WO1997033469A1

WO1997033469A1 - Rotary and tunnel-type kilns with multi-ducted radiant heating

Info

Publication number: WO1997033469A1
Application number: PCT/AU1997/000132
Authority: WO
Inventors: Ian Jeffrey Bersten; Dirk Domenico Cortesi
Original assignee: Roasting Technologies Pty. Ltd.
Priority date: 1996-03-11
Filing date: 1997-03-06
Publication date: 1997-09-18
Also published as: AU1862897A

Abstract

The use of infrared and gas burner radiant emitters in tunnel-ty pe, rotary and inclined kilns, together with supporting jackets is well established. There is a need, however, for more comprehensive geometry in this apparatus in order to provide in the one jacket (20), duct spaces (24, 28, 30, 32) for electric leads and/or gas supply, oxygen/air for the gas supply, coolant(s), additive(s), withdrawal of by-product(s) including fumes and wiring for monitoring and process control. The emitters (44) are formed by longitudinal extrusion and the ducts therein are formed in the same way and extend fully therethrough. A generally concave, preferably parabolic, recess (38) is provided along the length of the emitter to house the radiation source, with a reflecting surface (40) to direct the heat energy away from the jacket. A cover (42) made of quartz glass is mounted over the recess (38) to define an enclosed chamber. The integrated apparatus is used to treat nuts, peas and beans, such as soya, faba, cocoa, coffee, fruit and vegetables, starches, grains and cereals by such processes as roasting, blanching, instantising (pre-cooking), cooking, preservation, gelatinisation, sterilisation, drying, disinfestation, devitalisation and expansion.

Description

ROTARYANDTUNNEL-TYPEKILNSWITHMULTI-DUCTEDRADIANTHEATING

Field of the Invention The present invention relates to tunnel-type kiln apparatus and components for use with the same. The invention also extends to energy and process control in such apparatus. Apparatus according to the invention can find broad application in the food treatment industry, including roasting, drying, sterilisation, cooking, de- activation and disinfestation of foodstuffs and also has application in sewerage, mining, waste treatment, chemical processing and sterilisation industries.

When the term "kiln" is used throughout the present specification it is not intended to be limited to a furnace or oven for burning, baking or drying etc., but rather includes any tunnel-device wherein heating and/or radiation may take place to achieve a physical and/or chemical change in the product passing through the device .

Background Art The employment of infra-red radiation and gas burner heat emitters with tunnel-type kilns, more particularly rotating and inclined kilns for roasting, drying, cooking etc. is known. The use of supporting jackets with infra¬ red emitters and gas burners is also known. These jackets sometimes include a passage for the through-flow of coolant. However, there is a need for different geometries in such apparatus than currently provided, so that more flexible kilns can be offered and also so that product idiosyncrasies in particular with drying, roasting, cooking, sterilisation procedures etc. can be accommodated.

Summary of the Invention The present invention in a first aspect provides a mul i- ducted jacket for supporting an emitter in a tunnel-type kiln, the jacket including: at least one duct for delivering electricity or fuel to the emitter; and at least one free duct for the delivery or removal of a commodity other than a primary coolant to/from the jacket, the emitter or the kiln.

By a "primary coolant" it is meant a coolant that in use is primarily used for cooling the jacket from heat generated by the emitter.

The provision of such a jacket, whether it be used for supporting a gas or electric infra-red-type emitters, enables various control parameters to be introduced. The free duct(s) can also be used to supply an additional coolant to regions within the jacket (ie. in addition to a primary coolant duct) , although more preferably can be used to introduce new material, to withdraw by-products from a process, to provide further and/or alternative power supply etc.

In a practical sense, for example, in some roasting processes, smoke is produced in a latter stage of the roasting process (ie. late in its passing through the kiln) . This smoke can be withdrawn at its point of production through one of the free ducts (or through a separate exhaust system) . Alternatively, some processes require the spraying or addition of a chemical (eg. water, oil, flavours, etc.) at a certain point in a cooking, roasting, drying or sterilisation cycle and again, one of the free ducts can be employed to introduce such a substance or commodity at a precise location.

In addition, such a duct can be used to mount a number of emitters sequentially through a kiln. Independently controllable zones through the process can then be achieved by establishing various flow regimes through the ducting of the jacket and thereby varying the particular conditions at each emitter. In this regard, in a second aspect the second invention provides a tunnel-type kiln including two or more zones, each zone being controllable independently of each other zone with respect to a product when fed through the kiln.

Such a kiln can be employed where different chemical and mechanical characteristics are observed for a product passing through a kiln at different stages, temperatures, humidities, moisture contents etc. By providing distinct and independently controllable zones through the kiln, the addition of separate commodities, the withdrawal of by-products, or the maintenance of through-flowing product under certain conditions for certain periods of time can be achieved so that an end product having predetermined and desired characteristics can be produced.

Such independent control can be achieved through the variation of constructional parameters within the kiln, for example by employing transverse baffle plates, separate tunnel segments, internal helical screw combinations, baffles and scrapers etc. or through the variation of process operating parameters such as control of emitters in different parts of the kiln, addition and subtraction of products, varying flow characteristics etc.

Following from this, in a third and further aspect, the present invention provides a tunnel-type kiln adapted for having a product flow therethrough in a first direction, with helical screw means positioned in the kiln and adapted in use for engaging and moving at least part of the product in a direction counter to the first direction.

The employment of various helical screw configurations can counteract the through-flow of products and can increase product in kiln-retention time, control of product exposure to radiation and heat etc.

The helical screw means may be in the form of a peri-helical screw arranged on the interior of the kiln or in the form of one or more individual helical screws extending through the kiln and operable to achieve various through-flow and product level configurations.

