DE2429089A1 - PROCESS FOR PRODUCING LOW ASH SOLID AND LIQUID HYDROCARBON FUELS - Google Patents

Description

Process for the production of low-ash solids and liquids

Hydrocarbon fuels

For this application the priority will be from March 4, 1974 U.S. Patent Application Serial No. 446 974 used.

The invention "relates to a using a liquid solvent Dissolution process carried out for the production of low-ash solid hydrocarbon fuels and liquid Hydrocarbon distillate fuels from raw coal containing ash. Preferred starting carbon contains hydrogen, such as ■ bituminous and subMtuminous coal and lignite. In which A low-ash solid fuel (dissolved coal) is used together with as much liquid as possible from coal Fuel produced with an increase in the production of liquid fuel from a decrease in the production is accompanied by solid fuel. Liquid fuel is the more valuable product; the generation of liquid However, fuel is limited because it involves the by-production of undesirable gaseous hydrocarbons Goes hand in hand. Although liquid fuel is of greater economic value than low ash solid fuel, gaseous hydrocarbons have an even lower level Value as low-ash solid fuel or liquid fuel

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substance and have a higher ratio of hydrogen to carbon than solid or liquid fuel, so that their production means a waste not only of other fuel products but also of hydrogen.

Gaseous hydrocarbons arise primarily through hydrogenative cleavage, and there their formation during this Process is undesirable and catalysts in coal solvation processes generally have hydrogen cleavage activity, no particularly added one Catalyst used.

If raw coal is subjected to solvation at a relatively low temperature, the dissolved product will exist predominantly of high molecular weight fuel that is solid at room temperature. When the mixture of solvent and dissolved charcoal is then filtered to remove the ash and undissolved charcoal, and. the filtrate from vacuum distillation is subjected, the product is a high-boiling solid fuel, which is the vacuum bottom residue is won. This low-ash vacuum soil residue is here either as vacuum soil residue or as low-ash solid fuel or low ash solid fuel product. This vacuum soil residue is on a Conveyor belt cooled to room temperature and removed from the conveyor belt as lumpy, low-ash, hydrocarbonaceous solid fuel scraped off.

As the temperature of the solvation process is progressively increased, the vacuum bottom residue becomes (the low ash solid fuel) which is a high molecular weight polymer in liquid hydrocarbon fuel of lower molecular weight chemically similar to and similar to the process solvent Has boiling range. The liquid fuel product becomes the Partly recirculated as process solvent for the next run and here either as a liquid fuel product or referred to as excess solvent. The production of the liquid fuel is based on the Depolymerization of solid fuel by way of

509838/0583

various reactions such as splitting off of heteroatoms including Sulfur and oxygen. As a result of the depolymerization reactions, the liquid fuel has a slightly higher level Ratio of hydrogen to carbon and therefore a correspondingly higher heat of combustion than solid Fuel. One endeavors in the process as much as possible from the vacuum bottom residue (the solid fuel) in the product of the solvent boiling range (liquid fuel) convert because liquid fuel is economical is more valuable than solid fuel. If the temperature of solvation continues to rise, an even larger part becomes of the vacuum bottom residue is converted to solvent boiling fuel until a temperature is reached at the conversion of the vacuum soil residue into liquid fuel as a result of excessive thermal hydrogenating cleavage only at the expense of an excessive and uneconomical one Side production of hydrogen-rich gaseous hydrocarbons takes place. The present method creates 20 or 40 to 80 weight percent low-ash solid fuel on an anhydrous and ash-free basis, while the remainder of the product consists primarily of liquid fuel.

The invention is based on the object of thermal hydrogenative cleavage as far as possible, and at least to do so to avoid to such an extent that excessive production of gaseous hydrocarbons is avoided, since the formation of gases reduces the yield of the desired low-ash solid fuel product and the liquid fuel off product decreased. This object is achieved according to the invention solved by carrying out the solvation process in two separate stages and preferably in each stage working at a different temperature. According to one embodiment of the invention, less than 6 percent by weight are gaseous Hydrocarbons, based on the anhydrous and ash-free starting coal, are generated. The generation limit for gaseous hydrocarbons determines the generation limit for liquid product and therefore also the generation limit for the solid fuel product.

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^ £ 29089

An important advantage of the "at two different temperatures implemented method according to the invention is that a high temperature stage is made possible, thus making it possible reduce the sulfur content of the product. I ¹ Ur the sulfur removal namely relatively high temperatures are required, whereas temperatures below the required level Although the high temperatures required for effective sulfur removal also lead to hydrogenative cleavage, the hydrogenative cleavage reaction is more time-dependent and, therefore, by rapidly reducing the high process temperatures, one can reduce the sulfur content below minimal hydrogenation Achieve division.

The first reactor stage of the process according to the invention is a tubular preheater in which the slurry from coal and solvent essentially in plug flow in a relatively short residence time gradually heated up as it flows through the pipe will. The tubular preheater generally has a length to diameter ratio of at least 100 and preferably at least 1000. To the extent that the temperature a given mass of the feed from the inlet temperature to the maximum or outlet temperature that it holds is only exposed for a short time increases, various reactions take place in the material flowing through the pipe. The second If the residence time is longer, the reactor stage is carried out in a larger vessel that runs from the inlet to the outlet on an im substantially uniform temperature is maintained. A controlled one preferably takes place between the two stages Forced cooling so that the temperature in the second stage is lower than the highest temperature in the preheater. While the preheater stage is carried out with plug flow without significant backmixing takes place in the dissolver stage complete mixing of the solution takes place at a constant reactor temperature. The data given below show that a coal solution process operating at two different temperatures leads to a high degree of conversion

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of raw coal into low ash solid fuel and liquid Fuel leads and the ratio of liquid to solid fuel product is increased, while an excessive lift production of gaseous hydrocarbons is avoided. It is shown below that these results are better with a process operating at two different temperatures than with a process operating in both Stages with a uniform temperature works even if the uniform temperature is the same as one of the two temperatures used in the different temperature process.

