US3856675A

US3856675A - Coal liquefaction

Info

Publication number: US3856675A
Application number: US00304319A
Authority: US
Inventors: M Sze; G Snell
Original assignee: Lummus Co
Current assignee: Lummus Technology LLC
Priority date: 1972-11-07
Filing date: 1972-11-07
Publication date: 1974-12-24
Anticipated expiration: 1991-12-24
Also published as: DE2355606A1; NL174064C; JPS4997802A; LU68727A1; GB1452297A; DE2355606C2; BE806789A; ZA738417B; CA1004618A; JPS521922B2; NL174064B; IT996915B; NL7315260A; AU6214873A; FR2205564A1; AU469767B2; FR2205564B1; CS186778B2

Abstract

Insoluble material is separated from a coal liquefaction product by use of a promoter liquid having a 5 volume percent distillation temperature of at least 250* F., most preferably at least 400* F. and a 95 volume percent distillation temperature of at least 350* F. and no greater than about 750* F. The liquid has a characterization factor of at least 9.75. By use of the promoter liquid, insoluble material can be effectively separated from the coal product by a gravity settling technique. A preferred gravity settling apparatus is also disclosed.

Description

United States Patent Sze et al. Dec. 24, 1974 COAL LIQUEFACTION 3,791,956 2/1974 Gorin et al 208/8 M l [75] Inventors gg f zf z g g g 1: J Primary Examiner-Charles N. Hart Assistant ExaminerRobert G. Mukai [73] Assignee: The Lummus Company, Bloomfield, Attorney, Agent, or Firm-Mam &.Jangarathis 22 Filed: Nov. 7, 1972 [571 1 ABSTRACT I l f Insoluble materia is separated from a coa ique ac [211 Appl' 304519 tion product by use of a promoter liquid having a volume percent distillation temperature of at least 52 U.S. c1 210/73, 208/8, 208/ 2 most preferably at least and a [51] Int. Cl Cl0g l/00 lime percent i l i n mper ure f at leas 350 [58] Field of Search 208/8, 10, 210/73, R and g r than abOllt The liqui as 21 210/33, 202 characterization factor of at least 9.75. By use of the promoter liquid, insoluble material can be effectively [56] References Cit d separated from the coal product by a gravity settling UNITED STATES PATENTS technique. A preferred gravity settling apparatus is 3,519,553 7/1970 Johanson et al. 208/10 also dlsclosed' 3,687,837 8/1972 Fiocco et al. 208/8 31 Claims, 2 Drawing Figures 26 \lMake Up 1 To 550 F (425500Fl 2/ 1 23 25 l /3 l 24 J a 0 Cool slurrying H\ Liq zefaggtlon Separation I V sesglc i ildn Recovery m 6y00 -900 F /0 2 /5 /7 22 1" 900F+ l Stripping 1 COAL LIQUEFACTION This invention relates to the liquefaction of coal, and more particularly to the de-ashing of a coal liquefaction product.

Coal can be converted to valuable products by sub jecting coal to solvent extraction, with or without hydrogen, to produce a mixture of coal extract and undissolved coal residue, including undissolved extractable carbonaceous matter, fusain and mineral matter or ash.

The finely divided mineral matter or ash and unreacted coal must be separated from the coal extract, and in general, this separation step has been the principal drawback to the successful operation of a coal extrac tion process. The fine particle sizes encountered in coal solvation processes create numerous difficulties in attempting to use conventional separation techniques, such as filtration, centrifugation or settling. Attempts to use filtration techniques have not been particularly successful as a result of plugging of the filter pores with or without a precoat and the expense involved in providing the required filtration area.

Gravity settling techniques have also met with limited success as a result of low settling rates and inefficient ash removal. Centrifugation techniques have also been generally unsuccessful as a result of high cost and the difficulty in separating the lighter finely divided materials.

Accordingly, there is a need for an effective process for separating finely divided insoluble material from a coal liquefaction product.

An object of the present invention is to provide for improved coal liquefaction.

Another object of the present invention is to provide a new and improved process for separating finely divided insoluble material from a coal liquefaction product.

A further object of the present invention is to provide a process for separating insoluble material from a coal liquefaction product which does not require a filtration step.

Still another object of the present invention is to provide an improved gravity settler for coal deashing.

These and other objects of the present invention should be more readily apparent from reading the following detailed description thereof with reference to the accompanying drawing wherein:

FIG. 1 is a simplified schematic flow diagram of a coal liquefaction process incorporating the teachings of the present invention; and

FIG. 2 illustrates a preferred embodiment of a gravity settler for coal deashing.

The objects of the present invention are broadly accomplished, in one aspect, by use of a liquid which promotes and enhances the separation of insoluble material from a coal liquefaction product. More particularly, the coal liquefaction product, comprised of a liquid coal extract of dissolved carbonaceous matter in a coal liquefaction solvent and insoluble material (ash and unreacted coal) is mixed with a liquid promoter having an aromaticity less than that of the liquefaction solvent to enhance and promote the separation of insoluble material and provide a liquid coal extract essentially free of insoluble material.

The liquid which is employed to enhance and promote the separation of insoluble material from the coal liquefaction product is generally a hydrocarbon liquid wherein T is the molal average boiling point of the liquid R); and G is specific gravity of the liquid (60 F/60 F).

The characterization factor is an index of the aromaticity/parafinicity of hydrocarbons and petroleum fractions as disclosed by Watson & Nelson Ind. Eng. Chem. 25 880 (I933), with more parafinic materials having higher values for the characterization factor (K). The promoter liquid which is employed is one which has a characterization factor (K) in excess of 9.75 andwhich is also less aromatic than the liquefac tion solvent; i.e., the characterization factor K of the promoter liquid has a value which is generally at least 0.25, higher than the characterization factor of the liquefaction solvent.

