US3136711A - Process for reducing the pour points of crude oils - Google Patents

Process for reducing the pour points of crude oils Download PDF

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Publication number
US3136711A
US3136711A US98668A US9866861A US3136711A US 3136711 A US3136711 A US 3136711A US 98668 A US98668 A US 98668A US 9866861 A US9866861 A US 9866861A US 3136711 A US3136711 A US 3136711A
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United States
Prior art keywords
crude
wax
pour point
temperature
pour
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US98668A
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English (en)
Inventor
Marvin B Glaser
Lichtenstein Ira
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ExxonMobil Technology and Engineering Co
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Exxon Research and Engineering Co
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Application filed by Exxon Research and Engineering Co filed Critical Exxon Research and Engineering Co
Priority to US98668A priority Critical patent/US3136711A/en
Priority to GB8950/62A priority patent/GB979772A/en
Priority to DEE22599A priority patent/DE1216468B/de
Priority to FR962507A priority patent/FR1392602A/fr
Priority to NL6401913A priority patent/NL6401913A/xx
Priority to BE644537D priority patent/BE644537A/xx
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Publication of US3136711A publication Critical patent/US3136711A/en
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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
    • 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
    • C10G73/00—Recovery or refining of mineral waxes, e.g. montan wax
    • C10G73/02—Recovery of petroleum waxes from hydrocarbon oils; Dewaxing of hydrocarbon oils
    • 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
    • C10G73/00—Recovery or refining of mineral waxes, e.g. montan wax
    • C10G73/02—Recovery of petroleum waxes from hydrocarbon oils; Dewaxing of hydrocarbon oils
    • C10G73/06—Recovery of petroleum waxes from hydrocarbon oils; Dewaxing of hydrocarbon oils with the use of solvents

