Mixers propeller type

Side entering mixers are used for blending pui-poses. The side entering propeller type mixer is economical and establishes an effective flow pattern in almost any size tank. Because the shaft seal is below the liquid level, its use in fluids without corrosive and erosive properties is usually ideal. 

There are two primary types of mixers propeller/paddle and screw. Screw mixers can be further divided into two types batch and mixer-extruder. 

Figure 38.2 Side-entering propeller-type mixer...

Installation of propeller-type mixers varies greatly, depending on the specific application. Top-entering mixers utilize either a clamp- or flange-type mounting. It is important that the mixer be installed so the propeller or paddle placement is at a point within the tank, vessel, or piping that assures proper mixing. Vendor recommendations found in O M manuals should be followed to ensure proper operation of the mixer. 

Use well-designed, specialized polymer dissolution systems wherever possible (such as those from the U.S. Filter, Inc. subsidiary, Strandco ), especially for emulsion polymers, rather than simple dissolving tanks and mixers with propeller-type impellers. This prevents undissolved lumps of polymer (fish-eyes) and the breakdown of polymer chains. Always install a strainer to prevent possible pump clogging. 

The rheo cells can easily be replaced by various types of mixers, propellers or paddles (Figure 2.1.10). It is then possible to analyze the temporal evolution of chemical/physical reactions of mixing, demixing and sedimentation of materials in process engineering, e.g., during the mash process or fermentation [28, 29]. The stirring mechanics and speed can be optimized for various materials of different particle sizes and viscosity. 

A propeller-type mixer is satisfactory for preparing experimental batches of syntactic foam, but on a commercial scale a kneader-type... 

In a vertical cylindrical tank, the depth of the liquid should be equal to or somewhat greater than the diameter of the tank. If greater depth is desired, two or more impellers are mounted on the same shaft, and each impeller acts as a separate mixer. Two circulation currents are generated for each impeller, as shown in Fig. 9.5. The bottom impeller, either of the turbine or the propeller type, is mounted about one impeller diameter above the bottom of the tank. 

While stirring with a propeller-type mixer, add the Carbopol 934 and Morpholine in that order. 

Propeller types pump li( uid. Every revolution of a square pitch prop discharges a column of liquid approximately equal to the diamf ter of the propeller. The flow is iixial. Such pumps are used primarily for high-speed applications and side-entry mixers. Duel propellers are used on vessels with H/D ratios greater than 1. The axial flow decreases mLx time. They are heavier and cost more than pitched-blade turbines. Propeller-to-vessel-diameter ratio is usually Vs- A propeller-type impeller is used for high flow. 

Submersible-motor Paddle mixer Long shaft mixer Paddle mixer Stick-type propeller propeller mixer (vertical digester) (horizontal digester) mixer... 

In some respects, the propeller-type mixer causes continuous mass flow against a stationary flat bottom. If the speed of rotation is not sufficient, a stagnation area develops. The levels of turbulence in the tank, as well as the shape of the bottom of the tank. 

Batch Mixing Equipment. Melt mixing can be carried out in a variety of heated mixing equipment. In order of increasing effectiveness, these include vessels stirred with propellers, vessels with high shear (Cowles-type) dispersers, planetary mixers (Hobart-type), internal mixers (Sigma-blade or Banbury type), and modifications of these. 

Finish removers are manufactured in open or closed ketdes. Closed ketdes are preferred because they prevent solvent loss and exposure to personnel. To reduce air emissions from the solvents, condensers are employed on vent stacks. Mild steel or black iron ketdes are used for neutral or basic removers stainless steel (316 or 317) or reinforced polyethylene ketdes are used for acidic removers. The ketdes are heated to increase dispersion of paraffin waxes and aid in the mixing of other ingredients. Electric or air driven motors drive either sweeping blade or propeller mixers that give sufficient lift to rotate and mix the Hquid. Dispenser-type mixers are used to manufacture thick and viscous removers. Ketde, fittings, mixer, and fill equipment must be fabricated with materials resistant to the chemicals in remover formulas. 

When abrasive solid particles must be suspended, maintenance costs for the submerged shaft seal of a side-entering propeller may become high enough to make this type of mixer an uneconomical choice. 

Variation in the actual brake horsepower required to operate a mixer is the primary indicator of its performance envelope. Mixer design, whether propeller- or screw-type, is based on the viscosity of both the incoming and finished product. These variables determine the brake horsepower required to drive the mixer, which will follow variations in the viscosity of the products being mixed. As the viscosity increases so will the brake horsepower demand. Conversely, as the viscosity decreases, so will the horsepower required driving the mixer. 

Both propeller and screw mixers have specific setup requirements. In the case of propeller/paddle-type... 

Fig. 2.1.10 Complete cell with a paddle with one row of holes (blade stirrer), mounted in a glass tube (left), a second paddle with two rows of holes (middle) and a propeller mounted on a rotation axis (right) used to study the velocity distribution in different types of mixers.

Mix Process. Usually all liquid components (except the diisocyanate), antioxidants, ballistic additives, bonding agents, and metallic fuel are blended together and transferred to the mixer, a jacketed stainless steel vessel with provisions for vacuum mixing. This mixer is not much different from those found in the bread-baking industry, from which, in fact, this one was derived. Depending on the type of propellant, the... 

Another type of testing, that of electrostatic sensitivity, has been demonstrated in some cases to be more properly a delicate test of the ignitability of the material under localized thermal stress which correlates best to the friction sensitivity of the system under test rather than to electrostatic hazards. On the other hand, electrostatic tests done in the supposed atmosphere above a propellant mixer were reduced in absolute value by more than an order of magnitude when the ammonium perchlorate dust actually present was introduced in the test since this altered the potential path for spark discharge within the system. 

The final mixing takes place in a large Werner-Pfleiderer (or Baker-Perkins) type sealed mixer of the type extensively used in smokeless powder manufacture (Fig. 206). A capacity up to 2000 lb is used in the case of thiokol propellants. After the premix has been added to the mixer, the finally ground oxidant is added. This material is conveyed to the mixer in a closed container and is added so that the... 

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