Plant and method for providing carbon dioxide

Abstract

The present invention relates to a plant (1) for providing carbon dioxide (CO2), comprising a separation plant (2), which is fluidically connected to a gas mixture (4) of flue gas and carbon dioxide (CO2), and which is designed to separate the carbon dioxide (CO2) contained in the flue gas, and which, in operation, can be operated with steam from a steam line (7) and comprises a first carbon dioxide line (5) fluidically connected to the separation plant (2) and through which the carbon dioxide (CO2) separated in the separation plant (2) flows during operation, a preheater (6) through which the carbon dioxide line (5) passes and which is designed to increase the temperature of the carbon dioxide (CO2), and a multi-stage compressor (13) fluidically connected on the inlet side to a carbon dioxide line (12) leaving the preheater (6).

Description

[Technical Field]

[0001] The present invention relates to a plant and a method for operating a plant.

[0002] The present invention relates in particular to a plant and method for capturing and processing carbon dioxide (CO2) for transportation in pipelines.

[0003] It is known that carbon dioxide (CO2) emissions from power plant operations and other processes need to be reduced, and in this case, carbon capture is considered a key element in achieving the global goal of reducing CO2 emissions to the lowest possible levels.

[0004] The International Energy Agency (IEA) predicts that the amount of CO2 captured could increase from the current 50 million tonnes per year to 7.6 billion tonnes per year by 2050 to meet climate targets.

[0005] The only currently commercially available large-scale technology for capturing carbon dioxide (CO2) from exhaust gases, such as flue gases, is the amine system, which requires significant amounts of low-pressure steam, and therefore heat, for the process, making it very costly and often making carbon capture economically unattractive to operators.

[0006] A further aspect is that after sequestration, carbon dioxide (CO2) often needs to be transported over long distances if there are no storage or recycling facilities nearby, for which pipeline transportation in the supercritical phase is often considered a good approach. To get carbon dioxide (CO2) into the supercritical phase, it needs to be compressed from near atmospheric pressure to supercritical pressure (above 73 bar and 31°C), typically 100-200 bar.

[0007] During compression, a significant amount of heat is released, which currently remains unused due to the low temperature levels.

[0008] Depending on how the amine system is used, there are a variety of potential heat sources. Some processes are exothermic, so the waste heat stream can be utilized for LP steam processing. However, if this is not the case and there is no alternative heat source, a fuel-fired or electric boiler must be installed. Often, natural gas boilers are used, which consume large amounts of gas and generate additional carbon dioxide (CO2), which also must be captured, thus making the energy and investment requirements for the amine system even higher.

[0009] Regarding the heat of compression, it is reasonable to utilize it rationally and possibly combine it with the LP steam processing required for the amine plant. However, it is first necessary to convert the low-quality heat into high-quality heat. One possible approach is to use fewer intercoolers between compression stages, so that the carbon dioxide (CO2) is cooled only when it is above a temperature at which the heat can be utilized for LP steam processing. However, the carbon dioxide (CO2) is then cooled again to ambient temperature, so the amount of steam that can be generated is relatively small and the heat is only partially utilized. If it is desired to utilize 100% of the heat and maximize steam generation, a high-temperature heat pump can be used. However, this involves significantly higher investment costs and space requirements.

[0010] Against this background, the object of the present invention is to provide a plant and a method for the cost-optimal production of carbon dioxide (CO2).

[0011] A further object of the present invention is to maximize heat recovery for low pressure (LP) steam processing at the lowest possible cost and space requirements.

[0012] The object is to provide a plant for providing carbon dioxide (CO2), which includes a separation plant, which is fluidically connected to a gas mixture of flue gas and carbon dioxide (CO2), and which is designed to separate the carbon dioxide (CO2) contained in the flue gas, and in operation, the separation plant can be operated with steam from a steam line, and which further includes a first carbon dioxide line fluidically connected to the separation plant and through which the carbon dioxide (CO2) separated in the separation plant flows out in operation, and a preheater through which the carbon dioxide line passes and which is designed to increase the temperature of the carbon dioxide (CO2), and which further includes a carbon dioxide line discharged from the preheater and a steam line connected to an inlet side The system comprises a multi-stage compressor fluidically connected to a separation plant via a steam line, where after one stage the temperature and pressure of the carbon dioxide (CO2) are increased, after this stage the carbon dioxide (CO2) passes through a line to a steam generator, which is designed to generate steam by energy exchange of water supplied to the steam generator with the thermal energy of the carbon dioxide (CO2) discharged from the compressor after one stage, the carbon dioxide (CO2) cooled in the steam generator is returned to the compressor for the next stage, the steam generated in the steam generator is fluidically connected to a separation plant via a steam line, and the carbon dioxide (CO2) flowing out of the compressor after the last stage flows through a preheater to be heated and then flows into an outlet line, which is resolved by the plant.

