Equipment and method for thermal treatment of combustible solid material with inertization of ashes

Abstract

The present invention relates to an equipment and the relative process for performing thermal treatment at high temperature of combustible solid materials combined with inertization of ashes obtained therefrom. In particular, said equipment allows a particularly efficient and safe treatment of industrial and municipal combustible solid waste of various nature, also any dangerous ones.

Description

EQUIPMENT AND METHOD FOR THERMAL TREATMENT OF COMBUSTIBLE SOLID MATERIAL WITH INERTIZATION OF ASHESScope of the invention

[0001] The present invention concerns an equipment and the relative process for performing thermal treatment at high temperature of combustible solid materials combined with inerti zation of ashes obtained therefrom .

[0002] In particular, said equipment allows a particularly ef ficient and safe treatment of combustible solid industrial and municipal waste of varied nature, also any dangerous ones ( toxic, harmful , and so on) .Brief outlines of the known art

[0003] Traditional systems mainly used till today for disposal of combustible solid materials , in particular municipal and / or industrial solid waste are known to provide , for example , burying them into a dump or incineration with conventional technologies . However, both these solutions have many issues of environmental impact . For example , in the event of burying, the risk of long-lasting pollution of aqui fer because of the possibility of leachates is very high . While in the case of incineration, although pollution by macro-pollutant substances ( such as particulates , unburnt substances , nitrogen oxides and acids ) may be remarkably reduced, the amounts of micro-pollutants introduced into the environment are anyway high .

[0004] Therefore , over the past few years , alternative ways to existing disposal processes have been searched . In particular, pyrolysis processes of waste have been proposed, that is thermal treatments capable of trans forming bigger molecules into smaller molecules ( and, therefore , intosimpler final substances) . These processes are usually performed in an environment with low oxygen and at sufficiently high temperatures to volatilize organic pollutants. More specifically, in the absence of oxygen (therefore, in a reducing environment) , pyrolysis causes thermochemical decomposition of matter. This process, endothermic by its nature, operates cleavage of complex molecules (macromolecules) which are present, for example, in rubbers, in plastics, in cellulosic components and in other complex chemical compounds, transforming them into structurally simpler molecules (that is, smaller and, preferably, volatile) . In this way, a gaseous combustible mixture is mainly obtained at the end of the pyrolytic process and it can be used, for example, to feed gas turbines and therefore to produce electrical energy. Even more specifically, the combustion of waste described above causes thermal decomposition of matter, mineralization of organic substances contained in waste and transformation of inorganic substances into more easily separable and recoverable forms, or that can be safely disposed of in dump, in addition to a high reduction of weight and volume of residual waste (until assuming, for example, values equal to 10% or less of the initial volume) .

[0005] Waste which can be treated in this type of plants are, for example, preferably selected from: residues of transformation processes of paper, plastic, rubber and tires; as well as combustibles obtained by biomasses, such as timber or agricultural residues, and / or materials of organic origin and / or waste of hospitals and / or toxic / harmful industrial residues.

[0006] The substances emitted in traditional combustion processes are, for example, made up of: dust, carbon monoxide, sulfur dioxide, nitrogen oxides, hydrochloric or hydrofluoric acid, heavy metals, chlorine-organicsubstances , such as , for example , dioxins and furans . In particular, the presence of dioxins and / or furans in the exhaust fumes of said processes determines a strong environmental impact by the existing processes . The production of dioxins and furans occurs mainly because of incomplete combustion o f MSW . To minimi ze the formation o f these highly polluting and toxic substances , the combustion process must include the use of a suf ficient quantity of oxygen, high temperatures and prolonged contact times . Alternatively, dioxins and furans that are formed can be separated with the help of activated carbon or other abatement systems (however, with very high management average costs ) .

[0007] Unfortunately, existing equipment to execute combustion of waste such as the ones described in US 3 , 759 , 036 and US 4 , 732 , 092 are not always capable of providing abatement o f polluting emissions in such a way that they fall into prescribed limits according to laws in force . In other cases , however, prescribed limits may be respected only with the use of constructively complex equipment and which are poor value for money, in particular in terms of energetic consumptions necessary to achieve the relative process .

[0008] The PCT patent application WO2005121645 Al , and the corresponding granted European patent EP 1607681 Bl have recently described an equipment and the relative method to execute thermal treatment at high temperature of combustible materials , in particular waste of any composition, in which said treatment is executed between a pyrolysis chamber, in which combustible material i s heated in reducing environment , and a combustion chamber, in which said material is burnt through a current of gas containing oxygen . However, the described equipment still has technological di f ficulties which have not been suitably solved and the relative combustion process does notguarantee a type o f volumetric combustion with as much as possible uni form temperatures , in such a way to generate a stable combustion, of the so-called "flamel ess" type , capable of enabling both complete fusion and fluidi fication of ashes , and limitation of temperature peaks inside the fusion chamber . In particular, the limitation o f temperature peaks would have the double advantage of reducing production of nitrogen oxides and limiting the temperature on the wall s of refractory material delimiting the combustion chamber itsel f ( in fact , an excessive increase in average temperature in the combustion chamber would stress refractory material too much, which must be subj ect to temperature lower than 1600 ° C to guarantee a suitable duration . In addition, the parts of the equipment which are mainly subj ect to wear ( such as the movable grate which moves the material in the pyro-gasi f ication chamber and the evacuation crucible of ashes from the combustion chamber ) must be regularly replaced . Given the high compactness and fragility of refractory material , it cannot be subj ect to too many substantial variations of temperature and, therefore , the aforesaid components must be replaced without letting the refractory material excessively cool down . In order to achieve this purpose , innovative constructive solutions must be found which allow quick and ef ficient replacement of these two components as needed without exposing the most sensitive parts the equipment itsel f to excessive variations / decreases in temperature .Technical issue of the invention

[0009] Therefore , the field has the deep and strong need to solve the disadvantages o f the current technique , brie fly described above . In addition, the following needs are also strongly felt : the need to separate more ef ficiently residual solid particles of combustion dragged by the flowof combustion gases ; to optimi ze the control of the flow of solid material inside the equipment ; to improve the control of combustion through optimal modulation of various flows of comburent gas ; to guarantee high temperatures also downstream of the evacuation outlet of gas , thus avoiding any return of relatively cold gas inside the combustion chamber, which could cause solidi fication o f molten material thus causing the blocking of the discharge crucible of molten ashes .

