Classifications

• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F11/00—Treatment of sludge; Devices therefor
  • C02F11/06—Treatment of sludge; Devices therefor by oxidation
  • C02F11/08—Wet air oxidation
  • C02F11/086—Wet air oxidation in the supercritical state
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J19/24—Stationary reactors without moving elements inside
  • B01J19/2415—Tubular reactors
  • B01J19/243—Tubular reactors spirally, concentrically or zigzag wound
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J3/00—Processes of utilising sub-atmospheric or super-atmospheric pressure to effect chemical or physical change of matter; Apparatus therefor
  • B01J3/008—Processes carried out under supercritical conditions
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J3/00—Processes of utilising sub-atmospheric or super-atmospheric pressure to effect chemical or physical change of matter; Apparatus therefor
  • B01J3/04—Pressure vessels, e.g. autoclaves
  • B01J3/042—Pressure vessels, e.g. autoclaves in the form of a tube
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
  • C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
  • C02F1/467—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis by electrochemical disinfection; by electrooxydation or by electroreduction
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/00049—Controlling or regulating processes
  • B01J2219/00051—Controlling the temperature
  • B01J2219/00132—Controlling the temperature using electric heating or cooling elements
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/00049—Controlling or regulating processes
  • B01J2219/00162—Controlling or regulating processes controlling the pressure
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/18—Details relating to the spatial orientation of the reactor
  • B01J2219/185—Details relating to the spatial orientation of the reactor vertical
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/02—Treatment of water, waste water, or sewage by heating
  • C02F1/025—Thermal hydrolysis
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
  • C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
  • C02F1/46104—Devices therefor; Their operating or servicing
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F2101/00—Nature of the contaminant
  • C02F2101/30—Organic compounds
  • C02F2101/32—Hydrocarbons, e.g. oil
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P20/00—Technologies relating to chemical industry
  • Y02P20/50—Improvements relating to the production of bulk chemicals
  • Y02P20/54—Improvements relating to the production of bulk chemicals using solvents, e.g. supercritical solvents or ionic liquids

Definitions

• the present invention relates to a process for transforming chemical structures, that is to say a process for carrying out chemical reactions in a fluid under pressure and at temperature in particular in a supercritical fluid, and a device for its implementation.
• the invention relates to a process for transforming chemical structures, that is to say a process for carrying out chemical reactions in a fluid under pressure and at temperature, in particular in a supercritical fluid, comprising a solvent and at least one electrolyte such as a salt, in which reactive species are generated in situ by electrolysis.
• the invention finds applications in a wide variety of fields. It can be applied, for example, to the modification of molecular structures, in particular in molecular engineering or pharmacology. It can also be applied to the degradation of industrial effluents, for example, the degradation of deinking inks or metal hydroxide sludges, as well as to the treatment of all kinds of effluents, in particular aqueous effluents containing for example organic and / or mineral compounds, more particularly aqueous effluents containing halogen compounds. The invention can also be applied to the destruction of explosives or dangerous products, such as, for example, pesticides (polychlorinated biphenyls). Yet another area can be the recycling of natural products, such as, for example, slurry, cellar effluents and those from milk processing.
• reactors The processes making it possible to carry out chemical reactions, in particular in a fluid medium under pressure and at temperature, in particular in a supercritical fluid, are generally implemented in apparatuses called reactors.
• tubular reactor that is to say which generally takes the form of a cylinder whose length is clearly greater than the diameter, is the easiest reactor to use, the most flexible and the least expensive.
• Tubular reactors have been the subject of numerous patents, including the patents of NL DICKINSON: US-A-4 380 960, of JF WELCH and JD SLEGWARTH: US-A-4 861 497, of L. LI and EF GLOYNA: PCT / US 92 06459, or by M. MODELL: US-A-5 252 224.
• reactors are the so-called “reservoir reactors”, that is to say reactors which generally have a low Length to Diameter (L / D) ratio, for example close to 3 or less.
• This reactor is made up of two zones: the upper part of the reactor being under supercritical conditions for water, namely at a temperature above 374 ° C. and the lower part of the reactor being under subcritical conditions, namely at a temperature below 374 ° C.
• the supply takes place from the top of the reactor in the supercritical zone, seat of the oxidation reaction.
• the salts whose solubility varies between 1 ppb and 100 ppm above 450 ° C precipitate and fall with the other solid particles towards the lower part of the reactor.
• Tank reactors have the advantage of confining the reaction and the solid / liquid separation in the same reactor: but they have, in particular, the drawback of requiring large volumes to obtain relatively long residence times in order to carry out the reactions. their terms, which affects the overall cost of the process.
