A feedstock delivery device for continuous feeding of a feedstock to a pyrolysis reactor

Abstract

The invention provides a feedstock delivery apparatus (10) which enables a continuous supply of polymeric waste to a pyrolysis reactor (14). It features a mobile body (16) with a supply tube (18), a one-way flapper valve (24), and a piston (26) for controlled feedstock transfer. The sealing assembly ensures an airtight connection at the reactor port, accommodating reactor rotation while preventing leakage. The apparatus compresses feedstock into plugs, expelling air before entering the reactor. A flapper valve maintains back pressure during operation, while sealed nozzles in the reactor allow for steam or solvent interaction. The vehicle platform enables easy maintenance disconnection.

Description

A FEEDSTOCK DELIVERY DEVICE FOR CONTINUOUS FEEDING OF AFEEDSTOCK TO A PYROLYSIS REACTORFIELD OF THE INVENTION

[0001] This invention generally relates to an apparatus that provides a feedstock's continuous supply to a pyrolysis reactor.BACKGROUND OF THE INVENTION

[0002] Depolymerisation, specifically pyrolysis in a broader sense, involves breaking down long-chain molecules by applying heat in an environment devoid of oxygen. A significant challenge in this process revolves around establishing and maintaining a consistently sealed, controlled, oxygen-free environment within the reactor or liquefier (hereinafter referred to as a “reactor”). Achieving this requires precise control over multiple input and output ports and seals, mainly when dealing with fluctuating feedstock sizes and shapes.

[0003] Addressing the issue of oxygen infiltration during pyrolysis is a complex endeavour. The entry of oxygen can trigger oxidation within the pyrolysis process, leading to undesirable side reactions that degrade the efficiency of the depolymerization and adversely impact the quality of the end products. In particular, oxidation can reduce the yield of valuable hydrocarbons and lead to the formation of unwanted by-products. Additionally, the presence of oxygen poses a significant safety risk, particularly concerning the potential for fires and explosions, as pyrolysis operates at high temperatures. Controlling air presence in the context of solid materials undergoing rotary manipulation has proven to be exceptionally challenging. Various methods have been attempted, albeit with limited success.

[0004] This predicament is further compounded when dealing with feedstock composed of irregularly shaped solids, which is often the case. Due to this irregularity, maintaining an airtight seal between these objects and the input channel or chute becomes especially problematic, resulting in air ingress into the reactor. Moreover, irregular solids tend to cause clogging or uneven flow within the reactor system, creating further difficulties in maintaining consistent thermal and operational conditions, resulting in process instability.

[0005] Numerous strategies have been employed to feed solids into pyrolysis while continuously minimising air ingress. A common approach involves the use of a screw conveyor, while other solutions utilise airlocks. However, these methods are not entirely successful, and oxygen still infiltrates the process. Consequently, nitrogen is typically employed as a purging medium to mitigate the effects of oxygen ingress. This method, though commonly used, is costly and inefficient in larger operations, especially when nitrogen consumption is high. The need for continuous purging also increases operational complexity and maintenance costs.

[0006] The limitations of the currently employed solutions include the need to preprocess the solid feedstock through shredding or pelletising to achieve a uniform particle size distribution. Preprocessing adds significant operational costs, energy consumption, and equipment wear. Additionally, there is a risk of reverse flow from the process (especially if operated above atmospheric pressure) through the loading device. Furthermore, using nitrogen as a purge medium, while inert, reduces the calorific value of the gas produced in the pyrolysis process, making it challenging to combust in a furnace or effectively use as fuel gas for power generation. This results in a lower overall energy efficiency and limits the commercial viability of the end products.

[0007] The present invention at least partially addresses the problem.SUMMARY OF INVENTION

[0008] The invention provides a feedstock delivery apparatus for the continuous feeding of a feedstock to a pyrolysis reactor, the device including: a body, a tube, either engaged to or integral with the body, extending between a first end and a second (outlet) end, with the second end adapted for insertion into a port in the pyrolysis furnace, a one-way valve positioned at the second end, a piston engaged with the tube and adapted to move reciprocally between a retracted position and a forward position within the tube, a feed hopper in communication with the tube, adapted to contain a feedstock and to feed the contained feedstock into the tube, wherein, upon receipt of the feedstock in the tube, the piston is actuatable to move from the retracted position to the forward position, compressing the feedstock into a plug against a series of previously compressed plugs and expelling a leading plug of the series past the one-way valve, into the furnace.

