AU2011226134A1

AU2011226134A1 - Method for regenerating hydrocarbon filler

Info

Publication number: AU2011226134A1
Application number: AU2011226134A
Authority: AU
Inventors: Frederic Barth; Aurelien Ledieu; Dominique Rio; Luc Schrive
Original assignee: CONCEPTION D EQUIPEMENTS POUR L ENVIRONNEMENT ET L IND SC2EI SOC D; Commissariat a lEnergie Atomique CEA; Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Current assignee: Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Priority date: 2010-03-10
Filing date: 2011-03-09
Publication date: 2012-09-27
Anticipated expiration: 2031-03-09
Also published as: FR2957353B1; AU2011226134B2; FR2957353A1; AU2011226134B9; WO2011110585A1

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

1 PROCESS FOR REGENERATING HYDROCARBON FEEDSTOCK DESCRIPTION TECHNICAL FIELD The present invention pertains to a process 5 for regenerating hydrocarbon feedstock using a pre treatment step before filtering the said hydrocarbon feedstock. This process finds particular application in the treatment of waste oils, such as engine oils, in 10 particular for the regeneration thereof with a view to their further use. This type of treatment is commonly known under the expression « re-refining of used oils . The field of the invention is therefore the 15 field of regenerating hydrocarbon feedstock such as used engine oils. STATE OF THE PRIOR ART Oil conventionally corresponds to a mixture of hydrocarbons with which different additives can be 20 associated intended to reinforce the intrinsic properties of this oil or to impart additional properties thereto for a particular use. Among the additives commonly used for oils and engine oils in particular, mention may be made of: 25 - antioxidant additives whose function is to delay oxidation phenomena of the oil and thereby prolong its lifetime; 2 - detergent additives whose function is to maintain the cleanliness of the parts intended to be in contact with the said oil; - dispersant additives which are used to 5 place solid impurities in suspension in the oil (e.g. soot, dust, wear metals) formed in engine oils for example; - anti-wear additives contributing towards forming a protective film on the surfaces of the parts 10 in contact with the said oil; - anti-rust additives, additives improving the viscosity index or anti-foaming additives... etc. When oils are in use, they are subjected to stresses which will generate the degradation thereof, 15 translating as an increase in the level of contaminating elements in the said oils, these contaminating elements possibly being derived from: *degradation of the above-mentioned additives, such as antioxidant additives, anti-wear 20 additives; *external pollutants and wear metals derived for example from the parts with which the oil is in contact when in use; *fractions of fuel (such as diesel oil or 25 petrol) more or less oxidized and/or thermally cracked to liquid or solid form (therefore possibly forming soot). The result is polluted oil having stronger colouring than the initial clean oil, hence the name 30 black oil in the area of used engine oils, the dark 3 colouring being essentially due to the presence of oxidized and/or thermally cracked fuels. So that it can be re-used, oil must be rid of its contaminating elements and for this purpose it 5 must undergo depolluting operations, generally transposed from conventional refining operations, such as: *primary treatment intended to remove solid elements in suspension in the used oil, this treatment 10 conventionally being performed by filtration or decantation; *operations to separate polluting compounds dissolved in the used oil, e.g. by distillation, after which a recoverable fraction is obtained that is more 15 or less coloured and close to the base oil it is sought to obtain; *finishing operations, essentially to obtain a decoloured oil e.g. by adsorption of the said oil on activated bleaching clays or by catalytic 20 hydrogenation. The filtering of used oil can be conventionally conducted by tangential filtration which consists of causing the oil to pass tangentially to the surface of the filter. The oil passes through the 25 filter via the pressure it exerts thereupon whilst the undesirable colloid or solid elements present in the used oil mostly remain in the tangential circulating flow, thereby causing less clogging of the filter than would occur if the oil is filtered frontally. 30 However, having regard to the high viscosity of oils, the flow rate of the oil through the 4 porosity of the filter is slower than for liquids whose viscosity is close or identical to that of water, which is detrimental to the yield of filtration. To overcome this drawback, different 5 solutions have been proposed in the literature to filter a viscous liquid such as oil. One solution can consist for example of increasing the temperature of the liquid to be filtered to reduce its viscosity, as is proposed in document FR 10 2 482 975. More specifically, the treatment process described in this document entails passing the liquid to be treated through a mineral ultrafiltration filter at a temperature higher than 100 0 C, possibly reaching 350'C for example. 15 However this type of process has the following disadvantages: - a very high operating temperature, which requires precautions to be taken on account of the risks of flammability of the product to be treated; 20 - mechanical stresses applied to the ceramic membranes, these stresses being caused by differential expansion of the constituent material of the membranes on account of the difference in temperature induced between the start and end of 25 heating; and - a phenomenon of oxidation of components of the used oil feedstock, contributing in particular towards making it more viscous. Another solution can consist of adding an 30 adjuvant to the oil to be treated which will allow a 5 reduction in the viscosity of the liquid to be filtered. This adjuvant can be a liquid organic solvent such as hexane, heptane or any other oil 5 miscible organic solvent as described in FR 2 453 211, or it may be a supercritical fluid such as supercritical carbon dioxide as described in WO 00/52118. However these embodiments translate as a 10 high probability that undesirable elements will pass into the filtrate through the filter, which is adverse to the quality of the recovered filtrate. There is therefore a need for a process to regenerate hydrocarbon feedstock by filtration which 15 would allow a reduced number of undesirable elements contained in this feedstock to pass through the filter. DESCRIPTION OF THE INVENTION The inventors have surprisingly discovered that by applying suitable treatment to the hydrocarbon 20 feedstock before filtration, it is possible to reduce substantially the passing of contaminating elements through the filter, irrespective of the filtration mode involved. The invention therefore relates to a 25 process for regenerating a hydrocarbon feedstock containing one or more dispersant additives, the said process comprising the following steps: a) a step to contact the said feedstock with at least one agent which aggregates the said 30 dispersant additive(s), after which a feedstock is 6 obtained containing aggregates of the said dispersant additive (s) ; b) a step to pass the feedstock obtained after step a) through a filter retaining the said 5 aggregates. Before going into further detail in the description, the following definitions are specified. By hydrocarbon feedstock is meant feedstock comprising one or more hydrocarbons and optionally one 10 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 implementing the above-mentioned removal 15 process. By aggregating agent is meant an agent capable of generating the coalescence of the said dispersant additive(s), after which aggregates are formed of the said dispersant additives (for example in 20 the form of particles or colloids) which will be retained by the filter. Therefore with the invention, by means of the use of an aggregating agent to aggregate the said dispersant additive(s) to be removed before filtration, 25 it is possible to obtain a hydrocarbon feedstock comprising aggregates of the said dispersant additives in suspension, these aggregates easily being retained by the filter whilst the filtrate will therefore contain a hydrocarbon feedstock fully or partly rid of 30 the dispersant additive(s).

