The second reactor can be a liquid/gas exchange column operating co-currently or counter-currently.

According to one embodiment, the second reactor comprises a tank containing said second salt mixture and said inlet of said second reactor is disposed below the level of the free surface of said second salt mixture, preferably at the bottom of the tank.

The enclosure can include at the bottom, a removable grate for removing inert materials (rubble and other).

The facility according to the invention can be at least partially buried. Thus, at least the first bath can be buried in the ground. Only the inlets of the conveyors are accessible to enable the insertion of the carbonaceous material into the first bath. The second bath and/or the storage tank can also be buried.

It is obvious that all the features of molten salt baths cited with reference to the process according to the invention can be applied to mixtures of salts (molten or not) which can be used in the facility according to the invention.

Definitions

The terms “volatile hydrocarbons” denote saturated, unsaturated (alkene, alkynes), cyclic, unsaturated cyclic hydrocarbons having a vapor pressure of 0.01 kPa or more at a temperature of 293.15 K. It can consist more specifically of hydrocarbons that are saturated or unsaturated, optionally cyclic (also saturated or unsaturated) and including from 1 to 5 carbon atoms. They can optionally be branched and substituted by one or more radicals chosen from the following groups: methyl or ethyl.

The terms “carbonaceous material” denote any material containing carbon atoms, hydrogen atoms and optionally other atoms, of which oxygen, sulfur or halogen atoms, for example. In the sense of the invention, the organic material is a carbonaceous material.

The terms “solid carbonaceous material” denote a material in the divided state without any size restriction and capable of containing water or oils, water and oils being minority. A dispersion or an emulsion of carbonaceous material in a liquid (sludge) is not a carbonaceous material in the sense of the invention.

FIGURES

The present invention, the technical features thereof and the various advantages provided thereby will become more apparent on reading the following description, of a specific embodiment of the invention, presented by way of non-limiting example and which refers to the appended drawings wherein:

FIG. 1 represents a schematic view of a specific embodiment of the invention;

FIG. 2 represents a specific embodiment of the tank and the conveyors; and

FIG. 3 represents three alternative embodiments of the second molten salt bath.

DETAILED DESCRIPTION

With reference to FIG. 1, a specific embodiment of the facility and mode of implementation of the process according to the invention will be described. The facility includes an enclosure 1 which contains the first molten salt bath. The surface of the first liquid bath is represented by the line L. Heating means (not shown) make it possible to melt the initially solid salts and form a liquid phase, which forms the molten salt bath. The enclosure is provided with a draining pipe 3 which opens into the bottom of the enclosure, under the bath and makes it possible to drain the enclosure 1. The enclosure also includes a removable screen 11 which makes it possible to retain the solid materials which are not degraded by the bath. Two conveyors 5 lead to above the surface of the bath and make it possible to transport the waste deposited at the inlet 51 thereof into the bath. The enclosure 1 can be hermetically sealed at the outlet of the conveyors 5 by means for example of hatches or other. The facility includes a column 2 containing a second molten salt bath. A valve V1 makes it possible to regulate the gas flow from the enclosure 1 and entering the column 2. The outlet of the column 2 is connected to a storage tank 6 for pressurizing the gases. A valve V2 is used to regulate the gas flow entering the storage tank 6. Upstream from the valve V2, a bypass pipe 23 is located, which makes it possible to connect the outlet of the column 2 with the enclosure 1. The bypass pipe 23 opens into the enclosure 1, at a level located below the surface L of the first molten salt bath. A valve V3 equips the bypass 23 and is used to regulate the flow of recycled gases to the first bath. The dotted line SS represents the surface of the floor. In FIG. 1, the enclosure 1 is buried and the inlet 51 of the conveyors is flush with ground level. It is also possible to also bury the column 2.

A mode of implementation of the process according to the invention will now be described with reference to FIG. 1. The carbonaceous materials to be processed are carried, for example, by truck to the facility. They may consist of solid waste. Waste in the form of suspended solid particles in a liquid (sludge) cannot be processed with the process according to the invention. The waste is introduced into the conveyors 5 at the inlet 51 thereof. The conveyors 5 carry the waste into the enclosure and drop it into the first molten salt bath. The bath has been previously formed by melting the salts thanks to the heating means (not shown). According to the density thereof, the waste sinks into the bath or floats on the surface thereof. Inert waste (rubble, bricks, concrete, stones and others) which has a greater density than carbonaceous waste, in particular plastics, falls to the bottom of the bath and accumulates on the screen 11. It will subsequently be removed at the end of the process. After introducing the waste, the inlets 51 are hermetically sealed by means for example of hatches or other means and the salts are molten (batch operation). The enclosure 1 contains air located above the surface of the first bath. The cracking reaction of the carbonaceous material into hydrocarbons is catalyzed by the ions of the first bath. This reaction consumes the oxygen of the air contained in the enclosure 1, above the surface L of the first bath. The enclosure 1 being hermetic, the reaction starts in an air atmosphere. It then continues in an atmosphere that is oxygen-depleted, or even containing no more oxygen. The absence of oxygen increases the yield of hydrocarbons, particularly of volatile hydrocarbons, regardless of the type of carbonaceous material processed. The pressure above the first bath increases on account of the formation of hydrocarbons. When it reaches a given value which indicates that the enclosure contains mostly hydrocarbons (volatile or not), the value V1 is opened. The gases enter the column 2 containing the second molten salt bath. They then undergo a second catalytic degradation in this second bath. The second bath makes it possible to increase the volatile hydrocarbon yield. The second bath can be used in a column 2 wherein the gases to be processed are bubbled. The column 2 and the various alternative embodiments thereof will be described in more detail with reference to FIG. 3. In the column 2, the gases undergo a second degradation. At the outlet of the column 2, according to the composition of the outflowing gas flow, this flow is either directed (partially or completely) toward the storage tank 6. All or part of the flow can be redirected toward the first bath located in the enclosure 1 for a new processing. The gases are injected into the bath in order to pass through it in the form of bubbles and be once again degraded therein.

