Apparatus and method for heat treatment

Abstract

A thermal treatment apparatus and method in which a vessel having interconnected chambers in which solid material is thermally treated is suspended in a heat exchange medium while it rotates, thereby reducing the energy to rotate the vessel, increasing the heat transfer surface area, increasing the turbulence of the heat exchange medium around the vessel, and improving the movement of solid particles relative to each other and to the heat exchange surfaces. These features combine to increase the heat transfer rate within a compact vessel size.

Description

[Technical field]

[0001] The present invention relates to an apparatus and method for the thermal treatment, in particular of solid materials, and more particularly for the drying, torrefaction and pyrolysis of carbonaceous materials such as biomass, solid waste and fossil fuels. [Background technology]

[0002] Many physical and chemical processes are either exothermic or endothermic, hereafter commonly referred to as thermal processing, and include heating and cooling. Heat needs to be supplied or removed.

[0003] Known means for supplying or removing heat to or from a material include the following. (a) Direct means via contact or mixing, for example by passing a hot flue gas stream or a cold air stream through a bed of the solid material to be heat-treated; and / or (b) Indirect means via heat transfer, for example, heat from another source such as hot oil is transferred to the material through a heat exchanger.

[0004] Despite their many advantages, direct means are limited in many practical applications. This is because many processes cannot be carried out by contacting or exposing the solid material to air or another medium. For example, drying municipal solid waste by passing it through a hot stream of flue gas can spread pathogens and release odorous compounds into the environment, contacting combustible solids with hot air can cause explosions, cooling hot solid products by blowing cold air can oxidize the products, oxygen in the air can react with the solid materials, and processes such as pyrolysis need to be carried out in the absence of a sufficient air supply. In these types of applications, indirect means, for example the supply or removal of heat via a heat exchanger, are desirable.

[0005] The economics of thermally treating solid materials via heat transfer depend heavily on the creation of a large heat transfer surface area. Applicant's previous WO2015089556, the entire contents of which are incorporated herein by reference, discloses an apparatus for pyrolyzing carbonaceous materials having a vessel with an enhanced heat transfer surface area. However, the configuration disclosed therein requires an energy-intensive agitator to continuously agitate and transport the solid material to be thermally treated from the inlet to the outlet of the stationary vessel. The agitation action is necessary to create turbulence in the motion of the solid particles, which is very important to increase the rate of heat transfer to the solid particles. In addition to high energy consumption, the agitator also increases friction between the solid material to be treated and the reactor walls, negatively affecting the life of the equipment. Furthermore, energy-intensive pumps are required to pump the heat exchange medium, especially the liquid, at a high enough speed to achieve a high heat transfer rate of the fluid turbulence.

[0006] In many existing heat treatment processes that use equipment such as rotary kilns, the vessels holding the solid material being treated must have thick walls in order to have sufficient strength to accommodate the weight of the solid material being treated. However, thick walls tend to slow the rate of heat transfer across the walls. Where the heat transfer coefficient is relatively low, the vessels are often large in size to provide sufficient processing / residence time to supply or remove the heat required for the heat treatment process. Larger vessel sizes in turn require increased vessel wall thickness. Both thick wall construction and large vessel sizes increase capital and operating costs. Summary of the Invention [Problem to be solved by the invention]

[0007] It would be desirable to provide an apparatus for heat treating a solid material and producing a heat treated product having one or more improved characteristics. It would also be desirable to provide a method for heat treating a solid material and producing a heat treated product having one or more improved characteristics.

[0008] Any discussion of documents, devices, acts, or knowledge in this specification is included for the purpose of explaining the context of the invention and is not to be construed as an admission that any of the material formed part of the prior art base or common general knowledge in the relevant art prior to the priority date of the claims herein. [Means for solving the problem]

