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標題: Capture and Concentration of Carbon Dioxide from Flue Gas via Modified Carbon Nanotubes
作者: 盧重興
關鍵字: 環保工程;應用研究
自2006 迄今,本團隊所發展出之3-aminopropyl-triethoxysilane(APTS)改質奈米碳管(carbon nanotubes, CNTs)為一具有高開發潛力新型奈米吸附材料,在吸附CO2 的研究上已經證明比傳統吸附材料(如活性碳、沸石)具有更高吸附容量與穩定循環吸附能力。CNT(APTS)於煙道除硫系統(Flue GasDesulfurization, FGD)後端條件下(溫度:50ºC、CO2≒15%),吸附量達到82mg/g (1.9 mmol/g),比一般碳素或矽素材吸附劑高出數倍,並接近聯合國之氣候變遷組織(Intergovernmental Panel on Climate Change, IPCC)所提出的固體吸附劑吸附量(2 mmol/g)。由研究中又發現CNT(APTS)可完全脫附CO2,20 次循環吸附後,吸附量能夠維持79 mg/g(回復率96%)以上,顯示吸附能力無明顯衰退,而活性碳及沸石則無法有此良好的穩定性。CNTs 優異的吸脫附速率、CO2 捕獲效率、低吸脫附熱值及反覆吸脫附能力,使CNT(APTS)吸附成本能夠降低,預期能夠達到US$40/ton-CO2 以下(歐洲碳排放交易價格),未來在產業上捕獲煙道廢棄CO2 的應用極具潛力及商機。本計畫預以APTS 改質CNTs 進行煙道氣中CO2 捕獲及濃縮之研究,針對實場需求設計固定床及流體化床反應器,求取CO2 吸附及脫附/濃縮效率及實場操作參數,評估其應用於產業捕獲煙道氣CO2 之成本效益。本計畫為兩年期之研究,第一年度計畫將測試各種不同型式之商用CNTs 等吸附劑之CO2 吸脫附效率及成本分析,以及求取水蒸汽或變溫/變壓法等技術濃縮CO2 之操作參數。CNTs 藉由本研究團隊所開發的APTS 改質技術進行表面處理,以FGD 後端煙道氣條件和固定床吸附系統測試CNT 吸附CO2 能力,並求取水蒸汽或變溫/變壓法等技術濃縮CO2 之操作參數。因一般實場中煙道氣風量較大,固定床吸附系統體積必須增加,並容易發生壓降等問題,所以本研究規劃以流體化床系統來解決實場會面臨之問題。第二年度計畫將設計流體化床系統,進行CO2 吸脫附及濃縮之操作參數求取及成本分析,流體化床系統參數包括床壓與最小流體化速度、氣體流速、床體高度、粒徑尺寸與終端速度、溫濕度效應與熱傳導效率等操作參數,最後並利用水蒸汽或變溫/變壓法濃縮CO2 來評估流體化床應用於實場應用之可行性。本計畫完成後,預計可以提供未來模場或實場測試所需之吸附材改質技術及操作參數等,進行設計及操作,使國內碳捕獲技術更趨於商業化實廠應用。

ABSTRACTThe 3-aminopropyl-triethoxysilane(APTS) modified CNTs have been proven to bepromising sorbents for CO2 capture in our previous studies from 2006 to 2009. The resultsindicated that CNTs showed the greatest CO2 adsorption as compared with conventionalsorbents such as activated carbon and zeolite. The CO2 adsorption capacity as high as 82 mg/g(1.9 mmol/g) was obtained with a 15% CO2 inlet and at 50C, which is close to the targetedcapacity, 2 mmol/g, documented by Intergovernmental Panel on Climate Change (IPCC). Thecyclic adsorption of CO2 via CNT(APTS) showed that the adsorbed CO2 could be desorbedvia combination thermal and vacuum desorption while the adsorbed CO2 due to physicalinteraction could be regenerated during cycles of operation. The adsorption index (AI) ofCNT(APTS) at 20 cycle is 96%, which shows stable AI in 20 cycles of desorption. Thissuggests that the CNT(APTS) can be used in a prolonged cyclic operation with a low amountof energy required for desorption process. The advantage of CNTs are that the adsorption costof CNTs could reduced to US$40/ton-CO2 and desorption of CO2 from CNTs requires lessdesorption heat making them promising sorbents for CO2 capture in the field.This research project will employ CNT(APTS) as sorbent for CO2 capture andconcentration by fixed and fluidized bed adsorption system to assess their feasibility in thefield. The aim of project in 1st year is to find the best commercially available CNTs for CO2adsorption and its operation parameters for steam and thermal/pressure swingdesorption. It includes the study of CO2 adsorption under a simulated environment (post-fluegas desulfurization (FGD)) to distinguish the adsorption and desorption properties foreach type of CNT. The fixed bed system could cause the large pressure drop due to amountof flow rate in the field, which makes the system needs huge volume of adosrber. Hence, thefluidized bed adsorption system will be tested in the 2nd year which is to determine theoperation parameters of fluidized bed CO2 adsorber for the field. It includes the minimumfluidization velocity, pressure of fluidized bed, velocity of CO2 gas, height of fluidized bed,particle size, terminal velocity of particle, effects of temperature and moisture, heatconduction efficiency and CO2 desorption/concentration parameters via steam andthermal/pressure swing desorption.This project expects to provide useful information with respect to the potentialcommercially available CNT and their best operating conditions as design criteria for afull-scale adsorber in the field.
其他識別: NSC99-2221-E005-032-MY2
Appears in Collections:環境工程學系所

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