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Strategy of Refining A Petroleum Oil Containing Naphthenic Acids

Patented July 15, 1947 Process of REFINING A PETROLEUM OIL CONTAINING NAPHTHENIC ACIDS Mack C. Fuqua and John B. Lovell, Baton Rouge, La. assignors to straightforward Oil Development Company, a company of Delaware Utility September 20, 1944, Serial No. 555,026

12 Claims.

an acid-free oil layer and a solvent extract layer containing the salt of the naphthenic or different acids faraway from the oil, after which this extract layer is handled with an acidic fuel comparable to carbon dioxide so as to liberate the free organic acids, and so as to transform the organic base into the carbonate type. The freed acids are then readily separated from the solvent containing the natural base carbonate, and the carbon dioxide is readily driven off by distillation with a view to regenerate the organic base dissolvedin the solvent which may then be recycled.

Though the invention may be carried out by batch, if desired, it is preferable from a practical business point of view to operate by steady countercurrent solvent extraction, adopted by continuou remedy and separation in the various phases of the invention as mentioned above. v

Up to now, considerable work has been done in an’efiort to remove naphthenic acids from certain crudes, both for the recovery of the naphthenic acid and to free the variousdistillate cuts of the crude from acidic materials. The removing of these acids by alcoholic KOH or aqueous alkali, followed by acidification and extraction with a low-boiling distillate has not proved very profitable because of the formation of emulsions.

By the present invention, a very high percent of the overall naphthenic acid content material of the crude petroleum can be removed. Several advantages end result from this invention. One is that the considerably full removing of the naphthenic acids from the crude oil previous to any distillation permits the acquiring of acid-free distillates from the unique crude distillation with out the injection of any neutralizing substance, and prevents any corrosion or coking of furnace tubes during distillation. Another benefit is that the total naphthenic acids are obtained and these could then be separated by subsequent distillation into fractions of any desired boiling range; whereas if I the crude oil is first subjected to distillation previous to acid removal then every separate distillate should be subjected to acid elimination remedy if all the naphthenic acids are to be recovered and if every distillate is to be produced in an acidfree condition. A still additional advantage of this invention is that it permits regeneration of the organic base and recovery of the solvent, thus enabling the recycling of both of those brokers.

The invention may be applied to various types of crude oils comparable to parafiinic, naphthenic, asphaltic, or mixed base crude petroleum oils, though the invention is intended to use most significantly to crudes having a naturally excessive content of. naphthenic or other natural acids,

such as coastal crude, specifically White Castle,
Refugio, New Iberia, ,Webster, Friendsward, Thompson, Bayou Blue, Bayou Bouillon, Heavy Black Bayou, Charenton, Lake Washington, and

The canada natural gas price graph natural base for use needs to be one sufficiently basic to type natural salts with the naphthenic acids within the oil, and but ought to have good solubility traits in relation to the solvent or contact agent and when dissolved therein to the oil being handled. The watersoluble and alcohol-soluble amines represent an appropriate class of bases, and the amino-alcohols. or otherwise known as the hydroxyamines, are most well-liked. Good outcomes have been obtained with mono-ethanol amine, di-ethanol amine and triethanol amine. Different particular amines which can be utilized embrace: methyl amine, ethyl amine, n-

and isopropyl amine, n-butyl amine, sec-butyl amine, ter-butyl amine, propanol amine,isopropanol amine, butanol amine, sec-butanolamine, and ter-b’utanol amine.

The contact agent to be used must be an organicliquid able to appearing first as a mutual solvent for the amines and the naphthenic acid salts; and secondly, it have to be able to serving as solvent medium for the carbonate salts of the naphthenic acids resulting from the CO2 treatment, and but be sufficiently insoluble in naphthenic acids per se that itssolution with regenerated amine will separate readily from the liberated naphthenic acids. A suitable class of compounds for filling these necessities is the class of lower aliphatic alcohols. Isopropyl alcohol has been found particularly appropriate but others may be used comparable to ethyl alcohol, methyl alcohol, normal propyl alcohol, or even a few of the butyl alcohols. Different low molecular weight oxygen-containing organic solvents could also be used, equivalent to acetone, glycerin, methyl ethyl ketonc, ethylene glycol, Water-soluble esters, as ethyl alcohol.

Three acetate, ethyl propylate and isopropylate, or any water-soluble, oll–insoluble solvent.
The proportions of natural base and get in touch with agent in the solvent for use might, after all,

range inside pretty broad ranges relying upon the focus of acids within the crude oil being handled, and On the quantity of base used to extract the oil, and on the water-solventiextract) layer. This amount might finest be regulated by pH measurements. I

Though the separation of the liberated naphthenic acids from the solvent solution of hydroxyamino-carbonates often takes place readily upon settling, such separation could also be initiated if vital, or in any occasion accelerated, by cooling, or heating, by including extra solvent, or if necessary by including some precipitating solvent such as water.

