CA1126186A - Process for recovering a premium oil from a slurry produced by high temperature hydrogenation of a solid, hycrocarbonaceous fuel - Google Patents
Process for recovering a premium oil from a slurry produced by high temperature hydrogenation of a solid, hycrocarbonaceous fuelInfo
- Publication number
- CA1126186A CA1126186A CA331,941A CA331941A CA1126186A CA 1126186 A CA1126186 A CA 1126186A CA 331941 A CA331941 A CA 331941A CA 1126186 A CA1126186 A CA 1126186A
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- slurry
- column
- solvent
- oil
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Abstract
ABSTRACT OF THE DISCLOSURE
Process for separating feed slurry, produced by high temperature hydrogenation of solid hydrocarbon fuel and containing fine solids and polar liquids and oil, into first fraction (oil) and second fraction (fine solids and polar liquids), where (a) the slurry is mixed with a nonpolar sol-vent in a vertical column having (1) settling, (2) con-tacting and (3) collection zones, (1) and (2) being operated at 100°C-250°C and sufficient pressure to keep slurry and solvent in liquid state but less than 450 psi (317 kg/cm2). The slurry is introduced near the top of (2) and the solvent near the bottom of (2 and in a weight ratio of at least 0.5:1. They are mixed such that the solvent passes up through the column and contacts the slurry in countercurrent man-ner and extracts the slurry from the oil; and (b) the first fraction is recovered from (1) as an overflow, and the second fraction from (3) as an underflow.
18,394A-F
Process for separating feed slurry, produced by high temperature hydrogenation of solid hydrocarbon fuel and containing fine solids and polar liquids and oil, into first fraction (oil) and second fraction (fine solids and polar liquids), where (a) the slurry is mixed with a nonpolar sol-vent in a vertical column having (1) settling, (2) con-tacting and (3) collection zones, (1) and (2) being operated at 100°C-250°C and sufficient pressure to keep slurry and solvent in liquid state but less than 450 psi (317 kg/cm2). The slurry is introduced near the top of (2) and the solvent near the bottom of (2 and in a weight ratio of at least 0.5:1. They are mixed such that the solvent passes up through the column and contacts the slurry in countercurrent man-ner and extracts the slurry from the oil; and (b) the first fraction is recovered from (1) as an overflow, and the second fraction from (3) as an underflow.
18,394A-F
Description
IMPROVED PROCESS FOR RECOVERING A
PREMIUM OIL FROM A SLURRY PRODUCED BY
HIGH TEMPERATURE EYDROGENATION OF
A SOLID, HYDROCARBONACEOUS FUEL
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This invention relates to a process for sepa-rating a slurry comprising fine solids, polar liquids and premium oil, the slurry produced by high temperature hydro-aenation of ~ solid ~ydrocarbonaceous fuel into a first fraction comprising the premium oil and a second fraction comprising the fine solids and polar liquids.
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The high temperature hydrogenation of solid, hydro~arbonaceous fuels, such as the li~ue~action of coal, produces a feed slurry, comprising not only pre-mium liquid oil but also various solids, e.g., ash, inor-ganic sulfur, and other liquids, e.g., polar liquids.Removal or separation of these materials, especially the fine solids from the premium oil, is a major problem and has been the subject of much research.
British Patent 312,657 discloses an apparatus 20~ and process ~or the separation from solid residues of oi].s obtained in the destructive hydrogenation va.rieties of coal, tars, mineral oi.ls and the like. The apparatus com-prises a vertical column with a settling vessel attached `
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PREMIUM OIL FROM A SLURRY PRODUCED BY
HIGH TEMPERATURE EYDROGENATION OF
A SOLID, HYDROCARBONACEOUS FUEL
:
This invention relates to a process for sepa-rating a slurry comprising fine solids, polar liquids and premium oil, the slurry produced by high temperature hydro-aenation of ~ solid ~ydrocarbonaceous fuel into a first fraction comprising the premium oil and a second fraction comprising the fine solids and polar liquids.
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The high temperature hydrogenation of solid, hydro~arbonaceous fuels, such as the li~ue~action of coal, produces a feed slurry, comprising not only pre-mium liquid oil but also various solids, e.g., ash, inor-ganic sulfur, and other liquids, e.g., polar liquids.Removal or separation of these materials, especially the fine solids from the premium oil, is a major problem and has been the subject of much research.
British Patent 312,657 discloses an apparatus 20~ and process ~or the separation from solid residues of oi].s obtained in the destructive hydrogenation va.rieties of coal, tars, mineral oi.ls and the like. The apparatus com-prises a vertical column with a settling vessel attached `
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*o its top and a worm gear attached to its bottom. The -process comprises introducing a slurry of solid residues ~d oils into the column at or near the column top and a ~olvent, typically benæene, into the column at or near 5 the column bottom such that the solvent, as it passes up -~he col~mn, extracts from the slurry as it passes down ~he column, the oils. The solid residues are removed as a powder from the bottom ~f the column by the worm gear while the oils are remo~ed from the top of the column as an overflow from the settling vessel.
~ err-McGee (USP 3,607,716 and 3,607,717) teaches a gravity settling process comprising removing ~rom a coal liquefaction product fine solids using a -solvent heated to a super-critical temperature. This process differs from others in that the solids settle in a dense phase gas (the solvent under super-critical con-ditions). The fine solids are contained in the extrac-tio~ residue.
he present invention is an improved process for separating a feed slurry produced by high temperature hydrogenation of a solid, hydrocarbonaceous fuel and com-prising fine solids, polar liquids and premlum li~lid oil, into a first fraction comprising the premium liquid oil a~d a second fraction comprising the fine solids and polar 2~ liquids, characterized by (a) mixing the feed slurry with a nonpolar liquid solvent ~hich is a C5-Cg aliphatic or alic~I-clic hydrocar~on or a naphthenic or paraffinic frac-tion of a coal liquefaction product containing less than 10 weight percerlt axomatic compounds, -the mixing 18,394A F
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*o its top and a worm gear attached to its bottom. The -process comprises introducing a slurry of solid residues ~d oils into the column at or near the column top and a ~olvent, typically benæene, into the column at or near 5 the column bottom such that the solvent, as it passes up -~he col~mn, extracts from the slurry as it passes down ~he column, the oils. The solid residues are removed as a powder from the bottom ~f the column by the worm gear while the oils are remo~ed from the top of the column as an overflow from the settling vessel.
~ err-McGee (USP 3,607,716 and 3,607,717) teaches a gravity settling process comprising removing ~rom a coal liquefaction product fine solids using a -solvent heated to a super-critical temperature. This process differs from others in that the solids settle in a dense phase gas (the solvent under super-critical con-ditions). The fine solids are contained in the extrac-tio~ residue.
he present invention is an improved process for separating a feed slurry produced by high temperature hydrogenation of a solid, hydrocarbonaceous fuel and com-prising fine solids, polar liquids and premlum li~lid oil, into a first fraction comprising the premium liquid oil a~d a second fraction comprising the fine solids and polar 2~ liquids, characterized by (a) mixing the feed slurry with a nonpolar liquid solvent ~hich is a C5-Cg aliphatic or alic~I-clic hydrocar~on or a naphthenic or paraffinic frac-tion of a coal liquefaction product containing less than 10 weight percerlt axomatic compounds, -the mixing 18,394A F
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~eing conducted in a vertical column comprising a settling zone, a contacting zone and a collection 20ne, the settling and contacting zones operated at a-temperature between 100C and 250C and at a pres-sure sufficient to maintain both the slurry and sol-Ye~t in a liquid state but less t~an 450 psi (317 -kg/cm2), the slurry being introduced into the column at or near the top of ~he contacting zone and the solvent being introduced into the column at or near the bottom of the contacting zone, the sclvent and slurry being mixed in a weight ratio of at least 0.5:1 and contacted in such a manner that the 501--vent:
: (1) passes up and through the column while the slurry pas~es down and through the ~ol~mn;
: .(2) is in intimate contact with the ~ - slurry as the solvent and slurry simulta-- . ~eously pass through the colum~; and ~0 (3) extracts from the slurry, as the ~olvent and slurry simultaneously pass through the column, the premium liquld oil;
(b) recovering from the settling zone of the column as an overflow the first frac-tion; and : 25 ~c) recovexing from the collection zone of the column, as a viscous slurry underflow, the second fraction.
This process produces an essentiall~ solids-free over-flow of premium oil and an under:1Ow con-tainlng a minimum amount of pre~ium oil. Moreover, this process removes o~her materials, such as uncon~er-ted fuel, polar mole-cules rich in heteroatoms (o, N, S).
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~eing conducted in a vertical column comprising a settling zone, a contacting zone and a collection 20ne, the settling and contacting zones operated at a-temperature between 100C and 250C and at a pres-sure sufficient to maintain both the slurry and sol-Ye~t in a liquid state but less t~an 450 psi (317 -kg/cm2), the slurry being introduced into the column at or near the top of ~he contacting zone and the solvent being introduced into the column at or near the bottom of the contacting zone, the sclvent and slurry being mixed in a weight ratio of at least 0.5:1 and contacted in such a manner that the 501--vent:
: (1) passes up and through the column while the slurry pas~es down and through the ~ol~mn;
: .(2) is in intimate contact with the ~ - slurry as the solvent and slurry simulta-- . ~eously pass through the colum~; and ~0 (3) extracts from the slurry, as the ~olvent and slurry simultaneously pass through the column, the premium liquld oil;
(b) recovering from the settling zone of the column as an overflow the first frac-tion; and : 25 ~c) recovexing from the collection zone of the column, as a viscous slurry underflow, the second fraction.
