GB1574446A

GB1574446A – Treatment of coal for the production of clean solid fuel and/or liquid turbine fuel
– Google Patents

GB1574446A – Treatment of coal for the production of clean solid fuel and/or liquid turbine fuel
– Google Patents
Treatment of coal for the production of clean solid fuel and/or liquid turbine fuel

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Publication number
GB1574446A

GB1574446A
GB191977A
GB191977A
GB1574446A
GB 1574446 A
GB1574446 A
GB 1574446A
GB 191977 A
GB191977 A
GB 191977A
GB 191977 A
GB191977 A
GB 191977A
GB 1574446 A
GB1574446 A
GB 1574446A
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United Kingdom
Prior art keywords
coal
product
hydrogen
sulfur
stage
Prior art date
1977-01-18
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GB191977A
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ExxonMobil Oil Corp

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Mobil Oil Corp
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1977-01-18
Filing date
1977-01-18
Publication date
1980-09-10

1977-01-18
Application filed by Mobil Oil Corp
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Mobil Oil Corp

1977-01-18
Priority to GB191977A
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patent/GB1574446A/en

1980-09-10
Publication of GB1574446A
publication
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patent/GB1574446A/en

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Classifications

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

C10G1/04—Production of liquid hydrocarbon mixtures from oil-shale, oil-sand, or non-melting solid carbonaceous or similar materials, e.g. wood, coal by extraction

C10G1/042—Production of liquid hydrocarbon mixtures from oil-shale, oil-sand, or non-melting solid carbonaceous or similar materials, e.g. wood, coal by extraction by the use of hydrogen-donor solvents

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

C10G1/002—Production of liquid hydrocarbon mixtures from oil-shale, oil-sand, or non-melting solid carbonaceous or similar materials, e.g. wood, coal in combination with oil conversion- or refining processes