Definitions

  • IA A I I I I Q 60- I2 I; vIs. TO I-IIaII T0 GENTRIFUGE 2 8 3 a i I; 0 40-- 4 H z 2 III 50 l l l l 0 I0 20 so 40 so so 10 AVE.
  • This invention relates to a process for improving the pour point of waxy crude oils by selective removal of the waxes causing high pour points. Specifically, this process relates to a method of improving the pour point of a residual fuel oil by heating the entire crude, followed by cooling the crude to agglomerate and precipitate wax, centrifuging to remove precipitated wax, and fractionating the crude to obtain a residual fuel oil of low pour point. Thermal pretreatment of the entire waxy crude to an elevated temperature, followed by controlled cooling below its pour point and subsequent centrifugation selectively removes from the crude those waxes which cause high pour point in the residual fuel oil component of the crude.
  • a crude oil containing a large concentration of wax is preheated to a temperature sufliciently high to melt the highest melting wax and to disperse the asphaltenes and resins present.
  • heated crude is subsequently cooled at a controlled rate to a temperature near its pour point in order to precipitate the wax, which causes the high pour point, in the form of agglomerates which can be easily separated by centrifuging.
  • a wax-rich fraction is removed from the The I 3,136,7ll Patented June 9, 1964 crude oil.
  • the separated oil is fractionally distilled to obtain the various desired fractions.
  • a residual fuel cut boiling from 650 to 750+ is withdrawn.
  • a waxy crude having an original pour point of about 35 to 55 F. can in this manner have its pour point reduced 15 to 25 F.
  • the residual fuel component cut from the preheated crude has its pour point reduced l5-25 F.
  • the crude may be centrifuged at relatively high temperatures of 35 to 55F.
  • the centrifuge temperature is generally within about 10 F. below the upper pour point.
  • a further disadvantage of thermal cracking is that the hot filtration sediment problem which usually limits the amount of pour reduction with thermal cracking is nonexistent when centrifuging for pour reduction.
  • FIGURE 1 is a graph showing the effect of centrifugation temperature on the resulting pour point of a waxy crude, as well as the percentage of dense phase which is separated.
  • the crude used was whole Zelten crude which had a pour of 55 F. and which was heated to 200 F. and cooled to the indicated centrifugation temperature.
  • FIGURE 2 is a graphic presentation showing the synergistic effect on pour point of the asphaltenes and resins.
  • FIGURE 3 is a schematic diagram of the process used in accordance with applicants invention to obtain a resid. fuel fraction of low pour point.
  • Our process is advantageously used in reducing the high pour point of waxy crudes which contain from 3 to 12 wt. percent Wax, based on crude, and which contain in the residual fuel fraction from 7 to 25 wt. percent wax, based on the resid. fraction.
  • the high waxy crudes which are normally treated are the Middle East and North African crudes; for example, Zelten, Kuwait, and Aramco.
  • the wax present in the crude can be put in optimum condition to be precipitated and centrifuged.
  • the crude is heated to a temperature between F. to 220 F. and then cooled to the centrifuge temperature.
  • the temperature to which the crude is heated should be sufiiciently high to melt all the wax present and to disperse the asphaltenes and resins.
  • the crude should be heated to a temperature of 180 F. to 210 F. Specifically, temperatures of to 200 F. are used.
  • the exact temperature of pretreatment will depend upon the wax and asphaltene content of any particular crude.
  • the temperature of centrifugation is critical and is close to the standard ASTM upper pour point of the oil to be centrifuged.
  • the centrifuge temperature should be such that the maximum amount of waxes causing the high pour point will precipitate, but high enough that the viscosity of the oil centrifuged is not so lowered that the material is too viscous to separate the precipitated wax from the oil treated.
  • the waxy crudes are centrifuged at temperatures between 35 and 55 F. Specifically, temperatures between 40 and 50 F. are preferred. However, the optimum centrifugation temperature will vary from crude to crude, depending on the relative amount of wax and asphaltenes present.
  • the pressure is not critical and the process is normally carried out at atmospheric pressure. Obviously, when heating to 200 or more, some light ends in the crude will boil out. These can be refluxed, condensed and returned to the crude, or cooled and returned to a specific fraction. If it is desired to prevent escape of these light ends, the heating to 200 can be carried out under pressure.
  • the rate at which the heated crude is cooled is critical.
  • the crude may be shock cooled to just above its cloud point; however, cooling from this point to the temperature of centrifugation must be carried out at a controlled rate of about 0.5 to 2 per minute. If the crude is cooled too rapidly, the wax precipitates in fine crystals and does not have the opportunity to form agglomerates with the dispersed asphaltenes.
  • the centrifugal force applied to the wax agglomerates that form is critical to the extent that if too low a force is used, the wax agglomerates do not settle out and no change in pour point results. Generally, a centrifuge operating between 6,000 and 13,000 gs is used.
  • the present commercial centrifuges that are available operate in the range of 7,000 to 10,000 gs and these are the units that we prefer to use. Utilizing equip- I ment of this type, high throughout rates of crude may be attained. Residence times as low as a few seconds up to 5 minutes or more have been used. Preferably, residence times of about 2 seconds to about 1 minute are used.
  • the particle size of the asphaltene-wax agglomerates that are separated by the centrifuge generally range in the size of 30 to about 500 microns.
  • a centrifuge operating at about 7600 gs obtains a 5 to 6% separation of waxy material, based on entire weight of crude, at a flow rate of 2000 b./d. This relates to a residence time of about 10 seconds.
  • Conventional apparatus may be used to provide continuous heating of the waxy crude to be treated to a temperature up to 220 F. and also provide controlled cooling of the oil to the centrifuge temperature.
  • the residual oil fraction separated after centrifugation may be recycled through appropriate heat exchange equipment to the pretreatment heating zone to assist in raising the temperature of the waxy crude in the pretreatment step.
  • asphaltenes are slightly more potent inhibitors and probably reduce pour by means of a powerful surfactant effect.
  • Aromatic resins act either as very weak surfactants or as diluents.
  • the asphaltenic inhibitors In order to be effectively dispersed, the asphaltenic inhibitors must be liberated from previously formed wax-asphaltene agglomerates, and this occurs when the fuel is heated slightly above the temperature sufficient to dissolve the highest melting waxes present.
  • FIGURE 1 shows the criticality of the centrifugation temperature on the pour point of preheated whole Zelten crude.
