WO2018184123A1

WO2018184123A1 - Method and apparatus for extracting carbon dioxide during the wet oxidation treatment of waste

Info

Publication number: WO2018184123A1
Application number: PCT/CH2018/000012
Authority: WO
Inventors: Boris Correa
Original assignee: Granit Technologies And Engineering (Grt) Sa
Priority date: 2017-04-06
Filing date: 2018-04-05
Publication date: 2018-10-11
Also published as: CH713676A1

Abstract

The present invention relates to a method and apparatus (100; 300) for recovering carbon dioxide produced during wet oxidation treatment of an aqueous mixture of waste containing organic matter, possibly mixed with mineral materials, bio-mineral materials or organic resins. The installation (300) comprises an oxidation reactor (102) and a heat exchanger (103) located at the oxidation reactor outlet (102). The waste mixture to be treated and the oxidizing gas are introduced into the oxidation reactor 102. A fraction of the liquid resulting from said oxidation treatment in said reactor (102) is used for pre-heating the waste mixture and the oxidizing gas. A first gas and liquid separator (104) is used essentially to extract carbon dioxide and is connected to the inlet (161) of a pressurised gas cooler (105). The outlet (162) of the gas cooler (105) is connected to the inlet (171) of a second gas and liquid separator (106) for discharging gases which cannot be condensed and a pump (107) for filling containers or bottles (108) with pressurised liquid carbon dioxide.

Description

PROCESS AND PLANT FOR EXTRACTING CARBONIC ANHYDRIDE DURING WET PROCESSING BY WET OXIDATION Technical Field

The invention relates to a process for recovering carbon dioxide produced during a wet oxidation treatment from an aqueous mixture of waste containing organic matter, optionally mixed with inorganic materials, bio-mineral, organic resins or any other oxidizable substance;

said method comprising a first step during which an oxidizing gas is introduced into said aqueous waste mixture, said aqueous waste mixture is preheated and said oxidizing gas is carried out, said wet oxidation reaction is carried out in an oxidation reactor at temperatures sufficient to oxidize said oxidizable substances, the treated residues are cooled, the gases generated by said oxidation treatment of the residual liquids resulting from the oxidation treatment are separated at least partially and the gases separated from the liquids are pre-cooled;

said method comprising a second step in which the pre-cooled gases are fed into a first gas and liquid separator to separate the gases from the oxidation treatment of the liquid residues;

said method comprising a third step in which said separated gases are fed to a pressure cooler to liquefy them, said gases comprising carbon dioxide generated by the oxidation reaction of organic materials and non-condensable residual gases;

said process comprising a fourth step during which the pressurized liquid carbon dioxide is separated from the non-condensable gases, and; said method comprising a fifth step during which the produced liquid carbon dioxide is collected.

The present invention also relates to an installation for recovering carbon dioxide produced during an oxidation treatment by wet, from an aqueous mixture of waste containing organic matter, optionally mixed with mineral materials, bio-mineral materials, organic resins or any other oxidizable substance; said plant comprising means for supplying an oxidizing gas for introducing an oxidizing gas into said aqueous waste mixture, heating means for preheating said aqueous waste mixture and said oxidizing gas, an oxidation reactor for carrying out said reaction; wet oxidation, at temperatures sufficient to oxidize said oxidizable substances, cooling means for cooling the treated residues, gas separation means for at least partially separating the gases generated by said oxidation treatment residual liquids from the oxidation treatment and cooling means for pre-cooling gases separated from liquids;

said plant further comprising conveying means for feeding the pre-cooled gases into a first gas and liquid separator for separating the gases from the oxidation treatment of the liquid residues; transfer means for sending said separated gases into a pressure cooler to liquefy them, said gases comprising carbon dioxide generated by the oxidation reaction of organic materials and non-condensable residual gases;

gas separation means for separating the pressurized liquid carbon dioxide from the non-condensable gases, and;

capture means for collecting the produced liquid carbon dioxide. Prior art

The principle of the process of wet oxidation of waste of this type is known, in particular from the Swiss patent application 00493/12 filed on 10

greenhouse to slow global warming is a major drawback of this process. In addition, the plant corresponding to this process is equipped with a first heat exchanger mounted upstream of the wet oxidation reactor and a second heat exchanger mounted downstream of said reactor. This equipment is intended to ensure the thermal regulation of the oxidation treatment process, in particular the preheating of the mixture mixed with the oxidizing gas. However, the heat exchangers used in the installation are complex and expensive equipment so that a process in which two heat exchangers, the construction of which is complicated and the delicate maintenance, necessarily generate costs that penalize the operation of the plant. process and development of the application. The reduction of costs would undoubtedly be a considerable advantage for a generalization of the implementation of the process.

