本研究利用台電大潭複循環發電機組之熱平衡圖運轉條件，建立複循環機組加氫之熱力化學模擬模式，以此模式來模擬分析甲烷燃料加氫效應對複循環機組熱效率及CO2排放之影響，並評估加氫之成本效益。當甲烷加氫比率逐漸增加時，絕熱火燄溫度隨當量比(equivalence ratio,φ)變化之分佈曲線會往貧油遞減方向移動。由於絕熱火燄溫度決定氣渦輪機進口溫度，而氣渦輪機進口溫度越高，機組熱效率越高。因此以甲烷加氫當複循環機組之燃料，有助於在貧油條件下較低φ值時(φ < 1)，提供較高之火燄溫度，利於提升機組熱效率。以φ = 0.3加氫比率為10%為例，機組熱效率提升幅度可達21%，而機組CO2排放量減少幅度可達20.8%。相較於96年度國內電力設施CO2排放量平均值0.637kg/kW•hr，當複循環機組加氫比率達50%時，其CO2排放量為0.195kg/kW•hr，僅國內電力設施CO2排放量平均值之30.6%，可有效減少溫室氣體排放。以未加氫的複循環機組之燃料成本為基準，與加氫比率為10%的機組作比較，若納入CO2及NOx減量效益，以及我國（2010年）再生能源生產氫氣預估成本0.532 USD/m3，加氫燃料之成本淨效益為0.135 NTD/kW•hr，淨效益大於零具有投資價值。 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.
