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US2719106A - Champagnat - Google Patents

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US2719106A
US2719106A US27862752A US2719106A US 2719106 A US2719106 A US 2719106A US 27862752 A US27862752 A US 27862752A US 2719106 A US2719106 A US 2719106A
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urea
solution
emulsion
adduct
urea solution
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    • 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
    • C10G31/00—Refining of hydrocarbon oils, in the absence of hydrogen, by methods not otherwise provided for
    • C10G31/06—Refining of hydrocarbon oils, in the absence of hydrogen, by methods not otherwise provided for by heating, cooling, or pressure treatment

Definitions

  • This invention relates to an improved process for the refining of mineral oils. More particularly, the invention relates to a process for the extractive fractionation of petroleum oils, by means of urea.
  • urea forms crystalline solid adducts with straight chain and slightly branched chain hydrocarbons but does not form solid compounds with naphthenes, highly branched compounds or aromatics.
  • a method has been developed for refining petroleum fractions by resolution of the frac tions into chemical types by forming the above solid compounds, removing the remaining liquid phase (known as the urea adduction rafiinate), decomposing the solid compounds and recovering from the product the liberated hydrocarbons (known as the urea adduction extract).
  • the urea adduct may be formed, under the conditions of an emulsion, more rapidly than hitherto and with the formation of a solid phase in a form which is more readily separable from the liquid phase than has been the case hitherto.
  • the solvent according to the invention essentially contains three components as aforementioned, but it is not a matter of consequence if the ternary solvent contains minor amounts of other materials as, in fact, would 1 be inevitable when using commercial grade constituents. Clearly also it is not of consequence that there is used, instead of a monohydric alcohol or ketone, a mixture of compounds of these chemical types, since such a mixture would be serving the same function as either constituent alone without departing from the scope of the invention.
  • the urea adduct is formed as a suspension in a liquid phase comprising a solution of urea in the ternary solvent, the raffinate being present as an emulsion in the urea solution.
  • the density of the solution of urea in the ternary solvent is adjusted to be greater than that of the hydrocarbons and less than that of the adducts.
  • said product is then converted to a two layer system consisting of an upper raflinate layer and a lower layer comprising a. suspension of the solid urea adduct in the urea solution.
  • the layers of said system are separated and the lower layer subsequently heated to decompose the urea adduct, whereby a two phase system is formed, thereafter separating a phase, consisting essentially of the adduction extract, from a phase consisting of a solution of urea.
  • the solution of urea recovered after urea adduction comprises the same components as that employed for the urea adduction, the components being present, however, in different proportions.
  • part of the recovered urea solution is distilled to take overhead a fraction comprising an aqueous alcohol or ketone, which is employed again as emulsion breaking agent, and to recover as bottoms a urea solution which is added to the remainder of the recovered urea solution.
  • the distillation bottoms may be returned to the system after separation of the adduction raffinate but prior to the adduct deposition stage.
  • the urea solution so obtained is of the composition of the urea solution employed for adduct formation and is thus suitable, after addition of make-up materials, for recycle to the urea adduct forming stage.
  • the ternary solvent should comprise 10-90% by weight of the aqueous monohydric alcohol or ketone, and preferably contains 50-80% by weight of the aqueous monohydric alcohol or ketone, the balance being made up of the third component. If desired, of course, a mixture of monohydric alcohols and/ or ketones may be employed in the ternary solvent. It is preferred that 230% of water be employed, based on the combined weight of water, monohydric alcohol and ketone in the ternary solvent. Suitable alcohols include methanol, n-propanol, isopropanol and 2-methy1 propanol.
  • Suitable ketones The preferred 60 parts by weight of methanol parts by weight of water 25 parts by weight of ethylene glycol It has been established that starting with a saturated solution of urea in a ternary solvent according to the invention and rapidly cooling this solution by about 15 C. with vigorous agitation, a super-saturated solution is formed from which are obtained urea crystals which could be termed nascent and which are of very small dimensions.
  • the urea adducts are formed while the urea solution is in a super-saturated state.
  • this may be achieved by cooling a saturated solution of urea in a ternary solvent so as to obtain nascent urea crystals, then bringing into contact these two phases and forming an emulsion, preferably in a colloid mill, from the supersaturated solution of urea and the hydrocarbon fraction. It is also possible to bring into contact the hydrocarbon fraction and the saturated urea solution and then to cause the nascent crystallization of urea by cooling.
