GB2537194A

GB2537194A - System and method for controlled supply of commingled plastic from municipal solid waste (MSW) to an in-vessel and obtaining oil/liquid fuel of consistent

Info

Publication number: GB2537194A
Application number: GB1516786.9A
Authority: GB
Inventors: Ejaz Sayani Mohd
Original assignee: GREEN CONSERVATION RESOURCES Ltd
Current assignee: GREEN CONSERVATION RESOURCES Ltd
Priority date: 2015-04-01
Filing date: 2015-09-22
Publication date: 2016-10-12
Anticipated expiration: 2035-09-22
Also published as: GB2524405A; GB2537194B; GB201505656D0; GB201516786D0

Abstract

A system for the controlled supply and processing of commingled plastic comprising: an in-vessel 18 comprising: a cylindrical inner vessel, an oval outer vessel/jacket and a heating means, a burner, located in the outer vessel/jacket; a feeding hopper 16 and feeding screw 17 that supply the plastic to the in-vessel in a controlled manner; a heavy density separator 14 for separating vapour from wax; a venturi scrubber 10 for receiving and cooling the light vapours of the plastic and condensing the vapours into oil; a sludge screw conveyor 20 for removal of sludge from the in-vessel and a distillation column for receiving the oil from the scrubber and separating the oil into light oil with a low flash point and a residue wherein the residue is refuse-derived fuel (RDF). The feeding hopper 16 comprises a first pair of feed rollers and a second pair of feed rollers disposed below the first pair of feed rollers; all the feed rollers have paddles configured thereon. The in-vessel 18 comprises a feeding duct having an inverted cone shape and the plastic in the in-vessel is heated to a temperature between 400°C and 600°C.

Description

System and Method for Controlled Supply of Commingled Plastic from Municipal Solid Waste (MSW) to An In-vessel and Obtaining Oil/Liquid Fuel of Consistent Flash Point by Depolymerisation of Plastic from the MSW

Field of the invention

The present invention relates to controlled supply of commingled plastic from municipal solid waste (MSW) to an in-vessel and depolymerisation thereof. More particularly, the invention relates to a system and method for controlled supply of commingled plastic from municipal solid waste (MSW) to an in-vessel, depolymerisation of the plastic, and obtaining oil/liquid fuel of consistent flash point by continuous processing of commingled plastic from MSW (without any downtime required for clearing/clearing jamming).

Background of the invention

With demand of power and electricity growing exponentially day by day the traditional sources viz, fossil fuel (coal and petroleum reserves) are falling short to meet the hugely disproportionate requirement for running power plant.

On the other hand, there is an ever-growing problem of disposal of municipal solid dry plastic wastes.

Both the critical issues can be addressed if the municipal solid waste plastic can be recycled and/or used for deriving alternative fuel.

The commingled plastic from refuse or municipal solid waste (MSW) has decent calorific value and has found utility as a fuel in power plants. The refuse or municipal solid waste after being processed, particularly after shredding, screening and squeezing, is used as a fuel known as Refuse derived Fuel (RDF) in power plants.

There are methods known in the prior art of pyrolysis of plastic. However, those methods remain theoretical, and do not meet industrial requirement. This is due to the reason that for industry a continuous supply of alternative fuel having consistent flash point is an essential requirement, which presently is not met with any set up. Thls is mainly due to the reason that generally the Refuse Derived Fuel (RDF) is in loose fluffy form having a density less than one; however, due to inherent nature of the material, such solid waste is difficult to handle and generally clogs into its passages in depolymerisation system/set up, causing inconsistency in the processing of commingled plastic from MSW, and in turn resulting in failure to obtain oil/liquid fuel having consistent flash point.

Most of the conventional depolymerisation systems for feeding commingled plastic from MSW to in-vessel utilize a material storage chamber and a screw feeder, wherein the commingled plastic from the material storage chamber directly falls on the screw feeder disposed underneath the material storage chamber and the screw feeder pushes the commingled plastic from MSW to the in-vessel. However, such a configuration of the feeder has drawbacks associated therewith. For example, commingled plastic from MSW directly falling on the screw feeder causes the screw feeder to be loaded. In some cases the impact of the commingled plastic directly falling on the screw feeder is so much that it may cause damage to the screw feeder. Further, in case of conventional system the loading of the screw feeder is not uniform and as such the screw feeder may get damaged. Further, the commingled plastic may get trapped between narrow passages configured in the screw feeder and the screw feeder may get chocked.