[0010] The aim of the present invention is to provide a suitable solution for the technical issue described above , thus suitably complying with the needs of the skilled specialists of the field .Summary of the invention

[0011] These and other aims of the invention have been obtained with the production of a suitable equipment for executing in an optimal way thermal treatment at high temperature of combustible solid materials , combined with inerti zation of ashes obtained therefrom, and of a relative method for executing said thermal treatment through the use of said equipment .

[0012] Hence , an obj ect of the present invention is an equipment for pyro-gasi f ication of combustible solid materials , in particular industrial and municipal combustible solid waste of varied nature, also any dangerous one , combined with inerti zation of ashes obtained therefrom, as contained in the appended independent claim 1 , as well as in the following description and in the relative appended figures .

[0013] Another obj ect of the present invention is a process for performing the aforesaid pyro-gasi f ication through the use of said equipment , as reported in the relative appended independent claim, as well as in the fol lowing descriptionand in the relative appended figures.

[0014] In particular, the object of the present invention is pyro-gasif ication reactor (1) comprising at least three chambers (10, 20, 30) in fluid communication with each other, of which: a first pyrolysis chamber (10) ; a second combustion chamber (20) ; a third post-combustion chamber (30) ;

[0015] According to the invention, said second combustion chamber comprises a further chamber inside it.

[0016] More in particular, advantageously, said second combustion chamber comprises a further chamber (20a) obtained inside it such that, as a whole, two chambers (20, 20a) are generated and of which one (20a) inside the other (20) and with eccentric arrangement.

[0017] In this way, as a whole, the second chamber has such a geometry to generate, in actual fact, two chambers (20, 20a) placed one inside each other with eccentric arrangement .

[0018] Thanks to this solution, the complete combustion of char and the complete combustion of residual ashes can be guaranteed .

[0019] Thanks to this solution the complete combustion of char and the complete fusion of residual ashes may be guaranteed. The inner cylinder prevents cold flows introduced by primary air from skimming the char and softening ashes in determined conditions. Moreover, the reversal of flow causes a high turbulence and consequently a uniform temperature which avoids peaks of temperature and increase in the surface temperature of the refractory material. Inertization of ashes occurs only if these are molten and evacuated in any operative condition and with any entering waste, which is variable and unknown per se.Therefore, the most important effects of the particular geometry are:Complete combustion of char;Inertization of ashes;Reduction of thermal NOx (nitrogen oxides) ;Less thermal solicitation of the refractory material.

[0020] Advantageously, said two chambers (20, 20a) inside one another may be with generically cylindrical shape or the like .

[0021] Advantageously, said two chambers (20, 20a) have a development with longitudinal axes parallel to each other and placed at a certain distance from each other.

[0022] Advantageously, in said chamber (20a) a hole (50) suitable for enabling molten mineral ashes produced in the combustion chamber (20) to exit is provided.

[0023] Advantageously, said hole (50) houses a collection and discharge crucible (100) suitable for collecting said molten ashes and conveying them to a collection tank.

[0024] Advantageously, at least one thermal imager in the pyrolysis chamber (10) and at least one further thermal imager in the combustion chamber (20) suitable for enabling to check processes occurring during operation are comprised.

[0025] Advantageously, a cooling system comprising cooling channels which run along at least a part of the walls (21) delimiting the most internal chamber (20a) relative to the combustion chamber (20) is comprised.

[0026] The object of the present invention is also a method to perform pyro-gasif ication at high temperature of combustible solid materials combined with inertization of ashes obtained from combustion thereof, through a pyrogasification reactor according to one or more of said features .

[0027] Advantageously, said pyro-gasif ication is performedat a temperature varying from approximately 750°C to approximately 1600°C.

[0028] Advantageously, said combustible solid materials are selected from combustible solid industrial and municipal waste .

[0029] Advantageously: in said first chamber (10) the combustible material is subject to a heating at approximately 750°C in reducing conditions producing syngas and char which are transferred into the second chamber (20) ; in said second chamber (20) syngas is brought to temperatures of approximately 1.500-1.600 °C; said temperatures enable syngas to oxidize char and to melt the obtained mineral ashes; said molten ashes are then conveyed in liquid state into the discharge crucible (100) through which they are directed to a collection tank where they solidify by becoming vitrified; in said third chamber (30) the post-combustion gases obtained in the second chamber achieve complete oxidation of possible residuals still unburnt and guarantee maintenance of a desired temperature of final fumes at approximately 1.500°C.

[0030] Advantageously: transferring syngas from the chamber (10) to the chamber (20) occurs through two ejecting outlets (22) , in which syngas is mixed with compressed air; and transferring char from the chamber (10) to the chamber (20) occurs by using a movable grate (12) .

[0031] Advantageously: the amount of combustible material to be subject to pyro-gasif ication which is charged in the pyrolysis chamber(10) is controlled and determined by using the first thermal imager positioned in said chamber (10) ; while the second thermal imager positioned in the combustion chamber (20) checks that char coming from the chamber (10) is fully oxidised and that the formed residual ashes have been melted.Brief description of the drawings

