EP0834042B1 - Method and incinerator for incinerating hospital waste and the like - Google Patents

Description

The present invention relates to a method and a incinerator for environmentally friendly incineration hospital waste and other solid waste containing fuel.

Waste disposal must ensure total incineration of fuel at high temperature, non-combustible residues and fumes to be free from germs, hazardous compounds and odors. Currently, most of the waste hospital is cremated with household waste in incineration plants. This process has the disadvantage of presenting a great risk of contamination during waste transportation contaminated dangerous, or to incur costs high disinfection before transport.

The incineration of such waste directly on the place of collection (in clinics, hospitals etc ...) could significantly reduce the cost and the risk of contamination linked to transport. However small devices (ovens) for incinerating waste is usually perfectible and does not do not meet the cleanliness requirements of smoke, reliability, and convenience of use. They pollute the environment, especially during on and off, as well as when refill of waste in the oven, due to the significant gas formation caused by inflammation waste and combustion. The functioning of such incinerators can be interrupted by variations in the composition and properties of waste (humidity, ash content, etc.), which leads an increase in harmful releases.

EP-A-0 251 269 describes a method and a apparatus for gasifying solid fuel then burn gaseous gasification products. A gas generator for gasifying fuels solids such as wood, coal, fuels in briquettes, household waste etc ... is followed by burners for the combustion of gaseous products directly after the gasification. To improve the thermal efficiency of fuel combustion mentioned above, the air supplying the gasification zone and the burner is heated with heat given off gasification course. Air heating is ensured by passing primary air and air secondary through passages in a multiple wall of the gasification chamber.

This prior art practically excludes overload when dealing with coal or fuels in briquettes because the fuel continuously feeds the gasification zone, as the quantities previous are consumed in the process of gasification. However the heat transfer to from the gasification area is a drawback of the process because fuels with low power heat (e.g. wet) cannot burn. This leads to conditions on the composition fuel. When the fuel to be treated is composed of waste, it does not regularly supply the gasification zone because due to their low density, the waste loaded in the gasification can adhere to the walls of the chamber. As a result, the fuel feeds the gasification discontinuously and accordingly harmful releases are increased.

FR-A-2 649 782 describes a method intended for exclude environmental pollution, independently operator competence. The ignition stages, pyrolysis, combustion and cooling are ensured in sequence under continuous automatic piloting. The temperature is regulated by automatically controlling the air flow rate and operation of additional gas burners in rooms corresponding to the incinerator. So the overload driven by the introduction of a new batch of waste in the oven is prevented. The purpose of this process is main drawbacks of consuming a lot of energy, to require a complex installation, as well as a additional fuel (natural gas) to maintain the pyrolysis and combustion.

US-A-3,918,373 describes the treatment of waste solids with primary combustion and combustion secondary. The fumes produced by combustion secondary go through heat exchangers which heat the air for primary combustion. This process is complex and relatively inefficient for activate gasification of low-power waste calorific.

DE-C-3 335 537 describes an apparatus for pickling their lacquer objects that are placed in an enclosure including the outer face is exposed to the through gas flow a post-combustion chamber following a chamber combustion equipped with an air inlet and a burner combustible.

The object of the present invention is to ensure ecological incineration of hospital waste and other waste containing fuel, minimizing external heat supply while ensuring stable operation for a wide range of compositions and properties of waste, including wet waste.

• une étape de gazéification, durant laquelle lesdits déchets, en tant que premier composant, sont gazéifiés sous apport d'un agent gazéifiant constituant un second composant,
• une étape de post-combustion pendant laquelle les produits gazeux de l'étape de gazéification, en tant que troisième composant, sont brûlés sous apport d'un gaz oxydant secondaire en tant que quatrième composant,
• transfert de la chaleur produite par ladite étape de post-combustion à au moins une partie de l'un au moins desdits composants avant qu'il soit consommé dans celle correspondante desdites étapes de gazéification et de post-combustion,

   caractérisé en ce que l'étape de transfert est réalisée par contact entre des gaz produits par l'étape de post-combsution et une paroi perméable à la chaleur (24) délimitant une partie au moins de la chambre de gazéification .According to the invention, a method is proposed for incinerating solid waste containing fuel, such as hospital waste, comprising the following steps:

• a gasification step, during which said waste, as the first component, is gasified with the addition of a gasifying agent constituting a second component,
• a post-combustion stage during which the gaseous products of the gasification stage, as a third component, are burned with the addition of a secondary oxidizing gas as the fourth component,
• transfer of the heat produced by said post-combustion step to at least part of at least one of said components before it is consumed in that corresponding to said gasification and post-combustion steps,

characterized in that the transfer step is carried out by contact between gases produced by the post-combsution step and a heat-permeable wall (24) delimiting at least part of the gasification chamber.

