CA1190167A - Process for the liquefaction of solid carbonaceous materials - Google Patents
Process for the liquefaction of solid carbonaceous materialsInfo
- Publication number
- CA1190167A CA1190167A CA000407523A CA407523A CA1190167A CA 1190167 A CA1190167 A CA 1190167A CA 000407523 A CA000407523 A CA 000407523A CA 407523 A CA407523 A CA 407523A CA 1190167 A CA1190167 A CA 1190167A
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- Prior art keywords
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- liquefaction
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Classifications
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G1/00—Production of liquid hydrocarbon mixtures from oil-shale, oil-sand, or non-melting solid carbonaceous or similar materials, e.g. wood, coal
- C10G1/006—Combinations of processes provided in groups C10G1/02 - C10G1/08
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Life Sciences & Earth Sciences (AREA)
- Wood Science & Technology (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
- Working-Up Tar And Pitch (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
An improved process for liquefying solid carbona-ceous materials wherein liquefaction yields are increased by extracting the normally solid bottoms product with a solvent containing donatable hydrogen. The extraction is accomplished at a temperature within the range from about 50 to about 600°F and at a pressure within the range from about 0 to about 750 psig and at least a portion of the extract is recycled to the liquefaction reaction zone.
An improved process for liquefying solid carbona-ceous materials wherein liquefaction yields are increased by extracting the normally solid bottoms product with a solvent containing donatable hydrogen. The extraction is accomplished at a temperature within the range from about 50 to about 600°F and at a pressure within the range from about 0 to about 750 psig and at least a portion of the extract is recycled to the liquefaction reaction zone.
Description
3~ 7
2 This invention relates to an improved process for
3 converting coal or similar solid carbonaceous materials.
More particularly, this invention relates to an improved process for liquefying coal and similar solid carbonaceous 6 materials.
7 AS is also well known, proven petroleum and gas re-8 serves are shrinking throughout the world and the need for 9 alternate sources of energy is becoming more and more appar-ent. One such alternate source is, of course, coal since 11 coal is an abundant fossil fuel in many countries throughout 12 the world. Before coal will be generally accepted by the 13 ultimate consumer, however, it will be necessary to convert 14 the same to a form which will permit use in those areas 15 where liquid or gaseous fuels are normally required.
16 To this end, several processes wherein coal is ei-17 ther liquefied and/or gasified have been proposed hereto-18 fore. Of these, the processes wherein coal is liquefied 19 appear to be more desirable since a broader range of pro-20 ducts is produced and these products are more readily trans-21 ported and stored.
22 of these several liquefaction processes which have 23 heretofore been proposed, those processes wherein coal is 24 liquefied in the presence of a solvent or diluent, particu-25 larly a hydrogen-donor solventor diluent, and in the pre-26 sence of a hydrogen-containing gas appear to offer the 27 greater advantages. In these processes, lique~action is 28 accomplished at elevated temperatures and pressures and 29 hydrocarbon gases are invariably produced as by-products.
30 For the most part, however, these and other liquefaction 31 processes yield a normally solid bottoms product containing 32 relatively large quantities of carbon, which bottom product 33 cannot be discarded without further processing when an eco 34 nomic, waste-free process is sought. ~leretofore, several 35 methods have been proposed in an effort to avoid this dei-36 ciency. For example, the normally solid, bottoms product 37 can be subjected to further liquefaction in a separate stage .
~L~ 67 1 or stages until such time as the carbon content of the 2 normally solid, bottoms product has been reduced to a 3 point where the carbon content thereof is sufficiently low
More particularly, this invention relates to an improved process for liquefying coal and similar solid carbonaceous 6 materials.
7 AS is also well known, proven petroleum and gas re-8 serves are shrinking throughout the world and the need for 9 alternate sources of energy is becoming more and more appar-ent. One such alternate source is, of course, coal since 11 coal is an abundant fossil fuel in many countries throughout 12 the world. Before coal will be generally accepted by the 13 ultimate consumer, however, it will be necessary to convert 14 the same to a form which will permit use in those areas 15 where liquid or gaseous fuels are normally required.
16 To this end, several processes wherein coal is ei-17 ther liquefied and/or gasified have been proposed hereto-18 fore. Of these, the processes wherein coal is liquefied 19 appear to be more desirable since a broader range of pro-20 ducts is produced and these products are more readily trans-21 ported and stored.
22 of these several liquefaction processes which have 23 heretofore been proposed, those processes wherein coal is 24 liquefied in the presence of a solvent or diluent, particu-25 larly a hydrogen-donor solventor diluent, and in the pre-26 sence of a hydrogen-containing gas appear to offer the 27 greater advantages. In these processes, lique~action is 28 accomplished at elevated temperatures and pressures and 29 hydrocarbon gases are invariably produced as by-products.
30 For the most part, however, these and other liquefaction 31 processes yield a normally solid bottoms product containing 32 relatively large quantities of carbon, which bottom product 33 cannot be discarded without further processing when an eco 34 nomic, waste-free process is sought. ~leretofore, several 35 methods have been proposed in an effort to avoid this dei-36 ciency. For example, the normally solid, bottoms product 37 can be subjected to further liquefaction in a separate stage .
~L~ 67 1 or stages until such time as the carbon content of the 2 normally solid, bottoms product has been reduced to a 3 point where the carbon content thereof is sufficiently low
4 such that discarding thereof does not significantly and adversely affect the economics of the process. Staged 6 liquefaction, however, significantly increases both invest-7 ment and operating cos~s as a result of the additional 8 equipment required and as a result of the energy and other 9 utilities required to effect the further li~uefaction. It has also been proposed, heretofore, to recycle all or a 11 portion of the normally solid, bottoms product to a single 12 or plural liquefaction stage. When this is done, however, 13 a large portion of the material recycle is either unreac-14 tive (ash~ or it is difficult to convert (fusinite). These materials can amount to 60~ of the recycle material and re-16 cycle of these materials raises costs and lowers ther~al 17 efficiency. It has also been proposed, heretofore, to 18 simply burn the normally solid, bottoms product, directly, 19 or to gasify the normally solid, bottoms product to produce a gaseous product which can then be burned as a fuel.
21 Operation in this manner, however, reduces the yield of 22 normally liquid products, thereby reducing thermal effi-23 ciency, and increases both investment and operating costs 24 for essentially the same reasons already noted with respect to staged or further liquefaction. Finally, it has been 26 proposed, heretofore, to separate the unreactive and fusi-27 nite portions of the bottoms from the reactive portion 28 thereof by extraction. Generally, however, these operations 29 depend upon the use of a relatively expensive solvent (such as toluene) which must then be separated from the extract, 31 generally, hy vaporization. This type of operation too has 32 proven expensive due primarily to the high energy require-33 ment for separation of the solvent.
34 In light of the ~oregoing, the need for a liquefac-3~ tlon process which can be operated in a mode requiring fewer 36 liquefaction stages at an increased thermal efficiency to 37 yield a normally solid, bottoms product relatively low in J~ ~
1 carbon, which product may be discarded, i.s believed 2 readily apparent. More part:icularly, the need for a lique-3 faction process wherein a significant portion of the carbon 4 contained in the normally solid, bottoTnsproduct can be efficiently recovered via extraction is believed to be 6 readily apparent.
8 It has now been discovered that the foregoing and 9 other disadvantages of the prior art processes can be re-duced with the method of .he present invention and an im-11 proved liquefaction process provided thereby. It is, 12 therefore, an object of this invention to provide an im-13 proved liquefaction process wherein the yield of liquid 14 product is increased without further liquefaction at ele-vated temperatures and pressures and without recycling the 16 inactive and fusinite portions of the normally solid, bot-17 tom product which preferably can be discarded~directly, 18 after an extraction operation with a reduced impact on pro-19 cess economics and thermal efficiency. The foregoing and other objects and advantages will become apparent from the 21 description set forth hereinafter and from the drawings 22 appended thereto.
23 In accordance with the present invention, the fore-24 going and other objects and advantages are accomplished by liquefying a coal or similar solid carbonaceous material in 26 the presence of a hydrogen donor solvent at elevated tem-27 peratures and pressures and thereafter extracting at least 28 a portion of the reactive bottoms from the normally solid 29 bottoms product. The extraction will be accomplished with a hydrogen donor solvent derived from the solid carbonaceous 31 material subjected to liquefaction. The raffinate from the 32 extraction, without separation of the solvent, will be re-33 cycled to the liquefaction sta~e thereby increasing the 34 overall liquid yield of the process. The normally solid bottoms product remaining after extraction will contain less 36 carbon than the feed to the extraction step and may be dis-37 carded, directly, with less adverse impact on economics ~Llr:b~3~
l than would be the case lf the original, unextracted nor-2 mally solid bottoms product were discarded. As indicated 3 more fully hereinafter, however, maximum conversion of the 4 solid carbonaceous material and maximum thermal efficiency will be realized either by burning the remaining normally 6 solid bottoms product or by further treating the same to 7 produce a useful EuelO
8 BRIEF DESCRIPTION OF T~IE DRAWING
9 The figure is a schematic flow diagram of a process within the scope of the present invention.
11 DETAILED DESCRIPTION OF THE INVENTIO~7 12 As indicated, supra, the present invention relates 13 to an improved process for liquefying coal and similar so-1~ lid carbonaceous materials such as trash, coke and the iik~
wherein the yield of liquid products is increased ir a more 16 thermally efficient manner and a normally solid bottoms 17 product containing less reactive carbon produced thereby.
