阅读说明：本技术 微波热解反应器 (Microwave pyrolysis reactor ) 是由 阿丝盖尔·温恩 于 2019-09-23 设计创作，主要内容包括：本发明提供一种微波热解反应器(1),包括内管元件(2)和壳体(4),其中,内管元件(2)由透微波材料制成,布置在壳体内并且包括第一开口端(5)和第二开口端(6)；壳体(4)包括第一内表面、废物入口(10)、固体出口(11)、气体出口(12)和用于微波波导(14)的端口(13),第一内表面包围围绕内管元件(2)的环形空间(7、44),废物入口和固体出口分别与内管元件的第一开口端和第二开口端连通,并且用于微波波导的端口与环形空间连通；内管元件、壳体的废物入口和固体出口形成不与围绕内管元件的环形空间流体连通的导管的部分,并且其中,内管元件经由布置在内管元件的第一开口端(5)和第二开口端中的至少一个处的圆柱形弹性组件(54)夹紧在壳体内,弹性组件适于允许内管元件(2)的纵向膨胀并且包括中心贯穿通道(57),该中心贯穿通道具有与内管元件的中心线(C)成一直线的中心线。(The invention provides a microwave pyrolysis reactor (1) comprising an inner tube element (2) and a housing (4), wherein the inner tube element (2) is made of a microwave transparent material, is arranged within the housing and comprises a first open end (5) and a second open end (6); the housing (4) comprises a first inner surface enclosing an annular space (7, 44) surrounding the inner tubular element (2), a waste inlet (10), a solids outlet (11), a gas outlet (12) and a port (13) for a microwave waveguide (14), the waste inlet and the solids outlet communicating with the first and second open ends of the inner tubular element, respectively, and the port for the microwave waveguide communicating with the annular space; the inner tubular element, the waste inlet and the solids outlet of the housing form part of a conduit which is not in fluid communication with an annular space surrounding the inner tubular element, and wherein the inner tubular element is clamped within the housing via a cylindrical resilient assembly (54) arranged at least one of the first open end (5) and the second open end of the inner tubular element, the resilient assembly being adapted to allow longitudinal expansion of the inner tubular element (2) and comprising a central through passage (57) having a centre line in line with the centre line (C) of the inner tubular element.)

1. A microwave pyrolysis reactor (1) comprising an inner tubular element (2) and a housing (4), wherein

-the inner tubular element (2) is made of a microwave transparent material, arranged within the housing and comprises a first open end (5) and a second open end (6);

-the housing (4) comprises a first inner surface enclosing an annular space (7, 44) surrounding the inner tubular element (2), a waste inlet (10), a solids outlet (11), a gas outlet (12) and a port (13) for a microwave waveguide (14), the waste inlet and the solids outlet communicating with the first and second open ends of the inner tubular element, respectively, and the port for a microwave waveguide communicating with the annular space;

-the inner tubular element, the waste inlet and the solids outlet of the housing form part of a conduit which is not in fluid communication with the annular space surrounding the inner tubular element, and

wherein the inner tubular element is clamped within the housing via a cylindrical resilient assembly (54) arranged at least one of the first open end (5) and the second open end of the inner tubular element, the resilient assembly being adapted to allow longitudinal expansion of the inner tubular element (2) and comprising a central through channel (57) having a centre line in line with a centre line (C) of the inner tubular element.

2. A microwave pyrolysis reactor according to claim 1, wherein the resilient assembly comprises at least one spring element (54) compressible in a direction parallel to a centre line (C) of the inner tubular element and a fluid tight annular wall, the spring element having a first end (55) and a second end (56).

3. A microwave pyrolysis reactor according to claim 2, wherein the spring element (54) is cylindrical and comprises a central through channel (68) having a centre line in line with the centre line (C) of the inner tubular element.

4. A microwave pyrolysis reactor according to claim 2 or 3, wherein the spring element (54) is arranged to provide an evenly distributed force to at least one of the first open end (5) and the second open end (6) of the inner tube element.

5. A microwave pyrolysis reactor according to any of claims 2 to 4, wherein the spring element is made of a suitable metal, such as stainless steel.

6. A microwave pyrolysis reactor according to any of claims 2 to 5, wherein the spring element (54) is bellow-shaped.

7. A microwave pyrolysis reactor according to any preceding claim, wherein each of the first open end (5) and the second open end (6) of the inner tube element (2) comprises an annular surface (58, 59) arranged in a plane perpendicular to a centre line of the inner tube element.

8. A microwave pyrolysis reactor according to claim 7, wherein each of the first open end (5) and the second open end (6) comprises a flared portion (60, 61), characterized by the annular surface.

9. The microwave pyrolysis reactor according to any one of the preceding claims, wherein a protective sleeve (62) is arranged inside the at least one spring element (54), preferably such that the inner volume of the inner tube element (2) is not in fluid communication with the spring element.

10. A microwave pyrolysis reactor according to any preceding claim, wherein the resilient assembly (54) forms part of the conduit.

11. A microwave pyrolysis reactor according to any preceding claim, wherein the gas outlet (12) and the solids outlet (11) are a common outlet (11, 12) arranged downstream of the inner tube element (2).

12. A microwave pyrolysis reactor according to any preceding claim, wherein the inner tube element (2) is substantially vertical and arranged such that the first open end (5) is at a higher level than the second open end (6) such that material entering the waste inlet (10) during use is conveyed by gravity from the first open end to the second open end through the inner tube element.

13. A microwave pyrolysis reactor according to claim 7, wherein the annular surface (59) of the second open end (6) faces an annular shoulder (63) within the housing such that the inner tubular element is clamped between the annular shoulder and the resilient assembly.

14. The microwave pyrolysis reactor of any preceding claim, wherein the housing comprises a flange element (64) arranged to clamp the resilient assembly (54) between the flange element (64) and the first open end of the inner tube element.

15. A waste treatment system comprising a microwave pyrolysis reactor according to any one of the preceding claims, a microwave source (49) and a gas treatment system (47); wherein

-the microwave source (49) is connected to the port (13) through a microwave waveguide (14); and is

-the gas treatment system (47) is connected to the gas outlet (12) and comprises a suction arrangement (48) arranged such that the pressure at the gas outlet (12) can be kept below ambient pressure during use.

16. Use of a microwave pyrolysis reactor according to any one of claims 1 to 13 or a waste treatment system according to claim 14 for microwave assisted pyrolysis of any material susceptible to heating by microwaves.

Technical Field

The present invention relates to the field of microwave assisted pyrolysis reactors, and more particularly to a microwave pyrolysis reactor for waste treatment, the use of such a microwave pyrolysis reactor in a waste treatment system, and a waste treatment system comprising a microwave pyrolysis reactor.

