CA1141315A

CA1141315A - Method for conversion of solid carbonaceous materials to fluid products

Info

Publication number: CA1141315A
Application number: CA000341178A
Authority: CA
Inventors: Leonard Messer
Original assignee: American Minechem Corp
Current assignee: American Minechem Corp
Priority date: 1978-12-04
Filing date: 1979-12-04
Publication date: 1983-02-15
Also published as: GB2037809B; FR2443285A1; FR2443285B1; BE880432A; NL7908769A; GB2037809A

Abstract

ABSTRACT OF THE DISCLOSURE

Solid carbonaceous materials and particularly coal are converted to gas hydrocarbon liquid by forming an aqueous slurry in which an amalagam of carbonaceous and non-carbonaceous particles are suspended in water. The slurry is mixed together with an agglomerating liquid lyophobic to water and non-carbo-naceous particles and lyophilic to carbonaceous particles to form a mixture, and the mixture is agitated to preferentially agglomerate carbonaceous fine particles to form discrete agglo-merates having chemical and physical properties which are known and which are substantially uniform and constant. The non-carbon-aceous fine particles remain substantially unagglomerated in the slurry and are separated from the discrete agglomerates.
The discrete agglomerates or reconstituted particles are then heated to greater than 1500°F and preferably greater than 2000°F
in a controlled atmosphere to convert them into a gaseous product of unique purity and properties. Alternatively, the reconstituted particles or discrete agglomerates are to a temperature of about 750°F to 1000°F under controlled conditions to form a liquid product.

Description

ACRGROUND OF TRE INVENTION
FIELD OF THE INVENTION

The present invention relates to conversion of carbo-naceous materials, particularly coal, into gaseous or liquid products.

DESCRIPTION OF THE PRIOR ART

With the steady increase in the demand for hydrocarbon products of petroleum and natural gas and a growing reliance upon imported petroleum and natural gas to satisfy this demand, there has been increased emphasis on development of alternative sources of energy. In view of the relatively large domestic supply of available coal, the advance of mining technology, and the faster rising cost of other forms of energy, more complete exploitati~n of our coal resources has become increasingly more attractive.

Processes for the conversion of coal into liquid and gas fuels are described in the literature. For example, the

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~urgi, Koppers-Totzek, Hygas, CO2 Acceptor, BiGas, and Synthane and other related processes convert different grades of solid coal into various gaseous products. Similarly, the PAMCO and Synthoil processes convert solid coal into liquid products.

Coal is generally classified into grades of anthracites, semi-anthracites, bituminous, and sub-bituminous coals, and lignites.
Most conversion processes have tended to use bituminous, semi-bituminous and lignitic non-caking coals which are generally the feed to steam and electric generating plants. Anthracites and semi-anthracites are generally not suited for conversion because they are low in volatiles, tend to be unreactive, are in relatively short supply, and generally have a ready market in domestic and commercial central heating systems.

Low grade lignites have generally been considered un-satisfactory for known conversion processes because of their low calorific value and their high water and ash contents. Since conversion processes of the prior art have generally been in competition for bituminous, sub-bituminous, and non-coking coal with steam and electric power generation, coal conversion has been economically feasible only where substantial reserves of bitummous, sub-bitummous, and non-coking coal are located distant from substantially industrialized or populated areas. Thus, even though coal is a relatively plentiful resource, few of the known coal reserves are suited for economical conversion to a fluid product in accordance with prior conversion processes.

i315 The known conversion systems are in general slow and energy intensive in that they involve heating of the coal to typically between 750F and 2000F, and separation of heated waste solids from the liquified or gasified carbonaceous material.
In liquification processes, the separation has been performed by filtration and centrifuging processes which are relatively slow, incomplete and limit the speed of the process. In gasifica-tion processes, the separation has been performed by scrubbers which are expensive to build and expensively require large amounts of energy to operate. Additionally, in all such processes, the solid wastes must be cooled, with an accompanying loss of additional energy, and removal to a disposal area.

Certain impurities in the coal have been identified as undesirable pollutants that form stable oxides, most notably sulphur oxides, in the conversion process and report as exhaust emission. Another such impurity is nitrogen. Some of the volatile metalic impurities can also be included in the gas or liquid product of the conversion. These include arsenic beryllium, cadmium, lead, mercury, and selenium. Accordingly, prior con-' version ~ystems have also been limited by environmental controlswhich are required by state and federal regulations.

Coal conversion processes to date have usually attempted to control emissions of pollutants through the installation of pollution control equipment on the ~ystem. This has, however, necessitated equipment of increased size and complexity, and has substantially increased capital costs and operating costs, as well as consumption of energy to operate the pollution control e~uipment.

' ) li4i3i5 The present invention substantially reduces, eliminates, and avoids these disadvantages of the previous coal conversion systems. It sharply reduces the energy requirements for con-version and the environmental hazards and control requirements for conversion. At the same time, the invention increases the processing speed by avoiding quenching difficulties with solids present in the separation of large quantities of solid particulate from the qas or liquid product. The invention provides a purified product free of large quantities of impurities and eliminates solid disposal difficulties present in previous systems. It also provides a product of improved quality that can be produced from coal deposits previously considered unacceptable for con-version to fluid products.

SUMMARY OF THE INVENTION

The present invention provides a simple method of rapidly converting carbonaceous material into a fluid product of a liquid or gaseous hydrocarbon. The present method also provides a fluid hydrocarbon product of unique purity and quality.

An amalgam of carbonaceous and non-carbonaceous fine particles, preferably of ash and coal, are first dispersed in a suspension liquid such as water to form a slurry. The fine particles are preferably formed by comminuting coal from a mine head in a ball mill, agitated-media mill or the like. Alterna-tively, the fine particles may be the waste from a coal washing plant or refuse from a settling pond of a coal washing plant.

~1~1315 Added to the slurry is an agglomerating liquid lyo-phobic to both the suspension liquid and the non-carbonaceous fine particles and lyophilic to the carbonaceous fine particles.
The agglomerating liquid is preferably a hydrocarbon that can be volatilize`d and/or carbonized along with the carbonaceous fine particles as hereinafter described, having an initial boiling point greater than abou~ 149F (65C) and preferably greater than 302F (150C).

