WO1989007562A1

WO1989007562A1 - Handling bulk viscous liquids

Info

Publication number: WO1989007562A1
Application number: PCT/AU1989/000060
Authority: WO
Inventors: John Edmund Althaus
Original assignee: Vismatec Pty Ltd
Priority date: 1988-02-15
Filing date: 1989-02-15
Publication date: 1989-08-24
Also published as: KR900700365A

Abstract

A bulk container (10) for viscous liquids fitted with a plurality of microwave injection ports (18, 59, 112-117, 125) by which miccrowaves may effect heating of the contents for discharge from a lower outlet (17, 58, 126), the microwave injection ports (18, 59, 112-117, 125) being sealed against liquid outflow therethrough by a transmissive cap (33, 50, 108).

Description

TITLE: "HANDLING BULK VISCOUS LIQUIDS"

FIELD OF INVENTION This invention relates to bulk material handling and in particular to the discharging of viscous contents from large containers.

BACKGROUND

Industry utilises many raw materials that are viscous at normal temperatures such as tallow, bitumen, etc. These materials are heated to liquify them and enable their being poured into large storage containers for transport. At a receiving point, the container is heated to enable removal of its contents. Heating is typically by use of steam piped through coils built into the tank. Such tanks are standardised for shipment using standard container transport techniques. The containers are expensive, and their complexity is such that they are not readily cleaned and have a short life span.

OBJECTS It is an object of the present invention to provide improvements in the handling of bulk quantities of viscous materials of many types using the principles now established in respect of drums and the like as set out in prior patent specification No. PCT/AU86/00391. NATURE OF INVENTION

Other objects and various advantages of the invention will hereinafter become apparent.

The invention provides a bulk storage container comprising: a storage body; at least one microwave inlet thereto, and at least one liquid outlet; the microwave inlet being provided with a liquid occlusion means thereover that is transmissive of microwaves but prevents outflow of the container's contents. The container may be externally standard so far as construction and dimensions are concerned, the storage body being typically a steel cylindrical body supported in a rectangular cradle having the usual international container handling connection points therein. The interior of the container does not require any of the steam pipes of earlier containers and it is consequently more easily made and cleaned.

The invention further provides a means of handling bulk storage containers comprising: a support means; a container receiving frame hingedly connected to the support means whereat a container may be received and releasably held; and a displacement means whereby the container receiving frame may be tilted about its hinged point to tilt a container supported thereon; tilting being such that, in use, a container may be tilted to elevate its contents above an outlet thereto such that the contents flow therefrom may be controlled by selection of the angle of tilt.

In operation of the means of handling bulk storage containers, a container may be affixed to the container receiving frame making use of the internationally standard container connection points referred to above. Connection of the microwave sources required for heating may be provided via flexible tubing for piping the microwaves as is described in the prior patent specification and is more fully set out below, so that the container may remain coupled to a source of microwaves whilst the container is being tilted.

The invention still further provides a microwave station comprising: a movable platform; support racks mounted on the platform; and a plurality of microwave units each movably mounted in a support rack therefor; the microwave units being individually movable to and from a work face at an end of the platform which may be moved up to a container when one or more of the microwave units may be selectively coupled to a container so as to heat its contents.

The microwave station may be provided with microwave units feeding microwaves into flexible waveguides whose ends may be coupled up to coupling points on the container. A central processor may be employed to selectively fire the magnetrons of respective microwave units as required and optimise their operation having regard to the amount of material to be poured and its temperature.

DESCRIPTION OF DRAWINGS The invention will now be described with reference to various preferred embodiments as shown in the accompanying drawings wherein: FIG. 1 is a perspective view of a bulk storage container in accordance with the present invention;

FIG. 2 is a detailed sectional view of a container cap that might be used on the bulk storage container of FIG. 1, FIG. 3 is a detailed sectional view of a microwave inlet port which might be used in the bulk storage container of FIG. 1;

FIGS. 4 to 6 show detailed sectional views of other microwave inlet ports in accordance with the present invention;

FIGS. 7 and 8 show an arrangement of microwave injection ports at an end of the container;

FIGS. 9, 10 and 11 show various ways in which the bulk container may be modified for an optimum discharge; FIGS. 12 and 13 show alternate ways in which a bulk storage container as in FIG. 1 may be handled during discharge;

FIGS. 16 and 16 show details of a microwave generator set;

FIG. 17 shows a block diagram of how a microwave generator may be operated;

FIG. 18 is a particular circuit that performs the functions of FIG. 13; FIG. 19 illustrates a wave guide assembly; and

FIGS. 20 and 21 show a microwave phase changer.