[0013] The problem with this method is solved by the following steps. - fluid-technically feeding a gas mixture of flue gas and carbon dioxide (CO2) to a separation plant, separating carbon dioxide (CO2) in a separation plant; supplying carbon dioxide (CO2) to a preheater and heating the carbon dioxide (CO2) in the preheater; further transferring the carbon dioxide (CO2) heated in the preheater to a first stage of a multi-stage compressor, and increasing the pressure and temperature of the carbon dioxide (CO2) in the first stage; Further transferring the heated carbon dioxide (CO2) after the first stage to a steam generator, and using the thermal energy of the carbon dioxide (CO2) to generate steam in the steam generator; performing a return step, in which the carbon dioxide (CO2) cooled in the steam generator is sent to a further stage of a compressor, in which the temperature and pressure of the carbon dioxide (CO2) are increased; Further transferring the heated carbon dioxide (CO2) after a further step to a steam generator, and using the thermal energy of the carbon dioxide (CO2) to generate steam in the steam generator; Repeating the return step until the final stage; further transporting the carbon dioxide exiting after the last stage through a preheater; further transferring the carbon dioxide exiting the preheater to an outlet line; In this case, the steam generated in the steam generator is fluidically connected via a steam line to the separation plant.

[0014] This new solution makes it possible to maximize heat utilization and generate the same amount of steam as a heat pump, with little or no additional equipment or space required.

[0015] A salient feature of the present invention is the compressor, which typically contains six to eight stages for compression from atmospheric pressure to supercritical pressure. This means that the compression and steaming process within the waste heat steam generator (HRSG) actually proceeds multiple times, depending on the final number of stages required to reach the exit pressure.

[0016] The preheater and all further downstream connected components are used only once, regardless of the number of stages.

[0017] According to the present invention, the carbon dioxide (CO2) is only cooled to a point where the heat can still be used for steam processing in the waste heat boiler. This temperature is generally 5-10°C higher than the final temperature of the steam required for the amine system, depending on the final design of the heat exchangers. However, this means that the carbon dioxide (CO2) is not cooled back to ambient temperature before it reaches the next compressor stage. This allows for steam processing after each compression stage with the same number of heat exchangers / HRSGs as in conventional operation.

[0018] However, in practice, this process could only begin after the second or even third stage of the compressor, since the CO2 must first be heated from the atmospheric outlet temperature downstream of the amine system to a usable temperature level. Here, to further maximize steam processing, the hot CO2 downstream of the last HRSG can be used to preheat the CO2 at the compressor inlet to a usable temperature level, so that the entire compressor from suction to outlet is operated at a temperature level capable of processing steam, allowing steam processing to begin already after the first compressor stage.

[0019] Although the carbon dioxide (CO2) is already partially cooled to preheat it at the introduction point, a further post-cooler is required downstream of the preheater to cool the carbon dioxide (CO2) back down to ambient temperature. Furthermore, for pipeline injection, dehydration of the CO2 stream is often required, which is typically done using a triethylene glycol (TEG) system at a pressure of 40-50 bar, as this is the most economical method for CO2 dehydration. However, this would mean that the CO2 may need to be cooled at 40-50 bar back to ambient temperature for dehydration.

[0020] This problem can be solved by using a glycerin-based dehydration system, which, although somewhat more expensive and energy-intensive, allows for the dehydration of carbon dioxide (CO2) at supercritical pressures, thereby maximizing steam generation. However, if this is not desirable for some reason, the carbon dioxide (CO2) can also be dehydrated at 40-50 bar using a TEG system. In this case, adaptation of the preheater and heat exchanger is required.

[0021] According to the present invention, no additional equipment or machinery is required and the additional space requirements are very limited, whereas a heat pump would approximately double the space requirements and investment costs. This solution therefore considerably reduces the energy requirements of the amine system, thereby resulting in fuel savings if fossil fuels are used, and also in carbon dioxide (CO2) savings, and therefore in this context less carbon dioxide (CO2) needs to be recovered, while also resulting in capital investment savings for the amine system, since no additional machinery is required and only some additional drive power is needed.

