Apparatus for treating flowable materials

Jan. 30, 1962 _N. f. kruse etal 3,018,564

APPARATUS FOR TREATING FLOWABLE MATERIALS

Filed Aug. 1, 1957

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United States Patent Office

3,018,564

Patented Jan. 30, 1962

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3,018,564

APPARATUS FOR TREATING FLOWABLE MATERIALS

Norman F. Kruse and Norman H. Witte, Decatur, Ind., _ assignors to Central Soya Company, Inc., Fort Wayne, Ind., a corporation of Indiana

Filed Aug. 1, 1957, Ser. No. 675,641 6 Claims. (Cl. 34—173)

This invention relates to a material treating apparatus 10 and process, and more particularly to a means and method for treating meal. The invention is especially useful in the treatment of solvent-extracted meals, including soybean oil meal, but the apparatus and process are also applicable to the treating of other materials and to mate- 15 rials containing solvent or other liquids threon.

By way of example and for the purpose of illustration, the invention will be described herein in connection with solvent-extracted soybean oil meal.

In United States Letters Patent No. 2,585,793, there 20 is set forth a process in which solvent-extracted oil meal containing solvent or other liquid is heated below the boiling-point of water, steam being introduced into the meal to condense steam thereon so as to bring the moisture content of the meal into the range of about 14 to 25 30% and then cooking the meal at a temperature above the boiling-point of water to produce a toasted meal. In the practice, of the process, a casing provides a vertical series of kettles, and steam is introduced into various of the kettles and passed upwardly through the meal in the 30 kettles. In such a process, it was found that at best only a small fraction of the steam employed in the process could be introduced into the lower kettles, because when a large volume of steam was employed in the lower kettles, flakes of the meal were carried from the topmost 35 kettle into the condenser; as a result it was necessary to introduce the major portion of the steam within the top kettle. It has further been suggested that separate passages be provided around the kettles from the lower kettles to the upper kettles, through which steam and vapors ⁴⁰from the lower kettles could be introduced into an upper kettle. While this represents a definite advance in the art, there is still a deficiency in that the vapors and steam traveling from lower kettles are not utilized during this transit by being brought in contact with meal throughout their 45 path of travel. There has long existed a need for an apparatus and process by which vapors and steam leaving the lower kettles could be passed successively through the kettles in their upward travel to intimately contact meal therein while finally condensing the steam in an 50 upper area and while also controlling the temperature of the top portion of the meal for condensing residual portions of the steam.

An object of the present invention is to provide apparatus and means for overcoming the above-described 55 disadvantages and accomplishing the desired new results. A further object is to provide means whereby meal may be caused to follow a unique path of travel while at the same time providing large exposure areas whereby steam may be effectively passed through the meal slowly 60 and in successive steps for effecting efficient condensation upon the meal particles. A still further object is to provide apparatus for maintaining a continuous bed of meal from the top to the bottom of the apparatus while at the same time withdrawing meal at a controlled rate g5 so as to maintain a topmost layer of meal well above a heating zone so that a cooling layer is provided for condensing residual portions of the steam. Yet another object is to provide novel apparatus and process steps wherein liquid-bearing meal is freed of the liquid while at the 79 same time effecting a drying or cooking of the meal under favorable moisture conditions for toasting or cooking as the meal passes through the apparatus. Other specific objects and advantages will apear as the specification proceeds.

The invention is shown, in an illustrative embodiment, by the accompanying drawing, in which—

FIGURE 1 is a vertical, part-sectional view of apparaus embodying our invention and illustrating the process embodying our invention; FIG. 2, a transverse sectional view, the section being taken as indicated at line 2—2 of FIG. 1; FIG. 3, a broken enlarged sectional view, the section being taken as indicated at line 3—3 of FIG. 2; FIG. 4, a transverse sectional view, the section being taken as indicated at line 4—4 of FIG. 1; FIG. 5, a broken sectional detail view, on an enlarged scale, the section being taken as indicated at line 5—5 of FIG. 4; FIG. 6, a transverse sectional view, the section being taken as indicated at line 6—6 of FIG. 1; and 'FIG. 7, a detail sectional view, the section being taken as indicated at line 7—7 of FIG. 6.

In the illustration given, 1® designates apparatus providing a series of vertical kettles which are indicated by the letters A, B, C, D and E.

Casing 10 provides at the top of the apparatus an enlarged vapor dome 11 provided with an inlet 12 and with inspection openings 13. Vapors pass from the dome through the conduit 14 to a vapor scrubber 15, from the top of which a conduit 16 leads to a condenser. Slurry from the vapor scrubber is returned through pipe 18 to the upper kettle A.

A vertical shaft 19 is supported within bearings 20 within the apparatus and is connected at its lower end to a spur shaft 21 driven by a gear reducer 22 actuated by motor 23.