[0009] The feedstock delivery apparatus may include a sealing assembly engaged with the tube, adapted to provide a seal between the tube and the port.

[0010] The sealing assembly may include a rotator component, adapted to engage the pyrolysis reactor around the port, and a stator flange attached to the tube, adapted to seal against the rotator.

[0011] The rotator component may consist of a first flange and a second flange, which sandwich the stationary flange in the sealing assembly to form a seal, with the first flange attaching to both the second flange and the pyrolysis reactor.

[0012] The stator flange may include at least one circumscribing groove on the first face and at least one circumscribing groove on the second face, each groove adapted to receive a complementary sealing means to form a seal against the first flange and the second flange, respectively.

[0013] The sealing assembly may include a divider that engages the first and second flanges around the outer circumferential region to evenly axially space the first flange from the second flange when attached.

[0014] The divider may include a plurality of evenly radially spaced stubs.

[0015] The assembly may include a plurality of rubbing spacers that engage both the first and second faces of the stator flange, spacing the first flange away from the first face when the stator flange moves toward the first flange and spacing the second flange away from the second face when the stator flange moves toward the second flange.

[0016] The rubbing spacers may be made of non-stick material, such as PTFE, or a material with low mechanical resistance.

[0017] The body may be a mobile body. The mobile body may be mounted on wheels or tracks to enable the body to move towards or away from the pyrolysis reactor. The mobile unit may be self-propelled or moved by an external drive system.

[0018] The tube may be either cylindrical or a box-shaped tube.

[0019] The tube may taper inwardly from the first end toward the second end.

[0020] The valve may be a flapper valve.BRIEF DESCRIPTION OF THE DRAWING

[0021] The invention is further described by way of an example with reference to the accompanying drawings wherein:Figure 1 provides an elevation schematic of a feedstock delivery apparatus for continuous feeding of a pyrolysis reactor with the piston shown in its retracted position,Figure 2 shows a plan view schematic of the feedstock delivery apparatus depicted in Figure 1 ,Figure 3 illustrates the apparatus in elevation with the piston in its forward position,Figure 4 shows a longitudinally sectioned schematic of the apparatus, showing a series of feedstock plugs inside a tube,Figure 5 illustrates an isometric view of the feedstock delivery,Figure 6 depicts an elevation view of the apparatus, as shown in Figure 5,Figure 7 displays an elevation view of the sealing assembly within the feedstock delivery apparatus,Figure 8 illustrates a sectional view of a portion of the feeder tube, with the sealing apparatus engaged,Figure 9 is a sectioned view of part of the sealing apparatus,Figure 10 depicts an exploded isometric view of the sealing apparatus and the feeder tube it engages, andFigures 1 1 A and 11 B show sectioned views of the sealing apparatus, illustrating two configurations of the sealing flanges.DESCRIPTION OF PREFERRED EMBODIMENTS

[0022] Figure 1 illustrates a feedstock delivery apparatus 10, which provides a continuous supply of feedstock 12 to a pyrolysis reactor 14 (illustrated in dotted outline).

[0023] The apparatus 10 includes a mobile body 16, a feeder tube 18, either engaged to or integral with the body, extending between a first end 20 and a second or outlet end 22, a one-way flapper valve 24 positioned at the second end, a piston 26 engaged with the tube, and a feed hooper 28 in communication with the tube, adapted to contain the feedstock 12 and to feed the contained feedstock into the tube.

[0024] The mobile body is mounted on a vehicular platform 30, which, in this exemplary embodiment, is supported by a tracked propulsion system. The platform is equipped with continuous tracks, also known as caterpillar tracks 32 or treads, which provide stability and manoeuvrability. The apparatus 10 can be disconnected from the platform and removed for maintenance.

