US2878650A - Method of cooling thermoplastic and viscous materials - Google Patents

Description

March 24, 1959 1 c. KRCHMA METHOD 0F COOLING THERMOPLASTIC AND VIsCoUs MATERIALS Filed June 10, 1955 INVENTOR l y aff/@fr /ff OREY ' to accurate control.

METHOD OF COOLING rI'HERMoPLAsr'ic AND Viscous MATERIALS f Ludwig C. Krchma, Kansas City, MO., assignor to Socony Mobil Oil Company, Inc., a corporation of New York Application June 1o, 195s, serial No. 514,414 3 claims. (c1. sz-9s) The cooling of thermoplastic materials, of which highly viscous oils, and particularly high melting point asphalts, are typical,- -fpresents a rather serious-problem. This invention is directed to an improved method therefor. It Will be discussed with specific reference to highly viscous oils.

Cooling of highly viscous oils through higher temperature ranges, say down to about 400 F. from the processing temperatures at which they are produced, usually of the order of 400 F. to 800 F. and above, is normally not too serious a problem, and is capable of being handled in the usual exchangers, and the like.

Below about 400 F., the problem becomes dilferent. The oil being cooled becomes increasingly viscous, and proper contact of the material with the tube walls of a tubular heat exchanger becomes ditiicult to obtain because of lack of turbulence in the oil stream. Pumping pressures become increasingly costly because of increas ing viscosity, particularly when it is realized that poor contact of Oil and tube wall Yrequire greatly increased length of -oilpassage due to decrease of heat transfer through tube walls. Itis at the same time rather impractical to pass the cooling uid through the tubes of a conventional exchanger while passing the oil around the tubes because of fouling and coking diliculties often arising from the very natureof-,theheavy oils when so handled.

In many instances, it`is` desirable both to store these materials `at elevated. temperatures,- say of the order of '300 F. to 400 F., but to` pass them therefrom to a processing. step, such as mixing, or the like which must be.conducted at a lower temperature, such as a temperature of from 225 to 275 F.

Obviously, it is not economical to attempt to cool such products by mere storage. (It is quite common ,to ship hot asphalt in tank cars for quite long distances without substantial cooling.)

It is therefore an object of this invention to provide a method of cooling heavy, viscous oils, such as high melting point asphalts, and the like, without the use of heat transfer through surfaces separating the oil from the coolant. It is a further object to provide a rapid and effective method for such cooling, one readily susceptible It is an object to provide a nonhazardous method for cooling, and one that employs a minimum of costly equipment.

This invention is based upon the discovery that, quite contrary to expectation, cooling can be readily effected by admixing liquid water with,a conned moving stream of hot viscous Oil that is immiscible with water.

This is quite contrary to previous experience within the oil industry, for it is well known that the adventitious mixture of water with hot viscous oil results in the formation of foam and froth in volumes many, many, times greater than that of the oil and water involved. Major care is always taken when pumping heavy oil, above the boiling point of water, into a storage tank, to see that the storage tank is substantially free of acci- 2 j dentally` present water. Even in applying asphalt satu rants to rooting felts, papers, and the like,` the small amounts of moisture present in the'felts, etc., from Stor age in ordinary atmospheres, frequently gives very serious foaming troubles.

This method is also quite different from vthe older method, well known in the asphalt blowing art, of controlling the temperature of a blowing still byintroducing water, or propane, etc'. (i.e., a material vaporizable below the temperature of the still content), into the oil being blown. It has been appreciated for some time that water, when introduced into-an agitated lbody -of hot oil, evaporates therefrom without much'foaming difticulty. The blowing air in the blowing still provides such agitation. The present method, contemplates Aadmixing the water with hot oil, an operation which, in the light of prior experience, could be expected to be conducive to excessive foam production.Jv i

This method also differs from proposals: for cooling asphalt blowing stills by spraying water'into Vthe space `above the air-agitated oil in such a still. There, the water contacts only the surface of the oil lbody. Here, the water is intimately mixed with hot oil.

In order that this invention may be more readily understood, reference is now made to the drawing whic forms a part of this specification.l

In this drawing, the single figure of which is highly diagrammatic in form, 1 represents a tank containing hot, high melting point asphalt, which is to be cooled. This oil is pumped through pipe 2 by pump 3 over through pipe 4 into tank 5. Both tanks 1, and 5, are rather conventional in form, and equipped, as shown, with the usual roof hatches 6, and may be equipped, if desired, with air aspirators such as 7, actuated by steam or air from valved pipe 8. Such tanks, in comparatively small sizes, around 1000 bbls. or less, are commonly used in specification asphalt manufacture. At point 9, a controlled small amount of liquid water is introduced from pipe 10, under pressure of pump 11. This water may be withdrawn from tank 12, or from water main 13, 14. The amount of water so injected may be controlled in any of several ways. Pump 11 may be a metering pump such as those commonly used for injection of chemicals etc., into a owing fluid stream. Control may be effected by valve 15, in a usual manner, in which case, if pump 11 be a positive displacement type, ya pressure controlled bypass 16, around pump 11 will be required. A,Oran automatic setup, indicated in very general form `by observation point 17 and responsive valve v18, can be used, the observation at 17 being rate of liow, temperature, or a combination of these. All such methods of control and proportioning of two streams of liquid from mere manual control to elaborate proportioning instrumentation, are well known in the art. In general, for heavier, viscous oils, the simpler the control, the better. In most cases, with a pump 3 capable of operating at reasonably constant discharge, manual control at valve 15 will be adequate.