According to another aspect of the invention, there is provided a incinerator for implementing the method, comprising a gasification chamber, to contain a first component consisting of waste to be incinerated, means for introduce a gasification agent as a second component in said gasification chamber, a chamber afterburner, means of fluid communication between the gasification chamber and the post-combustion chamber, so as to introduce into the post-combustion a third component consisting of gaseous products from the gasification chamber, admission means for introducing into the post-combustion a fourth component consisting of a gas secondary oxidant, and means for transferring heat from the afterburner to at least one part of at least one of said components upstream of the post-combustion chamber, characterized in that the means for transferring heat includes a wall heat conductor separating the post-combustion chamber a gasification zone of said chamber gasification.

According to the invention, heat generated by the step of afterburner is used to heat directly a wall of the gasification chamber. So the heat transfer takes place with a minimum of losses at all the components involved in the process of gasification, and the chamber wall becomes a means by which the heat arrives.

The heat generated by the post-combustion process is directly used to promote reliable maintenance of the whole process even with power waste relatively low calorific. This avoids as much as possible the need for additional heating capacity. However, in the case of very low-power waste heat, especially wet waste, can be intervene such additional heat, preferably by regulating the additional thermal power in such a way to maintain a minimum gasification temperature and / or post-combustion.

According to one embodiment of the invention, the agent gasification and secondary air which supply the gasification and post-combustion chambers, respectively, or fractions of these when processes relatively high calorific waste dry, are preheated by recovering the heat from the fumes generated in the post-combustion chamber. This recovery is carried out by heat transfer to through walls of gas conduits and / or walls of bedroom. In particular, we can guide the air serving gasification agent and / or oxidizing gas secondary to through a heat exchanger mounted in the afterburner or in a chimney between the post-combustion and exterior. To regulate temperatures in the respective rooms, we can subdivide the air flows so that only one adjustable proportion of primary air (agent gasification) and / or secondary air, respectively, is preheated, while the other parts are directly sent to the rooms.

The contact between the wall of the gasification and post-combustion products can particular be assured by arranging the room gasification so that the region where the area is located gasification at least partially protrudes into the post-combustion chamber.

Gasification and post-combustion processes are controlled by regulating the consumption of the gasification and secondary air and / or redistributing the gasifier and the secondary air between corresponding intake ports, depending on temperatures in the gasification zone and in the post-combustion chamber. Temperatures are maintained within a range whose lower limit is defined by the need to avoid the release of compounds organic, including dioxynes, in dangerous concentrations. The upper limit of temperature is in particular determined by the suitability of the materials constituting the incinerator for resist heat. When the temperature in the gasification zone tends to exceed the limit prescribed, the feed rate of the agent is reduced preheated gasification to reduce the proportion of gasifier preheated in the total gasifier flow. If the temperature in the afterburner exceeds the upper limit, we reduce the air flow secondary preheated for example by redistributing correspondingly the flows towards orifices respective intake of the post-combustion chamber, so as to reduce the proportion of air secondary preheated in total air flow secondary. The aforementioned controls can be provided automatically. The incinerator must then be equipped a control device connected to probes for measure the temperature in the gasification chamber and in the post-combustion chamber, and to means corresponding, such as valves or fans speed-controlled, controlling flow rates corresponding supply and distribution of the gasifier and secondary air to through the intake ports of the the incinerator according to these temperatures. When it comes to treating specific waste which we know are within certain limits composition and properties, this control can however be ensured by initial adjustments in factory, by simple assembly of gas pipes correspondents, having cross sections correlated.

The process can use air as a gasification. However, when dealing with dry waste with high calorific value, we can also inject steam into the gasifying agent of way to reduce the temperature in the area of gasification. The heat needed to produce the steam can be recovered in the fumes.

