US2055459A - Process for making asphalt - Google Patents

Description

Sept. 22, 1936. f A. GUTZWILLER ,0 5

PROCESS FOIR MAKING ASPHALT Filed Aug. 1, 1952 1 Water Low Penetration Asphalt Blown Asphalt Inventor: A "4 M By his iAitorney:

Condensate I Oil I Patented Sept. 22, 1936 UNITED STATE PROCESS FOR MAKING ASPHALT Adolf Gutzwiller, Amsterdam, 'Netherland, as-

signor to Shell Development Company, San Francisco, Callt, a corporation oi'lDelaware Application August 1, 1932, Serial No. 627,206

In the Netherlands August 4, 1931 11 Claims.

(Cl. MiG-1%) This invention relates to the art of making blown asphalts and is more particularly concerned with a continuous method of producing asphaltic materials allowing flexible control of o the treatment. Y It is well known in the art that the properties of manufactured asphalts can be regulated by the conditions of the oxidizing treatment to which the raw materials are subjected during the manufacturing processes. A numberof treatingmethods and apparatus are known at present, whereby various carbonaceous residues are subjected to oxidation and evaporation, or distillation, for producing asphalts of the desiredfqualities.

if) Among the properties most commonly determining the quality of an asphalticproduct, or its 7 suitability for any particular use, canlbe mentioned: softening point, viscosity, flash point, penetration-temperature relation and ductilitytemperature relation. Each of the well known uses of asphaltic materials, such aspaving, roofing, pipe-coating, etc., requires a moreor less definite set of properties which must he possessed by the material most suitable for the particular service in question. In order to obtain aproduct possessing a predetermined set of characteristics, it is necessary to maintain in each individual case of operation a definite combinationof certain operating conditions, such as temperatures to which the material is subjected during treatment and the rate and the extent of oxidation. Gather conditions being equal, the reaction of oxidation and its extent are markedly influenced by the composition of the material being treated, by its temperature at the time o'foxidation, by the mass ratio of the oxidizing agent and the-material treated at the oxidation zone, and by thetime allowed for the oxidation to take place. The total effect of these facto'rsupon theproperties of the product is so pronounced, that the accurate control of the process is one-of the mostimportant requirements of an asphalt-blowing plant. It is an object of this invention to provide a process for manufacturing blown asphalt which can be easily adapted to the requirements of the heatercontai ning coil i.

It may be desirable in some cases the air-blown product through an overflow pipe various feeds or different specifications of'the finished product.

readily be understood from the following description illustrated by the attached drawing.

to In carrying out this invention in practice, a

"pipe through a spraying nozzle.

the hot material and'the air is discharged in a It is another object of this invention to'provide petroleum residue, produced by distillation, or cracking, or chemical treatment, or a coal tar, or any other suitable carbonaceous material can beused as charging stock. The material is continuously charged from a source not shown to a 5 heating coil I, wherein the temperature of the material is raised to a suitable point, not exceeding cracking temperature, and preferably within the limits of 460550 F. The raw material may be preheated before it reaches heater I by heat 10 exchange wlthhot media, such as the products leaving stills d and I2. fIhe heated material is conducted through a pipe 2 to a perforated coil 3 positioned near the bottom of a blowing still i;

I found it advantageous to have coil 3 perforated 16 at the boottm instead of at the top, as sediment carried by the liquid material is readily removed from the coil through the perforations, no sediment is allowed to settle and plug the perforations from outside, and greater stirring effect in still 5 2g a suitable pressure through a pipe 5; although other chemically active gases or vapors can be used at this point, air is most commonly em- 2 ployed, and for the purpose of illustration, its use is described in this specification. l

Athoroughmixing of air and liquid material takes place inpipe 2 and coil 8; the mixing occurring in the pipe 2 can be intensified, if desired, 39 by introducing the air into the oil stream'in said- The mixture of finely divided state fromthe coil 3 into still a wherein a suitable level of liquid is maintained 35 bymeans of overflow pipes 5', having a'commonheader 6. At the temperatureof thestill 4, the

light components of the treated material together withunc'onsumed' gases separate from the'liquid and arerenroved'throughpipe 1 to condenser 8 40 and to storage, not shown. The remaining airblown residue is continually withdrawn, preferably near the surface of the pool in the still I, and forced by apumpQ through a heating coil Ill, positioned either in a separate heatenorin to withdraw 5" or pipe connection 21'whi1e maintaining the liquid level'as indicated on the drawing or the w level may be lowered. -Also the air-blown material from still 4 may be removed directly to storage through pipe 22 and heat exchanger 23, water or other fluid, such as incomingfeed, be-

ing used to extract heat in the heat exchanger;

or it may be drained through either line 2'! or 28.

