直接結合上流式氣化爐與史特靈引擎之生質能發電系統

Direct Coupling of an Updraft Gasifier with a Stirling Engine to Produce Power From Solid Biomass Fuel

生質能源（biomass）是目前世界上被使用最多的再生能源之一，在未來的能源市場也佔有相當重要地位，大多生質能源具有能源密度低和分佈廣的特性，因此小型分散式生質能發電系統比一般大型集中式發電廠更具發展潛力，本研究發展一套直接結合改良型上流式固定床氣化爐（modified updraft fixed bed gasifier）與史特靈引擎（stirling engine）之小型分散式固態生質能發電系統。本改良型上流式固定床氣化爐主要是在氣化爐中的熱裂解區置入一內藏式燃燒管（embedded combustor）進行完全燃燒合成燃氣（syngas）而產生高溫且乾淨的排氣。氣化爐中的內藏式燃燒管則直接與史特靈引擎加熱端連結，並透過內藏式燃燒管內所產生的高溫排氣去加熱史特靈引擎的熱端，史特靈引擎因冷熱端的溫度差產生動力機械能，透過感應發電機（induction generator）自動地將機械能轉換成電能輸出。在本研究中，電能的輸出須仰賴熱能的輸入，而熱能輸入則與排氣的流量和溫度成正比。本研究的目的是直接結合本氣化爐與發電容量25 kW的史特靈引擎，以測試本平台的可行性，並量測本平台是否可達到史特靈引擎額定的電能輸出。

Biomass is the largest renewable energy source used in the world and its importance will grow only larger in the future energy market. Since most biomass sources are low in energy density and are widespread in space, small scale biomass conversion systems are therefore more competitive than a large stand-alone conversion plant. The current study proposes a small scale solid biomass powering system to explore the viability of the direct coupling of an updraft fixed bed gasifier with a Stirling engine. The modified updraft fixed bed gasifier employs an embedded combustor inside the gasifier to fully combust the syngas generated by the gasifier. The flue gas produced by the syngas combustion inside the combustion tube is piped directly to the heater head of the Stirling engine. The engine will then extract and convert the heat contained in the flue gas into electricity automatically. Output depends on heat input and the heat input is proportional to the flow rate and temperature of the flue gas. The preliminary study of the proposed direct coupling of an updraft gasifier with a 25 kW Stirling engine demonstrates that full power output can be produced by the current system. It was found, in the current investigation, that very little attention and no assisting fuel are required to operate the current system. The proposed system should be considered as a viable solid biomass powering technology.