US3672294A

US3672294A - Apparatus for treating granular material

Info

Publication number: US3672294A
Application number: US117597A
Authority: US
Inventors: John O Blixrud; Wayne I Knigge; Stanley C Rustad; Takuzo Tsuchiya
Original assignee: General Mills Inc
Current assignee: General Mills Inc
Priority date: 1971-02-22
Filing date: 1971-02-22
Publication date: 1972-06-27
Anticipated expiration: 1989-06-27

Abstract

A vertically oriented pressure cooker for treating granular materials on a continuous basis. A cylindrical cooking chamber, having a flat bottom surface with a discharge opening centrally located therein, is at least partially filled with the material to be cooked, by introducing the material and pressurized steam into the top of the chamber. A vertical shaft is rotatably mounted within the chamber, and it has a pair of curved discharge arms secured to its bottom end, and a pair of leveling arms secured to it, proximate the upper part of the chamber. A cylindrical shield having a larger diameter than the diameter of the discharge opening surrounds the shaft. By rotating the shaft, a layer of material is transferred along the bottom surface of the chamber toward the discharge opening.

Description

nited States Patent Blixrud et al.

[ 1 June 27, 1972 Knig e, Bloomington; Stanley C. Rustad, Golden Valley; Takuzo Tsuchiya, Minneapolis, all of Minn.

[73] Assignee: General Mills, Inc.

[22] Filed: Feb. 22, 1971 [21] Appl. No.: 117,597

[52] US. Cl. ..99/237 R, 99/348 [51 1 Int. Cl. ..A23b 9/00 [58] Field of Search ..99/237 R, 238, 234, 348, 80;

[56] References Cited UNITED STATES PATENTS 3,202,084 8/1965 Hale ..99/237R SO URCE 3,252,406 5/1966 Altman ..99/237R 3,336,137 8/1967 Hickey ..99/237R Primary Examiner-Robert W. Jenkins Attorney-Anthony A. Juettner and L. Me Roy Lillehaughen [57] ABSTRACT A vertically oriented pressure cooker for treating granular materials on a continuous basis. A cylindrical cooking chamber, having a flat bottom surface with a discharge opening centrally located therein, is at least partially filled with the material to be cooked, by introducing the material and pressurized steam into the top of the chamber. A vertical shaft is rotatably mounted within the chamber, and it has a pair of curved discharge arms secured to its bottom end, and a pair of leveling arms secured to it, proximate the upper part of the chamber. A cylindrical shield having a larger diameter than the diameter of the discharge opening surrounds the shaft. By rotating the shaft, a layer of material is transferred along the bottom surface of the chamber toward the discharge opening.

20 Claims, 10 Drawing Figures PA'TENTEDJum I972 M a U) INVENTORS JOHN O. BLIXRUD B WAYNE mousse Y STANLEY c. RUSTAD oTfiKU T CHIYA g Arron P'A'TENTEDJUM 27 m2 3. 672. 294

sum 3 or s INVENTORS JOHN '0. autxRun BY WAYNELKNIGGE STANLEY c. RUSTAD yzsm w Arraxw r FIE? PATENTEDJum 1972 3,672,294 saw u or 6 i 1 u 74 I I 20 I n I"/ INVENTORS JOHN o. BLIXRUD WAYNE LKNIGGE BY STANLEY c. RUSTAD :fiKU TS HI A /80 P'A'T'ENTEmuuzv 12172 SHEET 6 OF 6 v INVENTORS 0.. BLIXRUD WAYNE I. KNIGGE JOHN BY STANLEY c. RUSTAD jAKu UCHIYA APPARATUS FOR TREATING GRANULAR MATERIAL The present invention relates to an apparatus for treating granular material in a continuous process, and more particularly to an apparatus for continuously cooking cereal grains and/or other food products in a steam operated pressure-type cooker.

Cookers of various types are known to those in the art, for treating and cooking granular materials. Batch-type cookers, for example, have long been used for cooking materials such as cereal grains. In such devices, the ingredients to be cooked, are introduced into a closed container and subjected to pressurized steam for a prescribed period of time. After being cooked, the batch is discharged, and the cooker is charged with a new batch. Cookers of this type have a relatively low capacity, and a system of these cookers is expensive in construction and operation. Moreover, they are somewhat inefficient because considerable amounts ofsteam and heat are lost each time the apparatus is being emptied.

Continuous cookers tend to overcome some of the disadvantages of batch cookers. Some cookers of this type involve a horizontally aligned chamber into which the material tov be cooked, and pressurized steam are continuously introduced. An auger, or other suitable means, is provided for conveying the material through the cooker toa discharge end, at a predetermined feed rate. Vertically oriented continuous cookers have also been used for cooking granular materials; in such cookers, the cooking chamber is ofttimes provided with a cone-shapedlower end. During the cooking operation, the materialflows to the bottom of the cooking chamber, after which it is discharged from the chamber. To the best of applicants knowledge, such continuous cookers are often rather complicated in design, expensive to manufacture and construct, somewhat inefficient tooperate, they require a substantial amount of space, and they have been difficult to keep clean.