PREFERRED EMBODIMENTS BULK STORAGE CONTAINER In FIG. 1 is seen a schematic view of a bulk storage container comprising a hollow storage body 10 (typically a cylindrical plate steel construction with domed end walls) supported in a frame 11 (preferably having standard container traffic dimensions) with preferably standard corner pieces such as 12 that are holed to enable handling and securing of loads. The storage body 10 may be rested in frame 11 on bottom bearers 13 and 14 (these may also be steel to be welded within a steel frame 11). Each upright of frame 11 may be fixed by brackets to the storage body 10 to restrain its movement (such as brackets 15 and 16 which can be steel and welded into place). An outlet 17 of standard type may be provided so as to enable discharge of contents. At least one port 18 is provided to enable the storage body 10 to be coupled to a source of microwaves (a typical structure for these ports is described below). In some situations, where a plurality of microwave sources are utilised to inject energy into the storage body 10 through ports 18, coupling may occur with more regular arrays of ports to make it desirable to randomise their positions such that internal reflections will not result in coupling of any two magnetrons used as sources of energy.

So as to be filled, the storage body 10 may be provided with the usual plate type lid coupled to a port 20 over flanges 22 to which the lid may be screwed, bolted, clamped etc. The usual metal to metal configuration involves such tight tolerances that microwave leakage (at the usual longer frequencies) would not be likely. In the event that some arrangement is required to prevent it, a further flange 23 may be fixed around port 22 to cover over opening 21 with lid 24 wherein downwardly projected flange 25 is spaced from flange 23 by a small amount to create a choke of sufficient depth such that at the lip 27 what energy may exist at the lip is below acceptable limits so that if the seal at the lip be insufficient no significant leakage will exist anyway.

FIG. 3 is an axial transverse section through a port such as may be used at 18 in FIG. 1. This is shown exploded so as to more clearly show the respective elements. Container wall 28 is holed at 29 (circularly in this case) and an element 30 is inserted therein such that flange 42 abuts wall 28 (the two may be bolted, or otherwise connected together - element 30 may be welded to wall 28). Element 30 may provide a thread 31 internally of the container to receive a locking piece 34 with mating thread 35 to clamp wall 28 between it and flange 42 (these features might be omitted in a welded structure). So that port 29 may pass microwaves and yet prevent efflux of materials into a waveguide attached thereto a cap 33 can be provided (of teflon, ceramic, or other microwave transparent material). Cap 33 may be retained by locking piece 34 with flange 43 on cap 33 caught behind abutment 44 of locking piece 34. By this means port 29 can be coupled to a microwave source in the following manner. In FIG. 3, a waveguide 36 is shown extended into port 29 with rim 38 thereabout that is locked in use against abutment 39 by locking screw 41 whose thread 40 engages with thread 45. If leakage of microwaves be thought to be a problem a gap 37 may be provided between waveguide 36 and extension 32 of element 30 to create a microwave choke of sufficient length that energy levels at locking screw 41 are acceptably low should leakage otherwise be likely. The above described part is round but it will be clear to a man skilled in the art that the alternate standard rectangular forms may be adopted when rectangular waveguides are being used.

The cap 33 of the port of FIG. 3 is mounted internally of the hollow storage body to complicate its construction. The embodiment below enables a cap to be fitted from the outside.

In FIG. 4 (in axial transverse section) a waveguide 46 is locked by screw-in ring 47 such that waveguide rim 49 is locked into element 48. Between element 48 and waveguide 46 is locked a transparent or transmissive cap 50 which can be inserted into element 48 prior to insertion of the waveguide. Thus cap 50 may be put in place from outside the bulk container. A gap which acts as a choke results from this disposition of ports with the above noted effects in sealing the port.

FIG. 5 shows waveguide 56 separately locked in elements 55 by ring 54 with clamping rim 53 therebetween and ring 52 locking cap 51. In FIG. 6, microwave waveguide 101 protrudes through a port with locking rim 102 caught in port body 103 as follows. Port body 103 has insert 105 threadably engaged therein with locking ring 104 holding locking rim 102 against insert 104 so as to clamp the waveguide within the disconnectably coupled port. Insert 105 is screwed against an end flange of a microwave transparent cap 108 to clamp it against an end stop 106 at the inner end of the port body 103. An O-ring type seal 107 may be provided between end stop 106 and insert 105 to prevent liquid from seeping therepast. A metallic sleeve 109 may be provided to support the cap 108. This sleeve is mated with insert 105 as shown and a gap may exist between the sleeve 109 and the waveguide to establish a choke as described above. This preferred design for a port enables access to all its elements for cleaning, replacement, etc from outside the container body.