[0009] According to a first aspect of the present invention there is provided an apparatus for heat treating a solid material to produce a heat treated product, the apparatus comprising: an inner vessel having an inlet for supplying solid material into an interior space defined by walls of the inner vessel and an outlet for removing thermal treatment products generated within the inner vessel, the interior space defining a first passage between the inlet and the outlet of the inner vessel; an outer container containing a heat exchange medium between an inner container and an outer container, the outer container including an inlet for supplying the heat exchange medium into the outer container and an outlet for removing the heat exchange medium from within the outer container, a second pathway defined by a wall of the inner container and a wall of the outer container between the inlet and the outlet of the outer container, the inner container configured for at least partial immersion in the heat exchange medium, and the first pathway and the second pathway being in heat transfer proximity to one another for heat transfer across the wall of the inner container; Equipped with the inner vessel is configured to be rotated about an axis to facilitate relative movement between a wall of the inner vessel and the heat exchange medium, to facilitate movement of solid particles within the inner vessel relative to each other and relative to the wall of the inner vessel, and to pass the solid material and heat treated products along a first path toward an outlet of the inner vessel; The minimum distance from the wall of the inner vessel, perpendicular to the axis about which the inner vessel is rotated, varies along the length of the axis to increase the surface area for heat transfer across the wall of the inner vessel.

[0010] The apparatus may be arranged such that, in use, an axis about which the inner container is rotated is inclined at an oblique angle relative to the ground plane. The oblique angle may be selected to adjust the speed at which the solid material being heat treated in the inner container is transported along the first path.

[0011] The heat exchange medium may include a liquid that exerts a buoyant force on the inner vessel. The heat exchange medium may include a pressurized fluid that exerts a buoyant force on the inner vessel. The pressurized fluid may include a supercritical fluid.

[0012] The amount of heat exchange medium contained in the outer vessel may be controlled such that the buoyant force exerted by the heat exchange medium on the inner vessel is less than or equal to the total weight of the inner vessel and the solid material contained therein.

[0013] The walls of the inner container may be arranged such that the shortest distance from the wall of the inner container to the axis about which the inner container rotates varies periodically along the length of the axis of rotation. In one embodiment, the walls of the inner container include a plurality of inwardly projecting formations that divide the interior space of the inner container into a series of interconnected chambers, the projecting formations being spaced apart from one another along the length of the inner container.

[0014] Each protruding formation may extend radially inwardly and may include first and second annular wall surfaces at an acute angle relative to one another, the first and second wall surfaces converging to define an inner radius of the inner container. The acute angle may be less than or equal to 45 degrees, such as between 1 and 5 degrees, or even between 1 and 3 degrees.

[0015] A series of radially inwardly narrowing annular gaps may be provided on the exterior of the inner vessel by acute angles of the first and second annular wall surfaces of the protruding formations.

[0016] A plurality of baffles can be attached to the outer vessel protruding toward the inner vessel, at least a portion of the baffles positioned to align with an annular gap on the exterior of the inner vessel, and the baffles configured to direct flow of heat exchange medium into the gaps.

[0017] The outer container may have a semi-cylindrical lower section and a rectangular upper section.

[0018] The apparatus may further include one or more rollers and / or bearings disposed between the inner container and the outer container to support the inner container for rotation relative to the outer container.

[0019] The inlet and outlet of the inner vessel may be disposed at opposite ends of the inner vessel. The inlet of the outer vessel may be disposed in a lower portion of the outer vessel and may include an inlet manifold for distributing the heat exchange medium along the length of the outer vessel via a plurality of sub-inlets.

[0020] The outlet of the outer vessel may be disposed at a top of the outer vessel and may include an outlet manifold for allowing the heat exchange medium to exit the outer vessel via multiple sub-outlets along the length of the outer vessel.

[0021] The apparatus may be provided with a grinding media including a plurality of free moving elements for grinding and crushing solid material within the rotating inner vessel.

[0022] The apparatus may be configured such that the peak temperature within the inner vessel is controllable in a range suitable for drying the solid material.

[0023] The apparatus may be configured such that the peak temperature within the inner vessel is controllable in a range suitable for torrefying solid materials.

[0024] The apparatus may also be configured such that the peak temperature within the inner vessel is controllable in a range suitable for pyrolyzing the solid material.

[0025] The solid material may be any one or more of the following carbonaceous materials: biomass, fossil fuels and municipal solid waste.

[0026] In one particular embodiment, the interior space of the inner container is defined by a wall, such as two or more walls. Additionally, the second passageway may be defined by a wall of the inner container and a wall, such as two or more walls, of the outer container between the inlet and the outlet of the outer container.