Description

(54) TREATMENT OF COAL FOR THE PRODUCTION
OF CLEAN SOLID FUEL AND/OR LIQUID
TURBINE FUEL
(71) We, MOBIL OIL CORPORA
TION, a Corporation organised and existing under the laws of the State of New York,
United States of America, of 150 East 42nd
Street, New York, State of New York 10017,
United States of America, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement:- This invention relates to the desulfurization of coal as herein defined.
The present use of coal in the United
States is primarily for the purpose of conversion into electrical energy and thermal generating plants. A principal drawback in the use of coal on a more widespread basis is its sulfur content, which can range up to five percent. The removal of sulfur from any liquid or solid fossil fuel improves the fuel for use in energy release by oxidation without pollution.
Furthermore, the removal of sulfur from coal and solid coal derivatives permits more efficient use of coal in producing liquid fuels and feedstocks, in gasification processes, and in metallurgical processing.
In recent years, air and water pollution resulting from mining and burning of coal has come under public scrutiny. Earlier concern was over the smoke produced from coal-burning installations. Efforts were directed toward more complete combustion in power plants, development of processes for smokeless fuel for domestic use, and reduction of dust effluent from chimneys.
More recently, sulfur in coals and rocks overlying coalbeds has received wide attention as a major cause of air and water pollution. In recent years, for example, 209 million tons of coal containing an average of 2.5 percent sulfur was burned in the United
States; the sulfur discharged to the atmosphere mainly as sulfur dioxide, amounted to about 5 million tons.
Considering the subsequent increase in power demand which will continue into the foreseeable future, the seriousness of the problem is impressive. Accordingly, both
State and Federal Governments in the
United States have enacted legislation and promulgated regulations which place upper limits on the sulfur content of coals to be burned or on the sulfur dioxide content of the discharged flue gas. However, additional processing of coal, either by processing the coal before it is burned or by processing the flue gas after the coal is burned, adds to the cost of products derived from it-electricity, for example. Thus, the problem of pollution caused by the combustion of coal or coal-derived fuels affects utilization of coal as a source of power and, hence, its value as a natural resource.Therefore, the cost of removing sulfur from coal must be kept reasonably low, so that coal may be efficiently and economically used as an alternative energy source.
The sulfur in coal occurs in three forms: (1) pyritic sulfur in the form of pyrite or marcasite, (2) organic sulfur, and (3) sulfate sulfur. However, the primary sulfur contaminants are of the first two forms. One solution to the coal desulfurization problem is the removal of sulfur dioxide from flue gas generated by combustion of the coal; another is the removal of sulfur before the coal is combusted or otherwise used. The present invention is a solution of the latter type, and is more specifically described as the removal of organic and inorganic sulfur, especially pyritic sulfur, under relatively mild reaction conditions.
The use of manganese oxide to desulfurize coal and coal products has long been known in the art. However, these prior processes may be characterized as hightemperature volatilization processes as opposed to oxidative solubilization processes. For example, United State Patent
Number 28,543 (issued in 1860) discloses a process for the removal of sulfur after the coking process, wherein a mixture of sodium chloride, manganese peroxide, resin and water is applied to the red-hot coke, and sulfur is oxidized and released from the coke mass in gaseous form. Other similar processes are disclosed in United States
Patent Numbers 90,677, 936,211, 3,348,932 and 3,635,695.
The use of oxidative solubilization processes to remove sulfur from coal is a relatively new concept. Even though the solubilization of pyrites by various oxidizing agents, including nitric acid, hydrogen peroxide, hypochlorite, ferric and cupric ions, has long been known, the application of these reactions to the removal of pyrite from coal has only recently been reported.
The success of such processes in a coal medium was unexpected because pyrite is dispersed in finely divided form throughout the coal matrix, and the penetration of such an organic matrix with water is known to be difficult. Furthermore, the oxidative dissolution of pyrites from’the coal matrix with strong aqueous oxidizing agents, such as nitric acid, hydrogen peroxide, or hypochlorite extensively oxidize the organic.
coal matrix. Moreover, the use of such strong oxidizing agents will convert the sulfur content of the coal to sulfate but not to free sulfur which is obviously a more valuable commodity than sulfate.
The application of mild oxidation reactions to remove the pyrite from coal is disclosed in United States Patent Number 3,768,988. The process of that invention employs the ferric ion as the oxidizing agent and will hereinafter be referred to as the
Meyers process. Essentially, the Meyers process employs the following steps:
(1) reacting the coal with an effective amount of an aqueous solution containing ferric ion,
(2) separating the treated coal from the oxidizing solution, and
(3) purifying the treated coal.
Step (3) may be accomplished by first washing the coal and then drying it to volatilize the free sulfur residue in the coal.
It may alternatively be accomplished by extracting the washed, treated coal with an organic solvent for sulfur. Such a solvent may be benzene, kerosene, or p-cresol.
Numerous coal liquefaction processes are well known in the art. For example, United
States Patent Number 2,686,152 discloses a lignitic coal extraction process carried out with an organic solvent such as tetralin or a mixture thereof with a phenol at temperatures between about 4800 F. (2490C) and about 900″F. (482″C), preferably between 750″F. (399″C) and about 8600 F.
