GB1600373A

GB1600373A - Heat exchagers

Info

Publication number: GB1600373A
Application number: GB776378A
Authority: GB
Original assignee: SHERWEN ENG CO Ltd
Current assignee: SHERWEN ENG CO Ltd
Priority date: 1978-03-03
Filing date: 1978-03-03
Publication date: 1981-10-14

Description

(54) IMPROVEMENTS IN OR RELATING TO HEAT EXCHANGERS (71) We, SHERWEN ENGINEERING COMPANY LIMITED, a British Company of Mile End Green, Dartford, Kent, do hereby declare the invention for which we pray that a patent may be granted to us and the method by which it is to be performed to be particularly described in and by the following statement: This invention relates to rotary heat exchangers in which particulate material, e.g. powder, granules, pellets or larger masses, is agitated or turned over with the rotation of the chamber. The term heat exchanger is intended herein to include apparatus in which heat transfer is effected by radiant and/or conductive heating.

While the invention is applicable to relatively low temperature heating processes, such as the drying of particulate materials in a heated gas stream, it is especially concerned with the use of such apparatus in the combustion of material and/or the manufacture of burned or fired materials, namely materials that require to be subjected to temperatures perhaps as much as 1300"C or more in their processing. As examples there may be mentioned lime burning, the production of dead-burned magnesia or of cement, and particularly the production of artificial aggregates from materials such as clay or shale in which the material is processed to produce larger aggregate pieces within a desired range of size.

The use of cylindrical rotary chambers for heating particulate material is well known.

By rotating the chamber about its cylindrical axis the material is continuously agitated by the counteracting forces of friction with the drum surface and of gravity, and fresh surfaces are being continually exposed to the heating effect of a flame or a hot gas stream.

The amount of material that can be easily heated in the chamber at any time is however very limited in relation to the size of the chamber because as the depth of the material bed increases it becomes more difficult to ensure that all the particles are exposed in turn to the source of heat.

Non-uniform heating of the material may necessitate a longer heating time and in some instances it may be difficult to obtain a sufficiently uniform final product. Moreover, if the whole mass within the chamber is not continually agitated individual particles may accrete together, even while being agitated, and the physical and/or chemical changes intended by the heating process may not occur. In high-temperature conditions, such as the firing of clay-containing materials, this effect may cause large masses of material to fuse together to form masses of slag or clinker which must be discarded and which indeed may be difficult to remove from the chamber.

It is known to provide inwardly extending projections such as axial bars at the chamber walls to increase the agitation of the material and these may also have the effect of increasing the depth of the material bed.

The cylindrical form of the kiln is maintained, not least because the circular crosssection is required for strength and it also is the most efficient shape from the aspect of heat loss through the walls. In hightemperature applications the arduous physical conditions also limit the use of such projections: in Danish Patent No. 128 218 a brick-lined kiln uses bricks of different thicknesses to form inward projections, but these must be kept shallow and must be protected against abrasion and impact from the kiln contents my metal shields which are themseleves vulnerable to damage, and hardly modify the conventional circular cross-section.

It should be appreciated that the known cylindrical rotary chambers, because of the small depth of the material in the chamber, can lose a considerable proportion of the heat input in the cooling effect of the chamber walls on the material, which reduces the efficiency of operation. In hightemperature processes an inner refractory brick lining is provided, which results in a very heavy kiln structure requiring massive supports and high-power drive motors. Such kilns are costly to maintain due to the need for frequent repair and replacement of the brick lining. This also leads to considerable loss of production and efficiency as on each occasion the kiln must be allowed to cool down and must afterwards be brought at a controlled rate to its operating temperature.

Because of the high thermal mass these procedures may each occupy a number of days.

According to the present invention, there is provided a rotary heat exchanger comprising a chamber having entry and exit openings at opposite ends for a particulate material to be passed through the chamber for heating or cooling by means therein, the chamber having a non-circular internal cross-section transverse to its axis of rotation comprising a plurality of lobes, whereby material within the chamber can be alternately restrained to co-rotate with the chamber and then allowed to slip under gravity during the continued rotation of the chamber, and means being provided to support the chamber with its rotary axis inclined downwardly from the entry end to cause said rotation to progress the material towards the exit end.

