WO2016170000A1

WO2016170000A1 - Method of thermochemical decomposition of waste

Info

Publication number: WO2016170000A1
Application number: PCT/EP2016/058784
Authority: WO
Inventors: Pierlorenzo CAPRANICA; Mario Mattia
Original assignee: Convecom Srl
Current assignee: Convecom Srl
Priority date: 2015-04-22
Filing date: 2016-04-20
Publication date: 2016-10-27
Anticipated expiration: 2017-10-22
Also published as: ITVR20150065A1

Abstract

A method for preparing a combustible liquid and a carbonaceous solid by way of thermochemical decomposition of waste, wherein the combustible liquid comprises some well-determined chemical compounds, independently of the type of waste treated, the invention further relating to a combustible liquid with high calorific value which is obtainable with the method described, among whose components determined chemical compounds can again be found, independently of the type of waste treated.

Description

METHOD OF THERMOCHEMICAL DECOMPOSITION OF WASTE

The present invention relates to a method for obtaining a combustible liquid and a carbonaceous solid by way of thermochemical decomposition of waste.

The disposal of waste nowadays constitutes an extremely felt problem. To seek to limit the amount of waste sent to landfill, methods have been proposed of eliminating the waste by way of combustion at high temperatures (incineration), which produces a gaseous effluent, ash and dust as end products. Such methods are carried out in systems such as incinerators or waste-to-energy plants. With reference to the latest generation of incineration processes, the heat developed during the combustion of the waste is recovered and used to make steam, which is then used for generating electric power or as a heat vector (for example for district heating). While on the one hand incineration plants have made it possible to drastically reduce the quantities of waste sent to landfill, on the other hand they have the principal disadvantage of emitting extremely pollutant compounds into the atmosphere (for example dioxins).

In order to seek to overcome such drawback, methods have been devised for treating the waste which use non-combustive technologies that entail a thermochemical decomposition of the waste, obtaining as end products a combustible liquid or gas and a solid with a residual calorific value. Such methods entail mixing the waste with a vector fluid and with a reaction catalyst and heating it (typically to temperatures lower than 400°C) in the absence of oxygen, so as to prevent any combustion (and therefore the emission of pollutant gaseous compounds).

An example of waste treatment by way of non-combustive technology is described in DE 10049377 which discloses a process for depolymerizing plastic materials and waste in general which contain hydrocarbons. Such process uses a reactor associated with a recirculation evaporator. The reactor, to which the waste to be treated is fed, and the respective connecting ducts are filled with diathermic oil or dense fuel oil mixed with a catalyst. In order to provide the mixture of dense fuel oil and waste with the necessary energy for the chemical decomposition reaction to take place, next to the reactor a burner is provided which is associated with a combustion chamber for the solid residue obtained as a byproduct of the chemical reaction.

EP 1538191 Bl discloses an apparatus in which the necessary heat for the chemical reaction is supplied to the mixture of dense fuel oil and waste, not by way of an exchanger outside the reactor/reaction duct but by acting directly inside the reaction duct using a mechanical agitator adapted to generate a flow against the current with respect to the pumped flow of the mixture of dense fuel oil and waste. The flow against the current, by friction, causes the heating of the mixture.

EP 2113017 Al and WO 2008/102307 Al disclose an apparatus similar to the one disclosed in EP 1538191 Bl , in which the heating of the mixture of dense fuel oil and waste is again achieved by way of conversion of kinetic energy to heat energy (friction) by way of, in this specific case, a pump-turbine which is conceptually similar to the agitator in EP 1538191 Bl .

The solutions proposed in the cited patents suffer, however, drawbacks which are constituted, in particular, by the cost of the agitators (or of the pump-turbine) and by the overall energy balance of the reaction in that the agitators (or the pump-turbine) must use electricity, convert it to kinetic energy and then, by friction, convert that to heat. Merely by way of example, it is estimated that the power absorbed by a pump-turbine in a medium-sized industrial plant according to what is disclosed in EP 2113017 is equal to about 180 kW.

Other patent applications, for example WO 2010/149137 and WO 2010/149138, instead disclose a method of conversion of biomass by way of the direct liquefaction technique using a heavy oil such as service fluid. Furthermore, in all known plants and processes, it is found necessary to intervene on the pumping devices, constituted by mechanically-actuated centrifugal pumps, in order to try to limit losses. Such interventions are extremely complex and expensive, owing to the specific mixture to be pumped which has, typically, a percentage of solids of approximately 30% and high temperatures (about 400°C).