US Patent No. 4,543,190 A discloses a method of oxidizing an organic material by forming a mixture of the organic material with water and an oxygen-containing fluid under conditions near supercritical pressure. Fine analysis of this patent reveals that the process actually works under supercritical conditions which are totally proscribed in the present invention.

US Patent 5,417,937 describes a dry oxidation apparatus which differs from the installation according to the invention in that it comprises a preheating exchanger, totally absent from the installation, object of the present invention. The other documents cited in the research report, namely Swiss patent applications CH 706 345 A1, US US 2012/006756 A1 and US US 2016/141059 A1 are all inventions of the inventor CORREA Boris, which is the inventor of the present patent application, and which are fundamentally different from the present invention. Presentation of the invention

The present invention provides a solution to the problems mentioned above, by recovering the carbon dioxide released during the wet waste oxidation treatment, as a by-product of the process, which has the dual advantage of limiting pollution and recover a product that is a raw material with many applications in the industry.

For this purpose, the process according to the invention, as defined in the preamble, is characterized in that the gases generated by said oxidation treatment are separated at least partially from the residual liquids resulting from the oxidation treatment at the outlet. of said treatment reactor, the gases separated from the liquids are transferred into a heat exchanger in which they are pre-cooled, the pre-cooled gases are sent to a first gas and liquid separator to separate the gases from the treatment of oxidation of liquid residues, sending said separated gases in a pressure cooler for liquefying, these gases comprising carbon dioxide generated by the oxidation reaction of organic materials and non-condensable residual gas, l the pressurized liquid carbon dioxide is separated from the non-condensable gases and the liquid carbon dioxide produced is collected.

According to a second variant, at least a portion of the hot residual aqueous liquid fraction resulting from the oxidation treatment at the outlet of said treatment reactor can be pumped by injecting it upstream of said oxidation reactor directly into the reactor. mixture of cold aqueous mixture to be treated and before the injection of oxidizing gas, said transfer being carried out in a controlled manner, such that said mixture of aqueous mixture to be treated and oxidizing gas to which said portion of said fraction has been added A residual hot aqueous liquid enters the reactor at said predetermined preheating temperature. In this context, it is advantageous to inject said hot residual aqueous liquid fraction separated from the gases, during the oxidation treatment, directly into a feed conduit of said aqueous mixture to be treated in said reactor, and in that preheating the aqueous mixture to be treated by wet oxidation and oxidizing gas, by an appropriate dosage of said hot residual aqueous liquid fraction before the injection of the oxidizing gas.

Advantageously, said appropriate dosage of said hot residual liquid fraction is carried out by the management of the temperatures of the aqueous mixture to be treated by wet oxidation, the oxidizing gas and said hot residual aqueous liquid fraction from the reactor by injecting a volume of said hot liquids which depends firstly on its own temperature, and secondly on the temperature and the volume of said cold aqueous mixture to be treated and the oxidizing gas at the time of the injection.

According to an advantageous embodiment, said dosing of said hot residual liquid fraction separated from the gases during the oxidation treatment is carried out by means of a pump controlled by a control unit which calculates the flow rate of the injection as a function of the measured temperatures.

According to another embodiment of the process, the preheating is carried out by adding to the aqueous mixture to be treated cold and before the injection of the oxidizing gas a hot fraction of said treated hot residual liquid fraction resulting from the oxidation treatment to obtain a temperature injection in the reactor between 120 and 250 ° C and preferably between 130 and 180 ° C.

For this purpose also, the installation according to the invention, defined in the preamble, is characterized in that it comprises means for cooling the treated residues in a heat exchanger, means for at least partially separating the gases generated by said wet oxidation treatment of the residual aqueous liquids from the oxidation treatment, the means for for transferring the gases separated from the aqueous liquids into a heat exchanger and for pre-cooling said gases, a first gas and liquid separator for discharging on the one hand the non-condensable gases and the carbon anhydride generated by the oxidation reaction and secondly the aqueous liquids from the condensation in said heat exchanger, a pressure cooler in which the precooled carbon dioxide is liquefied, a second separator of gas and liquids to separate the liquefied carbon dioxide under pressure of non-condensable gases, and a conditioning and storage unit for storing liquid carbon dioxide in containers.

The installation further comprises means for transferring at least a portion of the hot residual aqueous liquids, originating from the oxidation treatment at the outlet of said treatment reactor, by injection upstream of said oxidation reactor, directly into the aqueous mixture of waste to be treated which is then mixed with the oxidizing gas, means for carrying out said injections in a controlled manner, such that said mixture of aqueous mixture to be treated, oxidizing gas and said part of hot residual aqueous liquids, enter the reactor at said predetermined preheating temperature and perfectly mixed.