18 The liquefaction is accomplished at an elevated temperature l9 and pressure and in the presence of a hydrogen donor sol-vent which is prepared from a portion of the liquefaction 21 liquid product. At least a portion of the hydrogen donor 22 solvent used during liquefaction will be used to extract 23 the normally solid bottoms product obtained from the lique-24 faction and at least a portion of the carbonaceous materials extracted from the normally solid bottoms product will be 26 present during liquefaction.
27 In general, the method of the present invention can 28 be used to liquefy any solid carbonaceous material which 29 can, effectively, be hydrogenated and liquefied. Such solid carbonaceous materials include, but are not necessarily 31 limited to, coal, ~rash, biomass, coke and the like. The 32 ~ethod of this invention is particularly useful in the li-33 quefaction of coal and may be used to liquefy any of the 34 coals known in the prior art including anthracite, bitumi-nous coal, subbituminous coal, lignite, peat, brown coal 36 and the like.
3 .~ ~ 7 1 In general, the solid carbonaceous material will be 2 ground to a finely ~ivided state. The particular particle 3 size or particle size range, actually employed, however, is not critical to the invention and, indeed, essentially any particle size can be employed. Notwithstanding this, 6 generally, the solid carbonaceous material which is lique-7 fied in accordance with this invention, will be ground to 8 a particle size of less than 1/4 inch and preferably to a 9 particle size of less than about 8 mesh (M.B.S.Sieve slze).
After the solid carbonaceous material has been si~e~
11 the same will be slurried with a hydrogen donor solvent.
12 As indicated more fully hereinafter, at least a portion of 13 the hydrogen donor solvent used in preparing the slurry wlll 14 have been used to extract the normally solid bottoms product 1~ from the liquefaction step. In general, the solid carbona-16 ceous material will be slurried with sufficient donor sol-17 vent to produce a slurry containing a solvent: solid car-18 bonaceous material ratio within the range from about 0.8:1 19 to about 10:1 on a weight basis. As used herein the reci-tation hydrogen donor solvent shall mean a hydrogen donor 21 solvent produced from a portion o~ the liquefaction liquid 22 product and will include any non-donor species that might 23 be contained therein.
24 The hydrogen donor solvent used in the process of this invention may be any portion of the liquefaction pro-26 duct from liquefaction containiny at least about 0.8 weight 27 percent of donatable hydrogen based on the weight of total 28 solvent or which can be treated to contain at least about 29 0.8 weight percent of donatable hydrogen based on the weight of total solvent. Particularly effective solvents are dis-31 tillate fractions cut from the liquefaction product and 32 having an initial boiling point within the range from about 33 350F to about 425F and a final boiling point within the 34 range from about 700 to about 900F. Generally, these fractions will not contain at least about 0.8 weight percent 36 of donatable hydrogen based on the weight of total solvent 37 but do contain sufficient aromatic concentrations as to 1 permit the production of a suitable hydrogen donor solvent 2 by hydrogenating at least a portion of the aromatics to a 3 corresponding hydroaromatic compound. In this regard, it 4 should be noted that compounds capable of donating hydro-gen during liquefaction are well-known in the prior art 6 and many are described in U.S. Patent 3,867,275. Compounds 7 capable of donating hydrogen during liquefaction include 8 the indanes, the dihydroflourines, the ~10-Cl2 tetra-hydrc-9 naphathalenes, the hexahydrofluorenes, the dehydro-, tetra-hydrohexahydro-, and octohydrophenanthrenes, the C12-C13 11 acenaphthenes, the tetrahydro-, hexahydro-, and decahydro-12 pyrenes, the di-, tetra-, and octahydroanthracenes, and 13 other derivatives oE partially saturated aromatic compounds.
14 As is also well-]cnown in the prior art, hydrogenation of various coal liquefaction liquid products will produce one 16 or more of these known hydrogen donor compounds.
17 During start-up of the process of this invention and 18 while solvent produced from the solid carbonaceousmaterials 19 subjected to liquefaction is not available the process may be started~up or operated with any of the known hydrogen 21 donor compounds mentioned above. Either as a pure compound 22 or as a mixture of such compounds either alone or in com-23 bination with components which will not donate hydrogen at 24 liquefaction conditions. Hydrogenated creosote oil may also be used during start-up or at other times when a sol-26 vent derived from the solid carbonaceous material subject 27 to liquefaction is not available. Generally, the creosote 28 oil will be hydrogenated in the same manner as is the sol-29 vent derived from the solid carbonaceous materials sub-jected to l.iquefaction, which method is described infurther 31 detail hereinafter. After the solid carbonaceous material 32 has been slurried, the slurry will then be subjected to 33 liquefaction at a temperature within the range from about 34 700 to about 950F and at a pressure within the range from about 800 to about 3000 psig. In general, from about 20 to 36 about 100 weight percent of the total solvent used in 1 preparing the slurry will have first been used to extract 2 reactive bottoms from the normally solid bottoms product 3 produced during liquefaction. This solvent will contain 4 from about 5 to 50 weight percent reactive bot-toms. The liquefaction will, therefore, be accomplished in the 6 presence of from about 0.05 to 0.5 parts of reactive bot-7 toms per part o~ coal, based on weight. During liquefac-8 tion, the reactlve bottoms will be converted to gaseous 9 and liquid products thereby increasing the total conversion o-E solid carbonaceous material and the yield of normally 11 liquid products.
12 During liquefaction, the solid carbonaceous material 13 will be converted in part to a normally gaseous product, 14 and part to a normally liquid product, and in part, to a normally solid bottoms product. In general, the normally 16 solid bottoms product will have an initial boiling point 17 within the range of about 900F to about 1100F and will 18 contain unconverted carbonaceous material, inorganic mate-19 rial and high boiling ;~llt convc~tod ca^bonaceous matelial.
Generally, the higl~ boiling, bu- con~Terted carbonaceous 21 material could be further reduced in molecular weight 22 if the bottoms were subjected to further liquefaction or 23 if the entire bottoms were recycled. Similarly, at least 24 a portion of the unconverted material could be converted if the bottoms were subjected to further liquefaction or if 26 the bottoms were recycled to a liquefaction stage. The 27 more difficult to convert portion of the unconverted car-28 bonaceous material (fusinite) would not, normally, be con-29 verted through further liquefaction or recycle of the bot-toms. Similarly, the inorganic material (ash) would not be 31 converted through further liquefaction of the bottoms or 32 via recycle thereof.
33 It has now surprisingly been discovered that a sub-34 stantial portion of the reactive materlal; i.e., normally solid carbonaceous material which could be converted to 36 either a gaseous or liquid product when subjected to further 37 liquefaction or recycled to a liquefaction stage, can be 38 separated from the nonreactive portion of the normally l solid bottoms product; viz., the ash and fusinite, by 2 extractlon of the bottoms with a donor solvent and parti-3 culaxly a donor solvent derived from the solid carbona-4 ceous material being subjected to liquefaction. The ex-traction may be accomplished at relatively mild conditions 6 and the extracted reactive portion of the normally solid 7 bottoms product further converted by recycling the same 8 to one or more of the liquefaction stages. The further 9 conversion of -the reactive portion of the normally solid bottoms product will, then, be accomplished with les, ll energy than would be required to subject the normally 12 solid bottoms product to further liquefaction in a se~a-13 rate stage and with less energy than would be required to 14 recycle the entire normally solid bottoms product. ~he process of this invention is, therefore, more energy effi-16 cient than processes heretofore proposed in the prior art.
17 In general, the extraction will be accomplished at 18 a temperature within the range from about 50 to about l9 600F and at a pressure within the range Erom about 0 to a-bout 750 psig. The extraction may be accomplished withany 21 suitable means known in the prior art to be effective for 22 the extraction of a soluble or extractable portion of a 23 normally solid material with a liquid. In general, the 24 extraction will be accomplished in a well-mixed vessel so as to insure good contact between the normally solid bot-26 toms product and the solvent used during extraction. The 27 solvent containing the extracted portion of the normally 28 solid bottoms product can then be separated from the rela-29 tively unreactive portion of the normally solid bottoms product by any suitable means such as decanting, centrifu-31 gation, filtration or the like. Of these, decanting after 32 a gravitational separation is most pr~ferred since less 33 energy is required for this particular mode of separation.
34 Following the separation, the solvent portion may be used directly in the preparation of a slurry of the solid car-36 bonaceous material to be subjected to liquefaction. Any 37 solvent that might be entrained in the ash and fusinite i7 g 1 rich rafflnate stream could be removed by flash vapori~
2 ~ation or by displacement with water. The remaining bot-3 toms, especially when the carbon content thereof is rela-4 tively low, could be discarded. For maximum efficiency, however, it is believed mostexpedient to either subject 6 the ash and fusinite rich raffinate to combustion so as to 7 recover the fuel value thereof or to subject the same to 8 gasification to produce a gas containing hydrogen which 9 could then be used to effect the liquefaction and hydroge-nation of the solvent fraction. When a partial oxidation 11 process is used to effect the gasification, displacement 12 of entrained solvent with water would offer certain advan-13 tages.
