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
• • 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
  • C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
  • C02F1/06—Flash evaporation
• • 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
  • C02F1/72—Treatment of water, waste water, or sewage by oxidation
• • 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
• • 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
• • 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
  • C02F2101/38—Organic compounds containing nitrogen
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F2209/00—Controlling or monitoring parameters in water treatment
  • C02F2209/02—Temperature
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F2209/00—Controlling or monitoring parameters in water treatment
  • C02F2209/03—Pressure
• • 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
  • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
  • Y02W10/00—Technologies for wastewater treatment
  • Y02W10/30—Wastewater or sewage treatment systems using renewable energies
• • 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
  • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
  • Y02W10/00—Technologies for wastewater treatment
  • Y02W10/40—Valorisation of by-products of wastewater, sewage or sludge processing

Definitions

• the field of the invention is that of the treatment of industrial or urban effluents charged with solid particles, including but not exclusively sludge from sewage treatment plants.
• the invention applies to the treatment of effluents which contain a significant proportion of organic matter and / or in suspension.
• the treatment in question involves ridding the effluents to be treated of a substantial part of the undesirable compounds they contain for their release into a receiving natural environment, a treatment plant or a network.
• the effluent under consideration may be essentially water, but also any other industrial fluid to which the invention may be applied.
• this treatment is implemented in a treatment plant, and is intended to treat the sludge of the wastewater treatment process entering the treatment plant.
• the treatment makes it possible to transform sludge into a suspension whose chemical oxygen demand (COD) is significantly reduced.
• COD chemical oxygen demand
• the solid phase of said suspension which is highly mineralized, can be removed, and the aqueous phase of the suspension may optionally be returned to the head of the purification plant.
• the purification methods used to treat urban or industrial effluents typically involve biological processes to reduce their biological oxygen demand (BOD) and reproduce natural phenomena by accelerating them.
• BOD biological oxygen demand
• some effluents have pollutants that are difficult to biodegradable, requiring the use of special processes, and / or frequently requiring the use of chemical substrates.
• the conditions for carrying out such a method are conventionally understood, for the pressure, between about 5 and about 160 bar, for the temperature between about 100 ° C. and about 350 ° C.
• the oxidizing gas used may in particular, be air, air enriched with oxygen or molecular oxygen.
• the quantity of sludge produced by wastewater treatment plants is about one million tonnes of dry matter per year. About half of this sludge is valued in agriculture while 35% is stored in landfills.
• this surcharge may represent 10 to 30% of the initial charge.
• one solution consists in reinforcing the operating conditions of the treatment of the effluents used, in particular in order to accentuate the mineralization of the residual sludge and to reduce the pollution load returning to the wastewater treatment sector.
• OHP wet oxidation treatments
• the energy recovery is done by preheating the effluent to be treated by the treated effluent.
• this arrangement makes it possible to recover the heat of reaction to reach self-sufficient energy operation with 45 g / l (or 4.5% DM) sludge for fresh sludge at about 80 g / l (or 8% DM) for digested sludge.
• the exchangers must be cleaned at regular intervals (typically every week or at best every 2 to 3 months).
• the reheating of the effiuent to be treated is done by mixing with the reaction medium in a piston reactor specially designed to promote mixing by adjusting the differences in density of the two fluids.
• a heating system uses the heat of reaction in a specific reactor where the heat transfer is done in several steps: a step of heat transfer by mixing the effluent to be treated with an oxidizing flow previously heated with the condensation heat of the water evaporated during oxidation drafting, and an indirect heating step on an exchanger integrated in the reactor.
• This configuration is applicable either in a subcritical oxidation system or in supercritical conditions.
• the disadvantage of this technique is to require the establishment of specific equipment in the reaction system, and to apply only on piston type reactors.
• the effiuent to be treated which contains by definition many oxidizable organic materials is directly contacted with the oxidant under conditions where the temperature is high (between 500 ° C and 600 ° C).
• the reheating is done with a reaction mixture which is maintained under supercritical conditions (the pressure may vary according to the techniques from 220 bar to 700 bar). It has also been proposed a heating system effiuent treated with the flash vapor obtained during the relaxation of the effiuent treated. These systems work batchwise in a non-oxidizing system and require at least two reactors, one using the flash steam produced by the other, which implies a complex and expensive installation.
• the invention particularly aims to overcome the disadvantages of the prior art.
• the object of the invention is to propose a process for the wet oxidation of effluents which makes it possible to dispense with the use of heat exchangers conventionally used for heating effiuents, without this being necessary. necessary to maintain the reaction mixture under supercritical conditions.