FIG. 7 shows a typical pattern of ports on the domed end 110 of a container in handling frame 111. The ports 112 to 115 may be oriented with their axes parallel, co-axial with the axis of the cylindrical container 110, that is orthogonal to the plane of FIG. 7. The axes 118 and 119 of ports 116 and 117 (see FIG. 8) may be angled inwardly each at an angle such as 7.5° to the axis of the container, being both offset in the horizontal plane only.

A similar pattern of ports may be provided at the other end of the container. In most circumstances, heating from one end of a bulk container will be adequate. However, heating from both ends and/or the sides is possible.

In the above described bulk container, if viscous liquid is to flow therefrom, consideration needs to be given to how air or other gas is to be allowed into the growing cavity if the effect of atmospheric pressure is to be allowed for. Below is set out various ways in which this might be allowed for.

FIG. 9 is an end view of a container 57 with outlet 58 and microwave inlet ports 59. Around the inlet ports 59 is trailed two heating lines 60 and 61. In use, these cause a heating of the viscous material along a line up the end wall to a conveniently placed inlet by which air or other gas may be permitted to enter and flow down the passage created to the cavity growing around the inlet port (or ports) that are being operated. When small quantities are to be discharged, only the lower ports might be used and use of the heating lines will connect their cavity to an inlet.

The heating lines 60 and 61 might be electical or by piped hot water. They may be placed either internally or externally (although external application is simplest and the then free inner surfaces are easier to clean). Hot water might be piped, through copper tubing adhered in heat conductive relationship with the steel plate of the container to heat the container wall and subsequently the stored material adjacent thereto. In the bulk container of FIG. 9 (and the other variations described herein) outlet 58 may be provided with a microwave choke of suitable character (as will be clear to a man skilled in the art). The ports 59 may be circular or rectangular . depending on the waveguide geometry and size will be dependent upon wavelength with sizes between 70mm and 250mm being typical.

FIG. 10 shows an alternate heating line layout with lines 62 and 63 wound around ports 59 in a pattern that extends the heated zone to the top of the container. A central port 64 might be used with a more powerful microwave generator (typically 915 megawatts with dimensions 292 × 146mm).

FIG. 11 shows the pattern of heating line 65 used with a single port 66 which may have a choke built in in the above manner with typical port sizes being 292 × 146mm or 86 × 44mm.

As an alternate arrangement to the above heating lines it might be possible to insert a length of microwave transmissive material up the inner wall of the bulk container over the ports to conduct some portion of the microwave power passed through the port therealong to heat the adjacent viscous material to achieve the function required of the above described heating line. In this regard, a length of extruded material such as teflon may be used. However, this complicates the internal structure of the container which is best left clear to enable cleaning etc.

So as to avoid possible problems associated with flammable vapours filling the cavity to raise a risk of combustion, instead of air being bled into the container, nitrogen or carbon dioxide can be used. The cavity might be pressurised to assist in exhaust of the contents. APPARATUS FOR HANDLING BULK CONTAINERS

FIGS. 12 and 13 show two ways in which the above described bulk containers may be handled at a discharge point.

In FIG. 12, a bulk container of viscous fluid is lowered onto a tilting support frame 68 which is free to pivot on a horizontal transverse axis through pivot 69. The bulk container may be fixed to support frame 68 to maintain its position during tilting. The rear end of the frame 68 is supported on means 71 whereby a horizontal rest position is established. A ram 72 may be used to raise the container about pivot 69 such that the container's contents are above the outlet ( at the pivot end) such that gravity assists the flow of heat treated liquid. This approach reduces the time that the liquid material remains in the microwave field. A microwave station 73 is linearly movable on rail 74 which is an extension of frame 68 between a retracted position when the bulk container may be unloaded and a new one loaded and a working, position adjacent the container end (as shown) when microwave units (to be described below) therein may be coupled (typically with flexible wave guides of the type described in the above- mentioned earlier application to the ports at the end of the container.