The following Table provides representative characterization Factors (K) for various materials:

The liquid which is used to enhance and promote the separation of insoluble material is further characterized by a 5 volume percent distillation temperature of at least about 250 F. and a volume percent distillation temperature of at least about 350 F. and no greater than about 750 F. The promoter liquid preferably has a 5 volume percent distillation temperature of at least about 310 F. and most preferably of at least about 400 F. The 95 volume percent distillation temperature is preferably no greater than about 600 F. The most preferredpromoter liquid has a 5 volume percent distillation temperature of at least about 425 F. and a 95 volume percent distillation temperature of no greater than about 500 F. It is to be understood that the pro moter liquid may be a hydrocarbon; e.g., tetrahydronaphthalene, in which case the 5 volume percent and 95 volume percent distillation temperatures are the same; i.e., the hydrocarbon has a single boiling point. In such a case, the boiling point of the hydrocarbon must be at least about 350 F. in order to meet the requirement of a 5 volume percent distillation temperature of at least about 250 F. and a 95 volume percent distillation temperature of at least about 350 F. The promoter liquid ispreferably a blend or mixture of hydrocarbons in which case the 5 volume percent and 95 volume percent distillation temperatures are not the same.

The 5 volume and 95 volume percent distillation temperature may be conveniently determined by ASTM No. D 86-67 or No. D 1160 with the former being preferred for those liquids having a 95 percent volume distillation temperature below 600 F. and the latter for those above 600 F. The methods for determining such temperatures are well known in the art and further details in this respect are not required for a fully understanding of the invention. It is also to be understood that the reported temperatures are corrected to atmospheric pressure.

As representative examples of such liquids, there may be mentioned: kerosene or kerosene fraction from paraffinic or mixed base crude oils; middle distillates, light gas oils and gas oil fractions from paraffinic or mixed based crude oils; alkyl benzenes with side chains containing or more carbon atoms; paraffmic hydrocarbons containing more than 12 carbon atoms; white oils or white oil fraction derived from crude oils; alphaolefms containing more than 12 carbon atoms; fully hydrogenated naphthalenes and substituted naphthalenes; propylene oligomers (pentamer and higher); tetrahydronaphthalene, heavy naphtha fractions, etc. The most preferred liquids are kerosene fractions; white oils; fully hydrogenated naphthalenes and substituted naphthalenes; and tetrahydronaphthalene.

The amount of liquid promoter used for enhancing and promoting the separation of insoluble matter from the coal liquefaction product will vary with the particular liquid employed, the coal liquefaction solvent, the coal used as starting material and the manner in which the liquefaction is effected. As should be apparent to those skilled in the art, the amount of liquid promoter used should be minimized in order to reduce the overall costs of the process. It has been found that by using the liquid of controlled aromaticity, in accordance with the teachings of the present invention, the desired separation of insoluble material may be effected with modest amounts of liquid promoter. In general, the weight ratio of liquid promoter to coal solution may range from about 0.221 to about 3.0: 1, preferably from about 0.3:1 to about 2.0:] and, most preferably from about 0.311 to about 1.521. In using the preferred promoter liquid of the present invention which is a kerosene fraction having 5 percent and 95 percent volume distillation temperatures of 425 F. and 500 F. respectively, promoter liquid to coal solution weight ratios in the order of 0.4:1 to 0.611 have been particularly successful. It is to be understood, however, that greater amounts of liquid promoter may be employed, but the use of such greater amounts is uneconomical. In addition, the use of an excess of liquid promoter may result in the precipitation or separation of an excessive amount of desired coal derived products from the coal extract. More particularly, as the amount of liquid promoter employed is increased, a greater amount of ash is separated from the coal solution, but such an increased separation is accompanied by an increased separation of desired coal derived products from the coal solution. By using the liquid promoters of the present invention, not only may modest amounts of solvent be employed, but, in addition, ash may be effectively separated from the coal solution; e.g., in amounts greater than 99 percent, without an excessive loss of desired coal derived products.

More particularly, coal, such as bituminous coal, on a moisture ash free basis (MAF) may contain from about 5 percent to about 10 percent of insoluble material, such as fusain, and accordingly, at a minimum, from about 5 percent to about 10 percent, of the MAF coal, is lost in the process. In the recovery of coal derived products by a solvation process, the potential product loss is measured by the amount of 850 F+ product which is not recovered from the coal in that it is this fraction, which includes insoluble coal material, such as fusain, which can not be recovered from the residual solid product of the coal deashing. In accordance with the present invention, on a MAF coal feed basis, product loss of 850 F+ components (on an ash free basis) can be maintained at a value of no greater than about 40 percent, by weight, and preferably no greater than about 25 percent, by weight. In general, the loss of 850 F+ products, on a MAF coal basis, is from about 10 percent to about 25 percent, by weight. In addition, the net coal product (the extracted carbonaceous matter, excluding promoter liquid, liquefaction solvent and gas make), hereinafter sometimes referred to as coal product, contains less than about 1 percent insoluble material, generally less than 0.1 percent insoluble material and most preferably less than 0.05 percent insoluble material, all by weight. The specific amount of insoluble material which is permitted to be present in the coal product is dependent upon the product standards, and the deashing is controlled in order to provide the required specifications. Based on an Illinois type, the production of a coal product having less than .05 percent, by weight, insoluble material, corresponds to 99+ percent ash removal but as should be apparent to those skilled in the art, the percent ash removal to provide a coal product having the required minimum amount of insoluble material is dependent upon the initial ash content of the coal. Thus, in accordance with the present invention, the liquid promoter is added to the coal solution in an amount, as hereinabove described, to provide a coal product in which insoluble material is present in an amount of less than about 1 percent, by weight, and most preferably of less than 0.05 percent, by weight, with the loss of 850 F+ product being from about 10 percent to about 40 percent, by weight, preferably from about 10 percent to about 25 percent, by weight, on a MAF coal feed basis; i.e., from about 60 percent to about percent, by weight, of the MAP coal feed is recovered as either gas make or liquid fuel product.

