US1619396A - Apparatus and process for fractional distillation and condensation - Google Patents

Description

March 1 1927 1,619,396

J. E. BELL; APPARATUS AND PROCESS FOR FRACTIIONAL DISTILLATION AND counzusmrpu Filed 00%... 1 4, 192] 2 shuts-sheet 1 Co/m/vs7?\ March 1,1927. 1,619,396

J. E. BELL I APPARATUS AND PROCESS FOR FRACTIONAL DISTILLATION. AND CONDENSATION all. /N T 0/1. oven. 0 w

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UNITED STATES 1,619,396 PATENT OFFICE- JOHN E. BELL, OF BROOKLYN, NEW YORK, ASSIGNOR TO SINCLAIR REFINING COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF MAINE.

APPARATUS AND PROCESS FOR FRAQTIONAL IDIS'IILLA'IION AND CONDENSATION.

Application filed October 14, 1921. Serial No. 507,629.

My invention relates more specifically-to the treatment of crude petroleum. For commercial purposes it is necessary to separate the crude oil, which is composed of a large number of different hydrocarbon compounds, varying in gravity and boiling point, into fractions or cuts, each composed of a group of hydrocarbons the gravities and boiling points of which range within certain predetermined limits. This separation is commonly effected by what is known as fractional distillation, the crude oil being .slowly raised in temperature through the range of temperature at which the desired distillates are given off, the distillate coming over below a predetermined temperature or end point constituting the first cut or fraction and being separately stored, the second out being composed of compounds distilling over between such temperature and a higher end point and so on. It has been found. impossible, however, in the process and apparatus heretofore employed to secure sharp cuts or divisions between the 'respective adjacent groups without making a series of distillations or re-runs, it being found that a certain proportion of the heavier hydrocarbons belonging in a lighter group or cut persist in remaining with the next heavier group or 3'0 out while a proportion of the lighter hydrocarbons of the heavier group are found with the lighter group or out. It is the object of the presentinvention to provide an apparatus in which in one'o'peration any desired number of cuts may be made with the end points of the cuts, groups or. fractions sharply defined, and at the same time to provide such an apparatusin which the oiland prodrcts are simply and easily handled and 40 in which the consumption of fuel is econo mized.

In the accompanying drawings I have shown and in the following specification described in detail a preferred embodiment of my invention; it is to be understood, however, that the specific disclosure is for the purpose of exemplification only and that the scope of the invention is defined in the following claims in which I have'endeavored 'to' distinguish it from the prior art so far as known to me without, however, relinquishing or abandoning any portion or feature thereof. j

In the..drawings, Fig. 1- is a plan view of a preferred form of apparatus embodying my invention; Fig. 2 a front View thereof; Fig. 3 an end view of the same; Figs. 4, 5. 6 and 8 axial sections of certain of-the elements thereof, and Fig. 7 a transvei so section on the line 77 of Fig. 6 Each part is identified by the same reference character wherever it occurs in the several views.

In the preferred embodiment of the invention shown in the accompanying drawings I have provided four still units each comprising a still and a heat inter-changer, but it will be understood that the number to be used dependsupon the number of cuts to be taken. The oil is circulated through the heat interchanger before being introduced into the still of the same unit and heated by the vapors from said still which are correspondingly reduced in temperature and condensed in the heat interchanger. Each still with its heat interchanger and connections is like the others except as the first and last stills of the series require modification by reason of their. end positions and therefore it will be sufficient, except for such modifications to describe one such unit. The stills 9, 9", 9, 9 are shown as of the horizontal cylindrical type, though this is not essential, and may be heated in any desired manner by-biirners 10 or the like. For convenience of transfer of material from one to the other the stills and heat interchangers 11, 11, 11. 11 are arranged upon an incline the first still into from a suitable source through a supply pipe 11, the oil, after being preheated, being forced by the head of supply through pipe 15 to the first heat interchanger 11 2- The crude preh-eater may be heated by steam or 1 other suitable means, but I prefer to heat it by the hot residue drawn off from the last still. 9' in the series through the pipe 16.