In a fourth aspect the present invention also provides a method of treating granular product comprising the steps of :

(a) agitating the product in a manner in which the grains are positioned in a plurality of orientations; and

(b) subjecting the grains to infra-red radiation in a number of those orientations.

Such a method can be used in all the applications highlighted in this specification and finds particular application with granular foodstuffs. In addition, such a method is particularly facilitated by at least preferred combinations of apparatus as defined in the first, second and third aspects throughout this specification.

Brief Description of the Drawings

Notwithstanding any other forms which may fall within the scope of the present invention, preferred forms of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:

Figure 1 shows an end view of a preferred ulti- ducted jacket according to the invention;

Figure 2 shows an underside view of the jacket of Figure 1 with infra-red lamps arranged therein; Figures 3 and 4 show schematic end views of two different jacket parabolic reflective configurations indicating how radiation intensity may be varied;

Figure 5 shows a side schematic view of a tunnel- type kiln having a number of different zones therein; Figure 6 shows a cross-sectional view of the kiln of Figure 5 taken along the line 6-6;

Figure 7 shows a view similar to that of Figure 5, but for an opposite arrangement of kiln segments.

Figures 8, 9, 10, 12, 13, 14 and 15 show end schematic views of various kiln geometries according to the invention; and

Figure 11 shows a side schematic view of the kiln shown in Figure 10.

Modes for Carrying out the Invention Referring to Figure 1, a jacket is shown in the form of a housing 20 that has a plurality of passages therethrough. The housing is particularly adapted for longitudinally supporting one or more infra-red radiating tubes (IR tubes) 22, but with slight modifications is also suitable for supporting gas burner IR generators and other types of radiation or heat emitter-type devices. The housing is preferably entirely sealed (ie. to be fluid-tight) and is internally pressurised. Thus, any leak therefrom can be detected by an appropriate sensor for a pressure drop. For example, should the cover 42 (described below) break or shatter during use, the process in which the housing is used can be stopped. Knowledge of the breaking of the cover can be critical when the housing is used in a food processing application.

The housing finds particular application with tunnel-type kilns (although is not so limited) and is generally longitudinally arranged through such kilns. In addition, two or more such housings can be arranged longitudinally and in eg. parallel in a given kiln.

In Figure 1, the IR tubes 22 have been removed for clarity, (but are then clearly shown in Figures 2 to 4) . The housing 20 includes a first passage 24 running longitudinally throughout its length. Generally, the housing can extend for the length of a kiln, or alternatively for the length of a tunnel kiln segment (as described below) . The first passage 24 is adapted for having arranged therethrough electrical wiring to be connected between a power source (remote from the kiln and not shown) and a respective IR tube. Alternatively, when a gas burner is employed, the first passage can be used for arranging gas piping therein that is connected between a gas source (located remotely from the kiln and not shown) and the burner. The gas may also be directly fed down the passage 24. The wiring (or piping) is connected to respective IR tubes (or burners) by being passed along the first passage and thence through a respective first hole 26 which has been formed or drilled in the housing.

On either side of the first passage, second coolant passages 28 are provided and are particularly adapted for the through-flow of a liquid coolant (eg. such as water) but may also have a gas coolant flowing therethrough (eg. such as cold air, nitrogen, C0₂ etc) . The housing includes two further passages 30, 32 arranged outside the coolant passages. Passage 30 can be used for the supply of air to a lamp end chamber (described below) and introduces air (optionally to pressurise the housing) into this chamber via flow hole 34 formed or drilled through a wall of the housing. However, the use of passage 30 is not so limited (as will be appreciated from the description of passage 32) . Passage 32 is typically an extra passage provided for the introduction and removal of substances including solids, liquids and gases to or from any product flowing through a kiln in which the housing is mounted.

Temperature, pressure, moisture and other sensors can be introduced into various zones or stages (see below) of a kiln in which the housing is positioned, by being passed down one of the extra passages 28, 30, 32. The wiring etc (for eg. a thermocouple that extends from the housing down into product (or space above the product) ) can be located in the passages and be fed from a suitable receiver (eg. computer controllers to provide continuous feedback about process operating parameters) .

In the roasting of coffee, once the majority of moisture has been driven out of each coffee bean, the coffee beans often undergo a pyrolysis process and then begin to smoke. It then becomes necessary to remove this smoke from the kiln and from the process. A tap hole 36, in communication with the kiln interior, can be formed or drilled through the wall of the housing and into passage 32 at an appropriate position along the housing (ie. at a position corresponding to that position through the kiln at which the coffee beans begin to smoke) . A vacuum may then be applied through the passage 32 and the smoke can be withdrawn from the process (or alternatively a separate suction line, optionally fan driven, can be provided - see for example duct 79 in Figure 6) .

Furthermore, by either using passage 32 or a separate duct (or ducts) 79, other byproducts can be removed. For example, in the IR roasting of coffee beans, the coffee husks become separated from the bean centre, (ie. as the bean swells) . These husks may subsequently ignite under the high IR roasting heats and hence should be removed. This can be easily achieved with preferred duct or passage configurations according to the invention.

When compared to existing processes, the use of this extra passage 32 results in substantially less entrained air being taken in with the smoke. As the smoke must be passed through an after-burner to consume the organics contained in the smoke (and prior to release of the exhaust to atmosphere) , the specific targeting and reduced volume of air achieved in the smoke outflow results in a considerably smaller after burner being required and thus considerable cost savings and benefits follow.

As another example, where the kiln is being used for pre-cooking, for example of rice, it may be necessary or desirable to introduce moisture (ie. water) to the process at a particular point. Again, this water can be passed through passage 32 via tap hole 36, optionally connected to a spray unit to evenly spray the water onto the foodstuff, at a predetermined point of foodstuff flow through the process to assist in the pre-cooking. The possible permutations with the use of the multi- passage housing are endless. Additional coolant passages are provided and smoke and by-product removal is made easy and controllable, as are product additions including moisture and other chemical additions, addition of colouring agents, flavours, emulsifiers, coating chemicals, etc., all at predetermined points during a product's baking, drying, cooking, roasting processes etc.

