US1597476A - Apparatus for distilling and cracking crude petroleum and distillate - Google Patents

Description

Aug. 24 1926.

C. M. PAGE APPARATUS FOR DISTILLING AND CRACKING CRUDE PETROLEUM AND DISTILLATE Filed August 26, 1920 2 Sheets-Sheet 1 Aug. 24 19% 1,597,476 I C. M. PAGE APPARATUS FORDISTILILING AND CRACKING CRUDE PETROLEUM AND DISTILLATE Filed August 26, 1920 2 sheets $heet 2 Caz M'PHGE Patented Aug. 24, 1926.

' UNITED STA-TIES" 1,597,416 PATENT oFFica.

, cum in. Pass, or CHICAGO, rumors, ASSIGNOR .ro snonsn FAJBYAN, or ennnva,

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arramrus FOR nrs'rnmme AND C ACKING cnnnn rnrnorn'un AND DIS'IILLATE.

Application filed August 26, 1920. Serial No. 406,179.

In the manufacture of gasoline or motor spirits by the treatment of high boiling point, residual, particularly the residual from the fractional distillation of paraffine base petroleum, after the lowerboiling distillates are removed, a lower boiling point' roduct of the parafiine series "is obtained y cracking. This is accomplished by raising the boiling point of the liquid residue by means of back pressure on the liquid and vapors which are maintained under such pressure throughout their course from the still'through the condenser and while undergoing condensation. This process is I known as theBurton process and such distillation of petroleum under pressure has been safely carried out on a large scale.

However, in this process and in any of the many allied-processes the great danger and chief difiiculty is due to the deposition of hard flinty coke on the inner walls of theheating element. Some-who have had considerable experience in cracking oil have said that the coke is forced into combina tion with the iron, making it brittle and utterly unable to withstand the high temperature' and pressure employed At any rate, the greatest deposition of the carbon occurs where. the wall of the still is hottest,

-causing a local overheating at that point.

Under such conditions the strength of the steel becomes an unknown quantity and as likely as not it yields to the stress without any warning. Oil 'vapors of a temperature around 650 F. ignite spontaneously when they evolve from a still into the surrounding atmosphere and in cracking processes the temperature is 750 to 850 F., and' even higher; hence the manifestdanger of cracking petroleum oil under such high pressures. 1

The resent invention relates to a process of' cradkingpetroleum and distillate in a still such as the still used in the Burton process, but which eliminates the production of coke on the walls of the still, thereby ob v-iating all danger due' to the weakening offthe steel at .the points where thecokeusually accumulates;

e Another fact'brou'ght out in the Burton process is thatthe deposition of coke '.011'

vertical heating surfaces is very. much less, being about one-third to one-fifth. of the amount deposited'i'on the upper side of a horizontal surface, such as an ordinary still bottom, in a given length of time.

An object of my invention therefore is to provide a heating element for the cracking ofpetroleum-and distillates in which the heating surfaces are practically all vertical,

thereby eliminating the de to an appreciable extent.

Also, in thepetroleum cracking industry,

it has been shown that the'ratio between the volume of oilheated and the area of the heating surface of the apparatus employed is an important factor. This relation may position of coke perhaps be moreclearly understood if it is approximately proportional to .theheated surfacein contactwith the oil. v

Another important object of my :inven- .tion is the \provision of means, whereby a.

thin film of oil is always maintained in contact with the heating element and the heating element itself is constructed so that a maximum amount of heating surface is provided in a minimum amount of volume of the heating element. 7

A furtherobject of my invention is the provision of means whereby part of the heat generated for the cracking of the distillate is electrically produced, and this is accomplished by means of a high frequency, high voltage current which produces eddy currents of great amperage which generate the heat in a heating element contained in the stiil'itself. 1

Astill further object of my invention is to provide a method of utilizing any excess heat which-is generated'by my process in heating an additional quantity of oil for a succeeding process of fractional distillation or cracking in another still.

" Another object of the invention is the use. of a high voltage, high frequency current of small amperagewhich results in the production of an: oscillating magnetic field through which the oil passes, and this produces a high molecular tension in the oil,

causing the 'molecules of the heavier hydrocarbons to break down or'crack with greater ease and also tends to the practical" elimina tionof theproduction of fixed gases.

- this invention will be apparent from the disclosures in the drawingsand specification.

The invention (in a preferred form) is illustrated in the drawings and hereinafter more fully described.

On the drawings: Figure 1 is 'a side elevation of an ap aratus constructed in accordance with my 1nvention? v -Figpre 2 is an enlarged side view, partly in section, of a single still head showing my particular cracking cells installed therein. Figure 3 is asectional view of a cell taken on the line 3-3 of Figure 2. Figure 4 is a sectional view of the same cell taken on theline 4-4 of Figure 2.

