US2121517A - Art of removing asphalt from asphalt base oils - Google Patents

Description

. June-21, 1938" D. G. BRANDT` ART OF REMOVING ASPHALT FROM ASPHALT BASE OILS Filed May 16, 19321 Sw N% Y e Wmv Patented June 21, 1938 REMOVING ASPHALT FRIOM ASPHALT BASEOILS .I

ART OF David G. Brandt, Westfield, J., assigner to Power Patents Company, Hillside, N.' J., a corporation' of Maine Application May 16, 1933, Serial No. 671,317

5 Claims.

`This invention relates to a process and apparatus for removing asphalt or bituminous materials from asphaltic petroleum oils, and more particularly for the recovery of valuable oil cong stituents and the production of marketable asphalt.

The asphalt used for making roads and for various purposes in the arts, is derived either from natural sources or from selected asphaltic petroleum oils. The usual procedure for obtaining asphalt from petroleum oils containing the same, is to distill the oil down to a heavy 4residue and use the whole of the residue after blowing with air, or other treatment, for the production of road. asphalt Vor other` asphaltic products. Such processes however, have been very wasteful of valuable cil constituents, particularly paraffin hydrocarbons, which are `suitable for the manu facture of lubricating oils. l

'I'he primary'object of thevpresent invention is the production of a high grade asphalt and the recovery of valuable oil constituents which have been heretofore waste. y

A further object of the invention is the provision of a process for removing asphalt from petroleum oil residues such as are formed froml the distillation of asphalti'c petroleum oils (mixed base or asphalt base oils) or produced in the cracking of petroleum oils.

The process of the present invention includes a relatively simple and effective procedure for removing asphalt from asphalt-containing oils which includes the steps of forming a-mixture of thel oil to be .tre-ated with a low molecular Weight hydrocarbon diluent l at a superatmospheric pressure and at a temperature suitable for lthe precipitation of the asphalt, passing the mixture into a settling zone in which the asphalt is allowed to precipitate or settle out, and thereafter separatingthe hydrocarbon diluent from the oil separated from the asphalt. l

The present invention also includes the use of a novel apparatus as well as other features, objects and advantages which will be apparent from the following detailed description taken in connection with the accompanying drawing in which: Y v

The ligure is a diagrammatic view partly in section of an apparatus-adapted to carry out the steps and features of the improved process.

The oil from which the asphalt is to be removed and which may be mixed base or purely asphalt base oil, is withdrawn from a chamber 2 through a line 4. The chamber 2 may represent the lower portion of a cracking chamber, distilling chamber, or other chamber from which the oil is Withdrawn through the line 4 in a heated condition at a temperature for example of from 450 to '750 F. This oil containing a substantial proportion of asphalt is'forced by means of a pump 6 anda line 8 through a heat exchange coil I0, mountedinthelower portion of apressure still I2, wherein the heat of the oil passed through the coil I0 is used for vaporizing the low molecular weight hydrocarbon from the asphalt-free oil produced inthe process. `'I'he oil leaving the coil I3 is then conducted .through a heat exchanger I4, a pipe I6, and then through a cooler I8 from which the oil passes at a temperature of from 50 to 130 F., through a pipe 20, in which is mount-ed a recording flow meter 22, or measuring device, and a branch pipe 24, into a mechanical mixer 26. In the pipeg24 and mixer 26, the asphalt-bearing oil is intimately mixed with a predetermined'quantity vof a vlow molecular weight hydrocarbon suchfas liquid propane, and the Vmixture is conducted' by meansof pipes 28 and 30 andv a branch pipe 32 'into the first of a series of pressure-settling chambers 34, '36 and 3B. The chambersv 36 and 38 are connected with pipe 30 by means of valved branchpipes 4I] and 42 respectively.

`The diluted oil mixture containing from 10% to 75% liquidv propane by volume, is conducted under pressure through the line 32 into one end offthe'chamber 34 and allowed to completely ll the chamber, so that` thereafter the diluted oil flows .thrOugh'the chamber' in a quiet manner, thus permitting theasphalt to settle out. Under these conditions, experiments have shownrthat because ofZ the lowvis'cosity and gravity of the oil ,blend, the asphalt settles in a manner comparable to the settling of sand from Water. The oil mixture in the chamber 34 is `completely freed of asphalt andthe clear asphalt-free oil blend is conducted from the chamber through an overflow line 44, into a valved discharge line 46 by which the oil is conducted to a pump 48 and forced through' a connecting line 5U, a heat exchanger 52 and heat exchanger I4 into the upper mid-portion of pressure still I2. The asphaltfree oil IblendY passing through the heat exchangers 52V andV I4`is heat-ed to asubstantial extent and then discharged on to av distributor tray 53 so that the oil mixture is rained or sprayed over the coils Ill mounted in the lower part of pressure still I2. The heat derived from the heat exchangers 52 and I4 andthe coil I0 is sufficient to vaporize substantially all of the propane contained in the oil blend. 55