The liquid material withdrawnfrom still 4 usually contains a certain amount of dispersed gas, and I found it of considerable advantage to have this entrained gas separated from the air-blown material before passing the gas-free liquid to the pump 9 and heating coil ID. A gas separator 30 is used to separate the gas from the liquid; this gas separator 30 is positioned between the header 6 and pump 9 and is provided with a gas vent 3| and liquid trap 32. The liquid trap, or separator, can be of any well known and suitable construction. A by-pass 33 serves to convey the air-blown material, when the separation of gas from the liquid is not deemed desirable, such as in the case of running. this material directly to storage.

From the coil l0 the air-blown asphalt is passed on through line H and discharged into an evaporator |2 provided with rectifying means [3.

Steam is injected into the evaporator I2 through a coil I5, preferably below the liquid level l4, which level is maintained at the desired height by liquid level controller l6. In the evaporator i2 a thorough contact is obtained between steam and the material being treated, and further separation of the more volatile components from the treated material is efiected. The vapors are conducted out of the evaporator through pipe ll, condenser, l8, and water separator l9, and the substantially water-free condensate is pumped to storage not shown. The rectified steamed material is continuallyl'removed from the bottom of the evaporator lZ/through a pipe 20, cooled in a heat exchangerZl, water or other fluid, such as incoming feed, being used to cool the material in the heat exchanger, and run to storage. A portion of the rectified asphalt may be recirculated through the evaporator l2 by means of pump-34 and a pipe connection 35, or it may be returned to the heating coil l by means of a pipe connection 36. Coil Ill may be wholly or 4 partially by-passed through line 26.

As a modification of the steam treatment of air-blown asphalt, I have sometimes found it of liquids and vapors.

Difllculties frequently encountered in the manufacture of blown asphaltic materials reside in the control of the temperature of oxidation to which the material undergoing treatmentis-subjected, and it is one of the objects of this invention to improve the method of this control.

One of the features of this process is the pre: ferred method of introducing the air into the system after. the heating coil but before the still. It has beenknown in the art to inject air directly into the still, or into the heating coil, or into the incoming charge before it enters the heating coil. Either of these methods has been practiced for some time with varying, degree of success. Certain unavoidable difliculties have been found, however, to accompany these methods. The injection of air before or into the heating coil tends-to cause undesirable carbonization of the material undergoing treatment, due, perhaps,

. to relatively high concentration of air at the injecting air before or into the heating coil are usually much higher than those employed in the present method.

Referring now to the method of injecting the air directly into the still, dimculties of other character have been encountered. When a relaquantity of undesirable distillate was producedwhen using the former method, and the uniformity of the air-blown residual material was difficult to maintain. My ,preferred method avoids the difliculties of both systems.

As has been described hereinbefore, the reacting mixture is, in this process, introduced into the still 4. To control the reactions taking place in this still, provisions are made:

(1) to regulate the temperature of the heated material leaving the heating coil I,

' (2) to regulate the gas flow in line 5,

(3) to regulate the time of contact between the oxidizing gas and liquid asphalt, and

(4) to regulate the composition of the material being treated:

Whileprovisions (1) and (2) may be carried out in any conventional manner, it is the purpose of this invention to control the time of contact between the oxidizing gas and the liquid material by maintaining a suitable level of liquid in the still 4. Preferably, this still 4 is a vertical cylindrically shaped chamber provided with means for continuously introducing the reacting substances and withdrawing the resulting products. The use of such a still has been-found much more advantageous than the use of the conventional horizontal chambers on account of the greater range available for varying the depth of liquid in such vertical still. Almost any desired degree of exhaustion of the active gas can be obtained.

by varying the liquid level, thus materially reducing the gas consumption.

It should be noted in this connection, that the vapor space in the still 4, contains, besides more volatile components of the asphaltic material, the residual gas substantially comprising only the inert portion of the gas injected through 5; it is readily seen, therefore, that the conditions prevailing in the still 4 are such that the lighter components of the asphaltic material are exposed only tothe action of substantially non-oxiding atmosphere, thus minimizing the carbonization of the material in the still 4.

It should be noted, furthermore, that the perforated coil 3 is continually and completely subly' viscous, sometimes solid, deposit of heavy material on said coil, whichnormally occurs when the coil is positioned at the topof the still and surrounded by air.