The liquid promoter may also be prepared by blending a material having a characterization factor below 9.75 with a material having a characterization factor about 9.75, provided the blend has a characterization factor about 9.75 and the boiling properties, as hereinabove described. The use of blended materials is a convenient manner of regulating the characterization factor.

The separation of the insoluble material from the coal extract is generally effected at a temperature from about 300 F. to about 600 F., preferably from about 350 F. to about 500 F., and at a pressure from about 0 psig to about 500 psig, preferably at a pressure from about 0 psig to about 300 psig. It is to be understood that higher pressures could be employed, but as should be apparent to those skilled in the art, lower pressures are preferred. The insoluble material is preferably separated by gravity settling with the essentially insolublefree coal extract being recovered as an overflow and the insoluble material as underflow. In such gravity settling, the amount of underflow should be minimized in order to minimize the loss of heavier products in the underflow. The underflow withdrawal rate to obtain desired results is deemed to be within the scope of those skilled in the art. In general, such a rate is from about 20 to about 25 wt. percent of the total feed (liquefaction product and promoter liquid.) The residence time for such settling is generally in the order of from about 0.5 to about 6 hours, and preferably from about 0.5 to 3.0 hours.

In accordance with a particularly preferred embodiment of the present invention, the coal liquefaction product, prior to mixing thereof with the promoter liquid, is treated to separate at least those components boiling up to about the 95 volume percent distillation temperature of the promoter liquid. In this manner, the coal liquefaction product is free of components which boil within the range of those present in the promoter liquid, thereby facilitating the subsequent recovery of the promoter liquid from the coal liquefaction product.

The invention will be further described with respect to an embodiment thereof illustrated in the accompanying drawing. It is to be understood, however, that the scope of the invention is not to be limited thereby.

Referring to the drawing, ground or pulverized coal, generally bituminous, sub-bituminous or lignite, preferably bituminous coal, in line 10 is introduced into a coal solvation and slurrying zone 11 along with a coal liquefaction solvent in line 12. The coal liquefaction solvent may be any one of the wide variety of coal liquefaction solvents used in the art, including both hydrogen donor solvents, non-hydrogen donor solvents and mixtures thereof. These solvents are well known in the art and, accordingly, no detailed description thereof is deemed necessary for a full understanding of the invention. As particularly described, the coal liquefaction solvent is a 600-900 F. solvent which is recovered from the coal liquefaction product and which has not been subjected to hydrogenation subsequent to the recovery thereof. The solvent is added to the coal in an amount sufficient to effect the desired liquefaction, and in general, is added in an amount to provide a solvent to coal weight ratio from about 1:1 to about :1, and preferably from about 1.5:1 to about 5:1.

A coal paste is withdrawn from zone 11 through line 13 and introduced into a coal liquefaction zone 14 wherein, as known in the art, the coal is converted to liquid products. The liquefaction zone 14 is operated as known in the art and may be catalytic or non-catalytic and may be effected in the presence or absence of added hydrogen. The hydrogenation may be effected in a fixed catalyst bed, fluidized catalyst bed or in an expanded or ebullating bed. The details of the coal liquefaction step form no part of the present invention and, accordingly, no details thereof are required for a full understanding of the invention. As particularly described, the coal liquefaction is effected in the presence of added hydrogen. The hydrogenation, as known in the art, increases the recovery of coal products and also reduces the sulfur and nitrogen content of the recovered liquid coal product. The liquefaction is preferably effected in an upflow ebullated bed, as known in the art; e.g., as described in US. Pat. No. 2,987,465 to Johanson. The coal liquefaction zone, as known in the art, includes means for recovering the various gaseous products.

A coal liquefaction product, comprised of a liquid coal extract of dissolved carbonaceous matter in the coal liquefaction solvent and insoluble material (ash and undissolved coal) is withdrawn from the liquefaction zone 14 through line 15 and introduced into a separation zone 16 to separate from the coal liquefaction product at least those materials boiling up to about the volume percent distillation temperature of the liquid to be used for promoting and enhancing the separation of the insoluble material. The separation zone 16 may include an atmospheric or vacuum flashing chamber or tower, and as particularly described separation zone 16 is designed and operated to separate components boiling up to about 550 F.

A coal liquefaction product, free of components boiling up to about 550 F., withdrawn from separation zone 16 through line 17, is mixed with promoter liquid in line 21 of controlled aromaticity, i.e., the character ization factor of the promoter liquid has a value which is generally at least 0.25 unit greater than the characterization factor of the coal liquefaction solvent. As particularly described, the promoter liquid is a kero sene fraction which has 5 volume percent and 95 volume percent distillation temperatures which fall within the range from about 425500 1F and is derived from a naphthenic or paraffinic distillate.

