US3181058A - Method and apparatus for determination of amount of salt in hydrocarbon oil - Google Patents

Description

April 21, 1965 Filed Ju1y5, 19s:

A. F. GULBRANDSEN 3,181,058 IBI'BOD AXD AIPARATUS FOR DBTERIIINATION OP lAIOUII'l' OF SALT IN HYDROCARBOH OIL 3 ShQOtQ-Shili 1 CURRENT (MA) I l I B0 '25 :00 SALT coewsm mm mas/100 0991,;

INVEN'TOR ATTORNEY Ap 1965 A. F. GULBRANDSEN 3, 8 58 v I HBTHOD AND APPARATUS FOR DETERMINATION OF AMOUNT OF SALT IN HYDROCARBON OIL Filed July 5, 1963 3 Sheets-Sheet 2 2. N3 Liza mint gar INVENTOR ARTHUR F- GULBRANDSEN Mm 244- ATTORNEY mo. om

E w 3, a5. m. u H w v: v v m mz0mmum aw s 53 N E a. q Z; w $9 April 27,1965 A. F. GULBRANDSEN 3,181,058 ma'ruon AND APPARATUS FOR DETERMINATION OF AIOUNI' OF SALT INHYDROCAHBON OIL a sneexs-sheei :5

Filed July 5. 1963 mus; Jomhzou wcamu INVENTOR- ARTHUR F- GULB DSEN BY w/dm 4 ATTORNEY zucmouum oh 4 to rates arm pending application Serial Number.148,137, filed on on ber 27, 1961, now abandoned.

This invention relates to the treatment of hydrocarbon oils and more particularly to apparatus and a method for the analysis of crude oil to determine the amount of salts present in the crude oil.

All crude oils, when produced,contain various amounts of emulsified salt solutions. Treatment in'the field usually reduces the amoimt of such emulsion very materially but crude oils delivered to refineries still contain appreciable quantities of salts. In some instances the crude may still contain in excess of 100 lbs. of-such salts per 1,000 barrels of oil. The composition of the salts in crude oils varies considerably but the salts present usually consist largely of the chlorides of sodium, calcium and magnesium with smaller amounts of sulfate and other anions. In the refinery the salt present in the crude oil tends to be deposited in heat exchanger tubes, thereby fouling the tubes and causing expensive shutdowns for cleaning. In addition, when such crude oil is heated, hydrolysis of the alkaline earth chlorides present liberates hydrochloric acid which corrodes vapor lines and con-' denser surfaces. For these reasons, it is important that the salt content of crude oil be reduced to the lowest practical limit prior to refining. In practice, the salt content of crude oils is frequently reduced to 3 or 4 lbs. per 1,000 barrels of oil or less.

The usual method for reducing the salt content of crude oil is by means of electrical precipitation. In order to know the most effective setting of the electrical instruments that control the desalting operation, it is-necessary to know the salt content in the efiiuent crudeoil, coming from the desalting equipment. While there is no completely standard method for analysis for the salt content of crude oil, there arenurnerous methods in use'in the industry. While not entirely similar, these methods are all alike-in principle. In these metho is of analysis a sample of the crude oil to be tested is thoroughly mixed or shaken with hot water to dissolve the salts. The aqueous solution is then separated and the salts present in the aqueous solution are determined by suitable means such as by titrating with standard silver nitrate solution. Due to the formation of emulsions, a number of hours may elapse before the water layer has separated completely enough so that the analysis can be completed. During this time the dcsalting equipment may or may not be functioning properly. Also, the results of such tests for salt content are frequently accurate only to about plus or minus of the salt present.

It is an object of the present invention to provide an .improved method and apparatus for determining the salt content of hydrocarbon oil by which the analysis may be completed in a very short length of time and with a high degree of accuracy. It is another object of this invention to provide a method and apparatus for the determination of salt in hydrocarbon oil for refinery operations in the form of automatic continuous or intermittent salt determination in a flowing stream of oil and, where desired, a continuous or intermittent recordation of the salt content of that oil.

In accordance with a preferred embodimentof the presa polar organic solvent to form a-homogeneous, single phase solution. If the crude oil contains appreciable quantities of asphaltic material, it ispreferred to use a strong non-polar organic solvent in additionto the polar solvent to insure that the asphaltic material is dissolved in the solution and is not precipitated by the addition of the polar solvent, Generally the mixture of crude with the polar organic 's olveutor the mixture of crude, polar organic solvent and the non-polar organic solvent must be thoroughly mixed to form a homogeneous mixture. When the crude contains appreciable quantities of asphaltic material it is preferred to first mix the crude with the non-polar solvent to form a homogeneous mixture and then to add the polar solvent to this mixture and form the final mixture to be tested. organic solvent is added to crude containing appreciable quantities of asphaltic material prior to the mixture of this crude with a non-polar organic solvent, a precipitate forms which deposits on the equipment andwhich often causes erroneous test readings. The'resulting singlephase solution is then contacted with spaced electrodes maintained at a known potential with alternating currentand the conductivity of the solution is measured by measuring the flow of alternating current between the electrodes.

