An integrated fuel combustion system with gas separation (adsorptive, absorptive, membrane or other suitable gas separation) separates a portion of carbon dioxide from a combustion gas mixture and provides for recycle of separated carbon dioxide to the intake of a fuel combustor for combustion. A process for carbon dioxide separation and recycle includes: admitting combustion gas to an adsorptive gas separation system contactor containing adsorbent material; adsorbing a portion of carbon dioxide; recovering a first product stream depleted in carbon dioxide for release or use; desorbing carbon dioxide from the adsorbent material and recovering a desorbed second product stream enriched in carbon dioxide for sequestration or use; admitting a conditioning and/or desorption fluid into the contactor and desorbing a second portion of carbon dioxide to recover a carbon dioxide enriched conditioning stream; and recycling a portion of the carbon dioxide enriched conditioning stream to an inlet of fuel combustor to pass through the fuel combustor for combustion.

A burner and methods of using the burner. The burner utilizes bypass conduits to separate the combustion air that is passed to the primary combustion zone into two or more portions. The two portions are injected into the primary combustion zone at different points so as to reduce the flame temperature. A NOx reducing medium may be mixed with the combustion air in the bypass conduit. The NOx reducing medium may be flue gases from a combustion chamber having the primary combustion zone.

A radiant tube recuperative burner assembly having a heat exchanger (13) and a burner (11); said heat exchanger (13) comprises: a first inner tube (15); a second heat exchanger tube (16) coaxial and external to the first tube (15); a third tube (24) coaxial and external to said second tube (16); a fourth tube (35) positioned perpendicular to said first tube (15); a fifth tube (36) coaxial and internal to said fourth tube (35); a flue gas outlet passage (27) positioned inside said fifth tube (36); a first gap (17) between said first tube (15) and said second tube (16); a second gap (25) between said third tube (24) and said second tube (16); a sixth gap (40) between said fourth tube (35) and said fifth tube (36); said first gap (17) communicates with said sixth gap (40); said second gap (25) communicates with said flue gas outlet passage (27); a Venturi tube (41, 52) positioned transverse to said fifth tube (36); the inlet of the Venturi tube (41, 52) communicates with said sixth gap (40); said Venturi tube (41, 52) has an outlet that is in communication with said flue gas outlet passage (27); and with a connection pipe (42) between said heat exchanger (13) and said burner (11).

A burner sub-system, a furnace comprising the same, a fuel combustion process and steam cracking process carried out in the furnace. The burner sub-system comprises a barrier wall segment between the burner tip and the flue-gas recirculation (“FGR”) duct, effectively blocking direct gas flow between the burner tip and the FGR duct opening, but without encircling the whole burner tip. The presence of the partial barrier wall has the advantage of preventing the temperature inside the FGR duct from becoming too high, while achieving low NOx emissions from the combustion process without overheating the burner tip because of reduced amount of heat reflection to the burner tip compared to an annular barrier wall. The invention is particularly useful in furnaces where hydrogen-rich fuel gas is combusted.

A modular boiler system for implementing fuel combustion is provided. The system includes a first boiler and a second boiler of a plurality of boilers, an oxygen input unit, a fuel input unit, a recycled flue gas input unit, and a flue gas separator. The first boiler receives oxygen from the oxygen input unit, fuel from the fuel input unit, and recycled flue gas from the recycled flue gas input unit. The first boiler outputs intra-system flue gas. The flue gas separator separates the intra-system flue gas into a first and second flue gas stream, transfers the first flue gas stream to the second boiler, and transfers the second flue gas stream to a gas cleaning system. The second boiler receives oxygen from the oxygen input unit, fuel from the fuel input unit, and the first flue gas stream from the flue gas separator.

In a method for reducing the NOx emissions of a rotary kiln of a clinker production plant, fuel supplied through a burner of the rotary kiln is burned along with primary air fed through the burner, wherein the primary air has a lower oxygen content and the primary air has an oxygen content reduced relative to that of the ambient air and a temperature increased relative to that of the ambient air, and the primary air is obtained by mixing ambient air with exhaust gas from the rotary kiln or from a heat exchanger connected to the rotary kiln and used for preheating raw meal. The primary air is further obtained by mixing with hot air, in particular waste air from a clinker cooler.

A gasification reactor is provided. The reactor comprises a first gasification area, a second gasification area and a shared combustion area. The shared combustion area is set between the first and second gasification areas. Therein, the (present invention applies interconnected fluidized beds in gasification. The connecting piping between the first and second gasification areas are separately replaced with dense beds to be integrated for forming a single reactor. Thus, the present invention simplifies the system, saves the cost and reduces the operation difficulty.

A method for reducing harmful gas emissions from a gas-fired boiler including a sealed forced-draught combustion chamber in which there is a burner to which there leads a first conduit for drawing in combustion air and from which there departs a second conduit for the discharge of combustion flue gases. Provision is made for drawing off a portion of the flue gases or exhaust gases from the second conduit and injecting it into the combustion air to reduce the percentage of atmospheric oxygen present in that combustion air and consequently reduce the production of harmful gases in the combustion flue gases. A boiler operating according to the aforesaid method is also disclosed.

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.

A gasification reactor is provided. The reactor comprises a first gasification area, a second gasification area and a shared combustion area. The shared combustion area is set between the first and second gasification areas. Therein, the (present invention applies interconnected fluidized beds in gasification. The connecting piping between the first and second gasification areas are separately replaced with dense beds to be integrated for forming a single reactor. Thus, the present invention simplifies the system, saves the cost and reduces the operation difficulty.