System for separating n-butane and iso-butane through differential pressure thermal coupling rectification

Abstract

The utility model provides a system for separating n-butane and iso-butane through differential pressure thermal coupling rectification, which comprises an iso-butane separation tower A, an iso-butane separation tower B, a tower A reflux tank, a tower B reflux tank, a tower A condenser, a cooler or heater, a tower A reboiler, a tower B reboiler, a tower A reflux pump and a tower B reflux pump, the tower A condenser, the tower A reflux tank and the tower A reflux pump are sequentially arranged on a tower top material pipeline of the isobutane separation tower A, the tower A reboiler is arranged at the tower bottom of the isobutane separation tower A, and the tower B reboiler is arranged at the tower bottom of the isobutane separation tower B. According to the system, an isobutane separation tower A serves as a low-temperature low-pressure tower, an isobutane separation tower B serves as a high-temperature high-pressure tower, condensation heat at the tower top of the isobutane separation tower B serves as a heat source of a reboiler at the tower bottom of the isobutane separation tower A, and the isobutane separation tower A and the isobutane separation tower B are thermally coupled; the steam consumption of the isobutane separation tower A is reduced, the refrigerant consumption at the tower top of the isobutane separation tower B is reduced, and the energy consumption is reduced.

Description

Technical Field

[0001] The utility model belongs to the field of chemical industry, in particular to a system for separating normal butane and isobutane by differential pressure thermal coupling distillation. Background Art

[0002] C4 hydrocarbons are a general term for monoolefins (n-butene and isobutylene), diolefins (butadiene), and alkanes (n-butane and isobutane). C4 hydrocarbons are primarily derived from catalytic cracking and steam cracking (C4 hydrocarbons are a by-product of ethylene cracking). Currently available methods for separating C4 hydrocarbons involve extractive distillation to obtain butadiene. The remaining C4 hydrocarbons are then reacted with methanol to produce MTBE, and the remaining C4 hydrocarbons are then extracted and distilled again to obtain n-butene. The overhead product of the extractive distillation column is an alkane mixture containing isobutane and n-butane. This mixture is typically burned as liquefied gas, and its value is not fully realized. For example, n-butane can be used to produce maleic anhydride, and isobutane can be dehydrogenated to produce isobutene, which can also be used to produce propellants or alkylated gasoline. Therefore, the separation of n-butane and isobutane also has promising industrial application prospects. Existing processes generally use conventional distillation to separate n-butane and isobutane, but the use of conventional distillation technology for separation suffers from high energy consumption, investment, and operating costs. Utility Model Content

[0003] In view of this, the utility model aims to propose a system for separating n-butane and isobutane by differential pressure thermal coupling distillation, so as to solve the problems of high energy consumption, high investment and operating costs of conventional distillation technology in the prior art.

[0004] In order to achieve the above-mentioned purpose, the technical solution of the utility model is achieved as follows:

[0005] A system for separating normal butane and isobutane by differential pressure thermal coupling distillation, comprising an isobutane separation tower A, an isobutane separation tower B, a reflux tank of tower A, a reflux tank of tower B, a condenser of tower A, a cooler or heater, a reboiler of tower A, a reboiler of tower B, a reflux pump of tower A, and a reflux pump of tower B, wherein the condenser of tower A, the reflux tank of tower A, and the reflux pump of tower A are sequentially arranged on a material pipeline at the top of tower A of the isobutane separation tower, the reboiler of tower A is arranged at the bottom of tower A of the isobutane separation tower, and the reboiler of tower B is arranged at the bottom of tower B of the isobutane separation tower;

