The present invention relates to a novel composition, its use, and the method based on the conveying of said composition through a fluid, in liquid phase or in vapor phase, for the decontamination and cleaning of systems containing hydrocarbons in petrochemical plants, such as refining plants or storage tanks.

STATE OF THE ART

Refining plants, petrochemical plants, storage tanks and hydrocarbon- containing systems in general are periodically subjected to maintenance and cleaning. These operations are required because of the depositing of organic and/or inorganic substances in the systems, with the entailed efficiency loss and reduction in production.

Apart from increasing and/or restoring the system efficiency, cleaning is also carried out to remove hazardous and pyrophoric substances from the apparatuses, thereby enabling inspections by technical staff.

The cleaning process is applied for plant sections in shifts. Therefore, plant sections face turnaround for the entire duration of the process, becoming unusable. This affects general plant revenue. Therefore, it is important that cleaning applications be performed effectively and over short times.

During turnaround, plants are subjected to decontamination, i.e., to a washing process assisted by steam and specific products, called chemical steaming. The products used in this procedure may be compositions based on mixtures of surfactants, as described by Patent US5462607, deriving from International Patent Application PCT WO2016/170473 A1 , or based on terpenes, as reported in USA Patent Application US2004/0238006 A1. Specifically, this latter document describes a non-aqueous composition based on terpenes and non-ionic surfactants that is conveyed by steam and used for cleaning refinery and petrochemical plant apparatuses.

The compositions described in the literature have a high ecotoxicological impact in case of dumping or intended sending to treatment (purification) systems, such as the wastewater system and, more specifically, the activated sludge system. Wastewater plants are developed chiefly based on the amounts of effluents (sewage) to be treated, the typology of pollutants present and the disposal restrictions in force.

One type of wastewater treatment is the biological process of activated sludge treatment, which is an aerobic-type treatment conducted by a more or less prolonged aeration of sewage inside a biological reactor in the presence of a microbial population (biomass), aimed at reducing organic matter (in particular, Carbon and Nitrogen) concentration. In activated sludge plants with a suspended biomass, the bacterial populations accountable for the purification process are present in the form of floe kept in suspension through air insufflation (if reactors are aerated) or by mixer (if reactors are anoxic or anaerobic). The active biomass consists of numerous microorganisms (bacteria, protozoa, metazoa, rotifera, etc.) continuously reproducing inside the reactor as a result of biochemical reactions of organic carbon degradation and nutrient utilization, enabling the consequent synthesis of new cell material. In short, the result obtained with an activated sludge plant is the elimination of the biodegradable organic matter by its transformation into inert material and in a concentrated sludge solution of organic matter that must be subjected to further treatments prior to final disposal.

The presence, in the sewage being inlet, of chemical substances toxic to the activated sludge is the cause of microbial population mortality and loss of wastewater plant efficiency.

Moreover, during a cleaning application the formation of stable emulsions among condensed steam/product/hydrocarbon can occur; said emulsions can entail a negative impact on the wastewater plant, reducing its efficiency and polluting the activated sludges, or reducing the system efficiency in case of refining plants, in which both the recovery of the hydrocarbon disposed of by the system, scrubbed in order to reuse it in production, and the concomitant clarification of water for its sending to the wastewater plant are often required.

The chemical products usually applied in cleaning processes are compositions based on mixtures of surfactants that, when conveyed in water, form foam. Foam has a mechanical and chemico-physical effect fostering deposits removal from the surfaces to be cleaned. However, when foam is persistent and present also in the sewage to be sent to the wastewater plant, flow reduction, plant efficiency reduction and a negative impact on activated sludges occur. Moreover, under high-temperature conditions (122-248 °F), the chemical compounds commonly used for cleaning might undergo thermal degradation, with the entailed formation of products corrosive to metals that constitute the plant. Also a product overdosage in the system might cause corrosion phenomena, in particular when the chemical products used contain acidic substances such as dispersants. Moreover, the chemical structure of hydrocarbons in a plant is such as to require the use of various products, each one targeted at the removal of specific hydrocarbons. Therefore, it is important that the products added into the system, concomitantly and, in some cases, with the same dosage, be chemically compatible thereamong in order to prevent the formation of undesired deposits and reaction byproducts.

