Device and method for co 2 up-concentration

Abstract

1. Device and method for enriching a CO2 (7) concentration in a gas stream, configured for receiving a first (3) gas stream at one end of at a main (1) pipe, further configured for transporting the gas stream in the main (1) pipe to provide a gas stream (4) with a higher CO2 concentration at another end of the main (1) pipe. The main (1) pipe is configured with a vertical separation (2) pipe having a cross-sectional area of at least 1200 cm2 and a length of at least 4800 mm. The separation (2) pipe has a valve (5) to release a top (18) gas, thereby increasing CO2 concentration in gas stream (4). The pressure difference between the first end of the main (1) pipe and the branch of the main (1) pipe, is in the range 3 to 20 mbar.

Description

[0001] Device and method for CO2 up-concentration

[0002] The present invention concerns a device for up-concentration of CO2 in a gas stream as indicated by the preamble of claim 1. The invention further concerns a method for up-concentration of CO2 in a gas stream and a use of such up-concentrated CO2.

[0003] Background

[0004] Up-concentrating of CO2 from gas streams such as a flue gas stream is necessary in order to utilise the CO2 (carbon-capture-and-utilisation, CCU) or to enable long-time storage (carbon-capture- and-storage, CCS). The demand in both cases is to reduce CO2 emissions with negative consequences for the climate. Different technologies have been developed and are applied for up-concentrating of CO2 from gas streams.

[0005] EP4321234 Al, EP4074409 Al and EP2512622 Al disclose separation and up-concentration of CO2 from gas streams such as flue gas streams. Multi-stage separation is feasible and CO2- concentrations of 98 %vol and higher can be achieved. A disadvantage of membrane technology is the low flux rate through the membrane which limit the productivity of the separation process. Another disadvantage is possible fouling of the membranes causing short maintenance intervals and further limitation of productivity. In addition, the energy consumption of the separation process is considerable.

[0006] EP4265318 Al, EP4182055 Al and WO12092176 A2 disclose devices, processes and means for separation and up-concentrating of CO2 from gas streams by adsorption, and CC -concentrations of 98 %vol and higher can be achieved. The disadvantage is that the separation process is energy- intensive due to the desorption process. Energy consumption is high for other processes such as cryogenic distillation or electrochemical reduction, too.

[0007] BR102018005769 A2 relates to a method of gravitational separation of CO2 from natural gas in caves of salt that allows the delivery of the natural gas and CO2 capture and storage (CCS). The mixture of CO2 and natural gas is pumped into the cave of salt with pressure of typically 20-50 MPa. The cave is closed and after the CO2 is settled on the bottom of the cave the natural gas is extracted from the top of the cave. The CO2 is left in the cave as a form of CCS. High energy consumption for preparing the cave, the transport of the gas mixture to the cave and the pumping of the gas mixture into the cave is required. In spite of a possible large volume of the cave the productivity is limited because the cave cannot be re-used for CO2 separation.

[0008] WO 2018 / 152238 Al discloses a process and an apparatus for the capture of carbon dioxide. A vapor comprising carbon dioxide and at least one other component is compressed to form a compressed mixture comprising a dense carbon dioxide fluid and the at least one other component. The compressed mixture comprising the dense carbon dioxide fluid and the other components is fed to a high-pressure density-driven separator wherein a stream enriched in the dense carbon dioxide fluid and a stream enriched in the at least one other component is formed. The stream enriched in the dense carbon dioxide and the stream enriched in the at least one other component fluid is removed from the separator. The process requires high pressure and high energy consumption.

[0009] AU 2021 / 287233 A discloses systems and methods to separate carbon dioxide from flue gases and sequester carbon dioxide. By using the properties of carbon dioxide and the temperature in a body of water (e.g., the ocean or freshwater body of water) or the temperatures of the ambient atmosphere, gaseous carbon dioxide can be converted to a liquid and separated from other gases. Pressure used to separate carbon dioxide from other gases may also be used to sequester liquid carbon dioxide. The liquid carbon dioxide is inert and can be discharged into the ocean without dissolving in seawater and acidifying the ocean. The liquid carbon dioxide may further be densified to be denser than seawater. The liquid carbon dioxide can then sink to the bottom of the ocean or be injected into ocean sediments or sediments and rocks beneath the ocean floor, inert and sequestered for the long term. The process requires high pressure and high energy consumption.

[0010] US 2022401879 Al discloses systems for separating and concentrating CO2 from air or a gas including a vortex tube designed for separating and concentrating CO2 from a gaseous input stream. The vortex tube has an operating design pressure of between 105 psi (7.2 bar) and 280 psi (19.3 bar) above atmospheric pressure and produces a concentrated CO2 outlet stream. The concentrated CO2 outlet stream is in fluid connection with a conversion system capable of converting the separated CO2 into another chemical compound.