The housing is typically formed as an extrusion, preferably of aluminium. When forming, it is preferable that a longitudinal channel 38 having a concave or parabolic cross-sectional shape is formed in the housing. A reflective surface 40 (eg. gold) is then formed on the channel base and a cover 42 (typically a glass cover formed of quartz etc.) is mounted over the channel to define an enclosed longitudinal chamber 44. As shown in Figures 2 to 4, the infra-red tubes can then be mounted within this chamber. The advantage of mounting the IR tube in the channel is that it is protected against product and by-product damage and, conversely the product is protected from glass contamination by a broken emitter tube. The glass also prevents product from touching the emitter and being scorched. As described above, the interior of the housing can thus also be pressurised (with the attendant product safety advantages) .

The housing is also provided with steeply sloping sides 46 and 48. Such a configuration is advantageous when the housing is used in a rotating kiln so that any product that drops onto the housing drops back to the base of the kiln to return to the product bulk.

Referring to Figure 2, an underside view of the housing 20 is shown. Each chamber 44 is bound by reflective surface 40, cover 42 and opposing left and right end walls 50 (but only one of which is shown for each chamber 44 in Figure 2) . The end walls can also be provided with a reflective surface facing into the chamber 44 to maximise reflection of radiation and heat out of the housing (ie. as shown in Figures 3 and 4) .

Each IR tube 22 includes a tungsten filament 52 and is formed with a short wave quartz globe (although medium and long wave globes are also used) . Tungsten filaments are the most effective source of radiant energy and the power input to each IR tube is typically varied between 1 and 3 kilowatts. Each tube is supported at its opposing ends in a ceramic lamp holder 54 and the tungsten filament is in turn connected to stainless steel lamp ends 56 (or "pinchpoints") , which in turn are connected to electrical wiring and thence a power source.

A second lamp-end chamber 58 is defined between the end walls 50 and is enclosed by the overlap of covers 42 and a further cover 60, itself typically formed of metal (eg. aluminium) . By enclosing the second chamber, cooling air can be pumped into the chamber via passage 30 and flow holes 34. This cooling air serves to cool the lamp ends and prevents their overheating, thereby maximising the efficiency and longevity of the IR lamps.

All the covers are held in position by a plurality of movable swing tabs 62 and all of the materials are selected and positioned to accommodate the differential expansion of the materials at high temperatures. As the lamp ends reach different operating temperatures to the lamp itself, the provision of separate chambers enables different cooling regimes to be employed and also different expansion characteristics to be accommodated.

Referring to Figures 3 and 4, two different configurations of the long channel 38 and reflective surface 40 of two housings 20 are shown. In Figure 3, a parabolic configuration is adopted that results in a relatively lesser intensity of IR radiation on product P when compared against the parabolic configuration of Figure 4. Of course, many different parabolic and other reflectors, lamp locations, and other configurations are possible with housings made according to the invention.

Referring to Figures 5 to 7, two alternative tunnel apparatus configurations 70 are shown. In Figure 5, tunnel apparatus 70 is inclined from its product entrance 72 to its product exit 74. The tunnel apparatus includes three independently controllable and rotatable segments 76, 77 and 78. The advantage of employing a number of different tunnel segments is that _. each can be independently controlled for each different stage in a product's process treatment cycle. For example, a product can be subjected to infra-red radiation under a rapid rotation in first segment 76. It then passes into second segment 77 where it may be subjected to gas fired heating and rotated in an opposite and slower direction to drive off a significant proportion of moisture. Finally, it moves into the third segment 78 where it is again subjected to IR radiation at an intermediate rotational speed and again in an opposite direction (rotation being indicated by arrows R) . In the third segment 78, product pyrolysis and/or smoking or decomposition may occur and the smoke is generally offtaken in the direction of arrow S, for example, by making use of passage 32 in housing 20. Alternatively or in addition to (or even in direct connection with passage 32) , a round duct 79 (shown in Figure 6) can be employed for the offtake of fumes etc or the addition of commodities. For example, liquid ₂ or CO2 can be added at a certain stage in a coffee roasting process to freeze-dry the coffee, which then may be dropped out of the tunnel apparatus .

Additionally, each segment may be separated from an adjacent segment by a divider plate 80. One such plate is shown in Figure 6. The divider plate functions to provide a clear delineation between the segments, but also provides mounting positions for a housing 20 in each segment . This mounting is facilitated by an extension portion 82 which, as shown in Figure 6, extends partway across the opening to segment 77. The divider plate also allows for the mounting thereon of electrical wiring, gas inlet and out-take pipes 83 (as shown in Figure ) , exhaust pipes and other electronic control lines etc. The employment of a number of dryer segments enables varying segment diameters to be employed. In Figure 5, the diameters of the tunnel segments progressively decrease whereas in Figure 7, the diameters progressively increase. Thus, variations in a number of different product flow regimes, product surface exposure times, bulk product exposure areas etc. can be achieved. The segments can also be stacked, with a first segment being vertically above a second, and a second above a third etc. The product exiting the first segment then enters the second segment and so on. This results in a configuration whereby less longitudinal storage space for the apparatus is required.

Also, by employing segments, and as described above, refined and finely controllable infra-red radiation can be employed at entrance and exit portions (76, 78) of the tunnel and less controlled but cheaper gas heating can be employed in the middle segment (77) . With such a configuration, a more economic use of energy can thus be made.

