US2719105A - Process for the production of high quality heating oil blends - Google Patents

Description

Sept. 27, 1955 H. w. PETERSON, JR, ETTAL 2,719,105

PROCESS FOR- THE PRODUCTION OF HIGH QUALITY HEATING OIL BLENDS Filed Feb. 27, 1952 DISTILLAHOM 9 i5 1 lnzem 83 i2 2 HEATHJG On. a

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(lboorrzag United States Patent PROCESS FOR THE PRODUCTION OF HIGH QUALITY HEATING OIL BLENDS Harry W. Peterson, Jr., Somerville, Albert C. Henn, Linden, and Albert Gathman, Elizabeth, N. J., assignors to Esso Research and Engineering Company, a corporation of Delaware Application February 27, 1952, Serial No. 273,606

1 Claim. (Cl. 196-14.4)

The present invention is concerned with an improved process for the production of high quality heating oils. The invention is more particularly directed to a process for treating cracked heating oils whereby the cracked heating oils may be effectively blended with sweet virgin heating oils to produce a satisfactory high quality blended heating oil product. In accordance with a specific concept of the present invention, a virgin heating oil is blended with a cracked heating oil which has been subjected to a solvent treatment utilizing a low molecular weight alcohol solvent as, for example, a solvent comprising methyl alcohol. A particular desirable solvent comprises methyl alcohol used in conjunction with a relatively small amount of isopropyl alcohol.

The present invention is broadly concerned with the production of improved hydrocarbon mixtures known as heating oils of the nature employed in various burner systems, as diesel fuels, or as domestic and industrial heating oils. Heating oils may be derived from petroleum by a variety of methods including straight distillation from crude petroleum oil, and thermal or catalytic cracking of various petroleum oil fractions. Heretofore, in the art, heating oil blends comprised a relatively large proportion of virgin heating oil as compared to cracked heating oils. However, due to the desirability of virgin heating oils as feed stocks to various cracking operations, as for example, a fluid catalytic cracking operation, the blends comprise an increasing proportion of cracked heating oil fractions as compared to virgin stocks. Virgin heating oil fractions are also very desirable as diesel oil products which further decreases their availability for heating oil blends.

It is known in the art that heating oils consisting completely or in part of catalytic cracked stocks are characterized by an undesirable instability giving rise to the formation of sediment. It is also known that when cracked heating oils are blended with virgin heating oils certain undesirable characteristics are increased due to their incompatibility. As a result, such blended fuel oils tend to cause clogging of filters, orifices, or conduits associated with the burning systems in which they are employed.

It is also known in the art that when a virgin heating oil is blended with a cracked heating oil, the carbon residue of the blend in many cases exceeds the carbon residue of either the virgin heating oil or the cracked heating oil. This carbon residue is an indication of the extent the blended heating oil will carbonize the burners, par- 1 ticularly a rotary burner in actual use and to some extent determines the burning characteristics and desirability of the fuel.

In order to improve the quality of blended heating oils, various processes have been practiced in the art. It is known in the art to process a virgin heating oil by a caustic wash if the oil be relatively sweet. On the other hand, if the virgin heating oil has a relatively high mercaptan content so as to render it sour, the oil is processed by a doctor treat or an equivalent sweetening operation. On the other hand, light cracked heating oils in many 2,719 ,105 Patented Sept. 27, 1955 "ice operations merely require a caustic wash. However, the conventional procedure is to secure the cracked heating oil from a relatively severe cracking operation in which case it is necessary to acid treat the cracked heating oil followed by a caustic wash in order to control the carbon residue. This latter operation is not desirable since acid treatment polymerizes many desirable constituents resulting in a loss in yield. Furthermore, the sludge is expensive and difficult to handle.

In accordance with the present invention the instability of catalytically cracked heating oils may be substantially overcome and its compatibility for blending with virgin heating oils increased by subjecting the cracked heating oil fraction to a solvent treatment utilizing a low molecular weight alcohol as, for example, those containing from 1 to 5 carbon atoms in the molecule.

Heating oil blends which may be processed by the operation of the present invention are particularly hydrocarbon mixtures of which more than about 10%, preferably from about 15% to 60% by volume consist of stocks derived from cracking operations. More precisely still, the finished blends may be characterized as petroleum fractions containing a proportion of cracked stocks greater than 10%, preferably from about 15% to 60% by volume, and falling within A. S. T. M. specification D39648T for Fuel Oils (Grade No. 1 or 2). Inspections of a typical heating oil blend are for example:

Gravity, API 34.5 Distillation, A. S. T. M.:

Initial, B. P., F. 363 10% at F. 438 50% at F. 504 at F. 583 Final, B. P., F. 640 Flash, F. 158 Color, Tag Robinson 15 Viscosity, SSU/ F. 34.7 Pour point, F 0 Sulfur, wt. percent .37 Suspended sediment, mgs./ 100 ml 1.0 Carbon residue on 10% residuum, percent .08 Corrosion, 1 hr. at 212 F. Pass Diesel index 48.2 Aniline point, F

