NL8701097A - METHOD FOR REMOVING ASPHALT FROM A HYDROCARBON OIL CONTAINING ASPHALT. - Google Patents

Description

"__- if 873029 / Ba / cd

Title: Method for removing asphalt from a hydrocarbon oil containing asphalt.

The Applicant mentions as inventor: Gérard Hotier in Rueil Malmaison, France.

The invention relates to an asphalt removal process in which a hydrocarbon oil containing asphalt is subjected to a treatment with an asphalt removal solvent to form two phases and said two phases are separated to separately form a light oily phase (crude extract). and recovering a heavy asphaltic phase (crude raffinate) and separating the solvent from each of said phases.

For a long time, an operation for removing asphalt IQ from an asphalting-containing oil has been known, which consists of treating the oil with an asphalt removal solvent.

Two phases then form which are separated; a light extract phase containing the main amount of the solvent and the deasphalted oil and a heavy raffinate phase containing mainly the asphalt and a little solvent. Each of these obtained phases is then subjected to a solvent removal operation. In this way, the deasphalted oil (D.A.O.) and an asphalt phase are separately obtained.

2Q US Patent 2,940,920 describes the separation of the light extract phase (a mixture of deasphalted oil and asphalt removal solvent) into a crude raffinate phase containing a heavy fraction called resins and a little asphalt removal solvent and into a crude extract phase containing a heavy oil fraction which has been de-waxed and deasphalted and contains the major part of the asphalt removal solvent, under conditions close to the critical point of the solvent. By critical point of the solvent is meant the torque critical pressure-3β critical temperature. The critical temperature of a pure substance is the maximum temperature at which such a substance can be liquefied by isothermal compression, the critical temperature of a mixture is the maximum temperature at which the entire mixture can be liquefied. The critical pressure of a pure substance is the maximum 8701097 τ * * * -2- pressure at which boiling or condensation can be observed by isobaric variation of the temperature, the critical pressure of a mixture is the maximum pressure at which one can reduce by isobaric temperature can liquefy the total of the mixture. Conditions near the critical point usually mean a temperature such as T = 0.95 to 1.05 T (with an absolute scale of the temperature), a pressure P such as P = 1.05 to 1.5 P (with an absolute scale of the pressure).

For example, Example IV, columns 25 and 26, lines 30 to 45 of said patent disclose the separation of a resin fraction on the one hand and a mixture of dehaxed and deasphalted oil and pentane on the other hand at a temperature of 0.96 to 1.04 T and at a pressure of 0.86 to 1.48 P.

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15 when the pressure and critical temperature of pentane are 196 ° C and 33.3 bar, respectively.

The subsequent separation of the crude extracts and the crude raffinates from said dehairing step of the solvent with which they are still mixed takes place under apparent super-2Q. Critical Conditions: Therefore, in U.S. Patent 2,940,929, the de-waxed and deasphalted oil is separated from pentane at 215 ° C and 38 bar (column 18, line 20), while U.S. Patent 4,305,814 discloses the mixture of resin and pentane separated at 240 ° C and 46 bar.

US patent 4 502 944 even shows a three-phase separation under light under critical conditions: T-0.95 T, P = 1.5 P, the following separations of the solvent-containing products still clearly take place in the supercritical range.

30. In French patent application 85/15 552, the applicant is committed to further improving energy recovery in the separation of DAO solvent by performing at least two supercritical separations in terms of temperature and heat recovery. recovery by exchange at the different streams and optionally by either recompressing the vapor or performing three supercritical separations with in that case recirculating the previously occurring condensation, specifying very precise working conditions of torques, for example, in the case wherein the solvent is pentane, 8701097 * * -3-, the temperature should be between 224 and 268 ° C and the pressure between 38 and 68 bar.

Another principle of economic separation of a solvent and a solute is also known; it consists of performing this separation by tangential filtration on a membrane.

In a report presented at the National Meeting of the American Institute of Chemical Engineers in Seattle, August 25-28, 1985, Kulkarni, Funk IQ, and Li presented the separation of deasphalted oil and pentane with an organic membrane at temperatures between 25 ° C and 50 ° C and at pressures of the order of 7 to 20 bar.

A typical result for this series of tests shows, starting from a mixture with a solvent weight content of 4 (20 wt% DAO, 80 wt% pentane), the formation per 2 m and per day of 300 to 800 liters of a mixture with a solvent weight percentage of 16 (6 wt% DAO, 94 wt% pentane)? wherein the ratio of the permeate flow rate to the charge flow rate is on the order of 0.1. Two main drawbacks can be argued against this technique: 1 °) the fraction of recirculated oil relative to the oil formed is far from negligible: 15%. Therefore, one will have to increase the amount of deasphalting solvent and the diameter of the reactor in order to maintain the operating parameters of the asphalt falt removal? 2 °) the temperature tolerated by the organic membrane does not exceed 75 °; and in addition, the selectivity decreases sharply from 25 to 50 ° C: since the asphalt removal takes place between 170 and 200 ° C, one must add a series of heat exchangers 3Q to the filtration unit so as not to heat the regenerated solvent to be recirculated to add this to the deasphalting conditions.

As for the ultrafiltration processes employing mineral membranes for the purpose of separating the hydrocarbonaceous products in a liquid state under operation at a temperature higher than 80 ° C, one may mention French Patent 2,482,975. mineral ultrafiltration barrier layers which are coated with a clear layer of at least one metal oxide having a permeable 8701097 *. 4 radius of radiation comprised between 5 and 25 nanometers; it is intended for regenerating waste oils by separating their impurities which are retained by the boundary layers used and which can also be used to reduce the asphaltenes content of hydrocarbon charges. In the latter application, the method proves to be unsatisfactory because the removal rate of the asphaltenes remains low, as shown by the example in the French patent.

