Separation method and separation system for a wide-boiling binary mixture

Abstract

The present application relates to the technical field of mixed material separation, and discloses a separation method and a separation system for a wide-boiling binary mixture. The separation method comprises the following steps: S1, first separating a wide-boiling binary mixture to obtain a low-temperature-level material, a high-temperature-level material and an optional medium-temperature-level material; wherein the temperature difference △T between the boiling point of the high-temperature-level material and the boiling point of the low-temperature-level material is greater than 20 DEG C; S2, first compressing the low-temperature-level material to obtain a first compressed material; dividing the first compressed material into two parts, and second compressing one part of the first compressed material to obtain a second compressed material; S3, if the boiling point T1 of the high-temperature-level material is less than 130 DEG C, performing the operation of step S31 or S32, or if the boiling point T1 of the high-temperature-level material is greater than 130 DEG C, performing the operation of step S33. The present application realizes the separation of a wide-boiling binary mixture by adopting a two-stage steam recompression heat pump technology, and realizes energy saving and consumption reduction.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of mixed material separation, in particular to a separation method and separation system for wide-boiling binary mixtures. BACKGROUND

[0002] Rectification technology is involved in many fields, including medicine, oil refining, chemical industry and food processing, etc. Rectification technology is mainly used for the separation of mixtures, and in particular, in modern chemical production and petroleum refining, rectification is one of the most mature and widely used separation technologies. However, the energy consumption of rectification process is huge. It is estimated that 40% to 70% of the energy consumption in chemical processes is used for separation, and the energy consumption of rectification accounts for 95% of it. The energy saving of rectification process firstly requires the selection or design of high-efficiency rectification equipment, and secondly determines the appropriate operating conditions and parameters, and reasonably selects multi-effect rectification, heat pump rectification, intermediate condenser, intermediate reboiler, etc.

[0003] With the development of energy-saving technology for rectification, the energy-saving benefits of heat pump rectification gradually stand out. The steam re-compression heat pump technology is a very promising technology. The principle of traditional steam re-compression heat pump technology is to change the steam with lower temperature at the top of the tower into steam with higher temperature through a compressor, and then use the heat released by the steam with higher temperature to provide the energy required by the reboiler at the bottom of the tower, thereby improving the energy-saving benefits of the rectification process. Currently, there are many sets of devices using steam re-compression heat pump rectification technology in industry. However, due to the use of compressors, including the requirement for the temperature of compressed steam and high equipment cost, the process parameters have relatively strict requirements. The traditional steam re-compression heat pump rectification technology is mainly suitable for the case where the temperature difference between the top and the bottom of the tower is within 15℃, and is not suitable for the case where the bottom temperature is greater than 130℃. For the rectification process of separating wide-boiling mixtures, the temperature difference between the top and the bottom of the tower is usually large. If the traditional steam re-compression heat pump rectification technology is used, it will result in high compressor cost, and the large compression ratio will require higher performance of the compressor, which may cause safety problems in actual application. SUMMARY

[0004] The purpose of the present application is to overcome the application limitation of traditional heat pump energy-saving technology in the separation of wide-boiling mixtures in the prior art, and to provide a separation method and separation system for wide-boiling binary mixtures. The present application uses two-stage steam re-compression heat pump technology to separate wide-boiling binary mixtures, further saves energy consumption in the separation of wide-boiling mixtures, and achieves the purpose of energy saving and consumption reduction.

[0005] In order to achieve the above-mentioned purpose, the present application provides a separation method for wide-boiling binary mixtures, which comprises:

[0006] S1, separating a wide-boiling binary mixture to obtain a low-temperature material, a high-temperature material and optionally a medium-temperature material; wherein the temperature difference ΔT between the boiling point of the high-temperature material and the boiling point of the low-temperature material is greater than 20℃;

[0007] S2, performing primary compression on the low-temperature material to obtain a primary compressed material; dividing the primary compressed material into a material a and a material b, and performing secondary compression on the material a to obtain a secondary compressed material;

[0008] S3, if the boiling point T1 of the high-temperature material is less than 130℃, performing the operation of step S31 or S32, if the boiling point T1 of the high-temperature material is greater than 130℃, performing the operation of step S33;

[0009] S31, performing first heat exchange between the secondary compressed material and the high-temperature material, performing reboiling treatment on the high-temperature material after the first heat exchange to obtain a first high-boiling point material; and performing condensation separation on the secondary compressed material after the first heat exchange to obtain a first low-boiling point material;

[0010] S32, performing second heat exchange between the material b and the medium-temperature material, returning the medium-temperature material after the second heat exchange, performing condensation separation on the primary compressed material after the second heat exchange to obtain a second low-boiling point material; performing third heat exchange between the secondary compressed material and the high-temperature material, and performing reboiling treatment on the high-temperature material after the third heat exchange to obtain a second high-boiling point material; and performing condensation separation on the secondary compressed material after the third heat exchange to obtain a second low-boiling point material;

[0011] S33, performing fourth heat exchange between the secondary compressed material and the medium-temperature material, returning the medium-temperature material after the fourth heat exchange, performing condensation separation on the secondary compressed material after the fourth heat exchange to obtain a third low-boiling point material; and performing reboiling treatment on the high-temperature material to obtain a third high-boiling point material.

