Energy-saving device and process for recovering alcohols through ultrasonic extraction and thermal coupling

Abstract

The invention discloses an energy-saving device and process for recovering alcohols through ultrasonic extraction and thermal coupling, and belongs to the technical field of post-etherification C4 methanol recovery. The original technological process is changed, etherified C4 is subjected to two-stage extraction, and the characteristics of an ultrasonic generation technology and a thermal coupling technology are combined, so that on the premise of ensuring the recovery effect, the extraction efficiency of the second extraction tower is improved, the content of methanol in extraction water entering a methanol recovery system is improved, and the production cost is reduced. The method reduces the supplement of fresh water in the etherified C4 methanol recovery process, recovers the tower top gas phase latent heat of the methanol recovery tower, reduces the energy consumption, and has a good energy-saving effect.

Description

Technical Field

[0001] The invention relates to the technical field of post-etherification C4 methanol recovery, and in particular to an energy-saving device and process for recovering alcohols through ultrasonic extraction and thermal coupling. Background Art

[0002] In an MTBE production unit, the C4 ether fraction flowing out from the top of the azeotropic distillation tower or the catalytic distillation tower contains 1-3 wt.% of methanol, which forms an azeotrope with the C4 ether fraction. The C4 ether fraction containing methanol cannot be used as an alkylation feedstock or as a civilian liquefied gas fuel, so the two must be separated.

[0003] Conventional distillation methods are incapable of separating the formed azeotrope, so extraction is the most commonly used separation method in China. Water and etherified C4 are immiscible, but completely miscible with methanol. Therefore, methanol can be extracted from the etherified C4 azeotrope, reducing the residual methanol content in the etherified C4 to less than 0.01 wt.%. However, methanol-containing water enters the methanol recovery tower, where distillation is required to separate the methanol and water, a process that consumes a lot of energy.

[0004] The extraction process is simple and environmentally friendly, but controlling the methanol content in the post-etherification C4 requires a high water volume. The low methanol concentration in the extraction water results in high energy consumption in the downstream methanol recovery tower. Furthermore, the latent heat of the overhead vapor phase in the methanol recovery tower is not effectively utilized, resulting in significant energy consumption. Heat pump distillation technology requires a temperature difference between the tower top and the bottom of the tower to be ≤36°C. Otherwise, increasing the energy required to generate the overhead vapor heat source would exceed the vapor phase latent heat. However, this temperature difference in the methanol recovery tower is typically above 40°C. Consequently, technologies such as heat pumps to increase the overhead vapor phase heat source and thereby utilize this latent heat have not been developed.

[0005] Chinese utility model patent CN218339008U discloses an alcohol recovery device for ether production and ether decomposition. This device uses a single-tower cyclic extraction process to increase the alcohol concentration in the aqueous alcohol solution entering the alcohol recovery system, achieving energy savings. However, this device still relies on single-tower extraction technology, ignoring the impact of dual-tower cyclic extraction on the extraction process and the possibility of coupling with other technologies. Consequently, energy savings are limited, and the device also fails to utilize the latent heat of the distillation tower overhead, resulting in high energy consumption. Summary of the Invention

[0006] The technical problem to be solved by the present invention is: to overcome the shortcomings of the existing technology and provide an energy-saving device and process for ultrasonic extraction thermal coupling recovery of alcohols. While ensuring the recovery effect, the extraction efficiency of the No. 2 extraction tower is improved, the methanol content of the extraction water entering the methanol recovery system is increased, and the gas phase latent heat at the top of the methanol recovery tower is recovered at the same time, energy consumption is reduced, and good energy-saving effect is achieved.

[0007] The technical solution of the present invention is:

[0008] On the one hand, the present invention provides an energy-saving device for recovering alcohols by ultrasonic extraction and thermal coupling, comprising a No. 1 extraction tower, wherein the No. 1 extraction tower is provided with a water inlet pipeline, an extraction water outlet pipeline 1 and an etherified C4 outlet pipeline 1; and further comprising a No. 2 extraction tower, wherein the No. 2 extraction tower is provided with an ultrasonic generator; the No. 2 extraction tower is provided with an etherified C4 feed pipeline, an extraction water outlet pipeline 2 and an etherified C4 outlet pipeline 2, the extraction water outlet pipeline 1 and the extraction water outlet pipeline 2 are connected to a mixed extraction water inlet pipeline and a methanol recovery heat exchange pipeline, and the etherified C4 outlet pipeline 2 is connected to the No. 1 extraction tower; the mixed extraction water The water inlet pipeline is connected to the No. 2 extraction tower, the methanol recovery heat exchange pipeline is connected to the heat exchanger, the methanol recovery feed pipeline of the heat exchanger is connected to the methanol recovery tower, the methanol recovery tower is provided with a bottom water outlet pipeline and a methanol discharge pipeline 1, the methanol discharge pipeline 1 is connected to the compressor, the compressed gas discharge pipeline of the compressor is connected to the heat exchanger, the heat exchange medium discharge pipeline of the heat exchanger is connected to the condenser, the condenser is connected to the methanol discharge pipeline 2, the methanol discharge pipeline 2 is connected to the methanol finished product discharge pipeline and the methanol reflux pipeline, the methanol reflux pipeline is connected to the methanol recovery tower, and the methanol recovery tower is also connected to a reboiler.

[0009] The two extraction towers can be in plate form or regular form, and the gas-liquid exchange form with small pressure drop and strong mass transfer capacity is preferred.

[0010] Preferably, the number of theoretical plates of the No. 1 extraction tower and the No. 2 extraction tower is 2-5.

[0011] Preferably, the ultrasonic generators are evenly arranged in multiple rows on the wall of the No. 2 extraction tower.

[0012] Preferably, the ultrasonic generators are arranged in 1-8 rows, and 1-16 ultrasonic generators are arranged in every four meters of each row.

[0013] Preferably, the bottom water outlet pipeline of the methanol recovery tower is connected to the water inlet pipeline of the No. 1 extraction tower.

[0014] On the other hand, the present invention also provides an energy-saving process for recovering alcohols through ultrasonic extraction and thermal coupling of the above-mentioned device. The etherified C4 containing methanol enters the No. 2 extraction tower and is extracted with mixed extraction water under the action of ultrasonic waves emitted by an ultrasonic generator. The extracted etherified C4 enters the No. 1 extraction tower. The extraction water produced after water extraction is mixed with the extraction water of the No. 2 extraction tower to form mixed extraction water. Part of it enters the No. 2 extraction tower to extract the etherified C4, and part of it enters the methanol recovery tower after heat exchange in the heat exchanger; the methanol separated from the methanol recovery tower enters the compressor for compression, and then enters the heat exchanger as a heat exchange medium to exchange heat with the mixed extraction water. The compressed methanol after heat exchange enters the condenser for condensation, and part of it is produced as a finished product, and the other part is refluxed to the methanol recovery tower.

[0015] Preferably, the top pressure of the No. 1 extraction tower is 0.4-0.7 MPa, more preferably, the top pressure of the No. 1 extraction tower is 0.5-0.6 MPa; the top temperature is 40-50°C, more preferably, the top temperature is 44-47°C; the bottom pressure is 0.5-0.9 MPa, more preferably, the bottom pressure is 0.6-0.7 MPa; the bottom temperature is 50-60°C, more preferably, the bottom temperature is 52-55°C.

[0016] Preferably, the top pressure of the No. 2 extraction tower is 0.5-0.9 MPa, more preferably, the top pressure is 0.6-0.7 MPa; the top temperature is 50-60°C, more preferably, the top temperature is 53-56°C; the bottom pressure is 0.6-1.0 MPa, more preferably, the bottom pressure is 0.7-0.8 MPa; the bottom temperature is 50-60°C, more preferably, the bottom temperature is 55-58°C.

[0017] Preferably, the top pressure of the methanol recovery tower is 0.3-0.4 MPa, more preferably, the top pressure is 0.35 MPa; the bottom pressure is 0.35-0.45 MPa, more preferably, the bottom pressure is 0.38 MPa; the top temperature is 95-100°C, more preferably, the top temperature is 98°C; the bottom temperature is 140-145°C, more preferably, the bottom temperature is 142°C.

[0018] Preferably, the power of the ultrasonic generator is 0.01-300 kW, and the frequency is 20 kHz-2000 kHz; more preferably, the power of the ultrasonic generator is 200-250 kW, and the frequency is 100-150 kHz.

[0019] Preferably, the mixed extraction water entering the second extraction tower accounts for 1-99 wt.% of all mixed extraction water, and more preferably, the mixed extraction water entering the second extraction tower accounts for 40-50 wt.% of all mixed extraction water.

