EP1235889A1

EP1235889A1 - Method and installation for gasifying carbonaceous compounds

Info

Publication number: EP1235889A1
Application number: EP00985382A
Authority: EP
Inventors: André Garnier; Jacques Proot
Original assignee: Agriculture Azote et Carbone Organiques (ANCOR); Proot Jacques
Current assignee: Agriculture Azote et Carbone Organiques (ANCOR); Proot Jacques
Priority date: 1999-12-03
Filing date: 2000-12-01
Publication date: 2002-09-04
Anticipated expiration: 2020-12-01
Also published as: CA2393088C; FR2801895A1; EP1235889B1; WO2001040411A1; DK1235889T3; CA2393088A1; AU2181801A; ATE499430T1; US7087098B2; DE60045662D1; ES2364123T3; US20030056438A1; PT1235889E; FR2801895B1

Abstract

The invention relates to a method of gasifying carbon-containing compounds incorporating mineral elements and/or potential contaminants, and it also relates to a gasification installation having means for containing a bath of molten slag, means for charging said compounds into said bath, means for injecting at least oxidizer into the bath so that the mixture of carbon-containing compounds and oxidizer is super-stoichiometric, whereby a first fraction of the compounds is pyrolyzed, a second fraction is subjected to a combustion reaction suitable for delivering heat energy to the bath of slag, and a third fraction diffuses into the bath, means for recovering the gas given off by the pyrolysis and the combustion of the first and second fractions, and means for lowering the temperature of a portion of the molten slag so as to allow it to solidify, thereby immobilizing at least a portion of the third fraction of the compounds containing mineral elements and/or potential contaminants.

Description

Process and installation for gasifying carbonaceous compounds

The present invention relates to a process for gasifying compounds of the carbon compound type and more particularly compounds comprising mineral fillers and / or potential contaminants. The present invention also relates to an installation for implementing the method.

One area of application envisaged is in particular that of the recovery of carbochemical or petrochemical residues and treated wood.

Gasification processes for carbon compounds are well known and lead to different gases depending on the initial constituents and the temperature conditions under which the chemical reactions take place. Among these reactions, there may be mentioned in particular: C + O ₂ = CO ₂

C + ^_1/2 O ₂ = CO C + CO ₂ = CO 2 C + H ₂ O = CO + H ₂ CO + H ₂ O = CO ₂ + H ₂

The reactions are more or less complete and they generally lead to a mixture of gases comprising in particular carbon dioxide and hydrogen.

The Winkler process is well suited to the gasification of coal and operates in a fluidized bed, making it possible to produce a mixture of carbon monoxide and hydrogen. However, this process is poorly suited to the types of fuel envisaged, in particular because of the particles of wood which fly away easily. Mention will also be made of the Lurgi process, fed with granular coal and working in a fixed bed under pressure, but at low temperature, which causes the release of numerous harmful compounds which it is necessary to recover by filtering the gases in a column of oil wash. Furthermore, in these processes specially designed for the production of gas from coal, no device is provided for inerting any contaminants or for removing the mineral charges that the coal could contain. However, the types of fuel envisaged include mineral fillers and above all contaminants, in particular chromium and copper, which it is essential to recover and to inert.

An object of the present invention is to provide a process for gasifying a compound comprising mineral fillers and / or potential contaminants in which the mineral fillers are removed, with the contaminants which are inert.

To achieve this object, according to the invention, the process for gasifying compounds, in particular carbonaceous compounds comprising mineral fillers and / or potential contaminants, is characterized in that it comprises the following steps:

- At least said compounds are loaded into a molten slag bath and the oxidizer is injected into said bath so that the mixture, carbonaceous compounds / oxidizer, is over-stoichiometric, whereby a first part of said compounds is pyrolyzed, whereby a second part undergoes a combustion reaction capable of yielding thermal energy to said slag bath, and whereby a third part diffuses into said bath,

- The gases from pyrolysis and combustion, from said first and second parts are recovered in particular, and, - the temperature is lowered by at least part of the molten slag so as to make it solid, thereby immobilizing it at least a portion of said third portion of said compounds containing at least fillers and / or potential contaminants.

Thus, a characteristic of the gasification process resides in the support constituted by the molten slag, in which the carbonaceous compounds, likely to contain mineral fillers and / or potential contaminants, decompose by pyrolysis. Under the action of temperature, between 1100 ° C and 1500 ° C, carbonaceous compounds form new chemical species leading to synthesis gas, and potential non-volatilized contaminants diffuse in the molten slag. The injected oxidizer and the new chemical species formed constitute a mixture which, under the effect of temperature, leads to a combustion reaction.