The I preferred construction of the preheater is shown in Fig.8. The pipe 16 enters the rear head of the preheater'and distributes the hot tar from the still 9 by means of a T 17, within the chamber 18 formed by the 15 conveyed to the first-heat interchanger as end wall 19 of the preheater and a header 2 spaced therefrom. A similar header 21 is mounted near the; front end wall 22 of thepreheater forming therewith a tar space or previously described. In order to insure a more thorough preheating of the oil, the oil chamber is provided with baffles 28 which cause the oil to pursue a circuitous path through the preheater. Chamber 18 is provided witha drain pipe 32 to drawofi'any heavy ,matter which may collect in said chamber.

It has been remarked that the oil is heated in the heat inter-changers 11 11, etc., by. .the vapors coming from the corresponding stills. As these heat interchangers are substantially alike in construction a description of one will answer for all. Fig. 5 shows such a heat interchanger in section. It is preferably cylindrical in shape, is supported in a vertical position, and comprises a barrel 33 and end plates 34, 35. Headers 36, 37 divide the interior of the interchanger into top and bottom oil chambers 38, 39, and an intermediate vapor chamber 40. The headers are connected by oil tubes 41 and the Va or chamber provided with baffles 42 by which the vapors are caused to circulate backward and forward about the oil tubes to provide for the full absorption of heat therefrom. The oil to be heated enters the chamber 38 at the top thereof (through the pipe 15 in the caseof the first heat interchanger) and escapes at the bottom through pipe 43. After passing through. the tubes 41 in the vapor chamber and receiving heat from the wa pors, it is led by the pipe 43 to the top of the still with which the heat interchanger is associated. The vapor from said still is led by the pipe 44 opening into the vapor space thereof to the lower end of said heat interchanger and, circulating through the vapor chamber therein, is cooled by the incoming oil and for the most part condensed, and may be drawn off through the draw-off pipe 45. Vapors uncondensed in the heat interchanger ll -escape through the pipe 46 connected with the upper end of the vapor chamber and are led to a condenser 47 which may be of any approved design. The uncondensed vapors from the heat interchangers 11*, 11, 11 escaping through pipes 46", 46, 46 respectively are conveyed by pipes 56 to the adjacent stills of lower temperature where they assist in heatin the oil therein and are partially condensed, as hereinafter described.

The construction of stills 9, 9", 9 is identical and shown in Fig. 4 of the drawings. Still 9 being slightly different will be described later. The body 48 is provided with ends 49, 49 and with headers 50, 51 which dividethe still into a vapor inlet chamber 53,

a vapor outlet chamber 52 and an intermediate oilchamber 54. .Tubes 55 extending between the headers connect chambers 53, v

52. Hot vapors enter chamber 53 through inlet 56 and passing through the tubes give up a portion of their heat to the oil in the still and are partly condensed, the condensate escaping at 58. The stills are somewhat inclined from rear to front to assure theflow of condensate to the outlet there for. The uncondensed vapors escape through outlet pipe 57 at the front. The oil undergoing distillation enters the still chamber 54 through inlet 66, and, after being heated bv the vapors in the tubesand the externally changer through pipe 43, to which referencehas been made, and which is connected to inlet pipe 66. The unvaporized residue of oil overflows from the still by pipe 59 to the adjacent hotter heat interchanger, pipe 59 being offset upwardly at 60 (Fig. 2) to lln maintain an oil level in the still approxif mately equal to two-thirds of its depth Drawoff 97 is provided for emptying the still chamber when desired. Uncondensed vapors from chamber 52 and vapors generated in the still chamber, which are of approximately the same boiling point and composition are united, outlet pipe 57 beingjoined to outlet pipe 61.