[0012] The second aspect of the present application provides a separation system for a wide-boiling binary mixture, the separation system comprising: a separation tower, a primary compressor, a secondary compressor, a condenser, a tower bottom reboiler and an optional auxiliary reboiler, and at least one of a feed preheater and an intermediate reboiler; wherein,

[0013] The separation tower comprises a raw material inlet, a tower top material outlet, a tower bottom material outlet and an optional intermediate material outlet; wherein the distance from the raw material inlet to the tower top material outlet is less than the distance from the intermediate material outlet to the tower top material outlet;

[0014] The primary compressor is communicated with the overhead material outlet of the separation tower; the secondary compressor is communicated with the primary compressor; the feed preheater is communicated with the raw material inlet of the separation tower; the bottom reboiler is communicated with the bottom material outlet of the separation tower; the auxiliary reboiler is communicated with the bottom material outlet of the separation tower; the intermediate reboiler is communicated with the intermediate material outlet of the separation tower; the condenser is communicated with the separation tower and at least two of the feed preheater, the bottom reboiler and the intermediate reboiler.

[0015] By the technical scheme, the application has the following beneficial technical effects:

[0016] 1) The separation method of the wide-boiling binary mixture provided by the method can realize the separation of the wide-boiling binary mixture by using the two-stage steam re-compression heat pump technology, the principle of the traditional steam re-compression heat pump technology is applied to the separation process in the wide-boiling mixture separation process, and the method can be applied to the case that the temperature difference between the tower top and the tower bottom is greater than 20℃. In the process of separating the wide-boiling binary mixture, the steam re-compression heat pump technology can save energy consumption.

[0017] 2) The application solves the limitation of the traditional heat pump energy-saving technology in the wide-boiling separation process (the traditional heat pump technology is harsh in use condition, and the heat pump is generally not suitable for the case that the temperature difference between the tower top and the tower bottom is greater than 15℃), the method is suitable for most wide-boiling separation processes, and the use range of the heat pump energy-saving technology is expanded; because the rectifying tower and the heat pump have multiple combination modes, it is difficult to select the best structure, the method provided by the application can quickly select the best initial structure according to different feed conditions, and a large amount of energy can be saved under the premise of the smallest heat pump power consumption compared with the case of not using the heat pump.

[0018] 3) The system combines the two-stage steam re-compression heat pump with the feed preheater, the intermediate reboiler, the bottom reboiler and the like, the first-stage compression of the two-stage steam re-compression heat pump is used to pressurize the tower top steam and then deliver the steam to the feed preheater or the intermediate reboiler, and the second-stage compression of the two-stage steam re-compression heat pump is used to pressurize the steam compressed by the first-stage compression and then deliver the steam to the intermediate reboiler or the bottom reboiler. The system is suitable for the separation of most wide-boiling binary mixtures, and a large amount of energy can be saved under the premise of the smallest heat pump power consumption. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a schematic diagram of the separation system of the wide-boiling binary mixture provided by the embodiment 1 of the application;

[0020] Figure 2 is a schematic diagram of the separation system of the wide-boiling binary mixture provided by the embodiment 2 of the application;

[0021] Figure 3 is a schematic diagram of a separation system of a wide-boiling binary mixture provided by embodiment 3 of the present application;

[0022] Figure 4 is a schematic diagram of a separation system not using a heat pump. DETAILED DESCRIPTION

[0023] The endpoints of the ranges and any values claimed herein are presented only as approximations. The ranges and values are understood to include values approximating the stated ranges and values. For example, a range of "1 to 5" is intended to include any number between (and the integers) 1 and 5. Any numerical range recited herein is intended to include all sub-ranges subsumed therein. For example, a range of "1 to 10" is intended to include any sub-range between (and the integers) 1 and 10, for example, 1 to 6.1 to 2.2 to 4.5 to 5.5 to 6, 3 to 7, and so forth.

[0024] A first aspect of the present application provides a separation method of a wide-boiling binary mixture, the separation method comprising the following steps:

[0025] S1, performing a first separation on the wide-boiling binary mixture to obtain a low-temperature material, a high-temperature material, and optionally a medium-temperature material; wherein the high-temperature material has a boiling point difference of >20℃ from the boiling point of the low-temperature material;

[0026] S2, performing a primary compression on the low-temperature material to obtain a primary compressed material; dividing the primary compressed material into an a material and a b material, and performing a secondary compression on the a material to obtain a secondary compressed material;

[0027] S3, if the boiling point of the high-temperature material is <130℃, performing the operation of step S31 or S32, or if the boiling point of the high-temperature material is >130℃, performing the operation of step S33;

[0028] S31, performing a first heat exchange on the secondary compressed material and the high-temperature material, performing a reboiling treatment on the high-temperature material after the first heat exchange to obtain a first high-boiling point material, and performing a condensation separation on the secondary compressed material after the first heat exchange to obtain a first low-boiling point material;

[0029] S32, performing a second heat exchange on the b material and the medium-temperature material, returning the medium-temperature material after the second heat exchange, performing a condensation separation on the primary compressed material after the second heat exchange to obtain a second low-boiling point material, performing a third heat exchange on the secondary compressed material and the high-temperature material, performing a reboiling treatment on the high-temperature material after the third heat exchange to obtain a second high-boiling point material, and performing a condensation separation on the secondary compressed material after the third heat exchange to obtain a second low-boiling point material;

[0030] S33. The secondary compressed material and the medium-temperature material are subjected to a fourth heat exchange. The medium-temperature material after the fourth heat exchange is returned. The secondary compressed material after the fourth heat exchange is condensed and separated to obtain a third low-boiling-point substance. The high-temperature material is reboiled to obtain a third high-boiling-point substance.

[0031] In this invention, after the material is separated by the separation tower, the material separated from the top of the tower is the low-temperature material, the material separated from the bottom of the tower is the high-temperature material, and the material separated from the side stream of the separation tower is the medium-temperature material. Furthermore, the boiling point of the low-temperature material is less than the boiling point of the medium-temperature material, which in turn is less than the boiling point of the high-temperature material.