The present invention relates to an asphalt removal method comprising a separation of deasphalted oil from deasphalting solvent based on a new principle which makes it possible to minimize the energy required for such separation.

The invention therefore relates to a process in which a hydrocarbon oil containing asphalt is subjected to a treatment with an asphalt removal solvent to form two phases and said two phases are separated to separately separate a light oily phase (crude extract) and 2Q. . heavy ash-containing phase (crude raffinate) and the solvent is separated from each of the above-mentioned phases, characterized in that in order to separate the solvent from the light oily phase, one works in at least three steps: 25 a) in a In the first step, the light oily phases are brought under supercritical conditions with respect to the solvent to effect a two phase separation, a light phase which is rich in solvent and a heavy phase which is rich in oil, whereby said 3Q two phases separates, the operating conditions being moderately supercritical, ie such that the solvent-rich light phase forms a liquid phase (or dense supercritical phase, ie with a density higher than the critical density of the pure solvent ); b) in a second step, subject to the solvent-rich light phase and separated in step a), to a tangential filtration controlled by circulation on the upstream side of an inorganic porous 4Q membrane, wherein the operating conditions on the downstream side of the membrane include a pressure lower than that on the upstream side, but the pressures are nevertheless sufficient to allow the permeate to consist of a vapor (or supercritical light phase ie having a density less than or equal to the critical density of the pure solvent) and therefore separately, on the downstream side of the membrane, said light supercritical phase is rich, which is rich in solvent and the upstream IQ side includes the remaining portion that has not passed through the membrane, called retentate, and which contains the de-asphalted oil which is low in solvent and c) in a third step, the heavy fraction which is rich in oil and which is separated in step a) is fractionated to separately obtain a solvent phase and a hydrocarbon-containing phase containing resins.

The principle of the invention therefore consists in performing a pre-separation under "liquid-liquid" conditions of the mixture of deasphalted oil and 2Q solvent and then passing the solvent-enriched phase along a porous inorganic membrane substantially under the same conditions, to recover a permeate which is mainly formed by solvent and retentate which will either be deprived of residual solvent and which will consist of a deasphalted and de-waxed oil or which will be recycled to the pre-separation step. The heavy phase of the pre-separation will later be stripped of solvent and will form an oily phase: either a simple deasphalted oil (if recirculation of 3Q the retentate takes place)? or a resin.

Therefore, energy can be recovered with respect to the traditional supercritical separation when the maximum temperature at which the solvent will be applied will preferably be 15-5 ° C lower than that of the conventional supercritical separation. Moreover, the pressure conditions chosen for step (b) make it possible to obtain a much higher selectivity than with a separation with a classic membrane? these conditions correspond to a state of "supercritical pervaporation".

8701097 't t -6-

The viscosity of the permeate is barely higher than that of a gas and the viscosity of the mixture to be filtered is reduced by an increase in temperature and a decrease in concentration of deasphalted oil.

The selectivity has been greatly improved with regard to a classical separation with a membrane in which a liquid phase is found on both sides of the membrane, with the same pore diameter. Since this pervaporation takes place in the supercritical region, the energy required for evaporation of the permeate is very much lower than that used in the subcritical region. In summary, the membrane separation under supercritical conditions, as described in the invention, shows a selectivity substantially equal to that of a conventional supercritical separation, but due to the fact that one can operate at a lower temperature, the energy requirement and the thermal exchange surface much lower.

The asphalt removal solvent comprises at least one hydrocarbon of 3-6 carbon atoms and belongs for example 2Q to the group nC3, nC ^, nC, -, nCg, iC4, ^ -C5 'neo c5' ^ so C6 'propylene, butenes, pentenes, hexenes or to the group of propane, butane, pentane, technical hexane, C 1 -fraction, C 2 -fraction, Ctj-fraction, Cg-fraction; propylene fraction, butene fraction formed by a mixture of the previously cited pure products.

The deasphalted oil comes either from the asphalt removal or from the asphalt removal followed by a resin removal of heavy petroleum products such as the atmospheric residue, vacuum residue, capped heavy crude products, 3Q catalytic cracking residues, coal or oil tar without limitation , using one of the aforementioned solvents.

The volume ratio of solvent / oil called welte-solvent content in a deasphalting or depilating operation is usually 3/1 to 10/1.

The present invention is characterized in that it is applicable only when: t 1) the step of supercritical pre-separation is biphasic "liquid-liquid", where the two separate phases can be considered either 8701097 '· -i -7- or as a heavy liquid and a light liquid or as a heavy liquid and a dense supercritical phase (a density higher than the critical density of the pure solvent). The qualification supercritical here refers to the asphalt removal solvent. This first condition "slightly supercritical" therefore precludes the formation of a heavy liquid and a vapor phase. It is preferable to avoid having to work with three phases.

IQ 2) The step of the final separation over the membrane is a supercritical pervaporation: the light liquid or the dense supercritical phase of the pre-separation step forms the "charge" of the mineral membrane, the permeate is formed by a "vapor1" or light supercritical phase (density less than or equal to the critical density of the pure solvent), where the retentate can be either single-phase, the charge then simply depleted of solvent or biphasic, then having a heavy liquid and a light liquid having a composition and properties 2Q substantially equal to that of the charge.

Preferably, the procedure is as follows: the crude extract coming from the asphalt removal part is brought to conditions of temperature and pressure and P 1, which are preferably in the following relations: Ts; P ^ T * P ^ 25 to effect two liquid phase separation, a heavy phase (A) which is rich in oil and a light phase (B) which is rich in solvent while separating both phases. Because of the economy, it will be preferred to assume P1 such that P ^ T · P ^^ ^ P ^; T ^, Tg, P ^ and P ^ are defined below -3Q: -T_, the minimum temperature of liquid-liquid separation s and is preferably + 15 ° C where T ^ is the temperature at which the rough extract is the asphalt removal unit leaves.