[0025] It is envisioned within the scope of the invention that the mobile body may be moved by any suitable means, whether self-propelled or moved via winching.

[0026] The supply tube 18 extends beyond the vehicular platform 30 of the body as a leading end section 34. This leading end section is adapted to penetrate a port 36 in a wall of the pyrolysis reactor 14.

[0027] The feedstock delivery apparatus 10 includes a sealing assembly 38 engaged with the tube, adapted to provide a seal between the tube and the port to establish and maintain a sealed connection and prevent oxygen ingress to the reactor. The difficulty arises because the reactor rotates, yet the apparatus must avoid rotationalmovement. The sealing assembly is, therefore, adapted to withstand this dynamic interaction, ensuring the reactor's rotation doesn’t break the airtight seal.

[0028] The sealing assembly 38 includes a first apertured flange 40 and a second apertured flange 42 comprising the rotator component of the assembly and a stator flange 44 or sealing ring (these terms are used interchangeably), attached to the tube, adapted to seal against the rotator. These components are best illustrated in Figure 10.

[0029] The sealing ring 44 is securely welded to tube 18 and reinforced by gussets 46. These gussets extend from both faces (48.1 , 48.2) of the stator flange and connect to the tube, providing additional structural support and stability.

[0030] The sealing ring 44 features two concentric grooves (50.1 , 50.2) on its first face, 48.1 and two more grooves (52.1 , 52.2) on its second face, 48.2 (see Figures 1 1 A and 1 1 B). Each groove is designed to accommodate a complementary sealing element 54 (together referred to as a gland), ensuring a secure fit. The sealing elements are made of a non-stick material, such as PTFE.

[0031] The first flange 40 and a second flange 42 (reactor-facing flange) sandwich the sealing ring 44 in the sealing assembly to form a seal by engaging the sealing means provided in the respective grooves on the first face and second face of the sealing ring. The first flange is then attached to the second flange and the pyrolysis reactor. The advantage of this dual-groove design is that if leakage occurs past the initial seal surrounding the first gland on either face, the subsequent seal around the second gland on each face will effectively prevent further leakage.

[0032] The first and second flanges (40, 42) each have a series of bolt holes 56 arranged in a circular pattern along their outer edges. Associated with these bolt holesare stubs 58, which function like washers and are installed with the bolts. Each stub is positioned between the flanges, with the bolt passing through it. The bolts are tightened to secure the assembly. The stubs are separate and uniform in size, and when inserted between the flanges, they maintain the spacing between the flange faces. The flanges compress the stubs as the bolts are tightened, ensuring a tight assembly.

[0033] The sealing assembly 38 features multiple rubbing spacers 60 attached to the sealing ring 44. However, in Figures 1 1 A and 1 1 B, only one spacer, 60.1 , is shown extending from the first face, 48.1 , while another spacer, 60.2, is illustrated protruding from the second face, 48.2. These rubbing spacers are also made from a non-stick material such as PTFE.

[0034] To connect the sealing assembly 38 (and therefore the apparatus 10) to reactor 14, a gasket (not shown) is positioned against the reactor port flange (not shown), which surrounds reactor port 36. With the first apertured flange 40 already attached to the tube, which passes through aperture 64 of this flange, the tube can then be guided through aperture 66 of the second apertured flange 42 until it contacts the sealing ring 44. The tube is inserted into the port with the second end 18 leading, continuing until the second flange meets the reactor port flange. The bolt holes 56 of the first and second flanges can be aligned by rotating the flanges in relation to each other and to the bolt hole in the reactor port flange. Once aligned, bolts 70 (for ease of illustration, only one is shown in Figure 10) can be inserted through the corresponding holes and the associated stubs to secure the outer perimeter of the first and second flanges to each other and then secured within threaded holes on the reactor port flange.

