Method and related equipment for gasifying carbonaceous materials by catalytic action in molten salt

Abstract

The solid carbonaceous material is contacted with a first molten salt bath in the presence of air for a predetermined period of time, the first molten salt bath being a mixture of NaCl, MgCl 2 , CaCl 2 , KCl, FeCl 2 and having a melting point equal to or greater than 300° C., a density measured in the liquid state and at atmospheric pressure greater than 1, and a specific heat capacity measured in the liquid state and at atmospheric pressure that is less than the specific heat capacity of water measured at a temperature of 25° C. and at atmospheric pressure, and wherein the gas formed is recovered, characterized in that the recovered gas is brought into contact with a second molten salt bath, which may be different from the first bath, and at the outlet of the second bath, the gas is stored, which may be under pressure, or is reinjected into the first or second bath. The invention also relates to an installation making it possible to carry out this method.

Description

Technical Field

[0001] The present invention relates to the conversion of carbonaceous substances into gas, particularly into volatile hydrocarbons. This method can be advantageously applied to waste of various origins and compositions.

Background Art

[0002] Wastes, particularly plastics, especially thermosetting plastics and / or halogen-containing substances, are difficult to recycle. Most of them are landfilled. Nevertheless, methods for recycling plastic wastes have been proposed. Some of them use molten inorganic salts.

[0003] For example, Patent Document 1 discloses a method for recycling plastics using molten salts. To increase the contact surface area between the plastics to be treated, the molten salts are sprayed onto plastic particles of less than 30 mm. The molten salts used are a mixture of sodium carbonate, potassium carbonate, and other carbonates having a melting point that is lower than 50 °C but higher than 50 °C.

[0004] Patent Document 2 discloses a method for recycling a plurality of printing plates. The printing plates are pulverized and then immersed in a molten salt bath composed of sodium carbonate and / or potassium carbonate. Air is used as a gasifying agent. The temperature of the bath is from 900 °C to 1000 °C.

[0005] Non-Patent Document 1 discloses the state of the art of thermal decomposition and gasification of biomass using a molten salt bath. Halides are known to have a catalytic effect on the decomposition of some compounds. Alkali metal carbonates are known to have a catalytic effect in carbon gasification in the presence of water vapor and carbon dioxide. This publication also describes that thermal decomposition of wood was carried out at 600 °C to 900 °C using a salt mixture of carbonate and chloride (NaCl and KCl). Lignin can be thermally decomposed at a temperature of 500 °C to 800 °C in a mixture of ZnCl2 and KCl.

[0006] Regarding waste, Non-Patent Document 1 above shows that the thermal decomposition of household waste is possible in molten Na2CO3 at 870°C to 1000°C. Polyethylene, polystyrene, and PVC were thermally decomposed in a molten mixture of MgCl2 and KCl at temperatures between 640°C and 850°C. The main products obtained were methane and ethylene. A eutectic mixture of NaOH and Na2CO3 at temperatures between 420°C and 480°C also allows for the thermal decomposition of PVC, polystyrene, polypropylene, and polyethylene. Plastic waste containing rubber was thermally decomposed in a liquid mixture of NaCl / AlCl3 at 380°C to 570°C and converted to gas.

[0007] Similarly, Non-Patent Document 1 describes how waste paper was gasified in a bath of molten carbonate at a temperature between 700 and 750°C in the presence of water vapor and carbon dioxide. In the case of tissue paper, a mixture of Li2CO3 and Na2CO3 is used. Lithium carbonate (Li2CO3) allows for the acquisition of more CO2. Alkali metals, with their smaller atoms, have greater catalytic power than other metals because they diffuse more easily into waste. Nevertheless, calcium tends to reduce the reaction yield by limiting contact between the paper and CO2.

[0008] Other studies have demonstrated the gasification of paper waste in the presence of CO2 and a molten carbonate bath at temperatures between 650°C and 750°C. The presence of molten Na2CO3 allows for catalytic action in the CO2 attack on the paper. The addition of K2CO3 and LiCO3 increases the yield.

[0009] Non-patent document 1 also states that the treatment plant sludge and rice were gasified in the presence of carbon dioxide and at a temperature between 500°C and 750°C using a bath of Li2CO3 and K2CO3. Nevertheless, SO2 was present in the resulting gaseous phase. X The compound was discovered.

[0010] Patent Document 3 discloses a method for destroying organic substances containing sulfur and / or halogens and / or toxic metals. The bath used contains alkalis and alkaline earth oxides and / or alkali sulfates. This method is applied to the gasification of tires. Patent Document 4 discloses a method for decomposing hydrocarbon substances (hydrocarbons) in a molten salt bath. The bath contains either a mixture of lithium oxide, potassium oxide and boron oxide, or a mixture of phosphorus pentoxide and sodium oxide. Thus, gaseous C3 hydrocarbons are obtained. Gasification is carried out with an airflow under atmospheric pressure.

