US2195833A - Treatment of hydrocarbon oils - Google Patents

Description

Apmifl Z, 1940. c. WIRTH, so ,8

TREATMENT OF HYDROCARBON OILS Filed Sept. 30, 1937 SETTLING TANK INVENTOR CHARLES WIRTH III Patented pr. 2, 1940 STATES 2,195,833 I TREATMENT OF HYDaooARBoN OILS Charles Wirth, IIL Chicago, 111., assignor to Universal Oil Products Company, Chicago, 111., a corporation of Delaware Application September 30, 1937, Serial No. 166,569

8 Claims.

The invention particularly refers to an improved process and apparatus for efiecting the removal of salt water or brines from hydrocarbon oils such as crude petroleum, reducedcrude and the like, which contain appreciable quantities of the same in the form of a water-in-oil emulsion.

The desirability of removing salts from petroleum oil is well recognized and has heretofore been a difficult problem in the oil refining industry. Most emulsions of the type referred to cannot be readily broken by centrifuging, filtration or absorption of the salt water by solid adsorbents and the like. The only known successful methods of breaking such emulsions are by distillation at substantial superatmospheric pressure, or by solvent extraction, either of which is costly and involves other difiiculties such as the corrosion problem normally present in distillation processes of this type and the expense'of recovering the solvent.

In the pyrolytic conversion of oils of the type above referred to, difiiculties are encountered due to the deposition of salts in the cracking. coil,

present, and one of the chief utilities of the invention is its adaptability to the continuous treatment of cracking stocks for the removal of salts therefrom prior to its introduction into the cracking zone.

An important novel feature of the invention resides in the provision for heating both the oil to be treated and the extraneous water with which it is intimately contacted, preferably to a temperature well above the normal boiling point of water and at a superatmospheric pressure adequate to maintain the Water. in liquid phase both during mixing and during the subsequent settling, L0 the latter being preferably accomplished without substantial loss of heat. Preferably, the oil and the extraneous water are'separately heated, since I have found that by this method the viscosity of the oil may be sufiiciently reduced prior to its 5 contact with the water, to prevent theformation of stable emulsions. This has been found particularly desirable with relatively heavy oils or oil of fairly high viscosity.

As' another special feature of the invention, it

.0 provides for diluting the heavy oils to be treated with regulated quantities of a lighter hydrocarcon oil prior to contacting the former with the extraneous water. This has much the same effect as separate heating of the heavy oil prior to its 5 contact with the extraneous heated Water, since a as Well as due to corrosion of the cracking equipmerit, particularly when magnesium chloride is,

similar reduction in the viscosity of the heavy oil is thereby obtained. However, these two features may be utilized conjointly Within the scope of the invention and are not to be considered fully equivalent. Any suitable light oil such as naphtha, kerosene, kerosene distillate, gas oil and the like may be utilized as a diluent for the heavy oil and may be commingled with the latter in heated state or the light and heavy oils may be commingled in relatively cool state and subsequently heated to the desired temperature, preferably prior to their contact with the extraneous water.

When the process is operated in conjunction with a cracking system, reflux condensate formed by fractionation of the vaporous products of the cracking process or selected low-boiling fractions of the reflux condensate, may be utilized as a diluent for the heavy salt-containing cracking stock and in such cases, heating of the diluent prior to commingling the same with the heavy oil is normally obviated due to the fact that it may be recovered from the fractionator of the cracking system in heated state.

The accompanying diagrammatic drawing illustrates one specific form of apparatus embodying the features of the invention and in which the process of the invention-may be successfully conducted. The invention is, of course, not limited to the particular type or form of apparatus illustrated.

Referring to the drawing, the oil to be treated, which may comprise a crude petroleum, reduced crude or the like containing a substantial quantity of inorganic salts in the form of brine or salt water emulsified with the oil, is supplied through line I and valve 2 to pump 3 by means of which it is fed through line 4 and valve 5 to heat exchanger 6, passing therethrough in indirect heat exchange with any suitable heating medium and being discharged therefrom through line i and valve 3 into a suitable enlarged settling chamber 10.

Simultaneously with the introduction of the oil into the settling tank, Water or a solution of salt and water is supplied through line it and valve E2 to pump it by means of which it is fed through line Hi and may be thence directed through line 2 5 and valve 56 into line 4 to commingle therein with the oil to be treated or, preferably, the Water is directed through valve 95 in line M to and through heat exchanger 56, pass-v ing through the latter in indirect heat exchange with any suitable heating medium andbeing discharged therefrom through line it wherefrom it may be directed all, or in part, through line l9 and valve 261 into settling chamber ill or wherefrom it may be introduced all, or in part, through valve l8 into line i to commingle therein with the separately heated oil from heat exchanger 6 following which the mixture is discharged into chamber It.