• these reservoir reactors provide only an imperfect solution to the problems of salt deposition and corrosion and it is necessary, in particular, to have recourse, for the manufacture of the reactor, to materials which can withstand such conditions, or to a lining of the reactor at using these same resistant and expensive materials, such as titanium.
• the two types of reactors include for the introduction into the reactor of the various reactants, necessary for the progress of the reaction of the devices often complex, bulky and expensive, which, moreover, does not allow a homogeneous distribution of these reagents within the reactor and therefore optimal control of the reactions.
• This is in particular the case of reactors in which the oxidation of substances is carried out in an aqueous medium, and where the air, necessary for the reaction, is taken, then compressed and, finally, injected into the medium. Air compression contributes significantly to the high cost of the process, and molecular oxygen is significantly less active than oxygen in atomic form.
• anode and cathode compartments which are generally separated by a separator element can be generated, for example in water, oxygen and hydrogen.
• the document EP-A-0 535 320 relates to a process for the oxidation of organic and inorganic substances from aqueous effluents.
• the substances to be treated are first of all stored and possibly mixed in a tank, then are sent by means of a high pressure pump to an electrolysis zone which is situated immediately before or else in the zone itself. of reaction.
• the electrolysis zone is located at the inlet of the reactor.
• the substances to be treated are brought to a temperature close to the critical temperature of the water, namely 374 ° C.
• the oxygen generated initiates the oxidation reactions. Due to the exothermic nature of these reactions, the reaction mixture heats up to a temperature of up to 650 ° C. This temperature is maintained in the reaction zone until the desired degradation of the compounds introduced into the electrolysis zone has occurred.
• the mixture which leaves the reactor then transfers its heat in a heat exchanger, the gas and liquid phases are expanded, separated and, possibly, subjected to a subsequent treatment.
• the object of the present invention is therefore to provide a method and a device which respond, inter alia, simultaneously to all of the needs indicated above, which do not have the disadvantages, limitations, defects and disadvantages of the methods and devices of prior art and which solve the problems posed by the methods and devices of the prior art.
• a process for transforming at least one chemical structure found in a fluid under pressure and at temperature comprising a solvent and at least one salt, in which said fluid is formed at the bottom of a first vertical reactor called a “tank reactor” and flows upwardly into said tank reactor, successively passing through: - a first lower zone where said fluid is maintained under first conditions temperature and pressure ensuring high solubility of said salt (s) and where it undergoes electrolysis in order to generate in situ at least one reactive species and to begin said transformation, then - a second upper zone in which said fluid is maintained under second temperature and temperature conditions pressure leading to precipitation of said salt (s), and where said transformation continues;
• the method according to the invention provides a solution to all of the problems mentioned above and meets all the needs indicated above.
• the size of the said tank reactor can be significantly reduced. , which has a positive impact on the overall cost of the process.
• the tank reactor associated with the tubular reactor, is also a reactor specific vertical which includes two superimposed zones: a lower zone, playing the role of electrolysis zone, and an upper zone which plays the role of zone of precipitation of the salts and where takes place most of the reactions in question.
• the combination of the two specific reactors according to the invention solves the problems linked to the precipitation of salts and to corrosion.
• the salts and, optionally, the solid particles are effectively separated in the tank reactor and the flow of fluid sent into the tubular reactor is essentially free of salts and possibly of solid particles, likewise, most of the corrosive compounds possibly present in the fluid stream is also eliminated in the tank reactor, it follows that the tubular reactor has almost only role to achieve the desired degree of transformation, that it is partial or complete and that it is not subjected to action of any salt or other corrosive compound, no special measures have been planned in order to limit the deposition of these salts, as well as corrosion.
• the tank reactor and, preferably, only its lower zone, which is in contact with corrosive species and in which there are a lot of salts should preferably be made of a material limiting corrosion.
• the specific structure of the vertical reservoir reactor of the process according to the invention makes it possible both to precipitate and separate the salts and to use them in the electrolysis zone to increase the efficiency of the reactions which take place there.
• the salts which precipitate in the upper supercritical zone Fall back under the effect of gravity, due to the vertical arrangement of the reactor, in the lower zone or electrolysis zone, where they are resolubilized and thus permanently saturate the fluid in the electrolysis zone.
• the fluid in the electrolysis zone has a high and regular conductivity, and the efficiency of the electrolysis, and consequently of the production of the active species, and the yield and kinetics of the initiated reactions are greatly increased.