[0011] Patent Document 5 discloses a method for treating solid or liquid hydrocarbon substances, such as coal, lignite, liquids derived from coal, bitumen, wood, or other biomass or shale oil, by a molten salt bath. The bath may contain a mixture of the following salts: KCl, LiCl, NaCl, CaCl2, or carbonates.

[0012] Patent document 6 discloses a method for recycling plastics using a pyrolysis solution which may be a bath of molten nonferrous metals containing at least zinc, tin, aluminum, lead, copper, and alloys thereof. [Prior art documents] [Patent Documents]

[0013] [Patent Document 1] Chinese Patent Application Publication No. 105385468 Specification [Patent Document 2] Chinese Patent Application Publication No. 102389888 Specification [Patent Document 3] French Additional Patent Publication No. 0070789 [Patent Document 4] French Patent Application Publication No. 2156050 Specification [Patent Document 5] UK Patent Application Publication No. 2106932 [Patent Document 6] International Publication No. 2014 / 167139 [Non-patent literature]

[0014] [Non-Patent Document 1] Review of thermal processing of biomass and waste in molten salts for production of renewable fuels and chemicals, International Journal of low-carbon technologies, 2012, Volume 7, p.318~324 [Overview of the project] [Problems that the invention aims to solve]

[0015] The object of the present invention is to provide a gasification method that can reduce or suppress the formation of volatile oxygen compounds. In fact, these compounds cannot be recovered and are considered undesirable by-products.

[0016] Another object of the present invention is to provide a method for gasifying carbonaceous materials that is easy to implement and, in particular, can be carried out in air.

[0017] Another object of the present invention is to provide the above method without using too much energy to reach the melting of the salt.

[0018] Another object of the present invention is to provide a gasification method that enables the acquisition of volatile hydrocarbons, in particular pentane, propene, ethane, and ethylene.

[0019] Another object of the present invention is to provide a method that makes it possible to obtain hydrocarbons containing 7, 8, 9 or more carbon atoms in a small proportion (less than 8% by mass).

[0020] Another object of the present invention is to provide a method capable of obtaining at least 30% by mass of linear unsaturated hydrocarbons (ethylene, propylene and butene) containing 2 to 4 carbon atoms.

[0021] Another object of the present invention is to provide a gasification method that can be implemented using a variety of carbonaceous substances, where the carbonaceous substances are composites (e.g., plastics, especially, e.g., thermosetting polymers), organic substances (wood, cardboard, plant waste) or mixtures (wet household waste containing organic substance residues (food packaging)).

[0022] Another object of the present invention is to provide a method that does not necessarily require the grinding of carbonaceous substances and enables the obtaining of volatile hydrocarbons even when solid substances are provided in the form of fragments of different dimensions, and especially, fragments of about several centimeters or about 10 centimeters.

[0023] Another object of the present invention is to provide a method that is found to be effective even when the carbonaceous substance is contained in a plastic bag (e.g., heterogeneous carbonaceous substances such as household waste containing plants and plastics).

Means for Solving the Problems

[0024] The present invention - The solid carbonaceous substance is contacted with a first molten salt bath for a predetermined period In the presence of air and The first step Here, the first molten salt bath contains at least one chloride-based salt selected from NaCl, MgCl2, CaCl2, KCl, FeCl2, and has a melting point of 300 °C or higher, a density greater than 1 measured under liquid state and atmospheric pressure, and a specific heat capacity always smaller than the specific heat capacity of water measured at a temperature of 25 °C and atmospheric pressure (i.e., smaller than 4.18 kJ / kg·K), and has a specific heat capacity measured under liquid state and atmospheric pressure do, - In the first step mentioned above the gas formed is recovered Second process by,This invention relates to a method for gasifying solid carbonaceous materials by catalytic action in a molten salt.

[0025] A key feature of the present invention is that the recovered gas is brought into contact with a second molten salt bath, which may be optionally different from the first bath, and at the outlet of the second bath, the gas is stored under optionally pressurized conditions or reinjected into the first or second bath.

[0026] Passage through the second bath allows for the conversion of volatile oxygen compounds into recoverable alkanes, alkenes, or alkynes that no longer contain oxygen. If passage through the second bath is insufficient, the gaseous mixture recovered at the outlet of the second bath can be added to the first bath or returned to the second bath. The second bath may also be the first bath, in which case there are two passes within the same enclosure containing the first bath.

[0027] Oxygen-containing gaseous compounds can be formed in significant amounts, depending on the properties of the carbonaceous material being processed. Therefore, if the carbonaceous material contains lignin or cellulose, oxygen compounds will be much more abundant than in the case of plastic waste.

[0028] The second bath allows for the decomposition of organic compounds (such as ethanal) formed by reaction with oxygen in the air above the first bath into hydrocarbons.

[0029] Advantageously, the gas is brought into contact with the second bath by bubbling the gas in the second bath. However, this contact is not limited to bubbling.

