【S015】 淨零碳排新興能源科技論壇

Thursday, 18 November, 14:30 ~ 16:00, Conference Room ROOM 7
Organizer: Shu-San Shiau, Shou-Yin Yang
Chair: 吳耿東


14:30 ~ 14:45 (15')
0063  Development of an oblique-impinging jet biochar-firing combustor
Hsiao-Kai (孝凱) Kan (干), Dean (鼎贏) Chou(周) and Yueh-Heng (約亨) Li (李)
To improve the combustion efficiency, two oblique-impinging flames were designed and employed to burn biochar in a more clean and stable way. The proposed oblique-impinging jet burner consists of two oblique jet burners and one slot jet burner. The oblique jet burner with a specific deflection angle was employed with a stoichiometric methane/air flame to generate the inner circulation zone. The slot jet burner placed in the center was used to deliver biochars derived from empty fruit bunch (EFB). Two premixed impinging flames would construct two flow structures, that is, an impinging jet zone and an inner recirculation zone. The incoming biochar particle would veer toward the inner circulation and trap inside the recirculation zone. Consequently, the biochar would encounter the devolatilization process and yield the resulting combustible gases, such as hydrogen, methane, and carbon monoxide. Eventually, the shrank biochar particle would be delivered towards the downstream impinging jet flame and then burn out. Theoretically, the proposed oblique-impinging jet burner can achieve clean and stable biochar-firing combustion.
To scrutinize the combustion characteristic of the proposed oblique-impinging burner, some parameters are examined in terms of the deflection angle (30°, 45°, 60°) of the oblique-impinging jet nozzle, the distance of two oblique-impinging nozzles, and delivering flowrate of biochar. In the experiment, particle imaging velocimetry (PIV) was employed to investigate the flow structure of the proposed burner, and two-color pyrometry was used to measure the surface temperature of biochar. Moreover, the soot volume of the biochar combustion was also measured by laser-induced incandescence (LII).

14:45 ~ 15:00 (15')
0243  碳纖維複材應用於集電板之燃料電池模組設計與應用
Chong-Kai Wang and Yean-Der Kuan
近年來隨著綠能產業的發展,燃料電池也越來越受到重視,而傳統燃料電池利用石墨或是金屬做為雙極板/集電板。石墨極板雖然其材料特性導電性佳、耐腐蝕性好,卻有著加工不易且易碎之缺點;金屬極板具有導電性好、延展性佳且易加工之特性,但其抗腐蝕性差而造成其使用上的限制。碳纖維複合材料為近幾年的新興材料,其具有機械強度高以及耐腐蝕等特性,其水平方向導電性佳,但垂直方向導電性較差,可以透過一些改良方式來增加其導電性,如添加導電顆粒、碳化等。本研究使用碳纖維複合材料製作質子交換膜燃料電池之集電板,利用碳纖維複合材料的特性以增加燃料電池中集電板的使用年限,並針對製作出的碳纖維集電板進行物理性質以及性能探討。後續將組成平面式2cell電池堆,進行發電測試。
本研究先進行碳纖維複合材料板的製作,將碳纖維平紋布、酚醛樹脂與鱗片石墨粉依比例秤重。運用均質機將酚醛樹脂混合鱗片石墨粉並添加甲醇以便於混合。使用刮刀將混合均勻的溶液均勻塗佈於碳纖維布上,靜置溶劑揮發後,將製作好的預浸布進行裁切,層層堆疊並用滾輪將層與層之間的氣泡擠出。將堆疊完的預浸布裝入模具中,放入熱壓機中進行熱壓,熱壓溫度設定150℃,熱壓壓力設定150kg/cm2,熱壓時間30min,熱壓完成後即可獲得碳纖維複合材料板。使用CNC雕铣機雕刻碳纖維集電板之幾何形狀。對於碳纖維複合材料板進行特性測試,分別進行面電阻量測、機械強度測試、腐蝕性測試以及SEM觀測。將碳纖維集電板組裝成單電池進行性能測試,後續將電池堆疊成平面式2cell進行性能測試。運用熱壓製程組合平面式2cell,其目的為減輕螺絲等重量,以達到輕量化之目的。最後結合小型儲氫瓶製成小型發電裝置,並運用風扇以及LED燈進行發電測試。
本研究於面電阻量測中發現隨著碳化次數增加,碳纖維集電板之面電阻值隨之降低。在機械強度的部分,未碳化之碳纖維試片三點彎曲強度平均值為469.7MPa、碳化一次為67.5MPa、碳化兩次為38.7MPa,隨著碳化次數增加,碳纖維之機械強度隨之降低。於單電池性能測試中,封閉式單電池使用燃料電池測試平台進行測試,以定電壓給與負載,氫氣流量300sccm,氧氣流量600sccm,氣體加濕並加溫至50℃,封閉式單電池最高可輸出82 mW/cm2。而開放式之陰極端自然對流,開放式單電池可輸出33 mW/cm2。於平面式2cell電池堆性能測試中,使用燃料電池測試平台進行測試,以定電壓給與負載,氫氣流量600sccm,氧氣流量1200sccm,氣體加濕並加溫至50℃,電池最高可輸出178 mW/cm2。而開放式之陰極端自然對流,開放式2cell最高可輸出84 mW/cm2。
本研究利用碳化來移除碳纖維複合材料板中的酚醛樹脂,由測試結果可得知,碳化能有效移除樹脂,隨著碳化次數增加,碳纖維複材集電板之面電阻隨之降低,電池性能也有所提升。然而碳化會降低碳纖維複合材料的機械強度,根據本研究之機械強度測試,其機械強度均符合美國能源局(DOE)所訂定之標準。本研究成功製作平面式2cell電池堆,進行熱壓時間測試,成功運用熱壓製程組合成2cell電池模組。於發電測試中,成功使風扇運轉以及LED燈發光。

