US2046081A - Process for manufacturing asphaltic products - Google Patents

Description

June 30, 1936. c, P. MCNEH. 2,046,081

PROCESS FOR MANUFACTURING ASPHALTIC PRODUCTS Filed March 23, 1934 INVENTOR Claude PMG/Vezi BY 5M1 ATTORNEY ?atented June 30, "W36 attach PROCESS FOR MANUFAC'IIMING ASPHALTIC PEODUCTS ration of Indiana Application March 23, 1934, Serial No. 717,058

16 Claims. (Gi. ltd- 14) This invention relates to the manufacture of asphaltic products, and particularly to the manufacture of asphaltic products by oxidation.

It is an object of my invention to provide an improved process for the manufacture of asphaltic products. Another object is to provide a process for the manufacture-of an asphaltic product having a consistency which is substantially unaffected by heating to high temperatures, for instance, to temperatures up to and including those at which substantial cracking commences to occur. A further object is to provide a process for the manufacture of asphaltic products by blowing with air or other oxygen-containing gas in which the initial oxidation is conducted at a low temperature to secure maximum safety and in which further process steps are used to secure a final product having a consistency which is unaffected by heating to high temperatures. Other and more detailed objects of my invention will appear as the description thereof proceeds.

It is known to produce asphalt and lighter asphaltic products such as road oils from residues from asphalt-bearing petroleum oils by'blowing with air or other oxygen-containing gas. The effect of this blowing operation is to harden the product or, in other words, decrease its penetration. Penetration is measured by the American Society for Testing Materials Standard Method of Test for Penetration of Bituminous Materials (Designations D 5-25) and may be defined as consistency expressed in terms of the distance in hundredths of a centimeter which a standard needle will'penetrate a sample to be tested when acting under a load of 100 grams for a time of 5 seconds at 77 F. or other desired temperature.

I find that the blowing operation can best be conducted at temperatures within the approximate range 300 F. to 425 F. and preferably within the approximate range 325 F. to 400 F. Temperatures lower than the minima indicated can be used but the reaction tends to become too slow for practical operation and more trouble is encountered from foaming. Temperatures somewhat above the maxima indicated can also be used, but at the cost of considerably increased fire hazard. which can be overcome only by the use of costly equipment and the expensive expedient of providing an excess of steam in the vapor space. This blowing can be carried on for a length of time which will depend very greatly upon the nature of the stock charged, the temperature used, the intimacy of contact between the stock and the oxidizing medium, and the results desired. The time may range from less than an below cracldng temperatures.

hour up to several days, or even weeks, the usual practice being to continue the blowing until the desired penetration is achieved. Thus, for instance, a penetration of from 75 to 125 at 77 F. may be suitable,

The product resulting form. this one step oxidation is, however, extremely unsatisfactory in that the penetration is not stable but tends to increase very markedly as the product is heated to an elevated temperature. Thus, for instance, if the product is used in the manufacture of a so-ealled cut-back asphalt, in which it is blended with a light petroleum diluent for cold application in road making, etc., and the cut-back asphalt thus produced is subjected to the ordinary test in which it is heated to a temperature of 680 F. and

the penetration of the residue then determined, it will be found that the penetration has increased as much as 75, 100 or even 150 units and has therefore completely failed to meet the usual specifications. This phenomenon, peculiarly enough, seems to occur even when the residue used to produce the asphalt is itself produced by pipe stilling and has been subjected to temperatures as high as 800 F. I am completely unable to explain this phenomenon, but I find it to be the usual one in the manufacture of asphaltic products from uncracked asphalt-bearing crude oils and'particularly from Mid-Continent and Winkler County, Texas crude oils. The phenomenon does not occur in the manufacture of asphaltic products from the s'o-called pressure tar produced by cracking processes.

I find that I can overcome this lack of stability by subjecting the oxidized asphaltic product to a prolonged soaking at a temperature within the range 425 F. to 575 F. or preferably within the range 450 F. to 550 F., and then re-oxidizing the material to the desired penetration. Temperatures lower than the minima indicated can be used but the time required is excessively long. The maxima indicated are the approximate points at which localized cracking oommences to occur due to local overheating. If 10- cal overheating is avoided somewhat higher temperatures can be used. The efiect of the soaking step is to soften the asphaltic product very markedly, or in other words to increase its penetration. This increase may be as much as 50, '75 or even 100 units. However, after reoxidation to the original penetration or to any other desired penetration, the consistency remains constant and is not afiected by further heating to temperatures In fact, the material produced by the soaking step without reoxidation has a stable consistency and its penetration is not afiectecl by further heating. The only purpose of the reoxidation is to harden the product and bring it back to the usually desired specifications.

