| 摘要: | 本研究目的在於探討使用流體化床氣化爐，在控制溫度850℃及等值比為0.2的條件下，對下水汚泥(sewage sludge, SS)與紡織污泥(textile sludge, TS)共同氣化產能的可行性。研究同時利用氣化爐結合整合型熱氣清淨系統，評估去除共同氣化過程所衍生污染物之效果，其中熱氣清淨系統主要以沸石、煅燒白雲石與活性碳所組成。為進一步瞭解下水汚泥與紡織污泥之共同氣化反應行為，本研究利用多步驟熱動力學分析方法，討論有關污泥共同氣化的熱分解反應動力學參數。
根據多步驟熱動力學分析結果顯示，下水汚泥、紡織污泥及其混合物的熱分解過程，呈現三種假反應(pseudo reaction)，其中紡織污泥反應活化能在三個連續反應階段，分別介於90-160、100-190與230-320 kJ/mol之範圍。雖然紡織污泥較不容易分解，但當與下水污泥混合後，將有助於污泥之共同分解。
下水汚泥與紡織污泥共同氣化反應分析結果顯示，當添加紡織污泥從15%增加至45%時，H2產量從2.45 mol/kg下降至2.12 mol/kg，然CO產量可從2.83 mol/kg上升至3.98 mol/kg。在共同氣化反應過程，產生氣體之冷燃氣效率介於13.61%至14.88%間，產氣能量則在2.40至2.63 MJ/kg之範圍內。若相較於下水污泥的氣化反應結果，單一下水汚泥的氣化產氣能量約為3.22 MJ/kg，稍高於與紡織污泥共同氣化之產氣能量。然而，就焦油形成的影響而言，當試驗過程添加紡織污泥，氣化反應所生成之總焦油量將降低，其中尤以輕質焦油的減量最為明顯。因此，試驗過程添加紡織污泥從15 wt.%增加至45 wt.% 時，可顯著提升污泥共同氣化的效能。熱氣清淨系統對於去除焦油之研究結果顯示，此系統可去除總焦油含量之77%，同時可去移約90%之重質焦油及35%氨氣。整體而言，本研究成果可初步驗證紡織污泥與下水汚泥共同氣化處理，不僅可處理大量產生之紡織污泥，同時可轉化污泥為能量應用。本研究擬發展的整合型熱氣清淨系統 (包括沸石、煅燒白雲石及活性碳)，對氣化產氣中焦油及NH3具有良好的去除效果。;This study investigated that feasibility of energy yield in co-gasification of sewage sludge (SS) and textile sludge (TS) using a fluidized-bed gasifier under controlled temperature of 850 ℃ and equivalence ratio of 0.2. An integrated hot-gas cleaning system equipped with zeolite, calcined dolomite, and activated carbon was installed and connected with gasifier for removing of trace pollutants produced from co-gasification process. Meanwhile, to further understanding the co-gasification behavior, the thermal degradation kinetic of SS and TS was also discussed using multistep-based determination method.
The kinetic analysis results indicated that the three pseudo reactions occurred in the decomposition of sewage sludge, textile sludge, and their blends using the multistep-based method. Compared to sewage sludge, the activation energy of textile sludge for three consecutive stages varied more widely in the 90-160, 100-190, and 230-320 kJ/mol range, respectively. Although, textile sludge was found harder to decompose, but its presence in a sludge mixture might positively influence sludge co-degradation.
Concerning co-gasification of SS and TS, in the case of TS addition increasing from 15 to 45 wt.%, H2 yield decreased from 2.45 to 2.12 mol/kg as well as CO yield increasing from 2.83 to 3.98 mol/kg. The cold gas efficiency (CGE) of the produced gas in co-gasification was varied in the range of 13.61-14.88 %, whereas the energy yield was found in the range of 2.40-2.63 MJ/kg of dry sludge. However, the energy yield produced from SS gasification was approximately 3.22 MJ/kg. It could observe the higher energy yield generated from SS gasification than that of co-gasification of SS and TS. Regarding tar formation, the TS presence in the feedstock could reduce the relative amount of total tar, especially for the light fraction tar reduction. Therefore, the TS addition increased from 15 to 45 wt.%, it could significantly enhance the gasification performance. A hot-gas cleaning system used in this research presented a considerable performance on tar removal efficiency that reached about 77 % of total tar content as well as removing 90 % heavy fraction tar and 35% ammonia gas in the produced gas.
In summary, co-gasification of sewage and textile sludge was considered as an alternative for simultaneous treating the increasing amount of these sludge and converting sludge-to-energy. Meanwhile, using a hot-gas cleaning system consisting of zeolite, calcined dolomite, and activated carbon would become a good choice for abating the tar and NH3 impurities in producer gas. |
