WO2016092516A1

WO2016092516A1 - Conversion of hydrocarbon based waste material into fuel

Info

Publication number: WO2016092516A1
Application number: PCT/IB2015/059537
Authority: WO
Inventors: William Graham
Original assignee: William Graham
Priority date: 2014-12-11
Filing date: 2015-12-11
Publication date: 2016-06-16

Abstract

A condenser (56) for hydrocarbon gases is disclosed which comprises elements (92). Each element (92) has a main tubular portion and a neck constituting a lower gas entrance to the element. The neck is smaller in cross-sectional dimensions than the tubular portion and there is a tapering section joining the neck to the tubular portion. The upper end of the tubular portion remote from the neck is open and forms an exit for uncondensed gases.

Description

CONVERSION OF HYDROCARBON BASED WASTE MATERIAL INTO FUEL FIELD OF THE INVENTION THIS INVENTION relates to the conversion of waste material into fuel.

BACKGROUND TO THE INVENTION

Synthetic plastics materials, derived from hydrocarbon fuels, are used extensively in industries such as packaging. Millions of tons of plastics are used to produce containers for food products and drinks. Only a small percentage of the plastics material is recycled. The figures available in the literature for the percentage of plastic products which are recycled vary but it is unlikely than more than 10 to 15% is recycled. The rest goes to landfill sites which are rapidly filling. Most plastic materials are not biodegradable.

Installations which convert used synthetic plastics material into fuel are in use in various countries of the world. The plastics material is heated in an oxygen free atmosphere in a reactor so that it is subject to pyrolysis. Hydrocarbon gases are driven off and a residue of charred plastics material remains.

The gases are condensed to give rise to hydrocarbon liquids which are flammable and which can have diesel, kerosene or paraffin like characteristics depending on the processing technique used. A 2009 publication of the United Nations Environment Programme entitled "Converting Waste Plastics into a Resource" is a compendium of technologies and describes the art as it stood that year.

Used tyres from vehicles are another waste product that accumulates in huge quantities and for which no commercially viable, environmentally friendly disposal solution has been proposed.

The present invention provides an installation for, and a method of, converting hydrocarbon based waste material into fuel which installation and method have advantages over known methods and installations.

BRIEF DESCRIPTION OF THE INVENTION

According to one aspect of the present invention there is provided a condenser for hydrocarbon gases, the condenser comprising elements each of which has a main tubular portion, a neck constituting the gas entrance to the element, the neck being smaller in cross-sectional dimensions than the tubular portion and there being a tapering section joining said neck to said tubular portion, the upper end of the tubular portion remote from the neck being open and forming an exit from the element for uncondensed gases.

Said neck and said tubular portion are preferably circular in cross-section and said tapering section is frusto-conical. Said elements are preferably of glass. Said elements can be arranged in columns each comprising a plurality of said elements, the neck of each upper element being inside the tubular portion of the element below it and the tapering section of each upper element resting on the open upper end of the element below it. The condenser can further comprise a vessel having a side wall, a base plate and a top closure defining a condenser chamber, a plurality of said condenser columns within said chamber, a hot gas inlet to the lower end of said vessel, a condensed liquid outlet from the lower end of said vessel, and an outlet for uncondensed gases at the upper end of said vessel. Said base plate preferably has perforations in it and said hot gas inlet can lead to a space below said plate.

In this form said hot gas inlet can comprise a pipe which enters at the top of the vessel, vertically traverses said chamber and passes downwardly through said base plate, said pipe being open at its lower end so that hot gases flow from the pipe into said space and then upwardly through the perforations of the base plate into said chamber.

Said vessel is preferably circular in horizontal cross section and said pipe is co-axial with said chamber, said columns being arranged in a plurality of circular arrays which are co-axial with said pipe.

A water cooling jacket can be provided which encases said vessel. The jacket can comprise sheet metal which has been indented from one side to produce recesses which are on the outer surface of the jacket and protuberances which are on the inner surface of the jacket, the tips of the protuberances being welded to said casing.