For a better understanding of the invention reference should be had to the accompanying drawingswherein identical numerals refer to identical parts and inwhich FIGURE 1 is a diagrammatic illustration of apparatus suitable for carrying out a preferred embodiment of the invention;- I

FIGURE 2 is a graph showing the relationship between salt content of crude oil and current passing between electrodes when practicing a preferred embodiment of the invention with the apparatus shown in FIGURE 1;

FIGURE 3 is a digrammatic representation of preferred apparatus for use with a method for the automatic intermittent analysis of a flowing stream of crude'in a refinery;

FIGURE 4 is a diagrammatic representation of a positive displacement metering pump and some of itsassociated parts which is used for metering crude;

FIGURE 5 is a diagrammatic representation of an electrical circuit and associated parts which can be 'used with the apparatus of FIGURE 3; and

FIGURE 6 is a diagrammatic representation of the sequence timer which can be used in the electrical circuit of FIGURE 5.

Referring to FIGURE 1, suitable apparatus is shown for maintaining a constant alternating current potential at terminals 11 and 12 of electrodes 13 and 14. While any suitable means for providing a suitablealternating current potential across these electrodes may be used, the apparatus shown and described in FIGURE 1 has been found convenient for this purpose. As shown in FIGURE 1, the apparatus may include terminals 16 and 17 adapted to be connected to a suitable source of alternating current such as ordinary volt house current. A switch 18 may be provided for shutting, off the AC. potential without necessity for disconnecting the terminals 16 and 17 and a pilot light 19 may be provided to indicate when the apparatus is connected and ready for use. In order to insure a constant alternating current potential at the electrodes l3 and 14, an adjustable auto transformer 20 may be provided to control the voltage supplied to the input side of a transformer 21. A volt meter 22 is preferably provided to measure the voltage supplied to the input of the transformer 21. While not essential, the transformer 21 may be used to increase the voltage across the electrodes 13 and 14 above that available at the terminals 16 and 17. As indicated in FIGURE 1, theoutput side of the .transformer 21 is connectedto the terminals 11 If the polar 3. I and 12 of the electrodes 13 and 14 to supply a constant alternating current potential thereto. A fuse 23 may be used to insure against overloading and suitable means such as a milliammeter 24 are provided for measuring the flow of current between the electrodes 13 and 14.

In the practice of the present invention a mixture of crude oil and solvent prepared as described below is contacted with electrodes 13 and 14. The current which passes between the electrodes at a given voltage is measured by the milliammeter 24 to provide an indication of the amount of salts present in the crude oil. It has been found that the conductivity of solutions of crude oil and solvent containing salts-does not appear to depend upon the particular salt present or the relative proportions of several of the various salts commonly found in crude oil. It has, therefore, been found possible by testing a number of crude oil samples of known salt content, to make up a graph, suchvas the one shown in FIG. 2, showing the current readings obtained at a given voltage with crude oils containingvarying amounts of salt. Such a graph may then be used as a reference curve to determine the amount of salt present in an unknown solution. Thus, once the apparatus has been assembled and reference graphs such as that shown in FIG. 2 obtained, a sample of crude oil of unknown salt content may be analyzed extremely rapidly merely by contacting a solution of such crude oil and solvent with the. electrodes 13 and 14, measuring the current passing between the electrodes and determining from the reference graph the salt content corresponding to'the measured current flow. It is, of course, necessary that the same proportions of the same solvent and the same test conditions be used in preparing the reference graph and in analyzing the unknown crude oil samples.

The apparatus in FIG. 3 is particularly suited for the.

finery operations, particularly in determining the salt content of crude which has passed through a desalter. A pipeline 26 carries a flowing stream of crude at 220 p.s.i.g. A smaller diameter conduit or line 28 is tapped into pipeline 26 so that crude constantly circulates from the inlet 30 of line 28 to outlet 32 of said conduit. Intermediate the cnds 30 and 32 of conduit 28 another conduit 34 is tapped into line 28. A solenoid valve 36 is interposed in conduit 34. Valve 36 permits crude to enter the electrical metering pump through inlet 42. Pump 40 is a Milton-Roy pump, Model MDI-23-45 of 2.25 g.p.'h. capacity.

