Thermal energy utilization system of C3C4 mixed dehydrogenation unit

Abstract

The present invention discloses a thermal energy utilization system for a C3 / C4 mixed dehydrogenation device, relating to the technical field of thermal energy utilization. The system utilizes the heat generated by a heat pump compressor as a heat source for the propane tower reboiler and the sideline extraction material of C3 / C4 separation tower A, the heat from the aromatic solvent piping system as a heat source for the reboiler of C3 / C4 separation tower A, and the heat from the bottom material of C3 / C4 separation tower B as a heat source for heat exchange with the inlet material of C3 / C4 separation tower A. This system fully utilizes the excess heat of the dehydrogenation device, reduces steam consumption, and achieves energy conservation.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal energy utilization, and in particular to a thermal energy utilization system for a C3-C4 mixed dehydrogenation device. Background Art

[0002] The dehydrogenation of alkanes to olefins has always been a research hotspot in the petrochemical field. As an important chemical raw material, olefins are widely used in various fields such as plastics, rubber, and fine chemicals. Currently, many sets of alkane dehydrogenation to olefins units have been built at home and abroad.

[0003] Currently, propane dehydrogenation units for propylene production have excess capacity. To expand the downstream supply chain, some companies are choosing to convert propane dehydrogenation units into mixed C3 / C4 dehydrogenation units. The C3 / C4 mixed product must be separated into a C3 / C4 separation tower system and a propylene / propane separation tower system. This process requires a reboiler at the bottom of the tower to heat the material. During the conversion, traditional processes cannot repurpose the existing depropanizer for the converted C3 / C4 separation tower, necessitating a new C3 / C4 separation tower, which is a significant investment. Furthermore, using steam as a heat source to heat the material consumes a lot of energy. The heat source generated by the dehydrogenation unit itself, the heat pump compressor outlet and the aromatic solvent heat source, are relatively low in temperature and are generally cooled directly, resulting in high energy consumption. Summary of the Invention

[0004] The technical problem to be solved by the present invention is: to overcome the shortcomings of the existing technology and provide a heat energy utilization system for a C3C4 mixed dehydrogenation device, in which the heat generated by the heat pump compressor is used as the heat source for the propane tower reboiler and the side line extraction material of the C3C4 separation tower A, the heat of the aromatic hydrocarbon solvent pipeline system is used as the heat source for the reboiler of the C3C4 separation tower A, and the heat of the bottom material of the C3C4 separation tower B is used as the heat source for heat exchange with the inlet material of the C3C4 separation tower A, so as to fully utilize the surplus heat of the dehydrogenation device, reduce steam consumption, and achieve the purpose of energy saving.

[0005] The technical solution of the present invention is:

[0006] A heat energy utilization system for a C3 / C4 mixed dehydrogenation device comprises a C3 / C4 separation tower A, a C3 / C4 separation tower B and a propane tower, wherein the C3 / C4 separation tower A is connected with a C3 / C4 mixture feed pipeline, a tower top material discharge pipeline A and a reboiler A, and is connected to the C3 / C4 separation tower B through a tower bottom material discharge pipeline A, the C3 / C4 separation tower B is connected with a tower top material discharge pipeline B, a tower bottom material discharge pipeline B and a reboiler B, the C3 / C4 separation tower A and the C3 / C4 separation tower B are respectively connected to a condenser 1 through a tower top material discharge pipeline A and a tower top material discharge pipeline B, the condenser 1 is connected to a reflux tank through a pipeline, the reflux tank is respectively connected to the C3 / C4 separation tower A and the C3 / C4 separation tower B through a reflux pipeline, and is connected to the propane tower through a C3 material discharge pipeline; the propane tower is connected There are a tower top material discharge pipeline C, a tower bottom material discharge pipeline C and a reboiler C. The tower top material discharge pipeline C is connected to a first-stage inlet tank, which is connected to the first-stage inlet of the heat pump compressor through a pipeline, the first-stage outlet of the heat pump compressor is connected to the reboiler C through a heat source feed pipeline 1, and the reboiler C is connected to the reflux port of the propane tower through a heat source discharge pipeline 1; the carbon three and carbon four separation tower A is connected to the reboiler D through a side line extraction pipeline and a side line return pipeline, the second-stage outlet of the heat pump compressor is connected to the reboiler D through a heat source feed pipeline 2, the reboiler D is connected to the second-stage inlet tank through a heat source discharge pipeline 2, the second-stage inlet tank is connected to the propylene product outlet pipeline, and is connected to the second-stage inlet of the heat pump compressor through the tower top material discharge pipeline D, and the tower bottom material outlet is connected to the propane tower through a reflux pipeline.