Further, in case of conventional system the feed is controlled by varying the rotational speed (rpm) of the screw feeder. The rpm of the screw feeder is controlled by using a variable frequency drive. However, such a configuration of the conventional system requires variable frequency drive and other delicate control equipment, wherein with more number of elements the reliability of the feeding system is substantially reduced. Further, the feeding system becomes prone to frequent failures, thereby requiring regular maintenance.

Thus, there is a need for a system and process for efficient pyrolysis/depolymerisation of commingled plastic from MSW, and there is a particular need of an efficient feeding system for pyrolysis/depolymerisation set up. More particularly, there is a need for a system and method for controlled and regulated feeding of commingled plastic from MSW to in-vessel of depolymerisation system. Further, there is a need for a feeding system that eliminates the drawbacks associated with loading of the screw feeder due to the commingled plastic directly dropping thereon. Furthermore, there is a need for a feeding system that is easy to operate and convenient to use. Still further, there is a need for a feeding system that is properly controlled and is reliable. Further, there is a need for a feeding system that is simple in construction. Furthermore, there is a need for a feeding system that requires less maintenance.

Objects of the invention Some of the objects of the system and the method of the present invention, which at least one embodiment herein satisfies, are as follows: It is an object of the system and the method of the present invention to ameliorate one or more problems of the prior art or to at least provide a useful alternative.

An object of the present invention is to provide a system and method for deriving oil/liquid fuel of consistent flash point by depolymerisation of plastic, which eliminates the drawbacks associated with prior art methods for the said purpose.

Another object of the present invention is to provide a setup which ensures a continuous and regulated supply of the raw material, viz. commingled plastic from MSW, which is essential for obtaining oil/liquid fuel of consistent flash point.

A further object of the present invention is to provide a system and method for deriving oil/liquid fuel of consistent flash point from plastic, wherein frequent jamming issues are efficiently overcome, without compromising on production time and schedule.

Another object of the present disclosure is to provide a feeding system for controlled and regulated feeding of commingled plastic from MSW, to an in-vessel.

Still another object of the present disclosure is to eliminate the need for variable frequency drive in the feeding system.

Another object of the present disclosure is to provide a feeding system that is simple in construction, precise in operation and reliable, easy to operate and convenient to use, and requiring less human intervention and less maintenance.

Still another object of the present disclosure is to provide a feeding system that automatically controls feeding of commingled plastic from MSW to an in-vessel.

Other objects and advantages of the system of the present disclosure will be more apparent from the following description when read in conjunction with the accompanying figures, which are not intended to limit the scope of the present

disclosure.

