GB2452289A

GB2452289A - Waste sterilisation and recycling apparatus

Info

Publication number: GB2452289A
Application number: GB0716793A
Authority: GB
Inventors: John Lomas
Original assignee: GLOBAL WASTE TECHNOLOGIES Ltd
Current assignee: GLOBAL WASTE TECHNOLOGIES Ltd
Priority date: 2007-08-29
Filing date: 2007-08-29
Publication date: 2009-03-04
Also published as: GB0716793D0

Abstract

A waste recycling apparatus which comprises an input for a waste mixture, which waste mixture may be 'raw' unsorted waste, a waste sterilisation means 2 which may be autoclaves, means for detecting and separating a plurality of different types of waste (3 11 12 13 13a), e.g. ferrous metal, non-ferrous metal, textile material, plastics materials, means for collecting a filtered part for respective recycling. The autoclaves may be heated by recovering heat from the exhaust gases of other autoclaves. Heat may be generated by oxidising parts of the treated waste in an oxidiser 3, with the heat being used to heat the autoclaves. The autoclaves may be mounted pivotally to move between loading and emptying positions. Also disclosed is the use of autoclaves to treat waste and a method of treating waste using an autoclave and an oxidation means to generate heat from treated products.

Description

Recyclina System This invention relates to a waste recycling system.

As concern over the environment grows, there is more and more demand for both domestic and industrial waste to be recycled as much as possible. Previously, the onus was largely upon individuals and individual business to separate out their recyclable waste and to deposit this at various recycling bank locations where, for example, glass could be collected and recycled at dedicated glass recycling facilities and similarly for paper products, ferrous metals and so.

More recently, local authorities have begun to request that householders, either voluntarily or mandatorily, separate out their waste so that recyclable waste can be sent direct to appropriate recycling facilities. This is, however, done on a rather piecemeal basis and still a large quantity of domestic and industrial waste still finds its way into the refuse system where it generally ends up in incinerators or as landfill, adding to various *::::* environmental problems. *

Whilst there are facilities that can accept raw' household waste, ie waste that has * 20 been unfiltered to separate out ferrous metals, glass, etc, these facilities are generally desigiled to handle one particular type of waste. Thus, facilities are available which can use S..

magnetic means to sort ferrous waste.from non-ferrous waste and divert the ferrous material *SSS to a recycling facility, and so on. There is, however, no single apparatus at the moment which can accept unsorted' general waste as an input and which can separate out, as part of an automated or semi-automated machine, many different types of recyclable waste and recycle them. Such an apparatus must be the ultimate aim of any recycling plan if it can recycle sufficient material, be efficient in energy use and result in minimal unrecyclable end product.

The present invention arose in an attempt to provide such a facility.

According to the present invention there is provided a waste recycling apparatus comprising an input for a waste mixture, which waste mixture may be raw' unsorted waste, a waste sterilisation means, means for detecting and separating a plurality of different types of waste, eg ferrous metal, non-ferrous metal, textile material, plastics materials, means for collecting a filtered part for respective recycling.

Preferably, the sterilisation means comprises one or more chambers for heating material under elevated temperature and pressure. These are generally known as autoclave and the term autoclave hereinafter will be intended to mean any apparatus adapted to apply elevated heat and pressure to material.

Most preferably, two or more autoclaves are provided and the apparatus further includes means for firstly using one or the autoclaves to sterilise material then using waste heated gaseous products (eg hot air) from the first autoclave to a second autoclave.

However, only one autoclave may be used in other embodiments. ** * I S...

The or each autoclave may be pivotally mounted to pivot into and out of a waste receiving and processed waste discharge positions.

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*: Preferably, at least fur part of the period, one autoclave is running a heat/pressure I...

*. s.. cycle at least a second autoclave is being loaded with waste. *s..

At least some of the heated air for the or each autoclave may be provided by a waste oxidization apparatus.

The apparatus may comprise means for forming products out of waste plastics, rubble and/or glass material, which products may comprise, for example, bricks, paving slabs and so on.

The invention further provides apparatus for treating waste material under elevated temperatures and pressure, comprising two or more autoclaves.

In a further aspect, there is provided a method of treating waste, comprising using autoclave means to treat the waste at elevated temperature and pressure, and heating treated products in an oxidation means to provide fuel for the autoclave means.

Preferably, two or more autoclaves are used, excess heat from the treatment cycle of one autoclave being used to provide heat for the treatment cycle of a second autoclave.