The carbon solvent for the process according to the invention contains liquid hydroaromatic compounds. For feeding to the first stage or preheater stage, the coal is slurried in the solvent. In the first stage, hydrogen ύοϊι the hydroaromatic solvent is transferred to the hydrocarbons of the coal, whereby the coal swells and the hydrocarbon polymers are split off from the coal minerals. The range of maximum temperatures that are suitable for the first stage (preheater stage) is generally 400 to 525 ° C: and preferably 425 to 500 0. If the available systems cannot handle larger amounts of gaseous hydrocarbons occurring as by-products, should the upper temperature can be limited to 470 ° C or less in order to reduce the formation of gaseous products. The residence time in the preheater stage is generally from 0.01 to 0.25 hours or preferably from 0.01 to 0.15 hours.

In the second stage (the dissolving stage) of the process according to the invention, the solvents are used Compounds that released hydrogen to the charcoal in the first stage and thus to the corresponding aromatics converted back into hydroaromatic hydrocarbons by reaction with gaseous hydrogen, which can be returned to the first stage in the cycle. The temperature in the dissolution stage is im generally 350 to 475 ° C and preferably 400 to 450 ° C.

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2429083

The residence time in the dissolving stage "is generally 0.1" to 3.0 hours and preferably 0.15 "to 1.0 hours. The temperature in the dissolving stage is advantageously lower than the maximum temperature in the Yor heating stage. About the temperature the process flow between the heater and the dissolver any suitable type of forced cooling "can be used. For example, between the preheater and add make-up hydrogen to the dissolver or make use of a heat exchanger. The residence time in the preheater is lower than that in the solver.

The liquid space flow rate for the process (parts of slurry per hour per part of reactor space) is 0.2 to 8.0, preferably 0.5 "to 3.0. The hydrogen to slurry ratio is generally in the range 3.6 to 180 and preferably in the range of 9 to 90 groove / " ¹⁰⁰ 1 · ^The weight ratio of recycled solvent product to coal in the feed slurry is generally in the range of 0.5: 1 to 5: 1, and preferably in the range of 1.0: 1 to 2.5: 1.

In both stages the reactions take place in contact with gaseous hydrogen, and in both stages are sulfur and oxygen heteroatoms are removed from the solvated, low-ash carbon polymer, which leads to depolymerization and conversion of the polymers of the dissolved coal into desulphurized and deoxygenated free radicals of less Molecular weight leads. These free radicals tend to be at the high levels achieved in the preheater stage Re-polymerize temperatures; remain at the lower temperatures in the dissolution stage according to the invention these free radicals, however, resist re-polymerisation by absorbing hydrogen. In the process according to the invention, carbon monoxide and water vapor can be used together with or instead of hydrogen, because these react with one another to form hydrogen. The water vapor can by supplying wet Coal can be produced or injected in the form of water. The reaction of hydrogen with the free radicals takes place

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2429083

at the lower temperature in the looser than at that higher temperature at the outlet of the heater.

The solvent used at start-up is preferably derived aμs coal. Its composition varies depending on the the properties of the coal from which it is extracted. Generally the solvent will be highly aromatic Liquid recovered from prior processing of fuel and generally in the area boils from about 150 to 450 ° C. Other general characteristics of the solvent are a density of about 1.1 and a carbon to hydrogen molar ratio in the range from about 1.0: 0.9 to about 1.0: 0.3. You can start with anything use any organic solvent for charcoal. A particularly advantageous start-up solvent is Anthracene oil or creosote oil with a boiling range of about 220 to 400 ° 0. The start-up solvent only takes a few moments part of the process, since the process results in dissolved fractions of the raw coal, the additional solvent form which, when added to the start-up solvent results in a total amount of solvent in excess of the amount of start-up solvent. Hence that loses original solvent gradually changes its initial composition and its composition approaches that of the solvent, which dissolves and depolymerizes which forms coal in the process. Therefore, every time the process is run after start-up, the solvent can be considered a part of the liquid product formed during a previous extraction of the raw coal.

For the dissolving process, the residence time in the preheater stage is more critical in the method according to the invention Meaning. Although the duration of the solvation process varies may vary according to the coal being treated, forming viscosity changes that the slurry undergoes while it is being used through the heater tube, a parameter which determines the residence time of the slurry in the preheater stage. The viscosity of a certain mass of the feed solution flowing through the preheater initially increases with

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increasing residence time in the preheater, then decreases again with increasing residence time when the solubilization the slurry progresses. The viscosity would increase again at the pre-hit temperature, that However, residence of the slurry in the preheater is terminated before there is a relatively large increase in the viscosity comes. An advantageous means of getting the right time to complete the preheater stage is the relative viscosity of the solution forming in the preheater, below which the ratio of the viscosity the resulting solution to the viscosity of the solvent fed to the process, both determined at 99 G to understand is. The relative viscosity is thus that at 99 ° C certain viscosity of a certain amount of solution divided by the viscosity of the dem, which is also determined at 99 ° C Process supplied solvent on its own:

Relative viscosity = viscosity of the solution at 99 ° C

Viscosity of the solvent at 99 ° C

The relative viscosity can be used as a measure of the residence time of the solution in the preheater. To the extent that how the solubility of a certain amount of the slurry progresses as it passes through the preheater, the relative viscosity of the solution initially increases to over 20 · up to a point at which the solution is extremely viscous and is in a gel-like state. When you're dealing with low solvent to charcoal ratios of, for example, 0.5: 1 works, the slurry even solidifies to form a gel. After the well over 20 When the maximum relative viscosity is reached, the relative viscosity of the relevant amount of material begins at a Minimum decrease, and it then has a tendency to rise again to a higher value if given the opportunity in addition there. The solubilization process continues until the relative viscosity (after its initial increase) drops to a value at least below 10, whereupon the residence time in the preheater ends and the solution is cooled and in

509838/0583

The dissolving stage is directed where it is at a lower temperature is held so that the relative viscosity does not rise above 10 again, normally one leaves the relative Viscosity even down to a value of less than 5 and preferably drop to a value of 1.5 to 2. In the preheater such conditions prevail that the relative viscosity would rise again to a value above 10, if not the effect of the conditions prevailing at the outlet of the preheater would suddenly end, e.g. by forced cooling.

