廢咖啡渣（SCG）具備優良的特性，使其成為可用於生產生物炭來取代木炭的生質物。然而，未經處理的SCG水分含量高，且與煤炭相比熱值較低。乾燥和焙燒是兩個能夠提高SCG燃料特性的製程。但這兩個製程都消耗大量能源；因此，在這些過程中節能十分重要。本研究提出了兩種方法來增強SCG的燃料品質，並優化其生產過程。
在研究的第一部分中，透過以重量比1：0.75的比例混合SCG和過氧化氫（H2O2）的節能前處理方法，將焙燒SCG生物炭進行高位發熱值（HHV）的最大化。田口法優化的生物炭的最大HHV為30.33 MJ∙kg-1，相較於未經處理的SCG提高了46.9%，相較於未經H2O2前處理的SCG生物炭提高了6.5%。田口法建議使用18%的H2O2濃度以獲得最大化的HHV。為了評估H2O2前處理對HHV和碳含量的貢獻程度，本文採用了差異強度（IOD）指標。IOD隨著H2O2前處理溫度的升高而增加。在焙燒前，經50°C前處理的SCG的IOD值為1.94%，而經105°C前處理的SCG的IOD值為8.06%。這是因為在焙燒之前，H2O2前處理一定程度地削弱了SCG的分子結構，從而導致更高的IOD值。經105°C前處理的焙燒SCG（TSCG）的IOD值為10.71%，較經50°C前處理的IOD值增加了4.59%。這意味著，用H2O2在105°C前處理的TSCG具有更好的熱穩定性。總體而言，本研究發現H2O2是一種綠色且有潛力的前處理添加劑，可用於大幅提高SCG生物炭的燃值。
研究的第二部分有關於一種根據熱處理過程中的功耗來預測SCG水分含量並評估SCG 生物炭的HHV的新方法。結果發現，在焙燒過程中，HHV 的增加率緊隨功率消耗的減少，這現象可以用來確定樣品所需的前處理時間以減少不必要的能源損耗。本研究使用非支配排序遺傳算法 II (NSGA-II) 來最大化 SCG 生物炭的 HHV，同時最小化處理過程中的能量消耗。NSGA-II的優化結果表明，使用 244 °C 的焙燒溫度和 27 分鐘 43 秒的焙燒時間，能生產 23.98 MJ∙kg-1 的 SCG 生物炭，而過程將消耗20.042 MJ∙kg-1的能量。此生物炭每公斤能量產率為85.93%，估計能源投入成本為每公斤新台幣12.21元。

Spent coffee grounds (SCGs) possess rich qualities that make it a viable candidate to be used for biochar production to replace charcoal. However, untreated SCGs are high in moisture content and have a low calorific value compared to coal. To enhance the fuel properties of SCGs, drying and torrefaction could be performed. However, both processes are energy-intensive, and therefore, energy conservation during these processes is crucial. Two methods are devised in this study to enhance SCGs and to optimize its production processes.
In the first part of the study, an energy-saving biochar valorization strategy by mixing SCGs with hydrogen peroxide (H2O2) at a weight ratio of 1:0.75 to maximize the HHV of torrefied SCG biochar is developed. Maximized biochar’s HHV derived via the Taguchi method is 30.33 MJ∙kg-1, a 46.9% increase compared to the raw SCG, and a 6.5% increase compared to the unpretreated SCG biochar. The H2O2 concentration recommended by Taguchi is 18% for the maximized HHV. A quantitative identification index of intensity of difference (IOD) is adopted to evaluate the contributive level of H2O2 pretreatment in terms of the HHV and carbon content. IOD increases with increasing H2O2 pretreatment temperature. Before torrefaction, SCGs’ IOD pretreated at 50 °C is 1.94%, while that pretreated at 105 °C is 8.06%. This is because, before torrefaction, H2O2 pretreatment weakens SCGs’ molecular structure, resulting in a higher IOD value. The IOD value of torrefied SCGs (TSCG) pretreated at 105 °C is 10.71%, accounting for a 4.59% increase compared to that pretreated at 50 °C. This implies that TSCG pretreated by H2O2 at 105 °C has better thermal stability. Overall, it is demonstrated that H2O2 is a green and promising pretreatment additive for upgrading SCG biochar’s calorific value, and torrefied SCGs have the potential to be used as a solid fuel to approach carbon neutrality.
For the second part of the study, a new method to evaluate SCG biochars’ HHV and predict moisture content from power consumption is developed. It is found that during torrefaction, the increasing rates of HHV immediately follow decreases in power consumption, which could be used to determine the pretreatment time for energy conservation. The non-dominated sorting genetic algorithm II (NSGA-II) maximizes SCG biochar’s HHV while minimizing energy consumption. The results show that producing SCG biochar with 23.98 MJ∙kg-1 HHV requires 20.042 MJ∙kg-1, using a torrefaction temperature of 244 °C and torrefaction time of 27 min and 43 sec. Every kilogram of biochar with an energy yield of 85.93% is estimated to cost NT$ 12.21 in energy consumption.

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