Advantageously, the cross-section is formed by a configuration with three equispaced lobes, having a clover leaf or trefoil shape. It can have a greater number of such lobes but not so as to limit their depth unduly, as they should be relatively deep radially of the rotary axis of the chamber, e.g. between 20% and 60%, preferably approximately 40% to 55%, of the maximum radius of the chamber. The lobes conveniently have a curved profile and are so shaped as to retain the material therein against slippage until they have undergone a substantial angular displacement from their lowest position, e.g. preferably at least 20C from that position, when a critical slope angle is reached.The material then begins to slip and the complete mass of particles is turned over relatively rapidly to come to rest again until the critical angle is again passed due to the continuing rotation of the kiln.

If the material is being heated by one or more burners it can be arranged that between each slippage direct radiant energy from the burner acts on the uppermost layers of the material for a relatively extended period, and the burner may be provided with reflecting means to increase the radiant heat output onto the material, while heat can also be transferred by conduction from a hot gas flow over the material. The cross-sectional profile of the chamber may also be so arranged that heat radiating from the uppermost lobe or lobes, from which the material has already fallen, tends to be preferentially directed towards the main mass of the material in a rising lobe.

With the complete turn-over of the material occurring several times in each revolution of the chamber it is possible to obtain substantially uniform heating of the material. Moreover, because of the retaining effect of the lobes, the bed of material in the chamber can be kept relatively deep so that a lesser surface area is in contact with the chamber walls for a given volume of material and the cooling effect of the walls is reduced.

For high-temperature operations, a rotary chamber according to the invention may comprise a kiln structure having a heatresisting inner lining and external loadbearing support means for the lining and the contents of the chamber, said support means extending longitudinally of the kiln but being thermally insulated from the inner lining. The inner lining will of course have the aforementioned transverse cross-section with lobes to increase direct radiant heating from a burner or burners in the kiln onto the material being processed.

The heat-resisting inner lining of the kiln may form the inner layer of a sandwich construction, with a thermal insulation layer in the space between the heat-resisting lining and an outer casing. The inner liner may be a unitary circumferential construction, either extending the full length of the chamber or being made up of a series of shorter circumferentially closed lengths with overlapping joints, or it may comprise a series of similar segments welded together, and in either instance it is preferably supported by the outer casing segments directly through the insulating layer which will be of a form that can transmit the bearing loads from the inner lining directly to the outer casing.

If the inner lining is a single circumferential unit, however, it may be sufficient to rely solely on the spacing effect of the insulating layer to hold the lining in place in relation to the outer casing.

The invention will be described by way of example with reference to the accompanying diagrammatic drawings, wherein Figures 1 and 2 are a side view and a transverse sectional view respectively of a high-temperature rotary heating chamber or kiln according to the invention, Figure 3 is a detail sectional view showing the sandwich construction of the walls of the chamber in Figures 1 and 2, Figure 4 is a schematic plan view of the burner shown in Figure 2, Figures 5 and 6 illustrate the fuel supply system of the burner of Figures 4 and 5, and Figures 7 and 8 are a side view and a transverse sectional view respectively of a further rotary heat exchange chamber according to the invention intended to operate at a lower temperature than the preceding examples.

Referring to Figures 1 and 2 of the drawings. the kiln comprises a rotary container 12 mounted on a fixed support frame 14. The container is supported through rollers 16 on the fixed frame and on which sit end rings 18 fixed to the container. The end rings act as circular guide tracks for the rotation of the container which is driven by one or more hydraulic motors 20 secured to the fixed frame and also engaging the end rings. The container comprises a heating chamber 22 having an internal transverse cross-section of trefoil shape with three deep lobes 24. each of curved profile. The cusps or regions of transition 26 between the lobes are flattened to avoid overheating.In this particular example, the lobes are circular with a diameter equal to the chamber radius at the middle point of the lobes and their circular loci all intersecting at the central longitudinal axis of the chamber.

The walls of the kiln are of a sandwich construction comprising a 6 mm outer mild steel supporting shell 32, a 100 mm main insulating lining 34 the outer cooler layers of which may be mineral wool and the inner hotter layers ceramic fibre, a permanent inner lining 36 of a high-temperature alloy, for example of 3 mm Incoloy 800H (Trade Mark), a heat resistant alloy rich in Ni and Cr. Within these layers there is preferably also a further thin, 12 mm, layer 38 of ceramic fibre insulation. and an innermost high-temperature alloy lining 40. also of 3 mm Incoloy 8()0H. that provides the inside surface of the kiln.

