移動式顆粒床過濾器進風口氣體流場行為與過濾性能之研究

The study of gas flow behaviors and filtration performance of moving granular bed filter

許嘉仁(Chia-Jen Hsu)

指導教授 ： 蕭述三

國立中央大學/工學院/機械工程學系/博士(2011年)

摘要

近年來先進國家均大量投入整合型氣化煤複循環發電系統的發展，但在這先進燃煤發電技術系統中，氣化過程所產生的合成氣含有大量粉塵有害物質，相對於燃煤發電系統中的渦輪機系統會產生腐蝕及破壞，因此發展過濾裝置為一重要解決方案，如此將可確保渦輪機系統壽命與發電效率的增加。
由於在顆粒床過濾器中，進風口的合成氣體分佈於過濾自由面上的均勻性，對於顆粒床的過濾行為而言相當重要。因此，在本論文中將利用所成功開發出的顆粒床過濾器，進行一系列氣體流場行為與過濾性能之研究。
針對氣體流場行為的研究，本論文將提出一新式合成氣進風口系統，並藉由一系列實驗分析的結果，進行系統設計之可行性評估找出最佳系統設計，並作為後續系統開發的依據。首先，在進風口系統中置入導流板裝置的設計構想，目的在改善原始進風口系統中氣體速度分佈不均的現象，並依據實驗所獲得之氣體流場速度分佈結果，定義氣體速度分佈標準差與過濾自由面速度差值的均勻性分析指標，並由其分析指標找出最佳進風口系統的設計參數。因此在固定中導流板長度230 mm與角度0°的條件下，並由不同上下導流板長度、角度與濾材質量流率變化(過濾程序之固定床與移動床模式)之實驗結果可知，在置入三組導流板設計於進風口系統中，將可提升進風口氣體流場速度分佈的均勻性，其中以固定床模式下的上下導流板長度200 mm與角度40°；移動床下的上下導流板長度170 mm與角度50° 的參數條件下能達到最佳的速度分佈均勻性，能使顆粒床濾材使用率增加，同時也將減少成本的支出。
而在顆粒床過濾性能研究上，依據氣體流場實驗結果，進行一系列冷性能過濾性能實驗，探討不同導流板設計、濾材質量流率與進口過濾自由面平均風速下的顆粒床過濾性能結果，並依據過濾效率與床體、兩過濾自由面壓降變化，找出最佳過濾性能實驗參數。而由過濾性能實驗結果可知，氣體流場的均勻性將有助於整體顆粒床過濾性能提升，同時由實驗結果也找出具最佳氣體流場均勻性與過濾效率的實驗參數條件為上下導流板長度170 mm、角度50°、濾材質量流率 600 g/min與進口過濾自由面平均風速40 cm/s。
最後，本論文研究中所得之成果，除將提供未來後續在建構連續式顆粒床過濾系統之相關週邊設備完整化外，也將給予高溫熱模過濾系統建構之參考，以加速整合型氣化煤複循環發電系統開發商業化。

關鍵字

顆粒床過濾器 ； 氣體流場 ； 導流板 ； 過濾效率 ； 壓降

並列摘要

The high-temperature gas cleanup system was designed in order to promote the performance of the IGCC power system. The IGCC system is considered the highest potential facility provide the important design for advanced coal-fired power plants. The high temperature syngas contains many dust particulates and fly ashes which should be filtrated before entering gas turbine. The moving granular bed filter used for filtration of the hot gas is one important apparatus under development. When the filter media move downwards through the vertical channel, the stagnation zones may form causing serious plugging problem. Putting a series of flow corrective elements has been demonstrated to be a good solution to diminish the stagnant zones and has been patented by our research group. However there still remain some systematic problems to commercialize the whole facility.
The design of the gas inlet component of the granular bed filter is important for achieving a uniform gas distribution and higher usage rate of the filter media. Consequently, this thesis tries to research gas flow behaviors and filtration performance by a series experiment of the gas velocity distribution, filtration efficiency and pressure drop to obtained better uniform distribution of gas velocity and filtration performances on a moving granular bed filter.
In study of gas flow behavior, the new gas inlet component design uses baffle devices in order to achieve a more uniform gas velocity distribution. The uniformity of the gas velocity distribution can be characterized by the standard deviation definitions and the differences in the mean velocities between the two filtration surfaces. The baffle lengths and angles affected the uniformity of gas velocity in inlet and filtration surfaces. The optimal experimental parameters were found by using different baffle lengths, angles and mass flow rate of filter media. The results of uniform gas velocity distributions were obtained by a series experiments. In condition of fixed middle baffle length 230 mm and angle 0°, the optimal experimental parameters were found which the baffle lengths 200 mm and angles 40° for fixed bed mode；the baffle lengths 170 mm and angles 50° for moving bed mode.
In study of filtration performances, the different baffle lengths and angles were studied according results of gas flow behavior in 3D cold filtration test. Moreover, the control factor includes the filtration superficial velocity, the mass flow rate of filter media, and the concentration of the dust gases in a series filtration experiment. The experiment results show that the uniform gas velocity distributions can help the higher filtration ecciciency in experiments of filtration performance. The optimal parmeters were the baffle lengths 170 mm, angles 50°, mass flow rate of filter media 600 g/min and the filtration superficial velocity 40 cm/s.
Furthermore, the results of gas flow behavior and filtration performance give important information about IGCC system that will be helpful for designing better models of moving granular bed filters in the future.

並列關鍵字

filtration efficiency ； baffle ； gas flow behavior ； pressure drop ； Granular bed filter

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