Benzene hydrogenation preheating distillation tower structure capable of efficiently recycling tower bottom heat

Abstract

The utility model provides a benzene hydrogenation preheating distillation tower structure capable of efficiently recycling tower bottom heat, which comprises a pre-distillation tower and a heat exchange device, the pre-distillation tower comprises a tower top and a tower bottom, the tower top is provided with a tower top discharge port, the tower top is provided with a first cooler, the first cooler is provided with a feed port and a discharge port, and the tower bottom is provided with a second cooler. A tower top discharge hole is communicated with a feeding hole in the first cooler through a pipeline; a reflux device is arranged outside the pre-distillation tower, an inlet and an outlet are formed in the reflux device, and the inlet of the reflux device is communicated with the discharge hole in the first cooler through a pipeline; the heat exchange device comprises a first heat exchange inlet, a second heat exchange inlet, a first heat exchange outlet and a second heat exchange outlet, and the first heat exchange inlet of the heat exchange device is connected with an outlet of the reflux device through a pipeline. And the heat utilization efficiency is improved, and meanwhile, the prior art is improved conveniently.

Description

Technical Field

[0001] The utility model relates to the field of benzene hydrogenation, in particular to a structure of a benzene hydrogenation pre-distillation tower with efficient recycling of bottom heat. Background Art

[0002] The process technologies involved in benzene hydrogenation mainly include hydrotreating and extractive distillation. During operation, crude benzene first undergoes a hydrogenation reaction and a desulfurization step in a stabilizer tower to obtain hydrogenated oil. Subsequently, the hydrogenated oil enters a pre-distillation tower for further processing.

[0003] The overhead fraction of the pre-distillation tower, after being cooled by a cooler, is introduced into a reflux tank, and a reflux pump transports it to the extraction process to participate in subsequent extraction operations. At the same time, the mixed benzene produced at the bottom of the pre-distillation tower is transported by a bottom pump and undergoes cooling treatment by a bottom cooler, and finally is sent to a storage tank area for storage.

[0004] During normal production, the temperature of the mixed benzene at the bottom of the pre-distillation tower needs to be maintained at about 155 - 158 °C, and the storage temperature of the mixed benzene in the storage tank area of the storage tank area is usually maintained at 30 - 50 °C. It must be cooled before entering the storage tank area. After the overhead fraction of the pre-distillation tower enters the reflux tank through the cooler, the temperature is usually about 50 °C. In the extraction process, a higher temperature is required. Appropriately increasing the temperature of the extraction feed helps to reduce the usage amount of hot oil in the extraction tower. In the prior art, the mixed benzene is often cooled separately and the overhead fraction is preheated. The overhead fraction and the mixed benzene are not subjected to heat recycling, and the utilization efficiency of the heat generated during production is relatively low, resulting in a large load on the overhead cooler and also increasing the cooling water consumption during production, leading to a higher production cost. Summary of the Utility Model

[0005] In order to solve the problem of relatively low utilization efficiency of the heat generated during production in the background art, the utility model proposes a structure of a benzene hydrogenation pre-distillation tower with efficient recycling of bottom heat.

[0006] The technical solution of the utility model is: including a pre-distillation tower and a heat exchange device.

[0007] The pre-distillation tower includes a top and a bottom. An overhead discharge port is provided at the top of the tower. A first cooler is provided outside the pre-distillation tower. The first cooler is provided with a feed port and a discharge port. The overhead discharge port is communicated with the feed port on the first cooler through a pipeline.

[0008] A reflux device is provided outside the pre-distillation tower. The reflux device is provided with an inlet and an outlet. The inlet of the reflux device is communicated with the discharge port on the first cooler through a pipeline.

[0009] The heat exchange device includes a first heat exchange inlet, a second heat exchange inlet, a first heat exchange outlet and a second heat exchange outlet. The first heat exchange inlet of the heat exchange device is connected to the outlet of the reflux device through a pipeline, and the second heat exchange inlet of the heat exchange device communicates with the bottom of the pre-distillation column;

[0010] The first heat exchange outlet of the heat exchange device is connected to the feed inlet of the external extraction column through a pipeline;

[0011] The second heat exchange outlet of the heat exchange device communicates with the feed inlet of the storage device.