If a given mass of hydroaromatic solvent and coal is first heated in the preheater, it is the first reaction product is a gel that forms in the temperature range from 200 to 300 ° C. This gelation is for responsible for the first increase in relative viscosity. The gel is formed by combining the hydroaromatic Compounds of the solvent with the hydrocarbons of the coal, which results from the swelling of the coal. at this bond there is likely to be a joint participation of the hydroaromatic hydrogen atoms in the Solvent and the coal as an early stage in the transfer of hydrogen from the solvent to the coal. the The bond is so strong that the solvent cannot be distilled off from the charcoal in the gel state. With further Heating the mass in question in the preheater to 350 ° C decomposes the gel, resulting in completion the hydrogen transfer results, and it arise low ash solid fuel, liquid fuel and gaseous products, and the relative viscosity decreases.

A decrease in the relative viscosity in the preheater is also caused by the depolymerization of the solvated Carbon polymer causes free radicals. This depolymerization is based on the elimination of sulfur and Oxygen heteroatoms from the hydrocarbon polymers of coal and on the separation of carbon-carbon bonds as a result of hydrogenative cleavage with the conversion of low-ash solid fuel into liquid fuel

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substance and gases. The depolymerization is from the development of hydrogen sulfide, water, carbon dioxide, methane, Accompanied by propane, butane and other hydrocarbons.

At the high temperatures at the outlet of the preheater zone, the repolymerization of the free radicals proceeds preferentially before the hydrogenation of the free radicals, and this is the ultimate endeavor of the mixture, im Preheater to assume a relative viscosity of more than 10 again. According to the invention, this second increase in relative viscosity prevented. The removal of sulfur and oxygen from the solvated low ash solid fuel is probably based on the fact that these substances are driven off by thermal cleavage of bonds, whereby Molecular fragments are left behind in the form of free radicals tend to polymerize again at the high temperatures. The termination of the prevailing in the preheater Conditions, e.g. through forced cooling behind the Yor heater stage, counteract the formation of polymer. Of the observed low sulfur content of the liquid fuel product, which is about 0.3 weight percent for a coal grade is while the sulfur content of the vacuum bottom residue (the solid fuel product) is 0.7 percent by weight, suggests that the sulfur is driven off the solid fuel product, with smaller molecular fragments of low sulfur content are left behind as free radicals.

It was found that the maximum temperature or outlet temperature of the preheater should be in the range of 4-00 to 525 ° C. To achieve this maximum temperature is the residence time of a given amount of the feed in the preheater is about 0.01 to 0.25 hours. With this coordination Depending on the temperature and residence time, coke formation is not a problem if the flow is not brought to a standstill , i.e. if the dwell time is not extended beyond the specified duration. Under these conditions is the yield of gaseous hydrocarbons is less than 6 percent by weight, while the yield of excess solvent (liquid fuel) is over 10 or 15 weight percent

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percent, based on the water- and ash-free coal charge, and the solid fuel yield is in excess of 20 weight percent. A strong gas generation should be avoided, because it leads to high hydrogen consumption, and because special facilities are required to accommodate or transport the gases. A gas yield of more than 6 percent by weight can be accepted, however, if facilities for the storage or extraction of gas are available. ■ The relatively low sulfur content of the vacuum soil residue (of the low-ash solid fuel product) of the process according to the invention is an indication that that the reaction is largely complete. It is also an indication that the vacuum soil residue has separated itself chemically from the ash so that it can be filtered off from it. ·

The hydrogen pressure in the process according to the invention is generally 35 to 300 kg / cm ² and preferably 50 to 200 kg / cm 2. At about 70 kg / cm ² hydrogen pressure, the hydrogen content of the solvent is usually about 6.1 percent by weight. If the hydrogen content of the "solvent is above this value, there will be a transfer of hydroaromatic hydrogen to the dissolved fuel, thereby increasing the formation of liquid fuel, which has a higher hydrogen content than the solid fuel. If the solvent is less than Contains 6.1 percent by weight hydrogen, it tends to take up hydrogen from the gaseous hydrogen at a faster rate than the fuel product, and once the solvent has roughly settled to a stable hydrogen content, the conversion apparently depends on the catalytic action of the coal ash Some deviations from this normal behavior occur as a function of temperature and time. Higher temperatures lower the content of hydroaromatic hydrocarbons, while high feed rates can prevent equilibrium values from being reached (because then ni there is not enough time). Furthermore,

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higher pressures mean that equilibrium is reached more quickly and an enhancement of the hydroaromatic character of the system.

In the dissolution stage of the process according to the invention, aromatic compounds react which have their hydrogen in the Preheaters have given off with hydrogen with regression of hydroaromatic compounds. Hydroaromatic compounds are partially (not completely) saturated aromatics. The chemical potential in the solvent is so low that the complete saturation of the aromatics does not take place to any significant extent. This is essential because only hydroaromatic Compounds, but not saturated aromatic compounds, can transfer hydrogen. Most saturated Hydrocarbons found in the dissolver are light products that are formed by ring opening of liquid products or formed by solvents or formed by the cleavage of aliphatic side chains. The aromatic one Part of the solid fuel product remains aromatic or hydroaromatic.

The joint effect of time and temperature in the preheater stage is in the process according to the invention important. The desired temperature effect in the preheater stage is essentially a short-term effect during the desired temperature effect in the dissolver a longer residence time requires. The desired short residence time in the preheater is achieved by using an elongated one Reaction tube with a high ratio of length to diameter (generally at least 100 and preferably at least 1000), so that the current is quickly discharged from the preheater after the desired maximum temperature has been reached and the action of the elevated temperature is terminated by forced cooling. Forced cooling can be done by direct cooling with hydrogen or by heat exchange. In the dissolution level, in which the temperature is lower, is the residence time is longer than in the preheater.

When the product of the process of the invention for the solvent refining of coal is distilled, are

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normally gaseous substances expelled overhead. Furthermore, a fraction of the middle settlement area is obtained, which is normally Liquid, carbon-containing fuel and (when starting up) solvent supplied from outside the process contains. In addition, a high-boiling material that is solid at room temperature is obtained. The remaining ashes of the coal can be obtained from the product by filtration, centrifugation or solvent extraction prior to distillation will.

