Tail gas decarburization and purification system

Abstract

The utility model provides a tail gas decarburization purification system which comprises a water washing tower, a circulating gas-barren liquor heat exchanger, a CO2 absorption tower, a purifier separator, a rich liquor flash drum, a pressurized regeneration tower, a regeneration system and a separation system, and the outlet of the water washing tower is communicated with a top pipeline of the circulating gas-barren liquor heat exchanger; an outlet of the circulating gas-barren liquor heat exchanger is connected with an inlet of a CO2 absorption tower, a gas phase of tail gas passing through the CO2 absorption tower flows into a purifier separator, a liquid phase of the tail gas flows into a rich liquor flash drum, an outlet of the rich liquor flash drum is connected with a regeneration system pipeline, and the tail gas passing through a regeneration system is separated by a separation system and then is discharged; and an inlet and an outlet of the semi-barren liquor pump are respectively communicated with the regeneration system and the CO2 absorption tower through pipelines. According to the tail gas decarburization purification system, decarburization operation is carried out through semi-barren liquor circulation, the number of devices is reduced, the device process is simplified, online non-stop overhaul of the devices can be achieved, and long-period stable operation of the system is effectively guaranteed.

Description

Technical Field

[0001] The utility model relates to the technical field of Fischer-Tropsch synthesis, and particularly relates to a tail gas decarbonization and purification system. Background Art

[0002] The hot potassium carbonate decarbonization process is a supporting technology for the F-T synthesis process, and its function is to remove part of the CO in the F-T synthesis circulation loop 2 from the recycle gas to ensure that the Fischer-Tropsch reaction reaches the designed conversion depth. The hot potassium carbonate method belongs to the chemical absorption method.

[0003] During the absorption process, the synthesis tail gas from Fischer-Tropsch synthesis is washed by a water wash tower and then enters the absorption tower for absorption. The decarbonized and purified gas at the top of the tower is cooled and separated and then sent to the Fischer-Tropsch synthesis and tail gas treatment device. The rich liquid at the bottom of the tower is flashed in a rich liquid flash tank and then enters a regeneration system composed of a pressure regeneration tower, an atmospheric pressure regeneration tower, a subsonic ejector, and a lean liquid flash tank. The regenerated lean liquid and semi-lean liquid are pumped into the absorption tower for cyclic absorption. The absorption tower is provided with three streams of absorbents, cold lean liquid, hot lean liquid, and semi-lean liquid. The semi-lean liquid comes from the atmospheric pressure regeneration tower and is pressurized by a semi-lean liquid pump and sent to the middle part of the absorption tower. The semi-lean liquid accounts for 67% of the total absorbent. The lean liquid comes from the lean liquid flash tank and is pressurized by a lean liquid pump and sent to the absorption tower. Part of the lean liquid enters the upper and middle parts of the absorption tower, and part of the lean liquid enters the top of the absorption tower after being cooled. The lean liquid accounts for 23% of the total absorbent. The synthesis tail gas enters from the lower section of the absorption tower and contacts the semi-lean liquid and the lean liquid in a countercurrent manner to achieve the purpose of decarbonization.

[0004] However, when the decarbonization load decreases, the absorption tower of the decarbonization device is provided with three streams of absorbents, cold lean liquid, hot lean liquid, and semi-lean liquid, and one lean liquid pump and two semi-lean liquid pumps are in operation. The operation process is complex, and long-term operation will increase the operation cost, which is not conducive to the energy conservation and consumption reduction of the device.

[0005] Therefore, in the prior art, there are technical problems that when the decarbonization load decreases, the absorption operation process of the three streams of absorbents is complex, the operation cost is increased, and it is not conducive to energy conservation and consumption reduction. Summary of the Utility Model

[0006] The main purpose of the utility model is to provide a tail gas decarbonization and purification system to solve the technical problems in the prior art that when the decarbonization load decreases, the absorption operation process of the three streams of absorbents is complex, the operation cost is increased, and it is not conducive to energy conservation and consumption reduction.

[0007] To achieve the above purpose, according to one aspect of the utility model, a tail gas decarbonization and purification system is provided, including a water wash tower, a recycle gas-lean liquid heat exchanger, CO 2An absorption tower, a purifier separator, a rich liquid flash tank, a regeneration system, and a separation system. Among them, the outlet of the water washing tower is connected to the top pipeline of the recycle gas-lean liquid heat exchanger, and the outlet of the recycle gas-lean liquid heat exchanger is connected to the inlet of the 2 absorption tower. The tail gas flows into the purifier separator after passing through the 2 absorption tower, and the liquid phase flows into the rich liquid flash tank. The outlet of the rich liquid flash tank is connected to the pipeline of the regeneration system. The tail gas passing through the regeneration system is separated by the separation system and then discharged; the inlet and outlet of the semi-lean liquid pump are respectively connected to the regeneration system and the 2 absorption tower pipeline.