[0012] Preferably, the reflux device includes a reflux tank and a reflux pump. The reflux tank includes an inflow port and a reflux port. The inflow port of the reflux tank is connected to the discharge port on the first cooler through a pipeline. The reflux pump is arranged outside the reflux tank, and a pipeline is connected between the reflux port of the reflux tank and the feed inlet of the reflux pump. The discharge port of the reflux pump is connected to the first heat exchange port of the heat exchange device through a pipeline.

[0013] Preferably, the heat exchange device includes a shell-and-tube heat exchanger and a first heat exchange pipeline. The first heat exchange inlet and the first heat exchange outlet on the shell-and-tube heat exchanger are connected through the first heat exchange pipeline. The fluid in the first heat exchange pipeline and the fluid in the shell exchange heat in the shell-and-tube heat exchanger.

[0014] Preferably, a bottom discharge port is provided at the bottom of the pre-distillation column. The bottom discharge port of the pre-distillation column is connected to the second heat exchange inlet on the shell-and-tube heat exchanger through a pipeline;

[0015] A bottom pump is provided on the pipeline connecting the bottom discharge port of the pre-distillation column and the second heat exchange inlet on the shell-and-tube heat exchanger.

[0016] Preferably, the storage device includes a storage tank and a second cooler. A storage port is provided on the storage tank, and a second cooler is arranged outside the storage tank. The storage port of the storage tank and the discharge port on the second cooler are connected through a pipeline. A cooling feed port is provided on the second cooler, and the cooling feed port of the second cooler is connected to the second heat exchange outlet of the shell-and-tube heat exchanger through a pipeline.

[0017] Advantages of the present utility model: The low-temperature fraction produced at the top of the column and the mixed benzene produced at the bottom of the column can be heat-exchanged through the heat exchange device, so that the low-temperature fraction is pre-heated before extraction and the mixed benzene is pre-cooled before storage. At the same time, the structure of the heat exchange device is relatively simple, only a shell-and-tube heat exchanger and a heating pipeline, which is convenient for transforming the structure of the pre-heating distillation column in the prior art, and the production cost and transformation cost are both relatively low. Description of the Drawings

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0019] Figure 1 It is a schematic diagram of the main structure of Embodiment 1;

[0020] Figure 2 It is a schematic diagram of the working process.

[0021] In the figure, 1 is a pre-distillation column, 2 is a first cooler, 3 is a reflux drum, 4 is a reflux pump, 5 is a shell-and-tube heat exchanger, 6 is a bottom pump, 7 is a second cooler, and 8 is a storage tank. Specific embodiments

[0022] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0023] Embodiment 1: The purpose of this embodiment is to propose a benzene hydrogenation pre-distillation column structure for efficient recycling of bottom heat.

[0024] According to From Figure 1 to Figure 2 as shown, it includes a pre-distillation column 1 and a heat exchange device.

[0025] The pre-distillation column 1 includes a top and a bottom. A top discharge port is provided at the top of the column. A first cooler 2 is provided outside the pre-distillation column 1. The first cooler 2 is provided with a feed port and a discharge port. The top discharge port of the pre-distillation column 1 is connected to the feed port on the first cooler 2 through a pipeline.

[0026] A reflux device is provided outside the pre-distillation column 1. The reflux device is provided with an inlet and an outlet. The reflux device includes a reflux drum 3 and a reflux pump 4. The reflux drum 3 includes an inflow port and a reflux port. The reflux drum 3 can also be selected as a reflux tank. Both the reflux drum 3 and the reflux tank are prior arts. The inflow port of the reflux drum 3 is connected to the discharge port on the first cooler 2 through a pipeline. The reflux pump 4 is provided outside the reflux drum 3. A pipeline connection is provided between the reflux port of the reflux drum 3 and the feed inlet of the reflux pump 4. The reflux pump 4 is used to draw out the overhead fraction of the pre-distillation column from the reflux drum 3.