Also, with the variation in diameters with the different segments, product expansion and shrinking can be accommodated. For example, the configuration of Figure 5 can be used where product shrinking occurs, and a similar throughput and effectively constant product exposure can be maintained because the segment diameters are progressively decreased, whereas in the configuration of Figure 7 product expansion can be accommodated. Also, in the configuration of Figure 7, where additional products are added at different segments (eg. 77 or 78), these may be accommodated without substantially effecting either the product throughput, the bulk or level, or the effective receiving of heat or radiation. Whilst physical separation of tunnel segments (eg. with plates, gaps etc) is one clear way of providing definite and distinct (ie. separate) control zones in a process, variation of process parameters within a single tunnel segment can also result in different zones (eg. where jackets housing different types of IR emitters are arranged in series and/or in parallel; or where emitters in different parts of the tunnel are operated differently; or where coolants and product/byproduct addition/takeoff are varied throughout etc) .

Aside from tunnel rotational speed, the angle of inclination from entrance to exit can be varied to change product throughput (eg. with hydraulic lifters etc) . This, in conjunction with the types of heating and radiation emitters employed, and together with the power or fuel control supplied to those emitters, can provide a number of variable parameters in the configuration, thereby enabling a wide variety of control procedures to be adopted.

Referring to Figures 8 and 9, schematic end views of a tunnel apparatus 70 with a housing 20 arranged therein are shown. It should be mentioned that as the tunnel dryer rotates, the housing is held in a constant horizontal position or at any other desired orientation, optionally adjustable (ie. its ends protrude beyond the opposing ends of the tunnel and are mounted to a frame and may therefore be engaged for adjustment of housing orientation) . The divider plates 80 enable a similar horizontal configuration to be maintained when a plurality of tunnel segments are employed.

Typically coolant is introduced into the housing from the lower end of the apparatus 70. The used coolant can then be pumped to a cooling tower (not shown) for down-cooling prior to being recycled to the housing.

Further, an extraction fan and product feeder (eg. hopper and vibratory feeder) can be provided at the entrance to apparatus 70. The extraction fan can remove moist air/gas, smoke, fumes etc from the process. The feeder can also include a trip switch to shut down the process/apparatus when there is no product feed entering the apparatus (eg. due to a blockage, equipment or manual error etc) . Figure 9 shows a typical horizontal orientation of product P as it progresses through the tunnel 70. With increasing rotational speed (indicated by arrow R) , the product will tend to assume the less horizontal and more inclined levelling as shown by the wavy line in Figure 9. The housing 20 may also be adjusted (tilted) so that the bulk of radiation is generally orthogonal to the product bed level. Figures 10 and 11 now show a tunnel configuration in which a peri-helical screw 84 is arranged on the internal circumference of tunnel apparatus 70. The helical screw tends to act on product flowing through the tunnel in a counter-active direction F (ie. tending to urge the product back up the tunnel in the direction C) . Of course, net product still flows (ie. because relatively more product flows down through the tunnel apparatus than is urged back up by the helical screw) . Typically, when the screw is located adjacent to the base 86 of the tunnel apparatus, the height of the helical screw does not project above the level of the product P (ie. as shown in Figure 10) so that the helical screw primarily causes product turbulence, agitation and a tumbling effect. Where a product flowing through the tunnel apparatus is free flowing, it forms a shallow level bed at the bottom of the dryer throughout the length of the tunnel . However, even free flowing products are difficult to control and process and hence the employment of a helical screw mechanism enhances this control .

With infra-red radiation, it is important to make the product bed level over its whole length because typically infra-red rays heat product to a depth of approximately 9mm for standard infra-red lamp configurations (ie. as described above) . By causing a portion of the product to flow upstream against the generally downward flow F, the rate of product throughput can be controlled as well as the tumbling action of the product . This means that products with uneven surfaces present a plurality of surfaces to be subjected to radiation, resulting in generally even eg. cooking, drying etc. without scorching.

In addition to or separately of the peri-helical screw, one or more helical screw rods 88 as shown in Figure 12 can be employed. The rods may be provided with baffles mounted thereon, in addition to or separately of a screw surface, or can act in conjunction with separate baffles, to agitate product more effectively. In addition the rods may include other types of protrusions for product agitation, stirring, dehusking, orientation and control in general. Each of these rods also has a screw configuration and can be independently or collectively driven (rotated) so that they tend to urge product back in the direction of arrows C to cause both tumbling of the product and to effect the product downstream flow rate F.

The helical screw shape of the peri-helical and other screw types can be varied as to pitch, height of screw vanes, angle of vanes, vane shapes etc. Generally, the more vanes in a given length of screw, the greater the back (or upflow C) of the product. The height of the screw is typically adapted to the size of the product (especially for particulate products) . Screw shapes with smooth or sharp vanes etc. can also control product flow.

Referring to Figure 13, the housing 20 can be provided with a plurality of optionally flexible scraper blades 90 projecting outwardly therefrom. These scraper blades engage against the interior wall of the tunnel apparatus 70 and screw 84 and force or scrape any product that has lodged or attached itself to the apparatus during rotation. The scraper blades can be configured to scrape product off any other surface as appropriate. The employment of scrapers is particularly useful for products that become sticky or tacky during a drying, cooking or roasting process etc. The scrapers prevent product from being attached to the apparatus when appropriately positioned. Also non-stick surfaces can be employed throughout the apparatus to assist in prevention of product adhesion.

Referring to Figure 14, a plurality of baffles 92 can be provided, with the baffles for example extending between vanes of the peri-helical screw or alternatively extending longitudinally throughout the dryer. The baffles tend to cause the product to be lifted up and around the walls of the tube (ie. when the tube is rotated in the direction of arrow R) and, depending on the angle of the baffle, will raise particles a certain height before they ultimately leave the baffle and tumble down back into the bed (ie. as indicated by arrow D in Figure 14) . Where the rotation speed is increased, the baffle will tend to throw particles further distances. The steep sides 46, 48 of the housing tend to prevent product from sitting on top of the housing and enable it to roll back into the main bulk of the product. The employment of baffles enhances the agitation of the product and also ensures that different surfaces of the product passing through the apparatus are presented for radiation/heating. This ensures a more uniform processing of product through the apparatus.

