Conditioner for processing raw grain composition to produce pelletized feed

This invention relates to an apparatus and a method for hydrothermally processing a raw grain composition with steam in a conditioner as a preliminary step in the production of a pelletized feed product. More specifically, this invention is directed to an apparatus and a method for massing in-process grain composition in a chamber to enhance efficacy and efficiency of hydrothermal treatment and to improve the production rate and quality of pelletized feeds.

FIELD OF INVENTION 
This invention relates to an apparatus and a method for hydrothermally 
processing a raw grain composition with steam in a conditioner as a 
preliminary step in the production of a pelletized feed product. More 
specifically, this invention is directed to an apparatus and a method for 
massing in-process grain composition in a chamber to enhance efficacy and 
efficiency of hydrothermal treatment and to improve the production rate 
and quality of pelletized feeds. 
BACKGROUND AND SUMMARY OF THE INVENTION 
Pelletized feeds are produced by hydrothermal treatment of a raw grain 
composition and processing the resulting mash. Typically the raw grain 
composition is processed in a conditioner where it is contacted and 
blended with steam injected into the conditioner with resultant 
gelatinization of at least a portion of the starch in the grain and 
formation of a heated, hydrated mash. The mash is delivered from the 
conditioner to a pellet mill where it is pressed through dies to form feed 
pellets. Typical industrial conditioners include steam treatment chamber 
and a series of blades that are attached to a rotatable tool bar mounted 
in the chamber. The blades are oriented on the tool bar to mix the grain 
composition with the injected steam and to advance the in-process grain 
composition through the conditioner. The tool bar is typically rotated at 
a high rate, often about 200 to 400 revolutions per minute. In practice, 
however, the raw grain composition is not uniformly processed 
(hydrothermally heated) because it is forced through the conditioner 
before the steam can be thoroughly blended with and penetrate the 
particulate constituents of the grain composition. The starch component in 
the pelletted product produced in such method is often insufficiently or 
not uniformly gelatinized resulting in poor quality feed pellets. 
The present invention provides a method and apparatus for the improved 
manufacture of pelletized feeds. In one embodiment of the present 
invention there is provided an improved conditioner for hydrothermally 
processing a grain composition. The conditioner comprises a housing having 
a inlet end, an outlet end and a chamber positioned between the two ends. 
The conditioner includes a rotatable tool bar and first and second sets of 
radially extending blades, said blades positioned oriented to promote 
formation of a plug of in-process grain composition in the conditioner as 
a result of rotation of the tool bar during operation of the condition. 
In one embodiment each blade in the first set of blades is oriented to lie 
in a first inclined position relative to the tool bar so that each blade 
in the first set of blades has a negative slope when viewed from a point 
away from the tool bar looking at the tip end of the blade. Each blade of 
the second set of blades is oriented to lie in a second inclined position 
relative to the tool bar so that each blade has a positive slope when 
viewed from a point away from the tool bar looking at the tip end of the 
blade. The tool bar is rotated during conditioner operation so that the 
first set of blades tends to advance the in-process grain composition from 
the inlet and toward the outlet end and the second set of blades tends to 
push the in-process grain composition toward the inlet end. The number and 
length of the blades in the first and second sets of blades can be 
variable as can the magnitude of the respective positive and negative 
slope inclinations of the blades within each set. Of course, the relative 
slope orientations of the first and second sets of blades can be reversed 
and the tool bar can be rotated in the opposite direction to provide an 
equivalent plug-forming effect. 
The rate of rotation of the tool bar can be controlled/varied during 
conditioner operation to control plug formation and in-conditioner 
retention time of the grain composition. Raw grain composition is fed into 
the inlet end of the conditioner substantially continuously during 
conditioner operation and at variable controlled rate, and steam is 
continuously introduced into the conditioner chamber to process the grain 
composition as it is advanced through the conditioner by the action of the 
tool bar. Formation of the "plug" of the in-process grain composition in 
the conditioner chamber helps prevent the injected steam from escaping 
through the outlet end of the conditioner and improves efficiency of steam 
utilization in the process. 
In one embodiment the first set of blades is positioned on the tool bar in 
an upstream region of the conditioner chamber near the inlet end, and the 
second set of blades is positioned on the tool bar in a downstream region 
of the interior chamber between the first set of blades and the outlet 
end. The plug-maker tool bar is coupled to a variable speed drive that can 
be controlled to rotate the tool bar at a defined speed/rotation rate 
within a range of speeds. 
