Heat energy recovery device for separating C9 heavy aromatics and recovery method thereof

Abstract

The invention relates to the technical field of chemical energy recovery, in particular to a heat energy recovery device for C9 heavy aromatics separation and a recovery method thereof.The recovery device comprises a light component removal tower, a tower top evaporator, a steam compressor, a tower bottom condenser and a closed-loop waterway system; a gas phase outlet in the top of the light component removal tower is connected with a material inlet in the tower top evaporator through a gas phase conveying pipe, a low-pressure steam outlet in the top of the tower top evaporator is communicated with the gas inlet end of the steam compressor through a pipeline, and the gas outlet end of the steam compressor is connected with a steam inlet in the tower bottom condenser through a high-pressure steam pipe. The condensation process of 125 DEG C gas phase materials at the top of the light component removal tower is coupled with the evaporation process of hot water in the hot water evaporation section through the tower top evaporator, and gradient utilization of gas phase latent heat is achieved. Compared with a traditional air cooling process, the heat energy recovery rate is high, additional cooling energy consumption is avoided, and the comprehensive energy consumption of the system is remarkably reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical energy recovery, and in particular to a heat energy recovery device for separating nine-carbon aromatic hydrocarbons and a recovery method thereof. Background Art

[0002] In the field of separation of C9 heavy aromatics, traditional processes rely on distillation tower systems to achieve component separation. During the process, a large amount of heat energy is consumed to increase the material temperature. However, a large amount of heat energy carried by the light components in the gas phase at the top of the de-light tower is often wasted due to limitations in recovery technology. In existing technologies, the gas phase at the top of the de-light tower is usually cooled by air cooling. This process not only fails to effectively recover the latent heat of the gas phase, but also consumes additional cooling energy, resulting in low overall energy efficiency of the system. At the same time, even if some processes attempt to recover waste heat, due to structural design defects in the heat exchange equipment, such as severe coking of the heat exchange tube bundle and unreasonable flow channel design, the heat recovery efficiency is further reduced, forming a vicious cycle of energy waste and additional energy consumption. In addition, low-pressure steam faces the dual technical bottlenecks of high pressure boosting energy consumption and unstable quality during the recycling process.

[0003] The traditional single-stage compression process, when boosting the low-pressure steam generated by overhead evaporation to high-pressure steam, suffers from low energy conversion efficiency. Furthermore, the steam temperature fluctuates significantly during the compression process, easily leading to unstable steam quality and making it difficult to meet the stable operation requirements of heat-consuming equipment such as the tower bottom reboiler. Furthermore, existing steam compressors lack efficient interstage cooling systems, resulting in increased energy loss during the compression process. This further exacerbates the system's energy consumption and makes it difficult to achieve a balanced economic and technical approach to recycling low-pressure steam. These issues severely hinder energy conservation and consumption reduction in the C9 separation process, as well as green production. Summary of the Invention

[0004] The object of the present invention is to provide a heat energy recovery device for separating nine-carbon aromatics and a recovery method thereof to solve the technical problems raised in the above background technology.

[0005] To achieve the above objectives, the present invention provides the following technical solutions.

[0006] A heat energy recovery device for separating nine-carbon heavy aromatics comprises a light-removing tower, a tower top evaporator, a steam compressor, a tower bottom condenser and a closed-loop water system, wherein the gas phase outlet at the top of the light-removing tower is connected to the material inlet on the tower top evaporator via a gas phase conveying pipe, the low-pressure steam outlet at the top of the tower top evaporator is connected to the air inlet of the steam compressor via a pipeline, the air outlet of the steam compressor is connected to the steam inlet on the tower bottom condenser via a high-pressure steam pipe, and the condensed water outlet on the tower bottom condenser is connected to the hot water inlet on the tower top evaporator via the closed-loop water system to form a steam and water circulation loop.

[0007] Preferably, the top evaporator includes an outer tube, a heat exchange tube and a spiral baffle. The heat exchange tube is fixed in the outer tube, and the heat exchange tube is a gas phase condensation section and a hot water evaporation section from top to bottom, and the gas phase condensation section and the hot water evaporation section are connected through a conical transition section. The low-pressure steam outlet is connected to the heat exchange tube, and the hot water inlet is connected to the gas phase condensation section. The spiral baffle is wound around the outside of the gas phase condensation section, and the outer edge is tightly fitted with the inner wall of the outer tube to form a spiral conveying path. The material inlet extends through the outer tube and is connected to the top of the spiral conveying path. The return water port at the bottom of the outer tube is connected to the top of the de-lightening tower through a U-shaped liquid seal tube.