[0006] When the heat of the top of the isobutane separation tower B is greater than or equal to the heat required by the bottom of the isobutane separation tower A, the top outlet of the isobutane separation tower B is connected to the inlet of the reboiler of the tower A, and the outlet of the reboiler of the tower A is sequentially provided with a cooler, a reflux tank of the tower B, and a reflux pump of the tower B. The outlet of the reflux pump of the tower B is refluxed to the top of the isobutane separation tower B and isobutane is produced; or one side of the top of the isobutane separation tower B is connected to the inlet of the reboiler of the tower A, and the other side of the top of the isobutane separation tower B is sequentially provided with a cooler, a reflux tank of the tower B, and a reflux pump of the tower B. The outlet of the reflux pump of the tower B is refluxed to the top of the isobutane separation tower B and isobutane is produced, and the outlet of the reboiler of the tower A is connected to the inlet of the reflux tank of the tower B;

[0007] When the heat at the top of the isobutane separation tower B is less than the heat required at the bottom of the isobutane separation tower A, the top of the isobutane separation tower B is connected to the inlet of the reboiler of Tower A, and the outlet of the reboiler of Tower A is connected to the reflux tank of Tower B and the reflux pump of Tower B in sequence. The outlet of the reflux pump of Tower B refluxes to the top of the isobutane separation tower B and isobutane is produced. The heater is set at the bottom of the isobutane separation tower A.

[0008] The isobutane separation tower A is a low-temperature, low-pressure tower, and the isobutane separation tower B is a high-temperature, high-pressure tower. Differential pressure heat-coupled distillation is adopted, and the top gas phase of the isobutane separation tower B is used as the heat source of the reboiler of the tower A, which saves most of the steam in the tower bottom and reduces energy consumption. A cooler is set on the top of the isobutane separation tower B instead of a condenser, which can further reduce energy consumption.

[0009] Furthermore, the cooler can also be replaced by an air cooler + aftercooler.

[0010] Furthermore, a mixed C4 feed pipeline is provided in the middle of the isobutane separation tower A and the isobutane separation tower B.

[0011] Furthermore, the top outlet of the isobutane separation tower A is connected to the inlet of the condenser of Tower A through a first pipeline, the outlet of the condenser of Tower A is connected to the inlet of the reflux tank of Tower A through a second pipeline, the outlet of the reflux tank of Tower A is connected to the inlet of the reflux pump of Tower A through a third pipeline, and the outlet of the reflux pump of Tower A is connected to the top inlet of the isobutane separation tower A through a fourth pipeline.

[0012] Furthermore, a fifth pipeline is provided on the fourth pipeline, the fifth pipeline is connected to the seventh pipeline, and the fifth pipeline and the seventh pipeline are production pipelines for isobutane.

[0013] Furthermore, the outlet of the B tower reflux tank is connected to the inlet of the B tower reflux pump through the eighth pipeline, the outlet of the B tower reflux pump is connected to the sixth pipeline and the seventh pipeline through the ninth pipeline, and the sixth pipeline is connected to the top inlet of the isobutane separation tower B tower.

[0014] Furthermore, a normal butane extraction pipeline is provided at the bottom of the isobutane separation tower A and the isobutane separation tower B.

[0015] Furthermore, when the heat required at the top of the isobutane separation tower B is greater than or equal to the heat required at the bottom of the isobutane separation tower A, the top outlet of the isobutane separation tower B is connected to the inlet of the reboiler of tower A through the 30th pipeline, the outlet of the reboiler of tower A is connected to the inlet of the cooler through the 31st pipeline, and the outlet of the cooler is connected to the inlet of the reflux tank of tower B through the 32nd pipeline.

[0016] Furthermore, when the heat required at the top of the isobutane separation tower B is greater than or equal to the heat required at the bottom of the isobutane separation tower A, a tenth pipeline is provided at the top of the isobutane separation tower B, and the end of the tenth pipeline is branched into an eleventh pipeline and a twelfth pipeline. The eleventh pipeline is connected to the inlet of the reboiler of Tower A, the twelfth pipeline is connected to the inlet of the cooler, the outlet of the cooler is connected to the inlet of the reflux tank of Tower B through the thirteenth pipeline, and the outlet of the reboiler of Tower A is connected to the inlet of the reflux tank of Tower B through the fourteenth pipeline.