[0008] Furthermore, the regeneration system includes a pressure regeneration tower and an atmospheric pressure regeneration tower. The outlet of the rich liquid flash tank is connected to the inlet of the pressure regeneration tower. There is a pipeline connection between the pressure regeneration tower and the atmospheric pressure regeneration tower. The outlet of the atmospheric pressure regeneration tower is connected to the pipeline of the inlet of the semi-lean liquid.

[0009] Furthermore, the upper middle part of the pressure regeneration tower is connected to the atmospheric pressure regeneration tower through two pipelines respectively, and the bottom of the pressure regeneration tower is connected to the atmospheric pressure regeneration tower through a pipeline.

[0010] Furthermore, the regeneration system further includes a steam boiling device, and the steam boiling device is respectively located at the bottoms of the pressure regeneration tower and the atmospheric pressure regeneration tower.

[0011] Furthermore, the regeneration system further includes a regenerated gas ejector, and the regenerated gas ejector is connected to the outlet at the top of the pressure regeneration tower and the outlet at the top of the atmospheric pressure regeneration tower.

[0012] Furthermore, a first air cooler and a gas-liquid separator are provided at the outlet of the atmospheric pressure regeneration tower. The tail gas is cooled by the first air cooler and then separated by the gas-liquid separator and then enters the regenerated gas ejector.

[0013] Furthermore, a second air cooler is further included. The tail gas passing through the 2 absorption tower enters the purifier separator after passing through the second air cooler.

[0014] Furthermore, the separation system includes an injection gas separator, a regenerated gas air cooler, and a regenerated gas separator. Among them, the tail gas discharged from the regenerated gas ejector enters the regenerated gas air cooler for cooling after passing through the injection gas separator. The cooled exhaust gas enters the regenerated gas separator, and the gas after separating the condensed water enters the discharge.

[0015] Furthermore, the separation system further includes a pressurizing device, and the gas after separating the condensed water enters the discharge after being pressurized by the pressurizing device.

[0016] Furthermore, the pressurizing device is a compressor or a blower.

[0017] Applying the technical solution of the present utility model, decarbonization operation is carried out by semi-lean liquid circulation, which reduces the number of equipment, simplifies the device process, makes the operation more convenient, the lean liquid flash tank can be handed over online, and the important equipment of the device can be overhauled online without stopping, which can ensure the long-term stable operation of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The specification drawings forming a part of this application are used to provide a further understanding of the present utility model. The schematic embodiments of the present utility model and their descriptions are used to explain the present utility model and do not constitute an improper limitation to the present utility model. In the drawings:

[0019] Figure 1 The structural schematic diagram of the tail gas decarbonization and purification system according to the present utility model is shown.

[0020] Among them, the above-mentioned drawings include the following reference numerals:

[0021] 10, water washing tower; 20, recycle gas-lean liquid heat exchanger; 30, CO 2 absorption tower; 40, purifier separator; 50, rich liquid flash tank; 60, regeneration system; 61, pressure regeneration tower; 62, atmospheric regeneration tower; 70, semi-lean liquid pump; A, sucked gas; B, purified gas; C, flash steam; D, regeneration tail gas. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The present utility model will be described in detail below with reference to the drawings and in conjunction with the embodiments.

[0023] It should be pointed out that unless otherwise specified, all technical and scientific terms used in this application have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs.

[0024] In the present utility model, unless otherwise stated, the orientation words such as "upper, lower, top, bottom" are usually in the direction shown in the drawings, or in the vertical, perpendicular or gravitational direction of the component itself; similarly, for the sake of understanding and description, "inside, outside" refer to the inside and outside relative to the contour of each component itself, but the above orientation words do not limit the present utility model.

[0025] In order to solve the technical problems existing in the prior art that when the decarbonization load decreases, the absorption operation process of three absorbents is complex, the operation cost is increased, and it is not conducive to energy conservation and consumption reduction, the present utility model provides a tail gas decarbonization and purification system.