Due to the exothermic character of the oxidation reactions taking place in the still 4, the temperature of the liquid material is further raised, after being heated in coil I. It has been found, that in order to avoid excessive carbonization of the treated material the temperature in the still 4 should preferably not exceed 550 F. In order to control this phase of the process, a portion of the air-blown material may be continually recirculated. by means of pipe connection 25, so that the raw material is somewhat diluted before being subjected to oxidation, and the heat of reaction petigidmit of reacting mass is thereby suitably regula In certain cases it may be advisable,to carry out the oxidation reaction at a somewhat diminished rate. Although it may be possible to realize this by regulating the rates of liquid and air flows through coil I and pipe 5, as well as by recirculation of the air-blown asphalt through line 25, and/or by a proper adjustment of the liquid level in still t, it is preferred to provide an additional means for this purpose; viz. recirculation of a portion of the air-blown material from the still 4 to the coil i by means of a pipe 29. The raw material is diluted in this case prior to being heated, and the temperature and thereby the rate of oxidation in the still 6 is accordingly reduced.

While the different properties of the air-blown material can be varied within rather wide limits by the process steps described hereinbefore, often it is found dimcult to obtain the desired product and to maintain the normal rate of production at the same time. It has been found, that, by incorporating in this process a step wherein the airblown asphalt is further heated and steam treated the range of variation of the properties of the finished asphalt is considerably expanded, the

, quality of the product'improved, and a greater throughput realized. As has been described, the heating coil Ill is used to raise the temperature of the air-blown asphalt; the temperature of the heated material after coil iii preferably should not exceed 600 R, which in the absence of the chemically'ac'tive gas at this stage of the treatment is a safe limit, below which extensive coking does not occur. The advantages of having the steam still directly connected to the blowing still reside in the manner in which the composition of the feed in pipe H is controlled; this control is carried out by means of pipeconnections 26 and 2 whereby oxidized, or unoxidized, material may readily be introduced into line i l to properly a'djust the characteristics of the steam-rectified asphalt. Further continuous recirculation of a portion of the steamed asphalt through the steam still by means of line 35 has a marked efiect upon the ease with which various combinations of melting point, penetration and ductility of the finished product can be obtained.

It should be noted that although the use of coil.

ing coil, as under certain conditions of operation I found it desirable to introduce the untreated material after the coil i in line 2 before the still i through line 88, maintaining at the same time the recirculation of either air-blown asphalt by means of pump 9 and line 29, or steam-rectified asphalt through pump 34 and line 36, or both, through said coil i and/or air-blowing still by-pas'sing, if desired, a part of that asphalt through line in. Cr I may, first, rectify the untreated material with superheated steam in i2 conveying it there by means of lines 38, 2t, and H, and then oxidize the reduced residue in a continuous operation in 4 conveying it there from l2 by means of pump 34, line 56, coil l, and lines 39 and 2.

For the manufacture of most commercial products I operate my plant at around atmospheric pressure. However, for the making of special products it is sometimes advantageous to maintain either or both stills 4 and I2, either under pressure or-vacuum; the apparatus must of course be constructed so as to be able to withstand this change in conditions: special vacuum pumps may have to be added. Though usually not much vacuum or pressure is needed, I find it, under special circumstances, useful to employ considerable pressure or a high vacuum.

Having fully described the details of my process and the apparatus in which the process can be successfully carried out, the invention is further: defined in the appended claims.

I,claim as my invention:

1. A continuous process for treating asphaltic oil to produce oxidized asphalt comprising: heating said oil to an oxidizing temperature, commingling the heated oil with an oxygen-containing gas in a confined stream, maintaining a body of partly oxidized oil, discharging the said stream of the oxygen-containing gas and oil undergoing oxidation into said body, thereby causing further oxidation of the said body of oil, separating more volatile components of the oxidized oil together .with the residual gases of the air, withdrawing oxidized oil near the surface of said body of oil, and recirculating a portion of the-withdrawn oil through the heating step.

2. A continuous process'for treating an asphaltic oil to produce oxidized asphalt comprising: heating said oil to an oxidizing temperature, commingling the heated oil with an oxygen-containing gas in a confined stream, maintaining a body of partly oxidized oil, discharging said "stream of the oxygen-containing gas and oil undergoingoxidation into said body of oil, thereby effecting further oxidation of the body of oil, permitting the unconsumed air and more volatile components of the oxidized oil to separate from the oil, withdrawing a portion of the oxidized oil, further degasifying the same, and recirculating a portion of the substantially gas-free oxidized oil through the heating step.