(4600 C), with or without hydrogen being used, and at atmospheric or at autogenous hydrogen pressure, said extraction process being carried out without any particular attention being paid to time of reaction and generally a time of about 30 minutes to 1 hour being preferred. This prior art disclosure indicates that liquid products are formed in an amount ranging from about 7% to about 50%. Gas formation is also observed in an amount varying from 13 to 28n e by weight of total products, the remaining products being mostly coke or char. Such a procedure cannot economically lend itself toward commercial production of liquid products.What is needed in any commercial coal liquefaction process is essentially complete liquefaction of the coal with minimum formation of gaseous products, since these gases are of little economic value and are in effect waste products which consume valuable hydrogen.
The invention relates to the solvation or liquefaction of coal as herein defined to produce a product of reduced sulfur and ash content without any substantial reduction of the hydrogen/carbon ratio of the carbonaceous material processed. More particularly the present invention is concerned with a two stage operation in which a first stage is a non-catalytic solvent dissolving operation maintained under temperature and residence time conditions selected to particularly reduce any significant loss of hydrogen from a hydrogen donor solvent as by aromatization or light gas producing reactions. In another aspect the combination operation of the present invention is concerned with minimizing the hydrogen requirements needed to produce a clean coal product of reduced sulfur and ash content.In a further aspect the present invention is concerned with a second stage operation either catalytic or non catalytic maintained generally under selected temperature conditions for the production of a clean coke product and/or a solvent refined coal of a composition which becomes fluid upon heating and is suitable for use as a boiler fuel.
The term «coal», as used herein, is to include any carbonaceous material not more than 88% carbon and containing substantial amounts of pyritic and organic sulfur, and oxygen. Thus, the term may include materials such as anthracite coal, bituminous coal, sub-bituminous coal, lignite, coke, petroleum coke, or coke breeze. The term pyritic sulfur is known in the art and refers to sulfur bound in chemical combination with iron in the coal in the form of iron pyrites. Some coals that may be improved by the combination process of this invention are shown in the following table.
Analyses of Coals
Name of Coal W. Kent. N. D. Lignite Wyodak III. #6 Pitts. Seam
State Kentucky N. Dakota Wyoming Illinois Kentucky
County Hopkins Ward Campbell Perry Marion
Seam 9, 14 Coteau Anderson 6 #3
Name of Mine Colonial Velva #2 Bell Ayr Burning Loveridge
Star #2
Q\ m \O mNm e V o o n Moisture to N N x * % Ash (as rec.) 7.83 5.43 3.63 9.77 10.29 C . % Volatile Matter @ 6000C 36.61 43.30 47.44 38.82 35.27 % Fixed Carbon n O N O O xD 73.06 65.32 71.82 70.44 75.43 5.00 4.37 5.20 5.08 4.78 9.17 20.66 17.12 9.37 5.27 %N 1.47 0.92 0.90 1.26 1.27 sL % S (total) 2.97 0.29 0.30 3.29 2.65 m .00 < mOo,eSo st 5 % S (organic) 1.36 0.21 0.23 1.79 1.47 % S (sulfate) 0.42 0.02 0.01 0.05 0.03 % Cl 0.00 0.00 0.0 0.02 0.08 % Ash 8.33 8.44 4.66 10.54 10.46 T < \DO oooorston OXx 0 tomt0n s o o o0 V o g o c) 8 s os Q v s .H s tE x t o z = S < > ; vSoz0mmm *sls *s!sKleuv -ileuv aXeUUIXm aletu -IXOld *All analyses are given on a dry weight basis unless otherwise stated.
# by difference.
According to the present invention, we provide a method for removing sulfur and ash from coal which comprises in a first stage solubilizing coal as herein defined in a hydrogen donor solvent material at a temperature of 800″F or less for a time of from 1 to 5 minutes, separating pyrite sulfur, ash and unconverted coal solids from the solubilized coal and thereafter in a second stage subjecting the solubilized coal to temperature conditions with the range of 600 to 1000 F for a time sufficient to upgrade the solubilized coal product and produce a clean product and removing at least a portion of the hydrogen donor material, e.g. by filtration.It is also desirable to reduce the oxygen content of the coal since too much retained oxygen will cause coking upon heating rather than produce a solvent refined coal (SRC) type material which will melt upon heating.
The coal feed mixed with a hydrogen donor material is preferably prepared by grinding to a particle size less than about 1/2 inch mesh. The coal may be wet ground in a ball mill rod mill or hammer mill to an acceptable particle size before being mixed with the solvent and heated as herein described.
The term solvent refined coal is intended to refer to any coal product of reduced sulfur, oxygen and ash content obtained by solvation of coal and recovered therefrom as a purified coke material or one of a composition which will melt upon heating and be flowable.
By hydrogen donor material it is intended to refer to relatively high boiling hydroaromatic compositions such as compositions comprising polycyclic aromatics or partially hydrogenated aromatic solvents (e.g. tetralin, anthracene, oil, coal oil, syntower bottoms, deasphalted tar, heavy cycle oil, FCC clarified slurry oil, coker gas oil and mixtures thereof).
According to an important feature of this invention, the solvent is recycled to the first or solubilizing stage and the amount of phenols present in the solvent contacting the coal is maintained in the range of 10 50 /n by weight, preferably 1 5%-30% by weight.
In some instances the presence of phenols of the first stage reaction is desirable as they aid in dissolving the initial coal products.
With optimizing in this way, care should be exercised to preserve the phenols. For example, the hydrogenation of the recycled solvent to achieve higher hydrogen donor capacity can often, be advantageous at the first stage of the process. In cases where both hydrogenated solvent and phenols are desirable in the first stage of the process, the phenols can be removed prior to hydrogenation and then reblended to the charge stock.
Too high a level of phenols in the recycled solvent can have deleterious effects. This is particularly the case in the second stage of the process. These deleterious effects occur in several forms.