The process of the present invention may be more fully understood by reference to the drawing illustrating one embodiment of the same. Referring specifically to the drawing, a crude oil feed stock is introduced into distillation zone 1 by means of line 2. Temperature and pressure conditions in zone 1 are adapted to remove overhead by means of line 3 normally gaseous hydrocarbons and to remove by means of line 4 hydrocarbon constituents boiling in the motor fuel and naphtha boiling ranges. A virgin heating oil fraction is removed from zone 1 by means of line 5' while a gas oil fraction is removed by means of line 6. A residuum fraction comprising the higher boiling constituents is removed as a bottoms by means of line 7. The virgin heating oil fraction removed by means of line 5 may be treated by various processes in order to refine the same. Normally this fraction is treated with a mild caustic wash, as for example, sodium hydroxide in treating zone 8. The fresh caustic is introduced by means of line 9 while the spent caustic is removed by means of line 10.

The caustic treated virgin heating oil is removed by means of line 11 and sweetened if necessary by the removal of mercaptans in sweetening zone 12. The sweetening agent is introduced by means of line 13 while the spent sweetening agent is removed by means of line 14. Any suitable sweetening agent or process may be utilized as for example a doctor treat, a bauxite treat or by a Unisol process. The finished virgin heating oil is removed by means of line and blended with cracked heating oil produced as hereinafter described.

It is to be understood that distillation zone 1, treating zone 8 and sweetening zone 12 may comprise any suitable number and arrangement of stages. The gas oil fraction removed by means of line 6 is passed to cracking zone 22 which may comprise any suitable cracking operation, as for example, a thermal or a catalytic cracking process. However, the present invention is particularly directed toward the production of a high quality virgincracked heating oil blend wherein the cracking process comprises a catalytic cracking operation, as for example a fluid catalystic cracking operation.

A fluid catalytic cracking plant is composed of three sections: cracking, regeneration, and fractionation. The cracking reaction takes place continuously in one reactor at a temperature in the range from about 800 F. to 1050 F. The spent catalyst is removed continuously for regeneration in a separate vessel, from which it is returned to the cracking vessel, which is at a pressure below about 200 lbs. usually below about 50 lbs. per sq. in. Continuity of flow of catalyst as well as of oil is thus accomplished, and the characteristic features of fixed-bed designs involving the intermittent shifting of reactors through cracking, purging, and regeneration cycles are eliminated.

Regenerated catalyst is withdrawn from the regenerator and flows by gravity down a standpipe, wherein a sulficiently high pressure head is built up on the catalyst to allow its injection into the fresh liquid oil stream. The resulting mixture of oil and catalyst flows into the reaction vessel, in which gas velocity is intentionally low, so that a high concentration of catalyst will result. The cracking that takes place results in carbon deposition on the catalyst, requiring regeneration of the catalyst. The cracked product oil vapors are withdrawn from the top of the reactor after passing through cyclone separators to free them of any entrained catalyst particles, while the spent catalyst is withdrawn from the bottom of the reactor and is injected into a stream of undiluted air which carries the catalyst into the regeneration vessel. The products of combustion resulting from the regeneration of the catalyst leave the top of this vessel and pass through a series of cyclones where the bulk of the entrained catalyst is recovered. The regenerated catalyst is withdrawn from the bottom of the vessel to complete its cycle.

The cracked products are removed from cracking zone 22 (overhead from the reactor) by means of line 23 and introduced into a distillation zone 24. Temperature and pressure conditions in zone 24 are adjusted to remove overhead by means of line 25 normally gaseous constituents and to remove by means of line 40 hydrocarbon constituents boiling in the motor fuel boiling range. A fraction boiling above the heating oil boiling range is removed as a bottoms fraction by means of line 27. A fraction boiling in the heating oil boiling range is removed by means of line 26.

Spent catalyst is removed from the bottom of zone 22 by means of line 29 and passed into regeneration zone 30 by means of line 31. Regenerated catalyst is withdrawn from the bottom of zone 30 by means of line 33 and re-introduced into the reactor 22 with the fresh feed by means of line 6.

In accordance with the present invention the cracked heating oil withdrawn from zone 24 by means of line 26 is introduced into a solvent treating zone 41, wherein the same is contacted with a solvent comprising methyl alcohol. The solvent is introduced into zone 41 by means of line 42. Temperature and pressure conditions are adjusted in zone 41 to secure a raflinate phase which is removed by means of line 43 and a solvent extract phase which is removed by means of line 44. The solvent extract phase is introduced into solvent recovery zone 45, wherein temperature and pressure conditions are adjusted to remove overhead by means of line 46 the solvent, and to remove by means of line 47 a solvent-free extract.

