Hybrid c4 olefin separation device with heat pump system

Abstract

This utility model discloses a mixed C4 alkane separation device with a heat pump system, comprising: a C4 evaporator or tank with a mixed C4 feed inlet, an extractive distillation column for separating alkanes and alkenes, and a distillation column. The inlet of the extractive distillation column is connected to the top outlet of the C4 evaporator or tank, and the stripping column is connected to the bottom of the extractive distillation column. The extractive distillation column is further connected to a heat pump system, which includes an open-loop heat pump system that transfers the low-grade heat energy of the vapor phase at the top of the extractive distillation column to the process material inside the extractive distillation column, and / or a closed-loop heat pump system that transfers the low-grade heat energy of the lean solvent after stripping from the stripping column through a multi-stage heat exchanger to the process material inside the extractive distillation column. This mixed C4 alkane separation device with a heat pump system can efficiently recover the low-grade heat energy of the vapor phase at the top of the extractive distillation column and the low-grade heat energy of the lean solvent.

Description

Technical Field

[0001] This utility model belongs to the field of chemical technology and relates to a mixed C4 alkylene separation device with a heat pump system. Background Technology

[0002] Mixed C4 hydrocarbons are mainly byproducts of ethylene steam cracking, fuel cell cracking (FCC), and methanol-to-olefins (MTO) plants, containing small amounts of C3, n-butane, isobutane, 1-butene, isobutene, cis / trans-2-butene, and small amounts of C5. Currently, extractive distillation is the primary method used both domestically and internationally to separate mixed C4 hydrocarbons. Extractants used include acetonitrile, mixtures of morpholine and N-formylmorpholine, mixtures of methyl ethyl ketone and N-formylmorpholine, sulfolane, and N-methylpyrrolidone. However, the use of N-methylpyrrolidone for the separation of mixed C4 alkylenes is not yet applied in China, and research is needed on how to use this technology in an energy-efficient and effective manner.

[0003] Heat pump distillation is a highly efficient separation technology that utilizes heat pumps to recover low-grade heat energy in a distillation system and significantly reduce distillation energy consumption. Researching the application of heat pump distillation technology to the separation process of mixed C4 alkylene compounds is of great significance for improving the economic efficiency of this separation process.

[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, without considering energy recovery. Patent CN104812725A uses the N-methylpyrrolidone method to separate C4 alkanes and C4 olefins, considering solvent heat recovery. Patent CN116670101A uses the N-methylpyrrolidone method to separate C4 alkanes and C4 olefins, considering both solvent energy recovery and steam heat recovery. These inventions study the separation of mixed C4 alkanes using the N-methylpyrrolidone method, but only consider solvent or steam energy recovery, failing to fully achieve energy efficiency. Therefore, further research is needed on using heat pump distillation technology to further improve the energy efficiency of the N-methylpyrrolidone method for separating mixed C4 alkanes. Utility Model Content

[0005] This invention uses N-methylpyrrolidone solution as an extractant to provide a mixed C4 alkylene separation device with a heat pump system, aiming to fully realize efficient energy recovery.

[0006] The present invention relates to a mixed C4 alkylene separation device with a heat pump system, comprising:

[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] The analytical column is connected to the bottom of the extractive distillation column;

[0010] The extractive distillation column is also connected to a heat pump system. Preferably, the heat pump system includes an open heat pump system that transfers the low-grade heat energy of the gas phase at the top of the extractive distillation column to the process material inside the extractive distillation column, and / or a closed heat pump system that transfers the low-grade heat energy of the lean solvent after desorption from the desorption column through a multi-stage heat exchanger to the process material inside the extractive distillation column.

[0011] Preferably, the open-loop heat pump system includes: a C4 alkane compressor; the top of the extractive distillation column is connected to the inlet of the C4 alkane compressor; the outlet of the C4 alkane compressor is connected to the inlet of the C4 alkane reflux tank after heat exchange with the first intermediate reboiler of the extractive distillation column; and the gas phase of the C4 alkane reflux tank is connected to the upper gas phase makeup gas of the C4 alkane compressor.

[0012] Preferably, 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.

[0013] Preferably, the closed-loop heat pump system includes: a working fluid evaporator for exchanging low-grade heat energy from lean solvent after multi-stage heat exchange, a working fluid compressor, and a working fluid storage tank. The outlet of the working fluid evaporator is connected to the inlet of the working fluid compressor. The outlet of the working fluid compressor is connected to the second intermediate reboiler of the extractive distillation column after heat exchange and then connected to the inlet of the working fluid storage tank. The outlet of the working fluid storage tank is connected to the inlet of the working fluid evaporator. Preferably, the gas phase of the working fluid storage tank is connected to the upper gas phase makeup gas of the working fluid compressor.

[0014] 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 collection branch; preferably, a circulating cooling water system for cooling the separated and refluxed C4 alkane is connected between the top of the extractive distillation column and the inlet of the C4 alkane reflux tank, preferably the circulating cooling water system is a circulating cooling water condenser.

[0015] Preferably, the top of the stripping column is connected to the inlet of the C4 olefin reflux tank, wherein a chilled water system for cooling the C4 olefins after stripping and before reflux is also connected between the top of the stripping column and the inlet of the C4 olefin reflux tank; preferably, the chilled water system is a chilled water condenser with a temperature range of -10℃ to 10℃; more preferably, it is a chilled water condenser with a temperature range of -5℃ to 5℃; even more preferably, the top of the stripping column is an atmospheric pressure or micro-pressure top, more preferably, the operating pressure of the top of the stripping column is 0.01~0.5 MPaG, preferably 0.04~0.1 MPaG.

[0016] Preferably,

[0017] The extractive distillation column also has a third intermediate reboiler and a bottom reboiler.

