FR2939804A1 - Converting petroleum charges (having e.g. heavy crude), comprises deasphalting oil with heavy solvent and light solvent comprising saturated hydrocarbon, converting deasphalted oil by catalytic cracking and converting pitch by visbreaking - Google Patents

Abstract

Converting petroleum charges of which the boiling curve is such that less than 20 wt.% of the charge is distilled at 343[deg] C in ambient conditions, comprises: a first deasphalting with a heavy solvent comprising saturated 5C hydrocarbons; a second deasphalting on deasphalted oil obtained from first deasphalting, with a light solvent comprising a saturated 3-4C hydrocarbon; converting deasphalted oil obtained from the second deasphalting by catalytic cracking; and converting a pitch obtained from second deasphalting by visbreaking. Converting petroleum charges of which the boiling curve is such that less than 20 wt.% of the charge is distilled at 343[deg] C in ambient conditions, and more than 40 wt.% of the charge is distilled at greater than 500[deg] C, comprises: a first deasphalting with a heavy solvent comprising a content of saturated 5C hydrocarbons of >= 95%; a second deasphalting on deasphalted oil obtained from first deasphalting, with a light solvent comprising a saturated 3-4C hydrocarbon content of >= 95%; converting deasphalted oil obtained from the second deasphalting by catalytic cracking; and converting a pitch obtained from second deasphalting by visbreaking.

Description

PROCESS FOR THE VALORISATION OF HEAVY RAIN AND PETROLEUM RESIDUES

The invention relates to the treatment of heavy crudes and petroleum residues, for example resulting from the atmospheric distillation or the vacuum distillation of a petroleum fraction. More specifically, it relates to hydrocarbon feedstocks derived from petroleum whose boiling curve is such that less than 20% by weight of the cup is distilled at the temperature of 343 ° C under ambient conditions.

Crudes, in general, have varying levels of atmospheric residues that depend at least in part on their origin.

This content typically varies between 10-50% by weight for conventional crudes, but can reach 50 to 80% by weight for heavy and extra heavy crudes such as those produced in Venezuela or the Athabasca region in northern Canada. These crudes generally have a density of less than 20 ° API.

The heavier part of the heavy hydrocarbon feeds consists of a mixture of an oily phase and an asphaltic phase. It is usual to distinguish two families in the compounds constituting the asphaltic phase: resins and asphaltenes. Asphaltenes, like resins, include polycyclic aromatic structures, thiophene rings and pyridine rings. The resins include molecules having less condensed structures and lower molecular weights than structures present in asphaltenes. Petroleum residues contain heteroatoms. Thus, there are sulfur compounds in large quantities, typically: the sulfur content (S) is 0.5 to 7% by weight relative to the total weight of the feed, nitrogen compounds, typically the nitrogen content varies from 0.05 to 1% by weight relative to the total weight of the filler, - metals, Ni, V and possibly Fe ....

These heteroatoms are generally not distributed uniformly in all fractions. Thus, very often metals are found mainly in the Asphaltenes fraction, while sulfur and nitrogen are more concentrated in the Asphaltenes and Resins fractions. A trend has emerged in recent years to seek to recover oil residues, which is relatively difficult. Indeed, the market is mainly requesting distillable fuels at atmospheric pressure at a temperature below 320-360 ° C. It is therefore useful, if not necessary, to convert these heavy residues to produce smaller molecules.

The applicant has described in the patent application EP 0 246 956 the use of a deasphalting in two successive steps. The first deasphalting being carried out with a mixture of heavy solvents to precipitate the asphaltenes and the second with a mixture of light solvents to precipitate the resins. This process was aimed at producing a deasphalted oil which can be used as a filler for catalytic cracking. Indeed, a way to obtain light products from the oily phase is to submit it to a catalytic cracking. However, the catalytic cracking feedstock must not contain too many metals or have a high Conradson residual. It may be recalled that the Conradson residue gives indications of the tendency of a product to form coke.

The present invention aims to optimize the conversion of the residues in their entirety, that is to say including asphaltenes, resins, etc.. to produce light cuts and to enhance the heavy part having a boiling point higher than 500 ° C.

Thus, according to a first aspect, the subject of the invention is a process for converting petroleum feeds whose boiling curve is such that less than 20% by weight of the feedstock is distilled at the temperature of 343 ° C. under the conditions ambient, and more than 40% by weight of the filler is distilled at a temperature above 500 ° C, comprising: - a first deasphalting of said filler with a heavy solvent comprising a content of saturated hydrocarbons having at least 5 carbon atoms higher or 95%, - a second deasphalting of the deasphalted oil from the first deasphalting, with a light solvent comprising a saturated hydrocarbon content of 3 or 4 carbon atoms greater than or equal to 95%, - the deasphalted oil After the second deasphalting is converted by catalytic cracking (FCC), the pitch from the second deasphalting is converted by visbreaking.