[0007] Preferably, the C3-C4 mixture feed pipeline is connected to a heat exchanger, the bottom stream discharge pipeline B is connected to the heat source inlet of the heat exchanger, and the heat source outlet of the heat exchanger is connected to the C4 product pipeline.

[0008] Preferably, the heat source inlet of the reboiler A is connected to an aromatic solvent feed pipeline, and the heat source outlet is connected to an aromatic solvent discharge pipeline.

[0009] Preferably, a second condenser is connected to the aromatic solvent discharge pipeline.

[0010] Preferably, the aromatic solvent discharge pipeline is connected to the product gas compression unit of the dehydrogenation device.

[0011] Preferably, the heat source inlet of the reboiler B is connected to a steam feed pipeline, and the heat source outlet is connected to a steam condensate discharge pipeline.

[0012] Preferably, the heat source discharge pipeline 2 is connected to a condenser 3.

[0013] Preferably, a pump is connected to the tower bottom material discharge pipeline A.

[0014] Preferably, a pump is connected to the reflux pipeline between the reflux tank and the C3 / C4 separation tower A and the C3 / C4 separation tower B.

[0015] Preferably, the tower bottom material discharge pipeline C and the propylene product discharge pipeline are respectively connected to pumps.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] In the project of transforming propane dehydrogenation technology into C3C4 mixed dehydrogenation, the present invention divides the C3C4 separation tower into two tower systems: Tower A (reusing the original depropanizer) and Tower B (newly added). The heat generated by the heat pump compressor is used as the heat source for the propane tower reboiler and the side line extraction material of C3C4 separation tower A, the heat of the aromatic solvent pipe system is used as the reboiler heat source of C3C4 separation tower A, and the heat of the bottom material of C3C4 separation tower B is used as the heat source for heat exchange with the inlet material of C3C4 separation tower A. The above can fully utilize the surplus heat of the dehydrogenation device, reduce steam consumption, and achieve the purpose of energy saving. Taking a 660,000 tons / year C3C4 mixed dehydrogenation device of a certain device as an example, the technology of the present invention can save about 47t / h of low-pressure steam consumption and about 2,400t / h of circulating water consumption, creating an economic benefit of about 70 million / year. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of the heat energy utilization system of the C3-C4 mixed dehydrogenation device of Example 1 of the present invention.

[0019] Figure 2 It is a structural schematic diagram of the heat energy utilization system of the C3-C4 mixed dehydrogenation device of Comparative Example 1 of the present invention.