In FIG. 13 bulk container 75 is loaded on a frame which is tilted about pivot 76 by ram 77 in the above described manner. A microwave station 78 is wheeled up to the container end and raised on extensible support 79 such as the scissor lifter shown on wheels 80. Connectors at each side (81 and 83 are in view) are engaged with the corner connectors of the bulk container frame so that the weight of microwave station 78 is supported off the end of the bulk container. Wheels 80 might be drawn up beneath station 78. Connector 83 is used to engage corner connector 76 to hold the base in place when the two units are tilted together. In FIG. 13 tank 120 is mounted in a support frame 121 and the tank is provided with a hatch 22, a relief valve 123 and a compressed air inlet 124. Microwave ports 125 are provided at the end face to connect with microwave generators in microwave station 78. A liquid outlet 126 may flow the tank's liquified contents into a heat exchanger 127 from which it may be pumped from outlet 128. The contents of the tank 120 may be monitored by load cells 130 so that the discharge can be controlled. FIG. 14 is a flow sheet indicating various aspects of control. Tank 130 is shown coupled at each end in the manner set out above to microwave generators 131 and 132. The microwave generators are controlled by signals output from interface 133 which relays commands of a micro-processor 134 under control of computer 135. The microprocessor takes account of various inputs from interface 136 that receives signals from various sensors and operative units as set out below regarding the status of various elements of the system. In FIG. 14 an hydraulic tilt unit 137 controls tilt ram 138 to assist flow from the tank by draining liquified contents to the outlet at 139 which may be valved at 140. A pump 150 may assist the flow and a heat exchanger 151 may be used to further control the temperature of the discharge. A primary heating temperature probe 152 measures the degree of microwave heating and the secondary heating temperature probe 153 can be used to monitor the operation of heat exchanger 151. A load sensor weighometer 154 monitors the discharge enabling cut off as required. Operation of pump 150 may be via pump controller 155 receiving instructions from the micro-processor through interface 133.

Utilising the above described system, a viscous material may be caused to flow from a tank with outflow affected by parmeters such as starting temperature, microwave field strength, tilt of the container, assistance to flow at the outlet by a pump in the outlet line and/or injection of compressed gas to the container, etc with the nature of an optimum regime being dependent upon the type of material being handled. A gas is admitted to the container to fill the growing cavity. A temperature boost may be desirable beyond what might optimally be provided by microwaves and the heat exchanger can then be brought into operation. Some materials may be degraded if left too long in an energetic field with a view to establishing a desired temperature through use of microwaves alone such that the heat exchanger becomes a useful addition to the system. Tilting of the container can be used to increase flow rates to reduce the temperature that the liquid would achieve if it remained longer in the microwave field. Tilting can be used to give some control over the discharge temperature as an alternate method to switching off the power to various ones of a plurality of generators. MICROWAVE STATION

In FIG. 15, a microwave generator 94 is mounted on rails 95 and 96 for to and fro movement on wheels such as 97. Generator 94 can contain one or two magnetrons to inject power into waveguide 98 together with various of its electrical supply and cooling accessories. The object of the movable mounting is to enable the waveguide end 99 to be moved up to a container port for coupling thereto. A plurality of these generators may be arrayed in a two dimensional layout for movement perpendicularly of the plane of the array with the array mounted in a framework on a movable platform. The platform can be wheeled up to the end of a bulk container when, one by one, the ends 99 may be inserted into ports, as required, and coupled up to the container. The coupling of end 99 requires some to and fro movement as a fair length of waveguide is threaded through the port, particularly when a choke arrangement (as described above) is in use. Some generators in the array may feed sideways of their direction of motion as in FIG. 16 wherein waveguide 100 converts a sideways feed to a direction parallel but offset with regard to rails 101 and 102. By this means, an array of generators may feed to two closely spaced ports. The waveguide 98 includes a transition 103 from rectangular to circular geometry and a section 104 which is flexible. The flexible section may be formed from helically wound steel flexible tube as is used in truck exhaust systems. The flexible character enables the waveguide end to be lined up with a port irrespective of any variations in position amongst containers from different sources. MICROWAVE POWER SOURCE

In the above described apparatus, the source of microwaves can be one or more magnetrons. Magnetrons are usually operated as half wave devices and their output is polarised. The below described technique enables up to four times the power that is delivered by the standard arrangement of a single magnetron coupled to a waveguide to be injected into the guide and thereby into the container through the one port.

In FIG. 17 magnetron 84 is coupled to a pair of matching transformers 85 and 86 via rectifiers 87 and 88 and capacitors 89 and 90. The use of this circuit and matched transformers enables full wave operation to double the magnetron's output into wave guide 91 via probe 92. Because the input power is polarised, a second magnetron 93 can be utilised with its plane of polarisation orthogonal to that of 84 such that the two will not become coupled. This way, upto four times the usual power is injected into the waveguide. This sort of adaptation can be useful in discharging large tanks where the surface area of a growing cavity can be large so that more power needs to be injected to keep up the power levels per unit area for optimal heating of the viscous contents.

