|Abstract: ||本研究嘗試利用煅燒白雲石取代部分氣泡式流體化床氣化系統之床砂，並評估作為催化劑提升廢車破碎殘餘物(Automobile Shredder Residue, ASR)，氣化產能之效率。試驗控制條件分別包括當量比(Equivalence ratio, ER)0.3、氣化溫度850℃及0~50%煅燒白雲石之取代比例等，產能效率則分別評估產氣組成特性、產物分布特性及合成氣熱值等，此外，污染物(重金屬、硫及氯)排放之分布特性，亦是本研究之重點。|
試驗結果，H2 及CO 組成比例分別為3.57 vol.%及4.86 vol.%，當以30%煅燒白雲石取代床砂後，分別增加為3.99 vol.%及5.95 vol.%，產氣比例分別提升了10.5%及18.3%。隨著煅燒白雲石之取代比例增加，ASR 催化氣化之產能效率則有增加之現象，其中以添加30%煅燒白雲石取代床砂條件下為最佳，產氣熱值從未添加煅燒白雲石之3.50 MJ/Nm3 增加至3.85 MJ/Nm3，氣體能源產量從4.98 MJ/kg 增加至5.14 MJ/kg，冷燃氣效率從17.40%增加至17.95%。就能源轉換效率之提升結果顯示，煅燒白雲石取代部分石英床砂確實有助於提升ASR 氣化產能之效率。重金屬排放特性之分析結果顯示，銅、鋅、鉻及鉛金屬，透過添加煅燒白雲石於試驗時，有效將原本分布於液相產物及氣相產物之重金屬，轉移至固相產物及煅燒白雲石中，大幅降低合成氣中重金屬含量。以未添加煅燒白雲石取代床砂之試驗結果為例，銅、鋅、鉻及鉛金屬之氣相產物分別為11.71%、9.07%、8.11%及36.28%，當煅燒白雲石取代30%床砂後，前述重金屬氣相產物比例分別降低為0.03%、0.91%、0.58%及1.13%。然而，易揮發性之鎘及汞，則主要分布於合成氣中，煅燒白雲石之添加對其較無明顯影響。
氣相及液相產物中硫含量分布比例，分別為57.6%及8.06%，當煅燒白雲石取代30%床砂後，氣相及液相產物比例分別降為16.6%及2.08%。而氣體中硫化氫濃度從未添加煅燒白雲石之570.84 ppm 降低至30%煅燒白雲石取代比例之439.38 ppm，硫化氫去除率約23%。氯排放特性之結果顯示，未添加煅燒白雲石取代床砂之試驗，氣相中氯含量分布比例為60.84%，當煅燒白雲石取代30%床砂後，其氣相中氯含量分布比例降低至20.91%。整體而言，煅燒白雲石取代氣化爐內之石英床砂，有利於降低合成氣中之氯及硫化物之排放。
根據本研究成果初步驗證煅燒白雲石可部分取代石英床砂，並作為氣化反應過程之催化劑，有效促進ASR 催化氣化轉換能源之效率，同時對後端產生之污染物排放及分布特性亦有完整的評估。因此，本研究結果應可提供做為未來相關ASR 催化氣化轉換能源應用技術及污染物排放控制之參考依據。;This research investigates that automobile shredder residue (ASR) converted into energy by fluidized bed gasification system with controlling at ER 0.3, temperature 850℃ and 0~50% ratio calcined dolomite addition as the catalyst and bed material replacement. The producer gas composition, product distribution, energy yield efficiency and trace pollutants (e.g. heavy metal, sulfur, and chlorine) emission characteristics were evaluated.
In the case of without calcined dolomite replacement test, the H2 and CO composition were 3.57 vol.% and 4.86 vol.%, respectively. When the bed material was replaced by 30% calcined dolomite, the H2 and CO composition was slightly increased to 3.99 vol.% and 5.95 vol.%, respectively. The syngas production increasing rate was approximately 10.5% and 18.3%, respectively. The energy yield efficiency of ASR catalyst gasification was increased with an increase in calcined dolomite replacement ratio, especially for 30% replacement ratio. The heating value of producer gas increased from 3.50 MJ/Nm3 to 3.85 MJ/Nm3 with calcined dolomite replacement ratio increasing from 0% to 30%. The gas energy density was also increased from 4.98 MJ/kg to 5.14 MJ/kg as well as the cold gas efficiency (CGE) was increased from 17.40% to 17.95%. Based on the results of energy conversion efficiency, replacing quartz sand with calcined dolomite could enhance the energy yield efficiency in ASR gasification.
The heavy metals emission characteristics results indicated that Cu, Zn, Cr, and Pb were mainly partitioned in the solid phase as calcined dolomite used in quartz sand replacement. That is, when calcined dolomite was used in gasifier, the above metals were significantly decreased in syngas as well as the metals emission was aslo reduced. In the case of without tested calcined dolomite replacement, the Cu, Zn, Cr, and Pb partitioning percentages in the gas phase were 11.71%, 9.07%, 8.11%, and 36.28%, respectively. In the case of 30% calcined dolomite replacement ratio, the above metals partitioning percentages in the gas phase were decreasing to 0.03%, 0.91%, 0.58%, and 1.13%, respectively. However, Cd and Hg were mainly partitioned in the syngas resulting in their high volatility characteristics. Obviously, the calcined dolomite addition was insignificant effect on Cd and Hg partitioning characteristics.
According to the results of the sulfur and hydrogen sulfide emission characteristics, in the case of without tested calcined dolomite replacement ratio, the sulfur partitioned in the gas phase and liquid phase were 57.6% and 8.06%, respectively. When replacing bed material with 30% calcined dolomite, the above sulfur partitioning characteristics were decreased to 16.6% and 2.08%, respectively. The concentration of hydrogen sulfide in syngas was decreased from 570.84 ppm to 439.38 ppm with an increased in calcined dolomite replacement ration from 0% to 30%. The hydrogen sulfide removal rate was approximately 23%. Meanwhile, in the case of without tested calcined dolomite replacement ratio, the chlorine was almost 60.84% partitioned in the gas phase. when replacing bed material with 30% calcined dolomite, the chlorine partitioning percentage in the gas phase was also significantly decreased to 20.91%. Overall, replacing quartz sand with calcined dolomite is beneficial to reduce the chlorine and sulfide emission in the syngas.
In summary, this research has proved the calcined dolomite could replace quartz sand as the bed material. It could enhance energy conversion from ASR via catalytic gasification, but also reduce the derived pollutants (e.g. heavy metal, sulfur, and chlorine) emission during the ASR gasification process. Therefore, the results of this research could provide useful information for the selection of catalytic gasification technologies and control strategies of pollutants emission in the future.