Fuel feed system for a gasifier and method of gasification system start-up

1. A method of start-up for a gasification system including a gasifier, said method comprising:

establishing a flow of a start-up fuel external to the gasifier prior to ignition of the gasifier, including circulating a particulate fuel within a flow circuit of the gasification system;

establishing a start-up liquid feed external to the gasifier during gasifier start-up;

channeling the start-up liquid feed and the start-up fuel to the gasifier during gasifier start-up; and

replacing a quantity of a first carrier gas used in conveying the particulate fuel to the gasifier with an alternate carrier gas.

2. A method of start-up for a gasification system in accordance with claim 1 , wherein establishing a flow of a start-up fuel further comprises one of circulating a pneumatically-conveyed particulate fuel within a flow circuit of the gasification system and stabilizing a flow of natural gas within the gasification system.

3. A method of start-up for a gasification system including a gasifier, said method comprising:

establishing a flow of a start-up fuel external to the gasifier prior to ignition of the gasifier, including stabilizing a flow of natural gas within the gasification system;

establishing a start-up liquid feed external to the gasifier during gasifier start-up;

channeling the start-up liquid feed and the start-up fuel to the gasifier during gasifier start-up;

adding a quantity of particulate fuel into the natural gas; and

replacing a quantity of natural gas used in conveying the particulate fuel to the gasifier with an alternate carrier gas.

4. A method of start-up for a gasification system in accordance with claim 1 , wherein replacing the quantity of the first carrier gas with the alternate carrier gas comprises replacing the quantity of the first carrier gas with CO2 recovered from the gasifier.

5. A method of start-up for a gasification system in accordance with claim 3 , wherein replacing the quantity of natural gas with the alternate carrier gas comprises replacing the quantity of natural gas with CO2 recovered from the gasifier.

6. A method of start-up for a gasification system including a gasifier, said method comprising:

establishing a flow of a start-up fuel external to the gasifier prior to ignition of the gasifier, including supplying a start-up carrier gas to a flow circuit of the gasification system and channeling a particulate fuel from a storage bin into the start-up carrier gas to form the flow of start-up fuel;

establishing a start-up liquid feed external to the gasifier during gasifier start-up; and

channeling the start-up liquid feed and the start-up fuel to the gasifier during gasifier start-up.

7. A method of start-up for a gasification system in accordance with claim 6 , wherein establishing a flow of a start-up fuel further comprises:

channeling the flow of start-up fuel to at least one separation device, wherein the at least one separation device substantially separates the particulate fuel from the start-up carrier gas; and

returning the separated particulate fuel to the storage bin.

8. A method of start-up for a gasification system in accordance with claim 7 , wherein channeling the flow of start-up fuel to at least one separation device further comprises channeling the flow of start-up fuel to at least one of a cyclone and a stripper.

9. A method of start-up for a gasification system in accordance with claim 7 , wherein supplying a start-up carrier gas further comprises supplying the start-up carrier gas from a supply source, and wherein establishing a flow of a start-up fuel further comprises returning at least a portion of the separated start-up carrier gas to the supply source.

10. A method of start-up for a gasification system in accordance with claim 6 , wherein channeling a particulate fuel from a storage bin into the start-up carrier gas further comprises transporting the particulate fuel through at least one solids pump.

11. A method of start-up for a gasification system in accordance with claim 10 , wherein channeling a particulate fuel from a storage bin into the start-up carrier gas further comprises directing a first stream of gas into a discharge conduit of the at least one solids pump, wherein the first stream is a sealing flow configured to traverse back through the at least one solids pump.

12. A method of start-up for a gasification system in accordance with claim 10 , wherein channeling a particulate fuel from a storage bin into the start-up carrier gas further comprises at least one of (i) directing a second stream of gas into a discharge conduit of the at least one solids pump, wherein the second stream is a jet configured to break up agglomerations of the particulate fuel, and (ii) mechanically delumping the particulate fuel within the discharge conduit.

13. A method of start-up for a gasification system including a gasifier, said method comprising:

establishing a flow of a start-up fuel external to the gasifier prior to ignition of the gasifier;

establishing a start-up liquid feed external to the gasifier during gasifier start-up, including forming the start-up liquid feed from a fresh water makeup;

channeling the start-up liquid feed and the start-up fuel to the gasifier during gasifier start-up; and

replacing the start-up liquid feed channeled to the gasifier with a post-start-up slurry comprising at least one of unconverted carbon recovered from the gasifier and a slag additive.

14. A method of start-up for a gasification system in accordance with claim 1 , wherein the channeling of the start-up fuel to the gasifier and the channeling of the start-up liquid feed to the gasifier are initiated substantially concurrently.

15. A method of start-up for a gasification system in accordance with claim 1 , wherein establishing the flow of the start-up fuel further comprises stabilizing a flow of natural gas within the gasification system, and wherein the channeling of the start-up fuel to the gasifier is initiated prior to the channeling of the start-up liquid feed to the gasifier.