高溫觸媒熱再循環燃燒器實作及其應用; A High-Temperature Sr0.8La0.2MnAl11O19-α Catalytic Heat-Recirculating Burner and Its Application

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題名:	高溫觸媒熱再循環燃燒器實作及其應用;A High-Temperature Sr0.8La0.2MnAl11O19-α Catalytic Heat-Recirculating Burner and Its Application
作者:	趙依心;Yi-Hsin Chao
貢獻者:	機械工程研究所
關鍵詞:	超低氮氧化物和一氧化碳排放;高溫觸媒熱再循環燃燒器;空間速度;高溫觸媒;瑞士捲燃燒器;space velocity;high-temperature catalyst;high-temperature catalytic heat-recirculating co;very low [NOx] and [CO] emissions;Swiss-roll burner
日期:	2006-07-15
上傳時間:	2009-09-21 11:55:19 (UTC+8)
出版者:	國立中央大學圖書館
摘要:	本研究結合熱再循環燃燒和觸媒燃燒兩大技術，開發一高溫觸媒熱再循環燃燒器，主要是應用熱再循環燃燒器(瑞士捲燃燒器，SRB)和高溫觸媒(Sr0.8La0.2MnAl11O19-α)，以建構一高效率和幾無NOx排放之燃燒裝置。本實驗使用甲烷與空氣預混燃氣做為燃料，首先針對SRB之基本特性進行評估，含SRB內部整體溫度分布、熱再循環率(heat recirculation rate, HR)和廢氣排放濃度等。之後，建立一高溫觸媒測試平台，定量量測和評估高溫觸媒的各項特性，包含自行製備高溫觸媒粉末、混合燃氣當量比(φ)之影響、高溫觸媒反應所需之初始溫度T0及其反應後之溫度(Tc-out)、燃氣空間速度(SV)之影響、高溫觸媒表面積變化之壽命測試，以及觸媒反應生成物濃度的量測等。最後，結合上述兩者實作設計一高溫觸媒熱再循環燃燒器。量測方面，使用11支K型和R型熱電偶、溫度擷取卡和資料處理軟硬體，可進行長時間的溫度記錄，以及利用煙道氣體分析儀，量測NOx和CO排放濃度。另外，使用掃描式電子顯微鏡(SEM)和氮氣吸附孔隙儀(ASAP)進行高溫觸媒之表面顆粒觀察和觸媒表面積測定。實驗結果顯示，固定φ=0.5時，SRB之整體溫度分布會隨著Ref值增加而上升，且最大溫度量測值均位在SRB中心特別設計之駐焰器附近，顯示駐焰器可將貧油預混甲烷火焰穩定地駐留於燃燒室中心。進一步分析Ref對HR之影響，發現在固定φ=0.5時，HR值會隨著Ref值升高而上升，這表示混合燃氣的流速愈快，使得SRB內部的熱傳導效應愈明顯，故熱再循環效果愈佳。有關高溫觸媒測試方面，當φ=1.3，控制T0=500oC，高溫蜂巢觸媒之Tc-out，會隨SV之增加(76,000~465,000 1/h)而增加，從1,050oC增加至約1,300oC，但當SV等於和大於310,000 1/h，Tc-out即不再上升且略微下降。有關廢氣量測方面，[NOx]和[CO]雖然會隨SV上升而增加，但均低於12 ppm。另外，固定φ=0.5、T0=500oC和SV為76,000 1/h，針對高溫觸媒進行5小時、15小時和52小時的壽命測試，結果顯示其觸媒表面積會呈現遞減的趨勢，從反應前的25 m2/g，依序遞減為16、8和5 m2/g，顯示高溫觸媒和載體製作方面，仍有甚大之改善空間。最後，以SRB當預熱器，將富油甲烷燃氣(φ=1.3)於SRB燃燒後，通入SRB出口端之高溫觸媒區，成功地實作設計出一具極低NOx和CO之高溫觸媒熱再循環燃燒器。 This study aims to construct a high-temperature catalytic heat-recirculating combustor using a Swiss-roll burner (SRB) and a high temperature Sr0.8La0.2MnAl11O19-α catalyst, which features high-efficiency and near-zero [NOx] emissions. Fuels are premixed methane/air mixtures at different equivalence ratios (φ), which are used in a 1.5-turn SRB for the performance test, including measurements of temperature distributions inside the SRB, heat-recirculation rate (HR), concentrations of emissions (NOx and CO), etc. Then, a new reaction platform is designed to quantitatively investigate various characteristics of such high-temperature Sr0.8La0.2MnAl11O19-α catalyst, from its preparation and production to the effect of φ, from temperature variations before and after the honeycomb catalytic sector to the effect of space velocity (SV), and from the degradation of the surface area of such catalyst after long time operation to measurements of emissions. The goal is to combine the above two technologies to design a high-temperature, high-efficient, very-low-NOx burner. The time evolution of temperature distributions inside the SRB are measured using as many as eleven K- and R-type thermocouples for which these data are recorded by a PCLD-818 data acquisition card an a GeniDAQ software at a sampling rate of 1 Hz. Emissions are measured by the standard flue-gas analyzer. The photographs and surface area of the high-temperature catalyst are obtained from the Scanning Electron Microscopy (SEM) and the Accelerated Surface Area and Porosimetry System (ASAP). Results for φ=0.5 reveal that all measured temperature data at various positions of the SRB increase with increasing Ref (Ref=VfDin/ν) increases from 370 to 980, where Vf, Din, and ν are the supply reactant velocity, the SRB channel width, and the kinematic viscosity of reactants, respectively. The highest temperature at various Ref and all occurs near a previously-designed flame holder in the central combustion chamber, confirming the flame holding feature for stable combustion in the center of the SRB. Furthermore, the HR of the SRB is found to be increased with Ref as well. Concerning the high-temperature catalyst, the initial temperature (To) condition to start up the high-temperature catalyst at φ=1.3 is To=500oC. Temperature measurements show that the temperature after the high-temperature catalyst (Tc-out) increases from 1,050oC to 1,300oC when values of SV increase from 76,000 1/h to 465,000 1/h. However, when values of SV are larger or equal to 310,000 1/h, Tc-out not only ceases its increase but also decreases slightly. Values of [NOx] and [CO] are only 1.9 and 2.1 ppm when SV=76,000 1/h. Even for SV=465,000 1/h, values of [NOx] and [CO] are all below 12 ppm. The longevity test of the high-temperature catalyst at φ=0.5, To=500oC, and SV=76,000 1/h show that the surface area of the catalyst would decrease from its initial value 25 m2/g to 5~8 m2/g when about 52 operation hours are applied. Finally, we use the SRB as a pre-heater to burn first rich CH4/air mixtures (φ=1.3), so that its high temperature off-gas (To>500oC) with remaining CH4/air fuels can be further reacted in the high-temperature honeycomb catalytic sector. This new device is believed to be of useful in gas turbine applications and in dealing with many industrial off-gas fuels. Thus, the goals of saving energy and reducing pollutants can be achieved.
顯示於類別:	[機械工程研究所] 博碩士論文

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