There can be a further condenser connected to said uncondensed gases outlet, to condense a further fraction of said hydrocarbon gas. A compressor can be provided for liquefying any hydrocarbon gas which does not condense in the further condenser.

To facilitate removal of columns of elements from the chamber, and their replacement by other columns, it is possible to provide a support for the columns of condenser elements which support can be lifted from, and lowered into, said condenser chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawing in which;

Figure 1 is a pictorial view of an installation in accordance with the present invention;

Figure 2 is a pictorial view of part of the installation of Figure 1 ; Figure 3 is a plan view of the installation of Figure 1 ; Figure 4 is a side elevation of a first trailer on which two reactors are mounted;

Figure 5 is a side elevation of a second trailer on which condensers are mounted; Figure 6 is an axial section through a condenser;

Figure 7 is a top plan view of the condenser with the lid and some pipe work omitted; Figure 8 is an elevation of a condenser element; Figure 9 illustrate two condenser elements before they are fully nested;

Figure 10 illustrate a column of condenser elements;

Figures 11A and 11 B are rear elevations showing the connections between three trailers;

Figure 12 is a side elevation of the third trailer;

Figure 13 top plan view of a support for holding columns of condenser elements; and Figure 14 is a side elevation of the support of Figure 13. DETAILED DESCRIPTION OF THE DRAWINGS

The installation 10 illustrated in the drawings converts synthetic plastic material waste (or used vehicle tyre casings) into fuel.

Conveyors 12 feed plastics waste or chipped tyre casings into hoppers 14 which have upper and lower blade valves. When the upper blade is in its retracted open position to permit waste to fall past the upper blade, the lower blade is closed. Only after the upper blade moves to its closed position does the lower blade move to its open position. This limits the quantity of air that can enter horizontally elongate reactor vessels 16 with the plastic waste. Screw conveyors 18 driven by motors 20, see Figures 1 and 1 1 B, move the material from the hoppers 14 to the vessels 16.

Load cells (not shown) are provided below weighing containers 22 into which plastic waste is dumped before it is lifted by the conveyers 12 to the hoppers 14. The load cells enable the weight of the charge of waste which reaches the reactor vessels 16 to be controlled.

Pusher plates 24 driven by motors and screws 26 move the weighed material along the containers 22 to the conveyors 12. Each reactor vessel 16 comprises an inner cylindrical barrel 28 (Figure 11 B) which is within an outer casing 30. There is an annular gap between the barrel 28 and casing 30.

Below the barrel and within the casing 30 there are burners 32 (Figures 2 and 1 1 B) for raising the temperature of the plastic waste in the barrel to a level such that pyrolysis takes place. The burners can be gas burners and / or liquid fuel burners. The hot gases flow upwardly between the barrel 28 and the casing 30 in a clockwise direction as viewed in Figure 11 B. A divider plate 34 prevents the hot gases from flowing anti- clockwise in the annular gap.

The heating gases escape from the casing 30 through an exhaust pipe 36 which leads to a catalytic converter 38 (see also Figure 1 ) and then to an exhaust stack 40. The hydrocarbon gases driven-off escape from the reactors by way of pipes 42. The temperature in the barrel can be, for example, 380 to 400 degrees centigrade and in the annular gap about 450 degrees centigrade.

Access to the inside of each casing 30 and barrel 28 is by way of a door 44 in the end wall of the casing 30.

In an alternative construction the feed arrangement described above can be omitted and an overhead conveyer (not shown) can be provided for feeding material to inlet openings 46 at the top dead centre positions of the reactor vessels. Alternatively, material such a whole tyre casings can be fed in through the opening which closed by the door 44.

The fixed barrel 28 can be replaced by a rotatable cylinder. In this form the waste is tumbled whilst being heated.