, As shown in FIG. 4 pump 40 comprises a piston 44,

reciprocable in a cylinder 46 formed within a body 48,

and rod connected to anelectrical motor 51. The body 48 has an outlet passage 50 which communicates with one end of conduit 52 having a pressure responsive valve 54 at its other end. Pressure responsive valve 54 comprises a housing 56 a valve seat 58,-and a ball urged against the seat 58 by spring 62. Valve 54 permits liquid to flow therethrough when a pressure-of 250 p.s.i.g. is imparted to the crude by pump 40. Valve 54 is thus in a normally closed position but is actuatable to permit oil to flow from the pump to the sample receiver when the pressure in conduit 52 between the pump outlet and the valve 54 is greater than the pressure in the pipe line 26, conduit 28 and conduit 34. Valve 54 communicates with'one end of conduit 64 which has a manually operated. by-pass valve 66 and a manually operated valve 68 in the line. Normally valve 66 is closed and valve 68 is open. The other end of conduit 64 communicates with and supplies measured quantities of oil to sample receiver 70 which is fitted with plate 72, stirrer 74 and electrodes 13 and 14. r

The bottom of the sample receiver 70 communicates with one end of conduit 78, so that liquid contents thereof can be drained, which in turn communicates with the inlet of electrical metering pump and motor 80. Metererally, means are provided such as a U-bend in conduit 78 so as to prevent appreciable quantities of oil from flowing from the sample receiver into the conduit 78 unless the pump 80isactivated. One end of conduit 82 communicates with the outlet of pump 80 while the other end thereof communicates with the conduit 28 downstream of the connection of conduit 28 with conduit 34. A one way check valve 84 prevents the flow of crude from conduit 28 into conduit 82. Conduit 86 communicates with sample receiver or cell 70 and carries a substantially anhydrous xylene from one end of conduit 88 and a mixture of substantially anhydrous alcohol from one end of conduit 90. Pipeline 88 has a solenoid valve 92.interposed therein. The other end of pipeline 88 is operatively connected to the outlet side of electrical pump and motor 96. Intermediate solenoid valve 92 and pump 96 is a one way check valve 98 and relief valve 100. The inlet side of pump 96 communicates with one end of pipeline 102 which supplies xylene thereto from a suitable container which is not shown. One end of pipeline communicates with the pump104 which is operatively connected to electric motor 106. Intermediate the ends of pipeline 90 is a valve .108 controlled by solenoid 110, a one way check valve 112 for preventing the flow of alcohol back into pump 104 and a pressure relief valve 114. Communicating with the inlet side of pump 104 is one end of pipeline 116 while the other end of this pipeline communicates with a source of a mixture of alcohols not shown. The mixture of alcohols contains 37 volume percent methanol and 63 volume percent n-butanol.

The operation of the apparatus of FIGS. 3 and 4 is controlled by the electrical circuits shown in FIG. 5. Three-timing mechanisms are interposed in the electrical circuit. All three of these timers are simply referred to herein collectively as a program timer. The individual timers are a control timer 118, a holding timer and a sequence timer 122. Timers 118 and 120 are well known timers and the combination unit of timers 118 and 120 is commercially available, e.g. Cramer-Type 742 timer. The sequence timer 122 is also a commercially available timer. One such timer is a Cramer-Type 521, 8 pole timer which makes one revolution in three minutes. The electrical circuit of FIG. 5 is closed by manually operated timer switch 124 which is normally in the closed position. A manually operated switch 126 is also provided for, energizing blower 128 to provide air circulation about the apparatus.

Sequencetimer 122 comprises an electric motor 130. Keyedinto shaft 130 are cams 1'34, 136, 138, 140, 142 and 144. On revolution of theshaft 130 cam 134 closes electrical contacts 144 which energizes motor 130 and stirrer motor 131. Cam 134 keeps contacts 144 closed during the entire analysis cycle which lasts for 3 minutes during which time the remaining cams actuate their corresponding electrical contacts for predetermined periods of time. Cam.136 closes electrical contacts 146 which actuate xylene pump 96 and open solenoid valve 92 for 40 seconds to meter 60 cc. of xylene into sample receiver 70. Cam 138 closes electrical contacts 148 which actuate cmde pump 40 and open solenoid valve 36 for 10 seconds to meter 10 cc. of crude into sample receiver 70. Contacts 148 are closed prior to transferring all the xylene to receiver 70. Cam closes electrical contacts 150 which actuate the alcohol pump 104 and open solenoid valve 108 for 35 seconds to meter 50 cc. of the alcohol mixture to sample receiver 70. Cam 142 closes electrical contacts 152 after the alcohol is thoroughly stirred in receiver 70. Contacts 152 energize the analyzer 158 and its associated electrodes 13 and 14 for 15 seconds. Cam 144 closes electrical contaots 154 which actuate discharge pump 80 after the analyzer is turned off. The discharge pump'operates for the remainder of the 3 minute analysis cycle. It drains receiver 70 and pumps the analyzed liquid into conduit The circuit also contains momentary contact switches 156 to actuate manually when desirable, each of the pumps and solenoids for xylene, crude, alcohol and the discharge pump. The. analyzer 158 can be identical to that shown in FIG. 1 except that the power source of the analyzer is through wires 160 and 162 and the ammeter 24 can be eliminated or its terminals operatively connected by wiring 164 and 166 .to a recorder which is not shown.