[0032] In this invention, "optional" refers to something that is optional. For example, the intermediate-temperature material is optional. In some embodiments, after the first separation, a low-temperature material, a high-temperature material, and an intermediate-temperature material are obtained, such as... Figure 2 and Figure 3 As shown. In other embodiments, after the first separation, low-temperature material and high-temperature material are obtained. There is no medium-temperature material, such as... Figure 1 As shown.

[0033] In this invention, step S31 corresponds to Figure 1 The diagram shown; step S32, corresponding to Figure 2 The diagram shown; step S33, corresponding to Figure 3 The diagram shown is shown in the image.

[0034] In the first heat exchange, the secondary compressed material provides heat to the high-temperature material; in the second heat exchange, the primary compressed material provides heat to the medium-temperature material; in the third heat exchange, the secondary compressed material provides heat to the high-temperature material; and in the fourth heat exchange, the secondary compressed material provides heat to the medium-temperature material.

[0035] This invention addresses the limitations of traditional heat pump energy-saving technology in wide-boiling-point separation processes. Traditional vapor recompression heat pump technology is only suitable for situations where the temperature difference between the top and bottom of the column is small (generally less than 15°C). However, in the separation of wide-boiling-point binary mixtures, the temperature difference between the top and bottom of the column is large, making traditional vapor recompression heat pump technology unsuitable. The method of this invention is applicable to most wide-boiling-point separation processes, expanding the scope of heat pump energy-saving technology. Because there are various combinations of distillation columns and heat pumps, selecting the optimal structure is challenging. The method proposed in this invention can quickly select the optimal initial structure based on different feed conditions, saving a significant amount of energy compared to not using a heat pump while minimizing heat pump power consumption.

[0036] In some implementations, the compression ratio of both the primary compression and the secondary compression is 1-2.

[0037] In some embodiments, the primary compression of the low-temperature material includes: dividing the low-temperature material into material c and material d, performing primary compression on material c, and condensing and separating material d to obtain a low-boiling-point substance.

[0038] In some embodiments, step S31 further includes: exchanging heat between material b and the wide-boiling-point binary mixture, and condensing and separating the heat-exchanged primary compressed material to obtain a low-boiling-point substance.

[0039] In some preferred embodiments, the primary compressed material after heat exchange is subjected to decompression treatment before condensation and separation.

[0040] In some preferred embodiments, the secondary compressed material after the first heat exchange is subjected to decompression treatment before condensation and separation.

[0041] In some preferred embodiments, the temperature of the primary compressed material is at least 10°C higher than the temperature of the wide-boiling-point binary mixture, and the temperature of the primary compressed material is less than 140°C.

[0042] In some preferred embodiments, the vaporization fraction of the wide-boiling-point binary mixture is 0.2-0.5.

[0043] In some preferred embodiments, the temperature of the secondary compressed material is at least 10°C higher than the boiling point of the high-temperature material; and the temperature of the secondary compressed material is less than 140°C.

[0044] In some embodiments, step S32 further includes: before condensing and separating the primary compressed material after the second heat exchange, subjecting the primary compressed material after the second heat exchange to pressure reduction treatment.

[0045] In some embodiments, the secondary compressed material after the third heat exchange is subjected to depressurization treatment before condensation and separation.

[0046] In some preferred embodiments, the temperature of the primary compressed material is at least 10°C higher than the boiling point of the intermediate-temperature material, and the temperature of the primary compressed material is less than 140°C.

[0047] In some preferred embodiments, the vaporization fraction of the intermediate-temperature material is 0.2-0.5.

[0048] In some preferred embodiments, the temperature of the secondary compressed material is at least 10°C higher than the boiling point of the high-temperature material; and the temperature of the secondary compressed material is less than 140°C.

[0049] In some preferred embodiments, the content of the light component in the wide-boiling-point binary mixture is higher than 70%.

[0050] In some embodiments, step S33 further includes: exchanging heat between material b and the wide-boiling-point binary mixture, and condensing and separating the heat-exchanged material b to obtain a low-boiling-point substance.

[0051] In some preferred embodiments, the heat-exchanged material b is subjected to depressurization treatment before condensation and separation.

[0052] In some preferred embodiments, the secondary compressed material after the fourth heat exchange is subjected to decompression treatment before condensation and separation.

[0053] In some preferred embodiments, the temperature of material b is at least 10°C higher than the temperature of the broad boiling point binary mixture, and the temperature of the primary compressed material is less than 140°C.

[0054] In some preferred embodiments, the temperature of the secondary compressed material is at least 10°C higher than the boiling point of the intermediate-temperature material; and the temperature of the secondary compressed material is less than 140°C.

[0055] In some embodiments, the broad boiling point binary mixture is fed using a bubble point feed method.

[0056] In some embodiments, the temperature of the broad boiling point binary mixture is higher than the boiling point of the low-temperature material and lower than the boiling point of the medium-temperature material.

[0057] In some embodiments, the broad boiling point binary mixture includes, but is not limited to, a mixture of benzene and toluene or a mixture of isopropanol and chlorobenzene.

[0058] In this invention, an energy balance is performed based on the actual separation system, and the calculation results are used to determine whether the materials need to be diverted and to determine the proportion of materials to be distributed for greater energy efficiency.

[0059] The method of this invention is mainly used for the separation of binary mixtures with a temperature difference (ΔT) between the top and bottom of the tower greater than 20°C, that is, the temperature difference (ΔT) between the boiling point of the high-temperature material and the boiling point of the low-temperature material is greater than 20°C.

[0060] In this invention, the temperature difference between the top and bottom of the tower refers to the absolute value of the temperature difference between the material temperature at the top and the material temperature at the bottom of the tower, denoted by ΔT. In this invention, the temperature at the bottom of the tower is higher than the temperature at the top.

[0061] This invention provides a method for separating a product of sufficient purity from a binary mixture with a wide boiling point while reducing the consumption of heating steam. The method proposes selecting different two-stage vapor recompression heat pump structures based on varying process operating parameters during the separation process. Figures 1-3 As shown.

