Selling an Idea or a Product

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Stages of Drying
Materials go through several physical stages
during the drying process - Paste, Granule and
Powder. Du- ring the early portion of the Paste
Stage, the product is a thickening slurry which
is readily put into turbu- lence by the action of
the plows. The Dryer has been designed to achieve
the critical Froude Nr. (The Point in which the
plows force the batch into turbulence thus
maximize the heat transfer capability of the
dryer. This attainment of the critical Froude
Number enables fast, efficient transfer of the
BTUs required to satisfy the latent heat of
vaporization, thus generating a much shorter
drying cycle. Conventional dryers do not begin to
achieve Littleford drying rates, even in this
Liquid Stage of the drying curve where drying is
most easily accomplished. As the slurry thickens
at the end of the Paste Stage , (end of the
constant rate period), the batch thickens to a
mud-like consistency, which in conventional dryers
causes the batch to ball or cake. This
makes drying exceedingly difficult, since
moisture (volatiles) must migrate from inside
thrugh capillaries to the par- ticle surface
before it can be flashed off. This point on the
drying curve is where the limited drying rate of
conventional dryers gets even worse, as internal
par- ticle drying replaces efficient external
drying. In the Granule Stage, Littleford
Ploughshare Dryers, utilizing both the action of
the turbulent plows and the high shear choppers,
reduce the forming lumps to smaller granules,
thus exposing large amounts of new surface for
drying.
Why is the Littleford so efficient?
As the product moves from the Granule to the
Powder Stage, continued use of the high shear
choppers will break the dry- ing granules into
fine Powder, allowing for possible elimination of
further milling of the dried product.
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Heat Transfer Graphics
The Littleford Dryer exhibits superior heat
transfer coefficients, often two or three times
higher than those of a ribbon or paddle dryers.
As much as ten times higher than tumble or tray
dryers.
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Advance Drying

The Chopper Advantages in Drying Fast,
efficient drying without lump formation
The action of the turbulent plows and the high
shear choppers reduce the forming lumps to
smaller granules, thus exposing large amounts of
new surface area for drying.
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Optimizing Drying in the Littleford
Main reasons for drying operations To facilitate
handling and further processing. To permit
satisfactory utilization of the final product. To
reduce shipping costs. To increase the capacity
of other equipment in the process. To preserve a
product during storage and shipment. To enhance
the value and usefulness of waste or various
products. To make a product with physical
characteristics more appealing to the customer.
Reasons for drying under vacuum Control
temperature of temperature-sensitive
products Recover solvents for re-use. Effective
solvent removal under non-explosive
conditions and control its safe
handling. Capacity can be controlled, or varied,
by processing small or large batch sizes to meet
existing process requirements.
As a general statement, all drying can be divided
into distinct periods. In thecase of Vacuum
Drying, it falls into (3) categories Time known
as the constant rate period, or that time the
moisture is easily evaporated from the
surface This occurs at a time when the material
is substantially at the boiling point of the
evaporating liquid under the absolute pressure
conditions exixting in the dryer. That period
known as the falling rate period when the
material approaches the wall temperature of the
dryer. As diffusion is taking place, the sensible
heat of the material starts to approach the
heating medium.
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Optimizing Drying in the
Littleford Successful Vacuum
Drying Points
Numerous test results have indicated that the
most successful vacuum dryings are Achieved
whenthe following conditions prevail
THE MATERIAL IS NOT SOLUBLE IN THE SOLVENT TO BE
REMOVED. THESE TYPES OF PRODUCTS CAN BE FOUND
MOSTLY IN PHARMACEUTICAL COMPANIES THAT ARE DOING
MULTI-STAGE SOL- VENT PURIFICATIONS. THIS TYPE OF
PRODUCT IS IDEAL FOR THE LITTLEFORD DRYER. IF THE
MA- TERIAL IS SOLUBLE IN THE SOLVENT TO BE
REMOVED, WE HAVE FOUND 20 TO 30 SOLVENT TO BE
THE VERY MAXIMUM. GREATER CONCENTRATION CAUSED
MASSIVE BUILD-UP AGAINST THE HEAT TRANSFER
SURFACES AND VERY HIGH POWER DEMANDS (10 HP IN
FM-130 PILOT UNIT).
