A complete combustion is a process burning all the carbon (C) to (CO2), all the hydrogen (H) to (H2O) and all the sulphur (S) to (SO2), which is possible only if there is sufficient oxygen available for converting (C) to (CO2), hydrogen (H) to (H2O) and sulphur (S) to (SO2). Theory of combustion suggests that 2.67 gm oxygen is required for 1 gm carbon combustion, which implies 2.67C gm oxygen is required for C gm carbon, 1 gm oxygen is required for 1 gm sulfur combustion, which implies S gm oxygen is required for S gm sulfur and 8 gm oxygen is required for 1 gm hydrogen combustion, which implies 8H gm oxygen is required for H gm hydrogen. In the combustion process the hydrogen content of the fuel is converted to H2O‚ which normally leaves the stack as water vapor‚ carrying with it the heat required to convert it from liquid to vapor. With fuels high in hydrogen‚ such as natural gas‚ this is a significant loss‚ upwards of 10 % of the energy in the fuel‚ depending on flue gas temperature.
This is time to arrest this loss by splitting these water vapors back to Hydrogen & Oxygen with alumina rich fuel firing.
The excess air ratio is not dictated by need for complete combustion, but more by the temperature which the turbine can withstand. So much of the air will mix in after the combustion to cool the mix to temperature suitable for the metallurgy. In fact a substantial part of the energy from the turbine is used to convey the air.
Complete Coal/NG combustion can save 10-15% fuel. We all know that in the combustion process the hydrogen content of the fuel is converted to H2O‚ which normally leaves the stack as water vapor‚ carrying with it the heat required to convert it from liquid to vapor with fuels high in hydrogen like NG ‚ this is a significant loss some time > 10 % of the energy in the fuel‚ depending on flue gas temperature. Now with an innovative idea these water vapors can be converted back to fuel Hydrogen & Oxygen which invites complete fuel combustion.
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