The petroleum feedstock according to the present invention can be for example a heavy crude oil, an atmospheric residue and / or a vacuum residue from the distillation of a crude oil.

The combination of the process steps, i.e., double deasphalting, FCC and visbreaking, can provide a process for overall recovery of the residues with a greater margin compared to what was previously done. , while maintaining good product qualities and increasing yields of converted products. This invention therefore proposes a process in which the conversion is optimized by first separating the residue into different fractions, these different fractions then being converted by suitable methods. This results in a substantial gain in performance, the conversion being optimized and the yields and qualities of products in light cuts being improved. Successive deasphalting in two stages, the first being carried out by contact with a heavy solvent, preferably C5-C7, and the second with a light solvent, preferably C3-C4, makes it possible to optimize the yield of DEO cut (hydrogenated deasphalted oil, DeAsphalted Oil), a content especially greater than or equal to 11% by weight, containing few metals, in particular a content of less than or equal to 40 ppm and preferably less than or equal to 5 ppm, and coke precursors, especially no asphaltenes. The initial elimination of Asphaltenes by contact with the heavy solvent, in particular C5-C7, then allows by the implementation of a second C3-C4 deasphalting, a much more effective and selective separation between the resins and the resins. Saturated and Aromatic fractions. This results in an improvement in the yield of the DAO cut, with a similar content of metals and asphaltenes, compared to a deasphalting comprising a single step with a light solvent.

The main advantage of the implementation of the method according to the invention is that the resin content is higher in the visbreductor charge. This may in particular allow an increase in the conversion of the visbreducer. Indeed, when the charge of the visbroeductor has a high content of resins, it may have a better crackability, and therefore a better visbreaking behavior. In the present invention, improving the stability of the visbroken effluent is improved, which may allow in order to obtain equivalent stability to work at a lower visbreaking temperature.

In addition, the pitch resulting from the second deasphalting, intended to be used as a visor-reducing agent, has a better stability due to the elimination of the most unstable asphaltenes. Furthermore, the amount of pitch, for example for use as a solid fuel, is generally lower than a sequence of processes comprising a single deasphalting.

Preferably, the solvent of the first deasphalting is an n-paraffin having from 5 to 7 carbon atoms. The second deasphalting solvent may be an n-paraffin having 3 or 4 carbon atoms. In particular, the solvent of the first deasphalting is n-pentane and the solvent of the second deasphalting is propane and / or n-butane. The heavy solvent of the first deasphalting can comprise a content of saturated hydrocarbons having at least 5 carbon atoms, especially an n-paraffin having 5 to 7 carbon atoms, and in particular n-pentane, greater than or equal to 95%, even be composed of such hydrocarbons. The light solvent of the second deasphalting may comprise a content of saturated hydrocarbons having 3 or 4 carbon atoms, in particular at least one n-paraffin having 3 or 4 carbon atoms, and in particular propane and / or n-butane, which is greater than or equal to 95%, or even consist of such hydrocarbons.

Figure 1 illustrates the method according to the invention. A petroleum feedstock (10) is distilled under atmospheric conditions, in an atmospheric distillation column (1), and produces a substantial amount of a cut (11) of atmospheric residue or RAT.

In general, the cup (11) contains less than 20% by weight of distillable molecules at 343 ° C. under these conditions and at least 40% by weight relative to the weight of the cut treated above 500 ° C. C at atmospheric pressure. According to a preferred embodiment of the invention, this feed is distilled under vacuum in a column (2) for collecting a vacuum distillate (12), called DSV and a vacuum residue (13) called RSV. The DSV and RSV sections are cut at a temperature varying according to the crudes in a temperature range generally ranging from 480 to 565 ° C.

The DSV cut contains no or few Ni and V metals (<2 ppm) and the asphaltene content of the feed is less than or equal to 1% and most often 500 ppm. Its hydrogen content is greater than or equal to 11% by weight, and most often greater than or equal to 11.5% by weight. The RSV cut contains most of the asphaltenes and metals contained in the feed (10). Generally, the content of metals, in particular Ni + V, varies from 100 to 800 ppm depending on the charges treated. The viscosity of this section is important, especially ranging from 50 to 2000 Cst at 150 ° C, typically about 400 Cst.