[0030] Advantageously, the gas is introduced below the free surface level of the second bath and through the maximum height of the bath. Thus, the gas can be injected from the bottom of the tank containing the second bath.

[0031] The density of the first bath allows for good catalytic action of the reaction, and carbonaceous material is found almost entirely suspended in the bath (between the two waters) or on the surface of the bath.

[0032] Preferably, throughout this patent application, the density and specific heat capacity are measured at the melting point of the bath.

[0033] Since the reaction can be carried out in the presence of air, the method is easy to implement and does not require the presence of water vapor or carbon dioxide, as in prior art methods. Furthermore, the implementation of the equipment is also simpler.

[0034] The bath preferably has a density lower than 2.2, which represents the maximum density of plastics. Therefore, inert waste (such as rubble, bricks, concrete, and stones) sinks in the bath and can be easily removed.

[0035] The melting point of the first bath is preferably 650°C or lower. This temperature makes it possible to obtain a molten material without excessive energy consumption.

[0036] The fact that the specific heat capacity of the first bath is lower than that of water allows for rapid dissolution of the salt and also enables relatively rapid cooling, which is advantageous when the method is carried out discontinuously (in batch mode).

[0037] Most chlorides Salt of the system The first bath is preferably sodium chloride. Salt of the system It may also consist solely of calcium chloride. It may also consist of sodium chloride.

[0038] According to the present invention, the composition of the first bath is not limited. It may further include at least one hydroxide selected from LiOH, NaOH, KOH, Ca(OH)2, Fe(OH)2, and / or at least one oxide selected from K2O, Na2O, CaO, P2O5, and / or at least one carbonate selected from Li2CO3, Na2CO3, K2CO3, CaCO3, and / or at least one nitrite compound selected from NaNO2 and NaNO3.

[0039] Advantageously, when the first bath contains at least one carbonate, the mass content of the carbonate in the first bath is less than 10%. This amount allows for limiting the melting point of the first bath while maintaining good catalytic activity.

[0040] Advantageously, the first bath has a melting point of the first chloride. Salt of the system The melting point is lower than that of the plurality of chlorides Salt of the system It contains at least one salt with a melting point lower than the lowest melting point of the bath. This salt mixture can partially separate phases when solidified, which helps to limit corrosion of the bath. The bath housing the bath is advantageously made of stainless steel.

[0041] According to one advantageous embodiment of the first bath described above, it comprises a chloride salt (preferably sodium chloride), a salt having a melting point lower than the melting point of chloride, and one or more oxides and one or more carbonates in less than 5%. Such a bath enables the implementation of the method according to the present invention. One or more carbonates are selected from the carbonates cited above. One or more oxides are selected from the oxides cited above.

[0042] According to the present invention, the composition of the second bath is not limited. It may have a melting point above 300°C, and / or it may further contain at least one chloride other than sodium chloride. This second bath makes it possible to purify the inverts of carbonaceous material that have been gasified in the first bath. The gas bubbles in the second bath, ensuring a rapid reaction. The volume of the second bath may be less than the volume of the first bath. Even if the melting point is high, if the volume is small, the energy consumption to obtain melting becomes reasonable. The second bath may also be heated by some of the heat generated by the first bath.

[0043] According to one embodiment that can be combined with each of the above embodiments, the second bath comprises at least one iodide and / or fluoride. The iodide can be selected from, in particular, LiI, NaI, KI, and AlI3, but is not limited to these. The fluoride can be selected independently of the iodide from, in part, the following salts, namely LiF, NaF, KF, CaF2, MgF2, and Na3AlF6, but is not limited to these.

[0044] Therefore, the second bath may also contain at least one carbonate in an amount exceeding 10% by mass.

[0045] The pressure above the first bath may be equal to or greater than atmospheric pressure. Preferably, it is equal to atmospheric pressure. The temperature above the first bath is, for example, at least 100°C.

[0046] Advantageously, the contact between the first bath and the carbonaceous material is carried out within an air-filled enclosure, which is then sealed after the carbonaceous material is introduced into the enclosure. In this way, the use of a second bath can be avoided. Oxygen is consumed at the start of the reaction, and organic compounds containing oxygen atoms are produced. These are produced in small quantities because the enclosure is closed and the amount of oxygen is reduced. Furthermore, these can also be converted to hydrocarbons by recycling in the first bath (a second pass).

[0047] The reaction can also be initiated in air and then continued in an atmosphere where gaseous oxygen is depleted (preferably less than 20% by volume). Thus, the amount of oxygen-containing organic compound formed can be limited.

