A SYSTEM FOR CAPTURE OF CARBON DIOXIDE

Abstract

A system for capture of CO.sub.2 from a gaseous CO.sub.2-containing stream is provided. The system comprises a plurality of first inlets for stream; a plurality of first outlets for a treated stream having a reduced CO.sub.2-concentration; and a plurality of supported sorbent materials between the first inlets and outlets allowing a first flow path (A) during a CO.sub.2-adsorption phase. Each supported sorbent material possesses a first side for receiving stream and a second side from which stream exits. Optionally, the system comprises a second inlet for a desorption fluid; a second outlet; a sealer for closing the first inlets and outlets during a CO.sub.2-desorption phase creating a second flow path (B) for fluid comprising desorbed CO.sub.2 through adjacent supported sorbent materials to the second outlet wherefrom a CO.sub.2-enriched stream can exit.

Claims

1. A system for capture of carbon dioxide (CO2) from a gaseous CO2-containing stream, the system at least comprising: a plurality of first inlets for a gaseous CO2-containing stream; a plurality of first outlets for a treated stream having a reduced CO2-concentration compared to the gaseous CO2-containing stream; a plurality of supported sorbent materials placed between the plurality of first inlets and the plurality of first outlets allowing a first flow path (A) therethrough for the gaseous CO2-containing stream during a CO2-adsorption phase, wherein each supported sorbent material possesses a first side that during the CO2-adsorption phase can receive the gaseous CO2-containing stream and a second side from which a treated gaseous stream having a reduced CO2-concentration can exit the supported sorbent material; optionally, a second inlet for a desorption fluid; a second outlet for a CO2-enriched stream; a sealer comprising a pair of doors or plates which can close the plurality of first inlets and the plurality of first outlets during a CO2-desorption phase thereby creating a second flow path (B) for a fluid comprising desorbed CO2 through a plurality of adjacent supported sorbent materials to the second outlet from which a CO2-enriched stream can exit.

2. The system according to claim 1, wherein the supported sorbent materials comprise sorbent particles supported within a bed.

3. The system according to claim 2, wherein the supported sorbent materials have a bed depth of from 1 to 20 cm.

4. The system according to claim 1, wherein the supported sorbent materials are closed at the faces that are substantially perpendicular to the flow direction of the first flow path (A).

5. The system according to claim 1, wherein the supported sorbent materials have converging first inlets.

6. The system according to claim 5, wherein the first inlets of the supported sorbent materials are slanted.

7. The system according to claim 1, wherein the supported sorbent materials have diverging first outlets.

8. The system according to claim 7, wherein the first outlets of the supported sorbent materials are slanted.

9. The system according to claim 1, wherein the system comprises at least 5 supported sorbent materials.

10. The system according to claim 1, further comprising a filter placed upstream of the plurality of first inlets when in CO2 adsorption phase.

11. A process for capture of carbon dioxide (CO2) from a gaseous CO2-containing stream, the process at least comprising the steps of: (a) providing a gaseous CO2-containing stream; (b) introducing the gaseous CO2-containing stream via a plurality of first inlets; (c) passing the gaseous CO2-containing stream via a first flow path through the supported sorbent materials to a plurality of first outlets thereby adsorbing CO2 from the CO2-containing stream; (d) removing a treated stream from the first outlets having a reduced CO2-concentration compared to the gaseous CO2-containing stream; (e) sealing the plurality of first inlets and first outlets with a pair of doors or plates thereby creating a second flow path (B) for a fluid comprising desorbed CO2 through a plurality of adjacent supported sorbent materials to a second outlet; (f) desorbing the plurality of adjacent supported sorbent materials thereby releasing CO2 adsorbed to the supported sorbent materials and obtaining a CO2-enriched stream; (g) removing the CO2-enriched stream obtained in step (f) from the second outlet.

12. The process according to claim 11, wherein the desorbing in step (f) comprises passing a stream of a desorption fluid via the second flow path (B) from a second inlet through the plurality of adjacent supported sorbent materials to the second outlet.

13. The process according to claim 11, wherein the stream of desorption fluid in step (f) has a pressure of between 0.5-1.5 bara.

14. The process according to claim 12, wherein the second flow path (B) during desorbing in step (f) is through at least 5 subsequent supported sorbent materials in series.

15. The process according to claim 11, wherein the desorbing in step (f) comprises heating the supported sorbent materials, preferably starting with the supported sorbent materials placed the furthest away from the second outlet, followed by supported sorbent materials placed closer to the second outlet.

16. The process according to claim 11, further comprising the steps: (h) undoing the sealing of the plurality of first inlets and first outlets; (i) repeating steps (a)-(h) multiple times.

17. The process according to claim 3, wherein the supported sorbent materials have a bed depth of from 1 to 20 cm.

18. The system according to claim 9, wherein the system comprises at least 10 supported sorbent materials.

19. The process according to claim 13, wherein the stream of desorption fluid in step (f) has a pressure of between 0.9-1.1 bara.

20. The process according to claim 14, wherein the second flow path (B) during desorbing in step (f) is through at least 10 subsequent supported sorbent materials in series.