[0018] The bottom of the C4 evaporator or tank has a C4 evaporator-reboiler;

[0019] The bottom of the stripping column is connected to the upper part of the extractive distillation column. The bottom of the stripping column first exchanges heat with the rich solvent heater at the inlet of the stripping column, then exchanges heat with the third intermediate reboiler of the extractive distillation column, then exchanges heat with the C4 evaporator-reboiler, and finally connects to the upper part of the extractive distillation column after temperature control by a lean solvent cooler. Preferably, in a mixed C4 alkene separation system with a closed-loop heat pump system, after heat exchange with the C4 evaporator-reboiler, it also exchanges heat with the working fluid evaporator in the closed-loop heat pump system, and finally connects to the upper part of the extractive distillation column after temperature control by a lean solvent cooler.

[0020] 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.

[0021] Preferably,

[0022] An open-loop heat pump system, preferably 0°C to 15°C, transfers the low-grade heat energy of the vapor phase at the top of the extractive distillation column to the process material inside the extractive distillation column whose temperature differs from the vapor phase at the top of the column by 0°C to 30°C. Alternatively, a closed-loop heat pump system, preferably 0°C to 15°C, transfers the low-grade heat energy of the lean solvent after heat exchange in the desorption column through a multi-stage heat exchanger to the process material inside the extractive distillation column whose temperature differs from the lean solvent after heat exchange by 0°C to 30°C.

[0023] Preferably,

[0024] The bottom of the stripping column is equipped with a stripping column bottom reboiler;

[0025] The bottom of the extractive distillation column is equipped with an extractive distillation column reboiler;

[0026] A lean solvent cooler is provided before the solvent inlet at the top of the extractive distillation column;

[0027] The bottom of the analytical column is equipped with a lean solvent circulation pump;

[0028] The C4 evaporator or tank is a C4 evaporator or a C4 evaporator.

[0029] Another objective of this invention is to provide a method for separating mixed C4 alkylene compounds with a heat pump system, comprising the following steps:

[0030] Step S1: The mixed C4 raw material is fed into a C4 evaporation tower or tank for vaporization to remove heavy components;

[0031] In step S2, the vaporized mixed C4 enters the extractive distillation column and comes into countercurrent contact with the lean solvent circulating from the top of the extractive distillation column. The vaporized C4 alkane is collected from the top of the extractive distillation column, and the rich solvent containing C4 olefins is collected from the bottom of the extractive distillation column and enters the stripping column.

[0032] In step S3, the rich solvent is heated and desorbed in the stripping column. The gaseous C4 olefin is collected from the top of the stripping column, and the lean solvent is collected from the bottom of the stripping column and recycled back to the extractive distillation column as an extractant.

[0033] Specifically, the low-grade thermal energy of the gaseous C4 alkane collected from the top of the extractive distillation column is enhanced to high-grade thermal energy by an open heat pump system before being exchanged for the intermediate process material in the extractive distillation column, and / or, the low-grade thermal energy of the lean solvent collected from the bottom of the stripping column is enhanced to high-grade thermal energy by a closed heat pump system after passing through a multi-stage heat exchanger before being exchanged for the intermediate process material in the extractive distillation column.

[0034] Preferably, in step S3, the gaseous C4 olefins collected from the top of the stripping column are condensed by the chilled water condenser at the top of the stripping column, with a portion being collected as a product and the other portion being refluxed back into the stripping column from the top; preferably, the temperature of the condensed C4 olefins is 0℃~20℃, more preferably 5℃~15℃; the pressure at the top of the stripping column is 0.01MPaG~0.5 MPaG, preferably 0.04 MPaG~0.1 MPaG.

[0035] Preferably, the method includes a step S2A of utilizing the low-grade heat energy of gaseous C4-tetraalkanes or a step S2B of condensing gaseous C4-tetraalkanes.

[0036] Specifically, step S2A, which utilizes the low-grade thermal energy of gaseous C4 alkanes, includes:

[0037] In step S2A1, the gaseous C4 alkane extracted from the top of the distillation column is pressurized and heated by the C4 alkane compressor of the open heat pump system.

[0038] In step S2A2, the pressurized and heated C4 alkane transfers heat to the process material in the extractive distillation column via the first intermediate reboiler.

[0039] In step S2A3, the heat-exchanged C4 alkane enters the C4 alkane reflux tank. Preferably, the heat-exchanged C4 alkane is condensed after being depressurized and cooled by a throttling valve before entering the C4 alkane reflux tank. More preferably, the C4 alkane condensed after being depressurized and cooled by a throttling valve enters the C4 alkane reflux tank after being temperature-controlled by a circulating cooling water condenser. A portion of the liquid C4 alkane is refluxed from the top of the extractive distillation column back into the extractive distillation column, and another portion of the liquid C4 alkane is collected as a product. The gaseous C4 alkane in the C4 alkane reflux tank is returned to the C4 alkane compressor.

[0040] The specific steps of the gas-phase C4 condensation step S2B include:

[0041] In step S2B1, the gaseous C4 alkane collected from the top of the extractive distillation column is directly condensed by the circulating cooling water condenser at the top of the extractive distillation column.

[0042] In step S2B2, the condensed C4 alkane enters the reflux tank at the top of the extractive distillation column. A portion of the C4 alkane is refluxed back into the extractive distillation column via the upper part, while the other portion is collected as product.

[0043] Preferably, the method further includes a step S3A of utilizing low-grade heat energy in a lean solvent, wherein step S3A specifically includes:

[0044] In step S3A1, the working fluid from the outlet of the working fluid storage tank of the closed heat pump system absorbs the low-grade heat energy of the lean solvent after heat exchange by the multi-stage heat exchanger through the working fluid evaporator.

[0045] In step S3A2, the gaseous working fluid that absorbs low-grade heat energy is then pressurized and heated by the working fluid compressor of the closed heat pump system.

