US1615384A - Art of pyrogenetic conversion of hydrocarbon oils - Google Patents

Description

11. 2 1927. F. A. HOWARD ET AL ART OF PYROGENETIG CONVERSION OF HYDROCAiBON OILS Filed May 23, 1921 4 Sheets-Sheet 1 WW) i r 1 HJHHUHHWHH wfl a I i, QN m m m rkfl .Q E L km 2% I. n

4 Sheets-Sheet 2 lfl llllildllll R 1 firl 1 11 L rll l1 Jan. 25 1927.

F. A. HOWARD ET AL ART OF PYROGENETIC CONVERSION OF HYDROCARBON OILS Filed May 25, 1921 1 615 384 1927' F. A. HOWARD ET AL ART OF PYROGENETIC CONVERSION OF HYDROCARBON OILS Filed May 23, 1921 4 Sheets-Sheet 5 Jan. 25, 1927.

F. A. HOWARD ET AL ART OF PYROGENETIC CONVERSION OF HYDROCARBON OILS Filed May 23, 1921 4 Sheets-Sheet 4 .fizverzZom,

Patented Jan. 25, 1927.

UNITED STATES PATENT OFF 1,615,384 IC E.

FRANK A. HOWARD, OF ELIZABETH, NEW JERSEY; EDGAR M. CLARK, OF NEW YORK, N. Y.; AND JAMES R. CARRINGER, F ELIZABETH, NEW JERSEY, ASSIGNORS TO STANDARD DEVELOPMENT COMPANY, A CORPORATION OF DELAWARE.

ART OF PYROGENETIG CONVERSION OF HYDROCARBON OILS.

Application filed May 23, 1921, Serial No. 471,724, and in the Netherlands January 15, 1921.

The present invention relates to the pyrogenetic conversion of heavier hydrocarbon oils under pressure into lighter hydrocarbon oils, for example, of the character of gasoline, and will be fully understood from the following description thereof, illustrated by the accompanying drawings, in which Figure 1 is a view in side elevation of a still and setting suitable for carrying-out the invention, these being shown partly broken away and partly in section;

Figure 2 is an end elevation of the still and setting, viewed from the'right-hand end of Figure 1;

Figure 3 is a transverse vertical section' through the still;

Figure 4' is a longitudinal vertical sectional View through the still on line 4-4 of Figure 3; and

Figure 5 is a plan view of the still and setting partially brokenaway and shown in part in horizontal section.

Referring more particularly to the .drawings, the numerals 10, indicate spaced setting walls of suitable masonry construction within which the still and the heating chamber are enclosed. At each end ,of the setting there are formed fire-places l1 and 12, which communicate with a heating chamber 13 of suitable refractory construction, and which extends within the setting walls 10, 10 for the greater part of their length. This heating chamber is of approximately rectangular cross-section. The fire- places 11 and 12 may be provided with any suitable firing means, for example, the oil burners 14 and 15, respectively, and the combustion gases therefrom pass through the heating chambers. A shallow checker- work 16, 16 is arranged in the bottom of each of the tire-places, and openings 17 from the exterior to this chcckerork are provided for the admission of air. At each end of the setting, at approximately the point where the fire-places open into the heating chamber 13, flues 18 and 19 open, each of them leading to a main flue 20 leading to a stack (not shown). The dampers 21 and 22 are provided to close the fines 18 and 19. respectively, when desired.

Below the heating chamber 13, and outside of its walls, the two longitudinally extending drums 23 and 24 are provided. which are of'similar construction. Each of them of equal length are provided, one on each side of the median line through the heating chamber. These drums are of similar construction, each being provided with transverse partitions 28 which completely close the drum, thereby dividing them each into a plurality of short compartments. The drums 26 and 27 are with the drums 23 and'24, and the. intervals between the partitions in each of the drums are substantially equal. Above the drums 26 and 27, preferably between them, a longitudinal cylindrical drum 29, of substantially the same length as the previously mentioned drums, is suitably supported, for example, on the transverse beams 30 which are supported on the vertical beams 31. This uppermost drum 29 is provided with transverse partitions 32, 32, which ere tend from the bottom of thedrum to a point spaced from the top, whereby free com munication along the top of the drum is permitted. The partitions 32. 32 in the drum 29 are spaced apart a distance equai to the spaces between the partitions in the previously mentioned drums.