Description

[0062] Hereinafter the present invention will be further illustrated by the following non-limiting drawings. Herein shows:

[0063] FIG. 1 a schematic representation of a DAC system according to the present invention in adsorption phase;

[0064] FIG. 2 a schematic representation of a first embodiment of the DAC system according to FIG. 1 in desorption phase;

[0065] FIG. 3 a schematic representation of a second embodiment of the DAC system according to FIG. 1 in desorption phase;

[0066] FIG. 4 a schematic representation of a further embodiment of a DAC system according to the present invention in adsorption phase; and

[0067] FIG. 5 a schematic representation of the DAC system according to FIG. 4 in desorption phase.

[0068] In this respect it is noted that the orientation of the DAC system may be varied and may be such that the first flow path A is substantially horizontal, substantially vertical or at an angle. In case that the first flow path A would be substantially horizontal, then FIGS. 1-5 are top views. In case that the first flow path A would be substantially vertical, then FIGS. 1-5 are side views. Please note that the first flow path A may be parallel (see FIGS. 1-3) or perpendicular (see FIGS. 4-5) to second flow path B.

[0069] For the purpose of this description, same reference numbers refer to same or similar components or streams.

[0070] The DAC system of FIG. 1, generally referred to with reference number 1, shows a plurality of first inlets 2 for a gaseous CO.sub.2-containing stream 10; a plurality of first outlets 3 for a treated stream 20 having a reduced CO.sub.2-concentration compared to the gaseous CO.sub.2-containing stream 10; a plurality (i.e. five) of supported sorbent materials 4 placed between the plurality of first inlets 2 and the plurality of first outlets 3 allowing a first flow path (A; not shown) therethrough for the gaseous CO.sub.2-containing stream during a CO.sub.2-adsorption phase.

[0071] In the embodiment of FIG. 1 the supported sorbent materials 4 comprise sorbent particles supported within a bed. The supported sorbent materials 4 are closed at the faces substantially perpendicular to the flow direction of the first flow path A and the second flow path B. In case FIG. 1 would be a side view, then these faces would be the top 4a and bottom 4b of the supported sorbent materials 4. The supported sorbent materials 4 have converging first inlets 2, which are slanted. Furthermore, the supported sorbent materials 4 have diverging first outlets 3, which are also slanted.

[0072] Typically, the system 1 will typically also comprise a filter (not shown) placed upstream of the plurality of first inlets 2 when in CO.sub.2 adsorption phase. This filter avoids that particulate material can enter the system 1.

[0073] During use of the system of FIG. 1, a gaseous CO.sub.2-containing stream 10 will be introduced via the plurality of first inlets 2 and pass via the first flow path through the supported sorbent materials 4 to the plurality of first outlets 3 thereby adsorbing CO.sub.2 from the CO.sub.2-containing stream. A treated stream 20 will be removed from the first outlets 3. This treated stream 10 will have a reduced CO.sub.2-concentration compared to the gaseous CO.sub.2-containing stream 10.

[0074] After a certain time has passed (or once a CO.sub.2 saturation level for the supported sorbent materials has been obtained), the adsorption phase as shown in FIG. 1 will be ended, and a desorption phase will start. This desorption phase will be illustrated with reference to FIGS. 2 and 3.

[0075] FIGS. 2 and 3 show schematic representations of a first and a second embodiment of the DAC system according to FIG. 1 when in desorption phase.

[0076] In the embodiment of FIG. 2, the system 1 further comprises a second inlet 5 for a desorption fluid 30 (such as steam) and a second outlet 6 for a CO.sub.2-enriched stream 40. Furthermore, the system comprises a sealer 7 which can close the plurality of first inlets 2 and the plurality of first outlets 3 during the CO.sub.2-desorption phase as shown in FIGS. 2 and 3. The sealer 7 is in the form of a pair of doors or plates and creates a second flow path B for a fluid comprising desorbed CO.sub.2 through the plurality of adjacent supported sorbent materials 4 to the second outlet 6 from which the CO.sub.2-enriched stream 40 can exit. In the embodiment of FIGS. 1-3, the second flow path B (in desorption phase) is substantially parallel to the first flow path A (in adsorption phase); initially, the second flow path B is contrary to the first flow path A, then the same and subsequently contrary again. In an alternative embodiment (not shown), the second flow path B has a direction which is initially the same as the first flow path A (and subsequently contrary, and so on).

[0077] After sealing the plurality of first inlets 2 and first outlets 3 by the sealer 7, a second flow path B for desorbed CO.sub.2 is created. The flow path B runs through the plurality of adjacent supported sorbent materials 4 in series to the second outlet 6.

[0078] During the desorption phase, the plurality of adjacent supported sorbent materials 4 are desorbed thereby releasing CO.sub.2 adsorbed to the supported sorbent materials 4 and obtaining the CO.sub.2-enriched stream 40. The obtained CO.sub.2-enriched stream 40 is removed from the system 1 via the second outlet 6.

