Boiler systems and associated control systems, methods for operating same, are described herein. In one example embodiment, a boiler system includes a furnace, an exhaust passage, an air passage, a FGR passage, a flue gas valve that is adjustable by way of a first actuator, a NO.sub.X gas sensor, an oxygen gas sensor, and an additional valve that is adjustable by way of a second actuator. Further, the boiler system includes at least one processing device coupled to the NO.sub.X gas sensor, the oxygen gas sensor, the first actuator and the second actuator. The at least one processing device is configured to generate control signals that are provided to the first actuator and second actuator, and also configured to generate correction factors by way of a calibration process and to utilize one or more of the correction factors in determining one or more of the control signals.

An oil boiler includes an outer container having openings at opposite ends, a combustion chamber that covers an opening at an upper end of the outer container and in which a combustion reaction occurs, a lower cover that covers an opening at a lower end of the outer container, a plurality of flue tubes to heat heating water flowing in the outer container by guiding combustion gas, a burner including a fuel nozzle that sprays fuel, an air nozzle that injects air, and a spark plug that ignites a mixture of the fuel and the air, and a flame tube part that defines a tube space by surrounding a partial space in which the mixture is ignited, the flame tube part including a flame tube having an open lower end and a recirculation hole formed through the flame tube such that the combustion gas is introduced into the flame tube.

A method heats a furnace process chamber with the combustion of fuel gas. The method heats the process chamber in a preheat mode when the temperature of the process chamber is below the autoignition temperature of the fuel gas. The preheat mode forms preheated combustion air by directing the combustion air through a regenerative bed. A stream of the preheated combustion air is directed into the process chamber in a condition unmixed with fuel gas. The preheat mode also forms a fuel rich mixture of the fuel gas and unheated combustion air. The fuel rich mixture is directed into the process chamber adjacent to the stream of preheated combustion air.

A method heats a furnace process chamber with the combustion of fuel gas. The method heats the process chamber in a preheat mode when the temperature of the process chamber is below the autoignition temperature of the fuel gas. The preheat mode forms preheated combustion air by directing the combustion air through a regenerative bed. A stream of the preheated combustion air is directed into the process chamber in a condition unmixed with fuel gas. The preheat mode also forms a fuel rich mixture of the fuel gas and unheated combustion air. The fuel rich mixture is directed into the process chamber adjacent to the stream of preheated combustion air.

The invention provides a combustion apparatus and a combustion method capable of ashing matter to be combusted inside a combustion chamber efficiently without providing a device such as an unburned combustibles measurement device and without varying the direction of injection of air into the combustion chamber. The powder fuel combustion apparatus 1 includes a fuel supply device 10, a primary combustion chamber 20, a secondary combustion chamber 50, an air supply/ash discharge device 32, and a cyclone dust collector 60. An inclined portion 23a is formed at a bottom portion 23 of the primary combustion chamber 20, and the inclined portion 23a includes bottom portion air supply ports 31 and an air supply/ash discharge device 32. The air supply/ash discharge device 32 includes a bottom portion air injection nozzle 34 and an ash delivery device 35. The bottom portion air injection nozzle 34 has upper and lower ends opened, and a plurality of injection ports 34a through which air is injected are formed on a side surface. During combustion of the powder fuel F, air having a strong wind pressure is injected through the bottom portion air injection nozzle 34 either regularly or irregularly to agitate the powder fuel F and achieve a good combustion state.

Processes and apparatuses for heating process fluid in a furnace. Fuel to the furnace is either hydrocarbons or hydrogen. The fuels may be sent to different furnaces or be sent at different times to the same furnace. Furnaces that are configured to receive both types of fuels may have different exhaust paths. An exhaust path for hydrocarbon fuel flue gas includes a carbon capture process zone.

Processes and apparatuses for heating process fluid in a furnace. Fuel to the furnace is either hydrocarbons or hydrogen. The fuels may be sent to different furnaces or be sent at different times to the same furnace. Furnaces that are configured to receive both types of fuels may have different exhaust paths. An exhaust path for hydrocarbon fuel flue gas includes a carbon capture process zone.

A method heats a furnace process chamber with the combustion of fuel gas. The method heats the process chamber in a preheat mode when the temperature of the process chamber is below the autoignition temperature of the fuel gas. The preheat mode forms preheated combustion air by directing the combustion air through a regenerative bed. A stream of the preheated combustion air is directed into the process chamber in a condition unmixed with fuel gas. The preheat mode also forms a fuel rich mixture of the fuel gas and unheated combustion air. The fuel rich mixture is directed into the process chamber adjacent to the stream of preheated combustion air.

Processes and apparatuses for heating process fluid in a furnace. Fuel to the furnace is either hydrocarbons or hydrogen. The fuels may be sent to different furnaces or be sent at different times to the same furnace. Furnaces that are configured to receive both types of fuels may have different exhaust paths. An exhaust path for hydrocarbon fuel flue gas includes a carbon capture process zone.

A supercritical CO.sub.2 boiler capable of realizing uniform combustion, corrosion resistance and coking resistance, and a boiler system are provided. The supercritical CO.sub.2 boiler includes a main combustion chamber, an upper furnace, a furnace arch and a flue, wherein a cross section of the main combustion chamber is circular or oval, or is of an N-sided shape, where N>4; at least four burner groups are disposed on the main combustion chamber, each group of burner nozzles corresponding to each burner group includes a recirculating air nozzle, a primary air nozzle and a secondary air nozzle; lateral recirculating air nozzles symmetrically distributed are respectively disposed at two sides of the primary air nozzle, the recirculating air nozzle and the lateral recirculating air nozzle are configured to feed recirculating flue gas or a mixed gas of the recirculating flue gas and secondary air into the main combustion chamber.