7 Said dispersant additives are conventionally organic compounds comprising a polar part and a lipophilic part which act to place solid or colloidal elements in suspension in the hydrocarbon 5 feedstock, such as dust, soot, wear metals, solid or colloidal oxidation residues to prevent these solid or colloidal elements from agglomerating and thereby prevent the formation of deposits. As examples of dispersant additives, 10 alkenylsuccinimides can be cited such as those meeting the following formula: 0

CH

3 R--CH

C-CH

2 N -(CH 2

-CH

2

-NH)

2

-CH

2

-CH

2

-NH

2 0 15 Ri being a hydrocarbon group. Mention may also be made, as examples of dispersant additives, of compounds of o Mannich base type such as those meeting the following formula: OH

CH

2 -NH-(CH 2 -CH 2 -NH) 2

-CH

2 -CH 2 -NH 2 R2 20 where R 2 is an alkyl group.

8 In a hydrocarbon feedstock such as used oil, the dispersant additives allow the ensured individualization of the above-mentioned elements, and these will be able to pass through the filter on which 5 the hydrocarbon feedstock is filtered, which will be detrimental to filtering performance. According to the invention by adding, before the filtering step, an aggregating agent to aggregate the said dispersant additives, an aggregate 10 of the said dispersant additives is formed which also comprises the individualized compounds dispersed in the feedstock before the aggregating agent is added. The adding of an agent to aggregate the said dispersant additives has the following advantages: 15 - through the formation of aggregates able to be retained by a filter, it allows the subsequent removal via filtration of the dispersant additives which no longer have optimal dispersion efficacy since they already contribute to the dispersion of external 20 pollutants generated when the oil was in use; - concomitantly, it allows the removal of external pollutants (namely elements not derived from the oil initially used such as soot, metal elements produced by wear of the parts with which hydrocarbon 25 feedstock was in contact when in used) and of additives initially present in the unused oil, these additives possibly being fully or partly degraded after the use of this oil such as detergent additives, anti-wear additives, these external pollutants and additives 30 being included in the formation of the aggregate with 9 the dispersant additives with which they were initially combined; - the adding of an agent to aggregate the dispersant additives induces little or no reduction in 5 the flow of filtrate through the filter during the filtering step. Without wishing to be bound by any theory, the aggregating agent of the said dispersant additives will be considered by the latter to be a pollutant to 10 be dispersed, which will contribute towards saturation of the dispersive functions of these additives until the onset of aggregates having a size such that that they will be retained by the filter used at the subsequent filtering step. 15 Agents which aggregate dispersant additives can be chosen from among: - solid compounds such as powders; - liquid compounds; - paste compounds; and 20 - mixtures thereof. As examples of powders, mention may be made of absorbent clays, ceramic oxides such as alumina, activated charcoal. Solid compounds can also be in the form of 25 organic salts or inorganic salts (such as sodium salts, potassium salts, ammonium salts). As examples of liquid compounds, mention can be made of organic solvents fully or partly miscible with the hydrocarbon feedstock to be treated.