[0079] In the embodiment of FIG. 2, the desorbing comprises passing a desorption fluid 30 (e.g. steam) from the second inlet 5 via the second flow path B through the plurality of adjacent supported sorbent materials 4 to the second outlet 6. As can be seen, the second flow path B is through five subsequent supported sorbent materials 4 in series.

[0080] In the embodiment of FIG. 3, no second inlet 5 is present. In this case the desorbing takes place by heating the supported sorbent materials 4 (no heating being shown). To this end, first the supported sorbent materials 4 placed the furthest away from the second outlet 6 are heated, progressively followed by heating the supported sorbent materials 4 placed closer to the second outlet 6. This progressive heating of different supported sorbent materials 4 will create the second flow path B. It goes without saying that heating may also be applied in the embodiment of FIG. 2. For the heating, heaters (not shown) are used. Preferably, electrical heating is used, powered by renewable energy.

[0081] After the desorption phase has ended, the adsorption/desorption cycle can be repeated.

[0082] In FIGS. 4 and 5 a further embodiment of the DAC system according to the present invention is shown. FIG. 4 shows the adsorption phase and FIG. 5 the desorption phase. In this embodiment, the flow path B in the desorption phase is substantially perpendicular to the flow path A (not shown) in the adsorption phase.

EXAMPLES

Example 1

[0083] The system of FIGS. 1 and 2 was used to illustrate the capture of CO.sub.2 from air, whilst using five, ten and twenty beds of supported sorbent materials (reference number 4 in FIGS. 1 and 2). As supported sorbent materials, sorbent particles supported within a bed were used. As sorbent particles, trilobe extrudates of 1.6 mm diameter were used. Each sorbent bed had a bulk density of 750 kg/m.sup.3 and a CO.sub.2 adsorption capacity of 0.4 mol CO.sub.2/kg sorbent. The volume of the sorbent beds, the volume of the inlets and the volume of the outlets were all equal.

[0084] As desorption fluid, steam (120 C., 1 bara) was used.

[0085] The composition of the CO.sub.2-enriched stream 40 at the second outlet 6 during desorption was calculated on the basis that the flow in the beds 4 themselves was plug flow and that the flow in the channels in between the beds was fully back-mixed. This will be the case in FIG. 2 as during desorption vapour is displaced from each bed at the same time along channels (in between the beds) over the full length of flow path B. This leads to efficient mixing of the vapour displaced from the beds with that in the channels in between the beds. Initially, the composition at the second outlet 6 will be essentially air that is displaced from the beds. This air is vented. Subsequently, a front of desorbed CO.sub.2 will reach the second outlet 6. The sharpness of this front is determined by the mixing pattern of alternate plug flow and back-mixed sections as described above. At a given point (the switch point in Table 1 below), venting is stopped and desorbed CO.sub.2 is collected.

[0086] Table 1 below shows the overall CO.sub.2 loss and obtained CO.sub.2 purity when using five, ten and twenty subsequent passes (one pass representing one bed of sorbent particles).

TABLE-US-00001 TABLE 1 CO.sub.2 purity of Overall CO.sub.2 collected loss via vent stream after [fraction of switch point total CO.sub.2 [vol. % on Nr. of passes desorbed] dry basis] At 99% switch point.sup.1 5 0.330 99.90 10 0.233 99.95 20 0.153 >99.95 At 90% switch point.sup.1 5 0.168 99.09 10 0.120 99.39 20 0.078 99.55 .sup.1Represents the vol. % of CO.sub.2 present in the CO.sub.2-enriched stream 40 that is removed from the system via the second outlet 6 when the switch is made from venting to collection of the CO.sub.2-enriched stream 40 at the second outlet 6.

[0087] As can be seen from Table 1, by passing a stream of steam as desorption fluid (via the second flow path B from the second inlet 5) through the plurality of adjacent beds 4 to the second outlet 6 in series) during the desorption phase, a high purity CO.sub.2-stream is obtained (with very low air contamination), with a relatively low CO.sub.2 loss. It can be seen from Table 1 that a CO.sub.2 purity of above 99 vol. % (on a dry basis) is readily achieved for a system with 5 sorbent beds in series.

[0088] Even better results were obtained by passing the desorption fluid through at least 10 and at least 20 beds in series. Increasing the number of beds gives an increased CO.sub.2 purity and a lower loss of CO.sub.2 via the vent. As a comparison, if the same method was used for a single bed with similar inlet and outlets, a CO.sub.2 purity of only about 50 vol. % would be achieved.

DISCUSSION

[0089] As can be seen from Example 1, the system and process according to the present invention allows for an effective way of capturing CO.sub.2 from a CO.sub.2-containing stream, whilst obtaining a high purity (>99.0 vol. % on a dry basis) CO.sub.2-stream and a low CO.sub.2 loss (<20% of the total desorbed CO.sub.2, preferably <10% of the total desorbed CO.sub.2).

[0090] Further, the CO.sub.2 purity obtained can be increased to 99.9 vol. % on a dry basis and above, by increasing the number of sorbent beds and delaying the switch point before which the outlet stream is vented.

[0091] The person skilled in the art will readily understand that many modifications may be without departing from the scope of the invention.