High concentration of phenols can induce high viscosity to the solvent-product stream and will result in slow filtration rates.
Phenols can chemically inter-act with coals and all coal products and cause the formation of products of higher polarity and therefore lower solubility. Phenols-coal products interactions result in loss of solvent range component and phenol-coal products interactions can promote the formation of solids, for example coke, char, semi-coke, reactor solids, residue or a variety of other deposits within the reactor or ancillary equipment. In the hydrogenative process phenols can consume excessive amounts of hydrogen.
Lower solvent refined coal solubility generally is associated with poor product quality. Products of lower order coal are more susceptible to interactions with phenols and these same coals are the ones which produce the highest steady state of phenol concentration in the recycled solvent unless proper action is taken to reduce the phenol level.
Control of the amount of phenols by selective removal from the recycled solvent can be brought about by a variety of techniques all of which are most advantageously applied after the first stage reaction and – the solids filtration or other separation manner. Amongst the many phenol removal techniques that may be employed are the following:
1. A large portion of the phenols in the recycled solvent range product are low boiling components and can be removed by distillation with the appropriate cut points.
Phenol- rich and phenol – depleted fractions can thus be obtained. The phenol – depleted recycled solvent can be recycled, further upgraded or included with the charge stock at the second stage of the process.
2. Alternatively the whole filtrate may be extracted with caustic to remove phenols.
The more preferred extraction procedure however, is to distill the recycle solvent away from the crude product mix after either the first or the second or both stages and remove the phenols from the distillate by extraction with caustic. The phenols can be recovered for further use or for sale as chemicals by acidification of the extract with acid or CO2. Phenols can also be selectively extracted with polar organic solvents.
3. For distilled, recycled solvent containing phenols, the phenols can be removed by percolation at temperatures near ambient through an appropriate absorbent such as silica, alumina, clay, diatomatious earth, charcoal, coal residue or other porous solids. The absorbed phenols are recovered by stream stripping and can either be used in the process or sold as chemicals.
4. An alternative destructive means of phenol removal is to catalytically hydrogenate the whole coal product or the recvclc solvent. This method avoids separations and in addition provides recycle solvent of higher hydrogen donor capacity which is desirable at both stages of the process. In these instances when the amount of phenols in the recycle solvent must be controlled at a level lower than that which would be achieved through normal processing, the desired phenol concentration is less than 10% and preferably less than 5% by weight.
The discussion hereinafter presented is directed to show that the split temperature coal solvation and clean product recovery operation of this invention results in high conversion of the coal to a deashed and desulfurized solid and/or modified coal product which will melt upon heating and the hydrogen consumption of the process is kept at a low level concomitant with maintaining high levels of solvation liquid for recycle in the operation. It is also shown by the following discussion that better results are obtained by employing a dual stage temperature operation of relatively low temperature and contact time in the first stage followed by a higher temperature in the second stage without catalytic hydrogenation.
Accompanying Figure 1 is a block flow diagram of a two stage process for upgrading coal comprising a dissolver, a filter and a second stage for converting the coal to coke, to a modified coal which becomes fluid upon heating or to a hydrogenated product suitable for use as a turbine fuel.
Figure 2 is a curve showing the relationship of retained sulfur and oxygen in solvent refined coal.
Figure 3 is a plot of data in graph form showing the relationship in hydrogen consumption to oxygen conversion when solubilizing coal.
Referring now to Figure 1, by way of example, a coal material such as Kentucky 9, 14 coal or any other available coal comprising not more than 88% carbon on a moisture-ash free basis and in a substantially pulverized condition following grinding or ball milling is charged to the process by conduit 2. The pulverized coal in conduit 2 is mixed with a hydrogen donor solvent material herein identified and introduced by conduit 4. The mixture is then passed to dissolver 6. In dissolver 6, temperature conditions are maintained at 8000F or less and more usually within the range of 550″F to 800″F for a mix residence time within the range of 1 to 5 minutes. The operating conditions selected for dissolver 6 are those which minimize or avoid aromatizing conditions, and/or the consumption of any significant amounts of hydrogen.The consumption of hydrogen is associated primarily with the formation of less desired side products such as methane, hydrogen sulfide and lighter hydrocarbons. Since the oxygen and sulfur content of SRC (solvent refined coal) is identified as being kinetically related, the consumption of hydrogen presents a major factor in SRC process optimization. In the work leading to the concepts of this invention it was observed that:
(1) the initial products formed at low temperatures and short contact times were high in hydrogen content and low in aromaticity; and
(2) thermodynamic control appears to be operative during SRC processing when elevated temperatures lead to more aromatic products.
The work results also indicate that the products of low temperature-short contact times could be potential hydrogen sources at elevated temperatures. On the other hand, at higher temperatures, the yield of recycle solvent range material was also observed to be higher for a given degree of oxygen conversion. The production of solvent, of course, is a critical element of the SRC process and it is observed that at lower temperatures, high hydrogen consumption is required for its formation.