The propane vapors are conducted from the still I2 through a vapor line 54 and passed through condensers 56 in which the propane is condensed under a suitably high pressure, and from which the condensate is conducted through a line 58 into a receiver 60. This receiver is pro- Y vided with an automatic pressure relief line 62 and with a float valve controlled line 64 through which the liquid propane is conducted into apropane storage tank 66. 'I'he outlet temperature from the pressure still I2 may be controlled by conducting liquid propane from. receiver 60 through a line 68 into the upper part of the still |2 onto one of the upper trays therein.

The petroleum oil recovered in the process, and which is of particular value for lubricating purposes, is discharged at a reduced pressure from the lower part of pressure still |2 through a liquid level valve controlled line 10 into a steam stripping contact chamber 12, in which the last traces of propane are removed. 'I'he asphaltand propane-free oil is conducted from stripper 12 through a liquid level valve controlled line 14 and passed to storage through heat exchanger 52 where the heat contained in the oil is used to preheat the oil being introduced into still I2. The propane vapors and steam separated in stripper 12 arefconducted through a vapor line 16 and a condenser 18 into a water separator 80. 'I'he propane remains uncondensed in the condenser 18 and is conducted from separator 80 throughl a line 82, placed under pressure by means of a compressor 84 and forced through a line 86 into the upper part of pressure still I2, where the propane is mixed with the vapors produced directly from the oil. vIt will be understood that a superatmospheric pressure up to 400 pounds or more per square inch is maintained in the still |2,:conden`sers 56 and receiver 60, according to the hydrocarbon usedas diluent, while a relatively low pressure of slightly more than atmospheric may be maintained in the stripper 12.

As soon as settling chamber 34 is filled suiliciently with settled asphalt, the stream of oilasphalt-diluent mixture flowing through lines 28 and 30 is turned into chamber 36 by opening the valve in branch pipe 40, and closing the valve in branch line 32. The oil blend thereupon continues Vto flow into settling chamber`36 until it is sufliciently filled with asphalt after which the valve in branch line 42 is opened and the valve in branch line is closed. From the chamber 36 the asphalt-free oil blend is conducted through the overflow line 44 and va valved connecting line 41 into the line 46.V When the chamberv38 is cut into thesystem, the asphalt-free oil blend passes through the overflow line 44 and a valved connecting line 49 into the line 46. When the asphalt-free oil is being conducted through the line 41 the valves in lines 46 and 49 are closed.

Assuming that the stream of oil blend from the mixer 26 is being conducted into chamber 36 after completing the chamber 34, it will be apparent that the body of asphalt in the latter chamber will contain a substantial amount of occluded oil. This oil is washed from the asphalt with fresh liquid propane. Liquid propane to be used in the process is therefore withdrawn from storage 66 and conducted through a line' 88, in which is mounted-a pump 90 and a flow control valve 92, and passed into a distributing line 94. This line 94 is provided with valved branch lines V96, 98 and |00 which connect respectively into settling chambers 34,36 Yand v38 through branch lines 32, 40, and 42. 'I'he liquid propane is conducted from the line 94 through the branch lines 96 and 32 into the chamber 34, and distributed into the body of asphalt therein, for the purpose of Washing the oil therefrom. The wash liquor overows from the chamber 34 through the discharge line 44, a valved branch line |02 and a line |04, into the line 24, where the propane Wash is mixed with the oil stock to be deasphalted. The quantity of oil washed from the asphalt in chamber 34 or any of the other chambers 36 and 38, is not sufficient to materially alect the propane as a blending agent in chamber 26. In fact, the quantity of propane, suicient for later use in the process, would be so great compared to the oil removed from the asphalt body, that the oil would have no appreciable affect on the blend formed in mixer 26. 'I'his operation however is very effective for removing the oil from the asphalt in chamber 34. The chambers 34, 36 and 38 are cut into the system successively as asphalt precipitation chambers, and then cut into the leaching system for removing the oil from the precipitated asphalt. Chamber 36 is connected with the line 94 by means of valved line 98 for the admission of liquid propane, and the extract is removed therefrom through overilow line 44 and a valved connecting line |06 which connects into line |04. Similarly'in the leaching of asphalt in chamber 38, the liquid propane is admitted through valved line |00 and the wash liquor discharged through overflow 44 and a valved branch line |08 which connects with the line |04.

