US2380294A - Method of treating and blending heating oils - Google Patents

Description

:July 10, 1945- A. Q. cATo Erm.

METHOD 0F TREATING AND BLENDING HEATING OILS Filed Feb. 12, 1944 ing' installations.

ling and "doctor swee/tening operations.

economy of equipment it is always good practice Patented July 10, 1945 METHOD oF TREATING AND BLENDING HEATING olLs r Y yilirtie Q. Cato,V Houston, George Wash, Goose Creek, and Albert J. Shmdl, Houston, Tex., assigners to Standard Oil Development Company, a corporation of Delaware l Application February 12, 1944, Serial No. 522,124,"

s claims. (ci. 19e-'33) in color when subjectedto the conventional iin-l ishing operation which includes treatment with The present inventionV is'- concerned with a method for handling oils employed in home heat- More particularly, it relates to`a method for treating petroleum heating oil fractions whereby oils of good color stability andproduct quality are obtained.v

' Heating oils asmentioned herein will be taken to include petroleum oil fractions boiling up to about 660 F. and having a gravity of at least 30 A. P. I. The oil shouldv be of'at least 10 color as measured by the Tag-ltobiiison color machine and yshould have a flash point between about 130 and 190, F.' Of course,-it must be realized that the oil should not corrode or plug the burning equipmentv and this tendency is usually reflected 4by an oil either passing or not passing the suspended sediment andr copper'strip corrosion tests.

The conventional treating methods forheating oil fractions in the petroleum refinery usually include distillation, acid treating, caustic wash- For to combine the treating operations suchzthat oils -from various sources are handled in one system are suitable for use as fuel for heating systems;

Heretofore heating oil fractions were vobtained from thermally cracked products and from crude petroleum. These fractions as mentioned before are amenable to finishing operations which may include acid treatment, caustic washing, doctor sweetening, and finally filtration. However, with the Vadvent of catalytic cracking' entirelyl new handling procedures were necessary fsince it was yfound that the conventional methods were not applicable to heating oil fractions from catalytically cracked hydrocarbons. 'For example,

when a catalytioally cracked heating-oil vfraction is admixed with heating oil fractions from thermally cracked products and crude petroleum, the admixture of the oils'is seriously impaired a strong alkaline reagent.

. lIt istherefore, the main object of the present-` invention to provide a ltreating and blending procedure for obtaining a heating voiliofpgood quality vwhich includes-heating oil rcomponents from: crude petroleum, j thermally cracked vnaphtha Vand catalytically cracked naphtha` In one specific yembodiment ofthe present invention heating oil fractions, i. e., fractions boiling between about 350 and 700 F, are segregated from crude petroleum, and mixed with the heating oil fractionvfrom a thermal cracking operation after the heatingpoil fraction-,from the tlcer-r mal cracking operation has undergone acid treatment, caustic neutral'mation rand rerunning to segregate from theracid-treated product a fraction similar in boiling range, to thatobtained from the distillation of4 the crude petroleum. The combined streamsvare then treated with an alkaline -solution,- and after removal of the alkaline solutionl from the'treated oil, the oil is then doctor sweetened as in conventional practices-Following the doctor sweetening operation the resulting alkali treated and sweetened oil is combined Vwith .a heating .oil fraction from a catalytic cracking operation'. 4It is preferred to passthe mixture through a yfilter containing. an adsorbent materiahsuch 'as fullers earth and rthe like, as a nal finishing stepfto insure the removal of foreign bodies, which maybe carried by the oil from the previous treating steps.'

While thev final filtering 'step is essential for the oils whichhave undergone treatment .with an alkaline reagent, andis desirable in some instances'for the oil from" the catalytic cracking f operatiomit is possible to omit the ltering step forl the oil from the, catalytic cracking operation andjcon'ibine this fraction withthe ltered oilsand obtain astable heating 'oil of commercial grade.

ence of alkaline reagents react with the oleflnic [If the, fuel oil fraction from the catalytic cracking stephad been -admixed `with the otherv two k streamsandv the jblend contacted with the alkaline solution', a vproduct of greatly inferior quality would have beenobtained. The reason for the unexpected result of the present inventionis not completely understood, but it is believed that in theheating oil lfractions obtained `from crudepetroleum there are present certain naphthenic type compounds, which in the presand aromatic constituents in the heating oil fraction from the 'catalytically cracked product.