[0020] Preferably, the compression ratio of the compressor is 1.2-3.0, and more preferably, the compression ratio of the compressor is 1.5-2.0.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The present invention changes the original process flow, so that the post-ether C4 undergoes two-stage extraction. Combined with the characteristics of ultrasonic generation technology, while ensuring the recovery effect, it improves the extraction efficiency of the No. 2 extraction tower, increases the methanol content of the extraction water entering the methanol recovery system, reduces the replenishment of fresh water in the post-ether C4 methanol recovery process, reduces energy consumption, and has a good energy-saving effect. At the same time, the present invention utilizes the characteristics of the compressor to improve the gas phase heat source level, breaking the requirement of heat pump distillation technology that the temperature difference between the tower top and the tower bottom is ≤36°C, recovers the gas phase latent heat at the top of the methanol recovery tower, and has a good energy-saving effect. Under the condition of meeting the requirements for the methanol content in the post-ether C4 after extraction, the present invention increases economic benefits, has simple equipment, is easy to operate, and does not introduce other impurities.

[0023] 2. The present invention provides a separate action position for the ultrasonic generator, so that the ultrasonic generator does not interfere with other equipment, thereby improving the stability and safety of the device.

[0024] 3. The process of the present invention is applicable to all C4 components and is applicable to the recovery of C4 methanol after etherification with a methanol content of 1-5 wt.%. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0026] Figure 1 It is a structural schematic diagram of the energy-saving device for recovering alcohols by ultrasonic extraction and thermal coupling according to the present invention.

[0027] In the figure, 1. Extraction tower No. 1; 101. Water inlet pipeline; 102. Extraction water outlet pipeline 1; 103. Etherified C4 outlet pipeline 1; 2. Extraction tower No. 2; 201. Etherified C4 feed pipeline; 202. Extraction water outlet pipeline 2; 203. Etherified C4 outlet pipeline 2; 204. Mixed extraction water inlet pipeline; 3. Ultrasonic generator; 4. Heat exchanger; 401. Methanol recovery heat exchange pipeline; 402. Heat exchange medium outlet pipeline; 5. Methanol recovery tower; 501. Methanol recovery feed pipeline; 502. Tower bottom water outlet pipeline; 503. Methanol outlet pipeline 1; 6. Reboiler; 7. Condenser; 701. Methanol reflux pipeline; 702. Methanol finished product outlet pipeline; 8. Compressor; 801. Compressed gas outlet pipeline. DETAILED DESCRIPTION

[0028] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0029] Example 1

[0030] like Figure 1 As shown, the energy-saving device for ultrasonic extraction thermal coupling recovery of alcohols in this embodiment includes an extraction tower No. 1. The extraction tower No. 1 has two feed ports. The top feed port is connected to the water inlet pipeline 101, which feeds a mixture of water and fresh water from the bottom of the methanol recovery tower 5. The bottom feed port is connected to the ether-post-C4 discharge pipeline 203, which feeds the ether-post-C4 from the top outlet of the No. 2 extraction tower 2; the extraction tower No. 1 has two discharge ports, the top discharge port is connected to the ether-post-C4 discharge pipeline 103, which discharges the extracted ether-post-C4, and the bottom discharge port is connected to the extraction water discharge pipeline 102, which discharges the extracted water from the extraction tower No. 1.