This process produces an essentiall~ solids-free over-flow of premium oil and an under:1Ow con-tainlng a minimum amount of pre~ium oil. Moreover, this process removes o~her materials, such as uncon~er-ted fuel, polar mole-cules rich in heteroatoms (o, N, S).
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The slurry here used is a slurry generally produced from the high temperature hydrogenation of any solid, hydrocarbonaceous fuel. The slurry produced from the liquefaction of coal is illustrative. The solids portion of this slurry comprises fine solids (e.g., ash), inorganic sulfur (e.g., pyrrhotite) and organic solids (e.g., unreacted coal) while the liquid portion comprises premium oil (e.g., hexane-soluble slurry components, such ~s paraffinic, naphthenic and aromatic hydrocarbons), and polar liguids ~e.g., asphaltenes and toluene-insolubles, both defined hereinafter). "Fine" here describes solids or minute particles of about 0.1 -to 20 microns in size.
The solids content (weighk basis) of this slurry can vary widely but is at least partially dependent upon the polar liquid's content. Generally, the greater the ~uantity of polar liguids present, the greater the solids content that can be effectively processed. Specifically, a sufficient guantity o~ polar llqulds must ~e lnsoluble ln the non-polar solvent at column conditions such that the polar liquids coalesce to form a separate, liguid continuum in which the fine solids content can be dispersed. Although guantitative parameters can and will vary with the par-; ticular feed slurry, column conditions, solvent, etc., it can be generally said that the resultant underflow should comprise less than about 65 weight percen-t solids. Con-~e~uently, a slurry compxising a solids content less than about 25 weight percent is preferred and a slurry compris-ing a solids content less than about 20 weight percent more preferred.
In a specific embodiment of this invention wherein hexane is the nonpolar solvent, an especially ~uited sluxry is produced by the liquefaction o a bitumi-nous coal. This slurry can take many forms, such as the ~lurry as produced (ash content of about 3 to 8 weight 18,394A-F
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The slurry here used is a slurry generally produced from the high temperature hydrogenation of any solid, hydrocarbonaceous fuel. The slurry produced from the liquefaction of coal is illustrative. The solids portion of this slurry comprises fine solids (e.g., ash), inorganic sulfur (e.g., pyrrhotite) and organic solids (e.g., unreacted coal) while the liquid portion comprises premium oil (e.g., hexane-soluble slurry components, such ~s paraffinic, naphthenic and aromatic hydrocarbons), and polar liguids ~e.g., asphaltenes and toluene-insolubles, both defined hereinafter). "Fine" here describes solids or minute particles of about 0.1 -to 20 microns in size.
The solids content (weighk basis) of this slurry can vary widely but is at least partially dependent upon the polar liquid's content. Generally, the greater the ~uantity of polar liguids present, the greater the solids content that can be effectively processed. Specifically, a sufficient guantity o~ polar llqulds must ~e lnsoluble ln the non-polar solvent at column conditions such that the polar liquids coalesce to form a separate, liguid continuum in which the fine solids content can be dispersed. Although guantitative parameters can and will vary with the par-; ticular feed slurry, column conditions, solvent, etc., it can be generally said that the resultant underflow should comprise less than about 65 weight percen-t solids. Con-~e~uently, a slurry compxising a solids content less than about 25 weight percent is preferred and a slurry compris-ing a solids content less than about 20 weight percent more preferred.
In a specific embodiment of this invention wherein hexane is the nonpolar solvent, an especially ~uited sluxry is produced by the liquefaction o a bitumi-nous coal. This slurry can take many forms, such as the ~lurry as produced (ash content of about 3 to 8 weight 18,394A-F
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5-pereent), the slurry after some solids removal, e.g., eentrifugation (ash content of about 0.5 to 5 weight per-eent), or the slurry after a solids concentration proce-dure, e.g., as the underflow from a hydrocyclone ~ash 5 eontent of about 10-15 weight percent). The solids con-tent of each of these forms is less than about 25 weight percent of the slurry.
The principle considerations in solvent selec-tion are that the solvent selectively extracts the premium oil and that the solvent and premium oil (extract) not have significant overlap in their distillation ranges (sinee such overlap can result in cross-contamination).
Sinee the components of the premium oil are generally ; nonpolar, a nonpolar solvent is used. The solvents are preferably hydrocarbon and more preferably C5-Cg aliphatic or alicyclic hvdrocarbon, such as ~entane, hexane heptane.
oetane, 3-methylpentane, cyclopentane, cyclohexane, etc.
Other suitable solvents inelude certain naphthenic or paraffinic fractions of a coal liguefaction product, such as a mixed C4-C5 portion or a paraffinic petroleum por-tion, sueh fractions cont.aining less than about 10 weight percent aromatic eompounds.
Column conditions (temperature and pressure) ean and will vary with the solvent and khe eomposition of the feed slurry. A minimum eolumn temperature is required suf~icient to maintain the feed and residual slurries in the li~uid state. The column temperature eannot exceed the eritical temperature of the ~olvent.
A minimum p.ressure is reguired sufficient -to avoid vapor-ization o both the solvent and the feed slurry. Practi-eal eonsiderations, such as eguipment, economy, etc., are ~he only limitations upon the maximum pressure that can be employed.
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The principle considerations in solvent selec-tion are that the solvent selectively extracts the premium oil and that the solvent and premium oil (extract) not have significant overlap in their distillation ranges (sinee such overlap can result in cross-contamination).
Sinee the components of the premium oil are generally ; nonpolar, a nonpolar solvent is used. The solvents are preferably hydrocarbon and more preferably C5-Cg aliphatic or alicyclic hvdrocarbon, such as ~entane, hexane heptane.
oetane, 3-methylpentane, cyclopentane, cyclohexane, etc.
Other suitable solvents inelude certain naphthenic or paraffinic fractions of a coal liguefaction product, such as a mixed C4-C5 portion or a paraffinic petroleum por-tion, sueh fractions cont.aining less than about 10 weight percent aromatic eompounds.
Column conditions (temperature and pressure) ean and will vary with the solvent and khe eomposition of the feed slurry. A minimum eolumn temperature is required suf~icient to maintain the feed and residual slurries in the li~uid state. The column temperature eannot exceed the eritical temperature of the ~olvent.
A minimum p.ressure is reguired sufficient -to avoid vapor-ization o both the solvent and the feed slurry. Practi-eal eonsiderations, such as eguipment, economy, etc., are ~he only limitations upon the maximum pressure that can be employed.
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As here used, "column t~mperature", "zone tem perature", and similar terms mean the temperature of the column wall or that portion of the column wall defining a zone. The temperature of the slurry, solvent and sepa-ration products of the slurry may or may not obtain the same temperature of the column wall, depending upon the flow rate of these materials. Generally, the greater the flow rate, the less likely that these materials obtain the temperature of the column wall. Of course, the mater-ials obtain the heat of the column wall by conduction.
Although column pressure is generally uniform ~hroughout, column temperature generally varies from one area or zone of the column to another. Since the residual slurry is relatively high in solids and high molecular . 15 weight polar materials content, it is the most viscous and rec~ires the greater tem~erature. Thus, the zone wherein this slurry collects is typically run at least about 20C
higher than the remainder of the column.
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Although quantitative temperature and pressure ranges cannot be stated generically, by way of illustration and with hexane as the solvent, a typical minimum column tempe~ature (excluding the residual slurry collection zone) is at least about 100C and preferably about 140C. The corresponcling pressures are typically about 180 psi and 200 psi (12.7 and 14.1 kg/cm2). A typical maximum temper-ature is about 225C and preferably about 200C with cor-xesponding pressures of about 450 psi and about 325 psi (31.8 and 23.0 kg/cm2). Although the residual slurry col-lection zone temperatures are yenerally about 20C higher, respectively, wi-th comparable pressures, p.referably the r~sidual slurry collection zone is ma.intained at a temper-atuxe of at least about 150C and most preferably at about 180~C.
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Premium oil extraction from the slurry is at least partially dependent upon the solven-t:slurry weight ratio fed to the vertical column. Generally the greater the solids content of the slurry, the greater the sol-vent:oil ratio used in the practice of this invention.
The use of a greater solvent:oil ratio under such circum-stances leaves a greater amount of polar liquids in the slurry and these polar liguids promote coalescence among the solids and thus fluidity of the underflow. A -typical minimum weight ratio of about 0.5:1 can be used although a ratio of about 0.6:1 is preferred. Practical considera-tions, such as energy efficiency, are the only limitations upon the maximum weight ratio although a maximum weight ratio of about 5:1, and preferably about 1:1, is typical.
A weight ratio of about 0.8:1 is especially preferred.
Generally, if the weight ratio is less than 0.5, i.e., less than 0.5:1, the recovered asphaltene has a reduced viscositY wnich indicates Poor seParation from tne prod-uct liquid. Moreover, detection of an interface between the residual slurry and the solvent-slurry phases becomes - difficult ,and the more difficult this becomes, the more dificult is the selective removal of the residual slurry from the vertical column. If the weight ratio is greater than about 1.0, feed slurry throughput (volume per unit time) is sacrificed and additional cost and utilities are incurred.
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Although the physical features (housing and channel size and shape) of the vertical column here used can be varied to choice, the column is typically a hol-low, elongated cylinder or pipe-like structure with a length over diameter (LOD) guotient between about 40 and 2 and preerably between about 20 and 5. The colurnn can be made from any suitable material but materials, such as ~teel, known to perform well under elevated temperatures , ~8,394A~F
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-and pressures are preferred. The column generally com-prises three zones: a first or settling zone, a second or contacting zone, and a third or collection zone.