In the continuous operation of the system, the proportion of liquid hydrocarbon conducted through the lines 83 and |04 to be mixed with the oil flowing through the line 20 may be automatically regulated by means of an automatic proportioning regulator ||0 which is connected into the flow meter or measuring device 22 and automatic valve 92. The regulator may be set to properly proportion the amounts passed through lines 20 and 88.

The body of asphalt collected in the chamber 34 following the washing with liquid propane contains some propane and a small amount of oil. The propane is removed from the asphalt by closing the valves in lines 96 and |02 (the valves in lines 32 and 46 are closed), and opening the valves in the vapor discharge line ||2 which discharges into a main vapor line ||4 leading to a tower ||6. The asphalt mixture is then heated under a superatmospheric pressure to a temperature of from 400 to 500 F., or to a temperature sufiicient to vaporize all of the propane and low boiling oil constituents Vwhich may be present. These vapors are conducted into the tower ||6 in which the propane is separated as a vapor and conducted through a vapor line ||8, condensers |20, and into a receiver |22. The oil condensed in tower i |6 may be withdrawn to storage through a valved discharge line |24. The chamber |22 is provided with a float valve controlled discharge line |26 (part not shown) for conducting liquid propane to storage 66 and with a vapor line |28 which may connect into compressor 84. An automatic pressure relief line |30 also connects into the chamber |22 through the line |28. The outlet temperature in tower I6 may be controlled by passing regulated amounts of liquid propane from receiver 22 through the return line |32.

The asphalt mixture in chamber 34 is heated by means of an indirect heating medium passed through a heating coil |34 mounted therein. This coil is supplied with a iluid heating medium such as a high boiling point oil or other suitable fluid which is circulated through a heating coil |36 of a pipe still heater |38. The heating medium is passed through lthe coil |36 by means of a pump `|40 and a valved connecting pipe |42, and discharged from the heater through valved pipes |44, |40, |48, apipe |50, and a valved connecting pipeV |52, which connects with the inlet of the coil |34 in chamber 34. The oil is circulated continuouslythrough the coil and heater untilfthe necessary heating is completed. The oil from the `coil' |34 passes through a valved connecting pipe |54 and through a pipe |56 to' the pump |40.

Each of the chambers and 38 is provided with vapor outlets |3 and l I5 which connect with Y vapor line H4, and is also provided with coils |34 and. connected into the heating coil`|36 by suitable pipe connections. The coil |34 in chamber 36 is provided with a valved inlet pipe |51 which connects into the pipe |50, and with valved outlet pipe |58 which connects into-the inlet of the pump |40. The coil |34 in chamber 38is provided with 'a valved inlet pipe |60 which connects into the pipe |50, and with a valved outlet `pipe |62 ,whichconnects into the pump inlet pipe |56.

By suitably setting the valves in the various pipes referred to, any one of the chambers may be connected into the heating system.

After the asphalt in chamber 34 .has been heated for a sufficient time to removey substantially all the propane and oil, the asphalt may be stripped with steam, introduced through a perforated distributor pipe |64. Each of the chambers 36 and 38 is also providedwith a similar distributor pipe. Following this stripping, the asphalt in chamber 34 may be withdrawn while hot through a valved discharge line |66, or the asphalt may Vbe first blown with air admitted through the valved line |64 for the purpose of producing a road asphalt, and then discharged through the line |66.4 In the blowing operation, the vapors and air may be vconducted through the lines ||2 and ||4 into the tower ||6 and the air or gases vented from receiver |22. In this operation of course, it will be understood that receiver |22 will not be connected into the propane storage 66 or with the compressor 84. Instead of conducting the air and vapor constituents into the tower i6 they may be bypassed from the line lli into other suitable condensing or treating means.

During the blowing operation in chamber 34 considerable heat may be developed, but the temperature of the asphalt may be controlled by circulating arcooling medium through the coil |34. This may be accomplished by using the same fluid which is used for heating, cutting out the heating coil |36 by closing the valves in lines |742 and |44, and passing the fluid from the pump |40 through line |46 and a valved branch line |68, into a cooler |10. The cool fluid is discharged from cooler |10 through a valved branch line |12 and into the lines |50 and |52. In this operation it will be understood that the valve in line |48 will be closed, and that the valves in lines |52 and |54 are open, so that the fluid may be circulated continuously through the cooler |10 and the coil |34. A

As the chambers 36 and 38 are cut into the system for removing the hydrocarbon from the asphalt, the cooler |10 may becut into the system at the proper time in the manner referred to above in, conection with chamber 34.