All the layers of this construction have similar lobed profiles with flattened transitions between the lobes. The outer shell 32 may be constructed first, with the end rings adjacent opposite ends of the container for supporting the container on the follers 16.

Spacers 44 secured to the inner face of the shell locate the inner lining 36 which is fabricated as a single circumferential unit, e.g. of welded panels (it may however be produced as a series of short axial lengths which are then assembled with overlapping circumferential joints within the shell. The spacers 44 locate the lining 36 at a uniform gap from the outer shell and the insulation 34 is then packed in and eventually acts as the spacing means. The insulation 38 is then laid over the lining 36 and finally component plates of the innermost lining 40 are placed over the second insulation layer and welded to form a continuous inner wall.

The layers of the sandwich construction are not positively secured together, to allow for differential thermal expansion. Nevertheless because of the non-circular crosssection they are located circumferentially without slippage. The inner layers are supported over their whole peripheral area by the outer casing shell and, moreover, the weight of the material in the kiln is similarly transmitted directly to the outer shell. The inner metal linings are thus substantially unstressed and the loads are supported by the relatively cool outer shell and transmitted through the end rings 18 to the rollers 16.

It is to be expected nevertheless that under very high temperatures and with abrasion from the kiln contents, the innermost lining 40 may wear in use. The inner insulation 38 operates as a tell-tale if a hole appears in the lining 40 and this can then be patched. Normal wear can therefore be repaired without affecting the intermediate lining 34 the life of which is further extended due to the insulating effect of the layer 38.

At the material entry end of the chamber, there is a cylindrical extension 52 of diameter slightly less than the minimum diameter at the regions of transition between the lobes. Projecting into the inlet end of the chamber extension is an inlet box 54 into which the material to be fired is fed through a top opening 55. The material falls on a cascade of vanes 56 that deflect it into the cylindrical extension but that ensure there is a free passage for the kiln exhaust gases to flow to an outlet 58 such as the rear outlet shown. Further details of the manner in which these inlet and outlet connections are employed are given in our concurrently filed patent application Nos. 8936)77 (Serial No.

1600372) and 8988/77 . The cylindrical extension has a cruciform axially extending barrier 60 dividing its interior into a series of smaller passages forming a transition to the main, lobed region of the kiln where there is a more intense tumbling action.

At the exit end of the kiln the fired particles spaced through a chute 62 leading to an outlet duct 64 connected to a forced draft fan 66. Cool air from the fan impinges on the material, so cooling it suddenly, and also entraining it in the manner of a jet pump so that it is carried away in the air flow.

The kiln heat source may be a radiant fluid fuel burner e.g. Figure 1 shows a thermal lance 68 projecting coaxially into the chamber from a fixed mounting 69 at the material exit and, while Figure 2 shows another radiant burner that will be described in more detail below. Because the kiln relies principally on radiant heating, the lobed cross-section offers an advantage in that the radiant energy is substantially better focussed on to the material than in a conventional rotary kiln. In other words, for a given burner flame length, the radiant heat flux density at the surface of the material bed is substantially increased, and the heat flux density may be as much as 2.5 times that in a conventional design.This, together with the tumbling action that exposes all the material continually to the radiant heat, allows the use of a kiln of much shorter length than a plain cylindrical kiln for the same output.

As its radiant heat energy is employed, the burner can be operated under substantially stoichiometric conditions and a minimum gas flow through the kiln is needed.

This will reduce the requirement for dust extraction from the waste gases but, more importantly in processes in which an excess of oxygen may have an adverse effect, such as in the firing of clay materials, it is easier to maintain a non-oxidising atmosphere in the chamber.

Figures 4 to 6 show further details of the burner 100 of Figure 2 and its control means. The burner comprises a casing 102 that extends over the whole or a substantial part of the total length of the kiln and is supported through stilt shafts 104 at both ends.The casing his a firing face 106 from which the burner flames are arranged to impinge on the material being processes to heat it by direct flame contact as well as by radiant heating. The firing face is inclined to the horizontal so that it faces onto the material held in a lobe of the kiln at that stage at which the material is beginning to slip into the succeeding lobe as the kiln rotates. the burner casing itself normallv remaining stationarv but being tiltable on its stub shafts to an optimum angle for a chosen kiln rotation speed.

