ITMI20102156A1 - MACRO-PARTS FOR THE PRODUCTION AND TREATMENT OF GAS - Google Patents

Description

[0001] The present invention relates to a macro-apparatus for the production, cooling and cleaning of the gas produced by a gasifier. The gasifier is suitable for producing combustible gas from biomass of different origins or from mineral coal. The cleaning apparatus is suitable for purifying the combustible gas produced by the gasifier.

[0002] Plants for the gasification of biomasses have been known for some time, ie plants suitable for producing combustible gas starting from biomass. The most relevant fraction of biomass (80-98%) is made up of carbon (C), hydrogen (H) and oxygen (O) organized in different types of molecules. The remaining fraction of biomass (2-20%) is made up of other molecules and other inorganic elements including above all silicon (Si), potassium (K), calcium (Ca), magnesium (Mg).

[0003] In a known way, the main reactions that occur during gasification are:

[0004] C O2â † ’CO2 (Combustion)

[0005] C 1⁄2 O2â † ’CO (Partial oxidation)

[0006] C H2O (g) â † ’CO H2 (Reforming of coal)

[0007] C CO2â † ’2CO (Boudouard reaction)

[0008] C 2H2â † ’CH4 (Methanation)

[0009] CO H2O (g) â † ’CO2 + H2 (Water / Gas Shift Reaction).

[0010] From these reactions, in the presence of air, a gas is obtained (called producer gas) composed of a mixture composed on a dry basis of approximately 50% N2, 20% CO, 15% H2, 10% CO2 and 5% CH4. If the reactions take place in the absence of air, the final mixture does not contain N2 and takes the name of â € œsynthesis gasâ € or Syngas.

[0011] Various types of gasification plants are known, which differ on the basis of the structure of the reactor, the path that the gas travels through inside the reactor, the type of filtration apparatus used, etc.

[0012] Gasification plants of the known type are not, however, free from defects.

[0013] Today's gasification plants can be grouped into two broad categories. The plants of the first category are largely made for experimental purposes, are characterized by large dimensions (typically greater than 1 MegaWatt power) and use sophisticated technologies. These dimensions and the fact that they are generally built in unique specimens make it impossible for them to be marketed on a large scale.

[0014] The plants of the second category are characterized by small dimensions, use rudimentary technologies and are especially suitable for rural realities of developing countries. The technological backwardness of these plants makes it impossible for them to be used on a large scale in the western energy market.

[0015] Extremely compact gasification plants were built in the 1940s. They were generally mounted on motor vehicles to remedy the absence of petroleum products. These systems made it possible to feed the internal combustion engines with wood or charcoal. They were characterized by small dimensions, but had a poor efficiency, produced a gas of unacceptable quality by today's standards and generally involved serious problems of environmental pollution.

[0016] Today's internal combustion engines require very high quality gas. In general there are also further, rather stringent, limitations on the maximum temperature of the supply gas, on its relative humidity and on the dew point of the tars present in it.

[0017] The attainment of such gas qualities, and above all the lowering of the temperature of the gas destined to feed an engine, implies the formation of condensation water. This water is particularly polluted with organic substances (phenols, ammonia, benzenes, etc.) and therefore poses considerable problems relating to treatment and elimination.

[0018] The object of the present invention is therefore to make available an apparatus for cooling and cleaning the gas produced by a gasifier, suitable for at least partially overcoming the drawbacks indicated with reference to the prior art.

[0019] In particular, the aim of the present invention is to make available an apparatus for cooling and cleaning the gas which has limited overall dimensions and which is of economical construction and easily replicable on an industrial scale.

[0020] Furthermore, the aim of the invention is to make available an apparatus and a method which are capable of producing a gas of high quality and at a sufficiently low temperature to be used also in today's internal combustion engines.

[0021] Another task of the invention is that of solving the problem of the disposal of polluted waters that are formed during the cooling of the gas and tars produced.

[0022] This object and these tasks are achieved by means of a macro apparatus according to claim 1, by means of a plant according to claim 11 and by means of a method according to claim 14.

[0023] In order to better understand the invention and appreciate its advantages, some exemplary and non-limiting embodiments thereof are described below, with reference to the attached drawings, in which:

[0024] figure 1 is a schematic view of a plant for the production of energy from biomass comprising the macro-apparatus for the production and treatment of gas and disposal of polluted water according to the invention;

[0025] figure 2 is a schematic view of another plant according to the invention;

[0026] figure 3 is a schematic view of a further plant according to the invention;

[0027] figure 4 is a diagram which represents the behavior of some types of tars as the temperature varies;

[0028] figure 5 represents a perspective view of the assembly consisting of the evaporative cooler and the evaporator forming part of an embodiment of the macro apparatus according to the invention;

[0029] figure 6 represents a plan view of the assembly of figure 5;

[0030] figure 7 represents a side view of the assembly of figure 5;

[0031] figure 8 represents a sectional view along the line VIII-VIII of figure 6;

[0032] figure 9 represents a sectional view of an embodiment of the gasifier forming part of the macro-apparatus according to the invention, in closed configuration;

[0033] figure 10 represents a sectional view of the gasifier of figure 9 in open configuration;

[0034] figure 11 represents an enlarged view of the detail indicated with XI in figure 9;

[0035] figure 12 represents an enlarged view of the detail indicated by XII in figure 10;

[0036] figure 13 represents the scheme of an oxidizing catalyst; And

[0037] figure 14 represents the behavior of the oxidizing catalyst as the gas temperature varies.

[0038] In the remainder of the description, reference will often be made to the concepts of "high", "upper" and the like and, respectively, to the concepts of "low", "lower" and the like. These concepts are to be understood unambiguously with reference to the apparatus correctly assembled in order of operation, therefore subject to the force of gravity.

[0039] In the description of the gas route, reference will also be made to the concepts of â € œupstreamâ € and â € œdownstreamâ €. With â € œupstreamâ € we mean a position along the path relatively close to the mouth of the reactor through which the biomass and the air necessary for the reactions are fed. Conversely, 'downstream' means a location along the path relatively far from the reactor mouth.

[0040] In the attached figures, the reference 100 generally indicates a plant for the production of energy from fuel, in particular from biomass BM. The plant 100 first of all comprises a macro apparatus 10 for the production and treatment of gas G. In accordance with the embodiment illustrated in Figure 1, the plant 100 then comprises, downstream of the macro apparatus 10, other components which will be described below. These further components preferably include an electrostatic filter 40 and a unit 80 for the use of gas G.

[0041] The macro apparatus 10 according to the invention comprises:

[0042] - a gasifier 12 suitable for receiving a flow of oxygenated gas and fuel BM and for emitting a flow of gas G;

[0043] - a duct suitable for conveying the flow of gas G from the gasifier 12 to a dedusting unit 14;

[0044] - a dedusting unit 14;

[0045] - a conduit suitable for conveying the flow of gas G from the dedusting unit 14 to an evaporative cooler 20;

[0046] - an evaporative cooler 20 suitable for treating the gas flow G, comprising:

- nebulization means 21 of an aqueous mixture MA in the gas stream G,

- a basin 22 suitable for decanting and maintaining a reserve of aqueous mixture MA in the condensed state in the evaporative cooler 20,

- a recirculation circuit 23 suitable for removing the aqueous mixture MA from the basin 22 and feeding it to the nebulization means 21 of the evaporative cooler 20; And

- a purge pipe 24 suitable for removing the condensed pollutants from the bottom of the basin 22 and conveying them towards the gasifier 12;

[0047] - a conduit suitable for conveying the flow of gas G from the evaporative cooler 20 to a scrubber 30;

[0048] - a scrubber 30 suitable for treating the gas flow G, comprising:

- nebulization means 31 of an aqueous mixture MA in the gas stream G,

- a basin 32 suitable for decanting and maintaining a reserve of aqueous mixture MA in the condensed state in the scrubber 30,

- a recirculation circuit 33 suitable for removing part of the aqueous mixture MA from the basin 32 and feeding it to the nebulization means 31,

- a purge pipe 34 suitable for removing the condensed pollutants from the bottom of the basin 32 and conveying them to the gasifier 12, and

- a heat exchanger 35 located along the recirculation circuit 33 of the scrubber 30, and - a compensation pipe 37 suitable for removing part of the aqueous mixture MA from the basin 32 and feeding it to the basin 22 of the evaporative cooler 20;

- a conduit suitable for conveying the flow of gas G from the scrubber 30 towards the outside of the macro-apparatus 10.

