Quenched water treatment system for ethylene unit

Abstract

The utility model relates to a quenching water treatment system for an ethylene device, which comprises a coalescence filtering unit, a water treatment unit, a water treatment unit and a water treatment unit, and is characterized in that the coalescence filtering unit comprises a first coalescence filter, a second coalescence filter and a third coalescence filter; the centrifugal unit comprises a centrifugal machine, the centrifugal machine is provided with a liquid-phase medium inlet and a liquid-phase medium outlet, the liquid-phase medium inlet is connected with the first concentrated sewage outlet, the second concentrated sewage outlet and the third concentrated sewage outlet, and the liquid-phase medium outlet is connected with a second liquid return pipeline used for returning centrifugally treated quenching water to the quenching water tower. After quenching water of an ethylene device is filtered by the multi-stage filter of the coalescence filtering unit, the content of tiny coke in the quenching water can be greatly reduced, and the frequency of cleaning a main filter is reduced, so that the risk of blockage of a quenching water heat exchanger is effectively reduced, and safe and stable production is realized.

Description

Technical Field

[0001] The utility model relates to the technical field of ethylene devices, in particular to a quenching water treatment system for an ethylene device. Background Art

[0002] In recent years, steam cracking ethylene plants using ethane and propane as raw materials have shown significant advantages in cost control. The specific process of ethylene-propane mixed steam cracking ethylene plants is basically as follows: In ethylene production plants using ethane and propane as raw materials, cracking furnaces produce cracking gas, which is first recovered by TLE for heat recovery to produce ultra-high pressure steam. Subsequently, these steams are cooled by boiler feed water, cooled to 190°C, and then sent to the quenching water tower. In the quenching water tower, the cracking gas directly contacts the circulating quenching water to achieve further cooling to 40°C. In the quenching water tower, the dilution steam and heavy components in the cracking gas are condensed. These condensed hydrocarbons and water are further separated at the bottom of the tower and the quenching water separation tank. Most of the quenching water separated from the bottom of the quenching water tower will be sent to various process heaters or reboilers through the quenching water circulation pump. After the low-level heat energy of the quenching water is used up, it will be further cooled by cooling water and then circulated back to the quenching water tower. At the same time, the process water separated from the quench water separator will be filtered to remove trace coke powder solids, and then enter the process water treatment system for purification. The purified process water will be sent to the process water stripping tower, and hydrocarbons and acid gases will be stripped out. The process water at the bottom of the process water stripping tower will be sent to the dilution steam generator to generate dilution steam, which will eventually be sent to the cracking furnace area and used as dilution steam for cracking reactions.

[0003] According to the process characteristics of the steam cracking ethylene production unit using ethylene propane as raw material, the cracking gas produced by the cracking furnace does not flow through the quench oil tower, but directly enters the quench water tower, which will cause the quench water in the quench water tower and the corresponding process water quality to be significantly affected (high oil component and impurity content). At present, several domestic ethylene propane steam cracking ethylene production units do not have a mature and reliable quench water treatment technology. Most of them use the previous petroleum hydrocarbon cracking quench water treatment technology: generally, a main filter (such as a basket filter with an electric scraper) and a secondary filter are combined. Due to the large circulation flow of the quench water, which can generally reach 1500t / h~2000t / h, it is first coarsely filtered through the main filter, and then the sewage is sent to the secondary filter for fine filtration. This filtering method has the following problems: on the one hand, it will cause a large amount of coke powder impurities in the quench water and low operating efficiency; on the other hand, the fine coke powder that cannot be filtered out is not filtered thoroughly, and the fine coke powder will be brought into the heat exchange users of the quench water system, causing the heat exchanger to be blocked.

[0004] Therefore, existing range hoods need further improvement. Utility Model Content

[0005] The technical problem to be solved by the utility model is to provide an ethylene device quenching water treatment system which can effectively remove coke powder impurities in process water and avoid blockage of heat exchanger in view of the current status of the prior art.