It is one object of the present invention to provide a new and improved apparatus for cookinggranular materials.

Another object is to provide an improved apparatus for cooking food materials which can be operated on a continuous basis in such a manner that the uncooked material is continuously introduced into the cooker at one end, while the cooked material is continuously discharged at the other end of the cooker.

A further object is to provide a vertically oriented continuous cooker having improved means for uniformly discharging the cooked material from the discharge end of the cooker.

A still further object is to provide a vertically oriented continuous cooker having a discharge system which removes material from the cooker in an improved and efficient manner.

Another object is to provide a continuous cooker having a system for readily adjusting the discharge rate of material from the cooking chamber, with respect to the input rate of material into the chamber, so as to maintain a predetermined cook time for the ingredients.

A still further object is to provide a vertical continuous cooker which is relatively simple to construct and operate, requires a minimum amount of space, and is efficient to operate.

Other objects and advantages will become apparent from a consideration of the following specification and accompanying drawings. Before proceeding with a detailed description of the invention, however, a brief description of it will be presented.

Preferably, the invention entails a vertically oriented, cylindrically shaped, pressure tight cooking chamber having a substantially flat bottom surface upon which the material being cooked, accumulates. An inlet opening is located at the top of the chamber for introducing material into the chamber, and a discharge opening is centrally located in the bottom surface, for removing material from the chamber. A vertically oriented shaft is rotatably mounted within the chamber. A pair of curved, horizontally aligned discharge arms are attached to the bottom end of the shaft so that they are juxtaposed over the bottom surface, and a pair of horizontal leveling arms are attached to the shaft proximate the upper portion of the chamber. A cylindrical shield surrounds the shaft and helps prevent material from flowing through the discharge opening in an uncontrolled manner, and it forms an annular band having a uniform thickness. When the shaft rotates, the curved arms transfer a layer of cooked material on top of the bottom surface, toward and into the discharge opening, while the leveling arms help distribute the material evenly within the chamber. At least one inlet opening is provided for introducing pressurized steam into the chamber, preferably at a point near, or slightly below, the top surface of the uncooked material in the chamber. As the cooked material is removed from the chamber, the bed of material within the chamber flows by gravity, toward the bottom of the chamber. The chamber is preferably mounted on a scale in such a manner that the total weight of material within the cooker can be readily determined and observed; by controlling the discharge rate of the material relative to the input rate, the required cooking time of the material within the chamber can be assured. In other words, during normal operation, a state of equilibrium exists within the cooker between the discharge rate and the input rate.

The invention will best be understood by reference to the following drawings, wherein:

FIG. 1 is a partial schematic view of a system for cooking materials on a continuous basis;

FIG. 2 is a front elevational view which illustrates the cooker in greater detail;

FIG. 3 is an enlarged top plan view of the structure shown in FIG. 2;

FIG. 4 is a side elevational view of the apparatus illustrated in FIG. 2;

FIG. 5 is an enlarged sectional view taken along line 5-5 of FIG. 4, which illustrates the cooker in greater detail;

FIG. 6 is a sectional view taken along line 6-6 of FIG. 5;

FIG. 7 is an enlarged, partial sectional view taken along line 7 -7 of FIG. 5;

FIG. 8 is a partial sectional view taken along line 8-8 of FIG. 7;

FIG. 9 is a partial sectional view which illustrates another embodiment of the invention; and

FIG. 10 is a sectional view which shows a further embodiment of the invention.

FIG. 1 illustrates a system for continuously treating or cooking a granular material, such as a selected cereal grain. As depicted, the system includes a feeder 10 for conveying materials to be cooked, such as the cereal grain, flavoring ingredients, etc., from an appropriate source 12 at a prescribed feed rate, into the inlet end 14 of a mixer 16. As the mixed material is discharged from the discharge end 18 of the mixer,

it is introduced into a vertically oriented cooking chamber designated generally by numeral 20. As the material enters the cooking chamber 20, it forms a bed of material which passes from the top of the chamber to the bottom thereof, by gravity. While in the chamber, the granular material is subjected to pressurized steam for a predetermined period of time, so that the ingredients are completely cooked prior to being discharged from the cooking chamber. The cooked material is discharged from the cooker 20 onto a conveyor 21, after which it can be further processed if desired.

FIGS. 2-4 illustrate the cooker 20, and the manner in which it is supported, in greater detail. A main frame structure 22, which includes four vertical legs 24, is positioned on the floor of a plant or manufacturing facility. An intermediate frame 26 is supported by the main frame 22, by means of a scale mechanism designated generally by numeral 28, so that it is suspended above the floor, and supported solely by the main frame 22. The intermediate frame 26 also includes four vertical legs 30 which are connected to each other by appropriate cross members, to form a structure for supporting the cooking chamber'20. The outer surface of the chamber 20 is secured to cross members 32 at 34, by appropriate means (not shown in detail); so that the chamber 20 is indirectly supported by the main frame 22, by means of the intermediate frame 26.

The scale mechanism 28 is a commercially available item, which can be readily purchased on the market; thus, it will not be described in detail. Toledo Scale Company of Toledo, Ohio, for example, manufactures a number of tank scales which might be satisfactorily used. Generally, scales of this type include a system of torsion pipes, lever arms, and appropriate mechanical linkages for connecting the lever system to an indicating head 36, which registers the total weight being exerted on the scale. Satisfactory results have been obtained by using Model No. 2382 with a N0. 33 Head, manufactured by the Toledo Scale Company. As the total weight of the intermediate frame 26, the chamber 20, and the ingredients within the chamber changes, such changes are readily indicated on the indicating head 36. It might be pointed out that if desired, the scale system might be tared by procedures known to those in the art, so that only the weight of the material within the cooker registers on the indicating head 36.

A first rotary valve 38 is mounted proximate the top of the cooking chamber 20, and it is interposed between the discharge end 14 of the mixer 16, and an inlet opening in the top of the chamber, by an appropriate conduit 40. A motor 42, mounted on the intermediate frame 26, is operatively connected to the rotary valve 38 by appropriate means. A second rotary valve 44 is attached to the bottom of the cooking chamber so that cooked material is discharged from the chamber directly into the valve 44. A motor 46 provides motive power for the valve 44. Rotary valves of this type are generally well known to those in the art. Such valves permit material to be introduced into, and discharged from, the cooking chamber without reducing the pressure within the chamber.

Openings

48 and 50, each provided with tempered sight glass, are provided for permitting an operator to look into the interior of the cooking chamber 20 while the cooking operation takes place.

Pressurized steam is introduced into the upper portion of the cooking chamber by means of conduits 52 (note FIG. 1) which are connected to a steam source 54 by appropriate conduits. Pressurized steam is also introduced into the lower end of the cooker by means of a conduit 56, which is also connected to the steam source 54.

Pressure regulators

58 and 60 control the amount of steam introduced into the

conduits

52 and 56, respectively.

FIG. illustrates the cooker 20 in greater detail. Generally, the cooking chamber 20 is comprised of an elongated cylindrical shell 62, a rounded cover or top 64, and a circular end plate or bottom surface 66. The cover 64 and the bottom plate 66 are secured to the shell by appropriate means, eg bolts, so that pressure tight seals are formed. The plate 66 is provided with a discharge opening 68 centrally located therein, and an inlet opening 70 is provided in the cover 64 so that it is proximate the upper portion of the cooking chamber. The conduit 40 introduces uncooked material from the rotary valve 38 into the cooking chamber. A short hopper 72, having almost vertical sidewalls, is secured at one end to the bottom 66, so that it surrounds the discharge opening 68. The second rotary valve 44 is secured to the bottom of the hopper 72 so that the cooked material passes from the chamber 20 into the rotary valve 44.

A shaft 74 is rotatably mounted within the cooking chamber 20 so that its longitudinal axis is vertically oriented. Preferably, the shaft 74 is mounted within the chamber 20 by rotatably supporting its upper end 76 in suitable bearings so that its lower end 78 is cantilevered within the chamber 20. In this regard, P16. illustrates one such arrangement for supporting the shaft 74; this arrangement will be described in greater detail hereinbelow. Cantilevering the shaft 74 eliminates the requirement for bearings and bearing supports in the lower portion of the chamber 20. If preferred, of course, such bearings and supports might be provided; it has been found, however, that they do have a tendency to cause materialto collect or become deposited on the members.

A cylindrical sleeve or shield member 80, comprised of upper and

lower portions

82 and 84, respectively, is positioned within the chamber 20 so that it surrounds the shaft 74, and is substantially coaxial with it. An annular space 83 is formed between the walls of the chamber and the shield 80, and the granular material, designated by letter M, is deposited within this space. Furthermore, the shield forms an innercompartment 85 which surrounds the shaft, in which none of the material is permitted to accumulate; the compartment 85 has a larger diameter than the diameter of the opening 68. A plate member 86 is secured to the top of the upper portion 82, and it is sealed relative to the shaft 74 by means of a split collar 88. A ring-shaped member 90 is secured within the bottom end of the lower shield portion 84, and a circular plate 92, having an opening surrounded by a hub 94, is attached to the ring 90 by appropriate means. As shown, the diameter of the plate 92, and thus the shield 80, is larger than the discharge opening 68, and it is spaced from the bottom surface 66 by a prescribed distance.

Since the shield 80 and the plate 92 have a larger diameter than the discharge opening 68, the granular material M is effectively prevented from freely flowing through the discharge opening 68. Moreover, it might be emphasized that the shield 80 cooperates with the outer chamber wall to define the annular space 83. It has been found that by keeping the thickness of this annular space relatively narrow, the

curved discharge arms

136 and 138 are able to remove a layer of material from the chamber more efficiently, because just a portion of the bottom surface, rather than the entire surface, has material thereon. No specific dimensions of the annular space are herein set forth, because the relative thickness can vary; it should be borne in mind, of course, that the shield diameter should be larger than the diameter of the discharge opening. It might also be pointed out that omission of the shield 80 generally tends to permit cooked material to flow through the opening 68 in an uncontrolled manner so that the rotary valve 44 might become choked or plugged, and operation of the discharge arms would be rendered inefiicient. As a result, cooked material tends to be removed primarily from the center portion of the chamber, and not from an area proximate the chamber walls. While the shield has been described as being cylindrical, a cone-shaped shield might be satisfactory for some applications as well, the base of such cone being larger than, and proximate the discharge opening in the bottom of the cooker.

The bottom end 78 of the shaft 74 is positioned within the hub 94 and it is connected to the hub by means ofa key 96. A retaining washer and nut assembly 98 effectively seals the bottom end of the shaft and the hub 94 together. A bushing 100, mounted in supporting webs or fins 102, aids in supporting the shaft 74 with respect to the shield portion 84. The upper end 104 of the shield portion 84 is formed having a reduced diameter so that it forms a shoulder 106 with the main part of the shield portion 84. A bushing 108 surrounds the shaft 74 so that it is interposed between the shaft and the top of the shield portion 84. A bearing housing 110, supported by web arms 112, houses a bearing 114; such bearing 114 being interposed between the upper end of the shield 104 and the housing 110. A shield drum ring 116 surrounds the lower end of the upper shield 82, and it fits within a groove 118 formed in the bearing housing 110, thus providing a tight seal between the

shield portions

82 and 84.

A pair of horizontal leveling

arms

120 and 122 are fixedly connected to the shaft 74 by means ofa hub 124 and key 126, so that they project radially away from the shaft axis. As illustrated, the arms are disposed proximate the upper portion of the chamber 20 so that they project through

openings

128 and 130, respectively, in the upper shield portion 82. A pair of U- shaped

members

132 and 134 are secured to the under surface of

arms

120 and 122, respectively, so that they project toward the bottom of the chamber. The

arms

120 and 122 are positioned on the shaft 74 so that as the shaft rotates, the

members

132 and 134 level or distribute the granular material as it is introduced into the cooking chamber.

A pair of elongated, curved sweep or discharge

arms

136 and 138 are secured to the bottom end 78 of the shaft, and more particularly the circular plate 92, so that they are juxtaposed over the bottom surface 66 of the chamber. In this regard, note FIGS. 7 and 8 as well. As shown in FIG. 7, the arm I 138 is secured to the plate 92 at a point on the left side of the shaft 74 and hub 96, so that it effectively curves or sweeps around the shaft 74, toward and along the wall of the chamber so that it terminates on the right side of the shaft 74. The arm 136, on the other hand, is attached to the plate 92 at a point on the right side of the shaft so that it curves around the shaft, toward and along the chamber wall, but on the opposite side when compared to the arm 138. As shown more fully in FIG. 8, the

arms

136 and 138 are positioned adjacent to the bottom surface 66 so that they contact or sweep along such surface, as the shaft 74 is caused to rotate. For purposes of description, each arm will be described as having an inner curved surface 140 and an outer curved surface 142. Each inner surface 140 is provided with an elongated indentation or groove 144. As viewed in FIG. 8, the groove 144 is formed so that it has a first sloping surface 146 which forms an angle of prescribed magnitude with the top surface 156, and a second sloping surface 148 which is shorter than the surface 146 and which forms an angle of a prescribed magnitude with the bottom surface 154 of the arm. An edge 152 is formed by the sloping surface 148 and the bottom surface 154 of the arm. The

surfaces

146 and 148 meet to form a somewhat curved portion designated by numeral 150. The top surface 156 of each arm is tapered slightly from a maximum dimension proximate the shaft 74, to a minimum dimension proximate the chamber wall. In other words, the thickness of the discharge arm increases from its outer extremity toward the point of attachment proximate the shaft 74.

As the shaft 74 is caused to rotate, the

discharge arms

136 and 138 sweep along the bottom surface 66 of the chamber and transfer a layer of material equal to the thickness of the arms, toward the center of the chamber, and more specifically toward the discharge opening 68. The specific cross-sectional shape of the inner surface 140 of the arms, aids in preventing the layer of material from tending to slide over the top surface 156 of the arms, because the sloping surface 146 tends to exert a slight downward force on the material proximate such surface; the edge 152 and the surface 148, on the other hand, tend to scrape or lift the cooked material off the bottom surface 66. Thus, each

arm

136 and 138 engages a layer of material and transfers it toward the center of the chamber.

Rotational movement is imparted to the shaft 74 by means of a variable speed motor 160, mounted at the top of the intermediate frame 126 (note FIGS. 2 and 4). The motor 160 is operatively connected to a pulley 162 secured to the top end 78 of the shaft. As depicted in FIG. 2, a support structure or bearing housing 164 is provided for supporting the shaft 74; such housing 164 in turn being attached to the intermediate frame 26 by a horizontal cross member 166. The bearing housing will be described in greater detail below, in conjunction with the description of FIG. 10.

As illustrated in FIG. 5, a number of vertically aligned webs or fins 168 are secured to the inner surface of the chamber 20 so that they are spaced around the shield 80. These fins aid in causing the material to move downwardly within the chamber during the cooking process, rather than in a helical manner due to the rotational effect of the shield 80. The ends 170 of steam conduits 52 within the chamber, are bent or curved so they direct the steam in a downward direction. Preferably, the tip of the conduit should be positioned proximate the top surface of the material M within the cooking chamber so that the steam is directed onto the top surface of the material. In some instances, it might be preferred to introduce the steam below the top surface of the material, and in other instances it might be preferred to position the conduits closer to the top of the chamber. While two conduits 52 are shown for introducing the steam, it should be recognized that additional conduits could be added as well.

A brief description of the

rotary valves

38 and 44 might be in order. Generally, valves of this type are well known in the art, and they are sometimes referred to as star valves. It has been found that both valves can be of the same general construction, although it is preferred to use a somewhat larger size for the bottom valve 44. FIGS. 5 and 6 illustrate the general construction of one type of rotary valve used with good results. The valve 44 includes a housing 172 which is secured to the hopper 72 at 174 to provide a pressure tight seal. A fixed, tapered liner 176 is positioned within the housing, and an inlet passage 178 and a discharge passage 180 communicate with the liner 176. A tapered rotor 182, having a plurality of pockets 184 formed by radially projecting webs 186, is fixedly mounted on a rotatable shaft 188, driven by the motor 46. Appropriate adjusting means are provided in a housing 190, for adjusting the clearance between the liner 176 and the rotor 182. Valves of this type might include a variety of features, such as an appropriate vent for permitting the steam to escape from a pocket filled with cooked material, before the cooked material is discharged from the valve.

Steam is introduced into the cooking chamber 20 at such a rate that a constant steam pressure is maintained within the cooking chamber. It has been found that a steam pressure of about 18-21 psig, and a corresponding temperature of about 250260 F., works satisfactorily for cooking most cereal grains. It should be realized, of course, that pressures much higher, e.g. 40 psig, or much lower, e.g. 5 psig, than this amount might be used for certain applications as well. At higher pressures, the required cook time decreases.

The feed rate of material into the cooker is determined by a number of factors, such as the desired cook time of the ingredients, the specific type of material being cooked, the pressure and temperature conditions within the chamber, the size or volume of the chamber, the amount of material within the chamber, and the like. It has been found that a cook time of about 55-65 minutes at a pressure of about 18-21 psig is adequate for most cereal grains. As an example, if the total weight of the material within the chamber is maintained at about 600 pounds, and a cook time of about 60 minutes is desired, a constant feed rate of about 10 pounds per minute into and out of the chamber should be maintained. The discharge rate of material from the chamber can be varied by increasing or decreasing the rotational speed of the shaft 74; generally, it should be approximately the same rate as the input rate.

In operation, ingredients to be cooked, such as wheat and one or more flavorants, are fed from the feeder 10 into the mixer 16, from which they are discharged into the rotary valve 38 and the cooking chamber 20, at a prescribed feed rate. Pressurized steam is also introduced into the top of the chamber 20 through the conduits 52, at a prescribed pressure, as well as through the conduit 56 into the bottom of the cooking chamber. In this regard, it has been discovered that introduction of steam into the bottom of the chamber helps equalize the pressure within the chamber, and helps prevent the material from being forced out through the discharge opening 68, due to the pressure within the chamber. It might be mentioned that the steam tends to condense on the walls of the chamber, thus adding moisture to the material therein. If this is found to be objectionable, a steam jacket, or insulation, might be provided on the exterior of the cooking chamber; or if preferred, the chamber walls might be heated by appropriate heat elements.

The material is permitted to accumulate within the chamber until at least half of the desired load, as shown on the indicator head 36 of the scale, is deposited therein. The motor 160 can then be energized so that the shaft 74 is caused to rotate at a relatively slow speed. A slow speed is selected so that a minimum amount of material is discharged from the chamber. As the top surface of the material within the chamber increases in height, it tends to accumulate in an area directly below the inlet opening 70. As the shaft 74 rotates, however, the leveling arms and 122 distribute the material within the chamber. Since the plate 92 is larger than the discharge opening 68, very little, if any, material is discharged from the chamber 20, until the shaft 74 is caused to rotate.

As the weight of the material within the chamber increases, the force exerted on the scale 28 also increases until the desired weight figure is indicated on the indicator head 36. Since the shaft 74, the shield 80, and the

sweep arms

136 and 138, are being rotated, a certain amount of material is removed from the chamber through the discharge opening 68. The amount of material being removed, of course, depends upon the rotational speed of the shaft. It might be necessary to dispose of the initial part of the material discharged from the cooker, due to incomplete cooking, since it may not have been in the chamber for the required amount of time. Once the material has been within the chamber for the prescribed amount of time, under the prescribed pressure and temperature conditions, the system can be operated on a continuous basis, and the material passes or settles to the bottom of the chamber by gravity. The

rotary valves

38 and 44 permit the material to be introduced into, and discharged from, the cooking chamber without adversely affecting the internal pressure of the chamber. If the pressure does drop, it can be increased by adjusting the

pressure regulators

58 and 60. If desired, pressure relief valves might be provided in the walls of the chamber for permitting steam to escape if the pressure exceeds a prescribed maximum. It has been found that the displacement volume of the bottom rotary valve 44 should be slightly greater than the displacement volume of the unloading device, i.e. the shaft 74 and the

arms

136 and 138, so as to prevent any of the material from being static in the hopper 72.

As described above, as the

curved discharge arms

136 and 38 are caused to rotate about the shaft axis, a layer of material corresponding to the approximate thickness of the discharge arms is transferred along the bottom surface 66 toward the discharge opening 68. Movable, curved arms of this type assure that a layer of material covering the entire bottom surface of the chamber is removed, rather than material from isolated or selected areas. In the event that the weight of the material within the chamber exceeds the predetermined amount as shown on the indicator head 36, the operator can increase the discharge rate of the material from the chamber, by increasing the rotational speed of the shaft 74. Conversely, if the discharge rate is too fast, the amount of material will not reach the predetermined weight figure, as shown on the indicator head 36, and the material will not be adequately cooked. In other words, by reducing the rotational speed of the shaft 74, the operator can reduce the discharge rate of material from the chamber. Thus, feed through the cooker is in a state of equilibrium when the weight of the material within the chamber, as shown by the indicator head 36, remains constant.

While the above system has been described as being semiautomated, because the operator can regulate the rotational speed of the shaft 74, the entire system might readily be made automated to such an extent that deviations or fluctuations in the total weight of the material within the cooking chamber, automatically cause the rotational speed of the shaft 74 to increase or decrease. Moreover, it should be recognized that other types of systems might be used for sensing and controlling the weight of material within the cooker. Load cells, for example, might be used for suspending the cooker and its contents. Load cells and their operation are well known to those skilled in the art, and will not be described in further detail.

FIG. 9 illustrates another embodiment of the invention, which is quite similar to the embodiment already described. In this construction, the lower portion 196 of a cylindrical shield 192 remains stationary relative to the upper shield portion 194 and the shaft 198. Two support bars 200 are attached to support members 202 on opposite sides of the shield, such support members in turn being attached to the interior of the cooking chamber 206 by webs or fins 204. A pair of ears or lobes 208 are secured to opposite sides of the lower shield 196, and they in turn are secured to the support bars 200. A bushing 210 is mounted in a bearing retainer 212, the latter being supported at the top end 214 of the lower shield; this structure provides a rotatable support between the shaft 198 and the lower shield 196. The lower end of the shaft 198 is also rotatably mounted relative to the lower shield by means of a bearing 216 mounted in a bearing retainer 218, the latter being supported by webs or fins 220 secured to the inner surface of the lower shield 196.

A pair of curved discharge arms 222 are secured to a circular plate or disc 224 by appropriate means, such plate being attached to the shaft 198 by means ofa hub 226 and key 228. A ring-shaped member 230 is secured to the inner surface of the lower shield 196, and an appropriate seal is provided for preventing material from passing between the plates 224 and the ring 230, into the interior of the shield 192. A pair of leveling arms 232, each having a U-shaped member 234 secured thereto, are attached to the shaft 198 so that they are rotatable with the shaft. Since the upper shield portion 194 rotates relative to the lower shield portion 196, a shield drum ring 236 provides a seal between the two components.

A pair of conduits 238 are provided for introducing pressurized steam into the chamber 206. Note that the conduits are positioned so that the steam is injected directly into the bed of granular material at a point slightly below its top surface.

The operation of this embodiment is substantially the same as the operation of the apparatus described in FIG. 5. The major difference is that the lower shield 196 remains fixed, while the shaft 198, the

arms

222 and 232, the plate 224, and the upper shield 194 are caused to rotate. Moreover, the pressurized steam is introduced directly into the bed of material being cooked, rather than onto the top surface of the granular material as described hereinbefore.

FIG. 10 illustrates another embodiment in which a vertically oriented shaft 242 is cantilevered within a cooking chamber 240 by rotatably supporting its upper end 244 in a bearing housing 246 located at the top of the cooking chamber. The bearing housing is similar to the bearing housing 164 referred to generally above. Note that the upper end portion of the shaft has a slightly smaller diameter than the remainder of the shaft so that a shoulder 248 is formed. The inner surface of the housing 246 is formed into three sections, a first cylindrical section 250 which is larger than, and which forms a first shoulder 252 with a second cylindrical section 254, and a third cylindrical section 256 which is smaller than, and which forms a second shoulder 258 with the second cylindrical section 254. A pair of bearings are positioned within the first cylindrical section 250. An angular contact bearing 260, capable of withstanding both thrust and radial loads, is positioned on the first shoulder 252, and it is separated from a second bearing 262 which is capable of withstanding radial loads, by a sleeve or bearing spacer 264. As shown, the shoulder 248 formed on the shaft 242 abuts against the under surface of the bearing 260, and a lock nut and washer 266 threadedly engages the top of the shaft so as to lock the bearings and spacer together. A shaft seal 268 positioned within the third cylindrical section 256, prevents dust and other material from entering the bearing housing 246 from the cooking chamber.

A cylindrical shield 270 having a top cover or plate 272, and a bottom plate 274 which is attached to the bottom of the shaft 242 by appropriate means, is caused to rotate as the shaft rotates. As shown, the diameter of the plate 274 is larger than a discharge opening 276 in the bottom surface of the chamber. Appropriate seals are provided for preventing any material from entering the interior of the shield 270. A pair of curved discharge arms 278, similar to the discharge arms described hereinbefore, are attached to the bottom plate 274, and a pair of leveling arms 280 are secured to the shaft 242 so that they project through openings 282 in the shield 270. Each of the arms 280 is provided with a U-shaped member 284 secured to its under surface.

A somewhat different system is shown for introducing pressurized steam into the chamber 240. The shaft 242 is provided with an elongated passage 286 therein which is coaxial with the shaft axis. Each of the leveling arms 280 is also provided with an elongated passage 288, which is perpendicular to, and which intersects with, the passage 286, and each of the U- shaped members is provided with a U-shaped passage 290, which intersects with the passages 288. A plurality of discharge ports 292 are located in each U-shaped member 284, for discharging steam from the passages into the chamber. Thus, a continuous passage is provided from the top of the shaft 244 to the interior of the chamber. A rotary union 294 is secured to the top of the shaft, and it permits pressurized steam to be introduced into the cooking chamber 240 from an appropriate source (not shown) through conduit 296, while the shaft is rotating.

The operation of this embodiment is basically the same as the previous embodiments, in that the granular material forms a bed in the cooking chamber, having a height dependent upon the input rate, relative to the discharge rate of material. As the shaft 242 rotates, the shield 270, the discharge arms 278, and the leveling arms 280 rotate about the shaft axis. Pressurized steam is introduced directly into the bed of material through the

passages

286, 288, and 290, thus causing the granular material to be cooked. As the curved discharge arms 278 revolve about the shaft axis, cooked material along the bottom surface of the chamber is transferred to the discharge opening 276, and ultimately through such opening to the exterior of the cooking chamber.

In the above description and attached drawings, a disclosure of the principles of this invention is presented together with some of the embodiments by which the invention may be carried out.

Now, therefore, we claim:

1. A continuous pressure cooker for cooking granular material comprising a substantially pressure tight cooking chamber aligned along a vertical axis so that it has a top end and a bottom end, the surface of said bottom end being substantially flat, an inlet opening proximate the top end for introducing material into the chamber against the pressure therein, a discharge opening at the bottom of the chamber for removing material from the chamber without reducing the pressure therein, said material passing from the upper portion of the chamber to the lower portion thereof by gravity, means for introducing pressurized steam into said chamber, movable means at the bottom of said chamber for discharging the cooked material from the chamber by transferring a layer of the material proximate the bottom surface of the chamber toward the discharge opening, and means for controlling the discharge rate of the material from the chamber.

2. The combination of claim 1 wherein a shaft is mounted within said chamber so that it is rotatable about said vertical axis, and a shield member is provided which surrounds at least the lower portion of said shaft, the cross-sectional dimension of the lower portion of said shield being larger than the crosssectional dimension of the discharge opening.

3. The combination of claim 2 wherein means are provided within the chamber for aiding in directing the material vertically toward the discharge end of the chamber.

4. The combination of claim 2 which includes hopper means, and means for securing said hopper means to the discharge end of the chamber so that it surrounds the discharge opening, and steam inlet means are provided in said hopper means for introducing pressurized steam into the bottom of the chamber.

5. The combination of claim 1 wherein a shaft is mounted within said chamber so that it is rotatable about said vertical axis, and the movable means for discharging the material from the chamber includes at least one elongated discharge arm connected to the bottom end of said shaft so that it is juxtaposed over the bottom surface of the chamber, said discharge arm transferring cooked material along the bottom surface of the chamber toward the discharge opening.

6. The combination of claim 5 wherein the chamber has a circular cross section and the discharge opening is centrally located in the bottom surface of the chamber.

7. The combination of claim 6 wherein means are provided over said discharge opening for minimizing the amount of material which passes through said opening, said discharge arm being interposed between said means and the bottom surface of the chamber.

8. The combination of claim 6 wherein the shaft is supported and joumalled at its upper end so that its lower end is cantilevered toward the bottom surface of the chamber, a tubular shield member is provided within the chamber which surrounds said shaft so that an annular space is formed between the walls of said chamber and said shield, said shield member having an upper end and a lower end and a larger cross section than the cross section of the discharge opening, and means are provided at each end of the shield for preventing the granular material from entering said shield member.

9. The combination of claim 8 wherein at least one horizontal arm member is fixedly attached to the vertical shaft proximate the upper end of the shield member, in such a manner that it projects through the surface of said shield.

10. The combination of claim 9 wherein the horizontal arm is provided with projecting means on its undersurface for leveling material within the chamber, as the arm rotates about the shaft axis.

11. The combination of claim 8 wherein means are provided for fixedly connecting said shield member to the shaft so that it rotates about the shaft axis as the shaft rotates.

12. The combination of claim 8 wherein the shield is comprised of two parts, an upper portion which is fixedly connected to the shaft so that it rotates with said shaft, and a lower portion which is rotatably mounted relative to the shaft by fixedly connecting a portion of it to the inner surface of the chamber, and sealing means are provided for preventing material from passing between the joint formed by said two sections.

13. The combination of claim 6 wherein a pair of discharge arms are provided on opposite sides of the shaft, each arm having its longitudinal axis horizontally aligned and having a curved configuration which extends from the shaft toward and along the curved surface of the chamber, said arms transferring a layer of material along the bottom surface of the chamber toward the discharge opening as the shaft rotates.

14. The combination of claim 13 wherein each discharge arm has a prescribed thickness, an inner curved surface, and an outer curved surface, said inner curved surface having an indentation therein.

15. The combination of claim 5 wherein at least one horizontal leveling arm is fixedly attached to the vertical shaft proximate the upper end of the chamber.

16. The combination of claim 15 wherein a passage is provided in the vertical shaft which extends along the longitudinal axis of said shaft, a horizontal passage is provided in the horizontal arm which intersects with the passage in the shaft, at least one orifice is provided in the arm member which forms an opening from the horizontal passage into the cooking chamber, and means for linking said shaft and shaft passage to a source of pressurized steam.

17. The combination of claim 5 which includes a first rotary valve, means for attaching said first rotary valve proximate the upper part of the chamber so that the material to be treated passes through said valve before it passes through the inlet opening into the chamber, a second rotary valve, means for attaching said second rotary valve proximate the lower part of the chamber so that the cooked material passes through the discharge opening and through said second rotary valve, said rotary valves maintaining the pressure within the cooker at a prescribed level.

18. The combination of claim 1 wherein the discharge rate of material from the chamber is controlled relative to the input rate of material into the chamber.

19. The combination of claim 18 wherein the controlling means includes a scale having an indicator head, said cooker being mounted on said scale so that any changes of the weight of material within the cooker are registered on the indicator head.

20. A continuous pressure cooker which comprises a substantially pressure tight cylinderical cooking chamber aligned along a vertical axis so that it has a top end and a bottom end, the surface of said bottom end being substantially flat, an inlet opening for continuously introducing material to be cooked into the chamber, a discharge opening at the bottom of the chamber for continuously removing the cooked material from the chamber, means for introducing pressurized steam into said chamber, means associated with said inlet and discharge openings for maintaining a predetermined pressure within the chamber, a vertically oriented shaft rotatably mounted within said chamber, movable means connected to said shaft proximate the discharge opening for transferring a layer of cooked material along the bottom surface of the chamber through said discharge opening as the shaft rotates, means including a shield member which surrounds at least the lower portion of said shaft, for effectively preventing said material from flowing through the discharge opening unless the shaft rotates, scale means, and means for positioning said cooker on said scale means so that any changes of the weight of material within the cooker are registered by said scale means.

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Claims

2. The combination of claim 1 wherein a shaft is mounted within said chamber so that it is rotatable about said vertical axis, and a shield member is provided which surrounds at least the lower portion of said shaft, the cross-sectional dimension of the lower portion of said shield being larger than the cross-sectional dimension of the discharge opening.

8. The combination of claim 6 wherein the shaft is supported and journalled at its upper end so that its lower end is cantilevered toward the bottom surface of the chamber, a tubular shield member is provided within the chamber which surrounds said shaft so that an annular space is formed between the walls of said chamber and said shield, said shield member having an upper end and a lower end and a larger cross section than the cross section of the discharge opening, and means are provided at each end of the shield for preventing the granular material from entering said shield member.