14 As indicated previously, the liquefaction will, generally be accomplished at a temperature within the 16 range from about 700 to about 900~F and at a pressure with-17 in the range from about 800 to 3000 psig. Any number of 18 liquefaction stages or zones may be used to effect the 19 liquefaction but a single stage is generally preferred since this reduces the initial investment cost and the 21 energy requirement for effecting the liquefaction. The 22 total nominal holding time required is that sufficient to 23 effect at least a partial liquefaction of the solid carbona-24 ceous material and will, generally, range from about 10 to about 200 minutes.
26 As also indicated previously, the liquefaction will 27 result in the production of a gaseous product, a normally 28 liquid product and a normally solid bottoms product. After 29 liquefaction, these products may be separated into respec-tive phases using conventional techniques. For example, the 31 gaseous products r,lay be flashed overhead and the liquid and 32 solids then separated using filtration, centrifugatiorl or 33 distillation. OE these, distillation is preferred.
34 After separation, the gaseous product may be upgraded to a pipeline gas or the same may be burned to provide ener-36 gy for the liquefaction process. Alternatively, all or a 1 portion of the gaseous product may be re~ormed to provide 2 hydrogen for the liquefaction process.
3 The liquid product may be fractioned into essen-4 tially any desired product distribution and/or a portion thereof may also be used directly as a fuel or upgraded 6 using conventional techniques. In accordance with the pre-7 senk invention, a portion of the liquid product will be 8 separated and used as a solvent or diluent in the liquefac-9 tion process of this invention. This portion of the liquid product will be hydrogenated to increase the amount of 11 donatable hydrogen therein prior to its use as a solvert or 12 diluent. Generally, a naptha fraction will be recovered 13 and the naptha fraction will be further processed to yieId 14 a high quality gasoline or similar fuel boiling in the nap tha range.
16 Finally, in accordance with the improvement of this 17 invention, at least a portion of the normally solid bottoms 1~ product will be withdrawn, extracted by contacting with at 19 least a portion of the solvent separated from the liquid product and this solvent containing the extracted components 21 from the normally solid bottoms product will be used in the 22 preparation of a solid carbonaceous material slurry which 23 is, ultimately, subjected to liquefaction in the process 24 of this invention. In general, from about 1 to about 6 parks of solvent or diluent per part of normally solid bot 26 toms product, by weight, will be contacted with the bottoms 27 product in the extraction step. As a result of this extrac-28 tion, from about 20 to about 80 weight percent of the reac-29 kive portion of the bottoms will be separated from the normally solid bottoms product during extraction. Slurry 31 preparakion will then be controlled to provide from about 32 0.05 to about 0.5 parts of "reactive" components per part 33 of solid carbonaceous material fed to the liquefaction 34 stage or zone.
PREFERRED EMBODIMENT
36 In a preferred embodiment of the present invention, 37 a coal will be liquefied in a single stage liquefaction 1 operation in a temperature within the range from about 2 80 to about 880F, and at a pressure within the range from 3 about 1500 to about 2000 psig. In the preferred embodiment, 4 the coal will be slurried with a solvent or diluent cut from the coal li~uefaction liquid product and hydrogenated 6 such that the solvent contains at least 45 weight percent 7 hydrogen donor species and contains at least 1.25 weight 8 percent donatable hydrogen. All of the-solvent used in 9 preparing the slurry will have been used to extractrea~tive material from the normally solid bottoms product produced 11 during liquefaction. The slurry after preparation will 12 contain from about 0.1 to about 0.3 parts of reactive 13 material from the bottoms per part of coal when fed to the 14 liquefaction stage or zone. The solvent to coal ratio in the slurry will be within tlle range from about 1:1 to 16 about 5:1. The nominal holding time during liquefaction 17 will be within the range from about 40 to about 140 minute~
18 In a preerred embodiment, the extrac~ion will be accom-19 plished at a temperature within the range from about 100 to about 400F and at a pressure within the range from 0 to 21 about 500 psig. The contacting between the solvent and 22 ~he normally solid bottoms product will be accomplished in 23 a countercurrent bafEled contacting vessel at a solvent to 24 normally solid bottoms product ratio within the range from about 4:1 to about 8:1 (v/v). In the preferred embodiment, 26 the baffled contacting vessel will be disposed vertically 27 with the solvent flowing upwardly and with the normally 28 solid bottoms product settling downwardly. The solvent will 29 then be withdrawn at or near the top of the baffled con-tacting vessel and the normally solid bottoms product free 31 of extracted reactive material will be withdrawn at or near 32 the bottom.
33 It is believed that the invention will be better 34 understood by reEerence to the attached Figure 1 which il-lustrates a particularly preferred embodiment. Referring 36 then to Figure 1, a finely divided coal or similar solid 37 carbonaceous material is lntroduced into mixing vessel 10 3~3~3~
1 through line ll and slurried with a hydroyen donor solvent 2 or diluent introduced throuyh line 12. In a preferred em-3 bodiment, the solvent will be all or a portion of a distil-4 late fraction cut from the liquefaction liquid product, which fraction will be hydrogenated to produce a solvent 6 containing at least 45 weight percent hydrogen donor species 7 and which will be used in the extraction of reactive solid 8 carbonaceous materials from the normally solid bottoms pro-9 duct. When all of the solvent is not used in the extraction step, any additional solvent required to effect the lique-ll faction may be recycled through line 13. ~uring start-up, 12 however, or when a recycle solvent is not available, any of 13 the known useful hydrogen donor solvents or diluents may be 14 introduced into line 13 through line 14.
In mixing vessel lO and after normally solid bo~toms 16 product is available, the coal or similar solid carbonaceous 17 material will also be mixed with reactive material extracted 18 ~rom said bottoms. In the embodiment illustrated, the reac-19 tive material will be contained in the solvent fed into 20 mixing vessel 10 through line 12. In the preferred embodi-21 ment, the reactive material and solid carbonaceous material 22 will be combined in a ratio within the range from about 23 0.1:1 to about 0.3:1 by weight. The reactive material and 2~ solid carbonaceous material will be combined with sufficient 25 solvent including that used in the extraction step and in-26 troduced into mixing vessel 10 through line 12 to produce a27 slurry wherein the solvent-to-solid carbonaceous material 28 ratio is within the range from ~:1 to about 8:1.
29 In the embodiment illustrated, the slurry is with-30 drawn from mixing vessel lO through line 16 and passed 31 through preheater 17. In the preheater 17 the slurry will, 32 generally, be preheated to the desired temperature and gen-33 erally to a temperature of about 50 to about 100F below the 34 temperature at which liquefaction is accomplished. When de-35 sired, and particularly when the solid carbonaceous material 36 has not been previously dried, steam will be flashed over-37 head through line 18.
1 In gene.ral, the s:Lurry of solid carbonaceous 2 material will be combined with molecular hydrogen. In a 3 preferred embodiment, the molecular hydrogen will be added 4 prior to preheating through line 19. This is not, however, critical, and the hydrogen could be added downstream of pre-6 heater 17 or added directly into the liquefaction vessel.
7 In any case, the hydrogen will be introduced after the 8 steam is flashed overhead. In the preferred embodiment, the 9 hydrogen will be produced either by the steam reforming of product gas from the liquefaction; by gasification of the 11 nonreactive portion of the solid bottoms product or by gasi-12 fication of solid carbonaceous material in a separate step, 13 all in accordance with conventional technology. In general, 14 su~ficient hydrogen will be introduced to provide from about 2 to about 10 weight percent, preferably from about 3 to 16 about 8 weight percent, molecular hydrogen based on dry, 17 solid carbonaceous material.
18 The slurry is withdrawn from the preheater through 19 line 20 and passed directly to liquefaction vessel 21~ In the liquefaction vessel 21, the solid carbonaceous material 21 is at least partially liquefied and, generally, at least 22 partially gasified, generally, in the absence of any added 23 catalyst. Preferably, the liquefaction vessel will be sized 2~ so as to provide a nominal holding time within the range 25 from about 40 to about 140 minutes and in a preferred embo-26 diment, a single vessel will be employed. Also, the temper-27 ature within the liquefaction zone 21 will, preferably, be 28 within th~ range from about 800 to about 880F and the 29 pressure will be, preferably, controlled within the range 30 from about 1500 to abou t 2000 psig.
31 In the embodiment illustrated, the combined product 32 from liquefaction vessel 21 is withdrawn through line 22 and 33 passed to separating means 23. In the embodiment illustrat-34 ed, the separating means may be a combined atmospheric and 35 vacuum distillation column wherein gaseous products and pro-36 ducts boiling below the naphtha boiling range are withdrawn 37 overhead through line 24 while a bottoms product comprising .fl~
1 unconverted solid carbonaceous material, mineral matter and 2 converted materials having an initial boiling point within 3 the range from about 950~F to about 1050F i5 withdrawn 4 through line 25. The liquid product is then fractionated
21 Operation in this manner, however, reduces the yield of 22 normally liquid products, thereby reducing thermal effi-23 ciency, and increases both investment and operating costs 24 for essentially the same reasons already noted with respect to staged or further liquefaction. Finally, it has been 26 proposed, heretofore, to separate the unreactive and fusi-27 nite portions of the bottoms from the reactive portion 28 thereof by extraction. Generally, however, these operations 29 depend upon the use of a relatively expensive solvent (such as toluene) which must then be separated from the extract, 31 generally, hy vaporization. This type of operation too has 32 proven expensive due primarily to the high energy require-33 ment for separation of the solvent.