[0006] The technical solution adopted by the utility model to solve the above technical problems is:

[0007] A quench water treatment system for an ethylene device, comprising:

[0008] A coalescence filtration unit, comprising a first coalescence filter, a second coalescence filter and a third coalescence filter connected in sequence, wherein the inlet of the first coalescence filter is connected to a quench water inlet pipeline for conveying quench water, the first coalescence filter also has a first quench water outlet and a first concentrated sewage outlet, the second coalescence filter also has a second quench water outlet and a second concentrated sewage outlet, the third coalescence filter also has a third quench water outlet and a third concentrated sewage outlet, the first quench water outlet is connected to the inlet of the second coalescence filter, the second quench water outlet is connected to the inlet of the third coalescence filter, and the third quench water outlet is connected to a first liquid return pipeline for returning filtered quench water to a quench water tower;

[0009] The centrifugal unit comprises a centrifuge having a liquid medium inlet and a liquid medium outlet, wherein the liquid medium inlet is connected to the first concentrated sewage outlet, the second concentrated sewage outlet and the third concentrated sewage outlet, and the liquid medium outlet is connected to a second liquid return pipeline for returning the quenching water after centrifugal treatment to the quenching water tower.

[0010] In order to achieve graded filtration and improve filtration efficiency, the first coalescence filter, the second coalescence filter and the third coalescence filter all include coalescence filter elements, and the mesh sizes of the coalescence filter elements of the first coalescence filter, the second coalescence filter and the third coalescence filter increase successively.

[0011] Preferably, the mesh number of the coalescence filter element of the first coalescence filter is 1000 mesh, the mesh number of the coalescence filter element of the second coalescence filter is 3000 mesh, and the mesh number of the coalescence filter element of the third coalescence filter is 5000 mesh.

[0012] In order to enhance the separation effect, the first coalescing filter, the second coalescing filter and the third coalescing filter are also connected to an external ventilation pipeline, and the external ventilation pipeline is connected to a gas source. The gas source (generally nitrogen or cracking gas) is distributed through a distributor inside the filter to evenly generate tiny bubbles. The bubbles cooperate with the filter element to more efficiently separate the coke powder.

[0013] In order to facilitate the cleaning of the coalescing filter, the coalescing filter elements of the first coalescing filter, the second coalescing filter and the third coalescing filter are also connected to an external backwashing water pipeline, and the water of the backwashing pipeline comes from the process water treatment unit.

[0014] In order to process the solid phase slag separated by the centrifuge, the invention also includes a solid phase receiving unit for receiving the solid phase medium after centrifugal treatment by the centrifuge and a slag processing unit located downstream of the solid phase receiving unit.

[0015] In order to discharge the sewage from the coalescence filter, the first coalescence filter also has a first sewage outlet, which is connected to the first sewage pipeline. The second coalescence filter also has a second sewage outlet, which is connected to the second sewage pipeline. The third coalescence filter also has a third sewage outlet, which is connected to the third sewage pipeline.

[0016] In order to discharge the sewage of the centrifuge, the centrifuge also has a fourth sewage outlet, and the fourth sewage outlet is connected to a fourth sewage pipeline.

[0017] Generally, the centrifuge can be any centrifugal separation device in the prior art that can separate liquid and solid phases. Preferably, in order to ensure the centrifugal effect and efficiency, the centrifuge is a disc centrifuge.

[0018] Compared with the prior art, the utility model has the following advantages: after the quench water of the ethylene device is filtered through the multi-stage filter of the coalescing filter unit, the content of micro coke in the quench water can be greatly reduced, reducing the frequency of cleaning the main filter, thereby effectively reducing the risk of blockage of the quench water heat exchanger and achieving safe and stable production. On the other hand, after the sewage generated by the coalescing filter unit is centrifuged in the centrifuge, the water phase and the oil phase will be sent back to the quench water tower for recycling, and the water content of the slag phase will be significantly reduced, thereby saving the cost of three waste treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a flow chart of a quench water treatment system for an ethylene plant according to an embodiment of the present utility model. DETAILED DESCRIPTION

[0020] The present invention will be described in further detail below in conjunction with the accompanying drawings.

[0021] In the specification and claims of the present invention, terms indicating directions, such as "front", "rear", "up", "down", "left", "right", "side", "top", "bottom", etc., are used to describe various exemplary structural parts and elements of the present invention, but these terms are used here only for the purpose of convenience of description and are determined based on the exemplary orientations shown in the accompanying drawings. Since the embodiments disclosed in the present invention can be arranged in different directions, these terms indicating directions are only used as explanations and should not be regarded as limitations. For example, "up" and "down" are not necessarily limited to directions opposite to or consistent with the direction of gravity.

