Impellers propeller

Frame-mounted ANSIB73.1 Wet-pit volute Axial flow impeller (propeller) volute type (horizontal or vertical)... 

The draft tubes of the reaetor are hollow in order to allow eooling or heating fluid to eireulate. The 300-ml laboratory-seale reaetor (1) is geometrieally similar to the larger reaetors. A marine-type impeller (propeller) provides a smooth and even flow field throughout the reaetor. 

Ni-Si recovery of HP Processes involving cone. H2SO4 processes. Sulphur stripping columns. Distillation columns containing acidic chlorides. Handling acid sludges processes impellers, propeller shafts, fasteners. Demisters in desalination plants refrigerating brines. Salt production. Evaporators steel... 

Erosion Similar to abrasion cutting in ductile metal fracture (of brittle material) very small chips or particles (e.g., impellers, propellers, fans) Reduce fluid velocity to eliminate turbulence select harder alloy (high chromium) hard coatings such as cement lined pipe, rubber lining... 

Liquid mixing impellers propeller,turbine, anchor... 

Once the swirling is stopped, the specific flow pattern in the vessel depends on the type of impeller. Propeller agitators usually drive the liquid down to the bottom of the tank, where the stream spreads radially in all directions toward the wall, flows upward along the wall, and returns to the suction of the propeller from the top. Propellers are used when strong vertical currents are desired, e.g., when heavy solid particles are to be kept in suspension. They are not ordinarily used when the viscosity of the liquid is greater than about 50 P. Pitched-blade turbines with 45° down-thrusting blades are also used to provide strong axial flow for suspension of solids. 

Impeller Propeller Rushton Helical Ribbon Anchor... 

For double suction pumps, using the HI convention, is taken as the total pump flow, although some pubHcations use half-flow, ie, flow per impeller eye. For multistage pumps, the developed head must be taken per stage for the NS calculation. By definition (eq. 9), high head, low flow pumps have low specific speed low head, high flow pumps, such as turbine and propeller pumps, have high specific speed. 

Uses. Uses for copper—siUcon alloys are siUcon bronze, UNS C 87200, as bearings, pumps, valve parts, marine fittings, and corrosion-resistant castings siUcon brass UNS C 87400 as bearings, gears, impellers, valve stems, and clamps and siUcon brass UNS C 87500 as small propellers, valve stems, gears, and bearings. 

David and Colvin [Am. Inst. Chem. Eng. J., 7, 72 (1961)]. Continuous heat transfer between kerosine and water unbaffled vessel. Open impellers (paddles and propellers) are better than closed (centrifugal and disk impellers) at the same tip speed. 

Axial-Flow Impellers Axial-flow impellers include all impellers in which the blade makes an angle of less than 90° with the plane of rotation. Propellers and pitched-blade turbines, as illustrated in Figs. 18-8 and 18-3, are representative axial-flow impellers. 

Axial-tlow impellers rnav also be mounted near the bottom of the cylindrical wall of a cssel as shown in Fig, 18-10, Such side-entering agitators are used to blend low- iscositv fluids [<(), Pa-s (100 cP)] or to keep slowly settling sediment suspended in tanks as large as some 4000 rn (1(P gal). Mixing of paper pulp i.s often carried out by sideentering propellers. 

Close-Clearance Stirrers For some pseiidoplastic fluid systems stagnant fluid may be found next to the -essel walls in parts remote from propeller or turbine impellers. In such cases, an anchor impeller maybe used (Fig, 18-6), The fluid flow is principally circular or helical (see Fig, 18-7) in the direction of rotation of the anchor. Whether substantial axial or radial fluid motion also occurs depends on the fluid iscosity and the design of the upper blade-supporting spokes. Anchor agitators are used particularly to obtain irnpro ed heat transfer in high-consistency fluids,... 

When fluid viscosity is low and flow is turbulent, an impeller moves fluids by an increase in momentum from the blades mich exert a force on the fluid. The blades of rotating propellers and turbines change the direction and increase the velocity of the fluids. 

Side-Entering Impellers For vessels greater than 4 m (1000 gal), a side-entering propeller agitator (Fig. 18-9) mav be more economical than a top-mounted impeller on a centered vertical shaft. 

I = tip speed of the propeller or impeller, m/s p = crystal density, g/ciTr... 

Batch Stirred Tanks Tanks agitated by coaxial impellers (turbines, paddles, or propellers) are commonly used for batch dissolution of solids in liquids and may be used for leaching fine solids. Insofar as the controlhng rate in the mass transfer is the rate of transfer of mate-... 

A basic stirred tank design is shown in Fig. 23-30. Height to diameter ratio is H/D = 2 to 3. Heat transfer may be provided through a jacket or internal coils. Baffles prevent movement of the mass as a whole. A draft tube enhances vertical circulation. The vapor space is about 20 percent of the total volume. A hollow shaft and impeller increase gas circulation (as in Fig. 23-31). A splasher can be attached to the shaft at the hquid surface to improve entrainment of gas. A variety of impellers is in use. The pitched propeller moves the liquid axially, the flat blade moves it radially, and inclined blades move it both axially and radially. The anchor and some other designs are suited to viscous hquids. 

FIG. 23-30 Basic stirred tank design and selected lands of impellers, (h) Propeller, (c) Turbine, (d) Hollow, (e) Anchor,... 

Mechanical agitation is needed to break up the gas bubbles but must avoid rupturing the cells. The disk turbine with radial action is most suitable. It can tolerate a superficial gas velocity up to 120 m/h. (394 ft/h) without flooding, whereas the propeller is limited to about 20 i7i/h (66 ft/h). When flooding occurs, the impeller is working in a gas phase and cannot assist the transfer of gas to the liquid phase. Power input by agitation and air sparger is 1 to 4 W/L (97 to 387 Btu/[fF-h]) of liquid. 

The pump impeller receives the pumped liquid and imparts velocity to it with help from the electric motor, or driver. The impeller itself looks like a modified boat or airplane propeller. Actually, boat propellers are axial flow impellers. Airplane propellers are axial flow impellers also, except that they are adapted to handle air. 

For turbine mixers that the width of a baffle should not exceed more than one-twelfth of the tank diameter and, for propeller mixers, no more than one-eighteenth the tank diameter. With side-entering, inclined or off-center propellers, as shown in Figure 13, baffles are not required. Instead, shrouded impellers and diffuser rings may be used to suppress vortex formation. These devices contribute to flow resistance and reduce circulation by creating intense shear and abnormal turbulence... 

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