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摘要: 陶瓷膜是過濾高溫含塵煙氣最有效的材料之一，其過濾性能和再生性能與塵粒在陶瓷膜孔道內的沉積和脫附機制相關。本文建立了不同孔隙率的陶瓷膜物理模型，然后結合連續性方程、動量方程和能量方程，設定邊界條件以及沉積條件，模擬了陶瓷膜過濾和脈沖反吹時，高溫煙氣的流動以及塵粒的沉積與脫附過程。結果表明，過濾速度較低和陶瓷膜孔隙率較高時，塵粒易于沉積在陶瓷膜孔道內；脈沖反吹時，增加反吹壓力，延長反吹時間，塵粒易于從陶瓷膜孔道脫附。采用厚度為20 mm，長度為1.5 m，孔隙率為40%的陶瓷膜管過濾溫度為1000 ℃，流速為1 m·min?1，壓力為0.1 MPa的含塵煙氣時，反吹氣壓力應不低于0.3 MPa，反吹時間不短于0.02 s，塵粒脫附時間在13 s，脈沖反吹時間間隔應高于452 s。Abstract: The main sources of fine particulate matter in the air are automobile exhaust and dust-containing hot flue gas emitted from combustion in the process of industrial manufacturing and municipal solid waste incineration, both of which are hard to clean at high temperatures. Ceramic membranes maintain high strength at high temperatures and an acid or alkaline atmosphere, and have a micron-scale and tortuous pores that block dust particles. The ceramic membrane is one of the most effective materials for successful hot flue gas cleaning as used in the integrated gasification combined cycle. Its filtration and regeneration performance are related to the deposition and desorption mechanism of dust particles in the channel of the membrane. In this study, a physical model of ceramic membranes of various porosities was established. Boundary and deposition conditions were then set up by combining continuity, momentum, and energy equations to simulate the flow of hot flue gas and the deposition and desorption process of dust particles during ceramic membrane filtration and pulse back-blowing. The results show that when the filtration velocity is low and porosity of the ceramic membrane is high, it is easy for dust particles to deposit in the membrane channel. Increasing back-blowing pressure prolongs back-blowing time during pulse back-blowing so that dust particles easily desorb from the channel of the ceramic membrane. When a ceramic membrane tube with a thickness of 20 mm, a length of 1.5 m, and a porosity of 40% is used to filtrate flue gas with a filtration temperature of 1000 °C, a flow rate of 1 m·min?1, and a pressure of 0.1 MPa, the blowback pressure should not be <0.3 MPa, blowback time should be longer than 0.02 s, and pulse blowback time interval should be more than 452 s.
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Key words:
- ceramic membrane /
- filtration /
- pulse-jet back blowing /
- deposition /
- desorption
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圖 2 不同孔隙率下的孔隙直徑分布圖
Figure 2. Pore diameter distribution with porosities of 40%, 45%, and 50%
圖 3 不同孔隙率下流速和壓降的關系曲線
Figure 3. Pressure drop in different filtration velocities with porosities of 40%, 45%, and 50%
圖 4 不同孔隙率下網格數量和有效顆粒直徑的關系曲線
Figure 4. Effective grain size in different mesh cell numbers with porosities of 40%, 45%, and 50%
圖 5 不同過濾速度下塵粒沉積濃度和沉積率隨時間變化曲線。（a）塵粒沉積濃度；（b）沉積率
Figure 5. Concentration of deposition dust particles and deposition rate at differrent times with filtration velocities of 1 m·min?1, 2 m·min?1, and 3 m·min?1: (a) concentration of deposition dust particles; (b) deposition rate
圖 6 不同孔隙率下沉積塵粒濃度和沉積率隨時間變化曲線。（a）塵粒沉積濃度；（b）沉積率
Figure 6. Concentration of deposition dust particles and deposition rate at different times with the porosities of 40%, 45%, and 50%: (a) concentration of deposition dust particles; (b) deposition rate
圖 7 不同過濾速度和孔隙率下沉積塵粒分布圖。（a）u = 3 m·min?1，ε = 40%；（b）u = 1 m·min?1，ε = 40%；（c）u = 1 m·min?1，ε = 45%；（d）u = 1 m·min?1，ε = 50%
Figure 7. Distribution of deposition dust particles at different filtration velocities and porosities: (a) u = 3 m·min?1, ε = 40%; (b) u = 1 m·min?1, ε = 40%; (c) u = 1 m·min?1, ε = 45%; (d) u = 1 m·min?1, ε = 50%
圖 8 反吹時間與沉積塵粒濃度和塵粒脫附率關系。（a）沉積塵粒濃度；（b）塵粒脫附率
Figure 8. Concentration of deposition dust particles and dust removal rate at different times with the pulse jet blowback pressures of 0.1, 0.3, and 0.5 MPa: (a) concentration of deposition dust particles; (b) dust removal rate
圖 9 反吹時塵粒分布圖（a）和壓力分布圖（b）
Figure 9. Distribution of dust particles (a) and pressure (b) at a pulse jet blowback pressure of 0.1 MPa and blowback time of 0.006 s
圖 10 不同反吹壓力下塵粒分布圖。（a）P2 = 0.3 MPa，T = 0.008 s；（b）P2 = 0.5 MPa，T = 0.008 s
Figure 10. Dust particle distribution under different blowback pressures: (a) P2 = 0.3 MPa, T = 0.008 s; (b) P2 = 0.5 MPa, T = 0.008 s
圖 11 陶瓷膜工作時間對沉積塵粒濃度和沉積速率的影響
Figure 11. Concentration of deposition dust particles and dust deposition rate during filtration and pulse jet cleaning
圖 12 不同時間下沉積塵粒和壓力分布圖。（a）0.03 s；（b）0.035 s；（c）0.095 s
Figure 12. Distribution of dust particles and pressure under different time: (a) 0.003 s, (b) 0.035 s, (c) 0.095 s
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