WO2011110585A1 - Method for regenerating hydrocarbon filler - Google Patents

Abstract

The invention relates to a method for regenerating a hydrocarbon filler including one or more dispersant additives, said method including the following steps: a) a step of placing said filler in contact with at least one agent for aggregating said dispersant additive(s), by means of which a filler including aggregates of said dispersant additive(s) is produced; b) a step of passing the filler produced from step a) over a filter retaining said aggregates.

Description

 METHOD FOR REGENERATING A HYDROCARBONATED LOAD

DESCRIPTION

TECHNICAL AREA

 The present invention relates to a regeneration process of a hydrocarbon feedstock implementing a pretreatment step before filtration of said hydrocarbon feedstock.

 This process finds, in particular, its application in the treatment of used oils, such as motor oils, in particular to regenerate them for a new use. This type of treatment is commonly referred to as "re-refining used oils".

 The field of the invention is therefore that of the regeneration of hydrocarbon feedstocks, such as used motor oils.

STATE OF THE PRIOR ART

 An oil corresponds, conventionally to a mixture of hydrocarbons, to which may be associated various additives intended to enhance the intrinsic properties of this oil or to provide additional properties for a particular use.

 Among the additives commonly used in oils, in particular in motor oils, mention may be made of:

antioxidant additives whose function is to slow the oxidation phenomena of the oil and thus extend its life; detergent additives whose function is to keep clean the parts intended to be in contact with said oil;

 dispersant additives which serve to suspend solid impurities in the oil

(such as soot, dust, wear metals) formed, for example, in motor oils;

 anti-wear additives helping to form a protective film on the surfaces of the parts in contact with said oil;

 antirust additives, viscosity index improvers or anti-foam additives ... etc.

 The oils, when they are used, are subjected to stresses that will cause their degradation, which is manifested by an increase in the level of contaminating elements of said oils, these contaminant elements possibly coming from:

 * degradation of the aforementioned additives, such as antioxidant additives, antiwear agents;

 external pollutants and wear metals emanating, for example, from parts with which the oil is in contact during its use;

 * fractions of fuel (such as diesel or gasoline) more or less oxidized and / or thermally cracked in liquid or solid form

(can thus form soot).

This results in a polluted oil with a stronger coloration than the initial clean oil, hence the term black oils in the field of used motor oils, the black color is mainly due to the presence of oxidized fuels and / or thermally cracked.

 In order to be reusable, the oil must be freed from its contaminating elements and, to this end, undergoes depollution operations transposed generally conventional refining operations, such as:

 a primary treatment intended to remove the solid elements suspended in the spent oil, this treatment being carried out conventionally by filtration or decantation;

 * separating operations polluting compounds dissolved in the waste oil, for example, by distillation, after which it is obtained a more or less colored recoverable fraction close to the desired base oil;

 finishing operations, essentially to obtain a discolored oil, for example, by adsorption of said oils on activated bleaching grounds or by catalytic hydrogenation.

The filtration of a used oil can be carried out conventionally by tangential filtration, which consists of passing the oil tangentially to the filter surface. The oil passes through the filter through the pressure it exerts on the filter, while the colloidal or solid undesirable elements present in the used oil remain in the tangential flow of the flow, causing a clogging of the filter less than that which would be obtained if the oil was filtered by frontal filtration.

 However, in view of the high viscosity of the oils, the rate of passage of the oil through the porosity of the filter is reduced compared with liquids whose viscosity is close to or identical to that of water, which affects the filtration efficiency.

 To overcome this drawback, various solutions have been proposed in the literature for filtering a viscous liquid, such as an oil.

 One solution may be, for example, to increase the temperature of the liquid to be filtered in order to lower the viscosity as proposed in document FR 2 482 975. More specifically, the treatment method described in this document consists in passing on a mineral ultrafiltration filter the liquid to be treated, and this at a temperature above 100 ° C, for example, up to 350 ° C.

 However, this type of process has the following drawbacks:

 a very high operating temperature, which requires precautions because of the risk of flammability of the product to be treated;

mechanical stresses applied to the ceramic membranes, these stresses being caused by the differential expansion of the material constituting the membranes by the temperature difference induced by the heating between the start thereof and the stopping of the latter; and a phenomenon of oxidation of components of the used oil charge contributing to render it, in particular, more viscous.

 Another solution may be to add an adjuvant to the oil to be treated, which will make it possible to reduce the viscosity of the liquid to be filtered.