[0022] Furthermore, except for the aftercooler, the feed water or carbon dioxide (CO2) from the inlet is always used to cool the carbon dioxide (CO2), which significantly reduces the cooling water requirements for the compressor, which can also be a significant advantage as the availability of cooling water is an issue in some regions.

[0023] Advantageous further configurations are set forth in the dependent claims.

[0024] An advantage of the present invention is that it maximizes the heat utilization and recovery of the heat of compression of carbon dioxide (CO2) with little additional machinery and space requirements.

[0025] An additional benefit is fuel savings in the boiler for LP steam treatment for the amine system.

[0026] A particular advantage arises from the significant savings in cooling water for the carbon dioxide (CO2) compressor.

[0027] A further benefit is gained from potential carbon dioxide (CO2) reductions when fossil fuels are used as the heat source for the boiler.

[0028] The above-mentioned characteristics, features and advantages of the present invention, as well as the manner in which they are accomplished, will be more clearly and more clearly understood in connection with the following description of the embodiments which are set forth in more detail in connection with the drawings.

[0029] Here, identical components or components having the same functions are denoted by the same reference numerals.

[0030] In the following, embodiments of the present invention will be described with reference to the drawings, which are not intended to represent the embodiments to scale; rather, the drawings, when used for illustration, are shown in a schematic and / or slightly distorted form. For the recovery of teachings readily discernible in the drawings, reference is made to the relevant prior art. [Brief explanation of the drawings]

[0031] [Figure 1] 1 shows a schematic diagram of an embodiment of a plant according to the invention; [Figure 2] 1 shows a schematic diagram of an alternative embodiment of a plant according to the invention; DETAILED DESCRIPTION OF THE INVENTION

[0032] FIG. 1 shows a schematic diagram of an embodiment of a plant 1 according to the invention.

[0033] The plant 1 is designed to provide carbon dioxide (CO2) and includes a separation plant 2. The separation plant 2 is fluidically connected via a line 3 with a gas mixture 4 of flue gas and carbon dioxide (CO2). The separation plant 2 is designed to separate the carbon dioxide (CO2) contained in the flue gas 4. The separated carbon dioxide (CO2) flows from the separation plant 2 via a first carbon dioxide line 5 through a preheater 6. In the preheater 6, the temperature of the carbon dioxide (CO2) is increased.

[0034] The first carbon dioxide line 5 is fluidically connected to the separation plant 2, which in this case is designed as an amine plant.

[0035] In operation, separation plant 2 is powered by steam from steam line 7. Carbon dioxide (CO2) generated in boiler 8 is also optionally supplied to separation plant 2 via line 10. Steam produced in boiler 8 is sent to separation plant 2 via line 11.

[0036] The heated carbon dioxide (CO2) downstream of the preheater 6 is fed via line 12 to a multistage compressor 13. The multistage compressor 13 is fluidically connected on the inlet side with the carbon dioxide line 5 leaving the preheater 6.

[0037] In the compressor 13, heated carbon dioxide (CO2) is fed to a first stage where the temperature and pressure of the carbon dioxide are increased.

[0038] After the first stage, the carbon dioxide (CO2) is fed via line 14 to a steam generator 15, which can be designed as a HRSG (Heat Recovery Steam Generator). The steam generator 15 is designed so that the water fed to the steam generator 15 is converted into steam by energy exchange with the thermal energy of the carbon dioxide (CO2) discharged from the compressor 13 after one stage.

[0039] The compressor 13 has 5 to 10 stages, in particular 6 to 9, and very in particular 7 or 8 stages.

[0040] The carbon dioxide (CO2) cooled in the steam generator 15 is sent to the next stage and returned to the compressor 13 via line 16. There, the carbon dioxide (CO2) is fed to the next stage and from there fed back to the steam generator 15. This can happen multiple times, i.e., the carbon dioxide (CO2) is passed through multiple stages in the compressor 13, and after each stage, the thermal energy of the carbon dioxide (CO2) is used to generate steam in the steam generator 15. For clarity, FIG. 1 shows only one line 14 to the steam generator 15 and one line 16 from the steam generator 15 to the compressor 13. For clarity, the individual lines to the steam generator 15 and back to the compressor 13 have not been shown.

[0041] The steam generated in the steam generator 15 is fluidically connected to the separation plant 2 via a steam line 7 .

[0042] The carbon dioxide (CO2) leaving the compressor 13 after the last stage flows through the preheater 6 via line 17.

[0043] The carbon dioxide (CO2) then flows to an aftercooler 18, which is designed to reduce the temperature of the carbon dioxide (CO2) leaving the preheater 6. Cooling water 20 is fed to the aftercooler 18.