[0017] Furthermore, when the heat required at the top of the isobutane separation tower B is less than the heat required at the bottom of the isobutane separation tower A, the top of the isobutane separation tower B is connected to the inlet of the reboiler of tower A through the fifteenth pipeline, and the outlet of the reboiler of tower A is connected to the inlet of the reflux tank of tower B through the sixteenth pipeline; a heater is provided at the bottom of the isobutane separation tower A for heat supplement.

[0018] Furthermore, the feed ratio of the isobutane separation tower A and the isobutane separation tower B can be adjusted to suit different device conditions.

[0019] Compared with the prior art, the system for separating n-butane and isobutane by differential pressure thermal coupling distillation described in the present invention has the following advantages:

[0020] (1) The n-butane and isobutane separation system described in the present invention adopts differential pressure heat coupling distillation technology, with the isobutane separation tower A serving as a low-temperature, low-pressure tower, and the isobutane separation tower B serving as a high-temperature, high-pressure tower. The condensation heat at the top of the isobutane separation tower B serves as the heat source for the reboiler at the bottom of the isobutane separation tower A. The isobutane separation tower A and the isobutane separation tower B are thermally coupled, thereby reducing the steam consumption of the isobutane separation tower A and the refrigerant consumption at the top of the isobutane separation tower B, thereby reducing energy consumption.

[0021] (2) When there is excess heat at the top of the isobutane separation tower B, a cooler is installed at the top of the isobutane separation tower B. Compared with the ordinary distillation condenser, the cooler is smaller in size and can be replaced by an air cooler + aftercooler. It has higher adaptability to changes in the components of the raw materials and can reduce equipment investment costs, equipment floor space, and energy consumption.

[0022] (3) The utility model sets a heater at the bottom of the isobutane separation tower A, so that when the heat at the top of the isobutane separation tower B is insufficient, the heater can serve as a small part of the heat source of the isobutane separation tower A to provide heat.

[0023] (4) The cooler described in the utility model and the reboiler of tower A share a high-efficiency heat exchanger to further recover heat, minimize the heat transfer temperature difference, and reduce energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0025] Figure 1 This is a schematic diagram of a system for separating n-butane and isobutane by differential pressure thermal coupling distillation as described in Example 1 of the present utility model;

[0026] Figure 2 This is a schematic diagram of a system for separating n-butane and isobutane by differential pressure thermally coupled distillation as described in Example 2 of the present utility model;

[0027] Figure 3 This is a schematic diagram of a system for separating n-butane and isobutane by differential pressure thermal coupling distillation as described in Example 3 of the present utility model.

[0028] Description of reference numerals:

[0029] 1. First pipeline; 2. Second pipeline; 3. Third pipeline; 4. Fourth pipeline; 5. Fifth pipeline; 6. Sixth pipeline; 7. Seventh pipeline; 8. Eighth pipeline; 9. Ninth pipeline; 10. Tenth pipeline; 11. Eleventh pipeline; 12. Twelfth pipeline; 13. Thirteenth pipeline; 14. Fourteenth pipeline; 15. Fifteenth pipeline; 16. Sixteenth pipeline; 17. Isobutane separation tower A; 18 , isobutane separation tower B; 19. Reflux tank of Tower A; 20. Reflux tank of Tower B; 21. Condenser of Tower A; 22. Cooler; 23. Heater; 24. Reboiler of Tower A; 25. Reboiler of Tower B; 26. Reflux pump of Tower A; 27. Reflux pump of Tower B; 28. Mixed C4 feed pipeline; 29. ​​n-butane production pipeline; 30. Pipeline 30; 31. Pipeline 31; 32. Pipeline 32. DETAILED DESCRIPTION

[0030] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features therein can be combined with each other.

[0031] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0032] In the description of this utility model, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections; direct connections, indirect connections through an intermediate medium, and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on specific circumstances.