[0027] In a second aspect of the present invention there is provided an apparatus for heat treating a solid material to produce a heat treated product, the apparatus comprising: an inner vessel comprising an inlet for supplying solid material into an interior space defined by at least one wall of the inner vessel and an outlet for removing thermal treatment products generated within the inner vessel, the interior space defining a first passage between the inlet and the outlet of the inner vessel; an outer container containing a heat exchange medium between an inner container and an outer container, the outer container including an inlet for supplying the heat exchange medium into the outer container and an outlet for removing the heat exchange medium from within the outer container, a second pathway defined by at least one wall of the inner container and at least one wall of the outer container between the inlet and the outlet of the outer container, the inner container configured for at least partial immersion in the heat exchange medium, and the first pathway and the second pathway being in heat transfer proximity to one another for heat transfer across the at least one wall of the inner container; Equipped with the inner vessel is configured to rotate about an axis to facilitate relative movement between at least one wall of the inner vessel and the heat exchange medium, to facilitate movement of solid particles within the inner vessel relative to each other and relative to the at least one wall of the inner vessel, and to pass the solid material and heat treated products along a first path toward an outlet of the inner vessel; The minimum distance from the at least one wall of the inner vessel perpendicular to the axis about which the inner vessel is rotated varies along the length of the axis so as to increase the surface area for heat transfer across the at least one wall of the inner vessel.

[0028] In a third aspect of the present invention there is provided a method for heat treating a solid material to produce a heat treated product, the method comprising: - feeding a solid material into an inner vessel rotated about an axis, the shortest distance from a wall of the inner vessel to the axis about which the inner vessel rotates varying along the length of the axis; - supplying a heat exchange medium to an outer vessel, the inner vessel being at least partially immersed in the heat exchange medium within the outer vessel such that the heat exchange medium exerts a buoyant force on the inner vessel while heat exchange occurs across a wall of the inner vessel between the solid material and the heat exchange medium to produce a thermally treated product; - removing the heat treatment product from an outlet of the inner vessel; Includes.

[0029] In one embodiment, the wall of the inner container comprises a plurality of inwardly protruding formations that divide the interior space of the inner container into a series of interconnected chambers, the protruding formations being spaced apart from one another along the length of the inner container.

[0030] In one embodiment, the heat exchange medium comprises a liquid or pressurized fluid to increase the degree of buoyancy.

[0031] In one particular embodiment, the amount of heat exchange medium is adjusted so that the sum of the buoyant forces is less than or equal to the total weight of the inner vessel and the solid material contained therein.

[0032] In a fourth aspect of the present invention there is provided a method for heat treating a solid material to produce a heat treated product, the method comprising: - feeding a solid material into an inner container rotated about an axis, the shortest distance from at least one wall of the inner container to the axis about which the inner container rotates varying along the length of the axis; - supplying a heat exchange medium to an outer vessel, the inner vessel being at least partially immersed in the heat exchange medium in the outer vessel such that the heat exchange medium exerts a buoyant force on the inner vessel while heat exchange occurs between the solid material and the heat exchange medium across at least one wall of the inner vessel to produce a thermally treated product; - removing the heat treatment product from an outlet of the inner vessel; Includes.

[0033] The embodiments of the present invention advantageously eliminate the need for an agitator to continuously agitate and rotate the solid material. Furthermore, the energy requirements of the device are advantageously reduced by utilizing buoyancy to suspend the rotating inner vessel. Furthermore, the rotating vessel immersed in the heat exchange medium creates a high relative velocity between the walls of the inner vessel and the heat exchange medium to achieve a high heat transfer rate. The rotation of the inner vessel rotates the solid material within the inner vessel to improve the movement of the solid particles relative to each other and to the vessel walls (i.e., the heat exchange surface), thereby improving the heat transfer between the walls of the inner vessel and the solid material being processed.

[0034] Heat transfer involves at least two materials for heat to be transferred from a hotter material to a colder material. While the above description has focused on the thermal treatment of solid materials to induce physical and / or chemical changes in the solid materials, those skilled in the art will appreciate that the above disclosed methods and apparatus can also be used to treat fluids, i.e., induce the necessary physical and / or chemical changes in the fluids, by using solids as heat exchange media without departing from the scope of the present invention.