The invention also provides apparatus or a method comprising any one or more of the features or method steps disclosed herein.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows schematically one embodiment of a waste recycling facility; Figure 2 shows a waste recycling facility; Figure 3 shows a waste input part of the facility of Figure 2; Figure 4 shows metal and plastics separation station; Figure 5 shows a metal separation station; Figure 6 is a side cross-sectional view of an oxidizer and boiler, and Figure 7 is a cross-sectional view from above the oxidizer and boiler.

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* : Referring to Figure 1, there is schematically shown a waste recycling apparatus S...

according to the present invention. *5*I

Generally, in the apparatus, waste is applied at a waste input station!. This can be raw unsorted waste and may, for example, be supplied in filled plastics bags, such as the black plastic sacks which are commonly used for domestic refuse in the UK, and include a household's normal waste. This waste may comprise organic matter, glass, ferrous and/or non-ferrous metals, plastics material, textile materials and fabrics and so on. The combined waste is applied to a waste stenlisation station 2. In preferred embodiments of the invention, the waste sterilisation station is an autoclave which applies elevated temperature and pressure, as will be described further below. Also, preferably, an oxidisation device 3 and a fredback loop 4 is used to provide heated air to aid the sterilisation process, as will be described further below. In general terms, a boiler 5 inputs energy into the waste sterilisation system through a turbine 6. Exhaust gases are fed to a condenser 7 and to a water treatment means 8. Products from this are applied through a hot well and from there back into the waste sterilisation apparatus (autoclave) 2.

After the waste sterilisation process, at station 2, the waste is in a dry processed state and is applied to a trommel 3. Here, fibrous and small particulate size waste is separated out from other solids. The solids component passes a screen 4 where oversized objects and textile materials are separated out and these can be baled and used to feed the oxidizer 3. Other solid and also the fibrous and other small waste separated out by trommel 3 are applied to other separator means for separating out other types of waste matter. These may comprise; a magnetic station 11 for separating out ferrous metal, an eddy current separator (ECS) 12 which separates out non-ferrous metal; air separator means 13 and 13a which separates out glass and compost or fuel components or which, from the solids components, can separate out rubble which has no recycling value, and; a plastics processing apparatus 40 which will be situated generally at the end of the system and which can be used to perform any plastics materials left after all other components have been :w: 20 separated out, into useable items such as paving blocks, bricks and other moulded plastics items. * I

The figure also shows the percentages of the input waste which might be expected, for a normal waste distribution, to be produced of the various end types of material. Thus, from a normal composition of domestic waste, approximately 45% might ultimately be retrieved which is useable as compost or fuel, approximately 8% glass may be retrieved, approximately 5% ferrous metal, about 2% non-ferrous metal, about 9% of the waste might be plastics material which can be moulded into useable blocks, etc and approximateLy 3% would be useable rubble. Thus, in an efficient process, only about 3 to 5% of the waste input at input 1 might be waste for which there is no recycling capability and which cannot be retrieved as recyclable waste.

Figures 2 to 5 show a system in a little more detail. Waste is loaded at loading station 1 onto an input conveyor belt 21. As shown in more detail in Figure 3, the waste is preferably brought in by trucks 22 of the type conventionally used for refuse collection and will usually be in the form of bagged household waste. In the UK, it is common to collect waste in so-called black-bags' which axe essentially light plastics bags (generally made of recycled material) and a household's entire normal daily waste may be put into these bags which are then collected by the vehicle 22 at or near the household and then taken to the recycling apparatus. The bags are then dropped through the fast loading door 23 into a holding pit 24. This preferably is at negative air pressure to prevent odours leaving the facility. In the pit, the waste is pushed onto conveyor belt 21 which may be upwardly inclined as shown. The waste may be weighed here to check for abnormal density, which could indicate, for example the inclusion of large rocks or other debris which are best manuallyremoved.

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Refuse from the conveyor is then dropped onto a high speed vessel loader 25.

Although only one input belt 21 and loading bay are shown, there may of course be a *...: plurality of these so that more than one refuse vehicle can be dropping its load at * S substantially the same time. As shown, the higher end of input belts 21 is mounted above *.** *.. the high speed vessel loader 25 so the bagged waste on the input belt simply drops onto the *** vessel loader 25. The vessel loader propels the waste into the rear of one, or preferably more, autoclaves 26, 27. In the or each autoclave, the waste is compacted, rotated and its pressure increased. In one embodiment, the pressure is brought up to a maximum of 7 bar g. The waste is then heated in the autoclave for approximately one hour, in a preferred embodiment at 200°C, producing a sterilised waste stream. Functioning of the autoclaves will be described further below. In the present embodiment, two autoclaves are used but more than this may be used.