In the automatic intermittent operation of the apparatus shown in FIGS. 3-6, a constant supply of 60 cycle 117 volt alternating current is provided for the electrical circuit by wires 168 and 170 through source 169-. The timer switch 124 is closed and this starts the control timer 118. The control timer can be set for any time between 0 and 60 minutes. In the preceding description it was set for 15 minutes. When the control timer 118 reaches a preset point, e.g. 15 minutes, it energizes holding timer 120. The control timer 118 then goes to its reset position to start the cycle again, e.g. for 15 minutes. The holding timer 120 bypasses sequence timer motor' switch 144 but energizes motor 130 until the cam actuated motor switch 144 in sequence timer 122 is closed. On closing of contacts 144 holding timer 120 goes to its reset position and sequence timer motor 130 is controlled by cam 134 and contacts 144. v

. In determining the salt content of crude oil in accordance with the present invention the mixture of diluent or diluents and crude oil should be a single phase, homogeneous mixture in which thesalt present in the crude gives the mixture sufiicient conductivity to be capable of measurement as described above. The salt in crude oils to be measured in accordance with the invention is usually present in the form of a water emulsion which is present in very small amounts and does not form a continuous phase. Direct measurement of the conductivity of such crude oil samples is generally impractical or impossible. While the quantity of polar solvent (or diluent) to be added may vary over extremely wide ranges and the amount to be used is almost entirely within the choice of the operator, it has been found convenient in many instances to use between about 1 and about 100 volumes of polar solvent per volume of crude oil. Mixing or shaking the crude oil with such solvent forms a homogeneous single phase solution or mixture which may then be tested for salt content by contacting it with a pair of spaced electrodes such as the electrodes 13 and 14 described above. Organic polar solvents suitable for this purpose include but are not limited to such solvents as alcohols and ketones, e.g. methyl alcohol, n-butyl alcohol, acetone, ethyl alcohol, propylene glycol, etc. While any suitable organic polar solvent or mixtures thereof may be used, alcohols containing from 1 to about 6 carbon atoms and particularly alkanols, have been found especially useful for this purpose. Preferably the polar solvent is a mixture of alkanols such as methanol and n-butanol. In one preferred embodiment the volume of methanol and n-butanol is from 3 to7 times the volume of crude sample wherein the volume of methanol in the alcohol mixture is from about 0.3 to 2 parts methanol per part of n-butanol; also, in such a combination it is preferred that the non-polar solvent, e.g. xylene, is from about 3 to- 7 times more than the volume of crude.

Where the crude oil to be tested contains asphaltic material (considered herein as being hydrocarbon material which is not soluble in pentane), strong non-polar organic solvents are preferably used in addition to the polar solvent in order to prevent precipitation of asphaltenes or other asphaltic material. For present purposes, strong organic solvents may be considered those which are capable of dissolving asphaltic material. Such solvents include, but are' not limited to benzene, toluene, xylene, carbon tetrachloride, diethyl ether, ethyl acetate, etc., or combinations of suitable solvents. Of such solvents, aromatic hydrocarbon solvents have been found especially suitable. organic solvents is preferred whenever the crude oil to be tested contains asphaltic material. Such asphaltic material is usually present in crude oil having gravities lower than about 30 API. In accordance with standard pracand reference graph will not be limited to crude oils which do not contain asphaltic material but can be used on most commonly encountered crude oils. I

When non-polar strong organic solvents or diluents of the type described above are used theymay be used in suitable quantities such as between about 1 and about volumes based on the amount of crude oil present. As in the case of the polar solvents, however, the practice of the invention is not limited to the use of solvents in these proportions or concentrations and, especially when the salt content of the crude is relatively high, it may be desirable to use considerably greater amounts of solvents in order to keep the current readings obtained across the across the electrodes fairly low. In this respect, concentrations of solvents yielding relatively low current readings are preferred since, as can be seen from FIGURE 2, the method of analysis described herein is more accurate under such circumstances. Also, of course, with a given equipment setup it may be desirable to bring all of the test data within the range of a single scale milliammeter without the necessity for providing a multi-scale' instrument or switching scales. 1

While it is preferred in practicing the present invention to keep the water content of the solution being tested at relatively low values, such as below about 0.5 volume percent, the presence of greater quantities of water does not adversely affect the analysis except that, as in the case of solvents, the proportions and quantities. of water must be kept constant in order to obtain reliable comparative data. Generally speaking relatively larger quantities of Water increase the conductivity of the solution and exces'sive amounts of water in any given solution make it dilficult or impossible to achieve a single phase homogeneous solution and in general lead to the same difficulties experienced with oil-water emulsions in the practice of previously known methods of analysis for the presence of salts in crude oil.

