Combustor fuel control systems with flow divider assemblies

A method for supplying fuel to a combustor with a first nozzle, a second nozzle, and a third nozzle, the method comprising the steps of:

• supplying a flow of fuel into a dividing valve;
• dividing, in the dividing valve, the flow of fuel into a first portion and a second portion at a predetermined proportion, the first portion having a first pressure and the second portion having a second pressure;
• directing the first portion and the second portion into a balancing valve;
• equalizing, in the balancing valve, the first pressure and the second pressure;
• directing the first portion to the first nozzle;
• and
• directing the second portion to at least one of the second nozzle and the third nozzle, wherein the dividing valve comprises
• a dividing cavity configured to receive the flow of fuel, the dividing cavity including a first dividing valve port and a second dividing valve port, and
• a piston device arranged within the dividing cavity and selectively positioned to divide the flow of fuel in the dividing cavity such that the first portion of the flow is directed into the first dividing valve port and the second portion of the flow is directed into the second dividing valve port;
• and
• a balancing valve fluidly coupled to the dividing valve and configured to receive the first portion of the flow at the first pressure and the second portion of the flow at the second pressure, the balancing valve comprising:
• a balancing cavity including a first balancing cavity port and a second balancing cavity port, and
• wherein the balancing device is arranged within the balancing cavity and selectively positioned to direct the first portion of the flow into the first balancing cavity port at a third pressure and the second portion of the flow into the second balancing cavity port at a fourth pressure such that the first pressure is approximately equal to the second pressure,
• wherein the balancing valve comprises a first balancing valve element, a second balancing element, and a spring element biasing the first balancing valve element away from the second balancing valve element,
• wherein the first balancing valve element, the second balancing valve element, and the spring element are configured to move with one another within the balancing cavity, and wherein the first balancing valve element and the second balancing valve element are configured to move relative to one another with compression and expansion of the spring element,
• wherein the first balancing valve element is configured to selectively cover the first balancing cavity port and the second balancing valve element is configured to selectively cover the second balancing cavity port, and
• wherein the spring element is configured to bias the second balancing valve element to block the second balancing cavity port when the second pressure is less than a predetermined pressure differential relative to fourth pressure, and to bias the first balancing valve element to block the first balancing cavity port when the first pressure is less than a predetermined pressure above the fourth pressure.

A flow divider assembly, comprising:

• a dividing valve comprising:
• a dividing cavity configured to receive a flow of fuel, the dividing cavity including a first dividing valve port and a second dividing valve port, and
• a piston device arranged within the dividing cavity and selectively positioned to divide the flow of fuel in the dividing cavity such that a first portion of the flow is directed into the first dividing valve port and a second portion of the flow is directed into the second dividing valve port;
• and
• a balancing valve fluidly coupled to the dividing valve and configured to receive the first portion of the flow at a first pressure and the second portion of the flow at a second pressure, the balancing valve comprising:
• a balancing cavity including a first balancing cavity port and a second balancing cavity port, and
• a balancing device arranged within the balancing cavity and selectively positioned to direct the first portion of the flow into the first balancing cavity port at a third pressure and the second portion of the flow into the second balancing cavity port at a fourth pressure such that the first pressure is approximately equal to the second pressure,
• wherein the balancing valve comprises a first balancing valve element, a second balancing element, and a spring element biasing the first balancing valve element away from the second balancing valve element,
• wherein the first balancing valve element, the second balancing valve element, and the spring element are configured to move with one another within the balancing cavity, and wherein the first balancing valve element and the second balancing valve element are configured to move relative to one another with compression and expansion of the spring element,
• wherein the first balancing valve element is configured to selectively cover the first balancing cavity port and the second balancing valve element is configured to selectively cover the second balancing cavity port, and
• wherein the spring element is configured to bias the second balancing valve element to block the second balancing cavity port when the second pressure is less than a predetermined pressure differential relative to fourth pressure, and to bias the first balancing valve element to block the first balancing cavity port when the first pressure is less than a predetermined pressure above the fourth pressure.