US2487103A - Production of fuel oils from acid sludge - Google Patents

Description

Nov. 8, 1949 J. H. CONE Er AL 2,487,103

PRODUCTION OF FUEL OILS FROM ACID SLUDGE Filed Sept. 18, 1947 SALT WATER I8 22 NoOH SOLUTION l5 HEATER FRESH WATER 23 24 l3 HYDROLYZER A ll 26 AC") SETTLER/\ i SLUDGE 5:3

ACID LAYER SALT WATER FUEL on. 30

Q71! INVENTOR.

ATTORNEYv saleable products.

Patented New. 8, 1949 PRODUCTION OF FUEL OILS FROM ACID SLUDGE John H. Cone, Polly, and Roy V. Comeaux, Baytown, Tex., assignors, by mesne assignments, to Standard Oil Development Company, Elizabeth, N. J a corporation of Delaware Application September 18, 1947, Serial No. 774,734

4 Claims. (Cl. 196-148) The present invention is directed to a method of producing fuel oils. More particularly, it is directed to a method for treating acid sludges for recoveryof hydrocarbon constituents therefrom which are usable as fuel oils.

In the refining of petroleum, quantities of sulfuric acid are employed to treat naphtha, kerosene, gas oil, and lubricating fractions to produce Sulfuric acid treating in the petroleum refinery is largely confined to the treatment of heavy naphthas and lubricating oil fractions. As a result of these treating operations, large quantities of acid sludge accumulate which must be economically processed to recover the valuable sulfuric acid constituents therein and also the enormous quantities of hydrocarbon constituents contained in the acid sludge by chemical reaction or by mechanical entrainment. It is customary practice to hydrolyze acid sludges to recover the sulfuric acid constituents and separate a hydrocarbon phase which may be used as fuel oil. The hydrocarbon phase which is separated from the acid layer in the hydrolysis of acid sludges is quite acidic in nature and contains appreciable quantities of ashy constituents. Before the acid oil may be used as a commercial fuel oil, it is usually necessary to neutralize the acidic constituents by contacting the acid oil with an alkaline solution such as sodium hydroxide. simple as it appears for the acid oil contains sulfonated bodies which, on reaction with the sodium hydroxide, form salts which are good emulsifying :agents. Indeed, the treatment of acid oil with sodium hydroxide is often so diflicult that the However, this operation is not quite as :acid oil or the unhydrolyzed sludge may be burned in the refinery itself as a low grade fuel. This is disadvantageous in that the acidic constituents may attack the burners and the furnaces in which the fuel is consumed, leading to rapid deterioration of this equipment.

Acid sludges obtained from treatment of heavy petroleum fractions for production of lubricating oils are ordinarily hydrolyzed for recovery of a weak sulfuric acid layer and a more viscous hylayer.

2 Washing the acid fuel with fresh water effects a substantial reduction in ash-forming constituents present in the fuel but the success of this operation is dependent upon close control of by.- drogen-ion concentration of the spent wash water. When the pH of the spent wash water is maintained Within the range 0.3 to 0.9 goodseparation of water from oil results and about '75 per cent of the water soluble ash is removed-from the fuel. If the pH of the fresh water (spent wash) is decreased below the minimum shown, ash reduction is impaired and when the pH is raised above about 1-.0, water-oil emulsions result. It has been found that when Wash water containing in solution sodium chloride in amounts in the range from about 1000 to 5000 parts per million of alkali metal chlorides is employed the efficiency of removal of ash forming constituents is not impaired and close control of hydrogen-ion concentration is not imperative. For example, we have successfully washed with salt water, fuels from which the spent wash waters had pH values ranging from 0.3 to 10.6. The. overall loss of hydrocarbon in the water layer is decreased by washing with salt water since the lower surface tension water (salt water) tends to decrease mechanical hangup of oil globules in the Water The solution of water. soluble ash in the Water layer is substantially equal for fresh and salt water so long as salt concentration of the salt water is controlled within the limits specified.

It is, therefore, the main object of the present invention to provide a process in which commercial grade fuel oils of low ash content may be produced without the formation of emulsions during the treating operation.

