Oil skimming structure at bottom of desulfurization tower

Abstract

An oil skimming structure at the bottom of a desulfurization tower, the oil skimming structure comprises: a tower body, wherein a raw gas inlet and a rich liquid outlet are provided in the bottom of the tower body, and multiple layers of trays are provided in the tower; a flow guide assembly, which is arranged at the bottom of the tower body and comprises a plurality of liquid-receiving disks and flow guide pipes, wherein the liquid-receiving disks are arranged below the multiple layers of trays and configured to receive a rich liquid, the plurality of liquid-receiving disks are spaced apart from each other on a tower wall in a direction of the central axis of the tower body, the top ends of the flow guide pipes are in communication with a bottom liquid-receiving disk, and the bottom ends of the flow guide pipes extend below a liquid level at the bottom of the tower; and an oil skimming trough, which is arranged against the bottom wall of the tower, wherein the top of the oil skimming trough is open and is flush with a high liquid level at the bottom of the tower, and the oil skimming trough is provided with an oil outlet. After a tower-bottom inner component of this solution is provided, the liquid level at the bottom of the desulfurization tower can be stably increased or reduced, thus reducing the impact of liquid level fluctuation on the control of a downstream regulation valve. In addition, an oil skimming operation can be easily and safely performed, the risk of cross-pressures possibly caused by a conventional oil skimming operation is avoided, and interface level control is not needed.

Description

An oil skimming structure at the bottom of a desulfurization tower Technical Field

[0001] The utility model belongs to the field of desulfurization tower bottom internal component structure arrangement, in particular to an oil skimming structure at the bottom of a desulfurization tower. Background Art

[0002] During the oil refining process, the raw gas of the desulfurization tower inevitably carries a small amount of light hydrocarbons or oil. Such hydrocarbons and oil accumulate too much and float on the upper layer of the rich amine liquid at the bottom of the tower. Therefore, the liquid at the bottom of the desulfurization tower must be skimmed regularly to keep the rich amine liquid at the bottom of the tower clean.

[0003] Although conventional desulfurization towers are equipped with oil skimmers, their operation is not very convenient. This is because the light oil carried in the gas has a lower density than the amine liquid, so the light oil floats above the surface of the rich amine liquid at the bottom of the tower. Most oil skimmer outlets are located at 80% of the liquid level plate. When skimming is performed under the guidance of an interface meter, cross-pressure is easily generated, resulting in accidents.

[0004] In common desulfurization tower bottom designs, the liquid level at the bottom of the desulfurization tower generally fluctuates greatly. The main reason is that the medium falling from the last tower plate continuously impacts the liquid surface. At the same time, since there is no obstruction to the falling of materials, and the light oil accumulates above the liquid surface at the bottom of the tower, the amine liquid at the bottom of the tower is prone to produce a large amount of foam. In severe cases, this foam rises along the tower, causing gas-carrying liquid and amine leakage accidents, which can easily cause the upper part of the bottom liquid level to be in a foamy state, resulting in a false liquid level, which in turn affects downstream operations and leads to poor desulfurization effect of the desulfurization tower. Technical Solutions

[0005] In response to the above technical problems, the purpose of the present utility model is to provide an oil skimming structure at the bottom of a desulfurization tower. After the bottom internals of this scheme are set, the liquid level at the bottom of the desulfurization tower can be stably increased or decreased, reducing the impact of liquid level fluctuations on the control of the downstream regulating valve; at the same time, the oil skimming operation can be carried out conveniently and safely, avoiding the risk of cross-pressure caused by conventional oil skimming operations, and there is no need to set up an interface level meter.

[0006] In order to achieve the above purpose, the technical solutions adopted by this utility model are as follows:

[0007] An oil skimming structure at the bottom of a desulfurization tower, comprising:

[0008] The tower body has a raw gas inlet and a rich liquid outlet at its bottom, and multiple layers of trays are arranged inside the tower;

[0009] The flow guide assembly is provided at the bottom of the tower body and includes a plurality of liquid receiving pans and flow guide pipes. The liquid receiving pans are provided below the multiple tower plates and are used to receive the rich liquid. The plurality of liquid receiving pans are spaced apart and distributed on the tower wall along the central axis of the tower body. The top end of the flow guide pipe is connected to the bottom liquid receiving pan, and the bottom end extends below the liquid level at the bottom of the tower.

[0010] The skimmer is arranged on the bottom wall of the tower, the top of the skimmer is open and flush with the high liquid level at the bottom of the tower, and the skimmer is provided with an oil outlet.