Background

Offshore waste treatment and management, for example on board ships, is usually obtained by the combined use of incinerators, collecting waste (e.g. edible oil, sludge, paper, plastic, cardboard and wood pallets) for subsequent weekly landings and discharge of sludge and food waste into the sea. Thus, the environmental footprint is quite large, especially in areas where shipping traffic is high. This is particularly evident in cruise ships, where certain ports and sea areas have many regulations that prohibit discharge to the ocean and exhaust emissions. The latter is prohibited for vessels at port, thus limiting the use of onboard incinerators. Many of the same problems and concerns associated with waste treatment and management are found in rural areas, islands and the like where the use of large scale waste treatment facilities is limited.

In addition to conventional incinerators, pyrolysis systems have also been used in waste treatment systems. Pyrolysis is the thermochemical decomposition of organic materials at high temperatures in the absence of oxygen, and in these systems, the pyrolysis reaction is obtained by internal plasma arc or external heating. The advantage of using a pyrolysis reactor instead of an incinerator is the low environmental impact in terms of air pollution and residue emissions. In addition to char, pyrolysis reactors produce syngas and/or bio-oil, which may be used to fuel boilers and/or gas turbines to produce energy as heat or electricity. Although known waste treatment systems using such pyrolysis reactors are superior in many respects to systems using incinerators, there is still great potential for improvement.

A recent and important development in the pyrolysis field is the microwave assisted pyrolysis reactor. In these reactors, microwaves are used to heat the material to be pyrolyzed.

Waste treatment systems using microwave assisted pyrolysis with microwave pyrolysis reactors are known. Examples of such systems are disclosed in, for example, US 5387321 and US 6184427B 1. Lam et al in energy (2012, 5, 4209 to 4232) review the physical principles, effects and advantages of using microwave assisted pyrolysis in waste treatment and waste to energy applications.

A microwave assisted pyrolysis reactor is disclosed in CN 102580650B. In CN102580650B, the gas generated within the reactor was allowed to exit the inner tube element of the reactor via an outlet arranged in the side wall of the reactor.

It is an object of the present invention to provide a microwave-assisted pyrolysis reactor suitable for microwave-assisted pyrolysis of various types of waste in a waste treatment, disposal and/or processing system. The present invention provides a microwave pyrolysis reactor which has a simple construction, is stable with respect to the type and size distribution of the waste to be pyrolyzed, and does not rely on a complicated solution of moving the waste to be pyrolyzed through the reactor. In particular, the present invention provides a reactor having improved operating life and shorter service intervals. It is another object of the present invention to mitigate or eliminate at least some of the disadvantages of prior art microwave-assisted pyrolysis reactors and waste treatment systems.

Disclosure of Invention

The invention is defined by the appended claims and by the following:

in a first aspect, the present invention provides a microwave pyrolysis reactor comprising an inner tubular element and a shell, wherein

-an inner tubular element made of a microwave transparent material, arranged within the housing and comprising a first open end and a second open end;

the housing comprises a first inner surface enclosing an annular space surrounding the inner tubular element, a waste inlet and a solids outlet communicating with the first and second open ends of the inner tubular element, respectively, and a port for a microwave waveguide communicating with the annular space; and

-the inner tubular element, the waste inlet and the solids outlet of the housing form part of a conduit which is not in fluid communication with the annular space surrounding the inner tubular element;

wherein the inner tubular element is clamped within the housing via a cylindrical resilient assembly arranged at least one of the first and second open ends of the inner tubular element, the resilient assembly being adapted to allow longitudinal expansion of the inner tubular element and comprising a central through passage having a centre line in line with the centre line of the inner tubular element.

In other words, the elastic assembly is adapted to allow thermal longitudinal expansion of the inner tubular element during use, i.e. expansion of the inner tubular element in a direction parallel to the centre line of the inner tubular element.

In other words, by being clamped via the resilient assembly, the resilient assembly is in at least indirect contact with, i.e. operatively connected to, the first open end and/or the second open end.

The resilient assembly may also be defined to be fluid tight in a radial direction with respect to the conduit and arranged to form a portion of the conduit between the first open end of the inner tubular element and the waste inlet or between the second open end of the inner tubular element and the solids outlet.

The inner tubular element is clamped by a compressive force acting in the longitudinal direction of the tubular element.

The resilient assembly may be arranged to provide a fluid tight connection with the first open end and form part of the conduit. The elastic assembly is arranged to allow/absorb/take up longitudinal expansion of the inner tubular element during use.

In one embodiment of the microwave pyrolysis reactor, a cylindrical elastic assembly is arranged at the first open end of the inner tubular element.

In one embodiment of the microwave pyrolysis reactor, the resilient assembly comprises at least one spring element compressible in a direction parallel to a centerline of the inner tubular element, the spring element having a first end and a second end, and a fluid tight annular wall. Preferably, the fluid tight annular wall extends at least from the first end to the second end of the at least one spring element.

The spring element may comprise a sealing ring arranged at each of the first and second ends. The spring element may comprise a sealing ring arranged at least one of the first end and the second end.

In one embodiment of the microwave pyrolysis reactor, the spring element is cylindrical and comprises a central through-channel having a centre line in line with the centre line of the inner tubular element.

The through-going channel may have a cross-section substantially equal to or larger than the inner cross-section of the inner tube element, i.e. the inner cross-section of the part of the catheter formed by the inner tube element.

In an embodiment of the microwave pyrolysis reactor, the spring element is arranged to provide an evenly distributed force to at least one of the first open end and the second open end of the inner tube element.

In other words, the spring element is arranged to provide a force that is evenly distributed at the first open end and/or the second open end, preferably evenly distributed to an annular surface of each of the first open end and/or the second open end, the annular surface being in a plane perpendicular to the centre line of the inner tube element.

In one embodiment of the microwave pyrolysis reactor, the spring element is made of a suitable metal (e.g., stainless steel).

In one embodiment of the microwave pyrolysis reactor, the spring element is bellows-shaped. Bellows-shaped is used to mean a cylindrical spring element with an integrated fluid-tight annular wall and a through-going passage. Preferably, the spring element is a metal bellows.

In one embodiment of the microwave pyrolysis reactor, each of the first open end and the second open end of the inner tubular element comprises an annular surface arranged in a plane perpendicular to a centerline of the inner tubular element. Preferably, at least an inner annular section of the annular surface overlaps with the transverse cross-section of the inner tube element at a longitudinal location corridor between the first open end and the second open end, i.e. such that a compressive force applied to the inner annular section is supported by the wall of the inner tube element.

In one embodiment of the microwave pyrolysis reactor, each of the first open end and the second open end includes a flared portion, or a flange portion, characterized by an annular surface.

In one embodiment of the microwave pyrolysis reactor, the resilient assembly comprises a protective sleeve arranged inside the at least one spring element, preferably such that the inner volume of the inner tubular element and the conduit/flow path are not in fluid communication with the spring element. The protective sleeve is preferably arranged between the flow path of the conduit and the spring element (or resilient component). The resilient assembly may be defined to include a protective sleeve.

