Patent ID: 8002541

Claim:
An apparatus comprising: a structure defining a combustion chamber; a burner having a port configured to deliver primary reactants into the combustion chamber to generate primary combustion products that flow downstream through the combustion chamber; a secondary fuel injector structure configured to inject second stage fuel into the combustion chamber separately from the burner port; a tertiary fuel injector structure configured to inject third stage fuel into the combustion chamber downstream of the secondary fuel injector structure; and a system configured to deliver fuel and combustion air to the combustion chamber through the burner, the secondary fuel injector structure, and the tertiary fuel injector structure at target rates that together have a target fuel-to-oxidant ratio, while delivering no additional combustion air to the combustion chamber, by: a) delivering the entire target rate of combustion air and a first partial target rate of fuel to the burner for delivery into the combustion chamber as primary reactants; b) simultaneously delivering a second partial target rate of fuel to the secondary fuel injector structure for delivery into the combustion chamber as second stage fuel under high temperature conditions that cause the second stage fuel to auto-ignite without requiring a combustion catalyst; and c) simultaneously delivering the balance of the target rate of fuel at a third partial target rate to the tertiary fuel injector structure for delivery into the combustion chamber as third stage fuel under high temperature conditions that cause the third stage fuel to auto-ignite without requiring a combustion catalyst.