EP1069174A1

EP1069174A1 - Gas generator to produce methane gas and carbon oxide

Info

Publication number: EP1069174A1
Application number: EP00113640A
Authority: EP
Inventors: Gino Tomadini
Original assignee: Sas Gino Tomadini & C
Current assignee: Sas Gino Tomadini & C
Priority date: 1999-07-06
Filing date: 2000-06-28
Publication date: 2001-01-17
Also published as: IT1310872B1; ITUD990126A1; ITUD990126A0

Abstract

Gas generator to produce a combustible gas, particularly methane and carbon oxide, starting from solid fuels, said gas generator including a containing structure defining at least a conduit (18) through which the solid fuel descends and comprising an upper part (10a) and a lower part (10b) defining a hearth (30) where the combustion and gassification of said solid fuel occurs, the combustible gas produced being fed to at least one user machine, said containing structure being equipped with walls able to define chambers and interspaces communicating with said at least one conduit (18) through which the solid fuel descends, said chambers and interspaces being associated with at least an aperture (19) through which hot gases are introduced into the gas generator (10), said hot gases arriving from the exhausts of said user machines or from the cooling systems of the mechanical parts of said user machines to allow the at least partial energy recovery of said hot gases, means (28) being included to convey to said hearth (30) at least part of the volatile parts arriving from the distillation of the fuel and used as comburent in order to reduce the quantity of new comburent air taken in from outside.

Description

FIELD OF THE INVENTION

This invention concerns a gas generator to produce methane gas and carbon oxide.
The invention is used to produce methane gas and carbon oxide with a reduced content of free hydrogen and nitrogen starting from selected solid refuse, both domestic and/or industrial, or from low-cost solid products such as wood chips and wood discards, solid biomasses in general, peat, lignite, carbon fossils and other comparable products.

BACKGROUND OF THE INVENTION

The state of the art includes various types of gassification devices to produce, from various types of waste materials or from low-cost raw material, combustible gases which are used to feed user machines of various types, such as for example the motors of generator sets for the production of electric energy or heating boilers.
The technology of gassification, which has been used for a long time to produce combustible gases starting from coal, peat and lignite, has recently been the object of great interest and development, in order to be used on combustible raw materials which are more difficult to process, such as solid domestic refuse and industrial waste, both to reduce environmental pollution and also to tackle the lack of main sources of energy.
Gas generators such as are employed at present, however, - an example of which is described in EP-A-001.856 and EP-A-001.857 - are able to produce methane gas and carbon oxide characterised by a high content of free hydrogen and nitrogen.
This is because of problems linked directly to the gassification device, also called gas generator, and also because of problems encountered in the various stages of the gassification process.
Conventional gas generators, moreover, have a low yield and consequently to produce a sufficient volume of methane gas to feed a medium power user, they need greater quantities of fuel; nevertheless, the gas produced has a low calorific power per unit of measurement.
In order to increase this yield and decrease the flow of fuel to the gas generator, attempts have been made to recover the heat of the combustible gases emerging from the gas generator to pre-heat the comburent fluids. This solution, however, has also shown itself to be only partly efficacious and until now has not made possible to produce methane gas and comburent gas with a high calorific power.
The above-cited documents EP-A-001.856 and EP-A-001.857 describe plants to produce combustible gas and water gas starting from solid and liquid fuel. The presence of water gas is disadvantageous since it is not easily adaptable for subsequent use in Diesel motors and Otto motors.
Moreover, these documents provide to perform, inside the gas generator and before gassification, a process to dry the solid and liquid fuel introduced, using the working gases themselves, and they do not provide any recovery of the heat produced by the user machines, such as motors and boilers, to which the gas produced by the gas generator is destined.
Furthermore, these documents do not provide the possibility to produce charcoal while the gas generator is temporarily inactive.
The present Applicant has designed and embodied this invention to overcome the shortcomings of the state of the art and to obtain further advantages.

