Method for combusting fuel in a fired heater

A method for combusting fuel in a fired heater having one or more burners, the method comprising:

• (a) combusting at least a portion of said fuel in the presence of an oxidizer in said burners producing a flue gas;
• and
• (b) recycling at least a portion of said flue gas to said burners;
• wherein step (a) and step (b) are conducted in a manner such that combusting takes place in a combustion regime represented by
• 13 4 , 500 ≥ 7554.8 - 933.72 ⁢ x + 64.960 ⁢ x 2 + .47705 ⁢ y - .55680 ⁢ z - 1579.2 w ≥ 2 , 500 ;
• wherein w represents a mole fraction of oxygen in the oxidizer, wherein 0.900≦w≦0.995;
• wherein x represents a recycle ratio in moles flue gas/mole of oxidizer, wherein 1.0≦x≦8.0;
• wherein y represents a temperature, in Fahrenheit, of the flue gas recycled to said burners wherein 300° F.≦y≦1,200° F.;
• and
• wherein z represents a heating value in Btu/scf LHV of said fuel wherein 100 Btu/scf≦z≦2,200 Btu/scf.

A method for operating a fired heater having a radiant section, the method comprising:

• (a) combusting a fuel in the presence of substantially pure oxygen in one or more burners of said fired heater producing a flue gas;
• and
• (b) recycling at least a portion of said flue gas to one or more burners;
• wherein the radiant section operates at a pressure greater than ambient pressure.

A method for monitoring and controlling the combustion of fuel in a fired heater comprising a fuel feed stream, an oxygen feed stream and a recycle feed stream, the method comprising the steps of:

• (a) monitoring said fuel, producing fuel composition data;
• (b) feeding at least a portion of said fuel to said fired heater;
• (c) combusting said fuel in the presence of substantially pure oxygen in one or more burners of said fired heater producing a flue gas having a temperature y, as measured in Fahrenheit;
• and
• (d) recycling at least a portion of said flue gas at a recycling ratio x, as measured in moles of flue gas/mole of oxygen, to the fired heater;
• wherein said fuel, substantially pure oxygen, and flue gas are fed into said fired heater in at least stoichiometric amounts wherein combusting takes place in a combustion regime represented by
• 15 4 , 500 ≥ 7554.8 - 933.72 ⁢ x + 64.960 ⁢ x 2 + .47705 ⁢ y - .55680 ⁢ z - 1579.2 w ≥ 2 , 500.