SUMMARY OF THE INVENTION

The present invention relates to a novel composition developed to overcome the most common technical problems associated with the use of the current chemical products on the market for the decontamination and cleaning of hydrocarbon- containing systems. In particular, the present invention provides an organic/solvent- based chemical composition improved, compared to those currently in use, both in terms of hydrocarbon solubilization ability and of impact on the wastewater plant, and ecotoxicological impact.

Object of the present invention are: a composition comprising a) one or more compounds belonging to the class of N, N- Alkyl amides and one or more compounds belonging to the class of terpenes; and b) a solvent comprising water and at least one glycol or a derivative thereof; the use of said composition for the decontamination and cleaning of systems containing hydrocarbons; and a method for decontamination and cleaning of hydrocarbon-containing systems, comprising conveying (introducing) said composition into said systems.

GLOSSARY

In the present description, the term “hydrocarbon” (HC) has the meaning commonly used in the literature, therefore denoting organic compounds containing only carbon and hydrogen atoms. Three classes of hydrocarbons can be defined: aliphatic hydrocarbons, which have a linear and/or branched open chain of carbon atoms and therefore are also termed acyclic, and can be saturated and unsaturated; alicyclic hydrocarbons, also termed naphthenic hydrocarbons, which are cyclic, i.e., closed-chain; aromatic hydrocarbons, characterized by the presence of at least one benzene ring.

The term “solvent” in the present description has the meaning commonly used in the chemical literature, therefore denoting a liquid substance dissolving a solid, liquid or gaseous solute, giving rise to a solution.

The term “cosolvent” in the present description has the meaning commonly used in the chemical literature, and therefore of one of the components of a solution, generally the one present in greater amount along with the solvent, or the one that, in its pure state, appears in the same aggregation state as the solution. the term “surfactant” has the meaning commonly used in the literature, and indicates substances having the property of lowering the surface tension of a liquid, facilitating surface wettability or miscibility between different liquids. In general, they are organic compounds with a polar “head” group, and a nonpolar “tail”; the compounds with said features are more generally referred to as "amphiphilic" or "amphipathic".

The “asphaltenic crude” in the present invention is a crude containing a > 5% w/w percentage of asphaltenes. Asphaltenes are a class of high molecular weight compounds contained in crude oil. They are solids at ambient temperature with a granular appearance and dark brown to black color. They are substances insoluble in n-heptane and soluble in benzene and/or toluene.

The "asphaltenic crude" considered is characterized by having 17-20% of Asphaltenes and a Pour Point of 12°C . The Pour Point (PP) is the minimum temperature at which the hydrocarbon is fluid (ASTM D97-17 and D5853-2017-05). The term "performance" has to be understood as the HC solubilization ability, or the ability to have a good impact on the wastewater plant, a good ecotoxicological impact, or both.

The term “test piece” refers to a sample of a given metal with an exposed metal surface. The term “topping column residue” in the present invention is a hydrocarbon which accumulates on the bottom of the topping column and proves to be of typically aromatic composition.

By the term Benchmark BM, in the present invention, it is meant a class of commercial products such as CHIMEC 2216 or Zymeflow 657 (products available on the market) of reference, to which the performance and the applicative characteristics of the novel products are compared. Said commercial products are based on active ingredients such as alkyl amine oxide in water.

By the term Benchmark BM W, in the present invention there are meant the versions of the same commercial products mentioned above, having a freezing temperature of < -20°C. To attain such performances at low temperatures, BM W products compositions commonly contain a certain amount of glycol.