The combined stream of coal liquefaction product and promoter liquid in line 22 is introduced into a gravity separation zone 23, comprised of a gravity settler which may be any one of those known in the art, wherein an essentially solids free overflow is separated from a solid containing underflow. Although the gravity settler may be any one of those generally known in the art, the settler is preferably of a special type developed for the present invention as hereinafter described with reference to FIG. 2.

The overflow essentially free of insoluble mateial, is withdrawn from separation zone 23 through line 24 and introduced into a recovery zone 25 for recovering promoter liquid and various fractions of the coal extract. The recovery zone 25 may be comprised of one or more fractionators to distill various fractions from the product. As particularly described, the recovery zone is operated to recover a first fraction having 5 percent and 95 percent volume distillation temperatures of from 425 to 500 F. which is to be used as the promoter liquid for enhancing and promoting separation i of solid material from the coal liquefaction product; a second fraction (500600 F) which may be employed as a distillate fuel blendstock; a third fraction (600- 900 F) a portion of which may be used as the coal liquefaction solvent in line 12 and a further portion thereof recovered as product and a residual product 900 F) of low ash and reduced sulfur content which may be used as a fuel or subjected to further treatment. The promoter liquid recovered in the: recovery zone is admixed with the liquefaction product in line 17 and makeup may be provided through line 26.

The underflow containing dispersed insoluble material withdrawn from separation zone 23 through line 31 is introduced into a stripping zone 32 wherein material boiling, below about 900 F is stripped therefrom and introduced into the recovery zone 25 through line 33. The ash rich stripper bottoms in line 34 may then be subjected to calcination or coking. Alternatively, part of the stripper bottoms may be used as feedstock to a partial oxidation process for producing hydrogen. As a further alternative a portion of the stripper bottoms may be used for plant fuel. These uses and others should be apparent to those skilled in the art from the teachings herein. In accordance with the present invention, the stripper bottoms in line 34 contains from about percent to about percent, by weight, of the MAF coal. In addition the coal product (the product recovered from

zones

16 and 25, excluding liquefaction solvent and promoter liquid contains less than 1 percent and preferably less than 0.05 percent, by weight, of insoluble material.

The gravity settler of the present invention which is preferably used in the embodiment of FIG. 1 is described with reference to FIG. 2.

Referring now to FIG. 2, there is shown the preferred settler 100 of the present invention comprised of a cylindrical main body portion 101 and dished upper and

lower heads

102 and 103, respectively. The main body portion 101 is provided with a feed inlet 104 which is positioned perpendicularly to the main axis of the vessel 100 at a central point thereof. The upper head 102 is provided with an inclined overflow outlet 105 and the lower head 103 is provided with an inclined underflow outlet 106, both of which are inclined at an angle of approximately The settler 100 is slanted at an angle with respect to horizonatal with the preferred angle being from about 45 to about The mixture of coal liquefaction prodnet and promoter liquid is introduced into the settler through inlet 104, with the essentially solid free overflow being withdrawn through overflow outlet 105 and the solid containing underflow being withdrawn without accumulation of ash and bitumens.

Although the settler of the present invention is particularly suited for use with the deashing technique of the present invention, such a settler may also be used 5 for gravity settling deashing by techniques other than those of the present invention.

The invention will be further described with respect to the following examples, but the scope of the invention is not to be limited thereby. Unless otherwise indi- 10 cated all parts and percentages are by weight.

All of the hydrotreated coal solutions used in the subsequent deashing examples except No. 92 (40 percent coal and 60 percent solvent) were prepared from a coal paste or suspension containing 30 wt. percent bitumi- 15 nous coal (Illinois No. 6) and wt. percent 600-900 F. coal tar distillate. This coal paste was fed along with hydrogen into an upflow, expanded bed catalytic reactor, containing a commercially available catalyst. The reactor was operated at temperatures and pressures in 0 the 750-850 F. and LOGO-2,000 psig range respec- 25 sure and an ash-rich liquid product was withdrawn.

This ash-rich liquid receiver product will hereinafter be referred to as either a coal solution, ash-rich coal solution, or hydrogenated coal solution.

Table 1 below is a summary of analytical inspection 30 data obtained for the ash-rich coal solutions used in the solvent deashing examples, which will be cited subsequently.

Table 1 Analytical Date Summary of Coal Solutions Used in the Solvent Deashing Examples Coal Solution Number Ash-Rich Coal Soln. Analvtical Data wt. 7? Sulfur 0. wt. Ash 2. wt. 7! Benzene lnsolublcs 8.

ll 36 38 2I 66 92 Table 2 below is a compilation of Characterization Factors on liquids used in the subsequent deashing examples. This index is a measure of aromaticity and/or parafinicity.

Table 2 Aromaticity and/or Paratinicity of the Liquids Used in thc Deashing Examples Liquids Char. Factor 571-95'4 volume distillate F. Remarks A 9.4l 400-450 Coal Tar Distillate B 8. 425-500 Coal Tar Distillate C 9. 403 Tetrahydronaphthalene D l 1. 425-500 Distillate Prepared from Kerosene The use of the inclined separator of the present 1n- EXAMPLE I vention for deashing a coal liquefaction product has been found to be particularly advantageous. The use of a settler in a horizontal position generally results in an accumulation of ash and heavy bitumens. The use of a tank in a vertical position prevents the accumulation of such materials, but it provides less settling cross sectional area than that provided in a horizontal tank. The use of the inclined settler of the present invention provides efficient use of a given diameter vessel for settling 300 grams of ash-rich coal solution number 1 and 1,200 grams of liquid A were charged to a 2 liter cylindrical stainless steel electrically heated rocking bomb. Bomb in measurements was 4.26 inches l.D. X 18 inches long on the straight side, and it was equipped with a A inch bottom drawoff valve. The contents of the bomb were rocked and heated to 500 F. over about a 30 minute period. Bomb contents were then allowed to settle vertically for about 4 hours at 500 F. without any rocking.