[0022] Figure 1 A preferred embodiment of the quench water treatment system for an ethylene device of the utility model is shown. The quench water treatment system for an ethylene device comprises a coalescing and filtering unit and a centrifugal unit.

[0023] The coalescence filter unit includes a first coalescence filter 11, a second coalescence filter 12 and a third coalescence filter 13 which are connected in sequence. In order to achieve graded filtration and improve filtration efficiency, the first coalescence filter 11, the second coalescence filter 12 and the third coalescence filter 13 all include a coalescence filter element 10, and the mesh numbers of the coalescence filter elements 10 of the first coalescence filter 11, the second coalescence filter 12 and the third coalescence filter 13 are increased in sequence. Specifically, the mesh number of the coalescence filter element of the first coalescence filter 11 is 1000 mesh, the mesh number of the coalescence filter element of the second coalescence filter 12 is 3000 mesh, and the mesh number of the coalescence filter element of the third coalescence filter 13 is 5000 mesh. The structure and filtration principle of the coalescence filter and its coalescence filter element are all prior art and will not be repeated here.

[0024] The first coalescing filter 11 has a first quenching water outlet 111, a first concentrated sewage outlet 112 and a first sewage outlet 113, the second coalescing filter 12 has a second quenching water outlet 121, a second concentrated sewage outlet 122 and a second sewage outlet 123, and the third coalescing filter 13 also has a third quenching water outlet 131, a third concentrated sewage outlet 132 and a third sewage outlet 133. The inlet of the first coalescing filter 11 is connected to a quenching water inlet pipeline 31 for conveying quenching water. The first quenching water outlet 111 of the first coalescing filter 11 is connected to the second coalescing filter 12 through a pipeline, and the second quenching water outlet 121 of the second coalescing filter 12 is connected to the inlet of the third coalescing filter 13. The third quenching water outlet 131 of the third coalescing filter 13 is connected to the first liquid return pipeline 32, so that the filtered quenching water is returned to the quenching water tower. The first sewage outlet 113 of the first coalescing filter 11 is connected to the first sewage pipeline 35, the second sewage outlet 123 of the second coalescing filter 12 is connected to the second sewage pipeline 36, and the third sewage outlet 133 of the third coalescing filter 13 is connected to the third sewage pipeline 37. That is, the sewage generated during the filtration treatment of the first coalescing filter 11, the second coalescing filter 12 and the third coalescing filter 13 can be discharged through the corresponding sewage pipelines for centralized treatment.

[0025] The centrifugal unit includes a centrifuge 20, a solid phase receiving unit 24 and a slag treatment unit 25. The centrifuge 20 of this embodiment adopts a disc centrifuge 20. The centrifuge 20 has a liquid medium inlet 21, a liquid medium outlet 22 and a fourth sewage outlet 23. The liquid medium inlet 21 is connected to the first concentrated sewage outlet 112 of the first coalescing filter 11, the second concentrated sewage outlet 122 of the second coalescing filter 12, and the third concentrated sewage outlet 132 of the third coalescing filter 13. The liquid medium outlet 22 is connected to the second liquid return pipeline 33, which is used to return the quenching water after centrifugal treatment to the quenching water tower. The fourth sewage outlet 23 of the centrifuge 20 is connected to the fourth sewage pipeline 38, and the sewage generated during the centrifugal treatment process can be discharged through the corresponding sewage pipeline for centralized treatment.

[0026] The solid phase receiving unit 24 is used to receive the solid phase medium after centrifugation by the centrifuge 20, and the slag processing unit 25 is located downstream of the solid phase receiving unit 24 and is used to process the slag. The solid phase receiving unit 24 and the slag processing unit 25 can also adopt existing conventional solid phase receiving devices and slag processing equipment, which will not be described in detail here.

[0027] The coalescing filter elements of the first coalescing filter 11, the second coalescing filter 12 and the third coalescing filter 13 of the present embodiment are also connected to the external ventilation pipeline 34, and the external ventilation pipeline 34 is connected to the gas source. The gas source (generally nitrogen or cracking gas) is distributed through the distributor inside the filter to evenly generate tiny bubbles. The bubbles and the filter element can separate the coke powder more efficiently.

[0028] In order to facilitate the cleaning of the coalescing filter, the coalescing filter elements 10 of the first coalescing filter 11, the second coalescing filter 12 and the third coalescing filter 13 are also connected to an external backwashing water pipeline 39, and the water of the backwashing pipeline 39 comes from the process water treatment unit.