[0031] The method further comprises a No. 2 extraction tower 2, on the wall of which a row of ultrasonic generators 3 is arranged, with two ultrasonic generators 3 arranged at intervals of two meters in the row of ultrasonic generators 3; the No. 2 extraction tower 2 has two feed ports, the top feed port is connected to a mixed extraction water inlet pipeline 204, for feeding in a mixed extraction water of the extraction water of the No. 1 extraction tower 1 and the extraction water of the No. 2 extraction tower 2, the bottom feed port is connected to a C4 after ether feed pipeline 201, for feeding in unextracted C4 after ether; the No. 2 extraction tower 2 has two discharge ports, the top discharge port is connected to a C4 after ether discharge pipeline 203, for discharging the C4 after preliminary extraction, the bottom discharge port is connected to a second extraction water discharge pipeline 202, for discharging the extraction water of the No. 2 extraction tower 2. The extraction water outlet pipeline 102 and the extraction water outlet pipeline 202 are connected to the methanol recovery heat exchange pipeline 401, the methanol recovery heat exchange pipeline 401 is connected to the heat exchanger 4, the methanol recovery feed pipeline 501 of the heat exchanger 4 is connected to the methanol recovery tower 5, the methanol recovery tower 5 is provided with a bottom water outlet pipeline 502 and a methanol discharge pipeline 1 503, the bottom water outlet pipeline 502 is connected to the water inlet pipeline 101 of the No. 1 extraction tower 1; the methanol discharge pipeline 1 503 is connected to the compressor 8, the compressed gas discharge pipeline 801 of the compressor 8 is connected to the heat exchanger 4, the heat exchange medium discharge pipeline of the heat exchanger 4 is connected to the condenser 7, the condenser 7 is connected to the methanol discharge pipeline 2, the methanol discharge pipeline 2 is connected to the methanol finished product discharge pipeline 702 and the methanol reflux pipeline 701, the methanol reflux pipeline 701 is connected to the methanol recovery tower 5; the methanol recovery tower 5 is also connected to the reboiler 6.

[0032] The energy-saving process for recovering alcohols by ultrasonic extraction and thermal coupling using the device of this embodiment is as follows:

[0033] The etherified C4 feedstock enters Extraction Tower 2, where it countercurrently contacts the mixed extract water at the top of Extraction Tower 2. Under the action of an ultrasonic generator 3, the methanol in the etherified C4 is extracted into the water. The extracted etherified C4 enters Extraction Tower 1, where it countercurrently contacts a mixture of water from the bottom of the methanol recovery tower 5 and fresh water, producing demethanolized etherified C4. The extracted water from Extraction Tower 1 is mixed with the water from Extraction Tower 2 to form a mixed extract water. 50% of the mixed extract water enters Extraction Tower 2 as the top water, while the remaining 50% enters the methanol recovery tower 5 after heat exchange in heat exchanger 4 as methanol recovery material. The methanol separated in the methanol recovery tower 5 enters compressor 8 for compression, then enters heat exchanger 4 as a heat exchange medium for heat exchange with the mixed extract water. The compressed methanol enters condenser 7 for condensation, with a portion withdrawn as finished methanol and the remaining portion refluxed to the methanol recovery tower 5. After the liquid in the bottom of the methanol recovery tower 5 is reboiled in the reboiler 6, the bottom water is mixed with fresh water through the bottom water outlet pipeline 502 and then enters the No. 1 extraction tower 1.

[0034] According to the above process flow, the theoretical number of plates of extraction tower No. 1 is 3, the top pressure is 0.55 MPa, the top temperature is 45°C, the bottom pressure is 0.65 MPa, and the bottom temperature is 53°C; the theoretical number of plates of extraction tower No. 2 is 3, the top pressure is 0.65 MPa, the top temperature is 55°C, the bottom pressure is 0.75 MPa, and the bottom temperature is 57°C; the top pressure of methanol recovery tower 5 is 0.35 MPa, the top temperature is 98°C, the bottom pressure is 0.38 MPa, and the bottom temperature is 142°C; the power of ultrasonic generator 3 is 220 kW, the frequency is 100 kHz; the compression ratio of compressor 8 is 2.0.

[0035] It is stipulated that the methanol content in the C4 after de-methanolization ether is ≤0.01wt.%, the total amount of C4 after feed ether is fixed at 6.2t / h, and the feed water-oil ratio is not stipulated. The methanol content in the extraction water entering the methanol recovery system composed of the methanol recovery tower 5, condenser 7, reboiler 6 and compressor 8 and the energy consumption of the methanol recovery system are examined.

[0036] The composition of the C4 feed after etherification entering the No. 2 extraction tower 2 is shown in Table 1:

[0037] Table 1

[0038]

[0039] Example 2

[0040] The difference from Example 1 is that in the energy-saving device for ultrasonic extraction and recovery of alcohols, the number of ultrasonic generators 3 is one.

[0041] Example 3

[0042] The difference from Example 1 is that in the energy-saving device for ultrasonic extraction and recovery of alcohols, there are four ultrasonic generators 3, and the four ultrasonic generators 3 are vertically arranged on the wall of the second extraction tower 2 at a distance of four meters.

[0043] Example 4

[0044] The difference from Example 1 is that the power of the ultrasonic generator 3 is 150 kW.

