Ammonia fired combustor operating method

A method of operating a combustor of a gas turbine, the combustor comprising a combustion liner that defines a combustion chamber, the combustion chamber including in a serial flow order a first zone, a second zone, and a third zone, the method comprising:

• delivering a fuel comprising mostly ammonia (NH3) and a first portion of oxidant as a fuel rich mixture to the first zone of the combustion chamber with one or more fuel nozzles disposed at a forward end of the combustor, wherein all of the fuel provided to the combustor is delivered to the first zone, wherein only the fuel comprising mostly ammonia is provided as the fuel to the combustor such that no other fuels are provided to the combustor in the second zone or the third zone, and wherein the fuel is defined as a gaseous or liquid product that ignites in the combustion chamber and produces combustion gases comprising nitrogen oxides (NOx);
• burning at least a portion of the fuel rich mixture in the first zone, whereby combustion gases containing nitrogen oxides (NOx) are produced and conveyed through the first zone over a first time period;
• conveying the combustion gases and unburned ammonia through the second zone over a second time period while delivering a second portion of the oxidant into the second zone to break down the unburned ammonia into ammonia intermediates in the second zone, whereby the nitrogen oxides in the combustion gases are consumed by reacting with the ammonia intermediates in the second zone, and whereby byproduct hydrogen is produced as a result of the break down of the unburned ammonia into the ammonia intermediates;
• delivering a third portion of the oxidant into the third zone while conveying the combustion gases and the byproduct hydrogen through the third zone over a third time period, wherein the third portion of the oxidant is greater than each of the first portion of the oxidant and the second portion of the oxidant, and wherein the second time period is greater than the first time period and the third time period, wherein the third zone begins once all of the unburned ammonia is consumed in the second zone such that only the combustion gases, the byproduct hydrogen, and the third portion of the oxidant enter the third zone;
• and
• burning the byproduct hydrogen in the third zone with the third portion of the oxidant.

A combustor comprising:

• a liner defining a combustion chamber extending between an inlet and an outlet, the combustion chamber including in a serial flow order a first zone, a second zone, and a third zone;
• at least one fuel nozzle configured to inject a fuel rich mixture of a fuel comprising mostly ammonia (NH3) and a first portion of oxidant in the first zone that produces nitrogen oxides (NOx) after ignition, wherein the first portion of the oxidant is between about 7% and about 15% of total oxidant added to the combustor, and wherein only the fuel comprising mostly ammonia is provided as the fuel to the combustor such that no other fuels are provided to the combustor in the second zone or the third zone, and wherein the fuel is defined as a gaseous or liquid product that ignites in the combustion chamber and produces combustion gases comprising nitrogen oxides (NOx);
• at least first two oxidant injection stages in the second zone, the at least first two oxidant injection stages in the second zone configured to inject a second portion of the oxidant comprising between about 7% and about 15% of the total oxidant added to the combustor;
• and
• at least second two oxidant injection stages in the third zone, the at least second two oxidant injection stages in the third zone configured to inject a third portion of the oxidant comprising between about 70% and about 86% of the total oxidant added to the combustor, wherein the third zone begins once all unburned ammonia is consumed in the second zone such that only combustion gases, byproduct hydrogen, and the third portion of the oxidant enter the third zone.