SUMMARY OF THE INVENTION

The invention is set forth and characterized in the main claim, while the dependent claims describe other characteristics of the invention.
The purpose of the invention is to provide a high performance gas generator able to produce methane gas (CH₄) and carbon oxide (CO) with a high calorific power, with a minimal production of water gas H₂, starting from solid fuel.
Another purpose of the invention is to provide a gas generator able to carry out a controlled recovery of heat, both inside and outside the gas generator itself, so as to be able to improve the gassification process in terms of yield and efficiency of the reactions, also exploiting the contribution of heat which is normally dispersed, such as that coming from the exhaust fumes of the user machines and from the cooling of their mechanical parts.
A further purpose is to optimize the yield of the chemical reactions inside the gas generator, by using sheets in the area of the hearth which are surface-treated with catalyzing material to encourage the formation of methane and to reduce to a minimum the presence of free hydrogen.
One characteristic of the invention is that it has a structure able to carry out energy recovery, both inside and outside the gas generator, so as to produce a considerable quantity of super-heated steam which is divided into hydrogen and oxygen; these are used both as a contribution of combustible gas for the production of methane, and also a comburent gas to replace part of the air taken into the gas generator from outside.
The gas generator according to the invention, therefore, is able to produce a combustible gas with an improved calorific power, yet still uses a lesser quality of solid fuel compared with conventional gas generators.
The gas generator according to the invention provides a maximum exploitation of energies which otherwise would be lost, such as the heat possessed by the gas produced, the cooling heat of the mechanical parts of the user machines, the heat of the exhaust gases of the machines and suchlike.
Experimental trials have shown that the energy recovery achieved by the gas generator according to the invention is in the order of 25-35%, which means that for every anhydrous kilogram of fuel it is possible to recover about 1000-1400 Kcal.
The heat recovered by the gas generator according to the invention, from cooling the mechanical parts of the user machines and from the heat of the exhaust gases from the user machines, is used, together or separately, to fulfil at least one of the following functions:

dehydration of the solid fuel;
dry distillation of the solid fuel;
evaporation and super-heating of the combustible fluids and of the comburents.