• the quantity of salts corresponding to the salts which are not resolubilized in the lower zone, settles at the bottom of the tank reactor and can be recovered continuously or in cycles.
• the process according to the invention has all the effects and advantages linked to carrying out the chemical reaction under pressure and at temperature, for example in supercritical medium, as well as all the advantages and effects linked to the in situ production of species by electrolysis, that is to say, in particular, a homogeneous distribution of these species throughout the fluid, producing much more reactive species, etc.
• the method according to the invention surprisingly combines the effects and advantages of each of the elements composing it without presenting any of the faults or disadvantages: thus, the tank reactor sees its reduced and optimized size, the reactor tubular, thanks to the position downstream of the tank reactor, allows to easily reach the desired degree of transformation, and for example to completely complete the reaction, without undergoing the harmful consequences of salt deposits and corrosion, and finally the salts are separated, corrosion avoided, the reaction optimized, thanks to the specific structure of the tank reactor: vertical, and in two zones, the lower zone allowing the active species to be produced in situ, with great efficiency, taking advantage of the electrolyte formed by the solubilization of the salts without it generally being necessary to add by means of often complex devices the less additive or external reagent.
• pressurized and temperature fluid is generally meant a fluid whose temperature and pressure are higher than its normal pressures and temperatures, namely 25 ° C and 1 bar (0.1 MPa).
• the supercritical conditions defined with respect to the pressures and temperatures at the critical point: Pc and Te
• Pc and Te are also defined in relation to the entire fluid.
• the latter may consist of a set of reagents, additives and active species, therefore in the case where the fluid consists of a complex mixture, the critical coordinates of the fluid may be poorly known.
• Pc and Te of the fluid are very close to Pc and Te of the solvent mainly present in the fluid or of the binary, ternary mixture, etc., mainly present in the fluid, and reference will then be made to the critical coordinates of said solvent to define the supercritical domain.
• the fluid "under pressure and at temperature” will generally be found in one of the three fields defined above.
• the pressures and temperatures of the above operating ranges are generally, respectively, in the ranges of 0.5 to 60 MPa and 50 to 600 ° C.
• the fluid is an aqueous fluid
• said first temperature and pressure conditions are essentially conditions ensuring a high solubility of said salt (s), namely, for example, from 1 to 10 g / l, in particular in the case of a fluid which is an aqueous saline solution - but these conditions are also optimized to ensure the best possible compromise between a good conductivity of the fluid, such as an aqueous saline solution, linked to said solubility of salts, good solubility in the fluid of structures chemicals to be transformed and reaction products and a good initiation of the transformation that one wishes to carry out from a kinetic point of view.
• a good conductivity of the fluid such as an aqueous saline solution
• the pressure in the lower zone is from 0.5 to 60 MPa and the temperature is greater than or equal to 25 ° C and less than the temperature at the critical point (Te).
• said first temperature and pressure conditions are subcritical conditions. These conditions are in particular those prevailing in the first zone in the case where the fluid is an aqueous saline solution. he It should be noted that if the temperature in the first zone is higher than the temperature at the critical point, the conductivity of the fluid generally becomes almost zero and no longer allows electrolysis, for example electrolysis of water under good conditions.
• the fluid is maintained under temperature and pressure conditions leading to precipitation of the said salt (s).
• Said precipitation generally corresponds to a solubility - in particular in the case of a fluid which is an aqueous saline solution - of less than 100 ppm, for example, from 1 ppb to 100 ppm.
• the solubility limit of said salts in these second conditions of pressure and temperature corresponds to the quantity of salts which it is desired to collect at the outlet.
• these pressure and temperature conditions must also ensure the solubility of the chemical structures which have not yet been transformed as well as that of the reaction products and allow the desired transformation or reaction to be prolonged.
• the pressure is from 0.5 to 60 MPa and the temperature from 200 to 600 ° C., in particular for saline aqueous effluents.
• the second temperature and pressure conditions are supercritical conditions.
• the third pressure and temperature conditions are generally located in the same pressure and temperature ranges as said second pressure and temperature.
• these third temperature and pressure conditions are conditions supercritical but are possibly different from the second temperature and / or pressure conditions.
• the temperature and pressure conditions differ only in temperature, the pressure being kept constant throughout the process, and being preferably a pressure higher than the pressure at the critical point Pc. Therefore, the pressure being constant, the temperature in the upper zone is a temperature allowing precipitation of the salt (s), the temperature in the lower zone is a temperature ensuring high solubility of the salts and the third temperature in the tubular reactor is a temperature possibly different from said first and second temperatures, but, however, generally higher than the second temperature (generally Te).