34 In light of the ~oregoing, the need for a liquefac-3~ tlon process which can be operated in a mode requiring fewer 36 liquefaction stages at an increased thermal efficiency to 37 yield a normally solid, bottoms product relatively low in J~ ~
1 carbon, which product may be discarded, i.s believed 2 readily apparent. More part:icularly, the need for a lique-3 faction process wherein a significant portion of the carbon 4 contained in the normally solid, bottoTnsproduct can be efficiently recovered via extraction is believed to be 6 readily apparent.
8 It has now been discovered that the foregoing and 9 other disadvantages of the prior art processes can be re-duced with the method of .he present invention and an im-11 proved liquefaction process provided thereby. It is, 12 therefore, an object of this invention to provide an im-13 proved liquefaction process wherein the yield of liquid 14 product is increased without further liquefaction at ele-vated temperatures and pressures and without recycling the 16 inactive and fusinite portions of the normally solid, bot-17 tom product which preferably can be discarded~directly, 18 after an extraction operation with a reduced impact on pro-19 cess economics and thermal efficiency. The foregoing and other objects and advantages will become apparent from the 21 description set forth hereinafter and from the drawings 22 appended thereto.
23 In accordance with the present invention, the fore-24 going and other objects and advantages are accomplished by liquefying a coal or similar solid carbonaceous material in 26 the presence of a hydrogen donor solvent at elevated tem-27 peratures and pressures and thereafter extracting at least 28 a portion of the reactive bottoms from the normally solid 29 bottoms product. The extraction will be accomplished with a hydrogen donor solvent derived from the solid carbonaceous 31 material subjected to liquefaction. The raffinate from the 32 extraction, without separation of the solvent, will be re-33 cycled to the liquefaction sta~e thereby increasing the 34 overall liquid yield of the process. The normally solid bottoms product remaining after extraction will contain less 36 carbon than the feed to the extraction step and may be dis-37 carded, directly, with less adverse impact on economics ~Llr:b~3~
l than would be the case lf the original, unextracted nor-2 mally solid bottoms product were discarded. As indicated 3 more fully hereinafter, however, maximum conversion of the 4 solid carbonaceous material and maximum thermal efficiency will be realized either by burning the remaining normally 6 solid bottoms product or by further treating the same to 7 produce a useful EuelO
8 BRIEF DESCRIPTION OF T~IE DRAWING
9 The figure is a schematic flow diagram of a process within the scope of the present invention.
11 DETAILED DESCRIPTION OF THE INVENTIO~7 12 As indicated, supra, the present invention relates 13 to an improved process for liquefying coal and similar so-1~ lid carbonaceous materials such as trash, coke and the iik~
wherein the yield of liquid products is increased ir a more 16 thermally efficient manner and a normally solid bottoms 17 product containing less reactive carbon produced thereby.
18 The liquefaction is accomplished at an elevated temperature l9 and pressure and in the presence of a hydrogen donor sol-vent which is prepared from a portion of the liquefaction 21 liquid product. At least a portion of the hydrogen donor 22 solvent used during liquefaction will be used to extract 23 the normally solid bottoms product obtained from the lique-24 faction and at least a portion of the carbonaceous materials extracted from the normally solid bottoms product will be 26 present during liquefaction.
27 In general, the method of the present invention can 28 be used to liquefy any solid carbonaceous material which 29 can, effectively, be hydrogenated and liquefied. Such solid carbonaceous materials include, but are not necessarily 31 limited to, coal, ~rash, biomass, coke and the like. The 32 ~ethod of this invention is particularly useful in the li-33 quefaction of coal and may be used to liquefy any of the 34 coals known in the prior art including anthracite, bitumi-nous coal, subbituminous coal, lignite, peat, brown coal 36 and the like.
3 .~ ~ 7 1 In general, the solid carbonaceous material will be 2 ground to a finely ~ivided state. The particular particle 3 size or particle size range, actually employed, however, is not critical to the invention and, indeed, essentially any particle size can be employed. Notwithstanding this, 6 generally, the solid carbonaceous material which is lique-7 fied in accordance with this invention, will be ground to 8 a particle size of less than 1/4 inch and preferably to a 9 particle size of less than about 8 mesh (M.B.S.Sieve slze).
After the solid carbonaceous material has been si~e~
11 the same will be slurried with a hydrogen donor solvent.
12 As indicated more fully hereinafter, at least a portion of 13 the hydrogen donor solvent used in preparing the slurry wlll 14 have been used to extract the normally solid bottoms product 1~ from the liquefaction step. In general, the solid carbona-16 ceous material will be slurried with sufficient donor sol-17 vent to produce a slurry containing a solvent: solid car-18 bonaceous material ratio within the range from about 0.8:1 19 to about 10:1 on a weight basis. As used herein the reci-tation hydrogen donor solvent shall mean a hydrogen donor 21 solvent produced from a portion o~ the liquefaction liquid 22 product and will include any non-donor species that might 23 be contained therein.
24 The hydrogen donor solvent used in the process of this invention may be any portion of the liquefaction pro-26 duct from liquefaction containiny at least about 0.8 weight 27 percent of donatable hydrogen based on the weight of total 28 solvent or which can be treated to contain at least about 29 0.8 weight percent of donatable hydrogen based on the weight of total solvent. Particularly effective solvents are dis-31 tillate fractions cut from the liquefaction product and 32 having an initial boiling point within the range from about 33 350F to about 425F and a final boiling point within the 34 range from about 700 to about 900F. Generally, these fractions will not contain at least about 0.8 weight percent 36 of donatable hydrogen based on the weight of total solvent 37 but do contain sufficient aromatic concentrations as to 1 permit the production of a suitable hydrogen donor solvent 2 by hydrogenating at least a portion of the aromatics to a 3 corresponding hydroaromatic compound. In this regard, it 4 should be noted that compounds capable of donating hydro-gen during liquefaction are well-known in the prior art 6 and many are described in U.S. Patent 3,867,275. Compounds 7 capable of donating hydrogen during liquefaction include 8 the indanes, the dihydroflourines, the ~10-Cl2 tetra-hydrc-9 naphathalenes, the hexahydrofluorenes, the dehydro-, tetra-hydrohexahydro-, and octohydrophenanthrenes, the C12-C13 11 acenaphthenes, the tetrahydro-, hexahydro-, and decahydro-12 pyrenes, the di-, tetra-, and octahydroanthracenes, and 13 other derivatives oE partially saturated aromatic compounds.
14 As is also well-]cnown in the prior art, hydrogenation of various coal liquefaction liquid products will produce one 16 or more of these known hydrogen donor compounds.
17 During start-up of the process of this invention and 18 while solvent produced from the solid carbonaceousmaterials 19 subjected to liquefaction is not available the process may be started~up or operated with any of the known hydrogen 21 donor compounds mentioned above. Either as a pure compound 22 or as a mixture of such compounds either alone or in com-23 bination with components which will not donate hydrogen at 24 liquefaction conditions. Hydrogenated creosote oil may also be used during start-up or at other times when a sol-26 vent derived from the solid carbonaceous material subject 27 to liquefaction is not available. Generally, the creosote 28 oil will be hydrogenated in the same manner as is the sol-29 vent derived from the solid carbonaceous materials sub-jected to l.iquefaction, which method is described infurther 31 detail hereinafter. After the solid carbonaceous material 32 has been slurried, the slurry will then be subjected to 33 liquefaction at a temperature within the range from about 34 700 to about 950F and at a pressure within the range from about 800 to about 3000 psig. In general, from about 20 to 36 about 100 weight percent of the total solvent used in 1 preparing the slurry will have first been used to extract 2 reactive bottoms from the normally solid bottoms product 3 produced during liquefaction. This solvent will contain 4 from about 5 to 50 weight percent reactive bot-toms. The liquefaction will, therefore, be accomplished in the 6 presence of from about 0.05 to 0.5 parts of reactive bot-7 toms per part o~ coal, based on weight. During liquefac-8 tion, the reactlve bottoms will be converted to gaseous 9 and liquid products thereby increasing the total conversion o-E solid carbonaceous material and the yield of normally 11 liquid products.
12 During liquefaction, the solid carbonaceous material 13 will be converted in part to a normally gaseous product, 14 and part to a normally liquid product, and in part, to a normally solid bottoms product. In general, the normally 16 solid bottoms product will have an initial boiling point 17 within the range of about 900F to about 1100F and will 18 contain unconverted carbonaceous material, inorganic mate-19 rial and high boiling ;~llt convc~tod ca^bonaceous matelial.
Generally, the higl~ boiling, bu- con~Terted carbonaceous 21 material could be further reduced in molecular weight 22 if the bottoms were subjected to further liquefaction or 23 if the entire bottoms were recycled. Similarly, at least 24 a portion of the unconverted material could be converted if the bottoms were subjected to further liquefaction or if 26 the bottoms were recycled to a liquefaction stage. The 27 more difficult to convert portion of the unconverted car-28 bonaceous material (fusinite) would not, normally, be con-29 verted through further liquefaction or recycle of the bot-toms. Similarly, the inorganic material (ash) would not be 31 converted through further liquefaction of the bottoms or 32 via recycle thereof.