Part of the RSV (15) is then sent to the first deasphalting step (3), in which the residue is brought into contact with a heavy solvent consisting essentially of saturated hydrocarbon molecules containing from 5 to 7 carbon atoms, preferably from pentane, n-hexane or n-heptane.

After contact, two phases are formed, one consisting of the parts of the non-soluble residue in the solvent is said phase Brai or Asphalt (17), the other consisting of the solvent and parts of the soluble residue. The solvent is distilled off from the soluble parts and recycled internally to the deasphalting process (3). It is obtained a soluble fraction (16) called DAO cut phase for DesAsphalted Oil cut.

This fraction (16) is then sent to the second deasphalting step (4), in which it is brought into contact with a light solvent consisting essentially of saturated hydrocarbon molecules containing from 3 to 4 carbon atoms, preferably n-propane or n-butane.

After contact, two phases are formed, one consisting of the parts of the non-soluble residue in the light solvent is said phase Brai or Resin (19), the other consisting of the solvent and parts of the soluble residue. The solvent is distilled off from the soluble parts and recycled internally to the deasphalting process (4). The solvent-free soluble fraction (18) is called the DAO cutting phase resulting from the second deasphalting. The DAO cut (18) contains small amounts of metals, Ni + V <35 ppm, which can vary depending on the solvents used.

In a preferred form of the invention and according to FIG. 1, the vacuum distillate (12) originating from the vacuum distillation (2) of the crude oil is sent to catalytic cracking (5) mixed with the deasphalted oil resulting from second deasphalting (18) to produce the feedstock (20) of the fluidized bed catalytic cracking (FCC) process. In this mixture, the metal content is preferably less than 2 ppm, the asphaltenes content preferably less than 500 ppm and the hydrogen content greater than 11% by weight, preferably 11.5% by weight. The characteristics of this feed are favorable to catalytic cracking. Preferably, the deasphalted oil resulting from the second deasphalting represents up to 50%, preferably up to 30%, of the total charge of the catalytic cracking.

It would also be possible to treat in FCC only DAO, the DSV cut being treated in other processes.

According to another mode, the DSV (12) is partially treated with FCC mixed with the DAO (18), the other part being treated elsewhere.

The catalytic cracking is carried out in a reaction zone containing a reaction chamber and a catalyst regeneration chamber between which the catalyst circulates continuously. The filler (20) is vaporized on contact with hot regenerated catalyst and reacts with the catalyst in the reactor. The temperature at the end of the reaction is typically between 500 and 600 ° C, preferably 520-540 ° C, the ratio between the catalyst flow rate and the feed rate being between 4 and 15, preferably between 5 and 8. The products of reaction are then separated by distillation downstream of the reactor. The catalyst is regenerated by combustion with air to remove coke deposited during the reaction and heat the catalyst. All the coke produced by cracking is therefore consumed by combustion during regeneration.

On the other hand, the resin or deasphalted oil fraction resulting from the second deasphalting (19) is sent to the visbreaking unit (6).

In a preferred form of the invention and according to FIG. 1, the vacuum residue (14) resulting from the vacuum distillation (2) of the crude oil is sent to the visor reducer (6) in mixture with the pitch resulting from the second deasphalting (19) to produce the charge (21) of the visbreaking unit (6).

Preferably, when the vacuum residue is sent into the visor reducer in admixture with the deasphalted oil resulting from the second deasphalting, the pitch resulting from the second deasphalting represents up to 50%, preferably up to 30%, of the total charge. visbreaking gear.

According to a preferred embodiment of the invention, the pitch resulting from the first deasphalting is used as a solid fuel.

Examples We evaluated the performances of the conversion scheme according to the invention, to evaluate the vacuum residues A and B whose properties are reported in Table 1 below.

Table 1: Properties of vacuum residues studied RSV A RSV B Density at 1014 1028 15 ° C (kg / m3) S (% wt) 4.7 4.1 Ni (ppm) 70 18 V (ppm) 240 66 CCR (% wt) 13.9 19.8 Asphaltenes C7 (% 10.3 5.6 wt) 500 ° C cut + 42.4 92.3 We have studied the performances, especially in visbreaking, which we obtain at Through two routes: According to the first route, known to those skilled in the art, a vacuum residue B is sent to the visbreducer. According to the second channel according to the invention (for example see FIG. 1), a vacuum residue A undergoes two successive deasphalting operations. The first deasphalting is carried out in the presence of n-pentane. The deasphalted oil from the first deasphalting is further deasphalted with n-propane. Then, the pitch resulting from this second deasphalting is sent, mixed with a portion of the vacuum residue B, to the visbreaking agent.