The middle-boiling fraction that occurs in vacuum distillation and is liquid at room temperature, is normally at least partially used as a solvent for slurrying guided by coal particles in a cycle. Although the vacuum soil residue, which is solid at room temperature, is used as a solvent is inferior to the normally liquid fraction of the middle boiling point, which is obtained from vacuum distillation, it has been found that the ash it contains is a beneficial part of the cycle. Apparently favored The iron contained in the ashes split the extracted heavy coal molecules, making an extracted one Lower average molecular weight fuel is produced. Therefore, if you have an ash-containing product stream in the Circulation leads, the relative yield of the fraction middle boiling point is increased, while the relative yield of Vacuum residue is reduced, using as a basis of comparison A process is used in which the middle boiling point fraction without ash is used as a solvent for the process in the cycle to be led. Another advantage of using an ash-containing circulating stream is that the subsequently The vacuum soil residue produced has a significantly lower sulfur content.

Another benefit of using a recycle stream containing ash is the increase in activity for the Hydrogenation of the solvent to replace the hydrogen, which the solvent acts as a hydrogen donor has lost. In order for the hydrogen to react with the coal feed, a solvent extraction of the coal from the

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Ash take place and a depletion of sulfur and oxygen heteroatoms can be made from the extracted coal is a transfer of hydrogen from the partially hydrogenated aromatic solvent molecules required. The gaseous one Hydrogen reacts indirectly with the coal and the carbonaceous fuel extracted from the coal by he first chemically interacts with the aromatic solvent molecules connects. An increased rate of binding of the hydrogen with the aromatic solvent molecules in turn, increases the speed at which the gaseous hydrogen reaches the coal. The initial one The hydrogenation activity of the externally supplied start-up solvent is not important if there is enough Allow time to pass for the process by recycling the ash-containing process solvent reached a steady state. With continued circulation of the ash-containing process solvent into the feed stream the ash content of the feed slurry gradually increases to an equilibrium value, and as soon as this is reached, the technical port step achieved by the invention becomes noticeable.

The method according to the invention makes use of a preheater, a solvent and a vacuum distillation tower which are connected in series. A slurry of crushed coal and recycled solvent is passed through the preheater. The preheater has a much lower fit than the dissolver, so the dwell time in the preheater is much shorter than that in the dissolver. From the outside, neither the preheater nor the dissolving stage is added to the catalyst; the preheater stage and the dissolving stage are the only two reactor stages of the process according to the invention. The effluent from the solver is filtered and then subjected to vacuum distillation. Gases are withdrawn overhead from the distillation column, fuel product liquid at room temperature is withdrawn in the middle of the column, and fuel product solid at room temperature is withdrawn from the

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The bottom of the column withdrawn. According to the invention there is an advantageous modification of the process in that one can rely on selective retention of the mineral ash residue im solver while using the fuel product preferentially lets exit from the solver "

In the preheater the relative temperature is higher than in the dissolver, while the residence time in the preheater is shorter in the preheater the hydrogen transfer from the solvent in the circuit to the freshly supplied coal without promoting excessive coking and polymerization. It has now been found that the minerals in the ash product, like iron in the form of ferrous sulfide (FeS), the transfer of hydrogen from the partially hydrogenated solvent generated in the dissolver to the supplied coal in the preheater catalyze. As already mentioned, the solvent does not contain saturated aromatic compounds, but hydroaromatic ones Compounds are created because these act as hydrogen donors, while saturated compounds are not hydrogen donors and their formation should therefore be avoided. Therefore, the intended goal would be through use a very effective catalyst, use of very high pressure or use of excessively long reaction times in the The dissolution process can be thwarted if this results in a high concentration of saturated compounds instead of hydroaromatic compounds Connections arise. In general, one works in the dissolver at a lower temperature than in the preheater and with longer dwell times, which are achieved by the fact that the dissolver is a larger vessel than the preheater «

It is advantageous if there is a substantial temperature difference between the preheater and the dissolver in order to to increase the hydroaromatic activity in the process. In general, the benefits of a wide temperature differential are increased when the amount of coal minerals is considered Enlarged in the procedure if you are in the solver at a relatively high hydrogen partial pressure and im Preheater works at a relatively lower hydrogen partial pressure, if you are in the loser at as possible

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low temperatures and at the same time longer dwell times works to compensate for the low temperatures to create, and if one has the good in the solver a sufficient There is a dwell time so that an equilibrium can be established at which the hydrogen transfer activity of the the circulating solvent coming to the dissolver is considerably higher than the hydrogen activity of the one used for start-up, externally supplied solvent.

The accumulation of minerals in the process not only increases the chemical driving force for hydrogen transfer in the preheater, but also favors the uptake of additional hydrogen by the solvent next pass through the solver. Increased this way the accumulation of coal minerals the degree of conversion in the process. The invention aims at the restraint of Coal minerals in the dissolution stage, without it being necessary to accomplish this through circulation.

The maximum temperature used in the preheater can (and which occurs as a result of the plug flow prevailing there at the outlet of the preheater) depends on the hydrogen donating activity of the solvent. The relatively low temperatures compared to those in the solver going to the preheater to use, favor the re-hydrogenation of the solvent and the generation of depolymerized carbon-derived products in the dissolver. The maximum concentration of minerals that can be allowed in a mineral-containing circulating stream depends on both on the pump delivery as well as the piltrability of the circulating flow because part of the circulating flow must be withdrawn and filtered once the appropriate process equilibrium is reached. According to the invention the problem of pump delivery of the circulating flow is eliminated because the concentration of the minerals according to the invention independent of a recycling of minerals is increased.

Table I and Pig. 1 of the drawings show that the hydroaromatic activity of the solvent with the iron

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content of the feed. Different types of coal give values that in this respect are on a smooth curve lie. As Fig. 1 shows, the hydrogen content of the increases Solvent with increasing mineral content. The values of the

Table I are determined at a hydrogen pressure of 70 kg / cm and shown graphically in FIG.

Table I.