[0045] Example 5

[0046] The difference from Example 1 is that the power of the ultrasonic generator 3 is 300 kW.

[0047] Example 6

[0048] The difference from Example 1 is that the power of the ultrasonic generator 3 is 50 kHz.

[0049] Example 7

[0050] The difference from Example 1 is that the power of the ultrasonic generator 3 is 150 kHz.

[0051] Example 8

[0052] The difference from Example 1 is that the extracted water from the No. 1 extraction tower 1 is mixed with the extracted water from the No. 2 extraction tower 2 to form mixed extracted water, of which 40% of the mixed extracted water enters the No. 2 extraction tower 2 as the top water of the No. 2 extraction tower 2.

[0053] Example 9

[0054] The difference from Example 1 is that the extracted water from the No. 1 extraction tower 1 is mixed with the extracted water from the No. 2 extraction tower 2 to form mixed extracted water, of which 60% of the mixed extracted water enters the No. 2 extraction tower 2 as the top water of the No. 2 extraction tower 2.

[0055] Example 10

[0056] The difference from Example 1 is that the compression ratio of the compressor 8 is 1.5.

[0057] Example 11

[0058] The difference from Example 1 is that the compression ratio of the compressor 8 is 2.5.

[0059] Comparative Example 1

[0060] Comparative Example 1 employed conventional single-tower extraction, i.e., a single extraction tower was used to extract the etherified C4. The process flow was as follows: the etherified C4 entered the extraction tower and was countercurrently contacted with a mixture of water from the bottom of the methanol recovery tower 5 and fresh water to produce the demethanoled etherified C4. The extracted water was then heat exchanged in heat exchanger 4 before entering the methanol recovery tower 5. After distillation, the water was condensed in the overhead condenser 7 of the methanol recovery tower 5 and reboiled in the bottom reboiler 6. Methanol was produced at the top of the tower, and the bottom water was mixed with fresh water before entering the extraction tower.

[0061] Comparative Example 2

[0062] Comparative Example 2 adopts the energy-saving device and process for recovering alcohols by ultrasonic extraction of Example 1, except that the ultrasonic generator 3 is not started.

[0063] Comparative Example 3

[0064] Comparative Example 3 employs conventional single-tower extraction, i.e., a single extraction tower is used to extract the etherified C4. An ultrasonic generator 3 is installed in the extraction tower, and the configuration of the ultrasonic generator 3 is the same as in Example 1. The process flow is as follows: the etherified C4 enters the extraction tower and is countercurrently contacted with a mixture of water from the bottom of the methanol recovery tower 5 and fresh water. Under the action of ultrasonic waves in the lower portion of the tower, methanol in the etherified C4 is removed, yielding demethanolized etherified C4. The extracted water undergoes heat exchange in heat exchanger 4 and enters methanol recovery tower 5. The overhead gas phase is compressed by compressor 8 and then enters heat exchanger 4 for heat exchange with the mixed extracted water. After heat exchange, it is cooled by cooler 7, with a portion refluxed back to the methanol recovery tower 5 and a portion withdrawn as methanol product. The bottom water from the methanol recovery tower 5 is mixed with fresh water and then enters the extraction tower.

[0065] Comparative Example 4

[0066] Comparative Example 4 employs dual-tower ultrasonic extraction, differing from Example 1 in that methanol vapor compression is not performed. The process flow is as follows: the etherified C4 feedstock enters Extraction Tower 2, where it countercurrently contacts the mixed extract water at the top of Extraction Tower 2. Under the action of an ultrasonic generator 3, the methanol in the etherified C4 is extracted into the water. The extracted etherified C4 enters Extraction Tower 1, where it countercurrently contacts a mixture of water from the bottom of the methanol recovery tower 5 and fresh water, producing demethanolized etherified C4. The extracted water from Extraction Tower 1 is mixed with the water from Extraction Tower 2 to form a mixed extract water. 50% of the mixed extract water enters Extraction Tower 2 as the top water, while the remaining 50% enters the methanol recovery tower 5 after heat exchange in heat exchanger 4 as methanol recovery material. After distillation, condensation occurs in the overhead condenser 7 of the methanol recovery tower 5 and reboiler 6. Methanol is produced at the top of the methanol recovery tower 5, and the bottom water is mixed with fresh water before entering Extraction Tower 1.

