Method for operating a boiler using oxygen-enriched oxidants

A method of operating a steam-generating boiler including a radiation zone and a convection zone comprising:

• introducing fuel into a combustion space within the boiler;
• introducing oxygen-enriched air into the combustion space,
• wherein the oxygen-enriched air contains about 21% to about 100% by volume oxygen;
• combusting the fuel and oxygen-enriched air to generate thermal energy in the combustion space;
• and
• collecting at least a portion of flue gases and recirculating at least a portion of the flue gases through the boiler,
• wherein introducing oxygen-enriched air comprises injecting oxygen-enriched air into the radiation zone and into the convection zone and wherein recirculating the flue gas comprises introducing the recirculated flue gas into the radiation zone and into the convection zone.

A method of operating a steam-generating boiler including a radiation zone and a convection zone comprising:

• introducing fuel into a combustion space within the boiler;
• introducing oxygen-enriched air into the combustion space,
• wherein the oxygen-enriched air contains about 21% to about 100% by volume oxygen;
• combusting the fuel and oxygen-enriched air to generate thermal energy in the combustion space;
• and
• collecting at least a portion of flue gases and recirculating at least a portion of the flue gases into the radiation zone and the convection zone,
• such that the relationship RC = 1 - FS ⁢ ⁢ Θ o Θ bc
• is maintained, where RC is a flow rate ratio of oxygen-enriched air to recirculated flue gas, FS is the ratio of fuel consumption between oxygen-enriched air combustion and air combustion, and Θbc represents the flow rate ratio between fuel and air, and fuel, for air combustion and Θo represents the flow rate ratio between fuel and oxygen-enriched air and fuel for oxygen-enriched combustion.

A method of operating a steam-generating boiler including a radiation zone and a convection zone comprising:

• introducing fuel into a combustion space within the boiler;
• introducing oxygen-enriched air into the combustion space injecting oxygen-enriched air into the radiation zone and into the convection zone,
• wherein the oxygen-enriched air contains about 21% to about 100% by volume oxygen;
• combusting the fuel and oxygen-enriched air to generate thermal energy in the combustion space;
• and
• collecting at least a portion of flue gases and recirculating at least a portion of the flue gases through the boiler,
• wherein recirculating the flue gas comprises introducing the recirculated flue gas into the radiation zone and into the convection zone.

A method of operating a steam-generating boiler including a convection zone and a radiation zone, wherein the steam-generating boiler is designed for air combustion using air combustion design tolerances, the method comprising:

• introducing fuel into a combustion space within the boiler;
• introducing oxygen-enriched air into the combustion space,
• wherein the oxygen-enriched air contains about 21% to about 100% by volume oxygen,
• combusting the fuel and oxygen-enriched air to generate thermal energy in the combustion space;
• and
• collecting at least a portion of flue gases and recirculating at least a portion of the flue gases to the convection zone and the radiation zone,
• wherein the recirculated flue gases are introduced at a flow rate that does not exceed air combustion design tolerances of the steam-generating boiler.

A method of operating a steam-generating boiler including a radiation zone and a convection zone comprising:

• introducing a low calorie fuel into a combustion space within the boiler;
• introducing about 0 to about 100% by volume of oxygen-enriched air through a low-calorific fuel oxygen burner located in a lower region of the radiation zone, about 0 to about 30% by volume through an inlet located intermediate to the lowest point of the radiation zone and the interface of the radiation zone and the convection zone, and about 0 to about 20% by volume of oxygen-enriched air through an inlet located in an upper region of the convection zone, and combinations thereof,
• wherein the total volume of oxygen-enriched air from all inlets equals 100%, and
• wherein the oxygen-enriched air contains about 21% to about 100% by volume oxygen;
• combusting the fuel and oxygen-enriched air to generate thermal energy in the combustion space;
• and
• collecting at least a portion of flue gases and recirculating at least a portion of the flue gases into the convection zone and radiation zone.