The abbreviations DEK 291, DEK 293 and DEK 296 in the present invention denote different mixtures of the same active ingredients, falling within the ranges reported below:

Glycol 30-80% w/w

Water 5 -30% w/w

N,N-alkyl amide 5-30% w/w

Terpene 0.5-5% w/w

Lauryl amine oxide 0 - 20% w/w

All mixtures are organic-based chemical compositions in solvent and water.

The term N,N-alkyl amide, for the purposes of the present description, denotes N, N- alkyl amides wherein the alkyl group is a linear or branched chain of carbon atoms with a number ranging from Ci to Ci ₈ .

The term “derivative” referred to glycols, for the purposes of the present invention, comprises glycol ethers.

DETAILED DESCRIPTION OF THE FIGURES

Figure 1. Shows Carbon steel C1018 test pieces uniformly covered by asphaltenic crude prior to Jar test start (see Examples Section).

Figure 2. shows said Carbon steel C1018 test pieces uniformly covered by asphaltenic crude, immersed in the solutions tested at the end of the Jar test. In particular, the test pieces are immersed in solutions containing 1) 1.5-2.5% BM; 2) 0.2-1% DEK 291; 3) 0.5-1.5% DEK 293; 4) 0.5-1.5% DEK 295 or 5) 1.5-2.5% BM W (see Examples Section). Figure 3. shows a system designed and assembled to conduct the Steam-Condense Phase test, i.e. a system able to simulate an application under chemical steaming, i.e. of reproducing the stage of application in steam phase or in condense (condensate) phase. The system is comprised of a glass column, a condenser, a condensatecollecting flask, a control unit and a product nebulizing/adding system (see Examples Section).

Figure 4. shows a Carbon steel C1018 test piece, previously uniformly covered by asphaltenic crude following a Steam-phase application of the product related to the invention, DEK 293 (see Examples Section).

Figure 5. shows a Carbon steel C1018 test piece uniformly covered beforehand by asphaltenic crude following a Condense-Steam-phase application of the product related to the invention, DEK 293 (see Examples Section).

DETAILED DESCRIPTION

The present invention refers to a composition for the decontamination and cleaning of systems containing hydrocarbons, comprising organic components able to solubilize the hydrocarbons and a solvent conveying the components able to solubilize the hydrocarbons into said systems through an aqueous or vapor (steam) phase.

Specifically, the composition object of the present invention comprises a) one or more compounds belonging to the class of N,N-Alkyl amides and one or more compounds belonging to the class of terpenes; and b) a solvent comprising water and at least one glycol or a derivative thereof.

The novel compounds belonging to the class of N,N-alkyl amides, contained in said composition, are new chemistry in vapor-phase applications; they were singled out for their good solvent power for hydrocarbon substances, being conveyable by the steam and being suitable from a toxicological standpoint to applications both in vapor phase and of organic nature. In fact, compounds belonging to the class of N,N-alkyl amides (NNAAs) are highly biodegradable compounds and with a high solvent power for hydrocarbons. Such compounds belonging to the class of N,N-alkyl amides have been classified as readily biodegradable based on specific tests, termed OECD tests, aimed at assessing and standardizing the biodegradability of organic compounds.

In one embodiment of the invention, said N, N-Alkyl amides can be alkyl amides wherein the alkyl group is a linear or branched chain of carbon atoms with a number ranging from Ci to Ci ₈ .

In a particular embodiment, said N, N-Alkyl Amides can be selected from one or more of N,N dimethyl 9-decenamide, N,N dimethyl decan-1-amide, N,N dimethyl octan- 1-amide and N,N dimethyl decan-1-amide, or mixtures thereof; and wherein the compound belonging to the class of terpenes is selected from terpineol, D-limonene and Dipentene.

Terpineol and D Limonene are individual identified compounds. Dipentene is a mix of plural terpenic structures. The terpenes in the mix can be individual ones or more than one. Preferred NNAAs are the two N,N dimethyl 9-decenamide, N,N dimethyl decan-1 -amide, individually or a mixture of the two.

