US2047985A - Process for controlling the decolorizing of hydrocarbon oils - Google Patents

Description

H. M. WEIR 2,047,985

PROCESS FOR CONTROLLNG THE DECOLORIZING OF HYDROCARBON OILS July 2l, 1936.

Filed June 10, 1931 Mm human. Q53 wzmi u u Q @gw Ywsbmw MEW w Lu All* FIN nwtwk. n".

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Patented July 2l, 1936 .UNITED STATES PATENTy OFFICE PROCESS FOB CONTROLLING THE DECOJ- QRIZING F HYDBOCARBON OILS Horace M. Weir, Philadelphia, Pa., assignor to The Atlantic Benning Company, Philadelphia, Pa., a corporation of Pennsylvania Application `lune 10, 1931, Serial No. 543,482 2 claims. (oi. 19e-4o) -jected -to such treatment. 'Ihe method and means whereby the invention may be carried out are hereinafter disclosed. The disclosure will suggest'various applications and modifications of the process and apparatus. to those skilled in the art, and these are considered within the scope of myinvention.

While the invention is particularly adapted to ythe treatment of mineral oils generally, for convenience, it will be explained in connection with theacid treatment of lubricating stocks. It is to be understood, however, that my invention may be applied when decolorization of the oil is effected by means of other decolorlzing agents, as for example, fullers earth.

In view of the fact that mineral lubricating oils have 'been chosen as' an example of liquid to be ,their 4then impure condition, but must be subjected to a further refining treatment which includes decolorizng.

' While many methods may be employed for decolorizing these oils, a common method is to treat them with sulfuric acid. It is only desired, however, to reduce lthe color to a certain degree, and any further reduction of color is both undesirable and a waste of decolorizing agent. Therefore, it is desirable to control the amountvof acid added as closely as possible toa particular amount. It is common practice to leave the addition of acid in charge of an operator whol judges by eye the color of the treated oi1,and either increases or decreasesthe amount of acid in accordance with such judgment. This method has many sh0rtcomings. as may readily be sensed. The color of l hours after the acid has been added, and conseoil produced will probably be as varied as the number of operators. Further, the oil will not be uniformly treated, sometimes being over-acidiiied, and other times being under-acidied. This comes from the fact that the operator may 5 neglect controlling the acid for a period of time until he notices that the oil has, for example, been under-treated and is therefore too dark. Upon this notice he will most likely proceed to increase the ilow of acid to make an oil of lighter color than the desired color of finished product, so that the blend of the two will result in the desired color. This requires much more acid than would be required if all of the oil had been uniformly treated, and further, it means that the colorimparting compounds which remain in the underacidied portion which forms a part of'the iinal oil product, .are lessv desirable than the colorimparting compounds resulting from a'f'correctly acidied or correctly treat'ed oil. 20

The eliminate in a measure the shortcomings of this process, and also to serve other desirable purposes, I have provided as one specific aspect of my invention a processv and apparatus for the continuous recording of the color o f the oil both before and after acid treatment. The color of the oil before the acid treatment may be measured and recorded by passing a part of the oil stream between a source of light and a light sensitive body, for example, a photo-electric cell. Currentv through the photo-electric cell is made to operate an indicating and recording device. By these, together with additional steps, the color of the oil after acid treatment is similarly recorded.

In recording the color of the oil after acid treatment, it is not sufllcient to merely measure the color of the oil after it has gone through the customary process. In such process the oil does not reach a nished condition until about 12 orv14 quently, measurement of the color at such time would not be useful in .controlling the rate of addition of acid. In accordance with the need for quicklydetermining whether or not the correct amount of acid is being added, I have provided a process for q'uickly bringing a sample stream of the treated oil into suitable condition for color measurement, and automatically (by recording the color of the passing stream of oil) determining the insufliciency or the excess oi' the acid treatment, as the case may be,

The single figure inthe drawing represents diagrammatically suitable specific apparatus in which my process maybe applied tothe acid treatment of minerallubricating oil.