[0035] The spacing stubs 58 function similarly to washers. They are thinner than the distance across the sealing ring from one sealing element to another, allowing forproper compression of the sealing elements when the first and second flanges (40, 42) engage and sandwich the sealing ring 44. Without these stubs, tightening the bolts could lead to the two flanges coming together too forcefully, potentially breaking the bolts or warping the edges of the flanges. Additionally, the stubs facilitate uniform tightening and torquing of the bolts, which is essential for maintaining the integrity of the seal between the first and second flanges and the interposed sealing ring. If the bolts are not tightened uniformly, areas with less tension may be prone to leakage. In contrast, sections with excessive tension may experience friction during rotation, leading to increased wear on the gland and putting additional load on the motor required to rotate the reactor.

[0036] The rubbing spacers 60 prevent metal-on-metal contact if the sealing ring 44 does not move horizontally in sync with the adjacent flanges (40, 42). This misalignment can occur if the vehicular platform 30 fails to move fully or becomes stuck while approaching reactor 14 after the flanges have been bolted to the reactor. In such cases, the flanges may shift axially in relation to the sealing flange, bringing either the first or second face (48.1 , 48.2) closer to one of the flanges, depending on the direction of movement.

[0037] If the sealing ring and flange come into contact, there is a risk that the sealing ring — and consequently the entire apparatus 10 — may rotate with the reactor during operation. This could cause the motor responsible for rotating the reactor to trip, burn out, or damage the gearbox. The PTFE rubbing spacers effectively prevent this issue by allowing the respective flange to contact the spacer, enabling it to slide with minimal friction while avoiding direct contact with the sealing ring.

[0038] Lastly, the sealing assembly 38 includes several sealed nozzles 62, which allow the introduction or removal of fluid streams from reactor 14, such as steam or solvents and facilitate the insertion of instrumentation or other auxiliaries.

[0039] The feed hopper 28 is filled with feedstock consisting of irregularly shaped polymeric waste solids, including various plastic fragments and chunks. The hopper's design accommodates these inconsistencies, with a wide opening and angled walls to ensure smooth material flow into the processing system, minimising the risk of clogging. The polymeric feedstock may include different plastics, such as polyethene, polypropylene, or polystyrene.

[0040] Feedstock is released from the feed hopper in a controlled manner_28, through an open section 72 of the tube, to fill a void 74 (a loading section) between the head of the piston, in its fully retracted position, and a trailing face of a previous batch of now compressed feedstock 76.2 (hereinafter referred to as a plug).

[0041] With void 74 filled with a measured amount of feedstock, a hydraulic actuator 78 is energised to move the piston from the retracted position, as illustrated in Figure 1 , to a forward position, as illustrated in Figures 3 or 4. This piston movement compresses the feedstock into a plug (76.1 ) against plug 76.2.

[0042] Plug 76.2 is resistive to this force as it is backed up against a series of plugs (76.3, 76.4, 76. N) within a compression section 80 of the tube, sequentially compressed during prior compressive cycles in the operation of the device 10. However, adding the freshly compressed plug 76.1 to the series causes the expulsion of a leading plug in series 76. N from the tube into the furnace, as shown in Figure 4, past the one-way valve 24. This plug drops into the reactor chamber to undergo pyrolysis.

[0043] To push past the one-way valve, plug 76. N must overcome the back pressure created by the weight of the flapper valve biasing the valve into the closed position and the higher than atmospheric pressure in the reactor, which will force the flapper valve to be closed.

[0044] This compression cycle can be repeated, with the piston actuated to retract back to its retracted position, opening void 74 once again to be filled with a fresh batch of the feedstock.

[0045] The air within and between the feedstock components is effectively expelled during the compression process. This compression action does not cease at the piston; it continues along the length of the compression section 80, with the plug pushing against the walls in the compression section and the plug ahead. Compression occurs between each successive plug within the series, progressively driving out the air. Notably, the air flows in the direction of decreasing density (i.e., towards the first end 20 of the tube), away from the reactor (i.e., away from the direction of increasing density).

[0046] When the plug enters a portion of the compression section 80 within reactor 12, it undergoes heating. This heat induces a reduction in the volume of the plastic within the plug, further increasing its density. The plug reaches its maximum density as it approaches the tube’s second end 22.