It is understood that the combustion which is always exothermic provides thermal energy to the slag allowing it to be kept at a certain temperature.

However, the object of the invention is to produce synthetic gas and to do this we adjust the proportion of carbonaceous compounds, that is to say of fuel, and of oxidizer so that the mixture is super-stoichiometric. Thus, the quantity of fuel is greater than the quantity of oxidizer capable of reacting with it and therefore a first part of the carbon compounds is pyrolyzed to lead to synthesis gas and a second part is burned and supplies energy to the slag.

The burnt gases and the gases from the pyrolysis are recovered, but it is understood that it is the latter which are of interest, either energetically or for various syntheses.

In addition, in order to immobilize the contaminants contained in the molten slag, the temperature of said slag is lowered by pouring it, then it is granulated. When the process is carried out continuously, advantageously, the temperature of a part of the molten slag is lowered by removal of said part. This operation consists in pouring the slag either sequentially or continuously.

In order to make the slag inert, and above all to fill the slag removed to maintain a constant level of the bath, advantageously, in particular, fluxes are added to the molten slag. For the implementation of the process, when the form of the compounds requires it, advantageously, the said compounds are conditioned in solid elements so as to charge the said elements directly above the molten slag bath, whereby said elements are deposited on the surface. of said bath and / or are incorporated therein.

In fact, when volatile and heterogeneous materials are introduced above the slag in fusion, taking into account the gassing these are likely not to directly reach the slag, or to be carried away with the gases. To overcome this, the said compounds are agglomerated together so as to constitute relatively heavy solid elements with regard to the evolution of gas, whereby the compounds are directly introduced into the slag bath.

In the case where the carbon compounds are sufficiently homogeneous and dry, preferably preferably, said compounds and the oxidizer are simultaneously injected into the molten slag bath.

It is also advantageously possible, during the start-up phases or when the amount of energy supplied to the slag by the combustion of carbonaceous compounds is too low, simultaneously injecting said oxidant and a fuel into said molten slag bath to produce a combustion reaction whereby thermal energy is transferred to said bath and keeps it at the desired temperature.

However, the object of the present invention is to recover the energy contained in carbonaceous compounds, in particular gases, and according to a particular characteristic, said gases are purified so as to obtain a clean combustible gas. This gas can be burned in situ in a thermal power plant or transferred to a distribution network with or without cogeneration.

The gases directly coming from the combustion reaction and from the pyrolysis are hot and according to another particular characteristic, the heat energy is recovered, in particular from said gases, so as to transfer thermal energy to a heat transfer fluid. In addition, a fourth part of said compounds vaporized by the slag bath is condensed into fusion. Indeed, a certain number of elements contained in carbonaceous compounds do not participate in the pyrolysis or combustion reactions and vaporize on contact with the slag. These elements are isolated at the heat exchanger, since the latter contributes to the condensation of said fourth part.

Another object of the present invention is to provide an installation for the gasification of compounds, in particular carbon compounds, comprising mineral fillers and / or potential contaminants, said installation comprising: means for containing a bath of molten slag,

means for loading at least said compounds into said molten slag bath,

- Means for injecting at least the oxidant into said bath so that the mixture, carbonaceous / oxidant compounds, is super-stoichiometric, whereby a first part, of said compounds, is pyrolyzed, whereby a second part undergoes a combustion reaction able to transfer thermal energy to said slag bath, and whereby a third part diffuses into said bath,

means for recovering in particular the gases resulting from the pyrolysis and from the combustion of said first and second parts, and,

- Means for lowering the temperature of at least part of the molten slag so as to make it solid, whereby at least a portion of said third part of said compounds is immobilized containing at least fillers and / or potential contaminants .

According to a preferred embodiment of the invention, the molten slag bath is contained in the lower part of a vertical cylindrical furnace comprising at least one opening pierced in the wall of the upper part of said furnace for loading said compounds , and at least one opening pierced in the wall of the lower part of said furnace to take at least part of the molten slag. It is understood that the carbonaceous compounds are projected into the molten slag from the top of the furnace, to be transformed, and that it is the same for the adjustments of the slag from which a part is removed. When the carbonaceous compounds reach the slag in fusion, they are transformed into gas and according to a characteristic of the invention, the wall of the upper part of the vertical oven is pierced with an orifice intended to collect at least the gases resulting from the pyrolysis and of the combustion of said first and second parts and said installation further comprises washing means connected to said orifice for purifying said gases.