[0011] In some technical solutions, the width of the disk surface of the multiple liquid receiving pans increases layer by layer from top to bottom, and wall panels are arranged at the edge of the liquid receiving pans. Between two adjacent liquid receiving pans, the upper end height of the wall panel of the lower liquid receiving pan is greater than the top end height of the wall panel of the upper liquid receiving pan. A liquid drop channel is formed between the wall panels of adjacent liquid receiving pans, the liquid receiving pans and the guide pipes.

[0012] In some technical solutions, there are two liquid receiving trays, namely an upper liquid receiving tray and a lower liquid receiving tray. One side of the two liquid receiving trays is set against the tower wall, and the wall panel is vertically set on the other side. The wall panel of the lower liquid receiving tray is located on the outside of the wall panel of the upper liquid receiving tray.

[0013] In some technical solutions, the flow guide assembly is further provided with a downcomer, which is connected to the bottom tower plate and is used to transfer the rich liquid to the top liquid receiving tray.

[0014] In some technical solutions, the bottom end of the draft tube extends below the normal liquid level at the bottom of the tower. The liquid between the normal liquid level and the low liquid level is rich liquid, the liquid between the normal liquid level and the high liquid level is partially emulsified rich liquid, and the liquid above the normal liquid level is a small amount of light hydrocarbons and oil.

[0015] Some technical solutions also include a liquid level detection component, which includes a first liquid level gauge located at the bottom of the tower for rich liquid level detection and / or a second liquid level gauge located in the skimming tank for light oil level detection. The first liquid level gauge and the second liquid level gauge are both provided with an upper liquid level gauge and a lower liquid level gauge for respectively detecting high and low liquid level changes.

[0016] In some technical solutions, a baffle is provided above the top of the skimmer tank, and the width of the baffle is not less than the width of the top opening of the skimmer tank.

[0017] In some technical solutions, the bottom of the skimmer is at the same height as the low liquid level at the bottom of the tower.

[0018] In some technical solutions, the rich liquid outlet is connected to a drainage pipeline, and a regulating valve is provided on the drainage pipeline.

[0019] In some technical solutions, multiple layers of tower plates are arranged in parallel and evenly spaced along the central axis of the tower body on the tower wall. Between two adjacent tower plates, a first gap is left between one side of the upper tower plate and the tower wall, and a second gap is left between the other side of the lower tower plate and the tower wall. The first gap and the second gap both form liquid passages. Beneficial effects

[0020] The utility model guides the rich liquid to below the normal liquid level in the tower through the combination of a multi-layer liquid receiving tray and a guide pipe, so as to improve the phenomenon of unstable liquid level at the bottom of the desulfurization tower caused by the impact of the falling medium, and can more realistically display the liquid level at the bottom of the tower, so as to facilitate the downstream control of the discharge of the liquid at the bottom of the tower; at the same time, the stable change of the liquid level at the bottom of the tower is conducive to the stable stratification of the oil and water phases, and a small amount of floating light hydrocarbons and oil are removed through the skimming tank through the stable rise and fall of the liquid level at the bottom of the tower. The operation is convenient and safe, and the risk of cross pressure caused by conventional skimming operation is avoided, and there is no need to set an interface level meter. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following is a brief introduction to the drawings and their markings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] FIG1 is a schematic structural diagram of an oil skimming structure at the bottom of a desulfurization tower according to an embodiment of the present invention;

[0023] FIG. 2 is a schematic diagram of the AA section of FIG. 1 .

[0024] The meanings of the symbols in the figure are as follows:

[0025] 11—first upper liquid level gauge, 12—first lower liquid level gauge, 2—oil skimmer, 3—drain pipe, 4—raw gas inlet, 51—second upper liquid level gauge, 52—second lower liquid level gauge, 6—draft guide pipe. Modes for Carrying Out the Invention

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the specific implementation methods of the present invention will be described below with reference to the accompanying drawings. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings and other implementation methods can be obtained based on these drawings without inventive work.

[0027] To simplify the drawings, only the parts relevant to the utility model are schematically shown in each figure; they do not represent the actual structure of the product. Furthermore, to simplify the drawings and facilitate understanding, in some figures, only one of the components with the same structure or function is schematically depicted or labeled. In this document, "one" not only means "only one" but also "more than one."

[0028] It should be further understood that the term "and / or" used in this specification and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0029] It should be noted that, unless otherwise specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they can refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediary; and internal communication between two components. Those skilled in the art will understand the specific meanings of these terms in this utility model based on the specific circumstances.

