Waste gas water seal system for polyethylene production process

Abstract

The utility model provides a waste gas water seal system of a polyethylene production process, which relates to the field of low-pressure slurry method polyethylene process, and comprises a water seal tank, the water seal tank is provided with a water inlet, a waste gas inlet, a water discharge port and a waste gas discharge port, the water inlet is connected with a production water supply pipeline, and the waste gas inlet is connected with a waste gas discharge port. The production water supply pipeline is communicated with the jacket water supply pipeline, the water discharge port is connected with the water discharge pipeline, the waste gas inlet is connected with the waste gas supply pipeline, and the waste gas discharge port is connected with the waste gas discharge pipeline. According to the utility model, the production water supply pipeline and the jacket water supply pipeline are combined to supply water to the water-sealed tank, so that the water seal pressure of the water-sealed tank is improved, and the problem that the use of the water-sealed tank is influenced due to the fact that low-pressure waste gas is discharged into the water-sealed tank when the liquid ring compressor is normally used because the water seal pressure of a water-sealed tank pipe is easy to be insufficient is solved.

Description

Technical Field

[0001] The utility model relates to the field of low-pressure pulping polyethylene technology, in particular to a waste gas water seal system of the polyethylene production technology. Background Art

[0002] The tail gas generated by polymerization reaction, hexane refining, etc. in the polyethylene production process is generally pressurized to 0.2MPa by a liquid ring compressor, and then separated by a gas-liquid separation tank. The gas phase after gas-liquid separation enters the boundary high-pressure flare network. The high-pressure flare network has corresponding recovery devices, and ethylene, butene, etc. in the gas phase can be recovered. However, in the actual process, the liquid ring compressor may fail, or it may also face a sudden increase in tail gas pressure. These situations make the tail gas emission face unorganized emissions. The tail gas compression path caused by the failure of the liquid ring compressor is isolated. At this time, the tail gas can enter the water seal tank for storage through the pipeline branch pipeline, and through the outlet pipeline of the water seal tank, after the tail gas breaks through the water seal pressure of the water seal tank, it is discharged to a safe place in the atmosphere.

[0003] However, affected by the height of the exhaust gas supply pipeline, the water seal tank receiving the exhaust gas is installed in a higher area. In some cases, the water seal tank needs to be installed in an area with a height of 25 meters or even higher. In this case, the production water is already supplied to multiple projects in parallel in the factory area, and considering the installation position of the water seal tank, the production water supply pipeline near the upper position of the production water main pipe needs to be connected to the water seal tank, resulting in the production water supply pressure to the water seal tank being lower than the design pressure in many cases. For example, in actual projects, the pressure of the water seal tank is about 0.15MPa in summer and about 0.2MPa in winter. In this case, the water seal tank pipe is prone to insufficient water seal pressure, resulting in the possibility that low-pressure exhaust gas may enter the water seal tank and be discharged during the normal use of the liquid ring compressor, affecting the use of the water seal tank. Utility Model Content

[0004] The utility model provides a waste gas water seal system for a polyethylene production process, which solves the problem that insufficient water seal pressure easily occurs in the existing water seal tank pipe, causing low-pressure waste gas to enter the water seal tank when the liquid ring compressor is in normal use.

[0005] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0006] A waste gas water seal system for a polyethylene production process comprises a water seal tank, on which a water inlet, a waste gas inlet, a water discharge port and a waste gas discharge port are arranged, the water inlet is connected to a production water supply pipeline, the production water supply pipeline is communicated with a jacket water supply pipeline, the water discharge port is connected to a water discharge pipeline, the waste gas inlet is connected to a waste gas supply pipeline, and the waste gas discharge port is connected to a waste gas discharge pipeline.

[0007] Furthermore, the gas outlet of the exhaust gas supply pipeline is located below the liquid level of the water in the water seal tank.

[0008] Furthermore, a first valve and a flow meter are arranged on the production water supply pipeline, and the flow meter is arranged downstream of the first valve.

[0009] Furthermore, a second valve is also arranged on the production water supply pipeline, and the second valve is arranged downstream of the flow meter.