The mixture is then agitated to preferentially agglo-merate the carbonaceous fine particles into discrete agglomerateswhile leaving the non-carbonaceous fine particles substantially unagglomerated in the mixture. Thereafter, the agglomerated carbonaceous fine particles are separated from the mixture.
The chemical and physical properties of the discrete agglomerates are substantially uniform throughout and are substantially con-~tant for a considerable period of time. The size and packing (density) of the agglomerates have substantial uniformity, and the size can be controlled by the composition and percentage `` of the liquid and the degree and duration of the agitation.
The ash content is uniform and low, ~enerally less than 4 to 6.5 percent. The moisture content of the discrete agglomerates is uniformly distributed throughout and typically is in the range of about 7 to 20 percent. The agglomerating liqu~d coats the ~oal particles of the discrete agglomerates to make the agglom-erates substantially inert to atmospheric oxidation such that he chemical and physical properties of the agglomerates remain constant for substantial periods of time. After separation, the discrete agglomerates are heated to greater than 750F in a controlled atmosphere to form a fluid hydrocarbon product.

11 ~1315 The hydrocarbon product thus formed may be liquid or gas depending on the heating temperature and rate and the chemical composition of the controlled atmosphere. In any case, the hydro-carbon product has unique properties caused by the uni~ue purity and uniform and constant chemical and physical properties of the discrete agglomerates. Specifically, a higher yield of the hydrocarbon product is produced owing to the uniform size, packing, moisture content and oxidation of the discrete agglomerates.
Also, the hydrocarbon product has notably reduced solid contamina-tion and substantially-lessened impurities such as sulphur, lead, beryllium, cadmium, and the like due to the separation of the non-carbonaceous material. As well as a higher calorific value than products of conversion process known to the prior art due to the benefication of the coal by the hydrocarbon agglomerating liquid.

Other details, objects and advantages of the present invention will become apparent as the following description of the presently preferred methods of practicing and making the same proceeds.

BRIEF DESCRIPTION OF THE D~AWING

In the accompanying drawings, the presently pre~erred em~odiments of the invention and the presently preferred methods of practicing the invention are shown in which:

Figure 1 is a schematic illustrating a method for con-verting coal to a gas in accordance with the present invention;

Figure 2 is a schematic illustrating another method for converting coal to a gas in accordance with the present in-vention;

Figure 3 is a schematic illu~trating a method for con-verting coal to a liquid in accordance with the present invention;
and Figure 4 is a schematic illustrating another method for co~verting coal to a liquid in accordance with the present invention.

DESCRIPTION OF T~E PREFERRED EMBODIMENTS

The reactions that are fundamental to the conversion of carbonaceous material.can be described as hydrogenation or, alternatively, decarbonization. As used herein, hydrogenation ~8 defined to be the addition of hydrogen to a more compiex hydro-carbon molecule and decarbonization is defined to be the removal a source of the carbon from a more complex hydrocarbon molecule.

Conversion of coal into a fluid product basically in-volves the conversion of a heavy hydrocarbon having a carbon to hydrogen atomic ratio of about 1:1 into methane, which has a carbon to hydrogen ratio of 1:4. Hydrogenation generally occur~ either through hydrogenolysis, in which gaseous hydrogen is reacted with the heavy hydrocarbon according to the general formula:
Cn~m ~ 2 g2 nC84 ~1) 11 ~131S

or hydrolysis, in which steam is reacted with the heavy hydro-carbon according to the general formula:
CnHm + xH20 Y CH4 + z C02 + wH2 (2) In decarbonization processes, a carbon product such as carbon dioxide, coke or char is formed and then removed from the system.
Carbon dioxide is formed by oxygenolysis in which the hydrocarbon is heated with oxygen according to the formula:
~ nHm 4n-m 0 _ CH4 + 4n4m C02 (3) The carbon dioxide is generally removed by scrubbing the gas with amine or hot potassium carbonate solution. Char is normally formed by pyrolysis, o~ heating the hydrocarbon to crac~ing tem-peratures. Pyrolysis proceeds according to the formula:
CnHm 4m CH4 + 4n4m C

In the course of sny of the basic conversions, a large number of intermediate compositions are formed. Specifically, the chemical equilibrium that determines the product yields of the conversion process are believed to be as follows:

1~4i315 Equilibrium in Conversion Reactions ReactionHeat of reaction Volume Equilibrium No.
H(kcal/mole at change constant 298K ~25C)) (~V) (Kp) C + 2 - C2 -94.056 1 to 1 (C2) (5) C + CO2 ~CO +41.203 1 to 2 ~Co)2 ~6) (co2) C + H20 - H2 + CO +31.3561 to 2(H2)(C) t7l CO + H O H + CO -9.847 2 to 22)l 2) (8) ~CO) (H20) CO + 3H2 CH4 + H2O _49.2434 to 2(C84)lH20~ (9 (CO) ~H2) C 2H2---CH4 -17.8892 to 1 2 (H2 ) C2 + 4H2CH4 + 2H2O _39,4105 to 3(CH4)(H2O) (11) ~C2 ) (H2 ) C + 2H2O2H2 ~ C2 +21.5102 to 3~H2) (CO2) (12) (H20) 20CH4 + CO22CO + 2H2 +59'0932 to 4~Cl ~ 2) (13) 2C + H2---C2H2 +54.1631 to 1~C2H2) (14) 2CH4 - C2H2 + 3H2 +89.9182 to 4(C2H2)(H2) (15) (CH4) 2CH4---C2H4 1 2H2 l48.2462 to 3~C2H4)(H2) (16) ~CH4) C2H6---C2H4 + H2 +32.7101 to 22~4l(U2~ (17) CH4 ~ ~2 - CO + 3H2 +49.2422 to 4~CO)(H2) ~i8) . (CH4)(H2o) :'~

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Development of coal conversion processes has been com-plicated by the fact that not only do most of the reactions of Table 1 occur at some point in the conversion of the coal to a fluid product, but also at some stage of the conversion, most of the above equilibria are believed to coexist. The most im-portant consideration in designing a coal conversion process in view of the foregoing equation is the enthalpy change ~H) of the different reactions. The enthalpy, or heat of reaction, is a measure of the endothermicity (~) or exothermicity (-~) of the reaction and therefore indicates whether supplying heat or withdrawing heat will drive the reactions 5-18 toward the right or left. In order to produce a lower molecular weight fluid product from the higher molecular weight materials found in coal in the most efficient and economic fashion, it is im-portant to balance the enthalpy change of the various steps, thereby minimizing the net thermal energy transfer to or from the process.