[0067] Comparative Example 5

[0068] The difference between Comparative Example 5 and Example 1 is that in the composition of the C4 feed after etherification, the methanol content is increased to 5.2 wt.%, and the contents of other components are reduced in the same proportion.

[0069] The process parameters of Examples 1-11 and Comparative Examples 1-5, the methanol concentration in the extraction water entering the methanol recovery system, and the energy consumption of the methanol recovery system are shown in Table 2:

[0070] Table 2

[0071]

[0072]

[0073] As can be seen from Table 2, compared with Comparative Example 1, Comparative Example 2 using a double-tower structure alone and Comparative Example 3 using ultrasonic action alone can both increase the methanol concentration in the extracted water and reduce energy consumption. However, when ultrasonic action is used alone in Comparative Example 3, the energy-saving effect is small, while the use of a double-tower structure alone in Comparative Example 2 can reduce the amount of circulating water and fresh water by 22.8%, and the overall energy consumption is reduced by 16.6%, which has a good energy-saving effect. At the same time, by comparing Example 1 with Comparative Example 4, it can be seen that the effect of thermal coupling technology in reducing energy consumption is more significant. Example 1 of the present invention using thermal coupling technology can effectively reduce the overall energy consumption by 47.8%. In addition, it can be seen from Comparative Example 5 that when the methanol concentration in the etherified C4 exceeds 5wt.%, the effect of ultrasonic circulation extraction will deteriorate relative to Example 1. The methanol concentration in the etherified C4 feed is increased by about 2 times, the water consumption increases by 196%, and the energy consumption increases by 163%. Both water consumption and energy consumption increase significantly. As can be seen from Examples 1-11, the present invention utilizes the synergistic effect of a dual-tower structure and ultrasonic waves to significantly reduce water usage and save energy. Two ultrasonic generators 3 can meet separation requirements. Increasing the number of ultrasonic generators 3 can improve separation efficiency, but this also increases investment and energy consumption. Similar to increasing the number of ultrasonic generators 3, increasing the power of ultrasonic generators 3 also facilitates separation. However, excessive ultrasonic power will not significantly improve separation efficiency, and energy consumption will increase significantly. Furthermore, when the frequency of ultrasonic generators 3 exceeds 50 kHz, it has little impact on separation efficiency. When the return ratio of mixed extract water exceeds 50%, further increasing the return ratio has little impact on separation efficiency. Furthermore, from the perspective of reducing the size and energy consumption of equipment such as pumps, a return ratio of 50% is a reasonable value. Increasing the compression ratio of compressor 8 results in greater energy savings, but this also increases compressor 8 energy consumption. Considering energy costs, a compression ratio of 2.0 is suitable.

[0074] In summary, the energy-saving device and process for ultrasonic extraction and thermal coupling for alcohol recovery of the present invention, through the synergistic effect of the dual-tower structure and ultrasonic waves, employs an appropriate number of ultrasonic generators (3), ultrasonic frequency, and extraction water return ratio, resulting in high ultrasonic power, which facilitates the recovery of methanol from post-etherification C4. Thermal coupling technology effectively reduces the energy consumption of the methanol recovery system. Using the device and process of the present invention, water consumption during the post-etherification C4 extraction process is significantly reduced, as is the overall energy consumption of the methanol recovery system, resulting in significant energy savings.

[0075] Although the present invention has been described in detail with reference to the accompanying drawings and in combination with preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, a person of ordinary skill in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and such modifications or substitutions shall be within the scope of the present invention. Any person skilled in the art who is familiar with the present invention may easily conceive of changes or substitutions within the technical scope disclosed in the present invention, and such changes or substitutions shall be within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the claims.