  • This may be effected in practice by delivering the urea solution to the contacting zone at a temperature above that of the mineral oil, while containing an excess of urea over that necessary to saturate the solution at the temperature of adduct formation.
  • This method allows the crystals to react from the time of their formation with the hydrocarbon fraction. Accordingly, there is attained an improved heat economy. Since the cooling of the urea solution is effected by the fresh charge of cool hydrocarbons, said hydrocarbons become heated when in contact with said urea.
  • adduct crystals are obtained which are very fine and remain in suspension for long periods, without agglomerating, thus facilitating the separation of the unreacted hydrocarbons.
  • fine crystals which do not agglomerate have less tendency to absorb the rafiinate.
  • the density of the solution of urea in the ternary solvent is readily adjusted to be greater than that of the hydrocarbons and less than that of the adducts which can consequently pass into the urea solution phase upon the decantation of the rafiinate.
  • a third advantage of the urea solutions is that their wetting power with respect to the adduct crystals is higher than that of the hydrocarbons with respect to these crystals. It is for that reason that the adduct crystals do not remain in suspension in thedecanted raffinate and do not absorb it to any appreciable extent.
  • the process of the present invention using the urea solutions hereinbefore described, may thus be operated without the use of cumbersome technical processes such as filtration, drying, or distillation of large quantities of products, and may rely to the fullest extent on the use of decantation as the actual means of separation.
  • the process of the present invention is particularly suitable for the separation of hydrocarbons contained in petroleum products, such as gasoline, kerosine, or gas oil, into a raffinate practically free from normal aliphatic hydrocarbons and an extract essentially consisting of normal aliphatic hydrocarbons.
  • FIG. 1 is a diagrammatic representative of the essential stages of the process
  • Figure 2 is a flow diagram of an apparatus suitable for use in the continuous treatment of petroleum distillation fractions, for example a petroleum naphtha.
  • a saturated urea solution in the ternary solvent is cooled at stage 1 and passed with the mineral oil feed, introduced by line 2, to stage 3 where an emulsion containing the urea adduct is formed.
  • Aqueous methanol introduced by line 4 is mixed with the product to form a two layer system in stage 7.
  • the upper raffinate layer is removed by line 8, the lower layer being heated in stage 9 to decompose the adduct.
  • stage 10 a two layer system is formed, the extract layer being removed by line 11.
  • To the unsaturated urea solution removed from stage 10 is added, by line 12, a distillation residue, having a high urea content, whereby a saturated urea solution is reformed.
  • stage 7 The necessary distillation feed for providing the aqueous methanol used in stage 7 is withdrawn from the main recycle fiow or urea solution by line 5 and passed to the distillation stage 6 from which overhead aqueous methanol is withdrawn by line 4 and bottoms by line 12. The remaining saturated urea solution is recycled to stage 1.
  • a urea solution, in the ternary solvent, at near saturation point is maintained at slightly elevated temperature, for example 40 C. in intermediate storage tank 14 by means of steam coils 15.
  • a pump 16 draws the urea solution and delivers it to a cooler 18 wherein said solution is cooled to a temperature comprised between 20 and 30 C.
  • Mineral oil preferably dried in a drier not represented on the diagram, is drawn by pump 17 into homogenizer 19. This also receives the cooled urea solution coming from cooler 18. The streams of urea solution and of mineral oil are sent in a constant ratio into the homogenizer 19 which is served by motor 20.
  • a finely dispersed emulsion is formed due to the presence of crystals of nascent urea.
  • the emulsion is cooled (for example to 15 C.) in a cooler 21
  • the reaction between the emulsified products takes place in reactor 22 cooled by a water coil 23 which serves to keep the temperature constant. (The temperature would otherwise tend to rise due to the exothermic reaction by which the adduct is formed.)
  • the emulsion is broken in vessel 24 by the addition of the required quantity of aqueous methanol supplied by pump 36 (this aqueous methanol is obtained by distilling part of the urea solution contained in 14 as will be set forth in the course of the description).
  • decanting vessel 25 In decanting vessel 25 the separation of the two layers resulting from breaking the emulsion in vessel 24 takes place. Raffinate which forms the top layer is removed by pipe 26 and transferred to a storage vessel.
  • the urea solution which holds the crystals of the adduct in suspension forms ,the lower layer in decanting vessel 25. It is removed by means of pump 27.
  • the urea solution is then heated to 40 C. in the steam heated vessel 28.
  • the adduct is decomposed into its constituents, which separate into two layers in the decanting vessel 29.