[0032] Further features and advantages of the pyrogasification equipment object of the present invention for achieving pyro-gasif ication of combustible solid materials, combined with inertization of ashes obtained therefrom, according to the invention, will become more apparent from the following description of a particularly preferred technical embodiment, given here below only by way example and in any case completely non-exhaustive for the knowledges of the specialist skilled in the field, with reference to the appended drawings, wherein:Figure 1 shows an overall section of the reactor according to the invention, which also highlights the crucible with underlying collection tank 51 and lif ting / lowering system of the collection tank through pantograph system 52; still figure 1 shows then a storage tank of vitrified ashes 52' which collects said ashes present in the tank 51 where they are transferred thanks to an auger system (52C) ;Figures from 2 to 4 show further sections still of the reactor;Figure 4-A shows a constructive detail regarding a fluid sucking system (for example gas) inside the reactor, preferably of the type with Venturi tube;Figure 5 is a further section of the reactor which highlights cooling channels which runs along the walls delimiting the second inner chamber and eccentric withrespect to the first combustion chamber ;Figure 6 shows a constructive section of the crucible ;Figure 7 shows a charging system;Figure 8 is an electromechanical scheme ;Finally figure 9 shows an evolution of flows in the combustion chamber, with the purpose of showing the relative ef fect obtained with production o f the combustion chamber in the form of two eccentric chambers ; therefore the figure outlines how the flow is forced to return back to the pyrolysis chamber, skimming the eccentric inner chamber, to then penetrate the latter ; then the same figure shows the intersection area of the gaseous j ets introduced into the combustion chamber through the openings 22 and 25 , respectively comburent ( generally air ) and syngas ; this intersection area is indicated in figure as "primary combustion area" .Finally figure 9A shows inlets of the varied flows into the reactor indicating the inlet of primary air and o f premixed syngas into the combustion chamber ; moreover, the same f igure shows suction of syngas which is formed in the chamber 10 and which is mixed with compressed air indeed to enter the combustion chamber in the form of premixed syngas .Detailed description of some preferred configurations of the invention

[0033] A particularly preferred embodiment of the equipment , that is the pyro-gasi f ication reactor 1 , of the present invention, is described in detail , together with its overall operation, respectively, in the appended figures . In its entirety, the reactor is substantially constituted by three distinct integrated combustion chambers in communication with each other .

[0034] Therefore , as one may infer from figure 1 , a first "pyrolysis-gasi fication" chamber 10 is provided ( or pyro-"gasification"; indicated from now on, for the sake of convenience, as "pyrolysis chamber", abbreviated to PC) .

[0035] Then a second "combustion chamber" 20 is provided (abbreviated to CC) .

[0036] Then a third "post-combustion chamber" 30 is provided (abbreviated to PCC) .

[0037] Said pyro-gasif ication reactor has, preferably a cylindrical or substantially cylindrical shape.

[0038] The rate of the flows of gaseous material to be subject to the pyro-gasif ication treatment has a symmetry with respect to an ideal vertical plane (with respect to the figure 1, therefore a plane orthogonal to the ground) which subdivides into two halves the reactor 1, by passing through its central axis C - C. A rate of flows is indeed shown in figure 9.

[0039] The conduction of the three chambers occurs by means of dedicated air currents for each chamber.

[0040] In the (first) pyrolysis chamber PC (10) , the solid material is subject to heating in reducing conditions (that is, with a scarce amount of oxygen) , at temperatures at approximately 750°C, preferably approximately 800°C, which divides organic material into "syngas" (or synthesis gas, that is a combustible gaseous mixture substantially H2, H2O, CO, CO2 and CJh-based, with few, very little impurities of NH3, H2S, HC1) and a carbonaceous residue (or "char", as used from now on for convenience) .

[0041] For the sake of clarity, in the present description and in the appended claim, the word "approximately" referred to the values of the reported temperatures means any possible variance of ±1-4% (preferably ± 1-2%) with respect to the value indicated for the temperature itself.

[0042] The syngas produced accordingly, preferably premixed with compressed air, is fed to the (second) combustion chamber CC (20) , through at least one specific ejectingoutlet 22 (more preferably two) , like for example indicated in figure 1, section B-B, and in figure 2. Moreover, as shown in figure 4-A the ejecting outlet is preferably fitted with a componentry of the type with Venturi Tube described below.

[0043] Therefore, the passage provided by the outlet 22 sets the two chamber 10 and 20 into communication. This communication through the ejector becomes unidirectional from the pyrolysis chamber (PC) to the combustion chamber (CC) .

[0044] In particular, therefore, the section B-B, still shown in figure 1, highlights the passage of communication between the two chamber 10 and 20 provided by the outlet 22.

[0045] Still with reference to figure 1, in its turn, the formed "char" is moved onto a suitable movement system 12, for example a movable grate 12 (for example, slidable onto two tracks with alternated movement) , and transferred into the combustion chamber CC 20.

[0046] Therefore, in the combustion chamber 20 occurs the transfer of "char" through the movement system 12 and syngas through the passage 22 (see for this purpose figure 1, section B-B, and figure 4) .

[0047] The movement system 12 is omitted in figure 4.

[0048] Therefore, figure 1 outlines a possible solution of movement system, which in a preferred embodiment, can be said movable grate 12 which can be moved in order to transfer char into the second chamber through the passage 12' .

[0049] Therefore, the passage 12' sets into communication the two chambers 10 and 20.

[0050] Therefore, the section B-B, still shown in figure 1, also highlights the passage 12' .

[0051] As described better in the following description, the section A-A allows highlighting of an important structural part of the present pyro-gasif ication reactor 1.

[0052] In particular, as still shown in figure 1, section A- A, the chamber 20 has an inner structure 21 inside it to form a sort of inner spherical cap 21, which inner structure is very well highlighted in figures 3 and 4.

[0053] Figure 3 and figure 4 are axonometric view which show a half of the pyro-gasif ication reactor and therefore show the circular wall 21 which protrudes from the wall of the chamber 20, therefore from the cylinder 20, to form an arc 21 which is still closed on the wall of the chamber 20. The section A-A of figure 1 shows very well the circular arc 21 which is closed on an arc of circumference relative to the cylinder 20.

[0054] Therefore, a further chamber (20a) , preferably with cylindroid shape as well and with elliptical section or the like, for example also cylindrical, is defined inside the chamber 20, which is preferably with circular cross-section.

[0055] Therefore, the two chambers are inside each other and not coaxial but rather out of axis, as one may well infer from figure 1 and / or 2.

[0056] Thus, this chamber (20a) is formed inside the chamber 20 and equipped with inlet and / or outlet openings.

[0057] Figure 2 is a further section which better highlights the section A-A to highlight formation of the two chambers inside each other.

[0058] As obvious from figure 2, the chamber 20 is indeed delimited by a cylindrical wall of predetermined thickness and, in figure 2, the wording "outer cylinder" is applied to the cylindrical surface of the wall facing the inside of the chamber 20.

[0059] The wording "inner cylinder" is applied to the surface of the wall delimiting the inner chamber (20a) and facing the surface defined "outer cylinder".