Advantageously, it may further comprise means for transferring at least a portion of the hot residual aqueous liquids from the oxidation treatment at the outlet of said wet oxidation treatment reactor, means for carrying out upstream of said oxidation reactor, the mixture directly into the aqueous mixture to be treated and then mixed with the oxidizing gas.

Advantageously, it may comprise means for carrying out said injection in a controlled manner, such that said mixture of aqueous mixture to be treated to which said residual liquid fraction has been added then the oxidizing gas enters the reactor at said predetermined preheating temperature and perfectly mixed.

Said vertical cylindrical chamber of said oxidation reactor advantageously contains a tubular column open at its end forming an opening which is formed at the end of a U-shaped curved section and opening into an upper zone of said tubular column for collecting the liquids. generated by the oxidation reaction in said oxidation reactor.

Said opening of said tubular column is advantageously connected by a conduit for supplying said hot liquids generated by the oxidation reaction, to a pump, mounted upstream of said oxidation reactor, on a conduit for supplying said mixture of aqueous mixture before the injection of the oxidizing gas.

According to a preferred embodiment, said pump is arranged to perform an appropriate dosage of said liquids by the management of the temperatures of the aqueous mixture to be treated by wet oxidation, the oxidizing gas and liquids from the reactor by injecting a volume of said liquids. which depends, on the one hand, on the temperature of said hot injected liquids, and on the temperature of said mixture of the aqueous mixture at the moment of injection.

Said pump is preferably controlled by a control unit which calculates the volume to be injected as a function of the measured temperatures.

Brief description of the drawings

The present invention and its advantages will appear better in the following description of embodiments given by way of nonlimiting example, with reference to the appended drawings in which: FIG. 1 represents a general schematic view of a first embodiment of the installation according to the invention, intended to recover carbon dioxide at the end of a wet oxidation treatment, from a aqueous mixture of waste containing oxidizable organic materials, and FIG. 2 is a general schematic view of a second embodiment of the plant according to the invention, intended to recover carbon dioxide at the end of a wet oxidation treatment, an aqueous mixture of waste containing oxidizable organic materials.

Best way to realize the invention

With reference to FIG. 1, the installation 100 which corresponds to said first embodiment, has as a function the treatment by wet oxidation of an aqueous mixture of waste containing oxidizable charges, in particular organic materials and / or bio-mineral materials or any other oxidizable substance, for example organic resins from radioactive waste and possibly containing mineral matter.

For this purpose, the installation 100 comprises, in the direction of the course of the treatment process, a first heat exchanger 101, an oxidation reactor 102 and a second heat exchanger 103 disposed downstream of said oxidation reactor 102. At the outlet 132 of the second heat exchanger 103 is placed a first separator 104 of gas and liquids which is equipped with an output 151 of the gases and an outlet 152 of the liquids. The output 151 of the gases, essentially carbon dioxide, is connected to the inlet 161 of a pressurized gas cooler 05. The outlet 62 of the gas cooler 105 is conected to the inlet 171. a second gas and liquid separator 106 which is equipped with two outlets 172 and 173. The outlet 172 makes it possible to evacuate gases that can not be condensed. The outlet 173, connected to a pump 107, makes it possible to fill containers or bottles 108 of liquid carbon dioxide under pressure, ie under a pressure between 200 and 300 bar, and preferably at least approximately equal to 250 bar.

The oxidation reactor 102 is preferably composed of a vertical cylindrical chamber 102a which contains a tubular column 102b open at its upper end 102c. Said upper end 102c open is formed at the outlet of the tubular column 102b whose upper end is curved U and disposed in an upper region of said vertical cylindrical chamber 102a. The vertical cylindrical chamber 102a of the oxidation reactor 102 has an inlet 102d located in an area near the base of the oxidation reactor 102, a 102e gas outlet located at the top of the oxidation reactor 102 and an outlet 102f , which communicates with the open end 102c of said tubular column 102b, and allows to capture the liquid substances in the vertical cylindrical chamber 102a of the oxidation reactor 102. The oxidation reactor 102 is surrounded by an insulating jacket 120 intended to maintain the cylindrical chamber 102a and its contents at the treatment temperatures provided for the oxidation reactions, according to the wet oxidation process. Said first heat exchanger 101 is called preheating exchanger, because its function is to ensure the preheating of the aqueous waste mixture to be treated and to maintain the temperature of said aqueous waste mixture between predetermined values in order to avoid deposits likely to plug this exchanger. The preheating exchanger 101 comprises an internal circuit 101a with an inlet 121, through which are injected firstly the aqueous mixture of waste to be treated, coming from a conduit 140 and secondly an oxidizing gas, for example from air or oxygen under pressure at controlled temperature from a conduit 141. On the conduit 140 is mounted a pump 142 which supplies the solution to be treated, driven by a motor 143. A flow measuring instrument 144 is controlled by a control and regulation unit 144b to regulate the flow of material in the conduit. 140. The preheating exchanger 101 also comprises an outlet 122 which is connected to the inlet 102d of the oxidation reactor 102, for conveying the raw material to be treated to the oxidation reactor 102. The preheating exchanger 101 also comprises a peripheral circuit 101b with an inlet 123 which is connected to the outlet 102f of said tubular column 102b, open at its upper end 102c. Said peripheral circuit 101b also comprises an outlet 124 which discharges a part of the residual liquids after the treatment of the aqueous waste mixture in the oxidation reactor 102.