In one embodiment of the microwave pyrolysis reactor, the resilient component forms a portion of the conduit. In other words, the resilient member forms or constitutes a part of the conduit which is not in fluid communication with the annular space. In other words, the spring element, the fluid tight annular wall and/or the protective sleeve form part of the conduit.

In one embodiment of the microwave pyrolysis reactor, the inner tubular element is substantially vertical and arranged such that the first open end is at a higher level than the second open end, such that material entering the waste inlet during use is transported by gravity from the first open end through the inner tubular element to the second open end.

In one embodiment of the microwave pyrolysis reactor, the annular surface of the second open end faces an annular shoulder of the housing (or within the housing) such that the inner tubular element is clamped between the annular shoulder and the resilient assembly. A first sealing ring may be arranged between the annular shoulder and the annular surface of the second open end of the inner tube element to ensure a fluid tight connection.

In one embodiment of the microwave pyrolysis reactor, the resilient member is urged against the annular surface of the first open end. A second sealing ring may be arranged between the annular surface of the first open end of the inner pipe element and the resilient assembly to ensure a fluid tight connection.

In an embodiment of the microwave pyrolysis reactor, the housing comprises a flange element arranged to clamp the resilient assembly between the flange element and the first open end of the inner tube element. A third sealing ring may be arranged between the elastomeric component and the flange element to ensure a fluid tight connection.

In an embodiment of the microwave pyrolysis reactor, the resilient assembly comprises at least one of a second sealing ring or a third sealing ring, preferably arranged at the first end and the second end of the spring element, respectively.

In one embodiment of the microwave pyrolysis reactor, the protective sleeve comprises a flange portion arranged between the flange element and the spring element (or the elastic component), which flange portion may act as a sealing ring to provide a fluid tight connection between the flange element and the spring element.

In one embodiment, the microwave pyrolysis reactor comprises a collar element arranged at the first open end of the inner tube element, the collar comprising an annular recess arranged to receive the lower edge of the protective sleeve.

In one embodiment, the microwave pyrolysis reactor comprises at least one sealing ring arranged between the resilient assembly and either of the first or second open ends of the inner tube element, between the first or second open ends of the inner tube element and the shoulder of the housing, and/or between the resilient assembly and the flange element, the at least one sealing ring preferably being made of metal or ceramic fibres, although sealing rings of other suitable materials may be used.

In one embodiment of the microwave pyrolysis reactor, the gas outlet is in fluid communication with the conduit, i.e. so that gas/volatiles may exit the reactor downstream of the waste inlet.

In one embodiment of the microwave pyrolysis reactor, the gas outlet and the solids outlet are a common outlet arranged downstream of the inner tube element. In other words, the gas outlet and the solids outlet constitute a single outlet arranged downstream of the inner pipe element. In other words, the common or single outlet for gas and solids is arranged on the opposite end of the waste inlet with respect to the inner tube element.

In one embodiment of the microwave pyrolysis reactor, the gas outlet and the solids outlet are separate outlets.

In one embodiment of the microwave pyrolysis reactor, the gas outlet is characterized by a gas outlet tube comprising a first open end arranged within the housing and facing the first open end of the inner tubular element.

In one embodiment of the microwave pyrolysis reactor, the first open end of the gas outlet tube is arranged at or above the level of the first open end of the inner tube element. The first open end of the gas outlet tube is preferably arranged above the level of the first open end. The first open end of the gas outlet tube is preferably at a level above the first open end of the inner tube element such that during use a layer of waste material may be arranged between the first open end of the inner tube element and the first open end of the gas outlet tube. The latter feature allows to further improve the filtration of the gases/volatiles generated during pyrolysis.

In one embodiment of the microwave pyrolysis reactor, a centerline of the inner tubular element intersects the first open end of the gas outlet tube. In other words, the centerline of the inner tube element intersects the horizontal cross-section of the first open end of the gas outlet tube.

In one embodiment of the microwave pyrolysis reactor, the first open end of the gas outlet tube is substantially centered about the centerline of the inner tube element.

In one embodiment of the microwave pyrolysis reactor, a centerline of the inner tubular element intersects a center of the first open end of the gas outlet tube.

In one embodiment of the microwave pyrolysis reactor, the first open end of the gas outlet tube has a smaller cross-sectional area than the first open end of the inner tube element.

In one embodiment of the microwave pyrolysis reactor, the waste inlet is arranged at a level above the first open end of the gas outlet pipe.

In one embodiment of the microwave pyrolysis reactor, the waste inlet is arranged at a level above the first open end of the inner tube element.

In one embodiment of the microwave pyrolysis reactor, the waste inlet is arranged at a level above the first open end of the gas outlet pipe, and the housing comprises a second inner surface defining a circumferential space around the first open end of the gas outlet pipe. The waste inlet is preferably arranged at a level above the circumferential space.

In one embodiment of the microwave pyrolysis reactor, the gas outlet tube comprises an upright tube section featuring a first open end. The circumferential space is disposed around at least a portion of the vertical tube.

In one embodiment of the microwave pyrolysis reactor, the waste inlet communicates with the first open end of the inner tubular element via a circumferential space.

In one embodiment of the microwave pyrolysis reactor, the second inner surface of the housing is part of a vertical inlet pipe having an upper opening and a lower opening, the waste inlet being arranged at the upper opening and the lower opening facing the first open end of the inner pipe element. The gas outlet tube includes a vertical section and a horizontal section, wherein the vertical section includes a first open end and the horizontal section extends through the wall of the vertical inlet tube.

In one embodiment of the microwave pyrolysis reactor, the section of the shell comprising the first inner surface is double-walled, the double-walled section comprising an inner space within which a cooling fluid may be circulated. The reactor includes a cooling fluid inlet and a cooling fluid outlet in fluid communication with the interior space.

In one embodiment, the microwave pyrolysis reactor comprises a cylindrical microwave distribution element arranged around the inner tubular element, the microwave distribution element being made of a microwave-impermeable material and comprising at least one opening for allowing microwaves to pass from the port and into the inner tubular element.

In one embodiment, the microwave pyrolysis reactor comprises an inert gas inlet arranged to provide inert gas into an annular space surrounding the inner tube element during use.

In one embodiment of the microwave pyrolysis reactor, the second open end of the gas outlet pipe may be connected to a gas treatment system comprising a suction device, such that a sub-ambient pressure may be present at the first open end of the gas outlet pipe.

In one embodiment of the microwave pyrolysis reactor, the inert gas inlet may be connected to a source of inert gas such that at least ambient pressure of inert gas may be present in the annular space during use.

In a second aspect, the present invention provides a waste treatment system comprising a microwave pyrolysis reactor according to any embodiment of the first aspect, a microwave source and a gas treatment system; wherein

-the microwave source is connected to the port through a microwave waveguide; and is

The gas treatment system is connected to the gas outlet or the gas outlet tube and comprises a suction device arranged such that during use the pressure at the first open end of the gas outlet tube or at the gas outlet can be kept below ambient pressure.

