US2286503A - Process for segregating hydrocarbons - Google Patents

Description

June 16, 1942. QCQN PROCESS FOR SEGREGATING HYDROCARBONS Filed June 29, 1938 2 Sheets-Sheet l a a 3 P 0 u 2 HE J 1 8 m2: .I l LR m J ms mw a a n 7 c a O cm Ill! 8 H 4 a L .1

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Patented June 16, 1942 UNITED STATES PATENT OFFICE PROCESS FOR SI I CZZZZATING HYDRO Ernest A. Ocon, Yonkers, N. Y.

Application June 29, 1938, Serial No. 216,629

8 Claims.

This invention relates to a means and method for segregating from a mixture of various miscible hydrocarbons a liquid concentrate of method. While distillation is sometimes effective when carried out with precision, it is thus uneconomical when used on a large scale; hence, was tried the separation by liquid solvents calculated to have selective chemical afiinities for certain components with an expectation thattwo distinct phases of liquid would separate by the action of gravity on account of the. difference in density between an undissolved component phase and a dissolved component phase.

The latter method of separation has been found impractical for intensive isolation of specific components.

I have found that simple distillation using the ordinary kinds of vapor fractionation devices, such as bubble towers and gravitational separation means, even those in which mechanical centrifuging means are used for amplifying the force of gravity, are "very inefficient in overcoming the powerful intermolecular forces of attraction be tween the hydrocarbon components, between the solute and undissolved components, and even those between the solvent and solution for the undissolved components. I have, therefore, devised a method of separation which employs forces having magnitudes closer to those of the intermolecular forces and operates on matter maintained principally in a dispersed condition so as to weaken the intermolecular attraction between the hydrocarbon components. A very simple illustration of the manner in which my method operates can be observed in the well known distillation test for determining the quantity of water in gasoline. In this test almosta negligible quantity of water which is homogeneously dissolved in the gasoline can be segregated in a gaseous atmosphere.

water molecules coalesce and condense out from the remaining hydrocarbon vapors.

An object of this invention is to obtain dispersion of mixed hydrocarbons and volatility controlling agent and to induce theproper coalescence of specific hydrocarbon components with an apparatus designed to carry out these manipulations effectively and with economy of energy, since the known kinds of vapor fractionating equipment are not satisfactorily adapted.

for the use of my method, and neither are the known types of centrifuges which depend for operation solely upon rapidly rotating parts. Further objects reside in the application of my method. These and other objects will become apparent from the following description and the claims.

As can be readily noted,- this invention has applications of a great variety, for example, in isolating substantially pure individual hydrocarbons from a very close cut of hydrocarbons, such as refinery gas, gasoline, etc., for fractionating emulsions which easily foam in ordinary distillation, for absorbing natural gas, for dehydrating a hydrocarbon oil, for incorporating 'anti-detonating agents into fuels efficiently, for

segregatinganti-knock components from motor fuels, for segregating non-paraffinoid hydrocarbons from lubricating oils, and for fractionation of any type of mixture or solution largely com usually is a substance normally in liquid state, partly immiscible with the hydrocarbon mixture,

having somewhat greater polarity (solubility in water) than the hydrocarbons, selectively greater chemical attraction for the type of hydrocarbons intended to be segregated as a liquid concentrate, and lower-volatility than the hydrocarbons to be left in the vapor state. By dispersing is meant conversion of a substance into gaseous or vapor state, into thin films on a solid contact surface,. or into an atomized liquid suspended As volatility controlling agents preferably may be used one or more of the following types of substances; alcohols, such as ethyl alcohol and the higher alcohols in fusel oil, water, cresols, phenol, aniline, crotonaldehyde, carbon tetrachloride, zinc chloride, aluminum chloride, sulphur dioxide, benzene numbered complex, nitro-benzene, etc. may be used at several the step of coalescing and precipitating from the dispersion specific hydrocarbons. particularly those in which has been induced a lower volatility by a volatility controlling agent. Such hydrocarbons as are made to coalesce may do so dissolved in the volatility controlling agent or occluded by it. More particularly. these steps are used in repeated alternate succession.