Successive movement of waste to the area gasification can be obtained by gravity of waste and be favored by a design and a size appropriate gasification chamber, for example by making the gasification chamber flared towards the low, for example in a cone. As a variant, this displacement can be ensured for example by a kind of agitator.

The volume of the post-combustion chamber is chosen so that when the incinerator is operating at its nominal capacity, the retention time of smoke in the room is higher than standard time required and takes place under a temperature and oxygen concentration higher than the values prescribed standards, these retention times, standard temperature and concentration being determined with a view to certain decontamination of the fumes.

We can initiate the process by an impulse thermal applied to waste in the area of gasification and / or gasification agent flow, by means of an additional thermal source, by example an electric heater which is interrupted functioning once the process of gasification has established itself stably. However, especially when dealing with waste at low calorific value, instead of interrupting the operation of the additional heat source, can reduce its power to a reduced value, and preferably we vary this reduced power by way to increase it when the temperature in the gasification zone goes below the limit lower prescribed. Such an order can be performed automatically by the steering device cited above, the latter then also being connected to means for regulating the power of the heat source additional.

Incineration of waste containing components dangerous, e.g. chlorine or sulfur, can be further supplemented by a purification of the smoke from the post-combustion chamber and / or pyrolysis gases withdrawn from the gasification chamber to extract harmful gases using known techniques, for example by passing the gaseous products to through one or more layers of particles of limestone or other absorbent material and neutralizing these pollutants. If the purification step concerns pyrolysis gases, for example pass these through a conduit containing said materials and connecting the gasification chamber to the post-combustion chamber.

To reduce the risk of air pollution by particles, the afterburner can be subdivided into separate volumes connected in series so let the smoke pass through them successively. Mon of these volumes is preferably arranged in a cyclone, the conduit leading to this volume being arranged to ensure there a circular gas flow. Such a cyclone dust the gases.

To reduce emissions from ignition and the shutdown of the incinerator, the process can be implemented continuously. To this end, the incinerator can be equipped with means for charging continuously or intermittently new waste into the gasification chamber and discharge the ashes and other incombustibles during the operation of the incinerator. Like, in the gasification chamber, the temperature is not high that in the region of the gasification zone, such loading and unloading can be done by known means, for example by loading waste by through an air lock.

To reduce the risk of contamination by germs and other dangerous chemicals present in the waste, we can load the waste directly in disposable containers (provided that they are flammable, for example polyethylene) these bags are also incinerated with the waste.

Before switching off the incinerator, when his room of gasification is substantially empty of waste to except the part of this room where is located the gasification zone, the supply of gasification is redistributed so that internal surfaces of the gasification chamber are heat treated for disinfection. AT For this purpose, the gasification chamber can be equipped with an additional intake port for the hot gasifier. The heating of this gasifying agent can be insured in the same heat exchanger where the air is preheated secondary.

To ensure a regular draw, the incinerator can be equipped, in addition to a fireplace, with a draw assist device, for example a extractor fan or ejector. This guarantees slight negative pressure in the rooms of the incinerator so as to avoid gas leaks to from these.

By means of the aforementioned preheating of air and / or waste, as well as the control of agent flow rates gasification and secondary air, and the proportion of the preheated part of these, the process described is less sensitive to variations in the composition and properties of the waste, and increases significantly the possibilities of dealing with waste with low calorific value, high content ash and very wet, with which due to small amounts of heat released, gasification self-sustaining is impossible without such preheating or additional heat output.

Other features and advantages of the invention will emerge further from the description below relating to examples.

• la figure 1 est une vue schématique d'un incinérateur selon l'invention ;
• la figure 2 est un schéma analogue à la figure 1, mais à échelle légèrement réduite et relatif à une variante, avec un détail II vu de dessus ; et
• la figure 3 est une vue schématique d'un incinérateur de laboratoire selon l'invention.

In the accompanying drawings:

• Figure 1 is a schematic view of an incinerator according to the invention;
• Figure 2 is a diagram similar to Figure 1, but on a slightly reduced scale and relating to a variant, with a detail II seen from above; and
• Figure 3 is a schematic view of a laboratory incinerator according to the invention.