[0046] In step S3A3, the pressurized and heated gaseous working fluid transfers its heat energy to the process material in the extractive distillation column through the second intermediate reboiler, and then enters the working fluid storage tank. Preferably, the working fluid after heat exchange is depressurized and cooled by a throttling valve and then condensed before entering the working fluid storage tank.

[0047] Preferably, the method includes a heat exchange step S3B for the lean solvent collected from the bottom of the analytical column, wherein step S3B specifically includes:

[0048] In step S3B1, the lean solvent collected from the bottom of the stripping column first transfers heat energy to the rich solvent through the rich solvent heater at the inlet of the stripping column.

[0049] In step S3B2, the lean solvent is then transferred to the process material in the extractive distillation column through the third reboiler in the middle of the extractive distillation column.

[0050] In step S3B3, the lean solvent is passed through the C4 evaporator or the C4 evaporator reboiler at the bottom of the tank to transfer heat energy to the mixed C4 feedstock.

[0051] In step S3B4, the lean solvent then transfers low-grade heat energy to the working fluid exiting from the working fluid storage tank via the working fluid evaporator.

[0052] In step S3B5, the lean solvent is finally cooled by a lean solvent cooler and then enters the extractive distillation column from the top.

[0053] Preferably,

[0054] In step S2, the bottom of the extractive distillation column is heated by the extractive distillation column reboiler, preferably by steam as the heat medium;

[0055] In step S3, the bottom of the stripping column is heated by the stripping column bottom reboiler, preferably using steam as the heat medium;

[0056] The C4 evaporator or tank is a C4 evaporator or a C4 evaporator tank.

[0057] Preferably, an open-loop heat pump system is used to transfer the low-grade heat energy of the vapor phase at the top of the extractive distillation column to the process material in the extractive distillation column whose temperature differs from that of the vapor phase at the top of the column by 0°C to 30°C, preferably by 0°C to 15°C. Alternatively, a closed-loop heat pump system is used to transfer the low-grade heat energy of the lean solvent after heat exchange in the desorption column through a multi-stage heat exchanger to the process material in the extractive distillation column whose temperature differs from that of the lean solvent after heat exchange by 0°C to 30°C, preferably by 0°C to 15°C.

[0058] Preferably, in step S2, the operating pressure of the extractive distillation column is 0.35 MPaG ~ 0.75 MPaG, more preferably 0.45 MPaG ~ 0.55 MPaG.

[0059] Preferably,

[0060] In step S2, the pressure range of the gaseous C4 alkane in the open heat pump system after being pressurized by the compressor is 0.45 MPaG ~ 2.5 MPaG, preferably 1.2 MPaG ~ 1.8 MPaG; the pressure range of the C4 alkane after being depressurized is 0.35 MPaG ~ 0.75 MPaG, preferably 0.45 MPaG ~ 0.55 MPaG.

[0061] And / or,

[0062] In step S3, the pressure range of the gaseous working fluid in the closed-loop heat pump system after being pressurized by the compressor is 0.45 MPaG~2.5 MPaG, preferably 1.2 MPaG~1.8 MPaG; the pressure range of the working fluid after being depressurized by the throttle valve is 0.2 MPaG~0.6 MPaG, preferably 0.25 MPaG~0.35 MPaG.

[0063] Preferably,

[0064] The preferred gaseous working fluid in the closed-loop heat pump system is butane or tetrafluoroethane, with n-butane being more preferred.

[0065] The C4 mixture contains 10 wt% to 90 wt% of C4 olefins, preferably 20 wt% to 80 wt%.

[0066] The extractant includes acetonitrile series solvents, morpholine and N-formylmorpholine series solvents, methyl ethyl ketone series solvents, sulfolane series solvents, N-methylpyrrolidone series solvents, etc., preferably an N-methylpyrrolidone solution with a water content of 1 wt% to 12 wt%, preferably with a water content of 8 wt%.

[0067] The positive and progressive effects of this utility model are as follows:

[0068] 1) The mixed C4 alkene separation process of this utility model with heat pump system can fully realize the efficient reuse of low-grade heat energy of the top vapor and low-grade heat energy of the solvent-poor solvent, greatly reduce the carbon emissions of the device, and strongly promote the comprehensive utilization of mixed C4.

[0069] 2) This invention utilizes a heat pump system to heat the process materials within the tower, partially vaporizing them and enhancing the gas-liquid separation effect within the tower. The concentration of C4 alkanes in the product increases from 98.2 wt% to 98.5 wt%. The enhanced separation effect of the extractive distillation tower further improves the stripping effect of the stripping tower on C4 olefins in the solvent-rich environment, increasing the concentration of C4 olefins in the product from 98.0 wt% to 98.2 wt%. Simultaneously, the total amount of gaseous products remains unchanged, and the recovery rates of C4 alkanes and C4 olefins are higher than those of the conventional N-methylpyrrolidone method. This means that both the recovery rate and purity of C4 alkanes and C4 olefins are improved.

[0070] 3) By installing a chilled water system at the top of the analytical tower, this utility model enables the analytical tower to operate at a lower pressure, thereby reducing the analytical temperature inside the entire analytical tower and reducing the amount of steam used for heating the analytical tower bottom, which further reduces the energy consumption of the device. Attached Figure Description

[0071] Figure 1This is a schematic diagram of the mixed C4 ether separation device with an open heat pump system according to Example 1;

[0072] Figure 2 This is a schematic diagram of the mixed C4 tetroxide separation device with a closed-loop heat pump system in Example 2;

[0073] Figure 3 This is a schematic diagram of a mixed C4 olefin separation device without a heat pump system, as shown in Comparative Example 1. Detailed Implementation

[0074] 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.

