US2762758A - Asphalt manufacture - Google Patents

Description

p 11, 1956 J. M. CRANMER 2,762,758

ASPHALT MANUFACTURE Filed May 5, 1953 Mm? (00L 4N7 AIDA 4Z7 LEVEL INVENTOR. JZM/v M OM 4/4452 mx bw ,4 GENT United States Patent C ASPHALT MANUFACTURE John M. Cranmer, Riverside, R. I., assignor to Socony Mobil Oil Company, Inc., a corporation of New York Application May 5, 1953, Serial No. 353,153 4 Claims. (Cl. 196-74) This invention has to do with a process for manufacturing asphalt and, more specifically, has to do with improvements in the manufacture of air blown asphalt.

As is well known in the art, air blown asphalts have been prepared by air-oxidizing various petroleum residues and/or fractions in heated stills or towers and the like. Difliculties incident to air blowing of an asphalt charge stock, have been control of asphalt charge and air and control of the resultant oxidation temperature. In general, it has been necessary to reduce the flow of asphalt charge and/ or the air charge in order to prevent the temperature from rising excessively. Obviously, a reduced flow rate is responsible for a curtailing or slowing up of production in a given operating unit. In addition, failure to control one or both of the foregoing factors has led to the formation of explosive mixtures. v

Numerous techniques have been resorted to in an effort to provide better control over the air-blowing-operation. For example, steam and/or air have been introduced into a heated asphalt charge stock to provide better agitation of the heatedasphalt charge stock, and cooling of the latter can be effected by circulating a suitable cooling medium through a coil disposed in the reaction vessel; these techniques are described by E. W. Gard and P. Subkow in United States Letters Patent 1,911,114. Cooling by means of an inside coil is sub- 2,762,758 Patented Sept. 11, 1956 the need for close control over the quantity of water so added; when an excessive quantity of Water is introduced into a hot asphalt charge, the water is converted into a large volume of steam with the result, that the asphalt charge surges up through and out of the still.

Although steam has been introduced hitherto into the vapor space of a reaction vessel above the heated asphalt charge stock, as described by Tijmstra, and although water has been injected directly into the heated asphalt charge stock, as described by Aldridge, it has been generally recognized in the industry that water-as opposed to steam-should not be allowed to come in direct contact with hot asphalt. In the past, water has been introduced by accident into a heated asphalt charge, with disastrous results. Water coming into contact with the heated charge, at BOO-500 F., so disturbs the equilibrium that the charge surges to the top of the vessel and overflows. In some instances, in fact, the surge has been so pronounced that the top of the vessel has been ruptured and destroyed.

Despite the apprehensions of those working in this 7 industry, it has now been established that water can be ject to several short-comings. For example, the amount of cooling which can be realized is limited by the amount of heat exchange surface so installed. Moreover, the outer surface of the coil becomes coated with carbon and other materials, with the result that heat exchange efficiency decreases. Additionally, the still or unit must be cleaned periodically to remove coke and other mamum, and the coil interferes with the cleaning operation, thereby making the latter moer expensive.

A later development involves the introduction of steam into the vapor space of the reaction vessel, in order to dilute the vapors therein and thereby to prevent the formation of an explosive mixture. The latter development is described by S. Tijmstra in 1,975,563. Although steam is elfective as a diluent, it is necessary to use excessive quantities of the same in order to cool the vapor space, and, even though large quantities of steam are so used, little or no cooling of the reaction mixture is ac,- complished.

Another procedure considered for controlling the oxidation temperature is explained by B. G. Aldridge in used safely and satisfactorily as a coolant when introduced into the vapor space of the reaction vessel and on to the surface of the asphalt charge being air blown in the man ner described below.

It is an object of this invention, therefore, to provide a process for manufacturing asphalt with close control over the temperature within the reaction vessel.v It is also an object of this invention to provide a process characterized by a high degree of safety in operation. Another object is to provide a process characterized by cornplete flexibility in the amount of cooling required and by eflicient heat exchange. Still another object is the provision of a process of low installation, operating and maintenance expenses. Other objects of the invention will be apparent from the following description.

It has now been found that the foregoing objects are accomplished by introducing a controlled amount of water into the vapor space of the reaction vessel and onto the liquid surface of the heated asphalt charge stock being air blown. The heated asphalt charge is maintained at a sufficiently high temperature when the water is so introduced, such that the water is completely evaporated when it comes into contact with the surface of the asphalt charge. In practice, the blowing temperature is maintained sufficiently above the boiling point of 1,988,766. The procedure of the last-mentioned patent calls for injection into the heated asphalt charge stock of a volatile liquid such as water; water serves as a cooling medium. This procedure is characterized by several disadvantages. It is necessary to exercise considerable operating care and to use controls in order to prevent water to insure complete vaporization of the added water.