The incinerator in Figure 1 includes a chamber vertically elongated gasifier 1 having a upper opening which is normally closed by a cover 21 or by a device allowing the continuous or discontinuous loading of waste 22 during the operation. When the cover is open, or thanks to such a loading device, the waste 22, such as hospital waste contained in disposable plastic containers, can be introduced into the gasification chamber 1.

A lower part 24 of the gasification 1 is defined by a perforated wall with through which the gasification chamber 1 is in fluid communication with an afterburner 5, which in turn is in communication fluid with the outside through a chimney 23 for smoke. Part 24 projects to the interior of the post-combustion chamber 5. The wall defining part 24 thus separating inside the gasification chamber 1 with the interior of the afterburner 5 is conductive of heat.

Part 24 of the gasification chamber is fitted with an intake port 3 for a gasification, more particularly air with possible addition of water vapor in the example.

Electric heating means 12 are mounted in the vicinity of part 24 of the gasification, either in the post-combustion chamber 5 in the vicinity of a perforated part of the wall defining part 24, either in the conduit gasifier adductor just upstream of the inlet 3.

We will first explain the process of gasification. The waste 22 having been loaded into the gasification chamber 1, the heating means 12 is activated to start heating the part lower waste 22, and the gasifying agent is sent through the intake port 3. This initiates gasification of said lower part of waste. As the parties successively of the waste is carbonated, the others parts move successively by gravity towards the perforated wall 24. A zone of gasification 2 substantially stable in part 24 of the gasification chamber.

Gaseous gasification products released from the gasification zone 2 flow through the perforated wall 24 in the post-combustion chamber 5. An inlet 6 is provided in the afterburner 5 near the perforated wall 24 for inject a gas into the post-combustion chamber 5 secondary oxidant, such as air, so as to burn gaseous gasification products in the post-combustion.

At the start of an incineration session, the means of heater 12 not only serves to initiate the gasification but also to initiate inflammation gaseous gasification products. Secondary air is introduced in more than stoichiometric quantities of so that the fumes 7 in the afterburner 5 contain excess oxygen in a proportion corresponding to standards relating to gas decontamination. He went up to the room afterburner 5 near the outlet of this one, a heat exchanger 8 in which the air coming from an intake device 26 recovers of the heat of the fumes which are about to leave the afterburner 5. The outlet of air from the heat exchanger 8 is connected to the gasifier inlet port 3 and at a secondary oxidant gas inlet 6 to through a respective flow adjustment means 31, 32. However, the inlet ports 3 and 6 are also connected to the air intake device 26 independently of the heat exchanger 8 through a other respective flow control means 33, 34. Thus, the temperature of the gasifying agent and the secondary oxidant gas can be set by setting, for each of them, the proportions of preheated air and of fresh air that compose them.

It is provided in the conduit for the agent hot gasification, downstream of the regulation means corresponding flow 31, a water injection means 36, this water forming vapor in the agent gasification heated when injected.

The gasification chamber 1 is also provided an additional inlet 13 for introduce hot gasifier in one location away from the perforated wall 24, at near the cover 21. The inlet 13 is supplied with hot gasification agent also under the form of hot air available at the outlet of the heat exchanger 8. The inlet 13 is equipped with a flow adjustment means 11.

The flow adjustment means 11, 31 to 34 are connected to an automatic pilot device 9 which also controls the operation of the heater 12. The heater 12 is connected to temperature sensors 10, one in the gasification 1 and the other in the post-combustion chamber 5.

The flow adjustment means 11 of the orifice additional intake 13 is ordered to send hot gasifier through the orifice 13 when the gasification chamber is almost empty as a result of the near completion of a incineration session, so as to disinfect by heat the internal surfaces of the chamber gasification. But like the gasification chamber is not yet completely empty, gaseous products continue to be produced in the area of gasification and burn in the afterburner, so the heat exchanger 8 is still capable of producing agent hot gasification for the inlet 13.

A draw assist device 14, under the form of an ejector, is mounted at the outlet of the post-combustion chamber 5 to produce so reliable a depression in all of the incinerator, so as to avoid the risk of leakage noxious gas from the incinerator.

A filter 37, consisting for example of one or several layers of limestone particles is also mounted at the outlet of the post-combustion chamber 5.

