US2050816A

US2050816A - Process for treating hydrocarbon oils

Info

Publication number: US2050816A
Application number: US623990A
Authority: US
Inventors: Le Roy G Story
Original assignee: Texaco Inc
Current assignee: Texaco Inc
Priority date: 1932-07-22
Filing date: 1932-07-22
Publication date: 1936-08-11
Anticipated expiration: 1953-08-11

Description

LE ROY G. STORY Filed July 22, 1932 INVENTOR PROCESS FOR TREATING HYDROCARBON OILS Aug. 11, 1936.

ATTORNEY Patented Aug. 11 I936 Le Roy G. Story, Beacon, N. Y., assignor to The Texas Company, New York, N. Y., a corporation of Delaware Application my 22, 1932, Serial No. 623,990

2 Claims.

This invention relates to processes for the treatment of hydrocarbon oils and more particularly to processes forthe productionof gasoline of high anti-knock value. 7

In accordance with my invention natural gasoline or other motor fuel having a relatively low anti-knock rating is reformed or converted to produce gasoline of higher anti-knock value by the application of heat and pressure. The contained heat of the resulting reformed product is utilized in stripping straight-run gasoline from crude oil, the straight-run gasoline thereafter being combined with the natural gasoline or other product of low anti-knock value undergoing reformation. By utilizing a process embodying these steps production of high antiknock gasoline may be economically carried out.

My invention will be more fully explained in the following description taken in conjunction with the accompanying drawing.

The single figure of the drawing is a diagrammatic view of an oil treating system embodying my invention.

Referring more particularly to the drawing, natural gasoline or other hydrocarbon motor fuel of low anti-knock value is introduced through a charging line I having a valve 2, into heating coil 3 of furnace 4. The heated oil from the coil 3 travels through line 5, heat exchanger 6, and reducing valve 7 into fractionator 8.

In the fractionator 8 the products are sepa rated into vapors which pass off through line 9 and condenser into receiving drum H, and liquid products which are withdrawn from the fractionator through line l2 having valve GI and are injected into flash chamber or separator l3 through line l4 under pressure generated by pump l5. This pump may be eliminated where the pressure in fractionator 8 is great enough to force the condensate into line [4. Line l4 has a reducing valve I6 therein which serves to lower the pressure on the liquid products, which evaporate in the still l3. The flash chamber has baflle plates l1 therein which serve to separate entrained particles from the vapors, which are carried through vapor line l8 into a second fractionator l9 from which the lighter products pass off as vapors through line and condenser 2| into receiving drum 22. Fractionator l9 has a trap-out plate or other means (not shown) for separating a side stream of naphtha suitable for reformation and this product may be conducted from the fractionator through return line 23 and pump 24 to line I, which leads to the reformation coil 3. The line 23 has a valve 25 for controlling the flow of side stream liquid from fractionator l9, and a connection 26 is furnished for conducting final naphtha distillate from receiving drum 22 into line 23, so that a portion of this product may be reformed if desir-. able.

A conduit 28 having a control valve 29 connects the bottom of fractionator l9 with the return line 23, and a pipe 30, controlled by a valve 3|, is also furnished whereby reflux condensate can be withdrawn from the system. Instead of the vapors from the flash chamber passing through line 18 to fractionator I9 they may be diverted through condenser 32 into line 23 by opening valve 33 in line 34 and closing valve 35 in the line leading to the fractionator.

Fresh charging stock, such as crude oil having a gasoline content, is supplied to the system by pump 31 which forces the oil through a conduit 36, cooling coil 38 in fractionator l9, cooling coil 39 in fractionator 8, heating coil 40 in the furnace 4, heat exchanger 6 and line 4| which connects with the conduit l4 leadingto the flash chamber or still I3. The heat exchangers 38 and 39 and heating coil 40 may be partially or completely by-passed as desired by proper manipulation of valves 42, 43, 44, 45, B0 and 46. A conduit 41 is also provided for by-passing heated products from coil 3 to fractionator 8 and the amount of fluid by-passed may be regulated by

valves

48 and 49.

