Non-equilibrium plasma-assisted method and system for reformulating and/or reducing tar concentration in gasification derived gas product
A method and apparatus is described for reformulating raw gas and/or reducing and/or converting the tar in a raw gas from a gasification reaction. More specifically, a gas reformulating system having a gas reformulating chamber, one or more sources of or means for generating non-equilibrium plasma, and optionally one or more oxygen source(s) inputs and control system is provided. Methods of reformulation and/or reducing the tar concentration in a raw gas from a gasification reaction that uses non-equilibrium plasma are also provided.
1. A method for reformulating a raw gas from a gasification reaction comprising the steps of:
a. removing particulates from the raw gas to obtain a particulate-free raw gas;
b. delivering the particulate-free raw gas to a mixing chamber;
c. injecting air pre-heated to a temperature of between 300-400° C. into the mixing chamber to obtain a mixture;
d. maintaining the mixture in the mixing chamber for a residence time sufficient to raise the temperature of the mixture to about 650-950° C. by partial thermal oxidation to obtain a pre-heated mixture;
e. contacting the pre-heated mixture with an electrical discharge such that a non-equilibrium plasma is formed, thereby producing a reformulated gas; and
f. removing the reformulated gas from the chamber.
2. The method of claim 1 , wherein the non-equilibrium plasma is formed by at least one of dielectric barrier discharge, gliding arc, direct-current and pulsed coronas, corona discharge, microwave plasma, electron-beam, micro-discharge and Radio Frequency (RF)-driven discharge.
3. The method of claim 1 comprising an addition of one or more process additives.
4. The method of claim 1 , wherein one or more process additives are added concurrently with formation of the non-equilibrium plasma within the mixture.
5. The method of claim 1 , comprising exposing one or more of the particulate-free raw gas, the mixture, or the reformulated gas to a catalyst.
6. The method of claim 1 further comprising adjusting an air to the particulate-free raw gas ratio to obtain the mixture.
7. The method of claim 6 comprising adjusting the air to the particulate-free raw gas ratio to between about 0.2 to about 0.6.
8. The method of claim 6 comprising adjusting the air to the particulate-free raw gas ratio to between about 0.3 to about 0.5.
9. The method of claim 6 , wherein air to the particulate-free raw gas ratio is adjusted based on reformulated gas quality.
10. The method of claim 6 , wherein air to the particulate-free raw gas ratio is adjusted to maintain a lower heating value (LHV) of the reformulated gas within a specific range.
11. The method of claim 10 , wherein the specific range is between 1.2 MJ/Nm 3 and 3.9 MJ/Nm 3 .
12. The method of claim 10 , wherein the specific range is between 3.4 MJ/Nm 3 and 3.7 MJ/Nm 3 .
13. The method of claim 10 , wherein the specific range is between 1.2 MJ/Nm 3 and 3.9 MJ/Nm 3 .
14. The method of claim 10 , wherein the LHV is about 3 MJ/Nm 3 .
15. A method for reformulating a raw gas from a gasification reaction comprising the steps of:
a. mixing the raw gas with air pre-heated to a temperature of between 300-400° C. to obtain a mixture;
b. maintaining the mixture in a mixing chamber for a residence time sufficient to raise the temperature of the mixture to about 650-950° C. by partial thermal oxidation to obtain a pre-heated mixture; and
c. directly contacting the pre-heated mixture with a gliding arc discharge, thereby producing a reformulated gas.