It is especially important in practicing the present invention that the electrodes be maintained at the desired potential with alternating current. The use of direct current has been found to be entirely unsatisfactory for this purpose due to deposition of constituents of the crude oil on one or more of the electrodes. These deposits build up quite rapidly and have the effect of completely destroying the validity of the data obtained by reducing the apparent conductivity and current readings by unknown factors which vary according to the rapidity and type of deposits built up. While it is essential that alternating current be used, the voltage which is employed may as mentioned above vary over extremely wide ranges at the discretion of the operator. For instance, the use of voltages at the electrodes within the range of between aboutSO and about 500 volts is satisfactory.

The following examples will illustrate the application of one preferred embodiment of the invention using appa- The use of such strong non-polarratus of the type describedabove and shown-in FIG- URE 1.

EXAMPLE 1 In order to establish areference curve for further eval- Teri milliliters of a mid-continent crude oil, when disuation of unknown samples, various samples of crude oil solved in 90 milliliters of the xylene-alcohol solvent of and lubricating oil containing known amounts and pro- Example 1 under the test conditions of Example 1,- gave portions of various salts were analyzed in accordance a reading of 4.0 milliamperes. From the reference curve with the present invention. In these tests each sample of FIGURE 2, this would indicate the presence of 16.5 contained ,salt in the amounts and proportions indicated lbs. of salt per 1,000 barrels of oil. A conventional exin Table I below. Milliammeter readings obtained for 10 traction analysis indicated 17 lbs. of salt per 1,000 bar-' these tests are also shown in Table I and the results obrels of oil.

tained are shown graphically in FIGURE 2. EXAMPLE In these tests each milliliter sample was dissolved ive milliliters of a Gulf Coast crude oil were diluted Bg g g i g z zf ggg gig a s gf with 5 milliliters of xylene and the mixture dissolved in holayl egieteriazlis anhygmust; to aform a0 singleyp 90 milliliters of the xylene-alcohol solvent of Example 1. homoganeous 501 tion and placed in an ASTM dissolved A reading of 5.6 milliamperes under the test conditions of Example 1 was obtained. This was equivalent to 21 lbs. gum test beaker. The electrodes .were placed in the of Salt per 1,000 barrels of oil as indicated by the referof ple only 5 milliliters of sample crude oil was used, the 125 volts across the electrodes. The electrodes for these result was multiplied by 2 to obtain the cquivalent of a tests were stainless steel plates measuring 1 inch by 2 inches by inch and were spaced inch apart 10 milliliter sample test. The value of 42 lbs. of salt per Usinn thearesuns Shown in Table I below a refrence 1,000 barrels of oil thus obtained compares with a value v of 37 lbs. per 1,000 barrels of oil obtained by conventional assists:assessi-ii .323: :2 FIGURE 2 they are not individually reproduced but all EXAMPLE were grouped extremely close to the resulting curve, thus 50 milliliters of Panuco crude oil was diluted with 50 indicating'extremely reproducible results. milliliters of xylene and, as' in the other examples cited,

Table I c 't fsalt wt t Oil Amollltgt cum t l'l 0111:1061 10B 0 S, P910911 (bill/1,000 bbl. of oil) Sodium chloride, 33.3 3 3g- Caleiurn chloride, 33.3- Lubricating oil. l 3 Magnesium chloride, 33.3- 5o 0) Sodium chloride, 3- 3 Calcium chloride, 25 Lubricating Oil 25 8 Magnesium chloride, 25 50 (1) Sodium chloride, as g Calcium chloride 33... Crude oil 25 3 Magnesium chloride, 33. 50 (1) Sodium chloride, 50 I 3 :2 Calcium chloride, 25.. Crude ml 25 8 Magnesium chloride, 25 50 O) l on scale.