The residue left after pyrolysis is complete can be dragged out through the open door 44 onto a conveyor 46 and thence to a storage bin 48. It is also possible to provide a chute 16.1 (Figure 4) in the underside of each vessel 16 to enable residue to be pushed out. The chutes drop the residue onto a conveyor 6.2. It is also possible to provide a port to which a vacuum hose can be connected so that the residue can be sucked out of the reactor vessel to a silo. To enable the barrel 28 to be cooled after pyrolysis is completed, a blower 50 is provided between the two vessels 16. This blows air through the annular gaps between the barrels 28 and casings 30.

The reactors vessels 16 are mounted on a trailer 52 and the pipes 42 span from this trailer to a further trailer 54 on which a plurality of condensers 56 are mounted. There is a flexible coupling 58 (Figure 11 B) in each pipe 42. The pipes 42 lead to a manifold 60 and inlet pipes 62 of the condensers 56 extend from the manifold 60. As best seen in Figure 6, there is a pipe joint 64 where each pipe 62 is joined to a pipe 66 which extends first horizontally and then downwardly into the condenser 56.

Each condenser 56 (see Figure 6) comprises a vessel in the form of a vertically elongate cylinder 68, a perforated base plate 70, an upper closure 72 and a cone 74 below the base plate 70 and constituting the lower end of the condenser 56. The pipe 62 enters the cylinder 68 and extends downwardly through the cylinder 68 to terminate in the cone 74 below the base plate 70.

A water jacket 76 surrounds the cylinder 68 to enable the temperature of the condenser to be controlled. Pipes 78 and 80 connect the jacket 76 to a source of cooled water as will be described. The water enters via the upper pipe 78 and exits through the lower pipe 80.

To ensure that water flows in as even a manner as possible through the cylindrical space bounded by the cylinder 68 and the jacket 76, the jacket can be manufactured using a metal plate that has been pressed to form a plurality of recesses in one surface and a corresponding plurality of protuberances on the other surface. The plate is rolled to form the jacket 76 with the protuberances on the inside and touching the cylinder 68. The tips of the protuberances are then welded to the cylinder 68. An outlet pipe 82 leads downwardly from the lower end of the cone 74 to a valve 84.

From the valve 84, a pipe (not shown) leads back to the reactor vessels 16. There is a pump (not shown) in this pipe.

During operation, if synthetic plastics material waste constitutes the feed stock, a waxy residue builds up in a chamber provided within the valve 84. When a predetermined level of this residue is sensed, the pump is activated and the residue is pumped from the valve back to the reactor vessels 16 for reprocessing.

There is a cylindrical storage tank 86 (Figure 5 and 1 1 B) below the load bed of the trailer 54. As best seen in Figure 5 pipework generally designated 88 connects the outlet valves 84 of the condensers 56 to the tank 86.

The hot hydrocarbon gases from the reactor vessels emerge, in each condenser 56, from the pipe 66 below the plate 70 and then rise up through the vessel. As the gases cool they condense and the condensate flows out via the pipe 82. Gases which do not condense flow out of the upper end of the cylinder 68 along a pipe 90.

Referring now to Figure 8, the hollow condenser element of glass illustrated is designated 92 and comprises a main tubular portion 94, a neck 96 of smaller cross sectional dimension than the portion 94 and a tapering section 98 which joins the main tubular portion 94 to the neck 96. The end of the tubular portion 94 remote from the section 98, and which is the lower end of the element 92 when it is in use, is open. This enables the neck of a lower element to be inserted, from below, into the tubular portion of an upper element. The lower end of the upper element seats on the junction between the tubular portion 94 and the section 98 of the lower element. The portion 94, the neck 96 and the section 98 are all circular in cross-section.

A column 100 of nested elements 92 can thus be formed as illustrated in Figure 10.

Columns 100 are arranged in the annular space between the pipe 66 and the cylinder 68. This is best seen in Figure 7. The greater part of the hot gases rising through the perforations of the plate 70 enter the columns 100 and flow upwardly from element to element and are condensed within the elements. Gases which enter the spaces between the columns condense on the outside surfaces of the columns.

