent circulating pump P1; rich solvent transfer pump P2; 1-mixed C4 feedstock; 2-vaporized mixed C4; 3-extractive distillation column overhead vapor phase C4 alkane; 4-alkane reflux branch; 5-alkane collection branch; 6-rich solvent; 7-extractive distillation column overhead vapor phase C4 olefin; 8-olefin reflux branch; 9-olefin collection branch; 10-collected lean solvent; 11-feed lean solvent. Detailed Implementation

[0034] The following specific examples illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. This utility model can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this utility model.

[0035] like Figure 1 As shown, the energy-saving mixed C4 alkane-olefin separation device of this invention includes a C4 evaporator or tank V1 that vaporizes the mixed C4 feedstock to remove small amounts of heavy components, an extractive distillation column T2 that separates alkanes and olefins, and a stripping column T3 that removes olefins from a rich solvent. The C4 evaporator or tank V1 has a mixed C4 feed inlet, and its top outlet is connected to the inlet in the middle of the extractive distillation column T2. ​​The C4 evaporator or tank V1 is heated by a C4 evaporator-reboiler E1 installed at the bottom to vaporize the C4 feedstock. The vaporized mixed C4 enters the extractive distillation column T2 and comes into countercurrent contact with the lean solvent. Of course, the C4 evaporator or tank V1 can be either a C4 evaporator or a C4 evaporator. When the heavy components in the mixed C4 feedstock are easily separated, a C4 evaporator is used; when the heavy components are difficult to separate, a C4 evaporator is preferred. Continuing... Figure 1 As shown, the extractive distillation column T2 uses the extractive distillation column reboiler E2 installed in the column bottom to heat the process material inside the column. Gaseous alkanes are collected from the top of the extractive distillation column T2. ​​These gaseous alkanes are first cooled by the circulating cooling water condenser E3 and then enter the C4 alkane reflux tank V2. A portion of the C4 alkane in the tank is then refluxed back into the extractive distillation column T2 via the reflux branch, while the other portion is collected directly as product from the alkane collection branch. The operating pressure of the extractive distillation column T2 is 0.35 MPaG to 0.75 MPaG, preferably 0.5 MPaG to 0.55 MPaG.

[0036] And continue as Figure 1 As shown, the bottom of extractive distillation column T2 yields a solvent-rich product containing C4 olefins. The bottom of extractive distillation column T2 is connected to the middle section of stripping column T3, with the olefin-rich solvent entering stripping column T3 from the bottom of extractive distillation column T2. ​​The stripping column reboiler E4 in the bottom of stripping column T3 heats and desorbs the process material within T3. Both the extractive distillation column reboiler E2 and the stripping column reboiler E4 utilize steam as the heat medium. After heating and stripping in stripping column T3, gaseous olefins are collected from the top. These gaseous olefins are first cooled by chilled water condenser E5 before entering the C4 olefin reflux tank V3. A portion of the C4 olefins in the tank is refluxed back to stripping column T3 via the reflux branch, while the other portion is collected directly as product from the olefin collection branch. The chilled water system is a chilled water condenser E5 with a temperature range of -10℃ to 10℃, preferably a chilled water condenser with a temperature range of -5℃ to 5℃, which can cool the gaseous olefins collected from the top of the tower to a low temperature of 0℃ to 20℃, preferably 5℃ to 15℃. This chilled water condenser uses a circulating refrigerant available from the factory or plant, including aqueous solutions of calcium chloride, propylene glycol, and ethylene glycol, preferably aqueous solutions of propylene glycol or ethylene glycol. Because the top of the stripping column T3 utilizes a chilled water condenser E5 to cool the extracted C4 olefins, the top of column T3 can operate at atmospheric or low pressure. Specifically, the top pressure of stripping column T3, i.e., the operating pressure, is 0.01 MPaG to 0.4 MPaG, preferably 0.05 MPaG to 0.1 MPaG. This lowers the stripping temperature within column T3, thereby reducing the amount of steam used for heating the column bottom and thus reducing the overall energy consumption of the unit. Furthermore, the separation effect of olefins cooled to low temperature by chilled water is better under low pressure, improving the recovery rate and purity of C4 alkanes and C4 olefins. Simultaneously, both the extractive distillation column and the stripping column can be used as single columns to meet the separation of mixed C4 alkanes, further optimizing the process flow and simplifying the number of equipment. In addition, for example... Figure 2 The existing alkane-alkene separation device shown in this invention has a low-pressure stripping tower T3, eliminating the need to install a rich solvent transfer pump P2 between the bottom of the extractive distillation tower T2 and the middle of the stripping tower T3. The rich solvent can be directly transported into the stripping tower T3 using the pressure difference, further simplifying the number of devices.

