SE446459B - PROCEDURE FOR THE CONVERSION OF COAL OR POWDER TO GAS-OR OR EASY-COMPLETED COOLET BY REACTION WITH ALKALIMETAL SULPHIDS - Google Patents

Description

15 20 25 30 35 446 459 efforts are required to be able to meet the needs that are to be expected in the future in order to obtain alternative energy sources, food or chemical starting materials. One of the most readily available sources of hydrocarbon material is carbon. To date, no ready-made means have been produced to produce hydrocarbons from coal without extensive investments in capital and economically defensible bases. Although various processes are known for converting carbon at high temperatures, such as high temperature, i.e. above 60006, and high pressure, for example over 25 atmospheres carbon gasification, no readily available low temperature and low pressure processes have been available through which carbon can be easily converted to its constituent hydrocarbons.

PRIOR ART Regarding the state of the art for the present invention, reference may be made to the following U.S. Patents: 3,926,775, 3,933,475, 3,944,480, 3,960,513, 3,957,503, 4,018,572, 4,030,893, 4,057,422 and 4,078,917. .

DISCLOSURE OF THE INVENTION It has now been noted that when carbon and other carbonaceous materials, such as peat, containing at least 50 Z of carbon and in addition to carbon, oxygen as an essential element, are treated with a special reagent, the carbon can be converted in the presence of this reagent and in the presence of steam to various hydrocarbon fractions, primarily gaseous hydrocarbon fractions having 1 to 5 carbon atoms (C1 to CS), for example methane, ethane, ethylene, etc.

It has further been noted that when this conversion is carried out at varying temperatures, i.e. using steam and carbon at certain steps at elevated temperatures, the proportions between the different hydrocarbons obtained from the same carbon can be varied. At lower temperatures volatile liquid hydrocarbons are produced, while at higher temperatures gaseous hydrocarbons are primarily produced.

Furthermore, it has been noted that different carbon, such as lignites of different compositions and sub-bituminous carbon, i.e. lower grade carbon, show different distillation points, although the production of the liquid and gaseous hydrocarbons still takes place. Higher (high quality) 10 15 20 25 30 35 446 459 carbon yields more liquid hydrocarbon distillate than the lower grade carbon does, while other modifications affecting the process or reagent make it possible to obtain more liquid distillate.

In general, it can be assumed that when an alcoholic solution of KHS alone (or with sulfur) is added to the carbon, the following reaction takes place: KHS + S2 + 1/2 H25 + 1/2 KZSS. additive. However, sulfur strives to stabilize KHS to a lesser From the above it appears that RHS can be used without sulfur? hydrolyzed polysulfide. Some degradation of KHS to KZS takes place in the presence of water. This degradation is partial. When hydrating carbon, both KHS and KZS should therefore be present. When sulfur is added, a less hydrated and therefore more water-stable polysulfide is needed.

Although the above reaction has been shown for KHS, NaHS may also work, but appears to work better without the addition of elemental sulfur.

It is also possible to use KHS or NaHS in tort ie without the addition of alcohol. NaHS is available as an industrial bulk product, usually in the form of flakes with about 30% by weight of Z water in the bulk material.

When H25 and its various polysulfide forms react with carbon, it primarily attacks the oxygen, sulfur and nitrogen present in the carbon in bound form to expel these constituents in the carbon. When these components are formed in the presence of steam or water, the bond splitting of the various carbon constituents together with the removal of oxygen, nitrogen and sulfur makes it possible to introduce hydrogen and thus the formation of hydroaromatic, aromatic and aliphatic compounds with short chains.

It has been observed that oxygen must be present in the carbon. For this reason, low quality coals, such as lignites, are very suitable. As the quality of the carbon increases, as in sub-bituminous carbon, the amount of oxygen in these coals decreases and consequently also the possibility of gaseous conversion and / or at the same time more components in the liquid phase are produced. It has also been observed that even carbon in the form of sub-lignite, i.e. lower class lignite, and peat can be converted according to the present process into various hydrocarbon constituents. BRIEF DESCRIPTION OF THE DRAWINGS To illustrate the present invention, reference is made to the accompanying drawing figure which schematically shows the reaction chain for the column conversion and the recovery of the various constituents.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring to the figure, the reaction vessel II is usually a retort or similar apparatus into which the carbon is fed in finely ground form.

Usually the carbon has a particle size up to 6.35 mm (1/4 inch) for lignite but can be larger as the reaction is size independent. For sub-bituminous carbon, the particle size can also be up to 6.35 mm (1/4 inch), but is suitably about 0.8 m (1/32 inch). After the system has first been depleted of all oxygen by introducing inert gas such as hydrogen or nitrogen, etc., KZS or KHS (or equivalent reagent) is introduced into alcohol. The system is then closed and the temperature is raised to 65 ° C, at which temperature the alkanol is distilled from the reagent. While the inert gas, i.e. nitrogen or oxygen, takes care of the stirring, the expulsion of water continues continuously at the same time as the expulsion of the alkanol. The alkanol is usually methanol or ethanol, although higher alkanols may be used as alkanols having up to 4 carbon EIOHIGI.