The rafiinate phase withdrawn by means of line 43 is introduced into solvent recovery zone 48. Temperature and pressure conditions in zone 48 are adapted to remove overhead by means of line 49 the solvent which is preferably recycled to zone 41. A raflinate or treated cracked heating oil phase free of solvent is removed from the bottom of zone 48 by means of line 50 and is blended with the virgin heating oil constituents removed from zone 12. It is to be understood that treating zone 41 and distillation of solvent recovery zones 48 and may comprise any suitable number and arrangement of stages. The present invention is generally directed toward the production of a high quality heating oil blend comprising virgin constituents and cracked constituents. The invention is particularly directed toward the treatment of cracked heating oil constituents secured from a fluidized catalyst cracking operation. In accordance with the present invention these cracked constituents prior to blending with virgin heating oil constituents are treated with an alcohol containing from about 1 to 5 carbon atoms per molecule. The preferred solvent comprises methyl alcohol. A very desirable solvent comprises methyl alcohol containing a relatively small amount of isopropyl alcohol.

The amount of solvent utilized per volume of heating oil treated may vary from about 0.25 to 4.00 volumes of solvent per volume of oil contacted. It is preferred that the amount utilized be from about 1.0 to 1.5 volumes of solvent per volume of oil contacted. Temperature conditions are preferably in the range from about F. to 125 F. Preferred pressures are from atmospheric to 10 to 30 lbs. p. s. i. g.

When utilizing a solvent comprising, for example, methyl alcohol and isopropyl alcohol, the amount of isopropyl alcohol utilized should be from about 2 to about 33% by volume of isopropyl alcohol based upon the amount of methyl alcohol employed.

The process of the present invention may be more fully understood by the following examples illustrating the embodiments of the same:

Example I A cracked heating oil fraction secured from a fluidized solids catalytic cracking operation having the following inspections:

Distillation:

I B. P F 388 5 F 444 10 F 460 20 F 466 30 F 475 40 F-.. 482 50 F 488 F 496 F" 504 F 518 F 532 F 549 F. B. P F..- 568 Gravity, A. P. I 22.5 Percent aromatics percent 63.5 Sulfur, wt. percent 1.13 Gardner color 17% Acid heat F 28 Flash, (P-M) i 172 SUS viscosity at F Bromine No 5.8 Mixed aniline point C 41.4

was contacted in a number of operations utilizing various quantities of methyl alcohol. erations are as follows:

The results of these op- Gals. MeOH/Gal. Oil

In another series of operations a cracked heating oil was contacted with various quantities of alcohol with the following results:

Gals. MeOH/Gal. Oil

Potential sediment 24.6 1.3 0.9 0.7 1 4 Con-carbon bottoms .46 .34 .21 .16

Color (Gardner) 12 10% 9 8% 7 Example III In another series of operations a cracked heating oil secured from a fluidized solids catalytic cracking operation was contacted with various quantities of alcohol with the following results:

Gals. MeOH/Gal. Oil

Potential sediment 32. 3 0. 7 0. 5 0. 7 1. 1

Con-carbon 10% bottoms 36 16 13 Color (Gardner) 12% 10 9% 8% 7% Example IV In another series of operations a cracked heating oil fraction is contacted with methyl alcohol (1 volumes of solvent per volume of oil) and also contacted with a solvent mixture comprising methyl alcohol and isopropyl alcohol. The results are as follows:

Gals.

Gals. Percent Gal. g gfi ISO Extract Aromat- Aromat- Methyl g Yield ics ios Alcohol From the above it is apparent that the total yields of aromatics in the extract is appreciably increased by utilizing this solvent mixture. The extract oil is found to be an excellent aromatic solvent for various substances as, for example, dichloro diphenyl trichloro ethane, as well as other related organic compounds.

What is claimed is:

Process for the preparation of a high quality heating oil blend of low potential sediment and low Conradson carbon comprising virgin constituents and from about 15% to by volume of cracked constituents which comprises segregating virgin hydrocarbon constituents boiling in the heating oil boiling range and cracked bydrocarbon constituents boiling in the heating oil boiling range, treating said cracked constituents with from about 0.25 to 4 volumes of a solvent mixture consisting of methyl alcohol and isopropyl alcohol under conditions to secure a rafiinate phase and a solvent extract phase, said solvent mixture being characterized in that the amount of isopropyl alcohol utilized is in the range from about 2% to about 33% by volume based upon the amount of methyl alcohol employed, separating said rafiinate phase and removing the solvent therefrom to obtain treated cracked constituents and thereafter blending said treated cracked constituents with said virgin constituents.

References Cited in the file of this patent UNITED STATES PATENTS 1,766,768 Werkenthin June 24, 1930 1,781,421 Werkenthin Nov. 11, 1930 2,051,612 Loebel Aug. 18, 1936 2,234,207 Thiele Mar. 11, 1941 2,361,080 Bolt et al. Oct. 24, 1944 2,417,236 Cato et a1. Mar. 11, 1947

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