The following examples are cited to demonstrate the shaken to dissolve the crude and obtain a single phase accuracy of results obtainable using the method of the homogeneous solution. 3 milliliters of the diluted solupresent invention in conjunction with a reference curve of tion (equivalent to 1.5 milliliters of the original crude oil) the type shown in FIGURE 2. All of the following tests was further diluted with 7 milliliters of xylene. This described below were made with the same apparatus used mixture, when dissolved in 90 milliliters ofthe xylenein Example 1 and the same voltage was maintained across alcohol solvent of Example 1, gave a reading of 2.3 millithe electrodes. amperes under the test conditions of Example 1. Accord- EXAMPLE 2 ing to the reference curve of FIGURE 2, this is equivalent to 11.5 lbs. of salt per 1000 barrels of oil. However Ten milliliters of a mid'continent crude oil, when dissolved in 90 milliliters of the xylene-alcohol solvent destandard of FIGURE 2 was based on a 10 l scribed in Example 1, gave a current reading of 7.4 00 sample so that the value of 11.5 must be multiplied by milliamperes when tested as described in Example 1. 1 Obtain indicated of From the reference, curve shown in FIGURE 2, this is 2 sat q arms f 9. A convenuonal equivalent to a salt content of 25 lbs. per 1,000 barrels fx gf g; ig of this crude "l a salt of oil. A salt content of 25 lbs. per 1,000 barrels of this k 2. pal-.1900 barrels of 11. oil was determined by a conventional extraction and 15 t e invention has been .descnbed abovqwlhh nation analysis. spect to certain preferred embodiments thereof, it will be EXAMPLE 3 uncciierstoiofril by those skillbed in the art that various changes H an mo 1 cations may e ma e without departing from Ten milliliters of a Canadian crude oil, the effluent the spirit and scope of the invention and all such changes from an electrical desalter, when dissolved in 90 milli- 70. and modifications are intended to be covered by the ap- [til-:61: otf thedxylene-zlghol slolvlent of Example 1 grader pended claims. Illustratively a second crude metering e es con itions o xamp e gave a tea ing 0 .38 pump and its associated parts can be em lo ed with the milliampere current flow across the electrodes. From apparatus in FIGS. 3-6 in order to dete i 'mi ne salt conthe curve of FIGURE 2, this is equivalent to 3.5 lbs. of tent of crude going into a desalter. Also, appropriate conduits and valves can be attached to conduit 34 to salt per 1,000 barrels of oil. A salt content of 4 lbs.

drain crude therefrom prior to thexanalysis cycle. inorder to obtain a more representativezsample of thexrude-in. line 26.

I claim:

1. A method for determining the amount of salt in hydrocarbon oil containing the same which comprisesmixing said oilwith a polar organicsolvent to form 'a -hornoges neous mixture, contacting the resulting mixture with; a.v

pair of spaced electrodes maintainedat-alternatingcurrent potential and measuring the.;fiow of.currente'hetweensaid electrodes.

2. The method for determining'the:amounttof' chloride.

i; (3) Correlating the flow of current. throughssaid solution of crude oil of unknown saltcontent. with the flow of current through the. solutions .oficrude oil.

- in a flowing stream of crudetunder pressurerfr'om a de salts in crude oil containing the" same:and=zsubstantial1y free of asphaltic material which comprises mixing said crude oil with a polar organic-solvent to formaehomoge neous single phase solution, contactingthe'resuiting solution with a pair of spacedelectrodes maintained at known 2 alternating current potential and measuring;v the: flow ofcurrent between said electrodes.

3. The method for determining. the" amount of saltin: crude oil containing the same and-which.contains'asphalticmaterial which comprises mixing a sample of .saidcrude oil with at least one polar organic solventsand at least one strong non-polar organic solvent to form a'ho'mogeneous solution, contacting the resulting; solution'with sapainof spaced electrodes maintained-at known alternatingccur rent potential and measuring the. flow of alternating'curp rent between said electrodes.

4. The method of claim 3 in which; thesalt iszpredominately a chloride, the polarand nompclar. organic; solvents is each present in amounts between 1"and..-100 times the amount of crude .oil. preseng'the-polart-organic solvent is a mixture of alkanols having from: 1"-to.6: car-'- bon atoms and wherein the crude is. mixed' withlthe non-x: polar organic solvent prior to contactwithz the 'polaror.

ganic solvent. 7

5. The method for' determiningthe amounti of chloride salts in crude oil containing the same and which contains: asphaltic material and has an API' gravity less than about. as measured by ASTM' Method.D287- which-comaprises mixing a predetermined quantity oflat'. least one:

strong non-polar organic solvent to form. alhomogeneous,

single phase solution containing less than'about 025 volumepercent water, said sample being mixedwitlrthenorupolarv organic solvent prior to mixing with thepolar'organicsolvent, contacting the resulting solution with a. pair. of spaced electrodes maintained at knownaltematingcurrent potential and measuring the flow. of. alternating cur-- rent between said electrodes asa measureof the concen tration of the chloride salt.