The temperature and pressure maintained in heating coil 3 should be that best adapted for reforming, or improving the anti-knock rating of the gasoline passing therethrough. The temperature may be for example 900 F. to 1200 F. and. the pressure of any suitable value, for example several hundred pounds per square inch, although pressure of 1000 to 2000 pounds per square inch may be used. In passing through the heat exchanger 0 the hot products from coil 3 are-reduced in temperature to a lower value, e. g. 500 F. The reducing valve 1 may lower the pressure on the products to approximately an atmospheric value or this valve may be adjusted to permit approximately the same pressure to obtain in both the fractionator 8 and heating coil 3. The temperature of the combined products in line H! may be 350 F. and the pressure may be of any value best suited for a stripping operation. This pressure will usually be low, for example 10 pounds per square inch although somewhat higher pressure may be maintained advantageously to prevent vaporization of the crude oil in the heat exchanger 0. Where low pressure is used no pressure reducing action is needed at valve I6. and on the other hand if the higher pressure is used reduction may take place at this valve. The bottoms may be drawn off from the separator l3 through line 58 controlled by valve 5| and be conductedwhile in a heated condition to some other well known form of cracking system, (not shown) or the oil may be cooled and put in storage.

The separator l3 may be so arranged and the temperature and pressure of the products be so correlated that substantially only gasoline of suitable boiling range for motor fuel will be re-, moved therefrom through the vapor line I8. The gasoline removed may be passed entirely into the line 23 leading to heating coil 3 by closing valve 35 and opening valve 33. In this case all of the gasoline products will be subjected to the reformation process. It may be found in certain cases that only the higher boiling point ends of the gasoline-like products need be reformed, the lighter products having a. sufliciently high antiknock rating without such treatment. case liquid products may be; removed from. the fractionator l3 either in the form of reflux condensate through conduit 28 or as a side stream through the pipe line 23, or both. The final products contained in receiving drums ll and I2 may be blended if desired by opening valve 52, in line 53 and either of the final products or a blend of the two, may be returned to the coil 3 through lines 26.. and 23 by proper manipulation of

valves

52, 54 and 2.1. T'ifty-five (55) and 56' are valved draw-off lines for distillate from the receivers H" and 22 respectively, while valved lines 5! and 58 serve as gas vents for these chambers.. The reflux condensatenot recycled from the bottom of fractionator l9 may be withdrawn fronrthe. system through the. conduit 30. ,A corresponding valved line69 provides a means for withdrawing excess condensate from fractionator a. w 7

operation gasoline tolloe reformed to improve its; antirknock value is-vintroduced through the line I- to heating coil 3 under a temperature of. any suitable value determined by the characteristicsof the'gasoline, for example 900 F. to 12005 F. and a pressure of; several hundred pounds per; square inch.- The heated products pass through heat exchanger 6 and are somewhat cooled thereby, their exit temperature-being possibly 500 F. The partially cooled products are then passed through the pressure reducing valve 1 and expanded into fractionator 8 with the result that final end point vapors pass off through theline 9 and are converted to liquid in thecondenser Il.-,. the, liquid being collected: in accumulator drum IL, Fractionation in the column 8 is aided by the action of cooling coil '39 which serves also to heat crude oil or other gasoline containing stock introduced through line 36, as explained hereinafter. The reflux condensate from fractionator 8 is conducted; through lines l2 and I4 intothe flash chamber or separator l3 along with the heated crude oil. The vapors from the flash chamber are transferred either to the condenser 32 or fractionator l9 while the liquid products from the flash chamber are withdrawn through draw-off line 58. If the vapors are conducted to the condenser 32 they are forced by the pump 24 to the heating coil 3 along with the natural gasoline, but if they are instead directed to the fractionator 13 they are. separated into lighter vaporous products and liquid. products. The light vaporous products pass overhead,. are partially In this condensed by the action of coil 38 and those remaining are carried off to the condenser 2| and receiving drum 22. Liquid products of the desired boiling point are Withdrawn from the fractionator either through conduit 28 or pipe 23 or both and without further cooling are introduced into the heating coil 3 by action of pump 24. The products returned to the heating coil by the pump just mentioned should be of a character such that an increase of anti-knock value by reformation is desired and the arrangement of piping which has just been described is provided so that a proper selection may be made. It has been pointed out hereinbefore that the point of removal of the liquids to be returned to the heating coil will depend upon the character of the products being treated as well as the temperature and pressure of the oil in line l4 and the operating characteristics of the flash chamber l3.