interchanger to which they are led by pipe 44 (see Fig. 1). Provision has been made however for leading them directly to a condenser 62 (Fig. 1) by means of pipe 63, pipes 44 and 63 being provided respectively with valves 64 and 65. The condensate from the vapor circulation of the still escaping through outlet 58 may be carrried by pipe 67 directly to a cooler; or it may betaken by pipe 69 to vapor outlet 46 of the adjacent Preferably the fvapors pass to the adjacent (cooler) heat pipe 45' hotter heat interchanger and permitted to enter the vapor space thereof and be subjected to redistillation. It is 'to'be observed in this connection that the condensate outlet of each interchanger is likewise connected by to vapor pipe 46 of the next hotter interchanger to provide for redistillation but an alternative connection 93 leads from each outlet to a cooler through which the condensate may be run to storage. Hand valves are provided in all these pipes to control the circulation.

Still 9 being the last and hottest of the series is without the heating circulation but is equipped for the introduction of steam which serves the purpose of reducing coking from the heavy tarry residue treated in this still and lowering the temperature at which distillation takes place. A spider 71 is susended near the bottom of the still by the inlet pipes 7 2, said spider comprising three tubes 73, 7 4, 7 5 extending longitudinally of the still and connected to the inlet pipes by branches 76, 7 7, 78. The longitudinal tubes are slitted or perforated for the injection of the steam supplied thereto by pipes 72 into the oil. Still 9 has an oil inlet 66 and a vapor outlet 61 similar to the like elements of the other stills and similarly connected. The drawoff 92, however, is connected to the preheater for the previously described purpose of preheating the fresh crude oil from the hot residue from still'9.

The operation of the plant has been described in connection with the construction but may be recapitulated as follows: Crude oil arriving flows through the preheater where it absorbs the surplus heat from the hot tarry residue from the last still flowing through the preheater in a direction opposite to that of the oil. It next flows through the first heat in- 'terchanger heat from the vapors from the first still passing in the opposite direction; thence through the first still where it 1s raised to a distilling temperature by the externally applied heat and the vapors circulating therethrough in pipes; thence through the following heat interchanger and still and so on, its temperature being raised step by step and its volatile contents being correspondingly driven off -until' in the final still the last fraction of desired distillate is removed, when it flows -to the preheater.

The vapors from the first still-may be passed directly to a condenser, or. in the preferred operation, are passed through the first interchanger and thence to the condenser, the condensate in the interchanger being refluxed into-the next hotter interchanger and revaporized, or conducted to storage. The vapors from each of the other stills may be conveyed immediately to condensers; preferably however they are run through the from a source of supply first.

from top to bottom absorbing adjacent densate therein being either refluxed or stored as described) and then through the next cooler still where they are largely condensed the uncondensed vapors mingling with the vapors generated in said still and passing on to the next heat interchanger ant still and so on. Thus the oil is subjected to' fractional distillation and the vapors thereof to fractionalcondensation at temperatures so related to the boiling point temperatures of the vapors themselves as to secure a high degree of sharpness of cut. With a comparatively simple apparatus a large number of cuts may be made. Except for unavoidable radiation losses but little heat is lost the heat from the overhead as well as that of the residue is largely absorbed by the oil during its treatment.

I claim:

1. A process of fractional distillation and condensation of oil comprising flowing the oil to be treated through a series of stills heated to successively higher vaporizing temperatures, heating the feed oil to each still by vapors from the same still, with cooler heat in'terchanger, (the con-i drawing the resulting condensate and heatv ing each still by the remaining uncondensed vapors from the still at next higher temperature.

2. A process of fractional distillation and condensation. ol? oil comprising flowing the oil to be treated through a series of stills heated to successively higher vaporizing temperatures, heating the oil intermediate successive stills by vapors from the still at higher temperature, withdrawing the resultoil to be treated throu-gha series of stills heated to successively higher vaporizing temperatures, heating the oil intermediate successive stills by vapors from the still at higher temperature, collecting the condensed vapors thereby produced, heating the still at lower temperature by the uncondensed vapors and collecting the condensed vapors thereby produced.