Dissolving temperature,
⁰ C Iron in the
Loading of the
Preheater,
Wt .-? 6 Hydroaromatic
Hydrogen activity 425 0.18 0.20 425 0.72 0.45 425 1.33 0.60 425 1.87 0.75 425 2.34 0.86 425 2.67 0.97 400 0.72 (0.51) 450 1.33 0.39 450 1.33 0.31 450 1.33 0.34

The values of Table I shown in Fig. 2 show that at a temperature in the dissolver of 450 ° 0 and a given iron content of the feed, the solvent is less hydroaromatic activity is given as at a temperature in the dissolver of 425 ° 0, from which it follows that at each Given iron content in the feed, a low temperature in the dissolver leads to an increase in hydroaromatic activity leads in the process. It is desirable to have as high as the hydroaromatic activity in the solvent possible because a high hydroaromatic activity enables a higher temperature to be used in the preheater, without the coke and polymer formation cause difficulties. Since the. increased hydroaromatic activity if you operate the solver at relatively low temperatures and longer dwell times, it is essential

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lent that the dissolving vessel in relation to the preheating is big. The use of different temperatures in the Yor heater and in the dissolver, combined with the increased mineral concentration As a result of the build-up of ash in the solvent, both the reaction in the gate heater and the Reaction in the loser takes place under the respectively preferred conditions. The different types of responses in the Yoreheater and going on in the dissolver are further favored by going into the dissolver at a higher hydrogen pressure works as in Yor heater.

In the process according to the invention, oxygen is more easily withdrawn from the fuel product obtained from the coal as sulfur, while nitrogen in the molecular structures is most firmly bound. Therefore, if you consider the circulation of the material extracted from the coal, it is found that the nitrogen concentration in the stream increases, while the sulfur concentration remains constant and the oxygen content decreases. Because high temperatures for sulfur removal are most favorable, the higher the temperature in the preheater, the lower the sulfur content in the product applies.

The first stage in dissolving the coal is the transfer of hydrogen in the preheater. When this transfer does not take place sufficiently, the solution degenerates through repolymerization and finally through coking. Many Lignite types contain only moderate amounts of iron, see above that in these cases the reactivity with hydrogen in the solvent may not be satisfactory. If such coal types but having a high sodium content can use carbon monoxide and water vapor for the purpose of generating hydrogen on the spot may be more advantageous than supplying it of hydrogen as such, because sodium catalyzes the water gas reaction. The rehydration of the solvent in the dissolver can be done by using hydrogen together with iron (II) sulfide originating from the coal as a catalyst used, or by using carbon monoxide and water vapor together with sodium or ferrous sulfide as a catalyst used.

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For the purposes of the invention, ash is selectively retained in the dissolving stage in batches or continuously, while liquid product is selectively allowed to flow off. The amount of the retained in the dissolution stage ash leads to the formation of an ash concentration in the dissolver to that ash concentration is equivalent to the solver that would be obtained when generally 10 to 80 or preferably 10 to 50 i <> the ash contained in the coal feed in Would lead to a cycle. By retaining the ash in the dissolver in the sense of the invention, one achieves the same advantage as with the ash circuit, but avoids the high pump conveying costs that would be required to convey the amount of ash-containing sludge that is required to produce a similar ash concentration in the dissolving vessel .

Table II shows the results of experiments performed by the process operating at different temperatures have been carried out, and explains the effect of the ash concentration when using a preheater stage and a downstream dissolution stage.

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cn ο co co co

ro

Attempt no.

Ash cycle Hr, pressure, kg / cm

Preheater temperature,

Solvent temperature, ⁰ C

Reciprocal liquid-space flow velocity, H

Hourly headspace flow rate

Solvent / coal * / ¹ ^ ⁰ ash in feed slurry, wt .- $ coal in feed,

Tabel 1 II CVJ 3 4th 5 no
.70 there
70 Yes
70 there
70 there
70 450
425 450
425 450
425 450
425 475
425

1.79

1.89

1.72

1.79

1.79

342
2.49 / 1 / 0.05 2.49 / 1 / 0.05

342 342 2.49 / 1 / 0.05 2.49 / 1/00 2.49 / 1/00

Yields, based on coal feed *

CO CO ₂

H ₂ S

Gaseous hydrocarbons Unidentified gases H ₂ O

Excess solvent

(liquid product) vacuum soil residue

(solid product) Insoluble organic matter

A total of 5,285
34.8

0.51
0.64

2.04
5.73

3.82
31.98

48.66
11.59

104.97 * on a water- and ash-free basis.

7.42
48.7

0.27
0.68

1.62
5.80

1.22
62.08

30.36

4.99
107.02

9.25 60.7

0.37 0.62

1.87

5.97

6.50

-0.12

48.26

36.44

4.23

104.23

10.08 66.1

0.52

1.29

4.65 9.30 1.68

53.75 30.36

5.04 106.59

10.65 69.9

0.28

0.28

1.95 '

7.1-5

12.87

1.81

49.37 21.06

9j0] _

103.20

t-o ro

CD CD CO CO

Table II (continued)

cn ο co OO CO CXJ

O Ol OP

Attempt no.

data

Extraction, G ew. -Fo Degree of conversion *, Weight-fo

Composition of the liquid fuel product

Carbon, wt. -Fo Hydrogen, wt. -Fo nitrogen, wt. -F> Sulfur, wt. -Fo oxygen, wt. -Fo

Composition of the vacuum "ground return"

Carbon, wt .- $ Hydrogen, wt. -F o nitrogen wt .- $> Sulfur, wt. -F> oxygen, ash weight?

1. 2 3 4th 5 95.91
88.41 92.63.
95.01 92.73
95.77 96.48
94.96 93.35
90.93 89.40
5.93
1.06
0.410
5.00 89.72
6.20
1.15
0.420
2.51 91.40
6.70
1.21
0.358
0.76 90.98
6.59 '
1.33
0.338
0.76 90.65
6.54
1.31
0.438
1.062 88, 54
4.74
2.22
0.676
3,619
0.205 88.71
5.35
2.10
0.606
3.156
0.078. 91.12
5.10
2.22
0.488
1.00
0.075

* on a water- and ash-free basis.

Attempt. No. 1 of Table II is made with a solvent carried out, which does not contain any circulated ash. In tests No. 2, 3, 4 and 5 of Table II, the solvent contains circulated ash. When trying No. 1 is the percentage of ash in the feed slurry from the coal fed in, while in experiments No. 2, 3, 4 and 5 the percentage ash content in the feed slurry increases steadily due to the progressively longer duration of the recycle. That through Process explained in Table II finally leads to the formation of an equilibrium in which the ash content is in adjust the slurry feed to a constant value; in the experiments reported in Table II however, this equilibrium has not yet been reached.