According to the invention the heat recovery is achieved, using conventional techniques, by means of recovery chambers provided for the purpose.
In the preferential embodiment of the invention there is at least a first recovery chamber in which at least part of the heat possessed by the exhaust gases of the user machine is recovered, and/or from the cooling of the mechanical parts of the user machine, and at least a second recovery chamber in which at least part of the heat possessed by the combustible gas produced is recovered.
In the gas generator according to the invention it is possible to distinguish substantially two parts: an upper part which is used to introduce the solid fuel and a lower part in which the combustion reaction occurs.
Before being introduced into the gas generator, the solid fuel is optionally subjected to a dehydration process, in order to reduce to a minimum the absorption of heat energy by the gas generator.
In this embodiment, the dehydration process is carried out by exploiting the residual heat of the exhaust gases of the user machines, for example a motor, and/or the heat of the cooling water of said machines.
Experimental tests have shown that this dehydration process allows to use even very wet fuel immediately, such as for example, freshly cut branches, with an energy recovery of 750 Kcal per every anhydrous kilo of fuel.
According to the invention, in the upper part of the gas generator, the fuel is subjected to a dry distillation reaction, that is to say, without combustion, of at least a percentage of the volatile parts of the fuel.
In this way, the solid fuel reaches the lower part of the gas generator already heated and without its volatile parts so that gassification occurs in a shorter time, without unburnt distillates, and with less energy required.
The distillation reaction, according to one characteristic of the invention, is achieved by means of heating the solid fuel obtained by making the exhaust fumes of the machines circulate in the afore-said first recovery chamber defined by suitable interspaces made in the upper part of the gas generator.
Due to the fact that dehydrated and pre-heated fuel is obtained previously, even in the upper part of the gas generator, it is possible to speed up the carbonization, or coking, of the solid fuel as it gradually descends along the gas generator; this facilitates a more regular process, in sequence, of the oxidizing combustion (in which oxygen and hydrogen free of water vapor are produced) and of the reducing combustion (in which carbon dioxide is transformed into carbon oxide).
According to a variant, the upper part of the gas generator is connected with a heat exchanger able to condense a defined quantity of the volatile parts to produce liquid fuel.
Any quantity of the volatile part which cannot be condensed is sent into the lower part of the gas generator to feed separately the oxidizing combustion and therefore the process of dividing the super-heated steam, which is fed parallel to the lower part, into oxygen and hydrogen.
According to one characteristic of the invention, the oxygen produced by the fission process reproduces itself and feeds the combustion without needing any other comburent to be added according to the quantity of gas required by the user machine.
The gas generator according to the invention is therefore able to regulate itself according to the variations in the requirement of combustible gas and in the production of exhaust gases by the user machine.
In fact, the variation in the requirement of combustible gas by the user machine, and the consequent variation in the production of exhaust gases, proportionally interfere both in the intake of air, and also in the production of distillates from the volatile parts of the solid fuel, and also, in an appropriate heat exchanger, in the production of steam with the residual heat.
The reduction in quantity of air taken in from the outside entails a drastic reduction in the supply of nitrogen.
This is particularly advantageous since nitrogen passively occupies a considerable volume in the fluids circulating in the hearth of the gas generator, it absorbs heat passively and considerably reduces the calorific power per unit of measurement of the gas produced.
The oxygen derived from the fission of the super-heated steam is usually in excess and, for this reason, the gas generator according to the invention has a conformation such that a part of the carbon produced by the solid fuel also reaches the last interspace in which the gas produced passes before it emerges from the gas generator to be delivered to the user machine.
In this way, consequent to a further formation of methane, the excess oxygen is combined with the carbon and produces carbon oxide instead of carbon dioxide.
According to the invention, gassification is encouraged by the fact that the fluids moving in the gas generator can follow ascending or descending paths and also horizontal paths, according to the variable resistances which they may meet among the fuel.
In one embodiment of the invention, the said paths of the fluids inside the gas generator are defined by separating walls able to define apertures of preferential passage.
According to the invention, the paths of the fluids in the upper part destined to dry distillation are encouraged by the presence of ventilation means, whereas in the lower zone relating to the formation of gas, they are caused by the forced intake towards the user machines.
According to the invention, at least the walls arranged in the zone of the gas generator affected by the reducing combustion are made of nickel alloys or are treated with nickel.
Nickel exercises a catalyzing action on the carbon and free hydrogen produced by the reducing combustion, encouraging the formation of methane gas and the production of a quantity of oxygen, with the advantage that less comburent air is required from outside the gas generator.
This allows to produce combustible gas with a low percentage of nitrogen with the advantages explained above.
According to one characteristic of the invention, the gas generator can carry out an alternative function to produce charcoal.
This alternative function is obtained by connecting, on the outside, the lower inlet of the gas generator with the gas outlet mouth and making the gases present between the mass of fuel re-circulate, after they have been cooled in a cooling device, inside the heap of coal which lies in the lower part of the gas generator.
When the gases emerging from the gas generator have a temperature which ensures the presence of spent coal (around 95+100°C), the latter may be extracted.
During this alternative function, the process of dry distillation and pre-heating of the solid fuels made in the upper part of the gas generator is carried out by an auxiliary burner.
The burner will continue to remove the distilled substances from the upper part, modulating their removal thermostatically according to the most suitable temperature, normally between 270°C and 320°C.

BRIEF DESCRIPTION OF THE DRAWING

These and other characteristics of the invention will become clear from the following description of a preferred form of embodiment, given as a non-restrictive example, with reference to the attached drawing which shows a schematic view of the gas generator according to the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

