US1843861A - Oil cracking apparatus - Google Patents

Description

Feb 2, 1932. H n BASSETT 1,843,861

OIL CRACKI NG APPARATU 5 Filed May 21. 1927 Patented Feb. 2, 1932 PATENT OFFICE HARRY P. BASSETT, OF PHILADELPHIA, PENNSYLVANIA OIL CRACKING APPARATUS Application filed May 21,

My invention relates to a process and apparatus for the cracking of hydrocarbon oils and more particularly contemplates the subjection of crude and heavy hydrocarbons to a treatment whereby they will be dissociated into light oils, such as gasoline, without the deposition of carbon.

One object of my invention is to provide an apparatus and a process for the cracking of heavy hydrocarbon oils in which the cracking temperature, ratio of steam to oil vapor and other physical and chemical variables are capable of exact control, resulting in eliicient cracking with no deposition of carbon, and with the further advantage that the process may be operated at atmospheric pressure.

A further object of my invention is to provide an apparatus which is simple to construct and operate and in which the flow of heat and the flow of oil are most economically regulated and in which any uncracked heavy oil is automatically returned to the system. Other objects will be apparent from a consideration of the specification and claims.

In the annexed drawing, there is shown a diagrammatic cross-sectional view of one form of my apparatus in which my improved process for the cracking of petroleum oils may be carried out.

My invention is characterized by the exactness of physical and chemical control. Heretofore, cracking units have been suggested in which oil emulsions or mixtures of oil and water have been vaporized and passed through cracking units under heavy pressures. In this type of unit, the steam tends to va orize prior to the oil so that at the end of the cycle the ratio of steam to oil has been greatly reduced. The cracking units have not been capable of scientific temperature control and hence carbon deposits are encountered. The cracking reaction depends primarily on the ratio of oil vapor to steam and on the cracking temperature. A few degrees change of temperature Will result in inefliciency, while the absence of suflicient steam results in a deposition of carbon. In my improved process, the supply of steam is independent from the oil vapor supply and therefore the presence of sulficient steam in 1927. Serial No. 193,177.

the cracking unit is insured. The combination of oil vapor and steam constantly flow at atmospheric pressure through the cracking chamber in contact with an electrically heated element maintained at the proper cracking temperature. B this method, an exceptionally efficient crac ing is carried out Without any deposition of carbon in the cracking chamber. If the conditions are maintained as contemplated by the process of this invention, the oxygen of the water vapor combines with the carbon, forming gaseous carbon monoxide and hydrogen which pass out of the system with the light oils. This formation of carbon monoxide precludes the possibility of carbon deposition.

Another marked advantage and improvement in my cracking unit over those heretofore used is that the process operates at atmospheric pressure and while it is capable of use at an elevated pressure, the employment of atmospheric pressure gives a cracking process which is entirely satisfactory in operation. As hereinbefore pointed out, the invention contemplates a steady and independent flow of steam, preferably superheated, which is mixed with the heavy oil vapors and thereafter the oil and the steam mixture pass through the cracking chamber in contact with and around an electrically heated element, for example in the form of an electric coil whereby complete and efiicient cracking is possible.

In the annexed drawing, 1 represents an oil vaporizing chamber or still heated by a suitable source of heat 2. The oil enters the system through supply pipe 3 and thereafter passes through the jacket 4 in which it is heated to a certain extent and through the pipe 5 into the still 1. The steam is generated in any suitable boiler 6 and is preferably superheated in a superheater 7 and thereafter enters the system through a pipe 8, shown in the drawing at the base of the cracking chamber but obviously the steam may enter at any convenient place, for example, it may en ter the still below the oil level, thereby aiding the vaporization of the oil to a certain extent. The vapors from the still 1 and the steam from the boiler 6 pass without change of pressure through the cracking chamber 9 in which is located the electrical element 10 composed f metal with terminals 11 and 12 connected to the necessary source of electricity.

