US2178329A - Manufacture of low boiling hydrocarbon oils - Google Patents

Description

Oct. 31, 1939. LE ROY a. sToRY MANUFACTURE OF LOW BOILING HYDROCARBON OILS Filed Jan. 50. 1957 Mme-(Om H HWWWWWH.

LE ROY 6.5mm

INVENTOR w m W .M

Patented Oehf3l, 1939 orr cs MANUFACTURE OF LOW BOILING HYDROOARBON OILS lire Roy G. Story, White Plains, N.

to The Texas Company, New York, N.

Y., assignor corporation of Delaware 'Application January 30, 1937, Serial n 123,127 a 3 Claims.

This invention relates to the manufacture of low boiling .hydrocarbon oils, such as gasoline,

fromhigher boiling hydrocarbon oils and normally'gaseous' hydrocarbons and has to do particularly with a gas reversion type of operation in which a higher boiling hydrocarbon oil is cracked in the presence of normally gaseous hya small amount of oxygen to promote the re-' drocarbons to increase the yield and improve the quality of the "motor fuel product. n

An important-object of the invention is to contact. the oil and gases undergoing conversion with action between the heavier oil and thegases to produce products of intermediate boilingpoint range. v

In accordance with the invention, a cracking stock is subjected'to conversion conditions of temperature and pressure whereby higher boiling oils are converted into lower boiling Products gaseous products lighter than gasoline.

including gasoline, the cracked products separated into a residuum, a clean distillate which is recycled to the cracking operation, gasoline-"and gaseous hydrocarbons are further fractionated to separate a normally gaseous hydrocarbon fraction, preferably predominating in Ca and C4 bydrocarbons, which is recycled to the cracking operation. A small amount of oxygen is contacted with the oil and gases subjected to con-f version conditions in order to promote interaction between the oil'and gases, or reversion 'of the gaseous hydrocarbons to products ofboiling range between the gases and the oil charged.

An extraneous gaseous hydrocarbon charge may be introduced into the system to increase the proportion of normally gaseous hydrocarbons in the charge to the cracking zone. d

The invention will be more fully understood from the following description which is intended to be read in connection with the accompanying drawing showing-a sketch of apparatus suitable for carrying out the process of the invention.

Referring to the drawing, a charging stock suitable for cracking or reforming, such as gas oil, naphtha or reduced crude, is charged through line I controlled by valve 2 and forced by the pump 3 into a heating coil 5 located in a furnace 6. In the heating coil the oil. is subjected to cracking conditions of temperature and pressure, which will depend on the type of oil used, but

it isv intended that as high a temperature as possible will be maintained int-the coil without encountering coking difllculties. Temperatures of 850-1100 F. and preferably around 950 mm F., and pressures of WHOM-pounds, and rub!- Theerably around 750-1500 pounds, may be employed. The higher temperatures may be used in converting lighter products, such as naphtha or gas oil, and in such case the reaction is largely in the vapor phase. Products from the coil 5 are passed through the transfer line 8 to a soaker M wherein the cracked products pass downwardly affording additional time of reaction. The conditions maintained in the seeker are preferably as near as possible those maintained in the heating coil, 10

except for the ordinary loss iii temperature and pressure, encountered in passing through the coil and transfer line to the soaking drum. .For example, the pressure may be about 100 pounds less in the coking drum and a drop-in temperature of around 50F. Residual products which may be heavy fuel oil 'or-coke collect in the bottom and may be removed through the valve controlled line II or a suitable manhole. The vapor products separated in the; seeker are withdrawn through the vapor line I2 controlled by'valve Hi to evaporator l4. Inthis evaporator the vapors are partially condensed to form a clean condensate which is withdrawn from the bottom ofthe evaporator through the lineli, controlled by valve l6, and forced by the pump I! back to the heating coil 5. A portionof the charging stock, if desired, may be introduced into the upper portion of the evaporator I through the line by the pump 2|. It is intended that substantially all the hydrocarbons of higher boiling point range than gasoline be condensed in the .evaporator. The gasoline and lower boiling point hydrocarbons as vapor and gases pass from the top of the evaporator through the vapor line 23 to fractlonator 25.