• chemical structure is meant, generally, according to the invention, any chemical structure, that is to say any association of atoms or molecules, solid, liquid or gaseous.
• This chemical structure may be organic in nature, such as, for example, heavy oils, aromatic compounds, etc., or inorganic or inorganic in nature, such as, for example, nitrates, metal acetates, sludges. hydroxides, etc.
• the transformation carried out in the process of the invention may relate to only one of these chemical structures or even more of these.
• the chemical structure (s) affected by the transformation can (can) be also a chemical structure (s) forming part of the solvent and / or the salt present in the fluid.
• chemical transformation or reaction is generally meant in the process of the invention, any modification affecting the chemical structure. It may be, for example, a degradation of the molecular or atomic structure of said chemical structure (s) into one or more chemical structures with a simpler molecular or atomic structure, it may also the interaction of different chemical structures with each other.
• These transformations can be any one or more of the reactions known in organic or inorganic chemistry, such as cleavage, condensation, addition, substitution, elimination, reduction, oxidation, etc.
• the fluid comprises a solvent
• this solvent constitutes the essential of the fluid
• the salt (s) and the chemical structure (s) are generally found in solution or in suspension in this solvent.
• This solvent is generally chosen from liquid or gaseous compounds under normal conditions of temperature and pressure. Also, the solvent can generally be chosen from water, known organic solvents, liquid under normal conditions of temperature and pressure, and mixtures thereof.
• the solvent can thus be chosen from liquid alkanes of 5 to 20 ° C, such as n-pentane, isopentane, hexane, heptane, octane; liquid alkenes of 5 to 20 C; liquid alkynes from 4 to 20 C; alcohols, such as methanol, ethanol; ketones, such as acetone; ethers; esters; liquid chlorinated and / or fluorinated hydrocarbons; solvents from petroleum fractions, such as white spirit; other organic solvents; and their mixtures.
• liquid alkanes of 5 to 20 ° C, such as n-pentane, isopentane, hexane, heptane, octane
• liquid alkenes of 5 to 20 C liquid alkynes from 4 to 20 C
• alcohols such as methanol, ethanol
• ketones such as acetone
• ethers such as acetone
• esters liquid chlorinated and /
• the solvent can also be chosen from gaseous compounds under normal conditions of temperature and pressure and their mixtures among which there may be mentioned carbon dioxide, helium, nitrogen, nitrous oxide, hexafluoride.
• sulfur gaseous alkanes of 1 to 5 carbon atoms: methane, ethane, propane, n-butane, isobutane, neopentane, gaseous alkenes having 2 to 4 carbon atoms: acetylene, propyne and butyne-1; gaseous dienes, such as propadiene; gaseous chlorinated and / or fluorinated hydrocarbons, for example, chlorofluorocarbons, called “Freon ® " and also called CFC or HCFC, etc., and their mixtures.
• the method according to the invention allows the treatment of aqueous effluents and the solvent is therefore water and the fluid can be defined as an aqueous saline solution, optionally charged with organic and / or mineral compounds.
• said fluid comprises at least one salt.
• This salt is chosen, for example, from the salts of metal cations and metalloids with an anion chosen from chloride, nitrate, acetate, sulfate, bromide, fluoride, carbonate, bicarbonate, etc.
• These salts are, for example, the salts found in effluents, in particular, aqueous effluents rejected by various industrial processes, such as nitrates, sulfates, etc.
• a fluid comprising said at least one structure to be transformed, a solvent and at least one salt at the bottom of the reservoir reactor.
• the structure (s) to be transformed can (can) be either a structure (s) different from the solvent and the salt (in the majority of cases, or can be the solvent and / or the salt themselves.
• each of the salt, the solvent, and the chemical structure (s) to be transformed can be introduced separately at the bottom of the tank reactor but two or more elements among these can be simultaneously introduced into the tank reactor, for example, in the form of a stream of fluid.
• a single fluid stream comprising both the salt, the chemical structure and the solvent, is introduced into the bottom of the reservoir reactor.
• It may be, for example, a saline effluent, for example, an aqueous saline effluent (the fluid is therefore then an aqueous saline solution), optionally charged with organic and / or mineral compounds to be transformed, preferably , to degrade.
• This effluent or aqueous saline solution can be acidic or basic, the process according to the invention therefore applies as well to basic aqueous saline solutions as to acidic aqueous saline solutions and more generally to any aqueous solution allowing current flow.