Claims

1. An energy-saving device for recovering alcohols by ultrasonic extraction and thermal coupling, comprising a first extraction tower (1), characterized in that: The first extraction tower (1) is provided with a water inlet pipeline (101), an extraction water outlet pipeline (102) and a first etherification carbon four discharge pipeline (103); it also includes a second extraction tower (2), and the second extraction tower (2) is provided with an ultrasonic generator (3); the second extraction tower (2) is provided with a etherification carbon four feed pipeline (201), a second extraction water outlet pipeline (202) and a second etherification carbon four discharge pipeline (203); the first extraction water outlet pipeline (102) and the second extraction water outlet pipeline (202) are connected to the mixed extraction water inlet pipeline (204) (101) and the methanol recovery heat exchange pipeline (401); the second etherification carbon four discharge pipeline (203) is connected to the first extraction tower (1); the mixed extraction water inlet pipeline (204) (101) is connected to the second extraction tower (2), and the methanol recovery heat exchange pipeline (401) is connected to the second extraction tower (203); the mixed extraction water inlet pipeline (204) (101) is connected to the second extraction tower (2), and the methanol recovery heat exchange pipeline (401) is connected to the second extraction tower (2). The heat exchange pipeline (401) is connected to the heat exchanger (4), the methanol recovery feed pipeline (501) of the heat exchanger (4) is connected to the methanol recovery tower (5), the methanol recovery tower (5) is provided with a tower bottom water outlet pipeline (502) and a methanol discharge pipeline (503), the methanol discharge pipeline (503) is connected to the compressor (8), the compressed gas discharge pipeline (801) of the compressor (8) is connected to the heat exchanger (4), the heat exchange medium discharge pipeline (402) of the heat exchanger (4) is connected to the condenser (7), the condenser (7) is connected to the methanol discharge pipeline (2), the methanol discharge pipeline (2) is connected to the methanol finished product discharge pipeline (702) and the methanol reflux pipeline (701), the methanol reflux pipeline (701) is connected to the methanol recovery tower (5), and the methanol recovery tower (5) is also connected to the reboiler (6).

2. The energy-saving device for recovering alcohols by ultrasonic extraction and thermal coupling according to claim 1, characterized in that: The number of theoretical plates of the No. 1 extraction tower (1) and the No. 2 extraction tower (2) is 2-5.

3. The energy-saving device for recovering alcohols by ultrasonic extraction and thermal coupling according to claim 1, characterized in that: The ultrasonic generators (3) are evenly arranged in multiple rows on the wall of the second extraction tower (2).

4. The energy-saving device for recovering alcohols by ultrasonic extraction and thermal coupling as claimed in claim 3, characterized in that: The ultrasonic generators (3) are arranged in 1-8 rows, and 1-16 ultrasonic generators are arranged in every four meters of each row.

5. The energy-saving device for recovering alcohols by ultrasonic extraction and thermal coupling according to claim 1, characterized in that: The bottom water outlet pipeline (502) of the methanol recovery tower (5) is connected to the water inlet pipeline (101) of the first extraction tower (1).

6. An energy-saving process for recovering alcohols by ultrasonic extraction and thermal coupling according to any one of claims 1 to 5, characterized in that: The etherified C4 containing methanol enters the second extraction tower (2), is extracted with mixed extraction water under the action of ultrasonic waves emitted by the ultrasonic generator (3), and the extracted etherified C4 enters the first extraction tower (1). The extraction water generated after water extraction is mixed with the extraction water of the second extraction tower (2) to form mixed extraction water, a part of which enters the second extraction tower (2) to extract the etherified C4, and a part of which enters the methanol recovery tower (5) after heat exchange in the heat exchanger (4); the methanol separated by the methanol recovery tower (5) enters the compressor (8) for compression, and then enters the heat exchanger (4) as a heat exchange medium to exchange heat with the mixed extraction water. The compressed methanol after heat exchange enters the condenser (7) for condensation, a part of which is extracted as a finished product, and the other part is refluxed to the methanol recovery tower (5).

7. The energy-saving process for recovering alcohols by ultrasonic extraction and thermal coupling according to claim 6, characterized in that: The top pressure of the No. 1 extraction tower (1) is 0.4-0.7 MPa, the top temperature is 40-50°C, the bottom pressure is 0.5-0.9 MPa, and the bottom temperature is 50-60°C.

8. The energy-saving process for recovering alcohols by ultrasonic extraction and thermal coupling according to claim 6, characterized in that: The top pressure of the second extraction tower (2) is 0.5-0.9 MPa, the top temperature is 50-60°C, the bottom pressure is 0.6-1.0 MPa, and the bottom temperature is 50-60°C.

9. The energy-saving process for recovering alcohols by ultrasonic extraction and thermal coupling according to claim 6, characterized in that: The power of the ultrasonic generator (3) is 0.01-300 kW, and the frequency is 20 kHz-2000 kHz.

10. The energy-saving process for recovering alcohols by ultrasonic extraction and thermal coupling according to claim 6, characterized in that: The compression ratio of the compressor (8) is 1.2-3.0.

Images