[0060] Moreover, figure 2 outlines some openings which are also highlighted in figure 4.

[0061] In particular, the passage opening 25, the passage opening 29 shown in figure 3 and the passage 22 introduced above are shown.

[0062] Moreover, with reference to figures 2, 3 and 4 a further through-opening 50 is highlighted which is needed to allow exit of the molten ashes which fall into the collection crucible 100 (shown isolated in figure 6 and shown assembled in figure 1) .

[0063] The crucible 100 is inserted into the opening 50 as one may see in figure 1. Figure 1 also shows the collection tank 51 of vitrified ashes which is raised by a pantograph system 52, and an extraction auger is also visible the section C-C.

[0064] The refore, the tank 51 is placed below the reactor to collect the molten ashes. The crucible 100 is actually part of the outer cylinder.

[0065] High temperatures (> 1.500°C, up to a maximum of approximately 1600°C) which are reached in the combustion chamber 20 allow oxidation of char and fluidification (that is, melt) the obtained mineral ashes which are then conveyed in liquid state into said discharge crucible 100 from which they are sent into a collection tank in which they become vitrified, as a result of the quick cooling.

[0066] The post-combustion air is introduced in the (third) post-combustion chamber 30 in such a way as to increase the percentage of oxygen thus guaranteeing complete oxidation of all unburnt elements and maintenance of a temperature of the final fumes of approximately 1.500°C, before they enter a recovery boiler (not indicated in the appended figures) , whose purpose is to perform thermal recovery of hot gas (that is, fumes) exiting from the reactor. The final fumes exiting from the boiler pass through an air-fumes exchanger with the purpose of pre-heating air sent into the pyrogasification reactor.

[0067] At a later time, the exhaust fumes, at a temperature of approximately 160°C, enter a final washing section (for example a sleeve filter, a catalyst, and so on) and then they are sucked by a forced draught fan and evacuated into the chimney.

[0068] Moreover, the pyro-gasif ication reactor described above in its essential parts is equipped with one or more control thermal imagers (not highlighted in figure for the sake of simplicity) .

[0069] For example, a first thermal imager can be positioned into the pyrolysis chamber 10 and a second thermal imager can be positioned in the combustion chamber 20.

[0070] These thermal imagers have the purpose of helping the optimal working management of the aforesaid pyrolysis chamber and combustion chamber, respectively.

[0071] The thermal imagers acquire images that are processed by a SW (Vision Assistant and Labview by National Instrument) . The thermal imager in the pyrolysis chamber (PC) works in the near infrared while the thermal imager in the combustion chamber (CC) works in the medium infrared in order to see through the flame.

[0072] Therefore, thanks to the thermal imagers, the operator can manage better the process.

[0073] Moreover, the pyro-gasif ication reactor is also equipped with a suitable system of measurement and / or control means which allows adequate registration and adjustment of operational parameters, such as: the values of the temperatures in the three communicating chambers of the pyro-gasif ication reactor described above, the values of the pressure in said three chambers; the concentration of oxygen in the combustion chamber 20 and upon exit from the recovery boiler of the reactor, - the various flow rates of gaseous flows and thetemperatures of air ( compressed or not ) introduced into the various chambers , the process calculator analyzes the live images acquired by the thermal imager which frames the pyrolysis chamber by pointing at the area where the separation wall with the combustion chamber is placed and obtains a signal ( LT101 ) which measures the percentage amount of filling in order to check this level ;Moreover, also an analysis of the images occurs to obtain the level of char which is collected in the combustion chamber . The main tas k of the thermal imager in the combustion chamber is to veri fy i f the material pushed by the movable grates towards the combustion chamber i s adequately consumed without accumulating in the combustion chamber .

[0074] As briefly anticipated and explained in detail below, the aforesaid thermal imagers allow an optimal and innovative management o f the movement of the movable grate together with the control and management of the flow rate of the treated material . Indeed, the thermal imager placed in the pyrolysis chamber 10 controls the amount of material present in said chamber, while the thermal imager placed in the combustion chamber 20 controls that the residual char coming from the pyrolysis chamber 10 is completely oxidi zed and that formed residual ashes are melted to then be sent correctly towards the evacuation crucible, in liquid state .

[0075] The images are acquired and are shown to an operator who decides , in case , to vary operational parameters . The images may be also analyzed through SW and an alarm may be generated .

[0076] In a particularly preferred embodiment of the invention, the outer si zes of the present embodiment ( that is , the reactor with three chambers communicating with eachother) have been studied in such a way as to maintain it compact and readily transportable with volume, only by way of non-limiting example, of approximately 6.000 x 2.500 x 2.800 (H) mm. In this case, the maximum amount of treatable material is approximately 1.500 kg / h, with a production of hot fumes at 1.500°C upon exit, up to approximately 13.000 Kg / h .

[0077] However, nothing, obviously, prevents the dimensions and geometry thereof from being varied, possibly also only / at least partially, by the technical designer on the basis of the present description and depending on particular productive and / or environmental needs, without thereby departing from the scope of protection of the present invention .

[0078] In addition to the aforesaid compactness and ease of transport (which can be achieved without the need to use special means / transport s ) the engineering of the plant and their small sizes allows its placement to close production cycles of companies thus achieving the 0 km energy supply chain with great advantages for environment and for the user .

[0079] Indeed, with integration into industrial production processes, the transports of processing waste towards disposal plants of third parties are eliminated with important benefits in terms of emissions and reduction of costs which the companies must bear to manage their waste.

[0080] Other important intrinsic features of the plant are modularity and scalability: the capacity of the plant may be increased by adding modular lines (for example, 1 line for 10.000 tons - 3 lines for 30.000 tons treatment) in such a way to allow the user to achieve energy self-sufficiency.

[0081] In an embodiment, the entry of primary air into the combustion chamber 20 is achieved, for example, through two double-flow burners (not indicated in figure) both capableof supporting combustion with a methane flame (primary flow) and of providing air necessary for combustion of syngas (secondary flow, coaxial to the primary flow) .

