US2032846A - Cracking apparatus and method of operating the same - Google Patents

Description

March 3, H936, D. 1 JACOBS Err AL.

CRACKING APPARATUS ND METHOD OF OPERATING THE SAME Filed oet. 1o, 1932 Patented Mar. 3, 1936 UNITED STATES PATENT OFFICE CRACKING APPARATUS AND METHOD F OPERATING THE SAME Donald L. Jacobs and Eddie M. Dons, Tulsa, Okla.,

assigncrs to Mid-Continent Petroleum Corporation, Tulsa, Okla., a corporation of Delaware Application October 10, 1932, Serial No. 637,014 3 Claims. (Cl. 196-47) This invention relates to cracking apparatus pors passing from the reflux condenser are prefand methods of operating the same, and more erably superheated before they enter the power particularly to the conversion of high boiling plant, and we have shown how this may be acpoint hydrocarbons into low boiling point fraccomplished without any additional cost in the tions. One of the objects of the invention is operation of the cracking system. 5 to produce a highly efiicient system of this kind The specific combination .and arrangement of wherein the several elements of the system coelements herein disclosed enable all of these reoperate with each other to establish and mainsults to be accomplished in a simple manner, tain all of the varying conditions of pressure and and the several elements cooperate with each temperature at a relatively low cost. other to provide the high efficiency while main- A further object is to subject the hydrocarbons taining the desired conditions in each element to the desired pressures in a cracking zone and of the cracking system.

reux condenser, and to accomplish this in a The drawing is a diagrammatical view of a feasible and economical manner, while subjectcracking system embodying the features of this ing the cracked vapors to a combination of coninvention. ditions whereby they are effectively utilized to i designates a furnace containing a cracking increase the efficiency of the cracking system, coil 2 wherein astream of hydrocarbons is heated Without in any way impairing the functions of to a cracking temperature while subjected to the reflux condenser. pressure transmitted from a pump 3 which forces With the foregoing and other objects in view, the stream into the cracking coil. the invention comprises the novel method, con- The cracked mixture discharged from the coil struction, combination and arrangement of parts 2 is conducted into a separating chamber 4 where hereinafter more specifically described and illusthe residuum is discharged through a pipe 5 protrated in the accompanying drawing, wherein is vided with a valve 6 to regulate the flow while shown the preferred embodiment of the invenmaintaining the contents of the separating chamtion.. However, it is to be undertsood that the ber under pressure.

invention comprehends changes, variations and The residual oil and carbonaceous material are modifications which come within the scope of the thus separated from the vapors which pass from claims hereunto appended. the separating chamber through a pipe 1 ex- In the preferred form of the invention,astream tending into a reflux condenser 8 where the 30 of hydrocarbons is conducted through a crackvapors are cooled to condense the high boiling ing zone where it is subjected to the desired heat point fractions. The reflux condensate falls to and pressure, the cracked mixture being transthe bottom of the condenser 8, while the low mtted into a separating chamber Where the vaboiling point fraction in the form of vapors is pors separate from the residuum and pass into discharged through a pipe 9 at the top of the 35 a reflux condenser. The vapors are cooled while reflux condenser and conducted to a nal conunder pressure in the reflux condenser, to condenser I0, as will be hereafter described. dense the high boiling point fractions and return The fresh charging stock, such as gas oil, or them under pressure to the cracking zone. The other heavy hydrocarbon liquid, may be forced low boiling point vapors pass from the reflux coninto the reflux condenser through a pipe I0', so 40 denser under pressure, and thence through a as to commingle with hot vapors and reflux conturbine, or other fluid-actuated power plant. densate. The cool charging stock is thus prewhere their pressure is converted into mechaniheated, and a mixture of the hot reflux concal energy. Vdensate and charging stock collects in a pool at Since the readily condensible vapors are conthe bOt'GOm 0f the reflux Condenser. A Dip@ l'l 4 densed in the reflux condenser, without passing extends from this D001 w the inlet 0f the pump into the power plant which receives the low boil- 3, -and a Pipe l2 COHIIGCS the Outlet 0f the Dump ing point vapors, it will be understood that the t0 the inlet O the Cracking C01 2. vapors entering the power plant are clean and As an example of operating conditions desirfree of the more readily condensible fractions. A able for intense cracking, we will now set forth a 50 relatively simple turbine can, therefore, be emspecific example, but it is to be understood that ployed to convert the waste energtT into mechanithe invention is not limited to the details of this cal power. illustrative example.