that catalytic cracking causes the formation -ofr certainv types of hydrocarbons in appreciably larger quantities than heretofore have been obtained in thermal cracking'operations. These types of hydrocarbon compounds include, among others, the cyclo-oleiinic hydrocarbons which are quite reactive; furthermore, the catalytically cracked materials contain 'appreciable quantities of hydrocarbons of branch structure which are. known tobe more reactive than those consisting essentially Yof straight chains. It isbelieved that these large quantities of cyclo-olenic compounds and hydrocarbons of branch 1structure yenter into reaction with other types of compounds quite readily and even more readily yin the presence of an alkaline material such as used in conventional treating operations in the modern refinery. It is to be understood that the foregoing hypothesis is given only by way of explanation for the unusual result of the present invention, and not as a restriction or 'limitation on the scope ofthe invention. v v

The present invention will be further illusltrated by reference to the drawing in which the single figure isa flow diagram of a preferred method of conducting the invention. Referring now to the drawing, numeral Il designates a feed line through which a hydrocarbon in the gas oil boiling range is introduced into catalytic cracking unit I2. Catalytic cracking unit I2 may be a cracking operation such as the socalled Thermofo'r cracking operation, or a fixed bed catalytic cracking operation, Vor a "vfluid `catalyst cracking operation. These several catalytic cracking operations 'have been described elsewhere'in the patent lliterature and further reference thereto lneed not be vmade here. The product issuing from catalytic cracking unit I2 is conducted therefrom by way of line I3 and discharges into a fractionation zone I4. Fractionation zone I4 is provided with linel I5 lfor removingv an overhead fraction boiling below 420 F., with line 16 for removalof a heavy gas yoil fraction boiling above 600 F. and with line I1 lfor the discharge of oil containing small amounts of catalyst when the catalytic cracking operation is of `the fluid catalyst type. f n

A fraction having heating oil characteristics discharges from fractionation Zone I4 by way of line I8 and may be introduced thereby intoua treating system I9. Treating system I9 may include acid treating, caustic washing, ordoctor sweetening operations, or .all of them. When treating system .l 9 includes .an acid treating step, it must also include a rernnning .step for removal of polymers resulting from the lacid treating operation. In ,a preferred operation, however, treating system EIii-is by-passed by closing ,olf valve in line I8 and opening valve 2I in branch line 22, `thereby -by-passing treating system I9 completely. Inl the cases where treating 4system vI9 is by-passed, it will beunderstood that valve 23 .in line 24 will also be closed off. The heating oil fraction from the catalytic cracking unit routed through line 22 is then further handled,

'as will be described hereinafter.

Operating iny parallel with catalytic cracking unit I2 is a thermal cracking unit 25 into which a gas oil fraction is introduced by way of line 26. The conditions for the satisfactory operation of a thermal' cracking unit have 'been disclosed in detail in the patent literature and Will not be repeated here. The thermally cracked product lissuing from thermal cracking unit 25 discharges by way of line 21 into fractionation Zone 28, which is provided with a line 29 for removal of material boiling below about 400 F. and line 30 for discharge of material Vboiling above about "700 F. .Fractionation zone 28' is also provided with .line 3l through which a heating oil fraction discharges into treating system. 32. Treating system 32 in this particular instance includes an acid treating system for removal of unstable hydrocarbons from the lthermally cracked heating `oil fraction. Line T8 serves as a means for injecting sulfuric acid into treating system 32,

and line 9 as a `means for withdrawing acid sludge treating system 32 discharges by Way of line 33 into fractionation Zone 34 which is provided with line 35 for removal of constituents boiling below aboutl '400't0 420 F., line 36 for removal of a heavy gas oil fraction and line 3l for discharge of polymerized material resulting from the acid treating operation. The heating oil fraction discharges from fractionation zone 34 by way of line A38 and is admixed with a heating oil fraction introduced into line 38 by way of line 39 and obtained in a manner to be described.