The temperature of the reoxidation step can be within the range hereinbefore specified for the soaking step, since the fire hazard existing in the original oxidation step has been eliminated by the removal of volatile materials in the first oxidation step and in the soaking step. However, it is possible to reoxidize at any temperature between the minima specified for the first oxidation step and the maxima specified for the soaking step.

The time required in the oxidation steps varies throughout a tremendous range depending on the nature of the material being treated, the desired specifications, and more particularly the temperatures involved and the intimacy of contact between the product undergoing treatment and the oxidizing medium. Thus, for instance, if efficient mechanical agitation is used to secure intimate contact, oxidation can be accomplished in a few minutes. Similarly, if countercurrent oxidation towers are used the oxidizing time will be relatively short. If, on the other hand, stills or tanks are used in the oxidation steps, the necessary time of contact will be considerably longer and will depend on the size of the vessel, the air distribution, the temperature of the operation. etc.v In general, the time occupied by the soaking step should be rather longer than that oc-' cupied by either of the oxidation steps, and should generally notbe less than 2 or 3 hours, and preferably not less than 24 hours.

As previously indicated, various types of equipment can be used in carrying out my process. In general, I prefer a continuous process utilizing countercurrent towers or stills, but my process can satisfactorily be carried out in a batch process as indicated by the following examples:

- Example 1 Penetra- 1 Temper- Time of soaking ature oi i ggg gggggi soaking test 0 hours 400 F 94 188 4 hours. 460 F 154 14 hours 500 F 23 hours 500 F 135 162 31 hours 500 F 134 169 39 hours 500 F 135 149 47 hours. 500 F 150 171 62 hours l 500 F 163 71 hours 500 F 160 162 The third column gives the penetration at 77 F. of samples withdrawn at various times during the soaking step and the fourth column gives the penetration at 77 F. of the residues obtained by incorporating the corresponding samples in a cut-back asphalt and distilling to 680 F. It will be noted that as soaking continued the two penerations become practically identical.

The soaked material having a penetration 01.

160 was then reoxidized by blowing at about 410 F. to a penetration of 91. The final product on being subjected to heating to 680 F. showed a penetration of 102.

Example 2 Penetra- Penetration (77 Tem- Time tion F.) alter Imam (77 F) cut-back 0 hours 400 F 08 166 6 hours 380 F 96 144 10 hours 400 F 94 145 25 hours 500 F. 115 135 33 hours 500 F. 124 135 41 hou1s 500 F. 122 148 49 hours 500 F. 125 134 57 hours 500 F. 128 133 65 hours 500 F. 1% 134 73 hours" 500 F. 137 135 81 hours..- 500 F. 113 120 85 hours..- 500 F. 107 114 90 hours 500 F. ,97 100 Blowing stopped. Blowing resumed.

It will be noticed that whereas at the end of the first oxidation period the asphalt was highly unstable and markedly affected by heating to 680 F., after soaking it became very stable and maintained this stability on reoxidation to a penetration of 97.

Reference will now be had to the accompanying drawing which is a semi-diagrammatic layout of apparatus for the carrying out of my process, preferably in continuous fashion.

The three steps of the process are preferably carried out in stills A, B and C respectively. The charging stock, which may suitably be a petroleum oil residuum having a viscosity of from 50 to 600 seconds Furol at 210 F., is introduced into still A by means of pump I, through line 2, and is there contacted with air introduced by means of compressor 3 through line 4, valve 5 and spray 6. The charge is oxidized in tank A to the desired consistency. The air, together with any vapors from the charge, pass overhead through valve 1 and line 8 to blow-down 9 wherein they are contacted with water from spray l0 and pass therewith to the sewer or to a separator through line H. The gases are vented through valve l2. The oxidized material is transferred from still A by means of valve l3 and line H to still B wherein its temperature is raised, as has been previously discussed. Still B may be heated by means of fire box I5 or otherwise. Vapors pass overhead through valve I6 to blow-down 9. It will be noted that still B is considerably larger than either still A or still C. This is due to the fact that the soaking time is usually several times the oxidation time and therefore when the process is operated continuously it is necessary to provide more soaking'capacity than oxidized capacity. The material from still B passes therefrom by gravity or otherwise through valve l1 and line ill to still C wherein it is again oxidized by means of air or other oxygen-containing gas introduced by means of compressor 3, line i 9, valve 20 and spray 2|. Gases are vented to the atmosphere through valve 22 or may pass to blowdown 9. After oxidation in still 6 to the desired'penetration the finished asphaltic product is withdrawn through valve 23.

