Efficiency Analysis of Gas Turbine Combined-Cycle Fed with Synthetic Natural Gas (SNG) and Mixture of Syngas and SNG

• Published in: Key Engineering Materials 2015-07, Vol.656-657, p.113-118
• Main Authors: Chen, Po Chuang, Chyou, Yau Pin, Wang, Ting, Chiu, Hsiu Mei
• Format: Article
• Language: English
• Subjects: Benchmarking; Climate change; Coal; Computer simulation; Construction; Efficiency; Electricity generation; Fossil fuels; Gas turbines; Industrial plant emissions; Natural gas; Power plants; Raw materials; Simulation; Synthesis gas; Synthetic fuels; Turbines
• ISSN: 1013-9826; 1662-9795; 1662-9795
• DOI: 10.4028/www.scientific.net/KEM.656-657.113

The effect of synthetic natural gas (SNG) and mixture of syngas and SNG fed to Natural Gas Combined-Cycle (NGCC) plants is presented in this study via a system-level simulation model. The commercial chemical process simulator, Pro/II® V8.1.1, was used in the study to build the analysis model. The NGCC plant consists of gas turbine (GT), heat recovery steam generator (HRSG) and steam turbine (ST). The study envisages two analyses as the basic and feasibility cases. The former is the benchmark case which is verified by the reference data with the GE 7FB gas turbine. According to vendor’s specification, the typical net plant efficiency of GE 7FB NGCC with two gas turbines to one steam turbine is 57.5% (LHV), and the efficiency is the benchmark in the simulation model built in the study. The latter introduces a feasibility study with actual parameters in Taiwan. The SNG-fed GE 7FB based combined-cycle is evaluated, and the mixture of SNG and syngas is also evaluated to compare the difference of overall performance between the two cases. The maximum ratio of syngas to SNG is 0.14 due to the constraint for keeping the composition of methane at a value of 80 mol%, to meet the minimum requirement of NG in Taiwan. The results show that the efficiency in either case of SNG or mixture of SNG and syngas is slightly lower than the counterpart in the benchmark one. Because the price of natural gas is much higher than that of coal, it results in higher idle capacity of NGCC. The advantage of adopting SNG in Taiwan is that it could increase the capacity factor of combined-cycles in Taiwan. The study shows a possible way to use coal and reduce the CO2 emission, since coal provides nearly half of the electricity generation in Taiwan in recent years.