[0026] As Figure 1As shown in the figure, the utility model provides a tail gas decarbonization and purification system, which includes a water washing tower 10, a recycle gas-lean liquid heat exchanger 20, a CO 2 absorption tower 30, a purifier separator 40, a rich liquid flash tank 50, a regeneration system 60 and a separation system. Among them, the outlet of the water washing tower 10 is connected to the top pipeline of the recycle gas-lean liquid heat exchanger 20. The oxygen-containing organic matter in the recycle gas is washed by the water washing tower 10. The outlet of the recycle gas-lean liquid heat exchanger 20 is connected to the inlet of the CO 2 absorption tower 30. The recycle gas is heated up through heat exchange in the recycle gas-lean liquid heat exchanger 20 and then enters the CO 2 absorption tower 30. After the carbon dioxide is removed by the CO 2 absorption tower 30, the gas phase flows into the purifier separator 40, and the liquid phase flows into the rich liquid flash tank 50. The outlet of the rich liquid flash tank 50 is connected to the pipeline of the regeneration system 60. The tail gas passing through the regeneration system 60 is separated by the separation system and then discharged; the inlet and outlet of the semi-lean liquid pump 70 are respectively connected to the pipeline of the regeneration system 60 and the CO 2 absorption tower 30.

[0027] Applying the tail gas decarbonization and purification system of the utility model, the semi-lean liquid circulation is adopted for decarbonization operation, reducing the number of equipment, simplifying the device process, making the operation more convenient. The lean liquid flash tank can be taken out online, and the important equipment in the system can be overhauled online without stopping, thus ensuring the long-term stable operation of the tail gas decarbonization and purification system.

[0028] Further, the regeneration system 60 includes a pressure regeneration tower 61 and an atmospheric pressure regeneration tower 62. The outlet of the rich liquid flash tank 50 is connected to the inlet of the pressure regeneration tower 61. The pressure regeneration tower 61 and the atmospheric pressure regeneration tower 62 are connected by pipelines. The outlet of the atmospheric pressure regeneration tower 62 is connected to the pipeline of the semi-lean liquid inlet; thus, the rich liquid after the first-stage flash enters the regeneration system 60 for regeneration.

[0029] Specifically, the upper middle part of the pressure regeneration tower 61 is connected to the atmospheric pressure regeneration tower 62 through two pipelines respectively, and the bottom of the pressure regeneration tower 61 is connected to the atmospheric pressure regeneration tower 62 through a pipeline; the rich liquid after the first-stage flash is in the flash section at the top of the pressure regeneration tower 61 and undergoes a second-stage flash at a pressure of 0.1 MPa. Most of the flash gas is CO 2 and water vapor.

[0030] In order to ensure the pressure and temperature inside the regeneration system 60, the regeneration system 60 further includes steam boiling heaters, which are respectively located at the bottoms of the pressure regeneration tower 61 and the atmospheric pressure regeneration tower 62. Thus, by respectively setting the steam boiling heaters, the separate control of the pressure regeneration tower 61 and the atmospheric pressure regeneration tower 62 can be realized.

[0031] In another embodiment of the present utility model, the regeneration system 60 further includes a regeneration gas ejector, which is communicated with the outlets at the tops of the pressurized regeneration tower 61 and the atmospheric pressure regeneration tower 62, so as to utilize the high-pressure gas in the pressurized regeneration tower 61. Among them, the regeneration gas ejector can be, for example, a subsonic regeneration gas ejector. The regeneration gas with a pressure of 0.10 MPa coming out of the top of the pressurized regeneration tower 61 is used as the motive gas and enters the subsonic regeneration gas ejector to suck the sucked gas coming out of the top of the atmospheric pressure regeneration tower 62, so that the pressure at the top of the atmospheric pressure regeneration tower 62 is maintained at 0.012 MPa.

[0032] To give full play to the efficiency of the regeneration gas ejector, a first air cooler and a gas-liquid separator are arranged at the outlet of the atmospheric pressure regeneration tower 62. The tail gas is cooled by the first air cooler and then enters the regeneration gas ejector after being separated by the gas-liquid separator; specifically, by arranging the first air cooler at the outlet of the atmospheric pressure regeneration tower 62, the sucked gas is cooled to 85 °C and then enters the gas-liquid separator. After the condensed water is separated by the gas-liquid separator, the sucked gas enters the regeneration gas ejector. Such an arrangement is beneficial to reducing the pressure at the top of the atmospheric pressure regeneration tower 62.