Deasphalting tests: An autoclave configured in deasphalting mode is used. The feedstock is introduced into the autoclave in the presence of the deasphalting solvent according to the desired level of solvent volume. The temperature and pressure of the test are adjusted according to the type of solvent chosen and the quality of the desired DAO. The mixture is kept stirred under the same conditions for at least one hour and then allowed to settle for another hour. The upper phase DAO is removed by the quilting of the medium until the solvent appears. The lower pitch phase is then withdrawn by the bottom quill until the remaining DAO appears (mixture DAO / pitch, said intermediate phase). The determination of the densities of the DAO, the pitch and this intermediate phase makes it possible to calculate precisely the yields in DAO and pitch.

Visbreaking Tests The methodology consists in using an autoclave configured in visbreaking mode. Viscoreduction of the charge is carried out in the stirred autoclave and heated at two different temperatures.

The gases generated by the cracking are condensed and recovered at the main condenser cooled to -10 ° C and the secondary condenser cooled to -80 ° C. The remaining gases are counted and collected (manual piston) in the middle and end of the test. The liquid effluent is recovered and analyzed (stability, sediment, density and viscosity at 100 ° C). The stability measurement is measured by the stability limit, also called S-value according to ASTM D7157. When the S-value of the visbroken effluent is higher, it is considered to be more stable. 1st deasphalting The first deasphalting is carried out on the vacuum residue A, whose properties are summarized in Table 1. The solvent used is n-pentane under the following conditions: • Solvent content: 2.75 v / v. • Pressure: 40 bar • Temperature: 170 ° C. The characteristics of the DAO cut obtained after this first deasphalting with n-pentane are collated in Table 2.

Table 2: Properties of the DAO cut from the first n-pentane deasphalting of RSV A Density at 15 ° C 988 (kg / m3) Viscosity at 100 ° C (cSt) 44.63 Viscosity at 70 ° C (cSt) 184.7 S (wt.%) 4.31 Ni (ppm) 33 V (ppm) 86 CCR (wt.%) 7.59 Asphaltenes (wt.%) 0.6 Cut 370 ° C - (wt.%) 16.2 Cut 370-500 ° C (wt.%) 13.8 Cut 500 ° C + (wt.%) 70 Saturated + olefins 20.6 Aromatic 61.5 including Monoaromatics 13.2 Resins 17.9 2nd deasphalting The second deasphalting is carried out at n -propane, on the DAO obtained at the first deasphalting under the following conditions: • Solvent content: 6 v / v. • Pressure: 40 bars Temperature: 60 ° C. The characteristics of the DAO and pitch cuts obtained after this second deasphalting with n-propane are collated in Table 3.

Table 3: Properties of CAD cuts and pitch from 2nd deasphalting with n-propane Density at 950 15 ° C (kg / m3) Viscosity at 100 ° C (cSt) 10.54 S (% weight) 3.22 as Ni (ppm) 3 V (ppm) 4 cs CCR (% wt) 1,10 -cs Asphaltenes (wt.%) 0.6 Cut 350 ° C - N wt.) 34.3 Cut 350-500 ° C (% 37'8) weight) Ô Cut 500 ° C + (% 27.9 wt) Saturated + olefins 33.2 Aromatic 63.0 including Monoaromatics 21.9 Resins 3.5 Density at N 15 ° C (kg / m3) 1037 Asphaltenes (% weight) 2.0 Saturated + olefins 8.40 Aromatic 82.60 including Monoaromatics 7.20 Resins 27.00 The second deasphalting with n-propane makes it possible to concentrate the resins in the pitch. This cut is also very aromatic, and has a low proportion of saturated compounds. Viscoreduction Viscoreduction is carried out for each of the channels at two different cracking temperatures: 434 ° C and 436 ° C. The cracking temperature is defined as being the temperature found in the autoclave configured in vis-reduction mode. Table 4 below indicates the composition of the charge of the visbreaking process in the two routes envisaged. It can be seen that the load is lighter when C3 pitch from the second deasphalting of the residue under vacuum (track 2) is integrated, as shown by the CCR (ConRadson Carbon section) which goes from 19.81 to 18.84. This will result in a decrease in coke production.15 Table 4: Visor Reducer Load Properties by Selected Route Track 1 Track 2 I RSV B Load (% wt.) 100% 80% Brai C3 viscometer from 2nd - 20 % deasphalting of RSV A (wt.%) Density at 15 ° C (kg / m3) 1028 1031 Sulfur (wt.%) 4,1 4,5 CCR (wt.%) 19,8 18,8 Asphaltenes (wt.%) 5 , 6 4.9 Viscosity at 100 ° C (cSt) 1089.0 1056.0 Viscosity at 135 ° C (cSt) 178.0 176.6 Sediment (ppm) 0 38 Cut at 500 ° C + (wt%) 92, 30 86.33 Saturated + olefins 6.2 6.6 Aromatic 70.7 69.0 including Monoaromatics 4.7 5.2 Resins 17.5 19.4 Table 5 below summarizes the yields of the visbreaking process and the properties of the visbroken effluent according to the chosen route.