In accordance with the foregoing table, the volume, change ~V) indicates whether the effect of a pressure increase would be to drive the equilibrium to the right or to the left depending upon the volume charge.

The equilibrium constant (Rp) indicates the composition of the final gas mixture at a given temperature after chemical equilibrium is established. Table 2 is a list of values of the respective equilibrium constants of each reaction in Table 1 for three different temperatures.

Value of Equilibrium Constant Kp in Conversion Reactions Equilibrium Value of K
constant 980F 134~F 1700F
(Kp)at~(527C~ (727C) (927C) (CO2) 6.709 x 1025 4.751 x 102 1.738 x 1017 (5)' (2) (co)2 1.098 x 10 2 ~.9OO 57.09 (6)' (H2)(CO) 4.399 x 10 2 2.609 39.77 (7) (H20) 10~H2)~CO2) 4.038 1.374 0.6966 (8)' (CO) ~H20j ~CH4)(H2O) 8.821 x 104.383 59.585 (9)' ~Co)(N2)3 (CH4) 1.411 9.829 x 10 1.608 x 10 ~10)' 2 ) ~CH4)(H2O) 2.185 x 103.190 85.537 (11)' 2 ) (H2 ) (H2) (CO2) 0.1777 3.608 28.01 (12)' (H20) 2~H )2 7.722 x 10 3 19.32 3.548 x 103 ~13)' ~CH4)~CO2) (C2H2) 1.602 x 10 12 1.337 x 10 91.156 x 10 7 ~14)' 2) 2H2)~H2) 8.017 x 10 13 1.384 x 10 74.474 x 10 4 (15)' ., ~CH4) li~l315 (C2H4)~H2)1.021 x 10 7 6.939 x 10 5 5.540 x 10 3 (16)' "
(CH4) (C2H4)(H2) 4.557 x 10 0.3443 6.224 (17)' (C2H6) ~Co)(H2)3 3.120 x 10 26.562.473 x 103 ~18)' (CH4)~H2O) Where Kp tends to increase with increased temperature, an in-crease in the process temperature will drive the reaction equi-librium of the respective equation in Table 1 to the right.
Where Kp tends to decrease with increased temperature, a de-crease in the process temperature will drive the reaction equi-li~r~um to the right.
The time in which equilibrium conditions will be es-tablished in reactions (5)-(18) is determined by the velocity constants of both forward and reverse reactions. The velocity constants are a function of the reactivity of the different species and, for many conversion reactions, the presence of a catalyst, either homogeneous or heterogeneous, is required in order to reach equilibrium conditions within an acceptable time.
Heterogeneous catalysts are materials that provide a fiurface on which reactions between gas molecules take place due to surface forces exerted by certain act~ve materials or centres. However these catalysts tend to attract molecules other tha~ those with which they are intended to react. Speci-fically, polar impurities of the coal such as sulphur, nitro-gen, oxygen, and metal compounds deposit on the catalyst, block the active ~i413~5 centres, and eventually poison ~he catalyst. Accordingly, it is essential for processes based on the catalystic conversion of coal that the reacting gases prepared from the coal be purified before they contact the catalyst.
-The presently disclosed process has been developedwith careful attention given to the considerations discussed above. The conversion steps carefully assess enthalpy considera-tions of the various reactions that occur and then carry out the conversion through an advantageous combination of stages.
lo In the various stages, pressure, temperature, volume, process rate, and other variables are controlled to achieve desirable product ratios.

In the prior art, conversion processes have assumed a carbonaceous feed material, typically coal, having physical and chemical properties which are known and which are constant throughout. However, both the physical and chemical properties of coal vary greatly from deposit to deposit and, furthermore, within the same deposit.

The carbonaceous molecules that are hydrogenated or decarbonized cover a broad range of molecular weights and structural complexity. Moreover, the carbonaceous feedstock is non-uniformly contaminated with non-carbonaceous material. Accordingly, prior coal conversion methods had to be individually adapted to the _ widely different grades and types of coal.

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Furthermore, surface effects such as oxidation and moisture cause variations in the properties of a single lump or a single particle of coal. The deviation in physical and chemical prop-erties of various grades of coal and nonuniformity of these properties within a single coal deposit have previously meant that a process designed for conversion of one grade of coal may have to be extensively modified or may even be unsuited for con-version of other grades of coal. In accordance with the present invention, carbonaceous materials of various grades and purities lo are converted to carbonaceous agglomerates having properties that are known and substantially constant despite variation in the properties of the carbonaceous feed material.

Referring to Figure 1, the carbonaceous material is converted to a fluid hydrocarbon product by first dispersing carbonaceous and noncarbonaceous fine particles of the carbo-naceous material in a suspension liquid to form a slurry 10.
l~ As used herein, ~fine particles" is specifically defined to mean small part~cles which are preferably less than ~.590 millimeters ~ in diameter (28 mesh Tyler) and typically less than 0.210 millimeters in diameter (65 mesh Tyler). As also used herein, ~carbonaceous material~ is hereby def~ned to include any raw material containing carbon which, when divided into fine particles, contains fine particles of both non-carbonaceous and carbonaceous materials.
Most desirably, the carbonaceous material is an anthracite or lower rank coal such that the carbonaceous fine particles are coal and the non-carbonaceous fine particles are ash. As used herein, ~ash~ fine particles are defined to include small par-ticles of materials such as clay and slate that generally appear as ash rather than volatiles on complete burning of coal.