In another embodiment of the present invention, there is provided a method 
for increasing the rate of hydrothermal processing of a raw grain 
composition in a conditioner having a grain inlet, a grain outlet, an 
interior chamber positioned to lie between the grain inlet and grain 
outlet, a tool bar mounted for rotation in the interior chamber, a grain 
feeder for advancing the raw grain composition through the grain inlet and 
into the chamber, and a steam inlet for injecting steam into the interior 
chamber to contact the raw grain composition. The method comprises the 
steps of advancing the grain composition through the grain inlet and into 
the interior chamber of the conditioner, injecting steam into the interior 
chamber to contact the grain composition, forming a plug comprising the 
in-process grain composition in the chamber with negatively sloping blades 
and positively sloping blades coupled to the tool bar by continuously 
rotating the tool bar, continuing to inject steam into the chamber to 
complete the hydrothermal processing of the in-process grain composition 
as it is retained in the chamber as part of the plug, discharging portions 
of the processed grain composition in the plug through the chamber outlet, 
and substantially continuously replacing discharged portions of processed 
grain composition by delivering raw grain composition into the interior 
chamber through the inlet. 
The present invention, therefore, comprises a conditioning chamber with an 
inlet and outlet end and a rotary blade assembly for advancing a grain 
composition from the inlet end to the outlet end. The blade assembly has 
blades at different pitches and/or locations to build a plug mass of grain 
in the composition chamber into which steam is injected to effect 
hydrothermal processing preliminary to pelletization of the composition. 
The blades are configured so that as the blade assembly is rotated at 
selected speeds, the grain composition is advanced from the inlet end of 
the chamber into the chamber to form part of the plug mass and ultimately 
through the outlet end of the chamber with the dwell time of the 
composition in the plug mass being sufficient to allow complete/effective 
hydrothermal processing of the composition to form a fluidized grain mash 
ideally suited for pellet milling.

DETAILED DESCRIPTION OF THE INVENTION 
Generally this invention is directed to an apparatus and a method for 
massing and blending a grain composition in a conditioning chamber with 
steam to provide a processed grain composition that can be formed into 
high quality feed pellets. A grain composition-plug maker in the interior 
chamber of the conditioner includes a first and a second set of blades 
mounted on a rotatable tool bar. Rotation of the tool bar during delivery 
of steam and raw grain composition to the conditioner operates to fill the 
conditioner and form a plug in the chamber comprising a partly-processed 
grain composition. Filling and operating the conditioner by designed plug 
formation increases production without increasing energy costs. Formation 
of the plug of partly-processed grain composition in the chamber works to 
increase the conditioning time and efficiency thereby allowing more 
uniform/complete hydrothermal processing of the grain composition with 
concomitant improvement in pelletized feed product quality. 
Referring now to FIG. 1, feed processing system 10 for providing a 
pelletized feed product comprises a water purification system 12, steam 
generating system 14, and pellet producing processor 16 including 
conditioner 54 and pellet mill 66. Boiler water for steam generation is 
supplied from water purifier 18 through conduit 20 to make up water tank 
22 where chemicals such as oxygen depleting chemicals and alkalizers are 
combined with the water before it is delivered through conduit 28 to steam 
generating system 14. Methods of purifying boiler water are well known in 
the art. Preferably the boiler water supplied to steam generating system 
14 is purified to have an electrical conductivity of less than about 3,700 
micromhos to minimize steam-borne contaminants. The type of steam 
generator used to provide steam is not critical to this invention. Thus, 
for example, a Clayton-type steam generator or a bent tube boiler can be 
used to provide steam to the pellet producing processor 16. Steam is 
delivered to conditioner 54 through conduits 36, 38, 40, and 42 and 
through pressure reduction valve 46, flow meter 50, flow control valve 52, 
and steam inlet 44. 
Steam, preferably non-superheated steam, is delivered through conduits 36, 
38, 40, and 42 to conditioner 54 by operating the steam generator 34 at 
relatively low pressure, generally less than about 100 psi, and minimizing 
pressure reduction en route to the conditioner. Preferably the steam 
generator is operated a pressure of less than about eighty pounds per 
square inch, more preferably less than about sixty pounds per square inch. 