Another object of the present invention is to treat acid oils recovered from acid sludges to remove emulsifiable constituents therefrom.

A still further. object of the present invention is to provide a process for recovery of a commercial fuel from an acid solution-resulting from the acid treating of petroleum hydrocarbons.

The objects of the present invention may be achieved by hydrolyzing an acid sludge with fresh water to obtain an acid layer andan oil layer, the oil layer being subjectcd'to' a washing operation with an alkali metal halide brine following which the brine washed oil is treated with a strong aqueous alkaline solution to neutralize the residual acid constituents therefrom. v

Briefly, the present-invention may be.described as involving the hydrolysis of an acid sludge with fresh water, the separation of an aqueous phase H9 14 an oi phase, the spf the 011 has with strong sulfuric acid is hydrolyzed with fresh. To the mixture undergoing. hydrolysis. may be added a chemical demulsifying agent, such water.

as for example, a sodium salt of petroleum sulfonic acids. However, the addition of. the demulsifying agent is optional and" may lie-dispersed with. It may be mentioned that sodium sulfonates act both as demulsifying and emulsifying agents under particular conditions. Thezmixture.

of fresh water and the acid sludge is then heated to a temperature in the range from about 100 to 200 F., following which the mixture is allowed tosettle into two phases, an oil phase, and an aqueous phase-which will include" the hydrolyzed sulfuric acid constituents: The oil phase may have a specific gravity in the range from 0.88 to about 0.92 and will have an acidity corresponding to about 1 to pounds of sodium hydroxide for everybarrel of oil layerseparated from the acid" layer. This acid oil is then washed with about 25'to- 100 volume percent of a brine solution, including sodium chloride, in the range from about 1000 toabout 5000-P. P; M. of the brine. The washed acid oillayer may then be heated to' facilitate the separation and to settle the salt water separated from the oil. The oil may then be conveniently' neutralized with an aqueous sodiumhydroxide solution andthe resutling product may be used as av commercial grade fuel. The' sodium hydroxidesolution employed in neutralizing the=residual acidity of the oil may have a: Baum gravity in the rangefrom about 40 toabout 50 Be; although stronger solutions may be used satisfactorilyi Thepresent invention will be-further'ill'ustrated by reference to the drawing in which the sole figure presents a: preferred mo'de'of' carrying out the invention. 7

Referring now to the drawing, numeral ll designates a charge line through which an acid sludge; resulting" from the treatment with sulfuricacid of a lubricatingoil distillate in a propane solution, charged to the system. It is customary-- to flux" suchsludges with a heavy naphtha fractionto reduce the viscosity and to improve the mobility of the sludges for ease of pumping. It willbe assumed for purposes of illustration that the acid sludge" introduced by line H is: such a sludge to which has been added a suitable flux: To theacid sludge in line H may be added" a sufficient amount of water by way of line I 2 to cause hydrolysis of the acid in the acid sludge; The mixture of acid sludge and water' in line- H then discharges into a hydrolyzer |3'- which is equipped with a heating coil orother'heating means? M to allow the raising of" the temperature of the mixture in hydrolyzer l-3- to as temperature in the range from about 140 to 200 F. Gpt'ibnally; the hydrolysis and. the heating operation maybe conducted by adding open steam by" means not shown to the hydrolyzervessel; l'*3 Hydrolyzer vessel I31 is also provided with a. line I5 controlled by valve- 16 by way" of which: a. chemical demulsifying agent maybe added to assist in the separation between the acid oil.- layer and acid layer which forms in hydrolyzer l3a There are many chemical de- 4 mulsifying agents on the market and any one of these suitable for use in acid conditions may be employed. This particular step does not form a part of our invention; therefore, further mention of a chemical demulsifying agent will not be made. In; any event; the employment of a chemical demulsifying agentis optional since acid sludges usually contain sulfonic acid constituents which are both emulsifying and demulsifying agents, andunder most conditions it will be unnecessary to add sucha material by way of line l5.