tling. chamber, and passing the diverted sample into contact with gaseous ammoniarwhereby the excess acid in the oil is neutralized. Itis preferble, but not essential, to conduct thediverted stream of il'through a ltering medium of any suitable type toremove therefrom the acid sludge lo prior to neutralization.` Any insoluble material present after the lneutralizing is commonly removed before the streaml of oil is subjected to color determination. A denite relationship which may be readily determined, exists between the color of the ammonia neutralized sample and the nal color of the neutralized oil obtained as a ilnished productfrom the usual treating process. The sample obtained as /above described is next passed through a glass sided cell, or its equivaient, which is-interposed between a source of light and a light-sensitive cell, such as 1) a photo-electric or photolytic cell which includes an alkali metal cell, or (2) a selenilmi cell. The amount of light transmitted through the tlowing ystream of oil varies with the intensity of the color Vof the oil 'and accordingly with the degree of acid treatment, and will cause variations in the amount bf (1) electric energy generated by the photonlectric or photolytic cell, or (2) resistance of the' iielenium cell, respectively. The rate at which tlectrical energy is generated in' the photo-eleciric or photolytic cellor the changes which occur In the resistance of the selenium cell as the case may be, is recorded ona scale or chart. 'I'he chart may, for example, be rotated under control 'cfa clock mechanism and color may be recorded by transverse iluctuations of a recording point.

Making particular reference to the single ilgure in the drawing,v a detailedl description of one method of carrying out my process, applied to the treatment of mineral lubricatingoil, will be disclosed.

' Oil which is to be acid treated, for instance, oil from one o'r more plates of a fractionating column of a pipe still distillation system, is pumped from I source of supply I to theknothole mixer 2 wherel it is intimately mixed with acontinuous stream of acid from tank 3.

monia contacting tower Il which contains haines, packing or other liquid-vapor contacting means I Ia. The oil iows downwardly through this tower countercurrent toand in direct contact with gaseous ammonia which is introduced into 5 the lower portion of the tower through' line I2,

which leads from an ammonia'supply in tank I3.

'of the oil passing to tank 9, does bear a definite relationship to the color of the finished oil, and

a variation in color of the diverted stream of -oil after treatment as aforesaid from a xed standard of comparison at once indicates that an incorrect 20 amount of acid is being admixed with the oil.

After passing through the nner I1 the divertedl stream of oil is passed through a transparent tube I8 which is interposed between incandescent lamp 20, connected with battery 2|, and light sen- 25 sitive cell 22. The oil after passage through tube I8 may. be returned to line 4 through valve controlled line I9, or if desired'since the stream of diverted oil is small, it may be conveniently col- 1ected in a suitable vesse1 by 'passing it from the' 39 system through valve-controlledline I 9 a which taps line I9;

'Ihe light sensitive cell 22 comprising a photoelectric cell upon which is impressed a constant voltage fromlsource 23, is connected to the grid and the cathode of a vacuum tube 24. Between the grid and the cathode of this vacuum tube is connected a resistance 25. Interposed between this resistance and the cathode .of the vacuum tube is the biasing-battery 26. The anode of this vacuum tube has impressed upon ita constant voltage from source 2l, and the cathode is heated In passing from source of su'pply I to the mixer 50, 2 a sample stream of the untreated oil is divetted through valve controlled line 3l, and is vpassed through a transparent tube I8avfor observation or color testing (as for example, by a system including elements numbered in the draw' 1 5'5 ing'as 20 to 30, which hereinafter will be described in detail), and thence is either introduced back into the main stream of oil through' valve controlled line 52, or, if desired, it may be passed to a suitable receptacle (not shown) by means of -.valve controlled line 83. In passing through the transparent tube I8a the color intensity of the sample stream of undecolorized oil is measured and recorded, for example, by means hereinafter referred to and shown in the drawing in connection with transparent tube I8.l