Once the desired operating temperature has been reached (after the distillation of alkanol, when used in the process) and steam is introduced into the system at a suitable temperature, the inert gas, such as nitrogen, which was first used to purify the system of oxygen, is no longer needed. The steam vessel 12 is provided with means for heating water in the vessel, but additional heating can also be provided such as by heating the line from the steam generator 12 to the reaction vessel 11.

A suitable means for controlling or controlling the reaction in the reaction vessel may also be provided, such as heating or cooling coils, temperature measuring instruments, means for heat control, stirring devices, etc. The reaction vessel may also have external heating.

The reaction products from the reaction vessel are introduced into the condenser 13, which may be of the reflux type with the temperature of the inlet and outlet water 446,459 adjusted so that the heavy fraction which first comes over from the coal is condensed. The heavy fraction can condense on the walls of the condenser apparatus 13a and then sink downwards to be received in the lower collector 14, from which these liquid products can be removed, recovered and analyzed at regular intervals.

From the lower collector 14 the gaseous effluent is then sent to a second condenser 15 where the gaseous products are further cooled and introduced into the wet purifiers 16. In these wet purifiers or scrubbers 16 there are suitable washing liquids to collect the desired product fraction in each one of the washing liquids. When applying the procedure on an industrial scale, separation in a column apparatus can be more practical.

The undissolved but washed component is in turn introduced in its gaseous state into the next gas purifier or scrubber, from which additional components are separated (as will be explained in the following). Although seven washing stations have been shown, the number is determined by the number of gaseous fractions that are intended to be recovered. The number of washing sections can thus be increased or decreased. The final gas fraction is measured with the measuring device 17 and can be collected and treated, for example by further washing and purification, i.e. distillation, or used directly.

As will be readily appreciated, especially as the gaseous fraction from gasification of coal consists of a comparatively narrow fraction consisting mainly of gaseous fractions having from 1 to 6 carbon atoms or adjacent liquids thereof, fractionation can also be used to recover the various reaction products. Common fractionation means are, for example, column apparatus and molecular sieves. Separation and distillation means of this kind are generally known and need not be described in more detail here.

However, for understanding the present invention, there is shown an embodiment which allows separation of different fractions based on the solubility of hydrocarbons having from 1 to 6 carbon atoms. 10 15 20 25 30 35 446 459 The process can be performed continuously. The separation function of the various reactive substances (such as the alcohol-based reagent) can thus be carried out in such a way that the system can work continuously with continuous addition of reagents, carbon and steam and continuous removal of the product. Under these conditions, inert gas purification may become unnecessary. From each of the gas purifiers 16, the dissolved component can be separated by conventional means, and the liquid used in the apparatus is separated therefrom.

Regarding the solubilities specified here, this normally applies to the specified gas at normal room temperature, i.e. about 2200.

Since the gas washing can be performed at room temperature and at near atmospheric pressure, the solubilities are intended to apply to these conditions. It can be noted that even high pressures can be used, such as in a distillation chain, to avoid too low temperatures. Even in this case, when the pressure conditions change, the conditions which control the recovery at varying pressures are well known to those skilled in the distillation art.

Based on well-known solubility factors, which are available in general manuals, these can be listed for the hydrocarbons recovered from the system.

The solubility of C1 - C6 hydrocarbons is as follows: Ethylene is soluble in ether, readily soluble in alcohol, acetone and benzene and insoluble in water. Ethane is soluble in benzene, slightly soluble in alcohol and acetone and insoluble in water. Propane is soluble in water and alcohol, very soluble in ether and benzene and slightly soluble in acetone. It is also very soluble in chloroform. Propylene is very soluble in water, in alcohol and in acetic acid. Butane is very soluble in alcohol, ether and chloroform and is soluble in water. Butene (1- & 2-) is very soluble in alcohol and ether, is soluble in benzene and insoluble in water. The 1-, 2-, and transpents are miscible in alcohol, ether, acetone, benzene, chloroform and heptane and slightly soluble in water. Hexane is soluble in ether and chloroform and very soluble in alcohol and insoluble in water. Hexene (1-, 2-, trans. 3-) is soluble in alcohol, ether, benzene, chloroform and pet. ethers and insoluble in water. Methane is soluble in water, alcohol, ether, benzene, methanol and toluene and slightly soluble in acetone. The reagent, such as potassium hydrosulfide or sodium hydrosulfide or a polysulfide thereof, is regenerated, for example in one of the reaction vessels when the washing liquid therein is alkanolic KOH or NaOH to form either the actual sulfide or hydrosulfide depending on the amount of HS as reacts with the hydroxide. Normally in these conditions the reagent will be precipitated as a white precipitate, for example by the formula K2S (hydrate) or Na2S (hydrate). In ethanol or higher alcohols, the only slightly soluble alkali metal sulphide can be separated from the system by simply removing the precipitate from the scrubber.