'11~1315 Slurry 1~ may be formed in various alternative ways from such coal. For example, part$culate coal 11 may be con-veyed directly from a mine to a comminuting means 12. ~omminuting means 12 may be any suitable, commercially available comminuting means such as a ball mill. Comminuting the coal into small particles is effective in freeing sulfur compounds and other non-carbo-naceous particles. ~igh sulphur content, as for example from pyrites, is particularly undesirable in that, among other effects, it can interfere with subsequent reactions in the conversion process. This is especially true where catalytic reactions are included in the process. Other contamminents r~leased by comminuting the coal include oxygen and nitrogen containing compounds. Oxygen is undesirable in the conversion process particularly where hydrogena-tion is used because, it increases hydrogen consumption. The presence of nitrogen in the coal will result in the presence of ammonia or nitrogen oxides in the fluid product, thus dilutinq the calorific value thereof.

Alternatively, slurry 10 may be underflow 14 from a conventional coal washer, which typically has a relatively low solids content of about 5 to lS percent solids in water. Vnder-flow 14 may be mixed with refuse slurry 15 of coal and ash f~ne particles of relatively high solids content, i.e. at least about 50 percent solids, formed by a water dispersion of the sediment of an existing settling pond adjacent the coal washing plant.
The mixing of underflow 14 and refuse slurry 15 should provide a slurry 10 of about S to 40 percent and most typically 20 to ~S percent solids of coal and ash fine particles. In this case, the carbonaceous and non-carbonaceous particles are already ~1 ~131S

sufficiently small so that sulfur compounds and other non-car-bonaceous particles are free in the slurry.

Slurry 10 is processed in agitator apparatus 16 to preferential~y aqglomerate the carbonaceous (e.g. coal) fine particles, while the non-carbonaceous (e.g. ash) fine particles remain substantially unagglomerated and dispersed in the slurry.
Added to slurry 10 at the inlet to agitator apparatus 16 is ag-glomerating liquid 17, which is lyophobic to both the suspension liquid (e.g. water~ and to non-carbonaceous fine particles and lyophilic to the carbonaceous fine particles to form a mixture.
~Lyophilic~ as herein used means that, in a disperse system, there is a marked affinity (wettability) between a disperse com-ponent and the dispersion medium and/or another disperse com-ponent. Some examples are glue and water, or rubber and benzene.
~Lyophobic~ as used herein means that, in a disperse system, there is substantially no affinity (wettability) between the disperse compenent and the dispersion medium and/or another dis-perse component. Examples are oil and water, or colloidal ~so-lutions~ of metals.

Agglomerating liquid 17 is preferably a hydrocarbon liquid that can be converted along with the carbonaceous fine particles as hereinafter described. Materials particularly suit-able for agglomerating liquid 17 are hydrocarbons having an initial boiling point greater than about 147F (65C). and preferably greater than 302F ~150C). Specifically suitable are light oil, light fuel oil, heavy fuel oil, and kerosene. Also suitable ~re creosote, filtered anthracene oil, hydrogenated filtered `13iS

anthracene oil, lubricating oil such as SAE 20, and chlorinated biphenyls. Heavy hydrocarbon materials such as a heavy crude petroleum, crude shale oil or coal tar are not preferred. ~eavy hydrocarbon liquids typically contain molecular groups lyophilic to non-carbo~aceous fine particles as well as carbonaceous fine particles and, therefore, do not provide the degree of separation of carbonaceous fine particles from non-carbonaceous fine particles preferred in the present method. In addition, such heavy hydro-carbon li~uids often need ~o be heated to provide sufficient fluidity for the operation of the present invention.

Agglomerating liquid 17 is selected and added in meas-ured amounts to control the agglomeration of carbonaceous fine particles as hereinafter described. Preferably, liquid 17 is added in amounts of about 2 to 10 percent by weight and most desirably between 3 and 7 percent by weight of the total solids in slurry 13 for high recovery, (e.g. 88-89 percent by weight).
Greater amounts of liquid 17 up to and exceeding 30 percent by weight may in some instances be utilized. Rowever, such lesser and greater amounts are not preferred because, on the one hand, sufficient agglomeration and binding of coal fine particles is not provided while, on the other hand, a waste of highly refined petroleum or coal tar derivative results.

The mixture of slurry 10 and agglomerating liquid 17 are mixed and agitated in agitator apparatus 16. Agitator appara-tus 16 may be any suitable agitating apparatus such as a modified turbine, a disc or cone impeller mixer, or a tank with recircu-lation. Preferably, however, agitator apparatus 16 is a tank llL~i3iS

equipped with a motor driven high shear impeller 18 extending to the bottom portion of the tank.

During agitation in agitator apparatus 16, the car-bonaceous fine particles are preferentially wetted by agglomer-ating liquid 17, which is preferably immiscible in water, and the carbonaceous fine particles are agglomerated into coarser particulate. The size of the agglomerates is primarily deter-mined by the composition and the percentage of liquid 17 added to slurry 10, and is controlled to provide the desired size and density for efficient conversion to the gaseous and liquid pro-duct. For the preferred percentage of 2 to 10 percent by weight of liquid 17, the agglomerates typically have sizes of from about 1 to 2 millimeters. The time required to effect agglomeration is generally dependent upon the degree of turbulence or agita-tion, with the shorter agglomeration time being associated with the higher agitation speed. The degree and duration of the agi-tation in apparatus 16 is also controlled to provide the desired size and packing (density) of the agglomerates.

