US2279937A - Process of dewaxing crude and refined petroleum oils - Google Patents

Description

UM OILS April 1.4, 1942. T. J. BROWN PRocEss oF DEwAxING GRUDE AND REFINED PETROLE Filed May 8, 1940 Patented Apr. 14, 1942 PROCESS OF DEWAXIN G CRUDE AND REFINED PETROLEUM OILS Thomas J. Brown, Cohoes, N. Y.

Application May 8, 1940, Serial No. 334,083

13 Claims.

v This invention relates to a process of dewaxing crude and refined petroleum oils," such as Pennsylvania and other paraffin base motor oils, whereby the pour point of the oil is reduced. This application is a continuation in part of my prior application filed August 12, 1,935, Serial Number 35,877.

The primary object of the invention isto provide a process which will expedite and facilitate the dewaxing of oils without having to resortto the chilling or freezing operation now commonly employed to dewax oils.

A further object of the invention is to provide a process for renng lubricating oils which will produce an oil of superior quality than oils rened in accordance with present known processes.

A still further object is to provide a proce-ss for refining crude oil which will produce highly refined gasoline, kerosene, neutrals, heavy oils, bright stocks and the like, with a much lower Wax content than ordinarily found in these products when subjected to conventional refining processes, thus making it possible to use the socalled D and E stocks of oil without further re-y ning or processing.

Other objects and advantages of the invention will be apparent during the course of the following description.

The present methods of distilling crude petroleum oils, such as Pennsylvania and other parafn base oils, result in the recovered products, such as gasoline, kerosene, neutrals, heavy oils and bright stocks having an excessive amount of paraffin therein and in many instances this renders the products unsuitable for certain uses which makes it necessary to resort tothe well known chilling or freezing process to remove the excess paraffin from the products. This is particularly true with the so-called D and E stocks of oil recovered from the distilled crude oil.

I have discovered that by blending paracymene which is a wax solvent and not an antiwax solvent, with the crude petroleum oil, the products recovered from the crude oil as a result of the distilling process will have a much lower wax content than if the distillation was carried out without para-cymene being present in the crude oil. The crude oil containing the para-cymene is distilled in the same manner as ordinary rening and distillation of oils is conducted at the present time. .I have found that the adding of para-cymene to a paraiiin base crudeoil causes a settling of thewax, so that during the distillation process the gasoline, kerosene and .other light ends passing oi do not contain as much paramn, as would be found in these products if para-cymene was not used. As paracymene has a high boiling point it does not pass off with the light ends but remains admixed with the remaining oil. After the light ends have.

passed ofi, the remaining oil and para-cymene are then distilled to about 600 F. during which time the para-cymene by chemical action causes a precipitation of the wax in flocculent form from the oil. During the latter step the para-v cymene passes oli from the oil in a clear form and may be fully recovered and used again and again. The oil containing the wax in precipitated flocculent form is. then placed in a filter press or centrifuging machine and by mechanical means the oil is completely separated from the `precipitated wax. .The recovered oil will naturally have a lower pour point than the original oil.

The accompanying drawing shows diagrammatically an apparatus suitable for carrying out the process, although it is understood other apparatus will serve the same purpose. In the drawing, 5 indicates a still having an agitator 6 and burner 'I for heating the still to the desired temperatures. A storage tank 8 for the paracymene is connected by a pipe 9 to the side of the still and a storage tank I0 for the crude oil is connected by a pipe I I to the side of the'still, the pipes 9 and II having meters I2 interposed therein. An earth hopper I3 is connected to the side ofthe still by a pipe I4 for introducing an absorbent material such as fullers earth or Retrol when desired. The still is connected with a fractionating tower I5 by pipes I6 and II, the former extending from the side of the still to the side of the tower and the latter extending from the end of the still to the bottom of the tower. 'Ihe pipe I1 serves as a run down pipe while the pipe I6 conducts the oil vapors from the still to the tower. The vapors pass from the tower I5 through a pipe I8 to a cooler I9 which has branch pipes 2t, 2l, 22, and 23 leading to the gasoline, kerosene, recovered paracymene, and neutral and light ends storage tanks 24, 25, 26, and 21, respectively. The oil remaining in the still passes through the pipe 28 which has branches 29 and 30 leading to a centrifuge 3|, the passage of oil through the branches 29 and 3o being controlled by a valve 32. The branch 29 is employed when absorbent material is introduced in' the still and has a lter 33 interposed therein for filtering the absorbent mate- 'l rial from the oil. A pipe 34 leads from the centrifuge to a wax storage tank 35 and the nished oil passes from the bottom of the centrifuge through a pipe 36 to the storage tank 31.

