Improved gas-phase benzene recovery control system

Abstract

The utility model relates to an improved gas-phase benzene recovery control system, which is used for recovering gas-phase benzene in a reflux tank of a benzene rectifying tower of an aromatic hydrocarbon device and recovering C6 light components with the boiling point close to that of benzene, and comprises a benzene reflux tank, an upward side pipeline is led out of the position, close to the top of the benzene return tank, of the nitrogen pipeline, the top of the side pipeline is connected with a first pipeline used for being connected with the fin type heat exchanger, the first pipeline is connected to the bottom of the fin type heat exchanger, and the top of the fin type heat exchanger is connected with a torch discharging pipeline; gas-phase benzene of the benzene return tank enters a first pipeline through a side pipeline, passes through a fin type heat exchanger and then enters a torch discharging pipeline to be discharged into a torch liquid separation tank, the fin type heat exchanger is additionally arranged on a torch discharging pipeline at the top of an original tank, the overall height of the torch discharging pipeline is increased, and the purpose of recycling liquid carried in torch gas is achieved. And compared with the original height, the ratio range of the improved height is 1-2 times.

Description

Technical Field

[0001] The utility model relates to an improved gas phase benzene recovery control system, which is used for recovering gas phase benzene from a reflux tank of a benzene rectification tower of an aromatics unit and recovering C6 light components with a similar boiling point to benzene, and belongs to the technical field of chemical industry. Background Art

[0002] There are a small amount of gaseous benzene and C5 and C6 light components with similar boiling points to benzene, as well as a small amount of nitrogen in the reflux tank of the benzene distillation tower of the aromatics unit (operating temperature of about 70-80°C, gauge pressure of 0.02-0.03MpaG, benzene boiling point of 80.1°C). These gaseous components need to be discharged to the flare tank through the flare pipeline for closed recovery, resulting in the loss of pure benzene. In addition, benzene is listed as a Class 1 carcinogen in the list of carcinogens published by the International Agency for Research on Cancer of the World Health Organization. Therefore, reducing the emission of this part of benzene and hydrocarbons not only reduces energy waste but also reduces the recycling of carcinogens and reduces the risk of exposure. Among them, the product composition and content, such as Figure 2 shown. Utility Model Content

[0003] In view of the deficiencies in the prior art, the purpose of the utility model is to provide an improved gas-phase benzene recovery control system, which achieves the purpose of recovering the liquid carried in the flare gas by adding a fin heat exchanger to the flare pipeline on the original tank top and increasing the overall height of the flare pipeline.

[0004] In order to achieve the above-mentioned purpose, the technical scheme adopted by the utility model is: an improved gas-phase benzene recovery control system, comprising: a benzene reflux tank, a nitrogen pipeline is provided on one side of the top of the benzene reflux tank, an upward side pipeline is led out from the nitrogen pipeline near the top of the benzene reflux tank, the top of the side pipeline is connected with a first pipeline for connecting a fin heat exchanger, the first pipeline is connected to the bottom of the fin heat exchanger, and the top of the fin heat exchanger is connected with a flare discharge pipeline; the gas-phase benzene in the benzene reflux tank enters the first pipeline through the side pipeline, and enters the flare discharge pipeline after passing through the fin heat exchanger and is discharged into the flare liquid separation tank for recovering the liquid phase;

[0005] Furthermore, the height of the flare discharge pipeline is raised from the top position of the side pipeline to the position above the fin heat exchanger, ensuring that there is a sufficient height difference between the flare discharge pipeline and the benzene reflux tank.

[0006] Furthermore, a flare pressure control valve group is provided on the flare pipeline;

[0007] Furthermore, the flare discharge pressure control valve group is installed at the rear end of the flare discharge pipeline;

[0008] Furthermore, an air cooler is provided above the other side of the top of the benzene reflux tank, and the upper part of the air cooler is connected to the benzene distillation tower line.

[0009] Furthermore, the nitrogen pipeline is provided with a control valve group with the same structure as that on the flare exhaust pipeline, and a one-way valve is provided at the lower end of the control valve group; the pressure of the benzene reflux tank is increased and stabilized through the nitrogen pipeline.