~he first or settling zone is generally the top portion of the column, equipped with a solvent-pre-mium oil extract outlet, and commences abo~e an entry port used for introducing th~ slurry into the second or contacting zone. This first or settling zone collects the solvent and premium oil flowing up from the second or contacting zone for its ultimate removal from the column. The function of this settling zone is to pro-vide an area for the gravity separation of any fine solids that may have been carried from the contacting zone by the ~olvent and premium oil. As such, it is desirable that 1~ the solvent and premium oil be quiescent, i.e., have little ~ or no convection currents, to encourage any fine solids to - - settle ~ack lnto the contacting zone. On large scales, ~ertical baff-es or other design features may be useful in -preventing such co~vection currents and resulting fine solids presence in the column overflow.
The second or contacting zone is generally the mid-portion, i.e., the portion between the first and third zones, of ~he column and it generally is the largest (on an overall length basis) portion of the column. Within this zone, the slurry descends the column in a partially back-mixed, partially countercurrent mode. Although the solvent-premium oil phase is nearly completely back-mixed in this second zone (due to both the density difference between the premium oil and solvent and to convection cur-rents), there is a net countercurrent flow of the residualslurr~ downward against the upflow of the solvent-premium oil phase. This second zone is equipped with a slurry entry port at or near its top and a solvent entry port at ~8,394A-F
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or near its bottom. Use of internals within this zone may be useful, especially in large-scale operations, to disrupt convection currents. Any such internals should -~e designed to avoid the buildup of asphaltenic residue with exposed surfaces generally no more than 30 degrees off the vertical axis of the column.
The third or collection zone is generally the bottom portion of the column and typically has an enlarged ; diameter relative to the first and second zones. This æone collects ~he residual slurry, i.e., fine solids and other materials comprising the slurry not soluble in the nonpolar solvent, for their ultimate removal from the column. The column wall defining this zone is generally ; maintained at a higher temperature than the wall defining 1~ the second zone because the residual slurry which is col--~; lected in the third zo~e has a greater viscosity than , eit~er the slurry, premium oil or solvent and thus requires a higher temperature to maintain its liquid state. Since the third zone, like the first and second zones, is gen-erally operated on a continuous basis, the temperature dif-ferential exhibited between the wall defining the third zone and the wall defining the second zone is not believed paralleled by a similar temperature differential between the contents o~ the second zone and the contents o the third zone. Howevex, it is believed that the higher tem-perature of the wall defining the third zone inhibits accumulation of the solids-containing residual phase along the interior of the wall and thus promotes a steady ~- and uninterrupted discharge of the residual slurry.
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The third zone is also equipped with a resi-dual slurry outlet which can be located at any convenient poin-t about the zone but is p~eferabl~ located at the .
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~: , . , . , ' center of the bottom of the ~one. This avoids solvent and premium oil escaping due to their bypassing the resi dual slurry. The residual slurry outlet can be equipped with any conventional means for facilitating the removal of the residual slurry from the zone, such as a valve, worm screw, or extruder.
In the accompanying drawings in which like numerals are employed to desi~nate like parts through-out the same:
Figure 1 is a preferred, specific embodirnent of a vertical column;
Figure 2 is a schematic flow diagram illus-trating the vertical column of Figure 1 in a specific combination with conventional, downstream separation 1~ equipment, and F~gure 3 is a schematic flow diagram illus-~rati~g a variation of the combination shown in Figure Z.
' ~; Various items of equipment, such as valves, ; fittings, condensers, pumps, etc. have been omitted so as to simplify the description. However, those sk1lled in the ar-t will realize that such conventional e~uip-ment can be, and is, employed as desired.
In Figure 1, a vertical column 10 consists of a first or settling zone 11, a second or contacting zone 12, and a third or collection zone 13. Zone 11 is equipped with a solvent-premium oil outle-t 14 and a thermal jacket lla. Zone 12 is equipped with a slurry inlet 16, a sol~
vent inlet 17 and a thermal jacket 12a. Zone 13 i'a ~quipped with a residual slurr~l outLet 19 and a thermal jacket 13a.
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In Figure 2, column 10 is connected to an adi~
abatic flash drum 22 by conduits 21 and 23. A distilla-tion unit 26 equipped with a removal conduit 28 is joined both to flash 22 by conduit 24 and to column lO by con- ~:~
duits 27 and 23. Conduits 27 and 23 are mated with each other. A separator 31 is connected to column 10 by con-duit 29. A conduit 33 proceeds from separator 31 and a conduit 32 joins separator 31 with a condenser 38 which in turn is joined to column 10 by mated conduits 39 and 10 23~
In Figure 3, a separation unit 34 replaces the adiabatic flash drum 22 and distillation unit 26 of Figure 2. Unit 34 is connected -to column 10 by con- :
duits 21 and 23 and is e~uipped with a removal conduit 37. Column 10 is e~uipped with removal conduit 29.
Having thus de-scribed the apparatus and refer-ring now to Figure 1, a slurry is continuously charged to ~^~ column 10 through slurry inlet 16 while a nonpolar solvent `, i5 simultaneously and continuously charged to column 10 ~' 20 through solvent inlet 17. The solvent passes up and ~hrough zone 12 while the slurry simultaneously passes down and through the same. During this continuous, simul-; taneous passing, the solvent and slurry are in intimate contact and the solvent extracts from the slurry the pre-25 mium oil which is soluble in the solvent at the ~one 12 conditions, thus producing a first fraction comprising the solvert and premium oil and a second fraction (resi~
dual slurry) comprising the fine solids and polar li~uids.
The solvent and premium oil are continuously transported 30 into zone 11 and removed therefrom through outlet 14. ~he resldual slurry is continuously collected in zone 13 and removed therefrom through residual slurry outLet 19.
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Referring now to Figure 2, the solvent-premium oil mixture present in zone 11 of column 10 in the form of a substantially quiescent pool is removed as an overflow ~nd is passed through conduit 21 to flash drum 22 where some of the solvent is separated from the premium oil and recycled to column 10 via conduit 23. The remaining sol-vent~premium oil mixture is transferred to distillation unit 26 where the remaining solvent is distilled overhead and recycled to column 10 via conduits 27 and 23 while the premium oil is removed as an underflow through removal out-~; let 28.
The residual slurry collected in zone 13 ofcolumn 10 is removed as an underflow and is passed to separator 31 via conduit 29. Separator 31 recovers any solvent present in the residue and recycles it to column 10 via conduit 32, condenser 38, and conduits 39 and 23.
ne remaining resiaual slurry is removea as an underfiow via conduit 33.
Referring now to Figure 3, the overflow from column 10 can be transferred (via conduit 21) to a single--stage solvent removal (recovery) unit, such as separation unit 34. Therein, the solvent is separated from the pre-mium oil and recycled to column 10 via conduit 23 while the extract is removed via conduit 37. The choice between unit 34 and the combination of units 22 and 26 is governed by the needs of the practitioner.
The recovered, high-solids content residual slurry is suitable as a gasification feedstock. The hydrogen:carbon ratio in this material is generally the same as or lower than that of li.~uefaction eed coal.
Thus, if this material is used as uel, the expenditure of hydrogen is minimi2ed. The premium oil is a desirable 18,394A-F
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recycle oil, a low-sulfur fuel or a feedstock for petro-chemicals. This material is generally recovered as a bot tom stream from a solvent distillation unit.
The process of this invention is particularly well adapted for the separation of a slurry produced by high temperature hydrogenation of coal into a first frac tion of premium oil and a second fraction of fine solids and polar liquids. The slurry differs from petroleum type materials i~ several important aspects.
First, the slurries of this invention typi-cally contain about 2 to 15 weight percent ash and about 8 percent unconverked organic solids.
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Second, the softening temperature of the resi-duai siurry c~nas co be ~vnsiu~ra~i~ higil~L tnall for pe~ro-leum-derived asphaltenes. Consequently, while propane `~ slurry separators (deasphalters) can operate at temperatures below 100C with a fluid residual product, the viscosity of the asphaltenic residue produced by this invention is typi-cally between 100,000 and 200,000 cps at 200C.
Third, the coal-derived liquids of this inven-tion tend to contain a larger fraction of solvent-insolu-ble oil, i.e., polar liquids.
Fourth, due ko the highly aromatic nature of ~he coal-derived oil and the large amounts of heteroatom--containiny organics, particularly phenolics, the differ-ence in interfacia]. tension bekween the premium oil and ~olvent tends to be greater for the coal-derived oil than for the petroleum-derived oils. This latter difference is believed to significantly effect the operation of the invention here described. The Marangoni eect is directly related to this interfacial tension difference.
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It is believed that the mechanism of extraction occurring in the process of this invention is a manifesta-tion of the Marangoni effect, a description of whlch fol-lows. When an oil containing a mixture of polar and non-polar species is contacted with a nonpolar solvent, inter-facial tension forces tend to cause the nonpolar species to concentrate at the oil surface. These nonpolar species are rapidly extracted by the nonpolar solvent, leaving a high concentration of polar species near the oil surface with a relati~ely high interfacial tension - a thermody-~amically unstable situation.