The lighter products of certain natural orstraight-run gasolines sometimes also need. reformation tOi increase their anti-knock value and in this case the finaldistillate collected in accumulator drums H arrd'2-2 may be returnedindividually or togetherwith any ofthe liquid productswhich have already been mentioned as subject. to reformation; According to one desirablermode of operation only gasoline stripped from the crude charged to the system is. passed through heating coil 3, for reformation, the supply-of natural gasoline introduced into pipe l being .cut ofi.

Economical operation of thesystem is insured by introducing fresh crude oil or other oil containing a. certain amount, of gasoline from line 36 through pump 31, heat exchanger 38 and 39, heating coil 40 and heat exchanger 6 into. the line l4, leading to the flash chamber 13. By this arrangement a large amount of the heat neces'- sary to strip the gasoline content, from the crude oil is derived by indirect contact inheat exchanger B, with the vaporous'prod-ucts from heating coil 3 and likewise by the added heat directly derived from the hot reflux condensate contributed by fractionator 8. Any added amount of .heat necessary or desirable for the stripping operation may bederived from the heating coil 40' of. the-furnace 4, the amount of heat picked up this manner being regulated by the proper setting of valves 48 and 8G. 1 A. certain amount of heat. is also: picked up by the crude oil in passing through; vapor cooling col-ls 38. and 39 of the fractionating columns.

I have. described a particular embodiment of my invention for the purpose. of illustration but it should be understood that various modificationsv and adaptations thereof may be made within the scope: of the invention, as; set forth by thegfollowing; claims. 1

I; claim:

1. The method of producing gasoline of high anti-knock value which comprises stripping crude hydrocarbon oil ina stripping zone to produce straight-run gasoline, separating said gasoline into a lighter portion and a heavier portion, cracking said heavier-portion at high temperature under superatmospheric pressure to increase its anti-knock value, passing the resulting cracked products, prior to reduction of the pressure thereon, in indirect heat exchange relationship with the crude oil to be stripped, subsequently; flashing said cracked products in. a zone separate; from said stripping zone to form vaporous gasoline products and heavier liquidproducts, combining said liquid products with said crude oil after the preheating thereof by said indirect heat exchange step and introducing the resulting mixture into said stripping zone wherein said stripping action takes place.

2. The method of treating hydrocarbon oil which comprises passing relatively low antiknock naphtha through a heating zone wherein it is raised to a reforming temperature and subjected to conversion into higher anti-knock gasoline constituents, passing the resulting reformed products in indirect heat exchange relation with fresh relatively heavy charging stock comprising lighter constituents in the gasoline boiling range and heavier constituents which has previously been passed through an externally-fired preheating zone, subsequently introducing said reformed products into a first zone wherein vapors separate from liquid residue, fractionating resulting vapors and condensing the fractionated vapors to form a light distillate, passing the preheated fresh charging stock from said indirect heat exchange step into a second zone wherein vapors separate from liquid residue, combining said liquid residue first-mentioned with said fresh charging stock after the passage thereof in indirect heat exchange with said reformed products to aid in the separation of vapors therefrom, fractionating said vapors last-mentioned to form a light distillate and blending said light distillates to form a final desired product.

LE ROY G. STORY.