[0020] In the figure, 1. C3 / C4 separation tower A; 101. C3 / C4 mixture feed pipeline; 102. Top material discharge pipeline A; 103. Reboiler A; 104. Bottom material discharge pipeline A; 105. Side line extraction pipeline; 106. Side line return pipeline; 107. Reboiler D; 2. C3 / C4 separation tower B; 201. Top material discharge pipeline B; 202. Bottom material discharge pipeline B; 203. Reboiler B; 3. Propane tower; 301. Top material discharge pipeline C; 302. Bottom material discharge pipeline C; 303. Reboiler C; 4. First stage inlet tank; 5. Heat pump compressor ; 601, heat source feed pipeline one; 602, heat source discharge pipeline one; 7, condenser one; 8, reflux tank; 801, C3 material discharge pipeline; 901, heat source feed pipeline two; 902, heat source discharge pipeline two; 10, second-stage inlet tank; 1001, propylene product outlet pipeline; 1002, top material discharge pipeline D; 11, heat exchanger; 12, C4 product pipeline; 1301, aromatic solvent feed pipeline; 1302, aromatic solvent discharge pipeline; 14, condenser two; 1501, steam feed pipeline; 1502, steam condensate discharge pipeline; 16, condenser three; 17, pump. DETAILED DESCRIPTION

[0021] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention.

[0022] Example 1

[0023] like Figure 1As shown, the heat energy utilization system of the C3C4 mixed dehydrogenation device of this embodiment includes a C3C4 separation tower A1, a C3C4 separation tower B2 and a propane tower 3. The C3C4 separation tower A1 is connected to a C3C4 mixture feed pipeline 101, a tower top material discharge pipeline A102 and a reboiler A103, and is connected to the C3C4 separation tower B2 through a tower bottom material discharge pipeline A104, and the tower bottom material discharge pipeline A104 is connected to a pump 17; the C3C4 separation tower B2 is connected to a tower top material discharge pipeline B201, a tower bottom material discharge pipeline B202 and reboiler B203, C3C4 separation tower A1, C3C4 separation tower B2 are connected to condenser 7 through top material discharge pipeline A102, top material discharge pipeline B201 respectively, condenser 7 is connected to reflux tank 8 through pipeline, reflux tank 8 is connected to C3C4 separation tower A1 and C3C4 separation tower B2 through reflux pipeline respectively, pump 17 is connected to reflux pipeline, and is connected to propane tower 3 through C3 material discharge pipeline 801; propane tower 3 is connected to top material discharge pipeline C301, tower bottom material discharge pipeline C302, tower bottom material discharge pipeline B301. Pipeline C302 and reboiler C303, the bottom material discharge pipeline C302 is connected to a pump 17, the top material discharge pipeline C301 is connected to a first-stage inlet tank 4, the first-stage inlet tank 4 is connected to the first-stage inlet of the heat pump compressor 5 through a pipeline, the first-stage outlet of the heat pump compressor 5 is connected to the reboiler C303 through the heat source feed pipeline 601, and the reboiler C303 is connected to the reflux port of the propane tower 3 through the heat source discharge pipeline 602; the carbon three and carbon four separation tower A1 is connected to the reboiler D through the side line extraction pipeline 105 and the side line return pipeline 106. 107, the second-stage outlet of the heat pump compressor 5 is connected to the reboiler D107 through the second heat source feed pipeline 901, the reboiler D107 is connected to the second-stage inlet tank 10 through the second heat source discharge pipeline 902, the second heat source discharge pipeline 902 is connected to the condenser three 16, the second-stage inlet tank 10 is connected to the propylene product outlet pipeline 1001, the propylene product outlet pipeline 1001 is connected to the pump 17, and is connected to the second-stage inlet of the heat pump compressor 5 through the top material discharge pipeline D1002, and the bottom material outlet is connected to the propane tower 3 through the reflux pipeline.

[0024] Working principle:

[0025] The C3 / C4 mixture delivered from other units enters C3 / C4 separation tower A1. After separation, the bottoms are pressurized by pump 17 and then transported to C3 / C4 separation tower B2 for further separation. The bottoms of C3 / C4 separation tower B2 are transported to the outside as C4 product.

[0026] The top materials of the C3C4 separation tower A1 and the C3C4 separation tower B2 are condensed by the condenser 7 and then transported to the reflux tank 8. The materials in the reflux tank 8 are divided into two parts. One part is pressurized by the pump 17 and returned to the C3C4 separation tower A1 and the C3C4 separation tower B2 as reflux material; the other part is transported to the propane tower 3 for propane and propylene separation.

