Performance Simulation and Cost-Benefit Analysis of the Hydrogen Addition Effects on the Combined-Cycle Unit (Based on the Dah-Tarn Power Plant)

• Main Authors: Chin-Tsan HO, 何金燦
• Other Authors: Shenq-yang Shy
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/71984140760677938169

碩士 === 國立中央大學 === 機械工程研究所碩士在職專班 === 96 === This thesis attemps to establish a thermochemical model for the combined-cycle unit simulation based on the operation conditions of heat balance diagrams from the Taipower Dah-Tarn power plant. We use this model to analyze the effects of hydrogen-blended natural gases to the thermal efficiency of the combined-cycle unit, to the reduction of CO2 emission, and to the corresponding cost-benefit estimation. Since the peak value of adiabatic flame temperatures of hydrogen-blended natural gases can be shifted toward the leaner side of their equivalence ratios (φ) when the mole fraction of H2 to natural gas of such fuel increases, this can result in a higher turbine inlet temperature and thus a higher thermal efficiency. Therefore, the usage of H2 addition is useful for lean methane combustion (φ < 1). For instance, the thermal efficiency of the combined-cycle unit has a 21% increment with a 20.8% CO2 emission reduction, when the natural gas fuel at φ = 0.3 is blended with 10% H2. Compared to 2007 mean annual CO2 emissions of domestic power plants which are about 0.637 kg/(kW•hr), if 50% H2 is blended into the natural gas fuel, the mean CO2 emission can be reduced to 0.195 kg/(kW•hr) which is only 1/3 of the 2007 annual mean. Consequently, adding hydrogen can have an important advantage of reducing greenhouse gas emissions. The estimated cost of H2 produced from some renewable energy sources is aboutf 0.532 USD/m3 in the 2010 fiscal year for Taiwan. Taking an example of a combined-cycle unit using methane dopping with 10% H2 as a fuel, the net benefit per unit of electricity generation is 0.135 NTD/kW•hr with the consideration of CO2 and NOx reductions. Thus, the net benefit of using hydrogen additions is promising and deserves to invest in the near future.