As illustrated in the attached drawing, a suitable asphalt charge stock at about 425 F. in valved line 1 is introduced into a lower section of still 2. Air is added to the still through line 3, and is dispersed into the asphalt charge stock through air nozzle pipe, turbo aerator or spider 4. The liquid level of the asphalt charge stock is indicated by 5. By way of illustration about 800 cubic feet per minute of air and -90 gallons per minute of a Kuwait (Near East) flux having a softening point of 80-85" F., are so added to still 2. The temperature of the still is maintained at about 500 F.

The temperature in still 2 is readily controlled by introducing a controlled quantity of water through line 6 into the vapor space of still 2. It will be understood that one or more lines such as 6 can be used, that a spray or battery of sprays can be used to bring waterv into the still, and that meters and coolers can be included in line 6; all are well-known expedients in the art. The quantity of water so added to the still can be related to the temperature within the still by such means, more Water being added as the temperature is increased and less water being added as the temperature is decreased. With the quantities of charge stock and air given above, 0.54 gallons of water are added during a period of "one minute.-

As shown, the outlet of water line 6 is above the asphalt level 5. Line 6 is generally at least several feet above the asphalt level, as for example, in a unit sixty feet high and with the asphalt level at about the forty-two foot ma 7 With the aforementioned addition of water, the temper ature of the still is maintained within a range of it rn contrast to this, when water Was omittedfroni the procedure, temperature control was unsatisfactory. In addition, it was necessary-when water was absent-to "resort to su' h eitpedijems as restricting the air how 'and/ or the asphalt charge in "order to control the temperature.

7 Gasesfin still 2 are removed through line 7. The gases lly nitrogen, a'sm'al'l amount of oi ygei were; the oxidation reaction and steep} from p 7 ing water, and oil vapors. The asphalt in ,2 nera l bmp t f n Pe e cf hi lvessel, "allowing'for a vaporfspacejof about thirtyper pent. Asphal t is withdrawn from still 2 through 'ei Although the temperature of operation 'is Shawn above to be about 500 F.,it is to beunders'tood thatany tentperatures suitable for, an asphalt blowing operation can be used-injthe procedure described herein. Generally, however, preferred operating temperatures fall within the 'ta'nge of 450-550 F. wlfen'no catalystjis used. Tempera ure's "as jlowas about 350 'F. is used when a suitable "cat'alystis employed. v V

(V Itisalso contemplated herein that catalystsfor'rriodifyin'g materials jean housed in the preparation of lasp'lfalts. For ekample'pho'sphoric'acid can be added to the asphalt "charge stock, either to line '1 or a separate line (not shown) with an inlet positioned above or below the 'asphaltlleveli, in which event the operating'conditions 'are preferably those des'cribedin copending application SerialN'o. 277,631, filed March 20, 1952. v Airis used as the sourceof oxygen in viewofits 'iew "cost and availability. I s t The operating technique of this invention is also useful for contacting oxidizing gases with other oils such as animal, marine, mineral and vegetable oils. By. Way of illustration, 'rape'seed'oil can be eitectively air-blown to a bodied oil useful'incompounded lubricants.

p Itis to fbe understood that the operating technique desjc ribedli'ereinisapplicable 'to batch operation and to on ne t vi ita on *Infa 'c ontiiluousoperation, it has'bcen foundthat ZQOO barrels per day ot a l30 'rne1ting point asph'altfca'n producedlina givenhnifwith nocoling water added. I 'n 'c'on'trast, nsin gfthe same unit and the sam charge sto'k under coinparableoperating conditions, but with 'ioui 'g'allonsof water perminute added in 'accordance 'with the new techniqu'e, 3,000 barrels per day of the same asphaltpifoducthav'fe been produced. This is 'an increase n typer 'qentjntheeapiacity of a single operating unit. Ihe asphaltfcharge stocks suitable for us'e'herein' can be of'variedfcharaeter, Broadly, anypetroleum residuum 'ng following separation therefrom er v o'c'arbons through lubricating oil ff ractions,or any el'ativelyf'high molecular weightextract obtained-b petroleum refining, can be used. For example, residua from Pennsylvania, fli [id-Continue'nt, California,

