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Topic: Ventury Scrubber for Electric Arc Wire Thermal Spray Process  (Read 3972 times)

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sleong76

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Ventury Scrubber for Electric Arc Wire Thermal Spray Process
« on: July 25, 2007, 03:36:02 AM »
Good day! I am new to the group and would like to share my problem with expertise out there.

Recently we have installed one set of ventury scrubber for the electric arc wire thermal spray process. The process mainly is anti-corrosion surface coating for semiconductor parts. It involves the usage of arc wire thermal spray equipment, which emmitted mainly aluminium sludge and particulates.

We, initially, thought of using a bag house dust collector to capture the pollutants but afraid of the spark, which might burns the bag. Hence, we have installed a ventury scrubber to capture the spark and particulates.

Unfortunately, the result are not as good as calculation. We still can see particulates coming out from the chimney. The pollutants are small, well, I do not have the size, but I have use 2 micron for the sizing. (As 10 micron is the smallest size of particulates visible to naked human eye). Please see the sizing assumption as follow (Johnstone Equation):

Air volume, Q = 7000 cfm
Efficiency, n = 99%
Diameter of particle, dp = 2 micron
Liquid-gas ration. Ql/Qg = 22 l/min/ 1000cfm
Correlation cofficiency, k = 0.15
Diameter droplet. d = 48 micron
Dust density = 165 lb/ft3

By calculation, the throat size = 13.75 inch
the main duct size = 18 inch
Pressure drop of ventury throat = 2.98 inch H20 (Empirical Equation)

I am just wondering what went wrong!? Could the expert tell me why?
Thanks. I am ready for any other details if required.