This document summarizes different types of mixers used in industrial processes. It describes static mixers, which mix fluids using inserts in pipes without moving parts, including helical element mixers and turbulent vortex mixers. It also describes intensive mixers like change-can mixers, kneaders including sigma and Banbury mixers, mixer extruders, and muller mixers. Finally, it discusses heating and cooling mixers like high speed mixers and cooling mixers used to precisely control temperature during industrial mixing.
2. Contents
•Static Mixers: Helical Element Mixers and
Turbulent Vortex Mixer or High Shear Mixers(HSM)
•Intensive Mixers: Change-can mixers, Kneaders:
Double-arm kneader (Sigma mixer) and Banbury mixer,
Mixer extruder and Muller mixer
•Heating and Cooling Mixers
3. Static Mixers
• What are static mixers?
• These are the mixers which are applicable to gases or low
viscosity liquids which are blended by passing them together
through a length of a open pipe or a pipe containing orifice
plates or segmental baffles.
• So the mixing is done by the flow of the gases or liquids inside
the pipe only.
• Under appropriate conditions the pipe length may be as short as
5 to 10 pipe diameters, but 50 to 100 pipe diameters is
recommended.
• More difficult mixing tasks are accomplished by static mixers,
commercial devices which consist of a series of metal inserts
placed in the pipe.
4. • Types of Static Mixers:
• Helical element mixer
• Turbulent vortex mixer
5. Helical Element Mixers
• Helical-element mixer is mainly used with viscous liquids
and pastes.
• This mixers provide continuous in- line mixing of fluids,
gases, or powders using no moving components. That’s
why also known as motionless mixers.
• Alternating helical mixing elements provide thorough
radial and axial blending in a short length by dividing the
main flow into two equal streams as material passes each
element.
• Each element 1 to 1.5 pipe diameters in length, divides the
stream into two, gives it a 180 degree twist, and delivers it
to the next element.
7. • The second element divides the already divided stream and
twists it 180 degree in the opposite direction.
• Successive elements further subdivide the stream until the
striations are so thin that the blending process can be finished
by molecular diffusion.
• The number of divisions increases by 2^n, where “n” is the
number of elements.
• These mixers are custom-designed for each application. The
number of elements is determined by the specific application.
• Mixers can be jacketed or electrically heated, and supplied with
fixed or removable mixer elements.
• Sizes range from 2mm to 2m in diameter.
• The recommended number of helical elements is 6 for Re = 100
to 1000, 12 for Re = 10 to 100, and 18 for Re less than 10.
8. • More elements are needed for very viscous liquids because of
the lower molecular diffusivity.
• The pressure drop per unit length is about 6 times that in the
empty pipe when Re less than 10, but increases to about 50 to
100 times that in the empty pipe when Re = 2000.
9.
10. Advantages
• Provide excellent mixing or blending of two liquids, a liquid
and gas, two gases, or two powders
• Plug flow device (first in, first out)
• Short, uniform residence time
• Uniform temperature, no “hot spots”
• Smooth shape and edge sealing of elements allows no dead
spaces for product to hangup of degrade
• Can be used for materials with low to high viscosities, upto
20000 poise or more
• No maintenance since no moving parts
• Can process highly corrosive materials
• Can be used in high viscosity heat exchangers to increase heat
transfer coefficients three to four times standard open tube
designs
11. Turbulent Vortex Mixer or High Shear
Mixer
• This is also used for gases and low-viscosity liquids as shown in
figure (b).
• This also provide continuous in-line mixing of fluids, gases, or
powders using no moving components.
• Each element of this mixer has four tabs protruding at an angle
into the pipe.
• Counter-rotating longitudinal vortices are formed in the wakes
of the tabs, providing efficient blending of the liquids or gases
after only two to four elements.
• The unique, intermeshing element design provides high levels of
mixing in a very short overall length and product residence time.
12. • The pressure drop per unit length is 25 to 40 times the value
for the empty pipe at Re = 10^4 to 10^5, but since only a few
elements are needed, the overall pressure drop is not large.
• The design is also adaptable to many types of applications.
• Figure (b) :
Turbulent Vortex Mixer;
13.
14. • These mixers are custom-designed for each application. The
number of elements and design specifics are determined by
the specific application.
• Mixers can be jacketed or electrically heated, and supplied
with fixed or removable mixer elements.