In one embodiment, the waste treatment system comprises means for providing waste to the inlet of the reactor and means for removing solids exiting the solids outlet of the reactor.

In one embodiment of the waste treatment system, the solids outlet chamber is connected to the solids outlet of the microwave pyrolysis reactor via at least one solids conveyor. The solids conveyor provides a fluid-tight connection between the solids outlet and the solids outlet chamber. The at least one solids conveyor may optionally include a heat exchange system for cooling the solids prior to the solids entering the solids outlet chamber.

In a third aspect, the present invention provides the use of a microwave pyrolysis reactor according to the first aspect, and/or the use of a waste treatment system according to the second aspect, for microwave assisted pyrolysis of any material susceptible to heating by microwaves.

In one embodiment of the first aspect, the microwave pyrolysis reactor comprises a waste inlet assembly in communication with the waste inlet and arranged to provide material to be pyrolyzed in an airtight manner to the first open end of the inner tubular member, and a solids outlet assembly in communication with the solids outlet and arranged to allow material to exit the microwave pyrolysis reactor in an airtight manner. The term "gas-tight manner" means that the material is transferred into and out of the pyrolysis reactor in a manner that prevents ambient gases (i.e. air/oxygen) from being drawn into the inner tube element of the reactor.

In an embodiment of the first aspect, at least one of the waste inlet assembly and the solids outlet assembly comprises a waste inlet chamber and a solids outlet chamber, respectively.

In one embodiment of the first aspect, each of the waste inlet chamber and the solids outlet chamber comprises a first valve and a second valve for isolating the respective chamber. The first and second valves are preferably gate valves, more preferably sliding gate valves.

In one embodiment of the first aspect, each of the waste inlet chamber and the solids outlet chamber comprises a gas inlet and a gas outlet for inert gas purging of the respective chamber.

In an embodiment of the first aspect, the microwave pyrolysis reactor comprises a pressure sensor for monitoring the pressure within the annular space.

In an embodiment of the first aspect, the gas outlet or gas outlet tube may be connected to a gas treatment system comprising a suction device such that during use a sub-ambient pressure is present or may be obtained at the first open end of the gas outlet or gas outlet tube.

In an embodiment of the first aspect, the inert gas inlet may be connected to an inert gas source such that during use at least ambient pressure of inert gas is present or may be present in the annular space.

The port for the microwave waveguide is arranged such that microwaves directed from the microwave source to the port are introduced into the annular space (i.e. the annular space of the first aspect or the first annular space of the fourth aspect).

In one embodiment of the first aspect, the first open end of the gas outlet or gas outlet tube is arranged upstream of the first open end of the inner tube element and downstream of the waste inlet. In the present application, the term "upstream" refers to a position moving through the inner tubular element relative to the waste material to be pyrolyzed.

The waste inlet may be defined as being disposed upstream of the first open end of the inner tubular element, and the solids outlet may be defined as being downstream of the second open end of the inner tubular element.

In one embodiment of the first aspect, the housing comprises a plurality of ports for microwave waveguides.

In one embodiment of the first aspect, the microwave pyrolysis reactor comprises a microwave blocking section arranged between the inner tube element and the port for the microwave waveguide such that microwaves entering through the port during use are prevented from directly impinging on the inner tube element.

The microwave blocking section may be a plate element facing the port for the microwave waveguide and preferably has a cross-sectional area at least equal to the port for the microwave waveguide. Preferably, the plate member has a cross-sectional area greater than the cross-sectional area of the port.

In one embodiment of the first aspect, the waste inlet chamber and the solids outlet chamber are connected to a waste inlet and a solids outlet, respectively, of the housing.

In one embodiment of the first aspect, the microwave pyrolysis reactor is characterized by a microwave distribution element comprising a hollow cylindrical element comprising an outer surface facing the inner surface of the housing, and an inner surface facing the inner tube element.

In an embodiment of the first aspect, the at least one opening of the microwave distributing element is arranged such that microwaves may pass through the at least one opening and into the inner tube element from at least two opposite radial directions of the microwave distributing element during use.

In one embodiment of the first aspect, the at least one opening is arranged such that there are no completely overlapping openings on diametrically opposite sides of the microwave distributing element, preferably such that there is no overlapping of openings on diametrically opposite sides of the microwave distributing element.

In an embodiment of the first aspect, the at least one opening is at least one groove, preferably the at least one groove is shaped as at least a part of a spiral groove arrangement.

In one embodiment of the first aspect, the microwave distribution element comprises a plurality of openings.

In one embodiment of the first aspect, the microwave distributing element is arranged around the inner tube element such that the second annular space is provided between the inner tube element and the microwave distributing element. In other words, in the first aspect of the present invention, the annular space is divided into the first annular space and the second annular space.

The term "waste" is intended to include any type of material suitable for pyrolysis in a microwave pyrolysis reactor.

The term "vertical" as used in connection with the inner tubular element refers to the direction of the centre line of the inner tubular element.

The terms "upstream" and "downstream" are relative to the movement of the waste material stream from the first open end toward the second open end of the inner tubular member.

Drawings

The invention is described in detail by reference to the following drawings:

FIG. 1 is a perspective view of a first exemplary microwave pyrolysis reactor.

Fig. 2 and 3 are side views of the microwave pyrolysis reactor of fig. 1.

Fig. 4 is a cross-sectional view B-B of the microwave pyrolysis reactor of fig. 2.

Fig. 5 is a top view of the microwave pyrolysis reactor of fig. 1.

Fig. 6 is a cross-sectional view a-a of the microwave pyrolysis reactor of fig. 5.

Fig. 7 is a side view of the microwave pyrolysis reactor of fig. 1.

Fig. 8 is a cross-sectional view C-C of the microwave pyrolysis reactor of fig. 7.

Fig. 9 is an exploded side view of the major components of the microwave pyrolysis reactor of fig. 1.

FIG. 10 is a cross-sectional side view of a second exemplary microwave pyrolysis reactor.

Fig. 11 is an enlarged view of detail a in fig. 10.

Fig. 12 is an enlarged view of detail B in fig. 10.

FIG. 13 is a cross-sectional side view of a third exemplary microwave pyrolysis reactor.

FIG. 14 is a perspective view of an exemplary waste treatment system featuring a microwave pyrolysis reactor according to the present invention.

Detailed Description

A first exemplary microwave pyrolysis reactor is shown in fig. 1-9.