[0075] like Figure 1 and Figure 2 As shown, the mixed C4 alkylene separation device with a heat pump system of this utility model includes an open heat pump system that transfers the low-grade heat energy of the gas phase at the top of the extractive distillation column T2 to the process material in the extractive distillation column T2, and / or a closed heat pump system that transfers the low-grade heat energy of the lean solvent after desorption from the desorption column T3 through a multi-stage heat exchanger to the process material in the extractive distillation column T3.

[0076] like Figure 1 The diagram shows a mixed C4 alkane separation device with an open-loop heat pump system according to this invention. It includes a C4 evaporator or tank V1, an extractive distillation column T2, a stripping column T3, a C4 alkane reflux tank V2, a C4 olefin reflux tank V3, a C4 evaporator-reboiler E1, an extractive distillation column bottom reboiler E2, an extractive distillation column third intermediate reboiler E3, a stripping column reboiler E4, a chilled water condenser E5, a rich solvent heater E6, a lean solvent cooler E7, an extractive distillation column first intermediate reboiler E8, a lean solvent circulation pump P1, and a C4 alkane compressor C1. The C4 evaporator or tank V1 has a mixed C4 feed inlet. The mixed C4 feedstock enters the C4 evaporator or tank V1 through the mixed C4 feed inlet for vaporization to remove heavy components. The C4 evaporator or tank V1 is heated by the C4 evaporator-reboiler E1 at the bottom. Of course, the C4 evaporator or tank V1 can be either a C4 evaporator or a C4 evaporator tower. When the heavy components in the mixed C4 raw material are easy to separate, a C4 evaporator is used; when the heavy components in the mixed C4 raw material are difficult to separate, a C4 evaporator tower is preferred. Continuing as... Figure 1As shown, the vaporized mixed C4 enters the extractive distillation column T2, where it comes into countercurrent contact with the lean solvent circulating from the top of T2. The extractive distillation column T2 is heated by the reboiler E2 in the bottom of the column. The gaseous C4 alkane collected from the top of T2 is first pressurized and heated by the C4 alkane compressor C1 of an open heat pump system. The pressurized and heated C4 alkane then transfers its heat to the process material inside T2, whose temperature differs from the top gaseous phase temperature by 0°C to 30°C (preferably 0°C to 15°C), through the first intermediate reboiler E8. This transfers the heat to the process material, whose temperature differs from the top gaseous phase temperature by 0°C to 30°C, to fully utilize the low-grade heat energy of the gaseous alkane collected from the top of the column, achieving efficient reuse of low-grade energy. After heat exchange in the open heat pump system, the C4 alkane is condensed by reducing pressure and cooling through a throttling valve. After temperature control by a circulating cooling water condenser, it enters the C4 alkane reflux tank V2. Then, part of the C4 alkane in the tank is returned to the upper part of the extractive distillation column T2 via the reflux branch, while the other part is directly collected as product from the alkane collection branch. The operating pressure of the extractive distillation column T2 is 0.35 MPaG ~ 0.75 MPaG, preferably 0.5 MPaG ~ 0.55 MPaG.

[0077] Continue as Figure 1 As shown, after extractive distillation in column T2, a solvent rich in C4 olefins is formed in the bottom of the column. This rich solvent is heated by the solvent-rich heater E6 and then enters the stripping column T3. The stripping column reboiler E4 in the bottom of column T3 heats the process material within the column. Both the extractive distillation column reboiler E2 and the stripping column reboiler E4 utilize steam as the heat medium. Continuing... Figure 1As shown, the solvent-rich column T3 is heated and desorbed, and the gaseous olefins collected at the top of the column are first cooled by a chilled water condenser E5 before entering the C4 olefin reflux tank V3. Part of the C4 olefins in the tank are refluxed back to the upper part of the desorption column T3 via a reflux branch, while the other part is collected directly as product from the olefin collection branch. The chilled water system is a chilled water condenser E5 with a temperature of -10℃ to 10℃, preferably a chilled water condenser with a temperature of -5℃ to 5℃, which can cool the gaseous olefins collected at the top of the column to a low temperature of 0℃ to 20℃ or 5℃ to 15℃. This chilled water condenser uses a circulating refrigerant available from the plant or equipment, including calcium chloride aqueous solution, propylene glycol aqueous solution, ethylene glycol aqueous solution, etc., preferably propylene glycol aqueous solution or ethylene glycol aqueous solution. Because the top of the stripping column T3 utilizes a chilled water condenser E5 to cool the extracted C4 olefins to a lower temperature than in existing technologies, the top of stripping column T3 can operate at atmospheric or low pressure. Specifically, the operating pressure at the top of stripping column T3 is 0.01 MPaG ~ 0.4 MPaG, preferably 0.05 MPaG ~ 0.1 MPaG, further reducing the stripping temperature within the entire stripping column T3. This reduces the amount of steam used for heating the bottom of stripping column T3, thus lowering the overall energy consumption of the unit. Furthermore, the separation effect of olefins cooled to a low temperature by chilled water is better under low pressure, improving the recovery rate and purity of C4 olefins. Simultaneously, since N-methylpyrrolidone solution is used as the extraction solvent, both the extractive distillation column and the stripping column can be single-column structures to meet the separation of mixed C4 olefins, further optimizing the process flow and simplifying the number of equipment. Continuing... Figure 1 As shown, the lean solvent in the bottom of the stripping column T3 is pumped by the lean solvent circulation pump P1, then heat-exchanged by a multi-stage heat exchanger and temperature-controlled by the lean solvent cooler E7 at the inlet of the extractive distillation column T2 before being circulated back to the extractive distillation column T2. ​​The multi-stage heat exchanger includes, in sequence, a rich solvent heater E6 at the inlet of the stripping column T3, a third intermediate reboiler E3 in the extractive distillation column T2, and a C4 evaporator reboiler E1 at the bottom of the C4 evaporator or tank V1. Of course, the lean solvent can also pass through the intermediate reboiler of the stripping column, the reboiler of the extractive distillation column, etc. (not shown in the figure) to make full use of the thermal energy of the lean solvent. The 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 an N-methylpyrrolidone solution with a water content of 1 wt% to 12 wt%.