35 -P is a "technologically limited" pressure, it stems from L

from economics calculations and expresses the fact that from a certain pressure, the increase in investment costs cannot in any way be offset by a reduction in operating costs or by an increased operating flexibility of 4Q unit, 8701097 -8- * «*’ t

P_ can therefore be set at 85 bar in the case of deasphalting with propane, at 75 bar in the case of a deasphalting with butane, at 68 bar in the case of a deasphalting with pentane and at 65 bar in the case of a de-asphalting with hexane.

Tj-j and Pb indicate the boiling temperature and the boiling pressure of the deasphalted oil and deashing altering solvent mixture respectively: in the very first approximation, the torque Tb, Pb is given by the extension of the curve IQ of the solvent vapor pressure beyond critical point »Certain characteristic values have been included in table 1 ._, __

Propane__n-Butane__n-Pentane__n-Hexane

Pb (bar) Tb (° Cj Pb (bar) Tb (° C) Pfa (bar) Tb (° C) Pb (bar) Tb (° C) 15 43 99 4Q 161 40 212 35 250 47.5 104 45. 169 45 220 40 261 55 112 50 176 50- 228 45 271 62.5 121 55 185 55 236 50 280 70 129 60 191 60 245 55 289 2Q 77.5 137 65 198 65 251 60 298 85 144 70 203 68 253 65 304 __75_209 __

For the indicated pressures Pb, the values "Tb" indicated in the table actually represent an estimate of the maximum value that the real Tb could achieve.

The actual boiling temperature depends, of course, on the oil content of the mixture and on the nature of said oil on the one hand, and on the composition of the deasphalting solvent which will generally be a fraction and not a pure product. On the other hand, the invention is not limited to the above values and the skilled person will be able to make the necessary adjustments.

In order to fulfill the second condition, ie the formation of a supercritical pervaporation over the membrane and in particular to avoid dealing with a liquid light or supercritical dense phase downstream of the membrane, the following is preferred: first light phase (B1 which is rich in solvent is passed in tangential filtration along a porous inorganic membrane 870 1 0 3 7 -9- at a tangential speed V, a load loss & P is applied across the membrane without adding additional heat feed the permeate in such a way that it relaxes adiabically V is preferably between two limits V y V2 and ΔΡ is also preferably between two limits> jlP2v The permeate forms a solvent phase which will be recirculated to the deasphalting step after thermal exchange The retentate is formed by either one or two liquid phases, the IQ total being enriched in oil as compared to of the first stage (B), and said retentate can be recirculated to the supercritical liquid-liquid pre-separation stage.

The preferred values of "V2" are defined below: The maximum tangential velocity V1 is set at 30 m.sec. , it is estimated that above that the polarization layer that forms is too thin, which implies a decrease in the selectivity. The minimum tangential velocity V9 isui -1 ^ fixed at 0.3 m.sec. below that, it is assumed that the polarization layer that forms is too thick and the permeate flow rate becomes too small.

The maximum pressure difference 4P1 between the two sides of the membrane depends on the mechanical resistance of the membrane support, this upper limit will generally be between 12 and 80 bar depending on the implementation of said support. The minimum differential pressure dP2 is arbitrarily set at 3 bar, below which the permeate flow rates become too small. The permeate side pressure is determined to have a super-3Q critical phase downstream of the membrane corresponding to the density condition of step (b) of the process.

Preferably, an inorganic membrane is used with a beam diameter of 2 to 10 nanometers and particularly preferably a pore radius of 2-4 nanometers. The porous ultrafiltration membrane may be one of those described in the prior art and, for example, in U.S. Pat. Nos. 4 06Q 488 or 4 411 790 or French Patent 2 55Q 953; according to these patents, the membrane may comprise a porous support of metal, 4Q ceramic or equivalent on which is deposited a thin material which is at least 8701097 (►-10-) formed by a metal compound, for example one of the oxides of the following elements: titanium, zirconium, magnesium, silicon, aluminum, yttrium, hafnium, mixed oxides of several of these metals with or without silicon, boron oxide or an alkali or alkaline earth metal fluoride, a silicon carbide or a silicon nitride etc.

According to the application of the method, it will be possible to bring the membranes in ultrafiltration modules to one IQ in a variable number. These modules can be placed in series or in parallel. The number of such modules depends, of course, on the selectivity of the mineral ultrafiltration membranes, on the nature of the charge, on the desired degree of enrichment for the two fractions, on the respective viscosities of the charge and on the permeate. and the temperature and pressure conditions selected.

In the description of the invention, the term "membrane" has been used for the sake of simplification, but will therefore refer to both a single membrane and an assembly of mem-2 (1 branes.

The principle of the invention will become clearer to the reader after considering the figures and the accompanying explanations. Figure 1 represents a first variant of the invention in which only asphalt and deasphalted oil are formed. Figure 2 shows a second variant of the invention in which asphalt, resin and deasphalted and dehaxed oil are formed.

According to Figure 1, the residue is fed into line 3Q and the solvent into line 29 into the reactor or series 3 3 deasphalting reactors 1, which preferably operate under slightly critical conditions. The heavy fraction formed by asphaltenes as well as a little solvent is discharged through line 24 to the solvent recovery stage 25 formed by low pressure evaporation (flash) 35 and final steam stripping, the asphalt is recovered at 26 and the recovered solvent is discharged through line 27. The light fraction formed by deasphalted oil and the major part of the solvent (at least 9%) is discharged through line 2 and heated in 870 1 09 7 -11 heat exchanger 3 and oven 4 to the supercritical conditions and to achieve. The then biphasic mixture is clarified in the separator 5.