• Sizes range from 2mm to 2m and larger in diameter.
15. Advantages
• Provide excellent mixing or blending of two liquids, a liquid and
gas, two gases, or two powders
• Plug flow device (first in, first out)
• Short, uniform residence time
• Uniform temperature, no “hot spots”
• Can be used for materials with low to high viscosities, upto
20000 poise or more
• No maintenance since no moving parts
• Can process highly corrosive materials
• High degree of mixing in short overall length
16. Applications
Processes: Industries:
Mixing Powder mixing Polymer processing
Injection molding
Reacting Liquid mixing Fiber production Fine
films
Coloring Laminar and turbul- Plastics extrusion
Polymerzation ent mixing applications Foods including edible
Heat exchange Obtaining product tem- oil, ice cream, mayonnai
pH control perature uniformity -se, chocolate, beverage,
Neutralization Extrusion milk, yogurt, and cheese
Diffusion Compounding Pharmaceutical
Gas mixing
17. Materials
Elements can be constructed of :
• Stainless steel
• Hastelloy
• Teflon
• Carbon steel
• PVC
• PP (polypropylene)
• PE (polyethylene)
• FRP (fiber reinforced plastics)
• Tantalum
• Kynar
• Inconell and many other materials
18. Intensive Mixers
Intensive mixers includes: change-can mixers, kneader (
dispersor or masticator ), mixer extruder and muller mixers.
Change-can mixer:
• blend viscous liquids or light pastes as in food processing or
paint manufacture.
• a small removable can 5-100 gal in size holds the material
to be mixed.
• In pony mixer, the agitator consists of several vertical
blades held on a rotating head and positioned near the
walls of the can.
• The blades are slightly twisted.
19. • The agitator is mounted eccentrically wrt the axis of the can.
• The can rests on a turntable driven in a direction opposite to
that of the agitator.
• When mixing is complete, the agitator head is raised, lifting the
blades put of the can, the blades are wiped clean, and the can is
replaced with another containing a new batch.
• In beater mixer, the can or vessel is stationary, the agitator has
a planetary motion, are shaped to pass with close clearance
over the side and bottom of the mixing vessel.
20.
21. KNEADERS:
General Information:
• Kneaders are high intensive mixers for cohesive solid systems.
• Some kneaders achieve their mixing action by squashing the
mass flat, holding it and squashing it again.
• Others tear the mass apart and shear it between a moving blade
and a stationary surface. There are two main types of kneaders:
• There are two main types of kneaders:
1. Double arm kneader
2. Banbury Mixers
22. Double arm Kneader
• A two arm kneader handles suspensions, paste and light
plastic masses.
• All double arm kneader mixers are equipped with two mixing
blades placed in W-shaped horizontal trough.
• The commonly used blades are sigma blade, spiral blade,
masticator blade and naben blade.
• The blades rotate towards each other at the same or
differential speed.
• The rotation of blade is either tangential to each other or the
blade may overlap within trough.
23.
24. • The blades pass the container walls and each other at a close
clearance 2-3 mm resulting in homogeneous mixture.
• The close clearance produce very high shearing action
thereby reducing any large particles.
• Homogeneous mixing is achieved within 10-15 minutes and
mixing homogeneity is 99%.
• The power consumption is very high compared to other types
of mixers.
25. • A disperser is heavier in construction and draws more power
than a kneader, it works additives and coloring agents into
stiff materials.
• A masticator is still heavier and draws even more power. It
can disintegrate scrap rubber and compound the toughest
plastic masses.
• Are often called intensive mixers.
26. SIGMA MIXER:
• The sigma blade mixer is a commonly used and most popular
mixer for high viscosity materials.
• It belongs to the family of double arm kneader mixers.
• It consist of a short rectangular trough with a saddle shaped
bottom. Two counter rotating blades are incorporated in the
trough.
• The blades are so placed and shaped that the material turned
up by one blade is immediately turned under the adjacent
one.
• The blades are driven through a gear mechanisam provided at
either or both ends.
27. • The trough may be open or closed and may be jacketed for
heating or cooling. The machine is operated in a batch wise
fashion.
• The machine can be emptied through a bottom valve where
100% discharge or thorough cleaning, between batches, is not
as essential.