[0008] Preferably, the steam compressor is a two-stage Roots compressor having three impellers for progressive compression.

[0009] Preferably, a reboiler is provided at the bottom of the de-light tower, and a bottom condenser is integrated at the bottom of the reboiler. The bottom condenser comprises an outer tank body, an inner cylinder body, a condenser tube bundle and an annular shell. The inner cylinder body is coaxially fixed in the outer tank body, and the two are jointly provided with an installation cavity which passes vertically upward. The condenser tube bundle is installed in the installation cavity, and the top end extends into the reboiler. The annular shell is arranged at the top of the outer tank body around the inner cylinder body. The steam inlet extends into the outer tank body and is connected with the annular shell. Several grid plates are fixed on the outer wall of the inner cylinder body. The grid plates are radially distributed to form several vertically extending fan-shaped flow channels. Several guide ports are provided at the bottom of the annular shell. Each guide port is connected to the fan-shaped flow channel one by one, and the condensed water outlet is connected with the inner bottom of the outer tank body.

[0010] Preferably, the closed-loop water system includes a circulation pipe, an expansion water tank, a deaerator, a high-temperature water pump and a pH adjustment tank. One end of the circulation pipe is connected to the condensate outlet, and the other end is connected to the hot water inlet. The expansion water tank, deaerator, high-temperature water pump and pH adjustment tank are installed on the circulation pipe in sequence.

[0011] Preferably, the pH adjustment tank has three compartments, which are the first compartment, the second compartment and the third compartment from bottom to top, and each compartment is provided with a stirring component and a pH meter.

[0012] Preferably, the recovery device also includes an intelligent control system, which includes a DCS controller, a gas chromatograph, a pressure transmitter, an electric control valve and a temperature sensor. The DCS controller is connected to the gas chromatograph, the pressure transmitter, the electric control valve and the temperature sensor respectively through an industrial bus. The gas chromatograph is installed in the gas sampling port at the top of the de-light tower, the pressure transmitter is integrated in the gas delivery pipe, the electric control valve is assembled on the circulation pipe and is located downstream of the high-temperature water pump, the temperature sensor is installed on the hot water inlet, and the detection end extends through the hot water inlet.

[0013] The present invention also provides a method for recovering heat energy for separating C9 aromatics, which specifically comprises the following steps: Step 1: The 125°C gaseous material at the top of the light removal tower is introduced into the top evaporator, condensed at the heat exchange tube to release latent heat, and the condensate is returned to the light removal tower through the U-shaped liquid seal tube; Step 2: The released latent heat is transferred to the hot water evaporation section through the tapered transition section, evaporating the hot water in the hot water evaporation section into low-pressure steam at 0.15MPa and 115℃. The water level in the hot water evaporation section fluctuates by ±10mm. Step 3: The low-pressure steam is compressed into 1.2MPa high-pressure steam through three stages of steam compressor; Step 4: High-pressure steam enters the outer tank, is heated by the liquid material in the reboiler, evaporates, absorbs heat, and condenses into 95°C hot water; Step 5: After the hot water is deoxygenated and pH-adjusted through the closed-loop water system, it is pressurized by a high-temperature water pump and re-transported to the top evaporator of the tower, with the pH value maintained at 9.2-9.8; Among them, the gas phase components are monitored in real time. When the light component content is greater than 18 vol%, the reflux flow rate is automatically increased to 38 t / h. When the heavy component content is greater than 5 vol%, the reflux flow rate is reduced to 35 t / h.

[0014] Compared with the prior art, the present invention has the following beneficial effects.

[0015] The overhead evaporator couples the condensation of the 125°C gaseous material at the top of the de-lightening tower with the evaporation of hot water in the hot water evaporation section, achieving a cascaded utilization of the gas-phase latent heat. Compared to traditional air-cooling processes, this achieves a high heat recovery rate and avoids additional cooling energy consumption, significantly reducing the overall system energy consumption.

[0016] A three-stage steam compressor is used to compress 0.15MPa low-pressure steam step by step into 1.2MPa high-pressure steam, reducing the energy consumption of steam pressure increase while ensuring the stability of the output steam temperature to meet the stable heating demand of the bottom condenser.