 This adjuvant may be a liquid organic solvent such as hexane, heptane or any other organic solvent miscible in oil as described in FR 2 453 211 or may also be a supercritical fluid, such as supercritical carbon dioxide, as described in WO 00/52118.

 However, these embodiments result in a significant probability of passage of undesirable elements in the filtrate through the filter, which is troublesome for the quality of the filtrate recovered.

 There is thus a need for a process for regenerating a hydrocarbon feedstock by filtration which would make it possible to reduce the passage through the filter of undesirable elements contained in this feedstock.

STATEMENT OF THE INVENTION

The inventors have discovered, surprisingly, that by appropriately treating the hydrocarbon feedstock before filtration, it is possible to substantially reduce the passage of contaminant elements through the filter, whatever the filtration mode. involved. Thus, the invention relates to a process for regenerating a hydrocarbon feedstock comprising one or more dispersant additives, said process comprising the following steps:

 a) a step of bringing said charge into contact with at least one aggregating agent of said dispersing additive (s), whereby a charge comprising aggregates of said one or more dispersing additives is obtained;

 b) a step of passing the charge obtained at the end of step a) on a filter retaining said aggregates.

 Before going further in this description, we specify the following definitions.

 By "hydrocarbon feedstock" is meant a feedstock comprising one or more hydrocarbons and optionally one or more compounds which, in addition to carbon and hydrogen atoms, may contain heteroatoms. In particular, the hydrocarbon feedstock is advantageously a liquid hydrocarbon feedstock, at least under the operating conditions for carrying out the abovementioned elimination process.

 By aggregating agent is meant an agent capable of generating coalescence of said dispersing additive (s), whereby aggregates of said dispersing additives (for example, in the form of particles or colloids) are formed which will be retained by the filter. .

Thus, the method of the invention, through the use of an aggregating agent of said dispersant additive (s) to be removed before filtration, allows to obtain a hydrocarbon feed comprising, in suspension aggregates of said dispersant additives, which aggregates will be easily retained by the filter while the filtrate will be a hydrocarbon feed removed, in whole or in part, the dispersant additive or additives.

 Such dispersant additives are conventionally organic compounds comprising a polar part and a lipophilic part, which serve to suspend in the hydrocarbon feedstock solid or colloidal elements such as dust, soot, wear metals, solid residues. or colloidal oxidation, so as to prevent these solid or colloidal elements to agglomerate and thus avoid the formation of deposits.

 Examples of dispersant additives are alkenyl succinimide compounds, such as those having the following formula:

R representing a hydrocarbon group.

Mention may also be made, as examples of dispersant additives, of compounds of the "Mannich base" type, such as those corresponding to the following formula:

dans lequel R est un groupe alkyle.

wherein R is an alkyl group.

 In a hydrocarbon feed, such as a waste oil, the dispersant additives will make it possible to ensure the individualization of the aforementioned elements, which will be able to pass through the filter on which the hydrocarbon feed passes, which affects the filtration performance.

 According to the invention, by adding, prior to the filtration step, an aggregating agent of said dispersant additives, an aggregate of said dispersing additives is thus formed, which also comprises the individualized compounds dispersed in the feedstock before introduction of the agent. aggregation.

 The introduction of an aggregating agent of said dispersant additives has the following advantages:

- It allows, by formation of aggregates able to be retained by a filter, the subsequent removal by filtration dispersant additives, which no longer have optimal dispersion efficiency, because they already contribute to the dispersion of external pollutants generated when using the load; it allows, concomitantly, the removal of external pollutants (ie elements not coming from the load initially used, such as soot, metal elements from the wear of the parts with which the hydrocarbon feed is in contact in use) and additives initially present in the unfused load, these additives can be, in part partially degraded after use of this load, such as detergent additives, antiwear additives, which external pollutants and additives are embedded in the formation of the aggregate with the dispersant additives to which they were initially bound;

 the addition of a dispersing additive aggregating agent induces little or no decrease in the flow of filtrate through the filter during the filtration step.

 Without being bound by any theory, the aggregating agent of said dispersant additives will be considered by them as a pollutant to be dispersed, which will contribute to the saturation of the dispersive functions of these additives until the appearance of aggregates having a size such that they will be retained by the filter involved during the subsequent filtration step.

 Dispersant additive aggregating agents may be selected from:

 solid compounds, such as powders;

 - liquid compounds;

pasty compounds; and mixtures thereof.