Summary of the invention

According to a first aspect of the invention there is provided a system for the controlled supply of commingled plastic from municipal solid waste (MSW) to an in-vessel and obtaining oil/liquid fuel of consistent flash point by depolymerisation of commingled plastic from the MSW, the system comprising: an in-vessel for receiving commingled plastic from MSW, comprising (i) an inner vessel wherein the commingled plastic from MSW is received, and (ii) an outer vessel/jacket having a heating means installed therein, the outer vessel/jacket surrounding/jacketing said inner vessel; a feeding hopper and a feeding screw for feeding the commingled plastic from MSW to the in-vessel; a heavy density separator for separating vapours from wax, the separator being connected to the in-vessel through a gas vapour path for travel of vapours of the plastic from the in-vessel, and part of the vapours condensing into wax in the heavy density separator; a venturi scrubber for receiving and cooling light vapours of the plastic condensing into oil; a sludge screw conveyor operationally connected to the in-vessel for removal of sludge from the in-vessel; a distillation column for receiving oil condensed into the venturi scrubber, heating the same, and separating light oil therefrom that has low flash point, through evaporation, the residue being refuse-derived fuel (RDF) collected in an oil storage tank; and a system for feeding the commingled plastic from MSW in a controlled manner to the in-vessel through the Feeding Hopper and the Feeding Screw, characterized in that, the in-vessel comprises a bearing housing having a cooling jacket with a seal, the seal maintaining anaerobic condition inside the in-vessel; the sludge screw conveyor comprises an insulating jacket for keeping the screw conveyor heated at temperature in a range of 420 to 500 degree Celsius so that there is no lump formation and jamming in the screw conveyor is thus avoided; the feeding hopper is designed as an inverted shoot with one or more roller-feed control devices and comprises at least one feed control device (not shown), operationally connected thereto, for ensuring regulated feeding into the in-vessel; The feeding screw is water-jacketed for cooling of the commingled plastic; the heavy density separator has its body having an inlet for the vapours of the plastic, a funnel-shaped bottom end, a central pipe forming outlet for thermally cracked simple compound fraction of the vapours of the plastic, and at least one rotary air lock valve for ensuring that all complex compounds or wax get trapped in the heavy density separator and only simple compound vapours are then carried forward through the outlet to the venturi scrubber; the vapours carried forward to the venturi scrubber are cooled down through direct cooling; and the system for feeding the commingled plastic from MSW in a controlled manner to the in-vessel comprises a material storage chamber/chute, a screw feeder, and a feed regulating arrangement disposed between the material storage chamber/chute and the screw feeder, so as to make the commingled plastic from MSW first pass through the feed regulating arrangement and is not directly dropped on the screw feeder, wherein light vapours go to the open venturi scrubber for cooling, the non-condensing vapours are re-used in a burner for heating a hot air generator (which supplies heat to the in-vessel), and the condensing vapours convert into the RDF oil.

The feed regulating arrangement of the system may include a first pair of feed rollers and a second pair of feed rollers disposed below the first pair of feed rollers, the feed rollers of the second pair of feed rollers being smaller in size than the feed rollers of the first pair of feed rollers; the feed rollers in a pair being capable of moving towards or away from each other through a gear motor arrangement, and all the feed rollers having paddles configured thereon.

The screw feeder of the system may be driven by an independent chain and motor arrangement.

The feed regulating arrangement of the system may bear the loading of the commingled plastic from MSW, thereby avoiding loading of the screw feeder and eliminating need for variable frequency drive for varying rotational speed of the feeder for regulating the feed to the in-vessel.

In the system chances of abrupt loading of the feeder may be further reduced by dropping a measured quantity of the commingled plastic from MSW on the feeder, with the help of a pair of panels, a pair of piston cylinders and a pair of load cells disposed on the pair of panels, the panels moving towards and away from each other to respectively define a hold configuration in which the panels hold the commingled plastic from MSW thereon and a release configuration in which the panels release the commingled plastic from MSW onto the screw feeder, wherein the movement of the panels towards and away from each other is governed by the piston and the cylinders.

The commingled plastic received in the in-vessel may be loose mixed multi-layered plastic.

The in-vessel may further comprise a feeding duct having inverted cone shape, which would avoid jamming and clogging of the feeding duct.

The in-vessel may further comprise an air jacket along its entire circumference for insulation of the in-vessel.

The material storage chamber/chute may receive the commingled plastic through a conveying system.

The commingled plastic from MSW may be fed in a controlled/regulated and continuous manner, without any downtime required for clearing/clearing jamming.

According to a second aspect of the invention there is a provided a method for controlled supply of commingled plastic from municipal solid waste (MSW) to an in-vessel and obtaining oil/liquid fuel of consistent flash point by depolymerisation of commingled plastic from the MSW, the method comprising the steps of: i. heating the plastic until it vaporises; ii. allowing the vapours to pass through a gas vapour path to reach a heavy density separator for removing partial cracking of the plastic/wax; allowing light vapours emanating from the heavy density separator to be collected in an open venturi scrubber and cooling the collected vapours therein, whereupon the condensing vapours convert into oil; iv. heating the oil at around 105 degree Celsius and obtaining evaporated light oil having low flash point; and v. passing the residue obtained after step (iv) above through a filter, thereby obtaining the RDF.