[0010] Furthermore, the jacket water supply pipeline is communicated with the production water supply pipeline between the first valve and the flow meter, and a third valve is arranged on the jacket water supply pipeline.

[0011] Further, the jacket water supply pipeline is in communication with the jacket water return pipeline of the condenser. Further, the jacket water return port of the condenser is in communication with the jacket water return pipeline, an end of the jacket water return pipeline is provided with an end guide valve through a branch pipeline, the branch pipeline upstream of the guide valve is connected to the jacket water supply pipeline, and a fourth valve is provided on the jacket water supply pipeline near the connection between the branch pipeline and the jacket water supply pipeline.

[0012] Furthermore, the water discharge pipeline includes a first downcomer, a first straight pipe, an ascending pipe, a second straight pipe and a second downcomer, the first downcomer is connected to the first straight pipe, the first straight pipe is connected to the ascending pipe, the ascending pipe is connected to the second straight pipe, and the second straight pipe is connected to the second downcomer.

[0013] Furthermore, the second straight pipe is arranged at a height that is consistent with the liquid level of water in the water seal tank.

[0014] Furthermore, a first outlet valve is installed on the first downcomer.

[0015] The beneficial effects of the utility model are:

[0016] The utility model combines the production water supply pipeline with the jacket water supply pipeline to provide water to the water seal tank, thereby improving the water seal pressure of the water seal tank and solving the problem that the water seal pressure of the water seal tank pipe is insufficient, resulting in low-pressure exhaust gas being discharged into the water seal tank when the liquid ring compressor is in normal use, thus affecting the use of the water seal tank. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the utility model or the technical solutions of the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 It is a schematic diagram of the overall device of the utility model.

[0019] Figure 2 It is a partial schematic diagram of the utility model.

[0020] Description of Figure Numbers:

[0021] 1. Water seal tank; 2. Water inlet; 3. Waste gas inlet; 4. Waste gas discharge port; 5. Water discharge port; 6. Production water supply pipeline; 7. First valve; 8. Flow meter; 9. Second valve; 10. Jacket water supply pipeline; 11. Third valve; 12. Jacket water return pipeline; 13. Condenser; 14. Drain valve; 15. Fourth valve. DETAILED DESCRIPTION

[0022] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0023] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means a limitation on the utility model and its application or use. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the utility model.

[0024] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the utility model. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0025] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, numerical expressions and numerical values ​​do not limit the scope of the utility model. At the same time, it should be clear that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The technology, methods and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be regarded as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0026] In the description of the present utility model, it needs to be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present utility model and simplifying the description. Unless otherwise stated, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present utility model: the directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0027] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below their position devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0028] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the utility model.

[0029] The utility model provides a technical solution: a waste gas water seal system for a polyethylene production process, such as Figure 1 As shown, it comprises a water seal tank 1, on which a water inlet 2, an exhaust gas inlet 3, a water discharge port 5 and an exhaust gas discharge port 4 are arranged, the water inlet 2 is connected to a production water supply pipeline 6, and the production water supply pipeline 6 supplies water to the water seal tank 1; the production water supply pipeline 6 is in communication with a jacket water supply pipeline 10;

[0030] The water inlet 2, the exhaust gas inlet 3 and the exhaust gas discharge port 4 are arranged at the upper part of the tank body, and the water discharge port 5 is arranged at the lower part of the tank body;

[0031] The production water supply pipeline 6 is connected to the water inlet 2 to supply production water into the water seal tank 1, so that the water in the water seal tank 1 reaches a certain depth, and the upper liquid level of the production water in the water seal tank 1 is fixed at a first height relative to the water seal tank 1.

[0032] The production water supply pipeline 6 is provided with a first valve 7 and a flow meter 8. The flow meter 8 is installed downstream of the first valve 7. The first valve 7 is a valve for controlling the opening or closing of the production water supply pipeline 6, and can control the supply side to provide or stop supplying water to the production water supply pipeline 6; the production water supply pipeline 6 is provided with a second valve 9, and the second valve 9 is installed downstream of the flow meter 8.