As described in the experimental section, for instance, NNAAs with a >Ci ₈ chain of carbon atoms, obtained a 64% value in the OECD 301 B test. As a rule, the active ingredients used in the products used in the prior art have a much lower biodegradability percentage (> 20%); having an active ingredient highly effective and with a high biodegradability enables the Inventors to assume a product easily disposable through the wastewater disposal plant.

The Inventors have surprisingly discovered that the compounds belonging to the class of N,N-alkyl amides as defined in the present description are characterized by a higher solvent capability compared to other compounds commonly used for the cleaning of hydrocarbon-containing systems; in fact, as reported in Table 1 , N,N-alkyl amides considered in the study (NNAAs with a <C _i8 chain of carbon atoms) have a high Kauri- butanol (Kb) value. The Kb value is an international, standardized measure of solvent power for a substance, governed by ASTM D1133 test; therefore, the higher the Kb, the higher the activity and the ability of the solvent being examined to dissolve hydrocarbons.

Table 1 Solvent power of more commonly used chemical compounds and of IN, IN alkyl amide

* Kb value singled out by ASTM D1133-02 test (Standard Test Method for Kauri- Butanol Value of Hydrocarbon Solvents). The N,N Alkyl Amides tested and considered in Table 1 prove to be non-flammable (H226), are not carcinogenic (H350), are not suspected carcinogenic (H351), are not toxic for the reproduction apparatus (H360D) and are not mutagenic for germ cells (H340). These molecules, therefore, though having a Kb lower than other solvents indicated in Table 1 , do not have the H-sentences indicated, unlike: N Methyl 2 Pyrrolidone, proves to be toxic for reproduction (H360D); methylene chloride, proves to be H351 (suspect carcinogen);

D Limonene and xylene, prove to be flammable (H226) therefore with a handling more difficult to manage; benzene is H340 (germ cell mutagen) and H 350 (carcinogen). According to the present invention, the solvent used is a solvent comprising water and at least one glycol or a derivative thereof.

In one embodiment applicable to all of the abovedescribed embodiments, said glycol can be an n-ethylene glycol or an ether thereof.

In a further embodiment, said glycol or derivative thereof can be selected among monoethylene glycol, propylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol monomethyl ether or mixtures thereof.

In one embodiment applicable to all of the abovedescribed embodiments, the composition of the present invention could further comprise an oxidizing agent. Said oxidizing agent could be of organic and/or inorganic nature and, preferably, able to reduce the pyrophoric hazard from iron sulfide.

Said oxidizing agent could be, e.g., an alkyl amine oxide and/or peroxides.

Non-limiting examples of suitable alkyl amine oxides that may be comprised in the composition of the invention can be lauryl dimethyl amine oxide, trimethyl amine oxide or N,N-dimethyl decylamine N-oxide.

Peroxides commonly used in the field, such as, e.g., sodium percarbonate, sodium perborate and hydrogen peroxide, could be used.

According to one embodiment, the composition of the invention could comprise

Glycol 30-80% w/w Water 5 -30% w/w N,N-alkyl amide 5-30% w/w Terpene 0.5-5% w/w Oxidizing agent 0-20% w/w to a total volume of 100%.

Non-limiting examples of embodiments of the composition as defined above, forming part of the present invention, are provided hereinafter.

DEK 291 composition water 10-20% w/w glycol 60-80% w/w

N, N alkyl Amide 10-25% w/w terpenes 0.5-3% w/w;

DEK 293 composition Water 8-10% w/w, glycol 60-80% w/w,

N, N alkyl Amide 5-25% w/w, terpenes 0.5-3% w/w,

Alkyl amine oxide 0-20% w/w;

DEK 296 composition water 10-20% w/w, glycol 50-70% w/w,

N, N alkyl Amide 10-25% w/w; terpenes 1-3% w/w

The composition object of the present invention, in any one of the abovedescribed embodiments, can be used for decontamination and cleaning of systems containing hydrocarbons. Therefore, object of the invention is the use of the composition of the invention according to any embodiment described and/or claimed for decontamination and cleaning of systems containing hydrocarbons.