Typically pressure reduction valve 46 is selected to reduce the steam 
pressure in conduits 38, 40, and 42 to an amount no less than forty 
percent of the steam generator pressure, more preferably no less than 
fifty percent, most preferably no less than sixty percent of the steam 
generator pressure. The resulting saturated, non-superheated steam 
delivered to condition 54 enables uniform, consistent, hydrothermal 
processing of the raw grain composition. 
Conduits 36, 38, 40, and 42 are sized to provide stoichiometric amounts of 
steam at a relatively low flow velocity to the conditioner in an amount 
and at a rate sufficient for effective hydrothermal treatment of raw grain 
composition being fed substantially continuously into the grain 
conditioning chamber. The low-velocity steam allows the raw grain 
composition in the grain conditioning chamber to absorb essentially 
qualitatively all of the moisture and heat from the steam. Preferably, 
conduits 36, 38, 40, and 42 are sized to deliver steam to the conditioning 
chamber at a velocity of about 8,000 to about 12,000 feet per minute 
(2,440 to about 3,660 meters per minute). Flow meter 50 displays the flow 
rate of steam delivered through the meter in pounds of steam per hour. 
Sizing of the steam conduits is calculated by determining the 
stoichiometric amount of steam needed per hour to process completely the 
raw grain composition to be delivered to the chamber during conditioner 
operation. Standard steam tables enable calculation of the size of pipe 
conduit necessary to deliver the required amount of steam per hour at the 
specified temperature, pressure, and velocity. A cylindrical pellet-mill 
conditioning chamber having dimensions of about 8 to about 12 feet in 
length (2.4 to about 3.6 meters) and about 12 to about 24 inches (30 to 60 
cm) in diameter and coupled to a pellet mill rated for about 150 to about 
225 horsepower can process a raw grain composition at a rate of about 18 
to about 24 tons per hour (16 to about 22 metric tons per hour). 
Generally, about 100 to about 200 pounds (about 45 to about 90 kg) of 
steam are needed to process each ton (0.9 metric ton) of raw grain 
composition. Thus, the range of stoichiometric amounts of steam for 
processing a raw grain composition in this pellet mill conditioning 
chamber is about 1,800 pounds to about 4,800 pounds per hour (820 to about 
2,180 kg per hour). Standard steam tables can be consulted to determine 
that a three inch (7.6 cm) diameter pipe can be used to deliver about 
1,800 to about 4,800 pounds of steam per hour at a linear velocity of 
about 8,000 to about 12,000 feet per minute (2,440 to about 3,650 meters 
per minute). 
A raw grain composition 56 stored in bin 58 is delivered to conditioning 
chamber 54 through grain conduit 60 by grain feeder 61 that is coupled to 
feeder drive 130. In conditioner 54 the raw grain composition is blended 
with steam to provide a partly-processed grain composition 62. Processed 
grain composition 62 is discharged from conditioner 54 through grain 
outlet 64 and delivered to pellet mill 66 through chute 68. The pelletized 
feed product 70 is produced from the partly-processed grain composition 62 
in pellet mill 66. The pelletized feed product 70 is collected in 
container 72 where it is cooled before storage. 
An illustrated embodiment of grain composition-plug maker 74 is shown in 
FIGS. 2-4. Plug-maker 74 includes tool bar 76, a first set of blades 78 
and a second set of blades 80. The first and second sets of blades are 
mounted to and extend radially from tool bar 76. Optionally, the 
plug-maker 74 can include a set of wiper picks 81 that extend radially out 
from tool bar 76 and trace the interior walls of the housing of the 
conditioner 54 to increase the grain blending efficiency of the 
plug-maker. 
Plug-maker 74 is mounted for rotation in the interior chamber of 
conditioner 54. Rotation of plug-maker 74 about an axis of rotation 82 
operates to blend a raw grain composition with steam and form a plug 152 
(See FIGS. 8 and 9) comprising partly-processed grain composition between 
the grain inlet 63 and grain outlet 64. Rotation of the tool bar and the 
included first and second sets of blades churns the partly-processed grain 
composition in the chamber and uniformly and continuously blends the grain 
composition with steam that is injected to the chamber of the conditioner 
through steam inlet 44 and thus prevents localized superheating of the 
grain. Rotation of plug-maker 74 also forms plug 152 in the conditioner 
chamber by massing the in-process grain composition to fill the full 
cross-section of the conditioner chamber 65 over at least a portion of its 
length. Plug formation increases both the conditioning time for processing 
the grain composition in the conditioner, and it increases the amount of a 
raw grain composition that can be processed through conditioner 54. 