The final step of heating the solvent resolution of hydroxyamino-carbonates to regenerate the hydroxyamine by liberation of carbon dioxide could also be carried out in an atypical tower nonetheless geared up with steam heating coils at appropriate elevations, so that regenerated solvent could also be withdrawn by gravity and liberated carbon dioxide given ofi at the top could also be recycled into the converter.

The invention can be better understood from a consideration of the connected drawing along side the following description which, without aspiring to limit the invention to the particular materials employed nor the exact gear used, will illustrate the applying of the invention to the steady countercurrent sol– vent extraction of a crude petroleum oil with mono-ethanol amine in the presence of isopropyl Referring, to the drawing, a crude petroleum oil is fed by way of inlet line I into extractor 2 in the decrease portion thereof and it rises countercurrently to a descending circulate of solvent getting into the higher portion of the tower through line’ 3. The solvent liquid flowing in line eight is composed of isopropyl alcohol which may be fed in by line 4, and ethanol amine which could also be fed in via line 5 along with recycle solvent flowing through line 6, as might be explained more absolutely later.

Because the oil rises via extractor 2 the naphthenic acids and other organic acids therein are step by step and substantially utterly removed in order that when the oil reaches the highest of the extractor it’s substantially acid-free and flows out through discharge line I, after which it could also be subjected to distillation or varied refining steps as desired, with out the necessity of including any corrosion-stopping agent. In the meantime, the solvent comprising isopropyl alcohol containing ethanol amine dissolved therein descends via the extractor 2 and removes the naphthenic and different acids by forming ethanol amine salts such as ethanol amine naphthenates, and so forth. which remain dissolved in the isopropyl a1- cohol so that this resulting extract is withdrawn four from the extractor by gravity by line eight and is passed into by way of line 9 into the upper portion of a converter l0 which may suitably be a vertical tower into which carbon dioxide is blown in near the bottom by means of line ll, any unabe sorbed gases being vented by line 12 at the top, from which they might or will not be recov ered and recycled, whereas the liquid section now consisting of a mixture of isopropyl alcohol containing ethanol amine carbonate dissolved therein and the oily liberated naphthenic acids which are insoluble in the alcohol resolution, is withdrawn by gravity from the bottom of the converter It by discharge line- I3 and passed by way of line I! into the separator 15 at or about the center.

thereof, whereby the lighter oily naphthenic acids separate and rise to kind an upper layer which is withdrawn by line It, whereas the alcohol answer of ethanol amine carbonate settles as a decrease layer and is withdrawn from the bottom of the separator l5 and handed through line I! into the nonetheless l8 which may be a vertical tower provided with suitable steam heating coils l9 or different appropriate heating means, to drive oi! carbon dioxide from the top of the nonetheless ll through line 20, for recycling if canada natural gas price graph desired through line 2|, while the residual isopropyl alcohol answer of regenerated ethanol amine is withdrawn by gravity from the underside of still l8 through discharge line 22 for recycling by way of lines 2’3,

. 6 and three into extractor 2.
Laboratory extraction of a coastal crude (White Castle) with a 1.30 neutralization number using 3% by quantity ‘of mono-ethanol amine in the presence of by quantity of isopropyl alcohol gave ninety four% removal of the naphthenic acid within the crude. Upon distillation of the amine-alcohol layer a seventy five% restoration of alcohol was obtained and a virtually complete restoration of the amine.

Subsequent extractions with varied concentrations of amines, and utilizing ethyl alcohol in addition to isopropyl alcohol as a contact agent, gave comparable naphthenic acid elimination.

It is understood of course that the naphthenic acid fraction recovered by this invention, as for example, by line It within the drawing, could also be subjected if desired to any further separating or purification steps, comparable to by distillation, additional extractions, or acid treating to offer desired purity.

It’s not supposed that this invention be limited to the specific supplies for equipment which have been recited merely for the sake of illustration, but solely by the appended claims wherein it is meant to assert all novelty inherent within the invention as well as all modifications coming throughout the scope and spirit of the invention.