Said use can be, e.g., applied to the decontamination and cleaning of hydrocarbon-containing systems such as refining plants, petrochemical plants, storage tanks and Oil & Gas systems in general. The present invention also relates to a method of applying said composition for decontamination and cleaning of systems containing hydrocarbons, comprising:

Adding the composition according to the invention, i.e. as defined in any embodiment provided in the present description, in the examples and/or in the claims, into said systems.

In one embodiment, said composition according to the invention can be added to a fluid in an aqueous liquid phase or conveyed directly with a vapor (steam) phase, at the typical concentrations of 0.5 - 10 %.

The composition can, e.g., be introduced into the system to be decontaminated through lateral ports or from the highest point of the system, obtaining a “shower” effect allowing to recover the washing fluid and the contaminants from the bottom, with a single passage or with a recirculation. According to another embodiment, it is possible to fill the system to be decontaminated with a volume of composition according to the invention and water of about 1/3 of that of the unit, and by subsequently insufflating steam from the bottom. The contaminated fluid is sent to wastewater treatment or into a tank containing products to be disposed of.

An example of “system to be decontaminated” according to the present description is a hydrocarbon-containing system and may be represented, without however being limited thereto, by plants (e.g., refining ones), storage tanks or parts thereof. Therefore, the composition can be applied with the aid of steam (Chemical Steaming) and/or of water. As described in detail in the Examples section, the embodiments DEK291, DEK293 and DEK296, selected with the Jar test, were in fact subsequently monitored and tested under chemical steaming. Initially, a system able to simulate an application under chemical steaming (shown in Figure 3) was set up, thereafter the composition conveying by the steam was assessed, whereas in the final tests the efficiency of the novel composition was compared to CHIMEC benchmark (BM and BM W) products, both in steam phase (as shown in Figure 4 and described in detail in the Examples section) and in Steam-Condense phase (as shown in Figure 5 and described in detail in the Examples section).

Therefore, it is possible to distinguish two modes for conveying said composition for decontamination and cleaning of systems containing petroleum hydrocarbons. Specifically: 1. Application through liquid phase

The method for decontamination and cleaning of hydrocarbon-containing systems can envisage the conveying of said composition into said systems through a liquid-phase fluid that, therefore, can be aqueous. Moreover, said fluid that will be used for plant decontamination and cleaning can be recirculated into the unit to be decontaminated along with said composition, with the aid of specific pumps. Alternatively, or concomitantly, the aqueous fluid added with the composition can be directed from the top of the system to be treated, through the aid of a syphon, thereby obtaining a shower effect. In each case, the wastewater is then discharged by the system from the bottom and sent to any treatment or segregation sections.

Through this method for decontamination and cleaning of said system, both the chemical action of the composition and the mechanical effect given by water turbulence in the system are exploited. 2. Application through vapor phase

The method for decontamination and cleaning of hydrocarbon-containing systems envisages the conveying of said composition into said systems through a vapor-phase (steam-phase) fluid. The additive-charged fluid of the composition is saturated steam. For saturated steam generation, a temperature of from 100°C to 160°C and a pressure set from 2 to 6 Bars will be used. The additive-charged saturated steam of the composition will be used for cleaning through its introduction into the system from the bottom, so that the nebulized/added composition be directed/conveyed by steam into the system.

Through this method for decontamination and cleaning of said system, both the chemical action of the composition and the mechanical effect of steam are exploited.

Examples intended to illustrate, in a non-limiting manner, the invention and the tests carried out in order to assay the efficiency thereof are provided hereinafter.