  • the upper layer comprises extract and is conveyed to a storage vessel by pipe while the lower layer comprising a urea solution at C. is sent to the intermediate storage vessel 14 by pipe 31.
  • the auxiliary circuit for distilling a fraction of the initial urea solution held in the tank 14, comprises a pump 32 conveying this urea solution into heater 33 which is preferably at a temperature of about 115 C.
  • the separation of the aqueous methanol vapors takes place in evaporator 34 which may be without a reflux condenser.
  • the aqueous methanol vapors condense in condenser 35.
  • the liquid aqueous methanol is sent by pump 36 into the mixer 24 where it is used to break the emulsion.
  • the warm residue from distillation vessel 34 is conveyed by pump 37 into pipe 31 in which it serves to reconstitute in amount and composition the initial urea solution prior to its being returned to reservoir 14.
  • the hot residue from 34 can be delivered wholly or partially by valve 38 (valve 40 being wholly or partially closed) into pipe 39 in order to reheat the urea solution containing the suspended adduct.
  • the residue is employed to heat the urea solution prior to its being passed on to heater 28.
  • the industrial plant which has been described with reference to Figure 2 is very suitable for the treatment of reforming distillates according to the manner of operation described in Example 1 hereinafter.
  • the octane number may be raised by four units by refining with urea according to the invention.
  • This increase in octane number is due to the fact that in the reforming of naphtha, the normal aliphatic hydrocarbons are left unchanged or are produced and it is the removal of these hydrocarbons by urea solution according to the invention which makes it possible to raise the octane number.
  • the normal aliphatic hydrocarbons which have been separated as extract according to the invention are available for cracking and it is well known from the cracking of hydrocarbons that they are an excellent starting material giving, by cracking, gases with a high content of unsaturated hydrocarbons. These are in increasing demand for the manufacture of chemicals of great economic importance.
  • Diagram 4 which does not have this drawback there is treated directly in the extractive crystallization unit 52 of the type represented in Figure 2, a naphtha 57, for example of boiling range l60260 C. as illustrated in Example 3, hereinafter, to obtain an extract 55 of normal aliphatics, distilling at l60260 C., which is a highly valuable material for chemical synthesis or fora special cracking unit (not shown) for the purpose of producing liquid and gaseous normal aliphatic hydrocarbons, particularly unsaturated ones, which are of great interest for the chemical industry.
  • the rafiinate 54 which is free of normal aliphatic hydrocarbons is fed into the reforming unit 51 which is then completely used to produce gas 58 and a gasoline 53 of a high octane number.
  • Example 1 A ternary solution was prepared consisting of:
  • a continuous phase consisting of a saturated urea solution which held droplets of rafiinate (thermal reforming spirit deprived of normal aliphatic hydrocarbons) in suspension.
  • the adduct crystals (urea-normal aliphatic hydrocarbons) were very abundant when the reaction was complete and enclosed droplets of rafiinate.
  • the excess urea crystals form a kind of lattice which makes the emulsion thixotropic and prevents the droplets of raflinate from collecting together and from forming a continuous phase which is capable of being separated by decantation.
  • the lower layer was heated to 40 C. (stage 9). This resulted in the decompositon of the complex since there was no longer a supersaturated solution of urea, the complex in consequence being unstable.
  • the product was settled to form two layers (stage 10) viz. an upper layer consisting of the extract phase 11 and containing the straight chain hydrocarbons decanted (line 11) and a lower layer consisting. of an unsaturated solution of urea in the ternary solvent.
  • the solution was unsaturated because on the one hand the temperature exceeded 38 C., and, on the other hand, the aqueous methanol has been added (by line 4).
  • urea solution was reconstituted in composition and volume by the addition (line 12) of the residue from the distillation of stage 6, consisting of 17 parts by weight of a mixture of ethylene glycol and urea still containing a small amount of methanol and water.
  • the octane number can be raised by four units by the motor method as well as by the Research Method, retaining the tetraethyl lead susceptibility and. the higher rating by the Research Method compared with results ob-.
  • Example 2 This example illustrates the application of the process of the invention to the treatment of a straight run motor spirit.
  • the splitting of the emulsion was carried out by the method used in Example 1 but in the present example there was added 20 parts of 90% aqueous methanol obtained by distillation of a further 54 parts of theinitial 8 urea solution. The 34 parts of hot residue were kept for further use.
  • the emulsion having been broken, the raffinate was separated by decantation.
  • the urea solution with the addition of aqueous methanol and containing the adduct, was heated to 40 C.
  • the extract layer was decanted and recovered and the urea solution reconstituted by the addition of 34 parts of the hot residue from the preliminary distillation.