15:00 ~ 15:15 (15')
0132  多階旋風式純氧煅燒系統負壓操作對煅燒效率之影響
書懷 張, 宗錡 李, 恆文 徐 and 啟雯 廖
多階旋風式純氧煅燒系統,是由純氧燃燒爐、上升導管、旋風煅燒塔、高溫風車、石粉進料系統、煙氣回流系統等單元所組成。於此系統下對石灰石進行純氧煅燒並產生高濃度的二氧化碳,以作為後續再利用及封存應用。本系統煅燒後產生之高溫回流煙氣將送回系統,可有效的提升熱的利用效率,並以負壓進行運轉,可有利於減少系統粉體堵塞的問題,提升未來系統放大之商業化競爭力。然而現行多階旋風式純氧煅燒系統進行負壓操作有兩個難題必須克服,其一為回流量無法控制導致系統仍為正壓;其二為負壓運轉系統風量不足,使燃燒室送熱能力較差,導致後端上升管溫度無法達到850℃以上,使石灰石煅燒效率偏低;亦可能使得燃燒室因蓄熱溫度過高而燒熔,使系統無法進行長時間運轉。
本研究以500kWt鈣迴路試驗廠煅燒系統來進行測試,藉由調整風車及風管配置,使系統可執行全負壓運轉,並增大系統風量,讓純氧煅燒可維持一定的送熱能力,並提升石灰石煅燒效率。評估內容包含在不同風車配置條件下,使用熱電偶及壓力計量測各單元溫度、靜壓分佈,以確認系統在負壓操作之熱流分佈。並在柴油、氧氣、風車轉速等不同條件下,取樣煅燒後的石灰石,以燒失重量方法測所對應的煅燒效率。
研究結果顯示,系統經由調整工程後,整體之風量明顯提升,煅燒系統可實現全負壓操作,而運轉的安全性及穩定性亦獲得提升。且負壓操作下,燃燒室送熱能力明顯增強,亦提升整體之溫度及石灰石的煅燒效率。未來將繼續進行系統優化及運轉經驗累積,以取得放大參數推動系統大型化應用。

15:15 ~ 15:30 (15')
0196  轉爐石於流體化床化學迴路系統反應研究
Cetera Chen and Seng-Rung Wu
本研究目的為開發流體化床化學迴路產熱技術,藉由以煉鋼廠之轉爐石為載氧體來降低系統操作成本,而系統所產出的熱能可提供給煉鋼廠作為製程所需的能源。實驗測試先以所建立的單流體化床流化反應測試設備量測轉爐石的最小流體化速度為3.6cm/s。接著,再於測試設備上進行甲烷反應現象觀察,結果顯示轉爐石載氧體在甲烷濃度5%與10%時,還原反應的甲烷轉化率均約為71%,而提高甲烷濃度至15%,甲烷轉化率可提高至79%。另外,實驗觀察亦顯示,床砂高度對反應器直徑比例(h/D)由為5降至2,雖可降低氣流的壓力損失,但也降低氣體燃料於床砂內的滯留時間,對於甲烷轉化率有負面的影響,甲烷轉化率由71.7%減少至53.3%。本研究對於甲烷與轉爐石流化反應的影響參數分析可做為交聯式流體化床化學迴路系統的設計與操作參考依據。