 As examples of powders, mention may be made of absorbent earths, ceramic oxides such as alumina, and activated carbon.

 The solid compounds may also be in the form of organic salts or inorganic salts (such as sodium salts, potassium salts, ammonium salts).

 As examples of liquid compounds, there may be mentioned organic solvents miscible in whole or in part with the hydrocarbon feedstock to be treated.

 As examples of pasty compounds, mention may be made of tars, bitumens or even more generally distillation residues.

 The aggregating agents may be added to the hydrocarbon feedstock to be treated at a level of from 0.1 to 20% by weight relative to the total weight of the filler, preferably from 0.25 to 10% and even more preferably from 0 to 20% by weight. 5 to 5% by weight.

 The hydrocarbon feedstock treated by this process may be, in particular, an oil, such as waste oil, which may be both an organic oil and a mineral oil.

 Organic oils include vegetable organic oils or animal organic oils.

The organic vegetable oils can be chosen from triglyceride oils, such as sunflower oil, peanut oil, rapeseed oil, corn oil, olive oil, coconut oil, palm oil and non-triglyceride oils, such as jojoba oil.

 The organic animal oils may be selected from fish, marine mammal, terrestrial mammal oils, such as beef, pork or sheep oils.

 As for mineral oils, they may be mineral oils resulting from the fractional distillation of crude oil, in particular spent black oils such as rolling oils or motor oils.

 Once the contacting step a) carried out, the method of the invention comprises a step of passing the charge thus treated on a filter which will retain the aggregates and thus to isolate a filtrate freed of said aggregates.

 This step can be performed:

 * by frontal filtration, which means that the flow of charge from step a) meets perpendicularly to its path the filter which will retain all the particles, including the aggregates formed in step a), having a diameter greater than the average mesh size of said filter; or

 * by tangential filtration, which means that the flow of charge from step a) flows parallel to the filter surface.

The filter may be a membrane based on metals or metal alloys (such as optionally stainless steel, nickel), oxides such as oxides chosen from Al 2 O 3, ZrC 2, TiCl 2. he can be capable of retaining particles whose mean particle size (ie the average particle diameter) is between 1 nm and 10 μm, preferably between 2 nm and 1 μm and more preferably between 2 nm and 0.1 pm.

 The filtration step, in particular when the filtration is tangential, can be assisted by a supercritical fluid, which means, in other words, that the charge before the filtration step b) is brought into contact with a fluid in the supercritical state, this contacting step can be implemented before, simultaneously and / or after step a).

The fluid in the supercritical state can be selected from CO ₂ , N ₂ O, SF ₆ , preferably CO ₂ , especially when it comes to treating an oil, such as a used engine oil.

 It may also be alkanes placed in a supercritical state, such as methane, ethane, propane, butane under its different isomers, pentane in its different isomeric forms, hexane in its different isomeric forms and heptane in its different isomeric forms.

 The advantage of using a fluid in the supercritical state is to reduce the viscosity of the charge to be treated and thus facilitate its filtration after formation of the aggregates.

The method of the invention can be implemented continuously or even discontinuously, that is to say in batches ("batch"). In the latter case, the step of bringing into contact with an aggregating agent is carried out once with all the volume of charge to be treated, this volume then being subjected entirely at once to the filtration step . This mode of operation is particularly interesting for products with high added value, available in small quantities and for which continuous operation is not suitable.

 The process of the invention can be carried out in an installation comprising at least:

 a unit (such as a tank) in which the contacting step a) will be implemented;

 a filtration unit connected to said unit as mentioned above; and

 * a retentate collection unit and a filtrate collection unit both connected to the filtration unit.

 The invention will now be described according to a particular embodiment given by way of illustration and not limitation.

BRIEF DESCRIPTION OF THE DRAWINGS

The single figure shows a schematic sectional view of an example installation for implementing the method of the invention according to the particular embodiment described below. DETAILED PRESENTATION OF A PARTICULAR EMBODIMENT

EXAMPLE

 In this example, an installation as shown in the single figure was used.

 In this figure, the installation

(referenced 1) comprises means for supplying a hydrocarbonaceous liquid feedstock to be treated, an aggregating agent and a supercritical fluid consisting of:

 a reservoir or tank 3 comprising the hydrocarbon feedstock to be treated;

 a tank or tank comprising the aggregating agent; and

 - A tank or tank 7 comprising a fluid in the supercritical state, which is in this case carbon dioxide.