Although I prefer to operate in three separate and distinct stages, as shown and described, it is possible to omit still C altogether and conduct the soaking and final oxidation simultaneously in still B by introducing air or other oxygen-containing gas therein by means of compressor 3, line 24, valve 25 and spray 25.

It is to be understood that my invention is particularly adapted to the manufacture of asphalt, especially paving asphalt. It can nevertheless be used on other asphaltic products such as road oils, the soaking period having a stabilizing efiect on the consistency or viscosity oi the oxidized road oil similar to its stabilizing efiect on the penetration of oxidized asphalt.

While I have described my invention in connection with certain specific embodiments thereof, I do not mean to be limited thereby except to my invention as defined in the appended claims.

I claim:

1. Process for producing an asphalt having a consistency substantially unaffected by heating to any temperature below a cracking temperature, comprising contacting a residue from an asphaltbearing crude oil with an oxygen-containing gas at an oxidizing temperature substantially within the range 300 F. to 425 F. and then soaking the oxidized stock without intimate contact with oxy- 7 gen-containing gas for at least about 24 hours at a temperature substantially higher than said oxidizing temperature but substantially below a cracking temperature.

2. Process for producing an asphalt having a consistency substantially unaffected by heating to temperatures below cracking temperatures, comprising contacting a residue from an asphaltbearing crude oil with an oxygen-containing gas at an oxidizing temperature substantially within the range of 300 F. to 425 F. and then soaking the oxidized stock without intimate contact with oxygen-containing gas at a temperature substantially higher than said oxidizing temperature and substantially within the range of 425 F. to 575 F. and then reoxidizing the soaked material by contacting it with an oxygen-containing gas at a temperature substantially within the range of 300 F. to 575 F.

3. Process for producing an asphalt having a consistency substantially unaffected by heating to temperatures up to at least 680 F., comprising contacting a residue from an asphalt-bearing crude oil selected from the group consisting of the Mid-Continent and Winkler County, Texas crude oils with an oxygen-containing gas at an oxidizing temperature substantially within the range 300 F. to 425 F. and then soaking the oxidized stock for at least 24 hours at a temperature in excess of 425 F. but substantially below cracking temperatures.

4. Process for producing a paving asphalt having a consistency substantially unaffected by heating to temperatures below cracking temperatures, comprising contacting a residue from an asphalt-bearing crude oil with an oxygen-containing gas at an oxidizing temperature until said stock reaches the desired penetration, soaking the oxidized stock at a temperature substantially higher than said oxidizing temperature but substantially below cracking temperatures for at least two hours and then reoxidizing the soaked stock at an oxidizing temperature to secure a product having a penetration approximately the same as the penetration of said firstmentioned oxidized stock.

5. Process for producing an asphaltic product having a consistency substantially unaiiected by heating to high temperatures comprising oxidizing a petroleum oil asphaltic stock at an oxidizing temperature substantially within the range 300 F. to 425 F and then soaking the oxidized stock without intimate contact with the oxidizing agent for at least about 24 hours at a temperature substantially higher than said oxidizing temperature but substantially below a cracking temperature.

6. Process for producing an asphalt having a consistency substantially unaffected by heating to any temperature below a cracking temperature, comprising contacting a residue from an asphaltbearing crude oil with an oxygen-containing gas at an oxidizing temperature substantially within the range 325 F. to 400 F. and then soaking the oxidized stock without intimate contact with oxygen-containing gas for at least about 24 hours at a temperature substantially higher than said oxidizing temperature but substantially below a cracking temperature.