As a further step to eliminate, or reduce, the The mixture of reflux condensate and charging condensation in the power plant, the cooled vastock may be delivered to the pump 3 under a 55 pressure of about 200 pounds per square inch and under a temperature of about 750 F. The pressure of the pump may be great enough to discharge the hot mixture to the inlet of the cracking coil 2 under a. pressure of about 300 poundsper square inch, or any other desired high degree of pressure.

The mixture to be cracked will thus be subjected to a high pressure in the cracking coil, and the temperature of the stream may be increased from about 750 F. at the pump 3 to about 875 F. at the discharge end of the coil.

The contents of the separating chamber 4 may be maintained at a temperature slightly lower than 875 F. and under a pressure of about 209 pounds per square inch to permit separation of the vapors from the residual material. This pressure is continued through the reflux condenser to a power plant I3 where the pressure is reduced to maintain the nal condenser I 0 under about atmospheric pressure.

The cracked product is thus condensed at atmospheric pressure, while the reflux condenser and separating chamber are maintained under any desired higher pressures. The mixture of reilux condensate and charging stock is discharged from the reiiux condenser and conducted through the pipe II under the pressure maintained in the reflux condenser.

The power plant I3 is preferably a fluid-actuated turbine having an inlet pipe I4 connected to a superheater I5, and a discharge pipe I6 connected to the nal condenser IU. A by-pass I1 connects the pipe I4 to the pipe I6, as shown in the drawing, so that the vapors can be discharged to the i'lnal condenser, without passing through the power plant. The pipes I4, I6 and I1 are provided with valves I8, I9 and 20, and an additional valve 2l may be interposed between the nal condenser and the discharge end of the by`pass I1; l

The superheater I5 comprises a chamber interposed between the pipes 9 and I4 to receive A the cooled vapors passing from the reiiux condenser 8 to the power plant I3. As a diagrammatical illustration of a means for indirectly transmitting heat to these vapors we have shown a coil 22 located in the superheater and having its discharge end connected to a condenser 23. Relatively hot vapors are conducted to the coil 22 by means of a pipe 24, and these hot vapors may be obtained from another part of the system. To illustrate this feature, we have shown an evaporating chamber 25 connected to the Vresiduum pipe 5 .and also connected to the vapor pipe 24. The pressure-reducing valve 6 in the pipe 5 is regulated to maintain the desired high pressure in the separating chamber 4 while the evaporator 25 is maintained under a pressure only slightly above atmospheric pressure. In response to this reduction of pressure, the volatile constituents of the highly heated residuum are vaporized, and the hot vapors pass through the pipe 24 to the superheating coil 22, and thence to the condenser 23. The temperature of these hot vapors will be relatively high, for example, about 750 F. The cooled vapors leaving the reux condenser at a temperature of, for example, 460 F., are, therefore, superheated to effectively transmit energy to the power plant I3, without 'undue condensationwhich would otherwise result from the work performed and the reduction of pressure at the power plant.

During the normal operation of the system, the valve I9 -in the by-pass I1 may be closed, while the valves in the pipes I4 and I6 are open. The power plant I3 will then be operated by the superheated vapors.