The ash remaining in the reaction vessel 11 is removed therefrom in a suitable manner and worked up, for example by dissolving the soluble substances therein and extracting, for example, potassium therefrom according to the difference in solubility of calcium hydroxide and potassium hydroxide, i.e. extraction of potassium with calcium hydroxide. and potassium hydroxide is removed. Sodium hydroxide is present in the ash in smaller quantities and can be removed in the same or other manner well known in the art. As sodium is present in carbon at considerably lower levels than potassium, it may be necessary to increase the sodium content during the continuous process if a sodium-based reagent is used. Potassium is found in sufficient amounts in carbon. As can be seen from the above, at lower temperatures for lignite, as will be shown in the following example, the reaction gives a hydrocarbon fraction ranging in the C3 - C6 hydrocarbon range, with the fraction on average having C4 as the predominant.

This fraction is normally recovered up to about 120 ° C. At 22,000, methane is produced to the butane fraction, including double-bonded unsaturated equivalents. At 360 - 450 ° C, ethylene and possibly some hydrogen are normally produced. In order to ensure that no hydrogen sulphide is driven away, the product stream is subjected to wet washing in an alkali metal, for example potassium or sodium, hydroxide alkanol solution under saturated conditions. The hydrogen sulphide reacts with the hydroxide so that the reagent, ie K2S and Na2S, is regenerated and in the presence of water, KHS and NaHS regenerate. In the gas stream thus purified, hydrogen sulphide is present in a very small amount, for example less than 0.01 volume-Z. The above process as well as the present invention will now be explained with reference to some examples, which, however, are not intended to constitute a limitation of the invention but merely as an illustration of a pair of its embodiments.

HEEEELL 50 milliliters of a solution of potassium hydrosulfide in methanol containing 0.37 g of potassium hydrosulfide per / ml were used as the basic reagent. 71 g of lignite were used with a "dry ash-free" content of 66 Z carbon, 3.97 Z hydrogen, 18.2 Z oxygen and 0.9 Z nitrogen (weight-Z) as well as a small amount of volatile constituents. The crude lignite contained 33 Z of water and 9 Z of dry ash. (Wet analysis of "fresh" gave 6 Z ash). The organic sulfur content of this lignite was 0.69 Z, while the pyritic sulfur content was unknown.

The experiment was performed with lignite which had been dried for 2 hours at 135 ° C and with lignite which had not been dried. The main difference between the dry and wet lignite was a production of very light hydrocarbon gases from the wet lignite at temperatures below the boiling point of the water during the heating period. Water from the lignite provided the hydrogen for this production of hydrocarbon distillates. In other respects, the reaction was similar.

Elemental sulfur was added to the lignite. It can also be added to the alcoholic KHS solution. The total amount of sulfur present was 8.25 g, which also included the organic sulfur content of the lignite.

The device consisted of a container and a line for hydrogen or nitrogen which is inert flushed (see figure). These inert gases can be fed directly or fed through a steam generator via a steam line into the reaction vessel 11. The steam line is heated to 14,000 and enters the reaction vessel near the bottom of the vessel which is heated to this temperature.

Temperature measuring devices are also provided. Normally, the vapor line enters through the center opening of the bottle. Initially, nitrogen or hydrogen is responsible for the stirring while the methanol in the reagent solution is distilled. However, the agitation can also be effected by other means, such as, for example, by mechanical agitation. The presence of water in the crude lignite gives a methanol-446 459 (or ethanol) -soluble hydrocarbon gas during this distillation. .

The production of this liquid hydrocarbon is minimal when using dry lignite. The reaction vessel 11 may have any suitable shape, but in the present example a round bottom flask with suitable inlet openings at the top is used. There is another inlet opening for the addition (and disposal) of lignite. The reagent is introduced through a suitable opening which closes during operation.

A further opening leads to a vertical water-cooled condenser 13, which opens into a round condensation bottle 14 with an outlet opening provided for this purpose together with an opening in the bottom for diverting distillate.

Residual gases are led from the condensation bottle (vessel) 14 into a second water-cooled condenser 15, suitably above said condensation bottle 14.

The gases from the condensing bottle, ie residual gases, are then passed through a series of scrubbers or scrubbers 16. These scrubbers consist of at least the following: a) a water scrubber, b) an ethanol (methanol) scrubber, c) a 1 M solution of KOH in 135 ml of methanol, d) a benzene wash, e) a 1 M solution of KOH in 2 M of water, f) a sulfuric acid wash with about 24 Z solution of 98 Z-ig HZSO As backfire protection a 4. tom scrubs.

The remaining gases then pass through a line and are collected by suitable collecting means. A chromatographic tube can be placed in front of the gas sample meter 17 (located between the scrubbers and the collecting means) so that gas samples can be analyzed. A chromatographic tube can also be placed elsewhere where desired in the recovery chain where it is desired to have gases or distillates analyzed.

A gas meter arranged in this line, calibrated in parts of a cubic foot, or equivalent, gives the accumulated volume of recycled hydrocarbon gas. During the execution of the process, the lignite (together with the sulfur it contains) is placed in the reaction vessel and heated to 35-50 ° C. 50 ml of reagent is added after the system has been flushed with hydrogen or nitrogen to remove atmospheric oxygen. The system is closed and the temperature is raised to 65 ° C, at which temperature the methanol component of the reagent is distilled. As previously mentioned, the hydrogen or nitrogen introduced is capable of providing sufficient agitation in the reagent-lignite mixture. The reagent also contains water both as impurities in the ingredients used for the preparation of the reagent and as additional water which is formed when the reagent is formed.