[0033] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0034] Example 1

[0035] like Figure 1 As shown, a system for separating normal butane and isobutane by differential pressure heat-coupled distillation is shown. When the heat at the top of the isobutane separation tower B tower 18 is greater than or equal to the heat required at the bottom of the isobutane separation tower A tower 17, the system comprises an isobutane separation tower A tower 17, an isobutane separation tower B tower 18, a tower A reflux tank 19, a tower B reflux tank 20, a tower A condenser 21, a cooler 22, a tower A reboiler 24, a tower B reboiler 25, a tower A reflux pump 26, and a tower B reflux pump 27. The tower A condenser 21, the tower A reflux tank 19, and the tower A reflux pump 26 are sequentially arranged on the material pipeline at the top of the isobutane separation tower A tower 17, the tower A reboiler 24 is arranged at the bottom of the isobutane separation tower A tower 17, and the tower B reboiler 25 is arranged at the bottom of the isobutane separation tower B tower 18;

[0036] The top outlet of the isobutane separation tower B tower 18 is connected to the inlet of the reboiler 24 of tower A. The outlet of the reboiler 24 of tower A is sequentially provided with a cooler 22, a reflux tank 20 of tower B, and a reflux pump 27 of tower B. The outlet of the reflux pump 27 of tower B refluxes to the top of the isobutane separation tower B tower 18 and produces isobutane.

[0037] A mixed C4 feed pipeline 28 is provided in the middle of the isobutane separation tower A 17 and the isobutane separation tower B 18 .

[0038] The top outlet of the isobutane separation tower A tower 17 is connected to the inlet of the A tower condenser 21 through a first pipeline 1, the outlet of the A tower condenser 21 is connected to the inlet of the A tower reflux tank 19 through a second pipeline 2, the outlet of the A tower reflux tank 19 is connected to the inlet of the A tower reflux pump 26 through a third pipeline 3, and the outlet of the A tower reflux pump 26 is connected to the top inlet of the isobutane separation tower A tower 17 through a fourth pipeline 4.

[0039] The fourth pipeline 4 is provided with a fifth pipeline 5 , which is connected to the seventh pipeline 7 . The fifth pipeline 5 and the seventh pipeline 7 are isobutane production pipelines.

[0040] The outlet of the B tower reflux tank 20 is connected to the inlet of the B tower reflux pump 27 through the eighth pipeline 8, the outlet of the B tower reflux pump 27 is connected to the sixth pipeline 6 and the seventh pipeline 7 through the ninth pipeline 9, and the sixth pipeline 6 is connected to the top inlet of the isobutane separation tower B tower 18.

[0041] A normal butane extraction pipeline 29 is provided at the bottom of the isobutane separation tower A 17 and the isobutane separation tower B 18 .

[0042] The top outlet of the isobutane separation tower B tower 18 is connected to the inlet of the reboiler 24 of tower A through the 30th pipeline 30, the outlet of the reboiler 24 of tower A is connected to the inlet of the cooler 22 through the 31st pipeline 31, and the outlet of the cooler 22 is connected to the inlet of the reflux tank 20 of tower B through the 32nd pipeline 32.

[0043] In a specific implementation, the raw material mixed carbon four enters the isobutane separation tower A tower 17 and the isobutane separation tower B tower 18 in proportion from the mixed carbon four feed pipeline 28 for separation. When the heat at the top of the isobutane separation tower B tower 18 is greater than the heat required at the bottom of the isobutane separation tower A tower 17, there is a lot of excess heat at the top of the isobutane separation tower B tower 18. The excess heat is used to heat the reboiler 24 of the tower A, and the excess heat enters the cooler 22 for cooling; isobutane is produced from the top of the separation tower, and normal butane is produced from the bottom of the separation tower.

[0044] This solution is flexible and more applicable. When considering the consumption of utilities, we make a budget based on 5% of the excess heat at the top of the tower.