The employment of baffles is also useful for products (such as coffee) which expand when heated, roasted, or cooked etc. As the products expand, the level of the bed rises and sometimes this can effect the capacity of the emitter to heat or radiate the product. The judicious combination of baffles of differing sizes can remove product from the bed for a time to enable the bed level to drop, thereby ensuring consistent radiation/heating.

Figure 15 shows a further variation employed with the peri-helical screw 84. A plurality of product flow- through holes 94 can be formed in the screw vanes, again to enable a controlled product flow F through the tunnel apparatus. The size of these holes can be increased progressively down through the apparatus to accommodate product expansion, or progressively decreased where a product contracts. The number of holes can be increased depending on whether a faster or slower throughput is desired at any given position within the tunnel apparatus. The holes also assist in creating product tumbling and turbulence to ensure maximum exposure of granular, particulate and bead-like product types.

In addition to the apparatus described above, various surfaces within the apparatus can employ friction modifying coatings, such as rough coatings, to facilitate a controlled flow of product .

A forward or rearward direction of product can also be induced by lifting the product up the sides of the tunnel apparatus in parallel channels (defined by baffles) to then land on the housing. The housing may then be provided with diagonal channels in sides 46 or 48 which can either direct the product forwardly or rearwardly within the tunnel apparatus .

The entire process, including parameters such as coolant flow, feed rate, apparatus (tunnel) inclination, radiation temperature, rotational speed(s) , agitation, gas extraction, baffle number, screw speeds etc can be computer controlled and various parameter "menus" specific or optimum to particular products to be processed can be pre-programmed into control software. All parameters can have set points, alarm ranges etc.

Typically many of the components employed are formed from heat resistant materials, including metal materials, ceramic materials etc. (especially aluminium, stainless steel and other alloys) . The apparatus described above has a very wide variety of applications including the roasting of nuts and beans, the blanching of fruit and vegetables, pre-cooking (instantising) of grains, the drying of grains, fruits and vegetables, the gelatinisation of starch, the inactivation of enzymes in a wide variety of foods, the sterilisation of foods, the disinfestation of insects within foods, the roasting, stabilising and sterilising of spices, the treatment of animal feeds, the drying of minerals and mining products in the mining industry, the sterilisation of potting soil, vermiculite expansion, the devitalisation of seed, the sterilisation of pharmaceutical products, the treatment and sterilisation of waste products including sewage etc .

EXAMPLES Non-limiting examples will now be described:

Various produce was subjected to infra-red radiation in equipment according to that described above.

1. ROASTING OF NUTS AND BEANS

The infra-red controlled and penetrating dry roasting method, when applied to nuts and beans, produced an even roast with a high level of uniformity and repeatability. Not only was the control of such a nature that it quarantined minimum damage to nutrients like proteins, vitamins and minerals, but it also inactivated enzymes effectively that caused rancidity and reduced microbial loads drastically. This not only resulted in a much tastier product, but also a healthier product, economical to produce and with an extended shelf life. Uneven size distribution did not have an adverse effect on the end product .

2. SOYA The value of toasted full fat soya for animal and human consumption has long been appreciated, but the process whereby the product was manufactured has not been successful or economical. High costs of equipment, inconsistent results, expensive running costs, labour intensive operations, operational difficul ies, poor quality end products and short shelf life have been but a few of the difficulties encountered in the past. Infra¬ red energy management systems according to the invention were observed to solve many of these problems . Soya in whole, cracked or meal form was processed. Process control approached 100% and was easy to attain and repeat, to be guaranteed at all times. Operation of the equipment did not require full-time supervision, or skilled labour. The soya fat was observed to remain intra cellular, with the result that the end products were easily processed (milled, screened, etc.) unlike conventional extruded products. The shelf life of the product was extended unlike extruded products which have a very much reduced life expectancy before rancidity. A coarse product with natural fibre still intact, was also produced.

The infra-red process not only reduced the trypsine levels effectively every time, but also maintained the available lysine levels.

As a result of the control in the process, protein drainage caused by over processing and trypsine inhibition caused by under processing were both restricted to a minimum. Available metabolisable energy levels were also increased to an average of 3780 Cal per kg.

3. FABA BEANS, PEAS, LUPINS AND OTHER VEGETABLE PROTEINS

The infra-red process was observed to improve the digestible energy of peas, faba beans and lupins considerably, while reducing the growth inhibitors contained within these raw products to safe levels.

Highly beneficial reductions of bacterial blight in peas (Pseudomonas syringae) and considerably lower other mycotoxins and moulds were evident after infra-red treatment.

Infra-red treatment reduced alkaloid levels in lupins from 850 mg/kg to less than 160 mg/kg. Successful precooked peas were also developed for the snack food market, using the infra-red system.

4. COCOA BEANS

Infra-red treatment permitted more economic production of better quality chocolate mass and powder, guaranteeing levels of enterobacteria, salmonella and moulds. Many other advantages were achieved when cocoa beans were processed using the infra-red technology including:

* No fat migration from the cotyledon.

* No detrimental effects on cocoa butter.

* Reduction of fines and dust losses. * A 40% increase in larger nib size.

* Loss of nib and shell less than 2%.

* Optimum nib yields were achieved.

5. BLANCHING OF FRUIT AND VEGETABLES

The speed and continuity of the infra-red process was observed to be an ideal vehicle for instant blanching.

