Oxyfuel turbine system and method for oxidant control

Patent metadata

Field	Value
Publication number	US-12467405-B2
Application number	US-202318838880-A
Country	US
Kind code	B2
Filing date	Feb 23, 2023
Priority date	Feb 23, 2022
Publication date	Nov 11, 2025
Grant date	Nov 11, 2025

Abstract

The gas turbine system comprises a combustor adapted to combust a fuel and an oxidant and generate pressurized hot combustion gas and a turbine fluidly coupled to the combustor and rotated by expansion of the pressurized hot combustion gas from the combustor. A heat exchanger is fluidly coupled to the turbine and adapted to cool expanded combustion gas exhausted from the turbine. A main oxidant supply line is adapted to supply oxidant to the combustor through the heat exchanger. The oxidant streaming through the heat exchanger is in heat exchange relationship with combustion gas exhausted from the turbine. A fuel supply line supplies fuel to the combustor. A secondary oxidant supply line is adapted to supply oxidant in the fuel supply line upstream of a fuel control valve. Also disclosed is a method of operating the system.

First claim

The invention claimed is:

1 . A gas turbine system ( 1 ) comprising:
a combustor adapted to combust fuel and oxidant and generate pressurized hot combustion gas; a turbine fluidly coupled to the combustor and rotated by expansion of the pressurized hot combustion gas from the combustor; a heat exchanger fluidly coupled to the turbine and adapted to chill expanded combustion gas exhausted from the turbine; a main oxidant supply line adapted to supply a main oxidant stream to the combustor through the heat exchanger; wherein in use the main oxidant stream flowing through the heat exchanger is in heat exchange with the combustion gas exhausted from the turbine, such that heat is transferred from the combustion gas to the main oxidant stream and the combustion gas is chilled; a recycle line adapted to recycle a first chilled combustion gas stream through the heat exchanger to the combustor as working fluid; a combustion gas removal line adapted to exhaust a second chilled combustion gas stream; a fuel supply line adapted to supply the fuel to the combustor; a fuel control valve along the fuel supply line adapted to adjust a fuel flowrate delivered to the combustor; and a secondary oxidant supply line coupled to the fuel supply line at a mixing point upstream of the fuel control valve; wherein the secondary oxidant supply line is adapted to feed a secondary oxidant stream in the fuel supply line.

2 . The turbine system of claim 1 , wherein the secondary oxidant supply line is arranged such as to bypass the heat exchanger.

3 . The turbine system of claim 1 , wherein the combustor comprises a plurality of fuel nozzles downstream of the fuel control valve.

4 . The turbine system of claim 1 , further comprising a secondary oxidant control valve in the secondary oxidant supply line adapted to modulate a secondary oxidant flowrate through the secondary oxidant supply line during a transient condition of the turbine in response to a variation in a load on the turbine.

5 . The turbine system of claim 4 , further comprising a main oxidant control valve in the main oxidant supply line, and a control unit;
wherein the control unit is adapted to selectively open and close the secondary oxidant control valve and the main oxidant control valve in response to the variation in the load on the turbine.

6 . The turbine system of claim 5 , wherein the control unit is adapted to perform the following steps:
increasing or decreasing a secondary oxidant flowrate through the secondary oxidant control valve in response to an increase or decrease of the load on the turbine; subsequently decreasing or increasing the secondary oxidant flowrate through the secondary oxidant control valve and simultaneously increasing or decreasing a main oxidant flowrate through the main oxidant control valve, maintaining an constant oxidant flowrate to the combustor.

7 . The turbine system of claim 1 , further comprising:
a main oxidant flowmeter adapted to detect oxidant flowrate in the main oxidant supply line; a secondary oxidant flowmeter adapted to detect oxidant flowrate in the secondary oxidant supply line; a secondary oxidant control valve adapted to adjust the oxidant flowrate in the secondary oxidant supply line; a control unit adapted to act upon the secondary oxidant control valve fs based on detection signals from the main oxidant flowmeter and the secondary oxidant flowmeter.

8 . The turbine system of claim 7 , further comprising a fuel flowmeter adapted to detect the fuel flowrate through the fuel supply line; and wherein the control unit is adapted to act upon the secondary oxidant control valve based on a detection signal from the fuel flowmeter in combination with detection signals from the main oxidant flowmeter and the secondary oxidant flowmeter.

9 . A method for operation of a turbine system, the method comprising:
supplying a fuel stream to a combustor through a fuel supply line; supplying a main oxidant stream to the combustor through a heat exchanger; combusting fuel from the fuel supply line, and oxidant in the combustor and generating a stream of pressurized hot combustion gas; expanding the combustion gas in a turbine and generating mechanical power therewith; discharging exhaust combustion gas from the turbine; flowing the exhaust combustion gas in the heat exchanger in heat exchange with the main oxidant stream, whereby the exhaust combustion gas is chilled and the main oxidant stream is heated; recycling a first chilled combustion gas stream through the heat exchanger to the combustor as working fluid and discharging a second chilled combustion gas stream; supplying a secondary oxidant stream to the fuel stream and blending the secondary oxidant stream in the fuel stream upstream of a fuel control valve arranged in the fuel supply line to form a blend of oxidant and fuel; and supplying the blend of oxidant and fuel to the combustor.

10 . The method of claim 9 , wherein the blend of oxidant and fuel is supplied to a plurality of fuel nozzles of the combustor.

11 . The method of claim 9 , further comprising a step of modulating a flowrate of the secondary oxidant stream in response to a load variation on the turbine.

12 . The method of claim 9 , further comprising the following steps:
increasing or decreasing a secondary oxidant flowrate through a secondary oxidant control valve in response to an increase or decrease of a load on the turbine; subsequently decreasing or increasing the secondary oxidant flowrate through the secondary oxidant control valve and simultaneously increasing or decreasing a main oxidant flowrate through a main oxidant control valve, maintaining a constant oxidant flowrate to the combustor.

13 . The method of claim 9 , further comprising a step of capturing carbon dioxide from the second chilled combustion gas stream.

14 . The method of claim 9 , wherein the secondary oxidant stream is supplied through a secondary oxidant supply line which bypasses the heat exchanger.

Assignees

• Nuovo Pignone Tecnologie Srl
• Nuovo Pignone Tecnologie—S R L

Inventors

• Miliani Alessio
• Zucca Alessandro
• Cosi Lorenzo
• Gamberi Francesco

Classifications

• Y02E20/34

  Indirect CO2mitigation, i.e. by acting on non CO2directly related matters of the process, e.g. pre-heating or heat recovery · CPC title

• F23R3/28

  characterised by the fuel supply (burners F23D) · CPC title

• F02C7/2365

  comprising an air supply system for the atomisation of fuel · CPC title

• F02C7/222

  Fuel flow conduits, e.g. manifolds · CPC title

• F05D2270/306

  Mass flow · CPC title