Table 5: Visor Reducer Yields and Viscorreduced Effluent Properties by Selected Route Route 1 Route 2 RSV B Load (% wt.) 100% 80% Braid C3 viscometer from the 2nd - 20% deasphalting of RSV A (wt.%) Cracking temperature (° C) I 434 436 434 436 Yields 1.01 0.81 0.86 0.92 Gases (wt.%) PI - 150 ° C (wt.%) 3.04 3.38 2.76 2, 150 - 350 ° C (wt.%) 11.62 12.77 19.06 17.82 350 - 500 ° C (wt.%) 18.45 18.18 20.15 19.10 500 ° C + (wt.%) ) 65.88 64.86 - 57.16 59.61 Conversion 500 ° C + 129.62 31.18 37.31 35.92 Visumreduced effluent 1.52 1.48 1.66 1.60 S-value (standard ASTM D7157), Sediment (ppm) 100 1112 230 2192 Density at 15 ° C (kg / m3) 1039.0 1036.4 1040.7 1049.7 Viscosity at 100 ° C (cSt) 315.30 214.9 182, The incorporation of the resin cut into the visbreaking charge makes it possible, at iso cracking temperature, to gain conversion. Thus at 434 ° C the conversion gain obtained is of the order of 26%. At 436 ° C, the conversion gain is of the order of 15%. In addition, the implementation of the invention leads to an improvement in the stability of the visbroken effluent. In fact, the stability limit (S-value) at iso-cracking temperature is higher for the visbroken effluent obtained by channel 2. The improvement in stability results in an increase in the stability limit of about 8 to 9% in both cases.

Claims (10)

Revendications1. Process for the conversion of petroleum feeds whose CLAIMS1. Process for the conversion of petroleum feeds whose boiling curve is such that less than 20% by weight of the feed is distilled at a temperature of 343 ° C under ambient conditions, and more than 40% by weight of the feed is distilled at a temperature above 500 ° C, comprising: - a first deasphalting with a heavy solvent comprising a content of saturated hydrocarbons having at least 5 carbon atoms greater than or equal to 95%, - a second deasphalting on the deasphalted oil from the first deasphalting, with a light solvent comprising a saturated hydrocarbon content having 3 or 4 carbon atoms greater than or equal to 95%, the deasphalted oil resulting from the second deasphalting is converted by catalytic cracking, the pitch resulting from the second deasphalting is converted by visbreaking. 2. Method according to claim 1 characterized in that the petroleum feedstock is selected from heavy crudes, atmospheric residues and / or residues under vacuum crude distillations. 3. Method according to one of claims 1 or 2, characterized in that the solvent of the first deasphalting is constituted by an n-paraffin having from 5 to 7 carbon atoms and / or the solvent of the second deasphalting is constituted by at least an n-paraffin having 3 or 4 carbon atoms 4. Method according to one of claims 1 to 3, characterized in that the solvent of the first deasphalting is n-pentane and the solvent of the second deasphalting is propane and / or n-butane 5. Method according to one of claims 1 to 4, characterized in that a vacuum distillate is sent to the catalytic cracking mixture with said deasphalted oil from the second deasphalting. 6. Process according to claim 5, characterized in that the deasphalted oil resulting from the second deasphalting represents up to 50%, preferably up to 30%, of the total charge of the catalytic cracking. 7. A method according to any one of claims 1 to 6, characterized in that a vacuum residue is sent to the visbreducer mixed with said pitch from the second deasphalting. 15 8. Process according to claim 7, characterized in that the pitch resulting from the second deasphalting represents up to 50%, preferably up to 30%, of the total charge of the visbreducer. 9. Process according to any one of claims 1 to 8, characterized in that the pitch resulting from the first deasphalting is used as a solid fuel. 10