[0030] In addition, in the description of the present application, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0031] When the desulfurization tower is operating normally, the desulfurized gas enters the desulfurization tower from the bottom and moves upward, and the lean amine liquid injected from the top of the tower moves downward. The lean amine liquid and the sulfur-containing gas are fully in contact in the plate tower to react and desulfurize. The desulfurized gas is discharged from the top of the tower, and the rich amine liquid is extracted from the bottom of the tower.

[0032] During the oil refining process, the raw gas of the desulfurization tower inevitably carries a small amount of light hydrocarbons or oil. Such hydrocarbons and oil accumulate too much and float on the upper layer of the rich amine liquid at the bottom of the tower. Therefore, the liquid at the bottom of the desulfurization tower must be skimmed regularly to keep the rich amine liquid at the bottom of the tower clean.

[0033] In conventional desulfurization tower bottom designs, the liquid level at the bottom of the desulfurization tower generally fluctuates greatly. The main reason is that there is no obstruction to the falling of materials. The medium falling from the last tower plate continuously impacts the liquid in the tower bottom, and the liquid level gauge shows a false liquid level, which not only affects the control of the downstream regulating valve, but also makes the skimming operation more difficult. When the skimming operation is performed under the guidance of the interface level gauge, cross pressure is prone to occur, causing accidents.

[0034] According to the present invention, a desulfurization tower bottom skimming structure is proposed, as shown in Figures 1-2. It includes a tower body, a guide assembly, and a skimming tank 2. Rich amine liquid accumulates at the bottom of the tower body. The guide assembly guides the rich amine liquid produced after the desulfurization reaction to below the normal liquid level at the bottom of the tower. A small amount of light hydrocarbons and oil floating on the liquid is removed through the skimming tank 2, which is flush with the high liquid level at the bottom of the tower.

[0035] It should be noted that the stable liquid at the bottom of the desulfurization tower of the present invention can be divided into three layers, with the stratification interfaces being defined as a high liquid level HL, a normal liquid level NL, and a low liquid level LL. The liquid between the normal liquid level NL and the low liquid level LL is rich amine liquid, the liquid between the high liquid level HL and the normal liquid level NL is partially emulsified rich amine liquid, and the liquid above the high liquid level HL is a small amount of light hydrocarbons and oil. By modifying the internal components of the conventional desulfurization tower bottom, the present invention directs the rich amine liquid below the normal liquid level NL at the bottom of the tower, thereby preventing a strong impact on the bottom liquid, avoiding disturbance of the oil-emulsion mixture in the upper layer, shortening the oil stratification time, and reducing the emulsification phenomenon after the oil-water mixture.

[0036] In the above embodiment, the tower body is arranged in a vertical direction, and a raw gas inlet 4 and a rich liquid outlet are respectively provided at the bottom of the tower body, and a purified gas outlet and an amine liquid inlet are correspondingly provided at the top of the tower body. A plurality of tower plates are provided in the middle of the tower body, and the parallel multi-layer tower plates are evenly distributed on the tower wall along the central axis of the tower body. Between two adjacent tower plates, a first gap is left between one side of the upper tower plate and the tower wall, and a second gap is left between the other side of the lower tower plate and the tower wall. The first gap and the second gap both form liquid passages.

[0037] The above-mentioned diversion assembly is arranged at the bottom of the tower body, including several liquid receiving pans and diversion pipes 6. The liquid receiving pans are arranged below the multi-layer tower plates to receive the rich liquid. The multiple liquid receiving pans are arranged in parallel and distributed on the tower wall at intervals along the central axis of the tower body. The width of the multiple liquid receiving pans increases layer by layer from top to bottom. Wall panels are arranged on the edge of the liquid receiving pans. The top of the diversion pipe 6 is connected to the bottom liquid receiving pan, and the bottom end extends below the normal liquid level at the bottom of the tower. A liquid drop channel is formed between the wall panels of adjacent liquid receiving pans, the liquid receiving pans and the diversion pipe 6.

[0038] Specifically, there are two liquid receiving trays, namely the upper liquid receiving tray and the lower liquid receiving tray. One side of the two liquid receiving trays is set against the tower wall, and the other side is vertically provided with a wall panel. The wall panel of the lower liquid receiving tray is located outside the wall panel of the upper liquid receiving tray.