3. A process for treating asphaltic oil comprising maintaining a body of partly oxidized oil, withdrawing a part of said body of oil, steam rectifying at least a portion of the withdrawn oil, heating the rectified oil to an oxidizing temperature in a confined stream, mixing said stream of heated oil with a stream of fresh oil, introducing an oxygen-containing gas into the combined oil stream; and discharging the resulting gas-oil stream still containing free oxygen into said body of partly oxidized oil, thereby further oxidizing said body of oil.

4. A process for treating asphaltic oil comprising maintaining a body of partly oxidized oil, withdrawing a part of said body of oil, steam rectifying a portion of the withdrawn oil, commingling the rectified oil with another portion of the withdrawn oxidized oil, heating the combined oil stream to an oxidizing temperature, mixing it with a stream of fresh oil, introducing an oxygen-containing gas into the resulting oil stream, and discharging the resulting gas-oil stream still containing free oxygen into said body of partly oxidized oil, thereby further oxidizing said body of oil.

5. A continuous process for treating asphaltic dized oil, discharging said stream into said body of oil, thereby further oxidizing said body of oil, withdrawing the oxidized oil and returning a portion thereof to the rectifying zone together with the fresh oil.

6. The process of claim 5, wherein a part of the withdrawn oxidized oil is mixed with the rectified oil and the mixture is heated to an oxidizing temperature.

7. A continuous process for treating asphaltic oil to produce oxidized asphalt, comprising: heating said oil to an oxidizing temperature, commingling the heated oil with an oxygen-containing gas in a confined stream, maintaining a body of partly oxidized oil, discharging the stream of oil and oxygen-containing gas into'said body of partly oxidized oil, thereby further oxidizing the same, simultaneously separating the oxidized oil from vapors and residual gases, withdrawing and re-heating at least a portion of the resulting substantially gas-free material, and steam-rectifying said re-heated portion.

8. A continuous process for treating asphaltic oil to produce oxidized asphalt, comprising: heating said oil to an oxidizing temperature, commingling the heated oil with an oxygen-containing gas in a confined stream, maintaining aibody of partly oxidized oil, discharging the stream of oil and oxygen-containing gas into said body of partly oxidized oil, thereby further oxidizing the same, simultaneously separating the oxidized oil from vapors and residual gases, withdrawing and steam-rectifying at least a portion of the resulting oxidized substantially gas-free material, commingling at' least a portion of the steamrectified liquid material with said withdrawn oxidized material, and steam-rectifying the resulting mixture.

9; A process of forming oxidized asphalt comprising: maintaining a heated bulk supply of oil in a chamber at an elevated temperature, continuously circulating substantially gas-free oil from the bulk supply to and through a heating coil and back to the bulk supply, continuously introducing an oxygen-containing gas into a confined stream of the circulating oil after the oil leaves the heating coil but before it enters said chamber, commingling said stream with the oil in said chamber, continuously permitting the residual air to separate from the oil in the chamber and pass out of the system, continuously withdrawing the resulting gas-free material, reheating it in a confined stream, and steam-rectifying said material.

10. A continuous process for treating asphaltic 10 oil to produce oxidized asphalt comprising heating a continuousstream of fresh asphaltic oil .in a heating coil in the absence of oxygen to an oxidizing temperature, commingling the heated oil while at said temperature with an oxygencontaining gas in a confined turbulent stream, maintaining a bodyof oxidized oil having a depth above the point of introduction of the commingled stream of oil and oxygen-containing gas effective for desired oxidation and discharging said stream of oxygen-containing gas and substantially unoxidized fresh oil into said body of oil, thereby further oxidizing said body of oil and simultaneously separating the oxidized oil while in said body from vapors and residual gases, continuously withdrawing at least a portion of the resulting substantially gas-free material oxidized to the desired extent and commingling it with the heated stream of fresh oil before it is discharged into said body of oil. 11. A continuous process for treating asphaltic oil.to produce oxidized asphalt comprising heating a continuous stream of fresh asphaltic oil in a heating coil in the absence of oxygen to an oxidizing temperature, commingling the heated -oil with an oxygen-containing gas in a confined turbulent stream, maintaining a body of oxidized oil having a depth above the point of introduction of the commingled stream of oil and oxygencontaining gas effective for desired oxidation and discharging said stream of oxygen-containing gas and substantially unoxidized fresh oil into, said body of oil, thereby further oxidizing said body, of oil and simultaneously separating the oxidized oil from vapors and residual gases, withdrawing at least a portion of the resulting substantially gas-free material oxidized to the desired extent and commingling it with the stream of fresh oil before it is subjected to heating.

ADOLF GUTZWILLER.

Images