[0033] In another embodiment of the present utility model, the separation system includes a jet gas separator, a regeneration gas air cooler and a regeneration gas separator. The tail gas discharged from the regeneration gas ejector enters the regeneration gas air cooler for cooling after passing through the jet gas separator, and the cooled exhaust gas enters the regeneration gas separator. The gas after separating the condensed water enters the relief. Specifically, all the regeneration gas coming out of the regeneration gas ejector enters the regeneration gas air cooler for cooling to 50 °C after being separated by the jet gas separator, and then enters the regeneration gas separator. After the condensed water is separated by the regeneration gas separator, it enters the relief system. The condensed water separated from the bottom of the regeneration gas separator goes to the underground tank.

[0034] Furthermore, the separation system further includes a pressurizing device. The gas after separating the condensed water enters the relief after being pressurized by the pressurizing device, so as to be able to increase the pressure of the gas entering the relief system and ensure the timely relief of the gas. Preferably, the pressurizing device can be selected as a compressor, a blower, etc., and the present utility model does not make specific limitations on this.

[0035] In another embodiment of the present utility model, the tail gas decarbonization and purification system further includes a second air cooler, and the second air cooler is arranged downstream of the CO 2 absorption tower 30 of the absorption tower, and the tail gas discharged from the CO 2 absorption tower 30 enters the purifier separator 40 after passing through the second air cooler; specifically, after the second air cooler cools the CO 2The tail gas discharged from the absorption tower 30 is cooled. After being cooled to 50°C, the tail gas enters the purified gas separator and is countercurrently contacted with the washing water pressurized by the purified gas water washing pump. The condensed water separated at the bottom of the tower is sent to the rich liquid flash tank 50 and the underground tank. Part of the decarbonized purified gas at the top is returned to the Fischer-Tropsch synthesis unit, and the rest of the purified gas is sent to the low-temperature oil washing unit.

[0036] In the working process of the tail gas decarbonization purification system provided by the utility model, the 40°C, 2.62MPa Fischer-Tropsch synthesis tail gas from the Fischer-Tropsch synthesis unit enters the circulating gas water washing tower 10, and after washing the oxygen-containing organic matter in the water washing tower 10, enters the circulating gas lean liquid heat exchanger to exchange heat with part of the lean liquid. After the heat exchange, the temperature rises to about 90°C, and enters the bottom of the absorption tower. In the tower, it countercurrently contacts with the cold lean liquid and hot lean liquid entering the tower from the top of the tower and the semi-lean liquid entering the tower from the middle of the tower to remove carbon dioxide, so that CO in the purified gas at the top of the tower outlet is reduced to 0.5%. 2 The content drops to ≤2 mol%, and after being cooled to 50°C by the second air cooler, it enters the purified gas separator, and is countercurrently contacted with the washing water pressurized by the purified gas water washing pump. The condensed water separated at the bottom of the tower is sent to the rich liquid flash tank 50 and the underground tank, and a part of the decarbonized purified gas at the top is returned to the Fischer-Tropsch synthesis unit, and the rest of the purified gas is sent to the low-temperature oil washing unit.

[0037] The rich liquid from the hydraulic turbine enters the rich liquid flash tank 50 for first-stage flash evaporation, flashing out a portion of process gas, most of which is CO, H 2 The flash gas is washed with washing water, cooled and separated, and then sent to the fuel gas network. The rich liquid after the first flash evaporation enters the flash evaporation section at the top of the pressurized regeneration tower 61, and the second flash evaporation is carried out at a pressure of 0.1MPa. Most of the flash gas is CO 2 and water vapor. The flash solution is divided into two parts, of which about 4000m 3 / h of rich liquid is introduced into the top and middle gas stripping section of the atmospheric pressure regeneration tower 62 through the two upper and middle pipelines.

[0038] The regeneration gas with a pressure of 0.10MPa coming out from the top of the pressurized regeneration tower 61 is used as the power gas and enters the subsonic regeneration gas ejector to draw the sucked gas coming out from the top of the atmospheric pressure regeneration tower 62, so that the top pressure of the atmospheric pressure regeneration tower 62 is maintained at 0.012MPa. All the regeneration gas coming out of the regeneration gas ejector is separated by the ejector gas separator and then enters the first air cooler to be cooled to 50°C and then enters the regeneration gas separator. After the condensed water is separated, it is pressurized by the blower to the discharge system, and the condensed water separated from the bottom of the regeneration gas separator is discharged to the underground tank.

