EP0663991B1 - Waste incineration apparatus and plant - Google Patents

Abstract

The apparatus comprises a hearth (2) provided with a loading opening, a combustion grid (8) disposed in the stove bottom, an air inlet opening and a combustion gas chimney, with the outlet being connected to the stove's upper portion. The invention is distinctive in that the chimney (3) is fitted with a combustion gas outlet manifold (34) oriented downwards, with its lower end opening to the exterior. The manifold contains a water diffuser (6) which is also oriented downwards.

Description

The subject of the present invention is a waste incinerator apparatus, as well as an incineration installation equipped with such an apparatus.

The invention relates in particular, but not exclusively, to an incinerator intended for use on ships.

International regulations prohibit the discharge into the sea of most of the waste produced by ships, in particular household waste, plastic packaging and bottles, oil residues, oily rags used to clean the machines, etc.

It should be noted that the nature of this waste is very heterogeneous, and certain materials burn and are eliminated by incineration much more easily than others.

Some vessels have specific waste incineration equipment. These devices are extremely sophisticated and expensive, and often difficult to use and maintain, so they are rarely used in practice. In addition, this type of device rejects opaque and polluting fumes, the combustion of materials being generally poor and incomplete.

On ships that do not have this kind of device, incineration is often done in simple metal drums. In this case the incineration is poor. In addition, the operation is extremely dangerous, hot fumes and incandescent particles that can freely escape from the barrel, and therefore constituting causes of fire. This is of course inadmissible, in particular on ships which transport flammable products.

This is why, the objective of the present invention is to propose an apparatus and an incineration plant which, while being simple in design and of a low cost price, are easy to use and allow to burn with a high efficiency and without danger of fire of materials, even motley.

It should be noted that document FR-A-1 231 446 describes a heating device which also performs an incinerator function. The appliance comprises a hearth provided with an opening for loading the waste to be incinerated, an air intake opening, a combustion grate disposed at the bottom of the hearth, and an exhaust chimney vertical. This is connected to the upper wall of the fireplace and opens into the atmosphere, upwards.

The device is equipped with electrically controlled fans, whose role is to improve the draft, and therefore to carry out an efficient and complete incineration.

Unfortunately, this known device does not solve the problem of lack of security which has just been mentioned, the escape of hot smoke and incompletely extinguished by the chimney to the outside is still possible. In addition, the presence of electric fans increases the cost price of the device.

In document US-A-2 194 490 is described an incinerator device comprising electrical combustion means, which is mounted on a sanitary installation. The burnt gases are evacuated through a bent pipe forming a siphon (in English "trap") to a waste water evacuation pipe.

At the upper part of the siphon, upstream side, opens a water injection nozzle, the function of which is to create suction in the duct, and thus to suck the gases out of the device. Theoretically, these gases then pass through the siphon, to the wastewater discharge pipe. In it, the water will naturally descend by gravity to the sewer system, while the gases will escape upwards to join the atmosphere. The pipe is therefore open at its upper end, thus playing the role of a conventional chimney.

In principle, this device is attractive, since the suction effect of the water injection nozzle is supposed to improve the draft and the evacuation of smoke.

Unfortunately, such an installation cannot function in practice because the volume of water which necessarily occupies the lower part of the siphon prevents the passage of gases. It should be noted that this device does not have a downward facing chimney. It is fortuitously, as a result of the presence of the siphon, that part of the gas passage duct is directed downward, forming the upstream branch of the "U" constituting the siphon. As explained above, the exhaust gas chimney is pointing upwards.

Document FR-A-1 170 060 also discloses a device for washing and cooling the burnt gases of a gas water heater. This known device comprises a suction pipe for burnt gases, the inlet of which is positioned above the chimney of the water heater, at a certain distance from the latter. In the elbow of the suction pipe is mounted an injector of water spray capable of sucking the burnt gases with ambient air in the pipe then washing, cooling and driving the burnt gases down, in the vertical part pipe.

However, this device has no influence on the pressure prevailing in the combustion chamber of the water heater and has no effect on the draft.

The waste incinerator which is the subject of the invention is of the same general type as that described in the document FR-A-1 231 446 cited above.

