US1865027A - Apparatus for cracking reduced crudes and the like - Google Patents

Description

June'28, 1932. N E. LOOMls 1,865,027

APPARATUS FOR CRACI-{ING REDUCED CRUDES AND THE LIKE Filed March lO, 1926 2 Sheets-Sheet 1 f gA b 1 .N h Q 2 L S 03 N n w "V if il l N l\ Q L m w 1g 1- lo 0 N N 0* l ,f xo. N

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APPARATUS FOR CRACKING REDUCED cRUDEs AND THE LIKE Filed March 10, 1926 2 Sheets-Sheet 2 l3c/msu? To WER cc UMULA TOR Ffa; -2

N {An-wwwa L Looms Juve/nto@ @ZM @Howe/1g l coil 23 arranged in a Patented June 2.8,'` 1932( UNITED STATES PATENT oFF-ICE NATHANIEL E. LOOMIS, OF 'WESTFIELD, NEW JERSEY, ASSIGNOR T0 STANDARD OIL Y DEVELOPMENT COMPANY, A CORPORATION OF'DELAWARE APIPARAT-US FOR CRACKING REDUCED CRUDES AND THE Application iled March 10, 1926. Seria No. 93,597.

This invention relates to improvements in processes and apparatus for the cracking of hydrocarbons intovl lower boiling products. ,The invention will be fully understood from the following description, taken in connection with the accompanying drawings, in

which Fig. 1 is a diagrammatic elevation of one suitable form of apparatus, and

Fig. 2 is a plan view of the same.

Referring to the drawings, reference numeral 1 denotes a shell still or equivalent distillation/or vapor-separating means, arranged in a furnace setting 2. The still 1 is preferably provided with internal horizontal flues 3, through which hot combustion gases from the furnace pass to a stack, not shown. The still is connected through line 4 with condensing and fractionating equipment, such as a bubble tower 5. This tower has the usual plates 6, receiving pan 7, vapor Vheat exchanger 8, vapor line 9, and condenser 10.

A condensate draw-off line 11, having a valve 12, conveys a fraction of the type of gas oil from Athe pan 7 to an accumulator tank 13. A line 14 serves to supply cooling fluid (ordinarily feed stockfor the system) to the vapor heat exchanger 8. A by-pass 15 in line 14 and valves 14', 15', are provided for the regulation of the supply of feed stock. Additional preheat may, be supplied in an exchanger 8', which receives the gas oil from the pan 7. Suitable by-pass lines are provided leading to exchanger 8',-as shown.

A line 16 carries the preheated feed stock to a tar heat lexchanger 17 which is supplied with hot tar from the still 1 through line 18, having a valvr19. The feed stock passes through the through pipes 20 and 21, in the latter of which a'pump 22 is installed, to a cracking furnace setting 24. Tar is withdrawn from the tar heat exchanger through 'valved line 25 to storage tar heat exchanger and thencel drums 27 and 28, in accordmore drums maybe operated in series, the

parallel arrangement 4 illustrated is preferred. Draw-oil' pipes 33 and 34 connect drums 27 and 28 respectively to a pipe 35 which discharges into the still 1.

A pressure release valve 36 is provided in pipe 35. The coil .and drums are to be operated at relatively high pressure, as is well understood in the art, and the drums should be thermally insulated as by means of a lagging 37, or in some other suitable way.4

The present invention is Aparticularly adapted to the treatment of reduced erudes,

ffor reasons which will be fully presented later. The following example, therefore, is based upon the use of such a stock, though it is to be `understood that the invention is not limited thereto.

Assuming the system to be in operation, a stream of reduced crude is preheated in the vapor heat exchanger 8 and tar heat exchanger 17 (also in exchanger 8', if desired), and is then passed continuously into the cracking coil 23 at a temperature of around 500 F. In the coil the temperature of the oil is'raised to about 850 F., and at this temperature it enters the drum or drums (27 and/or 28). The temperature of the converted product passing from the drums may be 750 F. or 'thereabout Vapors and liquid together are passed from the drum or drums into the still through the pipe 35.,

' .The pressure in the coll and drums may be, for example, about 300 to 350 pounds per square inch. This pressure may be reduced through vthe release valve 36 to substantially atmospheric pressure. The cooling incident to expansion of vapors may lower the temperature of the oil entering the still to about 700 F. The temperatures and pressures referred to abov'e are those generally preferred, but they may be varied.. A pressure control valve may be installed in the line 9, for use if it is desired to 'operate the still 1 and tower 5 under pressure.