  • This example illustrates the application of the process of the invention to the treatment of a straight run naphtha.
  • Example 1 330 parts of a urea solution saturated at 38 in the same solvent as that used in Example 1 were cooled and the solution stirred vigorously at 25 with 100 parts of naphtha having a distillation range of 160260 C. and from the distillation products of a Middle East. crude. The mixture was led into a homogenizer. The reaction took less than 10 minutes according to the qualitative test for the determination of straight chain hydrocarbons mentioned in Example 1'.
  • the emulsion was broken by the addition of 10 parts of by weight aqueous methanol obtained by the distillation of a further 27 parts of the initial urea solution.
  • the distillation residue was kept hot for further use in the process.
  • the raffinate was separated by decantation.
  • the urea together with the aqueous methanol carrying the adduct in suspension, was heated to 48 C. whereby the adduct was decomposed, setting freethe extract which was separated by decantation.
  • soluble oxygen-containing organic compound selected from the group consisting of ketones, mono-hydric alcohols, and mixtures of the foregoing
  • an alcoholic organic compound selected from the group consisting of poly-hydric alcohols and mono-amino-alcohols
  • a process for the extractive fractionation of mineral oils which comprises treating a mineral oil with a solution of urea in a ternary solvent consisting essentially of, in
  • a water-soluble oxygen-containing organic compound selected from the group consisting of ketones, monohydric alcohols, and mixtures of the foregoing, and an alcoholic organic compound selected from the group consisting of polyhydric alcohols and mono-amino-alcohols, forming an emulsion of the oil-in-water type, maintaining said emulsion under conditions such that a solid urea adduct is formed with components of said mineral oil, breaking said emulsion to form a two-layer system consisting of an upper layer comprising the urea adduction rafiinate and a lower layer comprising a suspension of said solid urea adduct in said urea solution, separating said ralfinate from said lower layer, separating said urea adduct from said urea solution, decomposing said urea adduct and recovering the liberated components of said mineral oil.
  • a water-soluble oxygen-containing organic compound selected from the group consisting of ketones, monohydric alcohols, and mixtures
  • a process for the extractive fractionation of mineral oils which comprises treating a mineral oil with a supersaturated solution of urea in a ternary solvent consisting essentially of, in admixture about 2% to about 30% water, a water-soluble oxygen-containing organic compound, selected from the group consisting of ketones, monohydric alcohols, and mixtures of the foregoing, and an alcohol organic compound selected from the group consisting of polyhydric alcohols and monoamino alcohols, forming an emulsion of the oil-in-water type, maintaining said emulsion under conditions such that a solid urea adduct is formed with components of said mineral oil, adding thereto an emulsion-breaking agent comprising an aqueous solution of a water-soluble monohydric alcohol to form a two-layer system consisting of an upper layer comprising the urea adduction rafiinate and a lower layer comprising a suspension of said solid urea adduct in said urea solution, separating said ra
  • said ternary solvent consists of ethylene glycol, water and a watersoluble oxygen-containing organic compound selected from the group consisting of ketones, monohydric alcohols and mixtures of the foregoing.
  • a process for the extractive fractionation of petroleum naphtha which comprises treating a petroleum naphtha with a supersaturated solution of urea in a ternary solvent consisting essentially of, in admixture, about 2% to about 30% water, a water-soluble oxygen-containing organic compound selected from the group consisting of ketones, monohydric alcohols, and mixtures of the foregoing, and an alcoholic organic compound selected from the group consisting of mixtures of polyhydric alcohols and mono-amino-alcohols, forming an emulsion of the oil-in-water type, maintaining said emulsion under conditions such that a solid urea adduct is formed with components of said petroleum naphtha, adding thereto an emulsion-breaking agent comprising an aqueous solution of a Water-soluble mono-hydric alcohol to form a two-layer system consisting of an upper layer comprising the urea adduction rafiinate and a lower layer comprising a suspension of said solid ure
  • a process for the production of straight chain hydrocarbons and high octane gasoline which comprises treating a petroleum naphtha by the process claimed in claim 8 with recovery of an extract comprising straight chain hydrocarbons and a raflinate comprising highly branched chain hydrocarbons and aromatics, wherein said rafiinate is thereafter subjected to thermal reforming with recovery of a high octane gasoline.
  • a process as specified in claim 5 in which the oxygen containing organic compound is a mixture of a monohydric alcohol and a ketone, and in which the combined weight of the water, monohydric alcohol and ketone in the ternary solvent employed in said urea solution for the formation of said adduct constitutes 50-80% by weight of said ternary solvent.