[0011] The drawback of the known methods for CO2 separation is high energy consumption, short maintenance intervals and limited productivity in relation to the size and cost of the separation device.

[0012] It is therefore a need for devices and methods for CO2 separation and up-concentrating which are straight forward without being energy-intensive.

[0013] Objective

[0014] It is thus an objective of the present invention to provide a method and device for scalable and energy saving separation of CO2.

[0015] The present invention

[0016] The above objective is achieved by the method according to the present invention as defined by claim 1. The method disclosed in claim 13 constitutes a further aspect of the present invention.

[0017] Preferred embodiments are disclosed by the dependent claims.

[0018] According to the present invention a device comprising at least one main pipe and at least one separation pipe on top of the main pipe is configured for receiving a first gas stream at a first end of a main pipe. The first gas stream may be a flue gas stream from a combustion facility. The gas stream proceeds through the main pipe and fills the main pipe and the separation pipe. The separation pipe is configured with means to release a top gas with a predetermined rate. The CO2 gas has a density of about 1,98 g / cm3 which is about 1,53 times higher than the density of air. CO2 is therefore up-concentrated in the separation pipe with the least concentration on top of the separation pipe. Release of top gas at the predetermined rate makes sure, that the subsequently fed first gas at the first end of the main pipe does not lead to a pressure increase.

[0019] A steady state is obtained in the separation tube with about 99% vol CO2 gas in the bottom and about 99% air at the top of the separation pipe. The main pipe right below the separation pipe and towards a second end of the main pipe has about 99% vol CO2 gas, too. This CO2 gas acts like a plug towards the subsequently following first gas due to the density difference between air and CO2 and the air in the following gas stream is forced to move upwards into the separation pipe. At the second end of the main pipe a second gas stream is provided with about 99% vol CO2.

[0020] The separation pipe must have a cross-sectional area of at least 1200 cm2and a length of at least 4800 mm. The pressure difference between the feeding of the first gas at the first end of the main pipe and the branch of the main pipe with the separation pipe is in the range 3 to 20 mbar. Higher pressure would reduce the enrichment of CO2 in the gas stream. Lower pressure would reduce the productivity in terms of provided CO2 at the second end of the main tube in a predetermined time.

[0021] Optionally, filters for filtering solid particles from the gas stream may be installed.

[0022] In a first embodiment the top gas has a CO2 concentration of less than 1 % vol. A CO2 concentration of less than 0,5 % vol is more preferred and a CO2 concentration of less than 0,1 % vol is most preferred. The top gas is released at the upper end of the separation pipe. The lower the concentration of CO2 in the top gas, the better is the separation in the separation pipe and the higher the concentration of CO2 at the second end of the main tube.

[0023] In another embodiment the means to release the top gas is a controllable valve. The valve may be a mechanically controlled valve, a valve comprising at least one spring, a valve comprising at least one balance weight, a ventilating flap and electrically controlled valve, a valve with actuator, a valve with nozzle, a throttle valve, a throttle valve comprising at least one balance weight or a different type of valve. The type of valve or other means to release the top gas is not essential for the function of the invention provided the top gas is released at the predetermined rate.

[0024] In another embodiment the main pipe has a length of at least 1000 m, preferably at least 700 m, more preferred at least 400 m and most preferred at least 200 m. The length of the main pipe is not essential for the function of the invention. Nevertheless, the pressure between the feeding of the first gas at the first end of the main pipe and the branch of the main pipe with the separation pipe may be adjusted due to a change in the length of the main pipe.

[0025] In another embodiment the separation pipe has a length of at least 5000 mm, preferably at least 5500 mm, more preferred at least 6000 mm and most preferred at least 8000 mm. A longer separation pipe will contribute to a better separation between CO2 and air. However, a longer separation pipe may involve issues on cost and mechanical stability of the device.

[0026] In another embodiment the pressure difference between the feeding of the first gas at the first end of the main pipe and the branch of the main pipe with the separation pipe is in the range 3 to 20 mbar, preferred in the range 4 to 10 mbar and more preferred in the range 5 to 6 mbar. Higher pressure provides more gas at the second end of the main pipe, however with reduced enrichment of CO2 in the provided gas stream.

[0027] In yet another embodiment the first gas stream is a flue gas stream from a combustion facility of carbon comprising material selected from the group consisting of biomass, natural gas, biogas and oil. The nature of the combusted material is not essential for the function of the invention. Materials of natural origin are preferred.

[0028] In another embodiment the bottom of the main pipe is provided with at least one valve configured for releasing condensed water. Water vapour which is comprised by the gas stream may condense and needs to be removed from the main pipe.