In the particular case here illustrated, the heating medium utilized in heat exchangers E3 and [6, which may comprise, for example, relatively hot vaporous or liquid products derived from a conjointly operated cracking system, not illustrated, is supplied in regulated quantities to the two heat exchangers, when both heat exchangers are utilized, from line 2! through branch lines 22 and 23 controlled, respectively, by valves 25 and 25.

and after heating the oil and extraneous water in the respective heat exchangers 6 and I6, is di charged therefrom through the respective lines 265 and 2's! controlled, respectively, by valves 23 and 2s into line 38 wherefrom it may be directed back into the cracking system, for example, or elsewhere, as desired. The invention is, of course, not limited to the use of the same heating medium in the two heat exchangers, nor is it limited to this particular method of heating the oil and extraneous water.

Although settling chamber it is here illustrated as a horizontally disposed cylindrical tank or drum, it may comprise a vertically disposed vessel or any other suitable form of settling equipment. The settling chamber is preferably insulated to prevent the excessive loss of heat therefrom and maintain materials undergoing treatment at the desired temperature, insulation being indicated in section at 38.

Preferably, the form of settling chamber here illustrated is maintained full of liquid at substantial superatmospheric pressure, the upper portion of the body of liquid in said chamber being treated oil and the lower portion of said body of liquid comprising salt water. The oil and salt water stratify in chamber Hi upon settling due to their diiferent specific gravities and the interface between the two is indicated in the drawing by line 32, although there is not necessarily a sharp segregation between the two layers and, in most cases, there will be an intermediate layer of emulsified oil.

When hot water or a hot solution of salt-inwater is supplied from heat exchanger lt directly to chamber Ill, it is preferably introduced into the latter zone, at any desired point or plurality of points therein, although the drawing illustrates only provision for introducing the water or salt water into the bed of water in the chamber beneath the interface between the oil and water layers.

The heated oil to be treated may be supplied, as previously indicated, from heat exchanger 6 to chamber it), either alone or in admixture with all or a regulated portion of the separately heated extraneous water or salt solution from heat exchanger H3 or with extraneous water or salt solution heated in commingled state with the oil, and in either case, this material is preferably supplied through line I to the lower portion of the settling chamber wherein it intimately contacts the body of salt water in this zone. Provision is preferably made for insuring intimate contact between the salt water in chamber! ii and the material supplied to this zone through line i, a suitable perforated pipe or spray device 33 for this purpose being illustrated in the drawing.

Salt water is removed from the lower portion of chamber I0 and from the system through line 34 and valve 35, the rate of removal preferably being regulated by means of valve 35 (which may, when desired, be an automatic control valve) so that a substantial constant quantity of salt water remains in the settling chamber.

The treated oil, from which some or more, of the salt has preferably been removed by the treatment afforded, is removed from the upper portion of chamber in in regulated quantities through line 36 and valve 3'! to subsequent crack ingequipment, not illustrated, or to cooling and storage or elsewhere, as desired. Valve 31 may, when desired, be an'automatic pressure control valve for maintaining a substantially constant superatmospheric pressure in chamber Hi.

When it is desired to dilute the salt-containing oil to be treated, a suitable relatively light oil, such as above mentioned, may be directed from a conjointly operated cracking system, not illustrated, or elsewhere, as desired, through line 38 and valve 39 to pump lB wherefrom it is discharged through line 4!. When the light oil is supplied to the system in heated state it may be directed through line 4! and valve' 42 into line i to commingle therein with the relatively heavy oil which it serves to dilute, preferably, prior to the commingling of the latter with the extraneous water or salt solution from heat exchanger I6. In some cases the use of hot reflux condensate or selected fractions thereof from the fractionator 'heat exchanger 6 for heating the latter or will at least materially reduce the amount of additional heat required to heat the heavy oil to the desired temperature of treatment, the extent of such additional heating being dependent, of course, upon the amount of hot diluent used and its temperature. In case the diluent is supplied to pump 49 in relatively coolstate, it is preferably directed therefrom through. line 4|, line 43 and valve 44 into line 4 wherefrom it passes in commingled' state with the heavy oil which it serves to dilute through heat exchanger 6 and therefrom, in the manner previously described, to chamber [0, or, when desired, a separate heat exchanger, or the like, may be provided for the diluent. 7