The plants and methods cited, in addition to having the industrial problems noted briefly above, are not optimized to make it possible to obtain fuels (both liquid and solid) with substantially constant chemical characteristics which would therefore represent an added value from the economic viewpoint.

The aim of the present invention is to devise a method for producing a combustible liquid and a carbonaceous solid with residual calorific value, starting from waste materials, which makes it possible to solve the problems and overcome the drawbacks found in the methods and corresponding plants described above.

Within this aim, an object of the invention is to devise a method where the combustible liquid and the carbonaceous solid are obtained without combustion reactions of the waste materials.

Another object of the invention is to devise a method for producing a combustible liquid and a carbonaceous solid which have a high calorific value.

Another object of the present invention is to devise a method for producing a combustible liquid in which determined chemical components are always present, independently of the type of waste used, thus ensuring a final product is obtained that is homogeneous from the viewpoint of the chemical composition and, as a consequence, of the chemical characteristics.

Another object of the invention is to devise a method that is highly reliable and efficacious, is easy to implement even on a large scale, and is low cost, for both implementation and running costs.

This aim and these and other objects which will become better apparent hereinafter are achieved by a method for preparing a combustible liquid and a carbonaceous solid by way of thermochemical decomposition of waste, which comprises the steps of:

(a) preparing a reaction mixture comprising the waste and a vector fluid consisting of an oil selected from the group consisting of: a diathermic oil, a mineral oil and mixtures thereof;

(b) keeping the reaction mixture at a temperature comprised between 320°C and 370°C and at a pressure comprised between -200 mbarg and

+200 mbarg for a time comprised between 90 and 180 minutes;

(c) extracting and rectifying the combustible liquid from the reaction mixture by way of a fractional distillation column;

(d) separating the carbonaceous solid from the vector fluid by way of a thin-layer evaporator;

wherein the combustible liquid comprises the following components:

(i) linear and/or ramified aliphatic hydrocarbons having from 8 to 25 carbon atoms;

(ii) phenol, optionally substituted with one or more groups independently selected from alkyl, alkenyl, alkoxy and hydroxyl;

(iii) polycyclic aromatic hydrocarbons, optionally substituted with one or more groups independently selected from alkyl, alkenyl, alkoxy and hydroxyl;

(iv) sulfur-containing aromatic compounds, optionally substituted with one or more groups independently selected from alkyl, alkenyl, alkoxy and hydroxyl;

(v) nitrogenous aromatic compounds, optionally substituted with one or more groups independently selected from alkyl, alkenyl, alkoxy and hydroxyl.

Further characteristics and advantages of the invention will become better apparent from the description of some preferred, but not exclusive embodiments of the method for preparing a combustible liquid and a carbonaceous solid with residual calorific value according to the invention.

In the description that follows, individual characteristics, indicated in relation to specific embodiments of the invention, can be interchanged or combined with other characteristics, indicated in relation to other specific embodiments of the invention.

In a first aspect, as noted, the present invention relates to a method for preparing a carbonaceous solid and a combustible liquid that comprises determined chemical components, by using the thermochemical decomposition of waste. As described above in more detail, the method comprises the steps of:

(a) preparing a reaction mixture comprising the waste and a vector fluid;

(b) maintaining such mixture at the conditions necessary for the thermochemical decomposition reaction of the waste to take place;

(c) extracting and rectifying the combustible liquid from the mixture, by way of fractional distillation;

(d) separating the carbonaceous solid from the vector fluid.

The reaction mixture prepared in step (a) comprises, together with the waste, a vector fluid; such vector fluid is an oil, and is selected from the group consisting of: a diathermic oil, a mineral oil and mixtures thereof. In particular, the mineral oil can be exhausted or not exhausted. Examples of diathermic oils that can be used in the reaction mixture are heavy paraffmic oils, preferably solvent-dewaxed. Examples of mineral oils that can be used in the reaction mixture are paraffin-based and/or polyalphaolefm-based lubricant oils derived from oil refining.

The waste to be processed is usually ground until it reaches a size category of approximately 8-10 mm before being mixed with the vector fluid. In addition to the waste and the vector fluid, the reaction mixture prepared in step (a) can further comprise one or more catalysts in order to increase the speed of the thermochemical decomposition reaction of the waste. The effect of the one or more catalysts in terms of product yield depends on the type of waste, but usually the presence of the one or more catalysts increases conversion of the waste to the form of combustible liquid by approximately 30-40%.