[0048] Solid carbonaceous materials are advantageous, - Solid waste containing one or more plastics selected from ABS, cellulose acetate (CA), polyamide, polybutylene terephthalate (PBT), polycarbonate, polyethylene, PET, HDPE, PP, PVC, PTFE, LDPE, PMMA, polyformaldehyde (POM), PVAC, styrene-acrylonitrile copolymer, optionally foamed polystyrene, PEEK, thermosetting resins including silicone in particular, and mixtures of at least two of these plastics, or solid waste consisting of the one or more plastics, -Waste containing animal organic matter or waste consisting of animal organic matter, and / or waste containing optionally processed plant organic matter, including paper, cardboard, wood, and plant waste, or waste consisting of said plant organic matter, and mixtures of these two types of waste, and - The above waste may optionally be present in a mixture of plastics selected from ABS, cellulose acetate (CA), polyamide, polybutylene terephthalate (PBT), polycarbonate, polyethylene, PET, HDPE, PP, PVC, PTFE, LDPE, PMMA, polyformaldehyde (POM), PVAC, styrene-acrylonitrile copolymer, optionally foamed polystyrene, PEEK, thermosetting resins including silicone, and mixtures of at least two of these plastics, or the above waste may optionally be placed in a bag made from the above plastics. They are selected from among them.

[0049] Therefore, household waste containing plastics and organic materials can be treated in the same way as construction waste, which often contains plastic insulation. It is even possible to treat these types of waste together.

[0050] The carbonaceous material is advantageously provided in the form of components with a thickness of several millimeters, such as plastic bags, films, or sheets. The surface area of ​​these components is not limited. Nevertheless, the carbonaceous material can be provided in the form of components with a thickness or diameter of several centimeters, within the dimensions of the first bath. The carbonaceous material can obviously be pre-ground, but this is not essential.

[0051] Regardless of the mode of implementation of the method according to the present invention, the contact with the second bath is 20 volume The process is carried out in a closed enclosure containing a gas mixture containing less than % oxygen, where the gas mixture may optionally be at a pressure lower than atmospheric pressure.

[0052] Advantageously, the pressure of the gas mixture located above the second bath is reduced before contact with the recovered gas. The reduction in oxygen content above the bath reduces the formation of oxygen compounds.

[0053] When the gas obtained and recovered from the first bath contains water vapor, the water vapor is condensed before being introduced into the second bath.

[0054] In fact, if the carbonaceous material contains water, the water evaporates and passes through the first bath. It is important not to condense the water vapor and introduce it into the second bath. The present water absorbs the energy required for evaporation at the expense of the catalytic reaction, and therefore, the presence of water increases the energy consumption of the method.

[0055] The present invention also relates to equipment that enables the implementation of a method for any one of the inventions described in the above claims.

[0056] This equipment is - The first may optionally be in a molten state. salt or An enclosure containing a salt mixture, wherein the first salt or The salt mixture contains at least one chloride salt selected from NaCl, MgCl2, CaCl2, KCl, and FeCl2, and has a melting point of 300°C or higher, a density greater than 1 measured in the liquid state and under atmospheric pressure, and a specific heat capacity measured in the liquid state and under atmospheric pressure that is less than the specific heat capacity of water measured at a temperature of 25°C and under atmospheric pressure. - The first of the above salt or A means of heating a salt mixture to enable its melting, - solid A conveyor of carbonaceous material, wherein the conveyor is the solid The inlet into which carbonaceous material is introduced, and the aforementioned solid carbonaceous Matter , comprising the molten first salt or salt mixture It has an outlet positioned to drop into the first bath, - A gas recovery means connected to the enclosure and opening above the first bath, and -Equipped with an inlet connected to the gas recovery means, and second salt or Second reactor, which can contain a salt mixture. - The second of the above salt or A heating means capable of melting a salt mixture, Equipped with, Here, the second reactor may optionally be provided with at least one screen for forming bubbles of a given size, and the second reactor is provided with a first pipe connecting the outlet of the second reactor to a storage tank, and the outlet of the second reactor is the One bath The enclosure may optionally be provided with a second pipe located below the surface, which connects to the area of ​​the enclosure or to the inlet of the second reactor.

[0057] The second reactor is the second salt or When a tank containing a salt mixture is provided, the inlet of the second reactor is melted The aforementioned Second salt or It is positioned below the level of the free surface of the salt mixture, which allows for contact by bubbling of the recovered gas.

[0058] The enclosure and the second reactor are of sufficient size to accommodate the gas or gaseous mixture in a volume located above the first bath. The resulting gaseous hydrocarbons are stored in this volume.

[0059] According to one embodiment that can be combined with each of the above embodiments, the second reactor is provided with means for making it gas-sealed, and the equipment is melted The second of the above salt or Prior to contact between the salt mixture and the recovered gas, the reactor is equipped with means that function as a pump to reduce the pressure of the gaseous mixture contained in the second reactor. Therefore, if the second reactor is equipped with a tank containing a second bath, the means that function as a pump will enable a reduction in the pressure of the gas volume located above the free surface of the second bath prior to contact with the gas recovered before the second bath.

