Gas-separation installation and method for separating co 2 from a gas stream by means of a granular adsorbent

Abstract

The present invention relates to a gas-separation installation for separating CO2 from a gas stream by means of a granular adsorbent, said installation comprising: an adsorption unit which is designed to adsorb CO2 from the gas stream by means of the adsorbent; a desorption unit which is designed to desorb CO2 from the adsorbent at a defined pressure and a defined temperature; a first conveying unit which is designed to store the CO2-loaded adsorbent from the adsorption unit to the desorption unit; a second conveyor unit which is designed to convey the unloaded adsorbent from the desorption unit to the adsorption unit; a preheater; and a cooler, wherein the preheater is designed to heat the adsorbent conveyed into the desorption unit to a defined first temperature above the dew point in the desorption unit, and wherein the cooler is designed to cool the adsorbent conveyed out of the desorption unit to a defined second temperature below the dew point.

Description

[0001] R.417049

[0002] - 1 -

[0003] Description

[0004] title

[0005] Gas separation plant and process for CO separation 2 from a gas stream using a granular adsorbent

[0006] State of the art

[0007] The present invention relates to a gas separation plant for separating CO2 from a gas stream by means of a granular adsorbent and an associated method.

[0008] To limit atmospheric warming, actively reducing the increased carbon dioxide (C₂) content resulting from industrialization is being discussed. Gas separation plants can be used for this purpose, actively removing and concentrating CO₂ from the ambient air so that the C₂ can be separated and stored. Since the binding of CO₂ to an adsorbent depends, among other things, on temperature and pressure, different conditions must be set for adsorption and desorption in order to separate CO₂ through the resulting hysteresis. Desorption occurs particularly at a reduced partial pressure and a temperature above ambient temperature. Furthermore, desorption can be carried out in the absence of air to prevent degradation of the adsorbent.

[0009] During desorption, in addition to CO2, bound water is released. This can result in a high water content in the form of water vapor within a desorption unit. When the cool adsorbent is introduced into the warmer desorption unit, this can cause the water vapor to condense on the adsorbent, leading to clumping and hindering further CO2 desorption. R.417049

[0010] -2 -

[0011] The adsorbent should be cooled below a critical degradation temperature in the desorption unit before exiting the protective atmosphere, although this cooling process can also lead to the condensation of water vapor on the adsorbent.

[0012] It would be desirable to have a gas separation system that can reliably prevent condensation of water vapor on the adsorbent and thereby enable a rapid desorption and adsorption process.

[0013] Disclosure of the invention

[0014] The gas separation system according to the invention with the features of claim 1 and the method with the features of claim 9 have the advantage that the condensation of water on the adsorbent in the desorption unit can be avoided and an accelerated desorption and adsorption process can be enabled.

[0015] According to the invention, this is achieved by the gas separation system comprising an adsorption unit, a desorption unit, a first conveying unit, a preheater, and a cooler. The adsorption unit is configured to adsorb CO2 from a gas stream using an adsorbent. The desorption unit is configured to desorb CO2 from the adsorbent using a defined pressure and temperature. The defined pressure is, in particular, a negative pressure lower than atmospheric pressure. The defined temperature in the desorption unit is preferably higher than the temperature in the adsorption unit. The first conveying unit is configured to convey the CO2-laden adsorbent from the adsorption unit to the desorption unit.The preheater is designed to heat the adsorbent fed into the desorption unit to a defined first temperature above the dew point of the gas or air stream in the desorption unit. The cooler is designed to cool the adsorbent fed out of the desorption unit to a defined second temperature below the dew point of the gas or air stream. Thus, the preheater and cooler ensure that the adsorbent in R.417049.

[0016] - 3 -

[0017] The desorption unit maintains a temperature above the dew point, preventing water vapor from condensing on the adsorbent within the unit. The cooler enables rapid cooling of the adsorbent under defined conditions, allowing it to be quickly reused in the adsorption unit and preventing degradation. Consequently, the gas separation system according to the invention enables the rapid and reliable separation of CO2 from a gas stream. The first conveying unit is preferably also configured to convey the adsorbent from the desorption unit to the adsorption unit.

[0018] The dependent claims describe preferred embodiments of the invention.

[0019] Preferably, the gas separation system comprises a second conveying unit configured to convey the discharged adsorbent from the desorption unit to the adsorption unit. This allows for a cyclical flow of the adsorbent from the adsorption unit to the desorption unit and back again. The preheater is preferably arranged adjacent to the first conveying unit, and the cooler is preferably arranged adjacent to the second conveying unit.