When they leave the oven, the gases have significant energy since they reach a temperature substantially higher than 1100 ° C. In order to improve the overall efficiency of the installation, a heat exchanger and deposition chambers are interposed between the oven and the washing means so as to recover at least partially the heat energy of said products and to recover a fourth part of the compounds vaporized in the oven in condensed form.

The gases escape through the hole drilled in the upper part and pass through all of the devices, until clean gas is obtained. To prevent gases from escaping through the opening intended for loading, provision is advantageously made for the means for loading said compounds to include a worm screw, opening directly below the molten slag bath, provided with heating means , whereby the compounds can be agglomerated together by melting at least one of said compounds. It is understood that the endless screw fixed on the opening intended for loading makes it possible to isolate the enclosure of the furnace when it is in operation and that it contains carbonaceous compounds. The fact that certain compounds are made pasty and agglomerate all the other compounds contributes to the impermeability of the loading opening with respect to the gaseous mass. This gaseous mass comes essentially from the decomposition of carbonaceous products, which is indirectly induced by the heat produced by the combustion of part of these products, which combustion requires an oxidant. According to a particular embodiment, the means for injecting the oxidant into the molten slag comprise a lance which passes through the wall of the upper part of the furnace to plunge into the bath of molten slag and in which the oxidant is under pressure.

According to another particular embodiment, the means for injecting the oxidant into the molten slag comprise a lance which passes through the wall of the lower part of the furnace to open into the bath of molten slag and in which the oxidant is under pressure.

In these two embodiments, the end of the lance is immersed in the slag, and the oxidizer under pressure diffuses therein to react with the fuel.

In the case of the last particular embodiment, advantageously, the opening pierced in the wall of the lower part of said oven opens into a reservoir contiguous to said oven, open in its upper part, the edges of which reach at least the average level. of the molten slag bath contained in the lower part of said furnace and said lance is introduced into said open upper part and passes through the common wall of the lower part of the furnace and of said tank to open into the molten slag bath. These provisions make it possible in particular to overcome the difficulties which the sealing of the passage of the lance presents in the wall of said furnace.

Furthermore, said tank makes it possible to pour the slag more easily, in particular within the framework of a continuous process, since it suffices to provide a groove in the rim of the tank in the extension of the level of the molten slag bath. Thus, each adjustment of the slag causes an increase in the height of the level and consequently the flow of a part of the molten slag. Other features and advantages of the invention will emerge on reading the description given below, by way of indication but not limitation, with reference to the appended drawings in which:

FIG. 1 is a general schematic view of a gasification installation for implementing the method according to the invention,

FIG. 2 is a simplified vertical sectional view of the furnace according to a particular embodiment of the installation,

- Figure 3 is a schematic sectional view along the plane III-

III of Figure 2; and - Figure 4 is a schematic sectional view along the plane IV-

IV of Figure 2.

Referring first to Figure 1, we will describe a general installation for the implementation of the gasification process according to the invention. Reactor 2, called the furnace, is the essential element of the installation, since it is within it that all of the transformations according to the invention take place.

The oven 2 is made of refractory material and it forms a vertical cylinder whose height is greater than the diameter. The diameter of such an oven is fixed according to the quantities of carbon compounds which it is desired to transform, but it is preferably between two and four meters, which makes it possible to optimize the overall yield.

In the lower part of the furnace 2 a slag 4 is deposited which is heated in a first phase by means of a lance 6 at the end of which burn a fuel and an oxidizer, injected under pressure. The end of the lance is immersed in the slag and causes it to melt, so that the molten slag constitutes a bath whose temperature can be between 1100 ° C and 1500 ° C.

In this embodiment, the lance passes through the wall of the upper part 8 of the furnace 2 and it is movable along the axis of the furnace so that the flame can be immersed in the slag. Fuels likely to be used are preferably gas or fuel oil and the oxidizer is generally pure air or oxygen-enriched air.

In a second phase, that is to say in normal operation, the thermal energy is supplied to the slag 4 by the controlled combustion of the carbonaceous compounds 10 which float in the slag bath. These compounds are loaded from a hopper 12 onto the slag bath 4 by means of the worm screw 14.

The carbon compounds capable of being transformed in the furnace 2 are essentially wood and hydrocarbons. Wood used as support for low voltage power lines or telephone lines is generally treated with water-soluble salts, for example solutions of copper, chromium, and arsenic oxides, while railway sleepers iron are treated with creosote. These woods as well as woods treated with the same substances are difficult to recycle, and the gasification process according to the invention makes it possible to destroy, or to recover and inert, the harmful contaminants which they contain.