While the process of the present invention has been described in connection with 4the use` of ing the absorption mixture.

of hydrocarbons is used as the diluent, a mixtureI liquid propane as a precipitating or diluting medium, it is to be understood that the invention is not limited to this particular hydrocarbon, but that low molecular weight hydrocarbons such as methane, ethane, propane, the butanes, the pentanes, the corresponding oleiins and naphthenes and mixtures thereof may be used. Furthermore, a mixture of any of these constituents with other hydrocarbons, may be used as a diluent provided the specific gravity of the diluent is not higher than that of pentane. The diluent may be blended with -the asphalt-containing oil in any suitable manner, for example, the diluent may be absorbed intothe oil under pressure while cool- Where a mixture of relatively narrow boiling range is preferred because of the greater ease in controlling the temperatures and pressures which are necessary inv carrying out the process. Such a mixture may `comprise one of the commercial products now produced by the fractionation of natural gas or cracking still gases.

The process of the present invention may` be varied in many respects without departing from the spirit and scope thereof, and the apparatus may be altered to suit the particular conditions which may be encountered in the treatment of any particular asphalt-bearing stock. 'I'he oil produced by they process, if removed from the asphalt at aV comparatively high temperature, may contain some wax or petrolatum which may not precipitate. This may 4be removed in a subsequent operation at a lower temperature so as to completely prepare the oil for lubricating purposes. In the foregoing description three asphalt separating chambers have been described but any number may be used in the system according to the specific cyclic operation to be `carried out. Instead of settling the asphalt from, the oil by gravity, it may be removed by filtration or by centrifugal separation.

Having thus described the invention in its Y preferred form, what is claimed as new is: l

1. The process of separating asphalt 'from asphalt-bearing oils, which comprises continuously mixing a stream of oil to be treated with a substantial proportion of a low gravity blending agent 'comprising a hydrocarbon diluent selected from the group of hydrocarbons: consisting of methane, ethane, propane, the butanes, the pentanes, the corresponding olenes and naph-V thenes, and mixtures thereof, passing a stream of the resulting mixture into one of a plurality of enlarged settling Zones in which the asphalt contained in the oil is precipitated therein until a substantial quantity of asphalt is contained in said zone, thereafter diverting said stream of oil mixture from said enlarged zone into another zone of said plurality of enlarged zones to deposit asphalt therein, introducing fresh blending agent into the precipitated asphalt contained in said first-mentioned zone following said precipitation to wash any occluded oil therefrom, removing the washed asphalt from thel enlarged zone, utilizing the wash liquor from said washing operation for blending with said fresh asphalt bearing oil introduced into the process to supply at least in part the blending agent, and

the washing" of the precipitatedasphalt therein, and thereafter heating theasphalt mixture in each settling zone following the Washing of the oil therefrom to vaporize and thereby remove the blending agent from the precipitated and washed asphalt.

3. The method of separating asphalt from a hot asphalt-containing residuum produced in a distilling operation, which comprises passing the' hotv residuum in indirect heat exchange with an oil mixture being distilled in a distilling zone to heat the oil mixture and effect distillation of a portion thereof, thereafter mixing a low gravity blending agent with said residuum to substantially dilute said residuum and precipitate theV asphalt contained therein, said agent comprising a hydrocarbon or mixture of hydrocarbons selected from the group consisting of methane, ethane, propane, the butanes, the pentanes, the corresponding olens and naphthenes, passing the mixture of residuum and blending agent alternatively into the respective chambers of a. plurality of asphalt settling chambers and therein permitting the settling of the asphalt from the diluted oil mixture, decanting separated oil and blending agent from the mixture in each settling chamber during the time the mixture is supplied thereto and conducting it into said distilling Zone wherein the blending agent is vaporized and distilled from the oil thereby recovering an asphalt-free oil as a product of said asphalt-containing residuum.

4. An apparatus for removing asphalt from asphalt-containing oils, comprising means for mixing asphalt-containing oil with a 10W gravity blending agent, a plurality of asphalt settling chambers, and means for separately conducting the asphalt oil-blending agent mixture into any one of s-aid chambers, means for separately introducing blending agent into each of said chambers to Wash the asphalt deposited therein while asphalt is being precipitated in another chamber, and means for conducting the Wash liquor from each of said chambers to the means for mixing-the blending agent with asphalt-containing oil.

5. The apparatus defined by claim 4 in which means is provided for heating and for cooling the contents of said settling chambers.

DAVID G. BRANDT.

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