6. The method of claim 5 wherein the non polar. organic solvent is xylene and the polar organic-solventis a. mixture of methanol and n-butanol.

7. The method for analyzing a crude oil sample to 'determine the chloride salt content thereoflwhich comprises.

the following steps:

(l) Subjectingeach of a number of crude oil samples.

containing known amounts of salts .to an; analysis including the steps of:

(a) Mixing saidsample with between. about l and.

about 100 volumesof polar organic solventtand. between about 1 and about. '100 volumes; of... strong non-polar organic. solvent basedon; volume of crude oil to. form abomdgeneous solution;

(b) Contacting said solutiontwitlra pain-of spaced. electrodes maintained at known alternating'cur salter, said crude containing asphaltic material,-. having an A-PI gravity of less than about. 30. and containing less than: about 0.5% by volume of water, whichcomprises passing a portion of the crude stream through a conduit, increasing the pressure on thezcrude in:.said-.conduit. above that inrthe remaining stream of Icrude,zmetering 'a' predeterminedavolu'me of a crude sample intheJcQnduit, decreas-. ing thepressure on. the. sample. and passing it i'nto.a.sanr=- ple receiver," mixing apredeterminedvolumeof substantially anhydrous xylene with. the samplezin the-:samplereceiver xtoxform a homogeneousrmixture, the volume of xylene being. from about 2 to 6' timestgreater. than" the. volume of'crude; mixing a predetermined-ivolume.of a substantially anhydrous mixture of methanol and;.n-buta-. nol with the mixturexof crude. and xylenein the sample receiver to form a homogeneous liquid..lmixture.-. thereof,

thevolume of the-mixture of methanol andbutanolbeing from about 3 to 7 times the volumeof 'crudezandwherein' the-volume of methanolin' said: methanolrand: butanol mixture-is from about 0.3 to Zipartst of-methanol 'per part of-in-butanoL'contacting the mixture-. 'of f'crude, xylene, methanol .and n:-butanol with'apair. of-spacedf electrodes maintainedatalternating current potential, measuring the flowof alternating current between 1 the: electrodes. as a measure 1 of salt concentration; drawing the liquid mixture from the sample": receiver through a conduit,'.,increasing the. pressureof the liquid mixture above. thatin theflowing stream-of crude: and finally injecting. the; liquid. mixture into said; flowing stream. on. the downstream" side.-. from which. the crude sample was obtained;

9. Analysis apparatus for determining salt content of hydrocarbongoil flowing through a pipeline. at. elevated pressures. which'rcomprises' a sample receiver, means for meteringia sample of predetermined. volumeof said hydrocarbon into said'sample receiver, said. metering .means comprisinga metering pump, a: conduit having valved means therein for receiving oil at' high pressuresfrom the y metering and. mixingwith said. sample a predetermined volume of a diluent liquid, a pair of spaced electrodes adapted for immersion in said sample anddiluent mixture in. said sample receiver, means formeasuring, electrical conductivity ofsaid mixture between the spacedelectrodes and .means for draining the'mixtureof sample and diluent from said sample receiver.

10;.Apparatus for determining the amount ofasaltv in hydrocarbon oil containing the. same comprising; a positive; displacement. pump, first iconduitirneans and. a normally closed. valve for controlling the flow. of oil from a source. of: oil into the: pump inlet, a..sample;.receiver,.

second .conduit means for conducting. oil. from: the. pump outlet to saidsarnple receiver," a norniallyclosed pressure responsivevalve in. said second conduit means actuatable ata pressure above that in said first conduit to permit a predetermined. quantity of oil from'the.:-pump.: to how into said .sample receiver, firstmetering nreans.for'metering and .mixing a predetermined quantity of a first diluent for the oil inthe sample receiver, second metering means for metering and mixing a predetermined quantity of a second' diluentwith. the oil andifirst diluentin the sample receiver, a pair of. spaced electrodes irr saidi sample receiver adapted for'immersion in said oil, first diluent and second diluentmixture, meansformeasuring electrical conductivity of fluid. between saidelectrode's, and

ioned valve, pump, first diluent metering means, second liluent metering means,,electrodes and draining means ire each electrically connected to an automatic timer and irogrammer.