The wood is packaged in fragments, the fine part of which is agglomerated with carbochemical or petrochemical residues. Bituminous shales can also be used in this gasification process.

The wood in the form of shavings and sawdust is introduced into the hopper 12 with the carbochemical or petrochemical residues forming a mixture, said hopper 12 being extended by the endless screw 14 which opens into an opening 16 pierced in the wall of the upper part 8 of the oven 2. The endless screw 14 is hermetically connected to the oven 2 and it is provided with a heating system which surrounds it so that, when the said mixture passes through it, the residues soften and form with shavings and sawdust from homogeneous portions comparable to solid elements. When these solid elements are at the base of the opening 16 they fall into the furnace 2 and are deposited on the surface of the molten slag bath 4.

In the case where the carbonaceous compounds are in pieces or agglomerated beforehand or the feed screw is not suitable for loading the fuel, an airlock or any device having the same function is provided for introducing said compounds into the slag 4 and respect the tightness of the oven 2.

These elements consisting essentially of carbon compounds 10 decompose under the effect of heat to form new substances, and in particular gases. A certain number of these compounds, constituting said fourth part, are vaporized, this is notably the case with water and arsenic. The latter is in the oxidized form in the feed but the conditions in the furnace reduce it to the metallic state; it will thus condense in the metallic form, which will allow better elimination.

The lance 6 which, in the first phase, makes it possible to inject an oxidizer and a fuel into the slag 4 so as to transfer energy to said slag by means of combustion, brings in this second phase the oxidant necessary for the controlled combustion of the carbonaceous compounds 10 present on the surface of the molten slag bath 4. Thus, only the controlled combustion of carbonaceous compounds yields the thermal energy necessary to maintain the bath temperature between 1100 ° C and 1500 ° C. As in the first phase, the oxidizer is injected at the end of the lance into the heart of the slag. In this way, said oxidizer diffuses into said slag 4 and reacts with carbonaceous compounds 10 according to a combustion reaction. The oxidizer consists of pure air, oxygen or a mixture of the two which is adjusted according to the oxidizing properties which it is desired to have. The oxidizer flow rate is also adjusted so that the mixture of carbonaceous compounds 10 / oxidizer is over-stoichiometric and thus, only a so-called second part of the carbonaceous compounds is burned to provide the energy necessary to maintain the slag in fusion. The rest of the carbon compounds, said first part, is therefore pyrolysis and forms new substances and in particular carbon monoxide and hydrogen. Carbonaceous compounds are likely to contain potential contaminants which spread into the molten slag during decomposition. This is particularly the case for chromium and copper. The chromium will scorify and the copper will dissolve in the slag if its content is very limited, otherwise it will be at the base of the formation of the dense phase in metallic or other form. In order to immobilize these elements, at regular or continuous intervals, the slag will be poured and then granulated. The pouring will be done through an opening, not shown in Figure 1, pierced in the wall of the lower part of the furnace 2. To compensate for the removal of slag, it is adjusted with conventional fluxes of the limestone, sand, ore type. iron, soda or others. These additions can be made from the opening drilled in the wall of the upper part 8 intended for loading carbonaceous compounds. Preferably a special opening is provided, not shown, pierced in the wall of the upper part 8 to load these fluxes. The appearance of the gases above the slag produces a gas pressure in the oven, which gases tend to escape through an orifice 18 pierced in the wall of the upper part 8 of the oven 2. A rising gas flow therefore appears in the furnace with regard to which the portions of carbonaceous compounds are sufficiently heavy to reach slag 4 in fusion and not to be entrained by the gaseous mass.

The temperature of the gases is generally greater than 1100 ° C., therefore, in order to optimize the energy efficiency of the installation, the heat energy of said gases is at least partially recovered by directing them into a chamber 20 comprising an exchanger thermal 22. The latter consists of a coil in which circulates a heat transfer fluid capable of actuating a turbine among others. The gases cool in contact with the heat exchanger 22, and a certain number of compounds, constituting said fourth part, condense, in particular arsenic at around 800 ° C. A space 24 is provided in the chamber 20 so as to store the condensation dust of the arsenic. One can also provide a second similar chamber (not shown), upstream of the first in which the dust will settle directly from the furnace 2. The latter will be recycled and reintroduced at the level of the conditioning of the load. When the gases reach a temperature of about 200 ° C, the efficiency of the heat exchanger 22 becomes relatively poor and the gases are evacuated. They are conveyed in washing means 26, connected to the chamber 20 to remove the last traces of dust, as well as the unwanted gases in order to supply clean gas at outlet 28. A main fan (not shown) is provided so to take up the gases at outlet 28 to convey them in a gasometer. This main fan is capable of creating a vacuum at the end of the gasification installation, contributing to the recovery of gases from the oven. The washing water is recycled in a purification device 30 to be reused. It is also planned to interpose between the chamber 20 and the washing means 26 a flare 32 so as to be able to evacuate the gases in the event of an incident, but especially during the start and stop phases. A clean synthesis gas is thus obtained, usable as fuel, but which could also be used to produce different organic compounds.