• the stream of fluid or effluent may also comprise only the solvent and the chemical structure, the salt being introduced separately, preferably, beforehand into the tank reactor, for example, by filling the bottom of the latter with salt: c that is to say that one introduces into this reactor, at the start of the process, a charge of salt sufficient for electrochemistry, this salt is not consumed by the process and it is confined in the tank reactor, in the bottom part of it.
• the fluid may not contain salts and not be conductive; then the fluid - such as an aqueous solution that is neither saline, acid, nor basic - is made conductive in the lower zone of the reservoir reactor, by a polymer membrane, or a solid electrolyte, of ionic conductor type, allowing the passage of the current between the anode and the cathode.
• the fluid - such as an aqueous solution that is neither saline, acid, nor basic - is made conductive in the lower zone of the reservoir reactor, by a polymer membrane, or a solid electrolyte, of ionic conductor type, allowing the passage of the current between the anode and the cathode.
• the method according to the invention is therefore of very general application and allows the treatment of all types of effluents, whether or not they contain a salt. It is also possible to add a gas such as C0 2 , or a liquid such as ethanol in said fluid or said fluid stream such as an aqueous saline solution in order to lower the critical coordinates.
• a gas such as C0 2
• a liquid such as ethanol
• the process according to the invention is generally carried out without the addition of any reagent.
• this reagent can be chosen, for example, from oxidizing compounds, such as molecular oxygen, and hydrogen peroxide H 2 0 2 .
• the additional reagent can also be chosen from reducing compounds, such as molecular hydrogen, hydrazine, lithium borohydride, and sodium borohydride.
• the fluid is formed (generally by introduction of a single fluid stream) at the bottom of a first reactor known as a "reservoir reactor".
• the size of the tank reactor is optimized by the presence of the tubular reactor in which the reaction ends, that is to say that its size is much smaller than that of the tank reactors in processes using a single tank reactor.
• This size of the reservoir reactor is determined so that the residence time in this reservoir reactor is sufficient for all the salts to precipitate and that most of the transformations involved reach a sufficient degree of advancement.
• the lower zone of the tank reactor or electrolysis zone is dimensioned so that the contact surface between the fluid, in particular the aqueous saline solution and the electrodes is sufficient to carry out the desired electrochemical transformation according to the parameters of. temperature and pressure.
• the upper part of the reservoir reactor is dimensioned essentially to allow precipitation of the salts.
• the fluid is formed in the lower half of the reactor, that is to say that the fluid stream is introduced into the lower half of the reactor, thus, in in the case of a cylindrical reactor, the introduction can be done at the base of the reactor, or else in the side wall.
• the reservoir reactor is arranged vertically, this particular arrangement of the reactor is fundamental to allow precipitation, decantation, resolubilization and evacuation of the salts and, optionally, of the particles in suspension, under the action of the gravity, according to the method of the invention.
• the fluid formed in the reactor flows upwardly in the tank reactor and firstly crosses a first lower zone, this lower zone will generally represent from 1/3 to 2/3 of the reactor, for example, half of the reactor.
• This temperature and pressure conditions prevailing in this first lower part have already been defined above.
• the lower zone is also an electrolysis zone, that is to say that it constitutes a conventional electrolysis cell, which comprises an anode and a cathode connected to a current generator between which, due to the large solubility of the salts in the fluid in the subscribed state, these salts ensure a high and regular conductivity of the fluid.
• the active species produced in the lower zone are, generally, resulting from electrolysis, from the decomposition of the solvent, thus, in the case of water, this is it decomposed into hydrogen and oxygen.
• the method according to the invention allows - in addition to the electrolysis of the solvent - to electrochemically transform one or more chemical structure (s) of the fluid - such as an aqueous saline solution - at the cathode or at the 'anode, to obtain one or more electrochemical product (s), thanks to the salts already present, or resolubilized, which ensure the conductivity of the solution.
• the active species generated in situ, at the very heart of the reactor most of which are much more active species than species introduced from the outside, which are, generally, molecular species.
• Transformations of chemical structures for example, of organic or inorganic matter in the fluid begin in this area; it could be, for example, the reaction of nascent oxygen, which begins to react on the organic or inorganic matter to be oxidized.
• the solvent is water and where the treated fluid is therefore a saline aqueous fluid or saline aqueous solution
• electrolysis leads to the decomposition of water and the transformation of the chemical structures can be a reaction of oxidation of the chemical structure from 1 '0 2 generated in the electrolysis zone thanks to the presence of the added or solubilized salts which ensure the conductivity of the solution.