At the end of the settling period, 150 grams of an ashrich underflow stream were withdrawn through the bottom valve. The remainder of the bombs contents were withdrawn through the bottom valve and this ash-lean solution was analyzed for ash content. The ash content of the ash-lean solution was 0.25 wt. percent which corresponds to an ash removal of 57 percent.

This example illustrates the ineffectiveness of an aromatic type of liquid; i.e., a characterization factor K below 9.75, notwithstanding the use of a liquid to coal solution of 4:1.

EXAMPLE 2 300 grams of ash-rich coal solution number 11, and a blend of 300 grams of liquid D and 900 grams of liquid B, were added to the 2 liter rocking bomb described in example 1. The contents of the bomb were heated with rocking to 500 F. over about a 30 minute period. Bomb contents were then allowed to settle vertically for about 4 hours at 500 F. without any rocking.

At the end of the settling period, 258 grams of an ashrich underflow stream were withdrawn through the bottom valve. The remainder of the bombs contents were withdrawn through the bottom valve and this ash-lean solution was analyzed for ash content. The ash content of the ash-lean solution was 0.01 wt. percent, which corresponds to an ash removal of 98+ percent.

This example illustrates the effectiveness of a liquid blend at a promoter to coal solution ratio of about 1:1.

EXAMPLE 3 A 1,500 ml. dimpled glass resin flask was used in the experiment. The resin flask was outfitted with a four bladed turbine agitator, thermometer, a heating mantle, reflux condenser, and a dropping funnel.

450 grams of ash-rich coal solution number 36 was added to the resin flask. Flask contents were then heated with mixing to 350 F. over about a 30 minute period. 585 grams of liquid C were added dropwise over about a 1 hour period. Agitation and a temperature of 350 F. were maintained during anti-solvent addition. The contents of the flask were agitated for an additional 30 minute period at 350 F. Agitation was stopped and the flask contents were settled for 4.0 hours at 350 F.

750 grams of ash-lean overflow solution were pipeted from the resin flask and analyzed for ash content. The resin flask was disassembled and an ash-rich underflow solution was poured from the flask. Ash content of the ash-lean overflow solution was found to be 0.08 wt. percent, which corresponds to an ash removal of 94.7 percent.

This example illustrates the effectiveness of a liquid promoter of the present invention, in the absence of diluent, at a promoter liquid to coal solution ratio of 1.3:1.

EXAMPLE 4 The equipment used in this experiment is identical to that used in Example 3.

650 grams of ash-rich coal solution number 38 was charged to a 1,500 ml resin flask. The flask was heated with mixing to 350 F. over about a 30 minute period. 350 grams of liquid D were added dropwise over a l hour period via a dropping funnel. Mixing and a flask internal temperature of 350 F. were maintained during the addition. The flasks contents were agitated at 350 F. for an additional 30 minute period. Agitation was stopped and the contents of the flask were allowed to settle for 4 hours at 350 F.

708 grams of ash-lean overflow solution were pipeted from the resin flask and subsequently analyzed for ash content. The resin flask was then disassembled and an ash-rich underflow solution was poured from the flask. Ash content of the ash-lean overflow solution was found to be 0.03 wt. percent, which corresponds to a 98.7 percent ash removal.

This example illustrates the effectiveness of a liquid promoter of the present invention, in the absence of diluent, at a promoter liquid to coal solution ratio of about 0.54:1.

EXAMPLE 5 The apparatus used in this experiment is identical to that used in Example 3.

450 grams of ash-rich coal solution number 11 and 650 grams of liquid B were charged to a 1,500 ml resin flask. The mixture was heated to 350 F. with stirring over about a 30 minute period. grams of liquid D were added dropwise via a dropping funnel over about a 1 hour period, while the agitation and a 350 F. flask internal temperature was maintained. The contents of the flask were then agitated at 350 F. for an additional 30 minute period. Mixing was stopped and the flasks contents were allowed to settle for 5 hours.

912 grams of ash-lean overflow solution was pipeted from the resin flask and subsequently analyzed for ash content. The resin flask was disassembled and 268 grams of an ash-rich underflow solution was poured therefrom. Ash content of the ash-lean overflow solution was found to be 0.05 wt. percent, which corresponds to a 96.4 percent ash removal.

This example illustrates the effectiveness of a liquid blend at a liquid to coal solution ratio of about 1.4:1.

EXAMPLE 6 The settler apparatus described with reference to FIG. 2 is used to deash ash-rich coal solution No. 21.

EXAMPLE 7 The apparatus described with reference to FIG. 2 is used to deash coal solution No. 92 using promoter liquid D. The conditions and results are reported in the following Table.

Run 7A Run 78 Run 7C Coal 92 66 92 Liquid to Coal 0.40 0.45 0.50

The following laboratory runs indicate the difference between a promoter liquid of the present invention and hexane as a promoter liquid, hexane being a paraffmic liquid which does not have the boiling characteristics of the liquid of the present invention.

Table Run 8A Run 813 Run 8C Coal Solution 92 92 92 Promoter liquid Hexane Hexane D Wt. ratio of Promoter 0.40 0.50 0.50 liquid to Coal Solution Temp. F. 400 400 400 Pressure (psig) 100 100 Settling Time (hrs) 4.0 4.0 40 Ash content overflow 1.60 0.77 0.0l wt.% Ash removal wt. 59.2 810 997 +850F MAF components 39.2 50.3 26.8

present in underflow wt.% MAF coal fed The above indicates the difference in effectiveness between hexane and the promoter liquid of the present invention.

