US2124514A - Method of transporting hydrocarbon oils - Google Patents

Description

Patented July 19, 1938 UNITED STATES METHOD OF TRAN SPORTING HYDROCAR- BON OILS Richard J. Dearhorn, Summit, N. J., assignor to The Texas Company, New York, N. Y., a corporation of Delaware Application February 27, 1937, Serial No. 128,069

4 Claims.

This invention relates to the treatment of hydrocarbon oils to improve the volatility. The invention further relates to the stabilization of hydrocarbon oils by decreasing the amount of the more volatile, unstable components. In particular, the invention has to do with treatment of crude oils to improve the volatility characteristics thereof by transforming lower boiling, unstable hydrocarbon components into less volatile, stable products, whereby there is obtained a treated crude which may be transported through pipe lines with greater facility.

The invention contemplates broadly the treatment of any hydrocarbon oil containing constituents which are desired to be transformed into products of improved volatility which may be readded to the main body of the oil to obtain a mixture having the desired volatility characteristics. The invention is advantageous in the treatment of hydrocarbon oils containing low boiling, unstable constituents which render the oil unsuitable for use or difiicult to handle due to the instability of the low boiling constituents. The inventionis particularly applicable to the treatment of crude oils containing normally gaseous hydrocarbons which render the crude difficult to handle or transport and entail large losses, due to evaporation in storage and transportation.

A principal object of the invention is to provide improvements in the transportation of crude mineral oils through pipe lines by polymerizing the unstable, low boiling hydrocarbons to higher boiling stable products, whereby the crude oil is more easily and more economically transported.

The invention will be described with particular reference to crude oil, but the invention is not restricted to this particular application, and it is to be understood that the principles of the invention may be applied for the treatment and handling of various types of oils, as will occur to those skilled in the art.

Usually crude oils contain considerable amounts of light hydrocarbons of varying degrees of volatility, and it is common practice to stabilize the crude oil by fractionating out a certain amount of the light, normally gaseous hydrocarbons to obtain a product of desired stability before transporting the crude through the pipe lines. In accordance with this procedure, it is common practice to separate all hydrocarbons lighter than butane. disposed of by exhaustion to the air or burning as useful fuel, or otherwise. In fields of large production, it may be impossible to utilize all the separated gases and accordingly considerable waste may occur of valuable hydrocarbons, including propane and considerable amounts of butane. This condition may occur particularly in The separated'hydrocarbons are then fields situated in undeveloped areas, particularly in foreign fields where it is necessary to transport the crude oils long distances to seaports or developed areas suitable for refinery locations.

In accordance with the present invention, crude oil from the well, or a portion thereof withdrawn from a main pipe line, is subjected to stabilization and fractionation to separate the normally gaseous hydrocarbons which are undesirable for transportation through pipe lines. The amount of gases so separated may vary, but in general it is contemplated that all or a portion of the propane, or all or a portion of the propane and butane, along with the lighter gases, may be separated. If the separated gases contain large amounts'of methane and ethane, it is desirable to separate the methane and all or a portion of the ethane, which may be usedas fuel and to recover an intermediate fraction which ordinarily would predominate in propane, along with the various amounts of ethane and butane. The

separated gaseous fraction or the intermediate the crude oil and the mixture transported through the pipe line.

The invention will be more fully understood from the following detailed description taken in connection with the accompanying drawing which is a diagrammatic view of one form of apparatus suitable for use in practicing the invention.

Referring to the drawing, the raw crude is introduced through the line I which may be a main pipe line or a branch line in communication with a producing well, or a feeder line leading to a trunk pipe line. This line comprises the incoming section I, a by-pass section 2 and an out-going section 3. In communication with the line is a take-off branch 4 for Withdrawing from the line I all or a portion of the oil which is treated and then returned to the outgoing section 3 through the return line 5.

The oil withdrawn through the take-off line 4 is passed either with or without the aid of the booster pump 1 into thefractionator or stabilizer 8. A portion or all of the oil may be introduced into the fractionatorthrough the branch line l0, but it is preferable to pass the oil through the lines II and I2, connected by a heat exchange coil l3 wherein the oil is preheated by indirect heat exchange with the stabilized product drawn off from the lower portion of the fractionator. The oil introduced into the fractionator is further heated by the heating element l4, located in the located in a furnace l9, and connecting lines and 20. Any suitable heating medium, such "as" Steam or any other fluid, maybe circulatedin the heating system.