[0062] A second aspect of the present invention provides a separation system for a broad-boiling-point binary mixture, the separation system comprising: a separation column A, a primary compressor D, a secondary compressor E, a condenser F, a bottom reboiler G and an optional auxiliary reboiler J, and at least one of a feed preheater B and an intermediate reboiler K; wherein the separation column A includes a raw material inlet, a top material outlet, a bottom material outlet and an optional intermediate material outlet; wherein the distance from the raw material inlet to the top material outlet is less than the distance from the intermediate material outlet to the top material outlet; for separating a broad-boiling-point binary mixture into a low-temperature material, a high-temperature material and an optional medium-temperature material;

[0063] The primary compressor D is connected to the top material outlet of the separation tower A and is used to perform primary compression on the low-temperature material to obtain primary compressed material.

[0064] The secondary compressor E is connected to the primary compressor D and is used to perform secondary compression on the primary compressed material to obtain secondary compressed material.

[0065] The feed preheater B is connected to the raw material inlet of the separation tower A and is used to preheat the wide boiling point binary mixture.

[0066] The reboiler G at the bottom of the tower is connected to the bottom material outlet of the separation tower A and is used to reboil the high-temperature material to obtain a high-boiling-point substance.

[0067] The auxiliary reboiler J is connected to the bottom material outlet of the separation tower A, and is used to assist the bottom reboiler in reboiling treatment, or to reboil the high-temperature material to obtain a high-boiling-point substance.

[0068] The intermediate reboiler K is connected to the intermediate material outlet of the separation tower A and is used to reboil the intermediate material.

[0069] The condenser F is connected to the separation tower A and to at least two of the feed preheater B, the bottom reboiler G, and the intermediate reboiler K, for condensing and separating the material to obtain low-boiling-point substances.

[0070] In some embodiments, the separation system further includes a distributor C, which includes a material inlet, a first material outlet, and a second material outlet. The material inlet of the distributor C is connected to the top material outlet of the separation tower A, the first material outlet of the distributor C is connected to the primary compressor D, and the second material outlet of the distributor C is connected to the condenser F.

[0071] In some embodiments, the bottom reboiler G includes a heating pipeline and a bottom material pipeline. The inlet end of the heating pipeline is connected to the hot end of the secondary compressor E, and the outlet end of the heating pipeline is connected to the condenser F. A first pressure reducing valve H is provided between the outlet end of the heating pipeline and the condenser F. The inlet end of the bottom material pipeline is connected to the bottom material outlet of the separation column A. The outlet end of the bottom material pipeline includes a first high-boiling-point material outlet and a first reflux port, and the first reflux port is connected to the separation column A.

[0072] In some embodiments, the auxiliary reboiler includes a material inlet, a second high-boiling-point material outlet, and a second reflux port. The material inlet is connected to the bottom material outlet of the separation column A, and the second reflux port is connected to the separation column A.

[0073] In some embodiments, the feed preheater B includes a raw material pipeline and a preheating pipeline. The inlet end of the raw material pipeline is connected to the raw material pipeline of the wide boiling point binary mixture, and the outlet end of the raw material pipeline is connected to the raw material inlet of the separation tower A. The inlet end of the preheating pipeline is connected to the hot end of the first-stage compressor D, and the outlet end of the preheating pipeline is connected to the condenser F. A second pressure reducing valve I is provided between the outlet end of the preheating pipeline and the condenser F.

[0074] In some preferred embodiments, the vaporization fraction of the feed preheater B is 0.2-0.5.

[0075] In some embodiments, the intermediate reboiler K includes an intermediate material pipeline and a heat exchange pipeline, the inlet end of the intermediate material pipeline being connected to the intermediate material outlet of the separation tower A, and the outlet end of the intermediate material pipeline being connected to the separation tower A.

[0076] In some preferred embodiments, the vaporization fraction of the intermediate reboiler K is 0.2-0.5.

[0077] When the temperature difference between the top and bottom of the tower ΔT > 20℃ and the bottom temperature T1 < 130℃, in some implementations, such as... Figure 1 As shown, the separation system includes a separation column, a primary compressor, a secondary compressor, a feed preheater, a bottom reboiler, an optional auxiliary reboiler, a condenser, and an optional distributor. In other embodiments, such asFigure 2 As shown, the separation system includes a separation tower, a primary compressor, a secondary compressor, an intermediate reboiler, a bottom reboiler, an optional auxiliary reboiler, a condenser, and an optional distributor; wherein, the inlet end of the heat exchange pipeline of the intermediate reboiler K is connected to the hot end of the primary compressor D, the outlet end of the heat exchange pipeline is connected to the condenser F, and a third pressure reducing valve L is provided between the outlet end of the heat exchange pipeline and the condenser F.

[0078] When the temperature difference between the top and bottom of the column ΔT > 20℃ and the bottom temperature T1 > 130℃, in some implementations, such as... Figure 3 As shown, the separation system includes: a separation tower, a primary compressor, a secondary compressor, a feed preheater, an intermediate reboiler, a bottom reboiler, a condenser, and an optional distributor; wherein, the inlet end of the heat exchange pipeline of the intermediate reboiler K is connected to the hot end of the secondary compressor E, the outlet end of the heat exchange pipeline is connected to the condenser F, and a fourth pressure reducing valve M is provided between the outlet end of the heat exchange pipeline and the condenser F.

[0079] In some preferred embodiments, the compression ratio of the primary compressor is 1-2; the compression ratio of the secondary compressor is 1-2.

[0080] When the temperature difference between the top and bottom of the column ΔT > 20℃ and the bottom temperature T1 < 130℃, the following method is adopted: Figure 1 and Figure 2 The diagram shown is a structural schematic.

