US1944057A - Apparatus for continuous distillation of heavy hydrocarbons - Google Patents

Description

Jan. 16, 1934. E. A. BARBET 1,944,057 APPARATUS FOR CONTINUOUS DISTILLATION OF HEAVY HYDROCARBONS Filed Oct. 15, 1950 3 Sheets-Sheet 1 E v K! I \ill "i2 Jan. 16, 1934. 5 BARBET 1,944,057

APPARATUSFOR CONTINUOUS DISTILLATION OF HEAVY HYDROCARBONS Filed Oct. 15, 1950 s Sheets-Sheet 2 u /r 21g iiy . u 2 f 7 2d? L 4/) I! If, I t\ 1 n y m NF m fl I fl J Jan. 16, 1934. E, A, BARBET 1,944,057

APPARATUS FOR CONTINUOUS DISTILLATION OF HEAVY HYDROCARBONS Filed Oct. 13, 1930 3 Sheets-Shret 3 17 7, gmlre Patented Jan. 16, 1934 PATENT OFFICE APPARATUS FOR CONTINUOUS DISTILLA- TION OF HEAVY HYDROCARBONS Emile Augustin Barbet, Paris, France Application October 13, 1930, Serial No. 488,498,

and in France October 14, 1929 1 Claim. '(Cl. 196-118) It has been proposed to crack hydrocarbons of a 'very high specific gravity and boiling at temperatures above 350 C. by conducting them through a layer of molten lead. However the 5 Commercial application of this method presents difiiculties and has not hitherto been successful in its application to distillation without cracking.

The present invention enablesthese difiiculties to be overcome owing to a special arrangement.

An apparatus thus constituted can serve for distilling and fractionating oils, 1. erfor a much more delicate operation than cracking,- the latter only effecting a rough and irregular distilla- 'tion.

To eifect cracking of the hydrocarbons it is necessary to allow them to remain in contact with the molten metal for a fairly substantial period of time to obtain the necessary heating. In contradistinction thereto if it is desired to effect a distillation of the hydrocarbons it is necessary to ensure that the hydrocarbons only remain in contact with the molten metal for a fraction of a second. 7

The apparatus, according to the presentinvention, allows continuous operation and a perfectly smooth running; it is particularly characterized by the following features:

I. Regularity of heating, which is a condition of success. Only two methods of heating are possible: v

(a) Heating with gas supplied by a coke or coal gas producer.

(b) Heating with mazout or even with the asphalt, residue of the process. a a

Only these methods of heating can maintain the molten lead at the desired constant temperature, and at the same time supply the heat neces sary for vaporizing the hydrocarbons;

II. Regularity of feeding with'hydrocarbons. 40 This is as indispensable as regularity of heating.

It has been recognized that by a regular .preheating of the oil, the hourly yield of the moltenlead bath is greatly increased, but it has been noted that it is indispensable to prevent boiling before the oil penetrates into the molten lead. For a given output, the vapour'bubbles, if any, occupy a volume 200 or 300 times greater than the volume needed by the liquid itself. This produces an undesired disturbance in the actual weight of injected oil, and therefore in the amotuit of heat required. It will be hereinafter disclosed how this problem may be solved.

III. The great advantage presented by bubbling the liquid hydrocarbon up through molten lead is the fact that the oil is subjected but for an extremely short period of time to a temperature high enough to produce immediate vaporization. This swiftness of operation not only avoids cracking, but moreover does not in the least influence viscosity i. e. the lubricating propi erties of the lubricating oils recovered, and this even if the temperature rises somewhat higher than the boiling point of these oils.

IV. The apparatus has nevertheless been devised also for working under reduced pressure, 5

in order to lower the distilling temperatures by about '70 or 80 C.

V. Many kinds of crudeoiL'Mexican, Persian or other crudes, have an important percentage of asphalt. This asphalt should not be allowed 701' to be carried over with the distillate, which would spoil lubricating oils; but then one must efiect a continuous drawing oif of asphalt, in order to maintain normal and constant working of the metal bath. r

vlplt is also very important to. preheat as much as possible the hydrocarbons to be distilled, before they penetrate into the molten lead, in order to lessen-the amount of heat the lead will have to supply. This result will be obtained .1-

drawings, the apparatus is composed of two 1.

heavy iron-plate boilers or stills A and A, placed side by side. The boilers may be of any section desired. The boilers contain molten lead. The

vapour formed by the distillation of the hydrocarbons rises through N N and passes through .P. The dephlegmators for successive fractional condensation, have not been illustrated in the drawings.

The oil is injected through a series of jacketed pipes L L, the lower end of which is fitted with a valve m which can be worked from without by means of the rod Z and handle K (see Figure 2).