The reactor is characterized by an inner tubular element 2 made of a microwave-transparent and fluid-tight material. The pipe element has an upper end 5 (i.e. a first open end) and a lower end 6 (i.e. a second open end), see fig. 9. The outer tube element 3, i.e. the microwave distribution element, is arranged concentrically around the inner tube element 2, thereby defining a first annular space 7 between the inner and outer tube elements, see fig. 4. The housing 4 of the reactor, more particularly the first inner surface of the housing, encloses a second annular space 44 (see fig. 4) surrounding the outer tube element and features a port 13 for connecting the second annular space to a microwave waveguide. The waveguide is used to transmit microwaves from a suitable microwave source, such as a magnetron or solid state generator. The port 13 includes a window (not shown) made of a microwave transparent material. The window allows microwaves to enter the housing while preventing gas from leaving the first annular space 7 and the second annular space 44. The housing 4 features an inlet 10 (or waste inlet), a solids outlet 11, a gas outlet tube 12, and an inert gas inlet 45 (see fig. 4 and 5). The inlet 10 and the solids outlet of the housing are arranged to communicate with the upper end 5 and the lower end 6, respectively, of the inner tubular element 3. The gas outlet tube 12 comprises a first open end 38 (see fig. 6 and 8) arranged within the housing 4 and facing the first open end 5 of the inner tube element, such that gas generated during pyrolysis may escape/leave the reactor. The first open end 38 of the gas outlet tube 12 is arranged above the level of the first open end 5 of the inner tube element 2 and is substantially centered about the centre line C of the inner tube element 2, see fig. 8. The arrangement of the first open end of the gas outlet tube 12 in this manner provides a very advantageous increase and improvement in the interaction between the generated gases and volatiles and the solid waste present in the reactor before allowing the gases/volatiles to exit via the gas outlet tube 12. The disclosed arrangement of the first open end of the gas outlet tube is considered to be the best solution. However, if the centre line C of the inner tubular element intersects the first open end of the gas outlet tube 12, an increased interaction of gas/volatiles and solids is also desired. The disclosed gas outlet arrangement directs gas/volatiles rising through the solid waste in the inner tube element towards the center of the inner tube element, thus increasing the desired interaction between volatiles and solid waste.

A further advantage is obtained by having the first open end of the gas outlet tube 12 at a level above the upper end 5 of the inner tubular element. This arrangement allows a certain amount of non-pyrolytic waste to be present between the upper end of the inner tube element and the first open end of the gas outlet tube. This quantity of non-pyrolytic waste provides increased filtration of the generated gases/volatiles before entering the gas outlet tube and enhances microwave absorption of the non-pyrolytic waste before entering the inner tubular element for pyrolysis.

Increased and improved interaction between solid waste and gas/volatiles is advantageous for at least two reasons; it increases the microwave absorption of the solids as the solids absorb or filter out high boiling volatiles (e.g. tar) and particulates (e.g. char) from the gas/volatiles and additionally provides a more uniform and pure gas/volatiles fraction.

The inlet 10 (i.e. the waste inlet or the solids inlet) of the housing 4 may be part of an assembly or housing section comprising a feed pipe 15 and a gas outlet pipe 12. The feed tube 15 has a first end 16 and a second end 17, and the inlet 10 is arranged at the first end 16 of the feed tube. The second end 17 faces the first open end 5 of the inner tubular element 2 such that a circumferential space 18 is formed between the feed pipe 15 and the vertical section of the gas outlet tube 12 comprising the first open end 38. The feature that the inlet communicates with the upper end 5 of the inner tubular element via the circumferential space 18 is very advantageous, since the circumferential space can act as a waste buffer, ensuring an optimal supply of waste to the inner tubular element.

The inert gas inlet 45, see fig. 4 and 5, is arranged to provide inert gas (typically nitrogen, but may be any other suitable inert gas, such as carbon dioxide, argon, flue gas, etc.) to the first and second annular spaces, i.e. the annular space between the first inner surface of the housing and the inner tube element.

The inner tubular element 2 together with the inlet 10 and the solids outlet 11 of the housing 4 serves as part of a flow path/conduit 37 (see fig. 8) which is not in fluid communication with the annular spaces 7, 44 surrounding the inner tubular element.

The wall of the outer tube element features a plurality of grooves 8 (i.e. openings) arranged in a helical configuration (i.e. a spiral groove arrangement), see fig. 9. During use, microwaves entering the reactor via the port 13 will enter the first annular space 7 between the inner and outer tube elements via the slots. The effect of the outer tubular element is to provide a more even distribution of microwaves which impinge on the waste within the inner tubular element. This in turn provides for more uniform heating of the material.

It should be noted that the microwave distribution element, i.e. the inner tubular element 2, is not essential for the function of the reactor, although providing advantageous effects. In embodiments of the reactor that do not include such microwave distributing elements, the shell defines a single annular space between the inner tube element and the shell (i.e., the inner surface of the shell). Hereinafter, the combined first and second annular spaces are generally referred to as the annular space.

In use, the microwave pyrolysis reactor is arranged with the inner tube element in a vertical direction such that the inlet 10 of the housing and the upper end 5 of the inner tube element are arranged at a level above the solids outlet 11 of the housing and the lower end of the inner tube element. This provides several advantages, including the feature that the waste material to be pyrolyzed passes through the reactor solely by using gravity. Furthermore, during pyrolysis, gaseous and/or volatile products (mainly hydrocarbon gases/vapours) formed in the lower part/level of the inner tube element will rise through the inner tube element and interact with the waste material located at a higher level in the inner tube, i.e. the less volatile components of the gases and the carbon particles directed upwards by the gas flow will be absorbed/adsorbed by the waste material onto this waste material. The gaseous products and the char particles generally have a much higher microwave absorption capacity than the waste material closer to the inlet of the housing, and the resulting effect is therefore an increased microwave absorption in said waste material. The latter effect is very advantageous as it allows for a more efficient pyrolysis of the waste material. This effect may even provide for efficient pyrolysis of the material, which would otherwise require the addition of microwave absorber additives, such as carbon, to achieve efficient pyrolysis. In addition to increasing microwave absorption, the interaction between the gaseous and/or volatile products and the waste material provides for efficient washing/filtration of the gas before exiting via the gas outlet tube 12. As mentioned above, the disclosed arrangement of the first open end 38 of the gas outlet tube 12 provides optimal interaction between the gas/volatiles and the waste material.

As mentioned above, in this particular embodiment, the slots 8 of the microwave distributing element 3 are arranged in a spiral configuration. However, useful or suitable homogenization effects for microwave distribution may be obtained by other slot configurations. Thus, other embodiments are contemplated in which the slots are replaced by openings having various cross-sectional areas (e.g., circular, elliptical, and polygonal). One requirement is that the opening is dimensioned to allow microwaves to pass from the second annular space to the first annular space. Furthermore, the openings are preferably arranged such that the openings do not completely overlap on diametrically opposite sides of the outer tube element. By avoiding such an overlap, a large part of the microwaves is reflected and distributed in the first annular space in the longitudinal direction of the inner pipe element.