[0029] After the quench water of the ethylene device of this embodiment is filtered through the multi-stage filter of the coalescing and filtering unit, the content of micro coke in the quench water can be greatly reduced, reducing the frequency of cleaning the main filter, thereby effectively reducing the risk of blockage of the quench water heat exchanger and achieving safe and stable production. On the other hand, after the sewage generated by the coalescing and filtering unit is centrifuged in the centrifuge 20, the water phase and the oil phase will be sent back to the quench water tower for recycling, and the water content of the slag phase will be significantly reduced, thereby saving the cost of three waste treatment.

Claims

1. A quench water treatment system for an ethylene plant, characterized in that include: A coalescence filtration unit, comprising a first coalescence filter (11), a second coalescence filter (12) and a third coalescence filter (13) connected in sequence, wherein the inlet of the first coalescence filter (11) is connected to a quench water inlet pipeline (31) for conveying quench water, the first coalescence filter (11) also has a first quench water outlet (111) and a first concentrated sewage outlet (112), the second coalescence filter (12) also has a second quench water outlet (121) and a second concentrated sewage outlet (122), the third coalescence filter (13) also has a third quench water outlet (131) and a third concentrated sewage outlet (132), the first quench water outlet (111) is connected to the inlet of the second coalescence filter (12), the second quench water outlet (121) is connected to the inlet of the third coalescence filter (13), and the third quench water outlet (131) is connected to a first liquid return pipeline (32) for returning filtered quench water to a quench water tower; The centrifugal unit comprises a centrifuge (20), wherein the centrifuge (20) has a liquid medium inlet (21) and a liquid medium outlet (22), wherein the liquid medium inlet (21) is connected to the first concentrated wastewater outlet (112), the second concentrated wastewater outlet (122), and the third concentrated wastewater outlet (132), and the liquid medium outlet (22) is connected to a second liquid return pipeline (33) for returning quenching water after centrifugal treatment to a quenching water tower.

2. The quench water treatment system for an ethylene plant according to claim 1, characterized in that: The first coalescence filter (11), the second coalescence filter (12) and the third coalescence filter (13) all comprise coalescence filter elements, and the mesh sizes of the coalescence filter elements of the first coalescence filter (11), the second coalescence filter (12) and the third coalescence filter (13) increase in sequence.

3. The quench water treatment system for an ethylene plant according to claim 2, characterized in that: The mesh number of the coalescence filter element of the first coalescence filter (11) is 1000 mesh, the mesh number of the coalescence filter element of the second coalescence filter (12) is 3000 mesh, and the mesh number of the coalescence filter element of the third coalescence filter (13) is 5000 mesh.

4. The quench water treatment system for an ethylene plant according to claim 2, characterized in that: The first coalescing filter (11), the second coalescing filter (12) and the third coalescing filter (13) are also connected to an external ventilation line (34).

5. The quench water treatment system for an ethylene plant according to claim 2, characterized in that: The coalescing filter elements of the first coalescing filter (11), the second coalescing filter (12) and the third coalescing filter (13) are connected to an external backwashing water pipeline (39).

6. The quench water treatment system for an ethylene plant according to claim 1, characterized in that: The invention also comprises a solid phase receiving unit (24) for receiving the solid phase medium after centrifugal treatment by the centrifuge (20), and a slag processing unit (25) located downstream of the solid phase receiving unit (24).

7. The quench water treatment system for an ethylene plant according to any one of claims 1 to 6, characterized in that: The first coalescing filter (11) further comprises a first sewage outlet (113), the first sewage outlet (113) being connected to a first sewage outlet pipeline (35); the second coalescing filter (12) further comprises a second sewage outlet (123), the second sewage outlet (123) being connected to a second sewage outlet pipeline (36); the third coalescing filter (13) further comprises a third sewage outlet (133), the third sewage outlet (133) being connected to a third sewage outlet pipeline (37).

8. The quench water treatment system for an ethylene plant according to any one of claims 1 to 6, characterized in that: The centrifuge (20) also has a fourth sewage outlet (23), and the fourth sewage outlet (23) is connected to a fourth sewage pipeline (38).

9. The quench water treatment system for an ethylene plant according to any one of claims 1 to 6, characterized in that: The centrifuge (20) is a disc-type centrifuge (20).

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