Paddle agitation

Types of agitators to use for fluids of various viscosities 13 Propeller agitators — fluids below 3,000 cp Turbine agitators — fluids at 3,000-50,000 cp Paddle agitators — fluids at 50,000-90,000 cp Modified paddle agitators — fluids at 90,000-1,000,000 cp... 

Four blade pitched paddle agitator Vessel fittings omitted for clarity... 

Data for a paddle agitator were correlated by a similar equation, except that the exponent on (hp.) was 0.53. Limited data with the vaned disk agitator in the 6-in. diameter vessel showed that the absorption coefficient increased with liquid depth as follows if the power input per volume was kept constant ... 

Hirsekorn and Miller (H2) made visual qualitative observations of the suspension of solids by paddle agitation in very viscous liquids (to about 50,000 cp.). For low impeller Reynolds numbers (about 10) in geometrically similar systems (6-, 12-, 18-in. vessels) the major factor in effecting particle suspension appeared to be power input per unit volume. In any given case the power required for complete suspension of all the particles was affected by system geometry and the settling velocity of the solids. No detailed correlation of the observations was presented. 

Pursell (P8) continued the study of paddle agitators, and developed a correlation given in Table VI. This equation fits his data in addition to the data obtained by previous investigators using paddle agitators. It will be noted that he has included terms to account for the effect of blade width W and the ratio of tank diameter to impeller diameter. 

In summary, because of the uncertain effect of system geometry, it is recommended that for purposes of estimation or design Table VI should be used to select a correlation which was developed from tests on a system as similar as possible to the one under consideration. For jacketed vessels using paddle agitators the correlation of Pursell is indicated. For other jacketed vessels or for the case of helical coils... 

Axis of paddle agitator, 2 tankof mixing system, 3 paddle of mixing system,... 

Both use a paddle agitator that also serves to prevent coking. 

HCRP = paddle agitator HCSP (Nonhebel and Moss, 1971). 

HCRP = paddle agitator HCSP = ribbon agitator PVP (Nonhebel and Moss, 1971). (Walas, 1988). 

The paddle agitator (without baffles) consists merely of arms placed on a vertical shaft inserted through the top of a tank. It is rotated by any suitable motive power (this type is very seldom used without baffles but in order to bring out the faults of this class better we will discuss it briefly). 

A combination of the propeller and paddle-agitator is got by inclining the bottom set of paddles so as to keep an upward motion of the solution in the tank. 

Blasinski H., Rzyski E., Mixing of non-Newtonian fluids with turbine, propeller, and paddle agitators, Int. Chem. Engng. 16 (1976) 4, p. 751-754... 

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