[0017] The inner cylinder and the grid plate form a radial fan-shaped flow channel, which, combined with the high-temperature material in the reboiler, realizes rapid condensation of high-pressure steam. The unique flow channel layout increases the heat exchange area, avoids local overheating and coking, extends the continuous operation cycle of the equipment, and has high heat exchange efficiency.

[0018] The pH adjustment tank's three-stage compartments, the first compartment, the second compartment, and the third compartment, treat hot water in stages to achieve deep deoxygenation and precise pH adjustment. Combined with a high-temperature water pump to increase the pressure to 1.2MPa, it effectively suppresses system corrosion and scaling risks, ensuring the long-term stability of the water circulation.

[0019] The intelligent control system monitors gas phase components in real time based on a gas chromatograph, dynamically adjusts the reflux rate of the light removal tower, and controls the tower top temperature fluctuation to ≤±1°C, thus solving the lag problem of traditional manual adjustment and ensuring smooth and efficient operation of the separation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the overall structure of the present invention; Figure 2 for Figure 1 A schematic diagram of the structure at center A; Figure 3 Schematic diagram of the closed-loop water system structure in the present invention; Figure 4 Schematic diagram of the structure of the tower top evaporator in the present invention; Figure 5 for Figure 4 Schematic diagram of the cross section of the structure shown; Figure 6 Schematic diagram of the bottom condenser structure of the present invention; Figure 7 for Figure 6 Schematic diagram of the cross section of the structure shown; Figure 8 for Figure 6 A schematic diagram of a partial cross section of the structure shown; Figure 9 It is a partial cross-sectional schematic diagram of the steam compressor in the present invention; Figure 10 This is a schematic diagram of the internal structure of the pH adjustment tank in the present invention; Figure 11 The present invention provides a schematic flow chart of the steps of the recovery method.

[0021] Figure: 1, degassing tower; 11, gas phase conveying pipe; 2, tower top evaporator; 201, outer cylinder; 202, heat exchange tube; 203, gas phase condensation section; 204, hot water evaporation section; 205, conical transition section; 206, spiral baffle; 207, spiral conveyor; 21, material inlet; 22, low-pressure steam outlet; 23, hot water inlet; 24, U-shaped liquid seal pipe; 25, return water inlet; 3, steam compressor; 31, high-pressure steam pipe; 4, tower bottom condenser; 401, outer tank; 402, inner cylinder; 403, condensation tube bundle; 404, ring Shell; 405, guide port; 406, grid plate; 407, fan-shaped flow channel; 41, steam inlet; 42, condensate outlet; 43, installation cavity; 5, closed-loop water system; 51, circulation pipe; 501, expansion tank; 502, deaerator; 503, high-temperature water pump; 504, pH adjustment tank; 505, stirring component; 506, pH meter; 507, first compartment; 508, second compartment; 509, third compartment; 6, reboiler; 7, gas chromatograph; 71, pressure transmitter; 72, electric control valve; 73, temperature sensor. DETAILED DESCRIPTION

[0022] The embodiments of the present invention are described below with reference to the accompanying drawings.

[0023] In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms, "connection", and "installation" should be understood in a broad sense. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. In addition, "communication" can be a direct connection or an indirect connection through an intermediate medium. Here, "fixed" means that the two are connected to each other and the relative position relationship after connection remains unchanged. The directional terms mentioned in the embodiments of the present invention, such as "inside", "outside", "top", "bottom", etc., are only reference to the directions of the accompanying drawings. Therefore, the directional terms used are for better and clearer explanation and understanding of the embodiments of the present invention, rather than indicating or implying 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 a limitation on the embodiments of the present invention.

[0024] In the embodiments of the present invention, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Therefore, features defined as "first" or "second" may explicitly or implicitly include one or more of the features.