With the adjustment of temperatures and pressures inhydrolyzen'vessel l3, a phase separation occurs and an acid oil layer and an acid layer are formed. The acid layer may be discharged from the hydrolyzer vessel [3 by way of line H: and further treated, concentrated and. refortified for reuse in treating petroleum oils. The acid-oil layer is withdrawn from the hydrolyzer vessel l3 by way of line It and has admixed with it by way of line l9: a brine of: sodium chloride having a. concentration in the range between 1000 and. 5000 P. P. M. The amount-of: saltwater employed will usually include. from. about 025 volume to 1.0 volume of saltwater toevery volume of acid oil withdrawn by." line I8 from hydrolyzer vessel I3. The admixture of salt water and acid oil. flows into. an incorporator or other mixing device 20 where intimate 1 admixture between the salt water brine andrthe acidoiloccurs.

Leaving incorporator 20; the admixture flows through line 2| through a heater 22 wherethe temperature of the admixture is raisedto a temperature in the rangebetween 125." F. and 200 F. The heated: mixture then. discharges by way of line 23 into-a settler-24 whichis of sufficient capacity to allowa residence time to lcause phase separation between the oil layergand the-salt water: introduced by line l9- The two: layers, the-oil layerand the salt water'layer, in settler 24 are allowed to separate and the salt Water is discharged from the system by way of line 25 while the oil layer, withdrawn by line 26, has; admixed with" it a strong sodium hydroxide solution introduced: by line. 21, and: then discharges' into incorporat'or' on similar mixing device 28 where contact with the sodium hydroxide solution occurs toallowneutralization of acidic constituents remaining in the acid oil produced in hydrolyzer 13. The amount of sodium hydroxide employed should be just sufficient to neutralize any residual acidity not re moved by the brine wash.

blown with air or heated and blown with. air

by means not shown to remove excess moisture. In practicing the invention as. illustrated in conjunction with. the drawing, no emulsification difficulties are encountered and. the fuel. oil is of satisfactory low ash content.

The invention will be further illustratedv by thefollowing examples? EXAMPLE. 1.

Five hundred: barrels of an acid oil obtained by hydrolysis of an acid sludge resulting from treating a petroleum fraction with strong sulfuric acid had added to it an amount of hot fresh water equivalent to '70 volume penoent of the oil. This hot water was intimately admixed with the acid oil in an incorporator and sufficient sodium chloride brine, in an amount to increase the salt content of the wash water to 1500 P. P. M., was added to the mixture. The admixture was transferred into a settling drum and allowed to separate. As soon as 100 barrels of the fuel oil-salt water mixture had been transferred into the settling drum, withdrawal of water was started and continued throughout the remainder of the run. The rate of withdrawal of water was only slightly less than the rate of addition of :water to the incoming fuel oil. One hour after the transfer of the oil to the settling drum had been started, all of the wash water had been withdrawn. No emulsion difficulties were encountered and acid removal averaged 70%. The brine washed fuel was then neutralized with a sodium hydroxide solution; the neutralized solution was then blown with air to remove residual moisture. The total elapsed time for the washing and withdrawal of water during this run was two hours and fortyfive minutes.

The original fuel washed with the salt water. had a gravity of 20 A. P. I. and a neutralization value expressed as pounds of sodium hydroxide per barrel of oil of 1.74. This fuel without washing with salt water had an average total ash content of 1.05% and a water soluble ash content of approximately 1%. The acid oil contained approximately 1.7% of water.

After the salt water wash and after the oil had been neutralized with sodium hydroxide, the gravity of the oil was found to be 21.3 A. P. I. while the neutralization value in pounds of sodium hydroxide per barrel'of oil was 0.59.

memos 6 water increased from 1500 P. P. M. to 1687 and varied thereafter to 1994, 1177, and 1381 P. P. M., with a final chloride content of 1738 P. P. M. at the finish of the run.

It will be apparent from the foregoing run that the gravity of the salt water washed and caustic neutralized fuel has been appreciably increased over that of the original acid oil. be further apparent that the total ash and water soluble ash content has been reduced appreciably by the salt water washing and increased only slightly by reaction of the acid constituents with sodium hydroxide. It is also apparent that the salt water wash removes appreciable amounts of acidic constituents from the acid oil in view of the neutralization values of the withdrawn salt water.