The carbonaceous agglomerates, being impregnated and having absorbed on the surfaces thereof liquid 17, which is gen-erally less dense than the suspension liquid, will tend to float to the top of the mixture. Agglomerated first mixture 19 is thus removed from the top of agitator apparatus 16 to a separa-tor 20, where the carbonaceous agglomerates 22 are separated from the suspension liquid and unagglomerated non-carbonaceous fine particles by size and/or density. Preferably, separator 20 is a sieve bend of an appropriate mesh size, e.g. 100 or 200 li ~l;~i5 mesh Tyler, such as that manufactured by authority from DSN NV
Vedernaldse Staatsmijnen. Alternatively, other types of sepa-rators such as an elutriator, cyclone or spiral fieparator, which are commercially available, may be utilized. Alternatively, the carbonaceous agglomerates 22 may be also separated in a float-sink tank where the carbonaceous agglomerates 22, which tend to float, are skimmed off by a rotating paddle through an over flow, while the water and unagglomerated non-carbonaceous fine particles, which tend to sink, are removed from the bottom of the tank as slurry 21 containing the non-carbonaceous fine par-ticles and substantially free of carbonaceous fine particles and agglomerating liquid.

Carbonaceous agglomerates 22 have low ash and impurities content, uniform size and packing (density), and even distribu-tion of moisture throughout the agglomerates. Typically, the moisture content of the discrete agglomerates is in the range of about 7-10 percent. The low content of non-carbonaceous materials, typically less than about 4-6.5 percent, and uniform size and packing as well as the uniform distribution of moisture throughout the discrete agglomerates permits the ~ubsequent steps of the conversion process to proceed in predictably and effi-ciently in accordance with the design of the various stages of the process.

The calorific value of the fluid product is generally dependant on the calorific value of the carbonaceous agglomerates 22. The inclusion of agglomerating liquid 17, which is a hydro-carbon, in agglomerates 22 beneficiates the calorific value of 11 ~13i5 the agglomerates and therefor, improves the quality of the fluid product by beneficiating its calorific value.

The quality of the fluid produced in accordance with the presently disclosed method is further improved in that ag-glomerates 22 are protected from partial oxidation of the coal particles by exposure to air. Agglomerating liquid 17 coats the individual coal particles and thereby protects them from oxidation prior to the conversion process. Partial oxidation of agglomerates 22 i8 undesirable for this reason that it de-stroys the uniformity of the chemical and physical propertiesthereby effecting the efficiency of the conversion process and the quality of the fluid product by altering the conversion proc-ess in accordance with equations 5-19. Accordingly, agglomerates 22 are resistant to changes in their chemical and physical composition caused by oxidation and can be stored for substan-tial periods, for example 4-6 months, without applicable oxidation.
Moreover, agglomerates 22 require no special storage facilities and ~an be stored in open stockpiles if desired.

At this stage, separated carbonaceous agglomerates 22 may be processed ~not shown) by pelletizing int~ larger par-t,iculates. The agglomerates may be pelletized to generally uni-form particle sizes of 0.10 to 1.0 inch in diameter by feeding the agglomerates to a pelletizing disc or tumbler along with a binder liquid to form a second mixture and then agitating said mixture. Alternatively, the agglomerates may be agitated, ex-truded or otherwise molded into pellets upon addition of a binder liquid to form said second mixture. Binder liquids particularly ~1~131S

suitable for this purpose are heavy hydrocarbons such as coke-oven coal tar, crude shale oil, petroleum crude or heavy fuel oil such as Bunker C, which is preferably heated to, for example, 100C., to bond the binder to and within the agglomerates. ~eating in this manner will also further serve to dewaterize the aqglomerates uniformly, typically to the range of about 5 to 12 percent moisture.
An accelerator is also preferably included in the binder liquid to hasten bonding of the binder in shorter times and/or at lower temperatures. The heavy hydrocarbon binder liquid serves to further beneficiate the discrete agqlomerates without disturbing the uniform chemical and physical properties of the discrete agglomerates 22. Accordingly, the quality of a fluid conversion product of the pellets is further improved by increasing the calorific value of the fluid product. Also, the addition of the heavy hydrocarbon builder liguid enhances the inertness of the carbonaceous material to atmospheric oxidation so that the chemical and physical properties of the pellets remain uniformly constant for even longer periods than the discrete agglomerates 22.

A variety of steps for the final conversion of carbo-naceous agglomerates 22 to a fluid product may be alternatively used in accordance with the presently disclosed invention. These various final conversion steps are comprised of various process stages that are designed to 6elected ash and moisture contents for the optimum conversion of the carbonaceous agglomerates 22 to a fluid product based on the physical and chemical properties of carbonaceous feed material. Advantageously, the above described steps for removal of the non-carbonaceous or ash fine particles li~l31S

from the carbonaceous particles results in carbonaceous agglomerates 22 having a low, uniform and generally constant ash and moisture content regardless of the source or quality of the carbonaceous material added to the slurry 10. Specifically, agglomerates 22 have an ash content of generally less than 6.5% for most coals and generally less than 4% for higher grade coals, and have a moisture content of generally about 5 to 12 percent. Accordingly, regardless of which particular conversion step is used and despite the preferred ash and moisture content for achieving optimum conversion of the carbonaceous material to a fluid product in accordance with the design of the particular conversion step employed, optimum conversion for any selected process may be attained by introducing where necessary, an appropriate quantity of ash and/or water to the carbonaceous agglomerates ~2. Since the ash and moisture content of carbonaceous agglomerates 22 is known, the quantity of ash and/or moisture which is to be introduced in accordance w$th the optimum conversion for the particular method is also known. Moreover, since the ash and moisture content of the carbonaceous agglomerates 22 is substan-tially uniform, the additional ash and/or moisture can be intro-duced at a constant rate. Accordingly, existing conversion proc-esses can be modified and new processes designed without regard to the peculiar physical and chemical properties of a particular source of carbonaceous feed material such as a particular deposit of coal.