[0044] Downstream of the aftercooler 18, the carbon dioxide (CO2) flows through a dehydration unit (glycerol) 19, which is designed to dehydrate the carbon dioxide (CO2) exiting the preheater 6. Here, via a dehydration line 21, the water separated in the dehydration unit 19 is discharged.

[0045] The aftercooler 18 is fluidically connected to the cooling water via a cooling water line 20 .

[0046] Subsequently, the carbon dioxide (CO2) generated and provided in the plant 1 is processed for transportation in a pipeline.

[0047] Figure 2 shows a schematic diagram of an alternative embodiment of a plant 1 according to the invention for providing carbon dioxide (CO2). The separation process in the separation plant 2 by means of a compressor 13 is identical to the embodiment according to Figure 1. Therefore, reference is made to the previous description of Figure 1.

[0048] 1 is that, for example, a further compressor 22 is arranged between the preheater 6 and the aftercooler 19, which is fluidically connected downstream of the superheater 23. The superheater 23 is also fluidically connected to a dehydration plant 24, which can be designed as a TEG system. Separated water 25 flows out of the dehydration plant 24.

[0049] Between the preheater 6 and the dehydration plant 24 there is a cooler 26 to which water 27 is fed.

[0050] The further compressor 22 is fluidically connected to the steam generator 31 in a similar manner to the compressor 13. As described for the compressor 13, in the further compressor 22 too, carbon dioxide (CO2) is fed to the steam generator 31 after each stage.

[0051] The carbon dioxide (CO2) cooled in the steam generator 31 is returned to the further compressor 22 via line 32 to the next stage of the further compressor 22. There, the carbon dioxide (CO2) is fed to the next stage and from there fed again to the steam generator 31. This is done multiple times, i.e. the carbon dioxide (CO2) is flowed through multiple stages in the further compressor 22, after each stage the thermal energy of the carbon dioxide (CO2) is used to generate steam in the steam generator 31. For clarity, only one line 33 to the steam generator 31 and one line 32 from the steam generator 31 to the further compressor 22 are shown in Figure 2. For clarity, the individual lines to the steam generator 31 and back to the further compressor 22 have not been shown.

[0052] The steam generated in the steam generator 31 is fluidically connected via a steam line 34 to the steam line 7 and thus to the separation plant 2 .

[0053] The carbon dioxide (CO2) leaving the further compressor 22 after the last stage flows via a line through a superheater 23.

[0054] The steam generator 31 is fluidically connected to the line 9 via the line 35 .

[0055] Downstream of the superheater 23 is arranged an aftercooler 28, which is likewise fed with water 29 as coolant. Subsequently, the carbon dioxide (CO2) generated and provided in the plant 1 is processed for transportation in a pipeline 30. [Explanation of symbols]

[0056] 1...plant, 2...separation plant, 3...line, 4...gas mixture, 5...carbon dioxide line, 6...preheater, 7...steam line, 8...boiler, 9...line, 10...line, 11...line, 12...line, 13...compressor, 14...line, 15...steam generator, 16...line, 17...line, 18...aftercooler, 19...dehydration unit, 20...cooling water line, 21...dehydration line, 22...further compressor, 23...superheater, 24...dehydration plant, 25...water, 26...cooler, 27...water, 28...aftercooler, 29...water, 30...pipeline, 31...steam generator, 32...line, 33...line, 34...steam line, 35...line

Claims

1. A separation plant (2) for separating carbon dioxide (CO ２ ), wherein the separation plant (2) separates flue gas and carbon dioxide (CO ２ ) and the separation plant (2) is fluidically connected to a gas mixture (4) of carbon dioxide (CO ) contained in the flue gas. ２ ) are designed to be separated, In operation, the separation plant (2) can be operated with steam from a steam line (7), Furthermore, a carbon dioxide (CO ) separator ( 2 ) is fluidically connected to the separation plant ( 2 ) and separated therein. ２ ) includes a first carbon dioxide line (5) through which the carbon dioxide gas flows during operation, Furthermore, the carbon dioxide line (5) passes through, and the carbon dioxide (CO ２ a preheater (6) designed to raise the temperature of the Furthermore, it includes a multi-stage compressor (13) fluidically connected at its inlet side to a carbon dioxide line (12) discharged from the preheater (6), After a certain stage, the carbon dioxide (CO ２ ) is increased in temperature and pressure, After this step, the carbon dioxide (CO ２ ) passes through a line (14) to a steam generator (15), The steam generator (15) is configured to convert the water supplied to the steam generator (15) into the carbon dioxide (CO 2 ) discharged from the compressor (13) after one stage. ２ ) to generate steam by exchanging heat energy with the steam. The carbon dioxide cooled in the steam generator (15) is then returned to the compressor (13) in a next step, the steam generated in the steam generator (15) is fluidically connected to the separation plant (2) via the steam line (7), The carbon dioxide (CO ２ ) flows through the preheater (6), where it is heated and flows into the outlet line; Plant (1).