It includes a hearth provided with a loading opening, a combustion grate arranged at the bottom of the hearth, an air intake opening, and a chimney for evacuating burnt gases, the mouth of which is connects to the upper part of the fireplace.

This device is remarkable by the fact, on the one hand, that the chimney comprises an exhaust pipe for the burnt gases which is directed downwards and which opens to the outside via its lower end, and, on the other hand, that this tubing is internally equipped with a water diffuser also directed downwards.

Thus, this diffuser fulfills a double function.

The first of these functions is to create a depression in the hearth relative to atmospheric pressure, which ensures a natural entry of combustion air through the air intake opening and prevents hot gases from leaving through the covers of the fireplace loading and cleaning openings, which are not necessarily tightly closed. This depression of the hearth ensures good draft, allowing efficient and complete combustion of the waste. All the hot gases, including the incandescent particles in suspension, are attracted by the suction effect in the chimney, preventing leaks, which are sources of danger.

The second function of the internal water diffuser is to extinguish the incandescent particles present in the burnt gases, to cool and wash the fumes, so that the burnt gases escaping from the appliance are not very polluting and cold or lukewarm .

In this regard it should be noted that the inverted arrangement of the chimney thwarts the exhaust of still hot gases, since these have a natural tendency to rise.

Furthermore, the features of the invention are defined in claim 1.

The waste incineration plant according to a preferred embodiment of the invention comprises an apparatus as described above. It includes means to recover the water released at the outlet of the chimney, to purify it and to bring it back to the diffuser according to a closed circuit.

It should be noted that it is known per se to purify and then reuse, in systems working in a closed circuit, water for washing burnt gases (see for example EP-A-0 152 061).

Other characteristics and advantages of the present invention will appear from the description and the appended drawings which represent a preferred embodiment thereof.

• la figure 1 est une vue éclatée, en perspective, de l'appareil ;
• la figure 2 est une vue en coupe transversale par un plan vertical passant par l'axe de la cheminée de l'appareil de la figure 1 ;
• la figure 3 est une vue de détail, en coupe axiale, du diffuseur d'eau ;
• la figure 4 est une vue schématique qui illustre le fonctionnement d'une installation conforme à l'invention.

In these drawings:

• Figure 1 is an exploded perspective view of the apparatus;
• Figure 2 is a cross-sectional view through a vertical plane passing through the axis of the chimney of the apparatus of Figure 1;
• Figure 3 is a detail view, in axial section, of the water diffuser;
• Figure 4 is a schematic view which illustrates the operation of an installation according to the invention.

The waste incinerator device, referenced 1, shown in FIGS. 1 and 2 comprises a box 2 of generally rectangular parallelepiped shape, for example cubic, with double wall, constituting the hearth of the device.

Its walls, both interior and exterior, are made of sheets of refractory steel sheet assembled by welding. The internal faces of the internal walls are coated with a refractory material not shown in FIG. 1 and referenced 26 in FIG. 2. This is for example an assembly of refractory bricks making it possible to obtain a high temperature of the hearth, for good incineration.

In the figures, the internal plates constituting the hearth are referenced 20 to designate the horizontal upper wall, 21 to designate the side and front and rear walls, 23 for the bottom wall.

The external wall elements are designated 40 for the side plates, 41 for the front and rear plates, 42 for the upper plate.

The box is supported by four feet 22 (only one of which is shown in Figure 1) which allow it to be supported on a plane S.

Appropriate spacers 210 maintain the desired spacing between the inner and outer wall elements, providing a peripheral space into which air can enter from below. The upper internal 20 and external 42 plates respectively have an opening 200 and a notch 420 coming in correspondence with the opening 200, to allow the introduction of the waste to be burned in the hearth. A cover 43 is provided for closing the opening 200 during use.

At the base of the hearth is provided a combustion grate 8 intended to receive the waste to be burned. This is supported by side angles 80 (of which only one is shown in Figure 1). The angles 80 are preferably reversible and adjustable in height. The front wall of the hearth is provided, in the lower part, with a cover 7 for cleaning the hearth, which is held in place by a crosspiece 72 and clamping screws 73.

The combustion air enters naturally through an opening 70 made in the cover 7. A sliding shutter 70 makes it possible to adjust the air flow entering the hearth by more or less discovering the opening 70.

