US3269428A - Method for packaging dry divided solid materials - Google Patents

Description

Aug. 30, 1966 l. H. STOCKEL ET AL 3,269,428

METHOD FOR PACKAGING DRY DIVIDED SOLID MATERIALS Filed Oct. 10, 1961 5 Sheets-Sheet l I VENTORfi. OL 1 5/21; 77 rcHEA/HL. Y [VA/a H.5'Toc/(EL.

Aug. 30, 1966 1. H. STOCKEL ET AL 3,269,428

METHOD FOR PACKAGING DRY DIVIDED SOLID MATERIALS Filed Oct. 10, 1961 5 Sheets-Sheet 2 INVENTORS.

0L 1 52 777'CHE/V/7L. BY [l/AEHSTocKEL.

(QwruVAcM ATTORNEYS.

Aug. 30, 1966 l. H. STOCKEL ET AL 3,259,423

METHOD FOR PACKAGING DRY DIVIDED SOLID MATERIALS Filed Oct. 10, 1961 5 Sheets-Sheet 3 Aug. 30, 1966 I. H. STOCKEL ET AL 3,269,423

METHOD FOR PACKAGING DRY DIVIDED SOLID MATERIALS 5 Sheets-Sheet 4 Filed Oct. 10. 1961 Inna mwhdmziib 1 QGEVQU +IIH| J am rllillll w United States Patent 3,269,428 METHOD FOR PACKAGING DRY DIVIDED SOLID MATERIALS Ivar H. Stockel, New City, N.Y., and Oliver 1R. Titchenal, Rumford, R.I., assignors to St. Regis Paper Company, New York, N.Y., a corporation of New York Filed Oct. 10, 1961, Ser. No. 144,142 Claims priority, application Belgium, Oct. 24, 1960, 474,115, Patent 596,334 14 Claims. (Cl. 141-10) This invention relates to the packaging of dry divided solid material, and more particularly, to methods and apparatus for fluidizing such material and delivering it into packaging containers, such as paper bags, for example, while in a fluidized state.

This application is a continuation-in-part of our copending application Serial No. 810,465, filed May 1, 1959.

Constructions of the class described are well known to the art and much effort has been expended in the development of various operating methods and apparatus. One familiar construction that has been utilized heretofore includes a vertical bin open at the top and having a discharge spout at its lower end. Air is introduced under controlled pressure into the lower end of the bin through an inclined air pervious pad to fiuidize the material in the bin and carry it out through the spout. While this type of appaartus has achieved a certain degree of commercial success, it, along with other known apparatus of the class described, has proven to be far from satisfactory in a number of respects. For example, it has been found that while known apparatus may perform reasonably well for one or a relatively small group of dry divided solid materials, no known packer is satisfactory for all such materials or even for more than a few types of material. Accordingly, to package several different materials, a number of different, costly machines were necessary.

Additionally, bearing in mind that it is the general object of all packaging equipment of the class described to obtain good weight results, as dust-free operation as possible, and good filling sped, all with as little air as possible, it has been found that in known fluidizing packers, it is often necessary to sacrifice one or more of these objectives in order to obtain desired results with the others, so that none of the known commercial fluidizing packers is entirely satisfactory.

It is thought that the failure of the art to produce a suitable packer is due to the fact that many of the presently held theories concerning the performance of dry divided solid material when fluidized in air for discharge from packaging machinery, are not entirely correct.

Accordingly, in an effort to develop a method and apparatus of the class described that would not only operate in a satisfactory manner for one or a relatively small group of materials under various conditions, but would also prove satisfactory for all dry divided solid materials under a variety of conditions, an extensive program of research and development was undertaken in which the conduct of .air and materials under fluidization was studied. As a result of this undertaking, an improved and expanded theory concerning the nature and conduct of fluidized solids as related to packaging was developed and, in order to facilitate a better understanding of the present invention, will be set forth briefly and in part here.

Consider a particle mass uniformly packed and lying at rest in a bin of uniform cross-section and open at its top through which it may be fed material to be packed. Each particle is supported against gravity by its neighboring particles creating a total weight per unit of area, or head of material in the bin. If air is caused to flow upward through the voids between the particles from a uniform supply of air entering through the bottom of the bin, the

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air flow will drag upward upon the particles and thus help to support them. The greater the air flow, the greater the support. There is a volumetric air flow rate (c.f.m.) for which the upwardly acting drag support on each particle just balances its downwardly acting weight. This is called the point of incipient fluidization, or the critical volumetric air flow rate. The pressure drop through the material for this critical volumetric air flow rate may be termed the critical pressure drop. For volumetric air flow rates less than this critical value, support of the particles is shared by drag and contacting neighboring particles; for volumetric air flow rates greater than the critical value, the drag support overbalances gravity and the particles momentarily move upwardly. As a result. of this upward movement, the particle mass occupies a larger volume in the bin, and the void space between particles is increased; therefore, the air velocity need not increase. The column expands until the increased volumetric air flow rate above such critical rate causes no increase in velocity immediately surrounding and supporting a particle. Additionally, the pressure drop through the head of material remains very nearly constant above the critical volumetric air flow rate.

In fluidizing a material, with a volumetric air flow rate equal to or greater than critical air flow rate, an air pressure is obtained in the material at the bottom of the column which is equal to the head of material, that is, the weight of the material in the column per unit of column cross-sectional area. What is important here is that this head of material is not developed by the particles of material resting upon other particles, but rather that an apparent head of material is developed in the manner described wherein the material throughout the column is fluid-like in behavior, that is, easily deformed and ready to pass through a filling spout into a bag, for example.

From the foregoing, it will be seen that the air pressure required at the bottom of a column of material to fluidize that column is the fluidized density of the material times the height of the column. It is somewhat more complicated to determine the critical volumetric air flow rate for a given material since this depends not only upon the material density but also upon particle size distribution and shape distribution. Since, for direct determination, a tedious microscopic examination is necessary, a simple experiment is recommended. Air flow rate is increased in an open bin until there is insignificant or no further increase in pressure in the bin, indicating that the critical volumetric air flow rate has been reached.

If now we open a discharge spout adjacent the bottom of the bin, we find that the apparent head of material in the column due to the pressure of particle supporting air will cause material and air to flow out of the bin through the spout. The material flows downwardly in the bin and thus reduces the upward air velocity below that at which it moved upwardly when the spout was closed. In fact, if material down flow velocity is large enough, the air may stand still or even flow downwardly. Therefore, it follows that maintenance of fluidization of downflowing material may require less air flow through the pad at the bottom of the bin than does fluidization of a stationary column, and quite often no air flow is required through the pad.

The foregoing discussion has assumed an ideal material. In practice, it is often found that initial voids vary from one region to another in the bin, and air does not flow uniformly through the material. Or, the material may be partially bound, plugged or bridged so that as the critical point is reached, some of the material expands, but bound portions of the material are partially supported by wall friction. The expanded material, being lighter, causes a smaller pressure drop to exist across itself than that which would occur with ideal material. Unfortunately, this smaller pressure drop further starves the bound region so that additional increases in total fiow only further expand the lighter expanded material, and further starve the bound material. Thus, the condition is self-aggravating. In time, agitation may wear the bound material away, but considerable time may be required for this; or, on the other hand, the extent to which the majority of air flow may localize varies from the mild extent already described, to an extreme in which a nearly material-free channel develops which may occupy less than 1% of the bin cross-section but carry over 90% of the air. Discharge under these conditions could be practically free of material or, in the event of a plugged tube, no discharge might occur for a period of time.

Furthermore, when dealing with an actual material, it 'has been found that even if a rather ideal state of fluidization is achieved, the particles, in their slightly agitated state, may happen to group more closely than average at a particular region of the bin, and may momentarily bind. This very local condition can, depending purely upon chance, aggravate itself until considerable material has become involved so that the previously described large scale redistribution of air flow results. Conversely, the material particles at a location in the bin may, in their agitated state, so move quite by chance as to create a local diluted region through which the air flow short circuits, thereby starving adjoining regions. Once again, a condition is created which can aggravate itself. The latter two situations clearly assist one another, so that it is unimportant which one occurs first.

Another condition that may exist in practice comes about when the volume of air flow is much greater than the critical value. Here, the column boils, that is, much of the air passes up through the material as relatively large air bubbles. Because this bubbling action causes considerable agitation, and because there is a large surplus of air flow, the other aforementioned behaviors are much less likely to occur. The state of the material everywhere, except for the small amount of dust in the bubbles, is one of fluidity.