10 As examples of paste compounds, mention can be made of tars, bitumen, of more generally the residues of distillation. The aggregating agents can be added to the 5 hydrocarbon feedstock to be treated to the proportion of 0.1 to 20 % by weight relative to the total weight of the feedstock, preferably from 0.25 to 10 % and more preferably from 0.5 to 5 % by weight. The hydrocarbon feedstock to be treated 10 according to this process can in particular be oil such as used oil, which may be either an organic oil or mineral oil. As organic oils, mention can be made of organic vegetable oils or organic animal oils. 15 Organic vegetable oils can be chosen from among triglyceride oils such as sunflower oil, groundnut oil, rapeseed oil, corn oil, olive oil, copra oil, palm oil, and non-triglyceride oils such as jojoba oil. 20 Organic animal oils can be chosen from among fish oils, marine mammal oils and land mammal oils such as oxen or sheep neatsfoot oil and trotter oils. As for mineral oils, these may be mineral 25 oils derived from the fractionated distillation of crude oil, in particular waste black oil such as rolling oils or engine oils. Once the contacting step a) has been performed, the process of the invention comprises a 30 step to pass the feedstock thus treated through a filter which will retain the aggregates and thereby 11 allow a filtrate to be isolated that is rid of the said aggregates. This step can be conducted: *by frontal filtration, meaning that the 5 flow of feedstock derived from step a) encounters the filter perpendicular to its pathway, the filter retaining all the particles and in particular the aggregates formed at step a) which have a larger diameter than the mean mesh size of the said filter; or 10 *by tangential filtration, which means that the flow of feedstock derived from step a) flows parallel to the surface of the filter. The filter may be a metal-based or metal alloy-based membrane (such as steel optionally 15 stainless, nickel), or oxide-based containing oxides such as those chosen from among A1 2 0 3 , ZrO 2 , TiO 2 . It can be capable of retaining particles having a mean size (i.e. the mean diameter of the particles) of between 1 nm and 10 pm, preferably between 2 nm and 1 20 pm, more preferably between 2 nm and 0.1 pm. The filtering step, in particular if filtration is tangential, can be assisted by a supercritical fluid, in other words meaning that the feedstock before the filtering step b) is placed in 25 contact with a fluid in the supercritical state, this contacting step possibly being performed before, simultaneously and/or after step a). The fluid in the supercritical state can be chosen from among C02, N 2 0, SF 6 , preferably C02 in 30 particular if the oil to be treated is used engine oil.

12 It may also be an alkane placed in the supercritical state such as methane, ethane, propane, butane in its different isomer forms, pentane in its different isomer forms, hexane in its different isomer 5 forms and heptane in its different isomer forms. The advantage of using a fluid in the supercritical state is that it allows a reduction in the viscosity of the feedstock to be treated, and thereby facilitates the filtration thereof after the 10 formation of the aggregates. The process of the invention can also be implemented continuously or discontinuously i.e. by batch process. In this latter case, the contacting step 15 with an aggregating agent is performed in a single operation with the entire volume of feedstock to be treated, this volume then being entirely subjected at a single time to the filtering step. This operating mode is of particular advantage for products with high added 20 value available in small quantities and for which continuous operation is not adapted. The process of the invention can be carried out in an installation comprising at least: *a unit (such as a vessel), in which the 25 contacting step a) will be conducted; *a filtration unit connected to the said unit mentioned above; and *a retentate collecting unit and a filtrate collecting unit both connected to the filtration unit.