The water contained in the reagent and carbon is distilled off at temperatures up to 135 ° C.

The distillate produced during the methanol (or ethanol) distillation will contain methanol- or ethanol-soluble hydrocarbon constituents containing gases. Water is distilled from the reaction mass, after most of the methanol has been removed, and is usually clear. This water may contain a small quantity of amber liquid hydrocarbons (which increase with the degree of carbon). At a temperature of 135-190 ° C, but usually at 135-190 ° C, a smaller fraction of liquid hydrocarbon is produced from the reaction mass. Even in this case, the amount increases with the carbon content. This liquid hydrocarbon is condensed in the water-cooled condenser 13 on the walls 13a of the condenser as a solid or semi-solid.

After the water-methanol mixture has been distilled from the reaction mass, the introduction of hydrogen or nitrogen may be stopped. At this point, i.e. at about 170 - 19000, only steam is used to stir the mixture, or a suitable stirrer can be used. Steam is not introduced into the reaction vessel until the methanol-water mixture has been distilled because the water-methanol mixture maintains the temperature at a specific temperature range during this distillation.

After the introduction of the steam, or of the steam plus continued introduction of hydrogen, different lignites and sub-bituminous carbons, due to their natural compositional properties, show different distillation points in the production of larger amounts of gaseous hydrocarbon. Preferably, the introduction of hydrogen is interrupted when steam is injected into the reaction vessel, since an accurate instrument reading of the quantity (volume) of gas emitted from the apparatus cannot be performed when hydrogen is introduced into the apparatus. However, suitable means, such as a second measuring device on the hydrogen tank, could give an indication of the amount of hydrogen passing into the system, which could be subtracted from the total reading on the final meter 17. It should be mentioned that some amount of hydrogen is used to hydrate the coal and that the amount of hydrogen cannot be measured by these means.

Normally, for low-carbon, a continuous production of hydrocarbon gases begins at the boiling point of methanol or ethanol and continues to increase while the reaction mass is heated to approximately 280 ° C. For higher carbon, only a small amount of gas production takes place at these low temperatures, ie up to around 280 ° C. These gases are mainly taken up in the scrubber system and a very small reading can be noted on the gas meter 17.

If the scrubber system is eliminated (and the initial hydrogen sulphide production from the reaction between the alkanolic reagent and the elemental and organic sulfur - the latter in the carbon - is vented separately or measured or wet washed with a suitable reagent in water) the gas quantity can be measured.

As previously mentioned, depending on the type of coal in each particular case, the initial gas quantity is low. From a certain lignite, for example, at temperatures below 28,000 about 0.7 - 1.4 1/50 g of gas are obtained from the wet coal.

Methane is normally released first and it has the greatest solubility in all the liquids in the scrubber system compared to each of the other recycled hydrocarbons. Pentane, hexane, hexene and pentene also have significant solubility in the scrubber fluids used in the system, except in water.

The hexene and hexane condense in the water-cooled condenser and are only gasified further by the action of the partial pressure of the other lighter gases passing over the liquid. A gas component which is recovered and which is led into the meter 17 is ethylene. Ethylene has limited solubility in kerosene and low solubility in water and alcohol in the various washing steps 16.

Ethylene has a characteristic odor of unsaturated hydrocarbon while the saturated hydrocarbon gases have no odor. The solubility of unsaturated hydrocarbon gases in sulfuric acid can be used to separate the saturated from the unsaturated hydrocarbons.

When the temperature reaches 33500, the first 100 g of wet lignite or sub-bituminous carbon give a faster gas production in the C1 - Cs carbon atom range.

Gas production increases considerably when one reaches 360 ° C, and when the final temperature is between 380 ° C and 45000, one can note a very fast gas production whereby also a certain amount of hydrogen is produced. At a temperature of 360 - 38000 carbonyl sulphide is also produced, and in sub-bituminous carbon, for example, 4.7% by weight of the total hydrocarbon gas may consist of carbonyl sulphide.

At higher temperatures, gases pass the water purifiers and are registered on the flow meter. For example, at the higher temperatures, one can obtain from 100 g of moist sub-bituminous carbon - after subtracting for the hydrogen sulfide - normally up to 0.04 cubic meters of gas from 47 g of the element carbon in the sub-bituminous carbon.

At normal temperature and pressure, about 3.7 moles of gas containing 47 g of the element carbon means an average carbon content of 2.25 for a product. Again, however, it should be noted that the products produced at different temperature levels consist of different decomposition fractions.

Gas chromatographic analysis in Experiment 1 gives a strong indication of two hydrogen atoms for each carbon atom in the gases. The starting lignite contained one hydrogen atom for every 1.38 carbon atoms, or, in a direct comparison, 0.725 hydrogen atoms for every carbon atom. Gas chromatographic analysis could not indicate any significant amount of oxygen present but showed that the gases collected consisted almost entirely of hydrocarbons. The hydrocarbons containing from 1 to 6 carbon atoms in this fraction consisted of either gases or very volatile liquids. Wet cleaners remove carbon dioxide such as potassium carbonate in the form of a precipitate in KOH-ethanol or the methanol solution. Normally a solution of one mole of KOH in two moles of water is used, whereby alcohol can be added to this aqueous solution of alkali metal hydroxide. 1 g of 25 g of commercial grade sodium hydrosulfide flakes were mixed with 100 g of sub-bituminous Maverick carbon. NaHS was of commercial grade in flake form and of varying analysis, in this particular case the sample containing about 30 Z of water. These flakes were placed on top of the carbon in the reaction vessel.