Each of the conditions mentioned, except the last, may occur at any time and reduce the performance of the packer. These conditions reduce the pressure above the pad, and therefore, reduce the effective head, the purpose of which is to provide a pressurized air-material mixture at the bottom of the column. Due to these conditions, the material feeding through the filling spout may be partially bound or overly dilute. If partially bound, the filling rate may be reduced; if overly dilute, excessive air and wild material enter the package, providing the basic factor in a dirty operation.

To insure total fluidization, it is tempting to employ the last condition, namely, bubbling or boiling due to greatly increased air flow. But this condition readily leads to excessive dilution and a dirty operation, longer filling times, high bag pressures, and a generally unstable cycle.

What is desired then, is the elimination of the firstnamed conditions without resorting to the last-named condition, such solution being applicable to all materials of the class described under a Wide range of desired conditions.

In essence then, the present invention resides in the provision of a method and apparatus that fulfills the aforementioned need; there being provided such method and apparatus which is relatively simple, and yet, is successful in eliminating the foregoing difliculties and disadvantages.

As a most important feature of the present invention, there is introduced into the column of material a secondary supply of air. This secondary supply is located above the primary pad at the bottom of the bin. As a result of this secondary air supply, excessive air flow rate can be obtained through the material in the column above the primary pad, while only critical flow rate or less than critical flow rate need be introduced through the primary pad. Excessive air above the region of the primary pad insures a fluidized state, while the critical air through the material in the bottom of the bin provides relatively compact, but fluid material in the region just before it flows through the discharge or package filling spout. In accordance with their feature of the invention, the secondary air supply will be so positioned that the material does not have time to destabilize on its way to the spout, and also that the material density can increase to the desired high value before it enters the spout.

The utilization of this secondary air supply quite naturally introduced the desirability of going to higher pressures to (1) decrease bag filling time through small filling spouts, and (2) eliminate the possibility of a condition wherein the pressure at the bottom of the bin approaches that of the bag, that is, the creation of a back pressure which would materially reduce or stop flow into the bag. But to increase the pressure with an atmospheric packer, that is, one that is open at the top, would mean increasing the height of the bin substantially where it is desired to package a dry divided solid material, this being due to the weight per unit of volume of the materialmost such material weighing between thirty-five and sixty-five pounds per cubic foot. On the other hand, if it became necessary to reduce the height of the bin, the obtainable pressure drop through the bin would be proportionally reduced for the same air flow rate. Therefore, to utilize the higher pressures, the height of the bins must be materially increased. This, of course, is not desirable since higher bins are more costly and require a greater number of secondary air supply means. Furthermore, since these atmospheric bins are loaded at the top, higher bins necessitate lifting of the material charge to a higher level and this often involves more costly equipment. There is, therefore, a need for a low head closed bin packer capable of utilizing during bag filling low to relatively high pressure ranges (2-15 p.s.i.g., for example).

Accordingly, another important feature of the present invention resides in the utilization of a bin that is of considerably lower height than known atmospheric or open type packers but that is capable of utilizing such relatively high pressure range. Packers having bins of the low enclosed type are subdivided into the batch infeed type and the continuous infeed type. The latter bin may be fed continuously through known types of continuous feeding devices, such as auger or star valve types of feeding apparatus, and, while such a packer of fluidized dry divided solid materials has proven satisfactory, nevertheless, it does present the problem of leakage of pressurizing fluid through the feeding valves. While this problem can be minimized by the introduction of sufficient secondary air to replace that which is lost in packaging as well as through the feed mechanism, the leakage becomes more of a problem as the valve wears and as higher pressures are used.

Therefore, another feature of the present invention resides in the application of secondary air to the closed bin low head batch type packers that may be opened to atmosphere between each bag filling cycle in order to take in a new charge of material, but which are closed to atmosphere during the actual filling of the bag. This type of packer packages batches of material between charges, and since continuous feeding is not required, a good, tight seal of the material charging valve may be effected between charges.

In packers of the closed bin batch type, the secondary air not only provides the energy level required to discharge fluidized material through a bag filling spout, but also replaces the air that moves out of the bin during packaging, and thus all or almost all of the air fed into the bin during bag filling in this type of packer is such secondary air. Accordingly, merely enough air flow for material fiuidizing or less (even zero flow) is fed during bag filling into the bin via said primary air source at the bottom region of the bin, and above it is fed such secondary air which thus accomplishes the aforementioned pressure change in the bin during bag filling (2-15 p.s.i.g., for example). It should be noted that the time lost during recharging of the bin is negligible since the packer is shut down while bags are changed, in any event. While this type of packer requires a slightly larger head than that of the continuous feed type, generally it is only necessary for the bin to have a capacity of 1 to 1 /2 bags of any given material.

The expression energy level as used herein refers in the atmospheric or open bin type of packer to the pressure of the air or gas surrounding a particle of material in the region inside the bin near the outlet to the filling spout. Such air or gas pressure is symbolic of a function of said energy level of the divided solid material and air or gas mixture. There is in the atmospheric type of packer, as its name suggests, substantially atmospheric pres sure at the top region of the bin. But near the bottom of the bin there is substantially higher air pressure surrounding the particles, attributable to the air fed through said pervious pad or air filter. Hence in the atmospheric type of bin there is a pressure differential between the pressure of the air surrounding a particle near the bin outlet to the spout and the pressure of the air surrounding a particle near the top or in the top region of the bin. However, in the closed pressurized or low head type of bin, when such bin is closed, the pressures of the air near the outlet and also in the top region thereof are substantially the same, and hence there is no pressure gradient between these two locations.

Another aspect of the invention contemplates the utilization in bins of the enclosed type, of a vent valve. It is often desirable to vent the bins just before the spout is closed to minimize dusting (blowback) problems. In the low head, continuous feed type packer, venting naturally takes place through the feeding mechanism, but a vent valve is desirable nevertheless to assure adequate venting. In the batch type packer, such a valve may also be used to evacuate the package through the bin just before the spout is shut, so as to minimize dusting (blowback) problems, or such a value may be used to vent the bin before opening it to its feeding apparatus so as to prevent an explosion into the feeder. Such a vent valve may also be used to lower the head towards the end of each filling cycle to obtain dribble feed into the package, thereby giving fine weight control. Another function for this vent valve is to enable bin pressure to be raised to a relatively high value before opening the discharge or filling spout and then quickly dropping the pressure to operating pressure simultaneously with opening of the spout to obtain an explosion effect in the bin, thus obtaining excellent fluidity.

Where such a vent valve is employed, means may be provided whereby venting takes place to the supply bin so that any material vented through the valve is not lost, but is ultimately fed back to the bin.

A further feature of this invention resides in the utilization of this vent valve as a cut-off device. When packaging certain materials, it has been found that by quickly venting the bin, the flow of material from the bin into a bag can be stopped or cut ofi substantially simultaneously with actuating of the vent valve. In such cases it is unnecessary to provide a filling spout cut-off mechanism or the attendant cut-oft" mechanism control equipment. Of course, the filling spourt cut-off mechanism may be retained for use during clean-out of the bin, in which case it can be manually operable.

Another feature of the present invention resides in the concept of so controlling the movement of the bag seat as to enable the same to be utilized to assure full opening of the bag. In this connection, it should be noted that one of the problems of the industry is that of incomplete opening of the bags because of the stiffness of the paper, stiff bottoms on pasted bags, and sometimes because the bottoms are pasted closed. Then, as the bag is being filled, the material being packed piles up in the bag above the portion of the inner Walls that are pasted together until a suflicient weight of material is so accumulated to break the bond. At this point, the accumulated material drops to the bottom of the bag and its impact tilts the scale beam to indicate a full bag when, in fact, the bag is only partially filled. Since the position of the scale beam is frequently used to control the operation of the packer, the bag will be improperly discharged as full. The present invention contemplates means for assuring full opening of the bag.

Still a further feature of the present invention resides in the bin design wherein the primary air pad may be disposed lower than the filling spout. The lower region of the bin may be conical, for example, with the primary pad adjacent the conical surface and the filling spout above such surface. This provides better distention of air in the lower region of the bin and facilitates the provision of a clean out opening at the bottom or apex of the conical lower bin region. The bin may be readily cleaned out and its contents conveyed to the supply bin or other desirable location by closing the spout and vent, pressurizing the bin, and opening the clean-out opening.

