WO1996018847A1

WO1996018847A1 - Refuse disposal methods and apparatus

Info

Publication number: WO1996018847A1
Application number: PCT/NZ1994/000142
Authority: WO
Inventors: Rex Lyle Joseph Waite
Original assignee: Waite, Mauritia, De
Priority date: 1994-12-12
Filing date: 1994-12-12
Publication date: 1996-06-20
Also published as: AU1205595A; AU716789B2

Abstract

A subterranean incineration system involves a receiving station (A) feeding material via a shredder (B) to a subterranean shaft (C) which is vented to atmosphere at (V). The shaft (C) connects with a substantially horizontal tunnel (T) at a lower end thereof with the horizontal tunnel in turn terminating with an opening (U) to atmosphere. Combustion occurs within the vertical shaft (C). An inner section of the charge tunnel (B) can also be used for drying or pre-combustion of the refuse material fed to shaft (C). Residual matter can be removed via the lower horizontal tunnel (T).

Description

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REFUSE DISPOSAL METHODS AND APPARATUS

TECHNICAL FIELD OF THE INVENTION

This invention relates to refuse disposal methods and installations for disposal of refuse.

BACKGROUND

There is a growing need to provide alternatives to conventional refuse disposal methods and apparatus such as land-fills or reclaim methods. In particular there is a need for environmentally acceptable apparatus and methods of refuse disposal and re-cycling.

OBJECT

An object of this invention is to provide such a method and apparatus for the disposing and/or re-cycling of conventional domestic and commercial refuse.

STATEMENT OF INVENTION

The method involves disposal, at least in part, of the refuse by combustion within a naturally occurring site and it is envisaged that part of the heat generated will be utilised for pre-combustion and/or drying of the refuse in situ and otherwise could be harnessed for useful purposes.

According to a first aspect of this invention there is provided a method of refuse disposal broadly comprising the steps of forming in a naturally occurring site a substantially vertical shaft vented to atmosphere at an upper section thereof and conjoining with a substantially horizontal tunnel at a lower end thereof with the horizontal tunnel in turn terminating with an opening to atmosphere, forming combustion means within the vertical shaft conjoining with a substantially horizontally extending charge tunnel with an inner section of the charge tunnel forming a pre-combustion chamber whereby refuse may be charged into the combustion zone of the shaft via the charge tunnel for disposal by combustion therein with residual matter removed via the lower horizontal tunnel.

According to a second aspect of this invention there is provided a method of refuse disposal broadly comprising the steps of forming in a naturally occurring site a substantially vertical shaft vented to atmosphere at an upper section thereof and conjoining with a substantially horizontal tunnel at a lower end thereof with the horizontal tunnel in turn terminating with an opening to atmosphere, providing a cyclonic combustion device within the shaft and providing a substantially horizontally extending charge tunnel conjoining with the shaft part-way up the length thereof and disposed to feed refuse from the charge tunnel to the combustion device, an inner section of the charge tunnel forming a pre-combustion chamber.

According to a further aspect of this invention there is provided a method of refuse disposal as described in either of the two preceding paragraphs characterised in that a limited combustion step is included to achieve a substantially homogeneous coked mixture and thereafter the mixture is vibrated to separate at least some of the calcineated material therefrom.

DRAWINGS

In further describing the invention reference is made to the accompanying drawing in which Figure 1 is a vertical sectional view through a site.

While the drawing depicts a single vertical plane this is for ease of understanding as the layout as hereinafter described could be arranged in a multitude of vertical planes and thus in this respect and others the drawing is to be considered schematic.

In the preferred embodiment a refuse disposal apparatus is installed and/or otherwise constructed in an naturally occurring mound such as a hill or part of a hill W. The installation essentially comprises a series of underground shafts and tunnels, more particularly described hereinafter, in which refuse can be incinerated at substantial temperatures providing acceptable emission control levels.

A main vertical shaft I is provided with a lower end of the shaft I conjoining with a substantially horizontally extending tunnel T. Tunnel T is bored or otherwise suitably formed from a convenient lower and laterally disposed point U of the mound W to intersect with and preferably extend passed the lower end of shaft I.

Preferably adjacent the top and in essence forming the top, of the shaft I a transverse tunnel O is formed. Transverse tunnel O intersects the shaft I and vents to atmosphere, preferably at several outlets V each preferably controlled such as by way of adjustably opening lids, depicted schematically on the drawing. Thus the transverse tunnel O provides an exhaust from the shaft I. As discussed hereinafter the arrangement enables the emissions to be directed as required including servicing of one section while another is being utilised.

An access feeder tunnel B is provided in a generally horizontal disposition to conjoin with the vertical shaft I part-way there up. Preferably a refuse receiving station A is provided at the entry to tunnel B. Preferably a worm-screw (not depicted) or similar conveyor means can be included to charge the refuse along the access tunnel B to the combustion zone C in so doing forming a low pressure air-lock.

A section of the access tunnel B preferably an inner section B2 provides a pre-combustion or drying zone in which refuse can be dried prior to complete charging into the vertical shaft I for combustion therein. To that end a pre-combustion tube B3 can be disposed essentially axially along section B2 and through which refuse can be charged into the vertical shaft I. Heat from the shaft I is thus able to circulate about tube B3 to dry refuse therein.

In a preferred embodiment the shaft I houses a cyclonic furnace H in the lower section thereof. The furnace H is disposed adjacently below a junction of shaft I with a horizontal shaft E to receive coked material from the latter as described hereinafter. The cyclonic furnace H is disposed with an outlet hopper K lowermost to receive non-combustible matter therethrough. Hopper K feeds scrap material to skips operating in tunnel T. In providing the furnace H is disposed lower than the charge tunnel E heated gasses given off at the combustion stage are utilised in the drying and coking stage.

