Staged prevaporizer-premixer

A method of prevaporizing and premixing fuel and air prior to combustion in a combustor, the method comprising:

• providing an inlet flow of air into a first stage chamber of an annular chamber having an inlet and outlet defining a second stage chamber coannular and continuous to the first stage chamber;
• introducing a fuel into the fist stage chamber of an annular chamber;
• atomizing the fuel into the first stage chamber;
• mixing the inlet flow of air and fuel at a first stage temperature for a first stage residence time;
• wherein the resulting fuel and air mixture is moved by the inlet flow of the air into the second stage chamber;
• introducing secondary air into the second chamber at a second temperature, which is higher than the first temperature;
• mixing the atomized fuel and air mixture that has flowed from the first chamber with the hotter secondary air in the second stage chamber for a second residence time, which is shorter than that of the first residence time, until the resulting mixture is at a desired prevaporized and premixed level for combustion;
• and
• directing the resulting premixed and prevaporized fuel and air mixture out the outlet of the annular chamber to the combustor;
• wherein the hotter secondary air is introduced by a plurality of high velocity jets;
• and
• wherein the hotter secondary air flows in a reverse direction of the fuel and air mixture from the first chamber.

A method of prevaporizing and premixing fuel and air prior to combustion in a combustor, the method comprising:

• providing an inlet flow of air into a first stage chamber of an annular chamber having an inlet and outlet defining a second stage chamber coannular and contiguous to the first stage chamber;
• introducing a fuel into the first stage chamber of an annular chamber;
• atomizing the fuel into the first stage chamber;
• mixing the inlet flow of air and fuel at a first stage temperature for a first stage residence time;
• wherein the resulting fuel and air mixture is moved by the inlet flow of the air into the second stage chamber;
• introducing secondary air into the second chamber at a second temperature, which is higher than the first temperature;
• mixing the atomized fuel and air mixture that has flowed from the first chamber with the hotter secondary air in the second stage chamber for a second residence time, which is shorter than that of the first residence time, until the resulting mixture is at a desired prevaporized and premixed level for combustion;
• and
• directing the resulting premixed and prevaporized fuel and air mixture out the outlet of the annular chamber to the combustor;
• wherein the fuel is comprised of a liquid fuel, and
• wherein the hotter secondary air is introduced by a plurality of high velocity jets, and
• wherein the hotter secondary air flows in a reverse direction of the fuel and air mixture from the first chamber.

A staged prevaporizer-premixer (SPP) for prevaporizing and premixing liquid fuel and air prior to combustion in a combustor, the SPP comprising:

• an annular chamber having an inlet end and an outlet end, wherein said annular chamber defines a first stage chamber and a contiguous and coannular second stage chamber;
• a liquid fuel inlet and a liquid fuel atomizer assembly positioned at the inlet of the annular chamber for finely atomizing liquid fuel introduced from the liquid fuel inlet in the first chamber of the annular chamber;
• an air inlet supply that introduces air into the first chamber for directing the atomized liquid fuel in a desired direction within the annular chamber at a first stage temperature for a first stage residence time;
• a secondary air inlet into the secondary chamber, wherein the secondary air is introduced through the secondary inlet providing further prevaporization and premixing of the partially prevaporized and premixed liquid fuel and air mixture from the first stage chamber at a second stage temperature, which is hotter than that of the first stage temperature, and at a second stage residence time, which is less than the first stage residence time, in order to substantially completely prevaporize and premix the fuel and air mixture prior to combustion;
• and
• an outlet nozzle to channel the substantially completely prevaporized and premixed fuel and air mixture from the second stage chamber to the adjacent combustor.