The gas generator 10 according to the invention includes a containing structure on a vertical axis, substantially cylindrical in shape and equipped with suitable insulating linings at least on the outer peripheral surface.
The gas generator 10 comprises two principal parts, an upper part 10a, in which a dry distillation, that is to say, without combustion, of the volatile parts of the solid fuel occurs, and a lower part 10b in which combustion and the formation of the gas takes place.
The upper part 10a is equipped with an inlet aperture 11 with which a loading device 12, of the gas-tight type, is coupled; the loading device 12 is used to load the solid fuel, which may include wood and biomasses in general, including solid domestic waste from differentiated rubbish collections.
In this case, the loading device 12 is of the Archimedean screw type and is governed by a level probe 13, which ensures there is a continuous presence of a defined quantity of solid fuel inside the gas generator 10.
According to a variant, the loading device 12 is of the type with a star valve.
The upper part 10a is equipped at the center with a vertical conduit 15 surrounded by coaxial containing walls which define, proceeding from the outside of the gas generator 10 towards the inside, an outer upper annular interspace 16, an intermediate upper annular interspace 17 and an inner upper annular interspace 18.
The solid fuel loaded into the upper part 10a is positioned in the inner annular interspace 18 and begins to heat up due to the effect of the hot gassy fluids which, at least in the initial cold start step, for some minutes, rise from the lower part 10b of the gas generator 10.
To be more exact, the hot gassy fluids are heated by the exhaust gases of the motors of the user machines, introduced into the gas generator 10 through an aperture 19 which sends them inside finned tubes, inner 53 and outer 56, arranged in a ring so as to delimit said interspaces 16 and 17.
The hot fumes are then made to circulate through the outer annular interspace 16 by at least a centrifugal fan 14 (advantageously there are two fans 14 arranged diametrically opposite) located in the high part of the gas generator 10 and forced, through the solid fuel, inside the central conduit 15 to be then put back into circulation together with fresh gassy fluids evaporated from the fuels during the dry distillation.
The passage of the gassy fluids from the annular interspace 17 both towards the annular interspace 18, and also towards the central conduit 15, is made possible by the fact that the conduit 15 is defined by a plurality of truncated-cone rings 22, superimposed and distanced from each other, and also by the fact that the annular interspaces 17 and 18 share a cylindrical wall 23 defined by a plurality of truncated-cone rings 23a superimposed and distanced from each other.
In the annular interspace 17 the gassy fluids are super-heated by the exhaust gases or fumes produced by the user machine, such as a boiler, a motor or suchlike, and introduced into a first recovery chamber 54 associated with said inlet aperture 19.
The first recovery chamber 54 is connected to a second, upper recovery chamber 55, by means of said finned tubes 53 and 56; after having yielded their heat to the fuel and contributed to its dry distillation in the upper part 10a of the gas generator 10, the exhaust gases are discharged by means of an outlet mouth 20.
As can be seen in the drawing, the outer interspace 16 is laterally delimited by the series of outer finned tubes 56 and by the series of inner finned tubes 53, and the intermediate interspace 17 is laterally delimited by the same series of inner finned tubes 53 and by the cylindrical wall 23 with the truncated-cone rings 23a.
In this way, therefore, the exhaust gases arriving from the user machines (motors, boilers, etc.) lap the walls of the cylindrical series of finned tubes 53 and 56 and heat the gassy fluids which pass inside the interspaces 16 and 17.
In the embodiment shown here, the upper part 10a is also equipped with an outlet 24 connected by means of a conduit 25 equipped with an intake aperture 25a to the inlet 26a of a heat exchanger 26.
In this way, a part of the distillates formed in the upper part 10a is forced by the fan or fans 14 and sent to the heat exchanger 26 which cools them and transforms them into condensed fuels which are collected in a container 27.
These condensed fuels can be used, for example, as liquid fuel to light the gas in the case of user machines consisting of Diesel motors.
The heat exchanger 26 is also equipped with an outlet 26b, through which that part of the distillates which is not condensed is discharged.
The outlet 26b is connected, by means of a conduit 28 equipped with a non-return valve 45, to the lower part 10b of the gas generator 10, to be more exact, in correspondence with the hearth 30, in order to re-introduce inside the gas generator 10 the non-condensed volatile parts of the biomasses.