[0027] The bottoms of propane column 3 are the propane product, which is pressurized by pump 17 and then transported to other units within the dehydrogenation unit. The overhead material of propane column 3 is transported to the first-stage inlet tank 4 and then to the heat pump compressor 5 for further pressurization. The material at the first-stage outlet of heat pump compressor 5 enters the reboiler C303 of propane column 3, exchanges heat with the reboiled material at the bottom of propane column 3, and then returns to propane column 3 as reflux material.

[0028] The propylene product at the bottom of the second-stage inlet tank 10 is pressurized and transported to the off-site tank farm. The material at the top of the second-stage inlet tank 10 is pressurized by the heat pump compressor 5 before entering the reboiler D107 of the C3 / C4 separation tower A1. After heat exchange with the material drawn from the sideline of the C3 / C4 separation tower A1 (i.e., a C3 / C4 mixture), it enters condenser 3 16 for cooling. The cooled material then enters the second-stage inlet tank 10.

[0029] In this embodiment, heat exchanger 11 is connected to C3 / C4 mixture feed line 101, bottoms outlet line B is connected to the heat source inlet of heat exchanger 11, and the heat source outlet of heat exchanger 11 is connected to C4 product line 12. The C3 / C4 mixture first enters heat exchanger 11, exchanges heat with the C4 product being delivered to heat exchanger 11, and after being heated, is delivered to C3 / C4 separation tower A1. The C4 product is cooled in heat exchanger 11 and then delivered to the outside of the tower.

[0030] Meanwhile, the heat source inlet of reboiler A103 is connected to aromatic solvent feed line 1301, and the heat source outlet is connected to aromatic solvent discharge line 1302. Aromatic solvent discharge line 1302 is connected to condenser 2 14, which is also connected to the product gas compression unit of the dehydrogenation unit. The heat source inlet of reboiler B203 is connected to steam feed line 1501, and the heat source outlet is connected to steam condensate discharge line 1502. Aromatic solvent delivered from other units within the dehydrogenation unit enters reboiler A103, exchanges heat with the reboiled material at the bottom of C3C4 separation tower A1, and then enters condenser 2 14 for cooling. After cooling, it returns to the original unit for continued use.

[0031] Comparative Example 1

[0032] like Figure 2As shown, the thermal energy utilization system of the C3 / C4 mixed dehydrogenation device of Comparative Example 1 includes a C3 / C4 separation tower A1 and a propane tower 3, and the C3 / C4 separation tower A1 is connected to a C3 / C4 mixture feed pipeline 101, a tower top material discharge pipeline A102, a tower bottom material discharge pipeline A104 and a reboiler A103; the C3 / C4 separation tower A1 is connected to a condenser 7 through a tower top material discharge pipeline A102, the condenser 7 is connected to a reflux tank 8 through a pipeline, the reflux tank 8 is connected to the C3 / C4 separation tower A1 through a reflux pipeline, a pump 17 is connected to the reflux pipeline, and the C3 / C4 material discharge pipeline 801 is connected to the propane tower 3; the condenser 7 is connected to a circulating water feed pipeline and a circulating water discharge pipeline; the heat source inlet of the reboiler A103 is connected to a steam feed pipeline 1501, and the heat source outlet is connected to a steam condensate discharge pipeline 1502. The C3-C4 mixture feed pipeline 101 is connected to the heat exchanger 11, the bottom stream discharge pipeline A is connected to the heat source inlet of the heat exchanger 11, and the heat source outlet of the heat exchanger 11 is connected to the C4 product pipeline 12.