The light liquid phase which is enriched in solvent 5 and is formed, for example, by at least 83% solvent and in most cases at least 88% solvent and at most 93.5% solvent is discharged through line 6 to the filtration assembly 9. It goes in tangential filtration along the membrane 7 at a rate V. The portion that has not passed IQ through the membrane, or the retentate, has been substantially depleted of solvent; it is either single-phase or biphasic and its global solvent content depends on tangential filtration conditions. It is preferably approximately equal to the solvent content of the mixture withdrawn from the deasphalting reactor through line 2. This retentate is added to the stream in line 2 downstream of the furnace 4. The portion that has been vaporized through the membrane or a permeate is under slightly supercritical conditions; P ^ - 4? and T2, where T2 is due to the adiabaric relaxation of the permeate. <ΔΡ represents the difference in pressure between the two sides of the membrane.

The composition of said supercritical phase preferably contains at least 94% by weight of solvent and in the majority of cases at least 97% of solvent, this stream is discharged via line 8.

The heavy liquid phase released by the separator 5 consists of at least 45% by weight of deasphalted oil and in most cases of about 55% by weight of deasphalted oil.

It is passed through line 11 and then reheated in 3Q the exchanger 12 and the furnace 3, the then biphasic mixture is clarified under supercritical conditions (defined in French patent application 8 515 5521 in separator 14).

The gaseous or light phase, which preferably consists of at least 97.5% solvent, is discharged to line 8 through line 19. The total of the solvents are then pumped into 20 through exchanger 3 where it cools while relinquishing its heat to the mixture. in line 2. The cooled solvent is then vented (21) to the hot solvent storage capacity 22 prior to pooling over line 23 with the supply of solvent 29, The 8701097 + -12 liquid phase, which is preferably consisting of at least 80% deasphalted oil is vented through line 15 and then relinquishes its heat in exchanger 12 before joining the solvent recovery step 16 formed by low pressure evaporation (flash) and steam stripping. The deasphalted oil is discharged at 18 and the recovered solvent is discharged through line 17, the total cold solvent from lines 17 and 27 comes together with the solvent supply 29 through line 28.

It is clear that instead of separating the solvent from deasphalted oil (line 11) by supercritical clarification (14) followed by evaporation (16), one can also work with simple distillation by directly mixing the mixture from line 11 in an evaporation unit 16 to feed. However, the thermal efficiency of the operation is clearly less advantageous, so that the first embodiment, which is shown in Figure 1, is preferable.

According to; Figure 2, the residue is fed via line 30 and the solvent via line 29 into the reactor or into the 2Q series reactors 1 for removing asphalt which preferably operate under slightly sub-critical conditions. The heavy asphaltenes fraction as well as a little solvent is discharged through line 24 to the solvent recovery stage 25 formed by low pressure evaporation (flash) and final steam stripping, the asphalt is recovered at 26, and recovered solvent is discharged through line 27,

The light fraction formed by deasphalted oil and the major part of the solvent (preferably at least 90%) is removed through line 2 and heated in exchanger 3. supercritical conditions and achievable.

The then biphasic mixture is clarified in separator 5, the oven 4 of figure 1 is generally not necessary here,

The heavy liquid phase which is preferably at least 50% resin 35 and in. in most cases containing at least 57.5% resin, it is discharged through line 11 to the solvent recovery stage 31 formed by low pressure evaporation (flash) and steam stripping, the resin is collected at 32 and the recovered solvent is discharged through line 27, 8701097 -13-

The light liquid phase is preferably formed by at least 75% solvent and in most cases at least 80% solvent and at most 90% solvent and is discharged through line 6 to the filtration assembly 9. It passes 5 through tangential filtration at a velocity V the membrane 7. The portion that has not passed through the membrane or retentate is either monophasic or biphasic and its global content is at least 30% by weight of oil and in most cases at least 37.5% of oil. This retentate is drained through IQ line 12 and heated in the exchanger 12 and the furnace 13, the then biphasic mixture is clarified in the separator 14, under supercritical conditions.

The light phase, which preferably consists of at least 97.5% solvent, is discharged through line 19 to line 8.

The total solvent is then pumped into 20 through exchanger 3 where it cools, relinquishing its heat to the mixture in line 2. The cooled solvent is then discharged through line 21 to the hot solvent storage 22 before passing through line 23 with the supply 2Q of solvent 29 to come together.

The liquid phase, which preferably consists of at least 80% deasphalted oil, is discharged through line 15 and then transfers its heat in exchanger 12 before coming together with solvent recovery step 16 formed by low pressure evaporation (flash) and flow stripping * The asphalt and resin depleted oil is discharged into 18 and the recovered solvent is discharged through line 17. The total cold solvent from lines 17, 27 and 33 comes together with the solvent supply 29 through line 33, 3Q. have been unable to use supercritical separator 14 and have been able to supply the power from line 10 directly to evaporator 16; however, the thermal efficiency would be less good.

Examples.

Examples 1 and 2, respectively, are intended to illustrate the liquid-liquid separation (a) and the following tangential filtration step (b). Examples 3 to 6 represent a complete mode of operation of the invention - without forming a resin fraction (examples 3, 4 and 51 8701097 -14- * w using as an extraction solvent of pentane, butane and propane, respectively - to form a resin fraction (Example 6) using pentane as a solvent.

By way of illustration, the analyzes of the crude load, of the asphalt removal solvents and of the de-asphalted oils which are representative are given below.

The percentages are percentages by weight.

