US2001187A - Process for treating hydrocarbons - Google Patents

Description

May 14, 1935. c. P. DUBBS v PROCESS FOR TREATING HYDROCARBONS Original Filed Sept. 2 1926 2 Sheets-Sheet 1 May 14, 1935'. c. P. DUBBS PROCESS FOR TREATING HYDROCARB ONS Original Filed Sept. 20, 1926 2 Sheets-Sheet 2 I. I LZ I I l l I l i lllllll llanl fl n H H I LHx I l I I N U H l L H H l Patented Mayl4, 1935 ITED STATES mar other 1 PROCESS" FOR TREATING HYDRo'oARn'oNsj 1 Claim.

This application is a continuation of my application, Serial No. 136,426, filed September 20,- l9260 In ,the conversion of high boiling point pa.

,5; troleumsinto lower boiling point petroleurns by subjecting such: petroleum to the action of heat underpressure, it is believed that the total coke produced is from two causes, namely-that part of the coke is produced from the splitting or breaking up of portions of higher boiling point oils into the desired; lower boiling point oils and that the rest of the coke is produced by main taining the heavy liquid residue from'the above reaction, separated fromxthe lower boiling point 1 products produced, at a temperature which causes a. substantial portion of this heavy liquid residue to be converted to coke-like bodies, and it seems that this temperature can be substantially below that point at which any substantial portion of the heavy oil will be converted into theydesirable-lower boiling point oils, such as commercial gasoline. Whether the above is true or not, I have found that as soonas thefirst reaction is overiconversion of the higher boiling point hydrocarbons into desirable lower boiling point oils) that by immediately reducing the temperature of the heavy liquid residue, the formation of coke is substantially arrested and the total amount produced is materially below that produced when the temperatureof said liquid residue is not immediately substantially reduced. 1 It is a well known fact that the heavy oils, or the heavier portions of thelighter oils, produce a great deal morecoke for a given amount of cracking than do the light .oils or lighter ends of the oil. For instance, there is a great deal more coke produced by cracking a 10 Baum gravity California oil to produce 25% gasoline than there is from producingthe same amount of gasoline from cracking a 24 Baurn gravity Galifornia oil; therefore, it is of great economic valuetohave a process and apparatus that will utilize the heat contained in a cracked light oil f to automatically separate the light from the heavy ends of another oil, and permit of the withdrawal of the heavy'ends of this oil along with the heavy endso-f the cracked oil, thus avoiding over-cracking or superheating of the heavy ends of the oil, thereby avoiding a heavy production of coke. l

,There are various methods of accomplishing the abovelobjects and my invention covers broadly all of the; variousmethods. In the following 5;; description, there is setforth an economical: and

(or. rec 5s) practical method and apparatus, suitable for;accomplishing these objects and it will be understood that the particular apparatus I have shown is smceptible of wide changes and still be within the principle taught in this invention.

In the drawings, Fig.1 and Fig. 1A. are a side elevational schematic or diagrammatic View, partly in vertical section of an apparatus in which the process may be carried out.

? .Those versed in the art will fullyunderstand the methods of calculatingto determine the sizes of the different parts of apparatus suitable for the particular operation they maydesire tofollow in the use of this process.

I wish to particularly point out that this process issusceptible to wide variations: as to t'e'm peratures and pressures used, which are of great value to the industry, as theypermit the'operationof the plant to be varied to suit the particular needs of the refiner for his particular market and conditions, and also for the various oils used in this art. l

. The following description will illustrate a; methodby which the purposes of the present invention can be accomplished. The oilto be treated is drawn from any suitable source (not shown) through lines l and 3, having. pump 2 -inter-, posed therein. From line 3, the oilmay be forced through lineB by opening valves 5 and I (valve 8 being closed) through the heat interchanger. 9, which may be of any suitable design.- "The preheated oil may then pass through valve lll; back into line 8, through. valve ll, being dis.- charged into the dephlegmator 12. .This clephlegmator may be of anydesign suitable for producing the desired results.

