Flat-blade turbine

Rakes, Gates Spirals, Anchors, Paddles Propellers Axial Flow Turbines Flat Blade Turbine Bar Turbine Bladeless Impeller Close Clearance Impeller and Stator... 

Turbine,Flat Blade (6) Turbine, Pitched Blade (6)... 

Turbine flowmeters, liquid meters 271 Turbines, flat-bladed 295... 

Turbine, flat blades, transfer to coil, baffled, Re, 2000-700,000 ... 

For Rushton turbines (flat-blade disc turbines), the following equation can be used (Nouri and Hockey, 1998) ... 

Propeller Rushton turbine Flat-blade turbine Pitch-blade turbine Anchor Hehcal ribbon... 

The decay constant is the key to the mixing rate number defined for Re > lO" by N/ D/TY = 0.5 for a disk flat blade turbine (DFBT), and N/ (D/TY = 0.9 for the propeUer. Therefore, power required to achieve any degree of uniformity in a fixed time is proportional to D and D for DFBT and propeUer, respectively. 

The most common impellers are the marine impeller or disc flat-blade turbine the flowpatterns which typically result are illustrated in Fig. 15-22. 

The power for agitation of two-phase mixtures in vessels such as these is given by the cuiwes in Fig. 15-23. At low levels of power input, the dispersed phase holdup in the vessel ((j)/ ) can be less than the value in the feed (( )df) it will approach the value in the feed as the agitation is increased. Treybal Mass Transfer Operations, 3d ed., McGraw-HiU, New York, 1980) gives the following correlations for estimation of the dispersed phase holdup based on power and physical properties for disc flat-blade turbines ... 

FK . 15-22 Uqiiid agitation by a disc flat blade turbine in the presence of a gas-liquid interface a) without wall baffles, (h) with wall baffles, and (c) in full vessels without a gas-bqiiid interface (continuous flow) and without baffles. [Couitesy Treyhal, Mass Transfer Operations, 3rd ed., p. 148, McGraw-Hill, NY,... 

FIG. 15-23 Power for agitation impellers immersed in single-phase liquids, baffled vessels with a gas-liquid surface [except curves (c) and (g)]. Curves correspond to (a) marine impellers, (h) flat-blade turbines, w = dj/5, (c) disk flat-blade turbines witb and without a gas-liquid surface, (d) curved-blade turbines, (e) pitcbed-blade turbines, (g) flat-blade turbines, no baffles, no gas-liquid interface, no vortex. 

Curves h to e are for turbines located at a distance C = d or greater from tbe bottom of tbe vessel. For disk flat-blade turbines, curve c, there is essentially no effect of d /dj in tbe range 0.15 to 0.50. For open types, curve h, tbe effect of d /dj may be strong, depending upon tbe group nh/dt. 

Curve g is for disk flat-blade turbines operated in unbaffled vessels filled witb liquid, covered, so tbat no vortex forms. If baffles are present, tbe power characteristics at high Reynolds numbers are essentially tbe same as curve h for baffled open vessels, witb only a slight increase in power. 

For tbe flat-blade disk turbines, at a spacing equal to 1.5d or greater, tbe combined power for both will approximate twice tbat for a single turbine. 

Radial-flow impellers include the flat-blade disc turbine, Fig. 18-4, which is labeled an RlOO. This generates a radial flow pattern at all Reynolds numbers. Figure 18-17 is the diagram of Reynolds num-ber/power number curve, which allows one to calculate the power knowing the speed and diameter of the impeller. The impeller shown in Fig. 18-4 typically gives high shear rates and relatively low pumping capacity. 

The most comprehensive correlation for heat transfer to vertical baffle-type coils is for a disk flat-blade turbine over the Reynolds number range lO to (2)(10 ) ... 

For non-New tonian fluids, viscosity data are very important. Every impeller has an average fluid shear rate related to speed. For example, foi a flat blade turbine impeller, the average impeller zone fluid shear rate is 11 times the operating speed. The most exact method to obtain the viscosity is by using a standard mixing tank and impeller as a viscosimeter. By measuring the pow er response on a small scale mixer, the viscosity at shear rates similar to that in the full scale unit is obtained. 

Paddle A paddle is similar to a turbine impeller but typically has only two large blades and operates at lower speeds than a turbine. They are primarily used in high viscosity mixing operations. In European and Japanese literature the term "paddle" also is used to describe the flat blade and pitched blade turbines discussed above. The term "turbine" generally is reserved for disk turbines. 

Figure 7-4. Six flat blade turbine. (Source Holland, F. A. and Bragg, R. Fluid Flow for Chemioal Engineers, 2nd ed., Edward Arnold, 1995.)...

Flat-blade disc turbine (ftushton turbine)... 

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