Tube B3 extends through shaft I and therebeyond in so doing creating a gas and coke producing as well as drying zone about main combustion zone C. An outlet D is provided from tube B3, outlet D depositing coked material and other matter into a horizontal shaft E extending from the lower section of shaft I.

The drying and coking zone B2 and B4 provides a limited combustion step. The limited combustion is such that the charring or pyrolytic coking of many materials such as common metals, plastics and glass within a charge of refuse is achieve by way of complete combustive destruction. The resultant homogeneous coke mixture is subsequently vibrated such as by passing it through a hammer mill positioned in shaft E. The action of the hammer mill breaks up the mixture, with the destructive effect on the more combustible materials being substantially more pronounced than that on the materials that have merely charred or been reduced to a calx. Suitable separation means such as a cyclonic separator are preferably provided to direct the combustible material from shaft E to furnace H for complete combustion. Calxed material is directed via a second hopper K (depicted at the right hand end of tunnel T) to the skips operating in tunnel T. A further hopper K can be provided connecting the receiving station A to tunnel T enabling pre-sorting of, for example, metal scrap at the outset.

Preferably an angled shaft G is provided between a lower section of the vertical shaft I and an entry A of the access tunnel B to provide an air duct to furnace H. Preferably a further duct F is provided to the side B4 of tube B2.

Access roads (not depicted) are preferably provided to the various tunnel mouths whether they be entry or exit mouths of the installation enabling ready access of vehicles to and from the installation. Thus refuse can be deposited in the access tunnel B and following drying and/or pre-combustion therein charged into vertical shaft I.

Preferably emitted gases are collected and directed through the combustion zone C.

That section forms the main combustion zone with combustion taking place therein with primary air being drawn in via the lower tunnel T up through the shaft I and emission taking place via one or other of the transverse tunnel V. Preferably filters M and/or scrubbers N are provided to provide an environmentally benign emission. Such filters M may incorporate limestone, expanded clay and/or charcoal and may involve a garden or similar bio-regeneration system with an overlay of natural growth possibly provided in a green-house Q. Vents P are preferably provided to control emissions to green-house Q. Further, a recycling duct R may be provided to return emissions for additional purification if need be.

It is envisaged that sufficient heat will be generated to achieve acceptable levels of emission and excess heat harnessed in any suitable such as via steam generation through boilers or similar units being incorporated into the installation, such as at J, to drive electrical generators or other energy conversion means. The lower tunnel T will provide an ashpit and ash removal means. To that end a heavy metal recovery plant U may be provided at the entry to tunnel T.

With collection mineral concentrates may be extracted and other ash used in concrete mixers such as the manufacture of breeze blocks.

Thus, a refuse disposal method and installation is provided which is not unsightly and in particular self contained reducing the likelihood of accidental dispersal of the refuse such as by inclement weather. Further it is envisaged that operational costs and maintenance costs will be substantially less than traditional land-fill methods and further the method is not limited to a finite life period such as with a land-fill method.

Claims

CLAIMS:

1. A method of refuse disposal comprising the steps of forming in a naturally occurring site a substantially vertical shaft vented to atmosphere at an upper section thereof and conjoining with a substantially horizontal tunnel at a lower end thereof with the horizontal tunnel in turn terminating with an opening to atmosphere, forming combustion means within the vertical shaft conjoining with a substantially horizontally extending charge tunnel with an inner section of the charge tunnel forming a pre-combustion chamber whereby refuse may be charged into the combustion zone of the shaft via the charge tunnel for disposal by combustion therein with residual matter removed via the lower horizontal tunnel.

2. A method of refuse disposal comprising the steps of forming in a naturally occurring site a substantially vertical shaft vented to atmosphere at an upper section thereof and conjoining with a substantially horizontal tunnel at a lower end thereof with the horizontal tunnel in turn terminating with an opening to atmosphere, providing a cyclonic combustion device within the shaft and providing a substantially horizontally extending charge tunnel conjoining with the shaft part-way up the length thereof and disposed to feed refuse from the charge tunnel to the combustion device, an inner section of the charge tunnel forming a pre-combustion chamber.

3. A method of refuse disposal as claimed in either of the two preceding claims characterised in that a limited combustion step is included to achieve a substantially homogeneous coked mixture and thereafter the mixture is vibrated to separate at least some of the calcineated material therefrom.

4. A method of refuse disposal as claimed in any one of the preceding claims wherein conveyor means are included to charge the refuse along the access tunnel in so doing forming a low pressure air-lock.

5. A method as claimed in any one of the preceding claims wherein the pre-combustion chamber is formed by a tube disposed essentially axially along at least the inner section of the access tunnel and through which refuse can be charged to the shaft.

6. A method as claimed in any one of the preceding claims wherein the combustion means comprises a cyclonic furnace.

7. A method as claimed in claim 6 wherein the furnace is disposed in a section of the shaft lower than the intersection of the junction of the access tunnel with the shaft.

8. A method as claimed in claim 7 when dependent on claim 5 wherein the tube extends beyond the shaft in so doing creating a gas and coke producing as well as drying zone and an outlet is provided from the inner end of the tube, the outlet enabling the depositing of coked material and other matter therefrom into a horizontal shaft extending from the lower section of vertical shaft.

9. A method as claimed in claim 8 wherein matter is feed from the horizontal shaft to the furnace.

10. A method as claimed in either claim 8 or claim 9 wherein ducts are provided between the lower section of the vertical shaft and the tube.