초록 ▼

A combustor capable of reducing the noxious emissions such as fuel bound and thermal nitrogen oxide products, during combustion of high nitrogen bearing and high aromatic content fuels is disclosed. The combustor includes a plurality of substantially concentric pipes defining annular passages with a

A combustor capable of reducing the noxious emissions such as fuel bound and thermal nitrogen oxide products, during combustion of high nitrogen bearing and high aromatic content fuels is disclosed. The combustor includes a plurality of substantially concentric pipes defining annular passages with annular divergent nozzles. The divergent nozzles may be formed by rings having a venturi shaped axial section to facilitate fast mixing of axially supplied air between adjacent annular passages. The longitudinal spacing between at least two adjacent nozzles defines first and second divergent cavities. A fuel rich torodial vortex is formed in proximity to a central fuel jet in the first cavity and advantageously converts fuel bound nitrogen to N2. A fuel lean torodial vortex formed in the second cavity mixes hot combustion products with additional gaseous reactant to complete the combustion while avoiding locally high temperatures, and thus thermal NOx formation. A ring of jet nozzles radially injects relatively small amounts of high pressure gaseous reactant or steam to form a throat to separate and stabilize the vortices. Alternatively, the pipe extending between the two cavities can include a convergent and divergent portion forming the throat between the cavities for separating and reinforcing the toroidal vortices. Guide vanes may be positioned in the annular passages to swirl the gaseous reactant entering the cavities to assist in the formation of the toroidal vortices.

대표청구항 ▼

A rich-lean combustor having at least one combustion stage and operable with reduced emission of fuel bound and thermal nitrogen oxide products, said combustor comprising: a. tubular wall means having at least three successive tubular wall portions disposed in successive downstream locations and hav

A rich-lean combustor having at least one combustion stage and operable with reduced emission of fuel bound and thermal nitrogen oxide products, said combustor comprising: a. tubular wall means having at least three successive tubular wall portions disposed in successive downstream locations and having respectively increasing dimensions in the radial direction to provide a generally outwardly diverging combustor envelope along the axial direction that defines an outwardly diverging combustion zone for low NOx combustion; b. means for supporting said tubular wall portions relative to each other to provide a rigid structure for the combustor; c. nozzle means for supplying fuel to said combustor in at least one predetermined location; d. each successive pair of adjacent tubular wall portions being structured to define a generally annular inlet flow path extending in the radial direction between the outer surface of the radially inward upstream wall portion of the pair and the inner surface of the radially outward downstream wall portion of the pair and further extending downstream in the axial direction along the inner surface of the radially outward downstream wall portion of the pair so that successive annular flow paths axially overlap, to enable the annular flows to combine at least partly for swirling radially inward flow into said combustion zone, said wall portions further being sized and structurally coordinated so that the total annular air flow includes substantially all of the pressurized inlet air flow needed for complete fuel burning in said combustion zone, other than any nozzle atomizing air flow or other special air flow that may be provided and such that the combustion air flows inwardly at a rate needed to support rich combustion along the axial region of said combustion zone thereby enabling leaner combustion radially outwardly and axially downstream thereof within said combustion zone; e. first swirl means for imparting a tangential velocity to inlet air flow through the first and radially inmost annular flow path; f. second swirl means for imparting a tangential velocity to inlet air flow through the second annular flow path located radially outwardly and axially downstream from the first annular flow path; and g. said first and second swirl means being interrelated to produce a negative radial gradient in the tangential velocities of the inlet air flows through the first and second annular paths, said tangential velocities decreasing with increasing radius and being operative within the diverging envelope of said combustion zone under operating inlet air pressure and gas axial velocity conditions to produce a depression of the axial velocity on the combustor axis with substantially all of the combustion air being recuperatively supplied by the swirling annular inlet flows after cooling the inner surfaces of said wall portions defining said combustion zone.