INCREASING CO/CO2 RATIO IN SYNGAS BY REVERSE WATER GAS SHIFT

Abstract

The present application relates to a production plant comprisinga synthesis gas generation step (1) arranged to receive a hydrocarbon or carboneous feedstock (2) and in a synthesis gas generation process provide a syngas, a production step (4) arranged to receive the syngas and produce a product stream (5), a reverse water gas shift step (4) arranged to receive a H2 rich gas stream (7) and a C02 feed (8) and in a RWGS step obtain a reverse shifted gas stream (9), andmeans (10) for adding said reverse shifted gas stream (9) to the synthesis gas stream (3).

Claims

1. Production plant comprising a synthesis gas generation step arranged to receive a hydrocarbon or carboneous feed stock and in a synthesis gas generation process provide a syngas a production step arranged to receive the syngas and produce a product stream a reverse water gas shift step arranged to receive a H.sub.2 rich gas stream and a CO.sub.2 feed and in a RWGS step obtain a reverse shifted gas stream, and means for adding said reverse shifted gas stream to the synthesis gas stream.

2. Production plant according to claim 1 wherein the production step is a methanol synthesis loop arranged to receive the syngas/reverse shifted gas mixture and produce a Methanol-rich product stream.

3. Production plant according to claim 1 wherein the production step is a purification unit producing a product gas rich in Carbonmonoxide.

4. Production plant according to claim 1, wherein the synthesis gas generation step is a reforming step, a gasification step, or a partial oxidation step.

5. Production plant according to claim 1, wherein the reverse shifted gas stream is provided downstream the synthesis gas generation step.

6. Production plant according to claim 1, wherein the RWGS step comprises a hydrogen recovery unit upstream the RWGS step.

7. Production plant according to claim 1, any of the proceeding claims wherein the H.sub.2 rich gas stream is a purge gas 12 from the production step.

8. Production plant according to claim 1, wherein the CO.sub.2 feed is provided from underground natural CO.sub.2 rich gas reservoir.

9. Production plant according to claim 1, wherein the CO.sub.2 feed is provided from a purification unit such as amine wash, PSA, etc. removing CO.sub.2 from a synthesis gas, flue gas, or natural gas.

10. Production plant according to claim 1, wherein the RWGS step comprises a High Temperature Shift Catalyst (e.g. Topse SK-201 or SK-501) or a UltraHigh Temperature Shift Catalyst.

11. Production plant according to claim 1, wherein the hydrogen recovery unit is a membrane unit, PSA unit or cryogenic unit.

12. Production plant according to a claim 3 wherein the purification unit producing a CO stream or CO-rich stream is a membrane unit or a cryogenic unit.

13. A process for adjusting the CO/CO.sub.2 ratio in a synthesis gas, said process comprising in a Methanol loop producing a Methanol stream from a synthesis gas in a RWGS loop producing in a RWGS step a shifted gas stream at least from a CO.sub.2 feed and a H2 rich gas stream, and adding the produced shifted gas stream to the syngas upstream the Methanol loop.

14. A process according to claim 13 wherein the H.sub.2 rich gas stream is a purge gas from the Methanol loop.

15. A process according to claim 13, wherein the shifted gas stream is produced over a High Temperature Shift Catalyst (e.g. TopsSK-201 or SK-501) or a UltraHigh Temperature Shift Catalyst.

16. A process according to claim 13, wherein the RWGS inlet temp is 250-750 C.

17. A process according to claim 13, wherein the RWGS outlet temp is 200-700 C.

18. A process according to claim 13, wherein the produced reverse shifted gas has a CO/CO.sub.2 ratio of 0.05-3.

Description

[0036] FIG. 1 shows a diagram of the plan/process according to the present invention wherein a synthesis gas generation step 1 is arranged to receive a hydrocarbon or carboneous feed stock 2 and in a synthesis gas generation process provide a syngas 3. A production step 4 is arranged to receive the syngas and produce a product stream (5). A reverse water gas shift step 6 is arranged to receive a H.sub.2 rich gas stream 7 and a CO.sub.2 feed 8 and in a RWGS process obtain a reverse shifted gas stream 9. The plant/process furthermore has means 10 for adding said reverse shifted gas stream to the synthesis gas stream. Upstream the reverse water gas shift process a H.sub.2 recovery unit 11 can be arranged to provide a gas stream 7 which has an increased H.sub.2 concentration compare to what is received from the production step 4. Such a H.sub.2 recovery unit may for example be used where a purge 12 from the production step 4 is used to provide the H.sub.2 rich stream. From the recovery unit a residual gas stream 13 may be provided e.g. to burners etc.

[0037] Thus according to the present invention is provided a process and a plant by which a mixture of CO.sub.2 and H.sub.2 stream is send to a reactor with a catalyst active towards the Water Gas Shift Reaction, a RWG shift (CO.sub.2+H.sub.2CO+H.sub.2O) can be obtained, improving the CO/CO.sub.2 ratio, and thus the reactivity of the synthesis gas, reducing the required catalyst volume and/or heat transfer area in the production step, such as a methanol synthesis reactor. The present process and plant may be a particular advantage for revamp projects, where the size of reformer and/or Methanol reactor is given by existing structures.