[0033] The exhaust gas supply pipeline is introduced into the water seal tank 1 through the exhaust gas inlet 3 and is inserted into the production water inside the water seal tank 1. The outlet of the exhaust gas supply pipeline penetrates into a certain depth below the upper liquid surface of the production water. The outlet of the exhaust gas supply pipeline is fixed at a second height relative to the water seal tank 1. In the height direction of the water seal tank 1, the first height is higher than the second height.

[0034] The water discharge pipeline is connected to the water discharge port 5 of the water seal tank 1. The water discharge pipeline has a pipeline portion that is equal to the first height in the height direction of the water seal tank 1, so that when the height of the water in the water seal tank 1 exceeds the first height in the height direction of the water seal tank 1, the production water is discharged from the water seal tank 1 through the discharge pipeline. When the height of the production water in the water seal tank 1 in the height direction of the water seal tank 1 is equal to the first height, the production water is stopped from being discharged from the water seal tank 1 through the discharge pipeline, so that the upper liquid level of the production water in the water seal tank 1 is equal to the first height fixed to the water seal tank 1. Through the principle of the communicating vessel, the outlet of the exhaust gas supply pipeline is fixed at a second height relative to the water seal tank 1, that is, the depth of the outlet of the exhaust gas supply pipeline in the production water remains unchanged. In this case, the depth of the production water can maintain a dynamic balance, achieving the effect of stably maintaining the water seal pressure.

[0035] The water discharge pipeline includes a first downcomer, a first straight pipe, an ascending pipe, a second straight pipe and a second downcomer, the first downcomer is connected to the first straight pipe, the first straight pipe is connected to the ascending pipe, the ascending pipe is connected to the second straight pipe, and the second straight pipe is connected to the second downcomer.

[0036] The first downcomer is provided with a first outlet valve for controlling the opening or closing of the first downcomer, and controlling the produced water discharge port 5 to discharge or stop discharging produced water.

[0037] The water discharge pipeline also includes a third straight pipe, the first straight pipe is connected to the third straight pipe, and the third straight pipe is connected to the second downcomer, wherein the first straight pipe is connected to the upcomer and the third straight pipe in parallel, and a second outlet valve for controlling the opening or closing of the third straight pipe is installed on the third straight pipe.

[0038] The exhaust gas discharge pipeline discharges the exhaust gas in the water seal tank 1 from the outlet of the exhaust gas supply pipeline fixed at a second height relative to the water seal tank 1 to the outside through the exhaust gas discharge port 4 for discharge. The exhaust gas discharge point of the exhaust gas discharge pipeline is an atmospheric safety discharge point. It can be understood that according to the scheme, the water seal prevents the low-pressure exhaust gas from overcoming the pressure provided by the production water and releasing the exhaust gas in the water seal tank 1. Therefore, only when the exhaust gas compression path is isolated due to a failure of the liquid ring compressor and the exhaust gas pressure is increased to break through the water seal, can the exhaust gas be discharged through the water seal tank 1 and discharged to an atmospheric safety location through the exhaust gas discharge pipeline. This allows the exhaust gas to be discharged in an organized manner in the event of a failure of the liquid ring compressor.

[0039] Example 1

[0040] A waste gas water seal system for a polyethylene production process, wherein the waste gas comes from a hexane purification system, a flash evaporation system, etc. in the polyethylene production process, and the water seal system specifically comprises a water seal tank 1, a production water supply pipeline 6, a jacket water supply pipeline 10, a waste gas supply pipeline, a water discharge pipeline, and a waste gas discharge pipeline.

[0041] The water seal tank 1 comprises a tank body, which has a water inlet 2, an exhaust gas inlet 3, a water discharge port 5 and an exhaust gas discharge port 4; the water inlet 2, the exhaust gas inlet 3 and the exhaust gas discharge port 4 are arranged at the top of the tank body, and the water discharge port 5 is arranged at the bottom of the tank body.