• the invention also aims to provide such a method that increases the energy recovery potential of the corresponding installation compared to known installations.
• the invention also aims to provide such a method which limits the maintenance operations of the corresponding installation compared to the solutions of the prior art.
• Another objective of the invention is to provide such a method which makes it possible to optimize the costs of building and / or operating the installations.
• Yet another object of the invention is to provide such a method which allows the treatment of effiuents continuously.
• aqueous phase oxidation process effiuents of subjecting said effluents oxidation in the presence of at least an oxidizing agent, at a temperature between about 20 0 C and about 350 0 C, at a pressure between about 1 bar and about 160 bar, so as to mineralize a portion of the organic material and to oxidize the ammonia nitrogen and total contained in said effluents, said oxidation being conducted inside a phase separation reactor in which a gaseous phase is formed above the liquid phase consisting of said effluents, said process comprising at least one heating step said effluents, characterized in that said heating step is essentially carried out within said reactor by the oxidation reaction heat of the organic material, said heating step being preceded by a step of concentrating said effluent.
• the present invention thus makes it possible to eliminate the exchangers used in the prior art and to recover all the heat of reaction in the reactor with phase separation.
• the separation within the reactor of the reaction gases produced by the oxidation of the organic materials makes it possible to reheat the effluent to be treated solely by the liquid phase, while maintaining these under conditions under criticism.
• the oxidant is thus always in contact with a reaction medium depleted in organic matter which provides a high level of safety on the reactor.
• the invention makes it possible to eliminate the exchangers, and all the maintenance sequences attached to them, such as the cleaning sequences in acidic medium, can be avoided.
• the availability of the unit is increased.
• the reaction mixture retains all its sensible heat and that the non-use or the partial use of the sensible heat of the reaction mixture to heat the effiuent to be treated, makes it possible to increase the potential of energy recovery.
• the reaction mixture at the outlet of the reactor is at the reaction temperature and a large part of the sensible heat of this mixture at the outlet of the reactor can be used to produce energy in its various forms (steam, thermal fluid or electricity) at a sufficient energy level to increase the potential for upgrading.
• the heat required for starting can easily be introduced by placing a double jacket on the reactor with the circulation of a hot fluid such as thermal oil. or steam, or by direct injection of steam into the reactor.
• a hot fluid such as thermal oil. or steam
• said oxidation is conducted in a reactor of infinitely mixed type.
• the combination of such a reactor of the type infinitely mixed with the method according to the invention can significantly increase the safety on this type of unit.
• said sludge concentration step is conducted so as to obtain effluents comprising between about 4 and about 20% solids.
• said sludge concentration step is conducted so as to obtain effluents comprising about 15% solids.
• said concentration is obtained by dilution of dehydrated or thick sludge in said effluents.
• said concentration of sludge is obtained by returning, in said effluents, a liquid phase resulting from a decantation step of said treated effluents.
• the method comprises a step of preheating said effluents upstream of said reactor.
• a step of preheating the effluent may be necessary to reach the operating temperature in the reactor by the only oxidation heat of organic matter.
• the preheating of the effluent to be treated can be done without adding an exchanger upstream of the reactor, but only by mixing with the steam produced by a partial expansion of the reaction medium produced at the outlet of the reactor in equipment separate.
• said oxidation step is conducted in the presence of a homogeneous metal catalyst belonging to the group comprising manganese, iron, cobalt, nickel, copper, zinc and mixtures and compounds of one or more of them.
• a homogeneous metal catalyst belonging to the group comprising manganese, iron, cobalt, nickel, copper, zinc and mixtures and compounds of one or more of them.
• said catalyst is preferably a copper or zinc compound, or a mixture thereof, and advantageously copper sulphate.
• the process comprises a step of recycling at least a portion of the solid phase present in said oxidation reactor.
• recycling operation does not mean that said recycled solid phase fraction must necessarily leave the reactor before being reintroduced. Recycling the solid phase only means that at least a fraction of said separated solid phase is reused within the reactor during at least one new wet oxidation cycle (continuous or batchwise).
• a step of recirculation of said effluent in the reactor is carried out during said oxidation reaction in a humid medium.
• Such a step ensures a sufficient contact time to allow the oxidation of the organic part of the effluents.
• the invention also relates to an installation for the implementation of an oxidation process in the aqueous phase of effluents comprising subjecting the effluents to oxidation in the presence of at least one oxidizing agent, at a temperature of between about 20.degree.
• said reactor is of the infinitely mixed type.
• FIG. 1 is a schematic representation of an installation for implementing the method according to the invention
• FIG. 2 is a schematic representation of the particular heat balance of the method according to the invention
• FIG. 3 is a curve indicating the dryness to be obtained as a function of the volatile fraction of the effluents to obtain the auto-combustibility