In starting the operation, the still 1 is charged with reduced crude and fired to a distillation temperature. Reduced crude is supplied to the cracking coil, which is suitably fired. The eluent from the coil is discharged into the drum or drums, and the cracked product is delivered into the still, in the manner described.

The cracking coil and soaking drums may be operated under an suitable conditions. Generally, the oil will be passed through the coil a't such a velocity that most of any carbon forming therein is swept out into the drums. Conversion takes place in the coil and drums, in a manner well understood in the art; that is, incipient or partial conversion occurs in the coil and further conversion is effected in the drum, by virtue of the contained heat of the oil.

The heat content of the oil from the drum is not sufficient to vaporize in the still theV amount of gas oil required for best results. The proper amount of additional heat is therefore supplied to the still, preferably by passing hot combustion4 gases through its internal flues 3. This method of heating is grade crudes which have been distilled or the removal of gasoline. Without this heating the percentage yield of gasoline from such stock is limited by two factors, namely the qualityv of the tar produced, and the amount of gas oil that 1s available Aforrecycling. If the digestion is conducted atsuch a temperature that the heat content of the digested oil is sufficient to vaporize an adequate amount of gas oil, the carbon. sediment content of the residuum or tar will generally be so high as'to prevent its use as fuel oil. Conversely, if the digestion is carried out at a temperature low enough to insure ood'tar the amount of gas oil vaporized will Ee insufficient, and the yield of gasoline on recycling will be correspondingly diminished.

Inaccordance with the resent invention, therefore, I suppl heat in ependently to va- -porize the desire amount of gas oil. The

cracking is regulated to produce the maximum amount of gasoline` that may be obtained without causing the tar to produce too much sediment. The maximum amount ofsediment is usually 0.25%. '.Tar containin not more than this amount will meet unker C specifications for fuel oil.' For 66 nis cruv example when working with 55% Califorde bottoms (reduced crude), without heating the still or chamber connected to the fractionating tower, the usual yields areabout 20% gasoline, 10% refined oil, 20% gas oil, and 50% fuel oil capable of passing the standard sediment tests. The coke and glas loss is small and may be neglected for present purposes. The gas oil may be cracked with about 40% conversion to gasoline, making a total gasoline yield of 28%. With the heated still, the ,same initial a-mount of gasoline and refined oil may be obtained, but I take olf 40% of gas oil, the residuum being reduced to 30%. With a 40% conversion of the gas oil to gasoline, the total gasoline yield is 36%. In general, the still will be operated to produce at least 30% of gas oil.

The gas oil may be mixed with the reduced crude, if desired, and used as a feed stock for the ,same coil. It is generally preferred,

however, to crack the gas oil in a separate operation. The tar from this operation is available for blending with the tar from the reduced crude to produce a desirable fuel oil product.

The advantages of the invention are not necessarily dependent upon specific details of the construction and operation described, and various changes and alternative arrangements may be made within the scope of the appended claim, in which it is my intention to claim all novelty inherent in the invention as broadly as the prior art permits. This application is a continuation in part of my application Serial No. 45,195, filed July 22, 1925.

I claim:

Apparatus for cracking reduced crude oil comprising a cracking coil, a digesting drum connected to receive oil from the coil, a fractionating device, a chamber connected with said device, internal flues for at least partially heating the chamber, a connection for passing the cracked product directly and without substantial loss of heat from the digesting drum into the chamber, means for separately withdrawing the gas oil fraction ,from the fractionating device, heat exchange coils in the upper part of the 'fractionating device, a heat exchanger through which the hot tar from the chamber is passed and means for supplying the reducedcrude through said heat exchange coils and heat exchangerto the cracking coil.

NATHANIEL E. LOOMIS.

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