Vacuum residue from Arable heavy (A) IQ, 15.

d. = 1.037

Asphaltenes Cy = 15.25%

Carbon Conradson -22.95% sulfur = 5.42% ..ihickle = 50 ppm vanadium = 167 ppm 15 Pentane fraction (B) dj5 = 0.630

Cr = 0.21 wt%, iCr = 23.40 wt%, nCr = 75.74 wt%, CI = 0.65 wt%

Butane fraction (C) 2Q dj | 5 = 0.580 (measured at 3 bar absolute) C "= 1.38; wt%, IC4 = 31.23%; butene 14 isobutene = 15.67 wt% nC4 = 34.88%; butene 2 trans = 9.14%, butene 2 cis = 7.18%, C + = 0.52%

Propane fraction (D) 25 = 0.505 (measured at 10 bar absolute) CJ = 1.47 wt%, propene = 16.22%, = 80.17%; = 2.14%

With pentane of asphaltedtane oil (E) d1 ^ = 0.995

Asphaltenes C ^ = 0.42%! Asphaltenes Cy = 0.04Q%;

Carbon Conradson = 11.6%;

Vanadium = 35 ppm I Efficiency at

Nickel = 6 ppm; Residue A = 68.30%

Sulfur = 4.57% j 35 nD 20 = 1.543 i

Oil removed from asphalt with butene. (F) dX4 = 0.987;

Asphaltenes Cj = 0.085% "Cy = 0.007% 8701097 -15-

Carbon Conradson = 7.85%

Vanadium = 28 ppm; Return at

Nickel = 5 ppm residue A = 53.15%

Sulfur = 3.38% 5 nd 20 = 1.529;

Oil depleted with asphalt (G) d15 = 0.982

Asphaltenes s 0.009%

Carbon Conradson = 4.05% j Efficiency at 10 Vanadium = 12 ppm residue A - 34.64%

Nickel = 2 φπι

Sulfur = 2.94% nD .20 = 1'507

Example 1.

The vacuum residue (A) is contacted with the pentane fraction (B), the volume content of solvent (expressed 3 at ambient temperature) is 4 m / m. The column is operated with a top temperature of 180 ° C and a relative pressure of 40 bar. In this way, the deasphalted oil (E) and an as-2Q form with a ring ball point of 168 ° C are formed.

The crude extract (23.4 wt%) mixed with the solvent (76.6 wt%) leaving the top of the extractor is subjected to various temperature and pressure conditions (202-205 ° C) 45-50 bar to give a liquid liquid separation. On the one hand, a light liquid phase consisting essentially of solvent and asphalt and resin-depleted oil is obtained, and on the other hand, a heavy liquid phase consisting of 50 to 55% resin and 50 to 45% solvent (see Table 1, lines 1 to 4).

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In a second series of tests, the initial deasphalting operation is carried out with a solvent content of 3 3 6.7 m / m, all other variables remaining the same. The crude extract (15 wt%) mixed with the C C fraction (85%), 5 leaving the extractor head is brought to 55 bar and at different temperatures .: (lying between 201 and 211 ° C) . There is still obtained a liquid-liquid separation, the characteristic properties of which are given in Table 1 (lines 5-7).

IQ The vacuum residue (A) is brought into contact with the butane fraction (C), the solvent volume content (expressed 3 at ambient temperature) is 5 m / m. The column is operated with a top temperature of 130 ° C and a relative pressure of 40 bar. In this way, asphalt de-oiled (F) is formed and an ash-fat with a ring ball point of 122 ° C is formed.

The crude extract (17.5 wt%) mixed with the solvent (82.5%) is brought to various conditions of temperature between 143 and 147 ° C and pressure between 52 and 56 bar absolute, to achieve a liquid-liquid separation to obtain 2Q. On the one hand, a light liquid phase consisting essentially of solvent and oil which has been cleared of asphalt and resin is obtained, and on the other hand, a phase consisting of 57 to 62% resin and from 40% to 45% by weight butane fraction, see Table 2.

Example 2 (Table 3).

In this comparative example, the performance of the various filtration elements in terms of their selectivity and their permeate flow rates is also examined, and the importance of the supercritical pervaporation 3Q over the subcritical pervaporation or is also brought to the fore. liquid ultrafiltration on the upstream and downstream sides of the membrane.

The filtration elements are pipes with a length of Q, 75 meters and 7 mm internal diameter. The interior of these tubes is coated with a filtration layer whose pore radius can be 2 nm, 3 nm or 4 nm.

The permeate flow rate is expressed in 1 / h for one element and 3 2 in m / day / m, the selectivity S is expressed by (H charge / (1-H charge)) / (H permeate / (1-H permeate)) where H charge is the 8701097-18 weight fraction oil in the charge and H permeate is the weight fraction oil in the permeate.

A first subcritical pervaporation test is carried out by circulating 600 l / h with an effective pressure of 22 bar and a temperature of 180 ° C of a mixture of 23.5% de-ashed oil E and Cg fraction (B ) where the tangential velocity along the 3 nm pore radius filtration media is therefore 4 m / sec. amounts. The load loss through the membrane is set at 8 bar and the permeate is collected in gaseous form IQ. It is then condensed at 140 ° C and then either put into the storage containing the mixture to be filtered or cooled to ambient temperature and annealed for flow measurement and analysis. Under these conditions it yields 1.675 l / h permeate containing 1.5 wt% oil.

Two filtration tests of the foregoing mixture are then carried out with a liquid state prevailing upstream and downstream with circulation of 600 l / h at 32 bar effective and 18 ° C first in an element with a pore radius of 2 nm, then in an element with a pore radius 2Q of 4 nm. The load loss is reset to 8 bar.

The flow measurements and analyzes are as follows: pore radius 2 nm: 0.186 l / h mixture containing 0.18 wt% oil pore radius 4 nm: 1.49 l / h mixture containing 12.45% oil.