The opening 70 is located below the level of the grid 8. At the bottom of the hearth, an opening 74 fitted with a flap 75 allows the evacuation of the ashes and other residues.

The device is equipped with a chimney 3 for evacuating the burnt gases.

It is a cylindrical tube having the general shape of an inverted "J".

The tube is formed of sections 30, 31, 32, 33 and 34 fixed to each other by welding.

The section 30 is a straight sleeve of short length disposed vertically and the base of which passes through circular openings in the plates 20 and 42. The sleeve 30 is welded to each of these plates, to open into the hearth.

At the upper end of the sleeve 30 is welded a first bend 31 which describes an angular sector of 90 °. This elbow is itself connected to a substantially horizontal rectilinear sleeve 32 which extends laterally, towards one of the sides of the hearth. Its length is sufficient for its opposite end to reach beyond one of the side walls 40 of the hearth.

The sleeve 32 is itself fixed by welding to a second elbow 33 which also describes an angular sector of 90 °, and the mouth of which is directed downwards.

To this mouth is welded a tube 34 of vertical axis. The length L1 of the latter is of the same order of magnitude, and preferably slightly greater than the height L2 of the hearth (see FIG. 2).

The top of the second elbow 33 has an opening, around which a small sleeve 35 is welded, coaxial with the pipe 34. This sleeve receives a system for supplying and diffusing water into the chimney.

The system comprises a supply duct 5, the end of which carries a fitting socket 50 fitted and fixed in the sleeve 35. At its free end is screwed a doubly threaded ring 51 in which a diffuser member 6 is fixed.

Figure 3 is a detailed view of the diffuser 6. It comprises a hollow body 60 screwed into the ring 51. The body 60 has two bores 61, 62 connected by channels 64 allowing the passage of water from the upper bore 61 to lower bore 62. The lower bore 62 opens downwards through a divergent conical chamfered wall 63. In the central part of the body 60 which separates the bores 61 and 62 is screwed an axial threaded rod 66.

This rod extends downward into the bore 62 and outside the body 60. It receives a spraying member constituted by a frustoconical nut 65, the angle of which at the top of the conical wall corresponds to that of the chamfer 63.

By screwing more or less the member 65 on the rod 66 we can bring more or less one of the other the two conical walls, and therefore vary the gap 620 which separates them. Nuts 67, 68 which act as lock nuts, prevent the screw 66 and nut 65 from being adjusted.

The water which is brought by the conduit 5 to the diffuser 6 will therefore cross the channels 64 to come and occupy the bore 62 from which it will escape in the form of rain, according to a conical jet.

This rain will descend inside the tube 34, over the entire length L1.

The fineness of the water droplets will depend on the passage section corresponding to the gap 620, and therefore on the height adjustment of the member 65.

Inside the hearth is arranged a sprinkler ramp 25 supplied with water by a supply duct 250. The ramp 25 extends horizontally in the upper part in the central region of the hearth.

Its role is to allow rapid extinction of the combustion materials inside the hearth, in the event of danger, by opening a control valve (not shown).

We will now explain how this device works.

The waste to be burned is introduced into the hearth through the opening 200, and comes to rest on the combustion grate 8. The materials are ignited, possibly using an auxiliary fuel for starting the operation.

The cover 43 being put in place to close the opening 200, the combustion air arrives in the hearth from below the grate, through the adjustable opening 70.

During operation, pressurized water is supplied to the diffuser 6, using an appropriate pump, as symbolized by the arrow G in FIG. 2.

As already said, the water leaves the diffuser 6 in the form of rain droplets which are sprayed at the upper end of the tube 34.

This diffusion, which takes place permanently, causes a suction upstream of the tubing, that is to say in the parts 33, 32 31 and 30 of the tubing. This suction is favorable for the evacuation of burnt gases, which enter the chimney as symbolized by the arrows F in FIG. 2.

The depression of the hearth also favors the admission of air, through the opening 70, and makes it possible to obtain an excellent draft, conducive to a complete combustion of all the materials, even slightly inflammable, placed on the grid.

The smoke stream entering the chimney generally carries glowing particles in suspension.

During their downward path in the tubing 34, these particles will be quenched by the water droplets emitted by the diffuser 6 inside the tubing.

