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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/2492

    Title: 流動式顆粒床過濾器之濾餅機制行為研究;Study of cake behavior on moving granular bed filter
    Authors: 陳一順;Yi-Shun Chen
    Contributors: 機械工程研究所
    Keywords: 濾餅厚度;煙塵濃度;氣體進口速度;cake thickness;dust concentration;filtration superficial velocity
    Date: 2009-01-22
    Issue Date: 2009-09-21 11:48:25 (UTC+8)
    Publisher: 國立中央大學圖書館
    Abstract: 在燃煤發電技術中,會產生大量的粉塵微粒、硫氧化物及氮氧化物等有害物質。粉塵微粒在進入燃氣渦輪機後,會附著在渦輪機的葉片上並造成破壞,因此燃燒後的高溫燃氣在進入燃氣渦輪機之前,必須先將大量的粉塵微粒過濾,以確保燃氣渦輪機動力系統的正常運作。流動式顆粒床過濾器淨化高溫燃氣是一項方案。顆粒床過濾的方法為利用濾材將固體與氣體分離,其基本操作原則為粉塵微粒經由高溫氣體的傳送進入顆粒床本體,並利用在燃氣通過濾材的過程中,將粉塵微粒吸附在濾材上,而乾淨氣體則被排出。流動式顆粒床過濾器的過濾機制有深層過濾模式及淺層過濾模式(濾餅模式),淺層過濾模式則建立在深層過濾模式的自由表面上。 在過去的冷性能相關實驗中,我們發現濾餅的存在對於流動式顆粒床過濾器的過濾效率有很重要的影響。因此,本篇論文的研究將針對在流動式顆粒床過濾器之濾餅過濾行為做探討。首先將設計與建構濾餅量測系統與量測方法,此系統可在不同過濾狀態下量測濾餅厚度。接著,利用此量測系統及量測方式,測量在濾餅成長下,對於系統的壓降及過濾效率的影響,以找出最佳的過濾效率操作參數,並確定系統的確能有效達到更高的過濾效率。另外,依據濾餅成長的實驗結果,進行濾餅結構的壓縮變形測試,壓縮變形測試項目以濾餅之實際過濾效率與氣體穿透濾餅的壓降隨時間變化為主,氣體進口速度、煙塵濃度與濾餅厚度都是影響因素。最後,利用三維冷模測試模型,實際通入含煙塵氣體,測試濾餅效應對於整體過濾效率的影響,並期待未來將相關成果建立及實際應用在高溫流動式顆粒床過濾系統。 A coal-fired power plant releases large amounts of pollutants, such as dust particulates, SOX and NOX. The high temperature gases contain many dust particulates and fly ashes which should be filtrated before entering gas turbine, because the dust particulates could destroy the gas turbine in a coal-fired power plant. The moving granular bed used for filtration of the hot gas is one important apparatus under development. The granular bed filter method is a gas – solid process commonly applied to remove different concentrations of fine particulates from the gas flows. The granular bed filter is based on the principle that the suspended particulates are removed by the passage of flue gas through filter granules. The clean gas exits from the outlet of the bed. Separating airborne dust in this kind of filter may take place either in the surface filtration mode (dust cake) or the deep-bed filtration mode, depending on which region in the filter that particulate deposition occurs. In the surface filtration mode, the filter media acts as a barrier, so that dust cakes tend to build up along the surface of the filter media, with relatively little dust penetrating the media itself. From our earlier series of cold tests in granular bed filter, we found that the existence of dust cake had influence on the collection efficiency of filter system. Consequently, this thesis tries to research filtration behavior of dust cake to get better filtration performance on a moving granular bed filter. First, we will develop an on-line powder pressure-displacement measurement system and the measurement method of cake thickness. The system could be adopted under the different condition. Using this system and method, the effects of pressure drop and collection efficiency understand on cake formation and growth. The results will be used in the operation factors. The complete increase of collection efficiency must be achieved by the filter system. In addition, dust cake compressibility of fine fly ashes on a filter system was carefully investigated under well-controlled conditions and by measuring the cake thickness under different filtration conditions using an on-line powder pressure-displacement measurement system. The cake compression test includes the collection efficiency and the pressure drop of the dust cake. The filtration superficial velocity, the dust concentration and the cake thickness are important factors. According to results of the cake filtration, the test will build a 3D cold test facility and perform the cold test. In the cold test, the control factor includes the circulation rate, the concentration of the dust gases, and the material and sizes of the filter granules. The result of cold test is essentially the development of a moving granular bed filter that could be applied in a high-temperature environment. The results are expected to serve as the basis for future research
    Appears in Collections:[機械工程研究所] 博碩士論文

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