EXAMPLES Jar Test

Test for measuring hydrocarbons (HC) solubilization ability (performance) under laboratory conditions. The Jar test was initially carried out to test and single out the composition and the embodiments thereof, and to further check any formation of HC/water emulsions.

A solution containing the composition to be tested was mixed with the use of an anchor, at low speed (< 150 rpm), for 2-5 hours, at a temperature of from 90°C to 100°C. Thereafter, Carbon steel C1018 test pieces were uniformly covered by a hydrocarbon (Figure 1). For the Jar test, two hydrocarbon types were tested: i) an asphaltenic crude, and ii) a topping column residue. Crude proved to be the more persistent hydrocarbon, and more difficult to solubilize. As shown in Figure 2, the test piece was then immersed in 200 ml of the solution to be tested. Thereafter: a) visual monitoring of hydrocarbons solubilization ability and emulsion formation; b) measuring of HC concentration in water, then measuring HC amount removed from the test piece, and then further measuring of HC solubilization ability; c) measuring the Chemical Oxygen Demand (COD), which is an indirect measurement of the amount of organic phase and of aqueous phase present in a water sample, 30 minutes after the end of the test; were carried out.

The performance of the composition and of the embodiments thereof was compared by using products present on the market for the decontamination and cleaning of systems, reported below:

Benchmark BM (CFIIMEC 2216 or Zymeflow 657)

Benchmark BM W (versions of the abovementioned commercial products with a <- 20°C freezing point) a) Visual monitoring

A visual assessment of HC amount removed from the test piece following the Jar test allowed to visually single out some preferred embodiments, more performing compared to Benchmark BM products. Specifically, compositions DEK 291, DEK 293, and DEK 296 were selected as more performing.

Moreover, the visual assessment of a possible formation of FIC/water emulsions following the Jar test allowed to rule out the formation of exclusions in case of use of the composition object of the present invention. b) HC concentration measurement

The measurement of HC concentration in water following the Jar test allowed to confirm the higher performance of the three embodiments - 0.5% DEK 291, 1% DEK 293, and 1% DEK 296 - compared to 2% Benchmark BM. Only data pertaining to tests carried out by using test pieces covered by asphaltenic crude are reported, as the latter is more persistent and more difficult to remove compared to topping column residue. In fact, in tests with the topping column residue, all tested compositions, novel and non-novel ones, removed HC from the test piece, not allowing to select and single out the most performing compound/composition.

The oil amount removed from test pieces, i.e. the amount, expressed in mg/I, of HC in water, was determined with spectrophotometric measuring (UV-Vis; at 580 nm), upon preparation of the calibration curve. The results obtained have been reported in Table 2, and confirm that the

Table 2 Measurement of HC in water at the end of the Jar Tests d) Chemical Oxygen Demand (COD) measurement

Aqueous phase COD measurement 30 minutes after the end of the Jar tests allowed to obtain a theoretical estimate of COD contribution by the products. COD represents one of the parameters commonly used for indirect measurement of the content of organic substances present in a water phase. Obtained results have been reported in Table 3 and show that, considering the use percentages, the Benchmark BM is characterized by a lower contribution of COD in the aqueous phase, whereas the three DEK embodiments have an incidence on COD comparable thereamong. Table 3 Aqueous phase COD measurement 30 minutes after Jar tests end.

The COD of solutions containing the composition and the Benchmark products at a 0.5% (v/v) concentration was determined as well. The measurement was repeated 120 minutes after the Jar Test, to check products distribution in water. The results are reported in Table 4 and confirm that the lower COD value is attributable to the BenchMark BM, whereas DEK embodiments have values higher and comparable thereamong. Table 4 Aqueous phase COD measurement 120 minutes after Jar tests end, carried out using the same concentration for all products and embodiments of the composition (0.5%). Chemical Steaming Test

Test for assessing the steam (vapor) phase conveying of the composition object of the present invention. HC solubilization ability by the embodiments related to the invention were tested under chemical steaming.