15:30 ~ 15:45 (15')
0035  Biochar’s Role for Negative Carbon Emissions in Agriculture and Forestry Circular Economy in Taiwan
Keng-Tung Wu and Chia-Ju Tsai
According to the definition by International Biochar Initiative (IBI), biochar is a carbonized solid biomass production by carbonization of solid biomass feedstock. Biochar can be used not only as solid fuels, but also as soil amendment materials with carbon sequestration. In agricultural applications, due to the porous structure and high specific surface area itself, biochar mixed with the soil can decrease the soil bulk density, increase the soil porosity, and improve aeration and water holding capacity (WHC) of soil. It may be used as a refuge for colonizing fungi and bacteria. If the carbon sequestration is through biomass energy, the net carbon withdrawal from the atmosphere is 0%, i.e., the net CO2 emission is zero. If the biochar is mixed with the soil, net carbon withdrawal from the atmosphere is about 20%.

In Taiwan, according to our investigation, except for the municipal wastes and general industrial wastes, the dry agriculture and forest solid residues were estimated at 636,297 t/yr in 2019. It would be a large resource for making biochar. In addition, producing and utilizing biochar can accelerate the formation of Taiwanese agriculture and forestry circular economy. To assist the potential manufacturers in establishing the biochar industry, and promoting the application of biochar, a 100 kg/hr (feeding rate) multiple hearth furnace (MHF) with a continuous feeding system for mass production of biochar was established at National Chung Hsing University, Taichung, Taiwan. The requirements of this pilot scale biochar production system focused on (1) mass production of biochar; (2) recovery of liquid byproducts (e.g., vinegar) for agricultural utilization; (3) good quality of biochar based on the pore diameter by controlling the carbonization temperatures; and (4) flue gas emissions that meet the environmental standards. The preliminary results show that feeding 100 kg/hr of the mixed wood pellet (from pruning street trees) into the furnace can generate about 20 kg/hr biochar under the operating temperature at 600oC. The byproduct of vinegar is about 0.06 L/L/hr, and can be diluted to 100 ppm for agricultural utilization. The property of produced biochar met the European Biochar Certificate (EBC Std.). The flue gas emissions also met the Taiwanese Stationary Pollution Source Air Pollutant Emissions Standards. Moreover, the net carbon withdrawal from the atmosphere is 17.02% by using biochar produced from the above MHF system.

In conclusion, we believe that through the performance of the pilot scale biochar production system, the Taiwanese agriculture and forestry circular economy would be established promptly and successfully.

Financial support of this work by the Council of Agriculture of the Executive Yuan, Taiwan (Grant No. 110AS-17. 1.2-ST-a4) is gratefully acknowledged.

15:45 ~ 16:00 (15')
0075  Experimental and modeling investigations of the air-sand flow behaviors in a dual fluidized bed cold flow system
Cong-Binh Dinh, Shu-San Hsiau, Chien-Yuan Su, Yi-Shun Chen and Hou-Peng Wan
“Research motivation” of this research is to study the unsteady characteristics of the air-silica sand flow in a lab-scale dual fluidized bed gasification cold flow system and investigate the influences of crucial parameters on the system hydrodynamics. “Research method” is to develop a two-dimensional computational fluid dynamics full-loop model with poly-size distribution in solid phases and carry out the corresponding experiments for validating the simulation results. The “Results” indicate that the mixture static pressure decreases from the bottom to the upper regions of the system, which maintains the system operations stable. The riser air inlet velocity and the gasifier static bed height are found to play significant roles in enhancing the total sand flow rates. In addition, the same tendencies in the prediction and experiment of both the mixture pressure and the sand flow rate show the feasibility of the proposed model. Moreover, undesirable phenomena possibly occurring in the system operation under improper conditions can also be predicted. It is noted in the “Conclusion” that the inventory of bed material and the fluidizing gas flow rates should be suitably regulated to maintain pressure balances, trouble-free continuous flow, optimal sand circulation rate, and low solids loss. The obtained results of this study can be further used as a reference for optimizing the designs and operational conditions of large-scale plants.