Accordinq to the conversion method illustrated in Fig-ure 1, the final conversion step converts the agglomerates 22 i31S

to synthesis gas, a mixture of carbon monoxide and hydrogen that can be converted to methane or heavier hydrocarbons in the presence of a catalyst. The final conversion step is based on the partial oxidation of agglomerates 22 in the presence of oxygen and steam.
When necessary, the carbonaceous agglomerates 22 are given a moisture content of 2 to 8 percent by adding water 24 and are then reduced to about 70~ through 200 mesh fineness in a size reducerv 26. Nitrogen 28 or other non-oxidizing gas is added to the size reducer 26 and the smaller sized agglomerates are carried in a nitrogen stream to a service bunker 30. The pul-verized coal agglomerates are then discharged into a stream of oxygen 31 and steam 32 to a gasifier 34 in which they are par-tially oxidized. Gasifier 34 is a refractory-lined, horizontal, cylindical vessel with conical ends. Gasifier 34 is provided with a steam jacket 36 which cools the refractory and burners of gasifier 34 and generates the steam 32 used in the partial oxidation of the pulverized agglomerates in gasifier 34. Under atmospheric or slightly positive pressure and a flame temperature of about 3,300F. - 3,500F., the agglomerated dust, oxygen and steam react at the burner heads of gasifier 34 to form crude synthesis gas 38 which contains carbon monoxide and hydrogen.

Approximately one-half the ash content remaining in the pulverized agglomerates precipitates in gasifier 34 as molten slag which is cooled in a slag quench tank 40. The unprecipitated ~sh reports with the synthesis gas 38 which, as it leaves gasifier 34, i8 water quenched in a primary washer 41 to scrub out the entrained ash. The gas stream is then passed through a secondary ll~i3~S

washer 42 to reduce further the quantity of entrained solids and through a gas cooler 44 to lower the gas temperature to about 95F. ~he cooled gas is then cleaned of remaining entrained particles in a disintegrator 55.

A waste heat boiler 46 recovers heat from the slag quench tank 40 and generates high pressure steam 48 which may be applied to turbine drives of compressors or pumps. Water from primary washer 41, secondary washer 42, and gas cooler 44 is pumped to a clarifier 50 which removes the slag particulates as 81udge 51. The cla~ified water is pumped from the clarifier 50 to a cooling tower 52 and is then recirculated through the gas cleaning apparatus. A stream of water 54 is added to make up for evaporation and windage losses at the cooling tower 52 as well as moisture losses in the clarifier sludge 51.

Synthesis gas 38 is composed principally of carbon monoxide, carbon dioxide and hydrogen. The major impurities are nitrogen and hydrogen sulfide which are generally removed either by a chemical reaction process or by a physical absorption process ~not shown). Synthesis gas 38 can be processed to yield various chemicals, such ~s hydrocarbons, ammonia, or methanol.
Alternatively, synthesis gas 38 can also be converted to pipeline quality gas by further cleansing the gas in precipitators followed by desulfurization, water gas shift conversion, removal of excess carbon dioxide, and methanation. (see equation (9).

Figures 2, 3 and 4 illustrate alternative embodiments of the presen~ invention in which carbonaceous agglomerates 22 are produced in the same manner as described with respect to 11 ~131S

Figure 1. Accordingly, the same reference characters have been applied to like parts of Figures 2, 3 and 4, and the practice of the method is described in the same manner as with respect to Figure 1. However, in Figures 2, 3 and 4, carbonaceous agglom-erates 22 are converted to different products by alternative final conversion steps.

In Figure 2, carbonaceous agglomerates 22 are reduced to -20 mesh carbonaceous particles in a size reducer 58 and placed in a fluidised bed pretreater 60 together with steam and oxygen.
The mixture of carbonaceous particles steam, and oxygen is main-tained at of about 1000-psig pressure and a temperature of about 800~F to perform surface oxidation of the carbonaceous particles and retard their a3glomeration property. The partially oxid zed, carbonaceous particles are then provided to the top of a gasifier 66 wh~le additional steam and oxygen are provided to the bottom of the gasifier 66 such that a fluidized bed of carbonaceous particles is maintalned in gasifier 66. Gasifier 66 i6 operated at a typical pressure of about 1,000 psi ~nd a typical temperature of about 1,800F to produce a product gas 67 and char 68 from the carbonaceous particles.

Product gas 67 is taken off the top of gasifier 66 while char 68 is removed from the bottom. Preferably, the char is used to fire a boiler (not shown) that produces the steam required for the process. ~roduct gas 67 contains tar, particu-lates, sulfur compounds, and light oil. The tar and particulates are removed from product gas 67 by a spray tower 68. The cleaned gas is passed through a shift converter 70 to produce carbon monoxide and hydrogen with the desired ration of hydrogen to carbon monoxide. The carbon mono~ide and hydrogen from shift converter 70 are cleaned in a hot carbonate scrubber 72 and sulfur cleaning apparatus 74. The cleaned gas having the correct ratio of hydrogen to carbon monoxide is converted in a catalytic methanator 76 to produce pipeline gas. Preferably, methanator 76 is of a type employing nickel catalysts.

In the process of Figure 3, carbonaceous agqlomerates 22 are converted into primarily liquid products. The carbonaceous agglomerates are reduced to carbonaceous particles 81 of about 70% -200 mesh in size reducer 80. Carbonaceous particles 81 are provided to a feed tank B2 in which they are mixed with a portion of the product oil 84 to form a slurry 86. ~ydrogen rich gas is added to slurry 86 and this mixture is introduced under turbulent flow conditions to a fixed-bed reactor 88 containing an immobilized Co-Mo/SiO2-A12O3 catalyst. The temperature within reactor 88 is typically about 850~F and the pressure is in the range of about 2,000-4,000 psi. The output product of reactor 88 18 provided to a vapor/liquid separator 90 in which the gases are ~eparated from the liguids and unreacted solids. The llquid and solid mixture is passed to a centrifuge 92 to remove the unreacted solid particles. The liquid from centrifuge 92 is product oil 84, a portion of which is recycled to feed tank 82 to form slurry 86. The solids from centrifuge 92 are provided to a pyrolyzer 93 to yield an additional quantity of product oil together with gases and a carbonaceous residue generally consisting of mineral matter.