The kettles may be formed by a single casing with separations therebetween and with means for passing meal downwardly from one kettle to another, while also passing vapors and steam upwardly through the meal in the kettles. Each kettle consists of a cylindrical shell and a steam-jacketed bottom, and steam and condensate connections are provided for each kettle except as noted later. Each kettle is also preferably provided with a quick-opening inspection door mounted in a larger access door 24.

Kettle A is a vapor cooling and scrubbing kettle or zone, and it is provided with a jacketed bottom 25 to which steam is supplied by the pipe 26.

Kettle B is a condensation kettle or zone, and it is provided with an annular heating jacket 27 to which steam is supplied through pipe 28.

Kettle C is a steam stripping kettle or zone, and the bottom of this kettle is provided by a hollow steam sparging plate 29 provided at its upper side with a large number of steam apertures 30, as shown in greater detail in FIGS. 4 and 5. Live steam is supplied to this plate through the pipe 31.

Kettle D is a conditioning kettle or zone, and it is provided with a jacketed bottom 32 to which steam is supplied through pipe 33.

The lowermost three kettles E are similar in construction, and each is provided with a jacketed bottom 34 heated by steam. These bottoms, like the bottom 32, each have flared or funnel-like conduits 35 extending downwardly to the surface of the meal in the kettle therebelow, with the exception of the bottommost kettle E, which has an outlet 36 leading to a screw conveyor discharge 37. In conduit 36, there is provided a gate valve 38 controlled by a manually-operable thread-and-nut equipped handle member 39.

Each of the kettles is provided with a sweep for agitating the flakes in the kettle. In kettle A, a sweep 40 is employed. In kettle B, the sweep 41 has a forwardly1

3,018,564 inclined end portion for the purpose of directing flakes through the central opening 42 provided by the annular heating jacket 27. Kettle C is provided with a double· sweep 43, as shown best in FIG. 4. In kettles D and E, single sweeps 44 are employed.

In kettles D and E, each of the jacketed bottoms is provided not only with the funnel-shaped chute, but also with vapor apertures 45 in which are mounted screens 46. The screens are supported within the apertures 45 by passing cylindrical portions of the screen through the aperture and securing a flanged bottom portion 47 to the bottom of the steam jacket by bolting, or any other suitable means.

Mounted on the cylindrical wall of kettle A is a level control flag 48, which is connected to a variable speed discharge member by mechanical or electrical linkage to maintain the proper material level in the kettle. In the specific apparatus illustrated, a flat member 49 is supported upon an angularly-extending shaft 50 carried by a rotatable shaft 51. The shaft 51 extends through a bearing and seal assembly 52 and is provided with a fixed, angularly-extending lever 53. To the end of the lever is secured a tie element 54 which engages a lever 55 at the lower portion of the machine. The lever controls the operation of a variable speed drive assembly 56 which drives a sprocket shaft 57 connected by chain 58 to a sprocket mounted on the discharge screw 59. Thus, when the level in kettle A drops below a predetermined point, discharge from the lowermost kettle is reduced until the level is restored; and similarly, when the level in kettle A rises, the motor 56 is speeded up to increase the discharge from the lower kettle and bring the level to the desired point.

The kettle or basket B has enlarged or inclined side walls which are in the form of louvers 60, as illustrated best in FIGS. 1 and 3. The inclined louver walls 60 diverge from the adjacent casing walls 61 to provide their bottom with an annular steam space 62. At the same time, there is provided below the steam-jacketed bottom 27 an annular vapor space 63. The annular body of meal in the kettle C provides a long inclined face 64 adjacent the vapor space 63 so that there is presented in communication two annular spaces 63 and 62 in which the communicating meal surfaces extend at a long angle, with the result that steam or vapor may pass readily through such meal spaces without disturbing the flakes while at the same time permitting the steam to pass from the lower bed of flakes in kettle C into the upper kettle B for intimate contact with the flakes or meal therein and for condensation thereon.

If desired, the outer portion of the. kettles may be steam-traced with tubing to provide warm-up heating, or may be steam-jacketed and insulated to prevent heat loss.

Operation

In the operation of the apparatus, meal, flakes, or other material are passed through the inlet 12 into the dome and thence into kettle A. A bed of meal is maintained upon the steam-jacketed bottom 25 by the level device 49 and at such a distance above the heating member 25 that a cool layer or top portion of meal is maintained for condensing residual portions of the steam so that most of the live steam is utilized in condensing upon the meal. The meal passes downwardly in an annular stream around the bottom 25 and into the condensing zone or kettle B, and from thence the meal passes inwardly through the central opening 42 into the steam stripping zone or kettle C. Here, live steam is introduced into the meal from the sparging plate 29. The steam rises through the meal, which has now assumed an umbrella shape, and excess steam escapes through the long face 64 of the meal body into the vapor space 63 and thence through the annular vapor space 62 where it enters back into the flakes or meal in kettle B through the louvers 60. By this means, the steam is introduced along a wide annular area into the body of meal in kettle B so as to be effectively condensed therein. As already stated, the cool top layer of meal maintained in kettle A is effective in completing the condensation of the bulk of the steam. 5 From kettle C, the meal passes downwardly through an annular stream around the central disk bottom 29 into the conditioning zone or kettle D. Here, the meal changes from a doughy condition or stage to a granular meal stage. From kettle D, the meal passes downwardly 10 through the drying and cooking zones or kettles E and is discharged through the screw conveyor 37.