The high temperature operations, on the other hand, lead to excessive coke formation because of secondary reactions and eventually the units plug up unless the hydrogen pressure is raised considerably.
Also, the formation of coke may be promoted by intrinsic minerals in the coal charged.
In view of the above observations, the present invention is directed to the concept that the product of a low temperature (800″F or less) short contact time (1-5 minutes) conversion of coal admixed with a hydrogen donor material can be filtered to remove minerals and inorganic sulfur, and the filtered product thus obtained used as a feedstock in a second stage operation under generally more severe conditions to produce products of different composition such as coke, a modified coal which is flowable upon heating to an elevated temperature or a hydrogenated product having the characteristics of a turbine fuel.
Referring now to Figure 1, the dissolver 6 is provided with conduit 8 for removal of gaseous components containing oxygen and sulfur freed from the coal in the operation.
In this operation, 70 or more percent of the coal is dissolved in the hydrogen donor material. The product obtained is thereafter passed by conduit 10 to a filter 12 wherein a separation is made to remove ash, pyrite and unreacted coal from the solubilized material. The filtered product of reduced oxygen and sulfur content as exemplified hereinafter is recovered from the filter by conduit 14 for further processing as hereinafter described.
In one mode of operation herein identified as mode «A», the solubilized coal recovered from the filter is passed by conduit 16 to a reaction zone 18. Reaction zone 18 may be a delayed coking zone wherein the material charged thereto is further processed at a relatively low temperature above about 800″F for a long residence time to produce a coke product of low sulfur, oxygen and hydrogen content.
Volatilized product is removed from the delayed coking operation and hydrogen donor material is separated for recycle in the combination operation.
On the other hand, reaction zone 18 may be maintained under relatively high temperature conditions within the range 850″F to 10000F wherein the filtered product of the first stage is subjected to a high temperature, short time thermal soak within the range of 1 to 15 minutes to produce a product of low sulfur and oxygen content but of high hydrogen content. In this operation, a solvent refined coal product is formed which is fluid when heated to a temperature of about 200″C.
Such material is suitable for use as fuel for a boiler normally burning residual materials such as bunker fuels. This material may be employed as formed by withdrawal through conduit 22 or it may be passed to a further filtering operation 24 wherein some char and ash are removed from the melt before the cleaned melt is recovered and withdrawn by conduit 26. Char and ash are recovered by conduit 28.
In yet another mode of operation herein identified as mode «B», the filtered product of step I is passed by conduit 30 to a catalytic hydrogenation zone 32 to which a hydrogen rich gas is passed by conduit 34. In catalytic hydrogenation zone 32, the solubilized coal product is catalytically hydrogenated at a temperature within the range of 600″F to 900″F. More usually, the temperature is maintained below about 800″F. The pressure is maintained within the range of 600 to 2000 psig and more usually is selected as a function of the hydrogenation desired. Substantially any hydrogenation catalyst may be employed.
For example, the oxides and sulfides of Co,
Mo, Ni, and W and mixtures thereof dispersed in a suitable inorganic matrix may be employed. Matrix materials of alumina, silica and mixtures thereof may be employed.
Figure 2 is a plot of data obtained showing the relationship between sulfur and oxygen content of a solvent-refined coal.
The graph is essentially self explanatory for the reasons herein discussed.
Figure 3 is a plot of data obtained showing the relationship between hydrogen consumption (based upon the weight of the coal) and oxygen conversion as discussed above leading to the concepts of this invention.
We conceive that for any end use of a coal that must be chemically modified (to meet fuel specifications) the optimum process will consist of a two stage process in which the first stage is conducted at a low temperature with short residence time; the product of this reaction is filtered prior to the second stage to remove ash and inorganic sulfur; and finally the second stage is conducted under different conditions depending on the desired end use, as described below. A flow diagram of this process is presented in the accompanying Figure 1.
First Stage
Coal solubilization ( > 70 4, conversion) with a H-donor solvent is achieved at rather low temperature (8000F or less) and short contact time 1–5 minutes). Under these conditions, the product has a high heteroatom (0, S, N) content. Often the sulfur content is too high to meet some specifications. We propose at this stage to filter the solution and to remove the inorganic material and the insoluble organic material (which have a higher heteroatom content and a lower H/C ratio than the dissolved coal).
Second Stage
A. For the production of clean solid fuel the filtered solution is heated in a second stage at much elevated temperature (above 860″F but not above 1000 F) where the removal of
S and 0 takes place rapidly and to a high degree. Even if some coke is formed during this stage it will contain little ash. A second filtration may or may not be used depending on the situation. After the removal of the solvent the product can be used as a clean fuel which meets higher quality specifications. Another alternative is to feed the total filtered product of the 1st stage to a process similar to delayed coking where oxygen and sulfur contents are then reduced further.
B. For liquid turbine fuel the coal solution obtained in stage one can be hydrotreated with a catalyst at temperatures of 600 to 8000F (at higher temperatures coal eliminates hydrogen). The catalytic stage is performed on a homogeneous solution from which inorganic materials and low quality organics (both likely catalyst poisons) are substantially removed. The product of the first stage is still rich in hydrogen relative to conventional SRC’s, is much easier to hydro-process, and consumes less hydrogen.
