Reduction of gaseous pollutants in combustion flue gas

Claim 2

Fuel burning apparatus adapted for reducing nitrogen oxides in its exhaust gas, comprising: a. means defining a primary combustion zone having an inlet for combustion supporting gas and an outlet for gaseous combustion products and having means for introducing fuel therein, b. a secondary combustion device disposed in a secondary combustion zone through which the gaseous combustion products flow from the primary zone, c. a source of combustion supporting gas, d. first flow control means constructed and arranged to conduct said gas to said primary combustion zone, e. second flow control means constructed and arranged to conduct said combustion supporting gas to said secondary combustion zone by way of said device, and f. means for sensing the level of carbon monoxide in the gaseous combustion products downstream of said secondary combustion device, said sensing means being operatively coupled to said second flow control means, said sensing means being responsive to the sensed level of carbon monoxide for operating said second flow control means to adjust the flow of said combustion supporting gas provided to said secondary zone in direct relation to the level of said sensed carbon monoxide.

Claim 3

The apparatus set forth in claim 1 including: a. fuel control means operatively coupled with said first flow control means for simultaneously regulating said combustion supporting gas and said fuel to said primary combustion zone whereby to maintain the desired ratio of gas to fuel in said zone.

Claim 4

The apparatus set forth in claim 2 including: a. means defining a main gas flow path leading from said source of combustion supporting gas to said first and second flow control means, and means for altering the flow rate in said main path thereby altering the flow rates through said first and second flow control means.

Claim 5

The apparatus set forth in claim 3 wherein said secondary combustion device comprises: a. a plurality of elongated hollow means extending into the flow path of said gaseous combustion products flowing in said secondary combustion zone and having a plurality of openings for dispersing said combustion supporting gas into the gas stream flowing through said secondary combustion zone, said hollow means being supplied with gas through one of said flow control means.

Claim 6

The apparatus set forth in claim 4 wherein said secondary combustion device comprises: a. a plurality of tubular elements which have longitudinally disposed openings for dispersing said combustion supporting gas into the gaseous combustion products in said secondary combustion zone, said tubular elements being coupled with said second gas flow control means.

Claim 7

The device set forth in claim 5 wherein: a. said tubular elements have their openings disposed in the downstream direction of gaseous combustion product flow.

Claim 8

Fuel burning apparatus adapted for reducing nitrogen oxides in its exhaust gas, comprising: a. means defining a primary combustion zone having an inlet for combustion supporting gas and an outlet for gaseous combustion products and having means for introducing fuel therein, b. a secondary combustion device disposed in a secondary combustion zone through which the gaseous combustion products flow from the primary zone, c. a source of combustion supporting gas, d. first flow control means constructed and arranged to conduct said gas to said primary combustion zone, e. second flow control means constructed and arranged to conduct said combustion supporting gas to said secondary combustion zone by way of said device, f. said secondary combustion device comprising a plurality of elongated hollow means having a plurality of openings for dispersing said combustion supporting gas into the gas stream flowing through said secondary combustion zone, said hollow means being supplied with gas through said second flow control means and being comprised of a porous material selected from the class consisting of ceramic, heat resistant metals and silicon carbide, and g. means for sensing the level of at least one of the gaseous combustion products downstream of said secondary combustion device, said sensing means being operatively coupled to said second flow control means, said sensing means being responsive to the sensed level of said at least one gaseous combustion product for operating said second flow control means to adjust the flow of said combustion supporting gas provided to said secondary zone.

Claim 9

Fuel burning apparatus adapted for reducing nitrogen oxides in its exhaust gas, comprising: a. means defining a primary combustion zone having an inlet for combustion supporting gas and an outlet for gaseous combustion products and having means for introducing fuel therein, b. a secondary combustion device disposed in a secondary combustion zone through which the gaseous combustion products flow from the primary zone, c. a source of combustion supporting gas, d. first flow control means constructed and arranged to conduct said gas to said primary combustion zone, e. second flow control means constructed and arranged to conduct said combustion supporting gas to said secondary combustion zone by way of said device, f. said secondary combustion device comprising a plurality of elongated hollow means having a plurality of openings for dispersing said combustion supporting gas into the gas stream flowing through said secondary combustion zone, said hollow means being supplied with gas through said second flow control means and being comprised of a porous material selected from the class consisting of ceramic, heat resistant metals and silicon carbide, and g. means for sensing the level of at least one of the gaseous combustion products downstream of said secondary combustion device, said sensing means being operatively coupled to said second flow control means, said sensing means being responsive to the sensed level of said at least one gaseous combustion product for operating said second flow control means to adjust the flow of said combustion supporting gas provided to said secondary zone.

Claim 10

Fuel burning apparatus adapted for reducing nitrogen oxides in its exhaust gas, comprising: a. means defining a primary combustion zone having an inlet for combustion supporting gas and an outlet for gaseous combustion products and having means for introducing fuel therein, b. a secondary combustion device disposed in a secondary combustion zone through which the gaseous combustion products flow from the primary zone, c. a source of combustion supporting gas, d. first flow control means constructed and arranged to conduct said gas to said primary combustion zone, e. second flow control means constructed and arranged to conduct said combustion supporting gas to said secondary combustion zone by way of said device, f. said secondary combustion device comprising a plurality of secondary air delivery elements including a hollow element having a plurality of holes therein for dispersing secondary combustion air in said gaseous combustion product stream, said air delivery elements being coupled to said second flow control means, and cooling means defining a cooling fluid flow space in conjunction with each said air delivery elements, and g. means for sensing the level of at least one of the gaseous combustion products downstream of said secondary combustion device, said sensing means being operatively coupled to said second flow control means, said sensing means being responsive to the sensed level of said at least one gaseous combustion product for operating said second flow control means to adjust the flow of said combustion supporting gas provided to said secondary zone.

Claim 11

Fuel burning apparatus adapted for reducing nitrogen oxides in its exhaust gas, comprising: a. means defining a primary combustion zone having an inlet for combustion supporting gas and an outlet for gaseous combustion products and having means for introducing fuel therein, b. a secondary combustion device disposed in a secondary combustion zone through which the gaseous combustion products flow from the primary zone, c. a source of combustion supporting gas, d. first flow control means constructed and arranged to conduct said gas to said primary combustion zone, e. second flow control means constructed and arranged to conduct said combustion supporting gas to said secondary combustion zone by way of said device, f. said secondary combustion device comprising a plurality of secondary air delivery elements including a hollow element having a plurality of holes therein for dispersing secondary combustion air in said gaseous combustion product stream, said air delivery elements being coupled to said second flow control means, and cooling means defining a cooling fluid flow space in conjunction with each said air delivery elements, and g. means for sensing the level of at least one of the gaseous combustion products downstream of said secondary combustion device, said sensing means being operatively coupled to said second flow control means, said sensing means being responsive to the sensed level of said at least one gaseous combustion product for operating said second flow control means to adjust the flow of said combustion supporting gas provided to said secondary zone.

Claim 12

The apparatus set forth in claim 8 wherein said secondary air delivery elements comprise: a. a plurality of tubular assemblies each including an inner tubular element having openings in its wall and being connected for being supplied from said second flow control means, b. an outer tubular element surrounding each said inner elements for defining the cooling fluid flow space in conjunction therewith, and c. means having a passageway extending from each said inner tubular element openings through said cooling fluid space and said outer tubular element to permit combustion supporting gas to flow from the inner element to said secondary combustion zone.

Claim 13

The device set forth in claim 9 wherein: a. said passageway means are elongated, extend axially of said tubular elements, and diverge from each other.