• This kind of oxygen generated is a much more reactive than molecular oxygen 0 2 .
• the oxidation reaction initiated in the electrolysis zone continues in the upper zone of the reservoir reactor and reaches the degree of transformation described, partial or complete, in the tubular reactor.
• the electrolysis zone can be a single zone but it can also be separated, in particular in the case of saline aqueous effluents, on the one hand into a cathode compartment and on the other hand into an anode compartment, which makes it possible to separate - in the case of water - the oxygen formed in the anode compartment from the hydrogen formed in the cathode compartment.
• the transformation can be a reduction reaction which occurs in the cathode compartment thanks for example to the hydrogen generated in situ in this cathode compartment which is in this case alone connected to the upper zone of the tank reactor, itself connected to a tubular reactor.
• the reduction reaction initiated in the cathode compartment of the lower electrolysis zone continues in the upper zone of the reservoir reactor and reaches the desired rate of progress, partial or complete in the tubular reactor.
• the tubular reactor can contain a catalyst bed.
• the reduction reaction can also be electrocatalysted at the cathode by the use of a surface electrode of a suitable nature, for example made of platinum.
• Said reactions or transformations for example of oxidation and reduction which are carried out respectively in the anode and cathode compartments, can be conducted simultaneously and a tubular reactor can then be connected to each of the anode and / or cathode compartments which then extend over all of the lower and upper zones of the tank reactor.
• the tubular reactor connected to the outlet of the cathode compartment can, as indicated above, contain a catalyst and the reduction reaction can be electrocatalysted at the cathode.
• the fluid then passes into the upper zone.
• the reactions and transformations, started in the lower zone continue and for some end: this is notably the case with the elimination of halogenated compounds and compounds containing atoms of S and / or P which are completely destroyed before they leave the tank reactor.
• the bonds involving halogens and, in particular, the C - Cl bond are easily hydrolyzable, break and can in particular undergo a nucleophilic substitution reaction, such a reaction begins, for example at subcritical temperature and ends before the fluid leaves the reservoir reactor.
• the halide anions X " such as chloride, bromide, iodide, fluoride as well as anions containing S and / or P atoms such as sulfates or phosphates can precipitate with other cations present in the medium and be easily separated with the rest of the salts.
• the precipitated salts possibly accompanied by solid particles which settle in the lower part of the tank reactor, are collected and, optionally, discharged continuously or by operating cycle.
• a fluid, essentially, free of salts is discharged.
• fluid essentially free of salts
• fluid is meant a fluid which contains only a very low concentration thereof, corresponding to the limit of solubility, at the temperature and pressure of the medium.
• the fluid stream is essentially free of halogenated compounds.
• the tubular reactor does not receive, according to the process of the invention, neither salts nor corrosive compounds, and simply has the role of achieving the desired degree of progress of the transformation, that is to say, for example, to complete the transformation (s) and reactio (s) not completed in the tank reactor. It can therefore be made of a conventional, “non-special” material, for example, of stainless steel. According to the invention, it is possible to treat fluids such as aqueous saline solutions which could not be treated by a tubular reactor alone. According to the invention, the tubular reactor is also under pressure and at temperature, in particular under supercritical conditions.
• the fact of achieving the desired degree of advancement of the transformation that is to say, for example, of completing the transformations, reactions in a separate reactor independent of the main reservoir reactor, on the contrary of the prior art where a single reactor is used to carry out the entire reaction, makes it possible to fix in this reactor operating conditions which may be different from those prevailing in the tank reactor; it will thus be possible to operate in the tubular reactor under the best conditions making it possible to obtain the desired degree of progress of the transformations or reactions, for example, complete completion of the reactions. It will also be possible to define conditions directing the reactions towards such or such final product, preferably recoverable.
• the fluid in the tubular reactor, is also maintained under supercritical conditions, but, preferably, more "distant" from the critical point than are the conditions in the upper part of the reservoir reactor: that is ie with pressures and / or temperatures higher than those prevailing in the upper zone of the tank reactor.
• the temperature in the tubular reactor will be from 200 to 600 ° C and the pressure from 5 to 60 MPa.
• the dimensioning of the tubular reactor for the treatment of a fluid depends on the parameters of temperature, pressure and residence time.
• a fluid for example an aqueous saline solution
• the desired degree of progress of the transformation can be obtained by optimizing the parameters P and T.
• the volume can be varied, that is to say that it is possible to adapt several lengths of tubular reactor to the outlet of the tank reactor.
• the present invention also relates to an installation for implementing the method of the invention, as described above.
