Oxidant control in co-generation installations

An improved combustion process comprising:

• a. providing an engine exhaust derived from combustion of a first fuel, the exhaust gas divided into first and second exhaust gas streams;
• b. feeding the first exhaust gas stream into a boiler having a combustion chamber and feeding the second exhaust gas stream into a heat exchanger;
• c. flowing air into the heat exchanger, and indirectly contacting the air with the second exhaust gas stream, thus forming a heated air stream;
• d. combusting a second fuel with the heated air stream in the combustion chamber to produce hot flue gases useful in heating water in said boiler;
• e. measuring one or more combustion parameters in the combustion chamber to provide combustion measurements;
• f. exchanging heat between the hot flue gases and water in the boiler, producing a boiler flue gas stream;
• and
• g. mixing at least a portion of the boiler flue gas stream with the second exhaust gas stream prior to the second exhaust gas stream entering the heat exchanger.

An improved combustion process comprising:

• a. providing an engine exhaust derived from combustion of a first fuel, the exhaust gas divided into first and second exhaust gas streams;
• b. feeding the first exhaust gas stream into a boiler having a combustion chamber;
• c. flowing air into a first heat exchanger, and indirectly contacting the air with at least a portion of boiler flue gas stream, thus forming a preheated air stream;
• d. exchanging heat between the preheated air stream and the second exhaust gas stream, thereby producing a heated combustion air stream;
• e. combusting a second fuel with the preheated air stream in the combustion chamber to produce hot flue gases useful in heating water in said boiler;
• f. measuring one or more combustion parameters in the combustion chamber to provide combustion measurements;
• g. transmitting the combustion measurements to a controller which compares the combustion measurements to set point values and subsequently controls the operation of control valves associated with flow of the first and second exhaust gas streams;
• and
• h. exchanging heat between the hot flue gases and water in the boiler, thereby producing a boiler flue gas stream.

An improved combustion process comprising:

• a. providing an engine exhaust derived from combustion of a first fuel, the exhaust gas divided into first and second exhaust gas streams;
• b. feeding the first exhaust gas stream into a boiler and feeding the second exhaust gas stream into a burner, the burner also taking in a fuel which is combusted with residual oxygen in the second exhaust gas stream to produce hot flue gases useful in heating water in said boiler;
• c. adding additional oxidant to the second exhaust gas stream prior to try to the burner, the additional oxidant comprising at least 21% oxygen;
• d. measuring one or more combustion parameters in the boiler to provide combustion measurements;
• and
• e. transmitting the combustion measurements to a controller which compares the combustion measurements to set point values and subsequently controls the operation of control valves associated with flow of the first and second exhaust gas streams.

An improved combustion process comprising:

• a. providing an engine exhaust derived from combustion of a first fuel, the exhaust gas divided into first and second exhaust gas streams;
• b. feeding the first exhaust gas stream into a boiler and feeding the second exhaust gas stream into a burner, the burner also taking in a fuel which is combusted with residual oxygen in the second exhaust gas stream to produce hot flue gases useful in heating water in said boiler;
• c. adding an additional oxidant to the burner, the additional oxidant comprising at least 21 volume % oxygen, oxygen in the additional oxidant combusting with a portion of the fuel;
• d. measuring one or more combustion parameters in the furnace to provide combustion measurements;
• and
• e. transmitting the combustion measurements to a controller which compares the combustion measurements to set point values, and subsequently controls the operation of control valves associated with flow of the first and second exhaust gas streams, and the operation of a control valve associated with the flow of the additional oxidant.