天然氣汽電共生電廠之操作模擬與經濟評估

Abstract

本研究依據台灣發電系統之現況，對以天然氣為燃料之複循環發電系統進行模擬以及熱力學與經濟分析。本研究應用工程軟體Aspen Plus對系統進行穩態模擬，其中包含氣渦輪機、蒸汽發電系統以及煙道氣循環系統。接著，本研究透過調整壓縮機進料的壓力以及氣渦輪機進料溫度與煙道氣循環流量比例、蒸汽渦輪機進料的溫度等重要操作變數進行熱力學分析。在系統模擬中，本研究以1 kg/s 的天然氣流量為基礎，調整不同的配置，發現在不同的熱力學條件下，其總發電功率可以約可達到29 MW至31 MW，蒸汽發電系統所輸出的熱能評估標準為蒸汽的流量，研究結果顯示提高其渦輪機進料之溫度可以有效提高整體的發電效率。另外，本研究以總發電功率500 MW為基準，對系統進行經濟分析。根據經濟分析的結果，複循環蒸汽與發電共生系統是一個能源效率高且利潤較高的系統。

Abstract The present study focuses on the simulation of a power plant with thermodynamic and economic analysis of a natural gas (NG) based combined heat and power plant from a Taiwanese perspective. The simulation of the power plant was done using the Aspen Plus software, which consists of an integrated gas turbine, a heat generation cycle (in terms of steam), and a flue gas recirculation stream. The thermodynamic analysis is done by varying the compressor inlet pressure and gas turbines’ inlet temperature to the flue gas recirculation ratio and the steam turbines’ inlet pressure. The simulations studied for the various configurations was done on the basis of 1kg/s of NG, and showed a power output of about 29 MW to 31 MW being generated under different thermodynamic conditions. The combined heat and power cycles’ output is measured in terms of thermal energy output, i.e., steam flow rate. It is observed that the higher the gas turbine inlet temperature, the higher the overall efficiency. The economic analysis was carried out based on a 500 MW power capacity for each configuration. Based on the economic analysis, the final results show that the combined heat and power process is both more profitable and highly efficient.