This thermodynamic driving force sets up circu-lation patterns in the oil phase which transfer nonpolar species rom the interior of -the oil phase to the inter-face where they are extracted. ~hese circulation patternscause rapid movement at the interface and extremely high ; mass transfer rates. The interfacial tension forces which drive the circulation patterns are opposed by the viscous effects in the oil phase. Consequently, high viscosity 2~ near the oil sur~ace will dampen the circulation patterns.
When the solvent-oil interface is generated by introducing oil into the solvent in the form of drops, e.g., from a small tube, the Maran~oni instability leads to a marked enhancement of the concomitant processes of ~5 dispersal and dissolution, i.e., to a rapid destruction of the droplet into numerous smaller droplets with an acco~panying extraction of the premium oil into the sol-~ent. Other studies have sho~n that when a viscous oil or polar solvents, like benzene or toluene, are used, the raRid rate o destruction does not occur. This Marangoni instability is believed to cccur under the operating con-ditions of the instant invention. As a consequence, the selection of solvent used in this invention preferably is such that the Marangoni effect is promoted. Solvents that 18,39~A-F
: ;
, - .
15~ 8~
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~do not promote this effect, such as benzene or toluene, literally extract all the liquid from the slurry thus pro-ducing powder for ultimate discharge as an underflow. As ~uch, polar liquids are not separated from the premium oil but are carried into the settling zone and removed as part of the overflow.
The Marangoni instability greatly enhances liquid-liquid extraction by providing large interfacial areas which thereby reduces the residence time required in the extraction zone. This in turn permits the use of e~uipment having smaller volume dimensions for a given volume of slurry and solvent and simplifies the design of the slurry inlet system, i.e., eliminates the need for closely controlling the initial droplet size of the slurry I5 previously necessary to obtain an extremely fine disper-sion of slurry into the solvent. Thus, the essence of this inven-tion lS the use of one o~ a specl~ic group of solvents in combination with a temperature differential `~ between various portions of the column wall to facilita-te the handling of the residue as a viscous liquid slurry.
Such a combination not only easily renders the operation of this invention, but it also promotes a desirable sepa-ration of the premium oil from the polar li~uids and ~ine solids.
The following examples illustrate this inven-tion. Unless otherwise noted, all parts and percentages are by weight.
~ .
~E~ ratus and Procedure ~ jacketed, vertical colu~m, 3 in. inner diam-; 30 eter and 54 in. long ~7.G~ cm x 1.37 m) having a design ~imilar to that described by Fiyure 1 was employed. The 18,394A-F
, ' ~16~ 6~
first and second zones were operated at a temperature of ~bout 160C and a pressure of about 200 psig (14.1 kg/cmZ) and the third zone was operated at a temperature of about 200C at a pressure of about 200 psig (14.1 kg/cm2). The pressure in the column was controlled by a back pressure ~ontroller and a valve on the heated ~150C) solvent-pre-mium oil outlet. This outlet fed into an adiabatic flash drum. There the solvent was flashed, removed and subse-guently condensed and recycled to a solvent feed tank.
Premium oil from the flash drum was stripped of any resi--dual solvent with a continuously fed distillation unit.
Residual slurry was removed from the column by a control valve. A level controller capable of detecting the interface between the residual slurry and solvent-15 -premium oil phases was used to control the asphaltene outlet valve.
~ exane was used as -the solvent and the column was fed various slurries at the rate of about 45 lb/hour (20.4 kg/hr). A hexane:slurry weight ratio of about 0.8:1 2Q was used.
Analytical Procedures In the following examples, the analytical pro-cedures employed were as follows:
.
Viscosity Viscosikies of product li~uids were measured at 25C using a Brookfield Viscometer. Ash was not removed from these li~uids prior to the measurement.
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Toluene Insolubles Product liquid (40 g) was shaken with toluene (160 g) and subsequently centrifuged. The supernatant li~uid was decanted and the remaining residue, toluene--insoluble hydrocarbons and ash, was vacuum-dried at 100C
and weighed. The ash content of the residue was deter-mined by ANSI/ASTM D482-74.
~ Asphaltenes ; Product liquid (25 g) was.shaken wi-th n-hexane ~ 10 (100 g) and subsequently centrifuged. The supernatant ; liquid was decanted and the residue (a mixture of ash, toluene insolubles, and toluene-soluble hydrocarbons which are insoluble in n-hexane, i.e., asphaltenes) was vacuum--dried at lOO~C and weighed. The asphaltene content was determined b~ s~lhtracti n~ t~ uene inso1llb1e~ and ash pre-; viously determined from the total hexane insolubles.
~ ' ' ~' .
i~ Coal Analysis , The coal used to generate the various lique-faction product liquids purified below was Pittsburg No. 8 Allison mine bituminous coal crushed, dried, pulverized and classified such that 99.9 percent would pass through a 120 mesh screen (U.S. Sieve Series). The sulfur content was about 3.9 percent.
Examples 1-3:
In Tables I-III are listed data from three operations employing different feed slurries, i.e., Table I-Hydrocyclone Underflow (12.6 percent ash), Table II-18,394A-F
, .
:, -18~ 6 -Liquefaction Product (5.2 percent ash) and Table III--Centrifuge Overhead (2.1 percent ash). ~eat of combus~
- tion (~Hc) was determined by ANSI/ASTM D2015-66 and Rams-bottom Carbon was determined by ANSI/ASTM D524-76.
IMPURITIES REMOVAL FROM A
HYDROCYCLONE UNDERFLOW SLURRY
Purified Product Asphal-10Feed Liquid tenes ~:
Amount, lb (kg) 51705 368.1 134.1 : (234~ (167)(60.8) Amount, wt % 100.0 73.3 26.7 ~:
Analyses: .
Viscosity, cps, 25C 320 60 Toluene Insolubles, % 9.8 0.84 Asphait~n~ 0 2i.2 18.6 : Ash, % 12.4 0.33 41.2 Carbon, wt % - ~ 48.9 Hydrogen, wt % - - 3.19 Sulfur, wt % - - 4.1 ~: Nitrogen Analysis, wt % - - 0.72 : ~Hc, BTU/lb (Kcal/g) - - 9,080 (2290) Ramsbottom Carbon, wt % - l1.l 72.7 . ' '.
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, 18,3g4A-F
.
-19~
TABLE II
IMPURITIES REMOVAL FROM A
LIQUEFACTION SLURRY
Purified Product Asphal-Feed Liquid tenes : Amount, lb (kg)4066 0 3219 07 863) Amount, wt % feed100.0 79.1717.67 Amount, wt % products - 81.76 18.24 Accountability = 96.8%
~nalyses 5C 632 . 152 ;: Toluene Insolubles, % 113.41729 93 : 15 Asphaltenes, % ~ 02 u i228.i4 Carbon, wt % - - 61 63 Hydrogen, wt % 2 94 Sul~u~, wt % - - 10,880 ~Hc, BTU/lb (Kcal/g) ~ ~ (2740) .
~ 18,394A~F
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~ABLE III
IMPURITI ES REMGVAL FROM A
CENTRI FUGE OVERFLOW SLURRYl Purified 5Product Asphal- :
Feed Liquid tenes :: Amount, wt % 100.0 88.311.7 Analyses:
~ Viscosity, cps, 25C 670 83 - 10 Toluene Insolubles, % 9.1 2.4 : Asphaltenes, % 36 29 Ash, % 1.9 0.0917.7 Carbon, wt % - - 72.0 Hydrogen, wt % - - 4.2 : 15 Sulfur, wt % - - 1.7 ~: Q~c' BTU/lb (Kcal/g) ~ ~13,200 ~3330) Ramsbottom Carbon, wt % - - 74 Represents average data based upon several runs made with this type of feed slurry. As a result, informa-tion on the total material fed and recovered and mater-ial balance accountability is not available.
.,' :' These data demonstrate, over a wide array of solid-containing slurries, the low residuum of ash in the purified product li~uid (overflow) and the low residuum of hexane-soluble hydrocarbon in the residual slurry.
Example 4:
~ series of experiments were conducted to determine the degree of solub.ili~y of coal~der.ived oil in pentane, hexane (a mixture of C6 paraf:~ins as con~
tained in commercial grade hexane solvents), cyclohexane, n-decane and toluene, .respectively. For each solven-~ the 18,394A F
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oil solubility was measured for a series of solvent to oil ratios. The oil solubility was determined by weigh-ing the appropriate amount of solvent and oil into an 8 ounce (224 g) bottle, shaking the bottle mechanically for at least 20 minutes to thoroughly m1x the two mater-ials, contrifuging the bottles contai:ning the mixture for at least 20 minutes to cause the insoluble phase to collect in the bottom of the bottle, decantin~ the liquids from the insoluble residue, vacuum-dryincJ the residue at about 80C, determining the residue weight and finally calculating the percent of the sample which was insoluble (% soluble oil = 100% - % insoluble). The results are reported in Table IV.
TABLE IV
% OF SAMPLE WHICH IS INSOLUBLE
Solvent Solvent Wt. Cyclo-Oil Wt. Pentane Hexane Hexane hexane Toluene 0.1 36.08 34.76 - - -: 20 0.2 28.03 26.37 - - -0.4 ~1.08 36.5419.8 25.8 9.~
0.8 44.4~ 39.9918.1 27.5 9.8 1.0 - 18.9 27.6 9.4 1.6 46.26 3g.26 3.2 43.21 36.71 ; 6.4 43.36 30.20 - - -Oil Sample A A B B B
18,394A~F
-2~
Oil Samples A and B are both samples of coal liquefaction products with initial boiling points of about 150C which had been centrifuged prior to this experimen-tation to remove all but a small frac-tion of the solids present (less than about 2-3 percent of sample is fil-terable solids).