Referring more particularly to the group of drums comprising drums, 23, 2 1, 26 and 27, communicating heating tubes 33, 33 are provided which extend diagonally upwards through the heating chamber between the drums above and below the said chamber on ,opposite sides of the median line there through, that is, the tubes communicate from drum 23 to drum 27 and from 24 to drum 26. A set of such tubes is provided for each comparement between the partitions in the several drums. In addition for each such compartment, a large tube or pipe 34., which may be designated as a downcomer, ere tends from each of the upper drums to the lower drum on the same side of the. median line through the heating chamber, that is, from drum 26 to drum 23 and from drum 27 to drum 24. These (lowncomcrs 34, 34-. pass outside of the heating chamber 13, but.

inside of the settin wall 10. The two bottom drums 23 an 24 communicate with each other by the pipes '34 of which a considerable number, for example, two, are provided for each of the intervals between the artitions in said drums. From each of the drums 26 and 27 large communicating pipes extend to the top drum 29, there being at least one such communicating pipe for each compartment between partitions in the said drums. The drum 26 is provided near each end with a valved ipe 36, which may be designated as an over ow pipe. Pipes 37, provided with suitable valves.;37", enter the top drum 29 near each end, and may be designated as the feed pipes. Each of the lower drums 23 and 24- is provided with a draw- ofl pipe 38, 38, these connecting with a central bottom discharge crime 39. A vapor-line 40 communicates with the vapor space in the top drum- 29 and leads to a suitable runback or dephlegmator and condensing devices (not shown). It will be apparent that the partitions within the drums divide the still as a whole into sections in which the oil is confined, each of these sections having its corresponding heating tubes and downcomers, the vapor spaces of these sections communicating at the top and the oil-containing spaces communicating at the bottom.

In the operation of pressure cracking stills, wherein a heavy hydrocarbon oil is heated under sufficient pressure to maintain it in the liquid phase, to convert it into lower boiling oint hydrocarbons, such as gasoline, it is esired to prevent the exces sive formation of aromatic products to such an extent as to give dominantly aromatic characteristics to the cracked dist-illate or naphtha produced. In continuous tube cracking rocesses as hitherto practiced. and as istinguished from pressure-still cracking processes in which the vapors of the lighter converted hydrocarbons are withdrawn from the oil substantially as soon as formed, it has hitherto been the experience in the art that a product having dominant aromaticcharacteristics has been produced. These characteristics evidence themselves not only in the highly aromatic odor and yellow color of the distillate, but also in its pghysical characteristics, and particularly its aum gravit when considered with reference to the boilin point of the distillate and of its various i ractions. For example, in comparing a tube-cracked naphtha with a. pressure-still naphtha having a similar range of boiling points, the following is found: The tube-cracked naphtha had a.

Baum gravity of 49.9, the pressure still naphtha 58.9.: The odor of the tubecracked naphtha was highly aromatic, that of the pressure-still naphtha was gasolineiike. The acid heat developed by the tubecracked naphtha was 61' F, 19- per cent being absorbed by 66 Baum acid. The acid heat developed by the pressure-still 'naphtha was 24 F., 11 per cent being absorbed by 66 Baum acid. It is thus apparent that the tube-cracked naphtha, in addition to its aromatic odor, indicates its dominant aromatic characteristics by its greater density and the greater acid heatdeveloped. Tn the following specification and claims products of these types will be indicated as having dominant aromatic characteristics and as having dominant paraflinoid characteristics, respectively.