[0081] According to a particularly preferred embodiment of the present invention, such as Figure 1As shown, the separation system provided by the present invention includes: a separation tower A, a feed preheater B, an optional distributor C, a primary heat pump compressor D, a secondary heat pump compressor E, a condenser F, a bottom reboiler G, a first pressure reducing valve H, a second pressure reducing valve I, and an optional auxiliary reboiler J. The binary wide-boiling-point mixture 11 enters the feed preheater B, and after preheating, it enters the separation tower A. At the top of the separation tower A, a low-temperature steam stream 12 is generated. After passing through the splitter C, the stream 12 is divided into two streams, namely stream c1 and stream d1. Stream d1 directly enters the condenser F for cooling. Stream c1 is compressed into high-pressure, high-temperature steam after passing through the first-stage heat pump compressor D, and is divided into two streams, namely stream a1 and stream b1. Stream b1 exchanges heat with the feed preheater B, providing it with heat. After heat exchange, the stream b1' enters the condenser F for further cooling through the second pressure reducing valve I. Stream a1 enters the second-stage heat pump compressor E, which further compresses and increases its pressure and temperature. The further compressed steam 12 exchanges heat with the reboiler G at the bottom of the tower, providing it with heat. After heat exchange, the stream 13 enters the condenser F for further cooling after passing through the first pressure reducing valve H. After cooling, stream 14 is divided into two streams, e1 and f1. Stream e1 is returned to separation tower A, and stream f1 is the first product, i.e., the low-boiling-point material. The high-temperature steam stream 15 generated at the bottom of separation tower A is divided into two streams, g1 and h1. Stream g1 enters the bottom reboiler G, and stream h1 enters the auxiliary reboiler J. The outlet stream 16 of the bottom reboiler G and the outlet stream 17 of the auxiliary reboiler J are the second product, i.e., the high-boiling-point material.

[0082] Taking a mixture of benzene and toluene as an example, the first product is benzene, and the second product is toluene, with benzene comprising 60 wt%. The purity requirement for the first product is 99.95 wt%. The column has 35 trays, with feed starting from the 19th tray. The bottom temperature of the benzene-toluene separation column is 116.7℃, which is less than 130℃, and the temperature difference between the top and bottom of the column is 33.8℃, which is greater than 20℃.

[0083] Adopting such Figure 1 The structural diagram shown is compared to... Figure 4 The separation system shown, which does not use a heat pump, can save 51.49% of energy consumption. For example... Figure 4 The separation system shown does not use a heat pump, where A is the separation tower, X is the top reboiler, Y is the bottom reboiler, 41 is a binary wide-boiling-point mixture, 42 is a low-boiling-point material, and 43 is a high-boiling-point material.

[0084] According to a particularly preferred embodiment of the present invention, such as Figure 2As shown, the separation system provided by the present invention includes: a separation tower A, an optional distributor C, a primary heat pump compressor D, a secondary heat pump compressor E, a condenser F, a bottom reboiler G, an optional auxiliary reboiler J, an intermediate reboiler K, a first pressure reducing valve H, and a third pressure reducing valve L. The binary wide-boiling-point mixture 21 directly enters the separation tower A, generating a low-temperature steam stream 22 at the top of the tower. Stream 22 is split into two streams, c2 and d2, after passing through the splitter C. Stream d2 directly enters the condenser F for cooling. Stream c2 is compressed into high-pressure, high-temperature steam after passing through the primary heat pump compressor D, and then splits into two streams, a2 and b2. Stream b2 exchanges heat with stream 28 through the intermediate reboiler K, providing heat to stream 28. After heat exchange, stream 29 returns to the separation tower A. After heat exchange, stream b2 enters the condenser F for further cooling through the third pressure reducing valve L. Stream a2 enters the secondary heat pump compressor E for further compression, increasing its pressure and temperature. The further compressed steam 22 exchanges heat with the reboiler G at the bottom of the tower, providing heat to it. After heat exchange, stream 23 enters the condenser F for further cooling after passing through the first pressure reducing valve H. After cooling, stream 24 is divided into two streams, e2 and f2. Stream e2 is returned to separation tower A, and stream f2 is the first product, i.e., the low-boiling-point material is obtained. The high-temperature steam stream 25 generated at the bottom of separation tower A is divided into two streams, g2 and h2. Stream g2 enters the bottom reboiler G, and stream h2 enters the auxiliary reboiler J. The outlet stream 26 of the bottom reboiler G and the outlet stream 27 of the auxiliary reboiler J are the second product, i.e., the high-boiling-point material is obtained.

[0085] When the light component content of a broad-boiling-point binary mixture is higher than 70%, or when high separation accuracy is required at the top of the column, and the temperature difference between the top and bottom of the column ΔT > 20℃ and the bottom temperature T1 < 130℃, it is preferable to use the first-stage compressed material after the first-stage compression for heat exchange in the intermediate reboiler K. Figure 2 The flowchart shown is shown.

[0086] Taking a mixture of benzene and toluene as an example, the first product is benzene, and the second product is toluene. Benzene comprises 80 wt%, and the purity requirement for the first product is 99.99 wt%. The column has 40 trays, with feed starting from the 20th tray. The bottom temperature of the benzene-toluene separation column is 116.7℃, which is less than 130℃, and the temperature difference between the top and bottom is 33.8℃, which is greater than 20℃. The benzene composition is 80 wt%, the light component content is greater than 70%, and the product purity requirement is 99.99 wt%, indicating a very high product purity requirement.

[0087] Adopting such Figure 2 The structural diagram shown is compared to... Figure 4 The separation system shown can save 55.69% of energy consumption without a heat pump.