5. A process of fractional distillation and condensation of oil comprising flowing the oil to be treated through a series of stills heated to successively higher vaporizing temperatures, heating the oil intermediate successive stills by vapors from the still at higher temperature, heating the stillat lower temperature by remaininguncondensed vapors, and combining the then remaining uncondensed vapors with'the vapors from the still at lower temperature.

6. A process of fractional distillation and condensation of oil comprising flowing the oil to be treated through a series of stills heated to successively higher vaporizing temperatures, heating the. oil intermediate Successive stills by vapors from the still at higher temperature, collecting the condensed vapors thereby produced, and heating the collected condensate by vapors from the still at next higher temperature.

7 A condensation of oil comprising flowing the oil to be treated through a series of stills heated to successively. higher vaporizing temperatures, heating the oil intermediate successive stills by vapors from the still at higher temperature, thus partially condensing said vapors, heating the still at lower temperature by the uncondensed vapors, collecting the condensed vapors thereby pro- ,duced, and heating the collected condensate by vapors from the still at higher temperaure. 7

8. A process of fractional distillation and condensation of oil comprising flowing the oil to be treated through a heated to successively higher temperatures and intermediate heat interchangers, passing the va ore from each still, except the first, throug the intermediate heat interchanger in the direction of decrease of temperature and thence through a heating element within ,st

the still at next lower temperature,-collecting the condensed product from the vapors in each heat interchanger, except the last, and returningthe condensate to the heat in-ter changer at next higher temperature in direct contact with the vapors therein.

9. A condensation of oil comprising flowing the oil to be treated through a series of stills heated to successivelyihighcr temperatures and intermediate heat interchangers, passing the vapors from each still, except the first, through the intermediate heat interchanger in the direction of decrease of temperature and thence through a heating element with-- in the still at next lower temperature,-collecting the condensed product in each heating element within each still, except the last, and returning this condensate to the adjacent heat interchanger at higher tempcrature in direct contact with the vapors therein.

10. A series of stills, means for maintaim ing them at successively higher temperaprocess of fractional distillation and series of stills process of fractional distillation and "rection, and connections changers, except the last,

tures, afseries of heat interchan ers, connections for passing oil successive y and alternately through the stills and heat interchangers in the direction of increase of temperature, and connections for. passing the vapors through the heat interchangers and sti Is in the reverse'direction.

11. A series of stills, means for maintaining them at successively higher temperatures, a series of heat interchangers, connections for passing oil successively and alternately through the stills and heat interchangers in the direction of increase of temperature, connections for passing vapors through the heat in'tercliangers and-stills in the reverse direction and means for collectthe reverse direction and means for collect ing condensed vapors produced in the heat interchangers.

13. A series of stills, means for'inaintaining them at successively higher temperatures, a series of heat interohangers, connections for passing oil successively and alter nately through the stills and heat interchangers in the direction of increase of temperature, connections for passing the vapors through, theheat interchangers' and stills in the reverse direction and means to mingle the uncondensed vapors passed through each ill with the vapors produced therein.

14. A series of stills, means for maintaining them at' successively higher temperatures a' series of heat interchangers, connections for passing oil successively and alternately through the'stills and heat interchangers in the direction of increase of temrection, and connections forirefluxing the condensate from the stills, except the last, through the respective adjacent heat interchangers of higher temperature.

15. A series of stills, meanslfor maintaining them at successively higher temperatures, a series of heat interchangers, connections natelg through the stills changers in the direction of increase of temperature and the vapors in the reverse difor refluxing condensate from the respective heat interthrough the respective adjacent heat interchangers of higher temperature.

JOHN E. 'BELL.

and heat interperature and the vapors int-h'e reverse diforpassing .oil successively and alter-

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