To the best of our knowledge, no known coal liquefaction technology takes advantage of the possibility of removal, at a very early stage in the process, of the inorganics and insoluble organic residue, and thereafter continues the major transformations required to produce superior fuel with a homogeneous solution, free of ash and other insoluble matter.
The use of the catalytic removal of sulfur and oxygen at low temperature would avoid the unnecessary reaction of aromatization in the first stage (due to high temperature) and the subsequent rehydrogenation of aromatics which are produced therein.
EXAMPLE 1
A slurry 1:5 of a W. Kentucky subbituminous coal (see Table 1) and an Hdonor solvent (tetralin, 43%; 2-methyl naphthalene, 33%; p-cresol, 18%) was heated to 8000F for 1 minute, whereafter insolubles were removed. Over 70 /n of all coal became soluble. Product I was obtained after the removal of the solvent and low volatile materials. The composition is shown in Table 1.
An SRC obtained at low temperatures and short contact time similar to those for
Product 1 was treated in a second stage at 8850F to produce clean boiler fuel as described below
A solution of liquid coal (Product 2 in
Table 1, obtained in similar conditions, but at higher conversion than Product 1) in the same solvent as for Product 1 is heated for 3 minutes at 8850 F. After the removal of the solvent, Product 3 was obtained (see table).
TABLE 1
Characteristics of the Initial Coal and its Liquefaction Products
Elemental Analysis
Sample H/C O S
Initial Coal 0.84 9.0 2.6*
Product 1 0.80 6.5 1.3
Product2 0.82 5.1 1.2
Product 3 0.84 3.2 0.75
Industrial SRC** 0.65 3.4 0.8 Ash < 0.5*** * 1.4 ' organic sulfur. ** same initial coal as our products. *** should melt at a reasonable temperature below 200"C. EXAMPLE 2: (First Stage Comparison) A series of runs were conducted at 8000 F at 1000--1400 psi H2 in which W. Kentucky 9, 14 coal was dissolved in a solvent comprising 43.1X tetralin; 37.8% 2-methyl naphthalene; 17.2- p-cresol; and 1.9% ypicoline on a weight basis. Differences in hydrogen consumption at long and short contact time are clearly shown in table 2 below. A large quantity of hydrogen is consumed at extended reaction times with only minor gains in total soluble product yield. A prime indicator of the degree of coal conversion is the percent oxygen removed from tfle coal. Sulfur linearly relates to oxygen (see Figure 2). The relationship between hydrogen consumption from the solvent and oxygen conversion (100 x "O" in SRC + Residue t "0" in Coal) is tabulated below. Also shown is the percent of the original coal which was converted to soluble form. TABLE 2 Contact Time wt % H % O/, Coal (minutes) Consumption Conversion Solubilization 0.5 0.17 6.76 50 1.3 0.22 39.91 78 40.0 1.06 59.00 93 417.0 2.58 80.48 96 For short contact times, essentially no hydrogen consumption from H2 gas was observed, so that these results represent closely the total hydrogen consumption. These data show (Figure 2) the linear relationships in oxygen and sulfur removal. Theoretically, if all of the oxygen was removed as water with concomitant hydrogen consumption, only 1.2 wt ," of hydrogen would be required. This indicates that after the initial loss of "easy" oxygen, the remaining oxygen must be removed with maior increases in hydrogen consumption. Note Figure 3. Comparative Example A comparative example is shown below which demonstrates the advantage of our two step procedure over conventional processes in the production of high quality liquids (turbine fuels). An SRC product (Number 1, Table 4) using the same W. Kentucky 9, 14 coal as that of Example 1 was obtained as a typical feedstock for SRC upgrading to turbine fuel. This SRC product and that obtained by us under the much mildcr conditions of the present invention and shorter contact time (Product 2, Table 4), when treated in a similar manner, show maior differences in hydrogen consumption when producing liquid fuels (Product 3, Table 4). Hydrogenation runs of Products 1 and 2 and recycle solvent (Table 3) are conducted in a shaker bomb apparatus (1 liter). In each run, the weighed hydrocarbons together with a weighed amount of catalyst of Table 5, CoMo catalyst, is loaded into the reactor. The properties of the catalyst are tabulated in Table 5. TABLE 3 Properties of the Recycle Solvent used in Shaker Bomb Hydrogenation Runs Recycle Solvent Chemical Analysis (J7950) Hydrogen, wt fa 7.56 Sulfur, wt % 0.32 Nitrogen, wt % 0.59 Oxygen, wt /n 4 4.05 Water, wt % % Specific Gravity, 60/60 F 1.0375 Simulated Distillation, wt % I-8500F 98.1 850 F+ 1.9 TABLE 4 Hydrogen Consumption for Hydrotreated SRC Product 1 Product 2 Product 3 C 87.6 80.9 88.5 H 4.9 7.07 7.5 0 3.4 6.48 2.5 N 2.0 1.16 0.8 S 0.8 1.33 0.2 Ash 0.7 1.7 0.5 Hydrogen Consumption SCF/bbl of SRC N3300 N800 TABLE 5 Properties of Catalyst Physical Properties Total Pore Volume, cc/g 0.54 Real Density, g/cc 3.41 Particle Density, g/cc 1.20 Surface Area, m2/g 173.0 Average Pore Diameter, A 125.0 Adsorption: Water 9.0 N-Hexane 4.0 Cy-Hexane 11.3 Crushing Strength, Ibs 11.7 Packed Density, g/cc 0.80 Loose Density, g/cc 0.67 Chemical Composition, wt % Ni 2.9 MoO3 12.8 CoO 0.06 Al203 88.5 SiO2 0.51 Fe 0.06 Cu < 0.005 V < 0.01 Na 0.01 K < 0.01 The bomb is purged with nitrogen and pressured cold to check for any leaks. After purging with hydrogen, the bomb is pressured cold to 900 psig and agitated at 200 rpm. The system is heated by an induction coil at a controlled rate (50 F/minute) to the reaction temperature. Pressure is maintained at an average of 2000 psig by adding H2 when the pressure drops to 1900 psig and venting gas when the pressure exceeds 2100 psig. After the elapsed reaction time, the bomb is rapidly cooled to ambient temperatures by a water quench. The bomb is vented and the gas volume recorded, sampled, and analyzed by mass spectrometry for C1-C5 hydrocarbons. The contents of the bomb are filtered to remove catalyst. The catalyst is extracted with hexane in a soxhlet extraction apparatus, air dried at 2000 F. and analyzed for carbon. The elemental composition and density of the liquid product are determined; light hydrocarbons in the liquid product are analyzed by gas chromotography. The liquid