[0035] Notwithstanding any other forms that may fall within the scope of the apparatus and methods described in the Summary, specific embodiments will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0036] [Figure 1] 1 is a schematic longitudinal cross-sectional view of an apparatus according to one embodiment of the present invention; [Diagram 2] FIG. 2 is a schematic cross-sectional view of the device shown in FIG. [Diagram 3] FIG. 13 is a cross-sectional schematic view of an apparatus having an alternative outer container. [Figure 4] 4 is a schematic longitudinal cross-sectional view of an apparatus according to another embodiment of the present invention; [Diagram 5] 11 is a schematic longitudinal cross-sectional view of an apparatus according to another alternative embodiment of the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] With reference to the accompanying drawings, there is shown an apparatus 10 for the thermal treatment of solid materials, such as biomass and / or municipal solid waste, to produce a thermally treated product. By way of example, it will be convenient to describe the invention for use in drying biomass and solid municipal waste. However, it will be understood that the apparatus is suitable for wider application and use, for example as an apparatus for the torrefaction and pyrolysis of carbonaceous materials.

[0038] The apparatus 10 includes an inner vessel 12 and an outer vessel 16. The inner vessel 12 is configured to be at least partially immersed in a heat exchange medium 13 contained in the outer vessel 16. The heat exchange medium 13 preferably includes a liquid, such as thermal oil. It may also include a supercritical fluid. Since thermal oil is one type of commonly used heat exchange medium, the invention will be described herein with reference to this particular medium. The inner vessel 12 includes an inlet 14 for providing a solid material 11, shown in FIG. 1 as "wet material", within an interior space defined by the walls of the inner vessel 12. Heat transfer between the solid material 11 and the heat exchange medium 13 occurs across the walls of the inner vessel 12. The inlet 14 may include a hopper 15 and a screw feeder 17 configured to feed the solid material into the interior of the inner vessel 12. The inner vessel 12 further includes an outlet 18 through which the heat-treated product produced within the inner vessel 12, shown in FIG. 1 as "dry material", exits. The inlet 14 of the inner vessel 12 is preferably provided at one end of the inner vessel 12 and the outlet 18 is provided at the opposite end. The interior space of the inner vessel 12 between the inlet 14 and the outlet 18 defines a first path along which the solid material to be treated travels. The apparatus 10 further includes bearings 19 provided at either end of the inner vessel 12 to support the inner vessel 12 for rotation relative to the outer vessel 16.

[0039] A motor (not shown in FIG. 1) via a transmission mechanism 25 is used to rotate the inner vessel 12 about an axis 56 (shown in dotted line in FIG. 1). The walls of the inner vessel 12 are not constructed as a standard cylinder, but rather are constructed such that the shortest distance from the wall of the inner vessel 12 to the axis 56 about which the inner vessel rotates varies along the length of the axis to increase the heat transfer surface area across the walls of the inner vessel 12.

[0040] It will be apparent that the walls of the inner vessel can take many different shapes. In a preferred embodiment, the walls of the inner vessel 12 include a plurality of inwardly projecting formations that divide the interior space of the inner vessel 12 into a series of interconnected chambers 30. The projecting formations are spaced apart at regular intervals from one another, preferably in substantially parallel alignment. The projecting formations may be annular in shape so as to define a substantially circular passageway 32 (FIG. 2) that extends radially inwardly and passes through a central longitudinal axis of the inner vessel 12, which is preferably, but need not necessarily, substantially the same as the axis 56 about which the inner vessel rotates. The circular passageway 32 interconnects the chambers 30 and provides a path for the flow of material gradually through adjacent chambers 30 within the inner vessel 12 from the inlet 14 to the outlet 18. It will be appreciated, however, that the circular passageway 32 may be sized and shaped in a variety of manners.

[0041] As best shown in FIG. 1, the protruding formations may include a first annular wall surface 24 and a second annular wall surface 26 at an acute angle. The acute angle may range up to 45° relative to one another, preferably 1°-10°, and even more preferably about 3°. The first and second wall surfaces 24, 26 converge to define an inner radius of the inner vessel 12 represented by a circular passage 32. At the exterior of the inner vessel 12, the first and second annular wall surfaces 24, 26 form a series of annular gaps 28 that narrow radially inward. The annular gaps 28 advantageously increase the surface area (heat transfer surface area) of the inner vessel 12, thereby maximizing the ability of the thermal oil to transfer heat across the walls of the inner vessel 12 to materials within the interior space of the inner vessel 12.