The plastic may be heated to a temperature of around 400 to 600 degree Celsius, preferably to a temperature of around 420 to 500 degree celsius.

The RDF may be provided in a controlled/regulated manner by continuous processing of commingled plastic from municipal solid waste (MSW) without any downtime required for clearing/clearing jamming.

The system the inner vessel of the in-vessel may be cylindrical, the outer vessel/jacket of the in-vessel may be oval-shaped, both the inner vessel and the outer vessel may be made of SS material, and the heating means installed in the outer vessel/jacket may be a burner,

Brief Description of Drawings

Figurel shows a schematic view of the system for deriving oil/liquid fuel of consistent flash point by depolymerisation of plastic, in accordance with an embodiment of the invention.

Figure la illustrates a schematic representation of a feeding system for providing controlled and regulated feed of commingled plastic from MSW to an in-vessel of depolymerisation system according to the present invention.

Figure lb illustrates a side view of the feeding system of Figure la.

Figure lc illustrates an isometric view of the feeding system of Figure la.

Figure 2 illustrates an isometric view of a feed control roller or feed roller of the feeding system of Figure la.

Figure 3 shows an expanded view of the heavy density separator.

Figure 4 shows an expanded view of the venture scrubber.

List of Components Component No. Name of the Component 10. Venturi scrubber 11. Oil storage tank 12. hot air generator 13. Burner for hot air generator 14. Heavy density separator 15. Gas vapour path 16. Feeding hopper 17. Feeding screw 18. In-vessel 19. Outer jacket 20. Sludge screw conveyor 21. Feeding duct in the in-vessel 22. Rotary air lock valve in the heavy density separator 23. Bearing housing 24. Water jacket 25. Emergency valve in the feeding duct in the in-vessel 10a Material storage tank/chute 26 Pump 12a Power plant equipment such as boiler (12a) 13a Burner heating power plant equipment such as boiler (12a), for which RDF is to be supplied 100. System (100) for feeding commingled plastic from MSW to the in-vessel (18) through the feeding hopper (16) and the feeding screw (17) 20a Screw feeder of for feeding commingled plastic from MSW to in-vessel Feed regulating arrangement for the system (100) 32a, 32b First pair of feed rollers 34a, 34b Second pair of feed rollers 33 Paddles configured on the feed rollers 36a Gear motor arrangement 22a Independent chain and motor arrangement driving the screw feeder (20a) 40a, 40b Pair of panels comprising arrangement for dropping measured quantity of fuel onto the screw feeder (20a) 42a, 42b Pair of piston and cylinder governing movement of the panels (40a, 40b) 44a, 44b Load cells measuring weight of refuse derived fuel (RDF)

Detailed Description

The foregoing objects of the present invention are accomplished and the problems and shortcomings associated with the prior art, techniques and approaches are overcome by the present invention as described below in the preferred embodiments.

The following description with reference to the accompanying drawing is provided to assist in a comprehensive understanding of exemplary embodiments of the invention as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.

The terms and words used in the following description and the claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention is provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.

It is to be understood that the singular forms "a", "an" and "the" include plural referents unless the context clearly indicates otherwise.

The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.

According to the present invention there is provided a system and method for controlled supply of commingled plastic from municipal solid waste (MSW) to an in-vessel and obtaining oil/liquid fuel of consistent flash point by depolymerisation of commingled plastic from MSW.

According to one embodiment of the present invention as shown in Figure 1, the system comprises an in-vessel (18), a feeding screw (17) operationally connected to a feeding hopper (16), path for plastic vapour (15), a heavy density separator (14), a venturi scrubber (10), an oil storage tank (11), a material storage chamber/chute (10a)receiving commingled plastic through a conveying system (not shown),), a burner (13) supplying heat to a hot air generator (12) for heating the in-vessel, and a sludge screw conveyor (20).The refuse derived fuel (RDF oil) can be supplied to power plant equipment such as boiler (12a) through a pump (26).

With reference to Figure 1, commingled plastic from MSW is fed into the in-vessel (18) for depolymerisation, through a feeding hopper (16) and feeding screw (17) assembly.