13 The invention is described below according to one particular embodiment given for illustration purposes and which is non-limiting. 5 BRIEF DESCRIPTION OF THE DRAWINGS The single Figure illustrates a schematic cross-sectional view of an example of an installation for implementing the process of the invention according to one particular embodiment described below. 10 DETAILED DESCRIPTION OF ONE PARTICULAR EMBODIMENT EXAMPLE In this example an installation was used 15 such as illustrated in the single Figure. In this Figure, the installation (referenced 1) comprises feeding means to feed the liquid hydrocarbon feedstock to be treated, an aggregating agent and a supercritical fluid, consisting 20 of: - a tank or vat 3 comprising the hydrocarbon feedstock to be treated; - a tank or vat 5 comprising the aggregating agent; and 25 - a tank or vat 7 comprising the fluid in the supercritical state, which in this case is carbon dioxide. The tanks 3 and 7 are connected to an injection zone 9 located upstream of the filtration 30 membrane 11, respectively via a pipe 13 provided with a pump 15 and a pipe 17 provided with a pump 19.

14 The tank 5 is connected to the pipe 13 downstream of the pump 15, and upstream of the injection zone 9 via a pipe 16. The contacting step a) of the process is 5 therefore performed at the injection zone 9. The two pumps 15 and 19 are high pressure metering pumps with membrane. The mixture resulting from the contacting in the injection zone 9 is then injected via a 10 circulation loop 21 equipped with a circulation pump 23 into a filtration membrane 11 in ceramic oxide having a mean pore size of 0.1 pm. This filtration membrane is connected via a pipe 24 to a separator 27 intended to collect the 15 filtrate mixed with the supercritical fluid, and a via a pipe 30 to a separator 31 intended to collect the retentate also mixed with supercritical fluid. The separator 27 is equipped with a pipe 37 to convey the filtrate towards a recovery unit (not 20 illustrated) and a pipe 39 to convey supercritical fluid towards the tank 7 via a pipe 36. The separator 31 is equipped with a pipe 33 allowing the retentate to be conveyed towards a recovery unit (not illustrated) and a pipe 35 allowing 25 supercritical fluid to be conveyed towards the tank 7 via the pipe 36. The hydrocarbon feedstock treated in this example is a used mineral oil of IGOL trademark originating from the oil change of a heavy vehicle of 30 RVI make which had travelled 100 000 km, this oil 15 containing a dispersant additive of alkenylsuccinimide type. One test was conducted without the addition of an aggregating agent to the oil to be treated (this 5 test being called the o control test below) and another test was conducted with oil having the same characteristics as the control test with the addition however of an aggregating agent of bitumen type downstream of tank 3 to the proportion of 1 % by weight 10 relative to the total weight of the oil (this test being called below the < test with aggregating agent ). Filtration was performed tangentially. The trans-membrane pressure (namely the 15 differential pressure which allows the passing of the oil through the membrane to recover a filtrate) was 4 bars. The static pressure (namely the pressure of

CO

2 applied at the point of injection 9) was 150 bars. 20 The treatment temperature was 130 to 135'C. At the outlet of the separator 27, for both these tests, the concentration was measured of the elements present in the filtrate (symbolised hereafter by Cfitrate) using the ASTM D 4629 method for nitrogen 25 and the ASTM D 5185 (ICP) method for the other elements. The results are grouped together in the Table below. 30 16 Element Control test Test with aggregating agent Criitrate Criitrate 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 nitrogen is present in a quantity that is about four times less in the filtrate derived from the test with aggregating agent compared 5 with the filtrate derived from the control test. This can be accounted for by the improved retention of the dispersant additives of alkenylsuccinimide type contained in the oil to be treated. This improved retention also translates as 10 improved retention results for the other elements given in the Table since these elements come to be trapped by the aggregating agent which alone generates the aggregating of the dispersant additives. 15

Claims

1. A process for regenerating a hydrocarbon feedstock comprising one or more dispersant additives, 5 the said process comprising the following steps: a) a step to contact the said feedstock with at least one aggregating agent of the said dispersant additive(s), after which a feedstock is obtained containing aggregates of the said dispersant 10 additive(s); b) a step to pass the feedstock obtained after step a) through a filter retaining the said aggregates. 15

2. The process according to claim 1 wherein the hydrocarbon feedstock is used oil.

3. The process according to claim 1 or 2 wherein the dispersant additives are chosen from among 20 alkylenylsuccinimide compounds and compounds of Mannich base type.

4. The process according to any of the preceding claims wherein the aggregating agent of the 25 said dispersant additives is chosen from among solid compounds, liquid compounds and paste compounds, and mixtures thereof.

5. The process according to any of the 30 preceding claims wherein the aggregating agent is added to the hydrocarbon feedstock to the proportion of 0.1 18 to 20 % by weight relative to the total weight of the feedstock.

6. The process according to any of the 5 preceding claims wherein step b) is performed by frontal filtration or tangential filtration.

7. The process according to any of the preceding claims wherein step b) is performed by 10 tangential filtration.

8. The process according to any of the preceding claims wherein step b) is conducted in the presence of a supercritical fluid. 15