The one or more catalysts are independently selected from the group consisting of solid materials whose active site (catalytic site) has acid, basic, or amphoteric characteristics. As is known to the person skilled in the art, an amphoter can exhibit both acid and basic behavior according to the chemical conditions in which it happens to be; examples of amphoteric catalysts can be doped acid materials with basic compounds dispersed in the crystalline structure. In the context of the present invention, the acidity and the basicity of the active sites of the catalysts are evaluated according to the Lewis theory or according to the Bronsted-Lowry theory. Since the one or more catalysts and the reagents are present in two different phases (respectively solid and fluid), the catalysis is heterogeneous. When the one or more catalysts are present in the reaction mixture, their quantity is comprised between 0.1% and 1% by weight on the total weight of the mixture.

Preferably, the one or more catalysts can be independently selected from metallic oxides. In a more preferred embodiment, the catalyst can be aluminum oxide. In another more preferred embodiment, the catalyst can be magnesium oxide.

The reaction mixture prepared in step (a) takes the physical form of a slurry, i.e. a dense form of fluid in which a solid (in this case, the ground-up waste) is pulverized within a liquid (in this case, the vector fluid). The physical form of slurry is particularly advantageous in that it makes it possible for the reaction mixture to be pumped through the reaction circuit of the plant in which the thermochemical decomposition takes place, thus always keeping the reaction circuit active. At the industrial level, therefore, the method of the invention can be carried out in continuous operation.

Step (b) of the method consists of keeping the reaction mixture at a temperature comprised between 320°C and 370°C and at a pressure comprised between -200 mbarg and +200 mbarg for a time comprised between 90 and 180 minutes. Since, as mentioned above, the method can be carried out continuously, the reaction time indicated must therefore be considered an estimate of the time necessary for the decomposition reaction of the waste to take place, and therefore of the average time the waste spends inside the reaction system. In the above conditions of temperature and pressure, the thermochemical decomposition reaction of the waste in the mixture takes place. It should be noted that the reaction temperature of the method is kept at a considerably lower value than that of a traditional catalytic cracking process (600-700°C). By operating at a temperature (320- 370°C) and in the absence of atmospheric oxygen, the formation is avoided of pollutant substances such as dioxins and furans, which are particularly damaging to health and to the environment. In a preferred embodiment, the reaction temperature can be comprised between 340°C and 360°C; more preferably, the reaction temperature can be comprised between 345°C and 355°C.

Once the waste present in the mixture has undergone the thermochemical decomposition, the end products, i.e. the combustible liquid and the carbonaceous solid, can be extracted from the mixture.

The combustible liquid is extracted from the reaction mixture and rectified by way of a fractional distillation column (step (c) of the method), into which the vapors of hydrocarbons produced by the thermochemical decomposition reaction are conveyed. The column separates the vapors of hydrocarbons and condenses them into two fractions: (i) light liquid hydrocarbons (for example kerosene) and (ii) combustible liquid comprising heavy liquid hydrocarbons. The light hydrocarbons exit from the head of the distillation column, while the combustible liquid is collected by way of a lateral offtake from the column and filtered in order to retain the solid particulate that may be present. In an embodiment, if it is not desired to separate the light liquid hydrocarbons from the combustible liquid, it is possible to carry out the extraction exclusively from the head of the column and collect the mixture of light liquid hydrocarbons and combustible liquid.

In a preferred embodiment, the rectifying of the combustible liquid by way of a distillation column can occur at a head temperature comprised between 150°C and 300°C and at a head pressure comprised between 300 mbar abs and 600 mbar abs.

Over time, carbonaceous substances deriving from the reaction, inert compounds that are already present in the raw material and, possibly, exhausted catalyst, tend to accumulate in the reaction environment, saturating it and leading to an increase in the density of the slurry. To prevent this phenomenon, the slurry can be diluted by way of the addition of further vector fluid, or, preferably, it is necessary to eliminate the aforementioned substances from the reaction circuit, in order to prevent clogging. This operation is carried out by drawing some of the slurry from the reaction circuit, and treating it in order to extract the carbonaceous solid from the vector fluid (step (d) of the method) and recovering the latter. The separation of the carbonaceous solid from the vector fluid occurs by way of vacuum flash evaporation and the evaporator used is the thin-layer type. The vector fluid (oil) evaporates, separating from the solid residue, and subsequently the vapors are recondensed and recovered. The solid residue is discharged from the bottom of the evaporator and cooled to a temperature comprised between 70°C and 80°C.