"The oil-acid mixture is transferred from the mothole-mixer through line 4 to a settling tank 5.4` Acid sludge is withdrawn through line 6 located at the bottom of the settling tank. Oil is 7u transferred from adjacent the top of the tank 5,

and after being mixed with water from tank lis resettled in the water settler 8, and then is pumped to suitable storage 9." A continuous sample is divvex'ted 'from line 4 by means of valve-controlled 35 "line I8 whichleadstotheupper, portion of am Aby current from supply source 29, the constant electromotive. force of which is adjusted by rheostat 30. As will be seen, the anode current and therefore the color of the oil passing through tube -I 8 is indicated and/or recorded by a galvanometer or potentiometer 28. The scale of this indicating instrument is adjusted so that color of the nnished product willbeindicated, for instance, in 50 the center of the scale, asat zero, and variation from this desired color may be indicated and recorded as a positive or negative number depending upon whether the oil is higher or lower in color than desired. f v

In operation, the diverted stream of acid-oil mixture is quickly neutralized, settled, filtered andpassed through the transparent cell, so that variation in the amount of vacid from that required to produce axed standard is indicated 60 continuously and within a short period of time. vHaving determined the relationship between the scale reading and the desired color of the finished oil leaving the settling chamber, 'it is seen vthat a direct check on the sumciency or inc5 suillciency of the acid treatment -is had, and this substantial change in thecondition of the oil,

acid, or operating of the apparatusto occur.-

If it is desired to regulate the decolorizing treatment in` an automatic manner, a system of relays maybe employed in conjunction with the photo-electric circuit. For example, a sensitive 15 relay 34 ymay be placed in the photo-electric circuitv in place of the4 galvanometer 28, such relay being in serieswith a battery 35, and a second relay 36 adapted to handle the current necessary to energize the pump motor 31. Should the sample stream of oil flowing thru the tube I8 be undesirably light in color, the intensity of the light passing thru the oil in the tube will be sufiicient to cause a considerable flow of current in the photo-electric circuit, and such current will energize the sensitive relay 34 to close the circuit including the battery and the relay 36. Relay 36, thus energized, will bring the relay contact bar 38 into the lower position, thus closing the pump motor circuit including the resistance 39. 'I'he increased resistance in the pump motor circuit will cause the pump motor' to slow down and less treating agent-will be introduced into the mixing vessel 2, in contact with the oil to be treated. 0n the other hand,

if the sample stream of oil passing thru the tube quantity of treating agent to the mixing vessel 2.

'Ihe method herein employed in expressing color of liquids is based on a definition of color similar to the concept of concentration of solutions. Thus a suitable standard liquid is arbitrarily assigned a standard color figure, say 10. By denition the color which results from mixing S volumes of the standard liquid with W volumes of a colorless white liquid, is taken as The colorimetric scale is so arranged that this concept of color concentration, or color intensity,

' as it is more generally designated, is retained over the whole range of colors, from the darkest liquid to a colorless liquid itself.v As can be seen, this system of expressing color provides a simple mathematical relationship between readings, the vlblac undecolorized distillate having its color intensity expressed in the same units as those used yto express the color of highly refined products. Further elaboration upon this method of expressing colors will be found in Vol. 22 (1930) Industrial and Engineering Chemter of making the control entirely automatic is a feature of the invention which may or may not be employed, as desired.- It can be readily sensed that time is of the essence in arriving at this color determination, for the longer the L period of time which elapses between the time of addition of the acid and the time at which the sumciency or insufficiency of acid treatment is determined' and communicated to the acid inlet valve, the greater will be the fluctuation of acid treatment, both under and over the correct amount. f

While the measurement of color after acid treatment is normally the only essential meas- 'urement in accomplishing certain aforementioned objects of my invention, e. g., controlling the rate at which acid is added to the undecolorized oil, yet by combining therewith the meas- 4urement of the color before acid treatment, that is, for example, after the oil leaves the fractionatingJ column and before it is introduced into the mixing chamber. the degree of color re' duction Whichactually takes place can be measuredl and recorded'. For example, by having this record bothbefore and after acid treatment, the ineilicient 'operation of the oil-acid mixing device could be discovered or a possible deterioration in strength of the acid could be located. Also, it will-abev seen that the process serves as a check on the operator, where changes are to be communicated from. .the light sensitive'cell to the acid inlet valve manually. Accordingly, it serves to increase the economy of the process by making the acid treatment uniform, for, withl out this continuous record or the equivalent, there would be no way of knowing whether the operator treated uniformly, or not. In addition the record of color before acid treatment serves to indicate the regularity or irregularity of operation in the fractionating column or other equipment through which the cil passes prior to the acid treatment. For example, improper deentrainment of liquid from'the lvapors in the operation of a fractionating column would manifest itself g by an increase in color intensity of the oil issuing from one or more of. theside streams from the column.