[0042] Additionally, to further increase the heat transfer surface area and rate, fins or similar structures known to those skilled in the art, now or in the future, can be added to the sides of the inner vessel wall that contact the heat exchange medium, particularly faces 24 and 26. The fins also help to improve turbulence in the heat exchange medium.

[0043] The outer vessel 16 includes an inlet 20 for supplying a heat exchange medium (e.g., thermal oil) into the outer vessel 16 and an outlet 22 for removing the thermal oil from the outer vessel 16. A second pathway is defined between the inlet 20 and the outlet 22 along which the thermal oil flows to indirectly provide heat for drying, pyrolysis, and the like. The inlet 20 for the thermal oil is preferably provided in a lower section of the outer vessel 16 and preferably includes an inlet manifold 40 for distributing the thermal oil along the length of the vessel 16 via a plurality of sub-inlets 42. Similarly, the outlet 22 for the thermal oil is disposed in an upper section of the outer vessel 16 to ensure that the thermal oil must flow around the inner vessel 12 to reach the outlet 22. The outlet 22 extends the length of the outer vessel 16 and includes an outlet manifold 44 that allows the thermal oil to exit via a plurality of sub-outlets 46 along the length of the outer vessel 16.

[0044] 3 shows an alternative embodiment having a different shape of the outer container 16. The lower section of the outer container 16 has the shape of a semi-cylinder. The upper section of the outer container 16 is preferably cuboid in shape. This advantageously makes it easier to place the inner container 12 downwardly into the outer container 16 during assembly.

[0045] FIG. 4 shows a schematic of an alternative apparatus 10' according to another embodiment of the invention. The same numbers as in FIG. 1 are used to indicate similar features. A heat exchange medium 13 (e.g., thermal oil) enters the outer vessel 16 through an inlet 20 and exits the outer vessel 16 through an outlet 22 located at the opposite end of the outer vessel 16. A plurality of baffles 50 are attached to the inner surface of the outer vessel 16. The baffles 50 may be positioned to project toward the inner vessel, at least a portion of the baffles being aligned with the annular gaps 28 on the exterior of the inner vessel 12. The baffles are designed to increase turbulence by directing the flow of the heat exchange medium into the gaps 28. The heat exchange medium enters each gap 28 by entering the space between its face 24 and the baffle 50, then exits each gap 28 by flowing through the space between its face 26 and the baffle 50. The heat exchange medium then flows along the narrow annular space between the inner vessel 12 and the outer vessel 16 before entering the subsequent gap 28. In this arrangement, the heat exchange medium is forced to flow sequentially through each gap 28. After passing through the last gap 28, the heat exchange medium exits the outer vessel via outlet 22.

[0046] The amount of thermal oil in the outer vessel 16 depends on the total weight of the inner vessel 12 and the material being processed in the inner vessel 12. Preferably, the amount of thermal oil in the outer vessel 16 is controlled so that buoyancy and gravity forces generally balance each other, or balance each other as much as possible, so that the bearings 19 support a minimum weight of the inner vessel 12 and its contents. In one particular example where the inner vessel is constructed with thin walls and the inner vessel 12 is in place, the thermal oil occupies approximately 60-70% of the volume of the space between the inner vessel 12 and the outer vessel 16 in order for buoyancy and gravity forces to balance each other.

[0047] Although the illustrated chambers 30 are all of uniform construction, this is not necessary: ​​the chambers 30 can be smaller toward the outlet 18 of the inner vessel 12, for example, to increase the surface area.

[0048] 2 and 3, each chamber 30 may also include a series of members 48 that function to mix, scoop, and lift the materials within the inner container 12 during rotation. The lifters 48 may take a variety of shapes known to those of skill in the art now and in the future, for example, they may be L-shaped.

[0049] FIG. 5 illustrates generally another alternative apparatus 10″ in accordance with another embodiment of the present invention. The same numbers as in FIG. 1 are used to indicate similar features. The key difference between apparatus 10″ and apparatuses 10 and 10′ is that faces 24 and 26 protrude beyond axis 56. Chambers 30 of apparatus 10″ also interconnect differently than the chambers of apparatuses 10 and 10′.