The heating oil fraction in line 39 is lobtained by charging a crude petroleum from crude oil storage tank 40 by Way of line 4| and pump 42 into fractionation Zone 43. From fractionation Zone 43, a light fraction boiling below yabout 400 to 420 F. is removed by line '44, and va fraction boiling above the 'heating -oil boiling range is removed by line `while the heating oil fraction is withdrawn by line 39,

The mixture of thermally cracked and vnatural heating 4oils is conducted by line 38 and is admixed with 'an alkaline solution, introduced Aby Way of line 46, in incorporator 41 and passed thence by lway of line 48 into settler 49. Alkaline solution is withdrawn from settler 49 by way of 'line 50. This solution may be recycled by lines 5| and 46 to line 38. From time to time -it will become necessary to discard a portion of the alkaline reagent discharged from settler 49 by Way of line 50. This is accomplished by opening valve 52. In a similar manner fresh alkaline reagent is introduced by line 46 'by opening valve 53 therein.

The alkaline treated mixture of thermally cracked and natural heating oils discharges from settler-49 by. way of line 54, has doctor reagent added thereto by line and passes through incorporator 56 and line 5l into settler 58 which allows gravity separation between the hydrocarbon phase and the doctorreagent phase. The doctor reagent phase may be withdrawn by line 59 and recycled to line 54 by way of line 55. As required, :from time to time, fresh doctor reagent may be introduced into the system by opening valve 60 in line 55. Spent doctor reagent may be discarded intermittently to maintain the solution at an optimum .strength by opening valve 6I in line 6.2.

In conjunction with the doctor sweetening operation described in connection with incorporator 56 and settler 58 it is usual practice to include ldoctor sweetenedV oil. i fplished by contacting the doctor treated hydrokically cracked fraction 'line 68. The filtering step removes foreign bod'- 30` -alkaline sulfide andwater washes to remove oc- .subjected to' treatement'with sulfuric acid and eluded or suspended lead compounds 'from the y'I'his is usually accomcarbons with a spent caustic solution which usu- `ally`c0ntains sodium polysulfide'compounds and is usually followed by washing with water. The hydrocarbons issuinggfro'my settler 58 by way of line 63 admix with the catalytically cracked *heating oil fraction from line 2| f and commingle inline 64 and are introduced` thereby into filter `65. `As mentioned before, filter 65 is packed with an vadsorbent material' such as Fullers earth,

kieselguhr, bauxite, orother similar adsorbents 'wellknown to the art.l The filtered oil discharges from 'filter 65 by way of' line 66 and is then sutable for use in heating oil systems.

The nal filtering step isdesirable for the production of a high grade heating oil but for yoperability of the process it is not essential that the fcatalytically cracked heating'oil fraction from line 2| be passed through Vthe fllter'. If itis desired to omit the filtration of the catalytically cracked fraction, valve 2| `in line y22 is closed and Valve 61 in line ppened allowing this fraction to by-pass filter 65 and the filtered mixture of the thermally cracked fraction and the crude fraction commingle in line 66 with the catalytintroduced thereto by reruny to proper distillation characteristics. This rerun material was then blendedwith a heating oil fraction from a crude petroleum, and similar tothe first run,- Iwas treated with 40 B. caustic 'followed by doctorl sweetening, sodium polysulfide and water washing, and filtration. This r,material was also tested to determine its characteristics. In a third operationan acid treated and 'rerun heating oil from the same thermally` cracked operation as runsone and two-was admixed with 'mixture then caustic washed, `doctor sweetened,

sodium polysulfidewashed and water washed. To this treated admixturewas addedv a heating oil fraction from a catalytic c'rackingoperationv and y the resultant composition was thenfiltered. This fourth vrun is the preferred embodiment ofthe present invention. f

The comparison ofthe tests obtained on the vmaterials resulting .from the four runs.' is presented in the following table:

TableI y e .After treatment with 409 B. sodium hydroxide doctor sweetening, sodium poly- After 40 B6. sodium hydroxide treatment,

sulfide Washing, water washing and filtering Odor test (nasal) l 175 ml. of the oil to be tested is measured into a dryfi ounc 212 F. The sample bottle is then'removed from the oven, the sample then determined and reported es the color hold.

ies from the oils suclias sodium salts of naphthenic acids produced in prior treatment with an alkaline reagent and when a component of the heating oil of the present invention is not treated with an alkaline reagent the filtration step, so far as that particular oil is concerned,

ted.