[0010] In the above structure of the utility model, the position above the top of the side pipeline is the original position of the flare pipeline; the utility model ensures the height difference with the benzene reflux tank by adding a fin heat exchanger and changing the height position of the flare exhaust pipeline; the purpose of setting the fin heat exchanger is to reduce the temperature of the benzene-containing gas as much as possible so that the maximum amount of benzene can be condensed into liquid phase; the purpose of ensuring the height difference between the flare exhaust pipeline and the benzene reflux tank is to allow a smaller amount of non-condensable gas containing benzene to enter the flare system, which is more conducive to the recovery of gaseous benzene, while ensuring that the condensed liquid benzene flows back to the tank by gravity.

[0011] The benzene distillation tower line at the top of the air cooler is derived from the benzene distillation tower. A feed line is arranged on the side wall of one side of the benzene distillation tower, and a petroleum benzene product at the top of the tower is distilled out through a side line on the other side, and the side line is connected to a benzene product extraction pump; the gas phase component at the top of the tower is cooled by the air cooler to a reflux tank of the benzene distillation tower and is used as reflux through a benzene reflux pump at the bottom of the benzene reflux tank; a pipeline connected to a toluene tower is arranged at the bottom of the benzene distillation tower, and C7+ aromatics at the bottom of the tower are sent to the toluene tower to continue to separate toluene.

[0012] Furthermore, the top of the flare separator tank is also connected to a flare head or a flare gas compressor through a pipeline, the bottom of the flare separator tank is connected to a waste oil pump through a pipeline, and the waste oil pump outlet pipeline is connected to the naphtha pre-hydrogenation unit of the aromatics unit; the liquid phase part in the flare separator tank needs to be returned to the naphtha pre-hydrogenation unit of the aromatics unit through the waste oil pump for re-pretreatment to avoid energy waste and loss of part of the pure benzene; the gas phase part of the flare gas is discharged to the flare head for combustion or recovered to the fuel gas system through the flare compressor for recycling.

[0013] The beneficial effects of the utility model are:

[0014] By adding a fin heat exchanger to the flare pipeline on the top of the original tank and increasing the overall height of the flare pipeline, the purpose of recovering the liquid carried in the flare gas is achieved; and the increased height is 1-2 times higher than the original. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a structural diagram of the utility model.

[0016] Figure 2 This is a table showing the composition and content of the products described in the background technology.

[0017] In the figure, 1, benzene reflux tank, 2, nitrogen pipeline, 3, side pipeline, 4, first pipeline, 5, fin heat exchanger, 6, flare exhaust pipeline, 7, side pipeline vertex position, 8, flare exhaust pressure control valve group, 9, air cooler, 10, benzene distillation tower line, 11, one-way valve, 12, flare liquid separation tank, 13, benzene distillation tower, 14, feed line, 15, side line, 16, benzene product extraction pump, 17, benzene reflux pump, 18, pipeline connected to toluene tower, 19, waste oil pump. DETAILED DESCRIPTION

[0018] In order to make the above-mentioned purposes, features and advantages of the utility model more obvious and easy to understand, the specific implementation methods of the utility model are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the utility model. However, the utility model can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the utility model, so the utility model is not limited by the specific embodiments disclosed below.

[0019] like Figure 1 An improved gas-phase benzene recovery control system shown includes: a benzene reflux tank 1, a nitrogen pipeline 2 is provided on one side of the top of the benzene reflux tank 1, an upward side pipeline 3 is led out of the nitrogen pipeline 2 near the top of the benzene reflux tank 1, the top of the side pipeline 3 is connected with a first pipeline 4 for connecting to a fin heat exchanger 5, the first pipeline 4 is connected to the bottom of the fin heat exchanger 5, and the top of the fin heat exchanger 5 is connected with a flare discharge pipeline 6; the gas-phase benzene in the benzene reflux tank 1 enters the first pipeline 4 through the side pipeline 3, and enters the flare discharge pipeline 6 after passing through the fin heat exchanger 5 and is discharged into the flare liquid separation tank 12;

[0020] Furthermore, the height of the flare discharge pipeline 6 is raised from the side pipeline vertex position 7 to the position above the fin heat exchanger 5 to ensure that there is a sufficient height difference between the flare discharge pipeline 6 and the benzene reflux tank 1 .

[0021] Furthermore, a flare discharge pressure control valve group 8 is provided on the flare discharge pipeline 6;

[0022] Further, the flare discharge pressure control valve group 8 is installed at the rear end of the flare discharge pipeline 6;

[0023] Furthermore, an air cooler 9 is provided above the other side of the top of the benzene reflux tank 1 , and the upper part of the air cooler 9 is connected to a benzene distillation tower line 10 .

[0024] Furthermore, the nitrogen pipeline 2 is provided with a control valve group having the same structure as that on the flare exhaust pipeline 6, and a one-way valve 11 is provided at the lower end of the control valve group.