• Figure 4 is a graph showing the amount of recoverable vapor as a function of the flash trigger
• - Figure 5 is a curve indicating the amount of steam required to heat the effluent supply.
• the principle of the invention lies in the practice of wet oxidation of effluents in a reactor by searching within this reactor for the self-combustibility of the effluents, by increasing their concentration. . If the organic concentration of the effluent is not sufficient, the method according to the invention further provides an energy recovery by flash expansion of the reaction liquid which produces steam used to heat by direct contact with the effluent to be treated.
• the effluents undergo a wet oxidation in a reactor 1, in the presence of a homogeneous catalyst and an oxidizing agent (in this case oxygen), at a temperature of between 20 ° C. C and 350 ° C and at a pressure between 1 bar and 160 bar so as to mineralize a portion of the organic material and ammoniacal nitrogen effluents to be treated.
• a homogeneous catalyst and an oxidizing agent in this case oxygen
• the reactor is a phase separation reactor inside which a gaseous phase is formed above the liquid phase.
• the reactor is of the infinitely mixed type (it is noted however that the process according to the invention can be applied with any type of reactor).
• a step of concentration of the effluents for example by dehydration means 5, is carried out upstream of the mixer 2.
• this concentration step is carried out so as to cause the fraction of dry matter in the effluents to be increased from 5% to 15%.
• the effluents are heated in the mixer 2 by injecting the flash vapor obtained using a flash balloon or flash 3.
• the mixer 2 thus allows the reheating of the effluent if its organic concentration is not sufficient without using an exchanger technology, but also to recycle part of the mineralized solid phase to increase the residence time of the solids compared to the hydraulic residence time.
• the effluent concentration step is conducted so as to introduce into the mixers effluents having about 15% solids, and more generally between 4% and 20% with an organic matter content of between 40 and 90% by weight. volatile materials and more preferably of the order of 60%.
• the decantation carried out using the decanter 4 makes it possible to obtain an overflow corresponding to the hygienized liquid phase, and a solid phase recirculated in part to the mixer 2, another part being intended to be valued.
• the mixing step can also be carried out by returning, in the effluents to be treated, a portion of overflow obtained at the end of the decantation step.
• the effluents to be treated are preheated in the mixer using the flash steam stored in the balloon 3 and recirculated to the mixer 2.
• the catalyst injected into the reactor is copper sulphate, or more generally a copper or zinc compound, or even more broadly a homogeneous metal catalyst such as manganese, iron, cobalt, nickel, copper. , zinc or mixtures and compounds of one or more thereof.
• the process includes, according to the present embodiment, a step of recirculation of the effluents in the reactor during the wet oxidation.
• sludge at 10 ° C. is introduced at a rate of 3,000 kg / h (representing an enthalpy H of 30,000 kg / h) in the mixer 2.
• sludges are injected into the reactor after only heating at 80/90 0 C This heating can be achieved simply by heating the sludge in a stirred tank and equipped with a jacket with hot water circulation, or as represented in FIG. 2 by mixing the sludge with the flash vapors obtained during the expansion of the treated effluent from the operating pressure at a pressure of the order of 7 bar, or else by recycling the solids to a temperature .
• the treated sludge leaves the reactor at the reaction temperature (250 ° C.) and some of their sensible heat can be used to heat the sludge to be treated according to the devices mentioned above, and the other part used to produce sludge. energy in the form of steam or hot thermal fluid.
• the sensible heat treated sludge would obtain for example about 650 kg / h of steam 6 bar from a boiler water at 105 ° C.
• the sludge at about 90 ° C from mixture (representing an enthalpy approximately 600,000 kcal / h) are injected into the reactor in which a temperature of about 250 ° C. is maintained under a pressure of 50/60 bar, producing an oxidation reaction heat of 1,350,000 kcal. / h, by injection of oxygen into the reactor at a rate of 440 kg / h and which represents an enthalpy of 1000 kcal / h.
• the wet oxidation produces a reaction gas at 250 ° C. at a rate of 1020 kg / h, ie an enthalpy of 460,000 kcal / h.
• the treated sludge is discharged from the reactor at a temperature of 250 ° C and at a rate of 5,380 kg / h, these representing enthalpy of 1,350,000 kcal / h.
• a transfer of the flash vapor produced in the reactor to the mixers is carried out, this steam having an energy yield of 437,000 kcal / h. It is noted that a step of recirculation of the solid phase at 45 ° C towards the mixture is carried out at a rate of 2 960 kg / h, for an enthalpy of 133 000 kcal / h.
• the principle of the invention lies in the fact of heating the effluents within the reactor by using the reaction heat of the effluents.
• the curve of FIG. 3 shows the dryness of the effluents to be obtained for obtaining the auto-combustibility by using the heat of reaction as a function of the volatile fraction (or volatile matter content MV), for a lower heating value of the MVs.
• PCI volatile fraction
• (PCI) of 5 200 kcal / kg of MV, for solid returns at 125 g / l, at a reaction temperature of 250 ° C, for a preheating temperature between 65 ° C and 85 ° C and for a temperature of flash steam of 200 ° C.
• the effluents are self-combustible.
• the curve of FIG. 4 indicates the amount of vapor recoverable by flash expansion under the same PCI conditions, solid return and reaction temperature as previously indicated, for a concentration of dry matter effluents (DM) of 10% and a volatile fraction of 70%.