EXAMPLE 9 In accordance with the present invention, in a typical run, based on 40 lbs. of coal feed in line 10 and 1.4 lbs. of hydrogen feed to the liquefaction zone, the net liquified coal product recovered in zone 16 and recovery zone is about 20 lbs; the gas make in the liquefaction zone is about 11 lbs; and the coal residual product in line 34 is about 10 lbs., with about 4 lbs thereof being ash. This represents about 99+ percent, by weight, ash removal, with MAF coal product loss based on MAF coal feed, being about 18 percent, by weight.

EXAMPLE 10 Coal solution number 92 is deashed in the laboratory using promoter liquid D as follows:

The present invention is particularly advantageous in that insoluble materials can be separated from a coal liquefaction product without requiring filtration. In addition, by proceeding in accordance with the present 5 invention ash and insoluble material separation can be maximized with minimum loss of desired coal derived products and with modest amounts of promoter liquid.

Although the prior art, in particular US. Pat. No. 3,607,716, discloses a process for separating insoluble material from a coal liquefaction product, without filtration, by use of a fractionating solvent, such as hexane, as hereinabove described, the use of such light fractionating solvents require higher amounts of the solvent to effectively remove ash and such ash removal is accompanied by a loss of desired coal derived products. In addition, such a process requires operating pressures higher than those required in the present invention which increases processing costs.

The present invention is also distinguishable from an extraction process in that the promoter liquid is not employed to extract a fraction of the liquid coal extract, but instead is employed to promote settling of insoluble material.

Numerous modifications and variations of the pres ent invention are possible in light of the above teachings and, therefore, within the scope of the appended claims the invention may be practised other than as particularly described.

What is claimed is:

l. A process for separating insoluble material from a coal liquefaction product produced from a coal feed and comprised of insoluble material and carbonaceous matter dissolved in a coal liquefaction solvent, comprising:

introducing said liquefaction product and a liquid promoter into a gravity settling zone to separate insoluble material by gravity settling, said liquid promoter having a 5 volume percent distillation tem' perature of at least about 250 F. and a 95 volume percent distillation temperature of at least about 350 F. and no greater than about 750 F., said liquid having a characterization factor (K) of at least 9.75;

said liquid having a characterization factor greater than said coal liquefaction solvent;

said promoter liquid being added in an amount sufficient to promote and enhance gravity settling of insoluble material to produce an overflow essentially free of insoluble material; and

recovering from the settling zone a liquid overflow essentially free of insoluble material and a liquid underflow containing the insoluble material.

2. The process of claim 1 wherein the weight ratio of liquid to coal solution is from about 0.2:] to about 3.011.

3. The process of claim 2 wherein the 5 volume percent distillation temperature of the liquid promoter is at least about 310 F.

4. The process of claim 2 wherein the liquid promoter is at least one member selected from the group consisting of kerosene, kerosene fractions, middle distillates, light gas oils, gas oil fractions, heavy naphthas, white oils and white oil fractions from crude oils.

5. The process of claim 4 wherein the characterization factor of the liquid promoter has a value at least 0.25 higher than the characterization factor of the coal liquefaction solvent.

6. The process of claim 1 wherein the weight ratio of liquid to coal solution is from about 0.3:1 to about 2.021.

7. The process of claim 6 wherein said promoter liquid is tetrahydronaphthalene.

8. The process of claim 1 wherein said liquid has a characterization factor of at least 1 1.0.

9. The process of claim 8 wherein said gravity settling is effected at a temperature from about 300 F. to about 600 F. and a pressure from about psig to about 500 psig.

10. The process of claim 8 wherein the promoter liquid is a fraction having a volume percent distillation temperature of at least about 425 F. and a 95 volume percent distillation temperature of no greater than about 500 F.

11. The process of claim 1 wherein the liquid promoter is a kerosene fraction having a characterization factor of about 1 1.9 and a 5 volume percent distillation temperature of no less than 425 F. and a 95 volume distillation temperature of no greater than about 500 F.

12. The process of claim 11 wherein the weight ratio of liquid to coal solution is from about 0.3:1 to about :1.

13. A process for separating insoluble material from a coal liquefaction product produced from a coal feed and comprised of insoluble material and carbonaceous matter dissolved in a coal liquefaction, solvent, comprising:

effecting said separation in a gravity settling zone in the presence of a liquid promoter of a hydrocarbon mixture, said liquid promoter having a 5 volume percent distillation temperature of at least about 250 F and a 95 volume percent distillation temperature of at least about 350 F and no greater than about 750 F, said liquid promoter being at least one member selected from the group consisting of kerosene, kerosene fractions, middle distillates, light gas oils, gas oil fractions, heavy naphthas, white oils and white oil fractions from crude oils,

and having a characterization factor (K) of at least said liquid having a characterization factor greater than said coal liquefaction solvent, the liquid promoter to coal liquefaction product weight ratio being from about 0.2:1 to about 3.0:1, said ratio being an amount which produces an essentially insoluble material free overflow from said gravity settling zone and a net coal product from said coal feed containing less than about 0.05 percent, by weight, insoluble material and an underflow which contains the insoluble material, said underflow containing no greater than about 40 percent, by weight, of the moisture ash free coal as an ash free 850 F+ fraction.

14. The process of claim 13 wherein said 5 volume percent distillation temperature is at least about 400 F.

15. The process of claim 14 wherein said promoter liquid is a kerosene fraction having a characterization factor of about 11.9, a 5 volume percent distillation temperature of at least about 4250 F., and a 95 volume percent distillation temperature of no greater than about 500 F.