[0033] The propane tower 3 is connected to a tower top material discharge pipeline C301, a tower bottom material discharge pipeline C302 and a reboiler C303. The tower bottom material discharge pipeline C302 is connected to a pump 17. The tower top material discharge pipeline C301 is connected to a first section inlet tank 4. The first section inlet tank 4 is connected to a first section inlet of a heat pump compressor 5 through a pipeline. The first section outlet of the heat pump compressor 5 is connected to the reboiler C303 through a heat source feed pipeline 601. The reboiler C303 is connected to the reflux port of the propane tower 3 through a heat source discharge pipeline 602. The second-stage outlet of the pump compressor 5 is connected to the second-stage inlet tank 10 through the second heat source feed pipeline 901, and the second heat source feed pipeline 901 is connected to the third condenser 16, and the third condenser 16 is connected to the circulating water feed pipeline and the circulating water discharge pipeline; the second-stage inlet tank 10 is connected to the propylene product outlet pipeline 1001, and the propylene product outlet pipeline 1001 is connected to the pump 17, and is connected to the second-stage inlet of the heat pump compressor 5 through the top material discharge pipeline D1002, and the bottom material outlet is connected to the propane tower 3 through the reflux pipeline.

[0034] Working principle:

[0035] The C3-C4 mixture delivered from other units first exchanges heat with the C4 product exiting the bottom of C3-C4 separation tower A1 before entering C3-C4 separation tower A1. After separation, the bottoms, as the C4 product, exchange heat with the C3-C4 mixture, cool, and then are transported out of the tower. The overhead material from C3-C4 separation tower A1 is condensed in condenser 7 and transported to reflux tank 8. The material in reflux tank 8 is divided into two parts. One part is pressurized by pump 17 and returned to C3-C4 separation tower A1 as reflux material, while the other part is transported to propane tower 3 for propane and propylene separation.

[0036] The bottom material of propane tower 3 is the propane product, which is pressurized by pump 17 and then transported to other units within the dehydrogenation unit. The overhead material of propane tower 3 is transported to the first-stage inlet tank 4 and then to the heat pump compressor 5 for further pressurization. The output material of the first-stage outlet of heat pump compressor 5 enters the reboiler C303 of propane tower 3, exchanges heat with the reboiled material at the bottom of propane tower 3, and then returns to propane tower 3 as reflux material. A portion of the propylene product at the bottom of the second-stage inlet tank 10 is pressurized and transported to the off-site tank farm, while the remaining portion is refluxed to propane tower 3. The overhead material of second-stage inlet tank 10 is pressurized by the heat pump compressor 5, cooled by condenser 3 16, and then returned to the second-stage inlet tank 10.

[0037] The steam and circulating water consumption of the heat energy utilization system of Example 1 and Comparative Example 1 are shown in Table 1:

[0038] Table 1 Steam and circulating water consumption of heat energy utilization system of Example 1 and Comparative Example 1

[0039] Comparative Example 1 Example 1 Save energy Steam t / h 77 30 47 Circulating water t / h 9400 7000 2400

[0040] As can be seen from Table 1, the heat energy utilization system of Example 1 is adopted, and the C3C4 separation tower is divided into two tower systems, Tower A (reusing the original depropanizer 3) and Tower B (newly added), and the heat generated by the heat pump compressor 5 is used as the heat source for the reboiler of the propane tower 3 and the side line of the C3C4 separation tower A1, respectively. The heat of the aromatic solvent pipe system is used as the reboiler heat source of the C3C4 separation tower A1, and the heat of the bottom material of the C3C4 separation tower B2 is used as a heat source for heat exchange with the inlet material of the C3C4 separation tower A1. The above can make full use of the surplus heat of the dehydrogenation unit, reduce steam consumption, and achieve the purpose of energy saving.

