WO2015071697A1

WO2015071697A1 - Gasifier for the production of synthesis gas

Info

Publication number: WO2015071697A1
Application number: PCT/IB2013/002549
Authority: WO
Inventors: Alberto ZUCCHELLI.
Original assignee: Apeiron Technology Incorporation
Priority date: 2013-11-15
Filing date: 2013-11-15
Publication date: 2015-05-21

Abstract

The invention concerns a plant for generating synthesis gas from biomass, comprising one or more gasification cells (10) with an intake for organic material (18) and an outlet for extracting the synthesis gas produced, characterised in that each cell comprises nozzles for introducing an air-and-CO₂ mixture, connected to an air/CO₂ mixer (4) which adjusts the quantities and proportions of air/CO₂ supplied to each gasification cell through said nozzles. Furthermore, the invention concerns a process for generating a synthesis gas from a solid organic material, comprising the following steps: introducing an organic material into a gasification cell (10); introducing preheated CO₂ or a preheated air/CO₂ mixture through a plurality of nozzles into the gasification cell (10); primary partial oxidisation of the organic material by means of the preheated CO₂ or a preheated air/CO₂ mixture with consequent generation of a synthesis gas, inert material and latent heat; extraction of the synthesis gas from the cell and starting to exploit its energy.

Description

GASIFIER FOR THE PRODUCTION OF SYNTHESIS GAS

The present invention refers to a plant and a corresponding process for generating a synthesis gas (syngas) starting from an organic material, preferably in the solid state. Furthermore, the present invention refers to a plant and a corresponding process for converting an organic material, preferably in the solid state, into a synthesis gas (syngas) of excellent quality, but at the same time variable according to the use for which it is destined.

Plants are known for converting a solid organic material into thermal and electrical energy, which first partially convert the organic material into a mixture containing a synthesis gas and a partially oxidised gas. This partial conversion (primary oxidisation) occurs in an oxidiser called the primary oxidiser. Immediately afterwards, the known plants proceed with a complete oxidisation of this mixture of said gases to obtain heat, and thus to generate vapour at high pressure. This complete oxidisation (secondary oxidisation) takes place in what is called the secondary oxidiser. The vapour generated is then sent to a turbine to obtain electrical energy.

The phase of oxidisation (primary and secondary oxidisation) can occur by means of :

- (i) incinerators suitable for almost totally oxidising the starting organic material, in the presence of air and excess oxygen, during the first phase of the process at temperatures of the order of 900-1000°C, for giving off a gas containing water, CO2 and organic material and, subsequently, suitable for superheating the oxidised gas in order to destroy any organic material still contained in it, converting it completely to CO2 and water;

- (ii) gasifiers suitable for initially converting the starting organic material into a mixture of synthesis gas and oxidised gases, by means of airflows which are such as to generate partial combustion with formation of CO, H_2l a little C0₂ and a little H₂0, at a temperature of around 600-800°C and, subsequently, for completely oxidising the mixture of synthesis gas and oxidised gases at a temperature of around 900°C;

- (iii) pyrolysers suitable for heating the organic-based material, without the latter coming into contact with the air, so as to bring them to the liquid phase in order to be able then to use them as combustible oils (pyrolysis oils).

The principal limitations of the known systems described above concern, on the one hand, the starting organic material to be treated and, on the other hand, the characteristics of the product of the process.

As far as the first category of limitations is concerned, in incineration systems (i), because of the high temperatures used, it is not possible to treat materials containing metals which would otherwise tend to melt during the process. Furthermore, the level of humidity in the intake materials must be fairly limited, to avoid the need to use auxiliary fossil fuels to keep the system active. Fluid bed gasification systems (ii), in order to function correctly, need an intake material which must be absolutely homogeneous in grain size and humidity content. Furthermore, the intake material absolutely cannot contain either glass or metals, on pain of blocking the system. Static bed gasification systems (ii), on the other hand, can accept intake materials contaminated with metals and glass, but cannot ever exceed 50% humidity in the intake material. Pyrolysis systems (iii) require the material with which they are charged to be always homogeneous in grain size, quality and humidity, otherwise the process will not be capable of developing a fuel oil with constant characteristics.

