Classifications

• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
  • C10G67/00—Treatment of hydrocarbon oils by at least one hydrotreatment process and at least one process for refining in the absence of hydrogen only
  • C10G67/02—Treatment of hydrocarbon oils by at least one hydrotreatment process and at least one process for refining in the absence of hydrogen only plural serial stages only
  • C10G67/04—Treatment of hydrocarbon oils by at least one hydrotreatment process and at least one process for refining in the absence of hydrogen only plural serial stages only including solvent extraction as the refining step in the absence of hydrogen
  • C10G67/0454—Solvent desasphalting

Definitions

• PROCESS FOR THE CONVERSION OF HEAVY CHARGES SUCH AS HEAVY CRUDE OILS AND DISTILLATION RESIDUES.
• the present invention relates to a process for the conversion of heavy charges, among which heavy crude oils, tars from oil sands and distillation residues, by the use of three process units : hydroconversion of the charge using catalysts in dispersed phase, distillation and deasphalting, suitably connected and fed with mixed streams consist- ing of fresh charge and conversion products.
• the conversion of heavy crude oils, tars from oil sands and oil residues in liquid products can be substantially effected in two ways: one exclusively thermal, the other by means of hydrogenating treatment .
• Current studies are mainly directed towards hydrogenating treatment, as thermal processes have problems linked to the disposal of the by-products, in particular coke (even obtained in quantities higher than 30% by weight with respect to the charge) and to the poor quality of the con- version products.
• Hydrogenating processes consist in treating the charge in the presence of hydrogen and suitable catalysts.
• silica/alumina or equivalent material
• Slurry technologies are characterized by the presence of particles of catalyst having very small average dimen- sions and effectively dispersed in the medium: for this reason hydrogenation processes are easier and more immediate in all points of the reactor.
• the formation of coke is considerably reduced and the upgrading of the charge is high.
• the catalyst can be charged as powder with sufficiently reduced dimensions (U.S. 4,303,634) or as oil- soluble precursor (U.S. 5,288,681).
• the active form of the catalyst generally the metal sul- fide
• the metallic constituents of the dispersed catalysts are generally one or more transition metals (preferably Mo, , Ni, Co or Ru) .
• Molybdenum and tungsten have much more satisfactory performances than nickel, cobalt or ruthenium and even more than vanadium and iron (N. Panariti et al . , Appl. Catal. A: Jan. 2000, 204, 203) .
• the catalyst can be used at a low concentration (a few hundreds of ppm) in a "once-through" configuration, but in this case the upgrading of the reaction products is gener- ally insufficient (N. Panariti et al., Appl. Catal. A: Jan. 2000, 204, 203 and 215) .
• extremely active catalysts for example molybdenum
• concentrations of catalyst for example molybdenum
• concentrations of catalyst thousands of ppm of metal
• the catalyst leaving the reactor can be recovered by separation from the product obtained from hydro-treatment (preferably from the bottom of the distillation column, downstream of the reactor) using conventional methods such as, for example, decanting, centrifugation or filtration (U.S. 3,240,718; U.S. 4,762,812). Part of the catalyst can be recycled to the hydrogenation process without further treatment.
• the catalyst recovered using known hydro-treatment processes normally has a reduced activity with respect to fresh catalyst and a suitable regeneration step must therefore be effected to restore the catalytic activity and recycle at least part of the catalyst to the hydro-treatment reactor.
• Hydrocarbons which can be precipitated by a crude oil or oil residue by treatment with n-heptane under standard conditions established by regulation IP-143, are conventionally defined as asphaltenes .
• phase separation phenomenon can be explained by the fact that as the conversion reactions proceed, the asphaltene phase becomes more and more aromatic due to dealkylation and condensation reactions.
• the stability loss control of a heavy charge during a thermal and/or catalytic conversion process is therefore fundamental for obtaining the maximum conversion degree without running into problems relating to the formation of coke and fouling.