Upon completion of the heating and sterilising cycle, the autoclave releases the by now virtually dry waste onto an off loading conveyor belt 28, which is shown is preferably parallel to the loading belt 25. From here, the waste stream is fed into a rotary trommel screen 29 and this separates out fibrous material (which might by now be termed compost) and oversized material (such as tins, rags, rubble, plastics, etc) onto two respective different conveyors 30 and 31. On the fibre conveyor 31, the fibre first flows past a magnetic separator 32 which removes metals onto metal conveyor 33 and a metal collector 34. The remaining materials pass into an air blower 35 that blows the lighter compost material via conduit 36 into composting silos 37 and the remaining glass and ceramic material continues into a glass outflow container 38.

The solids portion separated out by the trommel 29 passes onto a separation screen 39 to remove materials such as fabric, which material may flow to a baler 40 for transfer elsewhere or for use elsewhere in the plant. The baled material is advantageously transferred (by a forklift truck or other transporter) to an oxidizer 41 which can provide heat for the autoclaves as will be described further below.

The remaining solids in this stream, which may comprise tin, aluminium, other ** *. metal, plastics and other types of small debris, which pass through the mesh in the screen 39, pass onto a magnetic separator 42 which separates out the magnetic (ie ferrous) material * . where they ultimately flow into the ferrous material container 34 and the debris then carries * .** *..: onto an eddy current separator (ECS) 43 which separates out the non-ferrous metals into *.* container 44. Debris falls through a further screen where it is collected and baled whilst the plastics material continues through to a plastics processing machine which can wash, scrub and compress the plastics material before moulding it into desired shapes such as paving brick or tiles. To improve the strength of such bricks, other waste such as small rubble or glass may be added.

Referring now in more detail to the autoclave and oxidizer (heater) mechanism; Figure 3 shows how the waste material flows up input belt 21 and into the high speed vessel loader 25, then is applied into the autoclave 26. The autoclave 26 is pivotable about a pivot point 50 so as to pivot upward to the position 26a shown in Figure 3 where it can receive the waste stream from loading conveyor 28. After the heating/pressure sterilisation cycle, the autoclave is then pivoted downwards into position 26b where the waste is discharged onto the output conveyor 28, which is therefore at a lower elevation to input conveyor 25. In one embodiment, the first input belt 21 is at an angle of about 180.

The angle to which the autoclave raises will of course depend upon the length of the autoclave.

By using two or more autoclaves, greater performance can be achieved and also greater economy. In use, firstly autoclave 26 is in the raised position (26a) and autoclave 27 is the lowered position. Input waste is applied into autoclave 26 and steam or hot air from the boiler is used to heat the contents of the autoclave 26 under pressure as described.

After the processing cycle (typically for about an hour at about 200°C) autoclave 26 is brought into its lowered position and the by now sterilised waste is off loaded onto output conveyor 28. During this time, the other autoclave 27 has been raised into its upward position and now been loaded with waste. This then commences its sterilising cycle either S... while 26 is also sterilising or immediately afterwards. Thus, a continuous process can be achieved, achieving greater throughput and economy.

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When autoclave 26 has finished its sterilising cycle, there will be some residual hot *5S* air and this is applied through conduit mechanism 501o the second autoclave 27. Thus, a

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* .... most desired and unique feature of this design is that hot air from one chamber is recycled for use in a second chamber (autoclave). Each autoclave may be approximately l2m in length and about 2.7m in width. The basic principle of the autoclave is to provide controlled heat under pressurised conditions in the absence of time, for a preset time interval. In the preferred embodiment, the autoclaves are ones manufactured and managed by Advanced Autoclave Systems (AAS). The autoclave includes features such as a hot air jacket, compression spirals inside the autoclave, a control system for mixing hot air and stream and other features which enable the autoclave to proficiently function.

A novel aspect of this system is that the autoclave body is heated by hot flue gases from an oxidizer/incinerator 41. Hot air from the oxidizer is used to heat the outside of the autoclave.

A boiler and steam turbine system 51 is used to generate electricity for the plant operation and in combination the oxidizer 41 provides heat air for the autoclave as described. As fuel for this, bales from the separation lines are used. The oxidizer/ incinerator comprises a number of compartments or chambers 52A to 52F. Six are shown in the example but any number smaller or greater than this may be used. This is in contrast to previously proposed oxidizers or incinerators which tend to use one relatively large chamber. In embodiments of the present invention, by using a number of smaller chambers more efficient combustion can be obtained, smaller amounts of material can be burnt and also a much shorter time is required to fire up the burners for a smaller chamber than a larger chamber. Bales from the debaler 40 are taken from the separation lines into the incinerator. Typically, each bale will weight around 1,000 Kg (although this would depend on the material) and might burn for about 4 hours in one embodiment. The oxidizer may also be used to burn textiles, shoes or other items which have no or little recycling value.