As regards the second category of limitations, this refers to the limits imposed by the characteristics of the "product" of the process, that is to say, of what is generated by the process. Incineration systems (i), for example, can produce only heat. The quantity of heat produced depends directly on the nature of the material treated which can be regulated with extreme difficulty and only through the injection of fossil fuels. Gasification systems (ii), even though they do produce a synthesis gas, generally burn it because of the poor quality of the gas, producing in fact only heat. Some gasification systems, in the attempt to utilise the synthesis gas directly in internal combustion motors, are forced to set up complex purification systems which are extremely costly from an energy point of view. The purification processes normally reduce the calorific value of the synthesis gas to 60% of the value of the calorific power of the starting organic matter. Pyrolysis systems (iii) produce a fuel oil with rather interesting energy characteristics but similar to those of a heavy oil and, therefore, rather difficult to burn in a normal internal combustion engine.

Finally, the known art encounters certain limitations deriving from the characteristics of the combustion fumes. Incineration systems produce rather polluted fumes which often contain hazardous pollutants such as dioxins and fine powders. Reducing these pollutants is normally achieved through the use of very complex and expensive filtration systems.

Fairly clean fumes are, however, produced by gasification systems which normally avoid the production of dioxins, because of the considerable quantity of hydrogen liberated during the process. Even pyrolysis systems are not in themselves very polluting, but the subsequent combustion for energy purposes of the oil produced by the process can cause considerable environmental problems if not suitably treated.

In view of the problems present in the state of the art it is therefore an object of the present invention to make available a plant and a corresponding treatment for generating a synthesis gas capable of accepting as intake a solid organic material having a variable grain size, format and humidity content, i.e. without there being the need for any pretreatment system, in order to be able to handle the broadest possible range of sources and types of material at the lowest possible cost.

Another object of the present invention is to make available a plant and a corresponding process for converting a solid organic material into a synthesis gas (syngas) of excellent quality, but at the same time of quality variable according to the use for which it is destined.

Yet another object of the present invention is to make available a plant and a corresponding process for generating a synthesis gas with variable chemical and physical characteristics and therefore capable of being best adapted to systems specified for its use, as well as producing this synthesis gas with a high degree of efficiency, so as to contain within its chemical bonds the majority of the energy contained in the organic material from which it originated.

In addition, the plant and the process of the present invention aim at obtaining solid process sub- products practically free of carbon and, therefore, completely inert and reusable, as well as obtaining gaseous process sub-products not containing toxic substances or in any way polluting and harmful for the environment.

These objects and yet others which will become clear from the detailed description which follows have been achieved by the Applicant by means of a plant and a corresponding process for generating syngas having the characteristics defined in the attached independent claims.

Preferred embodiments are described in the detailed description which follows and in the attached dependent claims without wishing in any way to limit the scope of the present invention.

The plant for generating synthesis gas according to the invention comprises one or more reclosable gasification cells, with a dedicated inlet for accepting solid organic material and an outlet for extraction of the synthesis gas produced. The plant is characterised in that each of said cells comprises nozzles for introducing preheated C0₂ or a preheated air-C0₂ mixture connected to a pump or a mixer for air/C0₂ capable of adjusting the quantity of CO2 and the proportions of air/C0₂ in the mixture supplied to each gasification cell through said nozzles. One or more of said cells are reclosable, preferably hermetically, so as to avoid both the ingress of unwanted air and leaks of synthesis gas, and thus ensure an even better controlled atmosphere inside each cell.

In this way the preheated CO2 or the preheated air/C0₂ mixture, defined in percentages of air and C0₂ preferably in a ratio comprised from 1:100 to 100:1, permits the occurrence of the process of gasification with the characteristics required by the user. The type and degree of oxidisation depend on the ratio that is used between air and CO2. For example, with a small amount of air, partial oxidisation (without flame) occurs, with the formation of CO and H2 and latent heat, while by increasing the content of air and, therefore, of O2, complete oxidisation occurs with the formation of C0₂ and H2O and perceptible heat.

For example, a gasification cell can have the form of a parallelepiped with a base of about 20 square metres and a height of about 3 metres, with a total volume of about 60 cubic metres. The nozzles are preferably arranged on the sides and on the base. For example, there may be a nozzle every 20-30 square centimetres. The solid organic material in one cell, such as the one exemplified above, can burn without flame for example with a velocity of about 15-25 centimetres per hour.

The plant according to the invention has a simple structure, easy to construct, in which the cells contain many nozzles which introduce preheated or heated air/CC^. For this reason the plant accepts as intake any type of organic material, provided that it is in the solid state, without the need to execute any pretreatment upstream, and with a level of relative humidity even of up to 90%.