[0037] Continue as Figure 1As shown, the lean solvent in the bottom of the stripping column T3 is connected to the upper part of the extractive distillation column T2 after being temperature-controlled by a multi-stage heat exchange device and a lean solvent cooler E6. Specifically, a lean solvent circulation pump P1 is installed at the bottom of the stripping column T3 to transport the lean solvent in the bottom of the stripping column T3 to exchange heat with the aforementioned multi-stage heat exchange device and then to the extractive distillation column T2. ​​The aforementioned multi-stage heat exchange device includes an intermediate reboiler E7 installed in the extractive distillation column T2 and a C4 evaporator reboiler E1 installed at the bottom of the C4 evaporator or tank V1. The lean solvent cooler E6 is installed at the upper inlet of the extractive distillation column T2. ​​The lean solvent formed in the bottom of the stripping column T3 is recycled into the extractive distillation column as an extractant after being heat-exchanged by the multi-stage heat exchange device, making full use of the thermal energy of the lean solvent and achieving efficient energy recovery. The aforementioned lean solvents include acetonitrile series solvents, morpholine and N-formylmorpholine series solvents, methyl ethyl ketone series solvents, sulfolane series solvents, and N-methylpyrrolidone series solvents, preferably N-methylpyrrolidone solutions with a water content of 1 wt% to 12 wt%.

[0038] Table 1. Components and contents of mixed C4 feedstock in the separation of mixed C4 alkylenes according to this invention.

[0039] Components wt% n-Butane 37.43 Isobutane 0.40 Butene-1 3.85 Isobutylene 0.19 trans-2-butene 36.66 cis-2-butene 21.47

[0040] Example 1

[0041] according to Figure 1 As shown in Table 1, mixed C4 feedstock 1, with a temperature of 40℃, a pressure of 0.6 MPaG, and a flow rate of 19200 kg / hr, enters the C4 evaporator V1. The composition and content of the mixed C4 feedstock are shown in Table 1. The vapor-phase mixed C4 2 at the top of the tank, with a flow rate of 19200 kg / h, a temperature of 64.2℃, and a pressure of 0.6 MPaG, enters the extractive distillation column T2. ​​The circulating lean solvent 11 (8 wt% water + 92 wt% N-methylpyrrolidone) is cooled to 40℃ by the lean solvent cooler E6 before entering the upper part of the extractive distillation column T2. ​​The lean solvent inlet is located above the mixed C4 feedstock inlet. The extractive distillation... The gaseous C4-alkane 3 at the top of column T2 is condensed in the circulating cooling water condenser E3 at the top of the column. After condensation by the circulating cooling water, the temperature is 57.7℃ and the pressure is 0.53MPaG. A portion of the C4-alkane 4 is refluxed to the upper part of the extractive distillation column T2, and the other portion is collected as C4-alkane product 5, with a collection rate of 7140kg / h. The concentration of n-butane and isobutane in the C4-alkane product is 98.1wt%. The solvent-rich solvent 6 at the bottom of the extractive distillation column T2 is directly transported to the stripping column T3 by pressure difference. The temperature of the solvent-rich solvent is 101.7℃, the pressure is 0.61MPaG, and the flow rate is 149000kg / hr.

[0042] The operating pressure at the top of stripping column T3 is 0.05 MPaG. After the solvent-rich stripping column T3, the gaseous C4 olefins 7 at the top of the column are cooled by circulating chilled water (ethylene glycol aqueous solution) inside the top chilled water condenser E5, reaching a temperature of 11.3℃ and a pressure of 0.045 MPaG. A portion of the C4 olefins 8 is refluxed to the upper part of stripping column T3, and the other portion is collected as C4 olefin product 9, with a collection rate of 12060 kg / h. The concentration of butene-1, isobutene, cis-2-butene, and trans-2-butene in the C4 olefin product is 97.8 wt%. The temperature of the lean solvent 10 at the bottom of stripping column T3 is 152℃, the pressure is 0.09 MPaG, and the flow rate is 136940 kg / hr.

[0043] The lean solvent is pumped to the intermediate reboiler E7 of the extractive distillation column via the lean solvent ring pump P1. After exchanging heat with the process material in the column, the temperature drops to 101°C. After exchanging heat with the reboiler E1 of the evaporator, the temperature drops to 76°C. Then it goes to the lean solvent cooler E6, where it exchanges heat with the circulating cooling water and the temperature drops to 40°C. Finally, the lean solvent 11 is used as the extractant in the extractive distillation column T2 for recycling.