11'~1315 Gas from vapor~liquid separator 90 is provided to a gas separator 94 which removes NH3, ~2S and gaseous hydrocarbons from the hydrogen in the gas. The NH3 and ~2S are useful by-products. The hydrogen is recycled to reactor 88. The residue and gases from the pyrodizer 93 and the gaseous hydrocarbons from the gas separator ~4 are provided together with water and oxygen to a gasifier 96 and a shift converter 98 to provide make-up hydrogen. The make-up hydrogen together with the hydrogen provided by the gas separator 94 are added to the slurry 86 that lo is fed to reactor 88. If necessary, some of the ground carbon-aceous particles 81 can be added to the gasifier 96 and shift converter 98 to prepare a volume of hydrogen sufficient for the process requirement.

In Figure 4, carbonaceous agglomerates 22 are converted to synthetic crude oil, as well as to gas and a combustible char by yet another conversion process. Carbonaceous agglomerates 22 are reduced to granules of less than 1/8 inch diameter in a size reducer 100 and pyrolyzed at successively higher temperatures in a series of four fluidized bed reactors 102-lOS in this example.
A fraction of the volatile matter of the carboneous granules is released in each fluidized bed. The temperature of each bed is selected to be slightly lower than the temperature at which the granules will agglomerate and defluidize the reactor bed.
A typical temperature of each reactor 102-105 is about 600F., 850F., 1,000F. and 1,500F. respectively.

In reactor 105, a mixture of oxygen and steam is intro-duced at the bottom to provide process heat and hot crude synthesis ~i ~13i5 gas and flows against the movement of the carbonaceous granules such th~t the mixture passes upward through reactors 103-105 to fluidize the beds. The volatile matter removed from reactors 103-105 is carried to a scrubber 105' that condenses an oil-water mixture produced from the coal-tar vapors of the volatile matter by contacting the product gas stream with water. The condensed oil-water mixture is then sent to a separator 1~6 which ~eparates gases 108 from the condensed oil-water mixture and removes the water from the mixture by phase separation and dehydration to provide condensed oil 110. The gas 108 from separator 106, together with gas 112 from reactor 102 is delivered to a scrubber 114 such that synthesis gas 116 is provided at the output of the scrubber 114. Synthesis gas 116 is introduced at the bottom of reactor 102 and flows against the movement of the carbonaceous granules such that gas 116 passes upward through reactor 102 to fluidize the bed. Condensed oil 110 is provided to a filter 117 which removes solids carried from reactors 102-105. Oil from filter 117 is provided to a fixed bed hydro-treatment 117' where it is treated with hydrogen that is separated from the synthesis gas of scrubber 114 by a separator 115. The treatment of the oil with hydrogen in fixed bed hydro-treatment 117' removes sulfur, nitrogen and oxygen from the filtered oil and provide a high quality synthetic crude oil 118. It is preferred that hydrotreating be done at a temperature in the range of 700-800F.
in the presence of a nickel-molybdenum catalyst. Residual char is removed from reactor lQ5. It can be gasified to produce fuel gas, burned as a boiler fuel to assist in heating reactors 102-104, or used to produce hydrogen for treating the oil in fixed bed hydro-treatment 117'. Other process methods are adaptable to ~ coal feed of constant composition.

11 ~i315 Advantageously, the present invention is to~ally com-patable with the efficient transportation of the purified carbo-naceous material. Thus, when the final conversion of the carbo-naceous material is performed at a location remote from the source of the carbonaceous material, carbonaceous agglomerates 22 are readily transportable to the conversion site. Preferably, car-bonaceous agglomerates 22 are transported in a liquid slurry.
Alternatively, carbonaceous agglomerates 22 can be shipped in conventional transportation, such as covered railroad hopper cars, or briquettes can be formed from agslomerates 22, which are then reduced to the proper size distribution prior to con-version.

In accordance with the foregoing description, a method for the conversion of a carbonaceous material to a fluid product has been described in which non-carbonaceous particles are re-moved from the carbonaceous material prior to the gasification or liquidation step. The efficiency and economy of the final conversion step are thereby improved since significantly less non-carbonaceous material remains to be separated from the fluid product by relatively difficult and expensive purification or clarification procedures. Furthermore, the disclosed method for conversion of carbonaceous material improves the rate of conversion of the carbonaceous material into fluid product because the carbonaceous agglomerates developed in the process have a higher carbon content, they are substantially uniform and con-stant physical and chemical properties, and because less non-carbonaceous material is processed through the final conversion step where removal of non-carbonaceous material is relatively i31S

slow, difficult, and expensive. Also, the disclosed method is completely compatible with situations in which the conversion step is performed at a location which is remote from the source of the carbonaceous material since the carbonaceous agglomerates are readily transportable, preferably as a liquid slurry that is pumped through pipelines.

While preferred embodiments of the invention have been specifically described, it is to be understood that the invention may be otherwise variously embodied and used within the scope lo of the following claims.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A method of converting a solid carbonaceous material into a fluid comprising the steps of:
A. dispersing an amalgam of carbonaceous and noncar-bonaceous fine particles in a suspension liquid to form a slurry of 60% to 95% water by weight;
B. adding to the slurry a liquid that is lyophobic to the suspension liquid and the noncarbonaceous fine particles and lyophilic to the carbonaceous fine particles to form a mixture in which the liquid is less than 10% of the combined weight of the carbonaceous and noncarbonaceous fine particles, said liquid having an initial boiling point greater than about 149°F;
C. agitating the mixture to preferentially agglomerate carbonaceous fine particles into discrete carbonaceous agglomerates while said noncarbonaceous fine particles remain substantially unagglomerated in the mixture, said discrete agglomerates having a substantially uniform ash content of less than about 6.5% by weight, said agglomerates being substantially inert to atmospheric oxidation for a substantial period of time;
D. separating the discrete agglomerates from the mix-ture;
and E. heating the separated discrete agglomerates to at least 750°F to convert the agglomerates to a fluid product.

2. A method of converting a solid carbonaceous material into a fluid as set forth in Claim 1 wherein:
Step C includes agitating the mixture to preferentially agglomerate carbonaceous fine particles into discrete agglomer-ates that have a substantially uniform moisture content in the range of about 7% to 20% by weight; and Step E includes heating the separated discrete agglomer-ates to form a liquid product.