[0088] When the temperature difference between the top and bottom of the column ΔT > 20℃ and the bottom temperature T1 > 130℃, the following method is adopted: Figure 3 The diagram shown is a structural schematic.

[0089] According to a particularly preferred embodiment of the present invention, such as Figure 3 As shown, the separation system provided by the present invention includes: a separation tower A, a feed preheater B, an optional distributor C, a primary heat pump compressor D, a secondary heat pump compressor E, a condenser F, a bottom reboiler G, an intermediate reboiler K, a second pressure reducing valve I, and a fourth pressure reducing valve M. The binary wide-boiling-point mixture 31 enters the feed preheater B, and after preheating, it enters the separation tower A. At the top of the separation tower A, a low-temperature steam stream 32 is generated. After passing through the splitter C, the stream 32 is divided into two streams, stream c3 and stream d3. Stream d3 directly enters the condenser F for cooling. Stream c3 is compressed into high-pressure, high-temperature steam after passing through the first-stage heat pump compressor D, and is divided into two streams, stream a3 and stream b3. Stream b3 exchanges heat with the feed preheater B, providing it with heat. After heat exchange, stream b3' enters the condenser F for further cooling through the second pressure reducing valve I. Stream a3 enters the second-stage heat pump compressor E, which further compresses it to increase its pressure and temperature. The further compressed steam stream 32 exchanges heat with the intermediate reboiler K, providing it with heat to heat stream 38. The heated stream 39 returns to the separation tower A. Stream 33, after heat exchange, enters the condenser F for further cooling after passing through the fourth pressure reducing valve M. After cooling, the stream 34 is divided into two streams, namely stream e3 and stream f3. Stream e3 flows back into separation tower A, and stream f3 is the first product, that is, the low-boiling-point material is obtained. The high-temperature steam stream 35 generated at the bottom of separation tower A enters the bottom reboiler G. The outlet stream 36 of the bottom reboiler G is the second product, that is, the high-boiling-point material is obtained.

[0090] Taking a mixture of isopropanol and chlorobenzene as an example, the first product is isopropanol, and the second product is chlorobenzene. The isopropanol content is 40 wt%, and the purity requirement for the first product is 99.9 wt%. The column has 42 trays, with feed starting from the 35th tray. The bottom temperature of the isopropanol-chlorobenzene separation column is 142.3℃, which is greater than 130℃, and the temperature difference between the top and bottom of the column is 58.2℃, which is greater than 20℃.

[0091] Adopting such Figure 3 The structural diagram shown is compared to... Figure 4 The separation system shown, which does not use a heat pump, can save 44.57% of energy consumption.

[0092] The present invention will be described in detail below through embodiments, but the scope of protection of the present invention is not limited to the following description.

[0093] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents, instruments, and equipment used without a specified manufacturer are all commercially available products.

[0094] Example 1

[0095] The feed for a wide-boiling-point binary mixture is a mixture of benzene and toluene. The first product is benzene, and the second product is toluene. Benzene comprises 60 wt%, and the purity requirement for the first product is 99.95 wt%. The separation process of the benzene and toluene mixture was simulated using ASPEN PLUS simulation software. A 35-plate column was obtained. Feeding from the 19th plate met the purity requirement for the first product. The bottom temperature of the separation column used for separating the benzene and toluene mixture was 116.7℃, less than 130℃, and the temperature difference between the top and bottom of the column was 33.8℃, greater than 20℃. Figure 1 The flowchart shown is as follows: Figure 1 As shown, a mixture of benzene and toluene enters separation tower A, where a low-temperature first product vapor stream 12 is generated at the top. Stream 12 is directly compressed into high-pressure, high-temperature steam (after passing through ASPEN) after passing through a primary compressor D. According to PLUS simulation calculations, the heat provided by the steam at the top of the column cannot completely provide heat for the separation in column A. Therefore, stream 12 no longer passes through the distributor C to send a portion of the steam directly into condenser F (i.e., distributor C is not needed). The compression ratio of the first-stage compressor D is 1.75, and the power is 262.8kW. The high-temperature and high-pressure steam after compression is divided into stream a1 and stream b1. Stream b1 exchanges heat with the feed preheater B. The vaporization rate of the feed preheater B is set to 0.3, and the heat exchange is 611.2kW. The heat exchanged stream passes through the pressure reducing valve I and enters condenser F for further cooling. Stream a1 enters the second-stage compressor E for further compression to increase its pressure and temperature. The compression ratio of the second-stage compressor E is 1.6, and the power is 187.9kW. The further compressed stream 12 exchanges heat with the reboiler G at the bottom of the column, and the heat exchange is 2579.4kW. The heat exchanged stream passes through the pressure reducing valve H and enters condenser F for further cooling. According to the simulation requirements, an auxiliary reboiler J is added to provide additional heat, with a heat capacity of 253.6kW. After cooling, stream 14 is divided into stream e1 and stream f1. Stream e1 is returned to separation tower A, and stream f1 is the first product. Stream 16 is the outlet stream of reboiler G at the bottom of the tower, and stream 17 is the outlet stream of auxiliary reboiler J.

[0096] Table 1. Feed and product parameters for the mixture of benzene and toluene.

[0097] Component Feed / product Benzene feed (wt%) 60 Feed flow (kg / h) 20000 Benzene product purity (wt%) 99.95 Benzene product (kg / h) 12002.5

[0098] Table 2 shows the calculation results of the heat pump structure combining the feed preheater and the bottom reboiler.

[0099]

[0100] As can be seen from the data in Table 2, the total energy consumption using the method of this invention is 1605.7 kW, without the need for a heat pump separation system (such as...). Figure 4 The total energy consumption (as shown) is 3310kW. As can be seen from the above, compared with the total energy consumption without using a heat pump, the method of the present invention can save 51.49% of energy consumption.