2. The carbon dioxide (CO ２ 2. The plant (1) according to claim 1, wherein the wastewater is treated for transportation in a pipeline.

3. 3. The plant (1) according to claim 1 or 2, wherein the separation plant (2) is designed as an amine plant.

4. Plant (1) according to claim 1, 2 or 3, wherein the compressor (13) has 5 to 10 stages, in particular 6 to 9, very in particular 7 or 8 stages.

5. An aftercooler (18) is disposed downstream of the preheater (6), The after-cooler (18) cools the carbon dioxide (CO ２ ) is designed to reduce the temperature of A plant (1) according to any one of claims 1 to 4.

6. A dehydration unit (19) is disposed downstream of the preheater (6), The dehydration unit (19) is configured to decompose the carbon dioxide (CO ２ ) is designed to dehydrate, A plant (1) according to any one of claims 1 to 5.

7. 7. The plant (1) according to claim 6, wherein the dehydration unit (19) is arranged downstream of the aftercooler (18).

8. a further compressor (22) is arranged between the compressor (13) and the preheater (6); the compressor (13) and the further compressor (22) are fluidically connected to each other, A plant (1) according to any one of claims 1 to 5.

9. a cooler (26) is arranged between the compressor (13) and the further compressor (22); an outlet of the compressor (13) is fluidically connected to an inlet of the cooler (26), the outlet of the cooler (26) is fluidically connected to the inlet of the further compressor (22), A plant (1) according to claim 8.

10. a dehydration plant (24) is arranged between the cooler (26) and the further compressor (22); The outlet of the cooler (26) is connected to the inlet of the dehydration plant (24), the outlet of the dehydration plant (24) is fluidically connected to the inlet of the further compressor (22), A plant (1) according to claim 9.

11. 11. The plant (1) according to claim 10, wherein the dehydration plant is designed as a triethylene glycol (TEG) system.

12. Carbon dioxide (CO ２ 1. A method for providing a Flue gas and carbon dioxide (CO ２ ) to a separation plant (2) in a fluid-technical manner, The carbon dioxide (CO ２ ) in said separation plant (2); The carbon dioxide (CO ２ ) is supplied to a preheater (6), and the carbon dioxide (CO ２ ) (6) in the preheater; The carbon dioxide (CO ２ ) is further transferred to the first stage of a multi-stage compressor (13), and said carbon dioxide (CO ２ ) in said first stage; The heated carbon dioxide (CO ２ ) after said first stage is further transferred to a steam generator (15), and said carbon dioxide (CO ２ Utilizing the thermal energy of the steam generator (15) to generate steam in the steam generator (15); A returning step is carried out, and in the returning step, the carbon dioxide (CO ２ ) to a further stage of the compressor (13), where the carbon dioxide (CO ２ increasing the temperature and pressure of the The heated carbon dioxide (CO ２ ) after said further stage is further transferred to said steam generator (15), and said carbon dioxide (CO ２ Utilizing the thermal energy of the steam generator (15) to generate steam in the steam generator (15); repeating the returning step until the final stage; The carbon dioxide (CO ２ ) further transporting the preheated water through said preheater (6); The carbon dioxide (CO ２ ) further transferred to an outlet line; and The steam generated in the steam generator (15) is fluidically connected to the separation plant (2) via the steam line (7). method.

13. An aftercooler (18) is disposed downstream of the preheater (6), The after-cooler (18) cools the carbon dioxide (CO ２ ) is designed to cool The method of claim 12.

14. 14. The method according to claim 13, wherein a dehydration unit (19) is arranged downstream of the aftercooler (18).

15. 13. The method according to claim 12, wherein a further compressor (22) is arranged between the compressor (13) and the preheater (6). 。

16. 16. The method according to claim 15, wherein a cooler (26) is arranged between the compressor (13) and the further compressor (22).

17. 17. The method of claim 16, wherein a dehydration unit is disposed between the cooler (26) and the superheater (23).

18. 18. The method of claim 17, wherein the dehydration unit is designed as a triethylene glycol (TEG) system.

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