The yield values in Table II show that the solvent assumes an increasing hydrogenation activity with increasing ash content of the feed slurry, which is already evident from the small increase in the production of gaseous hydrocarbons, but above all from the large increase in the production of liquid product and the simultaneous sharp decline in the production of solid fuel product (vacuum soil residue) results. The liquid product has the solvent boiling range and has a slightly higher hydrogen to carbon weight ratio and heat of combustion (greater than 9450 cal / g) than the solid fuel product (the vacuum bottom residue) which has a slightly lower hydrogen to carbon weight ratio and a has slightly lower heat of combustion (more than 8800 cal / g). Although the recycling of the ash results in a somewhat higher hydrogen consumption (2.5 to 3 tfo) , this hydrogen is used profitably because it leads to an increased yield of fuel with a higher heat content.

Table II also shows that as the proportion of ash in the feed slurry increases, the percentage conversion on a water- and ash-free basis also increases. The decrease in the degree of conversion to water and

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ashless basis in experiment no. 5 is based on the "" in In this attempt the preheating temperature is too high and the dwell time in the preheater is too long. To this decline in To avoid the degree of conversion, the preheating temperature should be below 475 ° C., preferably below 470 ° or 465 ° C. and in particular should not be higher than 460 or 450 C, or the dwell time in the preheater should, if you are at higher temperatures works, be shortened.

. Table II also shows that the hydrogen content of the liquid product with increasing ash content in the feed increases. As already stated, an increasing hydrogen content in the liquid product means an increased heat of combustion. In addition, the data show that the higher the ash content of the feed, the higher the oxygen content of the piltrate product decreases, but a lower oxygen content in the fuel produced is in turn synonymous with a higher heat of combustion.

A very important feature, also evident from Table II, is the decrease in the sulfur content of both the liquid product as well as vacuum bottom residue as the ash content of the feed slurry increases. A decrease in the sulfur content of the vacuum soil residue, which is solid, low-ash coal at room temperature "Especially this solid, low-ash coal has a higher economic value.

From Table II it can be seen that the greatest advantage is obtained from the recycling of heavy vacuum soil residue containing ash achieved by keeping the temperature in the preheater under control. As Table II shows, increases at a preheater temperature of 450 ° C, the production of gaseous hydrocarbons with increasing water content of the feed slurry while at a preheater temperature increases from 475 ° 0. However, increasing the production of gaseous hydrocarbons is uneconomical, as it comes at the expense of the desired liquid fuel product. A yield of gaseous hydrocarbons on a water- and ash-free basis of 6

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2 ^ 29089 IM

weight percent is a suitable upper limit for grass production, if facilities for the storage and conveyance of gases are not available. Also the yield of liquid Product (excess solvent) drops sharply when the preheater temperature is increased from 450 to 475.degree will. Likewise, the degree of conversion on a water- and ash-free basis also decreases if the Yoreheater temperature of 450 is increased to 475 ° C.

Table III further explains the interdependence of the recycle feature of ash-containing vacuum soil residue and the feature that the preheater works at a higher temperature than the dissolver. at in experiments nos. 1, 2 and 3 of Table III no ash is circulated, while in experiments 4 and 5 of the ash cycle is used. Table III shows that the slurry charge in Experiments Hr. 4th and 5- has progressively higher ash contents, which results from the progressively longer duration of the cycle.

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509838/0583

CO OO CO OS

Attempt Kr.

Ash cycle ρ Hp pressure, kg / cm

Preheater temperature, ⁰ C

Solvent temperature, ⁰ C

Reciprocal fluid-space velocity, H

Gas space hourly flow rate

Solvent / coal * / HpO ash in the feed suspension, G- ew. - $ coal in the feed,

Yields, "based on coal feed *

Excess solvent

(liquid product) vacuum soil residue

(solid product) Insoluble organic matter

All in all

Tabel 1 III 3 4th 5 no
70 2 no
70 There
70 there
70 450
450 no
70 450
425 450
425 475
425 500
450

0.52

0.98

1.79

1.89

304

239

342

342

2.50 / 1 / 0.08 2.49 / 1 / 0.06 2.49 / 1 / 0.05 2.49 / 1 / 0.05

5.0
33.3

5.36
68.12

• 14.91
100.94

5.0
33.3

15.10
56.81

13.83
102.47

5.285
34.8

31.98
48.66

11.59

104.97

7.42 48.7

62.08 30.36

4.99 107.92

342 2.49 / 1/00

9.07 103.20

* on a water- and ash-free basis.

CJD O OO CD

Table III (continued)
Experiment no. '12

data

Recovery, wt. ~? S degree of conversion *, wt

Composition of the liquid fuel product

Carbon, wt. -Fo

.. Hydrogen, wt -f o Q is nitrogen, weight ~ $ to Sulfur, wt -f o oo oxygen by weight -.. $>

oo ι Composition of the vacuum "^ rv> soil residue ο cn

cn, carbon, wt. fo co hydrogen, wt. fo ^w nitrogen, wt. fo

Sulfur, wt. -F>

Oxygen, wt. -Fo

Ash, weight- fo

* on a water- and ash-free basis.