The carbon analysis was as follows: moisture 3.3 Z, ash 12.9 Z, sulfur 0.69 Z, carbon 70.2 Z, hydrogen 4.4 Z, nitrogen 1.13 Z and oxygen 6.16 Z (all weight-Z ).

The calorific value of the carbon was The mixture was heated to 28000 in a reaction vessel. Steam was injected (140 ° C steam) into the bottom of the reaction vessel to stir and to supply hydrogen for the hydrogenation of the carbon. Steam was injected as it reached a temperature of 17500. Probably the hydrosulfide was decomposed at least partially to sulfide during this heating due to the water content of the reagent and the carbon.

Below 175 ° C, a few clear drops of hydrocarbon were distilled with the initially evaporated water. The reagent bubbles up at 175 ° C apparently due to the formation of a lower hydrate of sodium sulfide with the subsequent release of water.

At 280 ° C, the emitted hydrocarbon gas was produced continuously and one was washed before being burned. At 350 ° C the experiment was stopped and about half of the carbon had reacted.

The liquid distillate, cooled and condensed in a water-cooled condenser, was 15 ml and gave an analysis of 9.8 Z hydrogen, 87 Z carbon, 0.67 Z 10 1.5 20 25 446 459 14 sulfur and 0.07 Z nitrogen. Chromatographic analysis showed that the gases were mainly ethylene. About 22.7 liters of gas were produced.

Without establishing any particular theory for the practical results of the invention, it can be assumed that oxygen, sulfur and nitrogen are removed from the carbon by a series of complex reactions, which are made possible by sulfur compounds of potassium or corresponding sulfur compounds of other alkali metals, as explained below. The reactions give via water and hydrogen sulphide molecules water which reacts with carbon at the point where carbon is freed from oxygen, sulfur or nitrogen. Thus, for the practice of the present invention, it is necessary for oxygen to be present in the carbon, but it is also advantageous that sulfur and nitrogen are present in the carbon in the form of organic sulfur or organic nitrogen forms. In addition, higher grade coal, such as bituminous coal, may not be so easily converted to gaseous hydrocarbons although, as will be explained below, this can still be done if the reaction scheme is appropriately modified.

It was noted that carbon with a carbon content below about 70 Z was almost completely gasified with at most 5 Z in the form of a solid and / or liquid distillate. A hard coal with about 75 Z carbon content gave 10 Z liquid distillate, the rest was gas. Coal with 82.3 7. carbon gave 33 Z of liquid distillate, while the rest was gas. An anthracite carbon with a 92 Z carbon content gave some gas and only about 2 l of liquid to solid distillate. When sodium is used instead of potassium, approximately the same amounts of liquid distillate are produced but less gas.

For these reasons, the present invention preferably relates to the gasification of lignite and sub-bituminous carbon. Furthermore, the invention is applicable for gasification of sub-lignite and peat and also wood which is a carbonaceous material with a carbon content in dry. conditions of about 50 Z carbon and about 40 7. oxygen is conceivable, but economic conditions do not make the process so advantageous in this case due to the lower carbon content of these raw materials per unit weight.

Although rubidium is equally active, potassium is the preferred hydrosulfide for practical reasons. Sodium is also useful as a sodium hydrosulfide, and polysulfides also cause the necessary reactions. Cesium, rubidium, potassium and sodium hydrosulphides and polysulphides can be used, but cesium and rubidium are not advantageous for cost reasons. Lithium can also be used but is not as effective as sodium.

A mixture of rubidium-; potassium and sodium sulphides (general), can be used with greater efficiency than any of the individual (general) sulphides. The term "general" refers to the series of sulfides beginning with hydrosulfides to polysulfides. The preferred ratio is 14 Z rubidium, 26 Z potassium and 60 Z sodium sulfides (general) based on the weight of the elemental metal. The weight ratios for the previous mixture are for the respective substances 1: 1.5 - 2.5: 3.5 - 4.5.

The amount of potassium hydrosulfide relative to coal is from 5 - 50 g / 100 g of coal, with about 10 - 25 g being what is normally used.

Preferably about 18 g of potassium hydrosulfide / 100 g of coal are used.

However, as will be explained in more detail, this reagent is regenerated.

If potassium in the cola ash is converted to hydrosulfide, there is no loss of potassium hydrosulfide and the reagent balance of the reaction becomes very advantageous in both batch and continuous processes.