The oxidizer is connected directly to the boiler system 51 and to the autoclave system which therefore uses the hot air from the oxidizer to burn to heat the outside of the * autoclave. The hot air is therefore provided to a jacket or pipe system surrounding each **** * **** autoclave. *

The oxidizer uses a combustion/oxidation process to change solid waste material (ie the bales) into a gaseous material and a by product of residual ash. The process takes place in two stages. Firstly, in a primary chamber, waste is reduced to ash at low temperature and starved air conditions. Secondly, in an afterburner, air is added and this creates turbulent combustion, high temperature and eliminates virtually all harmful pollutants. Indeed, amounts of heat are fed through a release outlet (not shown) such as a release valve.

It should be noted that the oxidizer uses no conventional chimney since the exhaust gas is fed directly to heat the autoclave system.

The boiler and steam turbine system 51 uses steam from the oxidizer to generate electricity. This can then be used for the plant operation either to wholly supply its power needs or partially. Electricity generation is done one small closed loop system.

Figure 4 shows a cross-section, in direction Dl of Figure 2, through part of the processing plant showing both autoclaves 26 and 27. The figure shows more clearly the jacket or pipe work 53 surrounding each autoclave and which receives hot air from the oxidizer 41. Waste treated in the autoclave is then applied to the primary trommel 29 where oversized material is separated out from the smaller material. Plastics material is separated out and extruded into bricks, blocks, etc at the plastic extrusion station.

Figure 4 shows another view illustrating the trommel and metal separator stations.

Figures 6 and 7, respectively, show a side cross-sectional view and a cross-sectional view from above illustrating the minox (oxidizer) unit 41, divided into a number of chambers. Hot air from this is applied to stream boiler 60. The boiler feeds a turbine S...

generator 61 which is used to supply power to the plant. Hot air is also applied via the hot * * air conduits 62 shown in Figure 7 to the autoclaves. **SS

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Claims

Claims 1. A waste recycling apparatus comprising an input for a waste mixture, waste sterilisation means, means for detecting and separating a plurality of different types of waste and means for collecting the separated out parts for respective recycling.
2. Apparatus as claimed in Claim 1, wherein the sterilisation means comprises one or more chambers for heating material under elevated temperature and pressure.
3. Apparatus as claimed in Claim 2, wherein the or each chamber is an autoclave.
4. Apparatus as claimed in any preceding claim, wherein two or more autoclaves are provided and the apparatus further includes means for firstly using one or the autoclaves to sterilise material then using waste heated gaseous products from the first autoclave to provide heat to a second autoclave. ** *
5. Apparatus as claimed in Claim 3 or Claim 4, wherein the or each autoclave is pivotally mounted to move to and from a loading position. * .
6. Apparatus as claimed in any preceding claim, including a waste oxidization means. *S** * *.SS *S**

*..
7. Apparatus as claimed in Claim 6, wherein the waste oxidization means provides at least some or the heat by the or each autoclave.
8. Apparatus as claimed in Claim 7, wherein material separated out by the apparatus is used as a fuel in the oxidizer.
9. Apparatus as claimed in any of Claims 6 to 8, wherein the oxidizer comprises a plurality of chambers.

-ii -
10. Apparatus as claimed in any preceding claim, comprising means for fonning, from plastics material and/or other material, bricks, building blocks, paving slabs or similar.
11. Apparatus as claimed in any preceding claim, wherein the waste material input to the apparatus is bagged, unsorted waste.
12. Apparatus for treating waste material under elevated temperatures and pressure, comprising two or more autoclaves.
13. Apparatus as claimed in Claim 12, wherein, at least for part of the period that one autoclave is running a heat/pressure cycle, at least a second autoclave is being loaded with waste.
14. Apparatus as claimed in Claim 12 or 13, wherein the autoclaves are pivotally mounted to move to and from a loading position. *S.
15. Apparatus as claimed in any of Claims 12 to 14, wherein heat from one autoclave is * used to heat a second autoclave. S...

S

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16. A method of treating waste, comprising using autoclave means to treat the waste at *S..

*..: elevated temperature and pressure, and heating treated products in an oxidation means to *SSS *. provide fuel for the autoclave means.
17. A method as claimed in Claim 16, wherein two or more autoclaves are used, excess heat from the treatment cycle of one autoclave being used to provide heat for the treatment cycle of a second autoclave.
18. Recycling apparatus substantially as bereinbefore described with reference to, and as illustrated by, any of the accompanying drawings.
19. A method of treating waste substantially as hereinbefore described, with reference to the accompanying drawings. * S.. S... *S... S.... *SI* * . S...

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