[0050] Apparatus 10, 10' or 10" may also include a variable speed electric motor (not shown) for rotating inner vessel 12 at a preset speed via transmission mechanism 25, which may be varied to adjust the turbulence of the heat exchange medium, the turbulence of the movement of solid particles relative to each other and to the walls of the inner vessel, and the residence time of solids within inner vessel 12.

[0051] The apparatus 10, 10' or 10" may be mounted on a skid base frame that can be used for lifting and transport. Additionally, the angle of inclination of the inner vessel 12 relative to the horizontal may be varied. Thus, the residence time of the solid material and resulting treated product within the apparatus 10, 10' or 10" may be controlled to allow a period of time sufficient for the material to be substantially treated at a given temperature.

[0052] In further embodiments of the present invention, the apparatus may be further adapted to simultaneously heat treat and grind or crush the material as it flows through the inner vessel 12 from the inlet 14 to the outlet 16. In these particular embodiments, the apparatus 10, 10' or 10" may include a grinding medium including a plurality of freely movable elements (e.g., hard bodies). The freely movable elements may take the form of balls, which typically have diameters ranging from about 10 mm to about 120 mm and are made from a variety of hard materials including steel and ceramic. The grinding media may be mixed with the material before or after it is introduced into the apparatus 10, 10' or 10" via the inlet 14. The grinding media may be supplied to the apparatus 10, 10' or 10" by other means known to those skilled in the art now or in the future. The grinding media may remain within the inner vessel 12. Rotating the inner vessel 12 imparts momentum to the grinding media, causing it to repeatedly collide with the solid material. The grinding media may also advantageously contribute to a mass heat transfer effect within the inner vessel 12.

[0053] Advantageously, if the solid material to be heat treated, such as a wet pasty solid, can adhere to the walls of the inner vessel 12, the use of grinding media can effectively remove the solid from the walls of the inner vessel 12.

[0054] In use, solid material such as municipal waste or biomass may be introduced into said apparatus 10, 10' or 10" via the inlet 14 of the inner vessel 12. The material is gradually transported through the interconnected chambers 30 of the inner vessel 12 from one end to the opposite end thereof by rotating the inner vessel 12. Lifters 48 in the interconnected chambers 30 aid in the movement of material within the chambers 30 and into adjacent chambers 30. To further facilitate the movement of material along the path, the inner vessel 12 may be inclined, for example, between 0° and 45°. The angle of inclination relative to the horizontal may also be varied to adjust the speed at which the material to be heat treated is transported along the path to the outlet 18. By appropriately selecting the temperature of the hot oil, the apparatus 10, 10' or 10" may be conveniently used as a dryer, a torrefaction unit or a pyrolysis unit. For example, by selecting an operating temperature above 300°C, the apparatus can be used to produce pyrolysis products, at temperatures of about 200°C-280°C, the apparatus can be used to produce torrefaction products, and at lower operating temperatures of 100°C-200°C, the apparatus can be used as a dryer to evaporate moisture in the material being processed.

[0055] Physical and / or chemical changes occur in the heat exchange medium. Rotating a vessel suspended in liquid is similar to a boat sailing through water, which is very energy efficient.

[0056] It will be readily apparent to one of ordinary skill in the art that embodiments of the present invention may offer advantages over the prior art, including, but not limited to, the following.

[0057] To provide an apparatus and method in which a vessel having interconnected chambers in which solid material is heat treated is suspended in a heat exchange medium while it rotates, thereby reducing the energy to rotate the vessel, increasing the heat transfer surface area, increasing turbulence of the heat exchange medium around the vessel, and improving the movement of solid particles relative to each other and to the heat exchange surfaces. These features combine to increase the rate of heat transfer within a compact vessel size.

[0058] To provide a versatile device that can be used as a heating or cooling unit depending on the heat exchange medium flowing through the outer vessel of the device, To provide an efficient drying apparatus having an increased heat exchange surface area compared to prior art drying units to enhance the rate of heat exchange.

[0059] It will also be understood that while the foregoing description refers to a particular order of process steps, the apparatus and devices and their configurations are provided for illustrative purposes only and are not intended to limit the scope of the invention in any way.

