Integrated Gasification Combined Cycle
Lee Layton, P.E.
This course begins with an in-depth look at the coal industry in the United States including the types of coal, the location of coal reserves, and the advantages and disadvantages to each of the types of coal.
After a thorough review of coal, the course delves into how gasifiers create a “syngas” from coal. Next, we look at the types of power plants that can be used with syngas, specifically, a combined cycle power plant.
Finally, we put it all together and discuss entire process of an IGCC power plant from the coal hopper to the gasifier, gas cleaning processes, scrubbing, and power production.
This course includes a multiple-choice quiz at the end, which is designed to enhance the understanding of the course materials.
After taking this course you should,
This course is intended for electrical and mechanical engineers as well as anyone who wants to understand how an Integrated Gasification Combined Cycle power plant works and role in the new energy economy.
Benefit to Attendees
By taking this course, the reader will understand how an IGCC power plant operates and how it may be part of the new energy economy as we move away from traditional coal-fired power plants.
Integrated gasification combined-cycle (IGCC) systems combine a coal gasification unit with a gas fired combined cycle power generation unit. The first stage is a coal gasification process. The second stage takes the cleaned gas and burns it in a conventional combustion turbine to produce electrical energy, and the hot exhaust gas is recovered and used to boil water, creating steam for a steam turbine which also produces electrical energy. In typical plants, about 65% of the electrical energy is produced by the combustion turbine and 35% by the steam turbine.
An integrated gasification combined cycle (IGCC) is a power plant that uses synthetic gas as its fuel source. The synthetic gas, also known as syngas, is used to power a combustion turbine generator whose waste heat is then used to power a steam turbine. The gasification process can use coal, heavy petroleum residues, or biomass as the feedstock.
An integrated coal gasification combined cycle power plant is the most environmentally friendly coal-fired power generation plant available today. The plants can generate electric power with very little greenhouse gas emissions.
Coal gasification is the process of converting coal to a gaseous fuel through partial oxidation. The coal is fed into a high-temperature pressurized container along with steam and a limited amount of oxygen to produce a gas. The gas is consists mainly of carbon monoxide and hydrogen. The gas is cooled and undesirable components, such as carbon dioxide and sulphur are removed.
By removing the emission-forming constituents from the syngas under pressure before combustion in the power block, an IGCC power plant produces very low levels of air pollutants (NOx, SO2, and PM) and volatile mercury.
IGCC uses a combined cycle format with a combustion turbine driven by the combusted syngas, while the exhaust gases are heat exchanged with water/steam to generate superheated steam to drive a steam turbine. Using IGCC, more of the power comes from the combustion turbine. Typically 60-70% of the power comes from the combustion turbine with IGCC, compared with about 20% using pressurized fluidized bed combustion (PFBC.)
IGCC will compete directly against other clean coal technologies such as the supercritical pulverized coal (SCPC) design. Presently, IGCC plants cost 20 to 25 percent more than a comparable SCPC power plant at any given site.
This course content is in the following PDF document:
Combining a coal gasification plant with a combined cycle power plant has the potential to provide an environmentally friendly method to continue to use coal as a generation fuel source.
IGCC plants hold the promise of high thermal efficiency, but they have not delivered on the promised efficiencies. However, in spite of the lower than expected efficiencies, the environmental benefits of IGCC may make it the choice for future coal-fired power plants.