[0082] Actually, it is a burner with double damper for adjusting air. One damper adjusts the primary combustion air, while the other damper adjusts a second air flow which is not directed to the burner head and which is usually needed to dilute gas produced by the flame, thus decreasing its temperature. In the case in question, in particular, the second flow is necessary as primary combustion air for syngas and char. The second flow bypasses the burner head and is sent outside onto a pipe coaxial to the pipe which contains the burner flame.

[0083] As outlined in the detail of the appended figure 4-A, in an embodiment, the transport of syngas occurs preferably by using Venturi principle with two branches 22' equipped with convergent nozzles inserted into conduits communicating with the pyrolysis chamber 10 and the combustion chamber 20. The position of the nozzle (made by a seal packing system on outer flange) is shifted to vary and optimize the flow rate of syngas and the flow rate of air, preferably compressed, used in the branches, is suitably varied.

[0084] The sucked syngas maintains the pressure in the pyrolysis chamber 10 and at lower pressure than that of the combustion chamber 20, thus facilitating inner recirculation of hot gas from the combustion chamber 20 to the pyrolysis chamber 10.

[0085] Recirculation is also guaranteed by the two circular openings placed below the sides of the opening 12' in the section B-B.

[0086] As described in the appended figures (see in particular figure 1) , the combustion chamber 20 contains a crucible 100 intended to collect the formed fluid ashes(that is, molten) which thus flow from the combustion chamber 20 to a collection (and cooling) tank containing water; therefore, fluid molten ashes fall into water, where become vitrified by solidifying. From here, for example, through an auger system or other functionally similar system, the extraction of vitrified solid parts (in other words, former molten solidified and vitrified ashes) is performed continuously by directing them towards a discharge box .

[0087] The whole system can be moved to perform maintenance and / or replacement of the crucible, or of parts thereof, for example, by means of an elevator platform. In the present embodiment, the whole system is secured in working position through pneumatic clamps, for example two clamps. Fluid waste fall through a filter in refractory material and a disk holed in the middle and, through a series of blowers which make the flow "flicker", it is reduced to small spheres before arriving at the cooling tank full of water .

[0088] The crucible is made up of various elements as shown in the following appended figure 5 and directly indicated in said figure.

[0089] The filter prevents any solid particles that have not yet been melted from falling into the crucible and blocking the passage of molten ashes. The holed disk, made of a material resistant to abrasion, for example silicon carbide, allows discharge of molten material.

[0090] In order to maintain the disk sufficiently hot, a portion of hot fumes is sucked by the combustion chamber 20. Said sucked fumes, together with air used to break the jet of molten ashes and together with the vapour of the present water evaporated because of heat, are then sucked again, and reintroduced into the combustion chamber 20.

[0091] The system of movable grates for moving char obtainedby pyro-gasi f ication in reducing environment from the pyrolysis chamber to the combustion chamber 10 may be of those already known .

[0092] In particular, said system may be formed by two movable planes equipped with alternate motion which let said material flow from a chamber to the other one in a controlled way (by modulating the frequence thereof , one controls the speed of the activating crank gear ) . The grates , provided as replacement components (both in the event of fault and wear) , are connected with an extraction system to be safely positioned, removed and replaced .

[0093] Figure 6 shows in detail the conduit for inletting the material to be subj ect to the treatment in the pyrolysis chamber 10 . The conduit (not shown in detail in figures 1 and 2 for the sake of simplicity) is interposed between the feeding and pushing unit of the material (not shown) and the combustor ( that is , the pyrolysis and gasi f ication chamber ) . Its function is to trans fer the compacted waste by limiting the air inlet to the maximum, given the need to operate in a reducing environment .

[0094] To let the waste material move forward ef ficiently, frictions must be necessarily reduced to the minimum; for this purpose , preferably, the conduit is heated outside by means of a series of electrical resistances .

[0095] A certain pre-heating of the waste material itsel f , which can reach for example an average temperature of approximately 95 ° C, is also obtained upon heating the surface of the conduit, in addition to the reduction of friction . This actually makes the conduit itsel f an integrating part of the pyrolysis section ( and of the relative proces s ) of the material to be treated and it may be considered like a "pre-chamber of pyrolysis" .

[0096] When necessary, also the conduit inletting material must be able to be replaced quickly without letting therefractory material of the pyrolysis chamber 10 cool , therefore it must be able to be moved ( for example , disconnected) and / or readily connected to the charge inlet of the chamber .

[0097] The desired volumetric combustion in the combustion chamber 20 is achieved through a particular 3D ( three- dimensional ) geometry of the combustion chamber 20 which maximi zes the volume with a high reaction speed .

[0098] The aforesaid geometry of the combustion chamber 20 is indeed made up of two eccentric cylinders with parallel axes , an inner one and an outer one , as already introduced at the beginning of the description .

[0099] Actually, the inner chamber is not exactly cylindrical , but it is similar in shape to it , thereby having two (more or less ) eccentric cylindroid elements and with parallel axes .

[0100] The volumetric combustion above is obtained by suitably applying and adj usting the following functional precautions : the so-called " staged combusti on" , in which the syngas flow ( sucked by the chamber PC, in which it has been produced) is premixed with compressed air, already enabling a first partial oxidation in the same transport channel o f syngas from the chamber 10 to the chamber 20 ; moreover, the cooling air of the inner cylinder ( substantially, a fraction of the primary air ) is inlet into the central area of the chamber 20 in such a way as to allow complete combustion of gas and providing oxygen suf ficient for the combustion of char .In detail , most part of the primary air is inlet through the lateral openings which are necessary to preheat the chamber with the burners . This fraction of the primary air intersects syngas transported by the compressed air, while the second fraction deriving from the cooling air of theinner cylinder is inlet into the area opposite the residual char ; the crossing point of the flows of syngas (premixed with compressed air which is necessary for the ej ector which sucks syngas from the pyrolysis chamber 10 ) and of the primary air which is arranged in the central area opposite the separation wall between the combustion chamber 20 and the post-combustion chamber 30 , which acts as di f fuser head thus distributing the reaction into the whole area opposite said separation wall ; thus , the gas radiates from the crossing point outwards , with change of flow direction; therefore , the hot , partially burnt , gas returns behind towards the other wall which separates the combustion chamber 20 from the pyrolysis chamber 10 , to then descend to access the exit passage from the 20 formed by its inner cylinder ; this fact causes great turbulence and speed of the gaseous flows ( in other words , the so-called fumes ) directed towards the surface of char, to guarantee its sol id combustion; the entry of the aforesaid fumes at the maximum temperature into said inner cylinder of the chamber 20 , in which the fumes skim ashes thus facilitating their fluidi fication ( that is , fusion) and the relative evacuation through the crucible ; in addition, the evacuation of molten ashes is facilitated by the inclination of the cylinder, as one may clearly see in figure 1 .