' M is an inner concentric pipe forming with L a heat insulating jacket, the object of which is 11035 to prevent the hydrocarbon from boiling before the moment of its being injected, in a thin jet, into the molten lead. The hydrocarbon is impelled by a pump. It enters into the pipes through valves E and E. The number of injectors L and L is as great as necessary, and their position slightly inclined in the way to project the oil upon the heated part of the boiler.

As it has been described above, the heating is made with gas coming from a gas producer or with mazout or residual asphalt from the distillation. The fuel arrives through longitudinal pipes C and the flame of the gas jets heats the boilers. After passing under the boilers, the flame is directed to flue H H and to outlet B.

It is necessary to insure a continuous outflow of the unvaporized asphalt. For this purpose several overflow pipes F and F are fitted at various points. These pipes lead the residue into receivers D D connected to vacuum vessels. When the receivers are full, the valves communicating with the vacuum vessels are closed and air let in so that asphalt can flow out and solidify. The asphalt may be used for heating ithe apparatus.

Utilization of waste heat-In the first place it is important to recover the heat of the fine gases after heating of the metal bath. These gases may be used for generating steam for various re- ,quirements of the plant, and at the same time for preheating the oil before it enters the still.

On the other hand a large amount of heat is contained in the oil vapours produced by the molten lead. As already stated, one must effect j;a fractionation of these vapours, and their latent heat being very low, one must not use for this purpose the oil to be treated, because this would be too violent. Air therefore is used, circulating in tubular condensers placed in succession, in

-=order to obtain a very regular and smooth condensation. Counter-current circulation is adopted, which means that the heated air from the last condenser passes into the foregoing one and so on. Every portion of the vapours will undergo an identical and very gentle fractional .-oil and at last even some heavy lamp oil.

The working under reduced pressure will give excellent results owing to the fact that expanded vapours are less easily condensed, which is very important in order to avoid premature condensation of gas oil.

The heat of the very hot air leaving the first condenser is utilized forcombustion either of gas or of asphalt for heating the molten lead bath.

By means of such apparatus, one may obtain a complete distilling of the heaviest oils, paraffin included, except asphalt, without the least formation of gas or carbon. Besides, the oils will have kept all their viscosity and their greenish fluorescence A modified type of the apparatus is shown on Figures 3 and 4 of the accompanying drawings. This apparatus comprises a square cast steel boiler a the convex heating surface of which possesses several pots b of a conical or cylindrical shape projecting above the hearth. Every pot is fitted with an injecting pipe L, similar to the above described ones. This arrangement of the heating surface, kept convex, allows a better exchange of heat at the same time reducing the weight of molten lead.

As shown on Figure 4, the arrangement of the projecting pots is lozenge-like, in order to allow easier heating by gas jets or mazout. The boiler should not be too large, for lesser expansion; however three, four or even five boilers may be placed in line on one single furnace, gas or mazout heating producing particularly long flames, which will give sufficient heat to every boiler.

Every boiler resting on the furnace is supported by a reinforced side belt g, this belt serving at the same time to keep the gases from escaping. After the hot gases have heated the three, four or five boilers, they are sent to the steam generators.

The bottoms of the boilers are reinforced by means of several cross-ribs t in the molten lead. Underneath the pots are also joined together by the ribs u so .that one may operate under a vacuum if desired.

The residual asphalt flows out through pipe I as above described.

Figure 5 illustrates a complete plant.

The chimneys 10 are slightly above the level of the liquid 11, the chimneys being covered by bells 12 having vertical slits 13. The overflow pipe 14 is level with the top of the liquid. Pipe 1 clips into the liquid as shown.

The hydrocarbon vapors passing from the boilers instead of being merely subjected to fractional condensation, may be directed through fitted with a condenser-cooler J, where they are rectified into far more clear cut fractions. The various extractions 12-3l56 made on the plates of the rectifier yield very distinct 115.

products, especially when distillation of hydrocarbons is concerned. The products drawn off are cooled in the manifold cooler Y. The final residue, which is the most viscous oil, passes through cooler Z to the test safe X.

Where very powerful plants are needed, in order to avoid too large boilers, one may arrange side by side as many batteries of four or five boilers each, as necessary, each battery having its own rectifier.

When a molten lead bath is employed, high temperatures can be used, the contact between the liquid and the molten lead lasting even less than a second. This results in extremely rapid distillation.

For the fusion of the lead, a temperature of 360 C. must be reached.

What I claim is:

Apparatus for the continuous distillation of hydrocarbons comprising a twin still adapted to contain molten metal, a vapor outlet common to the two stills, jacketed injection tubes, a valve at the outlet ends of the ejection tubes by which the hydrocarbon is projected into the molten metal, means for heating each still in proximity to the point of injection of the hydrocarbon and overflow pipes in the stills for continuously removing the asphaltic residue produced during distillation.

EMILE AUGUSTIN BARBET.

valves V and collector P to a reflux column I

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