  • Zelten crude having a 55 F. upper pour was preheated to 200 F. and centrifuged at the indicated temperatures. Thhe centrifuge was operated at 13,000 gs and the residence time was 15-20 seconds. It can readily be seen that for Zelten crude, an unexpected reduction in pour point can be obtained by centrifuging, after preheating, at a temperature of 4050 F. while, at the same time, minimizing the amount of resid. fraction loss to the dense phase.
  • FIGURE 2 of the accompanying drawings shows the effect of the natural pour inhibitors; i.e., asphaltenes and resins, on whole visbroken resid.
  • the curved line shows the effect of reheat temperature on the pour point of whole visbroken resid.
  • the top line shows that reheat temperature has no effect on pour point of the resid. in the absence of the natural pour inhibitors.
  • the middle line shows that the asphaltenes have a slightly better effect on pour point than the resins. It is noted, however, with only the resins or asphaltenes present that the reheat temperature has little or no effect on pour point.
  • Table I shows the effectiveness of reducing the pour point of a waxy crude and the resulting improvement in reduction of pour point of a resid. fraction obtained .by using the process of this invention.
  • Table II is a presentation of data showing the effects of centrifugal force, temperature of centrifugation, residence time, and thermal history of the crude treated on the percentage of material separated and pour point.
  • centrifugation temperature is important in order to opti; mize conditions of crude viscosity and wax agglomerate size to yield maximum selectivity for separating the high pour wax. This occurs in the range of 40 to 50 F. If the centrifuge temperature is too high, the wax agglomerates will be too small to be selectively separated. In fact, at 'sufliciently high temperatures, the heavy asphaltic materials which act as pour inhibitors may be preferentially separated and the pour of the crude can actually be increased. At temperatures below about 40 F., the selectivity of wax separation progressively decreases because of separation of viscous nonwaxy material with the Wax-rich fraction. Moreover, if the temperature is sufficiently low, the viscosity of the oil will become so high that solid particles can no longer move through the medium and no separation will be possible. This is brought out by the data presented in FIGURE 2 of the drawings.
  • FIGURE 3 of the accompanying drawings is a schematic flow diagram showing one arrangement of apparatus which may be used in the practice of one embodiment of the invention.
  • the heated crude is withdrawn through line 3 and introduced to cooler 4 where it is cooled to a temperature between 40 and 60 F.
  • the cooled crude is then charged to centrifuge 6 through line 5 wherein it is continuously centrifuged under a force of 7,000 to 13,000 gs for a residence time of 5 to seconds.
  • the main oil is taken off through line 7 and F. resid. fraction is withdrawn through line 11a and may be cycled through a heat exchange to the preheater to partially heat the incoming crude.
  • the crude charged to preheater 2 has a pour point between 45 and 55 F.; whereas, the main oil withdrawn through line 7 has a pour point of 25 to 35 F.
  • the wax-rich fraction withdrawn through line 12 from centrifuge 6 may be sent to a conventional pipestill 13 where it is separated into various desired fractions. For example, an overhead fraction containing 680 F. is withdrawn through line 14 and would constitute 40% by volume of the wax-rich fraction. A 1100 F. l-l-I fraction is withdrawn through line 16 which would constitute 10% by volume of the wax-rich fraction.
  • a very good feed for a steam cracker, 680/ 1100 R, which constitutes about 50% by volume of the Wax-rich fraction and which is almost all wax, is withdrawn through line 15.
  • the pour point of the resid. fraction is about 75 to F., as compared to a pour point of F. of the resid. fraction obtained from the untreated crude.
  • This process of selectively removing the waxes which cause high pour point in crudes and resid. fractions may be utilized to efficiently and economically reduce the pour point of crudes for handling at low temperatures, as well as improving the pour point of the resid. fractions so that they themselves may be more easily handled as residual fuels.
  • the residual fuels thus improved in pour point can, of course, be blended with other oils of lower pour point to make a more marketable product.
  • applicants process of utilizing the natural pour inhibitors present in the crude may be used to remove wax from other high wax concentration fractions by combining the crude with said high wax content fraction and carrying out applicants process wherein waxes which cause high pour point are selectively removed.
  • the entire crude was preheated at atmospheric pressure to a temperature of 200 F.
  • the lighter ends that distilled off were refluxed and returned to the preheater.
  • the crude had an initial pour point of 55 F.
  • the preheated crude was cooled rapidly to a temperature just above its pour point and then cooled at a rate of 1 to 2 to the centrifugation temperature of 43 F.
  • the cooled crude was continuously centrifuged in a conventional centrifuge operating at 13,000 gs with a residence time of about 6 seconds for the crude in the centrifuge.
  • a wax-rich phase was separated and amounted to about 7.5% by weight, based on the crude.
  • the main oil separated had a pour point of 35 F, and a 680 F.
  • H-I residual oil fraction distilled from the crude had a pour point of about 80 F. This pour point represents a reduction in pour in
  • the waxes responsible for high pour point in the residual fraction may be selectively removed from the crude with a minimum loss of resid.
  • This process is carried out in relatively inexpensive equipment and in an efiicient and economical manner.
  • the natural pour inhibitors in crude oil are utilized to selectively separate the undesirable high pour waxes.
  • An improved process for the refining of a crude oil of high pour point, containing wax and asphalt fractions, to reduce its pour point which comprises heating an entire crude to a temperature of from 160 to 220 F., cooling the oil to a point just above the cloud point and thereafter slowly at a controlled rate until a temperature between 35 and 55 F. has been reached thereby precipitating a portion of the said wax fraction from the said crude oil, centrifuging the precipitated wax agglomerates at a temperature between 35 and 55 F. to separate a dense wax phase from the crude, and recovering a crude of substantially lower pour point.
  • a process for improving the pour point of a Zelten crude containing about 6-10 wt. percent of wax, based on crude, and of the 680 F.+ resid. fraction containing about 19-22 wt. percent of wax, based on resid. comprising heating the entire Zelten crude to a temperature of about 180-210 F., shock cooling the heated crude to just above its cloud point, then cooling at a controlled rate of 0.5 to 2 per minute to a temperature of about -50" F. and continuously centrifuging the cooled crude at a temperature of 40 to F. to separate a dense Wax phase and a main oil substantially reduced in pour point.