[0049] Finally, the macro apparatus 10 according to the invention comprises a purifier 60 suitable for receiving a flow of oxygenated gas A and an aqueous mixture MA and for emitting a flow of purified wet oxygenated gas AU, the purifier 60 comprising in turn :

- a duct 61 for the adduction of a flow of oxygenated gas A;

- an evaporator 63 having nebulization means 630 of an aqueous mixture MA in the oxygenated gas stream A;

- a tube 65 suitable for withdrawing a quantity of aqueous mixture MA from the basin 22 of the evaporative cooler 20 and feeding the aqueous mixture MA to the nebulization means 630 of the evaporator 63;

- a conduit 62â € ™ suitable for conveying the humid oxygenated gas AU from the evaporator 63 to heating means 67;

- means 67 for heating the humid oxygenated gas AU suitable for raising its temperature beyond 200 ° C;

- a conduit 62â € suitable for conveying the moist oxygenated gas AU to an oxidizing catalyst 68;

- an oxidizing catalyst 68 suitable for promoting the oxidation of organic pollutants suspended in the humid oxygenated gas AU; and - a conduit suitable for introducing the purified moist oxygenated gas AU downstream of the oxidizing catalyst 68 into the atmosphere.

[0050] The macro apparatus 10 described above can preferably comprise one or more of the following auxiliary components:

- a tube 27 suitable for introducing water from the outside into the macro-apparatus 10, for example feeding it to the nebulization means 21 or to the basin 22 of the evaporative cooler 20;

- a discharge pipe 36 suitable for removing the excess aqueous mixture MA from the basin 32 of the scrubber 30 and conveying it towards the outside; and / or - a recirculation circuit 64 suitable for removing any condensed aqueous mixture MA from the bottom of the evaporator 63 and conveying it to the basin 22 of the evaporative cooler 20.

[0051] The patent application WO 2008/096387, in the name of the same applicant, describes a gasification plant which, in the general configuration and in the aspects known per se, is similar to the plant 100 considered here. Reference should be made to this document for the aspects not dealt with in depth in the following description.

[0052] The gasifier 12 is suitable, in a per se known way, for treating different fuels such as biomass of various kinds, vegetable coal or mineral coal.

[0053] The gasifier 12 is preferably of the downdraft (or downdraught) type, known per se. In this type of gasifier, the BM fuel is introduced into the reactor from above, the gasification reactions take place in the lower part of the reactor and the gas produced is removed from the bottom of the reactor. This type of gasifier therefore differs from others, called updraft, in which the gas produced is removed from the top of the reactor.

The downdraft gasifier offers some notable advantages in biomass gasification. First of all, it produces a gas with a limited tar content, thus facilitating the subsequent cleaning phase. Furthermore, the downdraft gasifier, as a by-product of biomass gasification, produces a carbonaceous residue called carbonella (or charcoal) whose demand is increasing more and more. In fact, this charcoal is used to improve the fertility of the land (in this sense it is called biochar) and above all to fix the carbon present in the biomass in an extremely stable form. This carbon derives from carbon dioxide (CO2) removed from the atmosphere by biomass.

[0055] The gasifier 12 is preferably of the opentop or opencore downdraft type, known per se. In this type of gasifier, the oxygen, necessary for the combustion and partial oxidation reactions of carbon, is generally supplied by the air sucked in from the environment at atmospheric pressure through the upper mouth of the reactor. This type of gasifier therefore differs from others in which the oxygen necessary for the combustion / gasification reactions is supplied at a pressure higher than atmospheric pressure by a special plant or is injected into defined points directly inside the reactor. This solution is adopted for example in the gasifier known as the Imbert type.

[0056] In accordance with other possible embodiments, aimed at obtaining a greater percentage of oxygen O2 in the air sucked in by the gasifier 12, an oxygen supply system is provided for oxygen O2 under pressure, for example a cylinder or other oxygen tank in pressure. Such embodiments potentially allow to increase at will the percentage of oxygen O2 in the flow of sucked air. The composition of the sucked air can therefore vary between that of the ambient air (therefore a mixture containing about 20% oxygen) and that of pure oxygen (100% O2), the intermediate compositions being generically definable as oxygenated air. The increase in the percentage of oxygen can be useful in some particular cases of operation of the gasifier 12 for a more effective gasification of some particular fuels, for example sludge. The expression â € œoxygenated gasâ € used below generically refers to ambient air, oxygenated air or pure oxygen.

[0057] Finally, this type of gasifiers generally have cylindrical reactors, with constant section, without grooves or restrictions (throatless) which allow the use of BM biomass with low density.

[0058] The opencore gasifier has the advantage of being very simple and economical in its construction and management. Furthermore, the opencore gasifier allows biomasses to be gasified with low melting ash and very low density such as herbaceous biomass.

[0059] Figures 9 to 12 illustrate a particular embodiment of the gasifier 12 included in the macro apparatus 10 according to the invention.

[0060] In accordance with this embodiment, the gasifier 12 comprises means 120 for lifting the outer shell 121.

[0061] Figure 9 shows the gasifier 12 in the closed configuration. This configuration is the one maintained during the operation of the gasifier 12 but also in the normal non-operational phases. In this configuration, the external jacket 121 therefore defines a separation between the interior of the gasifier 12 and the external environment.

[0062] Figure 10 shows the same gasifier as Figure 9, but in its open configuration. This configuration is the one maintained during the maintenance phases of the gasifier, typically during the removal of foreign bodies 123. In this configuration, the outer casing 121 is raised and therefore defines an opening that connects the inside the gasifier 12 with the external environment.

[0063] It is quite common for foreign bodies 123 to be inadvertently introduced into the gasifier 12 at the same time as BM biomass is introduced. Foreign bodies 123 are typically bodies which due to their physico-chemical nature cannot participate in the reactions of gasification, typically stones or metal scrap. For this reason the foreign bodies 123 pass through all the zones of the gasifier 12 maintaining their structure and their mass almost unchanged, and finally settle on the bottom grid 122 which supports the biomass BM.

[0064] The accumulation of foreign bodies 123 on the bottom grid 122 can in the long run cause an unacceptable alteration of the process conditions, for example due to the constriction that they cause in the passage section of the gas G leaving the gasifier. In view of this, it is therefore necessary to periodically remove the foreign bodies 123 from the bottom grille 122.

[0065] Gasifiers of the known type require in this regard periodic interruptions in operation which allow the external casing of the reactor to be disassembled in order to allow access to the grid. This solution, although widely adopted, requires long technical downtime of the plant, times necessary to let the reactor cool down, to allow the operators to disassemble the reactor, remove foreign bodies 123 and put the reactor back into its configuration. ™ exercise. As the expert can easily understand these long stops negatively affect the productivity of the plant.

[0066] The embodiment of the gasifier 12 illustrated in Figures 9 to 12, on the other hand, allows the removal of the foreign bodies 123 to be completed in an extremely simple way. The lifting means 120 in fact allow the outer shell 121 of the reactor to be lifted in such a way as to allow direct access to the bottom grate 122. The removal of foreign bodies 123 can thus be carried out in a simple and rapid manner, without the need for need for a long stop for the system.

[0067] Figures 11 and 12 show the detail of the lifting means 120, respectively in the closed operating configuration and in the open maintenance one. In the specific embodiment shown in the figures, the lifting means 120 comprise a plurality of jacks arranged on the outer perimeter of the shell 121.

[0068] As already highlighted above, the chemical reactions that take place inside the downdraft reactors are unable to obtain a complete gasification of the biomass BM, and therefore release, in addition to the flow of gas G produced, solid residues in the form of dust charcoal. As described above, this charcoal powder lends itself to interesting uses from an agricultural and / or environmental point of view. As an alternative to these uses, it is also possible to further exploit the charcoal for energy purposes.

[0069] In accordance with some embodiments, for example the one shown in Figure 3, the macro-apparatus 10 also comprises an auxiliary gasifier 125 suitable for the gasification of the charcoal dust C which escapes from the first gasifier 12 as a residue of the biomass gasification reactions BM.

[0070] The auxiliary gasifier 125 is preferably of the type suitable for the gasification of dusty masses, typically it can assume an updraft and opencore type structure.

[0071] In accordance with this embodiment of the macro apparatus 10, the auxiliary gasifier 125 comprises a duct 69 suitable for feeding the moist oxygenated gas AU that comes from the evaporator 63 of the purifier 60. The advantages deriving from the use of gas wet oxygenate AU inside the auxiliary gasifier 125 will be described later. Another conduit 126 is suitable for bringing the gases produced by the gasification of charcoal C from the auxiliary gasifier 125 to the main gasifier 12.