Plug-maker 74 includes tool bar 76 that extends the length of the interior 
chamber of conditioner 54. Tool bar 76 includes an upstream end 84 
proximate to the inlet end 134 of housing 55 of conditioner 54, a 
downstream end 86 proximate to the outlet end 136. Tool bar 76 is mounted 
for rotation in chamber 65. Preferably the tool bar 76 is coupled to a 
variable speed drive 132 so that the tool bar 76 can be rotated at a range 
of speeds from about 50 to about 200, more preferable about 70 to about 
150 revolutions per minute to provide optimum conditions for processing a 
raw grain composition. In a preferred embodiment the variable speed drive 
is a VARIMOUNT Series R80 Gear Motor manufactured by SEW-EURODRIVE. It is 
used for a conditioner eighteen inches in diameter by ten feet in length. 
During conditioner startup, the range of rotation speeds of the tool bar 
is about 95 to about 100 revolutions per minute. The shape of tool bar 76 
is not critical for practicing the present invention; the tool bar may be 
cylindrical or prismatic having three or more sides. Preferably the tool 
bar 76 includes four sides arranged to provide the tool bar with a 
rectangular or square cross section. The each of the four sides of tool 
bar 76 are adapted for mounting blades. 
A first set of blades 78 is mounted on tool bar 76. Each blade in the first 
set of blades 78 has a root end 88 adjacent to tool bar 76 and a tip end 
90 that lies in a spaced apart relation to the tool bar. Each blade in the 
first set of blades has a leading edge 94 and a trailing edge 92. Each 
blade is angularly positioned so that the leading edge 94 is in an axial 
position (on the length of the tool bar) between the trailing edge 92 and 
the inlet end 134 of housing 55. A rearward surface 96 extends between 
leading edge 94 and trailing edge 92 and faces inlet end 134 of housing 
55. A forward surface 98 extends between leading edge 94 and trailing edge 
92 and faces outlet end 136 of housing 55. Each blade in the first set of 
blades 78 is oriented relative to tool bar 76 to define an included obtuse 
angle 100 between a portion of the rearward surface 96 including trailing 
edge 92 and a reference line 110 that is parallel to the axis of rotation 
82 of tool bar 76. In a preferred embodiment of the present invention the 
obtuse angle 100 is about one hundred thirty-five degrees. When each blade 
in the first set of blades is viewed from a point away from the tool bar 
76 looking toward the tip end 90 of the blade, each blade is oriented to 
lie in an inclined position having a negative slope relative to tool bar 
76. 
A second set of blades 80 is mounted on tool bar 76. Each blade in the 
second set of blades 80 has a root end 112 adjacent to tool bar 76 and a 
tip end 114 in a spaced apart arrangement from tool bar 76. Each blade in 
the second set of blades has a leading edge 116 and a trailing edge 118 
positioned axially (on the length of the tool bar) to lie between leading 
edge 116 and inlet end 134 of housing 55. A rearward surface 120 extends 
between leading edge 116 and trailing edge 118 and faces inlet end 134. A 
forward surface 122 extends between leading edge 116 and trailing edge 118 
and faces outlet end 136. Each blade of the second set of blades 80 is 
oriented relative to the tool bar 76 to define an included acute angle 124 
between a portion of the rearward surface 120 including trailing edge 118 
and reference line 110. In a preferred embodiment of the present 
invention, the acute angle 124 is about seventy-five degrees. When each 
blade in the second set of blades is viewed from a point away from the 
tool bar looking toward the tip end 114 of the blade, each blade is 
oriented to lie in an inclined position having a positive slope relative 
to the tool bar 76. 