As it passes through theheat interchanger 9,

the charging stock is preheated by the hot vapors being cooled therein. After being 'discharged' into the dephlegmator l2, through line 6, it. is further'heated by intimately commingling :with the hot vapors and condensate therein't- This vaporizes the gasoline content of the charging stock, said'v'aporspassing out of the dephlegmator lii with the'low boiling point :vapors'pro-' duced by cracking the toil as will be later de' scribed. 3 l l These vapors pass out through vapor outlet l3; controlled by valve I3, through lheat interchanger 9, thence through lineI4,"controlled by valve I4, into condensing coils l5, contained in condensing box It, where condensation takes place, the condensed liquid pa'ssing 'throug'h line H, controlled by valve l1, into distillate receiving tank [8 provided with liquid draw-oil lihe 'l 9,

controlled by valve 20; 2| is a pressure gauge and 22 is a liquid level gauge. The uncondensable gas is led off through line 23, controlled by valve 24.

The unvaporized portion of the raw oil, continuously injected into dephlegmator i2, mixes with the reflux condensate produced in said dephlegmator i2, said mixture collecting on the dividing partition plate 25 being withdrawn through line 25, controlled by valve 21 (valve 30 being closed) and discharging into the lower part of dephlegmator l2. The plate 25 divides the dephlegmator into upper and lower compartments or sections. From the lower section of the. dephlegmator, the oil is withdrawn through line 28, controlled by valve 29, into line 3|, controlled by valve 32 (valve 33 in line 38a being closed) into pump 34 (valve 35 being closed in line 36). The pump forces the oil through line 38, controlled by valve 39, into line 38a (valve 31 in line 5| being closed), valve 39a being open, the oil discharging into line 43, from which it passes through heating tubes 4|, positioned in a suitable furnace 42.

The oil as it passes through tubes 4| is brought to a conversion temperature of, say 150 to 1200 F., more or less. The heated oil is then transferred through line 43, controlled by valve 46, and discharges into reaction chamber 41 where reaction occurs. The products of reaction are discharged together from the lower end of reaction chamber 41, through line 48, controlled by valve 49. From pump 34 to control valve 49, in this particular run, the pressure will be, say from 50 to 1200 pounds, more or less, according to the oil being treated and the results desired. Beyond the control valve 49, the balance of the apparatus may be at a reduced pressure, down to or sufiiciently above atmospheric to control the flow of material in the different parts of the apparatus.

The products of reaction from chamber 41 may pass through line 5!! into line 5|, valves 52, 53 and 54 being closed. Valves 53 and 54 on lines 55 and 55 are for use should valve 49 clog up, in which case, either line 56 and valve 53, or line 55 and valve 54 can then be used. Valve 51 is left open, and .the products of reaction discharged into what may be termed a separator chamber 58. Any hydrocarbons in liquid form discharging into separator chamber 58 are immediately reduced in temperature, due to the fact that a portion of their heat is constantly used to convert these liquid hydrocarbons into vapor, the amount so converted into vapor being dependent of course, upon the amount of latent heat contained in this oil when the pressure is reduced. In this manner, I substantially prevent the excessive formation of carbon from the second reaction in chamber 58.

If all of the volatile portion of the oil being treated is converted into vapors, then the greatest amount of coke will accumulate in separator 58, while a small amount of coke will accumulate in reaction chamber 41. Therefore, these should preferably be built in proper proportion, according to the operation desired on any particular plant.

When it becomes desirable to remove the coke and clean the separator chamber 58 and reaction chamber 41, the manheads 59, 68, BI and 62 are removed after the plant has been properly cooled and the coke is preferably removed through lower manholes 5S and 62.

If there is a liquid accumulation in separator 58, then the same is withdrawn through line 64, controlled by valve 63, and passed to suitable storage (not shown). Should this valve 63 clog, then valve 65 and line 66, or valve 51 on line 58 may be used. The vapors from the separator 58 pass out through line 59, controlled by valve 15, into the lower section of the dephlegmator i2, and as the vapors pass upwardly through the dephlegmator, they are cooled by the oil flowing downward through said dephlegmator. This condenses the heavier ends of the vapors, and this condensate with the unvaporized portion of charging stock may be drawn off through line 28, through valves 29 and 32, through pump 34, and returned through line 38a, valve 39a, line 40 to the heating tubes 4|.

