IGCC plants have two sources of power generation – a combustion turbine-generator and a steam turbine-generator. The process combines fuel feed stocks – typically coal or petroleum coke – together with oxygen to form a low BTU synthesis gas. A combustion turbine-generator burns the gas and generates power. Heat from the gasification process and exhaust from the combustion turbine-generator create steam to power a steam turbine-generator that also generates power.

The process begins with an air separation unit that splits ambient air into oxygen and nitrogen. The gasifier uses 96% of the oxygen stream, and the sulfur recovery process consumes the remaining 4%. The nitrogen expands through the turbine to increase power production and reduce NOx emissions.

Coal or petroleum coke is blended, pulverized, and mixed with water to produce a 62-68% coal/water slurry. The slurry is injected with oxygen at high pressure (375 psi) into the gasifier. Partial oxidation of the coal produces 2400-2700°F temperatures and transforms the slurry into steam.

The combination of heat, pressure, and steam breaks down the feedstock and creates chemical reactions that produce a hydrogen (H2) carbon monoxide (CO) synthesis gas, or syngas. The process also yields marketable elemental sulfur extracted from the coal. Feedstock minerals become an inert, glassy slag product used in road beds, landfill cover, and other applications.

The raw syngas passes through a series of coolers to reduce the temperature and produce high-pressure steam. The recovered heat preheats clean syngas and boiler feed water. Gas stream impurities including mercury (Hg) are removed. The radiant syngas cooler and syngas scrubbers remove fly ash from the gas stream. A portion of fly ash containing up to 30% carbon recycles to the slurry preparation. Carbon dioxide (CO₂) can be separated and processed for commercial use or captured for long term sequestration.

Enclosed IGCC storage facilities eliminate typical pollution from coal pile runoff, dust from coal piles, noise from coal moving equipment, and fire potential. The enclosed conveyor systems move and store the fuel as slurry in tanks or in coal storage enclosures adding to the environmental protection features of the plant.