[0072] In accordance with some embodiments, not shown in the attached figures, the macro apparatus 10 also comprises means for the evacuation of the dust and / or ashes that are collected respectively in the gasifier 12, in the dedusting unit 14 and (if present) in the auxiliary gasifier 125.

[0073] These means advantageously comprise one or more augers suitable for removing dust and / or ashes and for transporting them to suitable collection or storage containers. Furthermore, the means for the evacuation of dust and / or ashes preferably include valves suitable for allowing dust and / or ashes to escape from the macro apparatus 10, without at the same time allowing the entry of air from the environment. outside the inside of the macro apparatus 10. These valves are particularly advantageous in the case in which the inside of the system 100 is kept under vacuum to move the gas G along the system itself. In this case, the absence of the valve on the outlet of the powders from the gasifier 12 would cause the entry of air and the consequent explosion of the gasifier 12 itself.

[0074] The gas G leaving the gasifier 12 has a temperature of about 400 ° C-800 ° C and carries a significant quantity of pollutants. The main pollutants are charcoal dust, ash and tars in the vapor phase or nebulized. Gas G, in order to be effectively used in a utilization unit 80, must be cleaned as much as possible of pollutants and must be cooled down to a temperature below 70C °, preferably below 60 ° C.

[0075] The unit 14 for the dedusting of gas G can, for example, comprise a cyclone (see for example the diagram in Figure 1) or a ceramic filter for high temperatures (not shown). Both of these solutions are not described in detail here because they are well known to the skilled person.

[0076] The evaporative cooler 20 (also called â € œevaporative coolerâ €) is suitable for obtaining a first cooling of gas G by evaporating an aqueous-based mixture MA until the gas G itself is saturated. In other words, the nebulization means 21, located inside the evaporative cooler 20, nebulize the aqueous mixture MA in the gas flow G. Part of this mixture MA evaporates, absorbing heat and therefore lowering the temperature of the gas flow G. This mechanism works efficiently until the vapors produced by the evaporation of the aqueous mixture MA saturate the gas G.

[0077] In the embodiments described below it is considered that the aqueous mixture MA comprises mainly water, polar tars (therefore soluble in water) and apolar tars (insoluble).

[0078] In other possible embodiments of the apparatus 10 the aqueous mixture MA could also comprise other additives suitable for solving specific contingent problems. These additives can be in solution, emulsion, suspension, or in any case mixed in water. For example, one of these additives may include particles of calcium hydroxide Ca (OH) 2 which, in suspension in water, form the so-called milk of lime. The use of milk of lime allows to neutralize any acid compounds present in the G gas. Another useful additive could in some cases be an antifoam agent.

[0079] In general, the aqueous mixture MA also includes traces of the other elements present in the gas G, such as carbon (C) in the form of charcoal and other inorganic elements in the form of ash such as silicon (Si), potassium (K), calcium (Ca), magnesium (Mg).

[0080] As already described above, the nebulization means 21 can advantageously comprise a connection 27 to the water mains or to other water reserve external to the system 100. It is thus possible to compensate for any water losses that occur in the cooler evaporative 20 or downstream thereof.

[0081] The evaporative cooler 20 also comprises a basin 22 in which a reserve of aqueous mixture MA is collected in the condensed state. The presence of the MA mixture in the liquid phase guarantees the effective saturation of the gas G in transit in the evaporative cooler 20, but above all it is necessary in order to obtain an effective washing of the gas G.

[0082] In the evaporative cooler 20, by means of the nebulization means 21, a much greater quantity of aqueous mixture MA is injected than that necessary to saturate the gas G. The quantity of aqueous mixture MA in excess, which therefore passes through the gas G in the liquid state, it obtains the removal of the condensed tars in suspension and of the fine powders which are not retained by the dedusting means 14. Obviously the aqueous mixture MA which is nebulized in excess of the saturation of the gas G, and which therefore remains in the liquid state , accumulates in basin 22.

[0083] The temperature of the gas G leaving the evaporative cooler 20 depends on the concentration of tars in the aqueous mixture MA, and on the type of tars themselves. At the end of an initial transient, the operating parameters of the evaporative cooler 20 settle down. If the evaporative cooler 20 is well sized, the saturated gas G and the condensed aqueous mixture MA have practically the same temperature. In this steady state condition, the cooling of the gas G occurs almost exclusively by absorption of the latent heat of evaporation by the aqueous mixture MA.

[0084] If pure water were used instead of the aqueous mixture MA, the equilibrium temperature inside the evaporative cooler 20 would settle around about 80 ° C. As the concentration of tars in the aqueous mixture MA increases, the ebullioscopic constant of the aqueous mixture MA itself also increases and therefore the equilibrium temperature rises.

[0085] The basin 22 of the evaporative cooler 20 is preferably made in such a way that an efficient sedimentation of the non-soluble tars in the aqueous mixture MA, of the charcoal dust and of the ashes coming from the gasifier 12 and not knocked down by the unit can be achieved 14, so that the concentration of the same in suspension in the aqueous mixture MA is as low as possible. These decanted tars and powders are then purged through the tube 24 to the gasifier 12 to be gasified and then destroyed.

[0086] At the concentrations of tar in the mixture which are considered advantageous for the operation of the evaporative cooler 20, the equilibrium temperature is preferably between 75 ° C and 90 ° C. This temperature is reached by favoring the sedimentation of a certain quantity of insoluble tars in the aqueous mixture in the basin 22. In this case the aqueous mixture MA has a particularly low viscosity which favors the use of economical centrifugal pumps. If the concentration of water in the MA mixture were to decrease, the evaporative cooling effect would progressively decrease, causing the temperature of the mixture itself to rise.

[0087] The use of evaporative cooling of gas G, which occurs at temperatures generally above 80 ° C, eliminates the need to cool the aqueous mixture MA by means of a heat exchanger located along the recirculation circuit 23 which supplies the nebulization means 21.

[0088] A heat exchanger placed along this recirculation circuit 23 would in fact be easily dirty and would therefore require frequent maintenance. The aqueous mixture MA in fact contains a large quantity of tars which make any heat exchange in a traditional type heat exchanger, for example shell and tube, difficult and expensive.

[0089] Furthermore, in order to obtain an adequate heat exchange, the surfaces of the heat exchanger should be significantly colder than the aqueous mixture MA that touches them. This would cause a localized increase in the viscosity of the aqueous mixture MA, with consequent problems both of a thermal type (worsening of heat transmission) and of a hydraulic type (clogging of the exchanger).

[0090] Figure 4 shows a diagram representing the behavior of the different tar fractions as a function of temperature. As can be seen, the different tar fractions have distinctly different behaviors at the same temperature.

[0091] In particular, at a plausible equilibrium temperature for the operation of the evaporative cooler 20, for example at a temperature of 85 ° C, different phases coexist. There are the lighter (aromatic) tars completely in the vapor phase, other tars (light polyaromatic and heterocyclic) partially in the vapor phase and partially in the condensed phase, and finally there are the heavier tars (heavy polyaromatic) completely in the condensed phase.

[0092] The condensed tars collect in the basin 22 together with the water, forming the aqueous mixture MA. The aqueous mixture MA includes both polar tars that pass into solution, as well as non-polar tars which generally have a density higher than water and which, if left to settle properly, stratify on the bottom of the basin 22.

[0093] The purge pipe 24 is suitable for removing a large part of the sedimented tars which collect there from the bottom of the basin 22. They must be removed from the basin 22 to maintain the correct quantity of mixture MA inside the evaporative cooler 20. Furthermore, the condensed tars present in the mixture MA can be usefully returned to the mouth of the gasifier 12 and subjected again to the oxidation and gasification processes . Tars are in fact colloidal systems comprising a high quantity of organic substance, especially heterocyclic and polycyclic aromatic hydrocarbons. It is therefore possible to extract a further quantity of G gas from the tars.

[0094] In the attached figures 1 to 3, the evaporative cooler 20 is represented as a conduit crossed by the gas flow G in a substantially horizontal direction. Inside the duct, the aqueous mixture MA is nebulized in the direction of the gas flow. In a low point of the duct the basin 22 is obtained, in which the condensed MA mixture collects by gravity.

[0095] In accordance with what is illustrated in the attached Figures 5 to 8, the evaporative cooler 20 can assume the structure of a duct through which the gas flow G flows in a substantially vertical direction. Inside this duct the aqueous mixture MA is nebulized, for example in co-current with respect to the gas flow G. At the bottom of the duct there is the basin 22, in which the condensed mixture MA collects by gravity, similarly to as described above.