In the example of Figure 2, which will only be described that for its differences with that of figure 1, the post-combustion chamber 5 is subdivided into two volumes 41, 42, which the fumes 7 pass through successively before leaving room 5. The volume downstream 42 is arranged in a cyclone with a vertical axis so as to dust off the fumes. The gas pipe 43 by which the upstream volume 41 adjacent to the part 24 communicates with the downstream volume 42 at an opening of output directed in the circumferential direction of the volume 42 to generate the cyclone effect. The conduit 43 opens at the top of volume 42. An outlet duct 44 allowing the fumes to exit from the volume 42 has a opening close to the base of volume 42 and extends axially upwards through volume 42. Thus, the outer surface of the conduit 44 serves as a guide rotation for smoke 7 in volume 42 around the duct 44. The heat exchanger 8 is placed downstream of volume 42, between it and ejector 14. A filter such as 37 (Figure 1) has not been shown in Figure 2 but could also be expected.

1°)- On a chargé dans une chambre de gazéification 1 du prototype d'incinérateur représenté à la figure 3 environ 0,2 kg de bois humidifié (50% en poids d'eau) en morceaux de 10 à 15 mm. La densité moyenne de la charge était de 240 kg/m3. Après application d'une impulsion thermique par le chauffage électrique 12 au combustible en la partie inférieure de la chambre de gazéification 1 au-dessus de la grille 15, on a injecté de l'air primaire 3 dans la chambre de gazéification 1 et de l'air secondaire 6 dans la chambre de post-combustion 5. Ceci a causé l'inflammation d'une partie de la charge dans une région limitée inférieurement par la grille 15 et supérieurement par des ouvertures 16 à travers lesquelles les produits de gazéification 4 pouvaient s'écouler dans la chambre 5. C'est dans cette région que s'est établie la zone de gazéification 2. Les produits gazeux 4 ont ensuite été mélangés avec l'air secondaire 6 et brûlés dans la zone de combustion 17, produisant des fumées 7 extraits de la chambre 5. L'échangeur de chaleur 8 assurait le préchauffage de l'air primaire 3 et de l'air secondaire 6, et le refroidissement des fumées 7. Les débits d'alimentation de l'air primaire et de l'air secondaire étant respectivement de 0,5 et 0,4 l/seconde, le temps de traitement a été 10 mn. Les températures dans la zone de gazéification et dans la chambre de post-combustion étaient d'environ 800 à 900 et respectivement 1000 à 1100°C. La température des fumées à la sortie de la chambre de post-combustion derrière l'échangeur de chaleur était inférieure à 200°C. Les rejets de la chambre de post-combustion ne contenaient aucune poussière visible et étaient inodores.

2°)- Une charge échantillon, imitant la composition des déchets hospitaliers (selon l'analyse des déchets de l'Hôpital CHERNOGOLOVKA, région de Moscou, Russie) constituée de :

• textiles 24% en poids
• papier 28%
• carton 12%
• polyéthylène 9%
• caoutchouc 2%
• feuille d'aluminium 2%
• verre 7%, et
• eau 16%,

   a été chargée dans l'incinérateur de laboratoire décrit en référence à l'exemple 1. La masse et la densité du mélange chargés étaient de 0,17 kg et 190 kg/m3, respectivement. Avec les mêmes débits d'alimentation que ceux de l'exemple 1, la température dans la zone de gazéification et dans la chambre de post-combustion étaient d'environ 900 à 1000 et respectivement 1100 à 1200°C, respectivement ; la température de l'air alimentant les chambres était d'environ 500 à 600°C. La température des fumées à la sortie de la chambre de post-combustion (derrière l'échangeur de chaleur) était inférieure à 250°C. Le poids du résidu incombustible, constitué de verre fondu, de feuille et de cendre était de 0,02 kg ; il ne contenait aucune trace de carbone résiduel.

The prototype incinerator shown in FIG. 3 was used for experimental tests and will be described at the same time as the following experimental examples.

