US2110905A - Handling tar and asphalt - Google Patents

Description

March 15, 1938. G. F. CHASE BANDLING TAR AND ASPHALT Filed Aug. 20, 1934 F Glzczsa 7 ATTORNEY I R O m e w 806K 30 Patented Mar. 15, 1938 UNITED STATES PATENT OFFICE I 2,110,905 HANDLING TAB. AND ASPHALT George F. Chase, Hammond, Ind., assignor to Standard OilOompany, Chicago, 111., a corporation of Indiana Application August 20, 1934, Serial No. 740,605

1 Claim.

It is modern petroleum refinery practice to precipitate asphaltic, resinous and tarry matter from viscous lubricating oil stocks or from other oils containing the same by means of liquefied, noro mally gaseous hydrocarbons such as propane. For

instance, a 25% Mid-Continent petrolewniresiduum may be mixedwith 6-8 volumes of propane and subjected to a temperature of about 165 F. at a pressure of about 650 pounds, under which con- 15 ditions the asphalt will separate out as a lower layer whichmay be continuously withdrawn from the system. The asphalt is fluid at this temperature and pressure, partly because of its melted condition at high temperature and partly'because 20 of the presence of diluent propane. However, when this asphaltic material passes through a pressure release valve there is an instantaneous vaporization of propane which not only removes the diluent, but which effects instantaneous cool 25 mg, the net result of which is to cause the asphalt to solidify in a hard mass, which plugs the valve and the discharge pipe and which can only be handled with great difficulty. The object of my invention is to provide a method and means for 30 preventing solidification of asphaltic material in the release valve and discharge pipe, to prevent the cooling of the pressure release valve, and o avoid all difliculty in the handling of this oil-fr :e asphaltic, tarry or resinous material.

In practicing my invention, I inject a relatively non-volatile asphalt solvent or diluent in the high pressure line on the high pressure sldeof the release valve or through the release valve itself. The

introduction of the solvent into the relief valve 40 itself has certain advantages in that less solvent may be required and the heat of the solvent may -be utilized more effectively. The particular flux employed may depend upon particular conditions, upon the method of its introduction, and upon 45 the subsequent use which is to be made of the asphalt. When the asphalt is to be employed as a road oil or as a cut-back material, I prefer to employ auto tar distillate, coke still distillate,

pitch distillate, gas oil, naphtha, etc., and to use 50 the resulting mixture so that the flux may be left inthe asphalt when it is marketed and/or used.

'I'he'invention will be more clearly understood from the following detailed description.

In the accompanying drawing which forms a 55 part oi the specification and in which similar parts are designated by like reference characters in the several views,

Figure 1 is a flow diagram of'a high temperature propane deasphalting system showing the introduction of flux prior to or at the pressure re 5 fl.

lease valve;

Figure 2 is a cross section of a pressure release valve in open position showing the auxiliary -means for introducing flux; and

Figure3 is a similar cross section of the same valve in closed position. 1

I will describe my invention as applied to the propane deasphalting of a 25% residue from the distillation of Mid-Continent petroleum crude der non-cracking conditions by the use of steam and/or vacuum distillation. It should be understood, however, that the inventionis equally applicable to other viscous stocks containing asphaltic, tarry or resinous materials whether they are residual or distillate and treated or untreated.

In practicing my invention, I prefer to use propane as the asphalt precipitating medium, but it'should be understood that the invention is also applicable to other normally gaseous diluents such as ethane, butane, ethylene, propylene, etc. and it is also applicable to the use of normally gaseous solvents such as sulfur dioxide, The oil is introduced through line ill to mixer II where it is in-' timately mixed with propane from storage tank l2, line l3, pump l4 and line l5.v Oil is preferably introduced at a relatively high temperature, but

the mixture may be further heated by passing it through heat exchanger [6 in line I! on its way to settler I8. I prefer to use about 2 to 8 volumes of propane per volume of oil, but it should be understood that this ratio may be varied throughout very wide limits.

The settler l8 may be a horizontal cylindrical pressure vessel about 8' in diameter by 30' long and it may be mounted in a slightly inclined position, as shown in the drawing. However, I may use a vertical countercurrent treating apparatus,

'in which case a vertical tower is employed, the

temperature of about 165 F. and at a pressure 7 It should be understood, however, that this oil larly desirable when line 29 is relatively long or.

may be dewaxed, acid-treated, solvent-extracted, clayed or given any other treatments in the propane solution prior to' its introduction into flash chamber 2|. Propane from chamber 2| is conducted through line 24 and condenser 26- to gas trapout tank 26 and the liquid propane irom the base of this trap is conducted by line 21 to storage tank l2. Any ethane pr relatively noncondensible gases may be bled from the system through line 28.