FIG. 18 shows a circuit that performs the above function with power fed via secondary windings 105 to a magnetron 106. The two half cycles on the primary are utilised in the identical circuits with rectifiers 107 and 108 and capacitors 109 and 110.

FIG. 19 shows a waveguide assembly wherein a section 156 is coupled to end 157 via a flexible section 158. Section 156 is coupled to a source of microwaves via a bolted flange 159 or other suitable connector. End 157 has a rim 159 and a loose locking ring 160 as described above for enabling end 157 to be screw clamped into a microwave port of a container to be emptied. As microwave port structures are most readily manufactured in circular format, end 157 comprises preferably a circular section of waveguide although clearly a square sectioned waveguide could be utilised. Flexible section 158 is a helically wound structure with overlapped turns having a degree of axial slippage and clearly a circular waveguide structure is most readily adopted at this point. In practice microwave generation involves injection into rectangular or square sectioned waveguides and 156 may be a transition from rectangular to circular waveguide shape to accommodate the different geometries most usefully adopted at each end of the tank coupling waveguide. FIGS. 20 and 21 show side and end views of phase changer that may be added at the inlet end of transistion section 156 downstream of the microwave source bolted to flange 159. Phase changing is effected by a rotating plate, typically formed from teflon or another suitable material able to transmit microwaves. Rotation brings the plate alternately into and out of play with a phase change effected when it is across the field due to a delay in transmission introduced by the plate dependent upon the thickness of the plate. Plate 161 is supported at the bottom in a bearing assembly 162 and at the top in journal 163. Plate 161 mates at the top with a drive shaft connected at 164 to the output of motor 165 which spins the plate a selected speed. Changing the phase of the microwaves that are injected into a tank helps to overcome any tendency to form standing waves which, if developed, heat at points between nodes where no heating occurs.

Claims

1. A bulk storage container comprising: a storage body; at least one microwave inlet thereto; and at least one liquid outlet; the microwave inlet being provided with a liquid occlusion means thereover that is transmissive of microwaves but prevents outflow of the container's contents.

2. A bulk storage container as claimed in claim 1 wherein the occlusion means is fitted within the port by a locking ring such that it is removable from outside the storage body.

3. A bulk storage container as claimed in claim 2 wherein the port incorporates a choke limiting egress of microwaves.

4. A bulk storage container as claimed in claim 3 wherein the choke comprises a support sleeve supporting an axial extension of the occlusion means.

5. A bulk storage container as claimed in any one of claims 1 to 4 wherein the storage body is provided with a plurality of ports in a pattern that obviates coupling of microwave generators.

6. A bulk storage container as claimed in claim 5 wherein a means is provided to liquify material in the storage body up to a gas inlet.

7. A bulk storage container as claimed in claim 6 wherein the storage body is generally cylindrical, the ports are at an end thereof with their axes substantially parallel to that of the cylinder.

8. A bulk storage container as claimed in claim 7 wherein a pair of ports are angled inwardly such that their axes intersect that of the storage body.

9. A means of handling bulk storage containers as claimed in claim 1 comprising: a support means; a container receiving frame hingedly connected to the support means whereat a container may be received and releasably held; and a displacement means whereby the container receiving frame may be tilted about its hinge point to tilt a container supported thereon; tilting being such that, in use, a container may be tilted to elevate its contents above an outlet thereto such that the contents flow therefrom may be controlled by selection of the angle of tilt.

10. A means as claimed in claim 9 wherein the support means is provided with load sensors to monitor the discharge and the angle of tilt and microwave power are adjusted by a control means governing the discharge.

11. A means as claimed in claim 10 wherein the discharged material is passed to a heat exchanger for further heating prior to use.

12. A microwave station in a means of handling bulk storage containers as claimed in claim 9 comprising: a movable platform; support racks mounted on the platform; and a plurality of microwave units each movably mounted in a support rack therefor; the microwave units being individually movable to and from a work face at an end of the platform which may be moved up to a container when one or more of the microwave units may be selectively coupled to a container so as to heat its contents.

13. A microwave station as claimed in claim 12 wherein the movable platform is provided on a lifting means that elevates it for mating with the end of a storage body to be discharged, the movable platform being releasably locked thereto.

14. A microwave station as claimed in claim 13 wherein the microwave units are coupled to a microwave inlet port in the storage body by a flexible waveguide assembly.

15. A microwave station as claimed in claim 14 wherein a phase changer is incorporated in the flexible waveguide assembly. A microwave station as claimed in claimwherein the phase changer is a motor driven rotated transparent or translucent plate inserted into the waveguide.