There is also a conduit 29, equipped with a valve 46, to return said non-condensed volatile parts to a burner 31, with which the volatile parts are burnt and used, by passing inside the finned tubes 53 and 56, to contribute to the dry distillation of the woody biomasses in the upper part 10a of the gas generator 10.
The lower part 10b is equipped with an inlet conduit 32 through which comburent air is taken in, according to the requirements of the user machine, from the outside and sent to the hearth 30.
The lower part 10b is also equipped centrally with a conduit 21, axial to the conduit 15, through which the products of the first combustion occurring in the hearth 30 arrive from said hearth 30.
The hearth 30 is advantageously governed by a regulation thermostat 58b to maintain the temperature at values of around 700+800 °C, possibly discharging any excess steam generated through a discharge outlet.
The conduit 21, like the conduit 15, is defined by a plurality of truncated-cone rings 43 superimposed and distanced from each other.
Coaxial to and outside around the conduit 21 there are fins 40a, 43a, 44a which form vertical containing walls able to encourage the development of the catalyzing reaction of the nickel with which they are lined.
Proceeding from the outside of the lower part 10b of the gas generator 10 towards the inside, there is a first annular interspace 33, a second annular interspace 34, a third annular interspace 35, a fourth annular interspace 36, a fifth annular interspace 37, a sixth annular interspace 38 and a seventh annular interspace 39.
In the seventh annular interspace 39 the flames of the hearth 30 develop; they extend as far as the sixth annular interspace 38 where the solid fuel progressively descends.
The passage of the flames from the interspace 39 to the interspace 38 is made possible by the fact that the wall 40 shared by said interspaces 38 and 39 is defined by a plurality of truncated-cone rings 40a superimposed and distanced from each other.
The interspaces 37 and 38 are inter-communicating since the wall 44 which divides them consists of truncated-cone rings 44a superimposed and distanced from each other.
The solid fuel is progressively burnt in the interspace 38 and transformed into ash.
The ash is discharged from the gas generator 10 by means of an extraction device 41, in this case of the endless screw type, which is activated automatically on a thermostatic command 57 according to the temperature of the ashes.
In the gas generator 10 according to the invention, the gas produced rises through the interspace 37 and reaches an outlet mouth 48, provided with a valve 49, connected to the user machine.
In this case, moreover, the outlet mouth 48 is connected by means of a conduit 50 equipped with a valve 52 to the inlet of a cooling device 51, used exclusively during the alternative use of the gas generator 10 as a device to produce charcoal.
By means of these interspaces, both the distillates of the volatile parts of the fuels produced in the dry distillation zone 10a thanks to the heat of the exhaust gases generated by the motors, and also the steam produced with the residual heat of said fumes, reach the hearth 30. Moreover, the air which is taken in from the entrance 32 in order to feed the flames, the temperature of which is regulated thanks to the presence of the thermostat means, also reaches said hearth 30.
In this way, the steam produced finds the right conditions to start dividing into hydrogen and oxygen.
The oxygen produced, proceeding along the whole extension of the hearth 30, is able to reproduce itself and feed combustion without requiring any other comburent according to the quantity of gas required by the user machine.
This is because both the variation in the user machine's gas requirement and the corresponding variation in the production of exhaust gases or fumes by the user machine interfere - proportionally and directly - in the intake of air and the production of steam as in the production of distillates from the solid fuel.
According to one characteristic of the invention, the metal parts inside the gas generator 10, and in particular the truncated-cone rings 40a, 43a and 44a defining the walls 40, 43 and 44, and also the walls of the interspace 37, are treated and/or made with a catalyzing material, for example nickel, which acts as a catalyzer in the combination of the carbon with the oxygen, thus encouraging the production of methane gas.
According to another characteristic of the invention, the particular arrangement of the series of truncated-cone rings 44a of the wall 44 allows a part of the carbon in the interspace 38 to pass into the interspace 37.
In this way, the oxygen which is freed from the carbon oxide in the formation of methane combines again with the carbon in the interspace 37 to produce carbon oxide again, rather than carbon dioxide.
