Note: Descriptions are shown in the official language in which they were submitted.
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IMPROVED METHOD FOR MANUFACTURING COATED FEED PELLETS
The present invention relates to an apparatus and a process for the
manufacture of coated feed pellets.
5 BACKGROUND OF THE INVENTION:
The pelleting of feed for livestock is a well known process that
enhances palatability and thereby increases the growth rate for livestock. The
problem with pelleting feed for some livestock, such as baby pigs, is that the
addition of high fat levels to the ration causes the feed pellet to become soft.10 Consequently, transportation and handling of the feed pellet will lead to thebreakdown of the feed pellet. This in turn results in too many fine particles,
which has the consequence of reducing palatability and thus feed intake.
These soft feed pellets are also heat labile, as moist heat can lead to not onlybreakdown of the feed pellets but may also denature the nutritional
15 components of the feed pellets.
US Patent No. 5,132,142 discloses an apparatus for producing coated
pellets by layering powder onto particles. The apparatus comprises a vessel
and a rotor supported for rotation around a vertical axis and having a
supporting surface for supporting particles. The apparatus comprises
20 furthermore a feeding means for introducing a powder and a liquid into a
processing space inside said vessel and adjacent to the supporting surface of
said rotor. The feeding means comprises an introducing member which
consists of a liquid outlet and a powder outlet, wherein one of the outlets
encompasses the other. The process comprises introducing particles into the
25 vessel and subjecting them to an atomized spray of liquid and powder. At
room temperature, the ratio of powder to liquid is approximately 1:1 or 1.5:1.
This ratio can be increased at higher temperature which in turn decreases the
time required for the coating process and drying of the pellets.
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While US Patent No. 5,132,142 represents an advance over the prior
art in that there is little loss of coatin~ material and the pellets produced are
of uniform size and shape, the described process is not ideally suited for the
manufacture of coated feed pellets containin~ hi~h fat content. Specifically,
5 use of the apparatus described therein would subject the feed pellets to
rotational forces during the coating process which would cause breakdown.
Furthermore, the coatin~ process described therein is most efficient at hi~her
temperature, which, as stated above, would result in breakdown of the feed
pellet. While the coatin~ process can be carried out at room temperature,
10 doin~ so si~nificantly increases dryin~ time, durin~ which time the apparatus cannot be used.
SUMMARY OF THE INVENTION:
It is one object of the present invention, therefore, to provide an
15 improved process for manufacturin~ coated feed pellets.
Accordin~ to one aspect of the invention, there is provided a method
for manufacturin~ coated feed pellets, comprisin~:
wettin~ the feed pellets via a spray consisting of liquid droplets; and
directin~ the wet feed pellets into a bed of powder material, such that
20 the wet feed pellets become enclosed within the powder material, producing
coated feed pellets.
Preferably, the feed pellets are subjected to an initial separation step,
such that only individual feed pellets are exposed to the spray of liquid
droplets. More preferably, the separation step comprises a first rotating disk
25 that separates the feed pellets into individual units by centrifugal force.
Preferably, access of the feed pellets to the separation step is re~ulated
such that there is a rate of flow. More preferably, the flow rate is regulated
by placin~ the feed pellets into a first hollow tube of fixed hei~ht surrounded
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by a second hollow tube of variable height, both said hollow tubes bein~
placed directly above the first rotatin~ disk such that adjustin~ the height of
the second hollow tube regulates access of the feed pellets to the first
rotatin~ disk.
Preferably, the spray of liquid droplets is generated by dripping said
liquid onto a second rotatin~ disk. More preferably, the second rotating disk
is a concave rotatin~ disk. Yet more preferably, the second rotatin~ disk
revolves in the opposite direction of the first rotating disk and the first
rotatin~ disk is located 12 cm above the second rotating disk.
Preferably, the liquid used to ~enerate the spray is unheated so that
the spray is at ambient temperature. More preferably, the liquid droplets
ran~qe in diameter from 6-800 microns.
Preferably, the powder material is of a material such that it crystallizes
upon dryin~.
Preferably, the feed pellets are hi~h fat feed pellets, havin~ a fat
content of 8 to 30%. More preferably, the coating material crystalizes to
encase the high fat feed pellet.
Preferably, the wet feed pellets enclosed within the powder material
are subjected to a~qitation. More preferably, the wet feed pellets are ayitated
in a baffled vessel, such that said baffles hinder the pro~ress of the feed
pellets throu~h the vessel.
Preferably, the bed of powder material is present in a quantity that is
greater than the amount required for coating the feed pellets, such that there
is excess powder material. More preferably, the powder material is present in
at least a four fold excess relative to the amount required for coating the feedpellets.
Preferably, the coated feed pellets are separated from the excess
powder material. More preferably, the excess powder material is recycled.
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BRIEF DESCRIPTION OF THE FIGURES:
Figure 1 is an overview of the apparatus for manufacturing coated
feed pellets.
Figure 2 is a cross-sectional view of the mist generating system and
5 the pellet separator.
Figure 3 is a cross-sectional view of the coating system, the coated
feed pellet separator and the powder recycling system.
Figure 4 is a side view and a cross-sectional view of a feed pellet and a
coated feed pellet.
DETAILED DESCRIPTION:
In Figure 1 is shown an overview of the apparatus for manufacturing
coated feed pellets.
The invention comprises a mist generating system, a pellet separator, a
15 mist chamber, a coating system, a coated feed pellet separator and a powder
recycling system.