[0025] In the embodiments of the present invention, "and / or" is simply a description of the association relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone. Furthermore, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0026] References to "one embodiment" or "some embodiments" in this specification mean that a particular feature, structure, or characteristic described in connection with that embodiment is included in one or more embodiments of the present invention. Thus, phrases such as "in one embodiment," "in some embodiments," "in other embodiments," and "in yet other embodiments" appearing in various places in this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "including," "comprising," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0027] See also Figures 1-10The present invention provides a heat energy recovery device for separating nine-carbon heavy aromatics, comprising a light-removing tower 1, a tower top evaporator 2, a steam compressor 3, a tower bottom condenser 4 and a closed-loop water system 5. The gas phase outlet at the top of the light-removing tower 1 is connected to the material inlet 21 on the tower top evaporator 2 through a gas phase conveying pipe 11, the low-pressure steam outlet 22 at the top of the tower top evaporator 2 is connected to the air inlet end of the steam compressor 3 through a pipeline, the air outlet end of the steam compressor 3 is connected to the steam inlet 41 on the tower bottom condenser 4 through a high-pressure steam pipe 31, and the condensed water outlet 42 on the tower bottom condenser 4 is connected to the hot water inlet 23 on the tower top evaporator 2 through the closed-loop water system 5 to form a steam and water circulation loop.

[0028] The gas phase outlet at the top of the light-removal tower 1 transports the gaseous material to the material inlet 21 of the top evaporator 2 through the gas phase conveying pipe 11. The low-pressure steam outlet 22 at the top of the top evaporator 2 transports the generated low-pressure steam to the air inlet end of the steam compressor 3. The high-pressure steam compressed by the steam compressor 3 enters the steam inlet 41 of the bottom condenser 4 through the high-pressure steam pipe 31. The liquid condensed in the bottom condenser 4 flows out from the condensed water outlet 42 and is transported to the hot water inlet 23 of the top evaporator 2 through the closed-loop water system 5. In this way, a circulation loop of steam and water is formed, realizing the circulation flow and energy conversion of materials during the heat energy recovery process.

[0029] like Figure 4 and Figure 5 As shown, the top evaporator 2 includes an outer tube 201, a heat exchange tube 202 and a spiral baffle 206. The heat exchange tube 202 is fixed in the outer tube 201, and the heat exchange tube 202 is a gas phase condensation section 203 and a hot water evaporation section 204 from top to bottom, and the gas phase condensation section 203 and the hot water evaporation section 204 are connected through a conical transition section 205. The low-pressure steam outlet 22 is connected to the heat exchange tube 202, and the hot water inlet 23 is connected to the gas phase condensation section 203. The spiral baffle 206 is wound around the outside of the gas phase condensation section 203, and the outer edge is tightly fitted with the inner wall of the outer tube 201 to form a spiral conveying path 207. The material inlet 21 extends through the outer tube 201 and is connected to the top of the spiral conveying path 207. The return water port 25 at the bottom of the outer tube 201 is connected to the top of the de-light tower 1 through a U-shaped liquid seal tube 24.

[0030] In the tower top evaporator 2, a heat exchange tube 202 is fixed in the outer cylinder 201. The heat exchange tube 202 is connected from top to bottom with the gas phase condensation section 203 and the hot water evaporation section 204 through a tapered transition section 205. The hot water inlet 23 is connected with the gas phase condensation section 203 to input hot water. The material inlet 21 passes through the outer cylinder 201 and is connected with the top of the spiral conveyor 207. The spiral baffle 206 is wound around the outside of the gas phase condensation section 203 and the outer edge is attached to the inner wall of the outer cylinder 201 to form a spiral conveyor 207, so that the gas at the top of the de-light tower 1 The phase material enters the spiral conveying channel 207 from the material inlet 21 through the gas phase conveying pipe 11, condenses at the heat exchange pipe 202 to release latent heat, and the condensate returns to the top of the de-lightening tower 1 through the return water port 25 at the bottom of the outer cylinder 201 through the U-shaped liquid seal pipe 24. At the same time, the released latent heat is transferred to the hot water evaporation section 204 through the conical transition section 205, and the hot water input from the gas phase condensation section 203 to the hot water evaporation section 204 is evaporated into steam. The steam is output after connecting to the heat exchange pipe 202 through the low-pressure steam outlet 22, realizing heat energy recovery and material circulation.

[0031] like Figure 9 As shown, the steam compressor 3 is a three-stage Roots compressor having three impellers for progressive compression, thereby gradually increasing the pressure of the low-pressure steam.