In saying that uniform treatment will make for economy in acid consumption it might be well to point out that more acid is required per unit of color reduction below the desired color standard than is required per unit of color reduction above the desired standard. That is, when one tries to reduce the last traces of color from an oil a large excess of acid must be used. The amount of acid actually consumed in removing certain quantities of color imparting compounds from an oil of low color intensity is necessarily much greater than the amount of acid which would be consumed in removing a corresponding amount of color-imparting compounds from an oil of higher color intensity.

The rotation of the color recording charts in the preferred arrangement of Amy apparatus is controlled by a clock mechanism, so that Vthe color intensity of the incoming oil and the outgoing oil at a particular time can be ascertained. If, for example, the oil before treatment runs quite uniform in color, and the color record of the treated oil is shown by a line having a large number of fluctuations both above and below the standard color datum line, it is indicative of poor control on the part of the operator. However, if records both before and after treatment are quite uniform or free from any large iiuctuations, and yet an abnormally large amount of acid was consumed, it is indicative of some irregularity in the supplying an economic control is spoken of, A

that economic control comprehends elimination of the excessive use of acid or other decolorizing agent, control of the efElcient functioning of theA apparatus and equipment, and ascertainment of unfavorable conditions which may exist in the treatment given the oil prior to the decolorizing treatment.

While I have described my invention with particularity, it will be understood that it broadly relates to a process for the controlled decolorization of hydrocarbon oils. Regardless of the specific decolorization process or means used, e. g.,

regardless of whether acid or other decolorizlng agent is employedin the decolorization, itis to vbe understood that it is Within the scope of my in,-

vention to eciently control in such decolorizing process. Further, it will be observed that in the treatment of the diverted sample stream, as disclosed, the steps in the process of bringing the sample stream into a suitable condition to have its 'color measured may be varied within limits, and still permit a record to be had which Will bear a substantially direct relationship to the nal color of the main body of the oil being treated. The essential thing is to choose such steps for bringing the oil being treated to a condition where its color may be determined, that will require a minimum of time to intervene between the addition of acid or other decolorizing agent and the determination of the suiliciency or insumciency,

of the amount of such agent being added.

While a light sensitive cell or similar device is given herein as a means for automatically determining the color of the treated oil, it is alsopossible, though less satisfactory, to determine withv the eye in a modification of an ordinary colorimeter the color of the stream of neutralizedoil by-comparison with a standard sample.

It is pointed out that a combined process of'decolorization control including the step of recording color of the passing oil before treatment is distinctly advantageous. The idea of variationA in color of a black oil issuing from the fractionat ing column was entirely overlooked prior to my invention. This oversight lmay be explained by the fact that the oil as it issued from the fractionating colum'n always appears black evenv invention. This process of color recording has meant a great saving in acid. The continuous color record serves to keep a constant check on whether or not a fractionating column is eiliclently functioning to eliminate entrainment, and to locate other places in the treating process and apparatus in which improvement can be made.

What I claim is:

l. 'Ihe process of controlling the decolorizing treatment of hydrocarbon oil by passing through a conduit a stream of said oil to which a decolorizing acid has been added, diverting a relatively 10 oil flowing in the main stream, clarifying the` oil in the sample stream by the removal of sediment therefrom, photoelectrically recording variations Y in the color intensity of the clarified oil in said 20 sample stream, photoelectrically recording variations inc'olor intensity of the Aoil in the mainv stream prior to acidication and comparing said records as a means for controlling the decolorizing operation.

2. The process of controlling'the de'colorizing treatment of hydrocarbon oil by passing through a conduit a stream of said oil to which a denlte quantity of sulphuric acid has been added, diverting a relatively small sample stream of oil from 30 said main stream, introducing a measured (,uan-y tity of ammonia into said sample stream adapted to quickly .react with said sample stream and impart a color intensity thereto bearing a predetermined. relationship to the ultimate color of 35 HORACE M. WEIR.

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