25 The advantage of supercritical pervaporation is clear from the following two tests:

The foregoing mixture is introduced at an equal mass flow rate (i.e. here 680 l / h) 48 bar and 210 ° C into an element with a pore radius of 3 nm. The load loss through the 3Q membrane is set at 8 bar. Under these conditions, 10.17 l / h of mixture containing 5.9% oil is collected.

A mixture of 12.85% deasphalted oil and 87.15% Cl 2 fraction is passed through a filtration element with a pore radius of 3 nm, 720 l / h under 48 bar and 21 ° C. The tax loss. through the membrane there is still 8 bar. Under these conditions, 13.80 l / h of mixture containing 3.10% deasphalted oil is collected.

The flow rate and selectivity are maintained when the solvent is changed.

8701097 -19-

A filtration tube with a pore radius of 3 ran is again used. 540 L / h under 50 bar at 145 ° C is passed through from a mixture consisting of 7.35% deasphalted oil and 92.65% butane fraction. A load loss of 6 bar 5 is set over the membrane. It is cooled to ambient temperature and the permeate is let out at 3 bar to measure the flow and then analyze it. Under these conditions, 9.78 l / h mixture containing 1.57% oil is collected.

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Example 3 (Figure 1).

Hen injects 3 tons / h of vacuum distillable residue (A) via line 30 and 8.48 tons / h of line from line 29 of a mixture of 97.8 wt.% Fraction (B) and 2.2% recirculated deasphalted oil in a mixing zone followed by a clearing zone 1, the assembly being constructed as an asphalt removal zone; the pressure is then 53 bar and the average temperature is 190 ° C. Under these conditions, the mixture separates into two phases. 1.56 ton / h of an IQ mixture consisting of 61.5% by weight of asphalt and 38.5% solvent is drained via line 24, the latter being evaporated (flash) at low pressure and then stripped with steam in zone 25. 0.96 ton / h asphalt 26 and 0.6 ton / h solvent 27 are discharged from this zone and returned via lines 28 and then 29.

9,921 ton / h light phase is drawn off through line 2, which is formed by 22.45 wt.% Deasphalted oil and 77.55 wt. This mixture is reheated to 210 ° C in the heat exchanger 3 and then to 215.5 ° C in the oven 4; at that time the pressure has dropped to 48 bar due to load 2Q loss. 5,895 ton / h mixture is then added to this stream and fed with line 10 consisting of 22.45 wt% deasphalted oil and 77.55 wt% solvent. In the separator 5, the assembly separates into two liquid phases. The light liquid phase (12,084) ton / h) consisting of 12.46 wt% deasphalted and de-waxed oil is discharged through line 6 to the filtration assembly 9. This phase passes through membrane 7 at a tangential initial velocity of 4 m-sec. " 1. The permeate in an amount of 6.174 ton / h is discharged through line 8, it consists of 2.92 wt.% De-3 asphalted and de-waxed oil and 97.08 wt.% Solvent, the temperature has dropped to 210 ° C and the pressure up to 40 bar.

The temperature drop is only 5.5 ° C, demonstrating the advantage of pervaporation under supercritical conditions. The selectivity factor is S = ^ '9'2 / 97' '' 'θ8 * 4.74.

35 The average specific permeate flow rate of 18.1 m ^ / day / m ^ (expressed at ambient temperature and pressure) implies a total membrane surface area of 16.1 mv. To form the membrane 7, assemble parallel assemblies formed by a series of elementary tubes (described in Example 2 with an 8701097-22 pore radius of 3 nm. The retentate discharged through line 10 is recycled to separator 5.

The liquid heavy phase (3,747 ton / h) which is formed by a deasphalted oil that has not been de-waxed (54.6 wt%) and solvent (45.4 wt%) is passed through line 11 to exchanger 12 where it is again warmed to 233 ° C and oven 13 where it reaches 255 ° C, at which point the pressure has dropped to 40 bar, due to load loss. The then biphasic mixture, which is under IQ under supercritical conditions, is clarified in separator 14. Via line 15, 2.319 ton / h heavy phase is formed, formed by 87.97% deasphalted oil and 12.03% solvent. This phase cools to 227 ° C while relinquishing its heat to the flow from line 11 in exchanger 12, it then enters zone 16 where it is evaporated (flash) at low pressure and then stripped with steam. Through line 18, 2.04 tons of deasphalted oil are discharged, through line 17, 0.279 tons / h of solvent is returned to lines 28 and 29. Through line 19, 1,407 tons / h of light phase (supercritical 2Q vapor) is removed composed of 99.6 wt% solvent and 0.4% deasphalted oil. The flows in the pipes 8 and 19 terminate at the pump 20. Downstream of this pump, the pressure is 40 bar and the temperature is 218.5 ° C; after adiabatic compression, the flow is at 229 ° C and 55 bar, it then flows through exchanger 3 where it comes out at 204 ° C, after relinquishing its heat to the mixture of line 2; the line 21 leads it to the storage capacity 22 from where the line 23 leads it to the liquid injection 29.

Example 4 (Figure 1).

3Q In the deasphalting zone (1), 3 tons / h vacuum residue (A) and 9.745 tons / h of a mixture of 98.8% fraction (C) and 1.2% recycled asphalted oil are injected, under a pressure of 57 bar and an average temperature of 130 ° C.

Two phases separate: 35 - The heavy phase which is treated in assembly 25 forms 1.5 ton / h asphalt (line 26) and 0.9 ton / h solvent (line 27).