There has thus been outlined rather broadly the most important features of the present invention in order that a detailed description thereof that follows may be better understood and in order that the present contribution to the art may be better appreciated. There are, of course, additional features of the invention that will be described hereafter and which will form the subject of claims appended hereto. Those skilled in the art will appreciate that the conception on which the present disclosure is based may readily be utilized as the basis for designing the other structures for carrying out the several purposes of this invention. It is important, therefore, that the claims be regarded as including such equivalent constructions as do not depart from the concept and scope of this invention.

A specific embodiment of the invention has been chosen for purposes of illustration and description and is shown in the accompanying drawings, forming a part of the specification, wherein:

FIG. 1 is an elevational view, partially broken away, to reveal the interior of the bin of an atmospheric type packer in accordance with the present invention and illustrating the filling spout inserted through the valve of a FIG. 2 is an elevational view showing a low head type packer with continuous feed means;

FIG. 3 is an elevational view of a batch type packer in accordance with the invention and showing an overall arrangement of the packer and the bag weighing means as it might be used in relation to any of the various types of packers;

FIG. 4 is a schematic view of a pneumatic control circuit for the packer shown in FIG. 3 and illustrating the condition of the circuit when a cycle of operation is initiated; and

FIG. 5 is a schematic view of the circuit shown in FIG. 4 but showing the condition of the circuit when a stop signal has been initiated;

FIG. 6 is a graphical representation of bin air pressure plotted against volumetric air flow rate with respect to that embodiment of the invention having a bin open to the atmosphere;

FIGS. 7 and 8 are schematic representations in side elevation of a packer as described in connection with FIG. 6 and indicating two different conditions therein;

FIG. 9 is a graphical representation of bin air pressure plotted against time in an embodiment of the invention wherein the bin is closed to the atmosphere during the time of the filling of a container and illustrating several novel aspects of this embodiment;

FIG. 10 is also a graphical representation of bin air pressure plotted against time showing on a single graph curves typifying the operation of the embodiment which is closed and pressurized during the filling of the container and also the embodiment which is open to the atmosphere during such filling of the container.

Referring now to the drawings in detail, there .is shown in FIG. 1 a packer 10 of the atmospheric type, that is, one that is open to atmosphere at its top, comprising a bin 11 having an outlet opening 12 adjacent its bottom. The bottom of the bin may be conical in shape and may have a conduit 14 connected to its apex. A valve 15 is provided in this conduit for a purpose to be later described.

The outlet opening 12 is connected to a filling spout 16 by a flexible sleeve or pinch tube 17 which may be squeezed shut to stop the flow of material through the spout by a cut-off device 19 of known construction.

A pneumatically operable bag clamp assembly 20 of a known type is mounted above the spout to engage a bag 21 in the region of its valve and clamp the same against the spout.

It will be understood that in the various embodiments of the invention illustrated, any suitable bag clamping and spout flow control device may be utilized, as such devices per se constitute no part of the present invention.

As has been mentioned, the bottom of the bin 11 may be of conical shape. A primary air pad 22, which may be similarly shaped, is spaced slightly from the conical bottom of the bin, thus forming a subchamber 24 therebetween and the pad 22 is preferably formed of any suitable air porous material. Fluidizing air under pressure is admitted to the subchamber 24 through a pipe 25.

Near the top of the bin, 21 secondary air pipe 26 enters the bin and connects with a secondary air pad 27 which, as shown, may be in the form of a cylinder having its longitudinal axis coincident with the axis of the bin. This secondary air pad is essentially an air porous mufiier and, as shown, may be made in sections 29 that interfit, as by screw threads, so that any desired number of sections may be used. The primary and secondary air control means Will be described in connection with the embodiments of the invention to be discussed hereinafter. It is necessary at this point to understand that the air flow rates through both the primary and secondary pads can be maintained at levels suitable for the particular materials being packaged, whereby the primary pad 22 can supply the critical flow to establish incipient fluidization at the bottom of the bin, thus providing relatively oompact, flowable material in the region of the bin adjacent the filling spout, while the secondary air pad 27 can supply excessive air flow, that is, flow in excess of critical to insure a fluidized state, thus preventing the binding, plugging, bridging or channeling of the material above the secondary pad without resorting to boiling in which the material entering the filling spout will be overly dilute. It will also be understood that the secondary air pad will be located low enough so that the material does not have time to de-stabilize on its way to the filling tube, but high enough so that the material density can increase to the desired high value before it enters the filling spout.

Referring now to FIG. 2, there is shown a low head packer comprising a bin 41 that is substantially smaller in its vertical dimension, than is the bin 11 of the packer 10.

In this embodiment of the invention, the bin is shown with an inclined bottom 42, by way of example, and spaced therefrom is a primary air pad 44 providing a subchamber 45 therebetween that is fed air through a pipe 43. The bin also has an outlet opening 46 which may be connected to a spout 16 through a sleeve 17 in the same fashion as is the outlet opening 12 of the bin 11 already referred to. In this connection it will be seen that a suitable cut-off device 19 is used to control flow through the outlet opening and a bag clamp 20 is also used, as described, to clamp the bag in fill position.

This packer is provided with a top plate 45a that closes the bin to atmosphere. The plate 45a, however, has a feed opening 46a connected to an infeed conduit 47 leading from a hopper 49. This conduit 47 is provided with any suitable feed valve 56, such as the start valve shown, for effecting the continuous feed into the bin 41 of material to be packaged.

The secondary air pad is here shown as a horizontally disposed mufiler 51 to which is connected a secondary air pipe 52.

The flow rates in the primary and secondary air pads for each type of packer may, for example, be controlled by feeding the air supply through two variable orifices for each pad. Thus, as shown in FIG. 2, each of the air supply lines 43 and 52 is forked to form lines 43a, 43b and 52a, 5212, respectively. Each line 43a and 43b is supplied through a double orifice assembly 54 having chambers 55 and 56, each of which has a variable orifice 57, 59, respectively, in a portion therein. The variable orifices are set manually by control knobs 57a and 59a. A main air supply line 61b delivers air through branch lines 60a and 60b to the chambers 55 and 56, a valve 61 being provided to control the flow through one branch or the other.

The branches 52a, 52b of secondary air supply line 52 are each connected to a chamber of a double orifice assembly 62 that is similar to double orifice assembly 54, a valve 64 controlling the flow of air from supply line 60 to one chamber or the other.

Valves 61 and 64 are preferably controlled through links 61a and 64a linked to a rod 65 that is connected to a piston 66 reciprocable in an air cylinder 67, though other means may be used.

A complete description of the operation of the various embodiments of the invention will be presented later, but for the present it should be understood that the cylinder 67 will be connected in the pneumatic control system so that the valves 61 and 64 will operate at desired points in the filling cycle to control the flow of air through the air pads. In each case, the setting of the orifices will depend upon the material being packed and, as an example of the relationship of primary and secondary air flow control in a given cycle, the cylinder 67 may be connected in the pneumatic circuit to operate with the filling tube cut-01f mechanism to reduce the air to both primary and secondary pads as the machine is filling or the cut-off is open; or, it may be desired to increase flow through the secondary pad while decreasing fiow through the primary pad as flow through the filling tube is cut otf; thus maintaining a pressure level during down time and eliminating the need to build up a head after the filling spout is opened. In any event, it will be seen that the fiow rates through the pads may be readily varied at desired points in the filling cycle by diverting the air through one chamber or another of the orifice assemblies 54 and 62 by means of the valves 61 and 64, respectively. Also, for some materials, it may be desired to shut off one of the air pads at say the filling tube cut-01f point in the cycle. When packing such material, one of the orifices in the supply line to that pad is closed, and at filling tube cut-off the appropriate valve directs air to the chamber in the orifice assembly containing that closed orifice, thus cutting off the air fiow to the pad. It will be appreciated by those persons skilled in the art, that such an air supply control system provides universal control and enables the packers of the present invention to be utilized for an extremely wide range of materials not heretofore able to be packed in a satisfactory manner by a single packer.

As has already been mentioned, the invention contemplates the utilization of a vent valve in bins of the enclosed type.

Accordingly, as shown in FIG. 2, a pipe 69 containing such a valve 70 extends from the top plate 45a of the bin 41 to a suitable level in the hopper 49. The valve 70 is normally in the closed position, but may be opened, for

example, just before the spout is shut to drop the pressure in the bin to effect dribble feeding at the spout. While in continuous feed packers some venting naturally takes place through the feed mechanism, it is desirable to provide a vent valve to assure proper venting. It will be noted that any material that passes out of the bin through the vent valve is fed back to the hopper 49 so that the use of such a valve involves no waste.