[0060] Regardless of the embodiment, the apparatus is advantageously equipped with means for condensing steam, the condensing means being located upstream of the storage tank and / or on the second piping, and upstream of the first enclosure and / or the second reactor.

[0061] Advantageously, the enclosure and / or second reactor further comprises means for isolating / closing the enclosure from the external environment. These means make it possible to prevent the produced gas from being released into the external environment and also prevent the formation of excessively large amounts of oxygenated organic compounds produced for reaction with oxygen from the air. Means that function as a pump may also be equipped in the enclosure including the first bath, which makes it possible to reduce the amount of oxygen that can react with carbonaceous material by reducing the pressure above the first bath (after introducing the waste to be processed and isolating the enclosure).

[0062] The second reactor may be a liquid / gas exchange column operated in parallel or countercurrent flow.

[0063] According to one embodiment, the second reactor is the second salt or The reactor is equipped with a tank containing a salt mixture, and the inlet of the second reactor is melted The second of the above salt or It is placed below the level of the free surface of the salt mixture, preferably at the bottom of the tank.

[0064] The enclosure may be equipped with a removable grate at the bottom for removing inert material (such as rubble).

[0065] The equipment according to the present invention can be buried at least partially. Therefore, at least the first bath can be buried underground. Only the entrance to the conveyor is available to allow the insertion of carbonaceous material into the first bath. The second bath and / or storage tank can also be buried.

[0066] It is clear that all the features of the molten salt bath cited with reference to the method according to the present invention can be applied to salt mixtures (molten or non-molten salts) that may be used in the equipment according to the present invention.

[0067] definition The predicate “volatile hydrocarbons” means saturated, unsaturated (alkenes, alkynes), cyclic, and unsaturated cyclic hydrocarbons having a vapor pressure of 0.01 kPa or greater at a temperature of 293.15 K. More specifically, it can consist of hydrocarbons that are saturated or unsaturated, optionally cyclic (also saturated or unsaturated), and contain one to five carbon atoms. These can optionally be branched and substituted with one or more residues selected from the following groups: methyl or ethyl.

[0068] The predicate "carbonaceous substance" means any substance comprising carbon atoms, hydrogen atoms, and optionally other atoms, such as oxygen atoms, sulfur atoms, or halogen atoms. In the sense of the present invention, an organic substance is a carbonaceous substance.

[0069] The predicate “solid carbonaceous material” means a material that is divided without any dimensional constraints and may contain water or oil, in small amounts. Dispersions or emulsions (sludges) of carbonaceous material in a liquid are not considered carbonaceous material in the sense of this invention.

[0070] drawing The present invention, its technical features, and the various advantages provided thereby will become more apparent by reading the following description relating to specific embodiments of the invention, which are presented as non-limiting examples and refer to the accompanying drawings below. [Brief explanation of the drawing]

[0071] [Figure 1] Figure 1 shows a schematic diagram of a specific embodiment of the present invention. [Figure 2] Figure 2 shows a specific embodiment of the tank and conveyor. [Figure 3] Figure 3 shows three alternative embodiments of the second molten salt bath. [Modes for carrying out the invention]

[0072] Referring to Figure 1, specific embodiments of the apparatus and methods of implementation according to the present invention are described. The apparatus comprises an enclosure 1 containing a first molten salt bath. The surface of the first liquid bath is indicated by a line segment L. Heating means (not shown) can melt the salt, which was initially solid, and form a liquid phase that forms the molten salt bath. The enclosure is provided with a drain pipe 3, which opens into the bottom of the enclosure at the bottom of the bath and allows for draining of the enclosure 1. The enclosure also comprises a removable screen 11 that allows for the retention of solid material that is not decomposed by the bath. Two conveyors 5 extend above the surface of the bath and allow for the transport of waste accumulated at their inlets 51 into the bath. The enclosure 1 can be sealed at the outlets of the conveyors 5 by means such as hatches. The apparatus comprises a column 2 containing a second molten salt bath. A valve V1 can regulate the gas flow from the enclosure 1 into the column 2. The outlet of column 2 is connected to a storage tank 6 for pressurizing the gas. Valve V2 is used to regulate the gas flow into the storage tank 6. Upstream of valve V2 is a bypass pipe 23, which allows the outlet of column 2 to be connected to enclosure 1. The bypass pipe 23 opens into enclosure 1 at a position below the surface L of the first molten salt bath. Valve V3 is equipped on the bypass 23 and is used to regulate the gas flow recycled to the first bath. The dotted line SS represents the floor surface. In Figure 1, enclosure 1 is embedded and the conveyor inlet 51 is flush with the ground. It is also possible to embed column 2.