The lighter fraction of the recovered hydrocarbons that does not condense in the condensers 56 escapes through upper outlets constituted by the pipes 90 into a manifold 102. The manifold 102 is closed at one end (the left hand end in Figure 5) and connected at the other end to a pipe 104 which extends downwardly to the lower end a further condenser 106 (Figure 5). Liquid hydrocarbons run from the condenser 106 through a connection 108 and along pipe work 110 to the tank 86.

A vacuum pump 114 draws gaseous product that does not condense in the condenser 106 from the upper end of the condenser 106 and pumps it through a water seal 116 to an outlet 118. The inlet of a compressor (not shown) can be connected to the outlet 118 for the purpose of liquefying the lighter fraction which has remained gaseous.

The pump 114 maintains a sub-atmospheric pressure in the installation. For example, in the condensers 56 there is a pressure of about 0.8 Bar. By providing a number of condensers and appropriately adjusting the operating temperatures, it is possible to provide fuel one fraction of which has diesel-like characteristics, another fraction of which has kerosene-like characteristics and a still further fraction of which has paraffin- like characteristics. The third trailer 118 shown in Figure 12 is divided internally into a first, second and third compartments 120, 122 and 124. The compartment 120 contains a cooling tower 126 which supplies cooled water to the jackets 76 of the condensers 56 and also to the condenser 106. Part of the pipework for conveying cooled water to the condensers 56 is shown at 128.2 in Figure 12. The pipework leading to the condenser 106 is shown at 128.1 in Figure 11A and 11 B.

Below the load bed of the trailer 118 there is a tank 130 which is connected to the tank 86 so that recovered liquefied hydrocarbons can flow from the main storage tank 86 to the tank 130.

The compartment 120 further contains a number of filter membranes within vertical, cylindrical casings 132. The membranes have as their main function the removal of mercaptans from the liquid fuel. They also inherently retain any other solid particles in the liquid fuel. A pipe 134 (Figure 12) in which there is a pump (not shown) leads from the tank 130 to a manifold 136 which feeds the recovered fuel to the casings 132. The membranes are in series. An outlet pipe 138 leads from the last membrane of the series to the burners 32 of the reactor vessels 16.

There is a compressor 140 in the compartment 120 for supplying air under pressure to pneumatically operated control valves of the installation. The compressor 140 is connected to an air tank 142. The compartment 122 houses the controls 144 for the installation and the compartment 124 houses a diesel generator set 146 and its controls. Fuel from the pipe 138 is used to power the generator set 146.

Experimental work has shown that the hydrocarbon gases entering the condenser have a mixture of carbon chain lengths from one up to about 50 carbon atoms. The temperature of the gases is in the range 160 - 200°C. The temperature in the lower part of the condenser is such that a mist forms on the elements 92. The formation of mist on the elements 92 and the subsequent coagulation of the mist into drops breaks many of the hydrocarbon chains and reduces the long chain lengths to about 18 to 25 carbon atoms. At this chain length the hydrocarbons are liquid at the temperatures maintained in the lower part of the condenser. The short carbon chains of, for example, 1 to 5 carbon atoms, remain in gaseous form and flow out through the pipe 90.

The temperature of the elements 92 in the lower part of the condenser is maintained at about 80°C and the elements 92 in the upper part of the condenser is maintained at a temperature of about 35°C. There is a temperature gradient between the upper and lower ends of each condenser 56.

The support shown in Figures 13 to 14 comprise an upper disc 148 and a lower disc 150 between which there is a column 152 that is coaxial with the discs 148 and 150. An array of rods 154 pass through holes adjacent the peripheries of the discs 148 and 150.

The rods are threaded at both ends and have nuts 156 screwed on to them. The nuts

156 are not shown in Figure 13. When the upper nuts 156 are tightened against the top surface of the disc 148, the discs are pulled towards one another. The column 152 is hollow and the pipe 66 passes through the column. The column 152 acts as a spacer for the discs 148 and 150. It bears on the underside of the disc 148 and the top surface of the disc 150 when the upper nuts 156 are tightened.

