Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
  • H05H1/00—Generating plasma; Handling plasma
  • H05H1/24—Generating plasma
  • H05H1/26—Plasma torches
  • H05H1/32—Plasma torches using an arc
  • H05H1/42—Plasma torches using an arc with provisions for introducing materials into the plasma, e.g. powder or liquid
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
  • F23G5/00—Incineration of waste; Incinerator constructions; Details, accessories or control therefor
  • F23G5/08—Incineration of waste; Incinerator constructions; Details, accessories or control therefor having supplementary heating
  • F23G5/085—High-temperature heating means, e.g. plasma, for partly melting the waste
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
  • F23G2204/00—Supplementary heating arrangements
  • F23G2204/20—Supplementary heating arrangements using electric energy
  • F23G2204/201—Plasma
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
  • F23G2209/00—Specific waste
  • F23G2209/10—Liquid waste
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
  • F23G2209/00—Specific waste
  • F23G2209/12—Sludge, slurries or mixtures of liquids

Definitions

• the present invention relates to the field of liquid injection systems in the plasma torch stinger.
• liquids to be converted in a torch are examples of bio-oils, or sludge treatment plant, or "slurry" or particles resulting from the spraying of a solid, these particles being mixed with a liquid for injection into the stinger of a plasma torch.
• the bio-oil In the case of the bio-oil, this is obtained by flash pyrolysis, which is a thermochemical process (at a temperature T ⁇ 500 ° C.) in which the biomass is heated rapidly under a stoichiometric oxygen deficiency. Under the influence of heat, the biomass decomposes and leads to the formation of permanent gases, condensable vapors, aerosols and carbon residues. After cooling and condensation of volatile compounds and aerosols, one typically gets a dark brown liquid, the bio-oil. This is then gasified by injection into a plasma torch.
• Pretreatment of the bio-oil makes it possible to inject biomass into a plasma torch stinger to gasify it. Indeed the biomass would be, without this pretreatment step, heterogeneous, difficult to disperse (at least without expensive preliminary grinding) and difficult to inject under pressure because solid. Furthermore, in terms of the cost of transporting biomass to the gasification plants, flash pyrolysis pre-processing can be advantageous.
• a good balance is sought between the various parameters influencing the reaction, in particular the residence time of the liquid in the plasma dart, the plasma dard temperature, the exchange surface between the reagent and the plasma medium and the composition of the medium.
• the plasma dart resulting from a plasma torch has as its main characteristics a high temperature (from 5000 to 7000 K), a high flow rate (800 to 1200 m.s s -1 ) and a high viscosity. With such characteristics, the particles that we try to introduce into the heart of the dart tend to bounce on the latter.
• a first family includes injection methods based on the prior nebulization of the liquid before injection into the plasma dart.
• This type of solution favors the exchange surface between the reagent and the plasma medium, as in patent FR 2,565,992.
• the implementation of this process is carried out by means of a device making it possible to introduce the pulverized material in such a way that concentric around the hot gas flow using a carrier gas. It is conferred on plasma gas a rotary motion in the plasma generator for turbulence in the concentric flow spray material, wherein the hot gas stream warms the mixture.
• a second family concerns injection methods based on mixing forcing.
• the plasma can pass through a channel pierced with injection holes thus forcing the injected liquid to enter the plasma dart.
• Various documents evoke this technique for example the documents FR 1 509 436 or US 5 906 757.
• the plasma jet is forced to circulate in a tube provided with an increase in diameter, thereby creating a relaxation of the plasma jet in the growth zone and therefore a turbulence zone in the plasma.
• the liquid is injected into this zone and forms an annular annular ring or cylinder around the plasma dart.
• the plasma is circulated in a tube provided with at least one radially disposed injector, which makes it possible to inject the liquid with a tangential component in the plasma.
• This type of solution favors the residence time because the liquid is injected at the periphery of the plasma dart, where the flow velocity of the plasma is lower (of the order of 100 m / s compared to the speed at the heart of the dart which can exceed 500m / s.) Nevertheless this solution generates energy losses due to heat transfer with the walls of the channel. In addition, this solution does not force the liquid to penetrate deep into the plasma plume, not making it possible to benefit from the temperature effect or the reactive species constituting the heart of the plasma plume.
• a third family includes injection methods using several plasma torches.
• An embodiment of this method is mentioned in document CA 2 205 578.
• the principle of this method is to trap a jet of reagent in a confluence of at least two plasma jets, the confluence point of the plasma jets lying on the injection axis of the reagent.
• This type of solution allows the injection of the liquid directly in the depth of the plasma dart. In this case it is the temperature that is favored because takes advantage of the high temperatures prevailing at the heart of the plasma dart.
• a last family includes injection methods using an intermediate piece located in the plasma torch.
• a device for shaping this hot gas flow is placed on the path of the hot gas flow and the fluid material is brought to a nozzle, thus creating a flow of fluid material whose direction is similar to the direction of the hot gas flow, as described in patent FR 2,614,751.
• the fluid is injected directly into the heart of the hot gas flow, the particles to be converted thus being trapped in the hot gas flow. given the high viscosity of it.
• This method makes it possible to benefit from the temperature and the residence time in the plasma dart thanks to the possibility of counter-current injection of the plasma flow.
• the part must be cooled for its mechanical resistance because of high temperatures (causing thermal losses), cooling and also disturbing the plasma. In addition risks of clogging can occur in the starting or stopping phases due to the temperature level at the nozzle.
• the injectors of the same group of injectors Gi may be placed around the periphery of the plasma flow zone, with an angular spacing of 360 ° / (nl) relative to each other. They are preferably arranged so as to achieve a confluence of the jets of liquid that they inject into the plasma. They are not in direct contact with the stinger or with a plasma flow area.
• At least one injector may comprise a helical inner profile, so as to communicate to the fluid a component of rotational movement that can promote the dispersion of the liquid impact at the heart of the plasma dart.
• At least one injector may comprise piezoelectric means for splitting the injected liquid.
• a device according to the invention may comprise N groups of injectors (N> 1) arranged along of the plasma flow axis, injectors of different groups of injectors having angles of incidence different from the axis of flow of the plasma. This arrangement allows a better distribution in the plasma of the liquid charge to be treated.
• the further a group of injectors is away from the base of the plasma dart, the lower its angle of incidence relative to the axis of flow of the plasma is low.
• a device according to the invention may furthermore comprise means for injecting, in at least a portion of the injectors, trains of pulsed liquid jets or liquid jets, for example at oscillating pressure (variable as a function of time).
• one or more of the injectors each further comprises a steam injection nozzle for injecting a jet of steam simultaneously with the jet of liquid.
• a device according to the invention may further comprise means for pressurizing the liquid charge to be converted.
• the pressure of certain jets can be modified so that, in particular in certain configurations of the jets, it is possible to adjust the injection angle of the jets whose accuracy is modified.
• Means for preparing an injection liquid may further comprise means for spray the aqueous phase before it is injected.
• a device according to the invention may furthermore comprise optical means for controlling the injection quality and possibly adapting the injection parameters of the liquid charge to be converted to changes in the plasma dart.
• means can be provided to adapt the injection of the liquid feedstock to be converted to changes in the plasma dart.
• the n injectors of the same group of injectors may be arranged around the plasma flow area, with an angular difference of 360 ° / n relative to each other. They are preferably arranged so as to achieve a confluence of the jets of liquid that they inject into the plasma.
• a device and a method according to the invention are particularly applicable to a liquid of the bio-oil type, or to a sludge of purification plant, or to a mixture of solid particles and a liquid.
• Part of the heat released by the plasma can be recovered by the injector support and then transferred, by conduction, to the liquid passing in the injectors. It is advantageous to inject, in at least a portion of the injectors, pulsed liquid jet trains or liquid jets, for example whose injection pressure varies periodically.
• a jet of steam is injected into at least a portion of the liquid jets, a jet of steam simultaneously with the jet of liquid.
• the liquid can be separated beforehand between a first portion, vaporizable at relatively low temperature (of the order of about 80 to 150 ° C.) and a second, heavier part, to be injected into the plasma in liquid form.
• An addition of water in the liquid to be injected can also be performed, in order to optimize the conversion reaction of the liquid to be treated.
• a vapor layer is formed outside the plasma dart.
• the jets of liquid of the n injectors of the same group of injectors are preferably confluent in the plasma, the zone of confluence of the jets being advantageously located substantially on the plasma flow axis.
• the angle of injection of at least one jet into the plasma can be modified, for example by varying the fluid pressure in this jet.
• the quality of the injection of the liquid jets for example by means of the optical type; and / or the quality of the plasma at the exit of the torch;
• the composition of the charge and / or the operating conditions of the plasma may be desirable to be able to adjust, if necessary, the composition of the charge and / or the operating conditions of the plasma. For example one may wish to adjust the phase shift between the period of a pulse of the plasma plummet and the period of a pulse of the injection.
• FIG. 1A is an example of a detailed embodiment of a device according to
• FIG. 1B is an example of a detailed embodiment of a system according to the invention.
• FIGS. 2A to 4 are examples of injectors profiles used in a device according to the invention.
• FIGS. 5 and 6 illustrate the problems of crossing the plasma jet by a jet of liquid (in the case of excess of momentum of the liquid jet) and the case of a lack of momentum of the liquid jet not allowing the penetration of the plasma dart.
• FIG. 7 represents a maximum splitting impact of jets that confluence at almost 90 ° just before the impact.
• FIGS. 8A and 8B illustrate the impact of jets with non-orthogonal confluence inducing the formation of liquid sheets.
• FIG. 9 represents a configuration comprising several injector sections along the axis of the plasma torch.
• FIGS. 10A to 10C show the injection into pulses of trains of liquid jets to minimize the risk of saturation of the plasma jet.
• FIG. 11 shows a possible positioning of a set of 3 pairs of injectors along the axis of the plasma torch and along two axes perpendicular to each other.
• FIG. 12 represents a profile of the heat exchange coefficient at the wall as a function of the axis xx 'of the plasma flow, as well as the plasma dart and portions of the wall.
• - Figure 13 shows schematically the positioning of an injector and a steam injection nozzle.
• FIG. 14 illustrates the constitution of a water-rich vapor boundary layer at the edge of the plasma dart to prevent the formation of soot.
• FIG. 15 represents a typical illustration of a phase diagram of the type of the water-bio-oil system.
• FIG. 16 represents one of the optical interfaces of the reactor, allowing the diagnosis of injection by optical measurement.
• FIG. 17 shows in detail the distribution of a set of three pairs of injectors, brought into the same plane, along a plasma flow axis.
• FIG. 18 schematically represents elementary volumes of the plasma dart for estimating the degree of occupancy of the stinger by the liquid charge to be converted.
• FIG. 19 shows the formation of a liquid web by confluence of two liquid jets.
• FIG. 20 shows the evolution of the radius (r) of the fluid layer as a function of the angle ⁇ and the angle of incidence of the jets ( ⁇ ).
• FIG. 21 represents an example of the fluctuation of the electric arc within the plasma torch, by the temporal tracking of the voltage at the level of the electrodes of the torch.
• - Figure 22 schematically shows the distribution, on the circular section around a plasma dart, three liquid injectors.
• Figure IB includes such a device with additional peripheral means, described below.
• the references 30, 31 denote electrodes between which an electric discharge is produced. At the same time, the passage of a plasmagenic gas between these electrodes leads to the formation of a plasma dart 3.
• Electrode supply means are designated by the reference 32.
• a support system 2 for positioning and maintaining liquid injectors to be treated.
• a cavity 2 'formed in this support flows the plasma dart substantially along an axis B designated hereafter as the plasma flow axis.
• the cavity 2 ' is of substantially cylindrical shape and the axis B is cylindrical axis of symmetry of this cavity. But other shapes can be chosen for this cavity.
• In this support 2 are arranged at least two injectors, forming a group of two injectors.
• N groups Gi of injectors (NXJ 1 , but, in general, N £ 15 or ⁇ 20) which are arranged in this support, each group G 1 comprising at least two injectors, and, more generally, neither ( nor> 2) injectors.
• the N groups of injectors are arranged along the axis of flow of the plasma. The arrangement of these injectors is described more precisely below.
• FIG. 1A diagrammatically shows 4 liquid injectors designated by the references Ib, Id, Ib ', Id'. There are therefore in fact two groups G1 and G2 each of which are two liquid injectors. There are also 4 other injectors, or nozzles, Ic, Ic ', Ic which, as explained below, allow the separate injection of steam, each of them in cooperation with the engine. one of the injectors Ib, Id, Ib ', Id'.
• the injectors Ib, Id, Ib ', Id' of liquid are directed towards the zone in which the plasma dart 3 must be formed, so as to inject the liquid with a movement having a component in a direction A (see arrow A on the FIGS. 7, 8, 9, 10A-C,
• the injectors are here arranged in groups of two or in pairs, each pair, or the outlet orifices of these injectors (orifices through which the material to be treated is ejected towards the plasma), forming an axis II ' (see Figure 7) substantially perpendicular to the axis or to the flow direction B of the plasma, the two injectors of each pair being arranged substantially diametrically opposite on the periphery of the support 2 and being directed towards the zone in which the plasma 3 is formed.
• a group Gi of injectors comprises three injectors - and more generally no injectors - these, or their orifices, are disposed substantially in the same plane perpendicular to the plasma flow axis (in FIG. would be a trace plane I-I ', perpendicular to the plane of the figure and the axis B). They are then preferably arranged substantially at 120 ° - and more generally at 360 ° / n - from each other (see, for example, FIG. 22 which represents a schematic sectional view of an injection support 2, perpendicularly to the plasma flow axis B with a group of 3 injectors Ib, Ib ', Ib' 'in the same plane, at substantially 120 ° from each other).
• angles, with respect to the plasma flow axis B, of the liquid projection axes at the outlet of the injectors of the same group of injectors, or the output axes of the injectors of this group - injectors which are arranged substantially diametrically opposite with respect to the axis of flow of the plasma in the case ni 2 - on the periphery of the support 2 (see injectors Ib and Ib 'of Figures IA, IB, 7, 8, 10A - 10C) are substantially equal to each other (in absolute value).
• the device comprises three pairs or groups G1, G2, G3 of injectors, Ib, Ib ', Id, Id', If, If arranged along the axis B, on 3 different axes but perpendicular to the axis B.
• the angles, with respect to the axis B of plasma flow, the axes of projection or output of injectors of the same group are substantially equal in absolute value.
• the angle of the axis of each of the injectors Ib, Ib '(group Gl) with the axis B is equal to ⁇ / 2
• the angle of the axis of each of the injectors Id , Id '(group G2) with the axis B is equal to ⁇ / 4
• the angle of the axis of each of the injectors If, If (group G3) with the axis B is equal to ⁇ / 6.
• the angles that make the axes of projection or output of these injectors, located in this same plane, with the axis of propagation of the plasma, are equal or substantially equal to each other, or the angles that make the directions of incidence of the jets of the injectors of this group penetrating into the plasma, with the axis of propagation of the plasma, are equal or substantially equal to each other.
• the injectors of FIG. 17 have been represented in the same plane (that of the figure), but are preferably rather arranged as indicated in FIG.
• FIG. 11 thus distinguishes three groups of injectors, Gl, G2, G3 and all the angles between the projection axes and the plasma flow axis are substantially equal to 90 °; the angle at the apex of the cone formed by the injectors and the point of convergence on the axis of flow of the plasma is then equal to substantially 180 °.
• the injectors of the same group by their positioning in the support 2 and their orientation, allow to impose a confluence of jets (continuous or discontinuous), ensuring each of them to rely on the other (s) to split at the axis of propagation of the plasma dart.
• the resulting amount of movement of the confluent jets is found, in large part, in the opposite direction to the flow B of the plasma dart. This makes it possible to ensure an increase in the residence time of the material to be converted in the stinger, as well as an optimal secondary fractionation induced by the plasma sting.
• the secondary fractionation induced by the plasma jet is a function of the relative velocity between the dart and the fluid to be converted: the opposite directions, on the one hand, of the liquid, and on the other hand of the flow of the plasma, ensure a optimization of this relative speed.
• the injector-entry distance in the plasma dart (which may be indicative of the order of 10 times (or more) the diameter of the stinger) makes it possible to ensure a flight time of the jet before the entry into the dart which completes the heating of the jet and allows if necessary to volatilize a fraction of the light species (having been able to remain in the injected liquid jet) that do not necessarily require high temperatures present in the heart of the plasma dart to be converted .
• This makes it possible to optimize the jet presence time in the stinger and to use the plasma stinger specifically for species that are particularly refractory to conversion.
• the injectors arranged in the manner described above allow, as a function of the amount of movement available for each jet, to inject the liquid charge into the plasma dart 3 (or into the dense hot flow) so as to pass through it completely. 'to the flow axis of the plasma, and so that the jets meet substantially on this axis and rely on each other during this meeting, which increases their splitting. This avoids the situation, illustrated in FIG. 5, of partial crossing of the plasma jet by the jet, without it being possible to arrive on the axis without a significant spray, or even the situation of non-penetration of the plasma by the jet ( Figure 6). In the case of FIG. 6, the jet 10 of liquid is broken by the simple contact with the edges of the plasma 3. In FIG. 17 are represented the three points A1, A2, A3 (all three located on the axis B of FIG. flow of plasma), jets meeting different groups of injectors.
• Figures 8B and 19 also show in more detail the formation of a liquid web 13 by confluence of two jets 10, 10 '.
• the point or zone of confluence located on the plasma flow axis, forms the apex of a cone whose generatrices are also constituted by an imaginary line connecting the zone or the confluence point and the orifice of output of each of the injectors whose jets are found at this point or in this confluence zone, so each of the injectors of the same group of injectors.
• the half-angle at the apex of the cone is equal to the angle formed between the direction of injection of each liquid injector and the flow of the plasma, or at the angle formed by the direction of the incident jet at the confluence point and the axis of flow of the plasma.
• the group of injectors Id, Id ' forms, with the point A2 of the confluence of the jets of these two injectors, a cone whose vertex is precisely the point A2.
• Each of the straight lines ⁇ 2, ⁇ '2, which connects this point to the outlet orifice of one of these two injectors forms a generatrix of the corresponding cone.
• the group of injectors If, If forms, with the point A3 of confluence of the jets of these two injectors, a cone whose apex is the point A3.
• Each of the straight lines ⁇ 3, ⁇ '3, which connects this point A3 to the outlet orifice of one of these two injectors forms a generatrix of the corresponding cone.
• the confluent jets are atomized directly within the plasma, benefiting from the impact between the jets, the shearing effect due to the flow of the plasma, and the highest temperature (that of the core of the plasma). plasma) and reactive species.
• the confluence of the jets makes it possible to overcome a problem, namely the optimization of the momentum for introducing the liquid into the heart of the plasma dart. Indeed, it suffices to give enough momentum to the jet so that it can penetrate the dart, but without the risk that the jet crosses the dart in case of exceeding, even limited, the limit momentum (which is almost equivalent, at least in order of magnitude, to that of the plasma dart ). This gives an additional degree of freedom and a double level of fractionation (ie that due to the plasma (difference in velocity between the liquid and the dart) and that due to the impact) while allowing to achieve a compromise between the reaching the high temperatures of the plasma and the residence time of the liquid within the stinger.
• the length h (FIG. 5) of the continuous jet penetrating the plasma dart and not subjected to fractionation is: on the one hand, the function (in order of magnitude) of the square root of the ratio (denoted q) of the quantity of movement of the liquid jet 10 to that of the plasma dart 3; preferably, q is greater than 1, more preferably greater than 2, - on the other hand, depending on the injection angle (denoted by ⁇ , this is the angle between the flow axis of the plasma and jet directions),
• the degree of saturation can vary according to the nature of the stinger and the physicochemical properties of the charge to be treated (volatility, surface tension, etc.).
• a local charge rate of less than 1% makes it possible to preserve the risk of saturation of the also aware that there is a factor of at least 1000 between the volume occupied by a liquid and the one occupied by its vapor when it vaporizes).
• FIGS. 10A-10C This situation is represented in FIGS. 10A-10C, on which only two injectors Ib, Ib 'are represented, first as each emitting a jet of material; this material 3 'will be located, initially, in a zone situated in front (FIG. 10A) of the plasma 3, then driven in the direction of flow of the plasma, while the injectors no longer emit material ( Figure 10B); when the injectors each emit a new jet of material 3 '' it is first located in an area upstream of the plasma (FIG.
• the time between the end of one liquid injection pulse and the beginning of the next is then preferably at least the time of displacement of the elementary plasma volume; in other words, it is sought to inject, into the plasma, a volume of liquid allowing a sufficient renewal of the injection zone in the plasma, to admit a new injection pulse.
• the flow rate of the gas stream is generally very important (case of a plasma dart).
• means can be provided for injecting a vapor, as illustrated in FIGS. 1A, 13 and 14, where injectors or nozzles Id, Id 'of steam are arranged each to inject a jet of steam 100, 100 'in a direction forming an angle ⁇ with the direction of injection 10, 10' injectors Ib, Ib 'of liquid charge.
• This injection of steam makes it possible to provide an additional degree of freedom over the resulting injection angle between the liquid jet and the plasma jet.
• the point or the confluence zone AO located on the plasma flow axis B, forms the apex of a cone whose generatrices are moreover constituted by the directions D1 and D2 of the incident jets. confluence point.
• the injected gas may advantageously be the easily volatilizable part (at a temperature of for example between 80 and 150 ° C. approximately) of the liquid to be converted (that is to say the part which does not necessarily have a priori need of be injected into the plasma for vaporization or conversion). This fraction is by nature (since it consists of light elements) less subject to the phenomenon of coking.
• the quantity of this vaporizable aqueous part may also optionally be adjusted with an additional water injection in order to guarantee the complete gasification of the bio-oil in the event of oxygen and hydrogen deficiency, in particular due to a specific composition of the bio-oil.
• the bio-oil for an average gross formula (CHi, 9 Oo, 7), requires an equivalent amount of water of 0.3 mole per mole of bio-oil, to be completely gasified according to the formula :
• a fractional injection injection of the volatile part in the form of vapor and the part not vaporized in liquid form in the plasma
• it is injected into the plasma plume only what must be converted, the vaporizable part outside the plasma being advantageously used in another way.
• the steam blowing optionally allows the liquid filler to be preheated prior to entering the plasma. It also makes it possible to minimize the presence of soot (solid phase resulting from the bad gasification of the liquid charge) at the end of the sting 3. Indeed, the water vapor, not having a sufficient amount of movement compared to that 3 to penetrate plasma, it will be recirculated, as shown in Figure 14, by driving induced by the plasma plume 3, which will constitute a steam layer 11, 11 'rich in water. limit of the plasma dart.
• the references 110, 110 ' designate a cloud of circulating vapor accumulated on each side of the plasma due to the injection of steam, and from which the layers 11, 11' will be formed. Soots form very quickly (formation rate less than one thousandth of a second) by involving growth and aggregation phenomena, so it is interesting to sheath the plasma sting by these zones 11, 11 'rich in water vapor to limit this formation of soot relatively refractory to gasification once they have reached penalizing sizes (may exceed one micron) in terms of gasification time.
• the composition of the plasmagenic gas can be controlled at the level of the injection into the plasma formation electrodes 3b (FIG. 1A).
• the liquid injectors Ib, Ib ', Id, Id' may have for example profiled openings, whose opening 12, of diameter or maximum dimension ⁇ , allows both not to be subjected to inadvertent plugging due to the presence of fines in the liquid to be injected, but also guarantees a satisfactory distribution of the flow within the plasma dart at their end.
• Such an injector is shown schematically in Figures 2A and 2B, for illustrative purposes, in section and in front view.
• the opening 12 is not symmetrical with respect to a direction defined by the extension axis DD 'of the injector. This opening directs or deflects the fluid towards one of the sides of the axis DD '.
• the inner wall of these outlets may also comprise a helical thread 120, as illustrated in FIG. 4, enabling a quantity of rotational movement to be impelled to the fluid, which has the consequence of making it possible to increase the fractionation of the latter within This option allows to inject continuous or discontinuous jets.
• the injectors which can then be of the type described above, or even straight outlets, can be equipped with elements piezoelectric devices to vibrate the injector and to fractionate the liquid.
• This option makes it possible to inject discontinuous jet trains. More generally, a fractionation can be promoted by the use of appropriate phasing between the pulsation of the plasma dart due to the movement of the electric arc within the plasma torch and the pressure pulsations of the jet of liquid to be converted.
• Means for pressurizing the charge to be converted make it possible to ensure the injection speed and therefore the amount of movement of the fluid to be injected.
• These means may allow adjustment of the pressure and may be controlled for example by means 7a ( Figure IB) microprocessor type.
• the jet travel time before its confluence with another jet (this time decomposing between the flight time before penetration into the sting and the duration of travel within the sting). This time makes it possible, if necessary, to raise the temperature of the fluid and thus, by reducing the induced viscosity, to increase its fractionation during the impact of the jets.
• the present invention makes it possible to optimize the injection of the liquid feed so that the physical phenomena (in particular fractionation and evaporation) are optimized.
• Fragmentation the characteristic time for 1 droplet evaporation and residence time (after impact).
• the equilibration time of the droplets is relatively long compared to other phenomena, but it is not necessary to seek at all costs for this equilibrium operation to intervene (the hydrodynamic equilibrium in fact, the fact that all the shear potential of the dart has been used, the relative plasma / liquid velocity being zero as soon as this equilibrium occurs).
• the means or device forming the injector support 2 contribute to the proper positioning and maintenance of the latter. These means are integral with the torch.
• Two groups of injectors Gi and Gj (i ⁇ j) different may have a number of injectors ni and nj different from each other.
• the injector support surrounding the plasma dart has an annular shape that can be divided by section (2a, 2b, 2c) in order to obtain a degree of freedom as to the angles between the different injection planes (a group of two injectors form a plane (injection plane) with the confluence point of the two jets from these injectors) as can be visualized for the case of Figure 11 where these planes are alternately perpendicular to each other.
• Each group of injectors in Figure 11 has two injectors. These two injectors also define an axis, perpendicular to the plasma flow axis B, but also a plane, with the point of convergence.
• the support makes it possible to maintain the temperature of the liquid to be injected, in particular to control the viscosity thereof and to complete a preheating that may have occurred in upstream during a possible charge preparation step, as explained below.
• the liquid being thus, before injection, already brought to a temperature close to the conversion temperature, the residence time in the heart of the plasma dart is optimized, because used not (or little) to heat the liquid, but rather to convert it quickly after splitting.
• the material of the support and / or of the injector may be of refractory type while allowing sufficient heat transfer to allow a heat transfer that can ensure a preheating of the liquid to be injected, without inducing temperatures. superficial injector support too high for these or coking risks of the charge to be injected.
• references 2a, 2b, 2c designate three sections of the support 2 of the injectors. These three sections are, during operation of the torch, arranged around the plasma dart 3.
• the section 2c, which corresponds to the end of the plasma dart 3, is the one with respect to which the heat exchange coefficient is at its maximum. , as shown on the upper part of Figure 12.
• Part of the support 2 of injectors can therefore be used to recover a portion of the heat from the plasma plume 3. This recovered heat can then be transferred, by conduction, to the liquid passing in the injectors. This means of preheating the liquid makes it possible to reduce its viscosity, it therefore becomes more fluid and will be better fractionated in the plasma. If necessary, in case of excessive thermal stress at the peak of the exchange coefficient, the section 2c can be offset downstream of the plasma flow.
• the device of Figure IA may include various additional peripheral means. Such means are shown schematically in FIG. 1B.
• Means 4 may thus be provided to prepare the liquid charge and to put pressure and / or temperature the liquid to be injected by the injectors into the dart 3 of the plasma.
• means 5, 5a, 5b may be provided to perform a control of the quality of the injection.
• Means 6 may allow tracking of the pulsation of the plasma torch with which the battery of injectors is associated.
• Data processing means 7a, 7b make it possible, from data corresponding to various measurements made on the system, for example from data supplied by the means 5a, 5b, 6 to readjust, if necessary, the composition of the charge and / or operating conditions of the plasma. For example, these means make it possible to adjust, for example to minimize, the phase shift between the period of a pulse of the plasma dart 3 and the period of a pulse of the injection.