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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)
US98668A 1961-03-27 1961-03-27 Process for reducing the pour points of crude oils Expired - Lifetime US3136711A (en)

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Application Number Priority Date Filing Date Title
US98668A US3136711A (en) 1961-03-27 1961-03-27 Process for reducing the pour points of crude oils
GB8950/62A GB979772A (en) 1961-03-27 1962-03-08 Improvements of low temperature properties of oils
DEE22599A DE1216468B (de) 1961-03-27 1962-03-23 Verfahren zur Fliesspunktserniedrigung von Rohoelen
FR962507A FR1392602A (de) 1961-03-27 1964-02-03
NL6401913A NL6401913A (de) 1961-03-27 1964-02-27
BE644537D BE644537A (de) 1961-03-27 1964-02-28

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BE (1) BE644537A (de)
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FR (1) FR1392602A (de)
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NL (1) NL6401913A (de)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3369992A (en) * 1966-03-18 1968-02-20 Gulf Research Development Co Low pour point synthetic crude oil
US4577677A (en) * 1985-01-07 1986-03-25 Phillips Petroleum Company Method for cleaning heat exchangers
US4781819A (en) * 1983-07-06 1988-11-01 The British Petroleum Company P.L.C. Treatment of viscous crude oils
US5470458A (en) * 1989-02-01 1995-11-28 Ripley; Ian Method for the recovery of black oil residues
US20040089589A1 (en) * 2001-03-27 2004-05-13 Mason Thomas G. Disaggregation of asphaltenes in incompatible petroleum oil mixtures
WO2015108883A1 (en) * 2014-01-20 2015-07-23 Applied Research Associates, Inc. High efficiency pour point reduction process
CN115851314A (zh) * 2022-11-15 2023-03-28 国家能源集团宁夏煤业有限责任公司 一种润滑油基础油和其制备方法