The nozzles introduce into the gasification cell preheated/heated CO2 or a preheated/heated mixture of air and CO2. The term 'air" refers to a gas having a determinate content of oxygen (comburent) at a pressure of 1 atmosphere and 25°C. The CO2 or the mixture of air and CO2 must be preheated or heated. At a temperature below 200°C I am able to eliminate the water present in the solid organic material without causing any oxidisation.

In one embodiment, the CO2 or the mixture of air and CO2 is preheated to a temperature comprised from 200 to 300°C, which makes it possible to adequately bring about oxidisation without a flame, to give a synthesis gas.

The plant and the corresponding process of the present invention have a high efficiency compared with the known systems. This is due to the fact that the known systems use the energy contained in the starting organic material to produce the dissociation between the atoms of carbon and hydrogen present in the organic material with formation of CO and H2, while in the present invention preheated CO2 is used, conserving all the energy of the chemical bonds in the syngas (latent heat). Furthermore, the CO2 or the mixture of air/C02 are heated using the waste energy with a temperature of about 350°C, which in the systems of the known art is not exploited at all.

Furthermore, thanks to the low temperatures adopted in the gasification cells, the metals and silicates present in the organic material do not melt (sometimes they have melting points below 400°C). In one embodiment, the plant for generating synthesis gas from a solid organic material comprises furthermore an energy recovery system (secondary oxidiser) for oxidising the synthesis gas and/or converting it to hydrogen. The synthesis gas arrives at the energy recovery system (secondary oxidiser) at a temperature of about 400°C and contains CO and H2. Said energy recovery system is connected to the outlet of one or more gasification cells to receive its synthesis gas, and to the intake of the mixer to supply exhausted gas containing CO2 to one or more gasification cells via the mixer. Optionally, before introducing the exhausted gas containing CO2 and H2O (which at the outlet of the energy recovery system has a temperature of about 350°C) to the mixer and thus to the gasification cells, the exhausted gas can be recycled through a filtration system to provide purified exhausted gas containing CO2 and using an energy storage system (a thermal conservation device for storing the heat produced in the plant. At the outlet of the energy recovery system and at the entrance to the energy storage system, the gas containing C0₂ and H₂0 has a temperature of about 350°C. At the outlet of the energy storage system and at the entrance to the filtration system, the gas containing CO2 a

Apart from the exhausted gas CO2 and H2O, oxidisation in the energy recovery system produces heat which can be exploited inside the plant or, alternatively, sent outside to be used, for example, for generating electricity or thermal energy or chemical energy.

The energy recovery system can consist, in a first alternative, of a combustion chamber (burner) inside which the synthesis gas is oxidised in the presence of an excess of oxygen. This process leads to the formation of heat and exhausted gases (CO2 and H2O), which are subsequently normally used for the production of electricity using a steam or diathermic oil turbine.

In a second alternative, the energy recovery system can comprise a fuel cell of SOFC type (Solid Oxide Fuel Cell), for direct production of electricity, heat and CO2.

Finally, in a third alternative, the energy recovery system can comprise a so-called "water shift reactor", suitable for direct conversion of synthesis gas into hydrogen, heat and CO2.

Advantageously, the plant for generating synthesis gas from a solid organic material comprises furthermore a heat conservation device for storing the heat produced in the plant. Said device is connected to the intake where air/C02 are introduced to the device, and at the outlet to a fan connected to the energy recovery system, and to a pump or a mixer for introducing CO2 or a mixture of air/C02 to the gasification cell. The heat conservation device enables heating the CO2 and air to about 300°C, making it possible to recover and optimise the exploitation of this waste energy, which would otherwise be lost. This energy recovery makes it possible to increase the efficiency of the plant and the process of the invention. This strategy is extremely useful in recovering the waste heat, which is normally dispersed, allowing the plant extremely high efficiency in converting the organic matter into synthesis gas.

The conservation device enables the plant, given the discontinuous nature of the gasification process, to conserve the unused residual heat from the process, for subsequent use in the stages of preheating the gasification and oxidising mixtures, for example.

In an advantageous embodiment of the plant for generating synthesis gas from a solid organic material, there is also provided a preheating device. Said preheating device is used for increasing the temperature of the intake air to the heat conservation device or to the mixer, connected in its turn to the gasification cells or to the fan, connected in its turn to the energy recovery system.

If the temperature of the air/CCk mixture forming the intake to the gasification cell or the intake to the energy recovery system is itself at a temperature below 200-300°C or if, alternatively, having been sent to the heat conservation device, the air/C02 mix is ever at an insufficient temperature, the preheating system manages simply and effectively to make up the necessary heat. This situation can occur, for example, at the start when the plant is stationary and it begins operating.

