Systems and methods to improve shut-down purge flow in a gas turbine system

A method, comprising:

• utilizing a controller to:
• control at least one purging fluid flow source to provide a supplemental purging fluid flow to a gas turbine or a heat recovery steam generator (HRSG) of a gas turbine and HRSG system;
• receive a first measurement of a first temperature of the gas turbine and HRSG system from a first sensor, wherein the first measurement of the first temperature comprises at least a temperature at an inlet of the gas turbine;
• receive a second measurement of a rotational speed of the gas turbine from a second sensor;
• receive a third measurement of a supplemental purging fluid flow rate of the supplemental purging fluid flow during deceleration of the gas turbine from a third sensor;
• calculate an exhaust volume flow rate of the gas turbine and HRSG system based on at least the first temperature, the rotational speed of the gas turbine, and the purging fluid flow rate;
• obtain a purging volume of the gas turbine and HRSG system that is based on at least a volume of an HRSG of the gas turbine and HRSG system;
• and
• control the gas turbine and HRSG system, during shut-down of the gas turbine and HRSG system, to isolate a fuel source from the gas turbine at a portion of normal operating speed of the gas turbine sufficient to achieve the purging volume during coast down of air flow through the gas turbine and HRSG system based on the exhaust volume flow rate.

A tangible, non-transitory, machine-readable-medium, comprising machine-readable instructions to:

• control at least one purging fluid flow source to provide a supplemental purging fluid flow to a gas turbine of a power generation system;
• receive a first measurement of a first temperature of the power generation system from a first sensor, wherein the first measurement of the first temperature comprises at least a temperature at an inlet of the gas turbine;
• receive a second measurement of a rotational speed of the gas turbine from a second sensor;
• receive a third measurement of a supplemental purging fluid flow rate of the supplemental purging fluid flow during deceleration of the gas turbine from a third sensor;
• calculate an exhaust flow rate of the power generation system based on at least the first temperature, the rotational speed of the gas turbine, and the supplemental purging fluid flow rate;
• and
• control the power generation system, during shut-down of the power generation system, to isolate a fuel source from the gas turbine at a portion of normal operating speed of the power generation system sufficient to achieve a purging volume during coast down of air flow through the power generation system based at least on the exhaust flow rate.