[0096] The evaporative cooler 20 preferably comprises means 25 for crushing the encrustations which form inside it during the treatment of the gas flow G.

[0097] The crushing means 25 are preferably comprised between the upper zone in which the nebulization of the aqueous mixture MA takes place and the basin 22 in which the aqueous mixture MA is collected in the condensed state.

[0098] The crushing means 25 preferably comprise a series of knives 250 movable with respect to a grid 251. In accordance with the embodiment shown in figure 8, the knives 250 are mounted radially on a rotatable shaft arranged in proximity to the plane of the grid 251. In accordance with this embodiment, following the rotation of the shaft, the knives 250 periodically cross the plane of the grid 251.

[0099] It is described below how this solution allows to obtain some indisputable advantages. First of all it should be remembered here that, in this area of plant 100, the flow of gas G carries with it a large amount of pollutants, since it has been treated only by the dedusting unit 14. Most of the pollutants (be they in the form of vapors, aerosols or fine powders) are preferably removed further downstream, typically in the electrostatic precipitator 40 (described in detail below).

[00100] Inside the evaporative cooler 20 the gas flow G undergoes a drastic decrease in temperature: from about 400-800 ° C to about 75-100 ° C, preferably about 80 ° C. Due to this cooling, part of the tars condense to form drops which, in turn, act as aggregation nuclei for the dust present in the gas G.

[00101] The phenomenon described above therefore determines, in the area where the flow of hot gas G meets the flow of nebulized aqueous mixture MA, the formation of solid or semi-solid encrustations, even of considerable size. Such incrustations, detaching themselves from the walls of the evaporative cooler 20, can flow into the basin 22 and preclude its correct functioning. In fact, the scale has such dimensions as to quickly clog the purge pipe 24 and / or the recirculation circuit 23.

[00102] The crushing means 25, on the other hand, reduce the size of these deposits, so as to allow them to flow correctly through the purge pipe 24. In particular, during the operation of the evaporative cooler 20, the deposits are deposited by gravity on the grid 251 where the regular passage of the knives 250 shreds them into pieces sufficiently small that they can first fall through the grate 250 and can then be conveyed together with the liquid tars through the purge pipe 24.

[00103] As can be seen in figure 8, in this particular embodiment of the evaporative cooler 20, on the bottom of the basin 22 there is an auger 220 suitable for removing all the pollutants that collect there (whether they are tars plus or less fluids or pieces of the deposits previously crushed by the crushing means 25).

[00104] The basin 22 then comprises a socket suitable for withdrawing the aqueous mixture MA. This intake is placed in a position inside the aqueous mixture reserve MA so as not to draw on the heavier pollutants, which are deposited on the bottom of the basin 22, nor on the foams and lighter pollutants that float on the hair of the aqueous mixture MA. The socket feeds the recirculation circuit 23 which supplies the aqueous mixture MA to the nebulization means 21 of the evaporative cooler 20. Furthermore, the socket also feeds the tube 65 which supplies the aqueous mixture MA to the nebulization means 630 of the evaporator 63.

[00105] As already mentioned above, the scrubber 30 comprises a heat exchanger 35 placed along the recirculation circuit 33. The heat exchanger 35 is suitable for cooling the aqueous mixture MA on its way to the nebulization means 31, in so that the aqueous mixture MA can in turn cool the gas G in the scrubber 30.

[00106] Furthermore, the scrubber 30 can advantageously comprise a discharge pipe 36 suitable for removing the excess aqueous mixture MA from the basin 32 and for conveying it towards the outside.

[00107] In the scrubber 30 the gas G is cooled to the temperature required for a good functioning of the gas utilization unit 80, a temperature which typically is between 40 ° C and 50 ° C. During the cooling process of gas G, most of the water and tars present in gas G in the vapor phase at the outlet of the evaporative cooler 20 are condensed. These condensates accumulate in the basin 32 forming the aqueous mixture BUT. This aqueous mixture MA is continuously removed and pumped to the evaporative cooler 20 through the appropriate compensation pipe 37.

[00108] In this regard, it should be noted that in the evaporative cooler 20 the quantity of mixture MA present in the condensed state in the basin 22 progressively decreases due to the continuous evaporation of the same in the gas flow G. On the contrary, in the scrubber 30 the quantity of mixture MA present in the condensed state basin 32 increases progressively due to the continuous condensation of the vapors present in the gas G during cooling. In the macro apparatus 10 according to the invention, the excess of aqueous mixture MA present in the basin 32 is then used to continuously integrate the losses of the mixture MA into the basin 22.

[00109] If the temperature of the gas G leaving the scrubber 30 is higher than the dewpoint temperature of the gas G, the condensed water in the basin 32 is lower than the water evaporated in the evaporative cooler 20. In these operating conditions , even by continuously moving the aqueous mixture MA from the basin 32 to the basin 22, it is necessary to introduce water into the macro-apparatus 10 by drawing from an external reserve through the duct 27.

[00110] If the temperature of the gas G leaving the scrubber 30 is equal to the dewpoint temperature of the gas G, the water condensed in the basin 32 is equal to the water evaporated in the evaporative cooler 20. In these operating conditions by continuously moving the aqueous mixture MA from the basin 32 to the basin 22, the macro apparatus 10 is in water equilibrium.

[00111] If the temperature of the gas G leaving the scrubber 30 is lower than the dewpoint temperature of the gas G, the condensed water in the basin 32 is higher than the water evaporated in the evaporative cooler 20. In these operating conditions , even by continuously moving the aqueous mixture MA from the basin 32 to the basin 22, it is necessary to dispose of water from the macro apparatus 10 towards the outside. Such disposal of water can be done effectively through the purifier 60, as previously mentioned and as will be described in more detail below.

[00112] In accordance with some embodiments of the invention, the macro-apparatus 10 comprises a heat exchanger instead of the scrubber 30. This heat exchanger is preferably of the shell-and-tube type in which the hot gas G exchanges heat with a serving liquid.

[00113] Furthermore, the evaporative cooling of the gas G produces a reserve of water at a high temperature, generally equal to or higher than 80 ° C; this reserve makes it possible to generate water vapor in an economical and above all energetically very convenient way, for example through the evaporator 63 of the purifier 60.

[00114] The water vapor can be usefully evacuated towards the external environment in order to improve the conditions of the process and in particular to allow the lowering of the gas temperature G below its dew point, or dewpoint, as will be described below.

[00115] The purifier 60 therefore allows any excess aqueous mixture MA to be disposed of. This disposal represents a problem for known types of plants, as the aqueous mixture MA that must be disposed of is contaminated by a large quantity of pollutants that are dangerous for man and the environment.

[00116] As already reported above, downstream of the evaporator 63 the purifier 60 comprises means 67 for heating the flow of moist oxygenated gas AU. Such means can take different embodiments. They can comprise, for example, a heat exchanger 670 in which the moist oxygenated gas AU can absorb heat from another hot fluid, for example from the gas G leaving the gasifier 12. Alternatively, the means 67 can comprise a fitting 671 which brings together the wet oxygenated gas AU in another stream of hot gases directed to the oxidizing catalyst. These embodiments of the heating means 67 are described in more detail below.

[00117] Since the temperature of the aqueous mixture MA nebulized in the evaporator 63 is about 80 ° C, the mass of water that evaporates is equal to about 0.5 kg per kilogram of oxygenated gas A, for example air.

[00118] This evaporation in the purifier 60 allows to eliminate the excess of liquid water that condenses in the macro-apparatus 10 in the event that the gas G is to be cooled below its dewpoint temperature, typically below about 60 ° C . In this phase, a quantity of heat made available at low temperature is also used, and therefore generally not usable for other purposes.

[00119] The pollutants present in the aqueous mixture MA are typically hydrocarbons such as phenols, benzenes, toluenes, xylenes, naphthalenes for which the disposal of the excess MA mixture is difficult and expensive.

[00120] By way of example, the presence of phenols inside the aqueous mixture MA depresses the bacterial flora normally present in civil and industrial water purification systems, effectively not allowing the disposal of the aqueous mixture MA through the sewer system .