[0045] The project's utility consumption is shown in Table 1:

[0046] Table 1 Public works consumption table

[0047]

[0048]

[0049] Compared with conventional separation systems, Example 1 of the present invention can save 15.8 t / h of steam and 1082.6 t / h of circulating water, reduce operating costs by 3489 yuan / h, and save approximately 27.91 million yuan per year.

[0050] Example 2

[0051] like Figure 2 As shown, a system for separating normal butane and isobutane by differential pressure heat-coupled distillation is shown. When the heat at the top of the isobutane separation tower B tower 18 is greater than or equal to the heat required at the bottom of the isobutane separation tower A tower 17, the system comprises an isobutane separation tower A tower 17, an isobutane separation tower B tower 18, a tower A reflux tank 19, a tower B reflux tank 20, a tower A condenser 21, a cooler 22, a tower A reboiler 24, a tower B reboiler 25, a tower A reflux pump 26, and a tower B reflux pump 27. The tower A condenser 21, the tower A reflux tank 19, and the tower A reflux pump 26 are sequentially arranged on the material pipeline at the top of the isobutane separation tower A tower 17, the tower A reboiler 24 is arranged at the bottom of the isobutane separation tower A tower 17, and the tower B reboiler 25 is arranged at the bottom of the isobutane separation tower B tower 18;

[0052] One side of the top of the isobutane separation tower B tower 18 is connected to the inlet of the reboiler 24 of tower A. The other side of the top of the isobutane separation tower B tower 18 is successively provided with a cooler 22, a B tower reflux tank 20, and a B tower reflux pump 27. The outlet of the B tower reflux pump 27 refluxes to the top of the isobutane separation tower B tower 18 and produces isobutane. The outlet of the reboiler 24 of tower A is connected to the inlet of the reflux tank 20 of tower B.

[0053] A mixed C4 feed pipeline 28 is provided in the middle of the isobutane separation tower A 17 and the isobutane separation tower B 18 .

[0054] The top outlet of the isobutane separation tower A tower 17 is connected to the inlet of the A tower condenser 21 through a first pipeline 1, the outlet of the A tower condenser 21 is connected to the inlet of the A tower reflux tank 19 through a second pipeline 2, the outlet of the A tower reflux tank 19 is connected to the inlet of the A tower reflux pump 26 through a third pipeline 3, and the outlet of the A tower reflux pump 26 is connected to the top inlet of the isobutane separation tower A tower 17 through a fourth pipeline 4.

[0055] The fourth pipeline 4 is provided with a fifth pipeline 5 , which is connected to the seventh pipeline 7 . The fifth pipeline 5 and the seventh pipeline 7 are isobutane production pipelines.

[0056] The outlet of the B tower reflux tank 20 is connected to the inlet of the B tower reflux pump 27 through the eighth pipeline 8, the outlet of the B tower reflux pump 27 is connected to the sixth pipeline 6 and the seventh pipeline 7 through the ninth pipeline 9, and the sixth pipeline 6 is connected to the top inlet of the isobutane separation tower B tower 18.

[0057] A normal butane extraction pipeline 29 is provided at the bottom of the isobutane separation tower A 17 and the isobutane separation tower B 18 .

[0058] A tenth pipeline 10 is provided at the top of the isobutane separation tower B tower 18, and the ends of the tenth pipeline 10 are branched into an eleventh pipeline 11 and a twelfth pipeline 12. The eleventh pipeline 11 is connected to the inlet of the reboiler 24 of Tower A, the twelfth pipeline 12 is connected to the inlet of the cooler 22, and the outlet of the cooler 22 is connected to the inlet of the reflux tank 20 of Tower B through the thirteenth pipeline 13, and the outlet of the reboiler 24 of Tower A is connected to the inlet of the reflux tank 20 of Tower B through the fourteenth pipeline 14.