An embodiment of the process of the invention will now be described with reference to FIG. 1, in the case of waste containing plastics, optionally wet or partially covered with organic material (such as food packaging). The waste is introduced, for example, by a garbage truck into the conveyors 5. After introducing the waste, the inlets 51 are hermetically sealed by means for example of hatches or other means and the salts are molten. The waste is contained in plastic bags. The bags drop into the first molten salt bath. The bags sink immediately in the bath on account of the density thereof. The enclosure 1 communicates with the outside at the conveyors 5. The catalytic reaction is immediate and various gases are produced above the bath. The enclosure does not communicate with the outside. The enclosure optionally has a flange cover which is connected to the column 2 or to the tank 6. On account of the presence of oxygen in the air, ethanal type compounds are also produced at the same time as volatile hydrocarbons. The temperature above the bath is at least 100° C. when the temperature of the bath is 500° C. and the pressure is 1 bar. Once the pressure reaches a given value above the first molten salt bath, the gases produced are passed in the second molten salt bath. This second bath makes it possible to convert the compounds containing oxygen into volatile hydrocarbons. Analysis means mounted at the outlet of the column 2 make it possible to indicate the volatile hydrocarbon concentration of the gaseous mixture at the outlet of the column 2. If the composition is considered to be satisfactory, i.e., containing more than 90% by volume of volatile hydrocarbons, the gaseous flow is oriented toward the storage tank. Otherwise, the gaseous flow is oriented toward the first molten salt bath or toward the second molten salt bath according to the composition thereof and the compounds desirable to be degraded to volatile hydrocarbons (see Table 2).

With reference to FIG. 2, a specific embodiment of the enclosure 1 and the conveyors 5 will now be described. The elements in common with those of FIG. 1 are referenced the same. In FIG. 2, the enclosure 1 includes in the lower part thereof a cylindrical container 11 which contains the first bath (the liquid is not shown). The upper part of the enclosure is parallelepipedal and open to the outside via the conveyors 5. Three faces of this part are connected to a conveyor 5. The hatches are not shown. The catalytic reaction is always performed after introducing the waste, the hermetic closure of the inlets 51 and the melting of the salts. The outlet 61 is connected to the storage tank 6. The outlet 231 enables the recirculation of the gases formed toward the first bath. The entire facility does not necessarily include a second bath.

With reference to FIG. 3, three alternative embodiments of the second bath will now be described. It should be noted that the second bath is optional.

With reference to FIG. 3, the column 2 comprises two screens 220 disposed on top of one another along the height of the column. These screens make it possible to divide the gas flow to be processed into a bubble of given size. The black arrows indicate the gas circulation, from the bottom upward. The molten and therefore liquid salts circulate from the top downward from the inlet 210 to the outlet 211. The gases and the salts circulate at countercurrent. The bubbles promote and accelerate the catalytic reaction by increasing the contact surface area between the gases and the salts.

In FIG. 3, the second reactor contains the second bath. The reactor not being full, air can remain above the second bath short of filling the space unoccupied by the molten salt by an inert atmosphere. The gases are sent to the center of the reactor by the inlet pipe 25 so as to bubble in the second molten salt bath. The inlet pipe 25 is immersed in the bath and opens at the center of the reactor. After the reaction inside the second bath, the processed gases come out at the top of the reactor at the outlet 27.

With reference to FIG. 3, a third alternative embodiment will now be described. The second reactor 2 is horizontal and contains the second bath. Preferably, the second bath fills the second reactor 2 by half. The inlet and outlet pipes includes screens 220 which enable the formation of bubbles at the inlet and at the outlet of the reactor. The second salt bath is static as in the second alternative embodiment.

Example 1

The different types of waste indicated hereinafter in Table 1 were processed according to the process of the invention.

TABLE 1

Type of waste
Name of gas
Gas sample
Sample analysis

processed
sample
receptacle
method

HDPE
Alpha 1
2 L multilayer bag
μGC/MS

HDPE and PP
Alpha 2
2 L multilayer bag
μGC/MS

HDPE, PP and
Alpha 3
2 L Tedlar ® bag
μGC/MS

PET

Tedlar® is a semi-crystalline thermoplastic polyvinyl fluoride.

Table 2 lists the non-methane VOCs produced by the process according to the invention during the processing of the plastics of Table 1 in the presence of air and in a closed reactor containing only the first molten salt bath at 500° C. (+/−20° C.).

TABLE 2