Example 5:
~ series of experiments were performed as in Example 4 using hexane and decane as solvents. The oil used was the ash-rich fraction obtained by hydrocloning the 150C+ product slurry from the liquefaction o Pitts-burgh No. 8 coal. The results are reported in Table V.
TABLE V
% OF S~MPLE WHICH IS INSOLUBLE*
.
~ 15 Solvent Wt. Solvent ....
Oil Wt. Hexane Decane 0.1 19.79 21.14 0.3 .15.17 16.86 0.7 24.87 24.75 1.0 28.71 26.91 2.0 28.96 30.94 4.0 29.63 26.23 *Insolubles in the initial sample on an ash-free basis.
To assess the efEectiveness oE the solvent precipitation, the ash levels in the decanted liquids were determined for selected samples as shown below:
, l fl , 3 94A-F
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TABLE VI
~ ASH IN DECANTED SOLVENT AND OIL
Solvent Wt. Solvent Oil Wt. Hexane Decane 0.1 0.02 0.01 0.3 0.0 0.0 From the data presented in Tables IV-VI, several conclusions appear. First, while the amount of insoluble materials shows variations depending on the oil used and the solvent:oil ratio, and to a lesser degree on experi-mental uncertainty, there is a greater amount of insoluble maierial recovered for a given soiven~:oii ra~io a~la a given oil sample when pentane, hexane, cyclohexane or dec~
ane (all nonpolar solvents) is used thàn when the solvent ~; 15 is toluene (a polar solvent).
, .
Second, when the solvent is toluene, signifi-cantly less insoluble material is obtained due to the higher solubility of coal-derived oil in toluene than in paraffinic hydrocarbons.
Third, even at very low solvent:oil ratios the ash is very effectively removed from the soluble oil by the practice of this invention. Centrifugation of whole oil samples resul-ts in ash levels of 1-2 percent in the decanted oil.
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~24-Fourth, because of the increased solubility of the oil in hydrocarbon solvents at elevated temperatures, the operation of the deasphalter with an aromatic solvent such as toluene can be expected to result in little non-solid residue being separated as insoluble material. Resi-due obtained under these circumstances is not a viscous slurry but a powder wet with solvent. Problems with the removal oE such a residue prevented extended operation with toluene as a solvent. The xylenes, ethylbenzene and other mono aromatics would be expected to perform in a manner similar to toluene.
Example 6:
A room temperature study was conducted to observe the effect of solvent on the occurrence of Maran-goni instability. Hexane was placed in a glass vessel~iiled to a aep~n o~ a~out ~ incnes (~ cm). A coal--derived oil which contained about 0.1 percent ash, 1 percent toluene insolubles and 22 percent asphaltenes was used as the test sample. When this oil was added to the hexane dropwise from about 1 inch (2.54 cm) above the hexane li~uid surface rapid drop dispersion was observed. A photographic study of khe phenomena indi-; cated droplet dispersion began before the oil had pene-trated the hexane moxe than 1 inch. Secondary droplets whose diameters were less than 1/20th that of the ini-tial oil droplet were formed within one second and before the oil had penetrated the hexane more than 2 inches (5.1 cm). Simultaneously a clouding of the solvent in the vicinity indicated that extraction of a portion o:E the oil had occurred.
18,394A-F
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When the identical experimer.t was performed u~ing toluene in place of hexane as the solvent, no drop dispersion occurred. The oil drop settled through the ~olvent and rested on the bottom of the vessel with mini-~al extraction having occurred. The toluene solvent wasonly slightly discolored by the passage of the oil drop ~hrough it.
This data supports the importance of the Maran-goni effect in the rapid and effective ex-traction of the deasphalter ~eed slurry. The choice of solvenks which are less polar than mono aromatics, for example, C5-Cg paraf-~ins, is thus essential to obkain proper operation of the prozess.
EXample 7:
Using the apparatus and procedure of Examples 1-3, an extraction experiment was conducted in which coal--derived product oil with the below-described composition was processed. Oil feed rate was about 48.6 pounds (2.20 ~g) per hour and hexane feed rate was about 36.5 pounds (16.6 kg) per hour. Fox this experiment the column extrac-tion zone temperature was about 190C. The residue collec~
tion zone was hotter, i.e., the wa].l temperatures were 204C and 207C at the middle and bottom of the collection zone, respectively. The temperature in the center of the third zone was 195C. Operations under these conditions ; resulted in the by-passing of significant amounts of hex-ane and hexane-soluble oil through the residue outlet line.
About lS weight percent o~ the material in the residue col-lection vessel was a low viscosity hexane~-oil mixture ra~her than the desired viscous slurry. A sample of the 18,394A~F
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oil was analyzed after decanting a5 indicated below. A
hexane material balance indicated that much more than the usual amount of hPxane had escaped through the third zone outlet.
TABLE VII
~NALYSES
Feed Product Decanted Total Oil Oil Oil* Residue Viscosity @ 25C375 95 3000 ~sh % ~.14 0.002 14.22 30.54 % Toluene Insolubles 9.78 0.83 17.26 % Asphaltenes21.12 17.17 25.80 *Decanted from material in residue collection vessel.
:
Example 8:
As a continuation of the operation described in Example 7, the extraction process was kept in opera-tion while the temperature of the wall of the third zone was increased. After reaching steady state the following te~perature profile was recorded: Zone 2, 190C; wall 20 temperature at the middle and bottom of Zone 3, 225C and .
255C; temperature in the center of Zone 3, 212C. At these operating conditions no decantable oil was obser~ed in the residue collection zone. Product quality was as ~ollows:
.
18,394A-F
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TABLE VIII
ANALYSES
Feed Oil Product Oil Residue Viscosity @ 25C 375 62 5 Ash % 8.14 0.004 35.15 % Toluene Insolubles 9.78 0.88 : % Asphaltenes 21.12 17.08 . ~
A comparison of the data presented in Tables VII and VIII support the need for maintaining the wall temperature of the third zone at a temperature of about : 20C higher than the wall temperature of the rest of the column if a viscous residual slurry is to be recovered _ Jll ~ J.
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As here used, "column t~mperature", "zone tem perature", and similar terms mean the temperature of the column wall or that portion of the column wall defining a zone. The temperature of the slurry, solvent and sepa-ration products of the slurry may or may not obtain the same temperature of the column wall, depending upon the flow rate of these materials. Generally, the greater the flow rate, the less likely that these materials obtain the temperature of the column wall. Of course, the mater-ials obtain the heat of the column wall by conduction.
Although column pressure is generally uniform ~hroughout, column temperature generally varies from one area or zone of the column to another. Since the residual slurry is relatively high in solids and high molecular . 15 weight polar materials content, it is the most viscous and rec~ires the greater tem~erature. Thus, the zone wherein this slurry collects is typically run at least about 20C
higher than the remainder of the column.
~ ~ .
Although quantitative temperature and pressure ranges cannot be stated generically, by way of illustration and with hexane as the solvent, a typical minimum column tempe~ature (excluding the residual slurry collection zone) is at least about 100C and preferably about 140C. The corresponcling pressures are typically about 180 psi and 200 psi (12.7 and 14.1 kg/cm2). A typical maximum temper-ature is about 225C and preferably about 200C with cor-xesponding pressures of about 450 psi and about 325 psi (31.8 and 23.0 kg/cm2). Although the residual slurry col-lection zone temperatures are yenerally about 20C higher, respectively, wi-th comparable pressures, p.referably the r~sidual slurry collection zone is ma.intained at a temper-atuxe of at least about 150C and most preferably at about 180~C.
18,394A-F
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Premium oil extraction from the slurry is at least partially dependent upon the solven-t:slurry weight ratio fed to the vertical column. Generally the greater the solids content of the slurry, the greater the sol-vent:oil ratio used in the practice of this invention.
The use of a greater solvent:oil ratio under such circum-stances leaves a greater amount of polar liquids in the slurry and these polar liguids promote coalescence among the solids and thus fluidity of the underflow. A -typical minimum weight ratio of about 0.5:1 can be used although a ratio of about 0.6:1 is preferred. Practical considera-tions, such as energy efficiency, are the only limitations upon the maximum weight ratio although a maximum weight ratio of about 5:1, and preferably about 1:1, is typical.
A weight ratio of about 0.8:1 is especially preferred.
Generally, if the weight ratio is less than 0.5, i.e., less than 0.5:1, the recovered asphaltene has a reduced viscositY wnich indicates Poor seParation from tne prod-uct liquid. Moreover, detection of an interface between the residual slurry and the solvent-slurry phases becomes - difficult ,and the more difficult this becomes, the more dificult is the selective removal of the residual slurry from the vertical column. If the weight ratio is greater than about 1.0, feed slurry throughput (volume per unit time) is sacrificed and additional cost and utilities are incurred.
;
Although the physical features (housing and channel size and shape) of the vertical column here used can be varied to choice, the column is typically a hol-low, elongated cylinder or pipe-like structure with a length over diameter (LOD) guotient between about 40 and 2 and preerably between about 20 and 5. The colurnn can be made from any suitable material but materials, such as ~teel, known to perform well under elevated temperatures , ~8,394A~F
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-and pressures are preferred. The column generally com-prises three zones: a first or settling zone, a second or contacting zone, and a third or collection zone.
