- 學位論文
添加物及蒸汽對電漿熱處理生質廢棄物之影響
The Effect of the Plasma Torch System to Treat the Bio-mass Wastes with Additives and Steam
摘要
本研究以電漿火炬 (plasma torch, PT) 為熱源處理生質廢棄物，而以葵花籽渣 (sunflower-oil cake) 作為目標物，進行添加物的影響及更深入的應用可行性之探討，最終期望能獲得高產率的合成氣 (syngas)，達廢棄物資源再利用。 本研究所用之添加物為碳酸鉀 (K2CO3) 及氧化鋅 (ZnO)，目標溫度為973 K，針對氮氣電漿與蒸汽電漿作產物分析比較。研究發現，在氮氣電漿系統 (N-PT)中，若不計氮氣、水氣、二氧化碳及氮氧化物，未添加添加物時，其產氣中CO、H2及CH4之體積百分率(重量百分率) 分別為29.77 vol.% (84.29 wt.%)、69.25 vol.% (14 wt.%) 及0.93 vol.% (1.51 wt.%)。於N-PT中添加碳酸鉀 (NK-PT) 會增加CO及CH4的產氣體積比例，最高為添加5 wt.% 時，其CO、H2及CH4分別為44.88 vol.% (79.07 wt.%)、39.29 vol.% (4.94 wt.%)及18.8 vol.% (15.9 wt.%)。於N-PT中添加氧化鋅 (NZ-PT) 則對CO、H2及CH4的產氣比例較無影響，例如添加5 wt.%時，CO、H2及CH4之產氣比例分別為28.6 vol.% (83.53 wt.%)、70.4 vol.% (14.7 wt.%)及 0.95 vol.% (1.58 wt.%)。 在蒸汽電漿系統 (S-PT) 中，同樣不計氮氣、水氣、二氧化碳及氮氧化物，於973 K未加入添加物時，CO、H2及CH4的產氣比例分別為7.16 vol.% (41.22wt.%)、85.7 vol.% (35.22 wt.%)及7.11 vol.% (23.39 wt.%)。此S-PT與單純氮氣電漿 (N-PT) 相比，可知加入蒸汽可增加H2及CH4的產氣體積比例，其效果明顯。此S-PT再與NK-PT相比，其H2產氣體積比例亦較高。若考慮添加物對蒸汽電漿的影響，由實驗成果知，加入碳酸鉀 (SK-PT) 及氧化鋅 (SZ-PT) 時會稍稍增加H2的產氣體積比例。最佳比例為加入5 wt.% 的碳酸鉀時，SK-PT之CO、H2及CH4產氣比例分別為6.54 vol.% (42.57 wt.%)、89.25 vol.% (41.49 wt.%) 及4.17 vol.% (15.51 wt.%)。於S-PT中加入5 wt.% 的氧化鋅時，SZ-PT之CO、H2及CH4之產氣比例分別為4.56 vol.% (31.31 wt.%)、89.22 vol.% (43.8 wt.%) 及6.13 vol.% (24.09 wt.%)。SZ-PT與SK-PT相比較，其CH4產氣體積比例較高。 綜合而言：1) 添加K2CO3於N-PT中可促進生質物裂解為CO及CH4；2) 通入蒸汽於PT中可提升H2及CH4的產氣體積比例；3) 添加K2CO3及ZnO於S-PT中，可再提升S-PT之H2的產氣體積比例；4) SK-PT及SZ-PT提升H2產氣體積比例相近，約為89.2 vol.%，但SZ-PT仍可維持約6.13 vol.%之CH4，略優於SK-PT之4.17 vol.% CH4。 生質廢棄物屬於生質能源之一部分，適當處理以回收能源及資源是達成零廢棄全循環目標很重要的途徑之一，且將生質廢棄物資源能源化具有永續性、能源生產、以及同時處理廢棄物造成之環境問題等優勢，其能源生產與消費之政策影響亦將相當廣泛。
並列摘要
This study examined the feasibility and operation performance of plasma torch (PT) pyrolysis and gasification of biomass wastes, taking sunflower-oil cake as the target material. Emphases were focused on the effects of the pyrolysis and gasification conditions on the yields and compositions of major species of gas products when adding additives. The additives used were K2CO3 and ZnO, and the reaction temperature was set at 973 K. A comparison of the constitutes of gas products via nitrogen plasma torch (N-PT) and steam plasma torch (S-PT) was made. In the N-PT process without the additives, the maximum accumulated volume fractions (or mass fractions) excluding N2, H2O, CO2 and NOx for the gas products of CO, H2 and CH4 are 29.77 vol.% (84.29 wt.%), 69.25 vol.% (14 wt.%) and 0.93 vol.% (1.51 wt.%), respectively. As 5 wt.% of K2CO3 was added to the N-PT process (noted as NK-PT), the volume fractions of CO and CH4 in the gas products were increased, giving fractions of CO, H2 and CH4 of 44.88 vol.% (79.07 wt.%), 39.29 vol.% (4.94 wt.%) and 18.8 vol.% (15.9 wt.%), respectively. The effect of adding 5 wt.% of ZnO to the N-PT process (denoted as NZ-PT) on the fractions of CO, H2 and CH4 was insignificant, yielding 28.6 vol.% (83.53 wt.%), 70.4 vol.% (14.7 wt.%) and 0.95 vol.% (1.58 wt.%), respectively. In S-PT process without the additives, the fractions of CO, H2 and CH4 are 7.16 vol.% (41.22wt.%), 85.7 vol.% (35.22 wt.%) and 7.11 vol.% (23.39 wt.%), respectively. A comparison with those of the N-PT indicated significant increases of the fractions of H2 and CH4 in the gas products for the S-PT. For the S-PT process with addition of 5 wt.% of K2CO3 (called as SK-PT process), the fractions of CO, H2 and CH4 are 6.54 vol.% (42.57 wt.%), 89.25 vol.% (41.49 wt.%) and 4.17 vol.% (15.51 wt.%), respectively, indicating an increase of fraction of H2. An addition of 5 wt.% of ZnO to the S-PT (expressed as SZ-PT process) yielded the fractions of CO, H2 and CH4 of 4.56 vol.% (31.31 wt.%), 89.22 vol.% (43.8 wt.%) and 6.13 vol.% (24.09 wt.%), respectively, also showing an increase of fraction of H2. Futher, the volume fraction of CH4 for the SZ-PT is higher than that for the SK-PT. The above results can be summarized as follows. 1) An addition of K2CO3 to the N-PT enhances the formation of CO and CH4. 2) An introduction of steam to the PT increases the volume fractions of H2 and CH4. 3) Adding K2CO3 and ZnO to the S-PT further increases the volume fractions of H2. 4) SZ-PT and SK-PT give about the same volume fraction of H2 of 89.2 vol.%, while the volume fraction of CH4 for SZ-PT is 6.13 vol.% better than that for SK-PT of 4.17 vol.%. As bio-energy is now accepted as having a potential to supply a significant portion of the projected renewable energy provisions of the future, the information provided by this study is thus useful for converting the biomass waste to fuel gas via the proposed torch plasma pyrolysis and gasification techniques, approaching to meet the goal of full recycle of biomass wastes and zero biomass wastes.