It is claimed:
1. The means of refining” a crude petroleum oil which comprises subjecting it to continuous counter-current extraction with an answer consisting of an alkylol amine dissolved in a low molecular weight water-soluble oxygen-containing natural solvent to remove naphthenic acids considerably completely from stated crude oil, whereby stated crude oil is made considerably acidfree and substantially,non-corrosive during storage and subsequent distillation and refining treatments, separating the solvent extract now comprising solvent and dissolved therein allqlol amine salts of naphthenic acids along with any unreacted alkylolamine, treating mentioned solvent extract with carbon dioxide to convert said alkylolamine naphthenates into corresponding alkylolamine-carbonates and liberate free naphsesame thenic acids which are insoluble within the solvent solution of alkylolamine and carbonates thereof. separating stated liberated naphthenic acids from mentioned solvent solution containing alkylolaminecarbonates and heating stated resolution to drive off carbon dioxide from mentioned carbonates, thereby regenerating alkylolamine in solvent solution, and eventually recycling said alkylolamine in solvent resolution.

2. Process according to assert 1 through which the solvent is a decrease aliphatic alcohol.
a three. Course of according to claim 1 in which the alkylol amine incorporates 1 to three ethanol. groups.

Four. Course of in accordance to claim 1 wherein the solvent is chosen from the group consisting of isopropyl and ethyl alcohol and constitutes about 2% to 40% by volume based on the oil being handled.

5. Course of in accordance to say 1 by which the extraction is carried out at a temperature between F. and the decomposition temperature of the amine cleaning soap of the naphthenic acids.

6. The continuous means of refining crude petroleum’ oil which contains subjecting said oil prior to any distillation or different refining remedy to a continuous countercurrent extraction with about 20% by quantity of isopropyl alcohol and 3% by volume of mono-ethanol amine dissolved in mentioned alcohol, whereby the naphthenic acids current in said’crude oil are considerably fully removed therefrom and transformed into corresponding naphthenate salts of monoethanol amine dissolved in isopropyl alcohol, separating the resultant acid-free crude oil from the resultant solvent extract, treating the latter with carbon dioxide to transform the ethanol amine naphthenates into ethanol amine carbonate and thereby liberate free naphthenic acids as a liquid section insoluble in the isopropyl alcohol answer containing ethanol amine carbonate, separating said liberated naphthenic acids in a considerably pure form out there for business use and heating mentioned isopropyl alcohol resolution containing ethanol amine,carbonate to drive ofl. carbon dioxide and regenerate ethanol amine in resolution in isopropyl alcohol, and recycling mentioned solvent answer for use in further steady solvent extraction of recent crude oil.

7. In a strategy of refining a petroleum oil containing naphthenic acids, the steps which comprise contacting the oil with an answer consisting of a low molecular weight water-soluble oxygencontaining organic solvent having dissolved therein an organic water-soluble and alcoholsoluble amine that reacts with ‘the naphthenic acids to type naphthenates thereof, and separatsaid natural salts without decomposing the liberated organic acids, and recovering thus liberated natural acids from the acid-treated answer.

9. Process according to claim 7, by which the contacting of said oil with the amine within the presence of the oxygen-containing solvent is carried out in a vertically-elongated extraction zone by continuous countercurrent extraction, the oil being fed repeatedly into a decrease portion of the reaction zone and an answer’of the amine within the solvent being fed repeatedly into anupper portion of the extraction zone, whereas oil freed of natural acids is removed, repeatedly at the highest of the extraction zone and the resultant solution of the natural salts in the natural solvent is eliminated constantly at the underside of the extraction zone.

10. Process according to claim 7 in which the petroleum oil is a crude oil containing organic acids including naphthenic acids.

Eleven. Process in accordance to claim ‘1 through which the amine is an alkylol amine and the mutual solvent is a decrease aliphatic alcohol that is water-soluble.

12. In the process of refining petroleum oil containing natural acid, the steps which consist in contacting the oil with an aliphatic watersoluble and alcohol-soluble amine having primary properties to kind an natural salt thereof with the natural acid within the presence of a low molecular weight water-soluble oxygen-containing mutual organic solvent for the amine, the natural salt and carbonate salt of the amine, separating aresulting answer of the organic salt in mentioned solvent from the oil, treating the separated solution ing from the oil resulting naphthenates andunreacted natural amine dissolved in the natural solvent which remains undissolved in the oil to leave the oil freed of naphthenic acids.

8. Course of according to claim 7, adopted by treating the separated resultant resolution with carbon dioxide which liberates natural acids from with carbon dioxide to liberate organic acid from said salt and to convert the amine to’a carbonate salt, separating the liberated organic acid from the thus-treated resolution of the carbonate salt within the solvent, heating the solution of the carbonate salt to decompose stated carbonate salt and drive of! carbon dioxide gasoline whereby the amine is regenerated and reusing the regenerated amine in resolution within the solvent in refining petroleum oil.