~he first or settling zone is generally the top portion of the column, equipped with a solvent-pre-mium oil extract outlet, and commences abo~e an entry port used for introducing th~ slurry into the second or contacting zone. This first or settling zone collects the solvent and premium oil flowing up from the second or contacting zone for its ultimate removal from the column. The function of this settling zone is to pro-vide an area for the gravity separation of any fine solids that may have been carried from the contacting zone by the ~olvent and premium oil. As such, it is desirable that 1~ the solvent and premium oil be quiescent, i.e., have little ~ or no convection currents, to encourage any fine solids to - - settle ~ack lnto the contacting zone. On large scales, ~ertical baff-es or other design features may be useful in -preventing such co~vection currents and resulting fine solids presence in the column overflow.
The second or contacting zone is generally the mid-portion, i.e., the portion between the first and third zones, of ~he column and it generally is the largest (on an overall length basis) portion of the column. Within this zone, the slurry descends the column in a partially back-mixed, partially countercurrent mode. Although the solvent-premium oil phase is nearly completely back-mixed in this second zone (due to both the density difference between the premium oil and solvent and to convection cur-rents), there is a net countercurrent flow of the residualslurr~ downward against the upflow of the solvent-premium oil phase. This second zone is equipped with a slurry entry port at or near its top and a solvent entry port at ~8,394A-F
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or near its bottom. Use of internals within this zone may be useful, especially in large-scale operations, to disrupt convection currents. Any such internals should -~e designed to avoid the buildup of asphaltenic residue with exposed surfaces generally no more than 30 degrees off the vertical axis of the column.
The third or collection zone is generally the bottom portion of the column and typically has an enlarged ; diameter relative to the first and second zones. This æone collects ~he residual slurry, i.e., fine solids and other materials comprising the slurry not soluble in the nonpolar solvent, for their ultimate removal from the column. The column wall defining this zone is generally ; maintained at a higher temperature than the wall defining 1~ the second zone because the residual slurry which is col--~; lected in the third zo~e has a greater viscosity than , eit~er the slurry, premium oil or solvent and thus requires a higher temperature to maintain its liquid state. Since the third zone, like the first and second zones, is gen-erally operated on a continuous basis, the temperature dif-ferential exhibited between the wall defining the third zone and the wall defining the second zone is not believed paralleled by a similar temperature differential between the contents o~ the second zone and the contents o the third zone. Howevex, it is believed that the higher tem-perature of the wall defining the third zone inhibits accumulation of the solids-containing residual phase along the interior of the wall and thus promotes a steady ~- and uninterrupted discharge of the residual slurry.
., .
The third zone is also equipped with a resi-dual slurry outlet which can be located at any convenient poin-t about the zone but is p~eferabl~ located at the .
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~: , . , . , ' center of the bottom of the ~one. This avoids solvent and premium oil escaping due to their bypassing the resi dual slurry. The residual slurry outlet can be equipped with any conventional means for facilitating the removal of the residual slurry from the zone, such as a valve, worm screw, or extruder.
In the accompanying drawings in which like numerals are employed to desi~nate like parts through-out the same:
Figure 1 is a preferred, specific embodirnent of a vertical column;
Figure 2 is a schematic flow diagram illus-trating the vertical column of Figure 1 in a specific combination with conventional, downstream separation 1~ equipment, and F~gure 3 is a schematic flow diagram illus-~rati~g a variation of the combination shown in Figure Z.
' ~; Various items of equipment, such as valves, ; fittings, condensers, pumps, etc. have been omitted so as to simplify the description. However, those sk1lled in the ar-t will realize that such conventional e~uip-ment can be, and is, employed as desired.
In Figure 1, a vertical column 10 consists of a first or settling zone 11, a second or contacting zone 12, and a third or collection zone 13. Zone 11 is equipped with a solvent-premium oil outle-t 14 and a thermal jacket lla. Zone 12 is equipped with a slurry inlet 16, a sol~
vent inlet 17 and a thermal jacket 12a. Zone 13 i'a ~quipped with a residual slurr~l outLet 19 and a thermal jacket 13a.
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In Figure 2, column 10 is connected to an adi~
abatic flash drum 22 by conduits 21 and 23. A distilla-tion unit 26 equipped with a removal conduit 28 is joined both to flash 22 by conduit 24 and to column lO by con- ~:~
duits 27 and 23. Conduits 27 and 23 are mated with each other. A separator 31 is connected to column 10 by con-duit 29. A conduit 33 proceeds from separator 31 and a conduit 32 joins separator 31 with a condenser 38 which in turn is joined to column 10 by mated conduits 39 and 10 23~
In Figure 3, a separation unit 34 replaces the adiabatic flash drum 22 and distillation unit 26 of Figure 2. Unit 34 is connected -to column 10 by con- :
duits 21 and 23 and is e~uipped with a removal conduit 37. Column 10 is e~uipped with removal conduit 29.
Having thus de-scribed the apparatus and refer-ring now to Figure 1, a slurry is continuously charged to ~^~ column 10 through slurry inlet 16 while a nonpolar solvent `, i5 simultaneously and continuously charged to column 10 ~' 20 through solvent inlet 17. The solvent passes up and ~hrough zone 12 while the slurry simultaneously passes down and through the same. During this continuous, simul-; taneous passing, the solvent and slurry are in intimate contact and the solvent extracts from the slurry the pre-25 mium oil which is soluble in the solvent at the ~one 12 conditions, thus producing a first fraction comprising the solvert and premium oil and a second fraction (resi~
dual slurry) comprising the fine solids and polar li~uids.
The solvent and premium oil are continuously transported 30 into zone 11 and removed therefrom through outlet 14. ~he resldual slurry is continuously collected in zone 13 and removed therefrom through residual slurry outLet 19.
.
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Referring now to Figure 2, the solvent-premium oil mixture present in zone 11 of column 10 in the form of a substantially quiescent pool is removed as an overflow ~nd is passed through conduit 21 to flash drum 22 where some of the solvent is separated from the premium oil and recycled to column 10 via conduit 23. The remaining sol-vent~premium oil mixture is transferred to distillation unit 26 where the remaining solvent is distilled overhead and recycled to column 10 via conduits 27 and 23 while the premium oil is removed as an underflow through removal out-~; let 28.
The residual slurry collected in zone 13 ofcolumn 10 is removed as an underflow and is passed to separator 31 via conduit 29. Separator 31 recovers any solvent present in the residue and recycles it to column 10 via conduit 32, condenser 38, and conduits 39 and 23.
ne remaining resiaual slurry is removea as an underfiow via conduit 33.
Referring now to Figure 3, the overflow from column 10 can be transferred (via conduit 21) to a single--stage solvent removal (recovery) unit, such as separation unit 34. Therein, the solvent is separated from the pre-mium oil and recycled to column 10 via conduit 23 while the extract is removed via conduit 37. The choice between unit 34 and the combination of units 22 and 26 is governed by the needs of the practitioner.
The recovered, high-solids content residual slurry is suitable as a gasification feedstock. The hydrogen:carbon ratio in this material is generally the same as or lower than that of li.~uefaction eed coal.
Thus, if this material is used as uel, the expenditure of hydrogen is minimi2ed. The premium oil is a desirable 18,394A-F
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recycle oil, a low-sulfur fuel or a feedstock for petro-chemicals. This material is generally recovered as a bot tom stream from a solvent distillation unit.
The process of this invention is particularly well adapted for the separation of a slurry produced by high temperature hydrogenation of coal into a first frac tion of premium oil and a second fraction of fine solids and polar liquids. The slurry differs from petroleum type materials i~ several important aspects.
First, the slurries of this invention typi-cally contain about 2 to 15 weight percent ash and about 8 percent unconverked organic solids.
.
Second, the softening temperature of the resi-duai siurry c~nas co be ~vnsiu~ra~i~ higil~L tnall for pe~ro-leum-derived asphaltenes. Consequently, while propane `~ slurry separators (deasphalters) can operate at temperatures below 100C with a fluid residual product, the viscosity of the asphaltenic residue produced by this invention is typi-cally between 100,000 and 200,000 cps at 200C.
Third, the coal-derived liquids of this inven-tion tend to contain a larger fraction of solvent-insolu-ble oil, i.e., polar liquids.
Fourth, due ko the highly aromatic nature of ~he coal-derived oil and the large amounts of heteroatom--containiny organics, particularly phenolics, the differ-ence in interfacia]. tension bekween the premium oil and ~olvent tends to be greater for the coal-derived oil than for the petroleum-derived oils. This latter difference is believed to significantly effect the operation of the invention here described. The Marangoni eect is directly related to this interfacial tension difference.
18,394A-F
14~
,~ .
It is believed that the mechanism of extraction occurring in the process of this invention is a manifesta-tion of the Marangoni effect, a description of whlch fol-lows. When an oil containing a mixture of polar and non-polar species is contacted with a nonpolar solvent, inter-facial tension forces tend to cause the nonpolar species to concentrate at the oil surface. These nonpolar species are rapidly extracted by the nonpolar solvent, leaving a high concentration of polar species near the oil surface with a relati~ely high interfacial tension - a thermody-~amically unstable situation.
This thermodynamic driving force sets up circu-lation patterns in the oil phase which transfer nonpolar species rom the interior of -the oil phase to the inter-face where they are extracted. ~hese circulation patternscause rapid movement at the interface and extremely high ; mass transfer rates. The interfacial tension forces which drive the circulation patterns are opposed by the viscous effects in the oil phase. Consequently, high viscosity 2~ near the oil sur~ace will dampen the circulation patterns.