EXAMPLE 2 A number of runs were made in which acid oil was agitated with both sodium chloride brine and fresh water. The acid oil and the wash Water were heated in separate containers at temperatures in the range of 180 to 195 F., the acid oil being agitated with 50-100 volume percent of the washing medium. With fresh water, the

acid oil was shaken for one minute to give best removal of acid and separation of emulsion. For salt water, the agitation time was not critical. After formation of the fuel-water emulsion, the containers were maintained at 180 to 195 F. and water was withdrawn at intervals of 3, 5, 10, and 20 minutes, or until the total wash water was withdrawn. The criterion for satisfactory separation was arbitrarily set at 90% in 10 minutes. After removal of the water, the fuel layer was tested for acidity to phenolphthalein and then neutralized with 52 B. aqueous sodium hydroxide solution and tested for per cents ash, water soluble ash, and water. runs are given in the following table:

TABLE I rigiml Separation Per Cent after Washed NaOH AF u el Water Wash Minutes Wash Neutralized Fuel fittfi gg Required, Vol. Ash WS Ash Lbs./Bbl. Per Cent Type 3 5 Per Cent Per Cent E20 2.45 1.20 0.90 2.1 2. 45 75 FY6511 40 104 111 0. 85 0. 37 0. 35 3. 7 2. 100 do 0. 5 1. 5 7. 0 118 0. 90 0. 34 0. 28 4. 0 2. 45 75 S811; 1 42 65 98 99 0. 85 35 0. 34 2. 3 2. 45 100 (10. 60 83 102 103 0. 93 0. 38 0. 11 3.2 2. 45 100 (10. 100 101 10. 6 0,..24 0 24 6. 0 1.06 0. 68 0242 1.0 1. 05 Fresh 1 56 90 0. 89 0. 25 0; 21 1. 0 1. 06 7'5 (10 0. 7 2. 7 76 93 1. 00 0. 33 0. 22 1. 0 1. 06 100 (10 4 7 15 32 1. 06 0. 29 0. 28 1. 6 1. 06 50 SE15 1 K 13 39 87 100 0, 94 0. 32 0. 30 3. 4 1. 06 75 ('10. 30 52 88 103 12 03 0. 28 0. 28 1. 4 1. 05 100 (10. 40 94 101 1. 26 0. 27 0. 25 1.5 1.50 0.67 0.63 1.8 1. 50 75 Fresh 0. 6 1. 3 3. 3 6, 5 1. 29 0. 25 0. 26 0. 9 1. 50 75 Salt 1 78 90 100 102 1. 28 0. 26 0. 25 3. 0

. 1 Water containing 1640 P. P. M. chlorides.

2 100+ per cent theoretical caustic added to original wash water.

The total ash content was. 0.34% and the water soluble ash content 0.28%. The water content of the oil was 1.2%.

Analysis of the salt water separated from the oil after the washing operation showed it to have a neutralization value in pounds of sodium hydroxide per barrel ranging from 8.5 at the outset down to 2.13 at the finish of the run with the remainder of the values being intermediate the two. After the first hour, the neutralization value had dropped to 3.75 and declined there- It will be apparent from the foregoing data that the salt water allowed separation of more water in a shorter time than the fresh water. It will also be apparent that after the separated oil had been neutralized with sodium hydroxide the ash content of the salt water washed oil was not appreciably greater than that which had been washed with fresh water. Attention is directed to the pH of the wash water when fresh water was employed. It will be noted that when the-pH was controlled below about 0.9, separa after to 2.13. The chloride content of the salt tion of water from the acid oil was realized in a It will The results from these aemea ery sher sane ime, he ev r he the all aheve abo t 0-9, the se r on a e amed and when, it ab ut 1, p a all negligible separation was realized. On the other hand the 9H, 92 e br ne a pe to b immaterial; sinc seed sepa ation as ob i e e hen he PH as a high. as n as low a 0.85.