• The material to be kneaded is dropped into the trough and
mixed for a period of about 5-20 minutes or longer.
• The trough is then unloaded by tilting it.
28.
29. Blades for Double Arm Kneader
• Various designs of mixing blades are in following figure. The
sigma blade is most widely used.
• The mixer employing sigma blades is capable of starting and
operating with either liquids or solids or a combination of both.
• The sigma blade has good mixing action and is relatively easy to
clean when sticky materials are being handled.
• The dispersion blade builds up high shear forces required to
disperse powder or liquids into plastic or to rubbery masses.
• The double-naben blade is useful for heavy plastic materials.
30.
31.
32. Banbury Mixer
• A banbury mixer is the most common internal mixer. It is a heavy
duty machine with two blades each rotating in a cylindrical
sheet, but these cylinders partly intersect with each other.
• The blade is pear shaped, but the projection is spiral along the
axis and the two spirals interlock.
• The machine operates at a speed of 40 rpm or lower.
• The clearance between the blades and the walls is extremely
small, and it is here that the mixing action takes place.
• The material is fed from above and held in the trough during
mixing by an air-operated piston under a pressure of 1-10
kgf/cm^2.
33. • Mixed material is discharged through a heavy sliding door
which is provided at the bottom of the trough.
• The heat generated is taken out by spraying cooling water on
the walls of the mixing chamber and circulating through the
hollow agitator shafts during operation.
• Used mainly in plastic and rubber industries.
35. Muller Mixers
• A muller mixer consists of a pan incorporating muller wheels.
• In one of the designs of muller mixer , the pan is stationary and
wheels rotate; while in the other design, the pan is rotated and
the axis of the wheels is held stationary.
• In the stationary pan muller mixer, the central vertical shaft is
driven, causing the muller wheels to roll in a circular path over a
layer solids on the pan floor.
• Plows direct the solids under the muller wheels during mixing or
to an opening in the pan floor for the discharge of the mixer at
the end of the cycle.
36. • The muller wheels crush the material, breaking down lumps
and agglomerates.
• Capacity of the muller mixer ranges from a fraction of cubic
meter to more than 1.6 m^3 and the corresponding power
requirements ranges from 1/3 to 75hp.
• Mullers are used for handling batches of heavy solids and
pastes.
• These are also effective in uniformly coating the particles of
granular solids with a small amount of liquid.
37. Mixer Extruders
• Extruders are used to mix liquid-solid systems and to extrude
molten or plasticized polymers to semi-final and final product
forms.
• The feed to an extruder usually contains the base polymer in
granular or powder form, together with additives such as
stabilizers, plasticizers, and coloring pigments.
• The base polymer and additive are combined in a feed tunnel,
providing a relatively homogeneous mass that is then extruded
in the main working chamber.
• During processing in the extruder, the polymer is melted and the
additives are mixed.
38. • The feed enters a channel where it is mixed by one or two
rotating screws.
• The extrudate product is delivered at high pressure and at a
controlled rate from the extruder for shaping by a die or mold.
39. Applications:
• Plastic industry
• Preparation of additives such as pigments and resins
• Used to process cat and dog foods
• Floating and sinking fish feeds for the aquaculture and fish
farming
40. Heating and Cooling Mixers
High Speed Mixer:
• Bigger vessel with double wall jacket construction and perfect
height to dia ratio.
• Inside vessel is made from S.S 304 and mirror polished to avoid
depositing of material.
• Adjustable baffle plate is provided to achieve rapid and better
dispersion.
• Efficient production without cross- contamination and free from
moisture.
• Lower scrap rates in the extrusion due to consistence quality of
the dry blend.
41. • Excellent dispersion of the additives even with higher calcium
loading.
• Precise peripheral speed of mixing tool.
• Special S.S. blades having abrasive and wear resistance,
balanced with proper design for excellent mixing and higher
blade life.
• Heavy duty bearing housing with best quality bearings for
trouble free working.
• Best quality material of all key components.
42.
43. Cooling Mixer
• Bigger S.S. 304 Vessel mirror polished with mild steel jacket
for water circulation insures better and efficient cooling of
compounds.
• Mirror polished S.S 304 cone is provided for water circulation
and to increasing the cooling surface area and efficient
cooling cycle in least time.
• Shovel type S.S blades for efficient movement of compound
for shorter cooling time and discharge of material.
