US 6,289,851 B1Granted

Compact low-nox high-efficiency heating apparatus

AssigneeInstitute of Gas Technology

InventorsIosif K. Rabovitser, Richard A. Knight, Hamid A. Abbasi

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Abstract

A multi-stage heating apparatus having a first stage combustion chamber, a second stage combustion chamber, a primary porous matrix chamber disposed between the first and second stage combustion chambers, a secondary porous matrix chamber, heat exchanger tubes for transfer of heat from the combustion products to a working fluid, a recirculation device for recirculating combustion products in the first and second stage combustion chambers to the root of flames therein. A mixture of fuel and primary oxidant is introduced into the first stage combustion chamber, and the products of combustion therein are conveyed to the porous matrix chamber disposed between the first and second stage combustion chambers. After undergoing intensive heat transfer in the porous matrix chamber, the cooler products of combustion flow into the second stage combustion chamber forming additional products of combustion. The products of combustion then flow to a second porous matrix chamber in which they undergo further intensive heat transfer. From there, the products of combustion pass through an economizer for preheating a working fluid and through a condenser for removing moisture in the combustion products prior to being exhausted.

Claims26

Dependent claims

A heating apparatus comprising:

a first stage combustion chamber having a fuel/oxidant premix inlet and a first stage combustion products outlet;
a second stage combustion chamber having a second stage combustion products inlet in fluid communication with said first stage combustion products outlet and a second stage combustion products outlet;
a primary porous matrix chamber disposed between said first stage combustion chamber and said second stage combustion chamber having a primary matrix combustion products inlet in fluid communication with said first stage combustion products outlet and a primary matrix combustion products outlet in fluid communication with said second stage combustion products inlet;
a secondary porous matrix chamber having a secondary porous matrix combustion products inlet in fluid communication with said second stage combustion products outlet and a secondary porous matrix combustion products outlet;
heat exchange means for transfer of heat from said combustion products to a working fluid, said heat exchange means disposed in each of said first stage combustion chamber, said primary porous matrix chamber, said second stage combustion chamber and said secondary porous matrix chamber;
recirculation means for recirculating combustion products to a flame root of a flame present in each of said first stage combustion chamber and said second stage combustion chamber disposed in said first stage combustion chamber and said second stage combustion chamber;
and
means for introducing at least one of a secondary combustion oxidant and a secondary fuel into said second stage combustion chamber.

5 more elements

A combustion method comprising the steps of:

introducing a mixture of a fuel and a primary oxidant into a first stage combustion chamber and igniting said mixture, forming a flame and products of combustion;
recirculating at least a portion of said products of combustion to a root of said flame;
removing at least a portion of first stage heat generated by said flame from said first stage combustion chamber;
introducing said products of combustion into a primary porous matrix chamber comprising a radiating material surrounding at least one heat exchanger tube containing a working fluid to be heated, thereby forming cooled products of combustion and heating said working fluid;
introducing said cooled products of combustion and at least one of a secondary combustion oxidant and an additional amount of said fuel into a second stage combustion chamber, forming a second stage flame and additional said products of combustion;
removing at least a portion of second stage heat generated by said second stage flame from said second stage combustion chamber;
introducing said products of combustion into a secondary porous matrix chamber comprising said radiating material surrounding a second stage heat exchanger containing said working fluid;
recirculating at least a portion of said products of combustion to a root of said second stage flame;
and
exhausting said products of complete combustion from said secondary porous matrix chamber.

7 more elements

Dependencies are inferred from the claim text.

Facts

Application: 09/691,755Filed 18 Oct 2000
Granted: 18 Sep 2001
Term ends: Not estimatedThe source records don’t support an estimate.

Classification11 codes

F23C 9/006
Combustion apparatus characterised by arrangements for returning combustion products or flue gases to the combustion chamber: the recirculation…
F22B 31/04
Modifications of boiler construction, or of tube systems, dependent on installation of combustion apparatus; Arrangements or dispositions of…:…
F23C 6/042
In series connection: with fuel supply in stages
F23L 15/04
Heating of air supplied for combustion: arrangements of recuperators