[0060] In describing the present invention, unless the context requires otherwise by explicit language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" are used in the inclusive sense, i.e., to specify the presence of stated features but not to exclude the presence or addition of further features in various embodiments of the invention.

Claims

1. 1. An apparatus for heat-treating a solid material to produce a heat-treated product, comprising: an inner vessel having an inlet for supplying the solid material into an interior space defined by a wall of the inner vessel and an outlet for removing the heat treatment product produced within the inner vessel, the interior space defining a first passage between the inlet and the outlet of the inner vessel; an outer container containing a heat exchange medium between the inner container and the outer container, the outer container including an inlet for supplying the heat exchange medium into the outer container and an outlet for removing the heat exchange medium from within the outer container, a second pathway defined by the wall of the inner container and a wall of the outer container between the inlet and the outlet of the outer container, the inner container configured to be at least partially immersed in the heat exchange medium, and the first pathway and the second pathway being in heat transfer proximity to each other for heat transfer across the wall of the inner container; Equipped with the inner vessel is configured to rotate about an axis to facilitate relative movement between the wall of the inner vessel and the heat exchange medium, to facilitate movement of solid particles within the inner vessel relative to each other and relative to the wall of the inner vessel, and to pass the solid material and the heat treatment product along the first path toward the outlet of the inner vessel; wherein a minimum distance from the wall of the inner vessel perpendicular to the axis about which the inner vessel is rotated varies along the length of the axis to increase surface area for heat transfer across the wall of the inner vessel.

2. 2. The apparatus of claim 1, wherein the apparatus is arranged such that, in use, the axis about which the inner container rotates is inclined at an oblique angle relative to a ground plane to adjust the rate at which the solid material being heat-treated in the inner container is transported along the first path.

3. The apparatus of claim 1 , wherein the heat exchange medium comprises a liquid that exerts a buoyant force on the inner vessel.

4. The apparatus of claim 1 , wherein the heat exchange medium comprises a pressurized supercritical fluid that exerts a buoyant force on the inner vessel.

5. 4. The apparatus of claim 3, wherein the amount of heat exchange medium contained in the outer container is controlled so that the buoyancy force exerted by the heat exchange medium on the inner container is less than or equal to the total weight of the inner container and the solid material contained therein.

6. 2. The device of claim 1, wherein the walls of the inner container are arranged such that a shortest distance from the walls of the inner container to the axis about which the inner container is rotated varies periodically along the length of the axis about which the inner container is rotated.

7. 10. The device of claim 1, wherein the wall of the inner container comprises a plurality of inwardly protruding formations that divide the interior space of the inner container into a series of interconnected chambers, the protruding formations being spaced apart from one another along the length of the inner container.

8. 8. The apparatus of claim 7, wherein each protruding formation includes first and second annular wall surfaces extending radially inward and at an acute angle relative to one another, the first and second wall surfaces converging to define an inner radius of the inner container.

9. The apparatus of claim 8, wherein the acute angle is between about 1 and 20 degrees.

10. 9. The apparatus of claim 8, wherein a series of radially inwardly narrowing annular gaps are provided on the exterior of the inner vessel by the acute angles of the first and second annular wall surfaces of the protruding formations.

11. 11. The apparatus of claim 10, wherein a plurality of baffles are attached to the outer vessel and protrude toward the inner vessel, at least some of the baffles are positioned to align with the annular gap on the exterior of the inner vessel, and the baffles are configured to direct the flow of the heat exchange medium into the gap.

12. 10. The apparatus of claim 1, wherein the outer container has a semi-cylindrical lower section and a rectangular upper section.

13. 10. The apparatus of claim 1, further comprising one or more rollers and / or bearings disposed between the inner container and the outer container to support the inner container for rotation relative to the outer container.

14. The device of claim 1 , wherein the inlet and the outlet of the inner container are disposed at opposite ends of the inner container.

15. 2. The apparatus of claim 1, wherein the inlet of the outer vessel is disposed in a lower portion of the outer vessel and includes an inlet manifold for distributing the heat exchange medium along a length of the outer vessel through a plurality of sub-inlets.