[0059] In a specific implementation, the raw material mixed carbon four enters the isobutane separation tower A tower 17 and the isobutane separation tower B tower 18 in proportion from the mixed carbon four feed pipeline 28 for separation. When the heat at the top of the isobutane separation tower B tower 18 is equal to the heat required at the bottom of the isobutane separation tower A tower 17, the heat at the top of the isobutane separation tower B tower 18 is used to heat the reboiler 24 of the tower A. When the heat at the top of the isobutane separation tower B tower 18 is greater than the heat required at the bottom of the isobutane separation tower A tower 17, there is a large amount of excess heat at the top of the isobutane separation tower B tower 18. A part of the excess heat is used to heat the reboiler 24 of the tower A, and the excess heat enters the cooler 22 for cooling. Isobutane is produced from the top of the separation tower, and normal butane is produced from the bottom of the separation tower.

[0060] This solution is flexible and more applicable. When considering the consumption of utilities, we make a budget based on 5% of the excess heat at the top of the tower.

[0061] The project's utility consumption is shown in Table 2:

[0062] Table 2 Public works consumption table

[0063]

[0064]

[0065] Compared with conventional separation systems, Example 2 of the present invention can save 15.8 t / h of steam and 1082.6 t / h of circulating water, reducing operating costs by 3,489 yuan / h, and saving approximately 27.91 million yuan per year.

[0066] Example 3

[0067] like Figure 3As shown, a system for separating normal butane and isobutane by differential pressure heat-coupled distillation is shown. When the heat required at the top of the isobutane separation tower B tower 18 is less than the heat required at the bottom of the isobutane separation tower A tower 17, the system comprises an isobutane separation tower A tower 17, an isobutane separation tower B tower 18, a tower A reflux tank 19, a tower B reflux tank 20, a tower A condenser 21, a heater 23, a tower A reboiler 24, a tower B reboiler 25, a tower A reflux pump 26, and a tower B reflux pump 27. The tower A condenser 21, the tower A reflux tank 19, and the tower A reflux pump 26 are sequentially arranged on the material pipeline at the top of the isobutane separation tower A tower 17, the tower A reboiler 24 is arranged at the bottom of the isobutane separation tower A tower 17, and the tower B reboiler 25 is arranged at the bottom of the isobutane separation tower B tower 18;

[0068] The top of the isobutane separation tower B tower 18 is connected to the inlet of the reboiler 24 of tower A, and the outlet of the reboiler 24 of tower A is connected to the reflux tank 20 of tower B and the reflux pump 27 of tower B in sequence. The outlet of the reflux pump 27 of tower B refluxes to the top of the isobutane separation tower B tower 18 and produces isobutane. The heater 23 is set at the bottom of the isobutane separation tower A tower 17.

[0069] A mixed C4 feed pipeline 28 is provided in the middle of the isobutane separation tower A 17 and the isobutane separation tower B 18 .

[0070] The top outlet of the isobutane separation tower A tower 17 is connected to the inlet of the A tower condenser 21 through a first pipeline 1, the outlet of the A tower condenser 21 is connected to the inlet of the A tower reflux tank 19 through a second pipeline 2, the outlet of the A tower reflux tank 19 is connected to the inlet of the A tower reflux pump 26 through a third pipeline 3, and the outlet of the A tower reflux pump 26 is connected to the top inlet of the isobutane separation tower A tower 17 through a fourth pipeline 4.

[0071] The fourth pipeline 4 is provided with a fifth pipeline 5 , which is connected to the seventh pipeline 7 . The fifth pipeline 5 and the seventh pipeline 7 are isobutane production pipelines.

[0072] The outlet of the B tower reflux tank 20 is connected to the inlet of the B tower reflux pump 27 through the eighth pipeline 8, the outlet of the B tower reflux pump 27 is connected to the sixth pipeline 6 and the seventh pipeline 7 through the ninth pipeline 9, and the sixth pipeline 6 is connected to the top inlet of the isobutane separation tower B tower 18.

[0073] A normal butane extraction pipeline 29 is provided at the bottom of the isobutane separation tower A 17 and the isobutane separation tower B 18 .