The two heat exchangers, respectively 101 and 103, each consist of two tubes arranged one inside the other, so as to create two circuits, namely an inner circuit and a peripheral circuit which completely surrounds the internal circuit. As regards the first heat exchanger 101, it comprises the inner circuit 101a and the peripheral circuit 101b. The second heat exchanger 103 comprises an internal circuit 103a and a peripheral circuit 103b. The internal circuit 103a has an input 131 and an output 132. The peripheral circuit 03b has an input 133 and an output 134.

The outlet 32 of the internal circuit 103a is connected to the inlet 50 of a first separator 104 of gas and liquids, disposed downstream of the second heat exchanger 103 and which comprises a gas outlet 51 through which the gases are evacuated, in particular carbon dioxide, and a residue outlet 152, to evacuate liquid residues freed of organic substances that have been oxidized during the treatment. The residues passing through the outlet 152 of the separator 104 are evacuated through a valve 153 and a decompression diaphragm 154. The output 151 of the gases of the separator 104 of gases and liquids is connected to a pressurized gas cooler 05 containing a circuit internal refrigeration 105a. It comprises an entry 161 corresponding to the arrival of the gases, in particular carbon dioxide and gases which can not be condensed, and an outlet 162 through which liquid carbon dioxide is removed on the one hand and said non-condensable gases on the other hand. The outlet 162 of the high-pressure gas cooler 105 is connected to a second gas and liquid separator 06 to which liquid carbon dioxide and non-condensable gases are transferred through an inlet 171. A first outlet 72 allows evacuate the non-condensable gases, such as for example oxygen, carbon monoxide and possibly a small portion of carbon dioxide. A second outlet 173 makes it possible to evacuate the carbon dioxide in the liquid state, at a pressure of between 60 and 100 bar and preferably of between 65 and 73 bar.

The liquid carbon dioxide is finally collected after pumping by means of a pump 107, which carries the pressure of liquid carbon dioxide between 200 and 320 bar and preferably close to 250 bar, in containers or bottles 108, for storage, pending further industrial use. A temperature control device 180 is mounted on the conduit which connects the outlet 122 of the preheating heat exchanger 101 to the inlet 102d of the oxidation reactor 102.

The process which will be described below consists in extracting carbon dioxide produced during a wet oxidation reaction from organic waste. These oxidizable wastes are transformed into an aqueous waste mixture, and their oxidation produces large quantities of carbon dioxide which can be used for various industrial applications. The method comprises introducing an oxidizing gas into the aqueous waste mixture, preheating said mixture with said oxidizing gas in a first heat exchanger, and then performing said oxidation reaction in an oxidation reactor at temperatures sufficient to oxidize said oxidizable materials contained in said aqueous waste mixture, then cooling the treated residues in a second heat exchanger and finally separating the residual liquids from the non-condensable residual gases, finally isolating the carbon dioxide and storing it in suitable containers, in the form of a liquid under pressure.

The waste mixture to be treated and the oxidizing gas are introduced into the inner circuit 101a of the first heat exchanger or preheating exchanger 101 at a relatively low temperature which is the ambient temperature. The peripheral circuit of this heat exchanger receives the liquid from the oxidation reactor 102, at high temperature, which allows to preheat the oxidizing gas mixture and waste mixture to be treated. This preheated mixture is introduced into the oxidation reactor 102, in which the oxidizable substances contained in this mixture undergo the oxidation treatment. As mentioned above, the liquid, or at least a large part of the liquid resulting from this treatment is used for preheating the mixture in the preheating exchanger 101. The gas, or a large part of the gas, resulting from the treatment of The oxidation, however mixed with a residual fraction of high temperature liquids, is captured at the top of the reactor to be fed into the inner circuit 102a of the second heat exchanger 103. The purpose of this passage is to cool the gas, which is mainly carbon dioxide, however, mixed with some non-condensable gases such as oxygen, carbon monoxide and a fraction of the treated liquid. At the outlet of the second heat exchanger 103, the gas and the residual fraction of cold liquids are sent into the first separator of gas and liquids 104. The liquids are evacuated and the gas, which is a mixture of carbon dioxide and said non-condensable gases are sent to the cooler 105 which liquefies the carbon dioxide under pressure. At the outlet of this cooler 105, the products are sent into the second gas and liquid separator 106 which discharges the non-condensable gases and collects the liquid carbon dioxide, through a pump 107 which brings it to a filling station bottles or bottles 108 for use subsequent industrial Said industrial use may concern the food industry, the chemical industry or other industrial sectors, since carbon dioxide has many applications in many technical fields.