Turning now to FIG. 3, there is shown a batch type packer 75, that is, a packer that is opened to atmosphere between each bag filling cycle in order to take in a new charge of material. The bin, of course, is closed to atmosphere during the actual filling operation.

The packer includes a bin 76 mounted on -a suitable frame 77 and formed with an outlet opening 79 adjacent its bottom. The outlet opening 79 leads through a flexible sleeve 17 to a filling spout 16 as in the embodiments of the invention already discussed. A filling spout cutoff device 19 is provided for shutting off the flow of material through the filling spout as each bag is filled. A bag clamp device 20 is also provided to clamp the bag to the spout during filling.

As is well known in the art, the filling spout 16 and bag clamp 20 may be mounted on a frame 80 that includes a pair of downwardly extending legs 81 (only one of which is shown). The legs 81 are supported from a scale beam 82 by knife edge fulcrums as at 84. The beam 82 has rearwardly extending members 85 (only one being shown) that are in turn supported by knife edge fulcrums as at 86 mounted on the frame 77. The rear portion of the beam supports a weight basket 87 through knife edge fulcrums as at 89. An adjustable beam stop 90 is mounted on the frame 77 to limit the beam movement.

The frame 30 also includes an inclined member 91 connected to the legs 81 at its lower end by a link 92. A plate 94 secured to the member 91 has a series of spaced recesses 95 therein. A bag seat 96 is pivotal-1y mounted as at 97 on seat support link 99 that extends rearwardly thereof and has a cross-pin 100 that may rest in the recesses 95. By this means, the seat may be adjusted to support bags of different size in proper filling relation to the fill spout.

A pneumatic ram 101 is pivoted as at 102 to the member 91 and has its piston rod pivoted to a crank arm 104 that is fixed to the bag seat pivot 97 whereby the ram may be actuated to pivot the seat 96 about the axis of pivot 97 for a purpose to be described hereinafter.

The bin 76 has been shown with a conicalbottom which may have a cleanout pipe 14 and valve 15 (not shown in FIG. 3) connected thereto at its apex, as in FIG. 1. A primary air pad 105 is spaced from the bottom of the bin and primary air is fed by pipe 106 into the spaced therebetween to pass through the pad and into the bin. A secondary air pad 107 similar to that of FIG. 1 is shown within the bin and connected to an air supply pipe 109.

It will be seen that the upper end of the bin 76 is closed by a plate 110 having a central opening by which a hopper 111 communicates with the bin through a valve 112. The valve member or gate 114 for this section is controlled by a pneumatic ram 115.

As in the low head packer of FIG. 2, the bin 76 has a vent line 116 extending between the top thereof and hopper 111, and a normally closed vent valve 117 is interposed in this line 116.

Referring now to FIG. 4, there is shown schematically a pneumatic circuit for control of the various operating elements of the packer of FIG. 3, and illustrating the condition of the circuit at the start of a filling operation, the solid lines representing pressurized lines and the broken lines representing exhausting lines. Any suitable source of compressed air supplies such air to the line 120 which conducts the air through a filter and lubricator 121 -to a manifold line 122 which in turn is connected to a line 124 that leads to an air valve 125 of the sliding spool type. One end of the valve chamber communicates through line 126 with a manual start button 127, while the other end communicates through lines 129 and 129a with a manual stop button 130 and a scale stop button 130a, respectively. Depression of the manual start button 127 exhausts one side of the chamber of valve 125 allowing the spool to shift to the left to direct air through line 131 to cylinder 19 to open the fill spout, the cylinder exhausting through line 132, the valve 125 and ex- 'haust134.

The valve 125 supplies pilot air through a t ap line 135 for the operation of other valves in the system. Thus, the line 135 supplies air to the valve 136 which, in one position, established by pressure led to the right side of its chamber through the lines 124, and 171, the reversal valve 172 and lines 174 and 175, completes communication between the line 135 through line 137 with the chamber of a valve 139 so as to move the spool therein to the right, as viewed. This valve 139 therefore establishes communication between manifold line 12.2, line 140, and lines 141 and 142 to actuate a cylinder 144 to close the vent valve 117 (FIG. 3); also from line 141 to line 145 to actuate the cylinder 67 (FIG. 2) to set the valves 54 and 62 to supply air as desired to the primary and secondary pads; also to the bag clamp cylinder 20 moving it into clamping position. It will be seen that the lefthand side of the chamber of the valve 136 exhausts through the line 173 and reversal valve 172.

The opposite sides of each of these cylinders 144, 67 and 20 are simultaneously opened to atmosphere through lines 142a, 145a and 141a, respectively, through the opposite side of valve 139. Meanwhile, the chamber of valve 139 exhausts through line 147, valve 136, lines 149, 132, valve 125 and exhaust 134.

Simultaneously, air under pressure flows from line 137 into line at the cross-connector 151, thence through flow control 152 in the restricted direction, accumulator 154, providing a predetermined delay in the air signal, and line 155, to one side of the chamber of bag discharge control valve 156 shifting the spool therein to allow air to flow from the supply line 120 through line 157 to bag discharge cylinder 101 (FIG. 3).

At the same time, air flows from the cross-connector 151 through line 159 to the chamber of the feed gate control valve 160, shifting the spool therein to allow air under pressure to flow from manifold line 122, lines 161, and 162 to the feed gate control cylinder 115 (FIG. 3) to close the feed gate 114, the cylinder 115 exhausting through line 162a and valve 160.

It will be seen that \as bag discharge control valve 156 communicates the start signal to the bag discharge cylinder, the chamber of that valve 156 exhausts through line 164, cross-connector 165, line 147, valve 136, lines 149 and 132, valve 125 and exhaust 134, while the cylinder 101 exhausts through line 157a, valve 156 and needle valve control 158 that allows fine control of the bag discharge cylinder speed. Also, as the spool in the feed gate control valve shifts to the right, as viewed, the chamber exhausts through line 166, accumulator 167, line 169, flow control in the non-restricted direction, cross-connector 165, line 147, valve 136, lines 149 and 132 valve 125 and exhaust 134.

If it is desired to operate a bank of several packers, the pressure line 174 leading out of the reversal valve 172, maybe tapped by a cross-connector 168 to feed pressurized air to the right side of the chamber of a valve 136a similar to valve 136. A similar cross-connector 168a enables air to be brought from cross-connector 168 through line 175 to line to valve 136]), these valves exhausting through lines 176 and 177, respectively, crossconnector 179, line 173 and reversal valve 172, and serving to control circuits similar to that just described, in the same manner as does the control valve 136.

To summarize the operation of the control circuit,

upon the initiation of a start signal, the filling tube cutoff device 19 moves to the open position allowing communication between the bin and the bag; the bag clamp cylinder 20 is moved to clamp the bag on the spout; the air supply is delivered to the pads and 167 at predetermined fiow rates, as described in connection with FIG. 2 for a filling condition; the vent valve 117 is closed; the feed gate 114 is closed; and then, after a delay of say two seconds, for example, determined by the accumulator 154 and the flow control 152, the bag seat 96 is retracted to the position shown in FIG. 3.

The purpose for delaying retraction of the bag seat relates to the matter of assuring full opening of each bag. The bag, when mounted on the fill spout, is not fully extended before the seat is retracted. As filling starts, a small amount of material enters the bag and, if the bag is not fully open (exemplary reasons for this having been stated), this material accumulates above the bag bottom. After a slight delay, and before an amount of material so accumulates sufficient to tilt the scale beam to cut-off position, the bag seat is quickly retracted, snapping the bag to its fully extended length and enabling the accumulated material to drop towards the bottom of the bag, thus breaking any bond of paste in its path. As mentioned, this amount of material will not be sufficient to tilt the scale beam to cut-01f position.

Referring now to FIG. 5, there is shown schematically the same pneumatic control circuit illustrated in FIG. 4, but showing the condition of the circuit elements when a stop signal is initiated. In this view, as in FIG. 4, the solid lines represent the pressurized side of the circuit and the broken lines represent the exhaust side.

The stop signal may be initiated manually by depressing the stop button 136 or automatically when the scale makes its weight by actuation of the button a by the scale beam. Upon actuation of either of these buttons, the spool of valve 125 moves to the right, as viewed, directing air under pressure from line 124, through the valve and the line 132 to one side of cut-off cylinder 1? to actuate the same to cut off the flow of material through the spout by closing the pinch tube 17 (FIG. 3). The other side of cylinder 19 exhausts through line 131 the valve 125 and exhaust 134.