In a preferred embodiment the feeding hopper (16) is designed to holds at least 1.5 tonnes of commingled plastic. A feed control device (not shown), operationally connected to the feeding hopper (16), operates to ensure regulated feeding into the in-vessel. The raw material (viz. commingled plastic) level in the feeding hopper is monitored and maintained by a photocell, in order to ensure regular supply of the raw material. The hopper is designed as an inverted shoot to avoid jamming with four roller-feed control devices. The feed is regulated by a variable frequency drive motor.

After passing through the feeding hopper the raw material (viz. commingled plastic) flows further with the help of the feeding screw (17). The feeding screw (17) is water-jacketed for cooling of the commingled plastic. This is essential because in case of stoppage of the feeding screw (17) the raw material (viz. commingled plastic) would form into lumps, as the vapours from the in-vessel would adversely increase the temperature in the feeding screw (17).

There is a feeding duct (21) in the in-vessel (18), which is also inverted in design to avoid jamming and clogging. Due to inverted cone-profile of the duct from inside, at any place in the duct the lower portion has a bigger diameter than the upper portion, and hence any lumps formed in the duct at any place can be easily pushed down and passed inside the in-vessel, through the lower portions of bigger diameter.

The in-vessel is a jacketed vessel. There is an inner vessel that receives feed of the commingled plastic from MSW, and an outer vessel that surrounds and forms a jacket around the inner vessel (thus, one vessel inside another vessel; hence the name "in-vessel").

In a preferred embodiment, the inner vessel is cylindrical and it is made of SS material; and the outer vessel (jacket) is oval shaped and made of SS material. Heating means is installed in said oval-shaped outer vessel/jacket. In a preferred embodiment the heating means is a burner.

The inner vessel has a rotating scrapper shaft (not shown) which has mechanical seal bearings to agitate the material inside, which is important for vaporisation.

The in-vessel (18) is equipped with a specially designed water jacket (24) for insulation as generally the in-vessel temperature is maintained in a range of 300 to 800 degrees Celsius. There is also provided a bearing housing (23) at both ends of the scrapper shaft (not shown) rotating inside the in-vessel (more precisely, rotating inside the inner vessel of the in-vessel). The bearing housing (23) has a special cooling jacket (not shown) comprised of a mechanical seal, preferably of polytetrafluoroethylene (not shown) that cools the bearings of the housing (23). The seal maintains anaerobic condition inside the in-vessel (18), which is essential for pyrolysis of polymer to take place.

As an additional safeguard, a safety valve (25) is installed in the feeding duct (21) for handling fire or other similar emergency situations.

The in-vessel temperature is maintained in a range of 300 to 800 degrees Celsius. The commingled plastic is vaporised and is first passed through the heavy density separator (14), through a channel provided for the vapour path (15). This removes partial cracking of the plastic/wax.

The heavy density separator (14) acts as a natural draft. The construction of the heavy density separator is shown in Figure 3. The heavy density separator has its body having an inlet for the vapours of the plastic, a funnel-shaped bottom end, a central pipe forming outlet for thermally cracked simple compound fraction of the vapours of the plastic, and at least one rotary air lock valve (22) for ensuring that all complex compounds or wax get trapped in the heavy density separator and only simple compound vapours are then carried forward through the outlet to the venturi scrubber (10).

The vapours entering the venture scrubber (10) are cooled down through direct cooling. Due to direct cooling the venturi scrubber never gets jammed. Figure 4 shows an expanded view of the venturi scrubber (10).

The condensing vapours convert into oil. The oil recovered upon condensation of the vapours is passed through a distillation column (not shown) which is specially designed to electrically heat at around 105 degree Celsius. The part which evaporates upon heating (light fraction of the oil) is light oil which has low flash point. Separation of the light fraction ensures flash point consistency in the residue oil. The residue oil is passed through a filter (10 micron filter, in a preferred embodiment). The filtrate is nothing but the refuse derived fuel (RDF) useful for heating power plant equipment (such as boiler (12a)).

The vapours which do not get condensed are stored in a tank and used for captive consumption in heating the in-vessel and re-used in a burner (13) for heating the in-vessel (18).