33 It has now surprisingly been discovered that a sub-34 stantial portion of the reactive materlal; i.e., normally solid carbonaceous material which could be converted to 36 either a gaseous or liquid product when subjected to further 37 liquefaction or recycled to a liquefaction stage, can be 38 separated from the nonreactive portion of the normally l solid bottoms product; viz., the ash and fusinite, by 2 extractlon of the bottoms with a donor solvent and parti-3 culaxly a donor solvent derived from the solid carbona-4 ceous material being subjected to liquefaction. The ex-traction may be accomplished at relatively mild conditions 6 and the extracted reactive portion of the normally solid 7 bottoms product further converted by recycling the same 8 to one or more of the liquefaction stages. The further 9 conversion of -the reactive portion of the normally solid bottoms product will, then, be accomplished with les, ll energy than would be required to subject the normally 12 solid bottoms product to further liquefaction in a se~a-13 rate stage and with less energy than would be required to 14 recycle the entire normally solid bottoms product. ~he process of this invention is, therefore, more energy effi-16 cient than processes heretofore proposed in the prior art.
17 In general, the extraction will be accomplished at 18 a temperature within the range from about 50 to about l9 600F and at a pressure within the range Erom about 0 to a-bout 750 psig. The extraction may be accomplished withany 21 suitable means known in the prior art to be effective for 22 the extraction of a soluble or extractable portion of a 23 normally solid material with a liquid. In general, the 24 extraction will be accomplished in a well-mixed vessel so as to insure good contact between the normally solid bot-26 toms product and the solvent used during extraction. The 27 solvent containing the extracted portion of the normally 28 solid bottoms product can then be separated from the rela-29 tively unreactive portion of the normally solid bottoms product by any suitable means such as decanting, centrifu-31 gation, filtration or the like. Of these, decanting after 32 a gravitational separation is most pr~ferred since less 33 energy is required for this particular mode of separation.
34 Following the separation, the solvent portion may be used directly in the preparation of a slurry of the solid car-36 bonaceous material to be subjected to liquefaction. Any 37 solvent that might be entrained in the ash and fusinite i7 g 1 rich rafflnate stream could be removed by flash vapori~
2 ~ation or by displacement with water. The remaining bot-3 toms, especially when the carbon content thereof is rela-4 tively low, could be discarded. For maximum efficiency, however, it is believed mostexpedient to either subject 6 the ash and fusinite rich raffinate to combustion so as to 7 recover the fuel value thereof or to subject the same to 8 gasification to produce a gas containing hydrogen which 9 could then be used to effect the liquefaction and hydroge-nation of the solvent fraction. When a partial oxidation 11 process is used to effect the gasification, displacement 12 of entrained solvent with water would offer certain advan-13 tages.
14 As indicated previously, the liquefaction will, generally be accomplished at a temperature within the 16 range from about 700 to about 900~F and at a pressure with-17 in the range from about 800 to 3000 psig. Any number of 18 liquefaction stages or zones may be used to effect the 19 liquefaction but a single stage is generally preferred since this reduces the initial investment cost and the 21 energy requirement for effecting the liquefaction. The 22 total nominal holding time required is that sufficient to 23 effect at least a partial liquefaction of the solid carbona-24 ceous material and will, generally, range from about 10 to about 200 minutes.
26 As also indicated previously, the liquefaction will 27 result in the production of a gaseous product, a normally 28 liquid product and a normally solid bottoms product. After 29 liquefaction, these products may be separated into respec-tive phases using conventional techniques. For example, the 31 gaseous products r,lay be flashed overhead and the liquid and 32 solids then separated using filtration, centrifugatiorl or 33 distillation. OE these, distillation is preferred.
34 After separation, the gaseous product may be upgraded to a pipeline gas or the same may be burned to provide ener-36 gy for the liquefaction process. Alternatively, all or a 1 portion of the gaseous product may be re~ormed to provide 2 hydrogen for the liquefaction process.
3 The liquid product may be fractioned into essen-4 tially any desired product distribution and/or a portion thereof may also be used directly as a fuel or upgraded 6 using conventional techniques. In accordance with the pre-7 senk invention, a portion of the liquid product will be 8 separated and used as a solvent or diluent in the liquefac-9 tion process of this invention. This portion of the liquid product will be hydrogenated to increase the amount of 11 donatable hydrogen therein prior to its use as a solvert or 12 diluent. Generally, a naptha fraction will be recovered 13 and the naptha fraction will be further processed to yieId 14 a high quality gasoline or similar fuel boiling in the nap tha range.
16 Finally, in accordance with the improvement of this 17 invention, at least a portion of the normally solid bottoms 1~ product will be withdrawn, extracted by contacting with at 19 least a portion of the solvent separated from the liquid product and this solvent containing the extracted components 21 from the normally solid bottoms product will be used in the 22 preparation of a solid carbonaceous material slurry which 23 is, ultimately, subjected to liquefaction in the process 24 of this invention. In general, from about 1 to about 6 parks of solvent or diluent per part of normally solid bot 26 toms product, by weight, will be contacted with the bottoms 27 product in the extraction step. As a result of this extrac-28 tion, from about 20 to about 80 weight percent of the reac-29 kive portion of the bottoms will be separated from the normally solid bottoms product during extraction. Slurry 31 preparakion will then be controlled to provide from about 32 0.05 to about 0.5 parts of "reactive" components per part 33 of solid carbonaceous material fed to the liquefaction 34 stage or zone.
PREFERRED EMBODIMENT
36 In a preferred embodiment of the present invention, 37 a coal will be liquefied in a single stage liquefaction 1 operation in a temperature within the range from about 2 80 to about 880F, and at a pressure within the range from 3 about 1500 to about 2000 psig. In the preferred embodiment, 4 the coal will be slurried with a solvent or diluent cut from the coal li~uefaction liquid product and hydrogenated 6 such that the solvent contains at least 45 weight percent 7 hydrogen donor species and contains at least 1.25 weight 8 percent donatable hydrogen. All of the-solvent used in 9 preparing the slurry will have been used to extractrea~tive material from the normally solid bottoms product produced 11 during liquefaction. The slurry after preparation will 12 contain from about 0.1 to about 0.3 parts of reactive 13 material from the bottoms per part of coal when fed to the 14 liquefaction stage or zone. The solvent to coal ratio in the slurry will be within tlle range from about 1:1 to 16 about 5:1. The nominal holding time during liquefaction 17 will be within the range from about 40 to about 140 minute~
18 In a preerred embodiment, the extrac~ion will be accom-19 plished at a temperature within the range from about 100 to about 400F and at a pressure within the range from 0 to 21 about 500 psig. The contacting between the solvent and 22 ~he normally solid bottoms product will be accomplished in 23 a countercurrent bafEled contacting vessel at a solvent to 24 normally solid bottoms product ratio within the range from about 4:1 to about 8:1 (v/v). In the preferred embodiment, 26 the baffled contacting vessel will be disposed vertically 27 with the solvent flowing upwardly and with the normally 28 solid bottoms product settling downwardly. The solvent will 29 then be withdrawn at or near the top of the baffled con-tacting vessel and the normally solid bottoms product free 31 of extracted reactive material will be withdrawn at or near 32 the bottom.
33 It is believed that the invention will be better 34 understood by reEerence to the attached Figure 1 which il-lustrates a particularly preferred embodiment. Referring 36 then to Figure 1, a finely divided coal or similar solid 37 carbonaceous material is lntroduced into mixing vessel 10 3~3~3~
1 through line ll and slurried with a hydroyen donor solvent 2 or diluent introduced throuyh line 12. In a preferred em-3 bodiment, the solvent will be all or a portion of a distil-4 late fraction cut from the liquefaction liquid product, which fraction will be hydrogenated to produce a solvent 6 containing at least 45 weight percent hydrogen donor species 7 and which will be used in the extraction of reactive solid 8 carbonaceous materials from the normally solid bottoms pro-9 duct. When all of the solvent is not used in the extraction step, any additional solvent required to effect the lique-ll faction may be recycled through line 13. ~uring start-up, 12 however, or when a recycle solvent is not available, any of 13 the known useful hydrogen donor solvents or diluents may be 14 introduced into line 13 through line 14.
In mixing vessel lO and after normally solid bo~toms 16 product is available, the coal or similar solid carbonaceous 17 material will also be mixed with reactive material extracted 18 ~rom said bottoms. In the embodiment illustrated, the reac-19 tive material will be contained in the solvent fed into 20 mixing vessel 10 through line 12. In the preferred embodi-21 ment, the reactive material and solid carbonaceous material 22 will be combined in a ratio within the range from about 23 0.1:1 to about 0.3:1 by weight. The reactive material and 2~ solid carbonaceous material will be combined with sufficient 25 solvent including that used in the extraction step and in-26 troduced into mixing vessel 10 through line 12 to produce a27 slurry wherein the solvent-to-solid carbonaceous material 28 ratio is within the range from ~:1 to about 8:1.
29 In the embodiment illustrated, the slurry is with-30 drawn from mixing vessel lO through line 16 and passed 31 through preheater 17. In the preheater 17 the slurry will, 32 generally, be preheated to the desired temperature and gen-33 erally to a temperature of about 50 to about 100F below the 34 temperature at which liquefaction is accomplished. When de-35 sired, and particularly when the solid carbonaceous material 36 has not been previously dried, steam will be flashed over-37 head through line 18.