In starting the system, the valves I8 and 20 in the pipes I4 and I6 are preferably closed, while the valve I 9 in the by-pass is open, and the valve 2I in the vapor line is also open. Cool charging stock may be admitted through the pipe I0 at the reiiux condenser and conducted therefrom through the pipe I I to the pump 3, said pump being operated from any suitable source of power to force the charging stock in an endless course through the heating coil 2, and into the separating chamber 4 from which it returns to the pump by passing through a pipe 26 leading to the pipe I I. The circulation in this endless course results in a gradual heating of the charging stock, the air and water vapors being expelled through the Valve I9 in the by-pass I1 leading to the iinal condenser I0.

Thereafter, as the temperature and flow of vapor increases, the valve I9 is adjusted to gradually increase the pressure and establish the normal operating conditions. When the required pressure and velocity is obtained in the by-pass I1, its valve I9 is closed, and the valves I8, 20 f and 2I in the pipes I4 and I6 are opened to start the power plant I3. The admission of charging stock through the pipe I0 is continued, the Valve 21 in the return pipe 26 is closed, and the residuum valve 6 is opened during the normal running conditions. After these conditions are established, mechanical power is produced at the power plant I3, and such power may be employed for any desired purpose. For example, a portion of this power may be transmitted through a clutch 28 to a pump 29 which forces the charging stock into the system.

To maintain the predetermined degree of pressure in the reiiux condenser 8 When the conditions in the power plant I3 would permit a rela.- tively free escape of vapor, the valves I8 and 20 may be selectively adjusted to provide the desired conditions, and whenever necessary or desirable,

the valve I9 in the by-pass can be regulated to divert a portion of the vapors from the power plant.

We claim:

1. In ,the art of cracking hydrocarbon oils, the method which comprises cracking and Vaporizing a hydrocarbon oil under pressure, cooling the resultant cracked fluid under pressure to condense the fractions having relatively high boiling points, indirectly superheating .the remaining vapors by transmitting heat from the resultant cracked fluid formed during the cracking operation, reducing the pressure of the superheated vaporsV while transmitting them through a huid-actuated power plant to convert the vapor pressure into mechanical energy, and condensing the vapors discharged from said power plant.

2. In the art of cracking hydrocarbons, vthe method which comprises conducting a stream of hydrocarbon oil through a cracking Yzone Where the oil is subjected to a cracking operation Iunder pressure, transmitting the cracked mixture into a separating chamber whererthe vapors while under pressure separate from the hot residuum, withdrawing residuum from said chamber and reducing the pressure on said Withdrawn residuum to vaporize its volatile constituents, conducting vapors from said separating chamber and cooling them Yunder pressure to condense the fractions having relatively high boiling points, indirectly transmitting heat from said volatile constituents to the cracked vapors not condensed during said cooling operation while preventing a mixture of said Volatile constituents and cracked vapors, so as to superheat said cracked vapors, reducing the pressure of said superheated cracked vapors while transmitting them through a uid-actuated power plant to convert a substantial portion of the pressure into mechanical energy, and condensing the vapors discharged from said power plant.

3. In an apparatus for cracking hydrocarbons, .a cracking means wherein a stream of the hydrocarbons is subjected to a cracking temperature, a nal condenser wherein the cracked product is condensed, a reux condenser between said cracking means and final condenser, a separating chamber interposed between said reflux condenser and cracking means to separate the residuum from the vapors, an evaporator connected to said separating chamber to receive the hot residuum, a pressure-reducing valve interposed between said evaporator and separating chamber to permit free vaporization of the volatile constituents of the hot residuum, a pump connected to the inlet of said cracking means to provide a high pressure therein, means for conducting reux condensate and charging stock to said pump to maintain said high pressure, a power plant to maintain the desired pressure in the reux condenser, said power plant being interposed between said reux condenser and nal condenser to obstruct the cracked vapors passing from said reux condenser while converting their pressure into mechanical energy, a superheater interposed between said reflux condenser and nal condenser to superheat the cooled vapors before they enter said power plant, and a vapor conductor connecting said evaporator to said superheater so as to transmit heat from the vaporized constituents of the remsiduum to the cooled vapors passing from said reux condenser. 20

DONALD L. JACOBS. EDDIE M. DONS.

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