It should be emphasized that in general sufficient amounts of sulfur, sulphide, hydrosulphide or polysulphide should be present to take up the sulfur evaporated from the coal by oxygen during the deoxidation to prevent the evaporated sulfur from dehydrating the coal at a temperature above 17500. The purity of the various reagent forms must also be maintained above 325 ° C, as a rise in temperature above this level results in a slow dehydration of the carbon by alkali metal hydroxide melting. Since sulfur causes the formation of polysulfides and the alkali polysulfide is less hydrolyzed with increasing sulfur content, the degradation by steam (or other water) of the hydrolysis product is prevented, i.e. the hydrosulfide is thereby protected.

The choice of required amount of reagent is thus comparatively determined for each type of carbon and can be easily determined for the type of carbon in question from the above wide ranges of the reactants and the amounts of sulfur present in the carbon.

When calculating sulfur in coal, only organic sulfur is taken into account, ie sulfur bound to carbon. Nitrogen in carbon is converted to ammonia, and in large-scale operation it can be recovered as a valuable by-product.

As shown above, steam is used at a temperature at which the reaction is sought to take place, i.e. depending on the type of carbon and the decomposition levels of the carbon, as well as on the desired product. Steam is also a source of hydrogen, apparently in the form of H + (apparently not from OH-). Appropriate steam generation can take place at the selected temperature in the generator 12 shown in the figure. In the appropriate amount, sufficient steam is produced to give, for example, hydrogen for the hydrogenation of hard coal to a final product in the form of hydrocarbon having from 1 to 2 carbon atoms. If less hydration is desired, less steam is used.

As the sulfur content of the reagent is increased, i.e. sulfur in the carbon and added elemental sulfur, the reaction temperature is lowered. A reaction temperature of 380 ° C is lowered, for example, to 30 ° C, where, as an illustrative example, the sulfur balance represents a theoretical compound K 2 S 3 produced and maintained under the reaction conditions. A natural consequence of this phenomenon is that larger molecules are formed, for example isopentane and pentane.

Furthermore, the carbon quality affects the composition of the distillate, to the extent that the higher the carbon quality, the greater the proportion of liquid distillate under equivalent conditions, i.e. when using the theoretical K2S3 compound at the same temperature conditions.

As mentioned before, of course, the product composition changes as the temperature varies. Furthermore, the product composition also changes, as illustrated above, as the amount of sulfur in the reagent changes.

Due to the above, one can thus change the temperature, the sulfur content, the carbon quality and use recycling of alcohol-absorbed distillates (as will be explained in more detail below) in order to obtain the desired product fraction. Within the variation of a product fraction, recirculation of various other distillates in the recycling chain shown in Fig. 1 is conceivable.

The variations described above are within the following limits: temperature up to 42500 while the distillation starts at 40 - SOOC; the sulfur content of the reagent (for example for potassium) KZS but the sulfur content can go up to KZSS; the carbon quality should be within the lignite ~ to bituminous coal range.

When using anthracite, the results are less advantageous although a distillate can be obtained at 38,000 when using a reagent such as KZS4.

For sodium, useful sulfur forms are NaHS and Na2S to the Na2S2 sulphides, where NaHS is more stable than KHS with respect to water in carbon or steam and begins to react and produce a distillate at correspondingly lower temperatures (about 10 - 20 ° C lower) than potassium hydrosulfide, albeit in slightly smaller amounts. Rubidium, although not beneficial from a cost point of view, is at least as good and often even better than potassium.

If the alcohol distillate (including any existing hydrocarbon components) as shown in the figure is recycled from the separator 14 to the reaction vessel 11, the product composition may also be varied.

Furthermore, the recycled amount can also be varied. Thus, up to about 280 ° C, the product composition can be forced against a composition consisting of a liquid distillate having a boiling point of about 18006.

At a reaction temperature up to about 30 ° C, kerosene distillate is formed using said recirculation of alcohol to the reaction vessel.

As before, water, for example steam at a temperature of about 135 ° C or higher, must also be present in this recirculation for the reaction to take place.

For alcohol recycling, methanol is the preferred alkanol.

As can be seen from this aspect of the recirculation, the alcoholic distillate allows for further product modification by using the alcohol-soluble initial reaction products in the reaction vessel. As a result of this aspect, more liquid distillates can be obtained. 10 15 '20 25 30 35 446 459 18 When starting the process at about room temperature (and raising the temperature), elemental sulfur is added to the coal or to the reagent to give the selected sulfur content of the reagent. Under these conditions, the H S formed in the system during the reaction of the sulfur and reagent is removed from the gas stream and the washing system so that the reagent is formed again. When the temperature is raised, steam is not used, with any occurring hydrogenation of carbon relating to the water content of the carbon or reagent. At about 13 ° C, steam can be added if light distillates are desired. Preferably, however, steam is added at about the temperature at which a hydrate of the reagent begins to reshape or regenerate into a lower hydrate thereof. For potassium-based reagent, the steam addition temperature is selected to be about 170 ° C.

While the initial hydrate is converted to lower hydrate and releases hydration water, enormous amounts of steam are released. This is the signal that the point at which steam can be safely introduced has been reached, provided that the hydration water has left the reaction vessel.