TWO TYPES OF DRYING IN THE LITTLEFORD PROCESS
VESSELS ATMOSPHERIC AND UNDER
VACUUM
Factors that control heat transfer -Type of
mixing tool -Speed of agitation -Jacket
Area -Jacket Temperature -Boiling point of
volatile component U Q .
(A) (LmTD)
Vessels that can maximize all factors for
efficient drying FM, FKM, VT and DVT
types. Jacketing -Cover Max. Area of
shell. -Heat Shaft (optional) -Heat Heads
(optional) -Circulation fluids in jacket at
correct Reynolds number. -Connect all fluid flow
from bottom-up. -Connect all steam in _at_ top, out
at bottom through trap. Must supply sufficient
steam for process requirements.
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Explosion (overpressure) Protection -All sealed
units must be protected. -Units must be designed
for pressure (not necessarily stamped or
coded) Seals -Packing for medium vacuum or
atmospheric -Mechanical seals for high
vacuum. Discharge Valves Std.Contour, Ball,
GEMCO Vacuum -Vapor pressure controls B.P.
(want to max-imize differential between jacket
product) -Millimiters Hg Abs. Vs in. Hg
Ref. Vapor Port line sizing -Port less than
3 Ft/Sec -Vapor line less than 100 Ft/Sec.
Expanded volume under vacuum. Vacuum Systems
(Critical Proper Design) -Pump CFM pumping
rate. -Condenser Ft2 and tube diameter. -Full or
partial water recovery. IMPORTANT Draw vacuum
before running. N2 Flush Low level moisture
require it to lift vapor
out of drier. Air drying VS Vacuum drying
Optimizing Drying In the Littleford
3rd. Page.
Plow Types -Standard Heat Transfer. Choppers
-Used to deagglomerate lumps. -Add small amount
of heat to aid drying -Integral shafts are
recommended. Pulse Back Filter -Used to contain
solids in dryer. -Use hot pulse air. -Must be
heated above dew point of volatile -Sizing
chart for most applications. -Seal seams of
bags. -Use tight porosity bags with special
coating. RPMs -Normal Speed is Std. to
maximize heat transfer -Keep same Froud during
scale-up -Some applications are at reduced speed
due to Nature of product being dried, so as to
keep motor Loads as low as possible. Drives
Single,Two-Sp.,Varaible or Hydraulic.
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Drying Heat Sensitive Low Percentage Solids
The Littleford Day drying technology offers a
highly efficient economical means of drying
heat sensitive low percentage Solids solutions. A
considerable portion of the ingredients for the
Food, Pharmaceutical, Nutraceutical and
Biotechnical Industries is manufactured from the
extraction or reaction of plant materials using
solvents (water, alcohol, hexane, etc). This
process leaves the processor with a product in
the form of a liquid with a very low percent
solids level (Hydrolized Vegetable Protein,
St.Johns Wort, Enchinacea, and other
Nutraceutical products).
Processors have been searching for an economical
way to dry these products. In the past, due to
the stickiness of the Product during drying, the
processor was forced to utilize drying methods
such as frezze drying, spray drying, tray Dryers,
etc., expensive methods which did not rely on
mechanical agitation of the product through the
high viscosity Power Phase.
Typical Littleford vacuum drying process 1.-
Product is placed in the Littleford Ploughshare
Vacuum Dryer. Agitation Is initiated (plow
choppers (optional) followed by heating media
(hot water, Steam hot oil) on the vessel jacket
to raise the temperature of the product in The
dryer to the predetermined drying
temperature. 2.- With the vessel under vacuum, a
fine spray of the low solids solution is Atomized
into the heated bed of dried material. The rate
of spray is matched To the rate of vapor
evolution in order to mantain the bed of
materials as a Dry medium. 3.- After sufficient
material has been dried to raise the batch size
to a 70 Fill, the product is cooled (via cooling
media on the vessel jacket) to the Required
temperature for subsequent processing (other
ingredients added, Product granulated, etc.) or
discharge.