The fractionator 25 is divided into two sections and serves to stabilize the gasoline in the lower portion and to fractionate the normally gaseous hydrocarbons in the upper. In the lower portion of the fractionator the gasoline hydrocarbons are condensed and fractionated to pro-' duce a stable gasoline condensate which is with- 4 drawn from the bottom of the tower through the valve controlled line 26. The vapors and gases of lower boiling point than gasoline pass through the conduit 28 to the upper portion 0!. the fractionator wherein they are fractionated to separate a condensate fraction suitable for recycling, to the system. Vapors from the top of the tower are withdrawn through-the vapor line 30 to condenser 3| and the condensatecollected in accumulator 32. This condensate which may be largely C3 hydrocarbons including propane is withdrawn from the accumulator I! through the ime and recycled by pump Ii to'the top of the towerasareiiuxandcoolingmedium. Extranewshydrocarbongasasuc'hasnaturalgasolineorafractionthereofsuchasmeand of the fractionator through the line 31 by the pump 30; the condensate collected .in the middle portion of the tower around the conduit 20 and preferably consisting essentially of Ca and C passesthrough a re-coiler II, the bottoms, of which are withdrawn through the line ll and recycled by the pump back to the system. This gaseous fraction conveyed throughline if maybe conducted directly to the entrance of the heating coil I through the line N, or a portion or all may be by-passed through the line ll, by suitable manipulation of the valves 40 and 41, directly to the soaker. I

.An oxygen-containing gas such as relatively pure oxygen or air is introduced through the line II by pump ll into the system, preferably in combination with the gaseous hydrocarbon charge passing through the line ll. oxygen so introduced is usually less than and preferably around 5% to 1% of the combined oil and gaseous charge to the heating coil I. A convenient method of introducing the oxygen is mixing in proper proportions with the gaseous hydrocarbon charge and in such proportion to give the desiredamount of oxygen to the charge.

The normally gaseous hydrocarbons charged to the cracking coil may range from 540% and preferably around Ill-20% of the fresh charge and recycle oil and the amount of oxygen added may be about 5- 10% thereof.

As an example of the operation of the invention, a gas oil was subjected to cracking at about 1000 I". and a pressure of about 750 pounds, the cracked products separated into vapors and residuums, the vapors fractionated to form a recycle gas oil which was returned to the crachng coil.. The gasoline was separated from the remainingvapors and the gaseous hydrocarbons fractionated to separate the C: and C4 hydrocarbons which were also recycled to the cracking coil. The amount of recycle gaseous hydrocarbons was around including about 5% extraneous hydrocarbon fraction consisting essentially ofpropane and butane. About 10% by volume of oxygen was added to the recycle gases. A yield of about 80% gasoline of about 78 octane number was obtained.

' In United States Patent No. 2,149,800, March 'I, 1939,'to the present applicant, there is disclosed the conversion of hydrocarbon oils by partial oxidation with oxygen and oxygenated gases, whereby gasoline and a large amount of gaseous products are formed, and the polymerization of said gaseous products to produce additional gasoline.

Obviously many modifications and variations of the invention as hereinbefore set forth may be made without departing from the spirit and The amount of' scope thereof and therefore only such limitations shouldbeimposedasareindicatedintbeappended claims.

I claim:

1. A process for the manufacture of gasoline,

mixture with a minor proportion of normally gaseous hydrocarbonsand in the absence of gaseous products of combustion to cracking conditions of temperature and pressure whereby a substantial amoimt of lower boiling products containing oil of the gasoline boiling point range is formed from the higher boiling oil and gaseous hydrocarbons, separating the reaction products into a fractionheavier than gasoline, a gasoline fraction and normally gaseous hydrocarbons, fractionating the normally gaseous hydrocarbons to separate a fraction predominating in Ca and C4 recycling the fraction of Cr and C4 hydrocarbons to the cracking operation and contacting the oil and gaseous hydrocarbons while under cracking conditions with about /2 to 1% of oxygen as a catalyst to accelerate the conversion of the oil and gases to gasoline hydrocarbons.

gaseous hydrocarbons to separate a fraction predominating in hydrocarbons of 3 and 4 carbon atoms, recycling said fraction to the cracking operation and contacting the hydrocarbons while maintained under cracking conditions with about 55 to 1% of oxygen to promote the conversion of the oil and gaseous hydrocarbons to products of intermediate boiling point comprising gasoline.

3. A process for the manufacture of motor fuel,

which comprlsessubjecting a high boiling point hydrocarbon oil and normally gaseous hydrocarbons free from pressure far from the system to cracking temperatures in a heating coil and' enlarged reaction chamber. separating the cracked products into vapors and lmvaporized residuum, separating from the vapors a gasoline fraction and a clean recycle stock, returning said recycle stock to the heating coil, fractionating the uncondensed vapors to produce a gaseous. fraction predominating in hydrocarbons of 3 and 4 carbon atoms, recycling said gaseous fraction to the cracking operation and commingling

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