97.94 96.59 95.91 92.63 93.35 85.09 86.17 88.41 95.01 90.93 89.68 89.40 89.72 90.65 5.94 - 5.93 6.20 6.54 0.979 _ 1.06 1.15 1.31 0.46 - 0.410 0.420 0.438 4.13 5.00 2.51 1.062 87.32 89.03 88.54 88.71 91.12 5.11 5.12 4.74 5.35 5.10 1.91 2.02 2.22 2.10 2.22 0.944 0.719 0.676 0.606 0.488 4.58 3.04. 3,619 3.156 1.00 0.133 0.067 0.205 0.078 0.075

ND CX) CD OO CD

Trial Rr. 2 of Table III shows that "when used different working temperatures in the heater and in the loose a higher yield of liquid product (excess Solvent) and a higher degree of conversion achieved on a water- and ash-free basis and a lower one Sulfur content of the vacuum soil residue is obtained as in experiment no. 1, with the preheater and dissolver in the operated at the same temperature. Furthermore, experiment no. 3 shows that even without circulating solvent even greater advantages can be achieved if you work at different temperatures in the preheater and in the dissolver, the temperature in the preheater but does not reach 500 C. leaves. Experiments 4 and 5 show that when working with the ash cycle, the use of different temperatures in the Preheater and in the solvent for even better results with regard to the yield of excess solvent, the degree of conversion on anhydrous and ash-free basis' and the sulfur content of the vacuum soil pressure level leads that, however the improvement in terms of the yield of excess solvent and the degree of conversion to anhydrous and ash-free Base drops sharply when the temperature in the preheater gets too high, even if you have ash-containing vacuum floor residue leads in a cycle.

As the experiments in Table III show, the best results are obtained by recycling the ash in combination with the use of different temperatures in the preheater and in the dissolver.

Table IV shows the results of tests that investigated the influence of the ash cycle on the hydrogen content of the liquid product (of the excess solvent). Table IV is a porting of the data of the Test No. 1 to 5 of Table II and shows that the hydrogen content of the solvent continuously on the hydrogen content of the originally used for start-up Solvent also increases as the percentage of iron in the feed to the preheater as a result of constant Circulation of ash-containing vacuum soil residue

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α «

takes. From Table IV it can be seen that the iron in the Asohemineral as a hydrogenation catalyst for the solvent works. The faster the intermediate reaction between hydrogen and solvent takes place, the faster it takes place also the overall reaction between gaseous hydrogen and coal, because the gaseous hydrogen interacts with the coal indirectly on the way via the hydrogen donor activity between the partially hydrogenated aromatic solvent and the charcoal reacts.

Table IV Increase in ^ H over <f> H
in the original
Solvent addition Table II,
Attempt no. Pe in preheater
loading, fo 0.33 1 1.33 0.46 2 1.87 0.57 3 2.34 0.57 4th 2.54 0.60 5 2.69

Pig. Figure 1 is a graph of the values in Table IV. The original solvent used in the experiments Table IV and FIG. 1 indicate a hydrogen content of 6.04 percent by weight. Same as Table IV and Pig. 1 shows there is a steady increase in the hydrogen content of the liquid product, corresponding to the increase in the iron content of the feed slurry.

Table II and Pig. 2 show that the hydrogenation of the aromatic solvent in the solvent is improved, if you operate the dissolver at a lower temperature than the preheater, because this increases the accumulation of high Concentrations of hydroaromatic compounds in the product of the solver for the circulation is favored. The preheater advantageously operates at a higher temperature than the dissolver for more efficient hydrogen transfer to achieve the hydrogenated aromatic hydrocarbons on the coal in the next pass. High temperatures in

- 28 509838/0583

- pre-heater favor the depolymerization and the reactions, through which sulfur and oxygen are withdrawn from the property. A high concentration of transferable hydrogen Promotes the formation of liquid products and prevents coking. The maximum temperature allowed for the heater depends on the activity of the hydrogen available for transfer in the solvent. Massive Temperatures in the solvent favor the hydrogenation of both the Solvent as well as the depolymerized coal. Furthermore, it is generally beneficial to reduce the accumulation of the catalytically active ash minerals to the highest concentration that can still be managed, with the performance indicators the exhaust pump and the filter are the limiting factors. According to the invention, pump delivery costs saved because the concentration of ash minerals is increased without having to go through an ash cycle Makes use, or by making only partial use of an ash cycle system.

In Fig. 3 the method according to the invention is schematically shown. Powdered coal is fed to the process through line 10 and with that through line 14 im Recirculated solvent made into a slurry which is in contact with circulating hydrogen from line 40 comes. The slurry flows through line 16 to Preheater tube 18 whose length to diameter ratio is at least 100 to achieve plug flow. The preheater tube 18 is located in an oven 20 so that the temperature of a plug in the preheater of the feed slurry from a low inlet temperature to a maximum temperature at the outlet of the preheater increases.

The high temperature slurry exiting the preheater then passes through line 22 where it passes through The addition of cold make-up hydrogen via line 12 is cooled before it reaches the dissolver 24. The dwell time in the solver 24 'is much longer than that in the preheater 18 because the solver's length to diameter ratio

: - 29 -

509838/0583

is significantly less than that of the preheater 18, causing it to backmix and stop plug flow comes. The slurry is in the dissolver 24 ″ essentially at a uniform temperature while its temperature in the Yorheater 18 changes from the inlet to the Outlet of the same rises.

The data of Mg. 2 show that the process is greatly improved if one considers the concentration of coal minerals increased in the release zone. The concentration of coal minerals in the dissolving zone can be increased by increasing the solids cycle enlarge; however, this creates costs and difficulties in pumping this solid slurry. If one makes use of a cyclone separator 60, which is located at the head of the dissolving vessel 24, can you separate part of the pesticide runoff from the clear liquid product and retain it immediately in the dissolving vessel. This way you can remove the pesticide buildup in the dissolver take advantage of the mineral or ash concentration in general to increase to 2 to 20 weight percent, or preferably 5 to 15 weight percent, without the cost of any having to accept unnecessary pump funding. In addition, the cyclone separator 60 allows modification and control the mineral concentration in the dissolver 24 by having the ash-containing drain from the dissolver partially or completely bypasses the cyclone 60 through the bypass line 82.

Mineral residue as well as extracted liquid and solid fuel pass from the dissolver 24 into the one circular one Cross-section having the frustoconical interior of the Cyclone separator 60 through a tangential opening 62 in the lower part of its side wall. The slurry entering here is swirled up the cyclone and low ash fuel is removed from the top of the Cyclones are withdrawn through line 64 while pests return through line 66 via control valve 68 to dissolver 24. A portion of the low-ash fuel can optionally be circulated as a solvent through line 86 via valve 88 subtracted from. If necessary, part of the

- 30 509838/0583

From the solver 24 run the cyclone 60 through the bypass line and bypass valve 84. In this way, the extent to which pesticides are retained in Loser 24 can be control by actuating valves 68 and 84.