[0073] Next, a mode of implementation of the method according to the present invention will be described with reference to Figure 1. The carbonaceous material to be processed is transported to the facility, for example, by truck. This may consist of solid waste. Waste in the form of solid particles suspended in a liquid (sludge) cannot be processed by the method according to the present invention. The waste is introduced into a conveyor 5 at its inlet 51. The conveyor 5 carries the waste into an enclosure and drops it into a first molten salt bath. The bath is pre-formed by melting salt by a heating means (not shown). Depending on its density, the waste either sinks in the bath or floats on the surface of the bath. Inert waste with a density greater than that of the carbonaceous waste (e.g., rubble, bricks, concrete, stones), especially plastics, sinks to the bottom of the bath and accumulates on the screen 11. This waste is later removed at the end of the process. After the waste is introduced, the inlet 51 is sealed by means such as a hatch, and the salts are melted (batch operation). The enclosure 1 contains air above the surface of the first bath. The decomposition reaction of carbonaceous materials into hydrocarbons is catalyzed by ions in the first bath. This reaction consumes oxygen in the air contained in enclosure 1 above the surface L of the first bath. Since enclosure 1 is sealed, the reaction starts in an air atmosphere. The reaction then continues in an oxygen-depleted atmosphere, i.e., an atmosphere that no longer contains oxygen. Due to the absence of oxygen, the yield of hydrocarbons, especially volatile hydrocarbons, increases regardless of the type of carbonaceous material being processed. As hydrocarbons are formed, the pressure above the first bath increases. When the pressure reaches a predetermined value indicating that the enclosure contains almost all (volatile or non-volatile) hydrocarbons, valve V1 is opened. The gas enters column 2 containing a second molten salt bath. The gas then undergoes a second catalytic decomposition in this second bath. The second bath makes it possible to increase the yield of volatile hydrocarbons. The second bath can be used in column 2 through which the gas to be processed is bubbling. Column 2 and various alternative embodiments thereof are described in more detail with reference to Figure 3. In column 2, the gas undergoes a second decomposition. At the outlet of column 2, depending on the composition of the outflowing gas stream, this flow is directed (partially or completely) towards storage tank 6.All or part of the flow may be redirected again to a first bath located inside enclosure 1 for further processing. The gas is injected into the bath, passes through it in the form of bubbles, and is then decomposed again within the bath.

[0074] Next, one embodiment of the method of the present invention will be described with reference to Figure 1, in the case of waste containing plastic, which may optionally be wet or partially covered with organic material (e.g., food packaging). The waste is introduced into conveyor 5, for example, by a garbage truck. After the waste is introduced, the inlet 51 is sealed, for example, by a hatch or other means, and the salts are melted. The waste is placed in a plastic bag. The bag is dropped into the first molten salt bath. Due to its density, the bag sinks immediately into the bath. Enclosure 1 is in communication with the outside at conveyor 5. A catalytic reaction occurs immediately, and various gases are produced above the bath. The enclosure is not in communication with the outside. The enclosure optionally includes a flange cover connected to a column 2 or tank 6. Because oxygen is present in the air, volatile hydrocarbons and ethanal compounds are also produced simultaneously. When the bath temperature is 500°C and the pressure is 1 bar, the temperature above the bath is at least 100°C. When the pressure above the first molten salt bath reaches a predetermined value, the produced gas is passed through a second molten salt bath. This second molten salt bath makes it possible to convert oxygen-containing compounds into volatile hydrocarbons. An analytical instrument attached to the outlet of column 2 can indicate the concentration of volatile hydrocarbons in the gaseous mixture at the outlet of column 2. If the composition is considered sufficient, i.e., if it contains more than 90% by volume of volatile hydrocarbons, the gas stream is directed towards the storage tank. Otherwise, the gas stream is directed towards the first molten salt bath or the second molten salt bath, depending on its composition and the compounds to be decomposed into volatile hydrocarbons (see Table 2).

[0075] Next, with reference to Figure 2, a specific embodiment of the enclosure 1 and conveyor 5 will be described. Elements common to those in Figure 1 are referred to by the same numbers. In Figure 2, the enclosure 1 includes a cylindrical container 11 containing a first bath (liquid not shown) at its lower part. The upper part of the enclosure is a parallelepiped and is open to the outside via the conveyor 5. Three faces of this part are connected to the conveyor 5. A hatch is not shown. The catalytic reaction always takes place after the introduction of waste, sealing of the inlet 51, and melting of the salt. The outlet 61 is connected to the storage tank 6. The outlet 231 can recirculate the formed gas toward the first bath. The complete setup does not necessarily include a second bath.

[0076] Next, with reference to Figure 3, three alternative embodiments of the second bath will be described. Please note that the second bath is optional.

[0077] Referring to Figure 3, column 2 comprises two screens 220 positioned above each other along the height of the column. These screens allow the gas flow to be processed to be divided into bubbles of a predetermined size. The black arrows indicate gas circulation from bottom to top. Molten salt, i.e., liquid salt, circulates from top to bottom, from inlet 210 to outlet 211. The gas and salt circulate in a countercurrent. The bubbles promote and accelerate the catalytic reaction by increasing the contact surface area between the gas and salt.