6. INSTANTISING

Over the last ten years the world breakfast cereal market has grown considerably. Consumer awareness of health, diet and the importance of breakfast has stimulated growth, in particular the muesli sector, combining simply recognised natural products - fruit, nuts and cooked cereals. The infra-red system lent itself perfectly to treatment of such products.

7. COOKED CEREALS

The infra-red energy management system provided a gentle method of processing these cereals, producing a product that was very attractive from a nutritious, health, appearance and taste point of view. All the natural goodness of the grain was retained (infra-red treated flaked wheat, pearl barley, rice, rye and cereal bran were observed to be suitable for extensive use in industry) . The infra-red equipment according to the invention facilitated efficient and economical processing of all of these.

Other beneficial properties of infra-red treating were observed to be optimal flavour and colour developments and the ensuring that surface bacteria and moulds were substantially reduced. A unique method of precooking cereals (instantising) was also developed. The end result was a product that had the exact physical appearance and taste of a conventional product, but that required only two minutes cooking time instead or a conventional 40 minutes. The technology was applied to rice, maize and many other cereals, and saved time, the product had a longer shelf life, was observed to be healthier and more nutritious, was cost effective and therefore was more economical . Because of the increased digestibility of the starch it had an improved nutritional value.

Considerable flavour developments were obtained when malted wheat flakes were subjected to infra-red treatment. Toasting with infra-red had the effect of caramelising the sugars, which enhanced flavour characteristics in malted bread and many other products.

8. EXTENDED SHELF LIFE

Infra-red treated samples were compared against untreated samples after a period of 0, 6, 12 and 18 months of storage at room temperature. The untreated samples showed a markedly increased percentage of free fatty acids and peroxide values and were found to be rancid, compared to treated samples. Untreated samples also showed insect and mould contamination after 9 weeks, which the treated samples did not have. It was proved that infra-red treatment can be applied to prolong the safe storage of grains and grain products for up to 18 months.

9. GELATINISATION

The infra-red treatment was observed to control the gelatinisation of starches, which improved the food value of grains and grain products. Other applications for gelatinised starches already exist, where the preferred cost effective and controlled processing methods could be used to great advantage.

10. STERILISATION Up to 100% reduction in bacterial plate counts were achieved by infra-red treatments. Reduced contamination from mycotoxins, fungus and moulds in all cereal grains, beans and spices were also achieved. Many pharmaceutical products, minerals and other chemicals were sterilised effectively with the infra-red system.

11. DRYING

The drying of a vast range of products was successfully conducted with preferred infra-red methods. The combination of variable air extraction and a controlled and effective energy transfer system, made the process effective under many conditions.

Controlled end drying of fruit and vegetables was performed very quickly and effectively. For line drying operations, existing processes were easily installed for any free flowing product .

12. INSECT DISINFESTATION

A non-chemical, in line system for effective insect disinfestation of grain and grain products was provided. Many applications require an effective eradication of all stages of the insect, without doing harm to the seed itself. The present system's effective control and the penetrating characteristics of short wave infra-red lended itself to successfully executing this difficult task.

13. DEVITALISATION

All over the world researchers are working on a non- chemical, and cost effective way of treating seeds to prevent germination without damaging the product . Many countries throughout the world have already banned products like ethylene oxide and methyl bromide and very few effective alternatives are available, if at all. Preferred systems according to the invention provided a cost effective continuous system to do this. 14. ANIMAL FEEDS

Infra-red processed grains resulted in cooked starches that were more digestible and had higher energy values for most animals. Gelatinised grains were incorporated into diets of piglets, pets, horses, rabbits, and cattle. Not only did the animal benefit from an increased energy value, higher digestible fibres and more readily available proteins, but also from reduced microbial contaminated product.

AVAILABLE METABOLISABLE ENERGY (MJ/KG)

RAW TREATED

MAIZE 14.30 15.70

WHEAT 12.90 14.40

BARLEY 11.50 13.70

Feedlot feed conversions, and therefore economics were improved, by using less feed and reducing the feeding time. Milk productions in dairies were increased without additional feed, and higher peaks were achieved because of a denser ration. Infra-red treated barley was observed to be the most effective and palatable source for body building and muscle development in horses.

Full fat infra-red treated Soya is becoming more and more important in animal foods for a number of reasons . Dry dogfood markets are growing, because dry food offers improved health, an economic diet, an attractive appearance, and milk, water and gravy can be added. The need for fat addition to stock feed rations were eliminated in a preferred process. Energy dense rations were also manufactured cheaper.

15. IMPROVED OUTPUT OF EXISTING EXTRUDERS

It was found that by infra-red treatment of a product prior to extrusion, a considerable increase in the product capacity of the extruder was attained. Increased throughput resulted in a very cost effective way to expand a - system without increasing the entire infrastructure. Extruder costs in terms of maintenance was drastically reduced and quality and consistency was also improved.

16. BREWERY CEREAL ADJUNCTS

The search for economy in brewing raw materials has been intensified by the vast increase in the price of barley malt. The performance of infra-red treated cereals under brew house conditions was intensively studied in various breweries. This showed that levels of utilisation of up to 20% of torrefied adjuncts may be incorporated successfully.

17. EXPANSION OF VERMICULITE

The rotary infra-red system proved itself to be the most effective system to expand vermiculite on a small or commercial scale .

Many other applications of the preferred systems were considered possible. The application of the infra¬ red technology proved that the technique facilitates the manufacture of high quality foods with the following characteristics:

* Enhanced, nuttier flavour and more attractive appearance;

* Inactivation of the microbial and enzymatic loads resulting in a safer product, with an extended shelflife;

* A natural product without additives, preservatives and colorants, and without any fibre damage; * Improved starch digestibility, and preservation of undamaged vitamins, minerals and proteins;

* Reasonable price of the equipment, and an effectiveness of processing, therefore a much cheaper product . Other advantages observed included energy efficiency and the fact that infra-red has no harmful effects on personnel operating the equipment, or consumers of the processed products.

