Method for operating a reformer furnace and reforming plant

1. A method for producing a synthesis-gas product gas and at least one product vapor stream, the method comprising:

catalytic steam reforming a hydrocarbonaceous feedstock in a steam reformer with variable production capacity of the synthesis-gas product gas so as to form the synthesis-gas product gas and the at least one product vapor stream, the steam reformer including a plurality of catalyst-containing reformer tubes and a reformer furnace with burners for firing the reformer tubes;

cooling the hot synthesis-gas product gas stream in at least one heat exchanger by indirect heat exchange against a stream of water so as to form a cooled synthesis-gas product gas stream and a first partial vapor stream; and

supplying the first partial vapor stream to the product vapor stream, wherein the reforming furnace is operated so as to include the following steps:

(a) supplying a burner feedstock including fuel, combustion air and at least one flue gas recirculation stream to the reformer furnace,

(b) burning the burner feedstock in the burners so as to form a hot flue gas stream,

(c) cooling the hot flue gas stream in at least one heat exchanger by indirect heat exchange against a stream of water so as to form a cooled flue gas stream and a second partial vapor stream which is supplied to the product vapor stream,

(d) separating the cooled flue gas stream into a flue gas waste gas stream and at least one flue gas recirculation stream, the flue gas recirculation stream being recirculated to step (a), and

increasing a mass flow of the recirculated flue gas with decreasing mass flow of the synthesis-gas product gas so as to obtain an at least approximately constant product vapor stream by increasing the second partial vapor stream.

2. The method recited in claim 1 , wherein the flue gas recirculation stream is recirculated using a conveying device with adjustable conveying capacity.

3. The method recited in claim 1 , further comprising adding the flue gas recirculation stream to the combustion air.

4. The method recited in claim 1 , further comprising adding the flue gas recirculation stream to the combustion air at least one of before and after preheating the combustion air.

5. The method recited in claim 2 , wherein the conveying device is a blower.

6. The method recited in claim 1 , further comprising using the product vapor stream at least partly as export steam.

7. A method for producing a synthesis-gas product gas and at least one product vapor stream, the method comprising:

catalytic steam reforming a hydrocarbonaceous feedstock in a steam reformer so as to form the synthesis-gas product gas and the at least one product vapor stream, the steam reformer including a plurality of catalyst-containing reformer tubes and a reformer furnace with burners for firing the reformer tubes;

cooling the hot synthesis-gas product gas stream in at least one heat exchanger by indirect heat exchange against a stream of water so as to form a cooled synthesis-gas product gas stream and a first partial vapor stream; and

supplying the first partial vapor stream to the product vapor stream, wherein the reforming furnace is operated so as to include the following steps:

(a) supplying a burner feedstock including fuel, combustion air and at least one flue gas recirculation stream to the reformer furnace,

(b) burning the burner feedstock in the burners so as to form a hot flue gas stream,

(c) cooling the hot flue gas stream in at least one heat exchanger by indirect heat exchange against a stream of water so as to form a cooled flue gas stream and a second partial vapor stream which is supplied to the product vapor stream,

(d) separating the cooled flue gas stream into a flue gas waste gas stream' and at least one flue gas recirculation stream, the flue gas recirculation stream being recirculated to step (a), and

decreasing a mass flow of the recirculated flue gas with a constant mass flow of the synthesis-gas product gas so as to obtain a decreased product vapor stream by decreasing the second partial vapor stream.

8. The method recited in claim 7 , wherein the flue gas recirculation stream is recirculated using a conveying device with adjustable conveying capacity.

9. The method recited in claim 7 , further comprising adding the flue gas recirculation stream to the combustion air.

10. The method recited in claim 7 , further comprising adding the flue gas recirculation stream to the combustion air at least one of before and after preheating the combustion air.

11. The method recited in claim 8 , wherein the conveying device is a blower.

12. The method recited in claim 7 , further comprising using the product vapor stream at least partly as export steam.

13. A method for producing a synthesis-gas product gas and at least one product vapor stream, the method comprising:

catalytic steam reforming a hydrocarbonaceous feedstock in a steam reformer so as to form the synthesis-gas product gas and the at least one product vapor stream, the steam reformer including a plurality of catalyst-containing reformer tubes and a reformer furnace with burners for firing the reformer tubes;

cooling the hot synthesis-gas product gas stream in at least one heat exchanger by indirect heat exchange against a stream of water so as to form a cooled synthesis-gas product gas stream and a first partial vapor stream; and

supplying the first partial vapor stream to the product vapor stream, wherein the reforming furnace is operated so as to include the following steps:

(a) supplying a burner feedstock including fuel, combustion air and at least one flue gas recirculation stream to the reformer furnace,

(b) burning the burner feedstock in the burners so as to form a hot flue gas stream,

(c) cooling the hot flue gas stream in at least one heat exchanger by indirect heat exchange against a stream of water so as to form a cooled flue gas stream and a second partial vapor stream which is supplied to the product vapor stream,

(d) separating the cooled flue gas stream into a flue gas waste gas stream and at least one flue gas recirculation stream, the flue gas recirculation stream being recirculated to step (a), and

increasing a mass flow of the recirculated flue gas with a constant mass flow of the synthesis-gas product gas so as to obtain an increased product vapor stream by increasing the second partial vapor stream.

14. The method recited in claim 13 , wherein the flue gas recirculation stream is recirculated using a conveying device with adjustable conveying capacity.

15. The method recited in claim 13 , further comprising adding the flue gas recirculation stream to the combustion air.

16. The method recited in claim 13 , further comprising adding the flue gas recirculation stream to the combustion air at least one of before and after preheating the combustion air.

17. The method recited in claim 14 , wherein the conveying device is a blower.

18. The method recited in claim 13 , further comprising using the product vapor stream at least partly as export steam.

19. A plant for carrying out a method of producing a synthesis-gas product gas and at least one product vapor stream, the plant comprising:

a reformer furnace with burners and a plurality of catalyst-containing reformer tubes;

at least one heat exchanger for cooling a hot synthesis-gas product gas stream by indirect heat exchange against a stream of water by forming a cooled hot synthesis-gas product gas stream and a first partial vapor stream;

a measuring device for measuring a mass flow of the synthesis-gas product gas;

at least one heat exchanger for cooling a hot flue gas stream by indirect heat exchange against a stream of water by forming a cooled flue gas stream and a second partial vapor stream;

a measuring device for measuring a mass flow of the recirculated flue gas;

a measuring device for measuring a product vapor mass flow; and

a conveying device with adjustable conveying capacity for recirculating the flue gas recirculation stream to the reformer furnace, the conveyingdevice being configured to at least one of:

increase the mass flow of the recirculated flue gas with decreasing mass flow of the synthesis-gas product gas so as to obtain an at least approximately constant product vapor stream by increasing the second partial vapor stream,

decrease the mass flow of the recirculated flue gas with a constant mass flow of the synthesis-gas product gas so as to obtain a decreased product vapor stream by decreasing the second partial vapor stream, and

increase the mass flow of the recirculated flue gas with a constant mass flow of the synthesis-gas product gas so as to obtain an increased product vapor stream by increasing the second partial vapor stream.

20. The plant according to claim 19 , wherein the conveying device is a blower.