A second embodiment of the plant for separating and conditioning the carbon dioxide produced during the wet oxidation treatment is described hereinafter with reference to FIG. 2. The installation 300 comprises, successively, a an inlet assembly 200 of the aqueous mixture to be treated, an oxidation reactor 102, a heat exchanger 103, placed after said oxidation reactor 102 and then a specific equipment 250 whose function is, as for the installation 100 of Figure 1, to separate and collect the carbon dioxide produced. The inlet assembly 200 of the aqueous mixture to be treated in the installation 300 is advantageously constituted by a tank 200a or the like equipped for example with kneading or stirring members (not shown), which are capable of mixing the waste with a predetermined quantity of water for producing said aqueous mixture to be treated in the installation 300, according to the method described. The volume of added water is suitable so that said aqueous mixture has a fluid consistency and can flow through the various components of the plant 300.

Said so-called preheating exchanger 101 of the plant of FIG. 1 is eliminated, and the oxidation reactor 102 is directly fed with the mixture to be treated coming from said assembly 260. The oxidation reactor and, as previously composed of an enclosure vertical cylindrical 102a which contains said tubular column 102b open at its upper end 102c. This upper end 102c open is formed at the outlet of the tubular column 102b, curved U at its upper part and disposed in an upper zone of said tubular column 102b. Said tubular column 102b constitutes an inverted suction pipe which, by construction, sucks a maximum of liquid and a minimum of gas. The vertical cylindrical chamber 102a of the oxidation reactor 102 has an inlet 102d located in an area near its base, a gas outlet 102e located at its top and an outlet 102f, corresponding to the open end 102c of said tubular column. 102b, and which makes it possible to capture the liquid substances in the vertical cylindrical chamber 102a of the oxidation reactor 102. The oxidation reactor 02 is surrounded by an insulating mantle 120 intended to maintain it, as well as its contents, at the temperatures of treatment intended to ensure the oxidation reactions, according to the wet oxidation process which is implemented in the installation 300.

After the oxidation reactor 102 is disposed a heat exchanger 103 identical to the exchanger 103 of Figure 1 and having the same functions. The further processing, and in particular the recovery of the carbon dioxide product is carried out in the specific equipment 250 which receives the raw material from the outlet of the heat exchanger 103, namely substances from the reactor of oxidation 102 and having passed through this second heat exchanger 103.

The installation 300 comprises, as the installation 100, a gas and liquid separator 104, a pressurized gas cooler 105, a second gas and liquid separator 106 to which the liquid carbon dioxide and the non-gas are transferred. condensable, a pump 107, which carries the pressure of liquid carbon dioxide between 40 and 200 bar and preferably close to 60 bar, in containers or bottles 108, for storage, waiting for a subsequent industrial use.

The process involves extracting carbon dioxide produced during a wet oxidation reaction from organic waste. These oxidizable wastes are transformed into an aqueous waste mixture, and their oxidation produces large quantities of carbon dioxide which can be used for various industrial applications. An oxidizing gas is introduced into the aqueous waste mixture, said mixture is preheated with said oxidizing gas in an oxidation reactor, at temperatures sufficient to oxidize said oxidizable materials contained in said aqueous waste mixture, then the treated residues are cooled. in a heat exchanger and the residual liquids are separated from the non-condensable residual gases, finally isolating the carbon dioxide and storing it in appropriate containers, in the form of a liquid under pressure. The waste mixture to be treated and the oxidizing gas are introduced into the oxidation reactor 102, as mentioned above, a fraction of the liquid resulting from this treatment is reused for preheating the mixture mixture and oxidizing gas. The gas, or a large part of the gas, resulting from the oxidation treatment, however mixed with a residual fraction of liquids at high temperature, is captured at the top of the reactor to be sent into the internal circuit 103a of the second heat exchanger 103. The purpose of this passage is to cool the gas, which is mainly carbon dioxide, however mixed with some non-condensable gases such as oxygen, carbon monoxide and a fraction of the treated liquid. At the outlet of the heat exchanger 103, the gas and the residual fraction of cold liquids are sent into the first separator of gas and liquids 104. The liquids are evacuated and the gas, which is a mixture of carbon dioxide and said non-condensable gases are fed to the cooler 105 which liquefies the carbon dioxide under pressure. At the outlet of this cooler 105, the products are sent into the second gas and liquid separator 106 which discharges the non-condensable gases and collects the liquid carbon dioxide, through a pump 107 which brings it to a filling station bottles or bottles for later industrial use. Said industrial use may concern the food industry, the chemical industry or other industrial sectors, since carbon dioxide has many applications in many technical fields. The collection of carbon dioxide helps to reduce the greenhouse effect, knowing that this gas occupies an important place with regard to the warming of the Earth's atmosphere. With reference to FIG. 2, the installation 300 also has the function of treating by wet oxidation an aqueous waste mixture containing oxidizable charges, mineral substances and / or organic materials and / or bio-mineral materials. or any other oxidizable substance, for example organic resins from radioactive waste. Certain components of the present installation 300, identical to those of the installation 100 illustrated in FIG. 1, will not be described in detail and will be designated by the same references.

