WO2014054006A1

WO2014054006A1 - Incinerator for burning explosive material

Info

Publication number: WO2014054006A1
Application number: PCT/IB2013/059069
Authority: WO
Inventors: John Reid
Original assignee: Calordomus Limited
Priority date: 2012-10-02
Filing date: 2013-10-02
Publication date: 2014-04-10
Also published as: GB201217590D0

Abstract

An incinerator is described for burning explosive material recovered from a munition. The incinerator comprises a continuous conveyor 10 guided over idlers that are rotatable about a generally horizontal axis and a plurality of trays 12 suspended from the conveyor 10 in such a manner as to remain horizontal at all times. The conveyor 10 has an upper run 30 disposed within an incinerator chamber 22 within which explosive material loaded unto the trays 12 at a loading station 28 is burnt and a return run 32 disposed outside the incinerator chamber within which the trays 12 are cooled and returned to the loading station 28 to receive a fresh charge of explosive material.

Description

INCINERATOR FOR BURNING EXPLOSIVE MATERIAL

Field of the invention

The present invention relates to an incinerator for burning explosive material recovered from munitions.

Background of the invention

During the disposal of munitions, shells are opened and explosive material is extracted from them in a suitable manner. In GB patent applications 1118052.8 and 1118057.7, the present Applicants have disclosed how shells may be opened safely and how they may be emptied of explosive material. The shells can be recycled and in certain

situations it may be possible to recycle some of the

explosive material. However, there remains a need to dispose of explosive material on certain occasions, for example if there is a risk of it having become unstable or to prevent its use in illicit operations.

It is known that explosive material can be burned without risk of explosion provided that the maximum

thickness of the explosive material does not exceed a certain limit that is estimated using the critical diameter of steel sleeve test, sometimes also referred to as the Koenen test. This limit depends on the composition of the explosive material.

It had been proposed to shred the explosive material to below this thickness and to drop it through an incinerator having a vertical combustion chamber. This proposal, however, has the disadvantage that the explosive material is introduced directly into the hottest region of the

combustion chamber and can turn to a gas that rises and can then condense in a cooler area and subsequently explode. Summary of the invention

According to the present invention, there is provided an incinerator for burning explosive material recovered from a munition, comprising a continuous conveyor and a plurality of trays attached to the conveyor in such a manner as to remain horizontal at all times, wherein the conveyor has an upper run disposed within an incinerator chamber within which explosive material loaded unto the trays at a loading station is burnt and a return run disposed outside the incinerator chamber within which the trays are cooled and returned to the loading station to receive a fresh charge of explosive material.

In an embodiment of the invention, the conveyor has a first horizontal section serving as the loading station, an upwardly inclined or vertical section leading from the loading station to the upper run that is disposed within the incinerator chamber, and a downwardly inclined or vertical section within which the trays are lowered from the

incinerator chamber to the return run.

The trays may be generally flat and may have a

surrounding lip delimiting the maximum depth of explosive material that may safely be loaded onto the trays.

Conveniently, a flue is provided at the upper end of the incinerator chamber. In this way, an up-draught of air into the incinerator chamber created by the combustion within the incinerator chamber serves to cool the trays attached to the inclined or vertical sections of the

conveyor .

Embodiments of the invention offer the advantage that the explosive material is loaded on the trays within a low temperature loading station where the maximum depth of explosive material loaded onto each tray can be controlled. This ensures the safety of personnel loading the explosive material as the low temperature and the controlled depth of the explosive material avoid any risk of premature

combustion or explosion. The explosive material is then transported by the conveyor by the upwardly inclined section to the incinerator chamber were combustion takes place.

It is preferable for the upwardly inclined section of the conveyor to be vertical or steeply inclined so as to ensure a large vertical separation between the incinerator chamber and the loading station without unnecessarily increasing the horizontal size of the incinerator.

The fact that the combustion region of the incinerator chamber is arranged vertically at some height above the loading station and the return run of the conveyor ensures that a vigorous up-draught of air is created leading up to the incinerator chamber to cool the trays outside the incinerator chamber.

The trays may additionally be cooled by spraying them with a liquid, such as water, while they are travelling along the return run of the conveyor. If a pressurised spray is used, it may additionally serve to clean the trays by dislodging any combustion product that may adhere to the trays. As an alternative, the tray can run through a bath of water and be scrubbed with brushes.

It is generally important to avoid mixing water with the explosive material as this creates so-called pink water, disposal of which presents difficulties. However, the use of a pressure jet of water to clean the trays and cool them before they return to the loading station does not create pink water as the explosive material will have already been completely burnt. One can safely dispose of, or reuse, such water. If necessary, it may first be passed through a suitable filter to remove any combustion products. Though at least one gas or oil burner is required within the incinerator chamber to initiate combustion of the explosive material, the burning of the explosive material is itself an exothermic reaction that generates a substantial amount of heat and the burner may be extinguished once ignition of the explosive material has commenced.

To avoid the heat generated by burning the explosive material from being wasted, a heat exchanger may be disposed within the upper region of the incinerator chamber or the flue, to heat a fluid from which the heat energy may be recovered to generate mechanical or electrical power. Thus, for example, the heat may be used to convert water to steam which may then drive a steam turbine.

To minimise atmospheric pollution, the combustion gases discharged through the flue may be filtered, scrubbed or treated before being discharged.

Brief description of the drawings

The invention will now be described further, by way of example, with reference to the accompanying drawings, in which

Fig. 1 is a schematic vertical section through an incinerator of the invention, and

Fig. 2 is a perspective view of one of the trays suspended from the conveyor in Fig. 1.