The water droplets also cool and wash the fumes.

Given the relatively large length L1 of the tubing, it is ensured that the mixture of water and gas which opens into the atmosphere at the base of the tubing 34, symbolized by the arrows I in Figure 2, is at a relatively low temperature and no longer contains glowing particles. This mixture is therefore unable to start a fire.

During operation, cold air can freely penetrate from below, between the internal and external walls of the box constituting the fireplace. The external wall elements are thus kept at a moderate temperature, ensuring protection against burns by contact.

This air for cooling the walls rises towards the upper part of the hearth and is then evacuated by suitable openings, for example by the notch 420 placed above the cover 43.

Optionally, this hot air can be captured for subsequent use.

FIG. 4 schematically represents a waste incineration installation using an apparatus 1 of the type described.

In this installation the water is diffused in the chimney and recovered and recycled after treatment, that is to say returned to the diffuser 6.

The chimney 3 opens into a tower 9 for separating the smoke and the water. At the base of the tower is a deflector cone 90. The washed fumes escape from the tower 9 through a chimney 910, as symbolized by the arrow J.

The recycling circuit 900 is equipped with a pump 93 ensuring the circulation of the water taken from the tower 9 to bring it to the diffuser 6.

On this circuit is installed a purification device 91. It is for example a centrifugation device which separates the liquid and solid particles.

Then the water passes through a cooling device 92. It is a heat exchanger. The water, still lukewarm, is for example exposed to a jet of cold air A produced by a fan.

Finally, before arriving at the diffuser 6, the water passes through a filter 94 which perfects the purification.

Addition of water and treatment products can be added to the circuit, for example in tower 9, as symbolized by the arrows B1 and B2.

It goes without saying that it is possible to equip the apparatus and the installation which have just been described with servo-control means.

Thus, the adjustment of the combustion air flow can be carried out automatically by a regulation system acting on the flap 71 as a function of the temperature of the flue gases.

The extinction of the hearth by the ramp 25 can be triggered automatically if the operating conditions become abnormal, for example if the supply of water to the diffuser is done incorrectly.

Mechanical ventilation or smoke extraction systems can be added.

In a variant, it is possible to provide several water diffusion systems at the top of the tubing 34. Thus, the diffuser could for example have two cones 65 placed one above the other.

Such an apparatus is particularly suitable for maritime applications, in particular for equipping merchant ships. However, it goes without saying that its use is not limited to this kind of application. It can also be used for industrial and domestic purposes, or for communities, for example in hospitals.

Claims (4)

1. Waste incinerator apparatus which includes a furnace body (2) provided with an opening (200) for charging, a combustion grate (8) arranged at the bottom of the furnace body, an air inlet opening (70) and a flue (3) for evacuating the burnt gases, the mouth (30) of which flue is joined to the upper part of the furnace body, characterized in that the said flue (3) is formed by four successive sections comprising, from the furnace body (2) to the outside:

   - a substantially vertical straight tube (30) which is joined to the upper wall (20) of the furnace body (2);

   - a first elbow (31) describing a 90° angular sector;

   - a substantially horizontal straight tube (32);

   - a second elbow (33) describing a 90° angular sector;

   - a vertical pipe (34) which constitutes a burnt-gas exhaust outlet which opens at its bottom end to the outside, the length (L1) of which point is greater than or equal to the height (L2) of the furnace body (2);

      and in that it includes a water atomizer (6) which is fitted internally at the top part of the pipe (34) and is designed to spray water droplets in the form of a conical jet of rain directed downwards inside the said pipe (34).
2. Apparatus according to Claim 1, characterized in that the furnace body (2) is double-walled (21-40; 20-42), the space between the walls allowing circulation of air in order to refrigerate the furnace body.
3. Apparatus according to Claim 1 or 2, characterized in that the said water atomizer (6) comprises a hollow body (60) with a chamfered base, and a conical-walled spray nozzle (65) whose vertical position may be adjusted.
4. Waste incineration plant which includes an apparatus (1) in accordance with one of the preceding claims, characterized in that it includes means (9, 91, 92, 93, 94) for recovering the sprayed water exiting the flue (3), in order to purify it and to return it to the atomizer (6) along a closed circuit.

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