Each blade in the first set and second set of blades are arranged relative 
to one another so a forward surface 98 of a selected blade in the first 
set of blades 78 and the rearward surface 120 of a select blade in the 
second set of blades 80 converge in a direction toward the housing 55 and 
define an acute included angle therebetween of about fifty-five to about 
sixty-five degrees, more preferably, about sixty degrees. The first set of 
blades 78 is positioned on the tool bar to lie in an upstream region 126 
of the interior chamber 65 and the second set of blades 80 is positioned 
on the tool bar 76 to lie in a downstream region 128 of the interior 
chamber 65 between the first set of blades 78 and the outlet end 136 of 
housing 55. Preferably, the wiper picks 81 are positioned on tool bar 76 
to lie in downstream region 128 of the chamber 65. 
Steam is injected through steam inlet 44 into chamber 65. In a preferred 
embodiment illustrated in FIGS. 5 and 6, steam is injected through steam 
inlet 44 into manifold 138. Manifold 138 is positioned to lie in upstream 
region 126 of the chamber 65 and includes steam ports 140 through which 
steam exits manifold 138 into chamber 65. 
Referring now to FIGS. 7-9, a raw grain composition 56 is delivered through 
conduit 60 to grain feeder 61. Grain feeder 61 is coupled to feeder drive 
130. Preferably feeder drive 130 includes a variable speed drive that can 
be controlled to vary the feed rate of the raw grain composition into the 
grain inlet 63. It is understood that the initial feed rate will vary 
depending on the nature of the raw grain composition and that the feed 
rate is varied from an initial rate to a final rate to optimize the 
production of a pelletized product. Raw grain composition 56 enters the 
upstream region 126 of interior chamber 65 through grain inlet 63. 
Rotation of tool bar 76 rotates the first set of blades 78 positioned in 
the upstream region 126 to advance raw grain composition 56 toward the 
downstream region of the chamber 65. Steam injected through steam inlet 44 
into manifold 138 and through steam ports 140 contacts the raw grain 
composition 56 in chamber 65 initially to provide a partially-processed 
grain composition 62. 
Rotation of tool bar 76 and the attached first set of blades 78 operate to 
advance the grain composition past the steam ports 140 and to prevent the 
grain composition from occluding the steam ports 140. The second set of 
blades on the tool bar 76 churn and blend the in-process grain composition 
with steam and impart resistance to flow of the composition toward outlet 
64. As the blades on plug-maker 74 churn the grain composition to blend 
the grain with the steam, voids in the process composition are presented 
proximal to steam ports 140. As the steam fills the voids, the rate of 
steam flow into conditioner 54 rapidly increases as indicated by flow 
meter 50. When the plug 152 is fully formed, it contains no voids. Thus, 
flow meter 50 can be used to determine when the grain plug 152 is fully 
formed in the conditioner. When the flow meter indicates that the rate of 
steam flow is relatively constant, i.e., does not vary more than about ten 
percent over a about three to five minute time period, plug 152 has fully 
formed in the conditioner 54, and the in-process grain mass does not 
contain voids that are indicated by rapid variations the rate of steam 
flow into conditioner 54. 
The raw grain composition received in the upstream region 126 progresses to 
the downstream region 128, where rotation of the tool bar 76 and the 
included second set of blades 80 blend the in-process grain composition 
with steam. As an increased amount of a grain composition enters the 
downstream region 128, rotation of tool bar 76 and the attached second set 
of blades 80 mass the partly-processed grain composition to form grain 
plug 152. Formation of grain plug 152 increases the conditioning time and 
allows more complete gelatinization the starch in the grain. Continued 
rotation of tool bar 76 along with the attached blades further blends the 
in-process grain composition in the grain plug 152 to homogeneously, 
hydrothermally process the grain particles that make up the in-process 
grain composition. Formation of grain plug 152 in the interior chamber 
prevents steam from directly venting into the atmosphere, for example, 
through outlet 64. Thus, essentially all the moisture and heat from the 
steam is absorbed by the partly-processed grain composition in chamber 65. 
Once the plug of in-process grain is formed in the downstream region 128 of 
chamber 65, introduction of additional raw grain composition 56 into the 
upstream region 126 and advancing same under the influence of rotating 
tool bar 76 forces some of the in-process grain composition defining the 
grain plug 152 out grain outlet 64. The discharged grain composition is 
replaced with partly-processed grain composition from upstream region 126 
of chamber 65. The processed grain composition discharged through outlet 
64 is delivered through chute 68 to pellet mill 66 and formed into a 
pelletized feed product 70. 