[0032] like Figure 1 、 Figure 6 、 Figure 7 and Figure 8 As shown, the bottom of the light removal tower 1 is provided with a reboiler 6, and the bottom condenser 4 is integrated at the bottom of the reboiler 6. The bottom condenser 4 includes an outer tank body 401, an inner cylinder body 402, a condenser tube bundle 403 and an annular shell 404. The inner cylinder body 402 is coaxially fixed in the outer tank body 401, and the two are jointly provided with a mounting cavity 43 that passes vertically upward. The condenser tube bundle 403 is installed in the mounting cavity 43, and the top end extends through to the reboiler 6. The annular shell 404 surrounds the inner cylinder body 402. Arranged at the top of the outer tank body 401, the steam inlet 41 extends through the outer tank body 401 and is connected to the annular shell 404. A number of grid plates 406 are fixed on the outer wall of the inner cylinder 402. The grid plates 406 are radially distributed to form a number of vertically extending fan-shaped flow channels 407. A number of guide ports 405 are provided at the bottom of the annular shell 404. Each guide port 405 is connected to the fan-shaped flow channel 407 in a one-to-one correspondence. The condensate outlet 42 is connected to the bottom of the outer tank body 401.

[0033] High-pressure steam enters the outer tank body 401 through the steam inlet 41, and is diverted to the fan-shaped flow channel 407 through the guide port 405. The grid plate 406 increases the heat exchange area. The steam contacts the inner cylinder 402 and the condensation tube bundle 403 in the fan-shaped flow channel 407, and is heated by the liquid material in the reboiler 6 to evaporate and absorb heat to condense into 95°C hot water. The condensed water flows out from the condensed water outlet 42 to the closed-loop water system 5, realizing steam condensation and heat energy exchange.

[0034] Such as Figure 1 、 Figure 3 and Figure 10 As shown, the closed-loop water system 5 includes a circulation pipe 51, an expansion water tank 501, a deaerator 502, a high-temperature water pump 503 and a pH adjustment tank 504. One end of the circulation pipe 51 is connected to the condensate outlet 42, and the other end is connected to the hot water inlet 23. The expansion water tank 501, the deaerator 502, the high-temperature water pump 503 and the pH adjustment tank 504 are installed on the circulation pipe 51 in sequence, wherein the circulation pipe 51 is covered with a 50mm aluminum silicate insulation layer to reduce heat loss.

[0035] Among them, there are three compartments in the pH adjustment tank 504, namely the first compartment 507, the second compartment 508 and the third compartment 509 from bottom to top, with a volume ratio of 1:1:2. Each compartment is provided with a stirring component 505 and a pH meter 506. Among them, the first compartment 507 is filled with ammonia water, the second compartment 508 is filled with trisodium phosphate, and the third compartment 509 is a buffer chamber.

[0036] The pH adjustment tank 504 is provided with three compartments from bottom to top, namely a first compartment 507, a second compartment 508, and a third compartment 509 with a volume ratio of 1:1:2. The stirring component 505 and the pH meter 506 in each compartment work in conjunction with each other. The first compartment 507 is filled with ammonia water to adjust the pH value, the second compartment 508 is filled with trisodium phosphate to prevent scaling, and the third compartment 509 serves as a buffer chamber to stabilize the water flow. The 95°C hot water flowing out of the condensate outlet 42 passes through the circulation pipe 51, sequentially passes through the expansion tank 501, the deaerator 502 for deoxygenation, and is pressurized to 1.2 MPa by the high-temperature water pump 503. After graded treatment in the pH adjustment tank 504, it is returned to the top evaporator 2 through the hot water inlet 23, forming a closed water cycle.

[0037] In addition, the recovery device also includes an intelligent control system, which includes a DCS controller, a gas chromatograph 7, a pressure transmitter 71, an electric control valve 72 and a temperature sensor 73. The DCS controller and the gas chromatograph 7, the pressure transmitter 71, the electric control valve 72 and the temperature sensor 73 are respectively connected through an industrial bus. The gas chromatograph 7 is installed in the gas sampling port at the top of the de-light tower 1, the pressure transmitter 71 is integrated in the gas phase delivery pipe 11, the electric control valve 72 is assembled on the circulation pipe 51 and is located downstream of the high-temperature water pump 503, and the temperature sensor 73 is installed on the hot water inlet 23, and the detection end extends through the hot water inlet 23.