[0074] The top of the isobutane separation tower B tower 18 is connected to the inlet of the reboiler 24 of tower A through the fifteenth pipeline 15, and the outlet of the reboiler 24 of tower A is connected to the inlet of the reflux tank 20 of tower B through the sixteenth pipeline 16; the bottom of the isobutane separation tower A tower 17 is provided with a heater 23 for heat supplement.

[0075] In a specific implementation, the raw material mixed C4 enters the isobutane separation tower A 17 and the isobutane separation tower B 18 in proportion from the mixed C4 feed pipeline 28 for separation. The heat at the top of the isobutane separation tower B 18 is insufficient, and a heater 23 is added to use the heater 23 to provide a small amount of heat to supplement the heat source; isobutane is extracted from the top of the separation tower, and normal butane is extracted from the bottom of the separation tower.

[0076] This solution is flexible and more applicable. When considering the consumption of utilities, the utilities consumption is budgeted based on a 5% shortfall in the tower top heat.

[0077] The project's utility consumption is shown in Table 3:

[0078] Table 3 Public works consumption table

[0079] Serial number project Specification unit Isobutane separation tower A Isobutane separation tower B total 1 circulating water 32-40℃ t / h 1582.1 0.0 1582.1 2 steam 0.35MPaG t / h 1.1 19.2 20.3

[0080] Compared with conventional separation systems, Example 3 of the present invention can save 15.9 t / h of steam and 1082.6 t / h of circulating water, reduce operating costs by 3506 yuan / h, and save approximately 28.048 million yuan per year.

[0081] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A system for separating n-butane and isobutane by differential pressure thermally coupled distillation, characterized by: The invention comprises an isobutane separation tower A tower (17), an isobutane separation tower B tower (18), a tower A reflux tank (19), a tower B reflux tank (20), a tower A condenser (21), a cooler (22) or a heater (23), a tower A reboiler (24), a tower B reboiler (25), a tower A reflux pump (26), and a tower B reflux pump (27), wherein the tower A condenser (21), the tower A reflux tank (19), and the tower A reflux pump (26) are sequentially arranged on a material pipeline at the top of the isobutane separation tower A tower (17), the tower A reboiler (24) is arranged at the bottom of the isobutane separation tower A tower (17), and the tower B reboiler (25) is arranged at the bottom of the isobutane separation tower B tower (18); When the heat at the top of the isobutane separation tower B (18) is greater than or equal to the heat required at the bottom of the isobutane separation tower A (17), the top outlet of the isobutane separation tower B (18) is connected to the inlet of the reboiler (24) of the A tower, and the outlet of the reboiler (24) of the A tower is sequentially provided with a cooler (22), a reflux tank (20) of the B tower, and a reflux pump (27) of the B tower. The outlet of the reflux pump (27) of the B tower is refluxed to the top of the isobutane separation tower B (18) and the isobutane is produced; or one side of the top of the isobutane separation tower B tower (18) is connected to the inlet of the reboiler (24) of the tower A, and the other side of the top of the isobutane separation tower B tower (18) is sequentially provided with a cooler (22), a B tower reflux tank (20), and a B tower reflux pump (27), the outlet of the B tower reflux pump (27) is refluxed to the top of the isobutane separation tower B tower (18) and isobutane is produced, and the outlet of the reboiler (24) of the tower A is connected to the inlet of the reflux tank (20) of the tower B; When the heat required at the top of the isobutane separation tower B (18) is less than the heat required at the bottom of the isobutane separation tower A (17), the top of the isobutane separation tower B (18) is connected to the inlet of the reboiler (24) of the A tower, and the outlet of the reboiler (24) of the A tower is connected to the reflux tank (20) of the B tower and the reflux pump (27) of the B tower in sequence. The outlet of the reflux pump (27) of the B tower refluxes to the top of the isobutane separation tower B (18) and extracts isobutane. The heater (23) is set at the bottom of the isobutane separation tower A (17).