product is distilled under vacuum equivalent to a 6500F end point material to recover recycle solvent. All runs are conducted at 2000 psig hydrogen and 7500F for 2-4 hours. The feed mixture consists of 1/3 SRC and 2/3 recycle solvent at a 20:1 feed catalyst ratio. Both SRC feedstocks Products 1 and 2 above are upgraded by this procedure to a product of similar composition. Product 3, Table 4. The hydrogen consumption required for Product 1 is much greater that for Product 2 shown in Table 4. The advantage of using the two stage operation of this invention with the production of SRC under mild conditions at short contact time is clearly shown. The advantages above noted will generally occur with any hydrotreating catalyst, but the magnitude may vary from catalyst to catalyst. Other representative catalysts include oxides and sulfides of cobalt and molybdenum, nickel and molybdenum, molybdenum on alumina, nickel and tungsten. These components may be distributed on a matrix or inorganic oxide carrier material such as alumina, silica, clays and mixtures thereof. In upgrading coal to produce a higher quality fuel, the presently known hydrogenative processes all consume hydrogen in excess of that required for stoichiometric removal of heteroatoms. This hydrogen consumption is a key factor in the economics of the overall process. We have discovered two key facts which point to the possibility of decreasing hydrogen consumption. First, at low temperature and short contact times coal may be dissolved to more than 70% in typical coal solvents such as anthracene oil or coal liquids. This dissolution requires very little hydrogen. Second, the products of this low temperature operation are quite low in aromatics. Thus, if one wishes to produce a low ash-low sulfur solid, the product of low temperature solubilization can be freed of ash by filtration, and sulfur may be further reduced after filtration in a second stage at an elevated temperature. Any coke produced in the second stage, mode 2, high temperature, short contact time operation, is low in sulfur and ash, and could be left suspended in the final product. Alternatively, it could be removed by a second filtration and handled separately. If a liquid product such as turbine fuel is desired, the hydrotreating of a low aromatic material is desirable both in terms of ease of heteroatom removal and overall hydrogen consumption as shown by Table 4. WHAT WE CLAIM IS: 1. A method for removing sulfur and ash from coal which comprises in a first stage solubilizing coal as herein defined in a hydrogen donor solvent material at a temperature of 800 F or less for a time within the range of from 1 to 5 minutes, separating pyrite sulfur, ash and unconverted coal solids from the solubilized caol and thereafter in a second stage subjecting the solubilized coal to temperature conditions within the range of **WARNING** end of DESC field may overlap start of CLMS **. Claims (13) **WARNING** start of CLMS field may overlap end of DESC **. TABLE 5 Properties of Catalyst Physical Properties Total Pore Volume, cc/g 0.54 Real Density, g/cc 3.41 Particle Density, g/cc 1.20 Surface Area, m2/g 173.0 Average Pore Diameter, A 125.0 Adsorption: Water 9.0 N-Hexane 4.0 Cy-Hexane 11.3 Crushing Strength, Ibs 11.7 Packed Density, g/cc 0.80 Loose Density, g/cc 0.67 Chemical Composition, wt % Ni 2.9 MoO3 12.8 CoO 0.06 Al203 88.5 SiO2 0.51 Fe 0.06 Cu < 0.005 V < 0.01 Na 0.01 K < 0.01 The bomb is purged with nitrogen and pressured cold to check for any leaks. After purging with hydrogen, the bomb is pressured cold to 900 psig and agitated at 200 rpm. The system is heated by an induction coil at a controlled rate (50 F/minute) to the reaction temperature. Pressure is maintained at an average of 2000 psig by adding H2 when the pressure drops to 1900 psig and venting gas when the pressure exceeds 2100 psig. After the elapsed reaction time, the bomb is rapidly cooled to ambient temperatures by a water quench. The bomb is vented and the gas volume recorded, sampled, and analyzed by mass spectrometry for C1-C5 hydrocarbons. The contents of the bomb are filtered to remove catalyst. The catalyst is extracted with hexane in a soxhlet extraction apparatus, air dried at 2000 F. and analyzed for carbon. The elemental composition and density of the liquid product are determined; light hydrocarbons in the liquid product are analyzed by gas chromotography. The liquid product is distilled under vacuum equivalent to a 6500F end point material to recover recycle solvent. All runs are conducted at 2000 psig hydrogen and 7500F for 2-4 hours. The feed mixture consists of 1/3 SRC and 2/3 recycle solvent at a 20:1 feed catalyst ratio. Both SRC feedstocks Products 1 and 2 above are upgraded by this procedure to a product of similar composition. Product 3, Table 4. The hydrogen consumption required for Product 1 is much greater that for Product 2 shown in Table 4. The advantage of using the two stage operation of this invention with the production of SRC under mild conditions at short contact time is clearly shown. The advantages above noted will generally occur with any hydrotreating catalyst, but the magnitude may vary from catalyst to catalyst. Other representative catalysts include oxides and sulfides of cobalt and molybdenum, nickel and molybdenum, molybdenum on alumina, nickel and tungsten. These components may be distributed on a matrix or inorganic oxide carrier material such as alumina, silica, clays and mixtures thereof. In upgrading coal to produce a higher quality fuel, the presently known hydrogenative processes all consume hydrogen in excess of that required for stoichiometric removal of heteroatoms. This hydrogen consumption is a key factor in the economics of the overall process. We have discovered two key facts which point to the possibility of decreasing hydrogen consumption. First, at low temperature and short contact times coal may be dissolved to more than 70% in typical coal solvents such as anthracene oil or coal liquids. This dissolution requires very little hydrogen. Second, the products of this low temperature operation are quite low in aromatics. Thus, if one wishes to produce a low ash-low sulfur solid, the product of low temperature solubilization can be freed of ash by filtration, and sulfur may be further reduced after