IGCC is a new power generation system aiming at higher efficiency than regular coal-fired power generation by integrating coal gasification with combined cycle power generation technology consisting of gas turbine and steam turbine .

Differences to regular coal-fired power generation

Regular coal-fired power generation

The heat generated when coal is burned in the boiler is used to convert water into steam, and the steam’s expansion force is used to rotate the steam turbine and generate power.

Integrated coal Gasification Combined Cycle(IGCC)

Coal is gasified in the gasifier to produce fuel gas.
This fuel gas is fed into the gas turbine for combustion, which rotates the gas turbine and generates power.
In addition, the high-temperature exhaust gas that remains in the gas turbine is then fed into a boiler, and that heat generates steam, which rotates the steam turbine and generates power.


Coal is gasified in the ‘Gasification system’ to produce fuel gas. After the fuel gas has been cleaned in the ‘Gas clean-up system’, it generates power in the ‘combined cycle power generation system’ consisting of gas turbine and steam turbine.
*If you click the name of each equipment, you can read its explanation.
(Gasification system,Gas clean-up system,Combined cycle power generation system)


Gasification system

  • Coal is pulverized in the pulverizer and fed into the gasifier with nitrogen (dry feed).
  • The gasifier employs a two-chamber, two-stage entrained flow system consisting of a lower combustor (combustion chamber) and an upper reductor (reaction chamber).
  • The pulverized coal is burned at high temperature in the combustor to generate a high-temperature heat source that is required for the gasification reaction in the reductor.
  • The heat generated in the combustor is used in the reductor to gasify the pulverized coal and produce high-temperature coal gas(syngas).
  • SGC(Syngas Cooler),heat exchanger, uses the heat of coal gas and produces steam which is led into steam turbine.
  • Unburned material (char) that has not been fully gasified is collected at the gasifier outlet by the char recovery equipment and this is fed back into the combustor.
    The char is repeatedly fed into the gasifier until it is completely burned.

Gas clean-up system

  • The gas purifier removes impurities such as sulfur compounds (H₂S※1、COS※2)from the coal gas in stages using water and chemicals (wet process).
  • The COS in the coal gas is converted to H₂S in the COS converter (catalyst).
  • Trace elements such as halogen and ammonia are removed in the wet scrubber and the cooling tower.
  • The H₂S is removed in the H₂S absorption tower by absorbing it with a chemical solution called an amine solution.
  • The absorbed H₂S is separated from the amine solution in the absorption solution regeneration tower. The separated H₂S is burned then collected as gypsum in the flue gas desulfurization unit.
    *1:H₂S is hydrogen sulfide.  *2:COS is carbonyl sulfide.

Combined cycle power generation system

  • High efficiency power generation is achieved by utilizing combined cycle equipment, which integrates a 1,400°C-class gas turbine with a steam turbine, and seeks to save space by using a single-shaft design whereby the gas turbine, steam turbine, and generator are deployed around the same shaft.
  • It burns coal gas that has been cleaned in the gas purifier to rotate the gas turbine and generate power.
  • After combustion, the high-temperature exhaust gas is sent to the heat recovery steam generator (HRSG), which recovers the heat and generates steam to rotate the steam turbine and generate power.
  • Because steam is also recovered in the gasifier’s syngas cooler (SGC) heat exchanger, the steam turbine generates more power than natural gas combined cycle equipment. (The power output ratio between gas and steam turbines is about 3:2.)
  • The air required for gasification is extracted from the gas turbine’s air compressor, which reduces the power needed inside the plant.
  • Incorporating nitrogen oxide (NOx) removal equipment into the waste heat recovery boiler reduces the amount of NOx (nitrogen oxide) emitted.