Whilst the invention has been described with reference to a number of preferred embodiments, it should be appreciated that the invention can be embodied in many other forms.

Claims

CLAIMS :

1. A multi-ducted jacket for supporting an emitter in a tunnel-type kiln, the jacket including: at least one duct for delivering electricity or fuel to the emitter; and at least one free duct for the delivery or removal of a commodity other than primary coolant to/from the jacket, the emitter or the kiln.

2. A jacket as claimed in claim 1 that is formed from a longitudinal extrusion, wherein the ducts are longitudinally formed in the extrusion and extend fully therethrough.

3. A jacket as claimed in claim 1 or claim 2, wherein the emitter is an infra-red radiation emitter lamp and the at least one duct for delivering electricity is adapted for housing electrical wiring connected between the lamp and a power source.

4. A jacket as claimed in claim 1 or claim 2 wherein the emitter is a gas burner and the at least one duct for delivering fuel is adapted for housing a gas-conduit extending between a gas source and the burner.

5. A jacket as claimed in claim 3 or claim 4 wherein the jacket further includes at least one duct for the transfer of coolant, and optionally this coolant duct includes two such ducts arranged on either side of the one duct for delivery of electricity or fuel to the emitter, each of the two coolant ducts being adapted for the transfer of a first coolant through the jacket.

6. A jacket as claimed in claim 5 wherein the at least one free duct includes two such free ducts, each arranged on the outside of a respective first coolant duct, one free duct being adapted for the delivery of a second coolant, optionally different from the first coolant, and the other free duct being adapted for the introduction or taking away of commodities to/from the kiln.

7. A jacket as claimed in claim 6 wherein the first coolant duct is adapted for the transfer of a water-based coolant therethrough and the second-coolant duct is adapted for the transfer of air (or another cooling gas) therethrough.

8. A jacket as claimed in any one of the preceding claims that includes a generally concave recess along its length and in which the emitter can be arranged.

9. A jacket as claimed in claim 8 wherein in cross- section, a base of the recess is parabolic and includes a reflective material arranged thereon and along its length, such that in use heat and/or radiation released by the emitter is reflected away from the jacket.

10. A jacket as claimed in claim 8 or claim 9 that is adapted for supporting a plurality of emitters in series, with adjacent emitters being of the same or different emitter type.

11. A jacket as claimed in claim 10 wherein each emitter is housed within a respective chamber formed in the recess, with the ends of adjacent emitters extending into a common chamber that is also formed in the recess but between adjacent emitter chambers, and such that a separate coolant can be fed via one of the free ducts to the or each common chamber.

12. A jacket as claimed in claim 11 wherein each emitter chamber is defined by the base of the recess, opposing chamber end walls arranged in the recess and a cover adapted for the transmission of radiation or heat.

13. A jacket as claimed in claim 12 wherein for an infra-red lamp emitter the cover is formed of quartz or similar glass.

14. A jacket as claimed in claim 12 or claim 13 wherein adjacent end walls of adjacent emitter chambers combine with the recess therebetween and a separate cover to define the common chamber, the cover to the common chamber being formed from a metal plate.

15. A jacket as claimed in any one of claims 11 to 14 wherein when the adjacent emitters are infra-red lamps, a separate coolant fed to the common chamber is air.

16. A jacket as claimed in any one of the preceding claims that is adapted for being internally pressured in use .

17. A tunnel-type kiln including one or more of the jackets as defined in any one of the preceding claims.

18. A tunnel-type kiln including two or more zones, each zone being controllable independently of each other zone with respect to a product when fed through the kiln.

19. A kiln as claimed in claim 18 wherein the independent control is achieved by variation of kiln constructional parameters and/or kiln process operating parameters.

20. A kiln as claimed in claim 19 wherein the variation in kiln construction includes one or more transverse baffle plates that are arranged along the kiln to respectively divide it into the two or more zones .

21. A kiln as claimed in claim 20 wherein each baffle plate is adapted for supporting one end of a heat and/or radiation emitter for each zone on either side thereof, or is adapted for supporting one end of a jacket as defined in any one claims 1 to 16; each.baffle plate in addition being adapted for supporting any wiring or piping required for the emitter and/or associated with the ducts.

22. A kiln as claimed in claim 21 wherein the variation in kiln construction is additionally or alternatively achieved by dividing the kiln into a number of separate tunnel segments that each define a respective zone, with a baffle plate optionally being located between adjacent segments.

23. A kiln as claimed in claim 22 wherein from product entry to exit in the kiln, the equivalent cross-sectional diameter of the segments either:

(a) increases; or (b) decreases.

24. A kiln as claimed in any one of claims 19 to 23 wherein the variation in kiln process operating parameters to define each zone is achieved through the positioning along the kiln of one or more separately controllable heat and/or radiation emitter (s) for each zone .

25. A kiln as claimed in claim 24 wherein each emitter is identical to each other emitter but one or more emitters in a given zone are operated differently to one or more emitters in another zone to achieve the independent control of each zone.

26. A kiln as claimed in claim 24 or claim 25 wherein the emitters are as defined in any one of claims 3 to 5.

27. A kiln as claimed in any one of claims 24 to 26 wherein the or each emitter in a respective zone is supported in a jacket as defined in any one of claims 1 to 16. 28. A kiln as claimed in claim 27 wherein the variation in kiln processing operating parameters is additionally or alternatively achieved by varying:

(i) the amount of radiation or heat emitted from each emitter in each zone;

(ii) the amount of coolant flowing through the jacket,-

(iii) the amount of additional coolant flowing through the free duct(s) ; or (iv) the amount of additional commodities delivered to or removed from each zone in use.