3. A method of converting a solid carbonaceous material to a fluid as set forth in Claim 1 wherein:
Step C includes agitating the mixture to preferentially agglomerate carbonaceous fine particles into discrete agglomerates that have a substantially uniform moisture content in the range of about 7% to 20% by weight; and Step E includes heating the separated discrete agglomer-ates to form a gaseous product.

4. A method of converting coal into a fluid comprising the steps of:
A. dispersing an amalgam of coal fine particles in a suspension liquid to form a slurry of 60% to 95% water by weight;
B. adding to the slurry a liquid lyophobic to the sus-pension liquid and noncarbonaceous fine particles in the coal and lyophilic to carbonaceous fine particles in the coal to form a mixture in which the liquid is less than 10% of the combined weight of the carbonaceous and noncarbonaceous fine particles, said liquid having an initial boiling point greater than about 149°F.

C. agitating the mixture to preferentially agglomerate carbonaceous fine particles into discrete carbonaceous agglomer-ates while said noncarbonaceous fine particles remain substantially unagglomerated in the mixture, said discrete agglomerates having substantially uniform ash content of less than about 6.5% by weight, said agglomerates being substantially inert to atmospheric oxidation for a substantial period of time;
D. separating the discrete agglomerates from the mix-ture, and E. heating the separated discrete agglomerates to at least 750°F to convert the agglomerates to a fluid product.

5. A method of converting coal into a fluid as set forth in Claim 4 wherein:
Step C includes agitating the mixture to preferentially agglomerate carbonaceous fine particles into discrete agglomerates that have a substantially uniform moisture content in the range of about 7% to 20% by weight are substantially inert to atmospheric oxidation, and Step E includes heating the separated discrete agglomer-ates to form a liquid product.

6. A method of converting coal to a fluid as set forth in Claim 4 wherein:
Step C includes agitating the mixture to preferentially agglomerate carbonaceous fine particles into discrete agglomerates that have a substantially uniform moisture content in the range of about 7% to 20% by weight, and Step E includes heating the separated discrete agglomer-ates to form a gaseous product.

7. A fluid made from a solid carbonaceous material and prepared by:
A. dispersing an amalgam of carbonaceous and non-carbonaceous fine particles in a suspension liquid to form a slurry of 60% to 95% water by weight;
B. adding to the slurry to a liquid lyophobic to the suspension liquid and the noncarbonaceous fine particles and lyophilic to the carbonaceous fine particles to form a mixture in which the liquid is less than 10% of the combined weight of the carbonaceous and noncarbonaceous fine particles, said liquid having an initial boiling point greater than about 149°F;
C. agitating the mixture to preferentially agglomerate carbonaceous fine particles into discrete carbonaceous agglomer-ates while said noncarbonaceous particles remain substantially unagglomerated in the mixture, said discrete agglomerates having a substantially uniform ash content of less than about 6.5% by weight, said agglomerates being substantially inert to atmospheric oxidation for a substantial period of time;
D. separating the discrete agglomerates from the mixture;
and E. heating the separated discrete agglomerates to at least 750 F to convert the agglomerates to a fluid product.

8. A fluid made from a solid carbonaceous material and prepared as set forth in Claim 7 wherein:
Step C includes agitating the mixture to preferentially agglomerate carbonaceous fine particles into discrete agglomerates that have a substantially uniform moisture content in the range of about 7% to 20% by weight; and Step E includes heating the separated discrete agglomer-ates to form a liquid product.

9. A fluid made from a solid carbonaceous material and prepared as set forth in Claim 7 wherein:
Step C includes agitating the mixture to preferentially agglomerate carbonaceous fine particles into discrete agglomerates that have a substantially uniform moisture content in the range of about 7% to 20% by weight, and Step E includes heating the separated discrete agglomer-ates to form a gaseous product.

10. A method of converting a solid carbonaceous material into a fluid comprising the steps of:
A. dispersing an amalgam of carbonaceous and noncarbona-ceous fine particles in a suspension liquid to form a slurry of 60 to 95% water by weight;
B. adding to the slurry a liquid that is lyophobic to the suspension liquid and the noncarbonaceous fine particles and lyophilic to the carbonaceous fine particles to form a mixture in which the liquid is less than 10% of the combined weight of the carbonaceous and noncarbonaceous fine particles, said liquid having an initial boiling point greater than about 149 F;
C. agitating the mixture to preferentially agglomerate carbonaceous fine particles into discrete carbonaceous agglomerates while said noncarbonaceous fine particles remain substantially unagglomerated in the mixture, said discrete agglomerates having a substantially uniform ash content of less than about 6.5% by weight, said agglomerates being substantially inert to atmospheric oxida-tion for a substantial period of time;
D. separating the discrete agglomerates from the mixture;
E. comminuting the separated discrete carbonaceous agglomerates to reduce the particle size of the discrete carbona-ceous agglomerates; and F. heating the separated discrete agglomerates to at least 750° F. to convert the agglomerates to a fluid product.

11. A method of converting a solid carbonaceous material to a fluid as set forth in Claim 10 wherein:
Step E includes comminuting the separated discrete car-bonaceous agglomerates in a wet or dry form.

12. A method of converting a solid carbonaceous material into a fluid as set forth in claim 10 wherein:
Step E includes comminuting the separated discrete car-bonaceous agglomerates to a particle size of no greater than about 70%-200 mesh.

13. A method of converting a solid carbonaceous material into a fluid as set forth in Claim 10 wherein:
Step C includes agitating the mixture to preferentially agglomerate carbonaceous fine particles into discrete agglomerates that have a substantially uniform moisture content in the range of about 7% to 20% by weight; and Step F includes heating the separated discrete agglom-erates to form a liquid product.

14. A method of converting a solid carbonaceous material into a fluid as set forth in Claim 10 wherein:
Step C includes agitating the mixture to preferentially agglomerate carbonaceous fine particles into discrete agglomerates that have a substantially uniform moisture content in the range of about 7% to 20% by weight; and Step F includes heating the separated discrete agglom-erates to form a gaseous product.