In accordance with the present invention, a heavy hydrocarbon oil is heated under pressure while flowing in a continuous stream through a heated zone, and under such conditions as to secure a cracked distillation product containing lower boiling pbint oils havin a dominant paraiiinoid character, as distinguished from the products of prior tube-cracking processes in which a distillate of dominant aromatic character was produced. In order that this process may be more clearly understood, it is hereinafter described as carried out in the apparatus which has been hereinbefore described in detail. The stock to be converted may be. for example, a heavy distillate of the character of gas-oil having a gravity of 32 to 34 B6. The stock is sup plied to the still through the feed-pipe 37 near one end of the drum 29, for example, near that end at which the fire-place 11 is located. The stock fills the drums and the communicating tubes flowing in the direction of the other end of the still. The still may be heated by means of either of the lireplaces 11 or 12, it being preferred that the i fireplace 11 be employed, so the combustion gases travel through the heating chamber 13 in the direction of flow of the oil through the device. The fine 18 is then closed and flue 19 opened. The-oil is divided by the partitions in the drums into units, each of which gives oil its vapors into the common vapor space in the top drum and communicates with the remaining units in the lower drums. The heat is so conducted as to bring the oil as rapidly as possible to a high cracking temperature at which the rate of this conversion into lighter hydrocarbons of the character desired shall not be less than 36 per cent per hour, that is, not less than 810 to 820 F. A temperature of 800 to 1000 F. is preferred. By causing the combustion gases to pass through the heating chamber in the direction of flow of the oil, this temperature is rapidly acquired by the oil undergoing treatment, and the residual heat of the combustion gases as they pass through the heating chamber maintains the oil at the desired temperature. As a result of the heatgm. an

the point of feed.

ing of the oil in the tubes within the heat ing chamber, a rapid thermocyclic circulation through the tubes is produced. The oil entering into the first compartment between the head of the drum 29 andt'he first partition descends through the. corresponding pipes into the corresponding compartments. in. the drums 26 and 27 and'throu h the tubes 33 and downcomers 34 into tie corresponding compartment in ' drums 23 and 24; The space left in the bottom of the drums for free communication the entire length of the drums permits the oil to travel the length of these lower drums and fill up the entire oil space in the still. When the' thermocyclic circulation has been established, the oil in the lower drum in the interval between any two partitions therein flows rapidly upward through the tubes 33 to the corresponding intervals or compartments in the drums 26, 27 and 29, a downward flow being established through the j downcomers 34.- There is thus a rapid circulation in each unit of oil through the heated zone and of'oil from each unit to the succeeding one. The vapors of lighter hydrocarbons produced during the passage of the oil through the heated zone are substantially immediately evolved, passing out through the vapor-space in the to drum 29 and the vapor-line 40 to the con enser system. system suflicient to maintain the c arging stock in the liquid phase at the temperature of treatment, this pressure being at least 150 pounds Ipressur'e, although greater pressure maybe employed to increase the concentration of the lighter hydrocarbons in the liquid phase of the oil undergoing treatment and in the vapors issuing therefrom.v

The oil circulating through the tubes gradually travels towards the opposite end of the drums from which it feeds, the bottoms being continuously removed from the bottom drum through the tar- lines 38 and 39. As the lighter hydrocarbons re produced and evolved, the "volume of tie Oil in the successive units decreases, with the result that :the level of the oil in the top drum 29 gradually drops from compartment to compartment the greater'the distance from The distillate produced from the va )ors of the still operated in the manner a ove described has dominant ,parafiinoid characteristics, notwithstanding the high cracking temperature to which the?- charging stock is subjected 'for the period of its travel through the still. It is believed that this .is due to the removal of the lighter hydr carbons from the cracking zone substantial- "1y;- immediately upon formation, whereby no'further cracking or breaking down of the lighter hydrocarbons into aromatic compounds is produced and the 011 passing A pressure is maintained u on the through the zone is substantially entirely in the liquid phase. The retention .of the lighter hydrocarbons in the cracking zone,

particularly at the high temperatures to which they are subjected, would result in the formation of large proportions of aro- 'matics as is the experience in tube cracking processes, the resulting distillate then being of a dominantly aromatic character as is the case with the distillates produced art.

It is not -intended that the temperatures employed shall be limited to temperatures approximating the minimum temperature hereinbefore stated. Higher temperatures, for example, temperatures of the order of 1000 F. may be employed while utilizing pressures of say 250 to 300 ounds or above, suflicient .to maintain the cliargin stock in the liquid phase. In such case, t 1e rate of cracking into lighter hydrocarbons-of dominantly paraflinoid characteristics becomes very greatly increased, their immediate re"- moval from the cracking zone, however,

result in the formation of a distillate havingdominantly aromatic characteristics.