The operation of the process using the above described apparatus is as follows:

The still is charged with the crude oil from the tank I0 and a suitable quantity of paracymene from the tank 8 is introduced into the still and mixed with they crude oil by agitation. In some instances a charge of absorbent material such as fullers earth is introduced through the hopper I3 into the still and admixed with the crude oil and para-cymene but theuseof an absorbent material in carrying out the process is not necessary and may be left out. The mixnot have a pour point as low as the oil derived by my process.

While in the foregoing I have described my process as employed in the refining of crude oils, it is obvious the process can also be employed in dewaxing oils which have been distilled in the usual manner from crude oil without` paracymene being present in the crude oil. As previously explained theseY oils have an excessive amount of parafn which at the present time can be removed by the usual chilling process which is expensive. By adding para-cymene to these Y refined oils and then distilling the same to about ture of para-cymene and crude oil, either with or without the absorbent materialyis then hea-ted to a temperature to distill off the gasoline,V

kerosene, and neutral and light ends which pass through the fractionating tower I5 and then to the cooler I9 from which they pass to their respective storage tanks 24, 25, and 21. After the light ends have passed olf the temperature of the still is increased to about 600 F. at which temperature the para-Cymene passes o through the fractionating tower, cooler and tothe recovery tank 28. After the light ends and paracymene have been'distilled off the oil in the still is passed to the centrifuge 3| either through the direct passage 301i the oil contains no absorbent material or through the passage 29 and filter 33 if the oil contains an absorbent material. In the centrifuge the wax is separated from the oil and passage to the storage tank 35 while the dewaxed oil passes to the storage tank 31. y

When the process is employed to dewax refined oils the distilling steps of the light ends is'eliminated and consequently certain parts of the apparatus employed may be disepnsed with. The refined oil together with the para-cymene and either with or without the absorbent material are introduced into the still 5 and heated toa temperature vsufficient to cause the para-cymene to be distilled off and then the oil is passed to the centrifuge 3l either direct or through a filter dependent on the presence or absence of the absorbent material. The centrifuge separates the wax from the oil and the kwax is passedto a storage tank 35 while the dewaxed or finished oil passes to a storage tank 31.

For example, I have conducted a test in which eight ounces of para-cymene was blended with sixteen ounces of Pennsylvania crude oil. 'Ihe oil was distilled in the usual manner until the light ends had passed off and then the mixture of para-cymene and heavy oils was distilled up to 600 F. at which point all the para-Cymene had passed off. The oil was separated from the wax in a lter press and an oil product of the following specifications was obtained.

Gravity 28.3 Flash 480 Fire 520 Vis. 210 sec. Saybolt 130 Pour below zero-- Minus 5 well known chilling methods, etc., to produce a bright stock and the resultant bright stock would 600 F., I `find that the para-cymene causes the wax to be precipitated in locculent form from the oil. The oil containing the precipitated wax is then placed in a lter press or centrifuge machine and by mechanical means the oil is separated from the wax. If the lter press is employed to separate the oil from the wax particles, the oil is kept at a temperature of about 400 F. but when the centrifuge machine is employed the oil need only be kept at room temperature. `The, para-cymene need only remain in the oil for a length of time necessary to carry out the distilling operation and after Vthe paracymene distills off, the oil may be separated from the wax at anytime.

`As an example, I have conducted a test in which eight ounces of para-cymene was blended with an equal quantity of Pure Pennsylvania Bright Stock which had been refined in the usual manner and the mixture was distilled up to 620 1F. at which point all the para-cymene was distilled off. The oil containing the -precipitated wax particles was then placed in a filter press and the oil separated from thewax. The following table shows the results:

Saybolt. 5 below zero.

sec. Saybolt- Pour point 20 above zero.

Another test showed that oil known as Warren Er Stock after being treated in accordance with my process showed a drop in the pour point of the oil from .72 above zero to a point below zero. Thus, it is seen that from tests conducted the degree to which the pour point of the oil is lowered varies with the different grades of oil.

In addition to dewaxing the oil and lowering its pour point I also find that oil recovered or treated by my process has a much higher resistance to sludge and oxidation than regularly dewaxed oils.

If desired an absorbent material such as fullers earth or Retrol may be added to the oil when carrying out my process, as I have found such absorbent material will absorb the wax particles when separated out of the oil and also will assist in clarifying the oil. However, the process is not dependent upon the use of such absorbent material and can be successfully conducted Without the same.

