養豬場環境溫度對30kW沼氣渦輪發電機發電影響之實驗研究

Abstract

本論文在台中月眉台糖養豬場測試30 kW沼氣微型渦輪發電機，使用處理後之不同濃度甲烷濃度之沼氣進行實驗，分析不同環境溫度和功率負載對發電機的性能影響。研究計畫第一部分，使用實驗數據並且利用Brayton cycle與組件之實際效率計算發電機之性能。結果顯示發電機之發電功率為31.54 kW、熱效率為25.62 %。第二部分在不同環境溫度下，測試不同負載(15~30 kW)之發電機效能變化，利用量測的數據分析發電功率和熱效率。結果顯示當環境溫度從21.8 oC上升至31.4oC，發電功率和熱效率分別下降9.6%和2.9%，且在發電機未到達引擎最大轉速額定功率24 kW下，甲烷質量流率從0.1284增加至0.152 kg/min，顯示沼氣濃度不影響發電功率。第三部分，與國外研究之實驗數據作比較，探討不同燃料對CR30之性能影響。結果顯示發電機使用沼氣之淨輸出功率高於丙烷，但是使用沼氣之熱效率會低於丙烷。淨輸出功率和熱效率之最大差異分別為1.02kW和3.8%。最後，估計渦輪發電機沼氣發電之經濟效益，在5,000頭和20,000豬隻規模豬場使用渦輪發電機每年之發電量分別為165,200 kWh和826,000 kWh、減碳量分別為725噸和3,600噸。

This research carried out the 30 kW micro-gas turbine engine (CR30) experiments using biogas in a swine farm in Taichung. The experiment used different concentrations of methane in desulfurized biogas to investigate the ambient temperature and workload effects on MGT. Firstly, the theoretical calculations were analyzed by use of Brayton cycle assumption with actual component efficiencies and experimental data as inputs. The results showed that the calculated generator power output and calculated thermal efficiency are 31.54kW and 25.62%, respectively. Secondly, under various workloads (15~30kW), the ambient temperature effects on performance of MGT are investigated. When the ambient temperature increases from 21.8 oC to 31.4 oC, the net power output and thermal efficiency decrease 9.6% and 2.9%, respectively. Besides, when MGT does not reach the maximum engine speed (~96,000 rpm), the methane mass flow rate increases from 0.128 to 0.152 kg/min at 24 kW of rated power output, indicating that CH4 concentration in biogas does not affect the net power output. Thirdly, the comparisons with other researches were made for analyzing the effect by different fuels using CR30. By using biogas, it was found that the net power outputs are larger but the thermal efficiencies are lower than those by using propane. The maximum discrepancies of net power output and thermal efficiency are 1.02 kW and 3.8%, respectively. Finally, the economic benefits of MGT are estimated. The 5,000-pig and 20,000-pig swine farms can generate 165,200 kWh and 826,000 kWh of electricity per year and decrease 725 tons and 3,600 tons of CO2 per year, respectively.