We will now refer to Figures 2, 3 and 4 to describe in detail the lower part of the oven, according to a particular embodiment. FIG. 2 shows a view in vertical section of the furnace 2 in the wall of the lower part of which an opening 34 is pierced which opens into a tank 36, or pre-crucible, adjoining the lower part of the furnace 2. The pre-crucible 36 is open in its upper part and its edges 38 are substantially above the average level of the slag bath 4 in molten furnace 2. It is understood that the slag 4 in fusion gains the pre-crucible 36 and that its level is established at the level of the slag 4 of the furnace 2.

In this particular embodiment, the lance 6 is introduced into the open upper part of the crucible 36 and crosses, obliquely, the common wall of the lower part of the furnace 2 and of the fore-crucible 36, so that its end 40 opens into the molten slag bath from the furnace. Thus the oxidizer is injected into the slag 4 of the furnace and diffuses in particular on the surface so that the carbonaceous compounds burn. This embodiment notably makes it possible to overcome the problems of seal between the lance 6 and the furnace 2 when the latter passes through it in the upper part. In Figure 4, there is shown the lance 6, the furnace 2 and the pre-crucible 36 in top view according to section IV-IV. The lance 6 is eccentric with respect to the furnace 2, and the projection of the oxidizer imparts a rotation to the melt allowing better agitation and a good circulation of the slag 2 in the pre-crucible so that the latter does not freeze there . For this purpose, the orifice of the wall 42 through which the lance passes is at least as large as the opening 34 pierced in the wall of the lower part of the oven. Furthermore, in accordance with FIG. 3, the opening 34 is also eccentric and pierced tangentially to the internal wall of the furnace to open out in a corner of the pre-crucible. This configuration reduces the residence time of the slag 4 melted inside the fore-crucible and consequently the risks that it freezes there. To further mitigate this risk, advantageously the pre-crucible is provided with a cover, not shown, having an orifice for the passage of the lance. The slag is poured at regular or continuous intervals by means of a channel 44 formed in the edge of the pre-crucible, the closure of which is controllable. The slag is then granulated and it is likely to be used as an aggregate or as a sandblasting agent since the potential contaminants it contains are perfectly immobilized.

In addition, a tap hole is provided at the base of the pre-crucible, closed by a plug, making it possible to eliminate a dense phase which forms and settles at the bottom of the molten slag bath.

The invention will now be illustrated by means of a comparative example, in which three different oxidant compositions are injected into the molten slag. The example aims to give energy production values that can be expected from the installation in accordance with the invention by varying the composition of the oxidant.

The values and compositions below relate to a mixture comprising 70.6% of wood and 29.4% of pitch. The wood contains 15% moisture and 0.8% ash and the "pitch" contains 80% pure pitch and 20% earth. To easily melt the earth, the necessary corrective will be brought to the slag, for example iron oxide.

The data below assumes a consumption regime of 4722 Kg / h of the mixture of wood and pitch, and a flow of 9 tonnes of slag per day for an oven of 2 meters in diameter. Obviously the slag is readjusted according to the quantity poured.

The higher the oxygen content of the oxidizer, the more the quantity of gas produced decreases. Conversely, however, the gas which is resulting from the transformation is richer in carbon monoxide and hydrogen, which gives it a greater Lower Caloric Power (PCI).

However, the quantity of steam produced decreases with the increase in oxygen, and above all oxygen has a cost which must be passed on to the overall yield of the installation.

In the above example, the optimization of the process can be easily done by modulating the flow of oxygen and air. In the case of a different composition of carbon compounds, further adjustments of oxidizers would have to be made.