1 °) - We loaded into a gasification chamber 1 of the prototype incinerator shown in Figure 3 about 0.2 kg of humidified wood (50% by weight of water) in pieces of 10 to 15 mm. The average charge density was 240 kg / m3. After applying a thermal pulse by the electric heater 12 to the fuel in the lower part of the gasification chamber 1 above the grid 15, primary air 3 was injected into the gasification chamber 1 and l secondary air 6 in the post-combustion chamber 5. This caused the ignition of part of the charge in a region bounded below by the grate 15 and above by openings 16 through which the gasification products 4 could flow into the chamber 5. It is in this region that the gasification zone is established 2. The gaseous products 4 were then mixed with the secondary air 6 and burned in the combustion zone 17, producing fumes 7 extracted from the chamber 5. The heat exchanger 8 provided the preheating of the primary air 3 and the secondary air 6, and the cooling of the fumes 7. The feed rates of the primary air and secon air daire being respectively 0.5 and 0.4 l / second, the treatment time was 10 min. The temperatures in the gasification zone and in the post-combustion chamber were around 800 to 900 and respectively 1000 to 1100 ° C. The smoke temperature at the outlet of the post-combustion chamber behind the heat exchanger was below 200 ° C. The afterburner discharges contained no visible dust and were odorless.

2 °) - A sample charge, imitating the composition of hospital waste (according to the waste analysis from CHERNOGOLOVKA Hospital, Moscow region, Russia) consisting of:

• textiles 24% by weight
• paper 28%
• cardboard 12%
• polyethylene 9%
• rubber 2%
• aluminum foil 2%
• glass 7%, and
• water 16%,

was loaded into the laboratory incinerator described with reference to Example 1. The mass and density of the loaded mixture were 0.17 kg and 190 kg / m3, respectively. With the same feed rates as those of Example 1, the temperature in the gasification zone and in the post-combustion chamber were about 900 to 1000 and 1100 to 1200 ° C, respectively; the temperature of the air supplying the chambers was around 500 to 600 ° C. The smoke temperature at the outlet of the post-combustion chamber (behind the heat exchanger) was below 250 ° C. The weight of the non-combustible residue, consisting of molten glass, sheet and ash was 0.02 kg; it contained no trace of residual carbon.

Claims (25)

1. A method of incinerating fuel-containing solid wastes such as hospital wastes comprising the following steps :

   a gasification step, during which said wastes (22), as a first component, are gasifyed under admixture of a gasifying agent as a second component,

   a post-combustion step during which the gaseous products (4) of said gasification step, as a third component, are burnt under admixture of a secondary oxidant gas, as a fourth component,

   transfer of heat produced by said post-combustion step to at least part of at least one of said components prior to consumption thereof in the corresponding one of said gasification and post-combustion steps,

