Gas Turbine Powerplant Terms

Gas Turbine Power Plant

thermal power plant that uses natural gas to generate electricity

Flow of Natural Gas in the Philippines

Malampaya to Mindoro to Batangas

Natural Gas

is preferred over diesel because it is cleaner and has less emissions and smaller carbon footprint

Natural Gas

has a higher efficiency and lower specific fuel consumption than diesel

Ilijan Combined-Cycle Gas Turbine Powerplant

largest natural gas facility in the Philippines with a 1200 MW combined-cycle

Compressor

is where atmospheric air is drawn in to increase its pressure and temperature to feed the combustion chamber

Axial-Type

type of compressor since it generates more air volume

Combustion Chamber (Combustor)

fuel is injected into compressed air, burning the mixture to create high temperature and pressure gases

Turbine

the gases will expand through turbine blades, causing them to rotate and generate mechanical energy

Starting motor

electric motor connected to the turbine shaft that initially rotates the turbine to reach a speed for the combustion process to be operated

Heavy Frame Engines

used for combined cycle gas powerplants

Heavy Frame Engines

have lower pressure ratios, slower in speed, heavier, higher air flow and slower start-up

Aeroderivative Engines

used for simple or open cycle gas turbine

Aeroderivative Engines

have high pressure ratios, very compact and useful where smaller outputs are needed

Turbojet

gas turbine used in fighter jets

Turbofan

gas turbine used in large aircrafts

Turboprop

gas turbine used for propellers

Turboshaft

also known as a power producing engine

Turboshaft

used in helicopters in their rotor blades

Turboshaft

used in Auxiliary Power Units (APU) for aircrafts (to provide compressed air to drive the main engine)

Simple Cycle Gas Turbine

is usually less efficient compared to combined cycles

Simple Cycle Gas Turbine

also known as Open-Cycle Gas Turbine (OCGT)

Simple Cycle Gas Turbine

usually only run for a few hours a day as a peaking power plant because of its lower efficiency and fast start-up

Simple Cycle Gas Turbine

usually uses Aeroderivative Gas Turbines because rapid power generation might be needed

Regenerator

used to improve thermal efficiency

Avion Power Plant

97 MW dual-fired OCGT that runs on aircraft engines for land-based power generation that can run both on natural gas or diesel, making it a peakload plant for peak demands or electricity

Combined-Cycle Gas Turbine

is composed of a Brayton cycle (gas), Heat Recovery System Generator (HRSG), and Rankine cycle (steam)

Combined-Cycle Gas Turbine

more efficient than simple cycles and can achieve efficiencies up to 55%

Combined-Cycle Gas Turbine

exhaust gas of the gas turbine goes to the HRSG to produce steam for the steam turbine

Heat Recovery Steam Generator (HRSG)

specialized heat exchanger that extracts heat from the gas turbine and utilizes it for steam

Evaporator

part of HRSG where actual steam is generated

Economizer

preheats the feedwater before entering the evaporator by recovering more heat from the exhaust gases

Superheater

part of HRSG that raises the temperature of the steam generated by the vapor

Steam Drums

part of HRSG that separates steam and water

Single Shaft

both prime movers are on one shaft line connected by a synchronous self-shifting (SSS) clutch and drive a single, common generator

SSS Clutch (Synchronous Self-Shifting)

mechanism that automatically engages and disengages gears based on shaft speed

Synchronized

The speed of the internal gear and external gear should be ___ so that they can mate

Double Shaft

where each turbine (gas and steam) has its own separate generator on a different shaft

Advantages of Combined Cycle Gas Turbine Powerplant

High Power-to-Weight Ratio; Quick Start-up and Shutdown; Higher Efficiency; Low Emissions

Disadvantages of Combined Cycle Gas Turbine Powerplant

High Capital Costs; Maintenance Complexity; External Power is Needed; Fossil fuel dependency

Brayton Cycle

cycle in gas turbine engines where both compression and expansion processes take place

Brayton Cycle

used in aircraft propulsion and electric power generation

Brayton Cycle

proposed by George Brayton for use in the reciprocating oil-burning engine in 1870

Air-standard cycle

this means air alone is the working medium

Actual Gas-Turbine Cycles

this is a result of irreversibilities in the cycle with a given compression and turbine efficiency for the whole cycle

Regenerative Gas Turbines with Reheat and Intercooling

if used in conjunction with regeneration, these will result in an increase in thermal efficiency

To increase the thermal efficiency

the heat added (QA) should be reduced and the neat work (Wnet) should be increased

Intercoolers

are placed in between the different stages of the compressor

Intercoolers

is a heat exchanger that uses water as a cooling medium to reject heat

Intercoolers

used to return the products going out the compressor to its original temperature to save the compressor it is connected to

Intercoolers

helps save power consumed by lowering the temperature inlet of the multi stage compressors

Intermediate Pressure for Minimum Compressor Work

equal to the product of the square root of the first stage (suction) and the last stage (discharge) of the multi stage compressors

Reheater

located between the turbine stages

Regenerator/Recuperator

uses the exhaust gas from the turbine to the input of the combustion chamber to use the heat waste and lessen the combustion needed

Regenerator/Recuperator

the thermal efficiency increases since the exhaust gas that is used to preheat the air in the combustion chamber decreases the heat input and required net work

Regenerator Effectiveness

ratio of the actual enthalpy increase of the air flowing through the compressor side of the regenerator to the maximum theoretical enthalpy increase

Gas Turbines with Reheat without Regeneration

Same Compressor Work, Increase in Turbine Work, Decrease in Back Work Ratio, Decrease in Thermal Efficiency

Gas Turbines with Intercooling without Regeneration

Decrease in Compressor Work, Same Turbine Work, Decrease in Back Work Ratio, Decrease in Thermal Efficiency

Gas Turbines with Intercooling and Reheating without Regeneration

Decrease in Compressor Work, Increase in Turbine Work, Decrease in Back Work Ratio, Decrease in Thermal Efficiency

Gas Turbines with two-stage compression with intercooling, two-stage expansion with reheating, and regeneration

Decrease in Compressor Work, Increase in Turbine Work, Decrease in Back Work Ratio, Increase in Thermal Efficiency