The process can also be performed continuously. Normally a special temperature level is selected and introduced into the carbon and the reagent in the reaction zone, whereby the ash has been removed, the reagent and the alkali metal part of the reagent have been recovered therefrom and the reagent regenerated, for example with hydrogen sulphide. The liquid and gaseous fractions are preferably collected in a distillation column or suitable gas purifiers comprising the hydrogen sulphide. Consequently, a completely continuous process with reagent regeneration is possible based on the descriptions made here for the production of a desired product fraction for the selected temperature and other process conditions.

In outlining the complex steps through which the reactions are considered to take place, one must remember that one reaches the presented view by drawing conclusions, but that many reactions take place at the same time. The following explanation should thus only serve as an aid to understanding the invention and does not adhere to any particular theory, since the invention per se can be understood and practiced without reference to any theory. 10 15 20 25 30 35 446 459 19 If it was the case that K 2 SO 4 reacts with oxygen in a carbon at elevated temperatures in a closed system free of atmospheric oxygen to directly form K 2 SO 4 by exchanging all equivalent sulfur in the pentasulfide ion for oxygen , the reaction would stop when KZSOS has been converted to KZSO4. KZSOA would thus be inert in the system unless it was converted to carbon monoxide and KZS by reduction with carbon in the carbon. If this were indeed to happen, there would be danger in the reaction of the potassium sulphides with the carbon monoxide to form potassium carbonyl; a highly explosive compound. According to the present process, however, it is quite clear that the analyzed gases in the chromatography lines do not contain a significant amount of carbon monoxide or carbon dioxide.

It is also known that sulfur in elemental form dehydrates carbon at temperatures above 175 ° C (Mazumdar et al., Fuel, Volume 41, page 121 et seq., 1962).

Furthermore, air oxidation of potassium pentasulfide gives elemental sulfur, potassium thiosulfate (K2S203) and potassium tetrationate (K2S¿06). (Letoffe et al., Journal of Physical Chemistry, Vol. 71, pp. 427-430, 1974). Potassium pentasulfide decomposes to potassium tetrasulfide and sulfur at 300 ° C. This reaction is a slow reaction that gradually increases as the temperature rises above 30,000.

Potassium sulfide will contain 5 molecules of hydration water up to 150 ° C when it becomes dihydrate, and the dihydrate decomposes at 270 ° C to a solid lower hydrate and water and an even lower hydrate to 779-84000 at which temperature potassium sulfide decomposes to disulfide and elemental potassium. Elemental potassium is soluble in the solid sulphide.

The thiosulfua (xzszoß) decomposes above 20 ° C: Sum + pentasulfide, and the pentasulfide in turn decomposes to tetrasulfide and sulfur starting at a temperature of 30,000.

When potassium hydrosulfide (in alkanol) is used as reagent, the water content of the carbon and the water contained in the potassium hydrosulfide solution reacts to obtain hydrolysis and then decomposition to hydrogen sulfide and potassium hydroxide. Potassium hydroxide reacts with non-degraded potassium hydrosulfide to form potassium sulfide (in hydrogenated form) and water. Potassium pentasulfide (formed by reaction with organic sulfur in the carbon and added elemental sulfur) forms potassium hydrosulfide as follows: KHS + 2 S = 1/2 KZS + 1/2 H25. For sodium, the reaction is: NaHS + 1 l / 2 S = 1/2 Na 2 S 4 + 1/2 H 23.

No sulfur-containing polysulfides in the form of transition compounds (defined as sulfides having 2 to 5 sulfur atoms) are formed in the reaction with potassium and insufficient sulfur leaves unreacted KHS. However, this reaction occurs only in alcoholic solutions. In the case of sodium forms, only the tetrasulfide forms are formed.

Potassium sulphides with a sulfur content less than those of pentasulphide are broken down by oxygen to potassium.

In summary, the following happens. While oxygen as well as nitrogen and organic sulfur are removed, water or hydrogen sulphide (which is continuously produced by contact between water and the reagents) emits hydrogen to the carbon at the point where the carbon has been freed from oxygen, sulfur or nitrogen; nitrogen is released mainly as ammonia; and the sulfur is released to form an alkali (e.g. potassium) polysulfide, and at lower temperatures a mercaptan is formed with the alkanol solvent.

Mercaptans are absorbed in alcohol and in the KOH alcohol solution.

KOH in the methanol wash for the effluent gas stream gives the alkanol-insoluble thiosulfate. This overall reaction proceeds by reducing the hydrogen sulfide gas to sulfur and water, with subsequent reaction of the sulfur with KOH to form the potassium sulfate and potassium sulfide as shown above. The potassium sulfide can then obtain additional sulfur from the hydrogen sulfide to form potassium polysulfide which are the reagents used in the reaction. In general, the decomposition products of the carbon element have different compositions at different temperature levels. These 446 459 Zl temperature levels can be selected according to the desired composition of the volatile distillates and gaseous fractions which may be suitable for a particular end use. For example, at a temperature between 340 ° C and 36506, the following gas analysis was obtained for a gas product obtained from a sub-bituminous coal: methane 80.19 Z, ethane 9.12 Z, ethylene 1.41 Z, propane 2.67 Z, propylene 1 , 41 Z, isobutane 0.16 Z, n-butane 0.31 Z, hydrogen sulphide 0.001 Z and carbonyl sulphide 4.72 Z, and the remainder consisted of unidentified gaseous components.