[0047] Because of its high density and the tapering of the tube walls, the plug provides an efficient seal through the plug itself or between the plug and the tube walls, thereby preventing the gaseous product of the pyrolysis process from escaping the reactor via apparatus 10.

[0048] The flapper valve serves two essential functions: it further prevents the reverse flow of vapour, and it provides a reactive force (back pressure) to assist in compressing lower density plugs further up the series. This latter advantage is especially critical during the startup phase of apparatus 10 when there is no plug in the compression section to provide resistance. In this initial stage, the plug is absent and cannot prevent vapour flow. Consequently, the flapper valve remains closed, barring reverse flow, until the pressure generated by the compressing plug is sufficient to open the valve. This condition can only be met once the plug has been adequately compressed.

[0049] Lastly, the stator port 34 has several sealed nozzles 42, which allow the introduction of steam and / or solvents to be added or removed from reactor 14 and to facilitate the insertion of instrumentation or other auxiliaries.

Claims

CLAIMS1 . A feedstock delivery apparatus (10) for the continuous feeding of a feedstock to a pyrolysis reactor (14) which includes a body (16), a tube (18) either engaged to or integral with the body, extending between a first end (20) and a second end (22), with the second end adapted for insertion into a port of the pyrolysis reactor, a oneway valve (24) positioned at the second end, a piston (26) engaged with the tube, adapted to move reciprocally between a retracted position and a forward position within the tube between, a feed hooper (28) in communication with the tube, adapted to contain a feedstock (12) and to feed the contained feedstock into the tube, wherein, upon receipt of the feedstock in the tube, the piston is actuatable to move from the retracted position to the forward position, compressing the feedstock into a plug (38.1 ), against a series of previously compressed plugs (38.2, 38.3... ), and expelling a leading plug of the series past the one-way valve, into the furnace.

2. A feedstock delivery device according to claim 1 which includes a sealing assembly (38) engaged with the tube, adapted to provide a seal between the tube and the port.

3. A feedstock delivery apparatus according to claim 2 wherein the sealing assembly includes a rotator component (40, 42), adapted to engage the pyrolysis reactor around the port, and a stator flange (44) attached to the tube, adapted to seal against the rotator.

4. A feedstock delivery apparatus according to claim 3 wherein the rotator component comprises a first flange (40) and a second flange (42), which sandwich the stationary flange in the sealing assembly to form a seal, with the first flange attaching to both the second flange and the pyrolysis reactor.

5. A feedstock delivery apparatus according to claim 4 wherein the stator flange includes at least one circumscribing groove (50) on a first face (48.1 ) and at least one circumscribing groove (52) on a second face (48.2), each groove adapted to receive a complementary sealing means to form a seal against the first flange and the second flange, respectively.

6. A feedstock delivery apparatus according to claim 4 or 5 wherein the sealing assembly includes a divider (58) that engages both the first and second flanges around an outer circumferential region, to evenly axially space the first flange from the second flange when they are attached.

7. A feedstock delivery apparatus according to claim 6 wherein the divider includes a plurality of evenly radially spaced stubs (58).

8. A feedstock delivery apparatus according to anyone of claims 4 to 7 wherein the sealing assembly includes a plurality of rubbing spacers (60) that engage both the first and second faces of the stator flange, spacing the first flange away from the first face when the stator flange moves toward the first flange, and spacing the second flange away from the second face when the stator flange moves toward the second flange.

9. A feedstock delivery apparatus according to claim 8 wherein the rubbing spacers are made of non-stick material.

10. A feedstock delivery apparatus according to anyone of claims 1 to 9 wherein the body is a mobile body, mounted on wheels or tracks (32) to enable the body to move towards or away from the pyrolysis reactor.1 1 . A feedstock delivery apparatus according to anyone of claims 1 to 10 wherein the tube tapers inwardly from the first end toward the second end.

12. A feedstock delivery apparatus according to anyone of claims 1 to 11 wherein the valve is a flapper valve.

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