Please share your views.Īgitator shaft length should be calculated on which basis. (Otherwise i have to change my design which i have just freezed for my on going project. I hope this is inline to what is normally practiced. Sometimes in case of elipticle bottom the bottommost impeller dia is kept smaller compare to upper impeller dia. The graphs are easily available for various types of agitator as Nre vs Np. and type of agitator (pitch blade, flat blade etc.). The minimum distance between two impeller has to be same as impeller diameter. If this ratio is greater than 1.2 then go for two impellers else take one.Īs far as distance is concern, the distance between tank bottom to bottommost impeller centre line has to be 1/3 times of tank inside diameter. of impeller is decided by finding the ratio of (height of liquid level * sp. Let me put forward my views and plz correct me if wrong. Length of Agitator Shaft = distance between bearing & agitator (lower impeller) Thus, Impeller Clearance is Z/3 or T/3 based on the above table. Viscosity, cP (Pa.s):: Max Level, Z/T:: Number of Impellers:: Impeller Clearance (Lower : Upper) This method takes into consideration liquid level (Z), tank diameter (T), number of impellers and fluid viscosity. (Ref.: EEUA, page 5).Īnother method to determine lower impeller clearance is given in "Handbook of Chemical Engineering Calculations" By - Nicholas P. Per unit volume increases as the filling ratio departs from unity. Liquid, however, a filling ratio of 2 is recommended in order to maintain a sufficiently long period of contact between the gas & the liquid.
The filling ratio is the ratio of Liquid Depth to Tank Diameter, which is normally between 0.5 - 1.5. Ratio of bottom clearance to vessel diameter should be between 0.1 - 0.4 for a filling ratio of 1.0īut for an Anchor Impeller, clearance is determined by mechanical considerations a clearance of 1in. Referring to procedures laid down in Engineering Equipment Users Association (EEAU) handbook, EEUA HAND BOOK NO.9,Ĭlearance between Impeller & the bottom of the tank:
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