Figure 5 is another sectional view of the cell taken on the-line 5-5 of Figure 2 with parts in elevation.

As shown on the drawings: The apparatus consists essentially of a still 6 connected by suitable piping 8 to a condenser 10 and a receiver 12 for the condensed product, all' connected in an air-tight manner and adapted to be operated under pressure. A gas vent 14 is provided in the .receiver in order'to permit the escape of accumulated gases .if the pressure in the system should rise above a predetermined point. v

The'still 6. is suitably set in a foundation 16, made of brick or concrete,,or any suitable material, to permit of the still beingheated by a coal or gas fire in the usual way, a furnace therefor being provided at 18 and a fiueat 19. The temperature in the still and vapor delivery pipe is maintained at about the end, boiling oint of gasoline which is a variable factor ependent upon the pressure .on the system. Located within the still and adjacent the bottom thereof are what I term the cracking cells or chambers, which constitute the ch ef elements of my invention,.andone or more are installed in each still" according to the capacity thereof.

These cracking cells consist of an outer double-walled jacket "20 of metal having communicating therewith pipes 22 and 24, whlch extend out .of the still proper and permit of circulating a fluid medium through said jacket for pur oses of temperature regulation and also for heat exchange. This jacket is constr cted with an external hood 26, the edge of which extends below a series of openings 28, communicating between the interior chamber enclosed by the double-walled jacket 20 and the interior of the still properr This hood is designed to fill with the vapors of the low boil-. ing point products as they are formed within the interior of the cracking cells 20 and the vapors prevent the flow of liquid oil'through the cell by thermo-siphonic action. Oil enters the cell through the holes 30 near the within the cell.

- provided with holes 30 near the base, which permit the easy entrance of oil from the still to replace that which is cracked and escapes as a vapor through the upper holesand under the hood. The walls of these holes 30 may be inclined upwardly and inwardly to .80 prevent the backing up and escape there'- through of the more highly heated rails WVithin the chamber enclosed by the double-walled jacket 20 is placed a coil of metallic tubing or suitably constructed stranded wire cable 32 consisting of 'a number of turns in the form of a helix, one end 34 of which is grounded to the chamber or to the still in a suitable manner to conduct electric current, and the other end of this coil passes through an insulating bushing 36 of porcelain'or other suitable material located in the sides or top of the jacket and thence is electrically connected by a cable 38 through .95 another insulating bushing 40 in the still or still head to the external electrical apparatus which forms an important part of this invention. Within the helical coil 32 contained in the cracking cell and supported by 1 an insulating base 33 of orcelain or the like is a bundle of loosely ound rods or metallic wires 42, whose length runs vertically through said coil or helix. The spaces be tween these rods or wires constitute the 'areat in which the cracking effect is induced in the oil body, and byreason of the great heat generated, the large surface area presented, and the thinness of the sheets of oil, I

cracking is effected with great rapidity and of a spark gap 44, a condenser 46 and a volt- 12 age transformer 48 suitably connected to a source of alternating current through a manually operative variable reactance regulator or-pa1r of choke coils 50 and 52, the whole designed and so proportioned as to 1 produce a high frequency oscillating electric current through the condenser 46, spark gap 44, connecting leads 54 and 56 and the helix 32 enclosed by the double-walled jacket 20 of the cracking cell. 7 13o A blowout pipe for the cell is provided at 58, which communicates with the interior of the cracking cell and is adapted to allow the escape of the oil within the crackingv cell at desired intervals. Any'free carbon liberated'during the cracking process exists as.a .finely divided suspension and is practically confined within the cracking cell. 1 The blowout pipe offers a means of removing this at intervals without the necessity of checking the operation of the still,'the free carbon mixed with the oil being ejected as a sludge. The distillates to be cracked into gasoline are fed into the still by a pipe, and the level of the oil in the still is maintained "'atm con'stantvalue, this being determined by means of the gauge 62, the pressure bein% determined and regulated by gauge 84 an safety valve 86, while a thermometer is provided at 88.

The operation is as follows: Oil or distillate, preferably the latter, having been introduced into the still by means of the pipe 61, is heated therein by externally applied heat in the furnace 18 until a temperature and pressure approximating that of the end point of gasoline 'at the. given pressure is attained. Then the transformer 48 is brought into operation and comparativelyQlow voltage currents of great amperage are thereby induced in the bundle of rods or wires 42, these high amperage currents beiiig called eddy or Foucault currents. The passage of the current of high frequency through the helix 32 induces these eddy or Foucault currents in the bundle of wires 42/, which are preferably made of iron or copper, but may be made of any suitable material, and metals acting as catalyzers,

such as nickel, are especially advantageous;

with some classes of oils. These eddy currents result in the production of great heat,

art of which heat is due to hysteresis. urther, the high frequency oscillating 45 magnetic field produced around the helix 32 passes through the thin films of oil surrounding the rods or wires of the core 42 andresults in the production-of a high molecular tension in the oil. This molecular tension, together with a suitable heattand a proper pressure maintained on the system,

causes the molecules of the heavier hydro-.