As shown in Figure 3, initially a system able to simulate an application under chemical steaming was set up. Said pilot experimental system was designed and assembled to attempt reproducing the steam-phase application stage. The system is comprised of:

Glass column, having a steam inlet on the bottom, a product inlet at mid-height, a hook for the test piece at the head, a steam outlet at the head and a condense (condensation) outlet on the bottom. - Condenser, connected to the steam outlet at the column head. Aimed at condensing the steam.

- Flask, for collecting the condensation

Control unit. Aimed at thermostating the column to prevent thermal shocks by steam passage, with the entailed formation of condensate thereof. - Product nebulizing/adding system

Steam, generated and provided by the production boiler, enters from the column bottom at a pressure of 1-2 Bars. The composition to be tested is nebulized and injected at mid-column and conveyed by the steam at the head, where the test piece with the hydrocarbon is positioned. For this test only one type of hydrocarbon was used, i.e. asphaltenic crude, which proved to be the hydrocarbon more persistent and difficult to solubilize. These steam- phase final tests were therefore carried out under pejorative conditions. The test piece comes into contact with the steam/composition stream for about 3-6 hours. Steam and composition are cooled by passing into the condenser, and the condensate is finally collected into the flask.

Thereafter: a) measuring for determining steam- (vapor-) phase conveying of the composition through a direct measurement of components present in the condensates; b) visual assessment of process efficiency under chemical steaming, for visual comparison of the test piece between test start and end of test. c) olfactory impact under Chemical Steaming were performed

The process efficiency, meant as the performance of the composition and of the embodiments thereof under Chemical Steaming, was compared by using Benchmarks BM and BM W. a) Measuring for determining Steam phase conveying

The conveying of the composition and of the embodiments thereof, DEK 291, DEK 293, and DEK 296, by the steam was checked through measuring the compounds, in the collected condensates, present in the compositions. For the detecting of Benchmark BM and BM W concentration the Hach-Lange LCK 331 method was used, whereas for the determining of embodiments DEK 291, DEK 293, and DEK 296 the total nitrogen measuring method, referred to as Kjeldahl method, was used. b) Visual assessment of Chemical Steaming process efficiency

The efficiency of the Chemical Steaming process by conveying of the composition object of the present invention was instead assessed through a visual comparison of the test piece covered by asphaltenic crude hydrocarbon between test start and end of test. In particular, the efficiency was measured by visually assessing the condition of the test pieces both at the end of the steam-phase test (Figure 4) and at the end of the " steam-condense" test (Figure 5). The difference between the two tests lies in the medium used to carry the product into contact with the test piece. In fact, during the steam-phase test, the nebulized composition is conveyed to the test piece exclusively by the steam stream. In this condition, the novel compositions did not produce foam and removed part of the hydrocarbon from the test piece. In the tests defined as "steam-condense phase" the compositions are brought into contact of the test piece by the steam together with condense (condensation). c) Olfactory impact under Chemical Steaming

During steam phase tests, also the olfactory impact of the novel compositions was considered. The aroma proved to be pleasant, though less intense compared to that provided by CHIMEC benchmark BM and BM W products, under the same conditions. The advantage of the novel compositions is that the pleasant smell is provided by a compound that also has good solvent abilities (Terpenes) but is not toxic.

Corrosion test In the composition object of the present invention glycol is present, which has the dual function of making conveyable in water and steam the organic compound able to solubilize hydrocarbons belonging to the class of IN, IN alkyl amide and of terpenes, and of reaching a <-15°C freezing point.

To assess the corrosiveness of said composition, Jar tests in static mode were carried out (reference: ASTM G31/G1) in which the composition in its embodiments, in a Chemical Steaming process, was compared by using the Benchmarks BM and BM W .