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115125034B (zh) * 2022-07-29 2023-08-01 河南申豫之星空天技术有限公司 一种导热油加热发汗制备高熔点相变蜡的装置及工艺

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US369902A (en) * 1887-09-13 Sylvania
US1416890A (en) * 1920-03-12 1922-05-23 Philip T Sharples Method of refining petroleum
US1732143A (en) * 1927-07-16 1929-10-15 Travis Process Corp Process of removing amorphous wax from petroleum oils
US1974398A (en) * 1931-08-15 1934-09-18 Tide Water Oil Company Method of chilling lubricating oils for dewaxing
US2100662A (en) * 1935-03-12 1937-11-30 Standard Oil Co Dewaxing petroleum oils
US2770577A (en) * 1952-07-11 1956-11-13 Stossel Ernest Process of separating microcrystalline waxes from crude oil
GB851135A (en) * 1958-07-23 1960-10-12 British Petroleum Co Treatment of fuel oils
US3038854A (en) * 1959-02-09 1962-06-12 Texaco Development Corp Solvent dewaxing

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US369902A (en) * 1887-09-13 Sylvania
US1416890A (en) * 1920-03-12 1922-05-23 Philip T Sharples Method of refining petroleum
US1732143A (en) * 1927-07-16 1929-10-15 Travis Process Corp Process of removing amorphous wax from petroleum oils
US1974398A (en) * 1931-08-15 1934-09-18 Tide Water Oil Company Method of chilling lubricating oils for dewaxing
US2100662A (en) * 1935-03-12 1937-11-30 Standard Oil Co Dewaxing petroleum oils
US2770577A (en) * 1952-07-11 1956-11-13 Stossel Ernest Process of separating microcrystalline waxes from crude oil
GB851135A (en) * 1958-07-23 1960-10-12 British Petroleum Co Treatment of fuel oils
US3038854A (en) * 1959-02-09 1962-06-12 Texaco Development Corp Solvent dewaxing

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3369992A (en) * 1966-03-18 1968-02-20 Gulf Research Development Co Low pour point synthetic crude oil
US4781819A (en) * 1983-07-06 1988-11-01 The British Petroleum Company P.L.C. Treatment of viscous crude oils
US4915819A (en) * 1983-07-06 1990-04-10 The British Petroleum Compan Plc Treatment of viscous crude oils
US4577677A (en) * 1985-01-07 1986-03-25 Phillips Petroleum Company Method for cleaning heat exchangers
US5470458A (en) * 1989-02-01 1995-11-28 Ripley; Ian Method for the recovery of black oil residues
US20040089589A1 (en) * 2001-03-27 2004-05-13 Mason Thomas G. Disaggregation of asphaltenes in incompatible petroleum oil mixtures
US7029570B2 (en) * 2001-03-27 2006-04-18 Exxonmobil Research And Engineering Company Disaggregation of asphaltenes in incompatible petroleum oil mixtures
WO2015108883A1 (en) * 2014-01-20 2015-07-23 Applied Research Associates, Inc. High efficiency pour point reduction process
US10961469B2 (en) 2014-01-20 2021-03-30 Applied Research Associates, Inc. High efficiency pour point reduction process
CN115851314A (zh) * 2022-11-15 2023-03-28 国家能源集团宁夏煤业有限责任公司 一种润滑油基础油和其制备方法
CN115851314B (zh) * 2022-11-15 2024-05-31 国家能源集团宁夏煤业有限责任公司 一种润滑油基础油和其制备方法

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FR1392602A (de) 1965-03-19
NL6401913A (de) 1965-08-30
GB979772A (en) 1965-01-06
DE1216468B (de) 1966-05-12
BE644537A (de) 1964-08-28

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