      characterized in that the heat transfer step is performed by a contact between gases produced by the post-combustion step and a heat-permeable wall (24) bounding at least part of the gasification chamber (1).
2. A method according to claim 1, characterized in that said heat is transferred to a gasification chamber wall (2) which bounds a gasification zone (2) where the gasification step is performed, at a distance from an inlet (21) for the wastes (22) to be incinerated.
3. A method according to claim 1 or 2, characterized by performing the gasification step in a gasification chamber (1) having heat-permeable walls (24) protruding into a post-combustion chamber (5) in which said post-combustion step is performed.
4. A method according to one of claims 1-3, characterized in that, concerning said at least one component, there is controlled a proportion thereof to which heat produced by said post-combustion is transferred.
5. A method according to claim 4, characterized by measuring a temperature under which one of the gasification and post-combustion steps is performed and controlling said proportion thereby to regulate said temperature.
6. A method according to anyone of claims 1-5, characterized by using heat produced by said post-combustion step for producing steam and introducing said steam into the gasifying agent (3).
7. A method according to anyone of claims 1-6, characterized by cleansing said gaseous products of gasification (4) or the post-combustion flues (7) thereby to remove noxious gases therefrom.
8. A method according to claim 7, characterized in that said cleansing is performed by passing said gaseous products through at least one layer of material (37) absorbing or neutralizing said noxious gases.
9. A method according to anyone of claims 1-8, characterized in that prior to the gasification step, said wastes are charged into a gasification chamber (1) while being contained in disposable containers (22).
10. A method according to anyone of claims 1-9, characterized by initiating gasification by heating with an additional heat source (12) at least one of said first and second components adjacent a location (2) where said gasification step is to be performed.
11. A method according to claim 10, characterized in that the power of said additional heat source (12) is regulated according to the post-combustion temperature, when processing low-caloric wastes.
12. A method according to anyone of claims 1-11, characterized in that prior to the end of an incineration session, when a gasification chamber (1) in which said wastes have been charged for gasification is already almost free of wastes, with the exception of a portion (2) of said chamber where the gasification step has been performed, said gasifying agent is redistributed in said gasification chamber thereby to heat-treat internal surfaces of the gasification chamber for disinfection thereof with hot gasifying agent (13).
13. A method according to anyone of claims 1-11, characterized in that prior to the end of an incineration session, when a gasification chamber (1) in which the wastes have been charged for gasification is already substantially free of waste, with the exception of a portion (2) of said chamber where the gasification step has been performed, gasifying agent heated by heat from post-combustion flues is fed to sweep said gasification chamber thereby to heat-treat internal surfaces of the gasification chamber for disinfection thereof with heated gasifying agent (13).
14. A method according to anyone of claims 1-13, characterized by recharging wastes for gasification and optionally also discharging ashes and other incombustibles during performance of the gasification and post-combustion steps.
15. A method according to anyone of claims 1-14, characterized in that the temperature in the gasification zone is greater than or equal to 800°C.
16. An incinerator for performing a method according to anyone of claims 1-15, comprising a gasification chamber (1), for containing a first component consisting of wastes (22) to be incinerated, means (3) for introducing a gasifying agent as a second component into said gasification chamber, a post-combustion chamber (5), means for fluid communication between the gasification chamber (1) and the post-combustion chamber (5), thereby to introduce into the post-combustion chamber a third component consisting of gaseous products (4) coming from the gasification chamber (1), inlet means (6) for introducing into the post-combustion chamber (5) a fourth component consisting of a secondary oxidant gas, and means (8, 24) for transferring heat from said post-combustion chamber (5) to at least part of at least one of said components upstream of said post-combustion chamber (5), characterized in that said means for transferring heat comprises a heat conductive wall (24) separating said post-combustion chamber (5) from a gasification zone (2) of said gasification chamber (1).
17. An incinerator according to claim 16, characterized in that said gasification zone (2) is arranged in a portion of said gasification chamber (1) which protrudes in said post-combustion chamber (5).
18. An incinerator according to claim 16 or 17, characterized in that the means for transferring heat comprise a heat exchanger (8) mounted and connected for transferring heat of flues of the post-combustion chamber (5) to at least part of at least one of said second, third and fourth components.
19. An incinerator according to anyone of claims 16-18, characterized by being provided with a control device (9) connected to probes (10) for temperature measurements in at least one of the gasification and post-combustion chambers and to means (11, 31-34) for controlling the feed rate and the distribution of the gasifying agent and secondary oxidant gas according to these temperatures.
20. An incinerator according to anyone of claims 16-18, characterized by being provided with a control means (9) connected to probes (10) for temperature measurements in at least one of the gasification (1) and post-combustion (5) chambers and to means (11) for controlling which proportion of said at least one component is subjected to heat transfer from the post-combustion chamber according to these temperatures.
21. An incinerator according to anyone of claims 16-18, characterized by being provided with a control means (9) connected to detecting means (10) for temperature measurements in at least one of the gasification and post-combustion chambers and to means for controlling the power of an additional heat source (12) mounted adjacent a gasification zone (2) in said gasification chamber (1).
22. An incinerator according to anyone of claims 16-21, characterized by its gasification chamber being provided with supplemental inlet means (13) for heated gasifying agent intended to perform disinfection of the internal surfaces of the gasification chamber.
23. An incinerator according to anyone of claims 16-22, characterized by the outlet of the post-combustion chamber being provided with a draught-promoting device (14), e.g., an exhaust fan or an ejector.
24. An incinerator according to anyone of claims 16-23, characterized by the post-combustion chamber (5) being arranged in a manner that it is subdivided in at least two separate volumes (41, 42), the gas flow passing those volumes consecutively.
25. An incinerator according to claim 24, characterized by at least one (42) of said volumes being arranged in the form of a cyclone wherein the gas flow (7) is cleansed of dust particles.

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