A particularly advantageous improvement in the area of environmental compatibility consists of providing a filtering device, connected to the energy recovery system, to clean the exhausted gases before reusing them in the gasification cell or emitting them from the plant. The filtering device ("filter" or "purifier") receives a gas containing CO2 and H2O at a temperature greater than 100°C and may consist of a chemical reactor, inside which any polluting substances are neutralised, and a self-cleaning sleeve filter. For example, the chemical reactor which receives a gas containing CO2 and HCI, the latter obtained as a result of the presence of PVC in the solid organic material, can use lime or other basic substances to form insoluble or barely soluble salts. In this case the intake gas is purified to CO2. In this way it is possible to avoid any pollution of the atmosphere by exhausted gases emitted from the plant, and the carbon dioxide produced by the plant can be made into a usable product by photosynthesis- type processes.

Equally, for ecological reasons it is advantageous to have available in the plant of the invention a condenser for recovering the water contained in the exhausted gases. In fact, the water contained in the organic substances is not only represented by what is contained between the fibres of the organic material, normally known as humidity, but also by the water which is released because of the chemical reaction of oxidisation. Water being a valuable asset, instead of evaporating it into the environment, the plant will recover it and make it available for any industrial or photosynthesis processes connected with the plant itself. In a particularly advantageous embodiment, one or more gasification cells comprise temperature and pressure sensors, known to the expert in the field, which are connected to a continuous analyser which analyses the quality of the synthesis gas produced. The sensors are dedicated to monitoring for example the quantity of CO, C02, water and hydrogen. On the basis of the gas analysis, the plant's control system intervenes to adjust the temperature and/or volume and/or composition of the mixture of air/C02 delivered via the mixer to the gasification cells. By analysing the data from the sensors put at the service of the gasification cell, the analysis system defines the characteristics of the air/C02 mix, in order to obtain the desired gasification result.

The invention makes available a static gasification system capable of producing a synthesis gas with variable chemical and physical properties depending on the needs of a user who requires production of heat only and/or production of the energy carrier hydrogen. Thanks to its intrinsic characteristics, the system creates an environment unfavourable to the formation of pollutants such as dioxin and fine powders; furthermore, thanks to the low temperatures adopted in the gasification cells, it does not melt metals and silicates with a melting point higher than 400°C. The solid wastes of the system generally consist of carbon-free white ash.

Figure 1 shows a perspective view of a gasification cell used in a plant for generating synthesis gas from biomass according to the invention. Gasification cells are known to the expert in the field.

Figure 2 shows an operating scheme of a plant for generating synthesis gas from a solid organic material, according to the invention.

A detailed description of the present invention will be given below.

Figure 1 represents an embodiment of the gasification cells 10 according to the invention. The cell can naturally have dimensions varying according to the need to dispose of solid organic material or produce a synthesis gas. The cell comprises preferably metal structure having the form of a parallelepiped with a substantially rectangular or square base. Inside it a refractory material is applied which resists the temperatures that form during gasification, about 300-400°C.

In this embodiment of the invention, the cell 10 is provided with a large door located in the upper wall; when the upper part of the cell is completely open, it allows the organic material to be loaded. A door located in the lower part of the cell ensures that inert materials can be unloaded, once the gasification process is completed. Inside the cell, preferably on the base and the walls, there are a quantity of nozzles (about 1 nozzle every 20-30 square centimetres), through which CO2 or a heated mixture of air and carbon dioxide is introduced, by means of a pump or a mixer 4. This mixture, supplied by the mixer 4 (see fig. 2), is superheated and, once the percentage of air and water has been defined, enables the process of gasification to take place with the characteristics required by the user. The upper part of the cell contains the duct for extracting the synthesis gas produced during the process of gasification (not visible in Figure 1).

The gasification cell 10 is provided with a series of temperature and pressure sensors, as well as a continuous analyser capable of analysing the quality and quantity of gas produced. The data from the sensors is first analysed by the analyser and then used in the control system to define the characteristics of the air/C02 mix forming the intake to the cell so as to achieve the desired gasification result.

Figure 2 represents an operating scheme of the plant according to the invention. The organically based material, solid organic material 18, without any upstream pretreatment and in the conditions of grain size and humidity in which it is (for example small balls of vegetable waste from agriculture), is loaded into one of the gasification cells 10.