[0029] In another embodiment the concentration of CO2 in the first gas stream is at least 3 % vol, preferably at least 10 % vol, more preferred at least 20 % vol and most preferred at least 25 % vol. The higher the concentration of CO2 in the first gas stream the easier is it to reach the target concentration of 99% vol CO2.

[0030] In another embodiment the enriched CO2 concentration in the second gas stream is at least 80 % vol, preferably at least 90 % vol, more preferred at least 95 % vol and most preferred at least 99 % vol. Up-concentration of CO2 demands normally a concentration of at least 98% vol CO2. However, if lower concentrations are sufficient for a given application, the device may by adapted in order to maximise the productivity and reduce the CO2 concentration to the requested value.

[0031] In another embodiments the device may further comprise means for cooling, compression and storage of CO2 which are known within industrial handling of gases. In yet another embodiment the device may comprise two, three, four or more main pipes. The main pipes may have one separation pipe each or being connected before the junction with the separation pipe.

[0032] The liquified CO2 may be delivered to food and beverage producers, metal manufacturers, manufacturers of cooling devices, manufacturers of devices for fire suppression, greenhouse horticultures and manufacturers for fuels, chemicals and building materials.

[0033] Certain means and devices described herein for performing steps of the invented method are not described in detail herein since they are somewhat conventional in this technical field. For example, the disclosed embodiments may use elements such as sensor(s) for measuring properties; receiver(s) for receiving measurements or other data transmitted by another element; processor(s) for calculating and comparing data; data storage; display unit(s) for displaying data; measurements and instructions; and communication lines between such elements. The novelty and inventiveness of the disclosed method and device are inherent in the relationships and the specific way with which the means and devices are combined and used.

[0034] Example:

[0035] A device for enriching a CO2 concentration in a gas stream comprises four circular main pipes of 500 mm diameter which join a separation pipe of 400 mm diameter and a cross-section area of 1260 cm2. The separation pipe has a length of 5000 mm and a mechanically controlled valve on top and is configured with a supply pipe for the gas stream with the enriched CO2 concentration. The device is fed with 21,5 million cubic meters of flue gas per year at the first end of the main pipes and at the end of the supply pipe (second end of the main pipes) 8500 tons of CO2 with a purity of 99% are provided. The pressure difference between the feeding site of the flue gas into the main pipes and the joining site of the main pipes with the separation pipe is 5 to 6 mbar.

[0036] Below, the invention will be described in further detail in the form of non-limiting exemplary embodiments illustrated by drawings, where

[0037] Figure 1 is a side sectional simplified view of a device according to the present invention, for enriching a CO2 concentration in a gas stream before the gas stream reaches the separation pipe.

[0038] Figure 2 is a side sectional simplified view of the device of Fig. 1 after a steady state in the separation process has been obtained.

[0039] By simplified is understood that elements usually present in an industrial embodiment of the invention is omitted for more clearly to emphasize the principle features of the invention, and that some elements for same purpose may be out of scale.

[0040] Figure 1 shows a device for enriching a CO2 concentration in a gas stream right after the feeding of a first gas stream 3 has been started. The gas stream comprising CO27 and air 8 has not reached the separation pipe 2, the mixture of air 8 and CO27 moving through a main pipe 1 from left to right. At this point in time no second gas stream 4 with an up-concentrated CO2 concentration has yet reached the outlet end of the main pipe 1. A water valve 6 is visible beneath the separation pipe 2. A valve 5 for releasing top gas is closed.

[0041] Figure 2 shows the device of Figure 1 after the first gas stream 3 has reached the separation pipe 2 and a steady state in the separation process has been obtained. Air 8 and CO27 are mixed on the left (upstream) side of the main pipe 1 and separated on the right (downstream) side of the main pipe 1 where air 18 is released as top gas and the second gas stream 4 with up-concentrated CO27 , 17 is provided. The valve 5 is at least partly open in order to release a predetermined amount of top gas. Condensed water may be released through the water valve 6.

[0042] The pressure difference in the low millibar range between the inlet of the exhaust gas in the main pipe and the bifurcation of the main pipe with the separation pipe ensures a continuous separation of CO2 and gas components that have a lower density than CO2 (CO2 capture). At a given pressure difference in the low millibar range between the feed of the exhaust gas into the main pipe and the junction of the main pipe with the separation pipe, the means for releasing the top gas can be adjusted so that a steady state is achieved in the separation pipe with approximately 99 vol% CO2 at the bottom and more than 99 vol% air at the top.

[0043] The aforementioned pressure difference limits the amount of exhaust gas that can be fed into and separated in the device. The device in the example shows an annual CO2 capture of 8,500 tons and thus a power production of approx. 2 Megawatt (MW). See page 4, lines 25-32. The device with one or a few main pipes is well suited for CO2 capture from combustion plants with 1-10 MW. Plants with a power production of several hundred MW, such as gas-fired power plants, are difficult to realize with only one main pipe and only one separation pipe because the diameter of the main pipe / separation pipe exceeds the limit for handling such pipes. CO2 purification of a gas power plant would require a device composed of a few hundred pipes of comparable dimension as in the example.