1 In gene.ral, the s:Lurry of solid carbonaceous 2 material will be combined with molecular hydrogen. In a 3 preferred embodiment, the molecular hydrogen will be added 4 prior to preheating through line 19. This is not, however, critical, and the hydrogen could be added downstream of pre-6 heater 17 or added directly into the liquefaction vessel.
7 In any case, the hydrogen will be introduced after the 8 steam is flashed overhead. In the preferred embodiment, the 9 hydrogen will be produced either by the steam reforming of product gas from the liquefaction; by gasification of the 11 nonreactive portion of the solid bottoms product or by gasi-12 fication of solid carbonaceous material in a separate step, 13 all in accordance with conventional technology. In general, 14 su~ficient hydrogen will be introduced to provide from about 2 to about 10 weight percent, preferably from about 3 to 16 about 8 weight percent, molecular hydrogen based on dry, 17 solid carbonaceous material.
18 The slurry is withdrawn from the preheater through 19 line 20 and passed directly to liquefaction vessel 21~ In the liquefaction vessel 21, the solid carbonaceous material 21 is at least partially liquefied and, generally, at least 22 partially gasified, generally, in the absence of any added 23 catalyst. Preferably, the liquefaction vessel will be sized 2~ so as to provide a nominal holding time within the range 25 from about 40 to about 140 minutes and in a preferred embo-26 diment, a single vessel will be employed. Also, the temper-27 ature within the liquefaction zone 21 will, preferably, be 28 within th~ range from about 800 to about 880F and the 29 pressure will be, preferably, controlled within the range 30 from about 1500 to abou t 2000 psig.
31 In the embodiment illustrated, the combined product 32 from liquefaction vessel 21 is withdrawn through line 22 and 33 passed to separating means 23. In the embodiment illustrat-34 ed, the separating means may be a combined atmospheric and 35 vacuum distillation column wherein gaseous products and pro-36 ducts boiling below the naphtha boiling range are withdrawn 37 overhead through line 24 while a bottoms product comprising .fl~
1 unconverted solid carbonaceous material, mineral matter and 2 converted materials having an initial boiling point within 3 the range from about 950~F to about 1050F i5 withdrawn 4 through line 25. The liquid product is then fractionated
5 into desired fractions and in the embodiment illustrated, a
6 naphtha produc~ having an initial boillng point oE abou-t
7 150F and a final boiliny point within the range from about
8 350F to about 425F is withdrawn through line 26; a metal
9 distillate fraction having an initial boiling point within
10 ~he range from about 350~F to about 425F and a final boiling
11 point within the range from about 650F to about 850~ is
12 withdrawn through line 27 and a vacuum gas-oil fraction
13 having an initial boiling point within the range from about
14 650~ to about 850F and a final boiling point within the
15 range from about 950F to about 1050F is withdrawn through
16 line 280
17 In general, the overhead, gaseous material will com-
18 prise gaseous and lower hydrocarbons, steam, carbon oxides,
19 acid gases such as SO2 and H2S, any ammonia which may have
20 been produced during liquefaction and any hydrogen not con-
21 sumed during liquefaction. This stream may be scrubbed and
22 further divided to yield a high Btu gas, lighter hydrocarbons
23 and hydrogen. Generally, any nydrogen recovered from this
24 s-tream will be reused in either the liquefaction or hydrogen-
25 ation step. The naptha stream may be subjected to further
26 upgrading to yield a good quality gasoline and the heavier
27 stream withdrawn through line 28 may be upgraded to produce
28 a heavy fuel oil or hydrocracked and reformed to yield a
29 gasoline boiling fraction. Generally, the solvent boiling
30 range material or at least a portion thereof will be cataly-
31 tically hydrogenated to increase the concentration of hydro-
32 ~en.~donor species and at least a portion of the hydrogenated
33 fraction will then be used. to extract reactive material from
34 at least a portion of the normally solid bottoms product
35 withdrawn through line 25.
36 As indicated supra, the particular separation scheme
37 employed is not critical to the present invention and, indee~
3~7~
1 any of the separation techniques known in the prior art 2 could be used to affect a s~paration of the gaseous, liquid 3 and solld products. For example, the gaseous product could be flashed directly a'ter liquefaction and the liquid-solid mixture then subjected to spearation via distillation, 6 filtration, extractior., centrifugation or the like. In any 7 case, however, a bottoms product containing unreacted coal, 8 mineral matter and high boiling hydrocarbons will be availa-9 ble for extraction with a solvent separated from the lique-faction product.
11 In the preferred embodiment, the solvent fraction 12 wi~hdrawn through line 27 will be hydrogenated before the 13 same is used either as the extraction solvent or the lique-14 faction solvent or diluent. Preferably, the hydrogenation 15 Will be accomplished catalytically at conditions known to 16 be effective or this purpose in the prior art. In the 17 embodiment illustrated, hydrogenation is accomplished ln 18 hydrogenation vessel 29 with molecular hydrogen intro~uced l9 through line 30O The hydrogen actually used may be from any source but in a preferred embodiment will be produced either 21 through the steam reforming of at least a portion of the 22 gaseous product from liquefaction, by gasification of at 23 least a portion of the normally solid bottoms product or by 24 the gasiication of a portion o the so]id carbonaceous 25 material being subjected to liqueaction. In the embodiment 26 illustrated, unreacted hydrogen and the gaseous products of 27 hydrogenation are withdrawn through line 31. When desired, 28 this gaseous product may be treated to recover recycle hy-29 drogen. Also in the embodiment illustrated, the hydrogena-tion product is withdrawn through line 32. The hydrog~na-31 tion product includes that portion of the solvent to be 32 used in the extraction step, that portion of the solvent, if 33 any, to be returned directly to mi~ing vessel 10 and any 34 excess solvent that may have been produced. That portion of 35 the hydrogenation product to be used as a solvent during e~-36 traction is withdrawn through line 39 and the rP~i ni ng por-37 tion of the hydrogenation product is withdrawn through line , -- 16 ~
1 32'. Any excess solvent may be withdrawn through line 33 2 as product or stored for future use during liquefaction~
3 That portion of the solvent, if any, fed directly to mixing 4 vessel 10 is recycled through line 13.
Normally, the hydrogenation will be accomplished at 6 a temperature within the range from about 600F to about 7 950F and a pressure within the range from about 650 to 3 about 2000 psig, preferably 1000 to 1500 psig. The hydro-9 gen treat rate during the hydrogenation general]y will be 10 within the range from about 1000 to about 10,000 scf/bbl.
11 Any of the known hydrogenation catalysts may be employed but 12 a nickel moly catalyst is most preferred.
13 In accordance with the improved method of the pre-14 sent invention, the bottoms product withdrawn through line 15 25 may be divided and all or a portion thereof subjected to 16 extraction. The portion to be subjected to extraction will 17 be withdrawn through line 34 and fed to contacting vessel 18 40. In a preferred embodiment, the entire normally solid 19 bottoms product will be passed through contacting vessel 40.
20 ~ny portion of the bottoms product not subjected to extrac-21 tion may be withdrawn through line 35 and processed in 22 accordance with conventional technology. In general, Erom 23 about 80 to about 100 weight percent of the bottoms product 24 will be subjected to extraction.
In contacting vessel 40 the fraction of hydrogenated 26 product from hydrogenation vessel 29 used as the extraction 27 solvent i5 introduced at or near the bottom oE contacting 28 vessel 40 and flows upwardly through the contacting vessel 29 and is withdrawn at or near the top thereof through line 41.
30 The bottoms introduced through line 34 flow generally down-31 wardly and are withdrawn from the contacting vessel at or 32 near the bottom thereof through line 34'. In the embodiment 33 illustrated, the solvent withdrawn through line 41 contain-34 ing the extracted reactive materials is then passed through 35 knock-out drum 42 to faciliate the separation of any unre-36 active materials contained ~ereinO The unreactive materials 37 will be separated from knock-out drum 42 throush line 43'.
1 The unreactive materials separated in the knock-out drum 2 may then be combined with unreact~Te materials separated 3 from the contacting vessel 40 in line 43 and introduced into 4 separator ~6. In the separator, entrained solvent may be flashed overhead and the remaining portion of the normally 6 solid bottoms product withdrawn through line ~8. The re-7 covered solvent, thoug~ not illustrated, may be combined 8 with solvent withdrawn from knock-out drum 42 or with sol-9 vent withdrawn from hydrogenation vessel 29 through line 32.
The solvent, generally free of unreactive materials, is 11 withdrawn from knock-out drum 42 through line 12 and fed to 12 mixing vessel 10. The remaining portion of the normally 13 solid bottoms product withdrawn through line 48 may be di-14 rectly discarded or otherwise treated in accordance with conventional technology to recover the energy value thereof.