[0078] like Figure 2The diagram shows a mixed C4 alkane separation device with a closed-loop heat pump system according to this invention. It includes a C4 evaporator or tank V1, an extractive distillation column T2, a stripping column T3, a C4 alkane reflux tank V2, a C4 olefin reflux tank V3, a C4 evaporator reboiler E1, an extractive distillation column bottom reboiler E2, an extractive distillation column third intermediate reboiler E3, a stripping column reboiler E4, a chilled water condenser E5, a rich solvent heater E6, a lean solvent cooler E7, a lean solvent circulating pump P1, a working fluid storage tank V4, a working fluid compressor C2, an extractive distillation column second intermediate reboiler E9, a circulating cooling water system (i.e., a circulating cooling water condenser E10), a working fluid evaporator E11, and a lean solvent circulating pump P1. The C4 evaporator or tank V1 has a mixed C4 feed inlet, through which the mixed C4 feed material enters the C4 evaporator or tank V1 for vaporization to remove heavy components. The C4 evaporator or tank V1 is heated by the C4 evaporator-reboiler E1 at the bottom. Of course, the C4 evaporator or tank V1 can be either a C4 evaporator or a C4 evaporator tower. When the heavy components in the mixed C4 feedstock are easily separated, a C4 evaporator is used; when the heavy components in the mixed C4 feedstock are difficult to separate, a C4 evaporator tower is preferred. Continuing as... Figure 2 As shown, the vaporized mixed C4 enters the extractive distillation column T2, where it comes into countercurrent contact with the lean solvent circulating from the top of T2. The extractive distillation column T2 heats the process material within the column via the reboiler E2. After extractive distillation in T2, gaseous alkanes are collected from the top of the column. These gaseous alkanes are directly cooled by the circulating cooling water condenser E3 and then enter the C4 alkane reflux tank V2. A portion of the C4 alkanes in the tank is then refluxed back into the extractive distillation column T2 via the reflux branch, while the remaining portion is collected directly as product from the alkane collection branch. The operating pressure of the extractive distillation column T2 is 0.35 MPaG ~ 0.75 MPaG, preferably 0.5 MPaG ~ 0.55 MPaG.

[0079] Continue as Figure 2As shown, the bottom of extractive distillation column T2 forms a solvent rich in C4 olefins. This olefin-rich solvent enters the 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 inside T3. Both the extractive distillation column reboiler E2 and the stripping column reboiler E4 use steam as the heat medium. The solvent rich in solvent is heated and desorbed in stripping column T3, and gaseous olefins are collected from the top of the column. The collected gaseous olefins are first cooled by chilled water condenser E5 and then enter the C4 olefin reflux tank V3. Part of the C4 olefins in the tank are refluxed back to stripping column T3 via the reflux branch, while the other part 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 E5 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 equipment, including calcium chloride aqueous solution, propylene glycol aqueous solution, ethylene glycol aqueous solution, etc., preferably propylene glycol aqueous solution or ethylene glycol aqueous solution. Because the top of the stripping column T3 utilizes a chilled water condenser E5 to cool the extracted C4 olefins to a lower temperature than existing technologies, the top of stripping column T3 can operate at atmospheric or low pressure. Specifically, the operating pressure at the top of stripping column T3 is 0.01 MPaG ~ 0.4 MPaG, preferably 0.05 MPaG ~ 0.1 MPaG, thereby further reducing the stripping temperature within the entire stripping column T3. This reduces the amount of steam used for heating the bottom of stripping column T3, thus lowering the overall energy consumption of the unit. Furthermore, the separation effect of olefins cooled to a low temperature by chilled water is better under low pressure, improving the recovery rate and purity of C4 alkanes and C4 olefins. Simultaneously, since N-methylpyrrolidone solution is used as the extraction solvent, both the extractive distillation column and the stripping column can be single-column structures to meet the separation of mixed C4 alkanes, further optimizing the process flow and simplifying the number of equipment. Continuing... Figure 2As shown, the lean solvent in the bottom of the stripping column T3 is pumped by the lean solvent circulation pump P1 at the bottom of the stripping column T3, and then successively heats the solvent through a multi-stage heat exchange device, a closed-loop heat pump system, and a lean solvent cooler E7 before entering the upper part of the extractive distillation column T2, making full use of the thermal energy and low-grade thermal energy of the lean solvent. The multi-stage heat exchange device includes, in sequence, a rich solvent heater E6 at the inlet of the stripping column T3, a third intermediate reboiler E3 in the extractive distillation column T2, and a C4 evaporator reboiler E1 at the bottom of the C4 evaporator or tank V1. Of course, the lean solvent can also pass through the intermediate reboiler of the stripping column, the reboiler of the extractive distillation column, etc. (not shown in the figure) to fully utilize its thermal energy. The 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 an N-methylpyrrolidone solution with a water content of 1 wt% to 12 wt%.