[0078] In Figure 3, the second reactor includes a second bath. When the reactor is not full, air may remain above the second bath until the space not occupied by the molten salt is filled with an inert atmosphere. The gas is introduced to the center of the reactor by an inlet pipe 25 so that it bubbles 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 in the second bath, the treated gas is discharged from an outlet 27 at the top of the reactor.

[0079] Next, with reference to Figure 3, a third alternative embodiment will be described. The second reactor 2 is horizontal and includes a second bath. Preferably, the second bath fills only half of the second reactor 2. The inlet and outlet piping are equipped with screens 220 that allow for bubble formation at the reactor inlet and outlet. The second salt bath is stationary, as in the second alternative embodiment. [Examples]

[0080] Example 1 Table 1 shows that the following different types of waste were treated according to the method of the present invention.

[0081] [Table 1] Tedlar® is a semi-crystalline thermoplastic polyvinyl fluoride.

[0082] Table 2 lists the non-methane VOCs produced by the method according to the present invention during the processing of the plastics in Table 1 in the presence of air and in a closed reactor containing only a first molten salt bath at 500°C (±20°C).

[0083] [Table 2]

[0084] The results in Table 2 show that by using a catalyst containing only one chloride salt (sodium chloride in this case), a salt with a melting point lower than the melting point of the chloride, and less than 5% oxides and carbonates, the majority of the volatile hydrocarbons produced are pentane, propene, ethane, and ethylene.

[0085] Table 3 summarizes the total values ​​of the specific hydrocarbons obtained.

[0086] [Table 3]

[0087] Considering Table 3, it can be observed that hydrocarbons containing seven or more carbon atoms are present in samples Alpha 1, Alpha 2, and Alpha 3 at only 7.17% by mass, 6.68% by mass, and 4.66% by mass, respectively.

[0088] The linear unsaturated hydrocarbons having 2, 3, and 4 carbon atoms represent the hydrocarbon content at 31.31% by mass, 51.34% by mass, and 40.53% by mass, respectively.

[0089] The presence of oxygen made it possible to produce aldehydes and ketones. These oxygen compounds can be decomposed exclusively into hydrocarbons and carbon monoxide during passage through the second bath, particularly by bubbling, and therefore, in the absence of oxygen.

Claims

1. - A first step in which a solid carbonaceous material is brought into contact with a first molten salt bath in the presence of air for a predetermined period of time. Here, the first molten salt bath is NaCl, MgCl ２ CaCl ２ , KCl, FeCl ２ It comprises at least one chloride-based salt selected from, and has a melting point of 300°C or higher, a density greater than 1 measured in the liquid state and under atmospheric pressure, and a specific heat capacity measured in the liquid state and under atmospheric pressure that is less than the specific heat capacity of water measured at a temperature of 25°C and under atmospheric pressure. - The gas formed in the first step is recovered in the second step. A method for gasifying a solid carbonaceous substance by catalytic action in a molten salt, A method for gasifying a solid carbonaceous substance by catalytic action in a molten salt, characterized in that the gas recovered from the second step is brought into contact with a second molten salt bath that is the same as or different from the first molten salt bath, and the gas obtained at the outlet of the second molten salt bath is stored or reinjected into the first molten salt bath or the second molten salt bath.

2. The method according to claim 1, characterized in that the gas obtained at the outlet of the second molten salt bath is stored under pressure.

3. The method according to claim 1, characterized in that the gas recovered from the second step is brought into contact with the second molten salt bath by bubbling the gas in the second molten salt bath.

4. The method according to claim 3, characterized in that the gas recovered from the second step is injected from the bottom of the tank containing the second molten salt bath.

5. The first molten salt bath further contains at least one hydroxide selected from LiOH, NaOH, KOH, Ca(OH) ２ , Fe(OH) ２ , and / or at least one oxide selected from K ２ O, Na ２ O, CaO, P ２ O ５ , and / or at least one carbonate selected from Li ２ CO ３ , Na ２ CO ３ , K ２ CO ３ , CaCO ３ , and / or at least one nitrite compound selected from NaNO ２ and NaNO ３ . The method according to claim 1, characterized in that it contains the above components.

6. The method according to any one of claims 1 to 5, characterized in that the first molten salt bath contains at least one carbonate, and the mass content of the carbonate is less than 10%.

7. The method according to any one of claims 1 to 5, characterized in that the first molten salt bath contains at least one salt whose melting point is lower than the melting point of the one chloride-based salt or lower than the lowest melting point of the plurality of chloride-based salts.

8. The method according to any one of claims 1 to 5, characterized in that the second molten salt bath has a melting point above 300°C and / or further comprises at least one chloride different from sodium chloride.

9. The method according to any one of claims 1 to 5, characterized in that the second molten salt bath contains at least one iodide and / or fluoride.