[00121] The humid oxygenated gas AU containing hydrocarbons in the vapor phase leaving the evaporator 63 typically has a temperature close to the temperature of the water of the aqueous mixture MA present in the basin 22 (about 80 ° C) and must be heated to above 200 ° C, preferably above 300 ° C in order to be then usefully sent to the oxidizing catalyst 68 (see in this regard the graph of figure 14). Inside the oxidizing catalyst 68 (or catalytic oxidizer) the HC hydrocarbons present in the humid oxygenated gas stream are converted, in a known way, into H2O and CO2. At the outlet of the oxidizing catalyst 68, the flow of humid oxygenated gas AU, as it no longer contains hydrocarbons but only water vapor H2O (g) and CO2, can be safely discharged into the atmosphere without any danger for the environment and health ( in this regard see the diagram in figure 13).

[00122] The wet oxygenated gas flow AU can be generated in several ways. An extremely simple way is to use a fan 66 mounted in such a way as to suck air from the environment and blow it into the duct 61 that leads to the evaporator 63 of the purifier 60. Alternatively or in addition to the fan 66, another fan (not shown) can be mounted in such a way as to suck in the oxygenated gas AU already treated by the evaporator 63 and / or by the oxidizing catalyst 68. These solutions therefore require the use of ambient air as oxygenated gas A.

[00123] In accordance with other possible embodiments, aimed at obtaining a greater percentage of oxygen O2 in the oxygenated gas A, alongside or in place of the fans there is a supply system for oxygen O2 under pressure, for example a cylinder or other pressurized oxygen tank. Such embodiments potentially allow to increase at will the percentage of oxygen O2 in the flow of oxygenated gas. The composition of the oxygenated gas A can therefore vary between that of the air (therefore a mixture containing approximately 20% oxygen) and that of pure oxygen (100% O2), the intermediate compositions being generically definable as oxygenated air. The increase in the percentage of oxygen can be useful in some particular cases of operation of the oxidizing catalyst 68 for a more effective destruction of the HC hydrocarbons.

[00124] Figure 1 shows a first embodiment of the purifier 60 for the disposal of the aqueous mixture MA and the related pollutants. In accordance with this embodiment, the means 67 for heating the moist oxygenated gas AU comprise a heat exchanger 670. This heat exchanger 670 is suitable for generating a heat exchange between the gas flow G leaving the gasifier 12 (which is typically found at a temperature of around 600 ° C) and the flow of humid oxygenated gas AU leaving the evaporator 63 (which is typically found at a temperature of around 80 ° C).

[00125] The heat exchanger 670 is not subject to fouling due to the condensation of the tars and coal dust present in the gas G as the quantity of heat to be exchanged to raise the temperature of the humid oxygenated gas AU from about 80 ° C at about 300 ° C it is limited with respect to the total sensible heat available in the gas G. In the face of this there is a minimum cooling of the gas G and, consequently, minimum phenomena of condensation of the tars and adhesion of the powders.

[00126] Downstream of the heat exchanger 670 there is therefore the oxidative catalyst 68, at which the moist oxygenated gas AU reaches a temperature of about 300 ° C. Following the passage in the oxidative catalyst 68, the flow of moist oxygenated gas AU, now purified, is introduced directly into the atmosphere.

[00127] Figure 2 shows a second embodiment of the purifier 60 for the disposal of the aqueous mixture MA and the relative pollutants. This embodiment is suitable for use in plants 100 in which the utilization unit 80 of the gas G is a thermal unit, typically an internal combustion engine or a burner. In accordance with this embodiment, the means for heating the moist oxygenated gas AU comprise a fitting 671 suitable for making the flow of moist oxygenated gas AU (which is typically found at a temperature around 80 ° C) flow into the gas flow. discharge of the utilization unit 80 (which are typically found at a temperature of about 400-500 ° C).

[00128] The humid oxygenated gas AU is thus mixed with the exhaust gases of the utilization unit 80 and the gaseous mixture thus obtained is then fed to the oxidizing catalyst 68 and then dispersed into the atmosphere.

[00129] This solution is particularly advantageous in the case in which, as commonly occurs for endothermic engines available commercially, the utilization unit 80 is already equipped with its own oxidizing catalyst 68. The oxidizing catalyst 68 is therefore preferably one only, in common between the purifier 60 and the utilization unit 80.

[00130] According to this configuration, the quantity of sensible heat present in the exhaust gases and the relative temperature level are able to ensure that the final gaseous mixture, obtained from the introduction of the humid oxygenated gas AU into the exhaust gases , has a temperature higher than 200 ° C, typically higher than 300 ° C. This temperature therefore allows, by means of the oxidizing catalyst 68, the elimination of the HC hydrocarbons present in the gaseous mixture and therefore their final release into the atmosphere.

[00131] Figure 3 shows a further embodiment of the plant 100, comprising a different disposal system for the aqueous mixture MA and the relative pollutants. In accordance with this embodiment, the macro apparatus 10 further comprises the auxiliary gasifier 125 previously described.

[00132] In accordance with this embodiment, part of the moist oxygenated gas at a temperature of about 80 ° C is conveyed to the auxiliary gasifier 125, while the remaining part is conveyed to the heating means 67 and therefore to the oxidizing catalyst 68. In this type of plant, the means 67 for heating the humid oxygenated gas AU can comprise both a heat exchanger 670 as in the plant in figure 1 and a fitting 671 as in the plant in figure 2. For this reason in the figure 3, the means 67 for heating the moist oxygenated gas AU are represented in an extremely schematic way.

[00133] The gases produced by the gasification of the charcoal C in the auxiliary gasifier 125 (ie H2, H2O, CO, CO2) are carried through a special conduit 126 in the upper part of the gasifier 12 reactor. These products have a temperature of about 400â € “800 ° C and, by mixing with the combustion oxygenated gas flow entering the gasifier 12, contribute to the gasification reactions described above, in particular the coal reforming reaction, the Boudouard reaction and the methanation reaction.

[00134] The coal reforming reaction, favored by the presence of water vapor H20 (g) in the oxidation zone of the reactor, as well as the Boudouard reaction (also described above) are strongly endothermic reactions. These reactions therefore absorb the heat released by the other exothermic reactions that take place in the gasifier 12 (typically the combustion reactions of carbon and pyrolysis gases) and thus limit the temperatures in the oxidation zone to values around 800 ° Câ € "900 ° C.

[00135] These considerations, valid for the gasifier 12, are even more important for the auxiliary gasifier 125, due to the fact that it operates substantially in the presence of only carbon C. The generalized combustion reaction of carbon C could lead to inside the auxiliary gasifier 125 when very high temperatures exceeding 1500 ° C are reached. The introduction of water vapor H2O (g) into this type of reactor and the consequent generation of endothermic reactions is therefore even more important for limiting the temperature in the reactor.

[00136] As already explained above, the aqueous mixture MA, taken from the basin 22 and nebulized in the evaporator 63 of the purifier 60 with a temperature equal to or higher than 80 ° C, easily allows to saturate with water vapor H20 (g) a consistent flow of oxygenated gas A. It is thus possible to bring a consistent quantity of water vapor H20 (g) inside the auxiliary gasifier 125. Furthermore, as already explained above, the heat necessary to obtain the evaporation of the water that saturates the oxygenated gas stream A is provided by the cooling of the aqueous mixture MA.

[00137] Such heat, due to the relatively low temperature at which it is available, cannot generally find a useful use. On the contrary, in the macro apparatus 10 according to the invention, the use of this heat allows to exploit the gasification of the charcoal C in the auxiliary gasifier 125. All this allows to increase the energy efficiency and the overall quality of the whole. gasification process. The increase in energy efficiency can reach up to about 15% -20% depending on the type of BM biomass and its ash content, meaning a decrease in the specific consumption of BM biomass up to about 15% - 20% and an increase in the content of hydrogen H2 in the G gas produced by the plant.

[00138] This increase in energy efficiency is due to the complete utilization of the carbon content of the BM biomass which cannot be fully exploited in the main downdraft gasifier 12. In fact, the final residue of the updraft 125 auxiliary gasifier is made up only of inorganic ash.

[00139] It should be noted here that another solution for the generation of steam is known, historically used in mineral coal gasifiers. This known solution exploits the high temperature heat available in correspondence with the external walls of the reactor. However, a solution of this type does not entail any energy benefits as the heat necessary for the evaporation of the water is subtracted from the gasification reactions.

[00140] Figures 5 to 8 show an embodiment of the evaporative cooler 20 and of the evaporator 63 of the purifier 60, integrated in a single assembly 50. This embodiment of the invention is particularly advantageous. In fact, it allows to minimize heat losses along the line that feeds the aqueous mixture MA from the basin 22 to the nebulization means 630 of the evaporator 63. For an optimal operation of the invention, the aqueous mixture MA must in fact be nebulized at the highest possible temperature among those already available inside the plant 100. The high temperature of the aqueous mixture MA (usually equal to about 80 ° C) guarantees an efficient saturation of the oxygenated gas flow A. this, the exploitation of heat made available by the plant 100 itself makes it possible not to resort to external heat sources which would imply a drastic decrease in the overall energy efficiency of the process.