[0044] Comparative Example 1

[0045] like Figure 2 As shown, the conventional mixed C4 alkylene separation process using N-methylpyrrolidone solution includes: a mixed C4 feedstock 1, with a temperature of 40°C, a pressure of 0.6 MPaG, and a flow rate of 19200 kg / hr, enters a C4 evaporator V1. The composition and content of the mixed C4 feedstock are shown in Table 1. A gaseous mixed C4 2, with a flow rate of 19200 kg / h, a temperature of 64.2°C, and a pressure of 0.6 MPaG, enters an extractive distillation column T2. ​​A circulating lean solvent 11 (8 wt% water + 92 wt% N-methylpyrrolidone) is cooled to 40°C by a lean solvent cooler E6 before entering the upper part of the extractive distillation column T2. ​​The lean solvent inlet is located at the mixed C4 alkylene evaporator V1. Above the feed inlet; the gaseous C4 alkane 3 at the top of extractive distillation column T2 is condensed in the circulating cooling water condenser E3 at the top of the column. After condensation by the circulating cooling water, the temperature is 57.7℃ and the pressure is 0.53MPaG. Part of the C4 alkane refluxes 4 to the upper part of extractive distillation column T2, and the other part is collected as C4 alkane product 5, with a collection rate of 7140kg / h. The concentration of n-butane and isobutane in the C4 alkane product is 97.9wt%. The rich solvent 6 at the bottom of extractive distillation column T2 is transported to the stripping column T3 by rich solvent transfer pump P2. The temperature of the rich solvent is 101.6℃, the pressure is 0.61MPaG, and the flow rate is 149000kg / hr.

[0046] The operating pressure at the top of stripping column T3 is 0.38 MPaG. After the solvent-rich stripping column T3 is stripped, the gaseous C4 olefins 7 at the top of the column are condensed inside the top condenser E5 by circulating cooling water. The temperature is 47℃ and the pressure is 0.38 MPaG. Part of the C4 olefins 8 is refluxed to the upper part of stripping column T3, and the other part is collected as C4 olefin product 9. The collection rate is 12060 kg / h. The concentration of butene-1, isobutene, cis-2-butene, and trans-2-butene in the C4 olefin product is 97.6 wt%. The temperature of the lean solvent 10 at the bottom of stripping column T3 is 190℃, the pressure is 0.42 MPaG, and the flow rate is 136940 kg / hr.

[0047] The lean solvent is delivered to the reboiler E1 of the evaporator via the lean solvent transfer pump P1. After exchanging heat with the mixed C4, it goes to the solvent cooler E6. After exchanging heat with the circulating cooling water, the temperature drops to 40°C. Finally, the lean solvent 11 is used as the extractant in the extractive distillation column T2 for recycling.

[0048] In the conventional N-methylpyrrolidone solution method for separating mixed C4 olefins, the stripping column T3 operates at a relatively high pressure, and the top condenser uses circulating cooling water for condensation. This results in high temperatures at the bottom and top of column T3, leading to high energy consumption and significant product loss. This invention employs a lower pressure and temperature operation within the stripping column. The gaseous C4 olefins at the top are directly cooled by the refrigeration system, specifically the top chilled water condenser E5, using a refrigerant available from the factory or equipment. This reduces overall system energy consumption, optimizes the process flow, and simplifies the number of equipment. Simultaneously, it achieves excellent separation of mixed C4 olefins, enabling high recovery rates and high purity of both C4 olefins and C4 hydrocarbons. The performance comparison under the same feed conditions is shown in Table 2 below.

[0049] Table 2 Comparison of different process flows for the separation of N-methylpyrrolidone-based mixed carbotetraenes using solution method

[0050] Comparison Items Example 1 Comparative Example 1 Concentration of C4 hydrocarbons in the product 98.1 wt% 97.9wt% Concentration of product C4 olefin 97.8 wt% 97.6 wt% Energy consumption (kg standard oil / t raw material) 65.0 116.6

[0051] Conclusions: 1) In the separation process of mixed C4 alkanes, this invention controls the pressure at the top of the stripping column at a low pressure, and then uses a circulating chilled water condenser at the top of the column to condense the gaseous C4 alkane from the top of the column. Furthermore, the addition of an intermediate reboiler in the extraction and distillation columns enhances the recovery of lean solvent heat, thus reducing the overall system energy consumption from 116.6 kg standard oil / t feed in Comparative Example 1 to 65.0 kg standard oil / t feed. 2) Utilizing a lean solvent to heat the process material in the extraction and distillation column via the intermediate reboiler results in partial vaporization of the process material, enhancing the gas-liquid separation effect within the column. The concentration of the C4 alkane product increases from 97.9 wt% to 98.1 wt%. The low-pressure, low-temperature operation in the stripping column reduces the carryover of N-methylpyrrolidone solvent from the C4 alkane at the top of the column, increasing the concentration of the C4 alkane product from 97.6 wt% to 97.8 wt%. Meanwhile, the total amount of gaseous products did not change significantly, and the recovery rates of C4 alkanes and C4 olefins were higher than those of the conventional N-methylpyrrolidone method.