[0039] During the operation of the tail gas decarbonization and purification system provided by the present utility model, when the foam height analysis of the lean liquid and semi-lean liquid is unqualified, or after the pressure drop alarm of each tower, the metering pump should be started to add defoaming agent. When the alkalinity or pentavalent vanadium concentration in the solution is lower than the control value, potassium carbonate and vanadium pentoxide solutions need to be prepared in the underground tank and sent to the regeneration tower for liquid supplement through the condensate pump. The drained condensate from each equipment enters the underground tank, and the condensate is sent to the regeneration tower for water replenishment through the condensate pump. Before startup, potassium carbonate solution is prepared in the underground tank and sent to the solution storage tank through the condensate pump; then it is pumped into the pressurized regeneration tower 61 and the atmospheric pressure regeneration tower 62 through the solution pump.

[0040] From the above description, it can be seen that the above embodiments of the present utility model achieve the following technical effects:

[0041] 1. Effectively solve the technical problems that when the decarbonization load decreases, the absorption operation process of the three absorbents is complex, increasing the operation cost and being unfavorable for energy conservation and consumption reduction;

[0042] 2. Simplify the device process, make the operation more convenient, and can achieve on-line maintenance without stopping the vehicle, ensuring the long-term stable operation of the system.

[0043] Obviously, the above-described embodiments are only a part of the embodiments of the present utility model, rather than all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present utility model.

[0044] 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 present application. 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 "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0045] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein.

[0046] The above are only the preferred embodiments of the present utility model and are not intended to limit the present utility model. For those skilled in the art, the present utility model can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present utility model shall be included in the protection scope of the present utility model.

Claims

1. A tail gas decarbonization purification system, characterized in that: It includes a water washing tower, a circulating gas-lean liquid heat exchanger, a CO2 absorption tower, a purifier separator, a rich liquid flash tank, a regeneration system and a separation system, wherein the outlet of the water washing tower is connected to the top pipeline of the circulating gas-lean liquid heat exchanger, the outlet of the circulating gas-lean liquid heat exchanger is connected to the inlet of the CO2 absorption tower, the gas phase of the tail gas after passing through the CO2 absorption tower flows into the purifier separator, and the liquid phase flows into the rich liquid flash tank, the outlet of the rich liquid flash tank is connected to the regeneration system pipeline, and the tail gas passing through the regeneration system is separated by the separation system and then discharged; the inlet and outlet of the semi-lean liquid pump are respectively connected to the regeneration system and the CO2 absorption tower pipeline.

2. The tail gas decarbonization purification system according to claim 1, characterized in that: The regeneration system includes a pressurized regeneration tower and a normal pressure regeneration tower, the outlet of the rich liquid flash tank is connected to the inlet of the pressurized regeneration tower, the pressurized regeneration tower and the normal pressure regeneration tower are connected by a pipeline, and the outlet of the normal pressure regeneration tower is connected to the inlet pipeline of the semi-lean liquid.

3. The tail gas decarbonization purification system according to claim 2, characterized in that: The upper middle part of the pressurized regeneration tower is connected to the normal pressure regeneration tower through two pipelines respectively, and the bottom of the pressurized regeneration tower is connected to the normal pressure regeneration tower through a pipeline.

4. The tail gas decarbonization purification system according to claim 2, characterized in that: The regeneration system further comprises a steam boiler, which is respectively located at the bottom of the pressurized regeneration tower and the normal pressure regeneration tower.

5. The tail gas decarbonization purification system according to claim 2, characterized in that: The regeneration system further comprises a regeneration gas injector, which is communicated with an outlet at the top of the pressurized regeneration tower and an outlet at the top of the normal pressure regeneration tower.

6. The tail gas decarbonization purification system according to claim 5, characterized in that: A first air cooler and a gas-liquid separator are provided at the outlet of the atmospheric pressure regeneration tower. The tail gas is cooled by the first air cooler and then separated by the gas-liquid separator before entering the regeneration gas ejector.

7. The tail gas decarbonization purification system according to any one of claims 1 to 6, characterized in that: It also includes a second air cooler, and the tail gas from the CO2 absorption tower enters the purifier separator after passing through the second air cooler.

8. The tail gas decarbonization purification system according to any one of claims 1 to 6, characterized in that: The separation system includes an ejector gas separator, a regeneration gas air cooler and a regeneration gas separator, wherein the tail gas discharged from the regeneration gas ejector passes through the ejector gas separator and then enters the regeneration gas air cooler for cooling, the cooled exhaust gas enters the regeneration gas separator, and the gas after separation of condensed water enters the discharge.

9. The tail gas decarbonization purification system according to claim 8, characterized in that: The separation system also includes a pressurizing device, and the gas after separation of condensed water is pressurized by the pressurizing device and then discharged.

10. The tail gas decarbonization purification system according to claim 9, characterized in that: The pressurizing device is a compressor or a blower.

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