16 As indicated, supra, and in a preferred embodiment, 17 the extraction will be accomplished at a temperature within 18 the range from about 100 to about 400~F and at a pressure 19 within the range from about 0 to about 500 psig~ In the 20 embodlment illustrated, the treat rate in contacting vessel 21 40 will be within the range from about 4 v/v/hour to 8 22 v/v/hour. Though not illustrated, contacting vessel 40 23 could be a stirred vessel and the entire solvent/normally 24 solid bottoms product could be withdrawn and passed to a 25 gravity separator. The major portion of the solvent could, 26 then, be separated by withdrawing the same from the decanting 27 vessel at a point above the solid level. Solvent entrained 28 in the remaining solids portion could then be separated in 29 the same manner as illustrated. When a stirred vessel is 30 employed, space velocity is not important but sufficient 31 contacting time should be allowed to insure that from about 32 20 to about 80 weight percent oE the reactive material is 33 separated from the normally solid bottoms product. The 34 reactive material thus separated is recovered with less ener-35 gy than would be required with the use of a more conventional 36 solvent such as toluene or the like which would, normally, be 3~
l separated and reused in the extraction operation rather t~an 2 as a solvent in the liquefaction step.
3 ~aving thus broadly described the present invention 4 and a preferred embodiment thereof, it is believed that the same will become more apparent by reference to the following 6 examples. It will be appreciated, however~ that the exam-7 ples are presented solely for purposes of illustration and 8 should not be construed as limiting the invention.
9 EXA~PLE 1 In this example, a run was completed in a 100 pound ll per day continuous unit usi~g an Illinois seam coal (Illi-12 nois No. 6) as the solid carbonaceous material and a hydro-13 genated recycle liquid havlng an initial boiling point of 14 about 400F and a final boiling point o-F about 800F and containing from about 40 to about 45 weight percent hydro-16 gen donor species was used as the e~traction solvent and 17 as the solvent or diluent for liquefaction. The unit was 18 operated in a mode similar to that illustrated in Fisure 1.
19 All of the solvent withdrawn from hydrogenation vessel 29 was used to extract bottoms from the separation vessel. As 21 withdrawn, the bottoms contain 40 weight percent of toluene 22 soluble material. The bottoms were extracted with the hy-23 drogen donor solvent at 300F and 0 psig with a nominal 24 contacting time of 5 minutes. After extraction, the re-m~;n;ng portion of the normally solid bottoms product con-26 tained lO weight percent toluene soluble material. Use of 27 the solvent intended for slurry preparation to extract the 28 bottoms therefore resulted in the recovery of about 75 29 weight percent of the reactive material from the bottoms and the gaseous and liquid product yields were increased 31 accordingly.
32 ExAMpLE~2 33 In this example, a run was completed in a lO0 pound 34 per day continuous unit using an l~yodak coal as the solid carbonaceous material and a hydrogenated recycle liquid 36 having an intial boiling point of about 400F and a final 37 boiling point of about 800F and containing from about 40 3~
1 to about 45 weight percent hydrogen donor species was used 2 as the extraction solvent and as the solvent or diluent for 3 liquefaction. The unit was operated in a mode similar to 4 that illustrated in Figure 1. All of the solvent withdrawn from hydrogenation vessel 29 was used to extract bottoms 6 from the separation vessel. As withdrawn, the bottoms con~
7 tain 50 weight percent of toluene soluble material. The 8 bottoms were extracted with the hydrogen donor solvent at 9 300~F and 0 psig with a nominal contacting time of 5minutes.
After extraction, the remaining portion of the normally so-11 lid bottoms product contained 10 weight percent toluene 12 soluble material. Use of the solvent intended for slurry 13 preparation to extract the bottoms therefore resulted in the 14 recovery of about ~0 weight percent of the reactive material from the bottoms and the gaseous and liquid product y~elds 16 were increased accordingly.
17 From the foregoing it will be apparent that the to-18 tal conversion of the coal was increased by about 10-15 19 weight percent and the yield of both gaseous and liquid pro-ducts was increased. This increase was, effectively, accom-21 p]ished with less equipment and less energy than would have 22 been required if an additional liquefaction stage were em-23 ployed, if the entire bottoms were recycled or if a solvent 24 had been used to extract the bottoms which would then have been separated via distillation.
26 While the present invention has been described and 27 illustrated by reference to particular embodiments thereof, 28 it will be appreciated by those of ordinary skill in the art 29 that the same lends itself to variations not necessarily illustrated herein. For this reason, then, reference should 31 be made solely to the appended claims for purposes of deter-32 mining the true scope of the present invention.
3~7~
1 any of the separation techniques known in the prior art 2 could be used to affect a s~paration of the gaseous, liquid 3 and solld products. For example, the gaseous product could be flashed directly a'ter liquefaction and the liquid-solid mixture then subjected to spearation via distillation, 6 filtration, extractior., centrifugation or the like. In any 7 case, however, a bottoms product containing unreacted coal, 8 mineral matter and high boiling hydrocarbons will be availa-9 ble for extraction with a solvent separated from the lique-faction product.
11 In the preferred embodiment, the solvent fraction 12 wi~hdrawn through line 27 will be hydrogenated before the 13 same is used either as the extraction solvent or the lique-14 faction solvent or diluent. Preferably, the hydrogenation 15 Will be accomplished catalytically at conditions known to 16 be effective or this purpose in the prior art. In the 17 embodiment illustrated, hydrogenation is accomplished ln 18 hydrogenation vessel 29 with molecular hydrogen intro~uced l9 through line 30O The hydrogen actually used may be from any source but in a preferred embodiment will be produced either 21 through the steam reforming of at least a portion of the 22 gaseous product from liquefaction, by gasification of at 23 least a portion of the normally solid bottoms product or by 24 the gasiication of a portion o the so]id carbonaceous 25 material being subjected to liqueaction. In the embodiment 26 illustrated, unreacted hydrogen and the gaseous products of 27 hydrogenation are withdrawn through line 31. When desired, 28 this gaseous product may be treated to recover recycle hy-29 drogen. Also in the embodiment illustrated, the hydrogena-tion product is withdrawn through line 32. The hydrog~na-31 tion product includes that portion of the solvent to be 32 used in the extraction step, that portion of the solvent, if 33 any, to be returned directly to mi~ing vessel 10 and any 34 excess solvent that may have been produced. That portion of 35 the hydrogenation product to be used as a solvent during e~-36 traction is withdrawn through line 39 and the rP~i ni ng por-37 tion of the hydrogenation product is withdrawn through line , -- 16 ~
1 32'. Any excess solvent may be withdrawn through line 33 2 as product or stored for future use during liquefaction~
3 That portion of the solvent, if any, fed directly to mixing 4 vessel 10 is recycled through line 13.
Normally, the hydrogenation will be accomplished at 6 a temperature within the range from about 600F to about 7 950F and a pressure within the range from about 650 to 3 about 2000 psig, preferably 1000 to 1500 psig. The hydro-9 gen treat rate during the hydrogenation general]y will be 10 within the range from about 1000 to about 10,000 scf/bbl.
11 Any of the known hydrogenation catalysts may be employed but 12 a nickel moly catalyst is most preferred.
13 In accordance with the improved method of the pre-14 sent invention, the bottoms product withdrawn through line 15 25 may be divided and all or a portion thereof subjected to 16 extraction. The portion to be subjected to extraction will 17 be withdrawn through line 34 and fed to contacting vessel 18 40. In a preferred embodiment, the entire normally solid 19 bottoms product will be passed through contacting vessel 40.
20 ~ny portion of the bottoms product not subjected to extrac-21 tion may be withdrawn through line 35 and processed in 22 accordance with conventional technology. In general, Erom 23 about 80 to about 100 weight percent of the bottoms product 24 will be subjected to extraction.
In contacting vessel 40 the fraction of hydrogenated 26 product from hydrogenation vessel 29 used as the extraction 27 solvent i5 introduced at or near the bottom oE contacting 28 vessel 40 and flows upwardly through the contacting vessel 29 and is withdrawn at or near the top thereof through line 41.
30 The bottoms introduced through line 34 flow generally down-31 wardly and are withdrawn from the contacting vessel at or 32 near the bottom thereof through line 34'. In the embodiment 33 illustrated, the solvent withdrawn through line 41 contain-34 ing the extracted reactive materials is then passed through 35 knock-out drum 42 to faciliate the separation of any unre-36 active materials contained ~ereinO The unreactive materials 37 will be separated from knock-out drum 42 throush line 43'.
1 The unreactive materials separated in the knock-out drum 2 may then be combined with unreact~Te materials separated 3 from the contacting vessel 40 in line 43 and introduced into 4 separator ~6. In the separator, entrained solvent may be flashed overhead and the remaining portion of the normally 6 solid bottoms product withdrawn through line ~8. The re-7 covered solvent, thoug~ not illustrated, may be combined 8 with solvent withdrawn from knock-out drum 42 or with sol-9 vent withdrawn from hydrogenation vessel 29 through line 32.
The solvent, generally free of unreactive materials, is 11 withdrawn from knock-out drum 42 through line 12 and fed to 12 mixing vessel 10. The remaining portion of the normally 13 solid bottoms product withdrawn through line 48 may be di-14 rectly discarded or otherwise treated in accordance with conventional technology to recover the energy value thereof.