The microwave pyrolysis reactor includes a plurality of temperature sensors 42 and pressure sensors 43. The sensors themselves are not shown and in the drawings, reference numeral 42/43 is used to identify the sensor mounts/ports for the various sensors. The sensors monitor temperature conditions in the reactor and the pressure in the first annular space 7 and the second annular space 44 (i.e. the pressure in the annular space between the inner tube element and the first inner surface of the housing). When used in a waste treatment system, such as described below, the various sensors are connected to a suitable control and monitoring system (not shown).

The outer tube element 3 (i.e. the microwave distribution element) of the disclosed reactor comprises a first heat exchange system for removing heat from within the microwave pyrolysis reactor during use. The first heat exchange system is not necessary for the functional reactor, but provides several advantageous effects. The heat exchange system is characterized by a spiral-shaped fluid channel 41 arranged in the wall of the outer tube element 3 (i.e. the fluid channel is arranged between the outer surface and the inner surface of the microwave distributing element). The fluid channels are connected to a fluid inlet 39 and a fluid outlet 40 for a heat exchange fluid. By having the fluid channel as an integral part of the spiral design, the heat capacity of the heat exchange system can be increased without damaging the spiral slot arrangement, which provides a very good microwave distribution. However, the same advantages can be obtained when used in microwave distribution elements having other suitable arrangements of slots and/or openings. This feature is very advantageous when the reactor is used in an environment where the temperature of the shell is not allowed to exceed a certain temperature limit. In addition, having a heat exchange system for removing heat from within the pyrolysis reactor provides further advantages in that excess heat from the reactor may be used in various auxiliary systems, such as in the preheating of water, power generation, and the like. By arranging the heat exchange system in heat conducting contact with the outer tube element 3, the outer tube element serves as a heat conducting element of the heat exchanger. That is, the outer tube element functions in a manner similar to the heat transfer fins/baffles/plates used in known heat transfer systems. In addition, the outer tube element is arranged close to the inner tube element, heat is generated within the inner tube element, and an optimal temperature difference/gradient and heat transfer are obtained. Having a heat exchange system for removing heat from within the microwave pyrolysis reactor at a location proximate to the inner tube element, depending on the desired pyrolysis conditions, such as temperature, may provide the advantage that differences in thermal expansion of the inner tube element and the shell are minimized. These differences may additionally lead to material stresses on the inner tube element, leaks between the inner tube element and its connection to the housing, etc. See the solution in the following exemplary reactor, which minimizes potential problems caused by thermal expansion.

The reactor comprises a second heat exchange system to further increase the energy recovery during pyrolysis and to obtain a further reduction of the external temperature of the shell 4. The second heat exchange system is arranged in a casing section surrounding the annular space 7, 44. The casing sections are double walled to provide an inner annular space 50. The annular space 50 is connected to an inlet 51 and an outlet 52 for cooling fluid, so that cooling fluid (e.g. water) can circulate through the annular space.

A second exemplary microwave pyrolysis reactor is shown in fig. 10-12. During testing of the above reactor by referring to fig. 1 to 9, it was found that clamping/fastening of the inner tubular element within the shell requires a very precise application of force to avoid premature deterioration of the inner tubular element 2, while ensuring a fluid tight connection without potential thermal expansion/contraction of the reactor shell. This requirement is not ideal as small errors when clamping/tightening the inner tube element may result in a shortened operational life of the inner tube element and shorter maintenance intervals. Premature degradation of the inner tubular element may be caused by unevenly applied compressive forces, excessive compressive forces, an increase in compressive forces due to longitudinal expansion of the inner tubular element caused by the high temperatures of the pyrolysis process, and/or a combination of these factors.

In order to increase the operational lifetime of the inner tubular element, the second exemplary microwave pyrolysis reactor shown in fig. 10 to 12 provides a solution for clamping the inner tubular element within the housing, which avoids at least some of the above-mentioned factors. The reactor is similar to that of figures 1 to 9 and similar or identical features are identified by the same reference numerals.

In view of the reactor of fig. 1 to 9, the reactor of fig. 10 is mainly distinguished by the presence of an elastic assembly comprising a metal bellows 54 (i.e. a spring element) arranged at the first open end 5 of the inner tubular element 2. The inner tube element features flared portions 60, 61 arranged at the first and second open ends 5, 6, respectively. Each flared portion features an annular surface 58, 59 arranged in a plane perpendicular to the centerline of the inner tube element. Via the annular surfaces 58, 59, the inner pipe element 2 is clamped within the housing between the metal bellows 54 (see fig. 11) and a shoulder 63 arranged at the second open end 6 of the inner pipe element 2.

The metal bellows 54 is compressible in a direction parallel to the centerline C of the inner tubular member and has a first end 55, a second end 56 and a central through passage 68 having a centerline aligned with the centerline C of the inner tubular member. By clamping the inner tubular element via the metal bellows (i.e. the elastic assembly), an even distribution of the compression/clamping force applied to the annular wall of the tube is more easily obtained. Furthermore, longitudinal thermal expansion of the inner tubular element that occurs during use is absorbed by the metal bellows, the increase in compression/clamping forces caused by expansion is mitigated, and potential degradation of the tubular element is minimized. It should also be noted that the use of a resilient assembly to clamp the inner tubular element is advantageous in preventing leakage from the conduit/flow path 37, as the resilient clamping ensures optimum contact between the annular surfaces and shoulders of the inner tubular element and the metal bellows. Various sealing rings 69, 70, 71 are used to ensure a fluid tight connection between the inner tubular element 2, the metal bellows 54 and the housing. The sealing rings 69, 70 in contact with the metal bellows may be different sealing rings or alternatively form an integral part of the metal bellows.

To prevent solids and tars from accumulating on the inner surface of the metal bellows, the reactor (or elastomeric assembly) has a protective sleeve 62 disposed between the inner surface of the metal bellows and the flow path/conduit 37. The protective sleeve is mounted in a recess 67 of the collar 56 arranged at the first open end 5 of the inner pipe element and features a flange portion 65 clamped between the first end 55 of the metal bellows and the flange element 64. Preferably, the protective sleeve 62 is made of an elastic material so that the sleeve does not contribute a significant compressive force to the first open end 5 of the inner tubular member.

The metal bellows 54 is arranged towards the annular surface 58 of the inner tubular element 2 by means of a bolted flange element 64. In this embodiment, the flange element 64 is a lower portion of the feed tube 15.

A third exemplary microwave pyrolysis reactor is shown in fig. 13. The reactor comprises the same elastic assembly featuring a metal bellows 54 as described above, and an inert gas inlet (not shown) connected to the annular space between the inner surface of the shell and the inner tubular element 2. In view of the second exemplary reactor, the reactor in fig. 13 is distinguished in that the separate gas outlet 12, the outer tube element 3 and the second heat exchange system are eliminated. The gas outlet 12 and the solids outlet 11 of the third exemplary reactor are a common gas outlet 12 and solids outlet 11 arranged downstream of the inner pipe element 2.