[0101] According to the rate of the gas flow in the combustion chamber 20 , the flow is forced to return in the opposite direction to then descend towards the exit channel delimited by it by its inner cylinder .

[0102] Moreover, the appended figure 5 shows the channels travel led by cooling air of the structure of the aforesaid inner cylinder of the combustion chamber 20 , as well as thechannels for inletting secondary air into the postcombustion chamber 30, in which the aforesaid channels inletting secondary air cool the so-called diverting wall. This fact favors condensation / interception of residual particles of flying ashes, which are then held. The residual part of ashes deposited accordingly then flows downwards returning towards the evacuation crucible.

[0103] On the contrary, the cooling air of the inner cylinder mainly enriches with oxygen the combustion area of char, thus improving its transformation into a fluid, molten residual part.

[0104] The refore, inletting air is progressive and occurs overall in the following steps and areas:1. Gasification air, which is inlet into the portion below the grate of the pyrolysis chamber PC (not shown in detail in the figures) :2. Transport air of the syngas from PC to CC;3. Primary combustion air of gas (syngas mixed with air) :4. Primary combustion and cooling air of char5. Secondary air.

[0105] The average temperature of gases inside the combustion chamber CC increases progressively from the combustion area of syngas (approximately 1.450°C) until the combustion area of char (approximately 1.500°C) , until the melting area of ashes obtained by char (approximately 1.550- 1.600°C) , in which gases (fumes) are at the maximum temperature, with a sufficiently homogeneous distribution. The separation partition, constituted by the inner cylinder, between the combustion area of syngas and the melting area of ashes, guarantees that the relatively cold flows do not circulate near the evacuation crucible of molten ashes.

[0106] In addition, the combustion of solid char isguaranteed by high temperature and speed of the fumes ( as already described before ) together with the average excess of oxygen in the area ( substantially provided by the added primary air) ; actually, the average percentage in volume of oxygen of gases in the CC varies from a minimum of 2 % v / v up to a maximum of 4 % v / v . The area around char is also enriched with the seeping of the gasi fication air which also seeps by the under-grate portion ( the movable planes ) towards the combustion chamber CC .

[0107] Two thermal imagers are used to control the level of material present in the pyrolysis chamber 10 and in the combustion chamber 20 , one placed in the chamber 10 and one placed in the chamber 20 .

[0108] The main task of the pyrolysis thermal imager is to control i f the pile of material charged in the chamber 10 is as high as required to keep the connection conduit with the combustion chamber 20 . The recognition of the pile level is based on a software for the analysis of images . The process calculator of the plant analyzes " live" images collected by the thermal imager which frames the pyrolys is chamber 10 ( see the box LT101 in the diagram of the appended figure 8 ) , by pointing at the area where the wall separating the combustion chamber 20 is positioned and obtains the signal which measures the percentage amount of filling of solid materials (biomasses and / or waste ) in order to check the charging speed of waste into the combustor ( i f necessary, by suitably modi fying it ) .

[0109] To measure the amount of material present in the chamber 10 , which is provided real-time for the purposes of any immediate adj ustment of it , the following correspondence is assumed :Chamber empty of waste = 0% ( fully open passage between the two chambers PC and CC )Chamber full of waste = 100% ( fully closed passagebetween the two chambers PC and CC ) .

[0110] The main task of the thermal imager placed in the combustion chamber CC is to check whether the material pushed by the movable grates into the chamber CC is suitably consumed without being piled into said chamber CC . This result is obtained by adj usting the speed of the movable grates as a function of the necessary stay time in the pyrolysis chamber PC, to obtain the correct amount of solid material devolatili zed as much as possible ( in other words , without syngas and in the form of carbonaceous residual material ( char ) and ashes ) in inlet to the combustion chamber CC .

[0111] In summary, to control the pile level of the waste materials in the pyrolysis chamber PC, one may act on the following manipulable variables :Inlet speed, or flow rate , of entering waste ;Speed, or frequency, of the grates which is correlated with the flow rate of material exiting the pyrolysis chamber PC ;Temperature of the pyrolysis chamber PC, which is function of the air amount ( exothermic reaction) and of the hot gas inlet into it ;Pressure of the pyrolysis chamber PC which adj usts the amount of recirculated hot gas and, therefore , inlet again into the PC itsel f .

[0112] On the contrary, chemical and physical properties of the materials themselves , which vary depending on the type of material which one wants to treat , must be cited as unmanipulable variables which may influence the aforesaid pile level of waste materials .

[0113] The control of the pile level of waste material directly influences the amount of material treated by thepyro-gasif ier and, consequently, the exiting thermal power. The basic objective of the regulation is to be able to achieve the objective value of the desired power as much as possible, which is indirectly measured through the measurement of the vapour flow rate produced in the recovery boiler (not shown in the figures) , where the thermal recovery of hot gas exiting from the reactor occurs. Downstream of the reactor, the fumes cross the aforesaid recovery boiler where vapour is produced. In summary, the control of the pile level is based on a so-called primary regulation, based on the speed of inlet and discharge of the material present in the chamber PC, and on a so-called, more slow, secondary adjustment, based on the temperature of the chamber PC itself.Primary adjustment

[0114] The primary adjustment provides manual, or semiautomatic, adjustment of the grate speed and an automatic and continuous adjustment of the inlet speed of waste material to be treated into the chamber PC. The grate speed may vary between a minimum value and a maximum value (for example, from a minimum of 3 RPM to a maximum of 12 RPM - revolution per minute) ) and within this interval a thinner adjustment occurs on the basis of indications deriving from the thermal imager placed in the chamber CC . If the material (char) transferred into the chamber CC tends to accumulate, then the transfer speed of it must be decreased, otherwise the speed must tend to the maximum value set.

[0115] The thermal power of the plant is defined as the product of LCV (lower calorific value) of the material x the flow rate of material. Given that LCV varies at every moment and is never known, the power must be estimated through measurements of gaseous flows entering and exitingthe recovery boiler (for example, by means of flowmeters, or thermometers, or pressure meters) and an airfumes exchanger, which is placed upstream of said boiler and is necessary to pre-heat air of the three chambers, as already mentioned above.

[0116] The power of the plant is limited by any emission of pollutants. In particular, by way of non-limiting example the concentration of residual HC1 is measured in the exiting fumes (as well as the one of any possible pollutants) and correspondingly the amount of reagents necessary to reduce it / them which must be inlet into the treatment section of fumes placed downstream of the air-fumes exchanger. If the amount of reagents is maximum once HC1 exceeds a certain alert threshold, then the power of the plant is decreased.

[0117] Without describing in detail the adjustments of plants upstream and downstream of the pyro-gasif ication reactor (that is, the reactor complete with the three chambers) , as well as all necessary safety mechanisms, the adjustment logic of the pile in the chamber PC may be summarized through the diagram of the appended figure 8.

[0118] Substantially, the measurement of the pile level is performed through the first thermal imager (box LT-101) . For a high level, the inlet speed of material must be decreased, while it must be increased for a low level (box LIC-101) . A constant increase in speed is added to this adjustment action so that the system responds more quickly in the event of low level (box SY-101 A) . In its turn (box SY-101 B) the flow rate of vapour (box FT-601) set as "set" on (box FIC-601) is not exceeded. The vapour flow rate is directly proportional to the thermal power supplied by the pyro-gasif ication complete with all the three chambers.

[0119] The set to be set depends on the operative modalities of the software recognizing the images of the thermal imager of the chamber PC. Since the passage between the chambersmust remain closed as much as possible, in order to avoid an excessive recirculation of hot gas from the chamber CC to the chamber PC, the set is set at 100%.

[0120] In addition, the control software processes and also provides an over-fill signal of the waste pile in the chamber PC which, when necessary, fully interrupts feeding of said material. Feeding is reactivated as soon as the level signal (box LT-101) drops below 100%.Secondary adjustment

[0121] The secondary adjustment has the task of adjusting the temperature in the chamber PC in such a way that it maximizes the flow rate of waste material which can be processed in the chamber PC itself, given that the temperature is the only manipulable variable capable of affecting the stay time of the material in the chamber.

[0122] To adjust the temperature within the normal operational range of the chamber PC, approximately comprised from 700 °C to 900 °C, one must intervene by adjusting the pressure difference between the pyrolysis chamber PC and the combustion chamber CC and of the flow rate of comburent gas (usually, but not necessarily, the comburent gas is air; however, for example, oxy-combustion might also be partially implemented which provides oxygen in place of air or a mixture of nitrogen and oxygen with different ratio from air. Oxy-combustion would reduce produced Nox and would also greatly reduce the flow rate of fumes being equal the power with consequent relative ease of CO2 capture and, in addition, the temperature in the CC would be easily maintained also in the event of material with low LCW without the use of auxiliary methane) . The pressure in the chamber PC may vary between -3 and -6 mbar, while the comburent air flow rate in it may vary between 300 kg / h up to 1.200 kg / h.

[0123] The pressure in the chamber PC is adj usted by acting on the flow rate of compressed air inlet into the ej ector used for the transport of syngas .

[0124] In its turn, the pressure in the combustion chamber CC is adj usted by acting of the number of revolutions of the sucking fan (not shown in the figures ) . The pressure in the combustion chamber CC must remain within the interval comprised from -2 and -3 mbar . The maximum depression of the chamber PC with respect to the chamber CC is -4 mbar and the minimum depression is 0 . When the depression is maximum, the maximum flow rate of hot gas which recirculates from the chamber CC to the chamber PC occurs , and, therefore , the temperature in the chamber PC tends to increase , while when the depression zeroes , then consequently also recirculation zeroes and, consequently, the temperature in the chamber PC decreases .Summary of the features and advantages of the technology of the present invention

[0125] The present technology allowed achieving direct and complete oxidation of products generated by pyrolysis and gasi fication processes in the PC pyrolysis and gasi fication chamber, ( syngas , char and, possibly, also a portion o f tar ) . Syngas , char and any tar are burnt as they are, without any preventive treatment, inside the pyro-gasi f ication unit with integrated combustion of the present invention, in which the pyro-gasi f ication process , combination of pyrolysis and gasi fication, of the present invention is achieved . In particular, said complete combustion occurs substantially in the previously described combustion chamber CC .

[0126] Inside the pyro-gasi f ication unit with integrated combustion, there are :A very low amount of air ( that is , oxygen) , used inthe pyrolysis chamber (equal to approximately 0,1%, up to a maximum of 10% of the stoichiometric amount) to provide the necessary reducing environment;Operational temperatures comprised approximately between 700 and 800°C un the step of pyro-gasif ication (that is, in the chamber PC) and from 1.500 to 1.600 °C in the combustion step (that is, in the chamber CC) ;A solid step constituted by pyro-gasif ication char (possibly, also a lower amount of tar) in the chamber PC, which is oxidized and transformed into molted ashes in the chamber CC (subsequently vitrified in the collection tank exiting from the crucible of the chamber CC) .

[0127] The concept of pyro-gasif ication is based on reactions that occur in a balanced combination between pyrolysis and gasification processes. Syngas produced in the pyrolysis chamber PC at approximately 700-800 °C, has a high-power content, which allows reaching high temperatures in the subsequent combustion chamber CC, in which syngas is burnt in conditions of high turbulence and homogeneity of the reaction environment. Average temperatures comprised between 1.500°C and maximum 1.600°C are indeed reached in the combustion chamber.

[0128] In addition, high temperatures reached in the combustion chamber CC allow melting and vitrification of slags (ashes) produced in the PC and complete oxidation of any organic compounds still present, besides guaranteeing maintenance of operational conditions in the chamber PC at temperatures in the order of 700-800°C.