At the same time, air under pressure moves through the line 141, the valve 136, line 147 and cross-connector 165 to the righthand side of the chamber of valve 139, as viewed, shifting the spool to the left, thus exhausting one side each of the cylinders 144, 67 and 20 through the lines 142, and 141, respectively, the valve 139 and the exhaust 138, thereby opening the exhaust valve 117 (FIG. 3), shifting the cylinder 67 to regulate the air supply to the air pads as desired during down time, as explained with reference to FIG. 2, and opening the bag clamp.

Pressurized air, upon reaching the cross-connector flows through lines 164 to the right side of valve 156 to shift its spool to the left, as viewed, whereby air from supply line 120 flows through the valve to line 157a and one side of the bag discharge cylinder 101 thus tilting the seat 96 (FIG. 3) to discharge the bag from the fill spout, the opposite side of this cylinder 101 exhausting through line 157, valve 156 and adjustable exhaust 158 which is set to slow the action of the cylinder 101.

Air also flows from the cross-connector 165 through line 169, flow control in the restricted direction, accumulator 167 providing a predetermined delay in the air signal, line 166 to the right side of the chamber of feed gate valve 160 thus shifting its spool to the left, as viewed, and enabling air under pressure in the manifold 122 to move through line 161, valve 160, and line 162a to the feed gate cylinder 115 shifting the feed gate 114 (FIG. 3) to the open position to allow a new charge of material to move from the hopper 111 to the bin 76, the opposite side of this cylinder 115 exhausting through the line 162 and the valve 160. As the spools in the valves 139, 156

12 and 160 shift to the left the chambers exhaust through lines 137a, 155 and 159 respectively, to the cross-connector 151 and thence through line 137, the valve 136, lines 135 and 131, valve 125 and exhaust 134.

If a bank of packers are being used, the reversal valve 172 may be conveniently actuated to shift the positions of the spools in valves 136a and 136b by directing pressurized air through the line 173 to the cross-connector 179 and thence through lines 176 and 177 to the respective chambers, the opposite sides of the chambers exhausting through lines 174 and 180, respectively, along with the exhaust of valve 136 through the line 175 and the reversal valve.

To summarize the operation of the control circuit upon the initiation of a stop signal, the bag clamp moves to release position, the filling tube cut-off device is moved to the closed position stopping movement of material into a bag; the :air supply is delivered to the pads 105 and 107 at predetermined flow rates as described in connection with FIG. 2 for a down condition; the vent valve 117 is opened; the feed gate is opened, and the bag seat is tilted in a clockwise direction, as viewed in FIG. 3, but slowly because of the controlled exhaust through exhaust 158 on valve 156, to discharge the full bag.

It is important to note that the circuit illustrated is exemplary only. Actually, any cylinder can be controlled in its speed of operation by delaying its exhaust as, for example, by the adjustable exhaust valves 158. Also, the signal to any valve can be delayed by use of a flow control and accumulator in the particular line, as in the line 154), for example. Such variations are not shown herein, because those persons skilled in the art, upon familiarizing themselves with the illustrative circuits shown would be readily able to adapt the same to provide the desired variations.

It is, therefore, within the concept of the present invention to delay the operation of the bag discharge cylinder 101 after the initiation of a stop signal so as to permit natural venting of the air in the bag through the bag itself, thereby to minimize the blowing of dust out through the bag valve when it and the filling spout are separated. This could readily 'be accomplished by inserting a flow control and accumulator in the bag discharge valve signal circuit on the stop side, for example.

It is also Within the present concept to delay the operation of the cut-off cylinder 19 in the stop side of the cycle until after the opening of the vent valve 117. This would enable the bag to vent back through the bin, thus giving a quick, clean operation. In fact, with some materials, the cut-off can be eliminated altogether, the material flow stopping immediately upon venting the bin pressure through the valve 117.

Similarly, if desired, the opening of the cut-off could be gelayed in order to pro-pressure the bin before starting to Another important part of the present contribution resides in the utilization of the vent valve to allow some venting of the bin to lower the pressure therein as the filling portion of the cycle approaches its end. Thus, the speed of flow of material will be reduced to provide a dribble feed into the bag, giving fine weight control. The vent valve may also be used to raise the pressure in the bin to a relatively high value just before starting to fill, and then quickly dropping the pressure by opening the vent valve simultaneously With the fill spout to obtain an effect similar to an explosion in the bin, thereby creating a condition of excellent fluidity in the material. The vent valve would, of course, be immediately closed again as packing begins.

It has been found that the present invention enables certain powdery compressible materials to be pro-compressed and actually extruded through the filling spout into the bag. Where it is desired to accomplish such packing the primary air may be shut off completely by closing both of the variable orifices in the primary air supply line and raising the pressure of the secondary air to start the material flowing. In this connection it is important to note that with some materials it has been found advantageous to utilize the control circuit so as to shut off the primary air during filling and to turn it on during the down time while a new bag is being applied. In this way, the down time is utilized to fluidize the material, so that when the spout is opened, the secondary air can effect flow of the material through the spout without the addition of air in the region of the spout, thus maintaining the material in the spout at a relatively high density. This technique may be used with materials which retain for a period of time a sufiicient degree of fluidity after the primary air is shut olT.

The circuit illustrated in FIGS. 4 and 5 may readily be adapted to the atmospheric packer of FIG. 1 simply by eliminating those elements that are not needed such as the feed gate 114 and the vent valve 117, and the controls necessary for their operation.

If a bank of packers are being used, the present invention contributes a method whereby they may be cleaned out most economically. The bags are filled normally until the several bins have each less than a full bag of material remaining in them. Then, instead of cleaning each bin separately, thus wasting all of the material involved, the filling spouts are closed, and the material is fluidized and moved into one of the bins, valved interconnections being provided for the purpose. This one bin is then used to fill more bags and, when less than a full bag of material remains therein, a bottom outlet, such as 14 in FIG. 1 is opened, the fill spout is closed, and the bin is pressurized, thus discharging the remaining material.

It is to be understood that the term dry divided solid materials as used herein, is not to be interpreted as excluding materials that have a moisture content, the criterion being the ability of the material to be fluidized with a gas. In fact, such products as doughnut flour, the moisture content of which may run as high as and mixed molasses feeds, for example, come within the scope of the term.

Referring now to FIG. 6, there is shown a' graphical representation of bin pressure plotted against the volurnetric flow rate of the air in cubic feet per minute injected into an atmospheric type of packer, that is, one having a bin which is open to the atmosphere and of the type as shown in FIG. 1. The graph of FIG. 6 illustrates the point that in such open or atmospheric type of packer it is possible to have a preselected succession of volumetric flow rates but normally there is but a single energy level therein. However, such single energy level may not at all times exist but may in fact vary somewhat when the air flow rate is changed.

As shown in FIG. 6, a curve 190 is employed for illustrating the change of bin air pressure with change in volumetric air flow rate of the fluidizing air in an atmospheric type of packer which in this particular instance does not have a secondary air supply, that is, an air supply for injecting air into the divided material which is located above the primary or fluidizing source of air. The curve 190 has its beginning point at 191, the pressure rising substantially linearly up to the incipient point of fluidization at 192, then following such point, in the direction of increased air flow rate, there exists a small hump 193 characteristi of such pressure vs. air flow rate curves in this type of packer. The curve 190 thereafter at 190a is substantially level which indicates the condition thatthe value of the volumetric air flow rate of the fluidizing air injected into this packer is selected to be between a value not substantially in excess of that which occurs at the incipient point of fluidization 192 and a value which occurs below such point. The packer is cont-rolled whereby it is responsive to the condition that an increase in volumetric air flow. rate of the fluidizing air beyond the aforementioned incipient point of fluidization produces insignificant change in pressure in the bin in the region of the outlet. By so adjusting and so selecting the volumetric air flow rate as aforementioned the packer is controlled so that there is neither an excessive infeed of material nor a starving infeed of such material into the bin.

FIG. 7 shows schematically a bin ofthe open or atmospheric type, the bin being designated 194 and having an outlet or container filling spout 195 which is under the control of a valve 196 schematically shown here to be shut. Fluidizing air is directed into the bin from the bottom via an air pervious pad 197 which is fed thereto via a conduit 198 having two valves 199 and 200 for controlling the air flow therethrough. By closing off either one of these two valves the air flow through the conduit 198 can be substantially diminished or by adjusting either one of these valves the flow rate through the conduit 198 can be adjusted.