The asphalt from the lowest point in the settler tank I8 is withdrawn through line 29 and pressure reducing valve 36 to flash chamber 3|. In order to prevent short circuiting I may employ a suitable baflle 32 between the outlet leading to pipe 29 and the inlet on line H.

The precipitated asphalt,=under the conditions hereinabove set forth, is very fluid and may be readily handled in line 29, but when the pressure .is released at valve 30 there is an immediate vaporization of propane which causes a substantial drop in temperature and which deprives the 'asphalt of its solvent or thinner. that the reducing valve and the short nipple beyond it are likely to become plugged with solid asphalt having a melting point of perhaps 150-170" F. In order to prevent the difllculties incident to the vaporization of propane'in the pressure release valve, I introduce a flux from storage tank 33, pump 34, line 35 and branch line 36, 31, or 38 to the asphalt solution which is being withdrawn. Branch line 36 introduces the flux at the point at which the asphalt solution leaves the settling tank and this modification is particuof narrow cross section and/or when there is likelihood of shutdown. Branch 39 introduces the flux immediately prior to the pressure release valve and this modification oflers the advantage of minimizing the tendency for any of the flux to find its way into the settler tank l9 where it might contaminate the propane-oil solution. Branch introduces the flux directly into the valve and this modification will be more readily understood by reference to Figures 2 and 3.

Valve 30 may consist of a cylindrical casing 39 containing"a rotatable core 40 provided with a passage 4| which may bealigned with pipe 29 and nipple 29A. In view of the evolution of propane inthis valve and in view of the tendency of the valve to become plugged, I prefer to have thisopening slightly tapered from pipe 29 to nipple 29A, and to employ a nipple which is of slightly larger diameter than pipe 29. Another hole 42 is drilled in the core for alignment with pipe 38 when opening 4| is in alignment with pipe The result is 29 and hole 42 communicates with opening 4|. Thus the fluxed liquid is mixed with the asphalt solution directly in the valve itself. This fiux is preferably introduced in a heated state so that it overcomes the chilling effect of thevaporization of the propane. It also may be said to act as a lubricant to facilitate the ejection of the asphalt core-through this pressure release valve.

I may provide an enlarged chamber 43 at the centerof thecore (by boring a, transverse hole and plugging up the ends) so that, in efiect, the cylindrical plug of asphalt which moves through opening 4| is surrounded part by a jacket of flux liquid which insures the fluxing of the asphalt, at least on its peripheral surfaces, and thereby facilitates its discharge into nipple 29A and flash chamber 3|. On the other hand, the enlarged opening 43 may merely serve as a mixing chamber for the solvent or flux and the asphalt. Figure 2 shows the valve in open position and Figure 3 shows the same valve in closed position.

As a flux liquid I prefer to employ a light hydrocarbon oil such as gas oil, pressure for flash distillate, acid sludge distillate, pitch distillate, or other cracked distillates. I may, however, employ ordinary naphtha or light mineral oils and I may employ benzol or other aromatic solvents, In some cases, it may be desirable to employ well known tar solvents such as carbontetrachloride and other halogenated light hydrocarbons, car- .bon disulfide, etc. As hereinabove stated, how ever, I prefer to employ highly cracked and/or oxidized hydrocarbon flux oils because such oils are readily available in ordinary refineries and they are highly desirable constituents in road oils, cut-back asphalts, and the like.

The fluxed asphalt from pressure valve 30 is introduced into propane still 3| which is in turn provided with steam heating coil 45. The propane is removed through line 46, then through bypass 41 or compressor 49 to condenser 49 and trap 50. Liquid propane is returned through line 5| to the propane storage .tank I2 and relatively non-condensible gases are discharged when necessary through line 52. 'The fiuxed or cut-back asphalt is withdrawn from the base of the propane still or flash tower 3| through line 53, pump 54 and line 55, which leads to suitable storage tanks.

While I have described a preferred embodiment of my invention, it should be understood that I do not limit myself to any of the details GEORGE F. CHASE.

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