The burner casing can have an inner stainless steel lining 108 covered by a layer of ceramic fibre insulation 110 and sheathed with an outer covering 112 of Incoloy (Trade Mark) or a ceramic or cermet material. The firing face in particular is required to have good properties of heat resistance but the opposite faces of the burner casing are not employed as radiant heating surfaces and are subject only to extraneous heating effects. They will therefore be subject to much lower maximum temperatures and need less protection.

A large number of burner nozzles 114 are arranged over substantially the full extent of the firing face. The nozzles are ganged in groups to common fuel supply lines 116 with groups of, say, six nozzles occupying a short extent, e.g. 15 em, of the length of burner casing being operated together. Control valves 118 in the supply lines to the respective groups of nozzles are regulated by pyrometers 120 arranged also in the firing face, each adjacent its own group of nozzles so that the temperature profile along the length of the burner casing can be controlled as well as the maximum temperature at the firing face.

The burner is oil-fired (but a gas-fired arrangement can be provided) and the nozzles 114 are conventional low pressure nozzles, such as are known in domestic heating installations, with a common pump 122 supplying a header circuit 124 from which all the burner nozzles are fed. A forced draft fan 126 provides combustion air at a small positive pressure through conduit 127, the interior 128 of the burner casing 102 acting as a duct for the airflow and simultaneously being cooled by it.

The shape of the firing face, in particular its concave form as seen in Figure 2, is chosen to concentrate its radiant heat emission onto the material being processed, but the rear faces of the casing can have any convenient shape. Because the burner casing offers the possibility of directing the major part of the heat output directly onto a relatively deep bed of material, the temperature of the kiln interior walls will be lower and it may also be possible to direct a cooling gas flow through the space behind the burner. It may therefore be found possible to economise both as regards hightemperature protection of the casing and its thermal insulation.

The embodiment of the invention illustrated in Figures 7 and 8 is not intended for the very high temperatures of the preceding examples, and functions as the lowtemperature dryer in our co-pending patent application Nos. 8986/77 and 8988/77 (Serial No. 1600372). In this further construction the cross-sectional form of the chamber is as already described but the heat source is a hot gas stream, e.g. of combustion gases for the purpose of heating and/or drying particulate material in the chamber. The internal metal walls of the chamber are at a low enough temperature to form part of a load-carrying structure and it is sufficient simply to surround this inner casing with an outer layer of heat-insulating material (not shown) to avoid undue heat losses. The heating gases generated in a burner 80 in an airflow generated by a forced draft fan 82.

the flow through the chamber being assisted by an induced draft fan 84 at the exit. The gases enter the chamber through a central axial tube 86 having exit slots 88 running longitudinally of the chamber. Preferably.

said slots are in a face directed downwardly and slightly to one side so that the hot gas is directed mainly onto the bed of material contained in a rising lobe. analogously to the burner shown in Figure 2. Transverse baffle plates 90 are provided at intervals along the length of the chamber to ensure a minimum quantity of material is retained.

Material is introduced through a fixed entry chamber and an exhaust gas chimney 92 is connected to the outlet of the fan 84.

The dryer rotary chamber is mounted in a static support frame 93 by end mounting rings 94 fixed to th chamber casing and supported on rollers 95, with drive means 96 operating in the same way as the example of Figure 1. In this instance the end rings are secured to the chamber by pairs of tie rods 97 extending between peripheral flanges 98 of the casing and lugs 99 projecting inwardly on the mounting rings.

In each example of chamber described, material is progressed through the chamber as it rotates by virtue of the chamber being tilted slightly downwards, about 1" to 2", towards the material exit. Because of the lobed cross-section of the chamber, as it rotates the material in the bottom lobe is lifted to the point at which it exceeds its angle of repose. A thick upper layer then slips and falls into the succeeding lower lobe to be followed quickly by the remaining material that previously formed the lower layers but that now falls on top of the first portion of the material. This process is continuously repeated as each lobe rises from a lowermost position.In effect, the material is continually turned over as it falls in a free stream in one localised region of the chamber cross-section so that all the material is exposed to the heat source three times in every revolution of the chamber in a concentration similar to that achieved in a fluidised bed.

