Steady-State Simulation and Optimization of an Integrated Gasification Combined Cycle Power Plant with CO₂ Capture

Abstract

Integrated gasification combined cycle (IGCC) plants are a promising technology option for power generation with carbon dioxide (CO2) capture in view of their efficiency and environmental advantages over conventional coal utilization technologies. This paper presents a three-phase, top-down, optimization-based approach for designing an IGCC plant with precombustion CO2 capture in a process simulator environment. In the first design phase, important global design decisions are made on the basis of plant-wide optimization studies with the aim of increasing IGCC thermal efficiency and thereby making better use of coal resources and reducing CO2 emissions. For the design of an IGCC plant with 90% CO2 capture, the optimal combination of the extent of carbon monoxide (CO) conversion in the water−gas shift (WGS) reactors and the extent of CO2 capture in the SELEXOL process, using dimethylether of polyethylene glycol as the solvent, is determined in the first phase. In the second design phase, the impact of local design decisions is explored considering the optimum values of the decision variables from the first phase as additional constraints. Two decisions are made focusing on the SELEXOL and Claus unit. In the third design phase, the operating conditions are optimized considering the optimum values of the decision variables from the first and second phases as additional constraints. The operational flexibility of the plant must be taken into account before taking final design decisions. Two studies on the operational flexibility of the WGS reactors and one study focusing on the operational flexibility of the sour water stripper (SWS) are presented. At the end of the first iteration, after executing all the phases once, the net plant efficiency (HHV basis) increases to 34.1% compared to 32.5% in a previously published study (DOE/NETL-2007/1281; National Energy Technology Laboratory, 2007). The study shows that the three-phase, top-down design approach presented is very useful and effective in a process simulator environment for improving efficiency and flexibility of IGCC power plants with CO2 capture. In addition, the study identifies a number of key design variables that has strong impact on the efficiency of an IGCC plant with CO2 capture.

More Energy-Efficient CO2 Capture from IGCC GE Flue Gases

“…The simple two-stage Selexol process was simulated by Robinson and Luyben [15]. Bhattacharyya et al [16] implemented a comprehensive process simulation of an entire IGCC power plant integrated with a dual-stage Selexol process for a 90% overall carbon capture efficiency with the performance as shown in Table 5. Table 5 shows the energy consumption of the process, as extracted from Kapetaki et al [13], as well as a comparison between the energy consumption of the dual-stage Selexol process and that of the cryogenic energy-saving scheme as described earlier in Table 4.…”

A survey on current advanced IGCC power plant technologies, sensors and control systems

“…Bhattacharyya et al developed a three-phase top-down approach to maximize the net power of an IGCC plant with CO 2 capture and to evaluate the operational flexibility of the water gas shift (WGS) reactors [52]. Those authors also carried out two optimization studies on optimal steam pressure in the waste heat boiler and H 2 S/SO 2 ratio to improve oxygen demand, hydrogen yield and power generation [53].…”

Process simulation of a dual-stage Selexol process for 95% carbon capture efficiency at an integrated gasification combined cycle power plant

“…The simple two-stage Selexol process was simulated by Robinson and Luyben (2010). Bhattacharyya et al (2011) implemented a comprehensive process simulation of an entire IGCC power plant integrated with a dual-stage Selexol process for 90% overall carbon capture efficiency. Padurean et al (2012) reported an Aspen Plus simulation on a dual-stage Selexol unit at 70%, 80% and 90% CO 2 capture rate.…”