The features of the apparatus considered suitably adapted for carrying out th steps of dispersing and coalescing are embodied in means for generating vapors from the hydrocarbon mixture, means for passing liquid volatility controlling agent into contact with the generated vapors at multiple stages, with the general flow of the liquid agent and the vapor streams being preferably countercurrent in direction, means for utilizing the velocity head energy of the vapors to disperse the liquid agent at each contact stage, and means for altering the velocity and path of the stream containing dispersed hydrocarbons and agent in a manner which accelerate the intended coalescing and precipitation.

For clarity. the invention will be described by reference to a diagrammatic showing of a preferred form which the apparatus may take. In

Different solvents the drawings are represented two views of an apparatus.

Figure 1 shows an elevational view of tower I and appurtenances, a cutaway section of the tower being shown to illustrate the internal structure.

Figure 2 shows a horizontal cross sectional view of tower I at the section indicated by line A-A in Figure l.

Figure 3 shows an elevational view of modified tower I in which a rotating agitation is used to aid dispersion and centrifugal action in stages.

Figure '4 shows a horizontal cross sectional view of modified tower by line 3-13 in Figure 3.

The tower I consists in a multiplicity of sections separated by superimposed plates 2, each plate being provided with vapor passage means 3 and 4, interconnecting the sections and liquid removal means, such as overflow pipes 5. Be-

tween each pair of successive plates a lateral spiral fluid passage is formed by stationary curved impingement vanes I, which are best viewed in a horizontal cross-section, as shown in Figure 3. These vanes may be broadly described as sets of concentric and somewhat cylindrical tubes partitioning the fluid passages in each section and containing ports 9 and I0, for making the passages continuous. th ports II), being constricted and provided with orifice inlets from adjoining liquid overflow pipes to act as atomizers. At the upper end, tower is equipped with a vapor outlet pipe 6, leading to any type of conventional vapor condensing, collecting, or further fractionating means, and a fluid inlet pipe 8, for feeding fluid charging stock. At the extreme base of the tower are drain outlets II and I2, the former for any residuum collected in the settling zone I3, of the tower I, and the latter for decanting cleaner residuum from out. used to control flow in either or both drain outlets. Betweenthe bottom plate 2, and the residuum settling zone at base of the tower are a tangentially injecting inlet pipe 8, for the charging stock, a perforated retaining pan I5, for retainstages; secondly, there is I at the section indicated which sludge is settled. A liquid level control means I4. may be ing liquids in a rotary motion caused by the tangential injection of charging stock and a vapor inlet jet I6, located so as to contact the jetted vapors with liquids which drip from the pan I5. The ban and tangential injection arrangement is particularly useful when the injected hydrocarbons are partly in liquid state. for it acts to retain the liquids for a period to permit increased vaporization, the vapor jet underneath acting further to strip the residual portions which. drip from the pan. Condensed liquids which collect on the plates may be removed at any or all of the several stages by withdrawal lines II, which can be two or more.

portion being returned through line I9, if desired, or, if of relatively low or intermediate volatility, it may be withdrawn as a bottom product by line 20, or as a side-draw product by line 2I, the liquid hydrocarbon concentrate being removed in an alternate manner, depending in turn on its relative volatility. Overhead from the auxiliary stripping column may be passed by pipe I9. into an intermediate part of tower I, or by pipe 22, to a condenser and receiver or other separating means (not shown). A reflux from the overhead of tower I, may be returned thereto for regulating conditions in the tower by pipe line 23. By means of, inlet lines 25, additional volatilizing fluids such a steam, gaseous hydrocarbons etc., and/or volatility controlling agents may be injected at suitable temperatures into the spiralling stream of fluids to increase the stream velocity and control the volatilities of the substances dispersed in the stream while permitting a desired amount of condensation at each stage in the tower.

In Figure 3, the modified tower 1 illustrates the same general arrangement as shown in Figure 1, except that the corresponding tower in Figure 3 has provisions for mechanically rotated impingement vanes 26, in place of stationary vanes I, disposed in some sections between pairs of plates 2. The rotating vanes 28 are attached to a rotating shaft 21, which passes vertically through the central axis of tow'er I. The vanes 26, may be two or more in number and are preferably designed as illustrated in Figure 4.

to add velocity to the vapor stream in place of liquids out of the vapor stream. "Shaft 21, ro-

tates in journals 28, and sockets 29, and protrudes through a packed fitting 30, in th base to a means for rotating said shaft such as for example a driven gear Si, or by any other suitable manner. in pan I5, may be produced by vanes 32, attached to shaft 21, and rotated therewith.