- The light phase (10,345 ton / h) mixture with 15.63% deasphalted oil and 84.37% C4 fraction is reheated to 8701097 -23- 142 ° C in exchanger 3, then to 150.5 ° C in oven 4. To this stream is added 3.975 ton / h of recycled retentate containing about 15.70% deasphalted and de-waxed oil and 84.30% C4 fraction. The mixture separates in separator 5 under a pressure of 52 bar. The light liquid phase (11,823 ton / h) consisting of 6.27 wt% oil and 93.73 wt% butane fraction is fed to the filtration assembly 9, the initial tangential velocity along the membrane 7 being about 4 m / sec. amounts. The permeate (7.848 10 ton / h) consists of 98.5% fraction and 1.5% dehaxed and deasphalted oil is discharged to line 8, its temperature dropping by 146 ° C and its pressure to 44 bar.

The temperature drop is only 5.5 ° C, the selectivity factor has been S = x 9 '| "f" so = 4'39, the specific average permeate flow rate (expressed at ambient temperature and 3 2 3 bar) is about 12, 2 m / day / m. The retentate is recycled through line 10 to separator 5. The heavy liquid phase (2,496 ton / h) consisting of 60% deasphalted oil and 40% C4 fraction is reheated to 178 ° C in exchanger 12 and then to 195 ° C in oven 13 while the pressure has dropped to 44 bar as a result of tax loss. This mixture separates in separator 14. The heavy phase relinquishes its heat in exchanger 12 from where it leaves again at 166 ° C to be treated in assembly 16 from which 25 of 1.5 ton / h deasphalted oil is discharged 18 and 0.204 ton / h fraction (line 17). The light phase with 0.792 ton / h C4 fraction returns via line 19 to line 8 and then to pump 20. The temperature and pressure are 44 bar and 150.5 ° C upstream? after adiabatic compression, conditions at the downstream side are 161 ° C and 59 bar. This stream cools to 144 ° C in the exchanger 3, and is then passed to the buffer reservoir 21 before being recycled to line 29.

Example 5 (Figure 1).

In zone 1, under a pressure of 68 bar and an average temperature of 85 ° C, 3 tons / h vacuum residue (A) with 15.115 tons / h of a mixture of 0.83% recirculated oil and 99.17% Cj is treated fraction (D). 3.3 ton / h heavy phase are treated in zone 25 from which 1.95 ton / h asphalt (26) and 1.35 ton / h 40 solvent (27) are discharged. 14.814 Ton / h light phase 8701097 -24- (7.94% deasphalted oil and 92.06% C3 fraction) are reheated to 101 ° C in exchanger 3 and then to 110 ° C in oven 4. It is added this flow increases 17.226 ton / h recirculated retentate (7.97% dehaxed and deasphalted oil and 92.03% fraction). The assembly clears in separator 5 under a pressure of 63 bar. The liquid light phase of 29.94 ton / h (5.01% oil, 94.99% C3 fraction) is passed to the filtration assembly 9; the tangential -1 initial velocity along the membrane 7 is 4 msec. . The IQ permeate (12.714 ton / h: 1% oil and 99% C3 fraction) is collected at 105 ° C and 55 bar, then discharged through line 8. The temperature drop has been only 5 ° C, while 01/94 99 the selectivity S = - 'g · ^ - = 5.22 is slightly greater than with the other solvents, on the other hand, the average specific flow rate of permeate (expressed at ambient temperature below 10 bar) is slightly weaker than with the two' 3 2 solvents : 9.1 m / day / m,

The retentate is recycled through line 10 to separator 5.

20 - The heavy liquid phase (2.1 ton / h: 50% oil and 50% C3 fraction), is reheated to 124 ° C in exchanger 12, then to 145 ° C in oven 13. Clarification is below 55 bar in the separator 14, The heavy phase (1,236 ton / h) relinquishes its heat in exchanger 12 and leaves it at 125 ° C, 25 it is separated into 16 in 1.05 ton / h deasphalted oil (18) and 0,186 ton / h C3 fraction (17). The vapor phase (0.864 ton / h C3 fraction) returns to line 8 and then to pump 20: conditions on the upstream side are 55 bar and 108 ° C. After adiabatic compression, this flow is brought to 117 ° C and 70 bar. This stream is cooled to 99 ° C in exchanger 3, the line 21 returns it to the buffer capacity 21 from where it is recirculated to the line 29.

Example 6 (Figure 2).

35 tons of vacuum distillation residue (A) are injected through line 30 and 8.862 tons / h through line 29 of a mixture of 96.34% by weight of Cg fraction (B) and 3.66% by weight of recirculated deasphalted oil, in a mixing zone followed by a clearance zone 1, the assembly being designated as asphalt-4Q removal zone; the pressure is then 50 bar and the average temperature 8701097 -25- 178 ° C. Under these conditions, the mixture separates into two phases. 1.32 ton / h of a mixture consisting of 61.36% by weight of asphalt and 38.64% solvent is drained through line 24, which is evaporated (flashed) at low pressure, then stripped with water vapor in zone 25, from which 0.81 ton / h asphalt (26) is discharged and 0.51 ton / h solvent (27) which is returned to lines 28 and then 29.

10.362 ton / h light phase is drawn off through line 2 formed by 24.20 wt.% De-ashed oil and 75.80 wt.% C. fraction.

This mixture is reheated to 201.5 ° C in exchanger 3; at that time the pressure has dropped to 45 bar due to load loss. Two liquid phases are allowed to separate in the separator 5, in which supercritical conditions prevail.

The 0.546 ton / h heavy liquid phase formed by 54.95% resins and 45.05% solvent is discharged through line 11 to zone 31 where it undergoes low pressure evaporation (flash) and steam stripping. Through line 33, 0.246 ton / h of solvent is recovered and 0.3 ton / h of resins are discharged through line 32.

