Natural gas is expected to make up a significant proportion of the future global energy mix. Therefore, reducing greenhouse gas emissions from gas-fired processes is very essential for most countries, before emission reduction targets can be met. This article aims to carry out thermodynamic analysis of combined cycle gas turbine power plant with post-combustion CO 2 capture through modelling and simulation. The combined cycle gas turbine power plant and the CO 2 capture plant were simulated in Aspen Plus Õ . The combined cycle gas turbine power plant model was validated with simulation data from GateCycle Õ and the CO 2 capture plant model was validated with experimental data from the pilot plant at the University of Texas at Austin. The CO 2 capture plant was scaled up from pilot plant to commercial scale to process flue gas from a 250 MWe combined cycle gas turbine power plant. The integrated model for combined cycle gas turbine and CO 2 capture plant was further used for performance study. Exhaust gas recirculation has been proposed to increase CO 2 concentration in flue gas and reduce the flue gas flow rate. Its effect on combined cycle gas turbine power plant performance and capture plant sizing has been investigated. The analysis indicated that exhaust gas recirculation can reduce penalty on thermal efficiency without any major modification to the original power plant.

In this study, a combined cycle gas turbine (CCGT) power plant and a CO2 capture plant have been modeled in GateCycle ® and in Aspen Plus ® environments respectively. The capture plant model is validated with experimental data from the pilot plant at the University of Texas at Austin and then has been scaled up to meet the requirement of the 427 MWe CCGT power plant. A techno-economical evaluation study has been performed with the capture plant model integrated with flue gas pre-processing and CO2 compression sections. Sensitivity analysis was carried out to assess capture plant response to changes in key operating parameters and equipment design. The study indicates which parameters are the most relevant (namely absorber packing height and regenerator operating pressure) and how, with a proper choice of the operating conditions, both the energy requirement for solvent regeneration and the cost of electricity may be reduced.

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With increasing urgency for global action toward climate change mitigation, this study is undertaken to evaluate integration options for post-combustion CO 2 capture (PCC) on gas-fired power plants. High-fidelity models of a natural gas combined cycle power plant, a PCC plant, and a CO 2 compression train are integrated for a 90% CO 2 capture level. Three options to provide steam for solvent regeneration are explored: extracting steam from the intermediate-pressure (IP)/lowpressure (LP) crossover, using a gas-fired package boiler, and extracting steam from the LP drum. The effect of pressure losses because of steam extraction, a factor ignored in previous analyses, is also considered. The integrated plant net efficiency is 47.8, 40.4, and 44.9%, respectively, for the aforementioned scenarios. Next, supplementary firing of gas turbine exhaust is employed to generate an ample amount of steam to preserve plant net output under a sliding pressure scenario and meet solvent regeneration requirements. It is observed that the net plant efficiency converges to a value of 43.5% for the options considered.

This paper focuses on the relationship between the working fluid composition and the turbomachinery performance, notably on the case of flue gas recirculation. This aspect has been investigated by means of a semi-empirical radial equilibrium code for axial flow turbomachinery analysis. The mathematical model of the code, already described in previous works by the authors, is based on the assumption of steady, adiabatic and axisymmetric flow and, in this paper, has been extended to take into account the gas composition. The performance of an 1.5 stages axial-flow compressor and of a 4 stages turbine has been investigated under various working fluid compositions as expected from cycles with flue gas recirculation and the obtained results, which have been found to be consistent with those of a commercially available CFD code, have been compared with those which could be obtained with a traditional cycle working fluid composition. This analysis has allowed to prove how this modification of the working fluid composition through the turbomachinery leads to very small performance alterations.