In order to illustrate further the beneficial effects obtained by processing heating oil fractions in accordance with the present invention, several runs were made in which heating oil fractions, from thethree sources mentioned before in the specification, were subjected to Various treating procedures. In the rst run an acid treated and rerun heating oil fraction from a thermal cracking operation, a heating oil fraction from crude petroleum, and a heating oil fraction from a catalytic cracking voperation were blended together and then contacted with 40 B. caustic. After f the caustic wash the heating oil was doctor may be omiti Tests were obtained on l Run 11% Passes Does not passl. 0

Barely passes Joes not passe sample bottle and the `unstoppered bottle is maintained in an oven for 16 hours at allowed to cool to approximately room temperature and the Tag-Robinson color of It will be readily seen that the product obtained in accordance with the practice of the present invention in run 4 is superior in quality to those obtained by the other handling methods. Special attention is directed tothe vastly improved color of the products of run 4 `as compared to the products of runs 1 and 2. Run 3 did not contain any oatalytically cracked material; therefore, it is not strictly comparable with run 4. It will be noted, however, that the color stability, as reflected by the colorhold test ofl run 3, similar to runs 1 and 2, is vastly inferior t0 that of run 4. `The'other tests likewise reflect the superior product obtained by the practice of the present invention.

The superiority in product quality of the product obtained in the present invention was evidenced further on testing of samples of the material from the several runs after various intervals of storage. Samples after storing under conditions s'imulating atmospheric conditions in large storage tanks show the product of the present invention to remain substantially unchanged and l still meet the color specifications with a large margin ofsafety. y Y

In describing the present invention temperature and pressure conditions in the thermal given. Likewise,v in the several fractionation zones'the conditions of temperature and pressure are omitted since a person skilled in the art will be acquainted with the proper Aprocedures necessary to obtain the several fractions processed as described. Likewise, the amount and strength of the treating reagents are not given in describing the vpresent invention. These amounts can be determined by experimentation and may vary with the type of' stock undergoing treatment.

The nature and objects ofthe present invention having been described and illustrated, what 'We wish to claim as new and useful and to secure by Letters Patent is:

1. In a process for producing a heating oil the vsteps of subjecting a mixture of heating oil fractions from a thermal cracking operation and from a crude petroleum to treatment with an alkaline reagent, separating alkaline reagent from the treated mixture, doctor sweetening the treated mixture of heating oil fractions and admixing the doctor sweetened product with a heating oil fraction from a catalytically cracked product to obtain a blended heating oil.

2. A processv in accordance with claim 1 in which the blended heating oil is contacted with an adsorbent body. f

3. A process in accordance with claim 1 in which the doctor sweetened product is contacted -cracking and catalytic cracking operations are not cracking operationand recoveringv from the acid treated heating oil vfraction a heating oil fraction free of polymerized bodies, admixing said product free of polymerized bodies with a heating oil fraction from a crude petroleum and washing the mixture with an alkaline reagent, separating alkaline reagent from the admixture, .doctor sweetening the'caustic washed heating oil mixture, combining the doctor sweetened admixture with the-heating oil fraction from the catalytic cracking operation and ltering the mixture of the catalytically cracked heating oil and doctor which the heating oil fraction from the catalytic cracking operation is acid treated, rerun and then treated with an alkaline reagent.

8. In a process for nishing a heating oil to satisfactory quality the steps which comprise admixing a heating oil fraction from a crude petroleum with a heating oil fraction obtained by acid 'treating and rerunning a thermally cracked prodwith an adsorbent body before it is admixed With,

the heating oil fraction from a catalytically uct, caustic Washing the admixture of heating oil fractions, doctor sweetening the caustic Washed admixture, blending the doctor sweetened admixture With a heating oil fraction from a catalytic cracking operation and subjecting the blend to contact with an adsorbent material to obtain a iinished heating oil.

ARTIE Q. CATO. GEORGE WASH. ALBERT J. SHMIDL.

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