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Advantages of the advanced Littleford process
1.- Controlled drying through effective/optimum
heat transfer 2.- Improved Drying rates. 3.-
Increased efficiencies of drying. 4.- Efficient
single unit processing of the entire process
The Littleford equipment used to accomplish
this Advanced processing is the Littleford
Ploughshare Vaccum Dryer, which combines the
operational fe- Atures of liquid injection,
vacuum operation and Effective heat transfer
(heating or cooling) to dry in a single
processing unit. It operates according to the
proven fluidized bed mixing principle, Whereby
the materials being processed are man- Tained by
the plow shaped mixing elements in a Mechanically
fluidized suspeded state. This Permits liquid
and solid media to achieve intimate Individualized
, rapid contact with each other and The heat
transfer surfaces.
In addition, the Littleford Ploughshare Vacuum
Dryer may Be equipped with independently
operated, high shear chopper devices to
treduce the particle size of any Lumps or
agglomerates, exposing undried materials Thereby
ensuring thoroughly dried particle interiors.
This Deagglomeration further shortens the drying
time required. It is specifically dengineered to
maximize heat transfer, Yields coefficients that
are many times higher than those Of traditional
dryers. This advanced heat transfer techno- Logy
generates rapid drying in a single process
vessel. It can be enhanced with an optional Pulse
Back Filter to Effectively handle the vapor steam
created during steam Stripping and drying.
The Littleford process enables the processor to
produce an excellent, dried product with solvent
levels well below the limits set by the FDA. The
Littleford Ploughshare Vacuum Dryer is designed
and constructed according to GMP and to meet or
exceed FDA, 3A, USDA, compliance As specified by
the customer. This proven Littleford technology
has been applied to numerous complex and
difficult applications in the Food,
Pharmaceutical, Nutraceutical And Biotechnical
Industries. Littleford Ploughshare Vacuum Dryers
can be purchased in a variety of sizes to meet
most production require- Ments. Littleford can
interface its system controls with existing
equipment or supply fully automated process
control systems
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Typical Applications
Paint Sludge Slurry Para Toluene
Sulfonate Paraformaldehyde Peat Moss (Vermiculite
Mix) Penicillin Powder Pesticides Pharmaceuticals
(Intermediate) Photographic Process
Sludge Pigments Plastic Resin Beads Polyethilens P
olymers Polyvinil Alcohol Potassium Boro Fluoride
Phenate Protein Modifications Psyllium
Seed Q-R-S-T-U-V-W-X-Y-Z Refracting Powders Resin
Beads Selenium Metal Filter Cakes Sodium
Methylate, Phenate, Stearates Specialty
Chemicals Starch Powder Sulfonated
Polystyrene Temperature Sensitive Enzymes Tugsten
Carbide Slurry Toxic Sludges Vitamin Mix Wet
Friction Lining Wheat Bran, Farina Germ Zinc
Diacrylate
A-B-C Acetoquanamine Acetyl Salicilic
Acid Acrylic Powder Agricultural
Herbicides Aluminum Hidroxide Slurry Animal
Byproducts Animal Feed Products Animal Waste for
Fertilizers Barium Stearate Boric Acid
Solution Brewers Yeast Cadmium Oxide Calcium
Stearate Carbon Black Carbon Fibers Carboxi
Methyl Cellulose Carrageenan Catalyst Cellulose Ce
tylpyridinium Chloride Chmical Dye
Intermediate Chocolate Citric Acid Coal Ash
Slurry Cocoa (Dutching) Cocoa (Processing) Coffee
(Decaffeinating)
D-E-F-G Dental Adhesive Dextrose Dye
Intermediates Enzimes (Temp.Sensitive) Ethyl
Cellulose Fillers Fish Meal Flammable
Sludges Flour (Toasting) Friction
Material Graphite Filter Cake H-I-J-K-L Herbicides
Inks Inorganic Filler Powders Iron Oxide Filter
Cake Lead Phthalates/Stearates Lecithin Oil
Extract Liquid Fungicides Lithium
Fluorite M-N-O-P Magnesium Stearates Metal
Binders Reclaim Methyl Cellulose Modifies
Protein Powdre Molibdenum Disulfide