Landscapes

• Life Sciences & Earth Sciences (AREA)
• Hydrology & Water Resources (AREA)
• Engineering & Computer Science (AREA)
• Environmental & Geological Engineering (AREA)
• Water Supply & Treatment (AREA)
• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Treatment Of Water By Oxidation Or Reduction (AREA)
• Treatment Of Sludge (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=37698194

Family Applications (1)

Country Status (8)

Families Citing this family (10)

Family Cites Families (16)

• 2006
  • 2006-04-19 FR FR0603455A patent/FR2900147B1/fr not_active Expired - Fee Related
• 2007
  • 2007-04-13 US US12/295,492 patent/US8574442B2/en not_active Expired - Fee Related
  • 2007-04-13 AU AU2007239462A patent/AU2007239462B2/en not_active Ceased
  • 2007-04-13 CA CA 2646181 patent/CA2646181C/en not_active Expired - Fee Related
  • 2007-04-13 WO PCT/EP2007/053653 patent/WO2007118867A1/fr active Application Filing
  • 2007-04-13 JP JP2009505858A patent/JP2009534172A/ja active Pending
  • 2007-04-13 KR KR1020087025379A patent/KR101555491B1/ko not_active IP Right Cessation
  • 2007-04-13 EP EP07728118A patent/EP2007688A1/fr not_active Withdrawn

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events