[0101] Example 2

[0102] The feed for the wide-boiling-point binary mixture is a mixture of benzene and toluene. The first product is benzene, and the second product is toluene. Benzene accounts for 80 wt%, greater than 70 wt%. The purity requirement for the first product is 99.99 wt%, which is high. The separation process of the benzene and toluene mixture was simulated using ASPEN PLUS simulation software. A 40-plate column was obtained. Feeding from the 20th plate met the purity requirement for the first product. The bottom temperature of the separation column used for the benzene and toluene mixture was 116.7℃, less than 130℃, and the temperature difference between the top and bottom of the column was 33.9℃, greater than 20℃. Figure 2 The flowchart shown is as follows: Figure 2 As shown, a mixture of benzene and toluene enters separation tower A, where a low-temperature first product vapor stream 22 is generated at the top. Stream 22 is directly compressed into high-pressure, high-temperature steam (after passing through ASPEN) after passing through a primary compressor D. According to PLUS simulation calculations, the heat provided by the steam at the top of the column cannot completely provide heat for the separation in column A. Therefore, stream 22 no longer passes through the distributor C to send a portion of the steam directly into condenser F (i.e., distributor C is not needed). The compression ratio of the first-stage compressor D is 1.97, and the power is 385.3kW. The high-temperature and high-pressure steam after compression is divided into stream a2 and stream b2. Stream b2 exchanges heat with the intermediate reboiler B. The vaporization rate of the intermediate reboiler B is set to 0.5, and the heat exchange is 1454.7kW. The heat exchanged stream passes through the pressure reducing valve I and enters condenser F for further cooling. Stream a2 enters the second-stage compressor E for further compression to increase its pressure and temperature. The compression ratio of the second-stage compressor E is 1.43, and the power is 133.9kW. The further compressed stream 22 exchanges heat with the bottom reboiler G, and the heat exchange is 2388.9kW. The heat exchanged stream passes through the pressure reducing valve H and enters condenser F for further cooling. According to the simulation requirements, an auxiliary reboiler J is added to provide additional heat, with a heat capacity of 281.1kW. After cooling, stream 24 is divided into stream e2 and stream f2. Stream e2 is returned to separation tower A, and stream f2 is the first product. Stream 26, the outlet stream of reboiler G at the bottom of the tower, and stream 27, the outlet stream of auxiliary reboiler J, are the second products.

[0103] Table 3. Feed and product parameters for the mixture of benzene and toluene.

[0104] Component Feed / product Benzene feed (wt%) 80 Feed flow (kg / h) 20000 Benzene product purity (wt%) 99.99 Benzene product (kg / h) 15999

[0105] Table 4 shows the calculation results of the heat pump structure combining the intermediate reboiler and the bottom reboiler.

[0106]

[0107]

[0108] As can be seen from the data in Table 4, the total energy consumption using the method of this invention is 1838.7 kW, without the need for a heat pump separation system (such as...). Figure 4 The total energy consumption (as shown) is 4150.0 kW. As can be seen from the above, compared with the total energy consumption without using a heat pump, the method of the present invention can save 55.69% of energy consumption.

[0109] Example 3

[0110] The feed for the wide-boiling-point binary mixture is a mixture of isopropanol and chlorobenzene. The first product is isopropanol, and the second product is chlorobenzene. Isopropanol comprises 40 wt%, and the purity requirement for the first product is 99.9 wt%. The separation process of the isopropanol and chlorobenzene mixture was simulated using ASPEN PLUS simulation software. A tray number of 42 was obtained. Feeding from the 35th tray met the purity requirement for the first product. The bottom temperature of the isopropanol and chlorobenzene separation column was 142.3℃, greater than 130℃, and the temperature difference between the top and bottom was 58.2℃, greater than 20℃. Figure 3 The flowchart shown is as follows: Figure 3As shown, the mixture of isopropanol and chlorobenzene enters separation tower A, where a low-temperature first product vapor stream 32 is generated at the top. Stream 32 enters splitter C, where it is divided into stream c3 and stream d3. Stream c3 is then compressed into high-pressure, high-temperature steam (after passing through ASPEN) by a primary compressor D. According to PLUS simulation calculations, the heat provided by the steam at the top of the column is sufficient to provide heat for the separation in column A, with a surplus, requiring the installation of separator C). The compression ratio of the first-stage compressor D is 1.45, and its power is 95.0 kW. The high-temperature and high-pressure steam after compression is divided into stream a3 and stream b3. Stream b3 exchanges heat with the feed preheater B, whose vaporization rate is set to 0.3, and the heat exchange is 583.9 kW. The heat exchanged stream passes through pressure reducing valve I and enters condenser F for further cooling. Stream a3 enters the second-stage compressor E for further compression to increase its pressure and temperature. The compression ratio of the second-stage compressor E is 1.2, and its power is 36.3 kW. The further compressed steam 32 exchanges heat with the intermediate reboiler K, with a heat exchange of 1722.2 kW. The heat exchanged stream passes through pressure reducing valve M and enters condenser F for further cooling. The additional heat required by the bottom reboiler G is 1990.8 kW. After cooling, stream 34 is divided into stream e3 and stream f3. Stream e3 is refluxed into separation tower A, stream f3 is the first product, and stream 36, the outlet stream of reboiler G at the bottom of the tower, is the second product.

[0111] Table 5. Feed and product parameters for the mixture of isopropanol and chlorobenzene.

[0112] Component Feed / product Isopropanol feed (wt%) 40 Feed flow (kg / h) 15000 Isopropanol product purity (wt%) 99.9 Isopropanol product (kg / h) 5994

[0113] Table 6 shows the calculation results of the heat pump structure combining the feed preheater and intermediate reboiler.