12. Automatic apparatus for use in intermittently malyzing liquid flowing through a pipeline at elevated n'essures comprising a first conduit having an inlet end ll'ldoutlet end adapted for connection to a pipeline at 'ongitudinaily spaced locations and for continuously by- :assing therethrougha portion of the streamof liquid lowing in such line, a reciprocatingpiston pump for netering a predetermined quantity of oil sampleya secind conduit having a solenoid valve therein communicatng with said first conduit and the pump inlet, a sample 'eceiver' having means for draining liquid contents there- 'rom, a third conduit having a pressure responsive valve herein communicating with the pump outlet and the ample receiver, said pressure responsive valve actuatible to permit liquid to flow from the pump to the ample receiverwhen the pressure in said third conduit j etween the, pump outlet and pressure responsive valve sgreater than the pressure in the pipeline, means'for netering and transferring a predetermined quantity of a irst liquid diluent into said sample receiver, means for netering and transferring a' predetermined quantity of I second liquid diluent to said sample receiver, a stirrer In said sample receiver and means for actuating said itirrer, a pair of spaced electrodes adapted to contact he liquid in said sample receiver, means for measuring :he electrical conductivity of liquid in said sample re- :eiver, program timer means operatively connected to :he pump, solenoid valve, sample receiver draining means, first diluent metering means, stirrer, second diluent metering-means and the means for measuring electrical conductivity of the liquid, said program timer having means for actuating the pump, solenoid valve,first diluent transfer means and stirrer before transfer of the second diluentin said sampler receiver, said timer having means for actuating the electrical conductivity measuring means after the oil, first diluent and second diluent have been mixed with the stirrer to form a homogeneous mixture, and wherein said .timer has means for actuating the sample receiver draining means at the end of each intermittent analysis.

13. The apparatus of claim 12 including means for injecting the liquid mixture into said first conduit downstream of said second conduit, said timer having means for actuating the injecting means after actuating the conductivity measuring means.

14. Apparatus according to claim 10, in which the means for draining the mixture from the sample receiver includes a positive displacement discharge pump, conduit means for conducting oil from the sample receiver to the discharge pump inlet, conduit means for conducting oil from the discharge pump outlet to the source of oil and a normally closed pressure responsive valve in the last mentioned conduit means actuatable at a pressure above that in said source.

References Cited by the Examiner UNITED STATES PATENTS 2,607,718 8/52 Suthard 324-30 X 2,765,219 10/56 Shawhan 3243O X 2,782,15 1 2/57 Suthard.

2,950,177 8/60 Brown et a1 32430 3,014,178 12/61 Dunn 324-30 FREDERICK M; STRADER, Primary Examiner.

Claims (2)

1. A METHOD OF DETERMINING THE AMOUNT OF SALT IN HYDROCARBON OIL CONTAINING THE SAME WHICH COMPRISES MIXING SAID OIL WITH A POLAR ORGANIC SOLVENT OT FORM A HOMOGENEOUS MIXTURE, CONTACTING THE RESULTING MIXTURE WITH A PAIR OF SPACED ELECTRODES MAINTAINED AT ALTERNATING CURRENT POTENTIAL AND MEASURING THE FLOW OF CURRENT BETWEEN SAID ELECTODES.

10. APPARATUS FOR DETERMINING THE AMOUNT OF SALT IN HYDROCARBON OIL CONTAINING THE SAME COMPRISING A POSITIVE DISPLACEMENT PUMP, FIRST CONDUIT MEANS AND A NORMALLY CLAOSE VALVE FOR CONTROLLING THE FLOW OF OIL FROM A SOURCE OF OIL INTO THE PUMP INLET, A SAMPLE RECEIVER, SECOND CONDUIT MEAN FOR CONDUCTING OIL FROM THE PUMP OUTLET TO SAID SAMPLE RECEIVER, A NORMALLY CLOSED PRESSURE RESPONSIVE VALVE IN SAID SECOND CONDUIT MEANS ACTUATABLE AT A PRESSURE ABOVE THAT IT SAID FIRST CONDUIT TO PERMIT A PREDETERMINED QUANTITY OF OIL FROM THE PUMP TO FLOW INTO SAID SAMPLE RECEIVER, FIRST METERING MEANS FOR METERING AND MIXING A PREDETERMINED QUANTITY OF A FIRST DILUENT FOR THE OIL IN THE SAMPLE RECEIVER, SECOND METERING MEANS FOR METERING AND MIXING A PREDETERMINED QUANTITY OF A SECOND DILUENT WITH THE OIL AND FIRST DILUENT IN THE SAMPLE RECEIVER, A PAIR OF ELECTRODES IN SAID SAMPLE RECEIVER ADAPTED FOR IMMERSION IN SAID OIL FIRST DILUENT AND SECOND DILUENT MIXTURE, MEANS FOR MEASURING ELECTRICAL CONDUCTIVITY OF FLUID BETWEEN SAID ELECTRODES, AND MEANS FOR DRAINING THE MIXTURE FROM SAID SAMPLE RECEIVER.

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