兩階段移動式顆粒床之研究;The Study of Two-Stage Moving Granular Bed Filter

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题名:	兩階段移動式顆粒床之研究;The Study of Two-Stage Moving Granular Bed Filter
作者:	張家維;Chang, Chia-Wei
贡献者:	機械工程學系
关键词:	移動式顆粒床;除塵技術;兩階段;發電;過濾效率;Moving granular bed filter;Dust removal;Two-stage;Power plant;Collection efficiency
日期:	2021-07-13
上传时间:	2021-12-07 13:17:52 (UTC+8)
出版者:	國立中央大學
摘要:	在煤和生物質的氣化或燃燒過程裏，發展中的移動式顆粒床過濾器（MGBF）之應用在其間扮演著重要角色。這些過濾器具有相當大的開發潛力，可應用於先進發電系統的高溫氣體淨化。然而移動式顆粒床過濾器中的缺陷設計，可能會導致停滯區的產生並進而引起嚴重的問題，例如堵塞。因此為了解決停滯區的問題，在文獻中提出裝設於過濾器中的一流動校正單元為解決辦法，然而其中大多數研究為使用單一尺寸顆粒的過濾器濾材。本論文提出了一種新的方法，該方法為在一個過濾器裝置中導入了兩種顆粒大小的過濾器濾材，稱為兩階段過濾模式。依據學者Johanson 提出質量流率過濾器的設計理論為基礎，設計使用兩種尺寸顆粒的過濾器濾材來減少停滯區。基於過濾器中不同的幾何設計，在本研究中六種二維實驗配置中評估移動式顆粒床中的十字流流動模式，其中兩種過濾濾材由粗石英砂和細石英砂顆粒組成。研究發現，過濾器濾材的流動方式受過濾器內部幾何形狀的影響，且兩階段過濾器的最佳設計可在165 分鐘內完成並消除停滯區。在三維除塵技術實驗方面，延續採用二維兩階段移動式顆粒床過濾器之幾何設計，並使用粗、細兩種過濾濾材。在室溫下，進行使用粗石英砂顆粒和細石英砂顆粒兩種濾材下對各種質量流率的研究，並測試壓降、粉塵捕集效率和粉塵的粒徑分佈。此外，使用質量消耗比率來反映實際濾材的質量流量。而質量消耗比率可影響壓降、粉塵捕集效率和粉塵的粒徑分佈。研究指出兩階段移動式顆粒床過濾器可捕集大於1.775 μm 的粉塵，其中在粗石英砂顆粒的質量流率設定為330 g / min、細石英砂顆粒的質量流率設定為1100 g / min 下，可獲得最佳的粉塵捕集效率和粉塵的粒徑分佈，本研究的設計同時有助於發電廠高溫除塵系統的開發。;The application of moving granular bed filters (MGBFs) has been growing, which play an important role in the gasification or combustion of coal and biomass. Furthermore, these filters have great potential to be developed for the high-temperature gas cleanup of advanced power generation systems. However, owing to defective designs in MGBFs, the generation of a stagnant zone can result from serious problems such as plugging. Therefore, the researches of flow-corrective inserts (FCI) for filter vessels have been studied to minimize these issues. This study developed a novel approach dubbed as two-stage filtration mode, which combined two sizes of granules in a single filter vessel. Based on the design method of a mass flow vessel by Johanson′s theory, the reducing of a stagnant zone could be satisfied by using two sizes of filtering granules. The flow field in a two-dimensional and cross-flow MGBF was evaluated in six test configurations based on different geometric designs in a filter. The two sizes of filtering granules consisted of coarse and fine silica granules. The findings revealed that the flow field of filtering granules was influenced by the vessel geometry. In a two-dimensional test, the proposed system for two-stage mode minimized the stagnant zone in 165 minutes. We proposed a dust removal solution for the three-dimensional cold testing that used a two-stage MGBF with coarse and fine filtering granules. Using varied mass flow rates for coarse and fine granules at room temperature, the pressure drop, collection efficiency, and dust particulate size distributions were studied. Furthermore, the mass consumption ratio was utilized to evaluate the true mass flow. The pressure drop, collection efficiency, and dust particulate size distributions were all affected by the mass consumption ratio. Particulates larger than 1.775 μm were removed by the filter. Our findings revealed that a mass flow of 330 g/min for coarse granules and a mass flow of 1100 g/min for fine granules provided optimal collection efficiency and particulate size distribution. The proposed design may be useful in the construction of high-temperature systems in power plants.
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