 The tanks 3 and 7 are connected to an injection zone 9 located upstream of the filtration membrane 11, respectively via a pipe 13 provided with a pump 15 and a pipe 17 provided with a pump 19.

 The reservoir 5 is connected to the pipe 13 downstream of the pump 15 and upstream of the injection zone 9 by a pipe 16.

 The contacting step a) of the process is thus performed at the injection zone 9.

 Both pumps 15 and 19 are high pressure diaphragm metering pumps.

The mixture resulting from the contacting in the injection zone 9 is then injected via a circulation loop 21 provided with a circulation pump 23 into a filtration membrane 11. ceramic oxide with an average pore size of 0.1 μm.

 This filtration membrane is connected via a pipe 24 to a separator 27 for receiving the filtrate mixed with the supercritical fluid and via a pipe 30 to a separator 31 for receiving the retentate also mixed with supercritical fluid.

 The separator 27 is provided with a pipe 37 for conveying the filtrate to a recovery unit (not shown) and a pipe 39 for conveying the supercritical fluid to the tank 7 via a pipe 36.

 The separator 31 is provided with a pipe 33 for conveying the retentate to a recovery unit (not shown) and a pipe 35 for conveying the supercritical fluid to the tank 7 via the pipe 36.

 The hydrocarbon feedstock treated according to this example is an IGOL branded mineral oil resulting from the emptying of an engine of a RVI brand truck having traveled 100,000 km, this oil comprising a dispersant additive of the alkenylsuccinimide type.

A test was carried out without addition of aggregating agent in the oil to be treated (this test being referred to hereinafter as "reference test") and another test was carried out, with an oil having the same characteristics as the reference test, with the addition, however, of a bitumen aggregation agent downstream of the tank 3 at a level of 1% by mass relative to the total mass of the oil (this test hereinafter referred to as "aggregation agent test").

 Filtration is carried out tangentially.

 The transmembrane pressure (ie the differential pressure which allows the passage of the oil through the membrane to recover a filtrate) is 4 bars.

 The static pressure (i.e. the CO2 pressure that is applied at the injection point 9) is 150 bar.

 The treatment temperature is 130 to

135 ° C.

 At the outlet of the separator 27, the concentration of the elements present in the filtrate (symbolized hereinafter by Cfiitrat) by the ASTM D 4629 method for the nitrogen and by the ASTM D 5185 method was measured for these two tests. (ICP) for the other elements.

The results are summarized in the table below.

 Test Essay Element with Aggregate Reference Agent

Cfiitrat Cfiitrat

N 2100 500

 P 401 243

 Zn 323 171

 Ca 520 144

 Mg 7 3

Al 2 1 Fe 23 15

 Cr 2 1

 Mo 10 4

 Cu 2 0

 Pb 2 1

 Na 6 4

 B 24 14

It is noted that the nitrogen is present in an amount approximately four times smaller in the filtrate from the test with the aggregating agent than in the filtrate from the reference test. This is explained by the improved retention of the alkenylsuccinimide dispersant additives present in the oil to be treated.

 This improved retention also results in better retention results for the other elements in the table, since these elements are trapped by the aggregating agent which itself generates the aggregation of dispersant additives.

Claims

A process for regenerating a hydrocarbon feedstock comprising one or more dispersant additives, said process comprising the following steps:  a) a step of bringing said charge into contact with at least one aggregating agent of said dispersing additive (s), whereby a charge comprising aggregates of said one or more dispersing additives is obtained;  b) a step of passing the charge obtained at the end of step a) on a filter retaining said aggregates. 2. The process according to claim 1, wherein the hydrocarbon feedstock is a waste oil. 3. The method of claim 1 or 2, wherein the dispersant additives are selected from alkylenylsuccinimide compounds and Mannich base compounds. 4. A process according to any one of the preceding claims, wherein the aggregating agent of said dispersant additives is selected from solid compounds, liquid compounds and pasty compounds and mixtures thereof. The method of any of the preceding claims, wherein the agent aggregation is added to the hydrocarbon feedstock at a level of 0.1 to 20% by weight relative to the total mass of the feedstock. 6. Method according to any one of the preceding claims, wherein step b) is carried out by frontal filtration or tangential filtration. 7. Method according to any one of the preceding claims, wherein step b) is carried out by tangential filtration. 8. A method according to any one of the preceding claims, wherein step b) is carried out in the presence of a supercritical fluid.