Extensive experimentation with the present process to determine optimum operating conditions both in the laboratory and'on-semi-commercial scale, indicate that there are several factors to be considered for best results and that the preferred operating conditions may vary considerably with different types of oil and, more particularly, with oilsv containing varying percentages of salts. Therefore, no rigid rules for obtaining the most advantageous results will apply to all stocks. However, the experiments indicate that temperatures-ofthe order of 325 to 375 F., or more, with a sufllciently higher superatmospheric pressure to. retain the water in liquid state (300 pounds per square inch gauge pressure, for example) are ordinarily more advantageous than lower temperature and pressure conditions or higher temperatures and correspondingly higher pressures. It has also been found that there. is a pronounced advantage in separately heating the oil to be treated and the extraneous water prior to commingling the same, since the results indicate that this largely prevents the formation of stable emulsions. However, this precaution is not essential with all oils and the invention is therefore not limited to this feature. Dilution of the heavy oil prior to mixing the same with the extraneous water is also advantageous in much the same respect. It is also desirable to avoid excessive agitation of the mixture, although thorough mixing of the oil and water is, of course, essential. There appears to be a slight advantage in adding controlled amounts of salt to the extraneous water to be contacted with theoil. This is reflected in a sharper separation between the water and oil layers in the settling step, but does not appear to materially affect the percentage of salt removed from the oil.

As a specific example of the operation of the process of the invention, a mixture of West-Texas and Mid-Continent topped crudes of approximately 24 A. P. I. gravity and containing approximately 195 pounds of salts per thousand barrels is heated in a continuous stream to a temperature of approximately 310 F. The heated topped crude is commingled with approximately 20% by volume of light oil of the nature of kerosene distillate recovered as a hot sidestream from the fractionator of a cracking system, the light oil being commingled with the heavy oil at a temperature sufficient to increase the temperature of the latter to approximately 350 F. The hot commingled oils are then mixed with approximately 10% by volume of water, the latter being previously heated to approximately 350 F. and the mixture is discharged into the settling chamber. The system is operated at a superatmospheric pressure of approximately 300 pounds per square inch. The settling chamber is maintained substantially full of liquid, the heated mixture being sprayed upwardly into the water layer in the settling chamber. The settled salt water which contains approximately 95% of the salt originally contained in the oil is removed from the lower portion of the settling chamber and a substantially salt-free oil is recovered from the upper portion of the settling chamber. In this particular instance, the oil thus recovered is supplied while still in heated state to the fractionator of the same cracking system from which the aforementioned sidestream, used as a diluent, is recovered.

I claim as my invention:

1. A method of removing salt water or brine from hydrocarbon oil containing a substantial quantity of the same which comprises heating said oil in a flowing stream to a temperature of the order of 325 to 375 F. at superatmospheric pressure, separately heating a stream of water to substantially the same temperature under sufficient pressure to prevent vaporization, commingling the two streams and maintaining the resulting mixture at a superatmospheric pressure sufiicient to retain the oil and water in liquid state, introducing said mixture while still in heated state into a settling chamber maintained at substantially the same temperature and superatmospheric pressure, causing the resultant salt water and substantially de-salted oil to stratify in the settling chamber, and separately removing the same therefrom.

2. A process such as defined in claim 1 wherein the mixture of heated oil and separately heated water is introduced into a substantial body of salt water maintained in said separating chamher.

3. A process such as defined in claim 1 wherein the mixture of heated oil and separately heated water is introduced in sub-divided state into a substantial body of salt water maintained in said separating chamber.

4. A process such asdefined in claim 1 wherein the mixture of heated oil and separately heated water is sprayed upwardly into a substantial body of salt Water maintained in said separating chamber.

5. A method of removing salt water or brine from hydrocarbon oil containing a substantial quantity of the same which comprises diluting said oil to materially reduce its viscosity and specific gravity by commingling therewith regulated quantities of an oil of substantially lower boiling characteristics, separately heating a stream of the resulting commingled oils and a stream of water at a temperature of the order of 325 to 375 F. under suificient pressure to prevent vaporization, introducing the heated streams into a settling chamber maintained at substantially the same temperature and pressure, causing the resultant salt water and substantially de-salted oil to stratify in the settling chamber, and separately removing the same therefrom.

6. A process such as defined in claim 5 wherein said heated streams are introduced into a substantial body of salt water maintained in the settling chamber.

7. A process such as defined in claim 5 wherein said heated streams are introduced in subdivided state into a substantial body of salt water maintained in the settling chamber.

8. A process such as defined in claim 5 wherein said heated streams are sprayed upwardly into a substantial body of salt water maintained in the settling chamber.

CHARLES WIRTH, III.

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