[00141] In accordance with the embodiments represented in the attached figures, the plant 100 also comprises an electrostatic precipitator 40 suitable for treating the flow of gas G already treated by the macro-apparatus 10. The gas G leaving the macro-apparatus 10 has in fact immediately the desired cooling and a first dedusting, but still contains several pollutants in suspension. These pollutants (fine dust, tars in the aerosol phase and vapor) can be advantageously removed from the gas G by means of an electrostatic precipitator 40.

[00142] In particular, the plant 100 preferably comprises a wet electrostatic precipitator 40, also called Wet ElectroStatic Precipitator or WESP, of a per se known type. It includes ducts inside which an electrostatic field is maintained. In particular, the electrostatic precipitator 40 preferably comprises tubular structures inside each of which an electrode is placed. An electrostatic field can thus form inside each tubular structure, between the walls and the central electrode.

[00143] Furthermore, the precipitator 40 can preferably comprise:

- a tank 42 suitable for collecting the tars and water removed from gas G;

- a purge pipe 44 suitable for removing the condensed tars from the bottom of the tank 42 and conveying them towards the gasifier 12;

- a discharge tube 46 suitable for removing the excess aqueous mixture from the tank 42 and conveying it towards the basin 32; And

- an outlet duct 18 suitable for conveying the flow of clean gas G to a user unit 80.

[00144] The electrostatic precipitator 40 allows the gas G to be cleaned of suspended pollutants in order to obtain the desired quality for the utilization unit 80. The cleaning of the gas occurs, in a per se known manner, due to the electrostatic attraction exerted on the pollutants by the walls of the precipitator 40.

[00145] Immediately upstream of the electrostatic precipitator 40, the cooling of the gas G in the scrubber 30 causes the condensation of the vapors still present inside it. The formation of water droplets provides condensation nuclei for the tar molecules, and vice versa, the formation of tar droplets provides condensation nuclei for the water molecules. In this way the aqueous mixture MA passes from the vapor phase to the liquid phase, thus forming an aerosol of tar and water.

[00146] Once inside the electrostatic precipitator 40, the aerosol suspended in the gas G is attracted towards the walls of the precipitator itself by the effect of the electrostatic field maintained therein. The aerosol therefore adheres to the walls of the precipitator 40 and, dripping along the walls, collects in the tank 42.

[00147] Referring again to the diagrams of Figures 1 to 3, it is possible to note how the condensed liquids, removed from the gas G in the electrostatic precipitator 40, collect in the tank 42, which is also equipped with a purge pipe 44 .

[00148] Similarly to what has already been described above with reference to the purging pipes of the basins 22 and 32 of the evaporative cooler 20 and of the scrubber 30 respectively, the purging pipe 44 also allows at least part of the aqueous mixture MA to be removed from the bottom of the tank 42 . The removed mixture contains water, polar tars in solution and above all non-polar tars (insoluble in water) which collect on the bottom of the tank 42. For this reason, the purge pipe 44 advantageously draws in a low point of the tank 42, where they collect spontaneously by gravity the heavier non-polar tars. The tars, polar and non-polar, can be usefully returned to the mouth of the gasifier 12 and subjected again to the oxidation and gasification processes.

[00149] The lighter fraction of tars remains volatile in gas G even at the outlet temperature from the electrostatic precipitator 40. This fraction of tars is therefore conveyed with the flow of gas G to subsequent uses. Typically, the use of gas G involves a combustion phase, a phase to which even light tars can usefully contribute in view of their chemical nature.

[00150] The tank 42 of the precipitator 40 finally comprises a discharge pipe 46. This pipe is suitable for removing any excess aqueous mixture MA from the tank 42 and conveying it towards the basin 32.

[00151] In accordance with some embodiments, the electrostatic precipitator 40 comprises a thermal insulation suitable to avoid as much as possible the exchange of heat with the external environment. The gas G flows inside the electrostatic precipitator 40 at a temperature generally higher than the ambient temperature, usually at a temperature between 40 ° C and 60 ° C. Under these conditions, gas G would tend to spontaneously release heat to the external environment, cooling itself and triggering further condensation phenomena. These phenomena are therefore reduced thanks to the thermal insulation of the electrostatic precipitator 40.

[00152] In accordance with some embodiments, the plant 100 further comprises means 70 for reheating the gas G after having cooled it. Such means 70, if present, can for example be associated with the outlet duct 18.

[00153] The cooling of gas G, especially inside the evaporative cooler and scrubber 30, causes the condensation of most of the water and tars present in it in the form of vapor. However, gas G remains saturated with vapors, that is, it remains with a relative humidity equal to 100%. In these conditions, even a slight lowering of the temperature of the gas G determines the condensation of the vapors and the consequent formation of mists inside the gas G. The occurrence of such a lowering of temperature is extremely probable along the pipe 18 which carries the gas G from the electrostatic precipitator 40 to the external utilization unit 80. The consequent condensation and formation of mists would therefore risk dirtying the duct 18 and the utilization unit itself 80.

[00154] To avoid the aforementioned drawbacks, in accordance with some embodiments of the invention, the temperature of the gas G can be raised again by a few degrees (for example 10-20C °). This results in a reduction in relative humidity which falls below 100%. Under these changed conditions the gas G can undergo slight changes in temperature without giving rise to the formation of mists.

[00155] The heating means 70 can advantageously exploit the heat made available by other sections of the plant 100, such as for example the evaporative cooler 20, or by the unit 80 for the use of gas (which preferably comprises a internal combustion engine or another form of burner).

[00156] The circuit can be made in a manner known per se, for example it can advantageously be a closed circuit inside which a predetermined quantity of heating liquid circulates.

[00157] Each of the purge pipes 24, 34 and 44 (if present) and each of the recirculation circuits 23, 33 and 64, as well as the pipe 65, preferably comprises a pump suitable for handling the aqueous mixture MA even when it is rich in heavy tars such as those which must be returned to the mouth of the gasifier 12. These pumps can preferably be centrifugal pumps, gear pumps or peristaltic pumps, suitable for handling even very viscous fluids. In accordance with some embodiments, the pump placed on the recirculation circuits 23 and 33 which feed the nebulization means 21 and 31 of the evaporative cooler 20 and of the scrubber 30 respectively, can advantageously be centrifugal pumps. This type of pump is in fact suitable for providing a considerable flow rate of aqueous mixture MA, as long as it has a sufficiently low viscosity.

[00158] In accordance with some possible embodiments, the discharge pipes 36 and 46 can advantageously comprise a decanter suitable for further separating the tars from the water by gravity. The tars recovered from the bottom of the decanter can then be taken for their storage or to bring them back to the gasifier 12.

[00159] In accordance with some possible embodiments, the plant 100 further comprises a blower mounted on the duct 18 and suitable for moving the gas G along the entire plant 100, from the gasifier 12, through the dedusting 14, the evaporative cooler 20, the scrubber 30 and the electrostatic precipitator 40 (if present) up to the duct 18 and beyond.

[00160] In accordance with some possible embodiments, the plant 100 finally comprises a unit 80 for using the gas.

[00161] In accordance with the embodiments of the plant 100 represented in the attached figures 2 and 3, the gas utilization unit 80 comprises an internal combustion engine to which a generator for the production of electric energy.

[00162] In particular, it should be noted that the excellent quality of the gas G leaving the plant 100 according to the invention allows the powering of today's alternative engines (both Otto cycle and Diesel cycle) and / or gas turbine engines.

[00163] In accordance with other possible embodiments, the gas utilization unit 80 can comprise: burners and / or boilers for heating and / or for the production of domestic hot water; manifolds for conveying gas in a distribution network; compressors for storing gas in cylinders or tanks; gas filtering units using membranes or molecular filters for the fractionation of the producer gas into the individual gases that constitute it (H2, CO, N2, etc.); units for the production of liquid fuels by catalytic processes such as the Fischer-Tropsch process; and any other type of gas utilization unit 80 known per se.