Preferably, the temperature at which the evaporation occurs can be comprised between 280°C and 340°C and the pressure can be comprised between 2 mbar abs and 40 mbar abs. As noted, the method according to the present invention makes it possible to prepare a combustible liquid that comprises (i) linear and/or ramified aliphatic hydrocarbons having from 8 to 25 carbon atoms, (ii) phenol, (iii) polycyclic aromatic hydrocarbons, (iv) sulfur-containing aromatic compounds and (v) nitrogenous aromatic compounds, where each one of the components (ii), (iii), (iv) and (v), independently of the others, can be substituted with one or more groups, independently selected from alkyl, alkenyl, alkoxy and hydroxyl. In a preferred embodiment, each alkyl group, independently of each other, can have a chain having from 1 to 8 carbon atoms. More preferably, such chain can have from 1 to 4 carbon atoms. In the same way, in another preferred embodiment, each alkenyl group, independently of each other, can have a chain having from 1 to 8 carbon atoms. More preferably, such chain can have from 1 to 4 carbon atoms. Similarly, each alkoxy group, independently of each other, can have a chain having from 1 to 8 carbon atoms. More preferably, such chain can have from 1 to 4 carbon atoms.

The starting raw material which is degraded by way of thermochemical decomposition in the method of the invention is represented by discarded materials of various types, i.e. waste. In a preferred embodiment of the invention, it is possible to use waste with a high calorific value. In a particularly preferred embodiment, the waste with high calorific value can be, by way of example, refuse-derived fuels (RDF), car fluff, or solid biomasses. It is also possible to use mixtures of such waste with a high calorific value.

Refuse-derived fuels (RDF), commonly known as eco-bales, are solid fuels obtained from suitably selected and treated waste, and they are usually used to fuel waste-to-energy plants. The term "car fluff indicates the waste obtained from the demolition of cars and pulverized in the form of fluff, i.e. similar to confetti. The term "solid biomasses" defines any solid fuel based on organic matter, except for fossil fuels and plastics of petrochemical origin.

Independently of the type of waste used as the starting material, the following are always present in the combustible liquid produced with the method of the invention: (i) linear and/or ramified aliphatic hydrocarbons having from 8 to 25 carbon atoms, (ii) phenol, (iii) poly cyclic aromatic hydrocarbons, (iv) sulfur-containing aromatic compounds and (v) nitrogenous aromatic compounds, where the components (ii)-(v) can be optionally substituted as described previously. However, the combustible fluid can contain further components, which can vary according to the initial waste.

In particular, when the waste used as the starting material is RDF, car fluff or mixtures thereof, the combustible liquid can further comprise one or more of the following components:

(i) aliphatic heterocyclic compounds optionally substituted with one or more groups independently selected from alkyl and alkenyl;

(ii) benzene substituted with one or more groups independently selected from alkyl and alkenyl;

(iii) naphthalene, optionally substituted with one or more groups independently selected from alkyl and alkenyl;

(iv) biphenyl, optionally substituted with one or more groups independently selected from alkyl and alkenyl.

In a preferred embodiment, the aliphatic heterocyclic compounds present in the combustible liquid obtained using RDF, car fluff or mixtures thereof as the starting material can comprise one or more heteroatoms independently selected from the group consisting of nitrogen, sulfur and oxygen.

In another preferred embodiment, the linear and/or ramified aliphatic hydrocarbons present in the combustible liquid obtained using RDF, car fluff or mixtures thereof as the starting material can have from 12 to 22 carbon atoms. More preferably, such linear and/or ramified aliphatic hydrocarbons can have from 16 to 20 carbon atoms.

In a further preferred embodiment, the substituted benzene present in the combustible liquid obtained using RDF, car fluff or mixtures thereof as the starting material can be trimethylbenzene or methylstyrene.

Furthermore, the alkyl and alkenyl groups that can be present as substituents of the aliphatic heterocyclic compounds, benzene, naphthalene and biphenyl which are present in the combustible liquid obtained using RDF, car fluff or mixtures thereof as the starting material, can have a chain with a number of carbon atoms comprised between 1 and 8. More preferably, such chain can have a number of carbon atoms comprised between 1 and 4.