It is intended that the crude be stabilized i orfractionated to the desired extent in the frac-1 tionator or stabilizer 8. For this purpose the low boiling hydrocarbons undesirable to be retained in the crude during transportation are volatilized;

fractionated and withdrawn from the top of the.

fractionator through the line 22. The gaseous fraction removed from the top of the separator may be subjected as such to polymerization. In case this fraction contains too large a quantity of low boiling hydrocarbons or fixed gases, such as methane and ethane, itmay be transferred through a line, not shown, to the separator referred tov hereinafter, wherein the fixed gases would be separated without going through the polymerization system. I I

The hydrocarbon fraction intended for polymerization is compressed by a pump 26, preferably to a high pressure of the order of 500-5000 pounds. The compressed products substantially in the liquid phase are then passedthrough the line 27 to a heating coil 28, located in a furnace 30. In the coil 28, the hydrocarbons are subjected to polymerizing temperatures of 900-l200 F. and preferably around 1020-1060 F.,'for a'sufficient time, usually around 41-3 minutes, to

convert a substantial amount of the normally gaseous hydrocarbons into normally liquid hydrocarbons. The polymerization products are, then transferred through a line 32 in which may be located a transfer line heat exchangeror other cooling means, not shown,"to separator 33. In

this separator the normally liquid products are condensed and fractionated out and Withdrawn from the lower portion of the separator, through the'line 34. Vapors and gases uncondensed in the separator 33 are conducted through the vapor line 3| to a separator 35, referred to heretofore.-

'In this separator an intermediate fraction, in-

cluding propane and butane, is condensed and separated from the fixed gas fraction, including hydrogen, methane and ethane. mediate fraction is withdrawn from the bottom of the separator through the line 36 and recycled by the pump 31 to the polymerization coil 28. The wastegases are withdrawn from the top of the separator 35 and are discharged through the line 38. In case these gases are desired to be used as fuel'for the system, they may be passed through the line 40 to a burner located in the furnace [9, or through the branch line 4| to a burner located in the furnace 30. Also the gas may be used, if desired, to operate the pump 42 by withdrawing a portion thereof through the branch line 43. Y Y

The stabilized crude is withdrawn from the stabilizer 8 through the line 45 and combined with the polymer product, withdrawn from the separator 33 through line 34. The mixture is passed through a cooler 46, and forced by means of the pump 42 through the outlet line 5 to the pipe line.

The amount of polymerization products returned from the crude will depend upon I the nature of the raw crude oil. The more unstable the raw crude, the larger the amount of unstable The interor wild constituents that will be separated therefrom and be available for polymerization. Often crude, oils contain 5-10% or more of unstable products, and when these predominate in propane and butane, it is possible to convert around -60%, or more, of these materials into a polymer product. which may be readded to the icrude oil. This polymer product is transported with a mixture of the crude to the refinery and there' recoyered in the refining operation as a portion of the motor fuel fraction.

The present invention comprises an advan- -tageous means 'for economically utilizing the waste gases in an oil field by polymerizing them to valuable motor fuel hydrocarbons. The invention also provides a convenient method of polymerizing thesehydrocarbons in conjunction with the stabilization of the crude. Furthermore, in

accordance with the invention, the polymerized hydrocarbons are readded to, and transported with the crude oil through a single pipe line, thereby furnishing an. economical means for the transportation of the polymerized product. Moreover-,in accordance with the invention, the production of stabilized crude is materially enlarged and the motor fuel content thereof, substantially increased.

. Obviously many modifications and variations of; the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof; and therefore only such limitations should be imposed as are indicated'in the appended claims- I claim:

1. A process for stabilizing crude oil, which comprises separating from the oil normally gaseous hydrocarbons thereby forming a stabilized crude, subjecting said normally gaseous hydrocarbons to polymerizing conditions of temperature and pressure whereby a substantial amount of normally liquid hydrocarbons is formed and readdingsaid normally liquid hydrocarbons to the stabilized crude.-,

2. A process for the treatment of crude oil in preparation for transportation, which comprises subjecting the crude to a stabilizing operation to separate normally gaseous hydrocarbons therefrom and form a stabilized crude, subjecting the normally gaseous hydrocarbons to polymerizing conditions of temperature and pressure thereby producing a substantial amount of normally liquid hydrocarbons, separating the normally liquid hydrocarbons from the reaction products and readding the separated normally liquid hydrocarbons to said stabilized crude.

3. In the transportation of hydrocarbon oils throughpipe lines, the improvement which comprises withdrawing at least a portion of the hydrocarbon oil from the pipe line, separating normally'gaseous hydrocarbons from the oil, polymerizing said normally gaseous hydrocarbons to normally liquid products, readding the polymerizedliquid hydrocarbons to oil and returning the mixture to the pipe line. Y

4. In the transportation of crude oils through pipe lines, the improvement which comprises separating normally gaseous hydrocarbons from the crude, polymerizing said normally gaseous hydrocarbons to normally liquid products, readding said liquid products to the crude and transporting the mixturethrough the pipe line.

. RICHARD J.'DEARBORN.

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