[0020] Preferably, the preheater and the cooler are energetically coupled to transfer heat from the cooler to the preheater. Alternatively, cooling can be transferred from the preheater to the cooler. This energetic coupling saves energy required for heating and cooling the adsorbent, thus enabling more efficient operation of the gas separation system.

[0021] Furthermore, it is preferable to have the preheater and cooler energetically coupled via a heat exchanger. A heat exchanger enables a particularly efficient energy coupling of the preheater and cooler, allowing the gas separation system to be operated very efficiently and cost-effectively for CO2 separation. The heat exchanger can, for example, incorporate a heat pump or heat pipes.

[0022] Alternatively, the preheater and the cooler are preferably energetically coupled by means of a thermal conducting medium, wherein the thermal conducting medium is configured to cool the adsorbent in the cooler and to warm it in the preheater. R.417049

[0023] - 4 -

[0024] Heat. This allows for a simple and cost-effective energy coupling between the preheater and the cooler. The heat transfer medium is typically water, air, or oil.

[0025] Preferably, the gas separation system includes a product gas recirculation system configured to introduce product gas from the desorption unit into the preheater to heat the adsorbent. The product gas is preferably drawn from a region of the desorption unit with a low water content. This enables efficient heat recovery. Furthermore, the product gas recirculation can reduce the water vapor partial pressure in the region of the adsorbent being heated, thereby lowering the dew point. This allows the preheater to be positioned directly adjacent to the desorption unit without the risk of water vapor condensing on the adsorbent.

[0026] The cooler and / or the preheater are preferably each separated from the desorption unit by an airlock. This ensures that no water vapor from the desorption unit enters the preheater or cooler and condenses there on the adsorbent.

[0027] Preferably, the cooler and / or preheater are each arranged between two airlocks. This allows the adsorbent to be heated or cooled at the cooler and / or preheater under a defined pressure and environment. Furthermore, the arrangement between two airlocks allows for the removal and storage of CO2 that has already been desorbed during heating in the preheater. Cooling between the two airlocks can take place in the cooler under a protective gas atmosphere, thus preventing degradation of the adsorbent through contact with oxygen.

[0028] Alternatively, the preheater and / or the cooler is integrated into the adsorption unit. Heating or cooling can take place at atmospheric pressure, whereby, for example, the adsorbent is cooled by ambient air in the cooler, and the warming ambient air is used to heat the adsorbent in the preheater. R.417049

[0029] -5 -

[0030] Preferably, the preheater is integrated into the first conveying unit and / or the cooler into the second conveying unit. A structural combination of the preheater and / or cooler with a conveying unit for the adsorbent can be advantageous according to the invention, for example, if the conveying takes place in pipelines that can incorporate thermal coupling. Thermal coupling can be achieved in particular by the first conveying unit to the desorption unit having thermal coupling with the second conveying unit from the desorption unit. This coupling can be implemented as a double pipe. Further thermal coupling is possible if an airflow is guided internally through the first and second conveying units. One embodiment can be pneumatic conveying, in which the conveying airflow is used for thermal coupling.

[0031] Furthermore, the invention relates to a method for separating CO2 from a gas stream using the gas separation system described above. In the method, CO2 is adsorbed from the gas stream in an adsorption unit using an adsorbent. Subsequently, the adsorbent is heated in a preheater to a defined first temperature above the dew point in the desorption unit. The CO2 adsorbed onto the adsorbent is then desorbed in the desorption unit. After desorbed desorption, the adsorbent is cooled in a cooler to a defined second temperature below the dew point in the desorption unit. The method can be carried out in batches or continuously. Desorption is carried out, in particular, at a defined pressure and a defined temperature. The pressure is, in particular, below ambient pressure and the temperature is above ambient temperature.The temperature in the adsorption unit is controlled. By heating the adsorbent above its dew point and cooling it below its dew point, condensation of water on the adsorbent in the desorption unit can be prevented. Furthermore, separate heating and cooling can accelerate the desorption and adsorption steps.

[0032] Preferably, after desorbing, the adsorbent is cooled in the desorption unit to a temperature just above the dew point. This prevents R.417049 from

[0033] - 6 -

[0034] Water vapor condenses on the adsorbent in the desorption unit. Furthermore, cooling within the desorption unit allows the subsequent cooling in the cooler to be more efficient and faster.

[0035] Brief description of the drawings

[0036] Exemplary embodiments of the invention are described in detail below with reference to the accompanying drawings. The drawing shows:

[0037] Figure 1 shows a schematic view of a gas separation system according to a first embodiment of the invention,

[0038] Figure 2 shows a schematic view of a gas separation system according to a second embodiment of the invention.