It will also be realized that the hot oil to pump 3 may come from some other source, such as from a manufacturing operation through pipe 19, or that the contents of tank 5 may be recirculated to cooling, as by pipe 20, or that any combination of such sources could be used.

The proportioning of Water to oil is dependent upon the rate of cooling desired, and the major criterion of control is that substantially no liquid water shall be dis charged from the end of the mixing pipe into the tank. Even this is advisable rather than mandatory, for a small -amount of free water can be tolerated, particularly when the tank oil is well above the boiling point of water.

Contrary to expectation, the amount of water so added 3 can range upl to that necessary to elect substantial coolirig in single'passi" For example, an asphalt o'f 225 F. soft'point can be cooled n a single pass from about 380? to about 320 F.,1requiring.about 4.8 gallons of material to a temperature above its soft the b'olingpontof water; discharging the resulting mixtion and escape of water vapor.

62?'.F. waterperlminute, pumped into oil flowing at a 5 2. The method of cooling highly viscous heated petto ratefof about 265. barrels per hour. If desired, the operaleum oil fractions, of the nature of asphaltic residues and i l tion canbeconducted at lower rates. the like, which compriseszpassing the oil which is at a The piping sizes are in no way critical, except that the temperature substantially above.l thev .boiling .point of diameter .and length of the mixing pipe, and the nature of Water, through .a conduit as aconfnedfstream; continuousthewaten injection ttingshouldbe such as to secure ade- 10 ly admixing liquid water'in controlled small quantities"` fl quate lmixing before discharge.. .Since .such devices are with `rsaid material while.passing through'y saidflconduit, quite common in the oil and other. industries for. various to c`oo1 said material to -a'temperature' above-its-softpoint purposes .and the manner of calculatingsizes, etc., is well and above the boilingpoint of water; .discharging `the re- `known. inthe. art.,.no.discussion is .oiered here. A sulting mixture into a vaporzng space; and permitting .,Actua1 operating .resultsof `aV seriesl of cooling runs .are 15 the separation and-escape:` of waterwapor. Y n n setjortlflelow. inTable I. i VVV3. The method of coolig'highly'viscou's heated petrol f 'Table l spiral t Asphai Total aspiran i Highest .-Ave. Total B-.tnrsrnn 'man Asphalt Temp. yTemp. Quant. yfransfer Water Water @Water 1Water'f 'Tlme Of' vexrm'xzed f: iB tLuJs Trial Runs `Sott Before After Asphalt "-Rate, Temp., .,Rate, -.Rate, I Quant.,A (inject. ...vlirom` z .Removed Point Injectv., .,Inject., Barrels yBblsJ degrees Gala] Gals# Gallons: InHrs. Asphalt From t .Hdegrees =degrees t tvHr. .Min `Mln.` .fksrihalt 220 v 350 y332 00 2.5 .1.4.3 se 1.1.00 1 798,000 1-:megan 220 4332 31a 60 3.o 1.73 v 7s .0. 75 267, .725,000 225 3,40 325 60 3.0 1.75 105 #1.00 975, 000 `975,000 225 337 V297 50 1 3.5 :2.10 21s 1. 75. 1,107,000 `2,-040, 231 .350 `28s 60 3. 5l 3.00 .V360 2.00,n 1, 070, 000 3,340, 224 '360 200 65 n5.5 '3.90 y350 1.50' 2 150,000 r `3,225, l 220 ."435 285 00 :6.5 4.00 .2039 i250, 506.1000 ..=.e,490. 225 380 320 02 5.0 4.80 220 y0.75 2,706,000 .2.030, 225 '320 300 62 0.0 5. `50 110 A0.33 3,054,000 1,018',

.E'an'd 8'0ne pass operation.

In Athe-aboveiruns, runs 5 and v23 .are once-through runs. All'others:arerecirculating runs, in whichthe `oil to be cooledwaswithdrawn fromthe same. tanks -into which` the mixed oil;and1water streams discharged. '.In :all ot ythese runs, the water ashed to steam and readily disengaged from the asphalt. Asphalt and foam samples `takeniromrthe tanksimmediately after cooling7 showed.. substantially nomoisture. Foam was not voluminous.. There wasmo Serious-hazard apparent from foam, ifromre; or from explosion. The .process is simple `.''1nd.\economical,.r'frorn.;the.standpoint of operating and vfrom' equipment and maintenance considerations.

rI. claim:

1.."'IIhe :methodiof coolingy a thermoplastic material which isfnot'misc'ible with water, which comprises: passingame-thermoplasticmaterialwhich is ata temperature "substantially: above `the;boiling^pointof water, .through 'aac'ctnduit 'as a fconned stream; continuously` admixing -liquid ivater in controlled small rquantities with saidma 'teial fu'ihile 1 passing t through fsaid conduit, to coolzsaid leum oil ffractions, of the-.nature of .asphaltic vresidues and .i

vthe like, which comprises: passing .the oil which is `at `a temperatureof -about 4009 F.,..through a conduitA as a confined stream; continuously admixingiliquid water,

an amount from about.0.5to.fabout 4-k percent Aby volume of thev oil, with .said oil .whilepassing `through Asaid;- on@ duit, to `cool saidoil to astemperature aboveits soft point and `above= the boiling point. of water;..discharging.;the

resulting mixture into a vaporizing space; varidperrnittingA point and above i l

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