The present invention relates to a combustion apparatus capable of reducing the emission amount of nitrogen oxide and enabling stable combustion in the entire area of a set load. The combustion apparatus includes: a premixing chamber for premixing air and a gas; a blower for supplying a mixed-gas of the air and the gas to a burner; a combustion chamber for burning the mixed-gas by ignition of the burner; a heat exchanger for exchanging heat with water by using combustion heat in the combustion chamber; and an exhaust gas discharge part for discharging the exhaust gas passing through the heat exchanger, wherein the premixing chamber is formed in a Venturi shape having a throat part of which the cross-section area is tapered between an inlet and an outlet through which the air passes, the throat part of the premixing chamber being connected to a gas supply part for supplying a gas for combustion, and to an exhaust gas recirculation tube to which some of the exhaust gas having passed through the heat exchanger is introduced in proportion to differential pressure according to the flow rate of the mixed-gas passing through the throat part.

The present invention relates to a combustion apparatus capable of reducing the emission amount of nitrogen oxide and enabling stable combustion in the entire area of a set load. The combustion apparatus includes: a premixing chamber for premixing air and a gas; a blower for supplying a mixed-gas of the air and the gas to a burner; a combustion chamber for burning the mixed-gas by ignition of the burner; a heat exchanger for exchanging heat with water by using combustion heat in the combustion chamber; and an exhaust gas discharge part for discharging the exhaust gas passing through the heat exchanger, wherein the premixing chamber is formed in a Venturi shape having a throat part of which the cross-section area is tapered between an inlet and an outlet through which the air passes, the throat part of the premixing chamber being connected to a gas supply part for supplying a gas for combustion, and to an exhaust gas recirculation tube to which some of the exhaust gas having passed through the heat exchanger is introduced in proportion to differential pressure according to the flow rate of the mixed-gas passing through the throat part.

A modulating burner apparatus includes a burner and a blower placed upstream of the burner. A venturi is placed upstream of the blower. A damper valve is placed upstream of the venturi. The damper valve has an open position and a restricted position. A smaller gas valve and a larger gas valve are communicated with the venturi. A controller is operably associated with the system to select a position of the damper valve and to select the appropriate one of the gas valves so as to provide a low output operation mode and a high output operation mode, which in combination provide an overall turndown ratio of at least 25:1.

A modulating burner apparatus includes a burner and a blower placed upstream of the burner. A venturi is placed upstream of the blower. A damper valve is placed upstream of the venturi. The damper valve has an open position and a restricted position. A smaller gas valve and a larger gas valve are communicated with the venturi. A controller is operably associated with the system to select a position of the damper valve and to select the appropriate one of the gas valves so as to provide a low output operation mode and a high output operation mode, which in combination provide an overall turndown ratio of at least 25:1.

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 dry low NO.sub.X staged combustion system includes a fuel nozzle and a combustion compartment. The fuel nozzle includes a purge gas tube, a diffusion combustion fuel tube, an isolation gas tube, a premixed combustion fuel tube, a premixed combustion air tube. The purge gas tube is configured to feed a purge gas. The diffusion combustion fuel tube is fitted over the purge gas tube, and having an end provided with a diffusion combustion fuel swirler. The isolation gas tube is fitted over the diffusion combustion fuel tube. The premixed combustion fuel tube is fitted over the isolation gas tube. The premixed combustion air tube is fitted over the premixed combustion fuel tube. The combustion compartment is located downstream of the fuel nozzle.

The present invention relates to methods and systems for controlling a combustion reaction and the products thereof. One embodiment includes a combustion control system having an oxygenation stream substantially comprising oxygen and CO.sub.2 and having an oxygen to CO.sub.2 ratio, then mixing the oxygenation stream with a combustion fuel stream and combusting in a combustor to generate a combustion products stream having a temperature and a composition detected by a temperature sensor and an oxygen analyzer, respectively, the data from which are used to control the flow and composition of the oxygenation and combustion fuel streams. The system may also include a gas turbine with an expander and having a load and a load controller in a feedback arrangement.

The present invention relates to methods and systems for controlling a combustion reaction and the products thereof. One embodiment includes a combustion control system having an oxygenation stream substantially comprising oxygen and CO.sub.2 and having an oxygen to CO.sub.2 ratio, then mixing the oxygenation stream with a combustion fuel stream and combusting in a combustor to generate a combustion products stream having a temperature and a composition detected by a temperature sensor and an oxygen analyzer, respectively, the data from which are used to control the flow and composition of the oxygenation and combustion fuel streams. The system may also include a gas turbine with an expander and having a load and a load controller in a feedback arrangement.

A mobile heating device operated with liquid fuel is provided, having: a combustion chamber (2) comprising a combustion air inlet (3), wherein the combustion chamber adjacent to the combustion air inlet (3) comprises a widening portion (20) the cross-section of which widens with increasing distance from the combustion air inlet (3) and in which in operation combustion air and fuel are converted in a flaming combustion; a fuel supply which is arranged such that fuel is supplied into the widening portion (20); and an air guide device (6) being adapted to feed combustion air into the widening portion (20) with a flow component directed in the circumferential direction such that an axial recirculation region (RB) forms in the widening portion (20) in which gases flow in the direction towards the combustion air inlet (3) oppositely to a main flow direction (H). The combustion chamber (2) is fluidically sectioned into a primary combustion zone (PZ) and a secondary combustion zone (SZ). The primary combustion zone (PZ) comprises the widening portion (20) and the recirculation region (RB). The secondary combustion zone (SZ) is provided with a secondary combustion air inlet (23) in such a manner that a higher air-fuel ratio λ than in the primary combustion zone (PZ) forms in the secondary combustion zone (SZ).