Operation methods of rapid load changes for integrated coal gasification combined cycle power plants

Abstract

The IGCC (integrated gasification combined cycle) is emerging as one of the most advanced and effective systems for electric energy generation. The IGCC consists of pressure vessels such as a gasifier, syngas cooler and gas cleanup unit with the large time constants, so dynamic response of the power plant is delayed. On the other hand, the fluctuating power generation of renewable energies creates the need for flexible operations (e.g. fast start-up and rapid load change) of thermal power plants including IGCC power plants. This paper describes: (1) two new control methods for IGCC power plants that are combined as the proposed control method to reduce the gasifier pressure rise when rapid load changes are required; and (2) a plant-wide dynamic simulation to consider the operability and controllability of the plants. Simulation results showed the gasifier pressure rise rate was reduced from 7.4% to 3.6% due to the new proposed control method, recycle gas flow rate and steam flow rate control, with load change from 100% to 65% at 20%/min. In the case of 15%/min load change, the gasifier pressure rise rate was 2.8% and less than the maximum permissible value of 3.0%.

Keywords

• igcc
• dynamic simulation
• load change
• gasifier pressure