• This process comprises the following steps:
• hydroconversion with catalysts in slurry phase (HT) , distillation or flash (D) , deasphalting (SDA) is characterized in that the three units operate on mixed streams consisting of fresh charge and recycled streams, using the following steps:
• the heavy charges treated can be of different kinds: they can be selected from heavy crude oils, distillation residues, heavy oils coming from catalytic treatment, for example heavy cycle oils from catalytic cracking treatment, thermal tars (co ing for example from visbreaking or simi- lar thermal processes) , tars from oil sands, various kinds of coals and any other high-boiling charge of a hydrocarbon origin generally known in the art as "black oils”.
• the possible remaining part of the distillation residue (tar) or liquid leaving the flash unit, not recycled to the deasphalting zone, can be either totally or partially recycled, to the hydro-treatment section.
• the catalysts can be selected from those obtained from easily decomposable oil-soluble precursors (metallic naph- thenates, metallic derivatives of phosphonic acids, metal- carbonyls, etc.) or from preformed compounds based on one or more transition metals such as Ni, Co, Ru, W and Mo: the latter is preferred due to its high catalytic activity.
• the concentration of catalyst defined on the basis of the concentration of metal or metals present in the hydro- conversion reactor, ranges from 350 to 10000 ppm, preferably from 1000 to 8000 ppm, more preferably from 1500 to 5000 ppm.
• the hydro-treatment step is preferably carried out at a temperature ranging from 370 to 480°C, preferably from 380 to 440°C, and at a pressure ranging from 3 to 30 MPa, preferably from 10 to 20 MPa.
• the hydrogen is fed to the reactor, which can operate either under down-flow or, preferably up-flow conditions.
• the gas can be fed to different sections of the reactor.
• the distillation step is preferably carried out at reduced pressure, at a pressure ranging from 0.001 to 0.5 MPa, preferably from 0.05 to 0.3 MPa.
• the deasphalting step effected by an extraction with a solvent, which may or may not be hydrocarbon, (for example with paraffins having rom 3 to 6 carbon atoms) , is generally carried out at temperatures ranging from 40 to 200°C and at a pressure ranging from 0.1 to 7 MPa. It can also consist of one or more sections operating with the same solvent or with different solvents; the solvent can be recovered under supercritical conditions thus allowing fur- ther fractionation between asphalt and resins.
• a solvent which may or may not be hydrocarbon, (for example with paraffins having rom 3 to 6 carbon atoms)
• the stream consisting of deasphalted oil (DAO) can be used as such as synthetic crude oil (syncrude) , optionally mixed with the distillates, or it can be used as charge for fluid bed Catalytic Cracking treatment or Hydrocracking.
• DAO deasphalted oil
• synthetic crude oil syncrude
• hydrocracking Hydrocracking
• the ratio between the heavy residue to be sent to the hydro-treatment section (fresh charge) and that to be sent for deasphalting can vary from 0 to 100, preferably from 0.1 to 10, more preferably from 1 to 5;
• the stability of the streams in question and quality of the product to be obtained (also in relation to the particular downstream treatment)
• the fractions of fresh charge to be fed to the deasphalting and hydro-treatment sections can be modulated in the best possible way.
• the process, object of the present invention can be further improved, as far as the compatibility of the streams to be mixed is concerned, by controlling that the recycling between the streams containing asphaltenes, or fresh charge, tar and asphalt, has such a ratio that:
• Vi is the molar volume of the maltene component (i.e. non- asphaltene) of the mixture (cm 3 /mole) ;
• ⁇ m i x is the solubility parameter of the maltene component of the mixture (cal/cm 3 ) 12 ;
• T temperature expressed in Kelvin degrees.
• the asphaltenes used as reference for determining the properties indicated above are the insoluble n-heptane fraction (C 7 asphaltenes) .
• the values indicated in the formula are calculated as follows :
• V m i x molar average of the molar volumes of the maltene components
• ⁇ rn i volumetric average of the solubility parameters of the maltene components