[0038] In the intelligent control system of this recovery device, the DCS controller is connected to the gas chromatograph 7, pressure transmitter 71, electric control valve 72 and temperature sensor 73 through the industrial bus. The gas chromatograph 7 is installed in the gas sampling port at the top of the light-removal tower 1 to monitor the gas phase components. The pressure transmitter 71 is integrated on the gas phase delivery pipe 11 for detecting the gas phase delivery parameters. The electric control valve 72 is assembled on the circulation pipe 51 and is located downstream of the high-temperature water pump 503 to monitor the circulating water status. The temperature sensor 73 is installed on the hot water inlet 23 and the detection end extends into the interior to monitor the hot water parameters. The DCS controller dynamically adjusts the reflux rate to 36.9±0.5t / h based on the gas phase composition data feedback from the gas chromatograph 7, controls the tower top temperature at 125±1℃, and realizes intelligent monitoring and parameter adjustment of the system.

[0039] like Figure 11 As shown, the present invention also provides a method for recovering heat energy for separating C9 aromatics, which specifically comprises the following steps: Step 1: The gaseous material at 125°C at the top of the light removal tower 1 is introduced into the top evaporator 2, condensed at the heat exchange tube 202 to release latent heat, and the condensate is returned to the light removal tower 1 through the U-shaped liquid seal tube 24; Step 2: The released latent heat is transferred to the hot water evaporation section 204 through the tapered transition section 205, evaporating the hot water in the hot water evaporation section 204 into low-pressure steam at 0.15 MPa (g) and 115°C. The water level in the hot water evaporation section 204 fluctuates by ±10 mm. Step 3: The low-pressure steam is compressed into 1.2 MPa (g) high-pressure steam through the steam compressor 3 in three stages; Step 4: The high-pressure steam enters the outer tank 401 and is condensed into 95°C hot water by the heat absorbed by the liquid material in the reboiler 6 during evaporation; Step 5: After the hot water is deoxygenated and pH-adjusted by the closed-loop water system 5, it is pressurized by the high-temperature water pump 503 and re-transported to the top evaporator 2, with the pH value maintained at 9.2-9.8; Among them, the gas phase components are monitored in real time. When the light component content is greater than 18 vol%, the reflux flow rate is automatically increased to 38 t / h. When the heavy component content is greater than 5 vol%, the reflux flow rate is reduced to 35 t / h.

[0040] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

Claims

1. A heat recovery device for separating C9 aromatic hydrocarbons, characterized by: It includes a light-removal tower (1), a tower top evaporator (2), a steam compressor (3), a tower bottom condenser (4) and a closed-loop water system (5); The gas phase outlet at the top of the light removal tower (1) is connected to the material inlet (21) on the top evaporator (2) via a gas phase delivery pipe (11); The low-pressure steam outlet (22) at the top of the tower top evaporator (2) is connected to the air inlet of the steam compressor (3) through a pipeline, and the air outlet of the steam compressor (3) is connected to the steam inlet (41) on the tower bottom condenser (4) through a high-pressure steam pipe (31); The condensed water outlet (42) on the bottom condenser (4) is connected to the hot water inlet (23) on the top evaporator (2) through the closed-loop water system (5) to form a steam and water circulation loop.

2. The heat recovery device for separating C9 aromatics according to claim 1, characterized in that: The tower top evaporator (2) comprises an outer cylinder (201), a heat exchange tube (202), and a spiral baffle (206); The heat exchange tube (202) is fixed in the outer cylinder (201), and the heat exchange tube (202) comprises a gas phase condensation section (203) and a hot water evaporation section (204) from top to bottom, and the gas phase condensation section (203) and the hot water evaporation section (204) are connected via a tapered transition section (205); The low-pressure steam outlet (22) is connected to the heat exchange pipe (202), and the hot water inlet (23) is connected to the gas phase condensation section (203); The spiral baffle (206) is wound around the outside of the gas phase condensation section (203), and the outer edge is tightly fitted with the inner wall of the outer cylinder (201), forming a spiral conveying path (207); The material inlet (21) extends through the outer cylinder (201) and is connected to the top of the spiral conveying channel (207); The water return port (25) provided at the bottom of the outer cylinder (201) is communicated with the top of the light removal tower (1) through a U-shaped liquid seal pipe (24).

3. The heat recovery device for separating C9 aromatics according to claim 2, characterized in that: The steam compressor (3) is a three-stage Roots compressor having three impellers for progressive compression.