[0042] The production water supply pipeline 6 is connected to the water inlet 2 to supply production water to the water seal tank 1. The production water in the water seal tank 1 is supplied so that the production water reaches a certain depth, and the upper liquid level of the production water in the water seal tank 1 is fixed at a first height relative to the water seal tank 1. In a preferred embodiment, the production water supply pipeline 6 is provided with a first valve 7 and a flow meter 8, and the flow meter 8 is installed downstream of the first valve 7. The first valve 7 is a valve for controlling the opening or closing of the production water supply pipeline 6, and can control the supply side to provide or stop supplying water to the production water supply pipeline 6. More preferably, the production water supply pipeline 6 is provided with a second valve 9, and the second valve 9 is installed downstream of the flow meter 8.

[0043] The exhaust gas supply pipeline is introduced into the water seal tank 1 through the exhaust gas inlet 3 and is inserted into the production water inside the water seal tank 1. The outlet of the exhaust gas supply pipeline penetrates into a certain depth below the upper liquid surface of the production water. The outlet of the exhaust gas supply pipeline is fixed at a second height relative to the water seal tank 1. In the height direction of the water seal tank 1, the first height is higher than the second height.

[0044] The water discharge pipeline is connected to the water discharge port 5 of the water seal tank 1, and the water discharge pipeline has a pipeline portion that is equal to the first height in the height direction of the water seal tank 1, so that when the height of the produced water in the water seal tank 1 in the height direction of the water seal tank 1 exceeds the first height, the produced water is discharged from the water seal tank 1 through the discharge pipeline, and when the height of the produced water in the water seal tank 1 in the height direction of the water seal tank 1 is equal to the first height, the production water is stopped from being discharged from the water seal tank 1 through the discharge pipeline, so that the upper liquid level of the produced water in the water seal tank 1 is fixed at the first height relative to the water seal tank 1, and through the principle of the communicating vessel, the outlet of the exhaust gas supply pipeline is fixed at the second height relative to the water seal tank 1, that is, the depth of the outlet of the exhaust gas supply pipeline in the produced water remains unchanged. In this case, the depth of the produced water can maintain a dynamic balance, achieving the effect of stably maintaining the water seal pressure.

[0045] The water discharge pipeline includes a first downcomer, a first straight pipe, an ascending pipe, a second straight pipe and a second downcomer, the first downcomer is connected to the first straight pipe, the first straight pipe is connected to the ascending pipe, the ascending pipe is connected to the second straight pipe, and the second straight pipe is connected to the second downcomer.

[0046] The first downcomer is provided with a first outlet valve for controlling the opening or closing of the first downcomer, and controlling the water discharge port 5 to discharge or stop discharging produced water.

[0047] The water discharge pipeline also includes a third straight pipe, the first straight pipe is connected to the third straight pipe, and the third straight pipe is connected to the second downcomer, wherein the first straight pipe is connected to the upcomer and the third straight pipe in parallel, and a second outlet valve for controlling the opening or closing of the third straight pipe is installed on the third straight pipe.

[0048] The exhaust gas discharge pipeline discharges the exhaust gas in the water seal tank 1 from the outlet of the exhaust gas supply pipeline fixed at a second height relative to the water seal tank 1 to the outside through the exhaust gas discharge port 4. In the preferred embodiment, the exhaust gas discharge point of the exhaust gas discharge pipeline is an atmospheric safety discharge point. It can be understood that according to the scheme, the water seal prevents the low-pressure exhaust gas from overcoming the pressure provided by the production water and releasing the exhaust gas in the water seal tank 1. Therefore, only when the exhaust gas compression path is isolated due to a failure of the liquid ring compressor and the exhaust gas pressure is increased to break through the water seal, can the exhaust gas be discharged through the water seal tank 1 and discharged to an atmospheric safety location through the exhaust gas discharge pipeline. This allows the exhaust gas to be discharged in an organized manner in the event of a failure of the liquid ring compressor.

[0049] The water seal system further comprises a jacket water supply pipeline 10, wherein the jacket water is desalted water, and the outlet of the jacket water supply pipeline 10 is connected to the production water supply pipeline 6. A third valve 11 is arranged on the jacket water supply pipeline 10.