When the solvent-oil interface is generated by introducing oil into the solvent in the form of drops, e.g., from a small tube, the Maran~oni instability leads to a marked enhancement of the concomitant processes of ~5 dispersal and dissolution, i.e., to a rapid destruction of the droplet into numerous smaller droplets with an acco~panying extraction of the premium oil into the sol-~ent. Other studies have sho~n that when a viscous oil or polar solvents, like benzene or toluene, are used, the raRid rate o destruction does not occur. This Marangoni instability is believed to cccur under the operating con-ditions of the instant invention. As a consequence, the selection of solvent used in this invention preferably is such that the Marangoni effect is promoted. Solvents that 18,39~A-F
: ;
, - .
15~ 8~
..
~do not promote this effect, such as benzene or toluene, literally extract all the liquid from the slurry thus pro-ducing powder for ultimate discharge as an underflow. As ~uch, polar liquids are not separated from the premium oil but are carried into the settling zone and removed as part of the overflow.
The Marangoni instability greatly enhances liquid-liquid extraction by providing large interfacial areas which thereby reduces the residence time required in the extraction zone. This in turn permits the use of e~uipment having smaller volume dimensions for a given volume of slurry and solvent and simplifies the design of the slurry inlet system, i.e., eliminates the need for closely controlling the initial droplet size of the slurry I5 previously necessary to obtain an extremely fine disper-sion of slurry into the solvent. Thus, the essence of this inven-tion lS the use of one o~ a specl~ic group of solvents in combination with a temperature differential `~ between various portions of the column wall to facilita-te the handling of the residue as a viscous liquid slurry.
Such a combination not only easily renders the operation of this invention, but it also promotes a desirable sepa-ration of the premium oil from the polar li~uids and ~ine solids.
The following examples illustrate this inven-tion. Unless otherwise noted, all parts and percentages are by weight.
~ .
~E~ ratus and Procedure ~ jacketed, vertical colu~m, 3 in. inner diam-; 30 eter and 54 in. long ~7.G~ cm x 1.37 m) having a design ~imilar to that described by Fiyure 1 was employed. The 18,394A-F
, ' ~16~ 6~
first and second zones were operated at a temperature of ~bout 160C and a pressure of about 200 psig (14.1 kg/cmZ) and the third zone was operated at a temperature of about 200C at a pressure of about 200 psig (14.1 kg/cm2). The pressure in the column was controlled by a back pressure ~ontroller and a valve on the heated ~150C) solvent-pre-mium oil outlet. This outlet fed into an adiabatic flash drum. There the solvent was flashed, removed and subse-guently condensed and recycled to a solvent feed tank.
Premium oil from the flash drum was stripped of any resi--dual solvent with a continuously fed distillation unit.
Residual slurry was removed from the column by a control valve. A level controller capable of detecting the interface between the residual slurry and solvent-15 -premium oil phases was used to control the asphaltene outlet valve.
~ exane was used as -the solvent and the column was fed various slurries at the rate of about 45 lb/hour (20.4 kg/hr). A hexane:slurry weight ratio of about 0.8:1 2Q was used.
Analytical Procedures In the following examples, the analytical pro-cedures employed were as follows:
.
Viscosity Viscosikies of product li~uids were measured at 25C using a Brookfield Viscometer. Ash was not removed from these li~uids prior to the measurement.
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.
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Toluene Insolubles Product liquid (40 g) was shaken with toluene (160 g) and subsequently centrifuged. The supernatant li~uid was decanted and the remaining residue, toluene--insoluble hydrocarbons and ash, was vacuum-dried at 100C
and weighed. The ash content of the residue was deter-mined by ANSI/ASTM D482-74.
~ Asphaltenes ; Product liquid (25 g) was.shaken wi-th n-hexane ~ 10 (100 g) and subsequently centrifuged. The supernatant ; liquid was decanted and the residue (a mixture of ash, toluene insolubles, and toluene-soluble hydrocarbons which are insoluble in n-hexane, i.e., asphaltenes) was vacuum--dried at lOO~C and weighed. The asphaltene content was determined b~ s~lhtracti n~ t~ uene inso1llb1e~ and ash pre-; viously determined from the total hexane insolubles.
~ ' ' ~' .
i~ Coal Analysis , The coal used to generate the various lique-faction product liquids purified below was Pittsburg No. 8 Allison mine bituminous coal crushed, dried, pulverized and classified such that 99.9 percent would pass through a 120 mesh screen (U.S. Sieve Series). The sulfur content was about 3.9 percent.
Examples 1-3:
In Tables I-III are listed data from three operations employing different feed slurries, i.e., Table I-Hydrocyclone Underflow (12.6 percent ash), Table II-18,394A-F
, .
:, -18~ 6 -Liquefaction Product (5.2 percent ash) and Table III--Centrifuge Overhead (2.1 percent ash). ~eat of combus~
- tion (~Hc) was determined by ANSI/ASTM D2015-66 and Rams-bottom Carbon was determined by ANSI/ASTM D524-76.
IMPURITIES REMOVAL FROM A
HYDROCYCLONE UNDERFLOW SLURRY
Purified Product Asphal-10Feed Liquid tenes ~:
Amount, lb (kg) 51705 368.1 134.1 : (234~ (167)(60.8) Amount, wt % 100.0 73.3 26.7 ~:
Analyses: .
Viscosity, cps, 25C 320 60 Toluene Insolubles, % 9.8 0.84 Asphait~n~ 0 2i.2 18.6 : Ash, % 12.4 0.33 41.2 Carbon, wt % - ~ 48.9 Hydrogen, wt % - - 3.19 Sulfur, wt % - - 4.1 ~: Nitrogen Analysis, wt % - - 0.72 : ~Hc, BTU/lb (Kcal/g) - - 9,080 (2290) Ramsbottom Carbon, wt % - l1.l 72.7 . ' '.
..'~
, 18,3g4A-F
.
-19~
TABLE II
IMPURITIES REMOVAL FROM A
LIQUEFACTION SLURRY
Purified Product Asphal-Feed Liquid tenes : Amount, lb (kg)4066 0 3219 07 863) Amount, wt % feed100.0 79.1717.67 Amount, wt % products - 81.76 18.24 Accountability = 96.8%
~nalyses 5C 632 . 152 ;: Toluene Insolubles, % 113.41729 93 : 15 Asphaltenes, % ~ 02 u i228.i4 Carbon, wt % - - 61 63 Hydrogen, wt % 2 94 Sul~u~, wt % - - 10,880 ~Hc, BTU/lb (Kcal/g) ~ ~ (2740) .
~ 18,394A~F
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.
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~ABLE III
IMPURITI ES REMGVAL FROM A
CENTRI FUGE OVERFLOW SLURRYl Purified 5Product Asphal- :
Feed Liquid tenes :: Amount, wt % 100.0 88.311.7 Analyses:
~ Viscosity, cps, 25C 670 83 - 10 Toluene Insolubles, % 9.1 2.4 : Asphaltenes, % 36 29 Ash, % 1.9 0.0917.7 Carbon, wt % - - 72.0 Hydrogen, wt % - - 4.2 : 15 Sulfur, wt % - - 1.7 ~: Q~c' BTU/lb (Kcal/g) ~ ~13,200 ~3330) Ramsbottom Carbon, wt % - - 74 Represents average data based upon several runs made with this type of feed slurry. As a result, informa-tion on the total material fed and recovered and mater-ial balance accountability is not available.
.,' :' These data demonstrate, over a wide array of solid-containing slurries, the low residuum of ash in the purified product li~uid (overflow) and the low residuum of hexane-soluble hydrocarbon in the residual slurry.
Example 4:
~ series of experiments were conducted to determine the degree of solub.ili~y of coal~der.ived oil in pentane, hexane (a mixture of C6 paraf:~ins as con~
tained in commercial grade hexane solvents), cyclohexane, n-decane and toluene, .respectively. For each solven-~ the 18,394A F
-....
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oil solubility was measured for a series of solvent to oil ratios. The oil solubility was determined by weigh-ing the appropriate amount of solvent and oil into an 8 ounce (224 g) bottle, shaking the bottle mechanically for at least 20 minutes to thoroughly m1x the two mater-ials, contrifuging the bottles contai:ning the mixture for at least 20 minutes to cause the insoluble phase to collect in the bottom of the bottle, decantin~ the liquids from the insoluble residue, vacuum-dryincJ the residue at about 80C, determining the residue weight and finally calculating the percent of the sample which was insoluble (% soluble oil = 100% - % insoluble). The results are reported in Table IV.
TABLE IV
% OF SAMPLE WHICH IS INSOLUBLE
Solvent Solvent Wt. Cyclo-Oil Wt. Pentane Hexane Hexane hexane Toluene 0.1 36.08 34.76 - - -: 20 0.2 28.03 26.37 - - -0.4 ~1.08 36.5419.8 25.8 9.~
0.8 44.4~ 39.9918.1 27.5 9.8 1.0 - 18.9 27.6 9.4 1.6 46.26 3g.26 3.2 43.21 36.71 ; 6.4 43.36 30.20 - - -Oil Sample A A B B B
18,394A~F
-2~
Oil Samples A and B are both samples of coal liquefaction products with initial boiling points of about 150C which had been centrifuged prior to this experimen-tation to remove all but a small frac-tion of the solids present (less than about 2-3 percent of sample is fil-terable solids).
Example 5:
~ series of experiments were performed as in Example 4 using hexane and decane as solvents. The oil used was the ash-rich fraction obtained by hydrocloning the 150C+ product slurry from the liquefaction o Pitts-burgh No. 8 coal. The results are reported in Table V.