However, when the waste used as the starting material is solid biomasses or mixtures thereof, the combustible liquid can further comprise one or more of the following components:

(i) fatty acid esters;

(ii) benzoic acid, optionally substituted with one or more groups independently selected from alkyl, alkenyl, alkoxy and hydroxyl;

(iii) aliphatic esters of benzoic acid, optionally substituted with one or more groups independently selected from alkyl, alkenyl, alkoxy and hydroxyl;

(iv) heterocyclic aromatic compounds, in which the heteroatom is nitrogen, optionally substituted with at least one substituent comprising oxygen;

(v) linear and/or cyclic alkenes.

In a preferred embodiment, the combustible liquid obtained using solid biomasses or mixtures thereof as the starting material can comprise linear fatty acid esters, ramified fatty acid esters, or a mixture of linear and ramified fatty acid esters. Furthermore, such combustible liquid can comprise saturated fatty acid esters, unsaturated fatty acid esters or a mixture of saturated and unsaturated fatty acid esters. In another preferred embodiment, the alkyl, alkenyl and alkoxy groups that can be present as substituents of the benzoic acid and its aliphatic esters which are present in the combustible liquid obtained using solid biomasses or mixtures thereof as the starting material, can have a chain with a number of carbon atoms comprised between 1 and 8. More preferably, such chain can have a number of carbon atoms comprised between 1 and 4.

Preferably, the aromatic heterocyclic compounds where the heteroatom is nitrogen, which are present in the combustible liquid obtained using solid biomasses or mixtures thereof as the starting material, can be substituted by a methoxy group. More preferably, such aromatic heterocyclic compounds where the heteroatom is nitrogen can be substituted by a methoxy group and a hydroxyl group.

The method disclosed herein can be carried out in an apparatus of the type disclosed in Italian patent no. 1408057, extended to PCT/EP2012/065532 (WO 2013021011).

Another aspect of the invention relates to the combustible liquid obtainable by way of the method described herein.

In such combustible liquid, some chemical components are always present, independently of the type of waste used as the starting material; the presence of further chemical components depends on the type of waste treated.

In particular, linear and/or ramified aliphatic hydrocarbons having from 8 to 25 carbon atoms, phenol, polycyclic aromatic hydrocarbons, sulfur-containing aromatic compounds and nitrogenous aromatic compounds are always found in the combustible liquid prepared with the method of the invention, irrespective of the type of waste treated. Phenol, polycyclic aromatic hydrocarbons, sulfur-containing aromatic compounds and nitrogenous aromatic compounds can optionally be substituted with one or more groups, independently selected from alkyl, alkenyl, alkoxy and hydroxyl, as described previously with reference to the method.

Furthermore, if the waste treated is RDF, car fluff or mixtures thereof, the combustible liquid can further comprise one or more of the following components:

(i) aliphatic heterocyclic compounds;

(iii) naphthalene;

(iv) biphenyl.

Aliphatic heterocyclic compounds, naphthalene and biphenyl can optionally be substituted with one or more groups, independently selected from alkyl and alkenyl, as described previously with reference to the method.

On the other hand, if the waste treated is solid biomasses or mixtures thereof, the combustible liquid can further comprise one or more of the following components:

(i) fatty acid esters;

(ii) benzoic acid;

(iii) aliphatic esters of benzoic acid;

(v) linear and/or cyclic alkenes.

Benzoic acid (both as such and in the form of its aliphatic esters) can be optionally substituted with one or more groups independently selected from alkyl, alkenyl, alkoxy and hydroxyl, as described previously with reference to the method.

As noted, the method according to the present invention makes it possible to prepare a combustible liquid and a carbonaceous solid whose chemical/physical characteristics are exemplified in the examples that follow.

EXAMPLES:

Below are the analytic results carried out on two carbonaceous solids obtained with the method according to the invention.

Sample 1 : dried solid obtained by thermochemical decomposition of solid biomass (sawdust). Solid with presence of small to medium agglomerates, blackish, odorless.