• the means 4 for preparing (pressurizing and in temperature) the charge comprise, for example: a reservoir 4a of buffer reserve of the raw liquid charge, a water tank 4b (this may be water loaded with organic residues resulting from the treatment of effluents),
• a reservoir 4c for demixing or adjusting the water content for demixing or adjusting the water content (so that the conversion reaction can be total from a stoichiometric point of view).
• a decanter 4d allows the coarse separation of phases from the demixing of the raw liquid, if the latter is possible.
• the heavy phase can advantageously be injected into the heart of the plasma dart, out of the plasma torch (the most possible porch of the base 33, see Figure 17 and 18) to benefit, at best, from the optimizing zone fractionation, while the lighter phase (and easier to convert a priori), can be injected plasma tail dart or steam at steam injection nozzles (like the nozzles la, la 'in the figure 13), also making it possible to create an additional degree of freedom as to the injection angle of the liquid charge to be converted.
• Filters here two in number
• separating means for example of the centrifuge type
• a pump 4k makes it possible to recycle the undesired phase (for example the organic phase in the preparation zone of the aqueous phase) in the means 4d to carry out the decantation.
• Means 4h make it possible to measure the water content at the outlet of the demixing tank 4c. Indeed, in order to control the demixing phenomenon, a measurement of the water content can be carried out (for example by a Karl Fischer measurement). It may also be known, by measurement of elemental composition, using the means 4i, upstream of the introduction of the organic liquid charge into the buffer volume 4c, the carbon, oxygen and hydrogen content of the charge to be converted. .
• 4th means for supplying pressurized gas for example: nitrogen, or CO2, or methane or water vapor
• pressurized gas for example: nitrogen, or CO2, or methane or water vapor
• This gas may, at the exit of the injectors, begin to desorb and allow an adjustment of the composition of the medium (including oxidizing species).
• This solubilization of a gas followed by its rapid desorption (due to the large temperature and pressure gradients) in the reactor core, but especially plasma dart allows to promote the fractionation phenomenon referred. Indeed, it is likely to cause the formation of gas droplets in the liquid to be converted which, under the effect of temperature will be prone, by micro-cracking to locally split the injected liquid.
• the gas to be solubilized may represent a small mass relative to the liquid to be converted (unlike the vector gas nebulization). This leads to a fractionation of the liquid to be converted and also makes it possible to provide an additional reagent for the conversion of the latter.
• Means 4g, 4g 'pressurizing the load to be converted to ensure its injection speed and therefore its momentum allow an adjustment of the pressure to maintain it, continuous or variable, according to a periodicity and a signal (sinusoidal pressure for example as a function of time) adapted to the flow of plasma dart; in particular one thus obtains a possibility to oscillate the injection pressure to adapt to the fluctuations of the plasma dart, as evidenced by, for example, the oscilloscope 6a.
• a split solid distribution and surfactant system 4j optionally allows in situ formulation of a slurry-type filler.
• a heat exchanger 4m also optional, makes it possible to vaporize the aqueous phase before it is injected, in order to form a vapor phase to be injected separately, as already explained above, for example by the nozzles 1a, 1a. , Ic, Ic 'of Figure IA.
• heat can be recovered from a reactor cooling system and the electrodes of the plasma torch.
• Means 4p, 4o allow control of the good separation (by settling) by measuring the density of the phases, to the right of the decanter 4d demixing.
• the means 4i, 4h, 4o, 4p provide measurements to processor type means 7a for managing the preparation of the liquid to be injected.
• the ducts 40, 41 which will respectively allow the liquid phase to be injected, and possibly the separated vapor phase, may be heated, for example by a heating cord, or else by hot gas recovered at the outlet of the torch 3 and injected into a tube. double envelope around the ducts.
• a device may comprise means 5 for controlling the quality of the injection.
• An example of these means is an optical diagnostic assembly 5a allowing, by image analysis through one or more portholes 51, 53, as shown more specifically in FIG. 16, to proceed with the diagnosis of the quality of the fragmentation.
• Such an assembly comprises, for example, a high-definition camera 5b and a pulsed laser 5b 'for illuminating and visualizing the position or the displacement of the droplets of liquid charge within the dart.
• a system of filters 55 associated with the camera 5a and adapted to the nature of the plasma gases, makes it possible to overcome the emissivity of the plasma and to distinguish the droplets of liquid illuminated by the laser beam.
• a neutral sweeping gas (nitrogen in FIG. 16) makes it possible to avoid a deposit of soot on the porthole 51.
• a second example of these means is a diagnostic assembly 5c allowing, on leaving the reactor (or even on different sides inside the reactor, if the residence time of the gases in the latter is too great) to follow the composition of the permanent gases. From the data obtained by these measurements, we can deduce a first order of magnitude of the performance of the injection level.