16. The process of claim 15 wherein said settling zone is operated at a temperature from about 300 F to about 600 F and at a pressure from about 0 psig to about 500 psig.

17. The process of claim 16 wherein said underflow contains no greater than about 25 percent, by weight, of the moisture ash free coal as an ash free +850 F. fraction.

18.The process of claim 17 wherein said promoter liquid to coal liquefaction product weight ratio is from about 0.411 to about 06:1.

19. The process of claim 13 wherein underflow is withdrawn from said settling zone at a rate of from about 20 to about 25 wt. percent of the total of liquefaction product and promoter liquid introduced into the settling zone.

20. The process of claim 13 wherein the liquid promoter has a characterization factor of at least about 11.0.

21. The process of claim 20 wherein the promoter liquid has a volume percentdistillation temperature of no greater than about 600 F.

22. The process of claim 20 and further comprising: stripping promoter liquid and components boiling up to about 900 F. from said underflow.

23. The process of claim 20 wherein the promoter liquid is a fraction having a 5 volume percent distillation temperature of at least about 425 F. and a 95 volume percent distillation temperature of no greater than about 500 F.

24. The process of claim 13 wherein the characterization factor of the liquid promoter has a value at least 0.25 higher than the characterization factor of the coal liquefaction solvent.

25. A process for separating insoluble material from a coal liquefaction product produced from a coal feed and comprised of insoluble material and carbonaceous matter dissolved in a coal liquefaction solvent, comprising:

a. separating from the coal liquefaction product at least those components boiling up to about the 95 volume percent distillation temperature of the liquid promoter hereinafter defined in step (b);

b. introducing the coal liquefaction product from step (a) and a liquid promoter into a gravity settling zone, said liquid promoter having a 5 volume percent distillation temperature of at least about 250 F. and a 95 volume percent distillation temperature of at least about 350 F. and no greater than about 750 F., said liquid having a characterization factor (K) of at least about 9.75, said liquid having a characterization factor K greater than said coal liquefaction solvent and being present in an amount sufficient to promote and enhance gravity settling of insoluble material to produce a net coal product from said coal feed containing less than about 0.1 percent, by weight, insoluble material and a coal residue con taining no greater than about 40 percent, by weight, of the MAP coal feed as an ash free +850 F. fraction;

0. withdrawing a liquid overflow essentially free of insoluble material and a liquid underflow contain ing said coal residue from the gravity settling zone;

d. separating the promoter liquid from the liquid overflow; and

e. passing separated promoter liquid from step (d) to step (b).

26. The process of claim 25 wherein the liquid promoter has a characterization factor of at least about 1 1.0.

27. The process of claim 25 wherein in the liquid promoter is at least one member selected from the group consisting of kerosene, kerosene fractions, middle distillates, light gas oils, gas oil fractions, heavy naphthas, white oils and white oil fractions from crude oils.

28. The process of claim 27 wherein the promoter liquid has a 5 volume percent distillation temperature of at least about 310 F.

29. The process of claim 28 wherein said gravity settling is effected at a temperature from about 300 F to about 600 F and a pressure from about 0 psig to about 500 psig.

30. The process of claim 29 wherein said liquid is a kerosene fraction having a characterization factor of about 1 1.9, a 5 volume percent distillation temperature of no less than about 425 F. and a volume percent distillation temperature of no greater than about 500 F.

31. The process of claim 27 wherein the characterization factor of the liquid promoter has a value at least 0.25 higher than the characterization factor of the coal liquefaction solvent.

3 a UNITED STATES PATENT OFFICE CERTIFICATE OFCORRECTION Patent No. 3,856,675 Dated December 24, 1974 Inventor(s) MORGAN C. SZE ET AL It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

' In the specification columnZ line 4 the formula (K) should read as follows:

' Signed and Sealed this Tleenty-tltird Day Of December I980 [SEAL] Attest:

SIDNEY A. DIAMOND Attestt'ng Ojficer Commissioner of Patents and Trademarks

Claims

1. A PROCESS FOR SEPARATING INSOLUBLE MATERIAL FROM A COAL LIQUEFACTION PRODUCT PRODUCED FROM A COAL FEED AND COMPRISED OF INSOLUBLE MATERIAL AND CARBONACEOUS MATTER DISSOLVED IN A COAL LIQUEFACTION SOLVENT, COMPRISING: INTRODUCING SAID LIQUEFACTION PRODUCT AND A LIQUID PROMOTER INTO A GRAVITY SETTLING ZONE TO SEPARATE INSOLUBLE MATERIAL BY GRAVITY SETTLING, SAID LIAQUID PROMOTER HAVING A 5 VOLUME PERCENT DISTILLATION TEMPERATURE OF AT LEAST ABOUT 250*F. AND A 95 VOLUME PERCENT DISTILLATION TEMPERATURE OF AT LEAST ABOUT 350*F. AND NO GREATER THAN ABOUT 750*F., SAID LIQUID HAVING A CHARACTERIZATION FACTOR (K) OF AT LEAST 9.75; SAID LIQUID HAVING A CHARACTERIZATION FACTOR GREATER THAN SAID COAL LIQUEFACTION SOLVENT; SAID PROMOTER LIQUID BEING ADDED IN AN AMOUNT SUFFICIENT TO PROMOTE AND ENHANCE GRAVITY SETTLING OF INSOLUBLE MATERIAL TO PRODUCE AN OVERFLOW ESSENTIALLY FREE OF INSOLUBLE MATERIAL; AND RECOVERING FROM THE SETTLING ZONE A LIQUID OVERFLOW ESSENTIALLY FREE OF INSOLUBLE MATERIAL AND A LIQUID UNDERFLOW CONTAINING THE INSOLUBLE MATERIAL.