Through the above it has been shown that an easily accessible source of hydrocarbon can be obtained from carbon by a process carried out at low temperature and low pressure during regeneration of the reagent as part of the process.

Claims (27)

10 15 20 25 30 35 446 459 22 PATENT CLAIMS Process for the conversion of carbon or peat to gaseous hydrocarbons and volatile distillates, characterized in that said carbon or peat is reacted with a hydrosulphide or sulphide of an alkali metal or with mixtures thereof in the presence of water to such an extent in a temperature between 50 ° C and 400 ° C mainly at atmospheric pressure that a hydrogenated end product with one or two carbon atoms is formed, and that volatile liquid distillates and gaseous hydrocarbons are recovered. Process according to claim 1, characterized in that said carbonaceous product is reacted with an alkanol solution of an alkali metal hydrosulfide, a sulfide, a polysulfide or mixtures or hydrates thereof. 3. A process according to claim 2, characterized in that elemental sulfur is added to said alkanol solution of said alkali metal hydrosulfide. 4. A process according to claim 2, characterized in that said alkali metal hydrosulfide is potassium hydrosulfide. 5. A process according to claim 2, characterized in that said alkali metal hydrosulfide is sodium hydrosulfide. 6. A process according to claim 2, characterized in that said alkali metal hydrosulfide is a mixture of rubidium, potassium and sodium hydrosulfides and sulfides. Process according to any one of claims 2-6, characterized in that carbon or peat containing oxygen, sulfur or nitrogen in bound form is reacted with said alkali metal hydrosulfide or polysulfide or mixtures thereof or of various alkali metals or hydrates thereof as reagent, the reaction is carried out at a temperature between 135 ° C and 450 ° C in the presence of steam with substantially atmospheric pressure without hydrogen being added to the reaction, and the reagent is regenerated. 10 15 20 25 30 35 446 459 23 8. A process according to claim 7, characterized in that the carbon 'consists of lignite carbon. 9. A process according to claim 7, characterized in that the carbon is sub-lignite, i.e. lower class carbon. 10. A method according to claim 7, characterized in that the carbon consists of bituminous or sub-bituminous coal, i.e. lower grade coal. 11. A method according to claim 7, characterized in that peat is reacted. 12.; Process according to Claim 7, characterized in that the alkali metal consists of potassium. 13. A process according to claim 7, characterized in that the hydrosulphide or polysulphide consists of an alkali metal mixture of rubidium, potassium and sodium. 14. A process according to claim 7, characterized in that the alkali metal is sodium. 15. A process according to claim 7, characterized in that a part of the distillate is recycled as an alcohol solution to participate in the reaction between carbon or peat and said reagent. Process according to any one of claims 1-15, characterized in that the reaction is carried out at a temperature between 170 ° C and 450 ° C, preferably between 170 ° C and 380 ° C. Process according to any one of claims 1-16, characterized in that said carbon or peat is steam-treated at a temperature above 100 ° C to expel air from the material, that the steam-treated material is continuously introduced into a reaction zone maintained at said reaction temperature. between 50 ° C and 450 ° C, that said reagent is fed to the reaction zone together with water or steam in such an amount that the hydrogenated final product with one or two carbon atoms is formed by reaction between the coal or the peat and the reagent at substantially atmospheric pressure, that in addition to volatile distillates and / or gaseous products, hydrogen sulfide or carbonyl sulfide and carbon or peat ash are also recovered from the reaction zone and unreacted reagent and alkali metal products, such as alkali metal hydroxide, from the carbon or peat ash. react alkali metal hydroxides with hydrogen sulfide released during the reaction to thereby regenerate the reagent, and Add a sufficient amount of the regenerated reagent to the reaction zone to continue the reaction between carbon or peat and the reagent. 18. A process according to claim 17, characterized in that the reaction zone is kept at a certain, predetermined temperature for the production of gaseous hydrocarbons. 19. A process according to claim 17, characterized in that the reaction zone is maintained at a temperature suitable for recovering a predetermined hydrocarbon fraction. Process according to claim 17, characterized in that an alcoholic solution containing a part of said dissolved distillate is recycled to the reaction zone. 21. A process according to claim 17, characterized in that industrial sodium hydrosulfide is used as reagent. 22. A process according to claim 17, characterized in that the reagents are regenerated by reacting an alkali metal hydroxide in a saturated alcohol solution with hydrogen sulphide and precipitating the reagent as a mixture of a sulphide and hydrosulphide of said alkali metal hydrosulphide. 23. A process according to claim 17, characterized in that the gaseous hydrocarbon is washed in an alkali metal hydroxide solution so that the hydrogen sulfide is removed from said gaseous hydrocarbon as a reaction product with said alkali metal. 24. A process according to claim 17, characterized in that said gaseous hydrocarbon products are distilled to recover a desired product fraction. Process according to Claim 17, characterized in that a theoretical composition of K 2 S 3 based on material balance is used as reagent. 26. A process according to claim 17, characterized in that anthracitic coal is partially reacted with the reagent. Process according to any one of claims 1-26, characterized in that the process is carried out in the presence of sulfur.