[0039] In this embodiment, a certain distance is provided between the two wall panels, allowing liquid in the upper receiving tray a to flow directly along this channel to the lower receiving tray b. The liquid medium carried between the two receiving trays flows directly along the flow guide pipe 6 connected to the lower receiving tray b to below the normal liquid level at the bottom of the tower, eliminating liquid level fluctuations caused by the downward flow of the liquid impacting the bottom of the tower.

[0040] In a preferred embodiment, the upper end height of the wall plate of the lower liquid receiving tray b of the double liquid receiving tray is greater than the top end height of the wall plate of the upper liquid receiving tray a. The height difference prevents the medium in the liquid receiving tray from overflowing and falling directly to the bottom of the tower.

[0041] In some specific embodiments, the flow guide assembly is further provided with a downcomer, which is in communication with the bottom tray and is used to transfer the rich liquid to the top tray.

[0042] In the above embodiment, the skimmer 2 is installed against the tower bottom wall. The bottom of the skimmer 2 is at the same level as the low liquid level LL at the bottom of the desulfurization tower and is sealed at the bottom. The tower wall at the bottom of the skimmer 2 is open, providing an oil outlet for an external pipeline. The top of the skimmer 2 is open and at the same level as the high liquid level HL at the bottom of the desulfurization tower. Preferably, a baffle is installed above the top of the skimmer 2. The width of the baffle is no less than the width of the top opening of the skimmer 2 to prevent a large influx of medium into the skimmer in the event of a tower tray leak.

[0043] The above embodiment also includes a liquid level detection assembly, comprising a first level gauge located at the bottom of the tower for detecting the level of the rich amine liquid and / or a second level gauge located within the skimmer 2 for detecting the level of the light oil. The first level gauge comprises a first upper level gauge 11 and a first lower level gauge 12, and the second level gauge comprises a second upper level gauge 51 and a second lower level gauge 52, respectively detecting changes in the high and low liquid levels. The rich liquid outlet is connected to a drain line 3, which is provided with a regulating valve. The on / off and opening of the regulating valve are precisely controlled based on the detection data from the first level gauge.

[0044] The stable change of the liquid level at the bottom of the tower of the utility model is conducive to the stable boundary between the oil and water phases. The light oil in the liquid at the bottom of the tower can float stably on the liquid surface at the bottom of the tower in a relatively concentrated manner. When skimming the oil, the liquid level of the tower bottom is raised to be flush with the edge of the skimming tank 2. At this time, the light oil and rich liquid will overflow into the skimming tank 2. The progress of the skimming can be observed by personnel or the start and stop of the skimming process can be controlled according to the detection data of the second liquid level meter.

[0045] In order to have a clearer understanding of the technical solution and technical effects of the present invention, the working process of the oil skimming structure at the bottom of the desulfurization tower of the present application is now described in detail with reference to Figures 1-2:

[0046] Sulfur-containing gas from upstream enters the desulfurization tower through feed gas inlet 4 and flows from bottom to top. Lean amine liquid enters from the top and descends through the tower trays. The two countercurrent streams form a concentration gradient, allowing for full contact and reaction. After the hydrogen sulfide in the gas is fully absorbed by the lean amine liquid, the desulfurized gas exits the top of the tower, while the rich amine liquid, which has absorbed the hydrogen sulfide, descends through the tower trays. When the rich amine liquid reaches the last tray, tray N in the figure, it is transferred by a downcomer to the upper receiving tray a of the improved double receiving tray of this application.

[0047] Due to the setting of the double liquid receiving pan baffles and the existence of the height difference (△h) between the two liquid receiving pan baffles, the rich amine liquid is directly injected into the normal liquid level (NL) at the bottom of the tower along the guide pipe 6, which will not cause impact on the liquid surface at the bottom of the desulfurization tower, resulting in fluctuations in the liquid level at the bottom of the tower and causing inaccurate measurement.

[0048] After the rich amine liquid is stably injected below the normal liquid level at the bottom of the desulfurization tower, the liquid level at the bottom of the tower rises steadily. After the bottom liquid level gauge truly displays the bottom liquid level, the downstream regulating valve controls the rich amine liquid to be discharged from the rich liquid outlet. The true display of the bottom liquid level can more accurately control the opening of the downstream valve.

[0049] At the same time, due to the difference in density between light oil and amine liquid, light oil floats more stably above the liquid surface at the bottom of the tower and intermittently enters the skimmer tank 2. According to the display of the second liquid level gauge in the skimmer tank 2, the light oil and the entrained rich amine liquid are skimmed off from the oil outlet.