For this purpose, said installation 300, comprises as main components, arranged in the direction of the flow of the material, an inlet assembly 210 of the aqueous mixture to be treated by wet oxidation, an oxidation reactor 02 and an exchanger heat 103 and then a specific equipment 250 whose function is to separate and condition the carbon dioxide collected and which is identical in all respects to the installation 250 described with reference to Figure 1. It will be noted that the installation 300 , unlike the installation 100, has only one heat exchanger, namely P exchanger 103, said preheating exchanger 101 has been removed. To preheat the aqueous mixture, the preheating exchanger has been replaced by a preheating assembly 260. The advantage of this change is that the manufacturing cost of the assembly 260 as well as its operating cost are much higher. economic. This assembly will be described in more detail below.

Said assembly 260 for regulating the inlet temperature of the mixture of the aqueous mixture to be treated, has the function of ensuring proper preheating. For this purpose, the assembly 260 comprises a three-way mixer connected on the one hand to a supply line 140 of the aqueous mixture of waste to be treated, issuing from the tank 200a and on the other hand, to a supply duct connected to said open end 102c of said tubular column 102b, housed in the oxidation reactor 02, said supply duct 203 being arranged to bring the collected liquid substances into the vertical cylindrical chamber 102a of the oxidation reactor 102. Note that the mixture from the conduit 140 is cold and the liquid substances from the treatment in the reactor, are hot. A precise dosing of the volume of hot liquids makes it possible to raise the temperature of the mixture cold treatment mixture and hot liquids from the treatment, which will be added the oxidizing gas brought by a conduit 141 at a suitable preheating temperature. This precise metering is carried out by a variable flow circulation pump 204, which is regulated by the temperature of the mixture consisting of both the mixture to be treated by oxidation, the oxidizing gas and the fraction of liquid coming from the reactor, and which is hot. Said assembly 210 for regulating the inlet temperature of the mixture essentially comprising the aqueous mixture to be treated and the oxidizing gas, has the function of ensuring proper preheating of said mixture. For this purpose, the assembly 260 comprises a three-way valve 202 connected on the one hand to a supply line 140 of the aqueous waste mixture to be treated and on the other hand, to a supply duct 203, connected at said open end 102c of said tubular column 102b, this supply duct 203 being arranged to bring the collected liquid substances into the vertical cylindrical chamber 102a of the oxidation reactor 102. It will be noted that the mixture coming from the duct 140 is cold and that the liquid substances resulting from the treatment in the reactor, are hot. A precise dosing of the volume of hot liquids makes it possible to raise the temperature of the mixture to be treated cold and hot liquids from the treatment, to which will be added the oxidizing gas brought by a conduit 141 through an injector 202, at an appropriate preheating temperature . This precise metering is carried out by a variable flow circulation pump 204, which is regulated by the temperature of the mixture consisting of both the mixture to be treated by oxidation, the oxidizing gas and the fraction of liquid coming from the reactor, and which is hot. The inlet temperature of the mixture in the reactor is between 150 and 250 ° C, and preferably between 130 and 180 ° C. The operating pressure of the mixture at its entry into the reactor is advantageously between 70 and 200 bar, and preferably between 80 and 150 bar. The DOC concentration of the cold mixture to be treated is between 80 and 400 g-COD / l and preferably between 200 and 350 g-COD / l. The concentration of mineral matter is between 0 and 10% w / w in the cold mixture to be treated. The oxidizing gas is either oxygen or air. The circulation pump 204 brings into the circuit a hot fraction recovered from liquids coming from the reactor 102. The control of the phenomena of deterioration of the pumping at high temperature is ensured by the constant measurement of the differential pressure between the inlet and the outlet of the reactor. pump with a precision close to 1 bar.