FIG. 7 represents schematically the conditions in the bin when the fiilling tube or outlet 195 is closed, that is, when the valve 196 is closed.

FIG. 8, on the other hand, represents the bin 194 when the filling tube 195 has material passing therethrough by virtue of the opening condition of the valve 196. Thus when the filling tube 195 is open and the fluidized material is flowing to and through the filling spout, a different pressure condition occurs. The pressure condition of FIG. 7 is represented by the point 201 on the curve which represents the energy level of the material in the bin of FIG. 7 and this is the energy level, which it is desired to maintain in this particular packer, not only when the spout is closed, but also when it. is open.

But when the filling spout is open by the opening of the valve 196 and the condition of FIG. 8 exists, then, in order to maintain the energy level of point 201 (FIG. 6), it is necessary to diminish the supply of air into the bin, for example, by shutting off one of the valves 199 or 200 or by adjusting one of such valves. This, for example, reduces the voulmetric air flow rate from the value 202 back to a value 203, and by virtue of the falling movement of the divided particles downwardly in the bin 194 there will be maintained or approximately the aforementioned energy level at the point 201, this by virtue of the movement as schematically represented at 204, as shown in FIG. 8, which is symbolic of the activity of a particle while falling and moving toward the filling spout 195. While it is desired to maintain the energy level represented by the point 201 it is not always possible actually to stay on the target so to speak and to maintain this exact energy level. Hence when the volumetric flow rate is reduced to the value 203, the energy level may not remain precisely at the point 201 but may be slightly above or below. Hence to this extent there may be a selected succession of energy levels in this atmospheric type of packer.

However, in the closed bin type of packer, such as that shown in FIG. 3, there is in fact a preselected succession of energy levels which is symbolized by FIG. 9 representing bin air pressure plotted against time, the packer having an infeed of the batch type, that is, increments or batches of divided material are fed into the bin between each container filling cycle.

In FIG. 9 there is shown the curve 205 which starts at atmospheric pressure at point 206 and terminates at the end of the filling cycle at point 207 also at atmospheric pressure. This curve represents the changes in pressure within a bin of the type as shown in FIG. 3 during a typical filling cycle.

In the cycle represented in FIG. 9, there is employed the so-called prepressurizing technique wherein the bin is brought to a selected relatively high air pressure prior to the initiating of the filling of the container and such pressure is maintained substantially constant during the filling of such container, with the exceptions noted below.

Thus at the outset of this particular cycle, namely, at the commencing point 206, the pressure in the bin is zero (or atmospheric) and thereatfer the pressure at first rises to substantially the value indicated at 207:; which, for example, may be 2 p.s.i. and may remain at this value up to point 208 at Which time the pressure rises relatively abruptly, by virtue of the control of the volumetric air flow rate into the packer, up to the starting point 209 of the container filling cycle. At this point the bin air pressure has achieved the target value, for example, 10 p.s.i. Also, at this point when such target pressure has been reached, the operator of the apparatus will press a starting button.

However, prior to this pressure having been reached and reverting to the point 208, at, for example, 2 p.s.i. within the closed bin, there may automatically occur the following: The bin is automatically closed by suitable control means, namely, the valve (for example, the closure 11 (FIG. 3)) is closed; also the exhaust valve, for example, 117 of FIG. 3 is closed, and hence the pressure then can build up to the point 209 as aforementioned. The automatic closure of the bin by the closure of the valves 114 and 117, that is, the closure of the exhaust valve and of the top infeed valve, can be effected by means of a material level sensitive device in the bin or in response to time or alternatively in response to pressure.

After the pressure has built up to the point 209 and the operator has pressed the button to start the container filling cycle, the filling spout automatically opens by the opening of the valve of the filling spout. Thereafter the bag fills in the manner aforementioned while the curve 205 follows the substantially constant pressure region 205a which in this case remains substantially at 10 p.s.i. during the filling of the bag. When the point 210 has been reached, the bag is filled whereupon the spout is closed and the exhaust valve is opened. Alternatively, the exhaust valve may be opened in order to stop the feeding but in this particular case the filling spout is closed and the valves in the upper portion of the bin are opened thereby causing the sudden drop of the pressure to atmospheric, namely, to the point 207 comprising the righthand extremity of the curve 205.

The curve to the right of the point 207 and between the points 207 and 211 is designated by the numeral 212 and is substantially similar to curve 205 in that a point 218 is reached which is analogous to 208, and also a point 214 is reached which is analogous to 209 which signifies the starting of the container filling cycle by the opening of the filling spout. However, during the container filling cycle, that is, while a container such as a bag is being filled, and in order to render the divided material more fluid, it is possible suddenly to drop the pressure in the bin by some selected increment, for example, from 10 p.s.i. of the point 214 down to, for example, 8 p.s.i. of the portion of the curve designated by the numeral 215. Such dropping of the pressure was initiated at point 216 by, for example, an opening of a valve in the top of the bin. This opening of the valve and thus the lowering of the pressure is not enough to prevent an adequate flow rate but, as aforementioned, may be employed for artificially enhancing the fluidity of the material. Commencing at a point 217, the pres sure may be further dropped to the value 218 which is adequate for a dribble flow into the bag thereby achieving such a flow by a control of the valves of the bin and not of the spout.

Following the completion of such dribble flow, the container or bag having received the selected weight of material, the filling spout is closed and the pressure is abruptly dropped to the point 211 (atmospheric) of FIG. 9 simultaneously with the opening of, for example, the bin exhaust valve and also the top infeed valve of the bin.

Referring now to FIG. 10, there are illustrated several curves for indicating the pressurizing of the closed type of bin having the batch type of infeed, such pressurizing being accomplished by the injection of air well above the level of the outlet and by means of the socalled secondary or top air. The pressurizing of such batch infeed type of packer of the closed pressurized type is not in this form of the invention accomplished by primary air and in fact it is one of the objectives of this form of the invention to avoid the pressurizin-g of the bin by such primary or fiuidizing air which is fed into the bin via the lowermost air previous membrane. The employment of the so-called primary or fluidizing air for the pressurizing of this type of packer has not proved satisfactory because it has over-aerated the material and it has slowed down the filling time substantially.

The overaeration occurs principally in the bin and in an undesired location near the filling tube if such primary or fluidizing air is employed for the pressurizing of the bin.

It is necessary to inject into this type of bin large volumes of air to cause it to reach the desired pressure during the container filling cycle and since it has been found disadvantageous to inject these volumes of air via the lowermost air previous membrane, such press-urizing air is directed, for example, via the element 107 (FIG. 3) above the level of the membrane 105.

When such air via the secondary air injecting means 107 is employed for this purpose in the batch infeed type of packer, it is scheduled to flow into the packer, that is, it is fed into the packer at a selected volumetric flow rate as shown, for example, in FIG. 10 which is a plot of air pressure in the bin against time. FIG. 10 indicates, by way of example, a pressure of 2 p.s.i. in the bin initially up to the container filling cycle starting point 219, the latter being the righthand extremity of the initial portion 220 of this graphical representation.

At the point 219, the initiation of the container filling cycle takes place, for example, by the pressing of a starter push button on the packer, at which time air under pressure is fed in at the upper region of the bin via the upper conduit system, for example, via the conduit 109 and the upper or secondary air membrane 107 (FIG. 3). Such air can be fed into the closed bin at selected volumetric flow rate and, for example, this can be 50 c.f.m. which products the curve 221 and which has a gradual pressure gradient prior to the reaching of a selected target pressure in the bin, for example, 10 p.s.i.

Alternatively, the volumetric air flow rate can be much higher, for example, 200 c.f.m. which produces the curve 222 which is of substantially greater slope, the target pressure of 10 p.s.i. being reached early in the container filling period.

By Way of comparison, an atmospheric or open bin type of packer of this class may produce a pressure vs. time curve, as indicated at 223, which, due to a pccularity, has a slight dip or depression at 223a. Alternatively, reverting to a closed batch infeed type of packer of the type shown in FIG. 3, it is possible to inject the air into the upper region of the material via the secondary air injection means, such as 107, thereby to produce the line 224 which is at or near the initial pressure of 2 p.s.i. This may be desirable with certain types of material, for example, in tfilling an asp-halt lined bag, or any bag, with a fluid or air impervious lining and which type of bag may be used, for example, for containing a hygroscopic type of material requiring this kind of protection.