After the cell 10 has been hermetically closed, a mixture containing air/CC>2, preheated or heated to 300°C, coming from the mixer 4, is introduced by means of the fan 2.

The organic material, present inside the cell, in contact with the hot air, begins a process of gasification and partial oxidisation (without flame).

The synthesis gas which forms is immediately analysed, and its qualitative and quantitative composition is used to determine the composition of the mixture of air and CO2 and its temperature, in order to obtain the desired quality of synthesis gas. In particular the composition of the air/C0₂ mix is defined through the mixer 4, the temperature is sampled from the heat storage system 12 and, if insufficient, is topped up through the preheating system 17, while the quantity of the mix is defined by modifying the flow of the fan 2. The synthesis gas is extracted from the gasification cell 10 and ducted to the energy recovery system 11 , as long as there is organic-based material in the cell.

On the completion of the phase of gasification of the organic-based material, which has an average duration of about 20-24 hours, the bottom of the cell 10 is opened and the non-volatile materials present in the charge are expelled 7, to be treated if necessary with screens or magnets for subsequent exploitation as recyclable metals, glass and mineral salts. The synthesis gas is transported to the energy recovery system 11 and oxidised by the introduction of preheated air, from the preheating system 17 or from the heat storage system 12, in quantities determined by the fan 1. In the energy recovery system 11 the calorific power of the synthesis gas is converted into electricity, thermal energy or into hydrogen (chemical energy) and sent to have its energy exploited 15.

The oxidised gases, which after they have been exploited for energy purposes still maintain a temperature close to 350°C, are sent to the heat storage system 12, where part of the heat which they contain is conserved for future use. Next, the oxidised gases are driven, by means of the tail fan 3, into the filtering system 6 and subsequently deprived of their water content in the water recovery system 13. The gases sent towards the filtering system 6 are first passed through a reactor which, by the use of suitable chemical reagents such as lime or other suitable basic substances neutralises any unwanted compounds. They are then filtered through a normal sleeve filter before being expelled. The water arising from the recovery system 13 is expelled 14 for subsequent use, for example for irrigating a greenhouse. The resulting exhausted gases, composed mainly of CO2 and N2, are redirected by the CO2 mixer in circulation 5 towards the heat recovery system 12 or the expulsion system 9, for example towards a greenhouse, depending on the needs of the system.

The plant and the method of the present invention advantageously feature high flexibility and variability of operation thanks to the fact that as the intake material 18 varies, the element 12 (heat storage system) stabilises the energy recovery system 11 in the gasification cell 10. This effect is not achieved in the known plants which accept as intake a material with variable characteristics. In fact, a plant which is flexible as regards intake, i.e. which can accept a material as intake with variable humidity, calorific power and characteristics, is at a serious disadvantage due to the fact that the variability of the intake material has spinoff repercussions on the synthesis gas produced by said known plant both in terms of energy level of the synthesis gas produced and in terms of the (chemical and physical) quality of the gas. The plant and method of the present invention, on the other hand, even though fed by a material 18 which is variable in its characteristics, avoid this variability having repercussions on the synthesis gas produced, because the plant and the method of the present invention are able to bring "tailored" stabilisation (meaning small interventions to introduce heat in small intervals/fractions of time) to the system in terms of energy associated with the output gas 11 thanks to the element 12 which, through the mixer 4 and the fan 2, stabilises the gasification cell 10.

In the event that a pure synthesis gas is required for fuel cells, the system will begin to pump only CO2 at around 200-300°C for a time of about 30 minutes to assess the output humidity level. These conditions are maintained until the humidity level drops. At this point the embers are kindled by injecting a mixture of air (70%) and CO2 (30%). Measurements are taken of the temperature of the syngas produced and the quantities of H2 and CO in the output from the cells. The quantity of air injected starts to be reduced until the quantity of H2 and CO is greatest. At this point equilibrium is reached and the system maintains this quantity of air and CO2 for the entire process of gasification. If a syngas rich in water, C0₂ and H2 is required for a water shift reactor, the pumped mixture must be made up of 50% air and 50% water until H2 begins to form, then the air content is increased until H2 is produced; at this point the quantity of air used is reduced and production of H2 and CO is maintained.

If it is desired to obtain complete combustion, pump CO. at 300°C, measure the humidity and when this falls below 60%, inject air and modulate the quantity of intake air until the syngas reaches the temperature of 400-450°C.