The preheating obtained is substantially the same as that which is achieved by the preheating exchanger 102 of the embodiment of FIG.

The inlet temperature of the mixture in the reactor is between 150 and 250 ° C, and preferably between 30 and 180 ° C. The operating pressure of the mixture when it enters the reactor is advantageously between 60 and 200 bar, and preferably between 80 and 160 bar. The DOC concentration of the cold mixture to be treated is between 80 and 400 g-COD / l and preferably between 150 and 350 g-COD / l. The concentration of mineral matter is between 0 and 10% by weight in the cold mixture to be treated. The oxidizing gas is either oxygen or air.

A circulation pump brings into the circuit a hot fraction recovered from liquids from the reactor 102. The deterioration phenomena of the pumping at high temperature are controlled by the constant measurement of the pressure differential between the inlet and the outlet of the pump. with a precision close to 0.1 bar. The process involves extracting carbon dioxide produced during a wet oxidation reaction from organic waste. These oxidizable wastes are transformed into an aqueous waste mixture, and their oxidation produces large quantities of carbon dioxide which can be used for various industrial applications. An oxidizing gas is introduced into the aqueous waste mixture, said mixture is preheated with said oxidizing gas resulting from the oxidation reaction in an oxidation reactor, at temperatures sufficient to oxidize said oxidizable materials contained in said aqueous waste mixture. the treated residues are then cooled in a heat exchanger and the residual liquids are separated from the non-condensable residual gases, finally the carbon dioxide is isolated and stored in suitable containers as a pressurized liquid. Said industrial use may concern the food industry, the chemical industry or other industrial sectors, since carbon dioxide has many applications in many technical fields. The collection of carbon dioxide helps to reduce the greenhouse effect, knowing that this gas occupies an important place with regard to the warming of the Earth's atmosphere. The embodiment according to Figure 2 can significantly reduce the cost of the installation by removing one of the heat exchangers present in the installation according to Figure 1. It is understood that various alternative embodiments could be imagined. The shape of the elements could be varied according to the specific needs of a processing unit and the objectives sought for the treatment of a particular composition of waste. The variants imagined do not go beyond the scope of the obvious modifications for those skilled in the art and are within the scope of the present invention defined by the appended claims.

Claims

1. Process for recovering carbon dioxide produced during a wet oxidation treatment from an aqueous mixture of waste containing organic matter, optionally mixed with mineral matter, bio-mineral material organic resins or any other oxidizable substance;

said method comprising a first step during which an oxidizing gas is introduced into said aqueous waste mixture, said aqueous waste mixture is preheated and said oxidizing gas is carried out, said wet oxidation reaction is carried out in an oxidation reactor at temperatures sufficient to oxidize said oxidizable substances, the treated residues are cooled, the gases generated by said oxidation treatment are separated at least partially from the residual liquids resulting from the oxidation treatment and the gases separated from the liquids are precooled; ;

said process comprising a fourth step during which the pressurized liquid carbon dioxide is separated from the non-condensable gases, and; said process comprising a fifth step during which the produced liquid carbon dioxide is collected,

characterized in that the gases generated by said oxidation treatment of the residual liquids from the oxidation treatment at the outlet of said treatment reactor are removed at least partially, the gases separated from the liquids are transferred to an exchanger of heat in which they are pre-cooled, the pre-cooled gases are moved in a first separator of gas and liquids to separate the gases resulting from the oxidation treatment of the residues liquid, said separate gases are sent into a pressure cooler for liquefying, said pressure being maintained between 60 and 100 bar and preferably between 65 and 73 bar and the temperature between 10 ° C and 35 ° C and preferably between 15 ° C and 31, these gases comprising carbon dioxide generated by the oxidation reaction of the organic materials and non-condensable residual gases, the liquid carbon dioxide under pressure is separated from the non-condensable gases and collects the produced liquid carbon dioxide, without using additional energy.

2. Method according to claim 1, characterized in that transfers at least a portion of the hot residual liquid fraction, resulting from the oxidation treatment at the outlet of said treatment reactor, by pumping by injecting upstream of said reactor of oxidation, directly in the mixture of cold aqueous mixture to be treated before the injection of oxidizing gas, said transfer being carried out in a controlled manner, such that said mixture of aqueous mixture to be treated and oxidizing gas which has been adding said portion of said hot residual liquid fraction to the reactor at said predetermined preheat temperature.

3. Process according to claim 1, characterized in that said hot residual liquid fraction separated from the gases during the oxidation treatment is injected into a feed duct of said aqueous mixture to be treated in said reactor, and the preheating of the aqueous mixture to be treated by wet oxidation and oxidizing gas is carried out by appropriate dosing of said hot residual liquid fraction before the injection of the oxidizing gas.