16 As indicated, supra, and in a preferred embodiment, 17 the extraction will be accomplished at a temperature within 18 the range from about 100 to about 400~F and at a pressure 19 within the range from about 0 to about 500 psig~ In the 20 embodlment illustrated, the treat rate in contacting vessel 21 40 will be within the range from about 4 v/v/hour to 8 22 v/v/hour. Though not illustrated, contacting vessel 40 23 could be a stirred vessel and the entire solvent/normally 24 solid bottoms product could be withdrawn and passed to a 25 gravity separator. The major portion of the solvent could, 26 then, be separated by withdrawing the same from the decanting 27 vessel at a point above the solid level. Solvent entrained 28 in the remaining solids portion could then be separated in 29 the same manner as illustrated. When a stirred vessel is 30 employed, space velocity is not important but sufficient 31 contacting time should be allowed to insure that from about 32 20 to about 80 weight percent oE the reactive material is 33 separated from the normally solid bottoms product. The 34 reactive material thus separated is recovered with less ener-35 gy than would be required with the use of a more conventional 36 solvent such as toluene or the like which would, normally, be 3~
l separated and reused in the extraction operation rather t~an 2 as a solvent in the liquefaction step.
3 ~aving thus broadly described the present invention 4 and a preferred embodiment thereof, it is believed that the same will become more apparent by reference to the following 6 examples. It will be appreciated, however~ that the exam-7 ples are presented solely for purposes of illustration and 8 should not be construed as limiting the invention.
9 EXA~PLE 1 In this example, a run was completed in a 100 pound ll per day continuous unit usi~g an Illinois seam coal (Illi-12 nois No. 6) as the solid carbonaceous material and a hydro-13 genated recycle liquid havlng an initial boiling point of 14 about 400F and a final boiling point o-F about 800F and containing from about 40 to about 45 weight percent hydro-16 gen donor species was used as the e~traction solvent and 17 as the solvent or diluent for liquefaction. The unit was 18 operated in a mode similar to that illustrated in Fisure 1.
19 All of the solvent withdrawn from hydrogenation vessel 29 was used to extract bottoms from the separation vessel. As 21 withdrawn, the bottoms contain 40 weight percent of toluene 22 soluble material. The bottoms were extracted with the hy-23 drogen donor solvent at 300F and 0 psig with a nominal 24 contacting time of 5 minutes. After extraction, the re-m~;n;ng portion of the normally solid bottoms product con-26 tained lO weight percent toluene soluble material. Use of 27 the solvent intended for slurry preparation to extract the 28 bottoms therefore resulted in the recovery of about 75 29 weight percent of the reactive material from the bottoms and the gaseous and liquid product yields were increased 31 accordingly.
32 ExAMpLE~2 33 In this example, a run was completed in a lO0 pound 34 per day continuous unit using an l~yodak coal as the solid carbonaceous material and a hydrogenated recycle liquid 36 having an intial boiling point of about 400F and a final 37 boiling point of about 800F and containing from about 40 3~
1 to about 45 weight percent hydrogen donor species was used 2 as the extraction solvent and as the solvent or diluent for 3 liquefaction. The unit was operated in a mode similar to 4 that illustrated in Figure 1. All of the solvent withdrawn from hydrogenation vessel 29 was used to extract bottoms 6 from the separation vessel. As withdrawn, the bottoms con~
7 tain 50 weight percent of toluene soluble material. The 8 bottoms were extracted with the hydrogen donor solvent at 9 300~F and 0 psig with a nominal contacting time of 5minutes.
After extraction, the remaining portion of the normally so-11 lid bottoms product contained 10 weight percent toluene 12 soluble material. Use of the solvent intended for slurry 13 preparation to extract the bottoms therefore resulted in the 14 recovery of about ~0 weight percent of the reactive material from the bottoms and the gaseous and liquid product y~elds 16 were increased accordingly.
17 From the foregoing it will be apparent that the to-18 tal conversion of the coal was increased by about 10-15 19 weight percent and the yield of both gaseous and liquid pro-ducts was increased. This increase was, effectively, accom-21 p]ished with less equipment and less energy than would have 22 been required if an additional liquefaction stage were em-23 ployed, if the entire bottoms were recycled or if a solvent 24 had been used to extract the bottoms which would then have been separated via distillation.
26 While the present invention has been described and 27 illustrated by reference to particular embodiments thereof, 28 it will be appreciated by those of ordinary skill in the art 29 that the same lends itself to variations not necessarily illustrated herein. For this reason, then, reference should 31 be made solely to the appended claims for purposes of deter-32 mining the true scope of the present invention.
Claims (5)
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An improved process for liquefying coal or a similar solid carbonaceous material characterized by comprising the steps of:
(a) forming a slurry of a coal or similar solid carbonaceous material in a hydrogen donor solvent, at least a portion of which solvent was used as a solvent in the extraction of a normally solid bottoms product from the liquefaction accomplished in step (b);
(b) subjecting the slurry from step (a) to an elevated temperature and pressure to convert the coal or similar solid carbonaceous material in part to a normally gaseous product, in part to a normally liquid product and in part to a normally solid bottoms product;
(c) separating the normally gaseous product, the normally liquid product and the normally solid bottoms product from step (b);
(d) extracting at least a portion of the normally solid bottoms product with a donor solvent; and (e) using at least a portion of the donor solvent containing extracted components from the normally solid bottoms product from the extraction in step (d) in the formation of the slurry prepared in step (a).
(a) forming a slurry of a coal or similar solid carbonaceous material in a hydrogen donor solvent, at least a portion of which solvent was used as a solvent in the extraction of a normally solid bottoms product from the liquefaction accomplished in step (b);
(b) subjecting the slurry from step (a) to an elevated temperature and pressure to convert the coal or similar solid carbonaceous material in part to a normally gaseous product, in part to a normally liquid product and in part to a normally solid bottoms product;
(c) separating the normally gaseous product, the normally liquid product and the normally solid bottoms product from step (b);
(d) extracting at least a portion of the normally solid bottoms product with a donor solvent; and (e) using at least a portion of the donor solvent containing extracted components from the normally solid bottoms product from the extraction in step (d) in the formation of the slurry prepared in step (a).
2. A process according to claim 1 further characterized in that the donor solvent is a distillate fraction separated from the liquid product obtained in step (c), which solvent is separately hydrogenated to contain at least 0.8 weight percent donatable hydrogen.
3. The improved process of claim 1 wherein all of the donor solvent used in step (a) is used in step (d).
4. The improved process of claims 1, 2 or 3 wherein the extraction of step (d) is accomplished at a temperature within the range from about 50 to about 600°F and at a pressure within the range from about 0 to about 750 psig.
5. The improved process of claims 1, 2 or 3 wherein the extraction of step (d) is accomplished at a temperature within the range from about 100 to about 400°F and at a pressure within the range from about 0 to about 500 psig.
h. The improved process of claims 1, 2 or 3 wherein the extraction of step (d) is accomplished at a temperature within the range from about 100 to (claim 6 continued) about 400°F and at a pressure within the range from about 0 to about 500 psig, and the ratio of solvent to normally solid bottoms product is within the range from about 4:1 to about 8:1 v/v.
h. The improved process of claims 1, 2 or 3 wherein the extraction of step (d) is accomplished at a temperature within the range from about 100 to (claim 6 continued) about 400°F and at a pressure within the range from about 0 to about 500 psig, and the ratio of solvent to normally solid bottoms product is within the range from about 4:1 to about 8:1 v/v.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US33258381A | 1981-12-21 | 1981-12-21 | |
| US332,583 | 1981-12-21 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1190167A true CA1190167A (en) | 1985-07-09 |
Family
ID=23298880
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000407523A Expired CA1190167A (en) | 1981-12-21 | 1982-07-19 | Process for the liquefaction of solid carbonaceous materials |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0082586A3 (en) |
| JP (1) | JPS58109587A (en) |
| AU (1) | AU552352B2 (en) |
| BR (1) | BR8204822A (en) |
| CA (1) | CA1190167A (en) |
| ZA (1) | ZA825107B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4596650A (en) * | 1984-03-16 | 1986-06-24 | Lummus Crest, Inc. | Liquefaction of sub-bituminous coal |
| US4605486A (en) * | 1985-04-26 | 1986-08-12 | Exxon Research And Engineering Co. | Coal liquefaction process with increased naphtha yields |
| US9061953B2 (en) | 2013-11-19 | 2015-06-23 | Uop Llc | Process for converting polycyclic aromatic compounds to monocyclic aromatic compounds |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ZA774819B (en) * | 1976-08-20 | 1978-06-28 | Exxon Research Engineering Co | Multiple-stage hydrogen-donor coal liquefaction process |
-
1982
- 1982-07-16 ZA ZA825107A patent/ZA825107B/en unknown
- 1982-07-19 CA CA000407523A patent/CA1190167A/en not_active Expired
- 1982-08-10 EP EP82304209A patent/EP0082586A3/en not_active Ceased
- 1982-08-18 BR BR8204822A patent/BR8204822A/en unknown
- 1982-08-19 AU AU87423/82A patent/AU552352B2/en not_active Expired - Fee Related
- 1982-08-20 JP JP57143528A patent/JPS58109587A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| BR8204822A (en) | 1983-08-02 |
| ZA825107B (en) | 1983-04-27 |
| AU8742382A (en) | 1983-06-30 |
| JPS58109587A (en) | 1983-06-29 |
| EP0082586A3 (en) | 1984-10-10 |
| EP0082586A2 (en) | 1983-06-29 |
| AU552352B2 (en) | 1986-05-29 |
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