As an illustration of a method for operation in which cyclic hydrocarbons andasphaltic substances are to be segregated as a liquid concentrate from more desirable parafflnic lubricating constituents in a mixture containing those types f compounds the following example is given:

An initial charging stock e. g. a naphthene base bright stock, at a temperature of about 450 to 650 F., is led into the tower I, by inlet 8, in admixture with about an equal or larger proportion of crescls and subjected to vaporization in tower I, at a pressure maintained sufficiently plates Additional circulatory turbulence 2,280,!8 .low to obtain vaporization oi a substantial part of th hydrocarbons and the cresols at a pressure of about 200 to 700 mm. mercury absolute.

-A small proportion of gaseous hydrocarbons,

ponents of the-mixture, due to their higher inertia and lower fugacity, are precipitated out against the walls of the inpingement vanes and collected as a liquid layer above each plate. One portion of the liquid layers passes down through the overflow pipes 5, from which the down-flowing liquid is aspirated by a constricted high -velocity fluid stream at points i and becomes thereby redispersed. Another portion of the liquid layers is withdrawn from one or more plates by pipes W, as a liquid concentrate of denser hydrocarbons mixed with some of the c'resols and is removed to a cresol stripping zone i8, in which the cresols are yolatilized for example, by addition of a small amount of steam,

which is injected by pipe 25. Instead of cresols there may be similarly employed high boiling.

polar compounds with relatively higher amnity for cyclic hydrocarbons and asphaltic substances than for parafiinic compounds. Such polar compounds may be selected from the following group: nitroaniline. aniline, chlornitrobenzene, nitrobenzene. nitroanisole. tetrahydronaphthalene, benzyl alcohol, .triacetin, diacetin, and other similar agents having higher afinity for cyclic hydrocarbons than for paraflinic compounds.

As a further example, denser molecules are separated from cracked naphtha introduced near the bottom of tower i, by inlet pipe d, at a temperature in the range of 400 to 600 F., and mixed in their spiral paths up through said tower with fusel oil alcohol vapors having a temperature of about 200 or higher injected by pipe 25, preferably in about equal proportions by weight to the weight of the charged hydrocarbons. A

. minor quantity of steam at a temperature of about 400 1 1, or higher is injected at'the jet discharge of inlet 85. The vapors nearing out let 6 are maintained at a temperature of about 350 F., with the pressurein the tower being substantially atmospheric or slightly varying below or above atmospheric pressure depending upon the desired end point for the overhead ractlon. The overhead vapors highly enriched in lighter and more paraifinic hydrocarbons may be passed together with residual steam to a fractionating tower wherein they are'fractionated to procure relativel heavy reflux before final condensation so that aportion of said heavy reflux maybe recycled to the upper part of tower i, through pipe 23. for control of the overhead vapors. Portions of the liquid aggregate collected on intermediate plates 2 and comprising mainly a mixture of alcohols and hydrocarbons of cyclic branched or unsaturated character are withdrawn from the side of tower i, by means of pipes H, to side stripper IS, in which they are refractionated in the presence of a small quantity of steam to cause the hydrocarbons and steam to pass overhead through pipe 22, to a condenser thence a separator in which a concentrate of hydrocarbons separated out as a liquid layer from a water.

layer, said concentrate of hydrocarbons being rich in hydrocarbons of cyclic branched or unsaturated character. Liquid bottoms withdrawn from the base of tower II, are largely composed of alcohols while side draws which may be removed from an intermediate plate by pipe 2!. from stripper II, are composed largely of alcohol and hydrocarbons which may be further fractionated to further separate hydrocarbons fromalcohol as described with respect to the stripping action in stripper [8.

Among some of the advantages which may be ascribed to the novel method and apparatus of this invention are:

1. Economic construction of an eflicient fractionating means for segregating specific components from a mixture of hydrocarbons, with elimination of several defects commonly found in packedtowers or bubble towers by:-

(0) Having a low pressure drop (b) Avoiding channeling (c) Avoiding flooding (d) Having less liquid holdup (f) Having less dead spaces and (g) Imposing closer to equilibrium conditions mateticularly the heavier particles out of the vapor stream.