[0114]

[0115] As can be seen from the data in Table 6, the total energy consumption using the method of this invention is 2384.7 kW, without the need for a heat pump separation system (such as...). Figure 4 The total energy consumption (as shown) is 4301.9kW. As can be seen from the above, compared with the total energy consumption without using a heat pump, the method of the present invention can save 44.57% of energy consumption.

[0116] As can be seen from the results of Examples 1-3 above, the two-stage vapor recompression heat pump distillation method proposed in this invention can achieve excellent energy-saving benefits.

[0117] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for separating a broad-boiling-point binary mixture, characterized in that, The separation method includes: S1. Perform a first separation on the binary mixture with a wide boiling point to obtain a low-temperature material, a high-temperature material, and an optional medium-temperature material; wherein the temperature difference ΔT between the boiling point of the high-temperature material and the boiling point of the low-temperature material is greater than 20℃. S2. The low-temperature material is subjected to primary compression to obtain primary compressed material; the primary compressed material is divided into material a and material b, and material a is subjected to secondary compression to obtain secondary compressed material; S3. If the boiling point T1 of the high-temperature material is less than 130°C, then proceed with step S31 or S32. If the boiling point T1 of the high-temperature material is greater than 130°C, then proceed with step S33. S31. The secondary compressed material is subjected to a first heat exchange with the high-temperature material, and the high-temperature material after the first heat exchange is subjected to reboiling treatment to obtain a first high-boiling-point substance; the secondary compressed material after the first heat exchange is subjected to condensation separation to obtain a first low-boiling-point substance. S32. The material b is subjected to a second heat exchange with the medium-temperature material, the medium-temperature material after the second heat exchange is returned, and the primary compressed material after the second heat exchange is condensed and separated to obtain a second low-boiling-point substance; the secondary compressed material is subjected to a third heat exchange with the high-temperature material, and the high-temperature material after the third heat exchange is reboiled to obtain a second high-boiling-point substance; the secondary compressed material after the third heat exchange is condensed and separated to obtain a second low-boiling-point substance; S33. The secondary compressed material and the medium-temperature material are subjected to a fourth heat exchange. The medium-temperature material after the fourth heat exchange is returned. The secondary compressed material after the fourth heat exchange is condensed and separated to obtain a third low-boiling-point substance. The high-temperature material is reboiled to obtain a third high-boiling-point substance.

2. The separation method according to claim 1, wherein, The compression ratios of both the primary and secondary compression stages are 1-2.

3. The separation method according to claim 1 or 2, wherein, The process of performing primary compression on the low-temperature material includes: dividing the low-temperature material into material c and material d, performing primary compression on material c, and condensing and separating material d to obtain a low-boiling-point substance.

4. The separation method according to claim 1 or 2, wherein, Step S32 further includes: before condensing and separating the primary compressed material after the second heat exchange, subjecting the primary compressed material after the second heat exchange to pressure reduction treatment; and / or, Before condensing and separating the secondary compressed material after the third heat exchange, the secondary compressed material after the third heat exchange is first subjected to pressure reduction treatment.

5. The separation method according to claim 4, wherein, The temperature of the primary compressed material is at least 10°C higher than the boiling point of the intermediate-temperature material, and the temperature of the primary compressed material is less than 140°C. And / or, the vaporization fraction of the intermediate-temperature material is 0.2-0.5; And / or, the temperature of the secondary compressed material is at least 10°C higher than the boiling point of the high-temperature material; and the temperature of the secondary compressed material is less than 140°C; And / or, the content of the light component in the wide boiling point binary mixture is higher than 70%.

6. The separation method according to claim 1 or 2, wherein, Step S31 further includes: exchanging heat between material b and the wide-boiling-point binary mixture, and condensing and separating the primary compressed material after heat exchange to obtain a low-boiling-point substance.

7. The separation method according to claim 6, wherein, Before condensing and separating the primary compressed material after heat exchange, the primary compressed material after heat exchange is first subjected to pressure reduction treatment. And / or, before condensing and separating the secondary compressed material after the first heat exchange, the secondary compressed material after the first heat exchange is subjected to pressure reduction treatment; And / or, the temperature of the primary compressed material is at least 10°C higher than the temperature of the wide-boiling-point binary mixture, and the temperature of the primary compressed material is less than 140°C; And / or, the vaporization fraction of the wide-boiling-point binary mixture is 0.2-0.5; And / or, the temperature of the secondary compressed material is at least 10°C higher than the boiling point of the high-temperature material; and the temperature of the secondary compressed material is less than 140°C.

8. The separation method according to claim 1 or 2, wherein, Step S33 further includes: exchanging heat between material b and the wide-boiling-point binary mixture, and condensing and separating the heat-exchanged material b to obtain a low-boiling-point substance.

9. The separation method according to claim 8, wherein, Before condensing and separating the heat-exchanged material b, the heat-exchanged material b is first subjected to depressurization treatment; And / or, before condensing and separating the secondary compressed material after the fourth heat exchange, the secondary compressed material after the fourth heat exchange is subjected to pressure reduction treatment; And / or, the temperature of material b is at least 10°C higher than the temperature of the wide-boiling-point binary mixture, and the temperature of the primary compressed material is less than 140°C; And / or, the temperature of the secondary compressed material is at least 10°C higher than the boiling point of the intermediate-temperature material; and the temperature of the secondary compressed material is less than 140°C.

10. The separation method according to claim 1 or 2, wherein, The feeding method for the wide boiling point binary mixture is bubble point feeding.

11. The separation method according to claim 1 or 2, wherein, The temperature of the broad-boiling-point binary mixture is higher than the boiling point of the low-temperature material and lower than the boiling point of the medium-temperature material; and / or, The wide-boiling-point binary mixture is a mixture of benzene and toluene or a mixture of isopropanol and chlorobenzene.

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