• k constant whose value ranges from 0.2 to 0.5.
• the application described is particularly suitable when the heavy fractions of complex hydrocarbon mixtures produced by the process must be used as charge for cata- lytic cracking plants, both Hydrocracking (HC) and fluid bed Catalytic Cracking (FCC) .
• HC Hydrocracking
• FCC fluid bed Catalytic Cracking
• HT catalytic hydrogenation unit
• SDA extractive process
• the investment cost of the whole complex can also be minimized as, with respect to the scheme de- scribed in patent application IT-95A001095, for the same charge unit treated, the dimensions of the deasphalting section are increased whereas those of the hydro-treatment section (and downstream distillation column) are reduced; as the deasphalting unit involves lower investment costs than the hydro-treatment unit, there is a consequent saving on the investment cost of the whole complex.
• the heavy charge (1) or at least a part thereof (la) , is sent to the deasphalting unit (SDA) , an operation which is effected by means of extraction with solvent.
• SDA deasphalting unit
• deasphalting unit SDA
• DAO deasphalted oil
• asphalts and resins (3)
• the latter can be further separated into the two groups of compounds of which it is formed, and the fraction of resins (4) can be divided between DAO and asphalt.
• the stream consisting of asphalt and resins (or a fraction of these) is mixed with fresh make-up catalyst (5) necessary for reintegrating that used up with the flushing stream (14) , with the part of heavy charge (lb) not fed to the deasphalting section and optionally with the stream (15) (which will be described further on in the text) coming from the bottom of the distillation column (D) to form a stream (6) which is fed to the hydro-treatment reactor (HT) into which hydrogen (or a mixture of hydrogen and H 2 S) (7) , is charged.
• HT hydro-treatment reactor
• a stream (8) containing the hydrogenation product and catalyst in dispersed phase leaves the reactor and is fractionated in a distillation column (D) from which the lighter fractions (9) and distillable products (10) , (11) and (12) are separated from the distillation residue containing the dispersed catalyst and coke.
• This stream called tar, (13) , is completely or for the most part, except for a flushing (14) , recycled to the deasphalting reactor (SDA) .
• a part of this (15) can be optionally sent to the hydro-treatment unit (HT) .
• Reactor 3000 cc, steel, suitably shaped and equipped with magnetic stirring
• Atmospheric gas oil (AGO 170-350°C) :17%
• the asphaltene stream recovered at the end of the test contains all the catalyst initially fed, sulfides of the metals Ni and V produced during the 10 recycles from the hydro-treatment and a quantity of coke in the order of about 1% by weight with respect to the total quantity of Ural residue fed. In the example indicated, there was no need to effect any flushing of the recycled stream.
• Table 2 characteristics of test reaction products according to Example 1.
• Atmospheric gas oil (AGO 170-350°C) :24%
• Table 3 provides the characterization of the product obtained.
• Table 3 characteristics of test reaction products according to Example 2.
• the parameter k values were calculated in all the possible mixture situations of the two streams: from 0% of the first component and 100% of the second component up to the reverse situation, i.e. 100% of the first component and 0% of the second component.
• the temperature to which reference was made for determining the properties is 140°C.

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• Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
• Working-Up Tar And Pitch (AREA)

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Cited By (6)

Citations (7)

• 2002
  • 2002-12-30 AU AU2002358182A patent/AU2002358182B8/en not_active Ceased
  • 2002-12-30 WO PCT/EP2002/014847 patent/WO2004058922A1/en active Application Filing
  • 2002-12-30 EP EP02791874.7A patent/EP1578891B1/en not_active Expired - Lifetime
  • 2002-12-30 JP JP2004562520A patent/JP4498929B2/ja not_active Expired - Fee Related
  • 2002-12-30 ES ES02791874.7T patent/ES2679629T3/es not_active Expired - Lifetime
• 2005
  • 2005-06-16 NO NO20052951A patent/NO20052951L/no not_active Application Discontinuation
  • 2005-06-20 EC EC2005005872A patent/ECSP055872A/es unknown

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