In continual operation of thestill it is desirable to alternate the direction of feed and'direction of movement of combustion gases at times, thereby equalizing the wear on the cracking tubes.

Although the present invention has been described in connection with specific details of anapparatus suitable for carrying it into in the tube-cracking processes known in the preventing excessive cracking which would effect, and of a process for its emplo ment,- I

it is not intended that these details s all be regarded aslimit-ations upon the sec e of the invention, except in so far as inc uded in the accompanying claims.

We claim:

' 1. The process of pyrogenetic conversion of hydrocarbon'oils into lower-boiling point oils having dominant parafiinoid character istics which consists in continuously flowing the hydrocarbon oil through a zone heated to a temperature suflicient to cause conversion of the oilat a rate of at least 35% per hour and under a pressure sufiicient to 'maintain the said oil in the liquid phase tinuously ficient to maintain it in the liquid phase and continually removing the vapors of light hydrocarbons from each of said units substantially immediately upon formation during passage through the heating zone.

3. The process of pyrogenetic conversion of hydrocarbon oils into lower boiling point oils having dominant parafiinoid characteristics which consists in maintaining the oil in a plurality of communicating units, causing the oil of each unit to flow upwardly through a heated zone whereby it acquires a temperature suflicient to cause conversion at a rate ofat least 35% per hour, and continuously withdrawing vapors of light hydrocarbons from .each of said units while passingthrou h the heating zone, a pressure being maintained upon the oil at least suflicient to retain it in the liquid phase.

4. The process of pyrogenetlc conversion of hydrocarbon oils into lower boiling point oils having dominant paraflinoid characteristics which consists in maintaining a plurality of communicating units of oil, conflowing the oil into and progressively tirough said units, causing the oil of each unit to flow through a heated zone whereby it acquires a temperature sufiicient to cause conversion at a rate of atleast 35% per hour, and continuously withdrawin v'a pors of light hydrocarbons from eac of said units, a pressure being maintained on the oil at least sufiicient to retain it in the liquid phase.

5. In a pressure oil still, an upper and a lower. drum, each being partitioned into compartments, a heating vzone between the drums, communicating means between the corrcsonding compartments of the drums exten ing through the heating zone, communicating means between the corresponding compartments of the drums outside of theheating zone, means for collecting the vapors from the several compartments of the upper drum, and means establishing communication between the compartments in the lower drum.

6.- In a pressure oil still, a pair of upper drums, and a air of lower drums, each of said drums ing partitioned into comartments and the compartments of the ower drums communicating at their hottoms, a heating zone between the pairs of drums, the drums of each pair being on opposite sides of the median line through the heating zone,- heating tubes extending between the compartments of each of the lower drums through the heating zone to the corresponding compartments of the upper drum on the opposite side of the median line through the heating zone, communicating means between the compartments of each of the upper drums and the corresponding compartments of the lower drum on the same side of the medianline through the heating zone, said communicating means passing outside of the heating zone, means for collecting vapors from the upper drums, means for feeding oil into the compartments of the upper drums and means for withdrawing oil fromthe lower drums.

7. In a pressure oil still, a pair of upper drums, and a pair of lower drums, each of said drums being partitioned into compartments and the compartments of the lower drum's communicating at their bottoms, a heating zone between the pairs of drums, the 'drums of each pair being on opposite sides of the median line through the heating zone, heating tubes extending between the compartments of each of the" lower drums through the heating zone to the corresponding compartments of the upper. drum on the opposite side of the median line through the heating zone, communicating means between the compartments of each of the upper drums and the corresponding compartments of the lower drum on the same side of the median line through the heating zone, said communicating means passing outside of the heating zone, a drum above the upper drums, said drum being divided into compartments communicating at the to of the drum, communicating tubes exten ing from the compartmentsof the last-mentioned drum to the corresponding compartments of the upper pair of drums, means for withdrawing vapors from the drum above the upper drums and means for withdrawing oil from the lower drums.

FRANK A. HOWARD. EDGAR M. CLARK. JAMES R. oARRrNenn

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