[0039] Figure 3 shows a schematic view of a gas separation system according to a third embodiment of the invention.

[0040] Figure 4 shows a schematic view of a gas separation system according to a fourth embodiment of the invention.

[0041] Figure 5 shows a schematic view of a gas separation system according to a fifth embodiment of the invention and

[0042] Figure 6 schematic line diagrams of the water content, CO2 content, temperature and pressure during the process according to the invention in the gas separation plant.

[0043] Embodiments of the invention

[0044] Preferably, all identical components, elements and / or units in all figures are provided with the same reference numerals.

[0045] Below, with reference to Figures 1 to 6, a gas separation system 1 for separating CO22 from a gas stream 3 using a granular adsorbent 4 and an associated R.417049 are described.

[0046] - 7 -

[0047] The process for separating CO2 2 from the gas stream using the gas separation plant 1 is described in detail.

[0048] Figure 1 schematically shows the gas separation system 1 for separating CO22 from the gas stream 3 using the granular adsorbent 4. The gas separation system 1 has an adsorption unit 10 which can adsorb CO22 from the gas stream 3 using the adsorbent 4. Furthermore, the gas separation system 1 has a desorption unit 2 which can desorb CO22 from the adsorbent 4 at a defined pressure p and a defined temperature T.

[0049] The gas separation plant 1 also includes a first conveying unit 31, which can convey the CO22-loaded adsorbent 4 from the adsorption unit 10 to the desorption unit 20. Furthermore, the gas separation plant 1 includes a second conveying unit 32, which can convey the discharged adsorbent 4 from the desorption unit 20 to the adsorption unit 10. Thus, in a continuous process, CO22 can be adsorbed onto the adsorbent 4 at the adsorption unit 10 and subsequently conveyed by the first conveying unit 31 to the desorption unit 20, where the adsorbed CO22 can be desorbed. After desorbed, the discharged adsorbent 4 can be conveyed again to the adsorption unit 10 by the second conveying unit 32 to adsorb further CO22 from the gas stream 3.

[0050] Furthermore, the gas separation system 1 comprises a preheater 41 and a cooler 42. The preheater 41 is located adjacent to the first conveying unit 31 and is configured to heat the adsorbent 4 conveyed into the desorption unit 20 to a defined initial temperature T1 above the dew point T4 in the desorption unit 20. The cooler 42, located adjacent to the second conveying unit 32, is configured to cool the adsorbent 4 conveyed from the desorption unit 20 to a defined temperature T2 below the dew point T4.

[0051] The pressure p in desorption unit 20 can be, for example, 100 mbar, so that the dew point T4 is approximately 45°C. At a pressure p of 50 mbar in desorption unit 20, the dew point would only be 33°C. In R.417049

[0052] - 8 -

[0053] Desorption unit 20 can operate at temperatures around 100°C to desorb the CO2 2 from the adsorbent 4.

[0054] The preheater 41 and the cooler 42 are each separated from the desorption unit 20 by means of an airlock 46.

[0055] A condenser 21 is arranged on the desorption unit 20, at which the desorbed CO2 2 is condensed and removed. Furthermore, a vacuum pump 22 is arranged on the desorption unit 20, which can set a defined pressure p in the desorption unit 20 and can separate the desorbed and condensed CO2 2 and water from the desorption unit 20.

[0056] A blower 5 is arranged at the adsorption unit 10, which can convey the gas stream 3 towards the adsorption unit 10. The gas stream 3 leading to the adsorption unit 10 contains CO2 2. In contrast, the gas stream 3 leaving the adsorption unit 10 contains little or no CO2 2, as this has been adsorbed by the adsorbent 4.

[0057] The preheater 41 and the cooler 42 are energetically coupled to each other by means of a thermal medium 44. The thermal medium 44 can cool the adsorbent 4 in the cooler 42 and heat it in the preheater 41. The thermal medium can be, for example, water, air, or oil.

[0058] The granular adsorbent 4 is preferably an ion exchange resin.

[0059] Figure 2 shows the gas separation system 1 according to a second embodiment of the invention. The second embodiment is similar to the first embodiment and differs in particular in that the cooler 42 and the preheater 41 are each arranged between two airlocks 46. This allows the pressure in the preheater 41 and the cooler 42 to be reduced, so that heating and cooling can take place, for example, at a pressure p of 200 mbar. This embodiment can be advantageous if an adsorbent 4 is used that releases CO22 even with a small temperature change. Due to the encapsulated design R.417049

[0060] - 9 -

[0061] Between two locks 46, the CO22 desorbed in the preheater 41 or cooler 42 can be captured and separated.