It is to be understood that the apparatus may be equipp d with suitable indicating or recording devices for observation of pressures, temperatures, flow, etc., and that the apparatus is insulated where desired to maintain heat, and with valves-and pumps to regulate flow as required. The invention is not to be limited to' the particular form of apparatus herein described nor by any specific example or theory used for the purpose of illustration.

Having described my invention, what I claim and desire to secure by Letters Patent, is as follows.

1. The method for-segregating a liquid concentrate. of specific hydrocarbons from a mixture of hydrocarbons, which comprises dispersing -into a. vapor stream the mixed hydrocarbons in the form of liquid particles together with a volatility controlling compound having greater chemical attraction for the specific hydrocarbons, to be segregated, said vapor stream flowing upwardly and through a series of spiral passages, and coalescing said specific hydrocarbons together with volatility controlling agent by centrifugal action on said vapor stream carrying concurrently suspended therein the dispersed liquid particles.

2. The method for segregating a liquid concentrate of specific hydrocarbons of non-parafflnoid properties from a mixture of hydrocarbons, which comprises partially vaporizing said mixture dispersinginto a vapor stream liquid particles of an unvaporized portion of the mixed hydrocarbons together with a volatility controlling compound having greater chemical attrac (0) Being smaller in size for a given capacity tion for the non-paramnoid hydrocarbons to be segregated, centrifuging the dispersion to coalesce non-par'afdnoid hydrocarbons and associated volatility controlling compound in liquid pools over which the vapor stream is spirally passed, and withdrawing the non-coalesced dis persed hydrocarbonsoi paraihnoid character in vapor phase.

3. The method for segregating a liquid concentrate of specific hydrocarbons having relatively higher density from a mixture of hydrocarbons containing hydrocarbons of lower density, which comprises dispersing into a vapor stream discrete liquid particles of said mixture of hydrocarbons with partial vaporization of the hydrocarbons in admixture with a non-hydrocarbon organic compound having greater aflinity for the denser hydrocarbons of said mixture, and coalescing denser hydrocarbons together with non-hydrocarbon organic compound thus dispersed into liquid pools by imposing centrifugal forces upon the dispersion in a spiral flow.

4. The method recited in claim 3, in which a substituted cyclic hydrocarbon is used as the nonhydrocarbon organic compound and the specific hydrocarbons of relatively higher density are cyclic hydrocarbons.

5. The method recited in claim 3, in which an alcohol is used as the non-hydrocarbon organic compound and the hydrocarbons of lower density are straight chain paramns.

6. The method recited in claim 3, in which aniline is used as the non-hydrocarbon organic compound.

'7. The method for segregating a liquid concentrate of specific hydrocarbons having relatively higher density from a mixture of hydrocarbons containing hydrocarbons of lower density, which comprises partiallyvaporizing a substantial portion of the hydrocarbon mixture, leading the vapors through a series of spiral passages guided by an impingement surface against which denser particles are forced out by centrifugal action and caused to coalesce into a series of liquid aggregates of varying densities, redispersing portions of said liquid aggregates into said spiralling vapor stream, and withdrawing other portions of said liquid aggregates as liquid concentrates of the specific hydrocarbons having relatively higher densities, and separating vaporized hydrocarbons of lower density.

8. The method for segregating a liquid concentrate of specific hydrocarbons having relatively higher densities from a mixture of hydrocarbons containing hydrocarbons of lower density, which comprises vaporizing a substantial portion of the hydrocarbon mixture, leading the vapors through a series of spiral passages guided by an impingement surface against which liquid particles are forced out by centrifugal action imparted to the vapor stream and caused to coalesce into a series of liquid pools, redispersing portions of said liquid pools into said spiraling vapor stream as discrete liquid particles together with a volatility controlling compound having greater chemical attraction for the specific hydrocarbons to be segregated,

withdrawing portions of said liquid pools as liquid concentrates of the specific hydrocarbons having relatively higher densities, and separat-v ing vaporized hydrocarbon of lower density.

ERNEST A. OCC N.

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