• the installation according to the invention is an installation for transforming at least one chemical structure found in a fluid comprising a solvent and at least one salt.
• the installation according to the invention comprises:
• a vertical reactor comprising a first lower zone where the fluid is maintained under first temperature and pressure conditions ensuring high solubility of the salt (s), and a second upper zone in wherein said fluid is maintained in second temperature and pressure conditions leading to precipitation of the salt (s), said reservoir reactor being provided with means for maintaining said fluid in said lower zone under said first temperature and pressure conditions and means for maintaining said fluid in said upper zone under said second temperature and pressure conditions, electrolysis means provided in the lower zone and means for forming said fluid at the bottom of said tank reactor;
• a second reactor called “tubular reactor”, provided with means for maintaining the fluid in third temperature and pressure conditions making it possible to reach the degree of progress of the desired transformation and connected to the upper part of said reservoir reactor.
• the tank reactor has already been described above in relation to the process with regard in particular to its volume and size characteristics, this reactor can be made of any suitable material capable of withstanding the conditions of temperature and pressure prevailing in the reactor, for example, the reactor could be made of conventional stainless steel.
• the reactor could be made of conventional stainless steel.
• only the tank reactor and preferably only its lower zone, which is in contact with corrosive species, and in which are found a lot of salts should preferably be made of a material which limits corrosion, or else provided with a lining or lining in such a material, chosen from noble metals such as titanium, platinum, gold and oxides such as alumina A1 2 0 3 or zirconia Zr0 2 .
• the means for maintaining the fluid in the lower zone, in said first conditions of temperature and of pressure, for example subscribed can, for example, comprise, on the one hand, means for maintaining a pressure for example in the whole of the reactor and, on the other hand, means for maintaining a first temperature in the lower zone of the tank reactor.
• These means may, for example, include a high pressure pump intended to pressurize the fluid stream (s) before it (s) is (are) introduced (s) into the tank and a heat exchanger intended to bringing the fluid stream (s) into the desired temperature range in the lower zone of the tank reactor.
• the heat exchanger can be provided, for example, downstream of said high pressure pump.
• the means for maintaining the fluid in the second upper zone, in said second temperature and pressure conditions, for example supercritical can, for example, in a similar manner, comprise, on the one hand, means for maintaining a pressure, for example , greater than the pressure at the critical point (Pc) in the whole of the reactor, already described above, and, on the other hand, means for maintaining a second temperature, for example greater than the temperature at the critical point in the upper area.
• a pressure for example , greater than the pressure at the critical point (Pc) in the whole of the reactor, already described above
• Pc critical point
• second temperature for example greater than the temperature at the critical point in the upper area
• the means for maintaining a first temperature in the lower zone of the tank reactor and / or the means for maintaining a second temperature, for example higher than Te, in the upper zone of the tank reactor can be constituted by the tubular reactor itself, for example, wound around all or part of the tank reactor, for example around the upper zone of the tank reactor. Therefore, exchanges of calories will be made possible.
• These two reactors and in particular the tubular reactor will thus transfer part of its heat to the fluid in the tank reactor. Such an arrangement proves to be particularly advantageous from the point of view of the energy savings achieved.
• Said means for maintaining said fluid in the lower zone in the first temperature conditions can also be constituted by cooling means such as a refrigerant and said means for maintaining said fluid in the upper zone in the second temperature conditions can also be constituted by means of heating such as one or more heating element (s), and vice versa.
• the means for maintaining said fluid in the lower zone of the tank reactor in said first temperature conditions and / or the means for maintaining said fluid in the upper zone in said second temperature conditions can be constituted by a tube for supplying fluid stream, in particular as a single fluid stream such as an aqueous saline solution wound around all or part of the reservoir reactor in order, on the one hand, to heat the fluid stream before its injection into the reservoir reactor and, on the other hand, to purge the calories generated within the tank reactor.
• Said electrolysis means generally comprise electrodes, anode and cathode, connected to a current source or generator.
• the shape of the electrodes is generally the shape most suited to the geometry of the reservoir reactor, to the circulation of the fluid in the reactor, and to the flow of current, these electrodes will therefore generally have the shape of the wires, cylinders, grids, plates, concentric cylinders, similarly these electrodes can be formed by the wall of the tank reactor.
• the anode may consist of a wire and the cathode through the body of the tank reactor or vice versa.
• the electrodes are generally made of a material suitable for the treated fluid, so the electrodes are, for example, made of Pt, Au or any other suitable conductive material.
• the surface of the electrodes, and the other conditions of electrolysis, such as voltage and intensity can be easily determined by a person skilled in the art.