In the interspace 37 a possible presence of free oxygen still finds the catalyzing action of the nickel, but not the presence of carbon, so that the oxygen which is freed in the formation of the methane supplies carbon oxide and the free hydrogen transforms other carbon oxide into carbon dioxide.
The gas generator 10 as described heretofore functions as follows:
In the annular interspace 38 a reducing combustion begins which transforms the carbon dioxide into carbon oxide and, thanks to the reduction in temperature and the presence of nickel on the truncated-cone rings 43a and 44a, there is a high yield production of methane gas.
The methane gas likewise starts to form through the annular interspaces 37, 38 and 39.
Since the interspace 37 is also made of sheet treated with nickel, the formation of methane gas is further encouraged, reducing any possible excess of free hydrogen. Even if this might cause a further production of carbon dioxide, it is in any case advantageous since it gives greater guarantees of having, at outlet from the gas generator 10, a combustible gas with a high calorific power which is safer to use in high compression motors, particularly Diesel motors, in which the free hydrogen might cause unwanted self-ignition.
When the need to produce gas is over, or in other dead times, the gas generator 10 according to the invention can be used to produce charcoal, continuously and simply, without combustion in the lower part 10b. The production of charcoal can also be carried out for the first load of fuel in new gas generators, or of old generators which have to be re-loaded, so that it is possible to carry out extraordinary maintenance work inside.
During this step, the production of gas in the lower zone 10b is interrupted, but after the dry distillation of the fuel in the upper zone 10a it is possible to continue producing liquid condensates, collected in the container 27, by means of the heat exchanger 26.
In the upper zone 10a, a thermostat 58a can regulate the working temperature so as to obtain the total distillation of the volatile parts, for example for temperatures of 270+300 °C, or partial distillation, with temperatures of about 240+250 °C, so as to obtain condensates without tar or other impurities. The thermostat 58a can condition the activation of an appropriate valve (not shown here) which regulates the delivery of part of the burnt distillates to be used for the prior dehydration of the fuel; the other part of the distillates enters through the chambers 54 and 55, exchanging heat with the finned tubes 53 and 56 and then exiting through the aperture 20.
The woody biomasses, previously dehydrated, find themselves in an environment 15, 18 at a temperature that facilitates the evaporation of the volatile parts, which as they evaporate increase in volume and exit through the aperture 25a to be sent either to the heat exchanger 26 or again inside the gas generator 10.
From the upper zone 10a, the woody biomasses descend along the conduit 15, freeing themselves from the volatile parts and transforming into carbon, since they are subjected to a re-circling of the volatile parts generated by the fans 14, which make the volatile parts pass between the finned tubes 53 and 56, causing them to be super-heated thanks to the action of the burner 31.
The dehydrated biomasses arrive in the lower part 10b of the gas generator 10, in which they are simply cooled by the re-circling of gassy fluids.
In this case, we close the valve 45 of the conduit 28 which feeds the non-condensed distillates to the hearth 30 and we open the valve 46 of the conduit 29 which feeds the same non-condensed distillates to the burner 31.
At the same time we close the valve 47 of the inlet conduit 32 and the valve 49 downstream of the outlet mouth 48 and we open the valve 52 of the conduit 50.
In this way, the gases produced are made to recirculate in the gas generator 10, by means of the fan 59, after they have been cooled in the cooling device 51, inside the heap of coal which lies in the lower part 10b.
During the production of carbon, the dry distillation and pre-heating process of the solid fuels in the upper part 10a of the gas generator 10 is performed by the burner 31 which continues to take the distilled substances from the upper part 10a, modulating the removal thereof thermostatically according to the most suitable temperature, normally between 270°C and 320°C.
It is obvious that modifications and additions may be made to the invention, but these shall remain within the field and scope thereof.
It is also obvious that, although this invention has been described with reference to a specific example, a skilled person in the art shall certainly be able to achieve many other equivalent forms of gas generator, which shall all remain within the field and scope of this invention.