The residual material in the in-vessel is carbon powder which is removed with a sludge screw conveyor (20) operatively connected to the in-vessel (18). The sludge screw conveyor is jacketed with insulation, so that there is no lump formation and jamming is thus avoided.

The aforesaid system and process ensure continuous feeding of the raw material (i.e. plastic) for 22 hours a day, while the rest 2 hours are used for only heating and cleaning the entire system. Thus, without taking any downtime, i.e., while the operation is in progress, the system is cleaned of any jamming.

The (RDF) is first collected in an oil storage tank (11). It is thereafter transported to a material storage chamber/chute (10a) by a pump (26). From the chamber the fuel may be supplied as per the intended use, e.g. to a burner (13a) heating a power plant equipment (such as boiler) (12a).

Referring to Figure la -Figure lc of the accompanying drawings, different views of a system 100 for feeding commingled plastic from MSW to an in-vessel of the depolymerisation set up in accordance with the present invention. The system 100 for feeding includes a material storage chamber/chute 10a, a screw feeder 20a and a feed regulating arrangement 30 disposed between the material storage chamber/chute 10a and the screw feeder 20a, such that the commingled plastic to be fed has to first pass through the feed regulating arrangement 30 and is not directly dropped on the screw-feeder 20a, thereby eliminating the drawbacks of the conventional feeding system in which raw material is directly dropped on the screw feeder thereby causing loading of the screw feeder. In case of the system 100 for feeding the commingled plastic from MSW, the feed regulating arrangement 30 bears the loading and the loading of the screw-feeder 20a is avoided. The feed regulating arrangement 30 includes a first pair of feed rollers 32a, 32b and a second pair of feed rollers 34a, 34b disposed below the first pair of feed rollers 32a, 32b. The feed rollers 34a, 34b of the second pair of feed rollers are smaller in size than the feed rollers 32a, 32b of the first pair of feed rollers. All the feed rollers have paddles configured thereon for facilitating better handling of the fuel.

Figure 2 illustrates an enlarged view of a feed roller 32a with paddles 33 configured thereon. Further, the feed rollers 32a, 32b of the first pair of feed rollers can be moved towards and away from each other. Similarly, the feed rollers 34a, 34b of the second pair of feed rollers can also be moved towards and away from each other. The rotational speed (rpm) of the feed rollers 32a, 32b and the feed rollers 34a, 34b can be controlled.

The feed rollers derive driving power from driving chain and gear motor arrangement.

In accordance with an embodiment, the feed roller 32a and feed roller 34a are driven by a single driving chain and gear motor arrangement 36a and the feed roller 32b and feed roller 34b are driven by another driving chain and gear motor arrangement or driving chain and gear box arrangement 36b. Further, the movement of the feed rollers 32a, 32b is synchronized with the movement of the feed rollers 34a, 34b. Further, the screw feeder 20 is driven by independent chain and motor arrangement 22a. Such control of rotation speed and the movement of the feed rollers 32a and 34a enables the feed regulating arrangement 30 in uniformly distributing the commingled plastic from MSW over the screw feeder 20a rotating at fixed rpm, unlike conventional feeding system in which the screw feeder utilizes variable frequency drive for varying rotational speed thereof for regulating the feed to the in-vessel. The feed regulating arrangement 30 eliminates the loading of the screw feeder 20a and also eliminates the need for variable frequency drive for varying rotational speed of the screw feeder 20 for regulating the feed to the in-vessel. The feed regulating arrangement 30 eliminates the need to vary the rotational speed of the screw feeder 20a which may be detrimental for efficient operation of the screw feeder 20a and may lead to choking of the screw feeder 20a. In order to further reduce the chances of abrupt loading of the screw feeder 20a and ensuring uniform and controlled loading of the screw feeder 20a, a measured quantity of commingled plastic from MSW is dropped onto the screw feeder 20a. For achieving dropping of measured quantity of fuel onto the screw feeder 20a, an arrangement for dropping a measured quantity of fuel onto the screw feeder is used, this arrangement includes a pair of panels 40a and 40b, a pair of piston cylinders 42a and 42b and a pair of load cells 44a and 44b disposed on the pair of panels 40a and 40b.