The electrical element 10 may be of any desired form and should be so arranged that it insures sufficient contact with the oil and am to completely crack the oil. In the drawing, 1 have shown it in the form of a metallic coil but obviously wire screens or other type of electrical metallic elements may be used. It is in this chambe' 9. that the cracking takes place and a constant supply of steam through the pipe 8 makes it possible at all times to have sufficient water vapor present to react with the oil vapors and thereby prevent incomplete reaction with the accompanying deposition of carbon. The electrically heated metallic element 10 is capable of instantaneous and complete control and can be easily maintained at the temperature necessary to give the desired results. The temperature ill vary with the pressure. the type of oil, and final product desired. For example, When cracking kerosene obtained from Pennsylvania paraliine at atmospheric pressure, a temperature of about 525 C. will give commercial gasoline. The passage of the oil vapors and steam into the cracking chamber without change of pressure results in fractional cracking due to the fractional vaporization of the oil. In other words. the lighter fractions are first brought in contact with the steam in the cracking chamber, followed by the next higher boiling fractions and so on until the heavy fractions are vaporized. It is thus possible to control the cracking by maintaining the temperature and water vapor in the cracking chamber which are the optimum for the particular fraction being cracked. The fractional vaporization obviates the difficulties encountered when all the oil is subjected to the cracking process at the same time which often results in the undercracking of some and the overcracking of other portions.

The mixture of cracked distillate, heavy oils and water vapor pass from the cracking unit 9 into the separator 13 which is surrounded by jacket 4 through which the incoming oil passes. The separator 13 and the jacket 4 act as a heat interchanger where- J) the incoming oil is raised in temperature and the vapors from the cracking unit 9 are cooled. The temperature in this interchanger is so regulated that the heavy oils and water are condensed and are removed at the bottom of the separator through pipe 14. while the cracked lighter oils are maintained as a vapor and are led from the top of the separator through pipe 15 into a water-cooled condenser 16 and are removed from the bottom thereof at 17 in a condensed condition the finished product. The condensed water and heavy hydrocarbon oils which are removed from the separator 13 by pipe 1 are carried 1nto chamber 18 and allowed to ity than the water floats on the top of the water and is returned to the oil vaporizer 1 through pipe 19 at 20. The water is lrawn oil through overflow 21, to which is attached the levelling stand-pipc 22. This arrangement maintains an equal level inside and ontside of the chamber and allows automatic delivery of water and oil from the settling chamber.

The separation of the condensed hydroarbon oil and water at the bottom of tie eepirator hereinbefore described is one of the novel features of my invention. This separator affords a continuous means of separating LllQ water from the oil and returning the oil to the system while the water is removed in any convenient manner. As far as 1 am aware. the oil has never heretofore been separated from the water in the system by means of the difference in specific gravities between the oil and the water with the accompanying return of the oil to the system.

My process may be carried out by various means and in various forms of apparatus and considerable modifications in the details of the apparatus from that shown in the annexed drawing are possible without departing from the essential features of my invention.

I claim:

1. An apparatus for the cracking of heavy hydrocarbon oils comprising a still for the crude oil; means for heating the oil within the still to a desired temperature to distill the oil; independent means for supplying steam to the oil vapor; a vapor cracking chamber so disposed with respect to the still that the vapors generated in the still w'll pass into the cracking chamber without change of pressure; a metallic element in said cracking chamber heated directly by the passage of an electric current therethrough and capable of maintaining said cracking chamber at a cracking temperture; a separator communicating with said cracking chamber for separating the light oils from the water and high boiling point oils; and condenser operatively connected to said separator for the recovcry of the finished gasoline.

2. An apparatus for the cracking of heavy hydrocarbon oils comprising a still for the crude oil. means for heating the oil within the still to a desired temperature; independent means for supplying steam to the oil vapor; a vapor cracking chamber so disposed with respect to the still that the vapors generated in the still will pass into the cracking chamber without change of pressure; a metallic element in said cracking chamber heated directly by the passage of an electric current therethrough and capable of maintaining said cracking chamber cracking temperature; a heat interchanger connected to said cracln'ng chamber and comprising an incoming oil chamber and a separating chamber within said incoming oil chamber by means of which the incoming oil is heated and the water and high boiling point hydrocarbons are condensed; a settling chamber communicating with said separator in which the high boiling point oil and water are separated by means of the differences in specific gravities; a conduit extending between the settling chamber and the oil still whereby the high boiling point oil is returned automatically to said oil still; and a condenser operatively connected to said separator for recoverin the finished asoline.

H RRY P. BA SETT.

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