Thus in the batch infeed type of pressurized packer which is closed to the atmosphere during the container filling cycle, it is possible to select the volumetric flow rate of the air into the bin and this should be directed therein via the upper or secondary air injecting means and not via the lowermost air pervious membranes at the bottom of the bin.

Assume, for example, that a common conduit directs air to the closed type of bin of FIG. 3, this common conduit being in communication with the conduits 106 and 109. Such common conduit directs air under pressure to the bottom portion of the bin and thus also to the upper region thereof. The air flow rate to the bottom early in the filling cycle drops substantially to zero and such air follows the path of least resistance and the bulk of its volume thereupon is directed to the upper region of the bin via the secondary air injecting means 107.

Reverting to the curve 222 (FIG. 10), there is illustrated that the higher volumetric flow rate into the bin, for example, 200 c.f.m., shortens the filling time, there being indicated .a container filling cycle over the span 225 as opposed to the length of such filling time when the flow rate is 50 c.f.m. as indicated by the curve 221 and which is over a slightly longer span 226.

The curves of FIG. 10 represent what may be termed a pressure transient period which refers to the period of changing pressure in the bin during the time of the filling of the container. Such transient period, referring to the steep portion of the curve 222, would be during the time span 227, namely, from the point of the 2 p.s.i. pressure at 219 up to the point 228 Where the pressure in the bin reached its target value, for example, 10 p.s.i. and there became stabilized.

However, with respect to the other curve 221, the transient period is represented by the time span 229 which is slightly less than the span 226 and represents the length of time required from the starting of the filling cycle at point 219 up to the point where the pressure in the bin reached the target value, namely, 10 p.s.i.

Although it has been found advantageous to inject the principal pressurizing air flow into the bin via the secondary air injecting means, that is, means located as in FIG. 3 above the level of the lower membrane 105 and the tube 106, this is applicable only to the batch infeed type of packer which is closed to the atmosphere during the container filling time and is not applicable to the continuous infeed type of packer, such as that shown in FIG. 2. In fact, it is desirable to achieve the desired pressure in the type of packer of FIG. 2 via the air previous pad in the bottom of the bin although this embodiment of the invention is not limited to this characteristic. The reason for this is that it is possible to pressurize with air the continuous infeed type of bin at relatively low flow rates, the bin already having been pressurized and it is only required to add or inject into the bin a volumetric air flow rate that is being lost due to the infeed of divided material or, for example, due to a leak past the material infeed valve plus whatever volume of air is being lost during the filling.

Assume, for example, that the target value of pressure within the bin of the type of FIG. 2 is 10 p.s.i. and it is desired to maintain it continuously at this pressure despite a continuous infeed of divided material via the top of the bin. For example, there may be required a volumetric air flow rate of injection into the bin of 1 c.f.m. This preferably should be done via the air pervious pad in the bottom of the bin because it facilitates the maintenance of the fluidity of the divided solid material in the bin. While such 1 c.f.m. is desirable to be fed into the bin via its bottommost air pervious membrane, this injection of air may not be adequate to maintain the target pressure of 10 p.s.i. This may be because there is a leak past the infeed valve 50 of, for example, 5 c.f.m. which will require additional air to be fed into the bin in order to maintain the pressure. Thus, for example, an additional 4 c.f.m. may be added and this can be done via the secondary air injecting means in the upper part of the bin as by the air pervious membrane 51.

In lieu of an air leak past the infeed valve, as aforementioned, there may be an escape of air past an adjustable exhaust passage, for example, 69, and this may be in an amount, for example, of 1 c.f.m.

It is, of course, possible to have an injection of air into the bin for both fluidizing the divided material and pressurizing the bin and in the amount of l c.f.m., via the air pervious pad in the bottom of the bin to replace a loss of air of 1 c.f.m. at the top or upper region, this presupposing that there is no air leakage past the main infeed valve in which event there would be no need to add an additional volume of air via the secondary or upper air injecting means.

From the foregoing description, it will be seen that the present invention contributes a method and apparatus for packaging dry divided solid material quickly, efiiciently, with a minimum of air at the filling spout so that the material enters the bag in a dense state, with a minimum of dusting and with uniform bag weights; but most important, the present concept enables the accomplishment of such packaging for an extremely wide range of materials. For example, the batch packer of FIG. 3 has been used in tests to successfully package materials ranging from 6 pounds per cubic foot up to approximately pounds per cubic foot, and with particle sizes ranging from 400 mesh and finer up to inch pellets. Most bags can be packed with a free top as low as l to 1% inches.

Reverting to the batch feed type of packer shown in FIG. 3, a preferred method of operating the same in the filling of bags with the fiuidizable, comminuted material is as follows. Assume at the start of operations, the bin 75 is completely empty. The vent valve 117 is set at the open position to vent the bin to atmosphere, and air under fiuidizing pressure is continuously introduced through the lower air pressure line 106 and the fluidizing air pad, this pressure being such as to produce a relatively low pressure in the comminuted material of about 2 p.s.i. as represented by the line 208 in FIG. 9. The bin inlet valve 114 is now opened and a batch of the comminuted material charged from the upper storage bin 111 into the lower bin 75. Before the bin 75 is completely filled, however, the vent valve 117 is closed to prevent the comminuted material from entering and possibly plugging the vent line 116. When the bin 75 is filled to the desired extent, the inlet valve 114 is closed, and supplemental air under pressure is introduced through the upper air inlet pressure line 109 until the pressure has built up to a relatively high value of, for example, 10 p.s.i., as indicated by the point 209 of FIG. 9. At this point the filling cycle is initiated by depressing the start button to open the outlet valve 19 of spout 16 and thus fill a bag attached to the spout. When the bag is filled to the preselected weight, the valve 19 of the filling spout 16 is closed as is also the valve supplying the air to line 109, this being the valve corresponding to valve 64 of FIG. 2. The vent valve 117 is also opened to vent the bin 75 to atmospheric pressure, and the filling cycle thereafter repeated for the next bag filling as above described.

While the invention has been described in detail with respect to a preferred embodiment, it will be understood by those skilled in the art that various modifications may be made without departing from the spirit and scope of the invention and it is intended to cover all such changes and modifications in the appended claims.

We claim:

1. A method for packaging dry divided solid material comprising: introducing material to be packaged into bin means having a material discharge outlet, introducing air under pressure into said bin means in the region of said discharge outlet to fluidize the material in said bin means, opening said material discharge outlet while shutting off said fluidizing air, and admitting air under pressure into said bin means in a region above said first mentioned region in an amount greater than is required for fluidizing, the surplus air effecting compression of the material at the discharge outlet without prejudicing the flowability of said material out of said bin means through said material discharge outlet.

2. A method for evacuating a plurality of interconl9 nected bins each having dry divided solid material in an amount insufficient to constitute a package thereof and each having a package fill spout and at least one of said bins having a normally closed clean-out opening, said method comprising: fluidizing the material in some of said bins and causing it to flow into one of said bins having a clean-out opening to increase the amount of material therein, closing the interconnection between bins, discharging said material through the fill spout of said one bin into containers therefor until an amount remains in said bin insutficient to constitute a package thereof, opening said clean-out opening, and pressurizing said bin to cause said remaining material therein to flow out through said clean-out opening.

3. The method of dispensing fluidized comminuted material by means of an apparatus comprising a closed bin having an upper charging inlet and closure means therefor, and a normally closed lower dispensing outlet together with a first air injection and fluidizing means adjacent said outlet and a second air injection means disposedabove said outlet, said method comprising the steps of: charging said material through said inlet while injecting air under pressure through said first air injecting means at a volumetric rate such as to fluidize said material, opening said outlet to discharge said material, and while said outlet is open, injecting suflicient supplemental air under pressure through said second air injection means to compress said material at said dispensing outlet.

4. The method of dispensing fluidized, comminuted material by means of an apparatus comprising a closed bin having an upper charging inlet and closure means therefor, and a normally closed lower dispensing outlet, together with a first air injection and fluidizing means adjacent said outlet and a second air injection means disposed above said outlet, and means independent of said inlet and outlet for venting said bin to atmospheric pressure, said method comprising the steps of: charging said material through said inlet while injecting air under pressure through said first air injection means at a volumetric rate such as to fluidize said material, opening said outlet to discharge said material, and while said outlet is open, injecting sufficient supplemental air under pressure through said second air injection means to effect compression of the material adjacent said lower dispensing outlet, and venting said bin to atmospheric pressure after a preselected weight of said material has been dispensed.