[00164] The invention also relates to a method for the production and treatment of gas G. The method includes, when fully operational, the steps of:

- preparing a macro apparatus 10 in accordance with what is described above;

- supplying a flow of oxygenated gas and fuel BM to the gasifier 12;

- conveying the flow of gas G from the gasifier 12 to the dedusting unit 14;

- conveying the flow of gas G from the dedusting unit 14 to the evaporative cooler 20; - nebulising in the evaporative cooler 20 the aqueous mixture MA in the gas flow G so as to obtain the washing of the gas G and a first cooling phase by absorption of the latent heat of evaporation in the aqueous mixture MA;

- maintaining and decanting a reserve of aqueous mixture MA in the condensed state in the basin 22 of the evaporative cooler 20;

- removing the aqueous mixture MA from the basin 22 and feeding it to the nebulization means 21 of the evaporative cooler 20;

- remove the condensed pollutants from the bottom of the basin 22 and convey them towards the gasifier 12;

- conveying the flow of gas G from the evaporative cooler 20 to the scrubber 30;

- nebulising the aqueous mixture MA in the gas flow G in the scrubber 30 so as to obtain a second cooling phase by removing heat from the aqueous mixture MA;

- maintaining and decanting a reserve of aqueous mixture MA in the condensed state in the basin 32 of the scrubber 30;

- removing part of the aqueous mixture MA from the basin 32 and feeding it to the nebulization means 31;

- removing part of the aqueous mixture MA from the basin 32 and feeding it to the basin 22 of the evaporative cooler 20;

- remove the condensed pollutants from the bottom of the basin 32 and convey them towards the gasifier 12;

- cooling by means of the heat exchanger 35 the aqueous mixture MA in the path from the basin 32 to the nebulization means 31;

- introduce a flow of oxygenated gas A into the evaporator 63 of the purifier 60;

- taking a quantity of aqueous mixture MA from the basin 22 of the evaporative cooler 20;

- nebulize in the evaporator 63 the aqueous mixture MA withdrawn from the basin 22 in the oxygenated gas flow A so as to obtain a humid oxygenated gas flow AU;

- heating the moist oxygenated gas AU in the heating means 67 to a temperature over 200 ° C;

- conveying the hot humid oxygenated gas AU to the oxidizing catalyst 68;

- in the oxidant catalyst 68 promoting the oxidation of the organic pollutants suspended in the humid oxygenated gas AU;

- introduce the purified humid oxygenated gas AU into the atmosphere; And

- convey the flow of gas G from the scrubber 30 towards the outside of the macro-apparatus 10.

[00165] According to an embodiment of the method, the first cooling step lowers the temperature of the gas G from the 400-800 ° C at which it leaves the gasifier 12 to 75-90 ° C. This first cooling phase therefore involves the absorption of a large amount of heat, present in the gas G in the form of sensible heat. In the method according to the invention, the aqueous mixture MA preferably removes a large amount of heat from the gas G by absorbing it in the form of latent heat of evaporation, while a small part is absorbed in the form of sensible heat. In this first phase (evaporative) there is therefore no heat exchange towards the outside of the system and the heat therefore remains inside the gas flow G saturated with vapors.

[00166] According to an embodiment of the method, the second cooling phase lowers the temperature of gas G from 75-90 ° C at which it leaves the evaporative cooler 20 to 40-60 ° C, which are optimal for the operation of the utilization unit 80. This second cooling phase of gas G involves the removal of a large amount of heat, present in the form of latent heat in the vapors generated by the aqueous mixture MA (water vapor and light tars in the vapor phase) and mixed to gas G. In the method according to the invention, the aqueous mixture MA preferably removes the heat by absorbing it in the form of sensible heat, thus raising its own temperature. In this second phase (condensing) there is therefore an exchange of heat towards the outside of the system, through the exchanger 35.

[00167] The present invention also relates to a gasifier 12 of the downdraft opencore type comprising means 120 for lifting the outer shell 121. Such lifting means, as already described above in relation to the gasifier 12 forming part of the macro apparatus 10, are suitable for carrying the outer shell 121 from an operational closed configuration to an open maintenance configuration.

[00168] The present invention also relates to an assembly 50 similar to that described above in relation to Figures 5 to 8 and forming part of the macro apparatus 10. In particular, the assembly 50 comprises an evaporative cooler 20 and an evaporator 63.

[00169] The evaporative cooler 20 of assembly 50 is suitable for treating a flow of gas G and comprises:

- nebulization means 21 of an aqueous mixture MA in the gas stream G,

- a basin 22 suitable for decanting and maintaining a reserve of aqueous mixture MA in the condensed state in the evaporative cooler 20,

- a recirculation circuit 23 suitable for removing the aqueous mixture MA from the basin 22 and feeding it to the nebulization means 21 of the evaporative cooler 20; And

- a purge pipe 24 suitable for removing condensed pollutants from the bottom of the basin 22 and conveying them to the outside

[00170] Evaporator 63 of assembly 50 comprises:

- a duct 61 for the adduction of a flow of oxygenated gas A;

- nebulization means 630 of an aqueous mixture MA in the oxygenated gas stream A;

- a tube 65 suitable for withdrawing a quantity of aqueous mixture MA from the basin 22 of the evaporative cooler 20 and feeding the aqueous mixture MA to the nebulization means 630; And

- a 62â € ™ duct suitable for conveying the humid oxygenated gas AU to the outside.

[00171] The present invention also relates to an evaporative cooler 20 similar to the one described above in relation to Figures 5 to 8 and forming part of the macro apparatus 10. In particular, the evaporative cooler 20, suitable for treating a flow of gas G, comprises: - nebulization means 21 of an aqueous mixture MA in the gas stream G;

- a basin 22 suitable for decanting and maintaining a reserve of aqueous mixture MA in the condensed state in the evaporative cooler 20;

- a recirculation circuit 23 suitable for removing the aqueous mixture MA from the basin 22 and feeding it to the nebulization means 21 of the evaporative cooler 20;

- a purge pipe 24 suitable for removing the condensed pollutants from the bottom of the basin 22 and conveying them towards the outside; And

- means 25 for crushing the encrustations which form inside the evaporative cooler 20 during the treatment of the gas flow G.

[00172] In accordance with an embodiment of the evaporative cooler 20, the crushing means 25 are comprised between the zone in which the nebulization of the aqueous mixture MA takes place and the basin 22 in which the aqueous mixture MA is collected. Preferably, said crushing means 25 comprise a series of knives 250 movable with respect to a grid 251.

[00173] From what has been said above, it will be clear to the skilled person that the plant 100 as a whole, the macro apparatus 10 in particular and the method according to the invention overcome the disadvantages found in relation to the known art.

[00174] It is clear that the specific characteristics are described in relation to the different embodiments of the plant 100 with an illustrative and non-limiting intent.

[00175] Obviously, to the macro apparatus 10 and / or to the plant 100 according to the present invention, a person skilled in the art, in order to satisfy contingent and specific needs, will be able to make further modifications and variations, all however contained within the scope of protection of the invention, as defined by the following claims.

Claims (18)