7. Process for producing an asphalt having a consistency substantially unaffected by heating to any temperature below a cracking temperature comprising contacting a residue from an asphaltbearing crude oil with an oxygen-containing gas at an oxidizing temperature substantially within the range 300 F. to 425 F. and then soaking the oxidized stock without intimate contact with oxygen-containing gas for at least about 24 hours at a temperature substantially within the range 425 F. to 575 F.

8. Process for producing an asphalt having a consistency substantially unaffected by heating to any temperature below a cracking temperature comprising contacting a residue from an asphaltbearing crude oil with an oxygen-containing gas at an oxidizing temperature substantially within the range 325 F. to 400 F. and then soaking the oxidized stock without intimate contact with oxygen-containing gas for at least about 24 hours at a temperature substantially within the range 425 F. to 575 F.

9. Process for producing an asphalt having a consistency substantially unaffected by heating to any temperature below a cracking temperature comprising contacting a residue from an asphaltbearing crude oil with an oxygen-containing gas at an oxidizing temperature substantially within the range 325 F. to 400 F. and then soaking the oxidized stock without intimate contact with oxygen-containing gas for at least about 24 hours at a temperature substantially within the range 450 F. to 550 F.

- 10. Process for producing an asphalt having a consistency unaflected by heating to temperatures below cracking temperatures, comprising contacting a residue from an asphalt-bearing crude oil with an oxygen-containing gas at an oxidizing temperature substantially within the range 325 F. to 400 F. and then soaking the oxidized stock in the absence of oxygen-containing gas at a temperature substantially higher than said oxidizing temperature and substantially within the range 425 F. to 575 F. and then reoxidizing the soaked material by contacting it with an oxygen-containing gas at a temperature substantially within the range 300 F. to 575 F.

11. Process for producing an asphalt having a consistency unaffected by heating to temperatures below cracking temperatures, comprising contact- 450 F. to 550 F. and then reoxidizing the soaked material by contacting it with an oxygen-containing gas at a temperature substantially within the range 300 F. to 575 F.

12. Process for producing an asphalt having a consistency unaffected by heating to temperatures below cracking temperatures, comprising contacting a residue from an asphalt-bearing crude oil with an oxygen=containing gas at an oxidizing temperature substantially within the range 325 F. to 400 F. and. then soaking the oxidized stock in the absence of oxygen-containing gas at a temperature substantially higher than said oxidizing temperature and substantially within the range -i F. to 550 F. and then reoxidizing the soaked material by contacting it with an oxygen-containing gas at a temperatm'e substantially within the range 450 F. to 550 F.

13. A process for producing asphalt which comprises commingling oil with oxygen containing gas at an elevated oxidizing temperature suficient to oxidize at least the greater part of said oil into asphalt, discontinuing the supply of oxygen containing gas and then improving the characteristics of at least some of the oxidation products. in the oxidized asphalt by soaking the same, without intimate contact with an added gas, at a temperature substantially higher than i hours.

14. A process for producing asphalt which comprises commingling oil with oxygen-containing gas at an elevated oxidizing temperature suificient to oxidize at least the greater part of said oil into asphalt, discontinuing the supply of 5 oxygen-containing gas and then improving the characteristics of at least some of the oxidation products in the oxidized asphalt by soaking the 7 same, without intimate contact with an added oxidizing gas, for at least about 24 hours at a 0 temperature substantiaily higher than said oxidizing temperature below a cracking temperature for a period of time suflicient to accomplish said improvement.

15. A process for producing asphalt which com- 15 prises commingiing oil with oxygen-containing gas at an elevated oxidizing temperature sufficient to oxidize at least the greater part of said 011 into asphalt, discontinuing the supply of oxygen-containing gas and then improving the characteristics of at least some of the oxidation products in the oxidized asphalt by soaking the same, without intimate contact with an added gas, at a tempera ure substantially higher than said oxidizing. temperature but below a cracking 25 temperature for a period of time suflicie .t to accomplish said improvement.

16. Process for producing an asphalt having a consistency substantially unaffected by'heating to temperatures up to at least 680 F., comprising 30 contacting a residue from an asphalt-bearing crude oil with an oxygen-containing gas at an oxidizing temperature substantially within the range 300 F. to 425 F. and then soaking the oxidized stock for at least 24 hours at a tempera- 3:

ture' in excess of 425 F. but substantially below

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