Claims

Claims1. Device for enriching a CO2 (7) concentration in a gas stream, the device configured for receiving a first (3) gas stream at a first end of at least one main (1) pipe, the device further configured for transporting the gas stream in the at least one main (1) pipe and configured to provide a second (4) gas stream with a higher CO2 (17) concentration than the first (3) gas stream at a second end of the at least one main (1) pipe characterized in that the at least one main (1) pipe is configured on top with at least one separation (2) pipe having a cross-sectional area of at least 1200 cm2and a length of at least 4800 mm, thereby generating a branch of the main (1) pipe, wherein the separation (2) pipe is configured with means (5) to release a top (18) gas with a predetermined rate, thereby generating the second (4) gas stream being found at the second end of the main (1) pipe, wherein the pressure difference between the feeding of the first (3) gas at the first end of the main (1) pipe and the branch of the main (1) pipe with the separation (2) pipe is 3 to 20 mbar.

2. Device according to claim 1, wherein the top (18) gas has a CO2 (7, 17) concentration of less than 1 % vol, more preferred less than 0,5 % vol and most preferred less than 0,1 % vol.

3. Device according to claim 1 or 2, wherein the means (5) to release the top (18) gas is a controllable valve chosen among the group consisting of mechanically controlled valve, electrically controlled valve, valve comprising at least one spring, valve comprising at least one balance weight, ventilating flap, valve with actuator, valve with nozzle, throttle valve, throttle valve comprising at least one balance weight.

4. Device according to any of the previous claims, wherein the main (1) pipe has a length of at least 1000 m, preferably at least 700 m, more preferred at least 400 m and most preferred at least 200 m.

5. Device according to any of the previous claims, wherein the separation (2) pipe has a length of at least 8000 mm, preferably at least 6000 mm, more preferred at least 5500 mm and most preferred at least 5000 mm.

6. Device according to any of the previous claims, wherein the pressure difference between the feeding of the first (3) gas at the first end of the main (1) pipe and the branch of the main (1) pipe with the separation (2) pipe is preferably 4 to 10 mbar and most preferred 5 to 6 mbar.

7. Device according to any of the previous claims, wherein the first (3) gas stream is a flue (7, 8) gas stream from a combustion facility of carbon comprising material selected from the group consisting of biomass, natural gas, biogas and oil.

8. Device according to any of the previous claims, wherein the bottom of the main (1) pipe is provided with at least one valve (6) configured for releasing condensed water.

9. Device according to any of the previous claims, wherein the concentration of CO2 (7) in the first (3) gas stream is at least 3 % vol, preferably at least 10 % vol, more preferred at least 20 % vol and most preferred at least 25 % vol.

10. Device according to any of the previous claims, wherein the enriched CO2 (17) concentration in the second (4) gas stream is at least 80 % vol, preferably at least 90 % vol, more preferred at least 95 % vol and most preferred at least 99 % vol.

11. Device according to any of the previous claims, wherein the device further comprises means for cooling, compression and storage of CO2 (17).

12. Device according to any of the previous claims, wherein the device comprises at least two main (1) pipes, preferably at least three main (2) pipes and most preferred at least four (1) main pipes, wherein the main (1) pipes share a common separation (2) pipe or wherein each main (1) pipe is configured with an own separation (2) pipe.

13. Method for enriching a CO2 (7) concentration in a gas stream, comprising the steps of providing a first (3) gas stream at a first end of a main (1) pipe, transporting the first (3) gas stream in the main (1) pipe receiving a second (4) gas stream with the enriched CO2 (17) concentration at a second end of the main (1) pipe, characterized in that the main (1) pipe is provided on top with a separation (2) pipe having a cross-sectional area of at least 1200 cm2and a length of at least 4800 mm, thereby providing a branch of the main (1) pipe and the separation (2) pipe is further provided with means (5) to release a top (18) gas with a predetermined rate, wherein the pressure difference between the feeding of the first (3) gas at the first end of the main (1) pipe and the branch of the main (1) pipe with the separation (2) pipe is 3 to 20 mbar.

14. Method according to claim 13, wherein the second (4) gas stream is cooled, compressed and stored in liquid state in a CC -tank.

15. Use of the device of claim 1 and / or the method of claim 13 for supplying CO2 (17) to at least one receiver selected from the group consisting of food and beverage producer, metal manufacturer, manufacturer of cooling devices, manufacturer of devices for fire suppression, greenhouse horticulture and manufacturer for fuels, chemicals and building materials.

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