[0062] Figure 3 shows a third embodiment of the gas separation system 1. The third embodiment is similar to the first embodiment and differs essentially in the energetic coupling of the preheater 41 and the cooler 42.

[0063] In the third embodiment, the preheater 41 and the cooler 42 are arranged spatially adjacent to each other and energetically coupled by means of a heat exchanger 43. The heat exchanger 43 can, for example, be designed as a solid-state heat exchanger. Alternatively, the heat can be transferred by another energy carrier. For example, the heat exchanger 43 can have heat pipes.

[0064] Figure 4 shows a fourth embodiment of the gas separation system 1. This fourth embodiment is similar to the first embodiment and differs essentially in the arrangement of the preheater 41 and the cooler 42 on the adsorption unit 10. Atmospheric pressure can be present in the preheater 41 and the cooler 42, with the preheater 41 and the cooler 42 serving only to change the temperature. The preheater 41 and the cooler 42 are energetically coupled by means of the thermal medium 44, whereby air is preferably used as the thermal medium 44, which can, for example, be diverted from the gas stream 3 and first cools the adsorbent 4 in the cooler 42, thereby heating the thermal medium 44. The heat absorbed in the cooler 42 can be transferred through the thermal medium 44 in the preheater 41 to the adsorbent 4 in order to heat the adsorbent 4.

[0065] Figure 5 shows a fifth embodiment of the gas separation system 1. The fifth embodiment is similar to the first embodiment and differs essentially in the integration of the preheater 41 and the cooler 42 into the desorption unit 20. The gas separation system 1 has a product gas recirculation 45, which introduces product gas desorbed in the desorption unit 20 into the preheater 41 to heat the adsorbent 4.

[0066] - 10 -

[0067] In the first part of the desorption unit 20, water is increasingly desorbed, and in the second part, CO22 is increasingly desorbed. A staged separation of the desorbed water and CO22 allows the water-poor, CO2-rich product gas stream generated in the second part of the desorption unit 20 to be returned to the preheater 41 integrated into the desorption unit 20 via the product gas recirculation 45. This reduces the water vapor partial pressure in the area of ​​the preheater 41, thereby lowering the dew point T4.

[0068] Figure 6 shows different line diagrams of parameters of the gas separation plant 1 for different steps in the process for separating CO2 2 from the gas stream 3.

[0069] The first diagram shows the proportion of adsorbed water 6 in the adsorbent 4 as a function of time t. After adsorption S1 in the adsorption unit 10, the adsorbent 4 has a high proportion of adsorbed water 6.

[0070] By heating S2 of the adsorbent 4 in the preheater 41, a small amount of water 6 desorbs. The adsorbent 4 is then conveyed through the airlock 46 into the desorption unit 20 and heated further at a reduced pressure p. This desorbs a large portion of the water 6, resulting in a significant decrease in the proportion of adsorbed water 6 in the adsorbent 4.

[0071] After desorption S3 in the desorption unit 20, the adsorbent 4 is passed through a further airlock 46 into the cooler 42 and cooled further there. Due to the cooling S4, no further water 6 is desorbed or adsorbed, so that the proportion of adsorbed water 6 in the adsorbent 4 remains low.

[0072] The second diagram shows the proportion of adsorbed CO22 in the adsorbent 4 as a function of time t. After adsorption S1, the adsorbent 4 exhibits a maximum of adsorbed CO22. Heating S2 of the adsorbent 4 in the preheater 41 does not yet reach a state in which CO22 is desorbed from the adsorbent 4, so the proportion of adsorbed CO22 remains at a high level after heating S2.

[0073] - 11 -

[0074] At the level of desorption S3 in the desorption unit 20, the pressure p is reduced or the temperature T is increased to such an extent that a large proportion of the adsorbed CO22 is desorbed.

[0075] The third diagram shows the temperature T of the adsorbent 4 as a function of time t during the process steps in the gas separation unit 1. During adsorption S1, the adsorbent 4 is at ambient temperature. During heating S2 in the preheater 41, the temperature T is raised to an initial temperature T1 above the dew point T4 in the desorption unit 20.

[0076] For desorption S3, the adsorbent 4 is further heated to a process temperature T5 in the desorption unit 20. After a large portion of the adsorbed CO22 has been desorbed from the adsorbent 4, the adsorbent 4 is cooled in the desorption unit 20 to a third temperature T3 just above the dew point T4. This prevents the adsorbent 4 from degrading outside the desorption unit 20.