[0080] Continue as Figure 2 As shown, the low-grade heat energy of the lean solvent after desorption in column T3, after heat exchange in a multi-stage heat exchanger, is enhanced to high-grade heat energy by a closed-loop heat pump system and then transferred to the process material in the extractive distillation column, where the temperature difference between the lean solvent after heat exchange in the multi-stage heat exchanger and the process material is 0℃~30℃, preferably 0℃~15℃, to fully utilize the low-grade heat energy of the lean solvent and achieve efficient energy recovery. The closed-loop heat pump system includes a working fluid evaporator E11, a working fluid compressor C2, and a working fluid storage tank V4. Specifically, the working fluid exiting from the outlet of the working fluid storage tank V4 of the closed-loop heat pump system absorbs the low-grade heat energy of the lean solvent after heat exchange in the multi-stage heat exchanger through the working fluid evaporator E11. The preferred gaseous working fluid is butane, tetrafluoroethane, or n-butane. The gaseous working fluid, having absorbed low-grade heat energy, is then pressurized and heated by the working fluid compressor C2 of the closed-loop heat pump system. After pressurization and heating, the gaseous working fluid elevates its heat energy to high-grade heat energy and is transferred through the second intermediate reboiler E9 of the extractive distillation column to the process material in the extractive distillation column T2, where the temperature difference between the process material and the lean solvent after heat exchange with the multi-stage heat exchanger is 0℃~30℃ (preferably 0℃~15℃). The material then passes through a throttling valve to reduce pressure and temperature, condenses, and enters the working fluid storage tank V4. Simultaneously, the gaseous working fluid condenses into a liquid phase. The liquid working fluid at the outlet of the working fluid storage tank V4 recirculates into the working fluid evaporator E11, where it vaporizes after heat exchange with the lean solvent. A portion of the gaseous working fluid is supplied to the working fluid compressor C2 from the top outlet of the tank.

[0081] Table 1. Components and content of mixed C4 feedstock in the separation of mixed C4 alkylenes according to this invention.

[0082]

[0083] Example 1

[0084] As shown in Figure 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 gaseous 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 14 (8 wt% water + 92 wt% N-methylpyrrolidone) is cooled to 40℃ by the lean solvent cooler E7 before entering the upper part of the extractive distillation column T2. ​​The lean solvent inlet is located above the mixed C4 feedstock inlet. Gaseous C4 alkane 3, with a temperature of 59.2℃ at the top of the extractive distillation column T2, is pressurized and heated in the C4 alkane compressor C1. After compression, the temperature of the C4 alkane is 100.6℃, and the pressure is 1.5 MPaG. MPaG; The compressed C4 alkane 4 enters the first intermediate reboiler E8 of the extractive distillation column, where the temperature of the process material is 72℃. After heat exchange, the temperature of the C4 alkane is 97℃. The gaseous C4 alkane 5 then condenses into a liquid phase. The liquid C4 alkane 5, after being depressurized and cooled, enters the C4 alkane reflux tank V2, where the temperature is 58.9℃ and the pressure is 0.55 MPaG. The gaseous C4 alkane 8 in the tank returns to the compressor C1. A portion of the liquid C4 alkane 6 is refluxed to the upper part of the extractive distillation column T2, and the remaining portion is collected as liquid C4 alkane product 7 at a rate of 7120 kg / h. The concentration of n-butane and isobutane in the C4 alkane product is 98.5 wt%. The temperature of the solvent-rich 9 in the bottom of the extractive distillation column T2 is 101.6℃, the pressure is 0.61 MPaG, and the flow rate is 149000 kg / hr. It passes through the solvent-rich heater E6 by pressure difference. After heat exchange, it is then transported to the desorption tower T3, where the temperature of the solvent-rich solvent is 121.3 ℃.

[0085] After the rich solvent is desorbed in stripping column T3, the gaseous C4 olefins 10 at the top of the column are condensed in the top chilled water condenser E5 by circulating chilled water. The temperature is 11.3 ℃ and the pressure is 0.045 MPaG. A portion of the C4 olefins 11 is refluxed to the upper part of stripping column T3, and the other portion is collected as C4 olefin product 12 at a rate of 12080 kg / h. The concentration of butene-1, isobutene, cis-2-butene, and trans-2-butene in the C4 olefin product is 98.2 wt%. The temperature of the lean solvent 13 in the bottom of stripping column T3 is 151.8 ℃, the pressure is 0.09 MPaG, and the flow rate is 136920 kg / hr.

[0086] The lean solvent is pumped by lean solvent transfer pump P1 to the rich solvent heater E6, where it exchanges heat with the rich solvent and its temperature drops to 125°C. It then enters the third intermediate reboiler E3 of the extractive distillation column, where it exchanges heat with the process material in the column and its temperature drops to 103°C. After exchanging heat with the reboiler E1 of the evaporator, its temperature drops to 78°C. It then goes to the lean solvent cooler E7, where it exchanges heat with the circulating cooling water and its temperature drops to 40°C. Finally, the lean solvent 14 is used as an extractant in the extractive distillation column T2 for recycling.

[0087] Example 2

[0088] according to Figure 2 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 vaporous 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 E7 and then enters the upper part of the extractive distillation column T2. ​​The lean solvent inlet is above the mixed C4 feedstock inlet. The vaporous C4 alkane at the top of the extractive distillation column T2 is condensed by the circulating cooling water in the circulating cooling water condenser E10, with a temperature of 58.9℃ and a pressure of 0.55 MPaG. Subsequently, a portion of the liquid C4 alkane 4 is refluxed back to the extractive distillation column T2. The upper portion, another part, is collected as liquid-phase C4 alkane product 5, with a collection rate of 7120 kg / h. The concentration of n-butane and isobutane in the C4 alkane product is 98.5 wt%. The temperature of the solvent-rich 6 in the bottom of the extractive distillation column T2 is 101.6 ℃, the pressure is 0.61 MPaG, and the flow rate is 149000 kg / hr. After heat exchange via the solvent-rich heater E6 due to pressure difference, it is then transported to the stripping column T3. After heat exchange, the temperature of the solvent-rich 6 is 121.3 ℃.

[0089] After the rich solvent is desorbed in stripping column T3, the gaseous C4 olefins 7 at the top of the column are condensed in the circulating chilled water condenser E5 at the top of the column, with 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 12080 kg / h. The concentration of butene-1, isobutene, cis-2-butene, and trans-2-butene in the C4 olefin product is 98.2 wt%. The temperature of the lean solvent 10 in the bottom of stripping column T3 is 151.8 ℃, the pressure is 0.09 MPaG, and the flow rate is 136920 kg / hr.

