Methods and apparatus for diluent nitrogen saturation
View Patent ↗In one aspect, an embodiment of the present disclosure provides an Integrated Gasification Combined Cycle (IGCC) apparatus. The apparatus includes a saturator configured to saturate NPG with water vapor, and a heat recovery steam generator (HRSG), a low pressure steam loop through the saturator, wherein the HRSG is configured to heat the low pressure steam loop. The apparatus further includes a compressor and a heat exchanger configured to heat the NPG using waste process heat and extraction air from the compressor, wherein the heated NPG thereby becomes diluent nitrogen.
1. A method for introducing diluent into a syngas stream in an integrated gasification combined cycle (IGCC) plant having a combustor and a compressor, said method comprising:
producing nitrogen process gas (NPG) and water vapor;
saturating the NPG with the water vapor, such that the water vapor heats the saturated NPG to a first temperature;
extracting air from the compressor;
routing the extracted air from the compressor through at least two heat exchangers;
increasing the temperature of the saturated NPG to a second temperature through the at least two heat exchangers using heat from the extracted air and a source of waste process heat; and
supplying the saturated NPG at the second temperature along with essentially dry syngas to the combustor.
2. A method in accordance with claim 1 wherein said supplying the essentially dry syngas further comprises supplying essentially dry syngas at a constant moisture level.
3. A method in accordance with claim 2 further comprising operating the combustor at a substantially constant firing temperature.
4. A method in accordance with claim 1 wherein said supplying the essentially dry syngas further comprises supplying syngas having a constant heating value.
5. A method in accordance with claim 4 further comprising operating the combustor at a substantially constant firing temperature.
6. A method in accordance with claim 1 further comprising using a heat recovery steam generator to heat the water vapor supplied for use in said saturating the NPG.
7. A method in accordance with claim 1 further comprising:
routing the extracted air from the at least two heat exchangers through a third heat exchanger: and
increasing a temperature of condensate from a steam turbine at the third heat exchanger using heat from the extracted air.
8. A method in accordance with claim 7 further comprising routing the extracted air from the third heat exchanger to an air separator used for said producing NPG.
9. A method in accordance with claim 7 further comprising routing the heated steam turbine condensate from the third heat exchanger to a heat recovery steam generator.
10. A method for using nitrogen saturation and heating to facilitate increasing the efficiency of an integrated gasification combined cycle (IGCC) plant having a combustor and a compressor, said method including:
producing nitrogen process gas (NPG) and water vapor;
saturating the NPG with the water vapor;
extracting air from the compressor;
routing the extracted air from the compressor through at least two heat exchangers;
routing a source of waste process heat to at least one of the at least two heat exchangers, wherein the at least two heat exchangers are used to increase a temperature of the saturated NPG; and
routing the extracted air from the at least two heat exchangers through a third heat exchanger, wherein the third heat exchanger is used to increase a temperature of condensate from a steam turbine; and
supplying essentially dry syngas to a combustor along with the saturated and heated NPG.
11. A method in accordance with claim 10 wherein supplying the essentially dry syngas further comprises supplying syngas that has a constant moisture level.
12. A method in accordance with claim 11 further comprising operating the combustor at a substantially constant firing temperature.
13. A method in accordance with claim 10 wherein supplying the essentially dry syngas further comprises supplying essentially dry syngas that has a constant heating value.
14. A method in accordance with claim 13 further comprising operating the combustor at a substantially constant firing temperature.
15. A method in accordance with claim 10 further comprising using a heat recovery steam generator to heat the water vapor supplied for use in said saturating the NPG.