Claims

1. A plant for generating a synthesis gas from a solid organic material (18), comprising one or more gasification cells (10) with an intake for an organic material (18) and an outlet for extracting the synthesis gas produced,

characterised in that

each cell (10) comprises nozzles for introducing heated CO2 or a heated mixture of air and C02, the nozzles being connected to a pump or a mixer for air and CO2 (4) which regulates the quantity and the proportions of air and CO2 supplied to each gasification cell through said nozzles,

the plant comprising furthermore a heat conservation device (12) for storing the heat produced in the plant, connected to the pump for heating the intake CO2 or to an air/C02 mixer (4) for heating the intake air/C02 mixture.

2. The plant for generating a synthesis gas from a solid organic material according to claim 1, comprising furthermore an energy recovery system (11) for oxidising the synthesis gas and/or converting it into hydrogen, connected to the outlet of one or more said gasification cells (10) for receiving the synthesis gas thereof, and to the intake of the pump or of the mixer (4), through the heat conservation device (12), to supply an exhausted gas containing CO2 to one or more of said gasification cells (10), through the pump or the mixer (4).

3. The plant for generating a synthesis gas from a solid organic material according to one of claims 1 or 2, wherein a preheating device (17) is also provided for increasing the temperature of the intake air to the heat conservation device (12) or to the pump or mixer (4).

4. The plant for generating a synthesis gas from a solid organic material according to one of claims 1 to 3, wherein there is furthermore provided a filtering device (6), connected to the energy recovery system (11) through the heat conservation device (12), to purify the exhausted gases before they are reused in the cells (10) through the mixer (4) or emitted from the plant (6).

5. The plant for generating a synthesis gas from a solid organic material according to one of claims 1 to 5, furthermore comprising a condenser (13) for recovering the water contained in the exhausted gases coming from the filtering device (6).

6. The plant for generating a synthesis gas from a solid organic material according to one of claims 1 to 5, wherein one or more gasification cells (10) comprise temperature and pressure sensors connected to a continuous analyser of the quality of the synthesis gas produced, which analyser on the basis of the analysis adjusts the temperature, volume and composition of the air/CC>2 mixture delivered by the mixer (4) to said cells (10).

7. A process for generating a synthesis gas from a solid organic material, comprising the following steps:

- introducing an organic material (18) into a gasification cell (10);

- preheating CO2 or an air/CCh mixture to temperatures higher than 100°C and lower than

300°C,

- introducing preheated CO2 or a preheated air/C02 mixture through a plurality of nozzles to the inside of said gasification cell (10);

- partial oxidisation of the organic material (18) by means of the preheated CO2 or preheated air/CC>2 mixture inside the cell (10) with consequent production of a synthesis gas containing CO and H2, inert materials and latent heat;

- extraction of the synthesis gas from the cell (10) and introduction of said gas into an energy recovery system (11) for its energy to be exploited.

8. The process for generating a synthesis gas from a solid organic material according to claim 7, comprising furthermore a step of oxidising the synthesis gas produced and extracted from said cell (10); the oxidisation occurs in the energy recovery system (11) with generation of exhausted gas containing CO2 and perceptible heat.

9. The process for generating a synthesis gas from a solid organic material according to claim 8, wherein said oxidisation step is a combustion in the presence of an excess of oxygen.

10. The process for generating a synthesis gas from a solid organic material according to claim 7, comprising furthermore the step of converting the synthesis gas generated and extracted into H₂, exhausted gas and latent heat.

11. The process for generating a synthesis gas from a solid organic material according to one of claims 7-10, comprising furthermore the step of conserving part of the heat produced in the oxidisation phase (11) in a heat conservation system (12) and using the conserved heat for preheating the CO2 or the air/C02 mixture introduced into the gasification cell (10) and/or for preheating the air for the oxidisation in the energy recovery system (11).

12. The process for generating a synthesis gas from a solid organic material according to one of claims 7 to 11 wherein, in the step of preheating, the CO2 or the air/CC>2 mixture are preheated to less than 200°C to eliminate water present in the solid organic material (18).

13. The process for generating a synthesis gas from a solid organic material according to one of claims 8 to 12 wherein, in the step of preheating, the C0₂ or the air/CC>2 mixture are preheated to a temperature comprised from 200 °C to 300 °C to eliminate water present in the solid organic material (18).

14. The process for generating a synthesis gas from a solid organic material according to one of claims 8 to 12, comprising furthermore a step of filtering the exhausted gas and/or a step of condensing the water contained in the exhausted gas.