In the foregoing operation, it will be noted that substantially all of the steam was introduced in the third kettle C, from which flows two important advantages. 15 The feed flakes or meal entering the kettle A contain varying amounts of solvent. If the steam were introduced into the top kettle, there is a possibility that the solvent might pass through the steam area. With the present structure, if the solvent is very rich, the excess is pri20 marily boiled off in the top kettle A so that when the meal reaches kettle C in which steam is introduced, there is a substantially uniform solvent content which is effectively removed by the steam. In other words, the irregularities in solvent content are ironed out by the time they 25 reach the point at which steam is introduced into the system. The second advantage is that the topmost kettle can be kept relatively cool, at least with respect to its topmost portion, so that a much larger part of the steam can be utilized for condensation upon the flakes.

In the foregoing apparatus, there is provided means for maintaining a substantially continuous meal body from the topmost kettle to the lowermost kettle, while at the same time vapor spaces are provided between each of the kettles, the cross-sectional area of the vapor spaces 35 or passages, being larger in the uppermost kettles than in the lower kettles to accommodate the larger volume of vapors which pass through the upper kettles. It will be noted that some of the vapor spaces are annular spaces about the meal, as illustrated by spaces 62 and 40 63, while other of the vapor spaces are in the form of pockets enclosed within the meal, as, for example, the pocket area 25α below the steam-jacketed bottom 25, and the space 28α below the steam sparging plate 29. With this arrangement, vapors can be passed upwardly through ₄₅ the kettles without carrying meal with them and without channeling, and while also making intimate contact with the meal particles, and further, this structure permits the steam to condense uniformly upon the meal particle surfaces. At the same time, the bodies of meal in the 5Q lower kettles E provide in effect resistance beds which, together with their grids 46 having restricted vapor openings, prevent steam from flowing downwardly and cause it to move upwardly to perform the condensing function required.

By way of a specific example dealing with soybean oil flakes, the flakes from the extractor, containing approximately 0.5 lb. of solvent (hexane) per pound of dry flakes, enter the apparatus through the feed chute 12. Live steam of good quality is injected through the ₆q sparging plate 29 at a rate of approximately 250 lbs. of steam per ton of solvent-free flakes.

The steam flows upwardly through the unit countercurrent to the downward flow of flakes, condensing on the flakes as it rises through the bed. Steam leaving the _6g top of the flakes in kettle C reenters the flakes in kettle B via the louvered panels on the side of kettle B. The heat of condensation vaporizes the hexane from the flakes and raises the flake temperature. The temperature of the flakes in the top section of kettle A is preferably γθ maintained at about 150-170° F. Flakes leaving kettle C (below the sparging plate) are preferably at a temperature of about 210-215° F. and contain about 18-20% moisture and are substantially solvent-free.

In kettles D and E, the flakes are heated by the jacketed 75 bottoms, raising the temperature to about 220-230° F.

3,018,664 and evaporating some of the moisture from the flakes. The steam generated in this drying and toasting zone flows upwardly through the apparatus and joins the steam coming from the sparging plate to be used in the desolventizing action and in the condensing action. The 5 evaporation of steam from the meal in the drying zone thus provides a steam stripping action on the meal to insure complete removal of solvent.

While the lower section of the apparatus is commonly called the “toasting section,” actual toasting begins in 10 the top (desolventizing) kettle A as soon as the live steam condenses on the flakes. The rapid condensation of live steam produces a rapid change in the protein structure so that the intermediate sticky stage in the toasting process is largely avoided. 15

Vapors leaving the dome will be at a temperature of about 150-180° F. and will contain .06 to .20 lb. of steam per pound of hexane vapor. This small portion of the steam will not condense because the partial pressure of the steam in the vapors is substantially equal to the vapor 20 pressure of water at the temperature of the flakes in the top kettle. However, by maintaining the top portion of the meal relatively cool, as above described, the residual portions of the steam which can be condensed are utilized by condensing the same on the flakes in the 25 top layer referred to.

While, in the foregoing specification, we have set out specific apparatus and method steps in considerable detail for the purpose of illustrating the invention, it will be understood that such details of structure and of opera- 30 tion may be varied widely by those skilled in the art without departing from the spirit of our invention.