Solids or clear liquid flow out of the dissolver 24 via the lines 64 and 82 through line 26 to the output chamber 74. From the output chamber 74, non-converted Hydrogen and gaseous hydrocarbons withdrawn overhead through line 76 to distillation column 28. The ashy one Soil residue arrives from the stripping chamber 74 through line 78 to the filter 80. The filter 80 becomes the ash withdrawn through line 85, while the filtrate flows through line 83 to the distillation column 28.

A distillate is withdrawn from the distillation column 28 through line 42 in the middle and as a liquid process product won. Since the process creates so much liquid that part of it is considered liquid Take off fuel product and part other than solvent for the next pass in the cycle, some of the liquid product is passed through line 44 and line 14 out in the circuit, where you can optionally also feed fuel through line 86 to the pulverized Bringing charcoal into solution in the next pass.

The gases including the circulated hydrogen are passed from the distillation column 28 overhead Line 30 withdrawn and removed from the process either through line 32 or through line 34 and scrubber 36 passed to remove impurities from them, which are removed through line 38, and a purified hydrogen stream to produce, which is circulated for the next pass through line 4: 0.

The vacuum bottom residue is discharged from the distillation column .28 through line 46 onto a conveyor belt 54, where it is cooled to room temperature and solidifies. The solid, essentially ash-free fuel is removed from the conveyor belt scraped off by a device indicated at 56. As can be seen from Fig. 3, between the preheater and the dissolver

-31 50983 8/0583

no material removed from the process; Everything good that enters the preheater is done both by the preheater as well as passed through the dissolver before any product separation is carried out.

- 32 -

509838/0583

Claims (18)

Claims 1. Process for the production of low ash solid and liquid hydrocarbon fuels from ash-containing, hydrocarbonaceous coal, characterized in that one contacts the coal with hydrogen and a solvent for the hydrocarbons of the coal to one with hydrogen Standing slurry of coal and solvent mixes the slurry along with hydrogen inside a residence time of 0.01 "to 0.25 hours through a preheater conducts whose length to diameter ratio is at least 100, so that back-mixing is prevented and a given amount of the slurry will gradually rise from a low inlet temperature as it passes through the preheater heated to the maximum temperature of 400 to 525 ° 0 prevailing at the outlet of the preheater and the viscosity the relevant amount of the slurry initially to at least 20 times the viscosity of the solvent, both determined at 99 ° C, then rises to less than 10 times during the further passage through the preheater the viscosity of the solvent, both determined at 99 ° C> drops and finally back to more than 10 times that The viscosity of the solvent, both determined at 99 ° 0 », would increase, but that of the slurry and the hydrogen withdraws from the preheater before the viscosity of the slurry becomes 10 times the viscosity of the solvent reaches the slurry to a dissolver in which a temperature is below the outlet temperature of the preheater between 350 and 475 ° C is held, the slurry with a longer residence time than that in the Preheater passes through the dissolver, some of the coal - 33 5 0 9838/0583 withdrawn ash in the solvent selectively with respect to the fuel flow through which looser holds back, drains drain from looser and split it into a gaseous fraction, a fraction that is liquid at room temperature and a fraction that is solid at room temperature, The low-ash fraction is broken down and the pulp contained in the gaseous fraction is recycled to the Yor heater and at least part of the liquid and / or the solid fraction as a solvent in the Yorheater stage returns. 2. The method according to claim 1, characterized in that one increases the through the selective AseheZerückung Brings about hydrogen content of the solvent. 3. The method according to claim 1 or 2, characterized in that an ash concentration of 2 to 20 percent by weight in the dissolver is generated by the selective ash retention. 4. The method according to claim 1 or 2, characterized in that an ash concentration is obtained by the selective ash retention from 5 to 15 percent by weight produced in the solvent. 5. The method according to claim 1 to 4, characterized in that the solids retention is accomplished in the dissolver, by directing the drain from the dissolver at least partially through a cyclone separator. 6. The method according to claim 1 to 5> characterized in that that a maximum temperature of 425 to 500 ° G is maintained in the preheater. 7. The method according to claim 1 to 6, characterized in that that ma] works. that you work in the solver at a temperature of 400 to 450 C - 34 - 509838/0583 8. The method according to claim 1 to 7, characterized in that the material between the preheater and the dissolver one Subject to forced cooling by at least 20 C. 9. The method according to claim 1 "to 8, characterized in that that a preheater with a length to diameter ratio of at least 1000 is used. 10. The method according to claim 1 Ms 9, characterized in that that one works in the preheater "with a residence time of 0.01 Ms 0.15 h. 11. The method according to claim 1 Ms 10 ¹ , characterized in that one works in the dissolver with a residence time of 0.1 Ms 3 h. · 12. The method according to claim 1 to 11, characterized in that together with the hydrogen or instead of the hydrogen Uses carbon monoxide and water vapor. 13. The method according to claim 1 to 12, characterized in that that the process with a yield of low-ash solid fuel of 20 to 80 percent by weight, based on the water and ashless coal charging. H. The method according to claim 1 to 13, characterized in that one works under such conditions that the viscosity the slurry in the preheater to a maximum of 5 times the viscosity of the solvent, both determined by 99 ° C, drops. 15. The method according to claim 1 to 13, characterized in that one works under such conditions that the viscosity the slurry in the preheater to a maximum of 2 times the viscosity of the solvent, both determined by 99 ° C, drops. τ 35 - 50 9838/0583 16. Procedure after. Claim 1 Ms 15, characterized in that that you can force cooling between the preheater and the solver by bubbling hydrogen into the slurry between the heater and the dissolver. 17. The method according to claim 1 Ms 15, characterized in that the forced cooling between the preheater and the Dissolver is carried out by placing the slurry in a heat exchanger located between the preheater and the dissolver cools. 18. The method according to claim 1 Ms 17, characterized in that that a mineral concentration is maintained in the solver that is equivalent to the mineral concentration achieved by Circulation of 10 to 80 percent by weight of the coal ash would be achieved. 19o method according to claim 1 to 18, characterized in that that the process is based on a production of gaseous hydrocarbons of less than 6 percent by weight on the water- and ash-free coal charging. - 36 - 509838/0583 ■ η Blank page