A rich-lean combustion apparatus includes a first plate and a second plate provided to face each other to allow a rich mixture to flow therebetween through a rich mixture passage, a third plate provided to allow a lean mixture to flow through a lean mixture passage formed between the second plate and the third plate, a first burner port member for combusting the rich mixture, and a second burner port member for combusting the lean mixture, wherein, between the first plate and the second plate, a mixture inlet into which some of air supplied from a ventilator and a fuel gas injected from a nozzle are introduced, a mixture passage introduction portion and a mixture passage diffuser for allowing the rich mixture flowed into through the mixture inlet to flow to the rich mixture passage, an air inlet into which the remaining of the air supplied from the ventilator is introduced, and an air passage introduction portion through which the air flowed into through the air inlet flows are formed, and wherein a plurality of air through-holes are formed to pass through the second plate to allow the air of the air passage introduction portion to be spouted into an air passage formed between the second plate and the third plate, and a plurality of distribution holes are formed to pass through the second plate to allow some of a mixture passing the mixture passage diffuser to be spouted into the lean mixture passage.

A rich-lean combustion apparatus includes a first plate and a second plate provided to face each other to allow a rich mixture to flow therebetween through a rich mixture passage, a third plate provided to allow a lean mixture to flow through a lean mixture passage formed between the second plate and the third plate, a first burner port member for combusting the rich mixture, and a second burner port member for combusting the lean mixture, wherein, between the first plate and the second plate, a mixture inlet into which some of air supplied from a ventilator and a fuel gas injected from a nozzle are introduced, a mixture passage introduction portion and a mixture passage diffuser for allowing the rich mixture flowed into through the mixture inlet to flow to the rich mixture passage, an air inlet into which the remaining of the air supplied from the ventilator is introduced, and an air passage introduction portion through which the air flowed into through the air inlet flows are formed, and wherein a plurality of air through-holes are formed to pass through the second plate to allow the air of the air passage introduction portion to be spouted into an air passage formed between the second plate and the third plate, and a plurality of distribution holes are formed to pass through the second plate to allow some of a mixture passing the mixture passage diffuser to be spouted into the lean mixture passage.

A fuel injection nozzle (31) of the present invention comprises a pre-mixing passage (34) which mixes fuel (103) and air (102) to generate an air-fuel mixture; and an injection port (33) which is located downstream of the pre-mixing passage (34) and injects the air-fuel mixture into a combustion chamber (26). The fuel injection port (33) has a slit shape and a width that is less than a dimension that is twice as large as a quenching distance.

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 fuel-fired furnace incorporates specially designed fuel/air mixing and combustion structures. The fuel/air mixing structure is of a mixing sound-attenuating design and comprises a venturi having a perforated sidewall portion and being surrounded by a noise-damping housing chamber communicating with the interior of the venturi via its sidewall perforations. During use of the mixing structure, air is flowed through the venturi in a swirling pattern while fuel is transversely injected internally against the swirling air. The combustion structure comprises a burner box housing into which the fuel/air mixture is flowed, combusted, and then discharged as hot combustion gas into and through the heat exchanger tubes. The fuel/air mixture entering the burner box housing initially passes through a non-uniformly perforated diffuser plate functioning to substantially alter in a predetermined manner the relative combustion gas flow rates through the heat exchanger tubes.

A fuel-fired furnace incorporates specially designed fuel/air mixing and combustion structures. The fuel/air mixing structure is of a mixing sound-attenuating design and comprises a venturi having a perforated sidewall portion and being surrounded by a noise-damping housing chamber communicating with the interior of the venturi via its sidewall perforations. During use of the mixing structure, air is flowed through the venturi in a swirling pattern while fuel is transversely injected internally against the swirling air. The combustion structure comprises a burner box housing into which the fuel/air mixture is flowed, combusted, and then discharged as hot combustion gas into and through the heat exchanger tubes. The fuel/air mixture entering the burner box housing initially passes through a non-uniformly perforated diffuser plate functioning to substantially alter in a predetermined manner the relative combustion gas flow rates through the heat exchanger tubes.

A venturi nozzle for a gas combustor includes an orificed gas nozzle, a venturi tube and one or more support members. The orificed gas nozzle has a longitudinal axis, an inlet and an outlet. The venturi tube is aligned with the longitudinal axis and has an entrance proximate to the outlet of the orificed gas nozzle and an exit. The support member(s) are attached between the orificed gas nozzle and the venturi tube to create a gap between the venturi tube and the orificed gas nozzle. In some embodiments, two or more venturi nozzles can be combined together in various configurations into a nozzle assembly or multi-nozzle gas combustor and attached, mounted or disposed within a stack, chimney or vented enclosure. The wall(s) of the stack, chimney or vented enclosure may include one or more openings, cut outs or vents to provide primary and secondary air to the venturi nozzles.

A venturi nozzle for a gas combustor includes an orificed gas nozzle, a venturi tube and one or more support members. The orificed gas nozzle has a longitudinal axis, an inlet and an outlet. The venturi tube is aligned with the longitudinal axis and has an entrance proximate to the outlet of the orificed gas nozzle and an exit. The support member(s) are attached between the orificed gas nozzle and the venturi tube to create a gap between the venturi tube and the orificed gas nozzle. In some embodiments, two or more venturi nozzles can be combined together in various configurations into a nozzle assembly or multi-nozzle gas combustor and attached, mounted or disposed within a stack, chimney or vented enclosure. The wall(s) of the stack, chimney or vented enclosure may include one or more openings, cut outs or vents to provide primary and secondary air to the venturi nozzles.

A thimble shaped burner is made of a porous foam metal material and is adapted to be mounted on the interior of a plenum chamber receiving a fuel/air mixture under pressure. The fuel/air mixture infuses into the interior of the thimble shaped burner body and exits from it through a burner port in a support structure where the fuel/air mixture that has been infused through the burner body is ignited. The burners are typically used in multiples and are mounted by means conventional fasteners passing through reinforced mounting flanges on the interior of an air fuel plenum chamber. Flame lift off is reduced or eliminated by particular configurations and dimensions of annular metal washers that are used in association with the burner bodies for mounting purposes.

A thimble shaped burner is made of a porous foam metal material and is adapted to be mounted on the interior of a plenum chamber receiving a fuel/air mixture under pressure. The fuel/air mixture infuses into the interior of the thimble shaped burner body and exits from it through a burner port in a support structure where the fuel/air mixture that has been infused through the burner body is ignited. The burners are typically used in multiples and are mounted by means conventional fasteners passing through reinforced mounting flanges on the interior of an air fuel plenum chamber. Flame lift off is reduced or eliminated by particular configurations and dimensions of annular metal washers that are used in association with the burner bodies for mounting purposes.