The remaining vapors pass out through line l3, heat interchanger 9, line l4, condenser l5, line H, the condensed liquid collecting in receiving tank l3, as previously described. Should the vapors coming out of dephlegmator l2 through line l3, contain an undesirable portion of vapors having boiling points higher than those desired, these are condensed by taking some of the distillate collected in receiver l8 and passing it through line H, controlled by valve 1|, through pump 12 and line 14 (valve 13 being open), into the upper portion of dephlegmator i2 in such quantities as will bring about the desired result.

On the other hand, should the operation be such that the quantity of the charging stock preheated in the heat interchanger 9 results in excessive cooling, then portions or all of said charging stock may be diverted directly to the heating tubes 4| by the manipulation of valves H and 11 and such portion of charging stock not desired in the dephlegmator l2 can be passed through lines 11a. and 18, controlled by valve 80, to heating tubes 4| or, if it is desired that the charging stock be not preheated, or a portion of it not be preheated, then it may be discharged directly into the heating tubes 4| by obvious manipulation of valve 15, passing this portion of charging stock through line 16 into line 18 and into the heating tubes 4 l, valve 11 in this case being closed, Valve 19 in line 18 is normally kept closed, it being used only in cases of emergency to empty the plant of its oil content.

If in a particular operation it is desirable to bring the oil to a temperature within the above described ranges, that is, 750 F. to 1200 F. in the heating tubes 4! and maintain the oil under a range of pressure already described, i. e, 50 to 1500 pounds to the square inch up to valve 49, and this results in an excessive quantity of oil being vaporized in separator 58, and it is desirable to have a greater portion of the hydrocarbons being treated, collect in the form of liquid in separator 58, this can be brought about by directing the necessary quantity of cold charging stock from pump 2, through valve 15, line 15 (valve 11 being closed) into line 18 (valves 19 and 86 being closed), through line 8|, (valve 52 being opened). Thus the charging stock is injected into the hot products of reaction passing through line 5| and brings about the desired cooling. This results in the heavy ends of the products of reaction being collected as a liquid in separator chamber 58, and in addition, all but the heavy ends of the charging stock are evaporated leaving these latter heavy ends as a liquid. The liquid may be withdrawn through line 64. It will be found that this withdrawn residue is comparatively free of any solid matter, and is a suitable fuel for marketing purposes.

separator chamber58, the lighter ends of the charging stock are vaporized and thus separated from the; heavy; ends. Only the former eventuallygo to the cracking tubes 4 I, while the heavy ends are withdrawn from the bottom of separator-58 as-residuum which is of great economical value, as it is these heavy ends that producea great volume of the coke when subjected to cracking.

One versed in the art will readily understand that no absolute temperatures or pressures can be laid down suitable for all oils and conditions, but that a few preliminary runs will give the best operating temperatures and pressures for the particular oil to be used and products desired.

I desire to call particular attention to a condition of operation in which it is desirable to heat the oil as it passes through the tubes to a relatively low temperature, that is, for that particular oil the temperature used will result in a low conversion into the desired low boiling point products. If the apparatus throughout is maintained under a uniform pressure, there will not be sufiicient oil vaporized or vapors entering dephlegmator 2 to furnish sufficient volume of condensate in the dephlegmator for return to the heating tubes mixed with a fresh supply of raw oil. This portion of reflux can be increased by proportionately decreasing the pressure on the separator 58,.a higher pressure being maintained on the reaction chamber 41 and heating tubes M by manipulating valve 43. Under these conditions, the decrease in the pressure on separator chamber 58 proportionately increases the amount of treated oil that can be withdrawn from this separator chamber in the shape of vapors.