[0025] In the above structure of the utility model, the position above the side pipeline vertex 7 is the original position of the flare pipeline; the utility model ensures the height difference with the benzene reflux tank 1 by adding a fin heat exchanger 5 and changing the height position of the flare pipeline 6.

[0026] The benzene distillation tower line 10 at the top of the air cooler 9 is derived from the benzene distillation tower 13. A feed line 14 is arranged on the side wall of one side of the benzene distillation tower 13, and a petroleum benzene product at the top of the tower is distilled out through a side line 15 on the other side. The side line 15 is connected to a benzene product extraction pump 16; the gas phase component at the top of the tower is cooled by the air cooler 9 to the benzene distillation tower reflux tank 1 and is used as reflux through a benzene reflux pump 17 at the bottom of the benzene reflux tank 1; a pipeline 18 connected to a toluene tower is arranged at the bottom of the benzene distillation tower 13, and C7+ aromatics at the bottom of the tower are sent to the toluene tower to continue to separate toluene.

[0027] Furthermore, the top of the flare liquid separator 12 is also connected to a flare head or a flare gas compressor through a pipeline, and the bottom of the flare liquid separator 12 is connected to a waste oil pump 19 through a pipeline, and the outlet pipeline of the waste oil pump 19 is connected to the naphtha pre-hydrogenation unit of the aromatics unit; the liquid phase part in the flare liquid separator 12 needs to be returned to the naphtha pre-hydrogenation unit of the aromatics unit through the waste oil pump 19 for re-pretreatment to avoid energy waste and loss of part of the pure benzene; the gas phase part of the flare gas is discharged to the flare head for combustion or recovered to the fuel gas system through the flare compressor for recycling.

[0028] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0029] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present utility model, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0030] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] In the present utility model, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0032] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only implementation method.

Claims

1. An improved gas phase benzene recovery control system, characterized in that: include: A benzene reflux tank, wherein a nitrogen pipeline is provided on one side of the top of the benzene reflux tank, an upward side pipeline is led out from the nitrogen pipeline near the top of the benzene reflux tank, the top of the side pipeline is connected to a first pipeline for connecting a fin heat exchanger, the first pipeline is connected to the bottom of the fin heat exchanger, and the top of the fin heat exchanger is connected to a flare exhaust pipeline; the gaseous benzene in the benzene reflux tank enters the first pipeline through the side pipeline, and enters the flare exhaust pipeline after passing through the fin heat exchanger to be discharged into the flare separator tank.

2. An improved gas phase benzene recovery control system according to claim 1, characterized in that: The height of the flare discharge pipeline is increased from the top position of the side pipeline to the position above the fin heat exchanger.

3. An improved gas phase benzene recovery control system according to claim 1, characterized in that: A flare discharge pressure control valve group is arranged on the flare discharge pipeline.

4. An improved gas phase benzene recovery control system according to claim 3, characterized in that: The flare discharge pressure control valve group is installed at the rear end position of the flare discharge pipeline.

5. An improved gas phase benzene recovery control system according to claim 1, characterized in that: An air cooler is arranged above the other side of the top of the benzene reflux tank, and the upper part of the air cooler is connected to the benzene distillation tower line.

6. An improved gas phase benzene recovery control system according to claim 3, characterized in that: The nitrogen pipeline is provided with a control valve group with the same structure as that on the flare exhaust pipeline, and a one-way valve is provided at the lower end of the control valve group.

7. An improved gas phase benzene recovery control system according to claim 5, characterized in that: The benzene distillation tower line at the top of the air cooler is derived from the benzene distillation tower. A feed line is arranged on the side wall of one side of the benzene distillation tower, and a petroleum benzene product at the top of the tower is distilled out through a side line on the other side, and the side line is connected to a benzene product extraction pump; the gas phase component at the top of the tower is cooled by the air cooler to a reflux tank of the benzene distillation tower and is used as reflux through a benzene reflux pump at the bottom of the benzene reflux tank; a pipeline connected to a toluene tower is arranged at the bottom of the benzene distillation tower.

8. An improved gas phase benzene recovery control system according to claim 1, characterized in that: The top of the flare liquid separator is also connected to the flare head or the flare gas compressor through a pipeline, and the bottom of the flare liquid separator is connected to a waste oil pump through a pipeline, and the waste oil pump outlet pipeline is connected to the naphtha pre-hydrogenation device of the aromatics device.

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