US1866504A - Process for cooling molten bitumen - Google Patents

Description

y 5, 1932- KIRSCHBRAUN v 1,866,504

PROCESS FOR COOLING HOLTEN BITUMEN Filed ma 29. 1930 v 3 m2 H5 I; fl

Patented July '5, 1932 i UNITED STATES PATENTO'FFICE- LESTER 'KIRSCHBItAUN, OF LEONLA, NEW JERSEY PROCESS FOR COOLING MOLTEN IBITUMEN v Application filed May 29,

This invention relates to improvements in the production of aqueous bltumlnous emulsions, and is more particularly concerned with improvements in the production of aqueous dispersions-of the type disclosed in my prior Patent No. 1,615,303, granted J aning the same to agitation in the presence of Y such for example as colloidal clay,

"that the temperature of an aqueous suspension of colloidal material under conditions which serve to induce and promote rapid attenuation of the bitumen into threads and subdivisionthereof into finely divided particles dispersed in the aqueous vehicle. The colloidal material which may be employed in carrying out a process of the character described may comprise any one of a class of materials which are readily wet with water and capable of forming a viscous plastic mass therewith, bentonite, mineral pigments, slate dust, powdered mefalilic oxides," hydroxides and silicates or the In the commercial manufacture 'of aqueous bituminous emulsions of the type set forth it is essential that the bath of material in which the dispersion'is-being effected, be maintained at suitably controlled temperatures such as will provide a medium of sufficient viscosity to produce that degree of nternal viscosity which is necessary to effect largely upon the character of bitumen being,

emulsified, but in general it may be stated the bath should approximate the, melting point of the bitumen and at all events not more than aproximately 10 F. above the melting point thereof.

In the commercial'pract-ice of the process set forth in said patent, the temperature of the bath may be maintained at a suitable point by providing the emulsifying vessel with jackets forcirculating a temperature 1930. Serial No. 456,952.

regulating medium and/or by adding water frlom time to time to the material in the vesse I have found in actual practice that it is quite diflicult to maintain at all times the proper conditions of temperature in the emulsifying vessel, when the asphalt or other material to be'emulsified is fed in heat liquefied condition directly to the emulsifying vessel at a temperature considerably above the temperature of the mass in the vessel. Under these conditions, particularly when the asphalt is fed at a rapid rate, it frequently happens that local coalescence of emulsified particles occurs in the vessel where the hot molten asphalt strikes the material therein, causing considerable agglomeration of these emulsified particles, which must be overcome by additions of substantial quantities of water, thus resulting in the production of an emulsion containing more than the optimum amount of water in the external phase. It will be appreciated, of course, that it is desirable to produce an emulsion ,containing a minimum quantity ofwater in the external phase for any degree of dispersion, consistent with suspendable product.

According to my present invention, the con trol of temperature is facilitated, the production rate increased and the process other- 30 wise improved by the provision of a cooling stage for the molten asphalt immediately prior to its introduction into the emulsifying instrumentality, such that the asphalt may be reduced to a temperature about 50- degrees 35 otherwise improving upon the commercial manufacture of this type of emulsion. This difi'erential of, temperature will obviously (vary somewhat, depending upon the consistency of the asphalt the rate of heat radiation from the emulsifying apparatus and the frictional heat, developed during emulsificamo tion.v

' say 100 degrees conducted through i 'strumentality.

In the accompanying drawing, there is 2 shown a diagrammatic illustration of apparatus that may be employed in carrying out the invention.

The base to be emulsified preferably consists of a bitumen, non-fluid at normal temperatures, such for example as asphalt, pitches, or the like, having melting points of, to 200 degrees F. These materials are emulsified in heat liquefied condition, but as already stated, it is the purpose of my invention to bring them to the. emulsifying bath at a temperature not more than about 50 degrees to 10(1 degrees F above the melting point thereof. In order that these materials may be conveniently handled and pumps from one point to another in the emulsifying plant, it is necessary that they be heated to a temperature sutliciently high for rendering them fluid enough to permit pumping through pipes, et cetera, and this temperature is generally considerably higher than that at which it is desirable to introduce the same into the emulsifying bath. For example, when emulsifying asphalt of, say 140 F. melting point, ball and ring method) the asphalt must be heated to about 300 to 325 F. in order to condition it for ready handling. The asphalt may be heated to this temperature in any convenient way, and conducted by means of pumps (not shown) through a feed line 10 to a storage tank 11. 'This asphalt may belemulsified in an emulsifier of the general type shown at 12, which may consist of a cylindrical tank, within which is mounted a baffle 13 concentric with and spaced from the walls of the tank and open at its upper and lower ends;

Suitable stirring or-agitating blades 14 are fixed upon a vertical shaft 15.driven from any suitable source of power, and mounted interiorly of the baffle so as to agitate the mass of material in the emulsifying vessel.