[0027] The heat exchange device includes a first heat exchange inlet, a second heat exchange inlet, a first heat exchange outlet, and a second heat exchange outlet. The heat exchange device includes a shell-and-tube heat exchanger 5, a first heat exchange pipeline, and a second heat exchange pipeline. The outlet of the reflux pump 4 is connected to the first heat exchange port of the shell-and-tube heat exchanger 5 through a pipeline.

[0028] The bottom of the pre-distillation column 1 is provided with a bottom discharge port. The bottom discharge port of the pre-distillation column 1 is connected to the second heat exchange inlet on the shell-and-tube heat exchanger 5 through a pipeline. A bottom pump 6 is provided on the pipeline connecting the bottom discharge port of the pre-distillation column 1 and the second heat exchange inlet on the shell-and-tube heat exchanger 5. The bottom pump 6 is used to pump out the mixed benzene at the bottom and send it into the shell-and-tube heat exchanger 5.

[0029] The second heat exchange outlet of the shell-and-tube heat exchanger 5 is communicated with the inlet of the storage device. The storage device includes a storage tank 8 and a second cooler 7. A storage port is provided on the storage tank 8. A second cooler 7 is provided outside the storage tank 8. The storage port of the storage tank 8 and the outlet of the second cooler 7 are connected through a pipeline. A cooling feed port is provided on the second cooler 7. The cooling feed port of the second cooler 7 is communicated with the second heat exchange outlet of the shell-and-tube heat exchanger 5 through a pipeline.

[0030] The heat exchange device includes a shell-and-tube heat exchanger (5) and a first heat exchange pipeline. The first heat exchange inlet and the first heat exchange outlet on the shell-and-tube heat exchanger (5) are connected through the first heat exchange pipeline. The fluid in the first heat exchange pipeline and the fluid in the shell exchange heat in the shell-and-tube heat exchanger (5). The top fraction flows in the first heat exchange pipeline, and the mixed benzene flows in the shell of the shell-and-tube heat exchanger (5). During production, the temperature of the top fraction is about 50°C after being treated by the first cooler 2, while the temperature of the mixed benzene before cooling is about 155°C - 158°C. The mixed benzene and the top fraction exchange heat in the shell-and-tube heat exchanger 5, the temperature of the mixed benzene decreases, and the temperature of the top fraction increases.

[0031] The first heat exchange outlet of the shell-and-tube heat exchanger 5 is communicated with the inlet of the external extraction column through a pipeline.

[0032] Both the reflux pump 4 and the bottom pump 6 are connected to the control panel for control.

[0033] The first cooler 2 and the second cooler 7 can be selected as water-cooled coolers.

[0034] Working principle: The hydrogenated oil produced by the crude benzene through the hydrogenation reaction and the stable tower desulfurization steps is sent into the pre-distillation column 1. After the pre-distillation column 1 is processed, top steam is produced at the top and bottom mixed benzene is produced at the bottom.

[0035] The overhead vapor is withdrawn from the top of the column by the reflux pump 4 and sent to the first cooler 2 for cooling. The temperature of the overhead vapor is reduced to 50 °C, and then the overhead vapor is sent to the reflux drum 3, where the low-temperature fraction at the top of the column is formed. The low-temperature fraction is finally sent to the shell-and-tube heat exchanger 5.

[0036] The mixed benzene at the bottom of the column is generally at 155 °C - 158 °C. The mixed benzene is withdrawn by the bottom pump 6 and then sent to the shell-and-tube heat exchanger 5.

[0037] The low-temperature fraction and the mixed benzene exchange heat in the shell-and-tube heat exchanger 5. The temperature of the low-temperature fraction rises, completing the preheating before extraction, while the temperature of the mixed benzene becomes lower, causing its temperature to be reduced in advance before entering the second cooler 7, reducing the load on the second cooler 7.

[0038] The low-temperature fraction that has completed heat exchange is sent to the next process for extraction. The mixed benzene that has completed heat exchange is sent to the second cooler 7 for secondary cooling to reduce the temperature of the mixed benzene to 30 °C to 50 °C to meet the temperature requirements of the storage tank 8. Then, the mixed benzene that has completed secondary cooling is sent to the storage tank 8.