[0129] As indeed described above, in this chamber PC, temperatures are also supported by recirculation of hot fumes coming from the chamber CC, whose power supply contributes to the devolatilization process of the entering waste material. The pyrolysis and gasification process inthe pyrolysis chamber PC produces water gas and air gas. Both contribute to the formation of syngas and therefore both are burnt in the subsequent combustion chamber CC . The production of air gas is a chemical process which occurs by bringing in contact an air current with the hot coal (char) in an environment characterized by the lack of oxygen. This process is exothermic, that is a reaction which produces heat. The production of water gas is a chemical transformation process obtained by bringing into contact the water vapour with hot coal (char) . This reaction, differently from the previous one, is endothermic, i.e. it absorbs heat.

[0130] Advantageously, the hot power of syngas formed in the pyrolysis chamber PC allows reaching high temperatures in the combustion chamber CC with important benefits in terms of environmental impact, such as vitrification of residual materials (molten ashes) and destruction of dangerous organic species (for example, organic micropollutants) .

[0131] Advantageously, therefore, a feature of the present technology consists of simplicity of creating and transferring mixed gas (syngas) from the chamber PC to the Chamber CC without pre-treatments, maximizing power recovery obtained with its combustion at the same time.

[0132] The transfer of mixed gas from the pyrolysis chamber PC to the combustion chamber CC occurs through a path separated from the one with which combustible solid material (char and any residuals of tar) is transferred to the chamber CC . Any residual of tar (TAR) , since pyrogasification temperature is quite hot, is mainly in the vapour step in syngas itself. The integrated combustion avoids cooling syngas and therefore letting TAR condense.

[0133] Advantageously, transferring char from the pyrolysis chamber PC to the combustion chamber CC separately from syngas, guarantees complete combustion of said solidmaterial at a very high temperature (1.500-1.600 °C) without the need of insufflating air and with consequent relevant results in terms of environmental impact: that is, as already mentioned above, destruction of any dangerous complex organic molecules and complete vitrification of residual elements (molten ashes) , which can then be recovered subsequently like inert materials (for example, in the form of small spheres) useful for producing other precious secondary raw material.

[0134] In other words, advantageously, the pyro-gasif ication unit with integrated combustion of the present invention, substantially constituted by the three chambers (PC, pyrolysis and gasification; CC, combustion; and PCC, postcombustion) communicating and integrated in the same unit, breaks up the combustion process of solid waste into its elementary steps, thus enabling their autonomous management and control, thus obtaining important benefits in terms of performance, operating and environmental costs which go from the combustion in the gas step of syngas, to the containment of air amounts used throughout the process, in addition to the ones already mentioned above.Industrial applicability

[0135] The equipment of the present invention to perform thermal treatment at high temperature of combustible solid waste material, together with inertization of ashes obtained therefrom, and the relative process, enabled, thanks to the pyro-gasif ication unit with integrated combustion constituted by the three chambers described in the present description and in the relative appended claims, a breakdown of the combustion process of solids in its elementary phases, managing and controlling them in an autonomous way and thus obtaining important benefits in terms of performance, working and environmental costs.

Claims

CLAIMS1. A pyro-gasif ication reactor (1) , comprising at least three chambers (10, 20, 30) in communication with each other, of which: a first pyrolysis chamber (10) ; a second combustion chamber (20, 20a) ; a third post-combustion chamber (30) ; characterized by the fact that said second combustion chamber comprises a further chamber (20a) obtained inside it such that two chambers (20, 20a) are generated one (20a) inside the other (20) and with eccentric arrangement.

2. The reactor, according to claim 1, wherein said two chambers inside one another are with generically cylindrical shape or the like.

3. The reactor, according to claim 1 or 2, wherein said two chambers (20, 20a) have a development with longitudinal axes parallel to each other and placed at a certain distance from each other.

4. The reactor, according to one or more of the previous claims, providing in said chamber (20a) a hole (50) suitable for enabling molten mineral ashes produced in the combustion chamber (20) to exit.

5. The reactor, according to claim 4, wherein said hole(50) houses a collection and discharge crucible (100) suitable for collecting said molten ashes and conveying them to a collection tank.

6. The reactor, according to any one of the previous claims, comprising at least one thermal imager in the pyrolysis chamber (10) and at least one further thermal imager in the combustion chamber (20) suitable for enabling to check processes occurring during operation .

7. The reactor, according to one or more of the previous claims, comprising a cooling system comprising cooling channels which run along at least a part of the walls (21) delimiting the most internal chamber (20a) relative to the combustion chamber (20) .

8. A method for performing pyro-gasif ication at high temperature of combustible solid materials combined with inertization of ashes obtained by combustion thereof, by means of a pyro-gasif ication reactor according to any one of the previous claims; preferably said pyro-gasif ication is performed at a temperature varying from approximately 750°C to approximately 1600°C and / or in which said combustible solid materials are selected from combustible solid industrial and municipal waste.

9. The method, according to one or more of the previous claims, wherein: in said first chamber (10) the combustible material is subject to a heating at approximately 750°C in reducing conditions producing syngas and char which are transferred into the second chamber (20) ; in said second chamber (20) syngas is brought to temperatures of approximately 1.500-1.600 °C; said temperatures enable syngas to oxidize char and to melt the obtained mineral ashes; said molten ashes are thenconveyed in liquid state into the discharge crucible (100) through which they are directed to a collection tank where they solidify by becoming vitrified; in said third chamber (30) the post-combustion gases obtained in the second chamber achieves complete oxidation of possible residuals still unburnt and guarantee maintenance of a desired temperature of final fumes at approximately 1.500°C.

10. The method, according to one or more of the previous claims, wherein: transferring syngas from the chamber (10) to the chamber (20) occurs through two ejecting outlets (22) , in which syngas is mixed with compressed air; and transferring char from the chamber (10) to the chamber (20) occurs by using a movable grate (12) .

11. The method according to one or more of the previous claims, wherein: the amount of combustible material to be subject to pyro-gasif ication which is charged in the pyrolysis chamber (10) is controlled and determined by using the first thermal imager positioned in said chamber (10) ; while the second thermal imager positioned in the combustion chamber (20) checks that char coming from the chamber (10) is fully oxidised and that the formed residual ashes are melted.

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