Another result of the use of my process when bright stocks or heavy oils are recovered is that the addition of Paraflow disclosed in Patent'l No. 1,815,022 to the recovered oil will effectively reduce the pour point of the oil to a still lower not affected by the addition of Paraflow andthe pour point of such oils remains the same.

This process is not only valuable in producing a low pour point heavy oil or bright stock but is also valuable in removing the wax from various types of crude oils and has a desirable effect upon other products recovered from the crude oils. As an example; a crude .oil containing approximately 80% asphalt and 20% parain when distilled in the usual manner produces gasoline and other products that contain undesirable parain. By adding paracymene with this type crude oil and distilling in accordance with my process it is found that much, if not all of this wax is formed as a. sludge in the crude oil and during distillation does not pass from the crude with the light ends. This results in a much better finished product. Thus, it is seen my process has advantages in distilling all types oi crude oils containing' any amount of paraii'in. n

This invention is not to be limited by any specific example which may have been given for the purpose of illustration but only by the following claims.

Having thus described my invention, I claim:

1. The method of dewaxing petroleum oils which consists in mixing the oil with paracymene and an earthy wax absorbent medium, subjecting the mixture to a high temperature to cause the Wax to separate out of the oil and then separating the Wax and absorbent medium from the oil.

. 2. The method of lowering the pour point of bright stock lubricating oil containing wax consisting in mixing with the oil para-cymene and an absorbent material, distilling the mixture to cause the Wax tolseparate out of the oil, separating the Wax and absorbent material from the oil, and then adding an aluminum chloride condensation product of naphthalene and chlorinatedv parain wax to the oil.

3. The method of dewaxing petroleum oil which comprises mixing para-cymene with the oil, distilling the mixture at, a temperature to cause the wax to separate out of the oil and the para-cymene to pass off, and then separating the oil from the wax.

4. The method of distilling crude petroleum oil which comprises mixing para-cymene with the crude oil, heating the mixture to a temperature to cause the wax to separate out of the oil and the light ends to pass oi, raising the temperature to cause the para-cymene to pass off, and then separating the wax from the residual oil by mechanical means.

5. The method of distilling crude petroleum oil which comprises mixing para-cymene and an absorbent material with the oil, distilling the mixture to a temperature to cause the wax to separate out of the oil and the light ends to pass 01T, raising the temperature to cause the para-cymene to pass oi and then separating the wax andabsorbent material from the residual oil by mechanical means.

6. The method of dewaxing petroleum oil which comprises mixing para-cymene with the oil, heating the mixture at a temperature to effect fluocculent precipitation of the Wax from the oil, and then separating the oil from the wax.

7. The method of dewaxing crude petroleum oil which comprises mixing para-cymene with the crude oil, heating the mixture to cause the light ends to distill oi, raising the temperature to eiect a iiuocculent precipitation of the wax from the oil, then separating the Wax from the oil by mechanical means.

8. The method of producing bright stock and heavy'oils having a low pour point comprising mixing para-cymene with the crude oil and heating the mixture to distill oi the light ends and cause the Wax to separate out of the oil, and then separating the oil from the wax.

9. The method of producing bright stock and heavy oils having a low pour point comprising mixing para-cymene with the crude oil and heating the mixture to distill oi the light ends and cause the wax to separate out of the oil, then separating the oil from the wax, and then adding an aluminum chloride condensation product of naphthalene and chlorinated parain wax to the residual oil.

l0. The method of lowering the pour point of bright stock lubricating oil containing Wax comprising mixing para-cymehe with the oil, distilling the mixture to cause the wax to separate out of the oil, separating the wax from the oil, and then adding an aluminum chloride condensation product of naphthalene and chlorinated paraiiin Wax to the oil.

11. The method of distilling crude petroleum oil which comprises mixing para-cymene with the crude oil, heating the mixture to a temperature to cause occulent precipitation of the wax from the oil and the light ends to pass oi.

12. 'I'he method of distilling crude petroleum oil which comprises mixing para-cymene with the crude oil, heating the mixture to a temperature to cause the Wax to separate out of the oil and the light ends to pass ori.

13. The method of distilling crude petroleum oil which comprises mixing para-cymene and an absorbent material with the oil, heating the mixture to a temperature to cause the wax to separate out of the oil and the light ends to pass oil?.

THOMAS J. BROWN.

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