Pulse-Jet Q: How can the blown-away particles by the on-line cleaning process be collected? Q: Felted fabric or woven fabric?
Air/Cloth Ratio Filtration velocity (average velocity) Q: If thicker fabric is needed to sustain the high force, is its operating cost higher?
Filtration Mechanisms <ul><li>Diffusion (Lee & Liu, 1982) </li></ul>Lee, K.W. & Liu, B.Y.H., Aerosol Sci. Technol. , 1 :47-61, 1982 Q: How does efficiency change wrt d p ? Q: How to increase efficiency by diffusion? http://aerosol.ees.ufl.edu/respiratory/section04.html
<ul><li>Impaction (Yeh & Liu, 1974) </li></ul>Yeh. H.C. & Liu, B.Y.H., J. Aerosol Sci. , 5: 191-217, 1974 Q: How to increase impaction efficiency? Q: How does efficiency change wrt dp ? ( J = 2 for R > 0.4)
<ul><li>Interception (Krish & Stechkina, 1978) </li></ul>Krish, A. A. & Stechkina, I. B., “The theory of Aerosol Filtration with Fibrous Filters”, in Fundamentals of Aerosol Science , Ed. Shaw, D. T., Wiley, 1978. Q: How to increase interception efficiency? Fat Man’s Misery, Mammoth Cave NP
<ul><li>Gravitational Settling </li></ul><ul><li>Total Single Fiber Efficiency </li></ul><ul><li>Total Filter Efficiency </li></ul>S f : Solidarity factor Q: How does the filter efficiency change wrt particle size?
<ul><li>H = 1mm </li></ul><ul><li>= 0.05 </li></ul><ul><li>d f = 2 m </li></ul><ul><li>U 0 =10 cm/s </li></ul>Q: Should we increase or decrease flow velocity in order to increase collection efficiency for (a) tobacco smoke, (b) cement dust?
Parallel Flow Operation Q: How do you determine when to clean?
Pressure Drop (Filter Drag Model) Areal Dust Density Filter drag K 1 & K 2 to be determined empirically (resistance factor) P f : fabric pressure drop P f : particle layer pressure drop P s : structure pressure drop Q: What is the pressure drop after 100 minutes of operation? L = 5 g/m 3 and V = 0.9 m/min. K 2 K 1 990 60 690 30 610 20 505 10 380 5 150 0 P, Pa Time (min)
Time to clean Flow rate Filtering velocity Q: What are the parameters that affect our decision on the number of compartments to be used?
Areal dust density Filter drag Actual filtering velocity Pressure drop
<ul><li>Ex. Calculate the max pressure drop that must be supplied for the following baghouse for a filtration time of 60 minutes: K 1 = 1 inch H 2 O-min/ft, K 2 = 0.003 inch H 2 O-min-ft/grain, t c = 4 min, 5 compartments, L = 10 grain/ft 3 , Q = 40000 ft 3 /min, A c = 4000 ft 2 /compartment. </li></ul>