5. The method of dispensing fluidized, comminuted material by means of an apparatus, comprising a closed bin having a normally closed upper charging inlet and a normally closed lower dispensing outlet, together with a first air injection and fluidizing means adjacent said outlet and a second air injection means disposed above said outlet, said method comprising the steps of: opening said inlet, charging a batch of said material therethrough and closing while injecting air through said first means at a rate to fluidize said material, opening said outlet to dispense said material and While so doing injecting surplus supplemental air under pressure into said bin through said second air injection means the surplus air etfecting compression of the material at the lower dispensing outlet without prejudicing the flowability of said material.

6. The method of dispensing fluidized, comminuted material into a container by means of an apparatus comprising a closed bin having a normally closed upper charging inlet, a normally closed lower dispensing spout, and normally closed bin venting means together with a primary air injection and dispersing means adjacent said outlet, and secondary air injection means disposed above said outlet, said method comprising the steps of: injecting air through said primary means at a rate to fluidize said material, opening said inlet, charging a batch of said material therethrough and closing, opening said spout with said container attached and injecting surplus air through said secondary means for discharging compressed material into said container to a preselected weight, and prior to attainment of said weight, opening said venting means 2% to atmospheric pressure to dribble-feed said material until said preselected weight is attained, and thereupon closing said spout and discontinuing said secondary air injection.

7. The method of dispensing fluidized, comminuted material into a container by means of an apparatus comprising a closed bin having a normally closed upper charging inlet, a normally closed lower dispensing spout, and normally closed bin venting means together with a primary air injection and dispersing means adjacent said outlet, and a secondary air injection means above said outlet, said method comprising the steps of: injecting air through said primary means at a rate to fluidize said material, opening said inlet, charging a batch of said material therethrough and closing, opening said spout with said container attached and injecting air through said secondary means for densifying and thence discharging said material into said container to a preselected weight, and thereupon opening said venting means to atmospheric pressure, closing said spout and discontinuing said secondary air injection.

8. The method of dispensing fluidized, comminuted material into a container by means of an apparatus comprising a closed bin having a normally closed upper charging inlet, a normally closed lower dispensing spout, and normally closed bin venting means together with a primary air injection and dispersing means adjacent said outlet, and a secondary air injection means above said outlet, said method comprising the steps of: injecting air through said primary means at a rate to fluidize said material, opening said inlet, charging a batch of said material therethrough and closing, opening said spout with said container attached and injecting suflicient air through said secondary means for compressing the material at at least in the region of the lower dispensing spout and for discharging said material into said container to a preselected weight, thereupon opening said venting means to atmospheric pressure, closing said spout and discontinuing said secondary air injection, thereupon again opening said inlet to charge a second batch of material into said bin, closing said venting means prior to completion of said charge, and closing said inlet upon completion of said charge.

9. The method of dispensing fluidized, comminuted material by means of an apparatus, comprising a bin therefor having a normally closed lower dispensing outlet and fluidizing air injection and dispersing means adjacent thereto, said method comprising the steps of: charging said material into said bin, injecting air under pressure into said fluidizing means at a volumetric flow rate sufficient to fluidize said material with said dispensing outlet closed, opening said outlet to dispense said material, and while said outlet is open, injecting air through said fluidizing means at a different volumetric flow rate such as to maintain said material fluidized while discharging the same through said outlet.

10. The method of dispensing fluidized, comminuted material by means of an apparatus comprising a bin open to atmospheric pressure and having a normally closed lower dispensing outlet, together with means for injecting air under pressure into the base of said bin, said method comprising the steps of: charging said bin with said material with said outlet closed and injecting air into said material at a pressure suflicient to fluidize said material but insufficient to produce boiling thereof, opening said outlet to discharge said material and while said outlet is open, reducing said air pressure to a value such as to maintain substantially the same state of fluidization of said material as obtained at the higher pressure aforesaid with said outlet closed.

11. The method of dispensing fluidizable, comminuted material into a container by means of an apparatus comprising a closed bin having a normally closed upper charging inlet, a normally closed lower dispensing outlet, and

normally closed bin venting means, together with means for in ecting and dlspersing fluidizing air under pressure into said bin, which comprises: opening said inlet and charging a batch of said material into said bin while inectlng arr therein at a rate to establish a relatively low air pressure in said material, closing said inlet and increasing the air pressure Within said bin to a relatively high pressure, opening said outlet to discharge a batch of said material into said container while maintaining said relatively high air pressure within said bin, closing said outlet when said container is filled to a preselected extent and venting said bin substantially to atmospheric pressure while reducing the rate of air injection into said bin.

12. The method of dispensing fluidized, comminuted material into a container by means of an apparatus comprising a closed bin having a normally closed upper charging inlet, a normally closed lower dispensing spout, and normally closed bin venting means together with a primary air injection and dispersing means adjacent said outlet, and a secondary air injection means above said outlet, said method comprising the steps of: injecting air through said primary means at a relatively low rate to fluidize said material, opening said inlet, charging a batch of said material therethrough and closing, opening said spout with said container attached and injected air through said secondary mean-s to pressurize said bin to a relatively high value for discharging said material into said container to a preselected weight, and thereupon opening said venting means to atmospheric pressure, closing said spout and discontinuing said secondary air injection.

13. The method of dispensing fluidized, comminuted material into a container by means of an apparatus comprising a closed bin having a normally closed upper charging inlet, a normally closed lower dispensing spout, and closeable bin venting means, together with a primary air injection and dispersing means adjacent said outlet, and a secondary air injection means above said outlet, said method comprising the steps of: injecting air through said primary means at a rate to fluidize said material, opening said inlet with said bin venting means open and charging a batch of said material into said bin, closing said bin venting means before said bin is filled and thereupon closing said inlet, thereupon opening said spout with said container attached and injecting air through said secondary means to pressurize said bin to a relatively high pressure for rapidly discharging said material into said container to a preselected weight, thereupon opening said venting means to atmospheric pressure, closing said spout and discontinuing said secondary air injection, and repeating said method for the filling of additional containers.

14. The method of dispensing fluidized, comminuted material into a container by means of an apparatus comprising a closed bin having a normally closed upper charging inlet, a normally closed lower dispensing spout, and normally closed bin venting means together with a primary air injection and dispersing means adjacent said outlet, and secondary air injection means disposed above said outlet, said method comprising the steps of: injecting air through said primary means at a rate to .fluidize said material, opening said inlet, charging a batch of said material therethrough and closing, opening said spout with said container attached and injecting air through said secondary means at a rate to establish a relatively high pressure in said bin for rapidly discharging said material into said container to a preselected weight, and prior to attainment of said weight reducing the pressure in said bin to a value such as to dribble-feed said material until said preselected weight is attained, and thereupon opening said venting means, closing said spout, and discontinuing said secondary air injection.

References Cited by the Examiner UNITED STATES PATENTS 1,979,492 11/1934 Russell 14168X 2,221,741 11/ 1940 Vogel-Jorgensen 302-53 2,681,748 6/ 1954 Weller 222-195 2,792,262 5/ 1957 Hathorn.

2,887,292 5/1959 Titc-henal 222-495 X 2,905,362 9/1959 Aust 222-195 X 2,922,611 1/1960 Aust 177--1 2,936,994 5/ 1960 Lau 141-68 X 3,073,401 1/1963 Zenke 177-63 FOREIGN PATENTS 1,096,189 1 2/1954 France.

LAVERNE D. GEIGER, Primary Examiner. LOUIS J. DEMBO, Examiner.

N. STACK, E. EARLS, Assistant Examiners.

Claims (1)

1. A METHOD FOR PACKAGING DRY DIVIDED SOLID MATERIAL COMPRISING: INTRODUCING MATERIAL TO BE PACKAGED INTO BIN MEANS HAVING A MATERIAL DISCHARGE OUTLET, INTRODUCING AIR UNDER PRESSURE INTO SAID BIN MEANS IN THE REGION OF SAID DISCHARGE OUTLET TO FLUIDIZE THE MATERIAL IN SAID BIN MEANS, OPENING SAID MATERIAL DISCHARGE OUTLET WHILE SHUTTING OFF SAID FLUIDIZING AIR, AND ADMITTING AIR UNDER PRESSURE INTO SAID BIN MEANS IN A REGION ABOVE SAID FIRST MENTIONED REGION IN AN AMOUNT GREATER THAN IS REQUIRED FOR FLUIDIZING,

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