[0052] The present invention has been described in detail above with reference to the accompanying drawings and embodiments. Those skilled in the art can make various modifications to the present invention based on the above description. Therefore, certain details in the embodiments should not be construed as limiting the present invention, and the scope of protection of the present invention shall be defined by the appended claims.

Claims

1. A mixed carbotetraalkylene separation device for reducing energy consumption, the mixed carbotetraalkylene separation device comprising: A C4 evaporation tower or tank, having a mixed C4 feed inlet; An extractive distillation column for separating alkanes and alkenes, wherein the inlet of the extractive distillation column is connected to the top outlet of a C4 evaporator or tank; A stripping column, wherein the stripping column is connected to the bottom of the extractive distillation column, and the top of the stripping column is connected to the inlet of a C4 olefin reflux tank, characterized in that a chilled water system for cooling the C4 olefins before reflux is also connected between the top of the stripping column and the inlet of the C4 olefin reflux tank.

2. The reduced energy mixed C4 paraffin olefin separation apparatus of claim 1, wherein The chilled water system is a chilled water condenser with a temperature range of -10℃ to 10℃.

3. The reduced energy mixed C4 paraffin olefin separation apparatus of claim 2, wherein The chilled water system is a chilled water condenser with a temperature range of -5℃ to 5℃.

4. The reduced energy mixed C4 paraffin olefin separation apparatus of claim 1, wherein The top of the analytical tower is at atmospheric pressure or at a low pressure.

5. The reduced energy mixed C4 paraffin olefin separation apparatus of claim 4, wherein The pressure at the top of the analytical column is 0.01 MPaG ~ 0.4 MPaG.

6. The reduced energy mixed C4 paraffin olefin separation apparatus as in claim 4, wherein The pressure at the top of the analytical column is 0.05 MPaG ~ 0.1 MPaG.

7. The energy-saving mixed C4-tetraalkylene separation device as described in claim 1, characterized in that... The extractive distillation column has an extractive distillation intermediate reboiler. The bottom of the C4 evaporator or tank has a C4 evaporator-reboiler; The bottom of the stripping column is connected to the upper part of the extractive distillation column. The bottom of the stripping column is first connected to the intermediate reboiler of the extractive distillation column for heat exchange, then to the C4 evaporator reboiler for heat exchange, and finally connected to the upper part of the extractive distillation column after temperature control by a lean solvent cooler.

8. The energy-saving mixed C4-tetraalkylene separation device as described in claim 1, characterized in that... The top of the extractive distillation column is connected to the inlet of the C4 alkane reflux tank, the reflux branch of the outlet of the C4 alkane reflux tank is connected to the upper part of the extractive distillation column, and the outlet of the C4 alkane reflux tank is also connected to an alkane extraction branch.

9. The energy-saving mixed C4-tetraalkylene separation device as described in claim 8, characterized in that... A circulating cooling water system is connected between the top of the extractive distillation column and the inlet of the C4 alkane reflux tank to cool the C4 alkane before reflux after separation.

10. The energy-saving mixed C4-tetraalkylene separation device as described in claim 9, characterized in that... The circulating cooling water system is a circulating cooling water condenser.

11. The energy-saving mixed C4-tetraalkylene separation device as described in claim 1, characterized in that... The reflux branch of the outlet of the C4 olefin reflux tank is connected to the upper part of the stripping tower, and the outlet of the C4 olefin reflux tank is also connected to an olefin extraction branch.

12. The energy-saving mixed C4-tetraalkylene separation device as described in claim 1, characterized in that... The bottom of the stripping column is equipped with a stripping column reboiler; The bottom of the extractive distillation column is equipped with an extractive distillation column reboiler; A lean solvent cooler is provided before the solvent inlet at the top of the extractive distillation column.

13. The energy-saving mixed C4-tetraalkylene separation device as described in claim 1, characterized in that... The bottom of the analytical column is equipped with a lean solvent circulation pump; The C4 evaporator or tank is a C4 evaporator or a C4 evaporator.

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