"Ifhere will be occasions when the particular oil being used and thedegree of cracking such that it will be desirable to by-pass the separator 58, in which case, valve 57 is closed and valve 82 in line 83 opened. Valve in line 69 is closed, thus making the discharge from reaction chamber 41 directly into thelower section of dephlegmator l2, in which case, valve 2'! may be closed and valve opened. The condensate collecting in the lower section below pan 25 falls to the bottom of dephlegmator l2 and joins any unvaporized hydrocarbons entering the lower section of dephlegmator I2, being withdrawn and passed through line 28, valve and line 36 to suitable storage. This withdrawn liquid will be found to be a very high grade fuel with very little, if any, solid matter. The remaining vapors pass up through pipes 85 into the upper section of dephlegmator l2 and as they pass through the upper section of dephlegmator l2, the heavier ends are condensed, collecting on pan 25 along with any unvaporized oil injected into the dephlegmator above pan 25. ZThis liquid oil is drawn oil through line 26, valve 30, line 3i,

valve 32, and by pump 34 is forced through line 38, valve 39 (valve 33 being closed) line 38a, valve 39a, line 40 into heating tubes 4|. The remaining vapors pass from the top of dephlegmator IZthrough line I 3, as already described.

The particular dephlegmator that I have shown, may contain two reboiling pans marked 84. These are for the purpose of' catching the condensate and forming a pool in the path where the vapors are the hottest, these vapors tending to boil the light ends that may be contained in obtained by lower pressures.

Perforated pans 86 are also shown. It will be understood that one or a series of dephlegmators may be used of any desired design and size. 92 and 93 are liquid level gauge glasses. 84 are liquid try-cocks. g

The parts of the apparatus to be insulated to prevent loss of heat by radiation are indicated by broken lines. d j

To a certain degree, the percentage of a particular oil passing through the tubes that can be cracked into the desired low boiling point products without depositing a substantial amount of carbon in the tubes, is dependent upon the pressure maintained on the oil, that is, the percentage of cracking can be increased to a certain extent by increasing the pressure. Hence, those versed in the art will be governed as to what pressure they shall select for their particular operation.

I have also discovered the fact that in cracking oil commercially, it is of very great importance to mix the heavier ends of the condensed vapors of a previous cracking operation with theraw oil and subject this mixture to cracking heat. It will be understood that while increased pressures permit more cracking of the oil in each passage through the tubes, that the same result can be accomplished by mixing more of the heavy condensed ends of previously cracked oil with the raw oil. As this mixture passes through the tubes, it should be maintained at a lower pressure and not subjected to as high a degree of cracking as when using a higher pressure. By repeatedly recirculating the heavy ends of the vapors of a Another point Iwish to particularly cover in this application is, that by varying the degree of pressure on the separator 58 by valve 10, the rates of vapor to liquid withdrawn from separator 58 can be varied. There will be certain operations where this mode of operation is very advantageous, such operations being where the operator, desires to increase the amount of liquids withdrawn from separator chamber 58 over that There may be occasions when it will be found advantageous to maintain separator chamber 58 at the same pressure as reaction chamber 41. will be times when it will be found advantageous to operate the entire apparatus under a uniform pressure, in which case, the pressure may be controlled by the release of the uncondensable 'gas from receiving tank l8.

Having thus described my invention, what I claim is:

A cracking process which comprises passing hydrocarbon oil in a restricted stream through a heating zone and heating the same therein to cracking temperature under pressure, discharging the heated oil into the upper portion of a vertically elongated reaction zone maintained under cracking conditions of temperature and pressure, passing both vapors and liquid oil downwardly through the reaction zone and re- Likewise, there portion of the reaction zone, simultaneously advancing a continuous stream of charging oil toward the process under a mechanically applied pressure, dividing the stream of charging oil into separate portions and commingling one of these portions with the mixture of vapors and liquid oil Withdrawn from the lower portion of the reaction zone, separating the thus commingled hymoving the same as a 'mixture from the lower drocarbons into vapors and residue in a separating zone maintained under lower pressure than the reaction zone, fractionating the separated vapors in contact with another of said portions of the charging oil stream, supplying the resultant mixture of reflux condensate and charging oil to the heating zone, and finally condensing the fractionated vapors.

CARBON P. DUBBS.

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