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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)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
US27862752 1951-04-04 1952-03-26 Champagnat Expired - Lifetime US2719106A (en)

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US (1) US2719106A (xx)
BE (1) BE510286A (xx)
DE (1) DE952122C (xx)
FR (1) FR1035082A (xx)
GB (1) GB704439A (xx)
NL (1) NL77412C (xx)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2855390A (en) * 1952-05-24 1958-10-07 champagnat ctau
US3269935A (en) * 1966-08-30 Emulsion breaking in an adduct separation process

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1104947A (xx) * 1954-05-19 1955-11-25
NO309795B1 (no) * 1998-07-01 2001-04-02 Norsk Hydro As FremgangsmOte for O stabilisere oljer samt anvendelse derav, fremgangsmOte for O stabilisere pigmenter, og fremgangsmOte for fremstilling av for

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1941886A (en) * 1929-10-17 1934-01-02 Kontol Company Emulsion decomposing body
US1943427A (en) * 1928-11-01 1934-01-16 Ig Farbenindustrie Ag Production of organic acids
FR959374A (xx) * 1947-01-07 1950-03-28
US2518677A (en) * 1950-08-15 Separation of hydrocarbons using
US2557257A (en) * 1949-01-29 1951-06-19 Extractive fractionation process
US2569986A (en) * 1951-10-02 Extractive crystallization process
US2642422A (en) * 1953-06-16 Gorin

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE869070C (de) * 1940-03-19 1953-03-02 Basf Ag Verfahren zur Zerlegung von Gemischen organischer Verbindungen

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2518677A (en) * 1950-08-15 Separation of hydrocarbons using
US2569986A (en) * 1951-10-02 Extractive crystallization process
US2642422A (en) * 1953-06-16 Gorin
US1943427A (en) * 1928-11-01 1934-01-16 Ig Farbenindustrie Ag Production of organic acids
US1941886A (en) * 1929-10-17 1934-01-02 Kontol Company Emulsion decomposing body
FR959374A (xx) * 1947-01-07 1950-03-28
US2557257A (en) * 1949-01-29 1951-06-19 Extractive fractionation process

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3269935A (en) * 1966-08-30 Emulsion breaking in an adduct separation process
US2855390A (en) * 1952-05-24 1958-10-07 champagnat ctau

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DE952122C (de) 1956-11-08
BE510286A (xx) 1952-04-15
GB704439A (en) 1954-02-24
NL77412C (xx) 1955-03-15
FR1035082A (xx) 1953-08-14

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