In the disclosed embodiment, the resilient assembly features a single metal bellows to provide the desired resilient grip of the inner tubular element. In this embodiment, the metal bellows is obtained by rotating a steel tube to obtain the desired bellows shape. Metal bellows suitable for the present invention may also be obtained by any suitable method, such as welding and hydroforming, and are commercially available from a number of sources (e.g., Comvac AG and Kompaflex AG). An advantage of using a metal bellows is that it provides a spring element with an integral fluid-tight annular wall or surface, thereby providing enhanced security against leakage/leakage from/into the conduit/flow path 37. However, based on the present disclosure, other solutions for a suitable elastic assembly featuring a fluid-tight annular wall will be readily apparent to the skilled person. Alternative assemblies may, for example, include multiple annularly arranged spring elements (or a single annular spring) featuring a fluid-tight compressible sleeve, multiple spring elements (or a single annular spring) arranged in a compressible cylindrical fluid-tight housing, or the like.

In the disclosed embodiment, the inner tube element 2 of the exemplary pyrolysis reactor is arranged in a vertical direction due to the specific solution for the waste inlet 10 and the gas outlet 12 and/or the ability to transport waste through the inner tube element by gravity. However, the solution of the invention for clamping the inner tube element by using the elastic assembly is also applicable to further embodiments of the microwave pyrolysis reactor, irrespective of whether the inner tube element is vertical, horizontal or inclined, as long as the waste inlet and the gas/solid outlet are arranged such that waste can be introduced into the inner tube element and the gas/solid outlet is arranged such that gas/solid generated in the pyrolysis process is allowed to leave the inner tube element. In the case of a horizontal inner tube element, the waste may be conveyed through the inner tube element, for example by any suitable conveying system (e.g. a screw). Various suitable solutions for conveying waste through a microwave pyrolysis reactor are known in the art.

The main units/elements of an exemplary waste treatment system (or waste disposal or processing system) are shown in fig. 13, featuring a microwave pyrolysis reactor 1 similar to the microwave pyrolysis reactor described above. The reactor 1 in fig. 13 differs from the reactor shown in fig. 1 to 12 in that the shell 4 and the outer tube element 3 do not feature a heat exchange system.

In addition to the microwave pyrolysis reactor 1, the system comprises a waste container 19, a waste inlet chamber 20, a solids conveyor 21 and a solids outlet chamber 22. The waste container comprises a waste outlet 33 and has a screw conveyor 23 (screw not shown, only motor connected to the screw) arranged to provide waste material to the inlet 24 of the waste inlet chamber. The waste inlet chamber includes an upper valve 25 (i.e., an inlet valve) and a lower valve 26 (i.e., an outlet valve). Both the upper and lower valves are gate valves, but other suitable types of valves may be used. During the pyrolysis process, the internal volume of the inner tube element is maintained at a pressure below ambient pressure, as described below. The valve is capable of isolating the waste inlet chamber so that air/oxygen is prevented from being sucked into the reactor (i.e. into the inner tubular element 2) during feeding of the waste material. In this particular embodiment, oxygen may be purged from the waste material by using nitrogen (i.e., an inert gas) before the waste material enters the microwave pyrolysis reactor 1. Nitrogen is supplied via gas inlet 27 and released via gas outlet 28. However, while a nitrogen purge may be advantageous, this is not necessary because the amount of oxygen present in the isolated waste inlet chamber is small. The solids conveyor 21 is connected to the solids outlet of the microwave pyrolysis reactor and comprises a closed internal screw conveyor 34 (not shown). The screw conveyor 34 is arranged to convey solids exiting the microwave pyrolysis reactor to the solids outlet chamber 22. Other means for conveying solids in a solids conveyor, such as belts, may also be used.

The solids conveyor is sized (i.e., has a length and/or circumference) such that solids exiting the microwave pyrolysis reactor are allowed to cool sufficiently before they reach the solids outlet chamber. It is envisaged that the solids conveyor may comprise a heat exchange system for improving the cooling of the solids exiting the solids outlet 10. In addition to improving the cooling of the solids, such heat exchange systems may also be used, for example, to utilize heat in various auxiliary systems, such as preheating of water.

The solids conveyor includes a temperature probe to monitor the temperature of the solids during transport from the solids outlet 11 to the solids outlet chamber 22, the solids outlet chamber 22 including an upper valve 29 (i.e. inlet valve) and a lower valve 30 (i.e. outlet valve). The valve can isolate the solids outlet chamber so that oxygen or air is prevented from being drawn into the solids conveyor (and thus into the inner tubular member of the microwave pyrolysis reactor). Similar to the waste inlet chamber, any oxygen in the solids outlet chamber may be purged through the gas inlet 31 and gas outlet 32 (not shown) using nitrogen, but this is not required. The solids outlet 35 of the solids outlet chamber is typically connected to a solids vessel 36 (not shown) for temporary storage of solids.

In other embodiments, the inlet chamber 20 and the outlet chamber 22 may be arranged in other locations, for example with the outlet chamber arranged upstream of the solids conveyor, the inlet chamber arranged upstream of the waste container, etc., as long as the inlet and outlet chambers are capable of preventing oxygen or air from being sucked into the inner tubular element 2 and the flow path/conduit 37 during the entire pyrolysis process including the steps of feeding waste material and emptying solids. Although it is believed that the most effective and robust solution for providing an isolatable/airtight inlet/outlet assembly is provided, the inlet/outlet chamber may alternatively be replaced by any suitable inlet/outlet assembly capable of supplying waste material into the reactor (or solids out of the reactor) without allowing air to be drawn in due to sub-ambient pressure in the inner conduit element. Such alternative assemblies are disclosed in, for example, CN103923673A and WO 2013/077748a1, and are incorporated herein by reference.

The gas outlet tube 12 of the microwave pyrolysis reactor (or the second open end 53 of the gas outlet tube 12) is connected to a gas treatment system 47 for treating and/or storing gaseous/volatile products formed in the reactor. The gas treatment system includes at least one suction device 48 (i.e., gas fan/compressor/pump). The suction device 48 provides a sub-ambient pressure at the first open end 38 of the gas outlet tube 12. Thus, most or all of the internal volume of the inner tubular element, as well as the internal volume of the reactor in direct fluid communication with the inner tubular element, is also maintained below ambient pressure during use. This sub-ambient pressure provides for efficient transport of the gaseous products from the microwave pyrolysis reactor and ensures an optimal flow pattern of the gaseous products through the waste material due to the positioning of the first open end 38 of the gas outlet tube 12, as described above. The pressure at the first open end 38 may be maintained at, for example, about 5-15mbar below ambient pressure. It should be noted that in some cases the pressure in the lowermost part of the inner tube element may reach above ambient pressure due to the formed gaseous products and the increased flow resistance of these products encountering the first open end 38 of the gas outlet tube 12. However, this will not have an impact on the advantages of the reactor and system discussed below.