Claims

1. A thermal energy utilization system for a C3 / C4 mixed dehydrogenation device, characterized in that: The invention comprises a C3 / C4 separation tower A (1), a C3 / C4 separation tower B (2) and a propane tower (3), wherein the C3 / C4 separation tower A (1) is connected to a C3 / C4 mixture feed pipeline (101), a tower top material discharge pipeline A (102) and a reboiler A (103), and is connected to the C3 / C4 separation tower B (2) through a tower bottom material discharge pipeline A (104), and the C3 / C4 separation tower B (2) is connected to a tower top material discharge pipeline B (201), a tower bottom material discharge pipeline B (202) and a reboiler A (103). Reboiler B (203), C3 / C4 separation tower A (1), C3 / C4 separation tower B (2) are connected to condenser 1 (7) via tower top material discharge pipeline A (102) and tower top material discharge pipeline B (201), respectively; condenser 1 (7) is connected to reflux tank (8) via pipeline; reflux tank (8) is connected to C3 / C4 separation tower A (1) and C3 / C4 separation tower B (2) via reflux pipeline, and is connected to propane tower (3) via C3 material discharge pipeline (801); The propane tower (3) is connected to a tower top material discharge pipeline C (301), a tower bottom material discharge pipeline C and a reboiler C (303); the tower top material discharge pipeline C (301) is connected to a first-stage inlet tank (4); the first-stage inlet tank (4) is connected to a first-stage inlet of a heat pump compressor (5) through a pipeline; the first-stage outlet of the heat pump compressor (5) is connected to the reboiler C (303) through a heat source feed pipeline (601); and the reboiler C (303) is connected to the reflux port of the propane tower (3) through a heat source discharge pipeline (602); The C3 / C4 separation tower A (1) is connected to a reboiler D (107) via a side line extraction line (105) and a side line return line (106); the second stage outlet of the heat pump compressor (5) is connected to the reboiler D (107) via a second heat source feed line (901); the reboiler D (107) is connected to a second stage inlet tank (10) via a second heat source discharge line (902); the second stage inlet tank (10) is connected to a propylene product outlet line (1001) and is connected to the second stage inlet of the heat pump compressor (5) via a tank top material discharge line D (1002); and the tank bottom material outlet is connected to a propane tower (3) via a reflux line. The C3 / C4 mixture feed pipeline (101) is connected to a heat exchanger (11), the bottom stream discharge pipeline B is connected to the heat source inlet of the heat exchanger (11), and the heat source outlet of the heat exchanger (11) is connected to a C4 product pipeline (12); The heat source inlet of the reboiler A (103) is connected to an aromatic solvent feed pipeline (1301), and the heat source outlet is connected to an aromatic solvent discharge pipeline (1302).

2. The thermal energy utilization system of the C3-C4 mixed dehydrogenation device according to claim 1, characterized in that: The aromatic solvent discharge pipeline (1302) is connected to a second condenser (14).

3. The heat energy utilization system of the C3-C4 mixed dehydrogenation device according to claim 2, characterized in that: The aromatic solvent discharge pipeline (1302) is connected to the product gas compression unit of the dehydrogenation device.

4. The thermal energy utilization system of the C3 / C4 mixed dehydrogenation device according to claim 1, characterized in that: The heat source inlet of the reboiler B (203) is connected to a steam feed pipeline (1501), and the heat source outlet is connected to a steam condensate discharge pipeline (1502).

5. The heat energy utilization system of the C3-C4 mixed dehydrogenation device according to claim 1, characterized in that: The heat source discharge pipeline 2 (902) is connected to the condenser 3 (16).

6. The thermal energy utilization system of the C3 / C4 mixed dehydrogenation device according to claim 1, characterized in that: The tower bottom material discharge pipeline A (104) is connected to a pump (17).

7. The heat energy utilization system of the C3-C4 mixed dehydrogenation device according to claim 1, characterized in that: A pump (17) is connected to the reflux pipeline between the reflux tank (8) and the C3 / C4 separation tower A (1) and the C3 / C4 separation tower B (2).

8. The heat energy utilization system of the C3-C4 mixed dehydrogenation device according to claim 1, characterized in that: The tower bottom material discharge pipeline C and the propylene product outlet pipeline (1001) are respectively connected to a pump (17).

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