[0050] The water inlet of the jacket water supply pipeline 10 is connected to the jacket water return port of the condenser 13, and the jacket water of the condenser 13 supplies water to the jacket water supply pipeline 10. The production water supply pipeline 6 is provided with a first valve 7, a flow meter 8 and a second valve 9, and the flow meter 8 is installed downstream of the first valve 7, and the second valve 9 is installed downstream of the flow meter 8. Therefore, by opening the first valve 7, closing the third valve 11, and opening the second valve 9, the production water is supplied to the water seal tank 1 through the production water supply pipeline 6, and the flow meter 8 can measure the water volume. By closing the first valve 7, opening the third valve 11, and opening the second valve 9, the jacket water is first supplied to the water seal tank 1 through the jacket water supply pipeline 10, and then through the production water supply pipeline 6.

[0051] The condenser 13 is a condenser 13 at the top of the hexane refining tower, and the jacket water return port of the condenser 13 is connected to the jacket water return pipeline 12. The end of the jacket water return pipeline 12 is installed with an end guide valve 14 through a branch pipeline, and the jacket water supply pipeline 10 is connected to the branch pipeline upstream of the guide valve 14. As a preferred solution, a fourth valve 15 is installed on the jacket water supply pipeline 10 near the position where the branch pipeline is connected to the jacket water supply pipeline 10. The fourth valve 15 is a valve that controls the opening or closing of the jacket water supply pipeline 10.

[0052] The above is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent substitutions or changes within the technical scope disclosed by the present invention according to the technical solution and inventive concept of the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A waste gas water seal system for a polyethylene production process, characterized in that: The invention comprises a water seal tank (1), wherein the water seal tank (1) is provided with a water inlet (2), an exhaust gas inlet (3), a water discharge port (5) and an exhaust gas discharge port (4); the water inlet (2) is connected to a production water supply pipeline (6), the production water supply pipeline (6) is communicated with a jacket water supply pipeline (10), the water discharge port (5) is connected to the water discharge pipeline, the exhaust gas inlet (3) is connected to the exhaust gas supply pipeline, and the exhaust gas discharge port (4) is connected to the exhaust gas discharge pipeline.

2. The waste gas water seal system for polyethylene production process according to claim 1, characterized in that: The gas outlet of the exhaust gas supply pipeline is located below the liquid level of the water in the water seal tank (1).

3. The waste gas water seal system for polyethylene production process according to claim 1, characterized in that: A first valve (7) and a flow meter (8) are provided on the production water supply pipeline (6), and the flow meter (8) is provided downstream of the first valve (7).

4. The waste gas water seal system for polyethylene production process according to claim 3, characterized in that: A second valve (9) is also provided on the production water supply pipeline (6), and the second valve (9) is provided downstream of the flow meter (8).

5. The waste gas water seal system for polyethylene production process according to claim 1, characterized in that: The jacket water supply pipeline (10) is in communication with the production water supply pipeline (6) between the first valve (7) and the flow meter (8), and a third valve (11) is provided on the jacket water supply pipeline (10).

6. The waste gas water seal system for polyethylene production process according to claim 5, characterized in that: The jacket water supply pipeline (10) is in communication with the jacket water return pipeline (12) of the condenser (13).

7. The waste gas water seal system for polyethylene production process according to claim 6, characterized in that: The jacket water return port of the condenser (13) is connected to a jacket water return pipeline (12); an end guide valve (14) is installed at the end of the jacket water return pipeline (12) through a branch pipeline; a jacket water supply pipeline (10) is connected to the branch pipeline upstream of the guide valve (14); and a fourth valve (15) is installed on the jacket water supply pipeline (10) near a position where the branch pipeline is connected to the jacket water supply pipeline (10).

8. The waste gas water seal system for polyethylene production process according to claim 1, characterized in that: The water discharge pipeline includes a first downcomer, a first straight pipe, an ascending pipe, a second straight pipe and a second downcomer, the first downcomer is connected to the first straight pipe, the first straight pipe is connected to the ascending pipe, the ascending pipe is connected to the second straight pipe, and the second straight pipe is connected to the second downcomer.

9. The waste gas water seal system for polyethylene production process according to claim 8, characterized in that: The installation height of the second straight pipe is consistent with the liquid level height of water in the water seal tank (1).

10. The waste gas water seal system for polyethylene production process according to claim 8, characterized in that: The first downcomer is provided with a first outlet valve.

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