Claims

Gas generator to produce a combustible gas, particularly methane and carbon oxide, starting from solid fuels consisting of solid domestic and/or industrial waste, wood chip and/or discards, biomasses in general, coals, peat, lignite, said gas generator including a containing structure defining at least a conduit (18) through which the solid fuel descends and comprising an upper part (10a) cooperating with means (12) to load the solid fuel and able to perform the dry distillation of the fuel to separate the volatile parts, and a lower part (10b) defining a hearth (30) where first the oxidizing combustion, then the reducing combustion of said solid fuel occurs and then its gassification, the combustible gas produced being fed to at least one user machine such as a motor or a boiler, the gas generator being characterized in that said containing structure is equipped with walls able to define chambers and interspaces communicating with said at least one conduit (18) through which the solid fuel descends, said chambers and interspaces being associated with at least an aperture (19) through which hot gases are introduced into the gas generator (10), said hot gases arriving from the exhausts of said user machines or from the cooling systems of the mechanical parts of said user machines to allow the at least partial energy recovery of said hot gases, means (28) being included to convey to said hearth (30) at least part of said volatile parts arriving from the distillation of the fuel and used as comburent in order to reduce the quantity of new comburent air taken in from outside.
Gas generator as in Claim 1, characterized in that said upper part (10a) is suitable for the performance of a dry distillation reaction of said solid fuel and has at least a recovery chamber (54) in which at least part of the hot exhaust gases produced by said user machine are made to circulate, said recovery chamber (54) cooperating with at least an interspace (16) in which the gassy fluids arriving from said lower part (10b) are made to pass, said gassy fluids being able to supply a heat contribution for the dry distillation of the volatile parts of said solid fuel.
Gas generator as in Claim 2, characterized in that said recovery chamber (54) is associated with a first series of inner finned tubes (53) and with a second series of outer finned tubes (56) inside which said exhaust gases are made to circulate, said series of finned tubes (53, 56) being able to define said interspace (16) so that the gases circulating therein lap the walls of said finned tubes (53, 56) wherein at least part of the exhaust gases produced by said user machine is made to circulate, said exhaust gases being then discharged through at least an aperture (20).
Gas generator as in Claim 2, characterized in that ventilation and/or forced air-intake means (14) are provided to make said gassy fluids circulate in said interspace (16) and through the solid fuel to achieve said dry distillation of the volatile parts of the solid fuel.
Gas generator as in Claim 1, characterized in that in said lower part (10b) there is provided at least a second recovery chamber in which, through suction, the combustible gas produced by the gas generator (10) itself is made to circulate, said second recovery chamber cooperating with an interspace (34) able to be used for the recovery of the heat of said combustible gas to super-heat the steam produced through the residual heat of the exhaust gases of said user machines, said super-heated steam being sent to the hearth (30) where it is divided into hydrogen and oxygen.
Gas generator as in Claim 5, characterized in that said second recovery chamber comprises a first annular interspace for the partial feed of air to the hearth (30), a second annular interspace to feed the hearth (30) with super-heated steam and means to feed the hearth (30) with the distilled volatile parts arriving from the upper part (10a).
Gas generator as in Claim 1, characterized in that said lower part (10b) is provided with at least an interspace (37) through which the combustible gas produced is discharged, and at least an interspace (38) in which the carbon produced accumulates, between said interspace (37) and said hearth (30) there being provided a wall (44) equipped with through apertures which allow the passage of part of the carbon from said interspace (38) to said interspace (37) so that the oxygen which is freed from the carbon oxide in the formation of methane, by re-combining with said carbon, produces carbon oxide.
Gas generator as in Claim 1, characterized in that, at least in the lower part (10b), said walls are made of nickel or are lined with nickel.
Gas generator as in Claim 8, characterized in that at least part of said walls comprises truncated-cone rings, superimposed and distanced from each other.
Gas generator as in Claim 8, characterized in that at least part of said walls comprises fins forming vertical walls substantially arranged in a circle and able to facilitate the development of catalyzing reactions of the nickel with which they are partly lined.
Gas generator as in Claim 1, characterized in that it comprises at least a heat exchanger (26) equipped with an inlet (26a) connected with said upper part (10a) to condense part of the distillates produced in the latter to produce liquid fuel.
Gas generator as in Claim 11, characterized in that said heat exchanger (26) has at least an outlet (26b) connected to the hearth (30) to recover any possible part of the distillates which are not condensed.
Gas generator as in Claim 1, characterized in that it comprises an auxiliary circuit consisting of conduits (50, 52, 29) able to return at least part of the combustible gas in the lower part (10b) back into circulation in the gas generator (10) and at least part of the non-condensed volatile parts in order to allow the production of charcoal.
Gas generator as in Claim 13, characterized in that said auxiliary circuit of conduits (50, 52, 29) cooperates with at least a cooling device (51) able to lower the temperature of the combustible gas before putting it into circulation in the gas generator (10), in order to cool said carbon to a temperature of around 95+100 °C.
Gas generator as in Claim 12, characterized in that it comprises at least a burner (31) associated with the conduit (29) and able to burn in said upper part (10a) at least part of the non-condensed distillates produced.