TABLE V
% OF S~MPLE WHICH IS INSOLUBLE*
.
~ 15 Solvent Wt. Solvent ....
Oil Wt. Hexane Decane 0.1 19.79 21.14 0.3 .15.17 16.86 0.7 24.87 24.75 1.0 28.71 26.91 2.0 28.96 30.94 4.0 29.63 26.23 *Insolubles in the initial sample on an ash-free basis.
To assess the efEectiveness oE the solvent precipitation, the ash levels in the decanted liquids were determined for selected samples as shown below:
, l fl , 3 94A-F
i, :., 23- ~ ~%
TABLE VI
~ ASH IN DECANTED SOLVENT AND OIL
Solvent Wt. Solvent Oil Wt. Hexane Decane 0.1 0.02 0.01 0.3 0.0 0.0 From the data presented in Tables IV-VI, several conclusions appear. First, while the amount of insoluble materials shows variations depending on the oil used and the solvent:oil ratio, and to a lesser degree on experi-mental uncertainty, there is a greater amount of insoluble maierial recovered for a given soiven~:oii ra~io a~la a given oil sample when pentane, hexane, cyclohexane or dec~
ane (all nonpolar solvents) is used thàn when the solvent ~; 15 is toluene (a polar solvent).
, .
Second, when the solvent is toluene, signifi-cantly less insoluble material is obtained due to the higher solubility of coal-derived oil in toluene than in paraffinic hydrocarbons.
Third, even at very low solvent:oil ratios the ash is very effectively removed from the soluble oil by the practice of this invention. Centrifugation of whole oil samples resul-ts in ash levels of 1-2 percent in the decanted oil.
18,394A-F
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.
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~24-Fourth, because of the increased solubility of the oil in hydrocarbon solvents at elevated temperatures, the operation of the deasphalter with an aromatic solvent such as toluene can be expected to result in little non-solid residue being separated as insoluble material. Resi-due obtained under these circumstances is not a viscous slurry but a powder wet with solvent. Problems with the removal oE such a residue prevented extended operation with toluene as a solvent. The xylenes, ethylbenzene and other mono aromatics would be expected to perform in a manner similar to toluene.
Example 6:
A room temperature study was conducted to observe the effect of solvent on the occurrence of Maran-goni instability. Hexane was placed in a glass vessel~iiled to a aep~n o~ a~out ~ incnes (~ cm). A coal--derived oil which contained about 0.1 percent ash, 1 percent toluene insolubles and 22 percent asphaltenes was used as the test sample. When this oil was added to the hexane dropwise from about 1 inch (2.54 cm) above the hexane li~uid surface rapid drop dispersion was observed. A photographic study of khe phenomena indi-; cated droplet dispersion began before the oil had pene-trated the hexane moxe than 1 inch. Secondary droplets whose diameters were less than 1/20th that of the ini-tial oil droplet were formed within one second and before the oil had penetrated the hexane more than 2 inches (5.1 cm). Simultaneously a clouding of the solvent in the vicinity indicated that extraction of a portion o:E the oil had occurred.
18,394A-F
-: - - . ., : .
- , :
: : , ' - ,, .. ' ' ' ' :
-25~ &i~
When the identical experimer.t was performed u~ing toluene in place of hexane as the solvent, no drop dispersion occurred. The oil drop settled through the ~olvent and rested on the bottom of the vessel with mini-~al extraction having occurred. The toluene solvent wasonly slightly discolored by the passage of the oil drop ~hrough it.
This data supports the importance of the Maran-goni effect in the rapid and effective ex-traction of the deasphalter ~eed slurry. The choice of solvenks which are less polar than mono aromatics, for example, C5-Cg paraf-~ins, is thus essential to obkain proper operation of the prozess.
EXample 7:
Using the apparatus and procedure of Examples 1-3, an extraction experiment was conducted in which coal--derived product oil with the below-described composition was processed. Oil feed rate was about 48.6 pounds (2.20 ~g) per hour and hexane feed rate was about 36.5 pounds (16.6 kg) per hour. Fox this experiment the column extrac-tion zone temperature was about 190C. The residue collec~
tion zone was hotter, i.e., the wa].l temperatures were 204C and 207C at the middle and bottom of the collection zone, respectively. The temperature in the center of the third zone was 195C. Operations under these conditions ; resulted in the by-passing of significant amounts of hex-ane and hexane-soluble oil through the residue outlet line.
About lS weight percent o~ the material in the residue col-lection vessel was a low viscosity hexane~-oil mixture ra~her than the desired viscous slurry. A sample of the 18,394A~F
.. ; ' , ' , ~ . ', ' . .
. .
oil was analyzed after decanting a5 indicated below. A
hexane material balance indicated that much more than the usual amount of hPxane had escaped through the third zone outlet.
TABLE VII
~NALYSES
Feed Product Decanted Total Oil Oil Oil* Residue Viscosity @ 25C375 95 3000 ~sh % ~.14 0.002 14.22 30.54 % Toluene Insolubles 9.78 0.83 17.26 % Asphaltenes21.12 17.17 25.80 *Decanted from material in residue collection vessel.
:
Example 8:
As a continuation of the operation described in Example 7, the extraction process was kept in opera-tion while the temperature of the wall of the third zone was increased. After reaching steady state the following te~perature profile was recorded: Zone 2, 190C; wall 20 temperature at the middle and bottom of Zone 3, 225C and .
255C; temperature in the center of Zone 3, 212C. At these operating conditions no decantable oil was obser~ed in the residue collection zone. Product quality was as ~ollows:
.
18,394A-F
-27~
TABLE VIII
ANALYSES
Feed Oil Product Oil Residue Viscosity @ 25C 375 62 5 Ash % 8.14 0.004 35.15 % Toluene Insolubles 9.78 0.88 : % Asphaltenes 21.12 17.08 . ~
A comparison of the data presented in Tables VII and VIII support the need for maintaining the wall temperature of the third zone at a temperature of about : 20C higher than the wall temperature of the rest of the column if a viscous residual slurry is to be recovered _ Jll ~ J.
~: .
' , ~ , , . . .
: 18,394A-F
, , '.: ~ , :~ "
`
Claims (7)
1. An improved process for separating a feed slurry produced by high temperature hydrogenation of a solid, hydrocarbonaceous fuel and comprising fine solids, polar liquids and premium liquid oil, into a first frac-tion comprising the premium liquid oil and a second frac-tion comprising the fine solids and polar liquids, charac-terized by (a) mixing the feed slurry with a nonpolar liquid solvent which is a C5-C9 alipharic ox alicy-clic hydrocarbon or a naphthenic or paraffinic frac-tion of a coal liquefaction product containing less than 10 weight percent aromatic compounds, the mixing being conducted in a vertical column comprising a settling zone, a contacting zone and a collection zone, the settling and contacting zones operated at a temperature between 100°C and 250°C and at a pres-sure sufficient to maintain both the slurry and sol-vent in a liquid state but less than 450 psi (317 kg/cm2), the slurry being introduced into the column at or near the top of the contacting zone and the solvent being introduced into the column at or near the bottom of the contacting zone, the solvent and slurry being mixed in a weight ratio of at least 0.5:1 and contacted in such a manner that the sol-vent:
18,394A-F
(1) passes up and through the column while the slurry passes down and through the column;
(2) is in intimate contact with the slurry as the solvent and slurry simultaneously pass through the column; and (3) extracts from the slurry, as the sol-vent and slurry simultaneously pass through the column, the premium liquid oil;
(b) recovering from the settling zone of the column as an overflow the first fraction; and (c) recovering from the collection zone of the column as a viscous slurry underflow, the second fraction.
18,394A-F
(1) passes up and through the column while the slurry passes down and through the column;
(2) is in intimate contact with the slurry as the solvent and slurry simultaneously pass through the column; and (3) extracts from the slurry, as the sol-vent and slurry simultaneously pass through the column, the premium liquid oil;
(b) recovering from the settling zone of the column as an overflow the first fraction; and (c) recovering from the collection zone of the column as a viscous slurry underflow, the second fraction.
2. The process of Claim 1 wherein the slurry is produced from the liquefaction of coal.
3. The process of Claim 2 wherein the sol-vent:slurry weight ratio is between 0.6:1 and 5:1.
4. The process of Claim 3 wherein the solids content of the feed slurry is less than 25 weight percent of the slurry.
5. The process of Claim 4 wherein the under-flow comprises less than 65 weight percent solids.
6. The process of Claim 5 wherein the liquid solvent is at least one C5-C9 aliphatic or alicyclic hydro-carbon.
18,394A-F
18,394A-F
7. The process of Claim 6 wherein the tem-perature of that portion of the column wall defining the collection zone is at least 150°C.
18,394A-F
18,394A-F
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA331,941A CA1126186A (en) | 1979-07-17 | 1979-07-17 | Process for recovering a premium oil from a slurry produced by high temperature hydrogenation of a solid, hycrocarbonaceous fuel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA331,941A CA1126186A (en) | 1979-07-17 | 1979-07-17 | Process for recovering a premium oil from a slurry produced by high temperature hydrogenation of a solid, hycrocarbonaceous fuel |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1126186A true CA1126186A (en) | 1982-06-22 |
Family
ID=4114700
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA331,941A Expired CA1126186A (en) | 1979-07-17 | 1979-07-17 | Process for recovering a premium oil from a slurry produced by high temperature hydrogenation of a solid, hycrocarbonaceous fuel |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1126186A (en) |
-
1979
- 1979-07-17 CA CA331,941A patent/CA1126186A/en not_active Expired
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