[0039] Thus, the heat of the mixed benzene at the bottom of the column can be effectively utilized to participate in the heat cycle, enabling the mixed benzene to be cooled in advance while preheating the low-temperature fraction before extraction. This reduces the amount of hot oil used in the extraction column and also reduces the load on the second cooler 7, thereby reducing production costs. At the same time, the installed heat exchange device has a simple structure, only including the shell-and-tube heat exchanger 5 and heat exchange tubes, and the rest of the structure is the common structure of the existing technology, facilitating the transformation of the currently used benzene hydrogenation preheating distillation column and installing the heat exchange device on its basis.

[0040] For those skilled in the art, it is obvious that the present utility model is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or basic characteristics of the present utility model. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present utility model is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be encompassed within the present utility model. Any reference signs in the claims should not be regarded as limiting the claimed rights.

Claims

1. A benzene hydrogenation preheating distillation tower structure with efficient recycling of tower bottom heat, characterized in that: It comprises a pre-distillation tower (1) and a heat exchange device, The pre-distillation tower (1) comprises a tower top and a tower bottom, a tower top discharge port is provided on the tower top, a first cooler (2) is provided outside the pre-distillation tower (1), a feed port and a discharge port are provided on the first cooler (2), and the tower top discharge port is connected to the feed port on the first cooler (2) through a pipeline; A reflux device is provided outside the pre-distillation tower (1), and an inlet and an outlet are provided on the reflux device. The inlet of the reflux device is connected to the discharge port on the first cooler (2) through a pipeline; The heat exchange device comprises a first heat exchange inlet, a second heat exchange inlet, a first heat exchange outlet and a second heat exchange outlet, the first heat exchange inlet of the heat exchange device is connected to the outlet of the reflux device via a pipeline, and the second heat exchange inlet of the heat exchange device is connected to the bottom of the pre-distillation tower (1); The first heat exchange outlet of the heat exchange device is connected to the feed inlet of the external extraction tower through a pipeline; The second heat exchange outlet of the heat exchange device is communicated with the material inlet of the material storage device.

2. The benzene hydrogenation preheating distillation tower structure with efficient bottom heat recycling according to claim 1, characterized in that: The reflux device comprises a reflux groove (3) and a reflux pump (4), the reflux groove (3) comprising an inlet and a reflux port, the inlet of the reflux groove (3) being connected to the outlet of the first cooler (2) via a pipeline, the reflux pump (4) being arranged outside the reflux groove (3), the reflux port of the reflux groove (3) being connected to the inlet of the reflux pump (4) via a pipeline, and the outlet of the reflux pump (4) being connected to the first heat exchange port of the heat exchange device via a pipeline.

3. The benzene hydrogenation preheating distillation tower structure with efficient bottom heat recycling according to claim 2, characterized in that: The heat exchange device comprises a shell-and-tube heat exchanger (5) and a first heat exchange pipeline, wherein a first heat exchange inlet and a first heat exchange outlet on the shell-and-tube heat exchanger (5) are connected via the first heat exchange pipeline, and the fluid in the first heat exchange pipeline and the fluid in the shell and tube exchange heat in the shell-and-tube heat exchanger (5).

4. The benzene hydrogenation preheating distillation tower structure with efficient bottom heat recycling according to claim 3, characterized in that: The bottom of the pre-distillation tower (1) is provided with a bottom discharge port, and the bottom discharge port of the pre-distillation tower (1) is connected to the second heat exchange inlet on the shell-and-tube heat exchanger (5) through a pipeline; A bottom pump (6) is provided on the pipeline connecting the bottom discharge port of the pre-distillation tower (1) and the second heat exchange inlet of the shell-and-tube heat exchanger (5).

5. The benzene hydrogenation preheating distillation tower structure with efficient recycling of tower bottom heat according to claim 3, characterized in that: The material storage device comprises a storage tank (8) and a second cooler (7); the storage tank (8) is provided with a material storage port; the storage tank (8) is provided with a second cooler (7) outside the storage tank (8); the material storage port of the storage tank (8) and a material discharge port on the second cooler (7) are connected via a pipeline; the second cooler (7) is provided with a cooling material feed port; the cooling material feed port of the second cooler (7) is connected to a second heat exchange outlet of the shell and tube heat exchanger (5) via a pipeline.

Images