The process for providing a pelletized feed product in accordance with this 
invention may be optimized by monitoring certain key parameters such as 
the temperature of the partly-processed grain composition, the load on the 
pellet mill drive 146 and the flow rate of steam injected into the 
conditioner 54. The temperature of the partly-processed grain is measured 
using temperature sensor 142 that is located in grain outlet 64. 
Temperature sensor 142 measures the temperature of the processed grain 
composition that is passing through grain outlet 64 into chute 68. 
Preferably the temperature of the processed grain composition is about 
110.degree. F. (43.degree. C.) to about 220.degree. F. (104.degree. C.), 
more preferably about 150.degree. F. (65.degree. C.) to about 200.degree. 
F. (93.degree. C.). The rate of steam flow into the conditioner 54 is 
monitored by flow meter 50. In practice, the amount of steam will vary 
depending upon the nature and amount of the raw grain composition 
undergoing processing in the conditioner. Preferably, the rate of steam 
flow is about 100 to about 200 pounds of steam per ton of raw grain 
composition, more preferable from about 140 to about 160 pounds of steam 
per ton of raw grain composition. The initial rate of steam flow is slowly 
increased until the temperature of the in-process grain reaches the 
desired temperature. After the desired temperature is reached, the feed 
rate of raw grain composition 56 introduced into the conditioner 54 is 
increased. The temperature of processed grain passing through outlet 64 is 
monitored, and the amount of steam injected into the conditioner 54 is 
adjusted to maintain the temperature of the processed grain composition 
within the desired temperature range. As the feed rate increases, the load 
on the pellet mill drive 146 also increases. Load sensor 148 measures the 
load on the pellet mill drive 146. It is important to monitor the load on 
the pellet mill drive 146 so the load does not exceed the specified 
maximum full load capacity for the particular pellet mill drive 146. The 
load on the pellet mill may be decreased by decreasing the feed rate or 
increasing the rate of steam flow into the conditioner. When the load on 
the pellet mill drive 146 increases in response to an increased feed rate, 
the rate of steam flow into the conditioner is increased by opening flow 
control valve 52 until the load on the pellet mill drive 146 decreases by 
about ten percent to about sixty percent. Once the load on the pellet mill 
drive drops, the feed rate is again increased and concomitantly the load 
on the pellet mill drive increases. The steps of increasing the rate of 
steam flow and the feed rate are repeated until the load on the pellet 
mill drive does not drop by more than about five percent to about ten 
percent when the steam flow is increased. 
The adjustments to the feeder drive, the conditioner drive and the flow 
control valve may be made manually during operation of the conditioner. 
Alternatively, one or more of the steps in the processes may be computer 
controlled. Thus, a controller/computer 150 can receive inputs from one or 
more of sensing devices such as the steam flow meter 50, the temperature 
sensor 142 or load sensor 148 and in response to a predetermined value for 
each input, adjust the feed rate by adjusting the feeder drive 130, the 
rate of steam flow by adjusting flow control valve 52, or the variable 
speed conditioner drive 132 to optimize production and feed product 
quality. 
The processed grain composition that is discharged through outlet 64 is 
pelletized in pellet mill 66 to provide a durable pellet that does not 
require the addition of a binder such as sodium bentonite, calcium 
bentonite, or lignin sulfonate. Typically, the pellets produced in 
accordance with this invention have a Pellet Durability Index (PDI) of 
about ninety percent to about one hundred percent. The PDI was determined 
by charging a metal pipe, two inches in diameter and one foot in length, 
with about one hundred grams of feed pellets and one hundred grams of a 
metal agitator such as 5/8 inch metal hexnuts. The two inch metal pipe is 
capped at both ends and then rotated end for end at about fifty 
revolutions per minute for about five minutes. The tube is then opened, 
and the intact pellets are separated from the fines. The PDI is determined 
according to the following equation: 
##EQU1## 
Use of this invention to form a plug of partly-processed grain composition 
in the conditioner chamber increases the conditioning time for a raw grain 
composition and increases production of the conditioner without increasing 
the production costs. The starch in the raw grain composition is more 
uniformly and completely gelatinized by steam in the conditioner. The 
resulting pelletized feed product is a better quality product that 
exhibits increased durability without the necessity of added binders.