LNG power plant and operation method thereof

A fuel gas temperature control system for an LNG power plant having a gas turbine power generation unit having a gas turbine and a power generator, an LNG vaporization facility configured to feed vaporized LNG as a fuel gas to the gas turbine power generation unit, and a gas feed pipe extended from the LNG vaporization facility to the gas turbine power generation unit, the system comprising:

• (a) a fuel gas heating/cooling device disposed between the LNG vaporization facility and the gas turbine unit on the gas feed pipe, configured to heat and cool the fuel gas introduced into the gas turbine power generation unit;
• (b) a plurality of heating value detectors configured to detect a heating value of the fuel gas;
• (c) a temperature detector attached on the gas feed pipe between the fuel gas heating/cooling device and the gas turbine unit configured to detect a temperature of the fuel gas;
• and
• (d) a temperature control device of the fuel gas heating/cooling device configured to control temperature of the fuel gas supplied to the gas turbine power generation unit, the temperature control device having:
• a target temperature calculator connected to the heating value detector configured to receive a heating value of the fuel gas and calculate a target temperature of the fuel gas introduced to the gas turbine power generation unit;
• and
• a command generator connected to the target temperature calculator and the fuel gas heating/cooling device configured to receive the target temperature and a signal of temperature of the fuel gas detected by the temperature detector and generate a command to control the fuel gas heating/cooling device by comparing the target temperature and the temperature of the fuel gas.

A method of operating an LNG power plant, the method comprising:

• (a) detecting a heating value of a fuel gas supplied by an LNG vaporization facility;
• (b) generating a command to control the temperature of the fuel gas;
• (c) heating/cooling the fuel gas based on the command and introducing the fuel gas to a gas turbine power generation unit;
• (d) detecting a temperature of the fuel gas introduced to the gas turbine power generation unit;
• and
• (e) calculating a target temperature of the fuel gas introduced to the gas turbine power generation unit based on the heating value;
• wherein the command is generated by comparing the temperature of the fuel gas with the target temperature.

The method of operating an LNG power plant of claim 15, wherein:

• the step of detecting a heating value includes:
• detecting a status of the LNG vaporization facility,
• calculating a value equivalent to the heating value of the fuel gas as a first heating value, and
• detecting a heating value of the fuel gas before heating/cooling as a second heating value;
• and
• the step of generating includes:
• correcting the delay of the second heating value detection to a actual change in a heating value of the fuel gas by a dynamic characteristic model with the first heating value.