[0090] The lean solvent is pumped by lean solvent transfer pump P1 to the rich solvent heater E6, where it exchanges heat with the rich solvent and its temperature drops to 125°C. It then enters the third intermediate reboiler E3 of the extractive distillation column, where it exchanges heat with the process material inside the column and its temperature drops to 103°C. After exchanging heat with the reboiler E1 of the evaporator, its temperature drops to 78°C. It then exchanges heat with the working fluid evaporator E11 and its temperature drops to 48°C. Subsequently, it enters the lean solvent cooler E7 and exchanges heat with the circulating cooling water, where its temperature drops to 40°C. Finally, the lean solvent 11 is used as the extractant in the extractive distillation column T2 for recycling.

[0091] The gaseous working fluid 12 (the working fluid is n-butane, the same below) is pressurized and heated in the working fluid compressor C2. After compression, the working fluid temperature is 91 ℃ and the pressure is 1.2 MPaG. The compressed working fluid 13 enters the second intermediate reboiler E9 of the extractive distillation column. The temperature of the process material in the column is 72 ℃. After heat exchange, the temperature of the gaseous working fluid is 91 ℃, and at the same time, the gaseous working fluid condenses into a liquid phase. The liquid working fluid 14 enters the working fluid storage tank V4 after being depressurized and cooled. The temperature inside the tank is 42 ℃ and the pressure is 0.3 MPaG. The liquid working fluid 15 at the outlet of the working fluid storage tank V4 enters the working fluid evaporator E11. After heat exchange with the low-grade lean solvent after heat exchange, it vaporizes. The gaseous working fluid 16 at the top outlet of the tank returns to the working fluid compressor C2.

[0092] Comparative Example 1

[0093] like Figure 3As shown, the process for separating mixed C4 alkanes from 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 E7 before entering the upper part of the extractive distillation column T2. ​​The lean solvent inlet is located above the mixed C4 feedstock inlet. The gaseous C4 alkane 3 at the top of the extractive distillation column T2 is condensed in a circulating cooling water condenser E3. After condensation by the circulating cooling water, the temperature is 58.9 °C and the pressure is 0.55 MPaG. A portion of the C4 alkane 4 is refluxed to the upper part of the extractive distillation column T2, while the other portion is collected as C4 alkane product 5 at a rate of 7120 kg / h. The concentration of n-butane and isobutane in the C4 alkane product is 98.2 wt%. The temperature of the solvent-rich material 6 in the bottom of the extractive distillation column T2 is 101.6 ℃, the pressure is 0.61 MPaG, and the flow rate is 149000 kg / hr. After heat exchange via the solvent-rich heater E6 due to pressure difference, it is then transported to the stripping column T3. After heat exchange, the temperature of the solvent-rich material is 121.3 ℃.

[0094] After the rich solvent is desorbed in stripping column T3, the gaseous C4 olefins 7 at the top of the column are condensed in the top chilled water condenser E5 by circulating chilled water. The temperature is 11.3 ℃ and the pressure is 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 at a rate of 12080 kg / h. The concentration of butene-1, isobutene, cis-2-butene, and trans-2-butene in the C4 olefin product is 98.0 wt%. The temperature of the lean solvent 10 in the bottom of stripping column T3 is 151.8 ℃, the pressure is 0.09 MPaG, and the flow rate is 136920 kg / hr.

[0095] The lean solvent is pumped by lean solvent transfer pump P1 to the rich solvent heater E6, where it exchanges heat with the rich solvent and its temperature drops to 125°C. It then enters the third intermediate reboiler E3 of the extractive distillation column, where it exchanges heat with the process material in the column and its temperature drops to 103°C. After exchanging heat with the reboiler E1 of the evaporator, its temperature drops to 78°C. It then goes to the lean solvent cooler E7, where it exchanges heat with the circulating cooling water and its temperature drops to 40°C. Finally, the lean solvent 11 is used as an extractant in the extractive distillation column T2 for recycling.

[0096] In the N-methylpyrrolidone solution method for separating mixed C4 olefins, only considering solvent or steam energy recovery does not fully realize energy saving and high efficiency. This invention uses a mixed C4 olefin separation method with a heat pump system to further improve the energy efficiency of the N-methylpyrrolidone method for separating mixed C4 olefins. At the same time, the separation effect of mixed C4 olefins is significant, which can meet the requirements of high recovery rate and high purity of C4 olefins and C4 olefins. The effect comparison under the same feed conditions is shown in Table 2 below.

[0097] Table 2 Comparison of different process flows for the separation of N-methylpyrrolidone mixed carbotetraenes using the solution method

[0098]

[0099] Conclusions: 1) In the separation process of mixed C4 alkanes, Example 1, by adding an open heat pump system to enhance the recovery of low-grade heat energy from C4 alkanes, can reduce the overall system energy consumption from 69.5 kg standard oil / t feed in Comparative Example 1 to 57.0 kg standard oil / t feed. Example 2, by adding a closed heat pump system to enhance the recovery of low-grade heat energy from lean solvent, can also reduce the overall system energy consumption from 69.5 kg standard oil / t feed in Comparative Example 1 to 56.5 kg standard oil / t feed. 2) In the heat pump system, the process material in the extractive distillation column is heated within the first intermediate reboiler and / or the second intermediate reboiler of the extractive distillation column. Partial vaporization of the process material enhances the gas-liquid separation effect within the column, increasing the concentration of C4 alkanes from 98.2 wt% to 98.5 wt%. The enhanced separation effect of the extractive distillation column improves the desorption effect of the stripping column on the rich solvent, increasing the concentration of C4 alkanes from 98.0 wt% to 98.2 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.

[0100] 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 C4-tetraalkylene separation device with a heat pump system, characterized in that... The mixed C4 olefin separation device includes: 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 the C4 evaporator or tank; The analytical column is connected to the bottom of the extractive distillation column; The extractive distillation column is characterized by being further connected to a heat pump system.