[0077] During cooling S4, the adsorbent 4 in the cooler 42 is cooled to a defined second temperature T2 below the dew point T4. The second temperature T2 preferably lies between the dew point T4 and the ambient temperature.

[0078] The third diagram shows the pressure p as a function of time t. During adsorption (S1), heating (S2), and cooling (S4), the pressure p corresponds to the ambient pressure. During desorption (S3), the pressure p is reduced to a defined pressure p in order to desorb the adsorbed CO22 from the adsorbent 4.

[0079] Thus, by providing the preheater 41 and the cooler 42, the condensation of water vapor on the adsorbent 4 within the desorption unit 20 can be avoided. Furthermore, the energy coupling of the preheater 41 and the cooler 42 can increase the efficiency of the gas separation system 1 and reduce the cycle time.

Claims

R.417049 - 12 - Claims 1. Gas separation plant (1) for separating CO2 (2) from a gas stream (3), in particular an air stream (3), by means of a granular adsorbent (4), comprising an adsorption unit (10) which is configured to adsorb the CO2 (2) from the gas stream (3), in particular air stream (3), by means of the adsorbent (4), a desorption unit (20) which is set up to desorb the CO2 (2) from the adsorbent (4) by means of a defined pressure (p) and a defined temperature (T), a first conveying unit (31) which is set up to convey the adsorbent (4) loaded with CO2 (2) from the adsorption unit (10) to the desorption unit (20), a preheater (41) and a cooler (42), wherein the preheater (41) is configured to heat the adsorbent (4) conveyed into the desorption unit (20) to a defined first temperature (T1) above the dew point (T4) in the desorption unit (20), and wherein the cooler (42) is configured to cool adsorbent (4) conveyed from the desorption unit (20) to a defined second temperature (T2) below the dew point (T4).

2. Gas separation plant (1) according to claim 1, comprising a second conveying unit (32) which is configured to convey the discharged adsorbent (4) from the desorption unit (20) to the adsorption unit (10).

3. Gas separation system (1) according to one of the preceding claims, wherein the preheater (41) and the cooler (42) are energetically coupled to transfer heat from the cooler (42) to the preheater (41). R.417049 - 13 - 4. Gas separation system (1) according to claim 3, wherein the preheater (41) and the cooler (42) are energetically coupled by means of a heat exchanger (43).

5. Gas separation system (1) according to claim 3, wherein the preheater (41) and the cooler (42) are energetically coupled by means of a heat transfer medium (44), wherein the heat transfer medium (44) is configured to cool the adsorbent (4) in the cooler (42) and to heat it in the preheater (41).

6. Gas separation system (1) according to one of the preceding claims, comprising a product gas recirculation (45) which is configured to introduce a product gas from the desorption unit (20) into the preheater (41) in order to heat the adsorbent (4).

7. Gas separation system (1) according to one of the preceding claims, wherein the cooler (42) and / or the preheater (41) are each separated from the desorption unit (20) by means of a lock (46).

8. Gas separation system (1) according to claim 7, wherein the cooler (42) and / or the preheater (41) is arranged between two airlocks (46).

9. Gas separation system (1) according to one of claims 1 to 7, wherein the preheater (41) and / or the cooler (42) is integrated into the adsorption unit (10).

10. Gas separation system (1) according to one of claims 2 to 7, wherein the preheater (41) is integrated into the first conveying device (31) and / or the cooler (42) is integrated into the second conveying device (32).

11. Method for separating CO2 (2) from a gas stream (3), in particular an air stream (3), using a gas separation system (1) according to one of the preceding claims, comprising the steps: Adsorbing (S1) CO2 (2) from the gas stream (3), in particular air stream (3), by means of an adsorbent (4) in an adsorption unit (10), R.417049 - 14 - Heating (S2) the adsorbent (4) by means of a preheater (41), in particular in a preheater (41), to a defined first temperature (T1) above the dew point (T4) in a desorption unit (20), - Desorption (S3) of the CO2 (2) adsorbed on the adsorbent (4) in the desorption unit (20) and Cooling (S4) of the adsorbent (4) by means of a cooler (42), in particular in a cooler (42), down to a defined second temperature (T2) below the dew point (T4).

12. Method according to claim 11, wherein the adsorbent (4) in the desorption unit (20) is cooled after desorbing (S3) to a third temperature (T3) just above the dew point (T4).

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