16. 2. The apparatus of claim 1, wherein the outlet of the outer vessel includes an outlet manifold disposed at a top of the outer vessel for allowing the heat exchange medium to exit the outer vessel through a plurality of sub-outlets along a length of the outer vessel.

17. 10. The apparatus of claim 1, wherein the apparatus is provided with a grinding media comprising a plurality of free-moving elements for grinding and crushing solid material within the inner vessel.

18. The apparatus of claim 1 , wherein the apparatus is configured such that a peak temperature within the inner vessel is controllable within a range suitable for drying the solid material.

19. The apparatus of claim 1 , wherein the apparatus is configured such that a peak temperature within the inner vessel is controllable within a range suitable for torrefying the solid material.

20. The apparatus of claim 1 , wherein the apparatus is configured such that a peak temperature within the inner vessel is controllable within a range suitable for pyrolyzing the solid material.

21. The apparatus of claim 1 , wherein the solid material is any one or more of a carbonaceous material: biomass, fossil fuel, and municipal solid waste.

22. An apparatus according to any one of the preceding claims, wherein a physical and / or chemical change occurs in the heat exchange medium.

23. 1. An apparatus for heat-treating a solid material to produce a heat-treated product, comprising: an inner vessel having an inlet for supplying the solid material into an interior space defined by at least one wall of the inner vessel and an outlet for removing the heat treatment product produced within the inner vessel, the interior space defining a first passage between the inlet and the outlet of the inner vessel; an outer container containing a heat exchange medium between the inner container and the outer container, the outer container including an inlet for supplying the heat exchange medium into the outer container and an outlet for removing the heat exchange medium from within the outer container, a second pathway defined by the at least one wall of the inner container and at least one wall of the outer container between the inlet and the outlet of the outer container, the inner container configured to be at least partially immersed in the heat exchange medium, and the first pathway and the second pathway being in heat transfer proximity to each other for heat transfer across the at least one wall of the inner container; Equipped with the inner vessel is configured to rotate about an axis to facilitate relative movement between the at least one wall of the inner vessel and the heat exchange medium, to facilitate movement of solid particles within the inner vessel relative to each other and relative to the at least one wall of the inner vessel, and to pass the solid material and the heat treatment product along the first path toward the outlet of the inner vessel; wherein a minimum distance from the at least one wall of the inner vessel perpendicular to the axis about which the inner vessel is rotated varies along the length of the axis to increase a surface area for heat transfer across the at least one wall of the inner vessel.

24. 1. A method for heat-treating a solid material to produce a heat-treated product, the method comprising: - feeding a solid material into an inner container that is rotated about an axis, the shortest distance from the wall of the inner container to the axis about which the inner container is rotated varying along the length of the axis; - supplying a heat exchange medium to an outer vessel, the inner vessel being at least partially immersed in the heat exchange medium within the outer vessel such that the heat exchange medium exerts a buoyant force on the inner vessel while heat exchange occurs between the solid material and the heat exchange medium across the wall of the inner vessel to produce the thermally treated product; - removing said heat treatment product from the outlet of said inner vessel; A method comprising:

25. 25. The method of claim 24, wherein the wall of the inner container comprises a plurality of inwardly protruding formations that divide the interior space of the inner container into a series of interconnected chambers, the protruding formations being spaced apart from one another along the length of the inner container.

26. 25. The method of claim 24, wherein the heat exchange medium comprises a liquid or pressurized fluid to increase the degree of buoyancy.

27. The method according to any one of claims 24 to 26, wherein the amount of the heat exchange medium is adjusted so that the sum of the buoyant forces is equal to or less than the total weight of the inner vessel and the solid material contained therein.

28. 1. A method for heat-treating a solid material to produce a heat-treated product, the method comprising: - feeding a solid material into an inner container that is rotated about an axis, the shortest distance from at least one wall of the inner container to the axis about which the inner container is rotated varying along the length of the axis; - supplying a heat exchange medium to an outer vessel, the inner vessel being at least partially immersed in the heat exchange medium within the outer vessel such that the heat exchange medium exerts a buoyant force on the inner vessel while heat exchange occurs between the solid material and the heat exchange medium across the at least one wall of the inner vessel to produce the thermally treated product; - removing said heat treatment product from the outlet of said inner vessel; A method comprising:

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