The concentrations of the embodiments of the composition object of the invention and of the Benchmark products in demineralized water used were equal to 20000 mg/I, while the metal surface used (test piece) consisting of C1018 was exposed for four days both to demineralized water without compositions and products added (blank), and to demineralized water containing the compositions and products added. Process temperature was of 100°C. Corrosion rate was expressed in MPY (miles per year, mm/y). The results of the corrosion test are reported in Table 4 and have highlighted a corrosivity of embodiments DEK 291 and 293 lower than the Benchmark products (BM and BM W), under the conditions considered.

Table 5 Corrosivity measurement following Jar test in static mode (ASTM G31/G1)

Respirometric tests The method is based on the indirect measurement of the biological activity of an activated sludge through estimate of the oxygen consumed under conditions of aerobiosis and non-limiting substrate (Pagnotta and Tandoi, 1983). The methodology used (reference: ISO 8192,2007-OECD 209) is based on the determination of the inhibiting effect of the compositions being examined, tested at different concentrations, after 0.5 and 24 hours of contact time, towards the respiratory activity of an activated sludge (OUR: oxygen uptake rate). Result expression is provided for in four inhibition classes:

Table 6 Inhibition classes according to ISO 8192 classification, OECD209

The composition DEK 293, object of the invention, belongs to the fourth class related to the power inhibiting the respiratory activity of the activated sludge, regarded as the lower one defined by method OECD 209. It is deemed that all of the various DEK embodiments mentioned in the present invention be equivalent to DEK 293 as to the power inhibiting the respiratory activity of an activated sludge. The compositions being examined are less toxic compared to the Benchmark BM reference product at 500 mg/I, as after 24 hours of exposure the activated sludge exhibits a 47.4% inhibition thanks to the composition being examined, against the 67% obtained with exposure to Benchmark BM. At higher concentrations the novel compositions exhibit an inhibition that can be deemed equivalent to the best benchmark product on the market.

Moreover, during the stage of aerating the activated sludge/experimental product mixture no foam formation is observed. Test results are reported in Table 7.

Table 7 Respirometric and toxicological tests with activated sludges

The present invention therefore refers to a composition, its use, and to a method for decontamination and cleaning of systems containing hydrocarbons based on the conveying of said composition through a liquid-phase or a vapor-phase fluid.

Dosages being equal, the embodiments of the composition have performed a hydrocarbon solubilization ability higher than the other known compositions considered as reference in the study (BenchMark products BM and BM W), and moreover have exhibited a low corrosion rate, as lower than 0.03 mm/y at 100°C in the concentration range equal to 13%. The compositions of the products related to the invention also exhibit a low ecotoxicological impact, as able to inhibit the respiratory activity of the activated sludges by 45% in 24(h) at a dosage > 500 mg/I. This data makes them fall under the lowest class (IV: EC ₅ o >100 mg/I) of ecotoxicity for chemical compounds determined according to method OECD 209. Moreover, they have a low toxicological impact at environmental level, exhibiting an EC ₅ o >100 mg/I in crustaceans, algae and fish. Moreover, when conveyed through water or steam (vapor), they generate neither foam nor stable emulsions in the presence of hydrocarbons. Therefore, a combining of the product with an antifoam agent and/or with a specific product to break up the emulsion is unnecessary, as the sewage exhibits a clear-cut phase separation between water, that will be sent to the treatment plant, and hydrocarbon phase, that could be reused in-plant or adequately disposed of. The composition related to the invention can however be used simultaneously with agents generally used during liquid- and vapor- phase scrubbing. The agents considered in the compatibility test, in a 1 :1 ratio with the compositions related to the invention, are of aqueous matrix, contain oxidizing substances suitable for the treatment of pyrophoric iron and/or surfactant substances. Finally, the compositions object of the invention exhibit a freezing temperature of < - 15°C and, therefore, are also applicable under extreme temperature conditions.

Applicable dosage interval: 0.5-10% on the water or steam (vapor) volume available for the application.