• Means may also be provided to adapt the injection of the liquid charge to be converted to possible modifications of the plasma dart, and in particular to possible variations in the pulsation of the torch.
• the stinger from a blown arc plasma torch may be subject to pulsations due to the instabilities generated, especially during the rupture and regeneration of the electric arc inside the torch head.
• These modifications are relatively periodic and can be followed indirectly by the continuous recording of the voltage across the electrodes 30, 31 (FIG. 1A), as illustrated in FIG. 21.
• the periodicity of the pulsations of the stinger from the torch being relatively constant for a given torch and operating conditions, it is not necessarily useful (and in any case this is sometimes impossible because of the pulse frequency) to adapt the injection in real time to these pulses.
• the diagnostic system is also connected to the processor 7a which regularly compares the parameters of periodicity and phase between the control of the injection and the stacks of the plasma stinger.
• the plasma torch produces the plasma dart 3, in which the liquid injectors inject the charge to be converted.
• Means for preparing the charge provide a charge adapted to the injectors.
• Means of diagnosis of the quality of the injection make it possible to observe the fragmentation of the jets and to follow the composition of the permanent gases.
• control means make it possible to monitor the pulsation of the torch.
• the diagnostic means, the control means and the load preparation means send the information they have collected to means 7a, 7b of data processing.
• these data processing means can control the load preparation means, in order to adapt the composition of the load according to the information collected.
• the processing means also make it possible to control the pulses of the injectors with respect to the pulses of the plasma, for example to re-align them with respect to the latter.
• This example implements an untransferred arc plasma torch, of 2 MW electrical power, for the optimized conversion of the bio-oil by the best injection of the bio-oil within the plasma dart.
• the maximum capacity of the treatment system (Qmax) is close to 600 kg / h.
• Qmax maximum capacity of the treatment system
• Figure 17 gives, for a representation where the injectors would be in the same plane (that of the figure), the different notations for the positioning and the angles of the injectors; in particular :
• R and L are respectively the radius of the plasma at its base, measured from the plasma flow axis, and the length of the plasma dart from the base,
• ri denotes the length, measured on the plasma flow axis, of the fractionation zone or of the liquid layers, at the confluence of the jets,
• H'i denotes the position on the plasma flow axis
• the elementary volumes ⁇ vi defined as described in FIG. 18 then make it possible to define the occupancy rates of the liquid charge ( ⁇ i) for the elementary volumes encompassing the injection points.
• the configuration for the desired embodiment can be that indicated in Table II, configuration for which it can be sought, during operation, the minimization of ⁇ (distance between two zones of occupation of the sting by the liquid material, see figure 18) and the adjustment of the ⁇ i (in the light of the diagnostic elements of the quality of the injection) by means of the driving parameters that are ⁇ i, Qi and qi:
• ⁇ Qi ⁇ Qmax (Qmax total flow (defined as a function of the thermal power available in the plasma dart and the enthalpy of transformation of the charge (energy to convert the charge per unit mass), or here about 600 1 / h) ⁇ 1 and ⁇ 2 ⁇ 1%; q1 and q2 are both greater than 1.
• the device constituting the present invention makes it possible, in order to ensure the best possible conversion of the charge, to find the best compromise between: optimized fractionation of the liquid to be converted allowing optimization of the exchange surface between the liquid and plasma dart,
• the invention applies to the conversion of liquids such as bio-oils, or sludge treatment plant, or "slurry” or particles resulting from the spraying of a solid, these particles being mixed with a liquid for injection into the plasma torch.
• the invention also applies to the injection and / or the conversion of a liquid of the bio-oil type or, more generally, potentially containing fine particles or, more generally still, relatively difficult to nebulize (or atomize) of by its physicochemical properties (especially its viscosity).
• a gasification process of the bio-oil provides a gas suitable for the production of synthetic fuel.
• the bio-oil can be obtained by flash pyrolysis, thermochemical process (at a temperature T ⁇ 500 0 C) in which the biomass is rapidly heated in the absence of oxygen. Under the influence of heat, the biomass decomposes and leads to the formation of permanent gases, condensable vapors, aerosols and carbon residues. After cooling and condensation of volatile compounds and aerosols, a dark brown liquid, the bio-oil, is typically obtained. This is then gasified by injection into a plasma torch, according to the present invention, which makes it possible to limit or avoid the presence of tars (it is below the limit value of 0.1 mg / Nm3).
• the invention can also be advantageously implemented for the case of processes requiring the use of plasma darts or flame (s) or a relatively hot fluid (s) or generating a large amount of movement that does not make it easy to mix the load with this sting (or this hot flame or fluid or generating a large amount of movement).
• a system according to the invention also makes it possible to accept the variations in the density of the liquid to be converted. Indeed, with other systems, if there is variation in the density of the liquid, a fit that can be heavy is necessary.

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• Spectroscopy & Molecular Physics (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
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