• Separation means can be provided to separate the lower zone and, optionally, the upper zone of the tank reactor into a cathode compartment and into an anode compartment.
• the means for forming said fluid at the bottom of the reservoir reactor generally comprise means for introducing at least one stream of fluid, preferably single, at the bottom of the reactor. It is generally a pump or the like, the pump, as indicated above, is preferably a high pressure pump which serves to maintain the tank reactor at a pressure, for example, greater than the pressure Pc.
• the tubular reactor has already been described above, in relation to the method with regard to its characteristics of volume and dimensions.
• This tubular reactor is, according to the invention, placed in series with the tank reactor and is connected to the upper part thereof by channeling means or the like.
• the installation according to the invention may also include means, provided at the bottom of the tank reactor for collecting and, optionally, removing the settled salts and solid particles, continuously or by operating cycle.
• These means may, for example, consist of means for injecting a stream or stream of pure solvent, such as water, free of salt in the lower part of the reactor and in means for discharging the solvent flow which takes charge of salt.
• the elimination of the precipitated salts at the bottom of the reactor by rinsing or washing using a flow of solvent, such as pure water can preferably be carried out continuously or in cycles.
• means for generating ultrasound can be provided in the lower and / or upper zone of the reservoir reactor.
• Means for modifying the flow and, in particular, for promoting the settling of the salts and solid particles such as deflectors, baffles, baffles, or the like, may be provided in the upper and / or lower part of the reservoir reactor.
• These means for modifying the flow can be constituted by the electrolysis electrodes, themselves, in the lower zone of the reservoir reactor, for example, wound around one another to promote a piston-type flow.
• FIG 1 there is therefore shown an installation according to the invention which is more particularly suitable for the treatment of aqueous effluents saline or not.
• this installation essentially comprises a tank reactor 1 and a tubular reactor 2 which are associated in series.
• the effluent to be treated (arrow 3) coming, for example, from a storage tank, a high pressure pump and a heat exchanger (not shown) enters the bottom of the tank reactor 1, positioned vertically , via a tap 4 provided here in the side wall 5 of the tank reactor.
• the latter is shown in Figure 1 in the form of a cylinder whose diameter is equal to about one third of the height.
• the effluent crosses, first of all, the lower zone 6 of the reservoir reactor which constitutes an electrochemical cell provided with two electrodes, represented here, in the form of metal plates 7, 8, and connected to a current generator.
• the pressure in the lower zone is around 25 MPa, while the temperature is around 350 ° C; at this temperature, the salts make the solution conductive between the two plates and the water is decomposed into oxygen and hydrogen.
• the nascent oxygen begins to react on the chemical substances to be oxidized which are organic and / or inorganic matter and which include, for example, chlorine compounds, with, in addition, a high COD.
• the effluents then pass into the upper zone (beyond the limit 9 which may or may not materialize), where the fluid is in the supercritical state, that is to say that the pressure is of the order of 25 MPa and the temperature from 374 ° C to 600 ° C.
• the oxidation reaction intensifies and the salts precipitate (11) and fall (12) towards the bottom of the reactor.
• the critical zone 6 there is resolubilize and saturate the solution between the metal plates 7 and 8, the production of oxygen is therefore optimal; the non-resolubilized salts and the solid particles decant at the bottom 13 of the reactor.
• Means for collecting and optionally discharging the salts and solid particles in the form, for example, of discharge orifices 14, 15 are provided at the base of the reactor.
• FIG. 1 can include means for regulating the flow rates, pressure, temperature and the like, as well as sensors, waves, flow meters and the like, for measuring, in particular, the various parameters of the fluid.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Life Sciences & Earth Sciences (AREA)
• Hydrology & Water Resources (AREA)
• Engineering & Computer Science (AREA)
• Environmental & Geological Engineering (AREA)
• Water Supply & Treatment (AREA)
• Electrochemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Treatment Of Water By Oxidation Or Reduction (AREA)
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• 1998
  • 1998-07-10 FR FR9808923A patent/FR2780986B1/fr not_active Expired - Lifetime
• 1999
  • 1999-07-09 WO PCT/FR1999/001681 patent/WO2000002820A1/fr not_active Ceased
  • 1999-07-09 US US09/720,256 patent/US6551517B1/en not_active Expired - Fee Related
  • 1999-07-09 CA CA002337272A patent/CA2337272A1/fr not_active Abandoned
  • 1999-07-09 EP EP99929460A patent/EP1105352A1/de not_active Withdrawn

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