The light liquid phase (9,816 ton / h) formed by 22.49% dehaxed and deasphalted oil is discharged through line 6 to the filtration assembly 9. This phase travels at a initial initial speed of 4 m-sec. ”1 along the membrane 7. The supercritical permeate formed by 4.908 ton / h mixture of 6.3 wt% deasphalted and de-waxed oil and 93.7% fraction has cooled to 197.5 ° C while its pressure has dropped to 37 bar. The temperature drop has been only 4 ° C, which demonstrates the advantage of the supercritical pervaporation. The selectivity factor has been 3Q S = ^ = 4.32. The mean specific permeate flow rate of 12.4 n / m / day (expressed at ambient temperature and pressure) implies a total membrane area of 23.75 m. The retentate discharged through line 10 (also 4,908 ton / h), consisting of 38.7% deasphalted and 35 de-waxed oil and 61.3% solvent, is sent to exchanger 12 where it warms to 216 ° C and the furnace 13 in which it 250 ° C reached. At that point, the pressure has dropped to 37 bar due to load loss. The then biphasic mixture separates in the supercritical separator 14. Through line 4Q, 2.124 heavy phase is drained, formed by 88.98% deashing 8701097-26-phthalated oil and 11.02% solvent. This phase cools to 216 ° C, relinquishing its heat from the flow of line 10 into the exchanger 12, it then enters the zone 16 where it is evaporated (flash) at low pressure, and then with steam is stripped. Line 18 carries 1.89 ton / h deasphalted oil, through line 17 0.234 ton / h solvent is discharged to lines 28 and 29. Line 19 discharges 2.784 ton / h light phase (vapor ) consisting of 99.6% solvent and 0.4% deasphalted IQ oil. The flows of the pipes 8 and 19 open up to the pump 20. Upstream of this pump the pressure is 37 bar and the temperature 216.5 ° C; after adiabatic compression, the flow is at 226 ° C and 50 bar, it then flows through exchanger 3 which it leaves at a temperature of 192 ° C after 15 having transferred its heat to the mixture in line 2, line 21 takes it with it to the buffer capacity 22 from where the line 23 returns it to the solvent injection 29.

- Conclusions - 8701097

Claims (10)

1. Asphalt removal process, in which a hydrocarbon oil containing asphalt is subjected to a treatment with an asphalt removal solvent to form two phases and said two phases are separated to separate a light oily phase (rough extract) and a heavy asphalt-containing phase. (crude raffinate) and the solvent is separated from each of the above-mentioned phases, characterized in that in order to separate the solvent from the light oily phase, one operates in at least three steps: IQ a) in a first step the light oily phases under supercritical conditions with respect to the solvent to effect a two phase separation, a light phase rich in solvent and a heavy phase rich in oil and said two phases apart separates, the operating conditions being moderately supercritical, ie such that the solvent-rich light phase is a liquid f ase (or dense supercritical phase, i.e., with a density higher than the critical density of the pure solvent); b) in a second step, the light phase, which is rich in solvent, and which is separated in step a), is subjected to a tangential filtration which is controlled by circulation on the side upstream of an inorganic porous membrane, the operating conditions on the downstream side of the membrane include a pressure lower than that on the upstream side, but the pressures are nevertheless sufficient to allow the permeate to consist of a vapor (or supercritical light phase i.e. 3Q with a density of is less than or equal to the critical density of the pure solvent) and therefore, separately, on the downstream side of the membrane, one catches said light supercritical phase, which is rich in solvent and on the upstream side the remaining part that has not passed through the membrane called retentate and includes the de-asphalted oil which is poor in release agent and 8701097 -28- c) in a third step, the heavy fraction which is rich in oil and separated in step a) is fractionated to separately obtain a solvent phase and a hydrocarbon-containing phase containing resins. Process according to claim 1, characterized in that said step c) is carried out by supercritical fractionation comprising heating the oil-enriched heavy phase from step a) to separate it into two phases, separating said phases and delete. 10 by evaporation of. the residual solvent that is in the heaviest phase. 3. Process according to claim 2, characterized in that the supercritical fractionation is carried out under supercritical conditions much stricter than those of step a) and such that the resulting solvent-rich phase is gaseous or has a density that is is less than the critical density of the pure solvent. Method according to one or more of claims 1 to 3, characterized in that the retentate containing the deasphalted 2Q oil and residual solvent is subjected to a solvent-deasphalted oil fractionation to form a heavy phase of deasphalted dehaxed oil which is low in solvent and a light solvent to extract. '' 5. Process according to claim 4, characterized in that the solvent-deasphalted and de-waxed oil fractionation is carried out under supercritical conditions more severe than those of step a) and such that the obtained light solvent phase is gaseous or supercritical with a density lower than the critical density of the pure solvent. Method according to one or more of claims 1-3, characterized in that it comprises; the retentate is mixed with the light oil-containing phase (crude extract) and in mixture therewith subjected to the supercritical conditions of step a], wherein the hydrocarbon-containing phase obtained in step c) is then formed by a hydrocarbon-containing phase which simultaneously contains deasphalted oil and resins, 8701097 -29- Method according to one or more of claims 1 to 6, characterized in that the moderate supercritical conditions of step a) comprise a temperature T1 and a pressure P. ^ such that Τ ^> Tg P ^? P ^ in which represents the minimum temperature of the liquid-liquid separation and and represents the boiling temperature and the boiling pressure of the light oily phase (crude extract) subjected to step a), respectively. Method according to one or more of claims 1-7, 10, characterized in that the circulation along the inorganic porous membrane in step b) takes place therein at a tangential speed of 0.3 to 30 m.sec.-1. . Method according to one or more of claims 1-8, characterized in that the inorganic membrane contains pores 15 with a radius of 1-10 nanometers. Method according to one or more of claims 1-8, characterized in that the inorganic membrane contains pores with a radius of 2-4 nanometers. 8701097