Process for the production of synthesis gas

1. A process for the production of a synthesis gas for use in the production of chemical compounds from a hydrocarbon feedstock containing higher hydrocarbons comprising the steps of:

(a) splitting the hydrocarbon feedstock into at least two streams, a first hydrocarbon feedstock stream and a second hydrocarbon feedstock stream in the form of a by-pass hydrocarbon feedstock stream;

(b) adding steam to the first hydrocarbon feedstock stream and pre-reforming this stream to a pre-reformed gas containing methane, hydrogen, carbon monoxide, carbon dioxide and higher hydrocarbons;

(c) combining the bypassed hydrocarbon feedstock stream of step (a) with the pre-reformed gas of step (b) and pre-reforming the thus combined gas to a pre-reformed gas containing methane, hydrogen, carbon monoxide and carbon dioxide, wherein a steam-to-carbon ratio of the pre-reforming in step (b) is higher than a steam-to-carbon ratio of the pre-reforming in step (c);

(d) reforming in a reforming stage the pre-reformed gas of step (c) into a synthesis gas containing hydrogen, carbon monoxide and carbon dioxide.

2. The process according to claim 1 further comprising the step of a hydrodesulfurization stage removing sulphur compounds in the hydrocarbon feedstock prior to splitting in step (a).

3. The process according to claim 1 further comprising prior to the pre-reforming stage of step (b) or (c) the step of: a hydrodesulfurization stage removing sulphur compounds in the first hydrocarbon feed stock stream, or the second hydrocarbon feedstock stream, or both.

4. The process according to claim 1 in which the pre-reforming stage of step (b) is operated at a steam-to-carbon ratio in the range 0.60-1.30 calculated as steam-to-carbon ratio, while the pre-reforming stage of step (c) is operated at a lower steam-to-carbon ratio and which is in the range 0.30-0.80 calculated as steam-to-carbon ratio.

5. The process according to claim 1 in which the first hydrocarbon feedstock stream formed after the split is at least 30% vol of the hydrocarbon feedstock.

6. The process according to claim 1 in which the steam addition of step (b) is high pressure steam from a process condensate stripper located downstream the reforming stage (d).

7. The process of claim 1 in which the steam is solely added to the first hydrocarbon feedstock stream passed to the pre-reforming stage of step (b).

8. The process according to claim 1 in which the mixture resulting from adding steam to the first hydrocarbon feedstock stream is preheated to a feed temperature of 380-480° C. before entering the pre-reforming stage of step (b).

9. The process according to claim 1 in which the pre-reforming stage of either step (b) or (c) or both is adiabatic pre-reforming under the presence of catalyst.

10. The process according to claim 9 in which the catalyst is a solid nickel containing steam reforming catalyst suitable for operation at temperatures below 650° C.

11. The process according to claim 1 in which the reforming stage of step (d) consists of SMR, HER, ATR, CPO, POx, or a combination thereof.

12. The process according to claim 11 in which the reforming stage is ATR or CPO or POx.

13. The process according to claim 1 in which the synthesis gas of step (d) is subjected to synthesis of liquid hydrocarbons, including the Fischer-Tropsch synthesis and synthesis of gasoline.

14. The process of claim 13 , in which tail gas or off-gas from the synthesis of the liquid hydrocarbons is recycled to the pre-reforming stage (b), pre-reforming stage (c), reforming stage (d), or a combination thereof.

15. The process according to claim 1 , wherein the hydrocarbon feedstock containing higher hydrocarbons is selected from associated gas or shale gas or associated petroleum gas.