filtration in a second stage at an elevated temperature. Any coke produced in the second stage, mode 2, high temperature, short contact time operation, is low in sulfur and ash, and could be left suspended in the final product. Alternatively, it could be removed by a second filtration and handled separately. If a liquid product such as turbine fuel is desired, the hydrotreating of a low aromatic material is desirable both in terms of ease of heteroatom removal and overall hydrogen consumption as shown by Table 4. WHAT WE CLAIM IS: 1. A method for removing sulfur and ash from coal which comprises in a first stage solubilizing coal as herein defined in a hydrogen donor solvent material at a temperature of 800 F or less for a time within the range of from 1 to 5 minutes, separating pyrite sulfur, ash and unconverted coal solids from the solubilized caol and thereafter in a second stage subjecting the solubilized coal to temperature conditions within the range of 600 to 1000"F for a time sufficient to upgrade the solubilized coal product and produce a clean product and removing at least a portion of the hydrogen donor material therefrom. 2. The method of claim 1 wherein the solubilized coal mixture is maintained in the second stage at a temperature above 800of for a residence time less than 15 minutes to produce clean solvent refined coal. 3. The method of claim 2 wherein the residence time is within the range of 1 to 5 minutes. 4. The method of claim 1 wherein the solubilized coal is maintained at temperature conditions above 800"F for a time sufficient to produce a coke product of reduced sulfur content. 5. The method of claim 1 wherein the solubilized coal is subjected to catalytic hydrogenating conditions to produce a refined coal product suitable for use as a turbine fuel. 6. The method of claim 1 wherein the solubilized coal is maintained in the second stage at a temperature above 800"F and for a time which will produce a refined coal product that is fluid at a temperature of 200 C. 7. A process according to any preceding claim wherein the concentration of phenols in said solvent material employed in said solubilizing is 10 to 50, preferably 15 to 30, percent by weight. 8. A process according to claim 7 wherein such concentration is maintained by providing for at least part of the recycle solvent to by-pass hydrogenation before being re-used in said hydrogenation. 9. A process according to any preceding claim wherein phenols are removed from solvent recycled to said upgrading. 10. A process according to claim 9 wherein said removing is accomplished by distillation, extraction, sorption or catalytic hydrogenation. 11. A method for the desulfurization of coal according to any preceding claim substantially as hereinbefore described. 12. A method for the desulfurization of coal according to claim 1 substantially as hereinbefore described in Example 1. 13. Desulfurized coal when produced by the method of any one of Claims 1 to 12. GB191977A 1977-01-18 1977-01-18 Treatment of coal for the production of clean solid fuel and/or liquid turbine fuel Expired GB1574446A (en) Priority Applications (1) Application Number Priority Date Filing Date Title GB191977A GB1574446A (en) 1977-01-18 1977-01-18 Treatment of coal for the production of clean solid fuel and/or liquid turbine fuel Applications Claiming Priority (1) Application Number Priority Date Filing Date Title GB191977A GB1574446A (en) 1977-01-18 1977-01-18 Treatment of coal for the production of clean solid fuel and/or liquid turbine fuel Publications (1) Publication Number Publication Date GB1574446A true GB1574446A (en) 1980-09-10 Family ID=9730332 Family Applications (1) Application Number Title Priority Date Filing Date GB191977A Expired GB1574446A (en) 1977-01-18 1977-01-18 Treatment of coal for the production of clean solid fuel and/or liquid turbine fuel Country Status (1) Country Link GB (1) GB1574446A (en) 1977 1977-01-18 GB GB191977A patent/GB1574446A/en not_active Expired Similar Documents Publication Publication Date Title US4079004A (en) 1978-03-14 Method for separating undissolved solids from a coal liquefaction product US4334976A (en) 1982-06-15 Upgrading of residual oil CA1152924A (en) 1983-08-30 Process of converting high-boiling crude oils to equivalent petroleum products US4438816A (en) 1984-03-27 Process for recovery of hydrocarbons from oil shale US4089773A (en) 1978-05-16 Liquefaction of solid carbonaceous materials US4449586A (en) 1984-05-22 Process for the recovery of hydrocarbons from oil shale US3813329A (en) 1974-05-28 Solvent extraction of coal utilizing a heteropoly acid catalyst Shah et al. 1979 Oxygen, nitrogen, and sulfur removal reactions in donor solvent coal liquefaction US4133646A (en) 1979-01-09 Phenolic recycle solvent in two-stage coal liquefaction process US4317711A (en) 1982-03-02 Coprocessing of residual oil and coal US4260471A (en) 1981-04-07 Process for desulfurizing coal and producing synthetic fuels US4081358A (en) 1978-03-28 Process for the liquefaction of coal and separation of solids from the liquid product US4452688A (en) 1984-06-05 Integrated coal liquefication process CA1080649A (en) 1980-07-01 Treatment of coal for the production of clean solid fuel and/or liquid turbine fuel CA1171011A (en) 1984-07-17 Coal liquefaction process and apparatus therefor CN110819390B (en) 2021-03-12 Method and system for low-rank coal fractional conversion US4077866A (en) 1978-03-07 Process for producing low-sulfur liquid and solid fuels from coal US2654695A (en) 1953-10-06 Process for preparing liquid hydrocarbon fuel from coal US4339329A (en) 1982-07-13 Liquefaction of coal US4325800A (en) 1982-04-20 Two-stage coal liquefaction process with interstage guard bed CA1165257A (en) 1984-04-10 Coal liquefaction desulfurization process GB1603619A (en) 1981-11-25 Process for coal liquefaction CA1085330A (en) 1980-09-09 Treatment of coal for the production of clean solid fuel and/or liquid turbine fuel US3671418A (en) 1972-06-20 Coal liquefaction process using ash as a catalyst GB1574446A (en) 1980-09-10 Treatment of coal for the production of clean solid fuel and/or liquid turbine fuel Legal Events Date Code Title Description 1980-11-26 PS Patent sealed 1983-09-07 PCNP Patent ceased through non-payment of renewal fee
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