4. The heat recovery device for separating C9 aromatics according to claim 1, characterized in that: The bottom of the light-removal tower (1) is provided with a reboiler (6), and the bottom condenser (4) is integrated at the bottom of the reboiler (6); The tower bottom condenser (4) comprises an outer tank body (401), an inner cylinder body (402), a condensation tube bundle (403) and an annular shell (404); The inner cylinder (402) is coaxially fixed in the outer tank (401), and both are provided with a mounting cavity (43) that passes vertically upwards; The condenser tube bundle (403) is installed in the installation cavity (43), and the top end extends through the reboiler (6); The annular shell (404) is arranged at the top of the outer tank body (401) around the inner cylinder (402); the steam inlet (41) extends through the outer tank body (401) and communicates with the annular shell (404); A plurality of grid plates (406) are fixed on the outer wall of the inner cylinder (402), and the grid plates (406) are radially distributed to form a plurality of vertically extending fan-shaped flow channels (407); The bottom of the annular shell (404) is provided with a plurality of guide ports (405), and each of the guide ports (405) is connected to the fan-shaped flow channel (407) in a one-to-one correspondence; The condensed water outlet (42) is in communication with the inner bottom of the outer tank body (401).

5. The heat recovery device for separating C9 aromatics according to claim 1, characterized in that: The closed-loop water system (5) includes a circulation pipe (51), an expansion water tank (501), a deaerator (502), a high-temperature water pump (503) and a pH adjustment tank (504); One end of the circulation pipe (51) is in communication with the condensed water outlet (42), and the other end is in communication with the hot water inlet (23); The expansion water tank (501), the deaerator (502), the high-temperature water pump (503) and the pH adjustment tank (504) are sequentially installed on the circulation pipe (51).

6. The heat recovery device for separating C9 aromatics according to claim 5, characterized in that: The pH adjustment tank (504) has three compartments, which are, from bottom to top, a first compartment (507), a second compartment (508), and a third compartment (509); Each compartment is provided with a stirring component (505) and a pH meter (506).

7. The heat recovery device for separating C9 aromatics according to claim 5, characterized in that: It also includes intelligent control systems; The intelligent control system includes a DCS controller, a gas chromatograph (7), a pressure transmitter (71), an electric regulating valve (72) and a temperature sensor (73); The DCS controller is connected to the gas chromatograph (7), the pressure transmitter (71), the electric regulating valve (72) and the temperature sensor (73) via an industrial bus. The gas chromatograph (7) is installed in the gas phase sampling port at the top of the light removal tower (1); The pressure transmitter (71) is integrated on the gas phase delivery pipe (11); The electric regulating valve (72) is mounted on the circulation pipe (51) and is located downstream of the high-temperature water pump (503); The temperature sensor (73) is mounted on the hot water inlet (23), and the detection end extends through the inside of the hot water inlet (23).

8. A method for recovering heat energy for separating C9 heavy aromatics, based on the heat energy recovery device for separating C9 heavy aromatics according to any one of claims 1 to 7, characterized in that: The following steps are involved: Step 1: introducing the gaseous material at 125°C at the top of the light removal tower (1) into the top evaporator (2), condensing it at the heat exchange tube (202) to release latent heat, and returning the condensate to the light removal tower (1) through the U-shaped liquid seal tube (24); Step 2: The released latent heat is transferred to the hot water evaporation section (204) through the conical transition section (205), evaporating the hot water in the hot water evaporation section (204) into low-pressure steam of 0.15 MPa and 115°C; Step 3: The low-pressure steam is compressed into 1.2 MPa high-pressure steam through the steam compressor (3) in three stages; Step 4: The high-pressure steam enters the outer tank (401) and is condensed into 95°C hot water by the heat absorbed by the liquid phase material in the reboiler (6) during evaporation; Step 5: After the hot water is deoxygenated and pH-adjusted through the closed-loop water system (5), it is pressurized by the high-temperature water pump (503) and re-transported to the top evaporator (2); Among them, the gas phase components are monitored in real time. When the light component content is greater than 18 vol%, the reflux flow rate is automatically increased to 38 t / h. When the heavy component content is greater than 5 vol%, the reflux flow rate is reduced to 35 t / h.

9. The heat energy recovery method for separating C9 aromatics according to claim 8, characterized in that: In step 2, the water level at the hot water evaporation section (204) fluctuates by ±10 mm.

10. The heat energy recovery method for separating C9 aromatics according to claim 8, characterized in that: In step five, the pH is maintained at 9.2-9.8.

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