Process for the production of synthesis gas

• US 4,782,096 A
• Filed: 09/16/1987
• Issued: 11/01/1988
• Est. Priority Date: 02/10/1986
• Status: Expired due to Term

• Current Assignee: Foster Wheeler USA Corporation (John Wood Group PLC)
• Original Assignee: Foster Wheeler USA Corporation (John Wood Group PLC)
• Inventors: Banquy, David
• Primary Examiner(s): Mars, Howard T.
• Application Number:
  US07/097,387
• Time in Patent Office: 412 Days
• Field of Search: 518/704, 518/713
• US Class Current: 518/704
• CPC Class Codes: C01B 2203/046 Purification by cryogenic separation
• CPC Class Codes: C01B 2203/047 the impurity being carbon monoxide
• CPC Class Codes: C01B 2203/0475 the impurity being carbon dioxide
• CPC Class Codes: C01B 2203/048 the impurity being an organic compound
• CPC Class Codes: C01B 3/382 Multi-step processes
• CPC Class Codes: C01B 3/501 by diffusion
• CPC Class Codes: C01B 3/506 at low temperatures
• CPC Class Codes: C01B 3/56 by contacting with solids; Regeneration of used solids C01B3/508 takes precedence
• CPC Class Codes: C07C 27/06 by hydrogenation of oxides of carbon
• CPC Class Codes: C07C 29/1518 one step being the formation of initial mixture of carbon oxides and hydrogen for synthesis
• CPC Class Codes: C07C 31/04 Methanol
• CPC Class Codes: C07C 31/12 containing four carbon atoms
• CPC Class Codes: C07C 41/01 Preparation of ethers
• CPC Class Codes: C07C 43/043 Dimethyl ether
• CPC Class Codes: Y02P 30/00 Technologies relating to oil refining and petrochemical industry

Abstract

A process for producing an organic compound from a hydrocarbon containing feedstock. The feedstock is divided into two fractions. The first is subject to a primary steam reforming reaction. The reaction product is then combined with the second fraction and reacted with a free oxygen-rich gas in a secondary reforming reactor to form a synthesis gas having a ratio of

H.sub.2 /[2(CO)+3(CO.sub.2)]

between 0.80 and 1.00. The synthesis gas is then mixed with a hydrogen-rich stream, which has been separated from a purge gas from the synthesis loop, to form a final synthesis gas. The final synthesis gas is injected into a synthesis loop in which the desired organic compound is formed. The purge gas extracted from the loop is subjected to a physical separation to form a hydrogen-rich gas stream and a residual gas stream. A portion of the hydrogen-rich stream is recycled to form the final synthesis gas.

Claims

1. A process for producing an oxygenated hydrocarbon or mixtures thereof from a hydrocarbon containing feedstock, which comprises:

(a) dividing said feedstock into two fractions,

(b) subjecting the first fraction from (a) to a primary steam reforming reaction, by mixing said fraction with steam and heating the mixture thereof by indirect heat exchange, in the presence of a reforming catalyst, to form a gaseous effluent including hydrogen at a temperature between 650° and

850°

C.,

(c) mixing the gas effluent from (b) with the second fraction from (a),

(d) reacting in a single stage the gas mixture from (c) with a free oxygen-rich gas, in a secondary reforming reactor operating under essentially adiabatic conditions, and containing a single bed of catalyst, thus producing a synthesis gas at a temperature between 850° and

1250°

C., containing a percent methane equivalent of less than one-tenth of that of the gas mixture from (c), and having a Z ratio of between 0.80 and 1.00, where Z is defined as;

space="preserve" listing-type="equation">Z=moles H.sub.2 [2(moles CO)+3(moles CO.sub.2)]

(e) mixing the gas effluent from (d) with a hydrogen-rich stream free from carbon oxides to form a final synthesis gas stream,

(f) injecting said final synthesis gas into a synthesis loop, forming said oxygenated hydrocarbon or mixtures thereof in said loop, and extracting from said loop a purge gas stream,

(g) separating said purge gas stream in a physical separation to form a hydrogen-rich gas stream free from carbon oxides and a residual gas stream, and

(h) recycling at least a portion of said hydrogen-rich gas stream to step (e).

2. The process of claim 1 wherein said purge gas stream is first subjected to a shift conversion reaction, by reacting said purge gas with steam in the presence of a shaft catalyst, and then to said physical separation.

3. The process of claim 1 wherein said purge gas stream is subjected to a shift conversion reaction, by reacting said purge gas with steam in the presence of a shift catalyst, and then to the removal of carbon dioxide from said shift converted gas, and then to said physical separation.

4. The process of claims 1, 2, or 3, wherein the gas effluent temperature from said steam reforming reaction in step (b) is between about 720°

and about 780°

C.

5. The process of claims 1, 2, or 3, wherein the gas effluent temperature from said secondary oxygen reforming reactor is between about 950°

and about 1100°

C.

6. The process of claims 1, 2, or 3 wherein the gas effluent from said secondary oxygen reforming reactor has a z ratio of between 0.88 and 0.98.

7. The process of claims 1, 2, or 3 wherein the gas mixture from (e) has a z ratio essentially equal to 1.00.

8. The process of claims 1, 2, or 3 wherein said free oxygen-rich gas has a molecular oxygen content of at least 80% by volume.

9. The process of claims 1, 2, or 3 wherein said free-oxygen-rich gas has a molecular oxygen content of at least 95% by volume.

10. The process of claims 1, 2, or 3 wherein said first fraction of the feedstock treated in the primary steam reforming reactor is between about 5 and about 60% of the total feedstock.

11. The process of claim 10 wherein said first fraction of the feedstock treated in the primary steam reforming reactor is between 10% and 30% of the total feedstock.

12. The process of claims 1, 2, or 3 wherein the pressure in the primary steam reforming reactor and the secondary oxygen reforming reactor is above 30 bars.

13. The process of claims 1, 2, or 3 wherein said physical separation in step (g) is achieved by selective absorption over molecular sieves.

14. The process of claims 1, 2, or 3 wherein said physical separation in step (g) is achieved by selective diffusion though a membrane.

15. The process of claims 1, 2, or 3 wherein said physical separation in step (g) is achieved by distillation at low temperature.