Detailed description of the preferred embodiment

Fig. 1 shows a conveyor 10 from which trays 12 are suspended in such a manner as to remain horizontal at all times. One of the trays 12 is shown in perspective view in Fig. 2, in which it can be seen that the tray 12 has a shallow recess 14 and arms 16 on each side by which it is pivotably suspended from the conveyor 10. The conveyor 10 is formed by two spaced apart chains guided over idler sprockets that are not shown in the drawing, the two chains being driven to rotate in unison, in a clockwise direction is viewed in Fig. 1.

The conveyor 10 is used to transport the trays 12 through an incinerator 20 having an incinerator chamber 22 within which there is disposed a gas or oil burner 24. In addition to the part of the conveyor 10 that passes through the incinerator chamber 22, the conveyor 10 includes a horizontal section 26 that transports the trays 12 through a loading station 28 where the trays are charged with an explosive material to be burned within the incinerator.

The conveyor 10 has two main runs, namely a generally horizontal upper run 30 disposed within the incinerator chamber 22 above the burners 24 and a lower horizontal run 32, arranged outside the incinerator chamber, that acts as a return run for transporting the trays 12 back to the loading station 28. Above the return or lower run 32, there is disposed a jetting system 34 that directs jets and/or a spray of water onto the trays 12.

In order to achieve a significant separation between the upper and 30 and the lower run 32, the conveyor includes a steeply upwardly inclined section 36 that leads from the loading station 28 to the upper run 30 and a second

downwardly inclined section 38 that lowers the trays back to the level of the lower run 32. The inclined sections 36 and 38 may be vertical.

The direction of the air currents flowing through the incinerator chamber 22 is indicated in Fig. 1 by arrows 50. It can be seen that ambient air enters from beneath and is guided to flow over the inclined or vertical sections 36, 38 of the conveyor lower towards the incinerator chamber 22 before being discharged through a flue 52. This ensures that high temperatures generated in the incinerator chamber 22 are confined within the chamber 22. The trays 12 are cooled by this up-draught while being transported along the

upwardly inclined section 36 22 so that premature ignition of the explosive material does not take place before the trays reach the incinerator chamber 22 and they are also cooled immediately after leaving the incinerator chamber while travelling along the downwardly inclined section 38.

The drawing also shows that a filtration system 54 is disposed in the path of the flue gases to clean them before they are discharged to atmosphere. The filtration system may include a gas scrubber or other treatment system to clear the gases before they are discharged.

In operation, explosive material is loaded onto trays 12 within the loading station 28. The shallow recess 14 in the trays provides an indication of the maximum depth to which the trays can be loaded in order to avoid the risk of an explosion within the incinerator chamber 22. A scraper 60 may be disposed in the loading station to wipe across the upper surfaces of the trays 12 and thereby ensure that the explosive material does not exceed a safe thickness.

The explosive material loaded onto the trays is next transported to the incinerator chamber 22 where it is burnt using the heat generated by the burners 24. As the burning of the explosive material itself generates heat, the burners 24 can be extinguished once combustion has commenced. To take advantage of the energy released by the combustion, a heat exchanger 40 is disposed within the upper end of the incinerator chamber 22 that acts as a steam generator. The steam in turn drives drivers a turbine to generate

electricity or mechanical power needed for the operation of the munition disposal plant. After the explosive material has been burnt, the trays then descend along the section 38 of the conveyor to reach the lower horizontal run 32. The combustion taking place within the incinerator chamber 22 generates a substantial up-draught of air which, which is used to cool the trays 12 as they move back towards the loading station 28. The up- draught also raises the temperature within the incinerator chamber to improve the combustion quality. This ensures total burning of the explosive material and reduces

impurities in the flue gases.

During their return to the loading station 28, jets of water are directed on to the trays 12, both for the purpose of cooling them and of dislodging any ash or other

combustion residue adhering to them. In this way, on their return to the loading station 28, the trays are both clean and cold and ready to receive a fresh charge of explosive material .

The water used to cool and clean the trays is collected in a drainage system and filtered to remove any ash or combustion residue. The cleaned water may then be reused or disposed of safely.

Claims

1. An incinerator for burning explosive material recovered from a munition, comprising a continuous conveyor and a plurality of trays attached to the conveyor in such a manner as to remain horizontal at all times, wherein the conveyor has an upper run disposed within an incinerator chamber within which explosive material loaded unto the trays at a loading station is burnt and a return run

disposed outside the incinerator chamber within which the trays are cooled and returned to the loading station to receive a fresh charge of explosive material.

2. An incinerator as claimed in claim 1, wherein the conveyor has a first horizontal section serving as the loading station, an upwardly inclined or vertical section leading from the loading station to the upper run disposed within the incinerator chamber, and a downwardly inclined or vertical section within which the trays are lowered from the incinerator chamber to the return run.

3. An incinerator as claimed in claim 1 or 2, wherein the trays are generally flat and have a surrounding lip delimiting the maximum depth of explosive material that may safely be loaded onto the trays.

4. An incinerator as claimed in any of claims 1 to 3, wherein a flue is provided at the upper end of the

incinerator chamber.

5. An incinerator as claimed in any of claims 1 to 4, wherein jets are provided to cool the trays by spraying the trays with a liquid while they are travelling along the return run of the conveyor.

6. An incinerator as claimed in claim 5, wherein the jet are operative to spray liquid onto the tray with sufficient pressure to dislodge any combustion products may adhering to the trays .

7. An incinerator as claimed in any of claims 1 to 6, wherein at least one gas or oil burner is provided in the incineration chamber for initiating combustion of the explosive material on the tray.

8. An incinerator as claimed in any of claims 1 to 7, wherein a heat exchanger is disposed within the upper region of the incinerator chamber or the flue, to heat a fluid.

9. An incinerator as claimed in any of claims 1 to 8, wherein a filter or treatment device is provided cleaning gases exhausted from the incineration chamber.