The rate of progress of material through the chamber can be controlled by altering the downwards inclination of the longitudinal axis of the chamber from the material entry and e.g. by the support rollers towards one end of the chamber being vertically adjustable.

Because of the relatively high heating efficiency of the lobed heat exchangers described, as a result of the continual intensive turnover of their contents, these chambers can be very much shorter than a plain cylindrical chamber particularly as regards a high-temperature or firing kiln.

The described kiln with its lightweight insulation can be cooled for repair and brought back to operating temperatures in a few hours, and the weight reduction also greatly assists transportability in comparison with a conventional kiln with a brick lining or a refractory castable cement lining although it is possible to employ the lobed transverse cross-sectional form with more conventional materials.

It will be understood that the terms heat exchanger and heating chamber as used in this specification and claims also embraces all heat exchange chambers including chambers that function to cdol material by exposing it to a cooler gas stream, since in that case it is the gas that is heated. An example is the fired pellet cooling chamber that is described in our concurrently filed patent application Nos. 8986/77 and 8988/77 (Serial No. 1600372).

WHAT WE CLAIM IS: 1. A rotary heat exchanger comprising a chamber having entry and exit openings at opposite ends for a particulate material to be passed through the chamber for heating or cooling by means therein, the chamber having a non-circular internal cross-section transverse to its axis of rotation comprising a plurality of lobes, whereby material within the chamber can be alternately restrained to co-rotate with the chamber and then allowed to slip under gravity during the continued rotation of the chamber, and means being provided to support the chamber with its rotary axis inclined downwardly from the entry end to cause said rotation to progress the material towards the exit end.

2. A rotary heat exchanger according to claim 1 wherein the cross-section has a configuration with three equi-spaced lobes.

3. A rotary heat exchanger according to claim 2 wherein the lobes have a radial depth that is between 20% and 60% of the maximum radius of the chamber crosssection.

4. A rotary heat exchanger according to claim 3 wherein said radial depth is between 40% and 55% of said maximum radius.

5. A rotary heat exchanger according to any one of the preceding claims wherein the lobes each provide a chamber wall portion in the form of a circular arc in a plane normal to the chamber axis.

6. A rotary heat exchanger according to claim 5 wherein said arcuate wall portions have circular loci that intersect in the region of the chamber axis.

7. A rotary heat exchanger according to any one of the preceding claims wherein the chamber cross-section comprises flattened transition regions between adjacent lobes.

8. Rotary heat exchanger according to any one of the preceding claims wherein there is at least one circumferentially extending baffle within the chamber for retaining a minimum quantity of material progressing through the chamber in the region behind said baffle.

9. A rotary heat exchanger according to any one of the preceding claims wherein said entry and exit openings are arranged in centrally disposed end regions of the chamber having a cross-section substantially smaller than said lobed cross-section.

10. A rotary heat exchanger according to any one of the preceding claims having a

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. baffle plates 90 are provided at intervals along the length of the chamber to ensure a minimum quantity of material is retained. Material is introduced through a fixed entry chamber and an exhaust gas chimney 92 is connected to the outlet of the fan 84. The dryer rotary chamber is mounted in a static support frame 93 by end mounting rings 94 fixed to th chamber casing and supported on rollers 95, with drive means 96 operating in the same way as the example of Figure 1. In this instance the end rings are secured to the chamber by pairs of tie rods 97 extending between peripheral flanges 98 of the casing and lugs 99 projecting inwardly on the mounting rings. In each example of chamber described, material is progressed through the chamber as it rotates by virtue of the chamber being tilted slightly downwards, about 1" to 2", towards the material exit. Because of the lobed cross-section of the chamber, as it rotates the material in the bottom lobe is lifted to the point at which it exceeds its angle of repose. A thick upper layer then slips and falls into the succeeding lower lobe to be followed quickly by the remaining material that previously formed the lower layers but that now falls on top of the first portion of the material. This process is continuously repeated as each lobe rises from a lowermost position.In effect, the material is continually turned over as it falls in a free stream in one localised region of the chamber cross-section so that all the material is exposed to the heat source three times in every revolution of the chamber in a concentration similar to that achieved in a fluidised bed. The rate of progress of material through the chamber can be controlled by altering the downwards inclination of the longitudinal axis of the chamber from the material entry and e.g. by the support rollers towards one end of the chamber being vertically adjustable. Because of the relatively high heating efficiency of the lobed heat exchangers described, as a result of the continual intensive turnover of their contents, these chambers can be very much shorter than a plain cylindrical chamber particularly as regards a high-temperature or firing kiln. The described kiln with its lightweight insulation can be cooled for repair and brought back to operating temperatures in a few hours, and the weight reduction also greatly assists transportability in comparison with a conventional kiln with a brick lining or a refractory castable cement lining although it is possible to employ the lobed transverse cross-sectional form with more conventional materials. It will be understood that the terms heat exchanger and heating chamber as used in this specification and claims also embraces all heat exchange chambers including chambers that function to cdol material by exposing it to a cooler gas stream, since in that case it is the gas that is heated. An example is the fired pellet cooling chamber that is described in our concurrently filed patent application Nos. 8986/77 and 8988/77 (Serial No. 1600372). WHAT WE CLAIM IS:

1. A rotary heat exchanger comprising a chamber having entry and exit openings at opposite ends for a particulate material to be passed through the chamber for heating or cooling by means therein, the chamber having a non-circular internal cross-section transverse to its axis of rotation comprising a plurality of lobes, whereby material within the chamber can be alternately restrained to co-rotate with the chamber and then allowed to slip under gravity during the continued rotation of the chamber, and means being provided to support the chamber with its rotary axis inclined downwardly from the entry end to cause said rotation to progress the material towards the exit end.

generally cylindrical entry section through which to feed material into said lobed cross-section, the entry section having a radius not greater than the inner radius of said lobes.

11. A rotary heat exchanger according to any one of the preceding claims having heating means arranged to provide a radiant heat source extending axially through the central region of the chamber over at least a major part of its length.

12. A rotary heat exchanger according to any one of the preceding claims wherein the chamber has a sandwich wall construction comprising an inner metal lining, an intermediate heat-insulating jacket and an outer metal casing through which the weight of the internal lining and the contents of the kiln are supported.

13. A rotary heat exchanger according to claim 12 wherein a further lining is provided inside the first lining and is separated from the first lining by an insulation layer thinner than the first insulation layer.

14. A rotary heat exchanger according to claim 12 or claim 13 wherein the or each inner liner is located relative to the outer casing by contact pressure from its adjoining insulation layer of said sandwich wall construction between the liner and the easing.

15. A rotary heat -exchanger according to any one of claims 12 to 14 wherein rigid elements secured to the outer casing project inwardly through the thickness of the adjoining insulation layer to bear locatingly on the inner liner adjoining said layer.

16. A rotary heat exchanger according to any one of claims 12 to 15 wherein the or each inner lining is composed of one or more circumferentially closed units.

17. A rotary heat exchanger according to any one of the preceding claims comprising means provided by a fluid fuel burner having a combustion face arranged to direct heat onto the material held by a rising lobe of the chamber cross-section during the rotation of the chamber.

18. A rotary heat exchanger according to claim 17 wherein the burner is tiltable about the rotary axis of the kiln to adjust the direction of its heat output.

19. A rotary heat exchanger according to claim 17 or claim 18 wherein the burner combustion face has a transverse crosssection of concave form for increasing the concentration of radiant thermal energy on said material.

20. A rotary heat exchanger according to any one of claims 17 to 19 wherein means are provided to control the heat output of the burner in a varying manner over its length axially of the kiln.

21. A rotary heat exchanger according to claim 20 wherein the burner has a plurality of groups of fuel nozzles the combustion at which is arranged to be controlled by respective temperature sensing means each disposed in or adjacent the zone of the respective group of nozzles.

22. A rotary heat exchanger according to any one of the preceding claims having means at the chamber outlet for producing a cooling gas stream arranged as a jet pump to carry away the heated material through an output duct while cooling it.

23. A rotary heat exchanger according to any one of claims 1 to 16 arranged for use as a drier of the particulate material.

24. A rotary heat exchanger according to any one of the preceding claims arranged for use as a high temperature heating containter or kiln.

25. A rotary heat exchanger constructed and arranged for use and operation substantially as described herein with reference to Figures 1 to 3 or Figures 7 and 8 of the accompanying drawings.

26. A rotary heating container or kiln constructed and arranged for use and operation substantially as described herein with reference to Figures 1 to 6 of the accompanying drawings.