2. The system for separating n-butane and isobutane by differential pressure thermally coupled distillation according to claim 1, characterized in that: A mixed C4 feed pipeline (28) is provided in the middle of the isobutane separation tower A (17) and the isobutane separation tower B (18).

3. The system for separating n-butane and isobutane by differential pressure thermally coupled distillation according to claim 1, characterized in that: The top outlet of the isobutane separation tower A (17) is connected to the inlet of the A tower condenser (21) through a first pipeline (1), the outlet of the A tower condenser (21) is connected to the inlet of the A tower reflux tank (19) through a second pipeline (2), the outlet of the A tower reflux tank (19) is connected to the inlet of the A tower reflux pump (26) through a third pipeline (3), and the outlet of the A tower reflux pump (26) is connected to the top inlet of the isobutane separation tower A (17) through a fourth pipeline (4).

4. The system for separating n-butane and isobutane by differential pressure thermally coupled distillation according to claim 3, characterized in that: A fifth pipeline (5) is provided on the fourth pipeline (4), the fifth pipeline (5) is connected to the seventh pipeline (7), and the fifth pipeline (5) and the seventh pipeline (7) are isobutane production pipelines.

5. The system for separating n-butane and isobutane by differential pressure thermally coupled distillation according to claim 1, characterized in that: The outlet of the B tower reflux tank (20) is connected to the inlet of the B tower reflux pump (27) through the eighth pipeline (8), the outlet of the B tower reflux pump (27) is connected to the sixth pipeline (6) and the seventh pipeline (7) through the ninth pipeline (9), and the sixth pipeline (6) is connected to the top inlet of the isobutane separation tower B tower (18).

6. The system for separating n-butane and isobutane by differential pressure thermally coupled distillation according to claim 1, characterized in that: The isobutane separation tower A (17) and the isobutane separation tower B (18) are provided with an n-butane extraction pipeline (29) at the bottom.

7. The system for separating n-butane and isobutane by differential pressure thermally coupled distillation according to claim 1, characterized in that: When the heat required at the top of the isobutane separation tower B (18) is greater than or equal to the heat required at the bottom of the isobutane separation tower A (17), the top outlet of the isobutane separation tower B (18) is connected to the inlet of the reboiler (24) of the tower A through the 30th pipeline (30), the outlet of the reboiler (24) of the tower A is connected to the inlet of the cooler (22) through the 31st pipeline (31), and the outlet of the cooler (22) is connected to the inlet of the reflux tank (20) of the tower B through the 32nd pipeline (32).

8. The system for separating n-butane and isobutane by differential pressure thermally coupled distillation according to claim 1, characterized in that: When the heat required at the top of the isobutane separation tower B (18) is greater than or equal to the heat required at the bottom of the isobutane separation tower A (17), a tenth pipeline (10) is provided at the top of the isobutane separation tower B (18), and the end of the tenth pipeline (10) branches into an eleventh pipeline (11) and a twelfth pipeline (12), the eleventh pipeline (11) is connected to the inlet of the reboiler (24) of the tower A, the twelfth pipeline (12) is connected to the inlet of the cooler (22), the outlet of the cooler (22) is connected to the inlet of the reflux tank (20) of the tower B through the thirteenth pipeline (13), and the outlet of the reboiler (24) of the tower A is connected to the inlet of the reflux tank (20) of the tower B through the fourteenth pipeline (14).

9. The system for separating n-butane and isobutane by differential pressure thermally coupled distillation according to claim 1, characterized in that: When the heat required at the top of the isobutane separation tower B (18) is less than the heat required at the bottom of the isobutane separation tower A (17), the top of the isobutane separation tower B (18) is connected to the inlet of the reboiler (24) of the tower A through the fifteenth pipeline (15), and the outlet of the reboiler (24) of the tower A is connected to the inlet of the reflux tank (20) of the tower B through the sixteenth pipeline (16); a heater (23) is provided at the bottom of the isobutane separation tower A (17) for heat supplementation.

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