4. Process according to claim 3, characterized in that said appropriate dosage of said hot residual liquid fraction is carried out by the management of the temperatures of the aqueous mixture to be treated by wet oxidation, the oxidizing gas and said residual liquid fraction. hot from the reactor by injecting a volume of said hot liquids which depends on one hand on its own temperature, and secondly its temperature and the volume of said aqueous mixture to be treated cold and oxidizing gas at the time of injection.

5. Method according to claim 3, characterized in that said determination of said hot residual liquid fraction separated from the gases during the oxidation treatment is carried out by means of a pump controlled by a control unit which calculates the flow rate. injection according to the measured temperatures.

6. Process according to claim 2, characterized in that the preheating is carried out by adding to the aqueous mixture to be treated cold and before the injection of the oxidizing gas a hot fraction of said treated hot residual liquid fraction resulting from the treatment. oxidation to obtain an injection temperature in the injection reactor of between 120 and 250 ° C and preferably between 130 and 180 ° C.

7. Installation (100; 300) for recovering carbon dioxide produced during a wet oxidation treatment, from an aqueous mixture of waste containing organic matter, optionally mixed with mineral substances, bio-mineral materials, organic resins or any other oxidizable substance;

said plant comprising means for supplying an oxidizing gas for introducing an oxidizing gas into said aqueous waste mixture, heating means for preheating said aqueous waste mixture and said oxidizing gas, an oxidation reactor for carrying out said reaction; wet oxidation, at temperatures sufficient to oxidize said oxidizable substances, cooling means for cooling the treated residues, gas separation means for at least partially separating the gases generated by said oxidation treatment residual liquids from the oxidation treatment and cooling means for pre-cooling gases separated from liquids; said plant further comprising conveying means for feeding the pre-cooled gases into a first gas and liquid separator for separating the gases from the oxidation treatment of the liquid residues;

transfer means for sending said separated gases into a pressure cooler to liquefy them, said gases comprising carbon dioxide generated by the oxidation reaction of organic materials and non-condensable residual gases;

capture means for collecting liquid carbon dioxide produced, characterized in that said means for cooling the treated residues consist of a heat exchanger, means for at least partially separating the gases generated by said oxidation treatment by wet process residual liquids from the oxidation treatment, means for transferring the gases separated from the liquids in a heat exchanger and for pre-cooling said gases, a first separator of gas and liquids to evacuate on the one hand the non-condensable gases and the carbon anhydride generated by the oxidation reaction and, on the other hand, the liquids resulting from the condensation in said heat exchanger, a pressure cooler in which the precooled carbon dioxide is liquefied, a second gas and liquid separator for separating pressurized liquefied carbon dioxide from non-condensable gases, and a packaging and storage unit for storing liquid carbon dioxide in containers.

8. Installation according to claim 7, characterized in that it further comprises means for transferring at least a portion of the hot residual liquids from the oxidation treatment at the outlet of said wet oxidation treatment reactor, means for performing upstream of said oxidation reactor, injection and mixing directly into the aqueous mixture to be treated and then to inject the oxidizing gas.

9. Installation according to claim 8, characterized in that it comprises means for performing said injection and said mixture in a controlled manner, such that said mixture of aqueous mixture to be treated and said hot residual liquid fraction to which it is added the oxidizing gas, enter the reactor at said predetermined preheating temperature.

10. Installation according to claim 8 characterized in that said vertical cylindrical chamber (102a) of said oxidation reactor (102) contains a tubular column (102b) open at its end forming an opening (102c) which is provided at the end of a U-bend section opening into an upper zone of said tubular column (102b) for sensing said hot residual liquid fraction generated by the oxidation reaction in said oxidation reactor (102).

11. Installation according to claim 10, characterized in that said opening (102c) of said tubular column (102b) is connected by a conduit for supplying said hot residual liquid fraction generated by the oxidation reaction, to a pump, mounted upstream of said oxidation reactor, and which allows the injection of said hot residual liquid fraction in the feed conduit of said aqueous mixture and this before the injection of the oxidizing gas.

12. Installation according to claim 11, characterized in that said pump is arranged to perform a suitable dosage of said hot residual liquid fraction by the management of the temperatures of the aqueous mixture to be treated by wet oxidation, the oxidizing gas and said hot residual liquid fraction from the reactor by injecting a volume of said hot residual liquid fraction which depends on the one hand the temperature of said injected hot residual liquid fraction, the temperature of the aqueous mixture and the volume of the oxidizing gas at the time of injection.

13. Installation according to claim 12, characterized in that said pump is controlled by a control unit which calculates the flow rate to be injected as a function of the measured temperatures.