養豬場使用沼氣微型渦輪發電機發電之實驗研究

Abstract

本計劃書在小型養豬場使用30kW沼氣微型渦輪發電機發電。第一部分，測試引擎在不同負載條件下的效能以及針對目標引擎的能量使用進行效率分析；第二部分，利用所量測的數據計算並分析，包括熱效率、甲烷消耗率等，進而分析及比較微渦輪機與四行程汽缸式引擎的發電效能，並利用本論文的數據估算在台中養豬場規模為3000、5000頭豬使用沼氣發電的經濟效益分析。 實驗結果顯示，隨著負載從15調整到30kw時，渦輪引擎的沼氣供給量從184.9上升至251.8L/min，渦輪發電機的最大發電功率、熱效率和甲烷消耗率分別為25.23kW、23.12%和168.7 L/min，而汽缸引擎的最大發電功率、熱效率和甲烷消耗率分別為26.48kW、26.37%和155.2 L/min。數據顯示汽缸引擎在高負載的情況下(發電功率21~30kW)有較高的熱效率相對於渦輪發電機，然而在低負載的情況下渦輪發電機能比汽缸引擎發電機提供較佳及穩定的發電功率，值得注意的是渦輪發機的額定發電功率最低限制為15kW. 利用上述兩台發電機的實驗數據來估算在台中養豬場規模為3000及5000頭豬其使用沼氣發電的經濟效益，其分析內容包括設備初設成本、維護成本、年發電量及投資回收期。在豬隻規模為3,000的情況下，估算出使用汽缸引擎發電有較佳的經濟效益，而在豬隻規模為5,000的情況下，由於渦輪引擎可24小時不間斷的提供電力輸出，相對於汽缸引擎則受構造因素因而不可長時間持續供電(一天至多20小時，超過易使引擎損壞)，故5000頭豬隻所提供的沼氣量足夠發電機進行持續性的發電時，使用渦輪引擎發電有較佳的經濟效益.

This proposal carries out the 30kW micro turbine generator experiments on small biogas plant in a swine farm. Firstly, the performance of turbine engine under various operating loads was tested, and the energy analysis for micro turbine engine was studied. Second, in this study, it conducted a series of comparison tests by using piston and turbine engines such as thermal efficiency, CH4 consumption rate. The economic benefits were also estimated by the data obtained with 3000-head and 5000-head pigs by this research. The experimental results showed that the range of biogas flow rate to the turbine engine is from 184.9 to 251.8L/min with 67% CH4 of biogas under varying loads from 15 to 30kW, and the maximum power generation, the corresponding thermal efficiency and the CH4 consumption rate is 25.23kW, 23.12% and 168.7 L/min, respectively. For piston engine, the maximum power generation, the corresponding thermal efficiency and the CH4 consumption rate is 26.48kW, 26.37% and 155.2L/min, respectively. The threshold efficiency of turbine engine is 2.97% lower. Compared with turbine engine, the fuel efficiency and thermal efficiency for piston engine is higher under the higher load operating range (21 to 30kW). However, the turbine engine can provide higher performance with lower efficiency variation compared to those of piston engine in range of 15~ 21 kW. Remind that the lower load limit is 15kW for this turbine engine, whereas piston engine still can be operated as low as 5.4kW. As to the economic benefits of using biogas, it estimated that a swine farm with a scale of 3,000 heads and 5,000 heads in Taiwan The economic analysis consists of equipment cost, annual power generation, the revenue of power generation, and the payback period. The results showed that using the piston engine to generate electricity in a scale of 3000 swine farm has an advantage over the turbine engine. However, the maximum operating time for piston engine is 20 hours a day in order to protect generator. The turbine engine can work around the clock. Therefore, if the biogas is enough to keep engine working incessantly, then the net electricity production for turbine engine will be greater than the piston engine in a scale of 5000 swine farm.