EXAMPLE 3 The results of these comparative runs are shown r 'm following table:

TAB E I Water washingof acid fuel oil ljype of Salt in Wash Water NaCl CaClz Amount of Wash Water, Yolume Percent of Oil.. 75 75 Cl .Goncentration of Wash Water, P. P. M 1, 640 1,- 640 $53 933? Wa e Se arat d, R c t of Total 3 minutes 35. 5 0 5 minutes 57. 2 0 minutes 92. 2 1. 3 minutes 100.0 6. 5 minutes 20. 6 60 minutes 98. 0

Oil in v ra e ed Wash a er Perce 2- 0 0 of Recovered Wash Water 0.75 0.72 pections on Washed Fuel:

Neutralization Value (Mg-NaQH/cc. Fuel) 1 1 49 3 1.81 hsp c e s eui ehzl sl Fi t Total Ash, "Percent 0. 25 0. 41 Water Soluble Ash, Percent- 0. 24 0.519 er Com it Perce t: 4 3

1 Acid oil required 2.45 pounds NaOH per barrel of oil to neutralize to the phenolphthalein end point. i

2 Equivalent to 0.545 pound NaOH/Bbl. he ii eleht 1 9 9-64? were NeQh l- It Will be apparent from the foregoing data that the calcium chloride brine is ineffective in allowing separation from the acid oil after 20 minutes time, and only after 60 minutes had elapsed did complete separation result with the oil washed with the calcium chloride brine whereas the separation was complete with the oil washed with sodium chloride brine after twenty minutes. It will thus be seen that, if calcium chloride brine is employed, the settling time will be three t mes, longer than when employing sodium chloride brine as the washing medium. Even though longer settling times were required for the calcium chloride, it will be further apparent that the oil after washing with calcium chloride had a higher neutralization value than the sodium chloride brine washed oil, indicating that more sodium hydroxide would be needed to cause neutralization of the calcium chloride washed oil. Furthermore, the ash contents Of the calcium chloride washed oil were appreciably greater than the a onten o he sod um chloride ri e w sh d o lsh e on a be n illustrated b e am les n. thi h. ash; ils separated. t a acid slud es,-

hee washed with. when. q hr Whi ther tr a e a e ch qriq 1s are, unsuita le in. whi h t cone: 9 I alk li meta ride; for sim le, ri s of p tass u hl ride and hium. hhl i ay h em e e n e d of Qdium h The ature hen ha in 1o m s at Pr sent ih ne ,Pletely descri ed and l sha ed. what, w. t cla m, as ne and metal ahdtofseqh Y t hateht s;

A math resiu he inc 1 from ac d. slud e ulting hem the tre tment. e et e m it sul uric. whi h ompri es h m vz h acid sludg at a tem era ure in th ran bee .2 00: to bta h an acid- 11 mm the eszitl 11 a dium hydr x de 01.

25 2. A me d for pr ducing el oil om an ac d-Q11, ebtained b mamma s a ac slud esultin here the. treatmeht. q petrol u with sulfuric'acid at a temperature in the range be; tw en 1.0 aha which comprises wash said eeisl-oil e ri e 9i. an alkal me a f r roducin a ee 1. rom t f m e h d qlvsis. a a em: w en. 10!! and 200 E. 9i an sing Q hr atmen p hole hh wi h suliur c arid com s sh his sa d ac h. a sodium e le de brine h v ng a ehesh a on or d n the a e be ween 090 pars he H!!! 5.9 ar s per million, separating the brine from the acid-oil and neutralizing the acid oil with a sodium hyshezside solution.

4. A method for pro dueing fuel oil which comprises hydrolyzing n acid sludge, obtained by treatment of a lubricating oil distillate with sulfuric acid, at a temperature in the range between 100 and 200 F. to form an oil layer and an aqueous layer, separating said oil layer from said aqueous layer, washing the oil layer with a sodium chloride brine having a concentration of chloride. in the range between 1000 parts and 5000 parts per million, separating the brine from the washed oil, and neutralizing the washed oil with a sodium hydroxide-solution.

' JOHN H. CONE.

ROY V. COMEAUX.

eieif' e' h. -e perature in the. range be REFEmEfNCES CITED UNITED STATES PATENTS

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