Claims

1. A process for gasifying compounds, in particular carbonaceous compounds comprising mineral fillers and / or potential contaminants, characterized in that it comprises the following stages:

- At least said compounds are loaded into a molten slag bath and the oxidant is injected into said bath so that the mixture, carbonaceous compounds / oxidizer, is over-stoichiometric, whereby a first part of said compounds is pyrolyzed, whereby a second part undergoes a combustion reaction capable of yielding thermal energy to said slag bath, and whereby a third part diffuses into said bath,

the gases from pyrolysis and combustion, from said first and second parts are recovered in particular, and,

- The temperature is lowered by at least part of the molten slag so as to make it solid, whereby at least a portion of said third part of said compounds is immobilized containing at least fillers and / or potential contaminants.

2. Gasification process according to claim 1, characterized in that, in addition, said compounds are conditioned into solid elements so as to charge said elements directly below the molten slag bath, whereby said elements are deposited at the surface of said bath.

3. Gasification process according to claim 1 or 2, characterized in that, in addition, said compounds and the oxidant are simultaneously injected into the molten slag bath.

4. A gasification process according to any one of claims 1 to 3, characterized in that said oxidant and a fuel are simultaneously injected into said molten slag bath to produce a combustion reaction whereby thermal energy is yielded to said bath.

5. Gasification process according to any one of claims 1 to 4, characterized in that in addition, a fourth part of said compounds is condensed vaporized by the molten slag bath.

6. Gasification process according to any one of claims 1 to 5, characterized in that further purifies said gases so as to obtain a clean combustible gas.

7. Gasification process according to any one of claims 1 to 6, characterized in that in addition the heat energy is recovered, in particular from said gases, so as to transfer thermal energy to a heat transfer fluid.

8. A gasification process according to any one of claims 1 to 7, characterized in that, in addition, fluxes are added in particular to the molten slag.

9. Gasification process according to any one of claims 1 to 8, characterized in that the temperature is lowered of a part of the slag in fusion by removal of said part.

10. Installation for the gasification of compounds, in particular carbonaceous compounds, comprising mineral fillers and / or potential contaminants, characterized in that it comprises:

- means for containing a bath of molten slag,

means for loading at least said compounds into said molten slag bath,

- Means for injecting at least the oxidant into said bath so that the mixture, carbonaceous / oxidant compounds, is super-stoichiometric, whereby a first part, of said compounds, is pyrolyzed, whereby a second part undergoes a combustion reaction able to transfer thermal energy to said slag bath, and whereby a third part diffuses into said bath, - means for recovering in particular the gases resulting from pyrolysis and from the combustion of said first and second parts, and - Means for lowering the temperature of at least part of the molten slag so as to make it solid, whereby at least a portion of said third part of said compounds is immobilized containing at least fillers and / or potential contaminants .

11. Gasification installation according to claim 10, characterized in that the molten slag bath is contained in the lower part of a vertical cylindrical furnace comprising at least one opening pierced in the wall of the upper part of said furnace for loading said compounds, and at least one opening pierced in the wall of the lower part of said furnace to take at least part of the molten slag.

12. Gasification installation according to claim 10 or 11, characterized in that the means for loading said compounds comprise an endless screw, opening directly above the molten slag bath, provided with heating means, whereby the compounds can be agglomerated together by fusion of at least one of said compounds.

13. Gasification installation according to any one of claims 10 to 12, characterized in that the means for injecting the oxidant into the molten slag comprise a lance which passes through the wall of the lower part of the furnace to open into the bath of slag in fusion and in which the oxidizer is under pressure.

14. A gasification installation according to claim 13, characterized in that the opening pierced in the wall of the lower part of said oven opens into a tank contiguous to said oven, open in its upper part, the edges of which reach at least the average level. of the molten slag bath contained in the lower part of said furnace and in that said lance is introduced into said open upper part and passes through the common wall of the lower part of the furnace and of said tank to lead into the molten slag bath.

15. Gasification installation according to any one of claims 10 to 12, characterized in that the means for injecting the oxidant into the molten slag comprise a lance which passes through the wall of the upper part of the furnace to plunge into the bath of slag in fusion and in which the oxidizer is under pressure.

16. Gasification installation according to any one of claims 11 to 15, characterized in that the wall of the upper part of the vertical oven is pierced with an orifice intended to collect at least the gases from pyrolysis and combustion of said first and second parts and in that, in addition, said installation comprises washing means connected to said orifice for purifying said gases.

17. Gasification installation according to claim 16, characterized in that in addition a heat exchanger and deposition chambers are interposed between the oven and the washing means so as to recover at least partially the heat energy of said products and at recover a fourth part of the compounds vaporized in the oven in condensed form.