10. The method according to any one of claims 1 to 5, characterized in that the second molten salt bath contains at least one carbonate in an amount exceeding 10% by mass.

11. The method according to any one of claims 1 to 5, characterized in that the contact between the first molten salt bath and the solid carbonaceous material is carried out in an enclosure containing air, and the enclosure is sealed after the solid carbonaceous material has been introduced into the enclosure.

12. The method according to claim 11, characterized in that the sealed enclosure contains a gas mixture containing less than 20 volume percent of oxygen gas.

13. The aforementioned solid carbonaceous material is - Solid waste containing one or more plastics selected from ABS, cellulose acetate (CA), polyamide, polybutylene terephthalate (PBT), polycarbonate, polyethylene, PET, HDPE, PP, PVC, PTFE, LDPE, PMMA, polyformaldehyde (POM), PVAC, styrene-acrylonitrile copolymer, polystyrene, expanded polystyrene, PEEK, thermosetting resins including silicone, and mixtures of at least two of these plastics, or solid waste consisting of the one or more plastics, - Waste containing animal organic matter or waste consisting of said animal organic matter, and / or waste containing plant organic matter including paper, cardboard, wood, and plant waste or waste consisting of said plant organic matter, and mixtures of these two types of waste, - The waste in a mixture of plastics selected from at least two mixtures of these plastics, including ABS, cellulose acetate (CA), polyamide, polybutylene terephthalate (PBT), polycarbonate, polyethylene, PET, HDPE, PP, PVC, PTFE, LDPE, PMMA, polyformaldehyde (POM), PVAC, styrene-acrylonitrile copolymer, polystyrene, expanded polystyrene, PEEK, thermosetting resins including silicone, and the waste in a bag made from the said plastics, wherein the said waste refers to waste containing animal organic matter or waste consisting of said animal organic matter, and / or waste containing plant organic matter including paper, cardboard, wood, and plant waste or waste consisting of said plant organic matter, and mixtures of these two types of waste. The method according to any one of claims 1 to 5, characterized in that it is selected from among.

14. The method according to any one of claims 1 to 5, characterized in that the contact with the second molten salt bath is carried out in a closed enclosure containing a gas mixture containing 20% ​​by volume or less of oxygen.

15. The method according to claim 14, characterized in that the gas mixture is at a pressure below atmospheric pressure.

16. The method according to any one of claims 1 to 5, characterized in that the gas formed in the first step contains water vapor, and the water vapor is condensed before being introduced into the second molten salt bath.

17. - Enclosure (1) comprising a first salt or salt mixture, Here, the first salt or salt mixture is NaCl, MgCl ２ CaCl ２ , KCl, FeCl ２ It comprises at least one chloride-based salt selected from, and has a melting point of 300°C or higher, a density greater than 1 measured in the liquid state and under atmospheric pressure, and a specific heat capacity in the liquid state and under atmospheric pressure that is less than the specific heat capacity of water measured at a temperature of 25°C and under atmospheric pressure. - Means for heating the first salt or salt mixture to enable its melting, - At least one conveyor (5) for solid carbonaceous material, Here, the conveyor includes an inlet (51) into which the solid carbonaceous material is introduced, and an outlet arranged so that the solid carbonaceous material falls into a first bath containing the molten first salt or salt mixture. - A gas recovery means connected to the enclosure (1) and opening above the first bath, and - A second reactor (2) having an inlet connected to the gas recovery means and capable of containing a second salt or salt mixture, - Heating means capable of melting the second salt or salt mixture Equipped with, The apparatus is characterized in that the second reactor (2) is provided with a first pipe connecting the outlet of the second reactor (2) to a storage tank (6), thereby enabling the implementation of the method according to any one of claims 1 to 5.

18. The apparatus according to claim 17, characterized in that the second reactor (2) comprises at least one screen (220) that forms bubbles of a given size.

19. The apparatus according to claim 17, characterized in that the second reactor (2) comprises a second pipe connecting the outlet of the second reactor (2) to a region of the enclosure (1) located below the surface of the first bath or to the inlet of the second reactor (2).

20. The apparatus according to claim 17, characterized in that the second reactor (2) comprises a tank containing the second salt or salt mixture, and the inlet of the second reactor (2) is positioned below the level of the free surface of the molten second salt or salt mixture.

21. The apparatus according to claim 17, characterized in that the second reactor (2) is provided with means for making it airtight, and the apparatus is provided with means that function as a pump for reducing the pressure of the gas mixture contained in the second reactor (2) before bringing the second salt or salt mixture into contact with the recovered gas from the gas recovery means.

22. The apparatus according to claim 17, comprising means for condensing steam, wherein the means for condensing steam is located upstream of the storage tank (6) and / or on the second piping, and is located upstream of the enclosure (1) and / or the second reactor (2).

23. The apparatus according to claim 17, further comprising means for isolating / closing the enclosure (1) and / or the second reactor (2) from the external environment.

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