The sub-ambient pressure provided by the suction device 48 ensures that the loss of mechanical/structural integrity of the inner tube element 2 or any sealing element separating the inner volume of the inner tube from its surroundings (i.e. the annular spaces 7, 44) can be easily detected by monitoring the pressure within the annular space using the pressure sensor 43. The loss of mechanical/structural integrity may be due to, for example, a crack or a faulty seal in the inner tubular element. The pressure sensor 43 communicates with the control system so that the waste treatment system is shut down before any further damage can occur. The ability to effectively detect loss of mechanical integrity and stop the pyrolysis process is important because air/oxygen drawn into the reactor can cause explosive reactions with gaseous products.

To eliminate any remaining risk of air/oxygen mixing with the gaseous products during loss of mechanical/structural integrity, the annular space is filled with inert gas from inert gas source 46 via inert gas inlet 45. The inert gas (typically nitrogen, but any suitable type of inert gas may be used) in the annular space is maintained at (or above) a minimum ambient pressure, which is monitored by a pressure sensor 43. The pressure of the inert gas may for example be maintained at about 5-15mbar above ambient pressure. The pressure ap in the annular space and at the first open end 38 of the gas outlet tube 12 may for example be in the range of 10-30 mbar. If the mechanical integrity is lost as described above, only inert gas will be drawn into the inner tubular member or flow path/conduit 37. The inert gas source 46 will provide inert gas to the annular space until the pyrolysis process is safely stopped.

In addition to the extraction device 48, the gas treatment system 47 may include any suitable device or system for condensing/separating at least a portion of the gaseous products into condensate and gas, a storage system for gas and condensate, a system for generating heat and/or electricity, such as a gas-driven generator or oil furnace. In one embodiment, the inert gas source 46 may be connected to one of the systems for generating heat and/or electricity, such that the flue gas may be used as an inert gas.

In use, waste is first provided to the waste container 19. The waste container may for example be connected to or form part of a shredder, granulator and/or waste storage hopper, to provide waste material in a form suitable for introduction into the reactor. In the feeding sequence, waste material, preferably granular waste material, is conveyed to the outlet 33 of the waste container, the upper valve 25 of the waste inlet chamber is opened and waste material is introduced into the waste inlet chamber. After introduction, the upper valve 25 is closed and the waste inlet chamber 20 is purged, optionally by nitrogen (or any suitable inert gas) via a gas inlet 27 and a gas outlet 28. Subsequently, the lower valve 26 is opened and the waste material is allowed to enter the microwave pyrolysis reactor via the upper inlet 10 due to gravity. The lower valve 26 is closed and the waste material is pyrolysed by using microwaves from a microwave waveguide 14 (shown schematically) connecting a microwave source to the port 13.

A level sensor (not shown) disposed in the reactor detects when a suitably low level of waste material is reached and repeats the above-described feeding sequence to provide a new batch of waste material to the reactor. Initially, the waste material in the inner tubular element 2 is at the same level of pyrolysis throughout the inner tubular element, however, after a certain time of introduction of repeated batches of material, the material closest to the solid outlet 11 is completely pyrolyzed, i.e. mainly char, whereas the material closest to the inlet 10 is not.

Upon entering the microwave pyrolysis reactor through port 13, the microwaves enter the annular space 7 and the inner tube element via the slots 8 and are distributed within the inner tube element 2. During pyrolysis, the waste material is converted primarily to solid and gaseous/volatile materials, with the solid being composed primarily of carbon and the gaseous material being composed primarily of hydrocarbon gases/vapors. Typically, pyrolysis is carried out at a temperature in the range of 300-600 ℃. The hydrocarbon gas/vapour is allowed to leave the reactor via the gas outlet pipe 12. When pyrolysis of at least the lower portion of the waste material (i.e., the portion closest to the solids outlet 11 of the reactor) is complete, the solids conveyor 21 moves the solids to the solids outlet chamber 22. An advantage of having the inner tube element arranged in a vertical direction is that any hydrocarbon gas/vapour generated in the process will pass through the waste material between the location of gas generation and the first open end 38 of the gas outlet tube 12.

When the solids outlet chamber 22 is full, the upper valve 29 is closed and the lower valve is opened so that solids can exit the solids outlet chamber. After the solids exit, the lower valve 30 is closed, the solids outlet chamber is optionally purged of oxygen, and the upper valve 29 is opened to receive a new batch of solids. Typically, the solids outlet chamber is connected to a solids vessel for intermediate storage of solids.

Both the waste inlet chamber and the solids outlet chamber may optionally comprise means for venting gas/air out of the chambers, for example a gas valve connected to a suction means. By combining a nitrogen purge with a prior evacuation of the chamber, the amount of nitrogen required can be reduced. In further embodiments, the waste inlet chamber and/or the solids outlet chamber do not include any features for purging or evacuating air, as the amount of oxygen that can enter the reactor via the inlet/outlet chamber is not sufficient to cause any adverse effects.

In an alternative embodiment, the waste treatment system comprises a reactor 1 as disclosed in fig. 1 to 9 or 10 to 12, and the first and second heat exchange systems of the reactor 1 are connected to any suitable auxiliary system to utilize the heat recovered from the pyrolysis process. The recovered heat may be used, for example, for preheating of water, power generation, pre-drying of waste materials, etc. In addition to the first and second heat exchange systems, this embodiment may also include a third heat exchange system connected to the solids conveyor 21 as described above.

In yet another embodiment, the waste treatment system may comprise a reactor 1 as disclosed in fig. 13. In such an embodiment, the gas treatment system 47 may, for example, be connected to a gas outlet in the solids conveyor 21.

Suitable microwave-transparent materials for the inner tubular member 1 include glass materials, such as borosilicate or quartz, and various ceramics with low dielectric loss, such as boron nitride-based ceramics.

The use of microwaves for heating the material to be pyrolyzed makes it preferable that the material should have certain inherent properties, i.e. a high energy with an electric dipole and absorption of microwaves having a wavelength λ of 12cm to 32 cm. In many cases, the waste material will be highly heterogeneous and not all will have the characteristics required for effective microwave heating. In the latter case, it may be desirable or advantageous to mix the waste material with auxiliary materials prior to introduction into the microwave pyrolysis reactor, despite the advantageous effects of the vertical inner tube element as described above. Such auxiliary material may be, for example, char previously produced in a microwave pyrolysis reactor. However, even if such auxiliary material is needed, the vertical inner tube element and its advantageous effects will minimize the amount of such material.

The disclosed microwave pyrolysis reactor is primarily described by its use in the treatment of waste materials, where the products obtained, such as char, oil and tar, are not the primary target of the pyrolysis process. However, the products obtained and the thermal energy generated in the process are valuable and it is envisaged that the reactor and waste treatment system may be used in processes where the products obtained and/or the thermal energy generated are the primary targets. Such a process may be, for example, the production of biofuels by pyrolysis of wood-based raw materials, the production of energy, etc. Thus, the term waste treatment system is also intended to cover systems such as biofuels and power plants.