The disc 148 has an array of relatively large circular openings 158 in it and the disc 150 has a corresponding array of smaller circular openings 160 in it. Each opening 158 is sized to receive the tubular portion 94 of the upper element 92 of a three element column 100. The openings in the disc 150 are sized to receive the lower ends of the lower elements 92 of the columns 100. The necks 96 of the lower elements 92 pass through the openings in the disc 150 until the tapering section 94 abuts the peripheries of the smaller openings whereby the columns are supported on the lower disc 150.

The upper nuts 156 are removed and the disc 148 lifted off the column 152 for the purpose of removing elements 92 that have been in use and replacing them with fresh elements. Columns 100 each comprising three fresh elements 92 are supported on the disc 150 after the used elements have been removed.

The disc 148 is then replaced so that the upper ends of the upper elements 92 fit in the openings 158. The upper nuts 156 are screwed on to the rods 154.

A lifting eye (not shown) is provided for lifting the support of Figures 13 and 14 from the cylinder 68 and lowering a support with fresh elements 92 on it into the cylinder 68. Whilst three elements 92 are shown as constituting a column 100, there can be a greater number of elements per column.

Claims

CLAIMS:

1. A condenser for hydrocarbon gases, the condenser comprising elements each of which has a main tubular portion, a neck constituting a lower gas entrance to the element, the neck being smaller in cross-sectional dimensions than the tubular portion and there being a tapering section joining said neck to said tubular portion, the upper end of the tubular portion remote from the neck being open and forming an exit from the element for uncondensed gases.

2. A condenser as claimed in claim 1 , wherein said neck and said tubular portion are circular in cross-section and said tapering section is frusto-conical.

3. A condenser as claimed in claims 1 or 2, wherein said elements are of glass.

4. A condenser as claimed in claims 1 , 2 or 3, wherein said elements are in columns each of which columns comprise a plurality of said elements, the neck of each upper element being inside the tubular portion of the element below it and the tapering section of each upper element resting on the open upper end of the element below it.

5. A condenser as claimed in claims 4 and comprising a vessel having a side wall, a base plate and a top closure defining a condenser chamber, a plurality of said columns of elements within said chamber, a hot gas inlet to the lower end of said vessel, a condensed liquid outlet from the lower end of said vessel, and an outlet for uncondensed gases at the upper end of said vessel.

6. A condenser as claimed in claim 5, wherein said base plate has perforations in it and said hot gas inlet leads to a space below said plate.

7. A condenser as claimed in claim 6, wherein said hot gas inlet comprises a pipe which enters at the top of the vessel, vertically traverses said chamber and passes downwardly through said base plate, said pipe being open at its lower end so that hot gases flow from the pipe into said space and then upwardly through the perforations of the base plate into said chamber.

8. A condenser as claimed in claim 7, wherein said vessel is circular in horizontal cross section and said pipe is co-axial with said chamber, said columns being arranged in a plurality of circular arrays which are co-axial with said pipe.

9. A condenser as claimed in claim 8, and including a water cooling jacket which encases said vessel.

10. A condenser as claimed in claim 9, wherein said jacket comprises sheet metal which has been indented from one side to produce recesses which are on the outer surface of the jacket and protuberances which are on the inner surface of the jacket, the tips of the protuberances being welded to said casing.

11. An installation comprising a condenser as claimed in any one of claims 5 to 10 and a further condenser connected to said uncondensed gases outlet to condense a further fraction of said hydrocarbon gas.

12. An installation as claimed in claim 11 and comprising a compressor for liquefying any hydrocarbon gas which does not condense in the further condenser.

13. A condenser as claimed in any one of claims 5 to 12 and comprising a support for columns of condenser elements which support can be lifted from, and lowered into, said condenser chamber.

14. A condenser as claimed in claim 13 wherein said support comprises upper and lower discs which are held spaced apart by a column spanning between them, the lower disc having openings for receiving the said necks and the upper disc having openings for receiving said main tubular portions.