Middle Ea'shNear- East, Venezuela, etc. cru'des'can be used. Or in other words, residua from paraihnic, haphthenidfaromatic,high sulfur, etc. stocks are suitable. ItWillbe recognized, of course, that differences in charge stocks arereflecte'd in differences in the 'char'acter 'of the :final productscontemplated herein, and such di itere nc es areindicated below. Typical advantageous charge stocks area Qasper flux ha'ving an 85-90 F. softeningpoint, whichfis representative of 'a Mid-Continent charge; Lagunfllas huxeshaving softening points of 70 F. and F., such materials typifying Venezuelan residua charges; a 27% Kuwait residuumhaving an 80-85 softening point, and a 24% Kuwait residuum having a 90 "softening point, such typifyi'ng Near East charges; a

tar having a 95 F. softening point and obtained by a Duo-Sol treat of a heavy lubricating oil, and a tar having a 125 F. softening point and obtained by a Duo-Sol treat of a heavy lubricating oil.

I claim:

1. In the manufacture of asphalt wherein an asphalt charge stock is air blown at elevated temperature in a vessel in which a vapor space is maintained above the liquidlevel of the asphalt charge stock being air blown therein, the improvement which co pr ises: introducing into the said vapor space and onto the heated asphalt charge stock, liquid water inan amount sufiicient to control the temperature of said asphalt charge stock, and insufficient to so disturb the equilibrium that the asphalt charge surges to the top of the vessel and overflows said asphalt charge-stochbeing maintained at a temperature al'apve the boiling pointof water. I I

'2. In the manufacture of asphalt wherein an asphalt har jejstdck is air bldwn at a temperature between about 350 P. and about 550' 5., in a vessel in which a vapor Sp-ace 'maintain'ed above the liquid level of the asphalt "charge stock being air blown therein, the improvement which comprises: introducing into the said vapor space and onto the heated asphalt charge stock, liquid water-in a amount "sufficieiitto control the temperature of said jlt fcharge stock, 'and insuffi cient to so disturb the iurn that the 'asphalt'charge surges to the top or I se l, and overflows said asphalt charge stock being maintained at "a temperature above the boiling point of water.

3. In the manufacture of asphalt wherein an asphalt charge stock is air blow'ri'at a temperature of about 500 15., in a'vessel in which a vapor space ls'rnaint aine'd above the liquid level of the asphalt charge stock being air blown therein, the improvement which comprises: introduc'ing into the said vapor space and onto the heated asphalt charge stock, liquidwater'in an amout sufiicient to'the ves'sel "at the rate of about'OIS to 4 gallons per minute. s H

4. In the manufacture of asphalt wherein an asphalt chargestock is air blown at a temperature of eiboutESOO F.,in a vessel in alvap o r space is maintained awe the liquid level of 'tl'ie asphalt charge stock being air blown "therein, theirnprovement which comprises: introucing in'to the said vapor space and aim the heated iasphalt char gestock, liquid water in an amount sufficient to controlth'e temperature of'sai'd asphalt charge stock,

. an nsu'fficient to'so disturb the equilibrium that the asph'alt lcha'r'ge sur'ges to thet'op of the'v'ess el'aiid overfio'vvs, -said asphalt charge fsto'k beinginaintained at a temperature of -al'a'o'ut 500 F., the ratio between the rates of "asphalt charge stock, air and water charged to the vessel being the following:

(a) Asphalt'chafg stock, as gallons per minutefabout l; (15) Airfas cub 'f eet per'rni'nute, about 10; and

(a) 'Water, "as gallons per minutejup toabout "0105.

Reference Citd in the file of this patent

Claims (1)

1. IN THE MANUFACTURE OF ASPHALT WHEREIN AN ASPHALT CHARGE STOCK IS AIR BLOWN AT AN ELEVATED TEMPERATURE IN A VESSEL IN WHICH A VAPOR SPACE IS MAINTAINED ABOVE THE LIQUID LEVEL OF THE ASPHALT CHARGE STOCK BEING AIR BLOWN THEREIN, THE IMPROVEMENT WHICH COMPRISES: INTRODUCING INTO THE SAID VAPOR SPACE AND ONTO THE HEATED ASPHALT CHARGE STOCK, LIQUID WATER IN AN AMOUNT SUFFICIENT TO CONTROL THE TEMPERATURE OF SAID ASPHALT CHARGE STOCK, AND INSUFFICIENT TO SO DISTURB THE EQUILIBRIUM THAT THE ASPHALT CHARGE SURGES TO THE TOP OF THE VESSEL AND OVERFLOWS SAID ASPHALT CHARGE STOCK BEING MAINTAINED AT A TEMPERATURE ABOVE THE BOILING POINT OF WATER.

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