' V carbons to break down or crack with ease into low-boiling point hydrocarbons of the saturated class, and the production of fixed gases is very low.

, formed.- these being vapors at the temperature of the" surroundingoil in j the still proper, escape untler the edge of the'hood,

As thelow boiling'point "products are the core of-rods 42, which ossessa boiling polnt above that of.the desired product, are condensed by contact with the double-walled jacket through which is circulating a suitable medium at the correct temperature to ,70 absorb this excess heat, and if any vapor escapes under the hood with the vapors of said product it becomes condensedwithin-the oil in the still during its upward passage through the same. In either event, all of the vaporized products with a boiling point above that of the desired end point for a glven pressure are eventually returned to the cracking cell for further treatment.

I propose, in cases where it may be feasible, to pump crude oil through the double walled jacket 20, asshownin Figure 1, by means of the pump 60 and pipe 22. This 011, after cooling the vapors in the cracking cell, will emerge through the outlet pipe 24 8 and will then be conducted to an ordinary straight run still 66, which still is provided with a pipe68 leading to a condenser 70 and a receiver 72, liketvise provided with a vent pipe 74:. This crude oil, after being introduced into the still 66, will, with a slight addition of heat, be fractionally distilled and the gasoline and kerosene cuts made. Thus the excess heat-of the cracking cell' transferred to this oil by means of the double-walled jacket can be made to serve a useful purpose in preparing the crude oil for further cracking treatment and-in removing its originally contained gasoline and kerosene. Theworking pressure of the systemmay vary in practice from a few pounds gauge to as much as 80 pounds gauge, dependent upon the origin and-nature of the oils being treated and the characteristics of the product desired. The input of electrical energy is conveniently regulated by the adjustment of the variable reactance regulators 50 and 52, and in practice electrical energy may be raised from the zero point until a maximum amount of gasoline is distilling over associated with a minimum amount of fixed gases.

It will ,be seen that herein is provided a new and novel means for continuously cracking petroleum and distillates in which the heat applied to the distillate is electrically generated and highly concentrated, thereby eliminating practically all of the troubles due to the accumulation of carbon in the still, and further taking advantage of the high molecular tension due to the passage of the high frequency electric current which aids to break up the hydrocarbon molecules. Also, by this apparatus the troubles and danger due to the deposition of'hard flinty coke on the walls of'the still are completely avoided and the fact that coke does not so readily accumulate on a vertical heating surface is taken advantage of'in a highly eflicient manner. Another beneficial result is attained in the conservation of fuel by the heat exchange apparatus, in which the crude oil used in one stillas a condensing medium is keptheated and by a further slight addition of heat is then fractionally distilled in a second still. Further economyofheat is effected, because in the operation of an ordinary crackingstill, so much excess heat must be applied that a great many heat units are dissipated and lost, while in this process only a moderate heat is applied from the outside of the still, beingthat'necessary to bring the contents to about 410 F. at atmospheric pressure, and the additional heat necessary to effect the cracking is developed directly inthe cracking cell and is therefore highly concentrated with a minimum of loss.

I am awarethat many details inthe construction and operation of both the cracking and electrical apparatus may "be varied through a wide range, and'I therefore do not desire to limit the patent, when granted, otherwise than is necessitated by the prior art. y

I claim as my invention:

1. In an apparatus for cracking oil by heat and pressure, a multitude of closely situated vertical metallic surfaces and means surrounding them for electrically heating the same.

2. In an apparatus for cracking oil coniprising a gas-tight,still, a condenser and a receiver, a heating element including abun dle of metallic rods within the still surrounded .by a helix adapted to carry high frequencyelectric current.

-3. In an apparatus for cracking oil including a still and a furnacefor heating the still eXternally,-an velectrically heated cracking cell in the still, a hood enclosing the up per portion. of the cell, andmeans for automatically returning any vaporized products having a boiling point above that of the desired product to the cell for further treatment. 5

4. In an apparatus for cracking oil comprising a gas-tight still, a condenser and a I receiver; a heating. element including a bundle of metallic rods within the still, surrounded by a helix adapted to carry high frequency oscillating current, and a generator for such current including .a condenser and a spark gap.

5. In an apparatus for treating oils insubscribed my name.

' CARL M. PAGE.

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