2. The process of claim 1 wherein the weight ratio of liquid to coal solution is from about 0.2:1 to about 3.0:1.

3. The process of claim 2 wherein the 5 volume percent distillation temperature of the liquid promoter is at least about 310* F.

6. The process of claim 1 wherein the weight ratio of liquid to coal solution is from about 0.3:1 to about 2.0:1.

8. The process of claim 1 wherein said liquid has a characterization factor of at least 11.0.

9. The process of claim 8 wherein said gravity settling is effected at a temperature from about 300* F. to about 600* F. and a pressure from about 0 psig to about 500 psig.

10. The process of claim 8 wherein the promoter liquid is a fraction having a 5 volume percent distillation temperature of at least about 425* F. and a 95 volume percent distillation temperature of no greater than about 500* F.

11. The process of claim 1 wherein the liquid promoter is a kerosene fraction having a characterization factor of about 11.9 and a 5 volume percent distillation temperature of no less than 425* F. and a 95 volume distillation temperature of no greater than about 500* F.

12. The process of claim 11 wherein the weight ratio of liquid to coal solution is from about 0.3:1 to about 2.0:1.

13. A process for separating insoluble material from a coal liquefaction product produced from a coal feed and comprised of insoluble material and carbonaceous matter dissolved in a coal liquefaction, solvent, comprising: effecting said separation in a gravity settling zone in the presence of a liquid promoter of a hydrocarbon mixture, said liquid promoter having a 5 volume percent distillation temperature of at least about 250* F and a 95 volume percent distillation temperature of at least about 350* F and no greater than about 750* F, said liquid promoter being at least one member selected from the group consisting of kerosene, kerosene fractions, middle distillates, light gas oils, gas oil fractions, heavy naphthas, white oils and white oil fractions from crude oils, and having a characterization factor (K) of at least 9.75, said liquid having a characterization factor greater than said coal liquefaction solvent, the liquid promoter to coal liquefaction product weight ratio being from about 0.2:1 to about 3.0:1, said ratio being an amount which produces an essentially insoluble material free overflow from said gravity settling zone and a net coal product from said coal feed containing less than about 0.05 percent, by weight, insoluble material and an underflow which contains the insoluble material, said underflow containing no greater than about 40 percent, by weight, of the moisture ash free coal as an ash free 850* F+ fraction.

14. The process of claim 13 wherein said 5 volume percent distillation temperature is at least about 400* F.

15. The process of claim 14 wherein said promoter liquid is a kerosene fraction having a characterization factor of about 11.9, a 5 volume percent distillation temperature of at least about 4250* F., and a 95 volume percent distillation temperature of no greater than about 500* F.

16. The process of claim 15 wherein said settling zone is operated at a temperature from about 300* F to about 600* F and at a pressure from about 0 psig to about 500 psig.

17. The process of claim 16 wherein said underflow contains no greater than about 25 percent, by weight, of the moisture ash free coal as an ash free +850* F. fraction.

18. The process of claim 17 wherein said promoter liquid to coal liquefaction product weight ratio is from about 0.4:1 to about 0.6:1.

21. The process of claim 20 wherein the promoter liquid has a 95 volume percent distillation temperature of no greater than about 600* F.

22. The process of claim 20 and further comprising: stripping promoter liquid and components boiling up to about 900* F. from said underflow.

23. The process of claim 20 wherein the promoter liquid is a fraction having a 5 volume percent distillation temperature of at least about 425* F. and a 95 volume percent distillation temperature of no greater than about 500* F.

25. A process for separating insoluble material from a coal liquefaction product produced from a coal feed and comprised of insoluble material and carbonaceous matter dissolved in a coal liquefaction solvent, comprising: a. separating from the coal liquefaction product at least those components boiling up to about the 95 volume percent distillation temperature of the liquid promoter hereinafter defined in step (b); b. introducing the coal liquefaction product from step (a) and a liquid promoter into a gravity settling zone, said liquid promoter having a 5 volume percent distillation temperature of at least about 250* F. and a 95 volume percent distillation temperature of at least about 350* F. and no greater than about 750* F., said liquid having a characterization factor (K) of at least about 9.75, said liquid having a characterization factor K greater than said coal liquefaction solvent and being present in an amount sufficient to promote and enhance gravity settling of insoluble material to produce a net coal product from said coal feed containing less than about 0.1 percent, by weight, insoluble material and a coal residue containing no greater than about 40 percent, by weight, of the MAF coal feed as an ash free +850* F. fraction; c. withdrawing a liquid overflow essentially free of insoluble material and a liquid underflow containing said coal residue from the gravity settling zone; d. separating the promoter liquid from the liquid overflow; and e. passing separated promoter liquid from step (d) to step (b).

26. The process of claim 25 wherein the liquid promoter has a characterization factor of at least about 11.0.

28. The process of claim 27 wherein the promoter liquid has a 5 volume percent distillation temperature of at least about 310* F.

29. The process of claim 28 wherein said gravity settling is effected at a temperature from about 300* F to about 600* F and a pressure from about 0 psig to about 500 psig.

30. The process of claim 29 wherein said liquid is a kerosene fraction having a characterization fActor of about 11.9, a 5 volume percent distillation temperature of no less than about 425* F. and a 95 volume percent distillation temperature of no greater than about 500* F.