[0050] After the descending liquid in the tower of the utility model passes through the double liquid receiving trays provided this time, it directly flows along the guide pipe 6 to the normal liquid level at the bottom of the tower. The liquid level at the bottom of the tower will not show a false liquid level, and can maintain a relatively stable change. It can be accurately displayed on the liquid level gauge, which is convenient for downstream control.

[0051] The stable change of the liquid level at the bottom of the tower of the utility model is conducive to the stable boundary between the oil and water phases. The skimming operation can be performed through the liquid level display in the skimming tank 2. This solution is safe and convenient, will not cause cross-pressure accidents, and does not require the installation of an interface level meter.

[0052] The above-described embodiments merely represent several implementation methods of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the scope of the present invention, and these modifications and improvements fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. An oil skimming structure at the bottom of a desulfurization tower, characterized in that: include: The tower body has a raw gas inlet and a rich liquid outlet at the bottom, and multiple layers of tower plates are arranged inside the tower; The flow guide assembly is arranged at the bottom of the tower body, and includes a plurality of liquid receiving trays and flow guide pipes. The liquid receiving trays are arranged below the multi-layer tower plates and are used to receive the rich liquid. The plurality of liquid receiving trays are spaced and distributed on the tower wall along the central axis of the tower body. The top end of the flow guide pipe is connected to the bottom liquid receiving tray, and the bottom end extends below the liquid level at the bottom of the tower. The skimmer is arranged on the bottom wall of the tower, the top of the skimmer is open and flush with the high liquid level at the bottom of the tower, and the skimmer is provided with an oil outlet.

2. The oil skimming structure at the bottom of the desulfurization tower according to claim 1, characterized in that: The width of the plate surface of the multiple liquid receiving pans increases layer by layer from top to bottom, and a wall panel is arranged at the edge of the liquid receiving pan. Between two adjacent liquid receiving pans, the upper end height of the wall panel of the lower liquid receiving pan is greater than the top end height of the wall panel of the upper liquid receiving pan. A liquid drop channel is formed between the wall panels of adjacent liquid receiving pans, the liquid receiving pans and the guide pipe.

3. The oil skimming structure at the bottom of the desulfurization tower according to claim 2, characterized in that: There are two liquid receiving trays, an upper liquid receiving tray and a lower liquid receiving tray. One side of the two liquid receiving trays is set against the tower wall, and the wall panel is vertically set on the other side. The wall panel of the lower liquid receiving tray is located on the outer side of the wall panel of the upper liquid receiving tray.

4. The oil skimming structure at the bottom of the desulfurization tower according to claim 1, characterized in that: The flow guide assembly is also provided with a downcomer, which is communicated with the bottom tower plate and is used to transfer the rich liquid to the top liquid receiving tray.

5. The oil skimming structure at the bottom of the desulfurization tower according to claim 1, characterized in that: The bottom end of the draft tube extends below the normal liquid level at the bottom of the tower. The liquid between the normal liquid level and the low liquid level is rich liquid, the liquid between the normal liquid level and the high liquid level is partially emulsified rich liquid, and the liquid above the normal liquid level is a small amount of light hydrocarbons and oil.

6. The oil skimming structure at the bottom of the desulfurization tower according to claim 1, characterized in that: It also includes a liquid level detection component, which includes a first liquid level gauge arranged at the bottom of the tower for rich liquid level detection and / or a second liquid level gauge arranged in the skimming tank for light oil level detection. The first liquid level gauge and the second liquid level gauge are both provided with an upper liquid level gauge and a lower liquid level gauge for respectively detecting high and low liquid level changes.

7. The oil skimming structure at the bottom of the desulfurization tower according to claim 1, characterized in that: A baffle is arranged above the top of the skimmer tank, and the width of the baffle is not less than the top opening width of the skimmer tank.

8. The oil skimming structure at the bottom of the desulfurization tower according to claim 1, characterized in that: The bottom of the skimmer is at the same height as the low liquid level at the bottom of the tower.

9. The oil skimming structure at the bottom of the desulfurization tower according to claim 1 or 6, characterized in that: The rich liquid outlet is connected to a liquid discharge pipeline, and a regulating valve is arranged on the liquid discharge pipeline.

10. The oil skimming structure at the bottom of the desulfurization tower according to claim 1, characterized in that: The parallel-arranged multi-layer tower plates are evenly spaced on the tower wall along the central axis of the tower body. Between two adjacent tower plates, a first gap is left between one side of the upper tower plate and the tower wall, and a second gap is left between the other side of the lower tower plate and the tower wall. The first gap and the second gap both form liquid passages.

Images