29. A kiln as claimed in any one of claims 19 to 28 wherein the variation in kiln construction includes arranging in pre-determined zone(s) : (a) one or more counter and/or co-acting helical screws;

(b) a peri-helical screw arranged on the internal perimeter of the kiln in that zone;

(c) one or more baffles and/or scrapers in the or each zone to respectively lift and distribute product flowing through the kiln or to scrape product from surfaces to which the product attaches; and/or

(d) a variation in curvature of a reflector (optionally parabolic) positioned adjacent to the emitter in each zone.

30. A tunnel-type kiln as defined in claim 18 substantially as herein described with reference to the accompanying drawings .

31. A tunnel-type kiln adapted for having a product flow therethrough in a first direction, with helical screw means positioned in the kiln and adapted in use for engaging and moving at least part of the product in a direction counter to the first direction.

32. A kiln as claimed in claim 31 wherein the helical screw means includes a peri-helical screw arranged on the interior perimeter of the kiln and at least partway therealong.

33. A kiln as claimed in claim 31 or claim 32 wherein the helical screw means includes one or more independently rotatable elongate helical screws extending at least partway along the kiln interior and positioned in use such that the or each screw is generally submerged or immersed in product flowing through the kiln.

34. A kiln as claimed in claim 32 or claim 33 wherein vanes of the or each helical screw are provided with a plurality of holes therethrough to enable a predetermined amount of product to pass through the vanes, thereby generally enabling a flow of that predetermined amount of product in the first direction.

35. A kiln as claimed in any one of claims 31 to 34 that is also configured as defined in any one of claims 17 to 30.

36. A kiln as defined in any one of claims 17 to 35 that is rotatable at various speeds and/or is of adjustable inclination with respect to the horizontal, and downwardly so from kiln entrance to kiln exit, such that in use product feed rate and level through the kiln may also be independently controlled.

37. A method of treating granular product comprising the steps of:

(a) agitating the product in a manner in which the grains are positioned in a plurality of orientations; and (b) subjecting the grains to infra-red radiation in a number of those orientations.

38. A method as claimed in claim 37, that in addition employs apparatus as claimed in any one of claims 1 to 37.

AMENDED CLAIMS

[received by the International Bureau on 07 August 1997 (07.08.97); original claims 18,19,21,24-28,30 and 37 amended; remaining claims unchanged (5 pages)] infra-red lamp emitter the cover is formed of quartz or similar glass.

15. A_\Jacket as claimed in any one of claims 11 to 14 wherein when the adjacent emitters are infra-red lamps, a separate coolant fed to the common chamber is air.

16. A jacket as claimed in any one of the preceding claims that is adapted for being internally pressured in use.

18. A rotary tunnel kiln of the type where product is fed to one end of the tunnel and is removed from the opposite end, the kiln including two or more zones that each include a heat and/or radiation emitting device adapted such that product temperature in that zone can be controlled independently of the or each other zone.

19. A kiln as claimed in claim 18 wherein the independent control is additionally facilitated by variation of kiln constructional parameters and/or kiln process operating parameters.

20. A kiln as claimed in claim 19 wherein the variation in kiln construction includes one or more transverse baffle plates that are arranged along the kiln to respectively divide it into the two or more zones.

21. A kiln as claimed in claim 20 wherein each baffle plate is adapted for supporting one end of the emitting device for each zone on either side thereof, or is adapted for supporting one end of a jacket as defined in any one claims 1 to 16; each baffle plate in addition being adapted for supporting any wiring or piping that is required for the emitting device and/or associated with the ducts.

22. A kiln as claimed in claim 21 wherein the variation m kiln construction is additionally or alternatively achieved by dividing the kiln into a number of separate tunnel segments that each define a respective zone, with a baffle plate optionally being located between adjacent segments.

(a) increases; or

(b) decreases.

24. A kiln as claimed in any one of claims 19 to 23 wherein every zone in the tunnel has a separately controllable emitting device.

25. A kiln as claimed in claim 24 wherein each emitting device is identical to each other emitting device but one or more emitting devices in a given zone are operated differently to one or more emitting devices in another 2one to achieve the independent control of each zone.

26. A kiln as claimed in claim 24 or claim 25 wherein each emitting device is an infra-red lamp as defined in any one of claims 3 to 5 and/or a gas burner that emits infra-red radiation.

27. A kiln as claimed in any one of claims 24 to 26 wherein the or each emitting device in any given zone is supported in a jacket as defined in any one of claims 1 to 16.

28. A kiln as claimed in claim 27 wherein the variation in kiln processing operating parameters is achieved by varying:

(i) the amount of radiation or heat emitted from each emitting device in each zone;

(ii) the amount of coolant flowing through the jacket; (άii) the amount of additional coolant flowing through the free duct{s); or

(lv) the amount of additional commodities delivered to or removed from each zone in use.

29. A kiln as claimed in any one of claims 19 to 28 wherein the variation in kiln construction includes arranging in pre-determined zone(s) :

(a) one or more counter and/or co-acting helical screws; (b) a peri-helical screw arranged on the internal perimeter of the kiln in that zone;

30. A kiln as defined in claim 18 substantially as herein described with reference to the accompanying drawings.

34. A kiln as claimed in claim 32 or claim 33 wherein vanes of the cr each helical screw are provided with a plurality of holes therethrough to enable a predetermined amount of product to pass through the vanes, thereby generally enabling a flow of that predetermined amount of product in the first direction.

37. A method of treating granular product in a vessel comprising the steps of:

(a) agitating the product in a region of the vessel such that the grains are positioned in a plurality of orientations; and

(b) subjecting the grains directly to infra-red radiation from a radiation source located within the same region as the product and whilst the product is in a number of those orientations.