Sample 2: carbon obtained by thermochemical decomposition of car fluff. Powdered solid with presence of small to medium agglomerates, black, odorless. Unit of

Parameter Analysis method measure Result ment

CNR IRSA 2 Q 64 Vol 2

Residue at 105°C % p/p 98.62

1984

CNR IRSA 2 Q 64 Vol 2

Residue at 600°C % p/p 31.96

1984

Lower calorific value UNI EN 15400:2011 kJ/kg 24,259

Gross calorific value UNI EN 15400:2011 kJ/kg 25,612

Carbon (C) UNI EN 15407:2011 % p/p 54.61

Nitrogen (N) UNI EN 15407:2011 % p/p 0.57

Hydrogen (H) UNI EN 15407:2011 % p/p 6.12

EPA 5050 1994 + EPA

Sulfur (S) % p/p 0.28

9056 A 2007

In light of the foregoing, in practice it has been found that the method according to the present invention fully achieves the set aim in that it makes it possible to obtain a combustible liquid and a carbonaceous solid starting from waste materials, without the problem and drawbacks associated with the methods used to date. In particular, by way of the method of the invention the production of the combustible liquid and of the carbonaceous solid occurs without resorting to combustion reactions of the waste materials, thus avoiding the emission of pollutant substances. Furthermore, the combustible liquid and the carbonaceous solid produced with the method described herein have a high residual calorific value.

Also, the method of the invention results in a combustible liquid that always comprises some well-determined chemical components, independently of the type of waste used, thus making it possible to maintain the homogeneity of the final product. The method for preparing a combustible liquid and a carbonaceous solid by way of thermochemical decomposition of waste according to the present invention, and the combustible liquid obtainable by such method, thus conceived, are susceptible of numerous modifications and variations, all of which are within the scope of the appended claims; moreover, all the details may be substituted by other, technically equivalent elements, the correspondence of which is known to the person skilled in the art.

The disclosures in Italian Patent Application No. VR2015A000065 (102015902345991) from which this application claims priority are incorporated herein by reference.

Claims

1. A method for preparing a combustible liquid and a carbonaceous solid by way of thermochemical decomposition of waste, which comprises the steps of:

(b) keeping the reaction mixture at a temperature comprised between 320°C and 370°C and at a pressure comprised between -200 mbarg and +200 mbarg for a time comprised between 90 and 180 minutes;

wherein the combustible liquid comprises the following components:

2. The method according to claim 1, wherein the reaction mixture prepared in step (a) further comprises 0.1% to 1% by weight on the total weight of the mixture of one or more catalysts of the thermochemical decomposition reaction that are independently selected from the group consisting of solid materials whose active site has acid, basic or amphoteric characteristics.

3. The method according to claim 2, wherein the one or more catalysts of the thermochemical decomposition reaction are independently selected from the group consisting of metallic oxides.

4. The method according to any one of claims 1 to 3, wherein in step (b) the reaction mixture is kept at a temperature comprised between 345°C and 355°C.

5. The method according to one or more of the preceding claims, wherein rectifying the combustible liquid by way of a distillation column occurs at a head temperature comprised between 150°C and 300°C and at a head pressure comprised between 300 mbar abs and 600 mbar abs.

6. The method according to one or more of the preceding claims, wherein separating the carbonaceous solid from the vector fluid by way of a thin-layer evaporator occurs at a temperature comprised between 280°C and 340°C and at a pressure comprised between 2 mbar abs and 40 mbar abs.

7. The method according to one or more of the preceding claims, wherein each alkyl group, each alkenyl group and each alkoxy group has, independently of each other, a chain having from 1 to 4 carbon atoms.

8. The method according to one or more of the preceding claims, wherein the waste is selected from the group consisting of refuse-derived fuels (RDF), car fluff, solid biomasses and mixtures thereof.

9. The method according to claim 8 wherein, when the waste is RDF, car fluff or mixtures thereof, the combustible liquid further comprises one or more of the following components:

(i) aliphatic heterocyclic compounds optionally substituted with one or more groups independently selected from alkyl and alkenyl; (ii) benzene substituted with one or more groups independently- selected from alkyl and alkenyl;

10. The method according to claim 9, wherein the aliphatic heterocyclic compounds comprise one or more heteroatoms independently selected from the group consisting of nitrogen, sulfur and oxygen.

11. The method according to claim 8, wherein, when the waste is

RDF, car fluff or mixtures thereof, the linear and/or ramified aliphatic hydrocarbons have from 16 to 20 carbon atoms.

12. The method according to claim 8, wherein, when the waste is solid biomasses or mixtures thereof, the combustible liquid further comprises one or more of the following components:

(i) fatty acid esters;

(v) linear and/or cyclic alkenes.

13. The method according to claim 9 or claim 12, wherein each alkyl group, each alkenyl group, and each alkoxy group has, independently of each other, a chain having from 1 to 4 carbon atoms.

14. A combustible liquid obtainable from the method according to one or more of the preceding claims, which comprises the following components: