Concentrated solution for preserving the integrity and proper functioning of exhaust gas post-treatment devices using technical urea in solution.

Abstract

The invention consists of a concentrated active ingredient solution to be diluted in a technical urea solution used in exhaust gas post-treatment devices for the removal of NOx. The active ingredients included in its composition have the function of reducing crystalline cyanuric acid clumps that obstruct and destroy the SCR, reducing bacterial clumps that constitute harmful contaminants for exhaust gas post-treatment devices, reducing fungal proliferations that constitute harmful contaminants for exhaust gas post-treatment devices and reducing the formation of frost flakes or ice clumps that obstruct and destroy the SCR and constitute harmful contaminants for exhaust gas post-treatment devices.The components of the invention must allow the biodegradability and the absence of ecotoxicity of the invention, whether the invention is considered alone in its concentrated form or diluted in a technical urea solution. The packaging of the invention allows a simple dosage respecting the rules of dilution in a technical urea solution. The invention is presented in the form of a colored solution contained in a self-dosing bottle or not.

Description

Title of the invention: Concentrated solution for preserving the integrity and proper functioning of exhaust gas post-treatment devices using technical urea in solution.

[0001] The present invention is in the form of a concentrated solution, easy to use, at any time and in any place, easy to store and preserve, non-toxic, biodegradable, formulated at more than 99% from products of biological origin. The invention makes it possible to prevent the occurrence of undesirable effects of the use of a urea solution of the "AdBlue" type in devices for the post-treatment of exhaust gases from on-board or stationary Diesel engines, including with more or less long periods of disuse. Prior art

[0002] European and French standards regarding pollution emitted in particular by machines using a thermal engine, are increasingly draconian, with the effect of a significant reduction in emissions harmful to the environment. This fight against said emissions is set to intensify in the coming years to move towards ever fewer of these same emissions. To meet European and French environmental standards, manufacturers of thermal engine machines, particularly diesel, have had to integrate exhaust gas post-treatment devices into their production, which are SCR (Selective Catlytic Reducer or selective catalytic reducer), EGR (Exhaust Gas Recirculation or reduction of exhaust gases by recirculation) and FAP (Particulate Filters). These devices can be installed alone or in combination with varying degrees of efficiency and reliability.

[0003] Nevertheless, in light of the standards in force in Europe and France, SCR post-treatment devices are becoming more popular to the detriment of the other aforementioned devices, particularly in the production of land vehicles with thermal engines. This SCR device consists of reducing nitrogen oxide (NOx) emissions by means of a catalyst containing platinum and palladium, which is placed in the presence of gaseous ammonia. To obtain this gaseous ammonia, the most widespread method consists of vaporizing an aqueous solution of urea, which solution is brought to a temperature between 200°C and 400°C and introduced upstream of the SCR system. This is the device better known as "AdBlue" (registered trademark), a patented and widely used device, mainly used by both individuals and professionals. This urea solution (better known as AdBlue) is a liquid solution specially designed for diesel vehicles. It is composed of 32.5% urea and 67.5% demineralized water and complies with the ISO 2241-1 standard.

[0004] US 5489419 describes a method for reducing pollutants generated during combustion, more particularly NOx, by selective non-catalytic reduction (SNCR), using a NOx reducing agent, generally urea, in aqueous solution.

[0005] US 5645756 proposes to improve the reliability of devices brought into contact with aqueous urea solutions, prepared with water having a significant hardness, due to the presence, for example, of calcium, magnesium, carbonate ions.

[0006] WO 00 / 75643 describes a method for controlling the quantity of a urea solution used in a system intended to reduce NOx, in particular in a combustion process with selective catalytic reduction (SCR). This method consists of incorporating a fluorescent tracer into the urea solution and monitoring the evolution of the signal as a function of time, this fluorescent tracer also being able to have surfactant properties.

[0007] The method which consists of vaporizing an aqueous solution of urea, brought to a temperature between 200°C and 400°C and introduced upstream of the SCR type system (better known under the name "AdBlue"), which results from the patents mentioned above, has been in mandatory use since 2006 on heavy goods vehicles, then optionally on light private and utility vehicles for more than ten years. This device has become widespread to the point that most car manufacturers now offer, in their catalog, at least one vehicle incorporating it.

[0008] The generalization of this device described above now makes it possible to have feedback on its use. This feedback makes it possible to highlight operating drawbacks that could not have been anticipated during its development.

[0009] The most common recurring drawback noted by manufacturers of thermal engines powered by diesel fuel consists of the appearance of deposits in the exhaust pipes before the SCR inlet. These deposits can be significant enough to cause partial or even total blockage of the exhaust pipe and thus create losses in engine efficiency, or even lead to their consequent deterioration or destruction.

[0010] Experience teaches us that at constant injection configuration, the quantity of deposits formed is greater at low temperatures. These deposits, analyzed by manufacturers informed of their negative customer feedback, consist of crystallized cyanuric acid. Drops of urea solution of the "AdBlue" type are deposited on "cold" parts of the exhaust gas filtration circuit. These, not being vaporized or dried due to the insufficient temperature of the surface on which they are fixed, agglomerate (coalescence) and form a liquid deposit with a larger surface area and therefore more adherent. Due to the insufficient temperature of the contact surface, its ammonia residues decompose imperfectly and produce cyanuric acid which, over time, crystallizes.

[0011] This cyanuric acid can certainly sublimate and produce gaseous ammonia again, but this reaction can only occur at very high temperatures, i.e. more than 450°C. Unfortunately, such a temperature can rarely be reached in the entire exhaust pipes, and more particularly in the elbows of the pipes, which are conducive to the formation of these cyanuric acid deposits. These elbows are inevitable and result from the increasingly complex architecture of modern vehicles and machines with thermal engines.

[0012] The phenomenon described above occurs when the distance between the urea injection and the first bend is too short. This type of configuration prevents some of the urea drops from having sufficient time to vaporize and completely decompose into gaseous ammonia. They then stagnate on the wall of the conduit which is at too "cold" a temperature and prevents complete decomposition into gaseous ammonia. Cyanuric acid deposits then form which adhere to the wall. Layer by layer, a plug forms over time.

[0013] By the time engine malfunctions are noticed or detected by the vehicle's diagnostic and maintenance system, it is often too late. The blockage is too large to be "dissolved" and costly intervention is necessary to restore the vehicle's operation.

[0014] The only solution of the prior art, currently available to deal with the problem identified above, consists of producing an “AdBlue” urea solution to which is added, during the production process, an ingredient from the family of polyalkoxylated alcohols having ethoxylated and / or propoxylated groups. This addition during production results in the manufacture of a urea solution which is no longer “AdBlue”. In fact, this urea solution contains an additional ingredient. The sole function of this single ingredient is solely to facilitate the vaporization of the urea solution and correspondingly limit the formation of cyanuric acid on the cold parts mentioned above.

[0015] This prior art solution has several major drawbacks. Firstly, although its composition is more than 99% identical to that of “AdBlue”, it no longer meets any standard, in particular the ISO 2241-1 standard. Its inventor presents it commercially as a competing alternative to “AdBlue”. As a result, it cannot benefit from the worldwide distribution network of “AdBlue”. This prior art solution is therefore too weakly available to be accessible to an average user, whether individual or professional. This user is not able to implement a constant and therefore effective preventive action. It is very difficult to predict exactly when a full tank or top-up of urea solution compliant with ISO 22241-1 (“AdBlue”) must be done and consequently where one will be when this need arises. Let us add to the above that the prior art solution forces the professional user to obtain supplies from a single supplier, which obliges him to terminate the commercial contracts concluded with his previous suppliers and exposes him to a loss of control over his purchasing costs.

[0016] Secondly, the device, previously included in the description of the prior art, "AdBlue", consists of an aqueous urea solution composed exclusively of organic ingredients whose function is to reduce the emission of chemical substances harmful to the environment from exhaust gases. However, the solution of the prior art, described above, introduces into an entirely organic solution a chemical component derived to reduce the formation of cyanuric acid. A potentially polluting product, with low biodegradability, is introduced to "improve" the performance of a depolluting solution. There is a real contradiction and a problematic misuse here.

[0017] Another problem is raised by the most widespread method consisting of vaporizing an aqueous solution of urea, brought to a temperature between 200°C and 400°C and introduced upstream of the SCR type system ("AdBlue"). This problem results from the stagnation of this solution in the pipes and its storage tank, during more or less long periods of non-use of the land motor vehicle. However, feedback from the use of this method shows that the consequences of this stagnation can lead to malfunctions of the systems described above and in particular seizure or blockage of the injector responsible for spraying the solution. These seizure and blockage phenomena are generated by contaminants created during long periods of non-use. Repairs for this type of damage can prove costly.

[0018] Current transport policies in large cities and suburban areas encourage users not to systematically use their thermal engine vehicle, particularly diesel, on a daily basis during their working week, and to favour alternative methods of travel such as the use of public transport, carpooling or even non-polluting means of transport such as bicycles or electric vehicles for urban use. The above therefore results in periods, more or less long, of stopping the vehicle equipped with the urea solution injection system. A lack of use results in a lack of circulation of the urea solution and therefore stagnation which can lead to formation of moss, mold, bacterial and fungal proliferation, but also flakes of frost when the outside temperature is low. Not all vehicles are stored in a closed garage, let alone heated. The problem described above could not be taken into account when developing the most widespread method of spraying an aqueous solution of urea, heated to a temperature between 200°C and 400°C and introduced upstream of the SCR system ("AdBlue"). Firstly, because this device was initially intended for road tractors, which by nature are not intended to remain unused for long periods. Secondly, because when it was widespread for use in light vehicles, both private and commercial, policies for alternatives to the use of these vehicles were still in their infancy or non-existent.To date, there is no prior art document offering any solution to this new problem.

[0019] It follows from the above that a simple solution is needed to enable the user of a machine equipped with a device consisting of vaporizing an aqueous urea solution, heated to a temperature between 200°C and 400°C and introduced upstream of the SCR type system ("AdBlue") to implement a constant, and therefore effective, preventive action, curbing the new problems linked to the use of this technical solution. This solution is proving more necessary than ever in the current context of environmental and transport policies. To be effective, the solution must be able to be added to "AdBlue" from any supplier, be easily stored without constraints, be available in all circumstances and in all locations, be necessarily environmentally friendly, not require any particular technical knowledge to use it and not be dangerous for a user, even a layman.This solution does not exist in the prior art. Presentation of the invention

[0020] The invention is in the form of a concentrated solution, which can be tinted, if necessary, in blue for example, using a neutral dye. 2 liters of the invention make it possible to treat 1000 liters of a urea solution of the “AdBlue” type without altering its primary properties or contravening the requirements of the ISO 2241-1 standard. The invention will prevent the formation of cyanuric acid “plugs”, the appearance of foams, fungi, bacteria and will delay the icing phenomena which occur in the conduits and injectors in the event of prolonged stopping of the vehicle, in particular in cold weather. The invention therefore prevents the formation of currently known contaminants of the SCR device. These contaminants act as “poisons” of the entire SCR device and can cause its dete deterioration or destruction, or the deterioration or destruction of the peripherals necessary to maintain it in optimal operating condition. The invention can be easily handled by a lay user. The formulation of the invention, of more than 99% natural origin, makes it easily biodegradable ( [Fig.l]) and without ecotoxicity (see tables 4 and 5).

[0021] The invention is composed as follows, namely:

[0022] 1 - 70,000 to 90,000 ppm of a component, of plant origin, the preference of the inventor focusing on alkylpolyglucosides. This component will increase the vaporization of gaseous ammonia upon injection and will ideally limit by at least 80% the formation of cyanuric acid-based deposits on the "cold" walls in SCR devices. The above is achieved by reducing the surface tension of the urea solution in which the above-mentioned component is added by means of the invention. The reduction in surface tension is the predominant characteristic for establishing the effectiveness of the invention against the formation of cyanuric acid "plugs". The surface tension of an "AdBlue" type urea solution is 45 nN / m. The invention has a surface tension substantially lower than 30 mN / m, (Table 2). It should be noted that the invention introduced into a urea solution of the “AdBlue” type brings the surface tension of this solution to significantly less than 29 mN / m (Table 3).The invention therefore reduces the surface tension of an “AdBlue” type urea solution by more than a third. Since the alkylpolyglucosides are of natural origin, they allow the invention to be easily biodegradable and without ecotoxicity.

[0023] 2 - 10 to 100 ppm of an anti-foam and mold, the inventor's preference is relating to polysiloxanes, or any other equivalent compound whose impact on the environment and health, in the dosage chosen, is negligible to zero. This component will effectively prevent the formation of moss, mold and germs which could result from the stagnation of the urea solution (for example "AdBlue") in the pipes and storage tank of a thermal engine vehicle during a more or less long period of disuse.

[0024] 3 - 20 to 2000 ppm of a biocide and also antifungal, the preference of the inventor relating to l,2-benzisothiazolin-3-one (BIT), or any other equivalent compound whose impact on the environment and health, in the dosage chosen, is negligible to zero. This component will effectively prevent fungal proliferation and will reinforce the action of the above component against the proliferation of germs. Proliferations which could result from the stagnation of the urea solution (for example "AdBlue") in the pipes and the storage tank of a thermal engine machine during a more or less long period of disuse.

[0025] 4 - 1,000 to 100,000 ppm of an icing retardant, the inventor's preference being relating to Ethanol, or any other equivalent compound whose impact on the environment and health, in the dosage chosen, is negligible to zero. This component will effectively delay the icing of the urea solution (for example "AdBlue") in the pipes and the storage tank of a thermal engine vehicle during a more or less long period of non-use in a cold to very cold environment.

[0026] 5 - 700,000 to 1,000,000 ppm of an excipient, the inventor's preference being on biosmosed or, failing that, deionized water, or any other equivalent compound whose impact on the environment and health, in the dosage chosen, is negligible to zero. This excipient designates a substance which is not active. Its role is nevertheless important since it gives the invention the liquid aqueous form. All this while avoiding chemical interactions, in particular with the active ingredients listed above. Deionized water is equivalent to osmosis water. However, biosmosed water is "purer" (or has fewer minerals) than deionized water. The hardness of osmosis water is 0, for comparison, for tap water, it is around 60°F. This hardness depends on the concentration of calcium and magnesium.

[0027] By ppm is meant, in the broad sense of the term, one milligram per liter. Even if it is an abuse of language, because the liter (unit of volume) is not equivalent to the kilogram (unit of mass), this abuse of language is common and accepted by usage. Furthermore, the ppm is not a concentration but a ratio, that is to say a dimensionless quotient, like a percentage.

[0028] Surface tension is measured in millinewtons per meter mN / m. It is defined as the force that must be applied to the unit length along a line perpendicular to the surface of a liquid in equilibrium to cause the extension of this surface, or as the work exerted by this force per unit area. In the case of a drop of liquid A within liquid B, the energy is minimal when the surface area is minimal. The shape corresponding to the smallest possible surface area is a sphere. This is why water drops have a shape close to that of a sphere. If two drops meet, they will merge and thus form a single drop (coalescence), and this is to minimize the surface tension. The lower the surface tension value in mN / m, the less the drops are subject to the coalescence phenomenon.The overall energy of the interface depends only on the interface, the droplets of urea solution of the "AdBlue" type do not agglomerate on the surface of the SCR filter or on the surface of a pipe, their contact surface (interface) is low and the liquid therefore does not stagnate on the surface of the said filter or the pipes which prevents the formation of cyanuric acid deposits likely to crystallize and therefore create obstructing crystalline clusters.

[0029] The invention is prepared in the usual manner by mixing its constituents, preferably at room temperature, typically in a temperature range of generally from 10 to 60°C.

[0030] Components soluble in water, more particularly at room temperature, are exclusively used.

[0031] For reasons of speed and ease of mixing the invention with a urea solution of the “AdBlue” type, the inventor prefers to avoid pasty and / or solid components which could alter the aqueous form and solubility of the invention.

[0032] Preferably, the solution used for the invention allows the AdBlue with which it is mixed to comply with the ISO 22241-1 standard with regard to the quantities indicated in Table 1 of said standard: aldehydes, insoluble matter, phosphate, calcium, iron, copper, zinc, chromium, nickel, aluminium, sodium, potassium, and in general does not contain any element and / or component in such a quantity that it is likely to be a poison for the SCR catalyst.

[0033] Table 1 of the above-mentioned ISO 22241-1 Standard, “examples of recommended components”: [Tables 1] Steel alloys with a high Cr-Ni and Cr-Ni-Mo (Chrome nickel or Chromomolybdenum nickel, editor's note), for example in accordance with EN 10088-1, EN 10088-2 and EN 10088-3 (Metallurgical standards, Editor's note) or steel 304 (S30400, steel used in the automotive industry, Editor's note), 304L (S30403, same as above, Editor's note), 316 (S31600, same as above, Editor's note) and 316L (S31603, same as above, Editor's note) in accordance with ASTM 240, ASTM 276 and ASTM A312 (Standards governing the composition of the above-mentioned Cr-Ni and Cr-Ni-Mo steels, Editor's note) Titanium Alloys containing: Ni-Mo-Cr-Mn-Cu-Si-Fe (Nickel, Molybdenum, Chromium, Manganese, Copper, Silicon, Fe, Editor's note) conforming to ASTM 276 standard Polyethylene without component Component-free polypropylene Polyisobutylene without component Perfluoroalkoxyl alkane, (PFA) component-free Polyfluoroethylene (PFE) component-free Polyvinylidenefluoride (PVDF), component-free Polytetrafluoroethylene (PTFE) component-free Vinylidenefluoride copolymers, component-free Note 1: The above sequence does not constitute a ranking of recommended components. Note 2: Plastic-based components may contain a quantity of various components used in their manufacturing process or to give them specific properties. These components may contaminate AUS 32 (designation of the urea mixture, Ed.). For this reason, it is recommended that special care be taken in testing AUS 32 for contamination by these components contained in plastic-based components in direct contact with AUS 32.

[0034] The invention and its components must not interact with the components listed in the table above in amounts such that the invention or its components are likely to be a poison to the SCR catalyst.

[0035] The inventor retains a concentrated form, self-dosed by means of its container, of the invention for greater stability, use without loss by splashing and without dosage error, as well as easy and space-saving storage. The small containers will allow space-saving storage on board the motor vehicle. thermal system concerned. The user of the invention can easily obtain an aqueous urea solution of the "AdBlue" type commercially, from the reseller or manufacturer of his choice, or which he has available, and can, anywhere and at any time, treat it with an effective preventive aim, without interruption, and finally without changing his purchasing habits or suffering additional supply constraints. Larger containers will be reserved for use by automotive professionals or road hauliers, for example.

[0036] Table 2 Surface tension measurement invention alone: [Tables 2] Sample Measure 1 Measure 2 Measure 3 Average VG Blue 10073 PV-AS 22-0380-001 29.6 28.9 29.0 29.1

[0037] The results show good reproducibility of the values ​​recorded with an average surface tension of 29.1 mN / m.

[0038] Table 3 Surface tension measurement invention incorporated into AdBlue: [Tables3] Sample Measure 1 Measure 2 Average AdBlue + 0.2% VGBlue PV-AS 22-0213 28.8 28.9 28.9

[0039] The results show good reproducibility of the values ​​recorded with an average surface tension of 28.9 mN / m.

[0040] [Fig-1]: Under the experimental conditions of the test:

[0041] The VG Blue product is considered to be readily biodegradable.

[0042] The VG Blue product is 93% biodegradable after 28 days of testing.

[0043] The term “readily biodegradable” is applicable to pure substances.

[0044] Table 4 ECOTOXICITY on Daphnia: [Tables 4] Test Effect Toxicological descriptors VG BLUE Daphnia Immobilization EC 100-2411 >100 mg / L EC 50-2411 >100 mg / L EC 20-2411 >100 mg / L EC 10-2411 >100 mg / L EC 0-24h 100 mg / L Daphnia Immobilization EC 100-4811 >100 mg / L EC 50-4811 >100 mg / L EC 20-4811 >100 mg / L EC 10-48h >100 mg / L EC 0-48h 100 mg / L Results in mg / L of VG BLUE for the immobilization test

[0045] In parentheses: 95% confidence interval of CErX % (if calculable)

[0046] ECOTOXICITY on unicellular green algae NF EN ISO 8692, results of toxicological descriptors [Tables 5] Test Effect Eco-toxicological descriptor VG BLUE Algae Growth rate CEr50-72h >100 mg / L CEr20-72h >100 mg / L CErlO-72h >100 mg / L CSEO-72h 100 mg / L Results in mg / L of VG BLUE for the growth inhibition test

[0047] In parentheses: 95% confidence interval of CErX% (if calculable)

[0048] Validity criteria

[0049] Average growth rate of the control at 72 hours greater than 1.4 dl (2.50 d-1)

[0050] Coefficient of variation of the growth rate of the control solutions less than 5% (2.51%)

[0051] Variation in pH less than 1.5 units in the control containers after 72 hours of incubation (-0.2 pH units).

[0052] Reference substance carried out from March 14 to March 17, 2022: (2.5 DCP) EC50r-72h = 3.9 mg / L (value in accordance with the results previously obtained by the laboratory and between 2.08 mg / L and 4.68 mg / L - acceptable range of sensitivity of P.subcapitata algae as defined in standard NF EN ISO 8692: 2012).

[0053] In summary:

[0054] The invention consists of a solution of active ingredients mixed in biosmosed water, the invention is a concentrate, to be diluted in a technical urea solution used in exhaust gas post-treatment devices for the removal of Nox, the active ingredients entering into its composition have the function of reducing crystalline clusters of cyanuric acid obstructing and destroying the SCR, reducing bacterial clusters which constitute harmful contaminants for exhaust gas post-treatment devices, reducing fungal proliferations which constitute harmful contaminants for exhaust gas post-treatment devices and reducing the formation of frost flakes or ice clusters obstructing and destroying the SCR and constituting harmful contaminants for exhaust gas post-treatment devices, the components of the invention allow the biodegradability and the absence of ecotoxicity of the invention,whether the invention is considered alone in its concentrated form or diluted in a technical urea solution, the packaging of the invention allows simple dosing respecting the rules of dilution in a technical urea solution.

[0055] The invention is therefore a concentrated liquid solution intended to be easily diluted in any aqueous urea solution meeting the ISO 22241-1 standard, which urea solution is brought to a temperature of between 200°C and 400°C and introduced and vaporized, by means of an injector, upstream of the SCR type exhaust gas post-treatment system fitted to engines running on diesel or gas oil.The invention is obtained by mixing in biosmosed water or, failing that, deionized water, constituting an aqueous excipient free from impurities, a first component whose function is to reduce the surface tension of a solution into which it is directly or indirectly introduced, this component necessarily has the same degree of biodegradability and absence of ecotoxicity as a compound of plant origin, a component whose function is to delay the formation of moss, pioneer plants and mold, a component whose function is to delay the formation of organisms of the kingdom of fungi or mycetes or even mycota, and a component whose function is, once added to a liquid, even in the presence of a strong dilution, to make it freezable to a lower degree. All of the components and the excipient constituting the invention must, in the concentrated form, or diluted in a technical urea solution, be biodegradable and non-ecotoxic.

[0056] The invention is a solution according to claim one of the embodiments preceding which is characterized in that its composition presents a biodegradability and a non-ecotoxicity comparable to a compound of plant origin and a reduction in surface tension greater than or equal to that generated by a non-biodegradable and / or ecotoxic chemical compound.

[0057] The invention is a solution claiming one of the preceding embodiments which is characterized in that it is in the form of a concentrated liquid solution to be diluted, at a rate of 2 liters of the invention to treat 1000 liters of a technical urea solution meeting the ISO 22241-1 standard, the invention, by its concentration, therefore has a very small volume compared to the quantity of technical urea solution to be treated, is therefore easy to store, takes up little space, can be easily transported on board a diesel thermal engine machine equipped with the SCR system,

[0058] The invention does not alter or modify the action of the urea solution complying with ISO Standard 22241-1 and does not alter or modify the normal operation of the SCR system.

[0059] A high yield concentrated solution wherein the aqueous solution is as defined in claim one of the preceding embodiments.

Claims

Claims

1. A method of using a concentrated solution for the removal of Nox, the reduction of crystalline cyanuric acid clumps clogging and destroying the SCR, the reduction of bacterial clumps which constitute harmful contaminants for exhaust gas aftertreatment devices, the reduction of fungal proliferations which constitute harmful contaminants for exhaust gas aftertreatment devices and the reduction of the formation of frost flakes or ice clumps clogging and destroying the SCR or constituting harmful contaminants, for exhaust gas aftertreatment devices characterized in that said solution is diluted in a technical urea solution used in exhaust gas aftertreatment devices for the removal of Nox, said concentrated solution is characterized in that it consists of a solution of active ingredients mixed in biosmosed water,which has a hardness of 0°F, also the concentrated solution is composed as follows: - 70,000 to 90,000 ppm of a component selected from alkyl-polyglucosides. - 10 to 100 ppm of an anti-foam and mold, preferably polysiloxane types, - 20 to 2000 ppm of a biocide and also antifungal, preferably 1,2-benzisothiazolin-3-one (BIT), or any other equivalent compound - 1,000 to 100,000 ppm of an icing retardant - 700,000 to 1,000,000 ppm of an excipient, preferably biosmosed water.,

2. Method of use according to claim 1 characterized in that a concentrated solution according to claim 1 is formulated to be diluted, at a rate of 2 liters to treat 1000 liters, any technical urea solution used in exhaust gas post-treatment devices for the removal of Nox from a diesel thermal engine.

3. Process for the preparation of a concentrated solution comprising a solution of active ingredients mixed in biosmosed water, the solution concentrate consisting of the following: - 70,000 to 90,000 ppm of a component chosen from alkyl- polyglucosides. - 10 to 100 ppm of an anti-moss and mold, preferably of polysiloxane types, - 20 to 2000 ppm of a biocide and also antifungal, preferably 1,2-benzisothiazolin-3-one (BIT), or any other equivalent compound - 1,000 to 100,000 ppm of an icing retardant - 700,000 to 1,000,000 ppm of an excipient, preferably biosmosed water. characterized in that the solution is self-dosed in a container, preferably self-dosing, to allow the method of use according to claim 2.

Images