The panels 40a and 40b move towards and away from each other to respectively define a hold configuration in which the panels 40a and 40b hold the commingled plastic from MSW thereon and a release configuration in which the panels 40a and 40b release MSW onto the screw feeder 20a, wherein the movement of the panels towards and away from each other is governed by the piston cylinders 42a and 42b respectively. The panels 40a and 40b move from the hold configuration to the release configuration only when a pre-determined weight of the fuel is supported on the panels as measured by the load cells 44a and 44b. More specifically, the panels 40a and 40b intermittently move from the hold configuration to the release configuration to release the commingled plastic from MSW onto the screw feeder 20a, when a pre-determined weight of the commingled plastic from MSW is supported on the panels.

The feed regulating arrangement 30 facilitates precise control and regulation of the feed to the in-vessel. The feed rollers move away from each other, when more feed is to be provided and the feed rollers move close to each other when less feed is to be provided.

Such a configuration of the system 100 facilitates uniform distribution of the commingled plastic from MSW over the entire length of the screw feeder 20a, thereby reducing the loading of the screw feeder 20a and enabling accurate control and regulation of the feed to the in-vessel without varying the rotational speed of the screw feeder. Thus, the system (100) imparts a controlled manner to feeding of the commingled plastic to the in-vessel (through the feeding hopper (16) and feeding screw (17)). As can be seen from Figure 1, the commingled plastic starts to move from the material storage chamber (10a); then it is passed through the system (100); then through the feeding hopper 16; then through the feeding screw 17; and then reaches the in-vessel (18).