Claims 1. Macro apparatus (10) for the production and treatment of gas G, comprising: - a gasifier (12) suitable for receiving a flow of oxygenated gas and fuel BM and for emitting a flow of gas G; - a conduit suitable for conveying the flow of gas G from the gasifier (12) to a dedusting unit (14); - a dedusting unit (14); - a conduit suitable for conveying the flow of gas G from the dedusting unit (14) to an evaporative cooler (20); - an evaporative cooler (20) suitable for treating the gas flow G, comprising: - nebulization means (21) of an aqueous mixture MA in the gas stream G, - a basin (22) suitable for decanting and maintaining a reserve of aqueous mixture MA in the condensed state in the evaporative cooler (20), - a recirculation circuit (23) suitable for removing the aqueous mixture MA from the basin (22) and feeding it to the nebulization means (21) of the evaporative cooler (20); And - a purge pipe (24) suitable for removing the condensed pollutants from the bottom of the basin (22) and conveying them towards the gasifier (12); - a conduit suitable for conveying the flow of gas G from the evaporative cooler (20) to a scrubber (30); - a scrubber (30) suitable for treating the gas flow G, comprising: - nebulization means (31) of an aqueous mixture MA in the gas stream G, - a basin (32) suitable for decanting and maintaining in the scrubber (30) a reserve of aqueous mixture MA in the condensed state, - a recirculation circuit (33) suitable for removing part of the aqueous mixture MA from the basin (32) and feeding it to the nebulization media (31), - a purge pipe (34) suitable for removing the condensed pollutants from the bottom of the basin (32) and conveying them to the gasifier (12), - a heat exchanger (35) located along the recirculation circuit (33) of the scrubber (30), and - a compensation pipe (37) suitable for removing part of the aqueous mixture MA from the basin (32) and feeding it to the basin (22) of the evaporative cooler (20); - a conduit suitable for conveying the flow of gas G from the scrubber (30) towards the outside of the macro-apparatus (10); the macro apparatus (10) further comprising a purifier (60) suitable for receiving a flow of oxygenated gas A and an aqueous mixture MA and for emitting a flow of purified moist oxygenated gas AU, the purifier (60) comprising: - a conduit (61) for the adduction of a flow of oxygenated gas A; - an evaporator (63) having nebulization means (630) of an aqueous mixture MA in the flow of oxygenated gas A; - a tube (65) suitable for withdrawing a quantity of aqueous mixture MA from the basin (22) of the evaporative cooler (20) and feeding the aqueous mixture MA to the nebulization means (630) of the evaporator (63); - a conduit (62â € ™) suitable for conveying the humid oxygenated gas AU from the evaporator (63) to heating means (67); - means (67) for heating the moist oxygenated gas AU suitable for raising its temperature beyond 200 ° C; - a conduit (62â €) suitable for conveying the moist oxygenated gas AU to an oxidizing catalyst (68); - an oxidizing catalyst (68) suitable for promoting the oxidation of pollutants suspended in the humid oxygenated gas AU; And - a conduit suitable for introducing into the atmosphere the purified moist oxygenated gas AU downstream of the oxidizing catalyst (68). Macro apparatus (10) according to claim 1, wherein the gasifier (12) is of the downdraft opencore type. Macro apparatus (10) according to claim 1 or 2, further comprising an auxiliary gasifier (125) suitable for the gasification of the charcoal powder C coming out of the gasifier (12). Macro apparatus (10) according to the preceding claim, in which the auxiliary gasifier (125) is of the updraft opencore type. 5. Macro apparatus (10) according to claim 3 or 4, further comprising a conduit (69) suitable for supplying the auxiliary gasifier (125) with the humid oxygenated gas AU coming from the evaporator (63), and a conduit (126) suitable for feeding to the gasifier (12) the gases produced by the gasification of the charcoal C in the auxiliary gasifier (125). Macro apparatus (10) according to any preceding claim, wherein the evaporative cooler (20) comprises means (25) for crushing the solid or semi-solid encrustations which form inside it during the treatment of the gas flow G. 7. Macro apparatus (10) according to the preceding claim, in which the evaporative cooler (20) comprises at least one screw (220) suitable for removing from the bottom of the basin (22) the pollutants that collect there, said pollutants comprising tars more or fewer fluids and / or pieces of solid or semi-solid encrustations crushed by the crushing means (25). Macro apparatus (10) according to any preceding claim, wherein the means (67) for heating the stream of moist oxygenated gas AU in the purifier (60) comprises a heat exchanger (670) in which the moist oxygenated gas AU can absorb heat from gas G leaving the gasifier (12). Macro apparatus (10) according to any preceding claim, wherein the means (67) for heating the stream of wet oxygenated gas AU in the purifier (60) comprises a fitting (671) which brings the wet oxygenated gas AU into another hot gas flow directed to the oxidizing catalyst (68). Macro apparatus (10) according to any preceding claim, wherein the gasifier (12) comprises means (120) for lifting the outer shell (121), suitable for bringing the outer shell (121) from an operational closed configuration, to an open maintenance setup. Plant (100) for the production and treatment of gas G, comprising a macro apparatus (10) according to any preceding claim, an electrostatic precipitator (40) and a utilization unit (80). Plant (100) according to the preceding claim, wherein said utilization unit (80) comprises an internal combustion engine and / or a burner and an oxidizing catalyst (68), the oxidizing catalyst (68) being in common with the purifier ( 60) of the macro apparatus (10). System (100) according to claim 11 or 12, in which the electrostatic precipitator (40) comprises a thermal insulation suitable for avoiding the exchange of heat between the gas G and the external environment. 14. Method for the production and treatment of gas G, comprising, when fully operational, the steps of: - providing a macro apparatus (10) in accordance with any one of claims 1 to 10; - supplying a flow of oxygenated gas and BM fuel to the gasifier (12); - convey the flow of gas G from the gasifier (12) to the dedusting unit (14); - convey the flow of gas G from the dedusting unit (14) to the evaporative cooler (20); - nebulising in the evaporative cooler (20) an aqueous mixture MA in the gas flow G so as to obtain the washing of the gas G and a first cooling phase by absorption of heat in the aqueous mixture MA; - maintaining and decanting in the basin (22) of the evaporative cooler (20) a reserve of aqueous mixture MA in the condensed state; - removing the aqueous mixture MA from the basin (22) and feeding it to the nebulization means (21) of the evaporative cooler (20); - remove the condensed pollutants from the bottom of the basin (22) and convey them towards the gasifier (12); - conveying the flow of gas G from the evaporative cooler (20) to the scrubber (30); - nebulising the aqueous mixture MA in the gas flow G in the scrubber 30 so as to obtain a second cooling phase by removing heat from the aqueous mixture MA; - maintain and decant in the basin (32) of the scrubber (30) a reserve of aqueous mixture MA in the condensed state; - removing part of the aqueous mixture MA from the basin (32) and feeding it to the nebulization means (31); - remove part of the aqueous mixture MA from the basin (32) and feed it to the basin (22) of the evaporative cooler (20); - remove the condensed pollutants from the bottom of the basin (32) and convey them towards the gasifier (12); - cooling by means of the heat exchanger (35) the aqueous mixture MA in the path from the basin (32) to the nebulization means (31); - introduce a flow of oxygenated gas A into the evaporator (63) of the purifier (60); - take a quantity of aqueous mixture MA from the basin (22) of the evaporative cooler (20); - nebulize in the evaporator (63) the aqueous mixture MA withdrawn from the basin (22) in the oxygenated gas flow A so as to obtain a humid oxygenated gas flow AU; - heating the moist oxygenated gas AU in the heating means (67) to a temperature over 200 ° C; - conveying the hot humid oxygenated gas AU to the oxidizing catalyst (68); - promoting in the oxidizing catalyst (68) the oxidation of the organic pollutants suspended in the humid oxygenated gas AU; - introduce the purified humid oxygenated gas AU into the atmosphere; And - convey the flow of gas G from the scrubber (30) towards the outside of the macro apparatus (10). 15. Gasifier (12) of the downdraft opencore type characterized in that it comprises means (120) for lifting the outer shell (121), suitable for bringing the outer shell (121) from a closed operating configuration to an open maintenance configuration . 16. Evaporative cooler (20) suitable for treating a flow of gas G, comprising: - nebulization means (21) of an aqueous mixture MA in the gas stream G, - a basin (22) suitable for decanting and maintaining a reserve of aqueous mixture MA in the condensed state in the evaporative cooler (20), - a recirculation circuit (23) suitable for removing the aqueous mixture MA from the basin (22) and feeding it to the nebulization means (21) of the evaporative cooler (20); - a drain pipe (24) suitable for removing the condensed pollutants from the bottom of the basin (22) and conveying them to the outside; And - means (25) for crushing the encrustations that form inside the evaporative cooler (20) during the treatment of the gas flow G. Evaporative cooler (20) according to the preceding claim, in which the crushing means (25) are comprised between the zone in which the nebulization of the aqueous mixture MA takes place and the basin (22) in which the aqueous mixture MA is collected, and wherein the crushing means (25) comprise a series of knives (250) movable with respect to a grid (251). 18. Assembly (50) comprising an evaporative cooler (20) and an evaporator (63), wherein the evaporative cooler (20) is suitable for treating a flow of gas G and comprises: - nebulization means (21) of an aqueous mixture MA in the gas stream G, - a basin (22) suitable for decanting and maintaining a reserve of aqueous mixture MA in the condensed state in the evaporative cooler (20), - a recirculation circuit (23) suitable for removing the aqueous mixture MA from the basin (22) and feeding it to the nebulization means (21) of the evaporative cooler (20); And - a drain pipe (24) suitable for removing the condensed pollutants from the bottom of the basin (22) and conveying them to the outside; and in which the evaporator (63) comprises: - a conduit (61) for the adduction of a flow of oxygenated gas A; - nebulization means (630) of an aqueous mixture MA in the oxygenated gas stream A; - a tube (65) suitable for withdrawing a quantity of aqueous mixture MA from the basin (22) of the evaporative cooler (20) and feeding the aqueous mixture MA to the nebulization means (630); - a duct (62â € ™) suitable for conveying the humid oxygenated gas AU towards the outside.