In Figure 2, the mist generating system and the pellet separator are
shown in cross-section. The mist generating system comprises a water pipe
1, having a vertical and a horizontal component. The horizontal component is
20 attached to an outside water source. Water pressure can be controlled at a
first valve 2 or, alternately, the water can be shut off completely at a second
valve 3. Both valves are located on the horizontal component of the water
pipe 1. The vertical component of the water pipe 1 enters the mist chamber
through a 1.5" hollow shaft 4. At the end of the vertical component of the
25 water pipe 1 is a nozzle 5 situated approximately 12 cm above a concave
rotating disk 6 revolving at 1800 RPM which is located within the mist
chamber. The concave rotating disk 6 is driven by a 1" shaft 7 located below
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the plane of the concave rotating disk 6. The 1" shaft is connected via a belt
and pulley system 8 to a 1 horsepower motor 9.
The pellet separator comprises a variable speed conveyor that
terminates at a duct 10. The duct 10 is connected to a walled vessel 11
S which also contains the mist chamber. The entry point of this duct 10 into
the walled vessel 11 is situated above a hollow tube of fixed height 12
located within the mist chamber. Surrounding the hollow tube of fixed height
12 is a hollow tube of variable height 13. Directly below the hollow tube of
fixed height 12 and the hollow tube of variable height 13 is a flat rotating
10 disk 14, wherein the flat rotating disk 14 has a diameter equal to or greaterthan the diameter of the hollow tube of variable height 13. Furthermore, the
flat rotating disk 14, revolving at 800 RPM, is driven by a 1.5" hollow shaft 4
located above the plane of the flat rotating disk 14. The 1.5" hollow shaft 4
is connected to a 1 horsepower motor 15 via a belt and pulley system 16.
The mist chamber comprises a nozzle 5 located at the lower base of
the 1.5" hollow shaft 4 as described above as part of the mist generating
system. Approximately 12 cm below the nozzle is the concave rotating disk 6
described above as a component of the mist generating system. The mist
chamber is located within the walled vessel 11 described above as also
20 containing the pellet separator. Connected to the base of the walled vessel
1 1 is a sloped and tapered shaft 17 that is connected to the main chamber
18 of the coating system via a duct 19.
In Figure 3, the coating system, the coated feed pellet separator and
the powder recycling system are shown in cross-section. The coating system
25 comprises a main chamber which is equipped with a sensing system for
determining if the powder level is too high 20 or too low 21. Connected to
the base of the main chamber 18, below the level of entry of the duct 19
from the walled vessel 11 is a baffled vibrating tank 22. The opening at the
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base of the baffled vibrating tank 22 is regulated by a sliding gate 23. This
opening is situated directly above a declined agitating conveyor with a
perforated floor 24 that is part of the coated feed pellet separator.
The coated feed pellet separator comprises a declined agitated
5 conveyor with a perforated floor 24. Both the declined conveyor with a
perforated floor and the baffled vibrating tank 22 are agitated back and forth
by a rocking platform 25 connected to a 2 horsepower motor 26 by a belt
and pulley system 27. At the terminus of the declined agitating conveyor with
a perforated floor 24 is a duct 33 for discharge of the coated feed pellets. A
10 feed pellet 34 encased in coating material 35 is shown in cross-section in
Figure 4 and in side view in Figure 5.
The powder recycling system consists in part of an inclined screw
conveyor belt 28 located directly below the declined agitating conveyor with
the perforated floor 24. At the elevated terminus of the screw conveyor 28 is
15 a duct 29 into a narrow chamber 30, wherein the material is elevated via a
vertical screw conveyer 31. At the apex of the vertical screw conveyor 31 is
a duct 32 to the main chamber 18 of the coating system.
In operation, water dripped from the water pipe 1 onto the concave
rotating disk 6 generates a spray of water droplets in the mist chamber. Feed
20 pellets enter the pellet separator from the variable speed conveyor via a duct
10. Said duct 10 directs the feed pellets into the hollow tube of fixed height
12 situated above the flat rotating disk 14. The hollow tube of variable height
13 serves as a collar so as to restrict access of the feed pellets to the flat
rotating disk 14. Raising the height of the hollow tube of variable height 13
25 will increase the flow rate of the feed pellets into the mist chamber. Upon
encountering the flat rotating disk 14, the feed pellets are separated into
individual units by centrifugal force and dropped down into the mist chamber.
Therein, the feed pellets pass through the spray of water droplets and are
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directed into the main chamber 18 of the coating system, which contains a
quantity of the coating material that is in at least four fold excess of the
amount required to coat the feed pellets. The mixture of powder material and
feed pellets passes into the baffled vibrating tank 22. The combination of
5 agitation and the baffles promotes coatin~ of the feed pellets. The mixture ofcoatin~q material and coated feed pellets exits the baffled vibrating tank via an
opening with a sliding gate 23. Openin~q the sliding gate 23 will increase the
rate of flow of the mixture out of the baffled vibrating tank 22. Next, the
mixture of feed pellets and coating material is deposited onto the declined
10 agitating conveyor with a perforated floor 24. Shaking of this conveyor
system separates the coated feed pellets from the unused powder. At the
terminus of the declined ayitating conveyor with the perforated floor is a duct
for discharge of the coated feed pellets 33. The unused powder passes
through the perforated floor to an inclined screw conveyor 28. The inclined
15 screw conveyor carries the unused powder material to a vertical screw
conveyor 31 via a duct 29. At the apex of the vertical screw conveyor 31 is
another duct 32 which returns the unused powder material to the main
chamber 18 of the coating system.
Since various modifications can be made in my invention as herein
20 above described, and many apparently widely different embodiments of same
made within the spirit and scope of the claims without departing from such
spirit and scope, it is intended that all matter contained in the accompanying
specification shall be interpreted as illustrative only and not in a limiting
sense.