Claims

We claim: 1, A system for controlled supply of commingled plastic from municipal solid waste (MSW) to an in-vessel and obtaining oil/liquid fuel of consistent flash point by depolymerisation of plastic from the MSW, the system comprising: an in-vessel (18) for receiving commingled plastic from MSW, comprising (i) an inner vessel wherein the commingled plastic from MSW is received, and (ii) an outer vessel/jacket having a heating means installed therein, the outer vessel/jacket surrounding/jacketing said inner vessel; a feeding hopper (16) and a feeding screw (17) for feeding the commingled plastic from MSW to the in-vessel; a heavy density separator (14) for separating vapours from wax, the separator being connected to the in-vessel through a gas vapour path (15) for travel of vapours of the plastic from the in-vessel, and part of the vapours condensing into waxin the heavy density separator; a venturi scrubber (10) for receiving and cooling light vapours of the plastic condensing into oil; a sludge screw conveyor (20) operationally connected to the in-vessel for removal of sludge from the in-vessel; a distillation column for receiving oil condensed into the venturi scrubber, heating the same, and separating light oil therefrom that has low flash point, through evaporation, the residue being refuse-derived fuel (RDF) collected in an oil storage tank (11); and a system for feeding the commingled plastic from MSW in a controlled manner to the in-vessel through the Feeding Hopper and the Feeding Screw, characterized in that, the in-vessel comprises a bearing housing (23) having a cooling jacket with a seal, the seal maintaining anaerobic condition inside the in-vessel (18); the sludge screw conveyor (20) comprises an insulating jacket for keeping the screw conveyor heated minimum at 420 degree Celsius and maximum at 500 degree Celsius so that there is no lump formation and jamming in the screw conveyor is thus avoided; the feeding hopper (16)is designed as an inverted shoot with one or more roller-feed control devices and comprises at least one feed control device (not shown), operationally connected thereto, for ensuring regulated feeding into the in-vessel; The feeding screw (17) is water-jacketed for cooling of the commingled plastic; the heavy density separator (14) has its body having an inlet for the vapours of the plastic, a funnel-shaped bottom end, a central pipe forming outlet for thermally cracked simple compound fraction of the vapours of the plastic, and at least one rotary air lock valve (22) for ensuring that all complex compounds or wax get trapped in the heavy density separator and only simple compound vapours are then carried forward through the outlet to the venturi scrubber (10); the vapours carried forward to the venturi scrubber (10) are cooled down through direct cooling to condense into oil; and the system for feeding the MSW in a controlled manner to the in-vessel comprises a material storage chamber/chute (10a), a screw feeder (20a), and a feed regulating arrangement (30) disposed between the material storage chamber/chute (10a) and the screw feeder (20a), so as to make the commingled plastic from MSW first pass through the feed regulating arrangement (30) and is not directly dropped on the screw feeder (20a), wherein light vapours go to the open venturi scrubber for cooling, the non-condensing vapours are re-used in a burner (13) for heating a hot air generator (which supplies heat to the in-vessel), and the condensing vapours convert into the RDF oil.
2. The system in accordance with Claim 1, wherein the feed regulating arrangement (30) includes a first pair of feed rollers 32a, 32b and a second pair of feed rollers 34a, 34b disposed below the first pair of feed rollers 32a, 32b, the feed rollers 34a, 34b of the second pair of feed rollers being smaller in size than the feed rollers 32a, 32b of the first pair of feed rollers; the feed rollers in a pair being capable of moving towards or away from each other through a gear motor arrangement (36a, 36b for each of the pairs), and all the feed rollers having paddles (33) configured thereon.
3. The system in accordance with Claim 1, wherein the screw feeder (20a) is driven by an independent chain and motor arrangement (22a).
4. The system in accordance with Claim 1, wherein the feed regulating arrangement (30) bears the loading of the commingled plastic from MSW, thereby avoiding loading of the screw feeder (20a) and eliminating need for variable frequency drive for varying rotational speed of the feeder (20a) for regulating the feed to the in-vessel.
5. The system in accordance with Claim 1, wherein chances of abrupt loading of the feeder (20a) are further reduced by dropping a measured quantity of the commingled plastic from MSW on the feeder (20a), with the help of a pair of panels 40a and 40b, a pair of piston cylinders 42a and 42b and a pair of load cells 44a and 44b disposed on the pair of panels 40a and 40b, the panels 40a and 40b moving towards and away from each other to respectively define a hold configuration in which the panels 40a and 40b hold the commingled plastic from MSW thereon and a release configuration in which the panels 40a and 40b release the commingled plastic from MSW onto the screw feeder 20, wherein the movement of the panels towards and away from each other is governed by the piston cylinders 42a and 42b respectively.
6. The system in accordance with Claim 1, wherein the commingled plastic received in the in-vessel is loose mixed multi-layered plastic.
7. The system in accordance with Claim 1, wherein the in-vessel further comprises a feeding duct (21) having inverted cone shape, which avoids jamming and clogging of the feeding duct.
8. The system in accordance with Claim 7, wherein the in-vessel further comprises an air jacket (19) along its entire circumference for insulation of the in-vessel.
9. The system in accordance with Claim 1, wherein the material storage chamber/chute (10a) receives the commingled plastic through a conveying system (not shown).
10. The system in accordance with Claim 1, wherein the commingled plastic from MSW is fed in a controlled/regulated and continuous manner, without any downtime required for clearing/clearing jamming.
11. A method for controlled supply of commingled plastic from municipal solid waste (MSW) to an in-vessel and obtaining oil/liquid fuel of consistent flash point by depolymerisation of plastic from the MSW, the method comprising the steps of: i. heating the plastic until it vaporises; ii. allowing the vapours to pass through a gas vapour path (15) to reach a heavy density separator (14) for removing partial cracking of the plastic/wax; Hi. allowing light vapours emanating from the heavy density separator to be collected in an open venturi scrubber (10) and cooling the collected vapours therein, whereupon the condensing vapours convert into oil; iv. heating the oil at around 105 degree Celsius and obtaining evaporated light oil having low flash point; and v. passing the residue obtained after step (iv) above through a filter, thereby obtaining the RDF.
12. The method of claim 11 wherein the plastic is heated to a temperature of around 400-600 degree Celsius.
13. The method of claim llwherein RDF is provided in a controlled/regulated manner by continuous processing of commingled plastic from municipal solid waste (MSW) without any downtime required for clearing/clearing jamming.
14. The system in accordance with Claim 1, wherein the inner vessel of the in-vessel is cylindrical, the outer vessel/jacket of the in-vessel is oval-shaped, both the inner vessel and the outer vessel are made of SS material, and the heating means installed in the outer vessel/jacket is a burner.