(327d) Optimization Studies of An Integrated Gasification Combined Cycle (IGCC) Plant with CO2 Capture

Authors: 
Bhattacharyya, D., West Virginia University
Turton, R., West Virginia University
Zitney, S. E., National Energy Technology Laboratory, U.S. Department of Energy


Integrated Gasification Combined Cycle (IGCC) plants with CO2 capture have a strong potential to be the leading technology in view of its numerous advantages over other commercially available technologies. However, its energy efficiency should be improved to make these plants commercially viable. To improve its energy efficiency, a systematic, top-down, design approach is taken considering commercially available technologies. In this three stage approach, first important global design decisions are made based on optimization studies. This is followed by taking optimum local design decisions. At the end, the operating conditions are optimized. The operability of the plant is taken into account before taking final design decisions. The IGCC reference plant includes an entrained, downflow, General Electric Energy (GEE) gasifier with a radiant syngas cooler (RSC), a two-stage water gas shift (WGS) conversion process, and two advanced ?F? class combustion turbines partially integrated with an elevated-pressure air separation unit (ASU). A subcritical steam cycle is considered for heat recovery steam generation. Syngas is selectively cleaned by a SELEXOL acid gas removal (AGR) process. Sulfur is recovered using a two-train Claus unit with tail gas recycle to the AGR. A multistage intercooled compressor is used for compressing CO2 to the pressure required for sequestration. A number of important global design decisions are identified that have strong impact on system performance. As an example of a global design decision, the optimum combination of CO conversion in the WGS reactors and CO2 capture in the SELEXOL unit is considered. An optimal design decision results in about 1.2% increase in the net plant efficiency (HHV basis) compared to a previously published study by NETL1. Further improvement in the plant efficiency is achieved by optimizing local design decisions and operating conditions.

1 Cost and Performance Baseline for Fossil Energy Power Plants Study, Volume 1: Bituminous Coal and Natural Gas to Electricity,? National Energy Technology Laboratory, www.netl.doe.gov, August 2007