The emulsifying media may be stored in a suitable receptacle emulsifying instrumentality through a valved pipe 17 so as to feed the suspension of emulsifying media into the material undergoing agitation within thebafile. The asphalt is likewise fed into the mass of material within the 'baflie through a feeding pipe 18, after previously having been cooled, in the manner hereinafter to be more fully described, to a temperature of about 50 F. above the temperature of the mass in the emulsifying in- The propeller or agitator blades 14 arepitched so as to force the material imdergolng agitation within the bafiie downwardly, the material then taking an upward course in the annular space between the battle and the wall of the tank 12 and being thus recirculated for further agitation within the bafile. "The finished emulsion may be withdrawn from the tank 12 continuously or cooled to the desired degree by means 0 the smaller chamber 21 and 16 and conducted to the prior to the introduction thereof into the emulsifying instrumentality, I may provide an enlarged chamber 20 within which is maintained a smaller chamber 21-to which the hot asphalt may be fedfrom the storage tank 11 through a valved feed pipe 22. hollow drum-or cylinder 23 is mounted for rotation in the chamber 21, the diameter of this drum or cylinder being such in relation to the height of the chamber 21 that a portion only of the peripheral surface of the drum is submerged within the 'molten asphalt in the chamber-during the rotation of the drum. A suitable cooling or refrigerating medium may be continuously circulated through the interior of the cylinder or drum 23 as by means of an inlet conduit 24 and outlet conduit 25. If desired, the drum 23 may be provided with an internal concentric cylinder (not shown), and the cooling medium circulated through the annular space between the outer and inner drums. The drum 23 is rotated slowly and during such rotation picks up a thin film of the asphalt from the chamber 21, this film being ragidllly t e cooling medium circulating in the interior of the drum. A doctor blade or apron 26 is suitably mounted so as to be in free contact with the surface of the rotating cylinder to thereby remove the cooled asphalt continuously therefrom and discharge the same as shown into the enlarged chamber 20, the doctor blade for this purpose having its outer edge extending beyond the corresponding wall of being inclined downwardly so as to permit free flow of the cooled asphalt over the surface of the blade for continuous delivery to the enlarged chamher. The flow of asphalt from the storage tank 11 to the chamber 21 is maintained in such ratio relative to the withdrawal of the cooled asphalt from chamber 20 through the pipe 18 that the level of the asphalt in the Y enlarged chamber will preferably be at all times below the bottom of the smaller chamber 21, thus avoiding material transfer of heat from the hot asphalt in the chamber 21 to the cooled asphalt in the enlarged chamber 20. For-this purpose also there may be employed,-if desired, suitable liquid level regudevices for the enlarged chamber20,

lating as well as for the smaller chamber 21, the

overflow being conducted to the storage tank By'the arrangement as thus described, I have made it possible to emulsify bitumens or the like in a bath which can be consistently maintained at temperatures approximating the melting point of the material to be emulsifie without substantial variation of this LA to a su temperature due to the temperature of the incoming bitumen and without afiecting the normal plant procedure incident to the ready and convenient han and transfer of the material to be emulsi through pumps; feed lines, et cetera.

I- claim as my invention:

tially predetermined temperature, which comprises maintaining a pool of molten bitumen, picking up the bitumen from said pool in a thin film and subjecting said.

film of bitumen to a cooling media in indirect contact therewith, and continuously delivering said film of cooled bitumen, in a liquid state, to a bulk su Egly.

2. A process for coo g molten bitumen to a predetermined temperature above the melting point thereof, which comprises maintaining a pool-'ofithe molten. bitumen, picking up the bitumen from said pool in a thin film and subjecting said film of bitumen to a. cooling media in indirect contact therewith and continuously delivering said film of bitumen, in a li uid state, after subjection to said cooling me um to a bulk supply maintained out of contact with said pool.

In testimon whereof I aflix my si ature.

L STER KIRSCHBR UN.

rocess for cooling molten bitumen.

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