2. The mixed C4 ether separation device with a heat pump system as described in claim 1, characterized in that, The heat pump system includes an open heat pump system that transfers the low-grade heat energy of the gas phase at the top of the extractive distillation column to the process material inside the extractive distillation column, and / or a closed heat pump system that transfers the low-grade heat energy of the lean solvent after desorption from the desorption column through a multi-stage heat exchanger to the process material inside the extractive distillation column.

3. The mixed C4 ether separation device with a heat pump system as described in claim 2, characterized in that... The open-loop heat pump system includes: a C4 alkane compressor; the top of the extractive distillation column is connected to the inlet of the C4 alkane compressor; the outlet of the C4 alkane compressor is connected to the inlet of the C4 alkane reflux tank after heat exchange with the first intermediate reboiler of the extractive distillation column; and the gas phase of the C4 alkane reflux tank is connected to the upper gas phase makeup gas of the C4 alkane compressor.

4. The mixed C4-tetraalkylene separation device with a heat pump system as described in claim 3, characterized in that... 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.

5. The mixed C4 alkylene separation device with a heat pump system as described in claim 2, characterized in that... The closed-loop heat pump system includes: a working fluid evaporator for exchanging low-grade heat energy from lean solvent after multi-stage heat exchange, a working fluid compressor, and a working fluid storage tank. The outlet of the working fluid evaporator is connected to the inlet of the working fluid compressor. The outlet of the working fluid compressor is connected to the second intermediate reboiler of the extractive distillation column after heat exchange and then connected to the inlet of the working fluid storage tank. The outlet of the working fluid storage tank is connected to the inlet of the working fluid evaporator.

6. The mixed C4 alkylene separation device with a heat pump system as described in claim 5, characterized in that, The gas phase of the working fluid storage tank is connected to the upper gas phase of the working fluid compressor.

7. The mixed C4 alkylene separation device with a heat pump system as described in claim 5, 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.

8. The mixed C4 alkylene separation device with a heat pump system as described in claim 7, characterized in that, The top of the extractive distillation column is connected to the inlet of the C4 alkane reflux tank by a circulating cooling water system for cooling the separated and refluxed C4 alkane. The circulating cooling water system is a circulating cooling water condenser.

9. The mixed carbotetraene separation device with a heat pump system as described in claim 1, 2, 3 or 5, characterized in that... The top of the analytical column is connected to the inlet of the C4 olefin reflux tank. A chilled water system is also connected between the top of the analytical column and the inlet of the C4 olefin reflux tank to cool the C4 olefin after analytical treatment and before reflux.

10. The mixed C4 alkylene separation device with a heat pump system as described in claim 9, characterized in that, The chilled water system is a chilled water condenser with a temperature range of -10℃ to 10℃.

11. The mixed C4-tetraalkylene separation device with a heat pump system as described in claim 10, characterized in that, The chilled water system is a chilled water condenser with a temperature range of -5℃ to 5℃.

12. The mixed C4 ether separation device with a heat pump system as described in claim 11, characterized in that... The top of the analytical column is at atmospheric pressure or low pressure, and the pressure at the top of the analytical column is 0.01~0.5 MPaG.

13. The mixed C4 ether separation device with a heat pump system as described in claim 12, characterized in that... The pressure at the top of the analytical column is 0.04~0.1 MPaG.

14. The mixed C4-tetraalkylene separation device with a heat pump system as described in claim 2, characterized in that... The extractive distillation column also has a third intermediate reboiler and a bottom 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 first exchanges heat with the rich solvent heater at the inlet of the stripping column, then exchanges heat with the third intermediate reboiler of the extractive distillation column, then exchanges heat with the C4 evaporator reboiler, and finally exchanges heat with the upper part of the extractive distillation column after being temperature controlled by the lean solvent cooler.

15. The mixed C4T olefin separation device with a heat pump system as described in claim 14, characterized in that... In a mixed C4 alkene separation system with a closed-loop heat pump system, the bottom of the stripping column first exchanges heat with the solvent-rich heater at the inlet of the stripping column, then exchanges heat with the third intermediate reboiler of the extractive distillation column, then exchanges heat with the C4 evaporator-reboiler, and then exchanges heat with the working fluid evaporator in the closed-loop heat pump system. Finally, after being temperature-controlled by a lean solvent cooler, it is connected to the upper part of the extractive distillation column.

16. The mixed C4 alkylene separation device with a heat pump system as described in claim 9, 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.

17. The mixed C4 alkylene separation device with a heat pump system as described in claim 2, characterized in that... An open-loop heat pump system that transfers the low-grade heat energy of the vapor phase at the top of the extractive distillation column to the process material in the extractive distillation column whose temperature differs from that of the vapor phase at the top of the column by 0°C to 30°C, and / or a closed-loop heat pump system that transfers the low-grade heat energy of the lean solvent after desorption from the stripping column through a multi-stage heat exchanger to the process material in the extractive distillation column whose temperature differs from that of the lean solvent after heat exchange by 0°C to 30°C.

18. The mixed C4 alkylene separation device with a heat pump system as described in claim 17, characterized in that... An open-loop heat pump system that transfers the low-grade heat energy of the vapor phase at the top of the extractive distillation column to the process material in the extractive distillation column whose temperature differs from that of the vapor phase at the top of the column by 0°C to 15°C, and / or a closed-loop heat pump system that transfers the low-grade heat energy of the lean solvent after desorption from the stripping column through a multi-stage heat exchanger to the process material in the extractive distillation column whose temperature differs from that of the lean solvent after heat exchange by 0°C to 15°C.

19. The mixed C4 ether separation device with a heat pump system as described in claim 1, characterized in that... The bottom of the stripping column is equipped with a stripping column bottom 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; 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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