EP0123161B1 - Process for the hydrogenation of coal - Google Patents

Abstract

1. Process for the hydrogenation of coal, in which finely ground coal is pasted with pasting oil which consists of hydrocarbon mixtures extraneous to the process and, for the remainder, of oil originating from the process, and is hydrogenated at pressures of 100 to 700 bar, preferably 250 to 350 bar, and temperatures of 350 to 520 degrees C, preferably 440 to 490 degrees C, with hydrogen, optionally in the presence of catalysts, in a bottom phase, the products which are liquid and solid at these pressures and temperatures are separated off, and gaseous product, if appropriate after intermediate condensation, is further hydrogenated without pressure release in a gas phase over fixed catalysts and liquid product is isolated by fractional condensation, characterized in that the pasting oil consists to the extent of 30 to 100% by weight, preferably 50-95% by weight, of hydrocarbon mixtures, extraneous to the process, from the group of petroleum-derived top residue and/or vacuum residue, heavy oil or very heavy oil or oil from low temperature carbonization of oil shale and/or tar sand, having a boiling range such that boiling commences above 200 degrees C and preferably above 300 degrees C, with the remainder consisting of oil originating from the process and having a boiling range such that boiling commences above 200 degrees C, preferably above 300 degrees C.

Description

Document DE-A-2 715 625 describes a process for the hydrogenation of coal with solvent and hydrogen at elevated temperatures and pressures in the presence of a catalyst in order to obtain a liquid product. Gases and solids are separated from the liquids. The liquid product is then distilled. Aromatic hydrocarbon mixtures are used as solvents that are foreign to the process, such as. B. anthracene oil. It is also possible to use process oil, but it is not clear what percentage of the process oil is used as grating oil or whether the products boil above 200 ° C.

Document DE-B-2 040 764 describes a process for liquefying coal, in which coal is pulverized with a naphthenic aromatic solvent under pressure and at high temperature.

The document DE-A-3 209143 describes a process for the multi-stage hydrogenation of coal, in which finely ground coal is rubbed with only oils of process origin and preferably at pressures of 100 to 400 bar, preferably 250 to 350 bar and temperatures of 400 to 520 ° C 440 to 490 ° C, optionally hydrogenated with hydrogen in a bottom phase in the presence of catalysts, from the gaseous hydrogenation product after separation of the phase containing solids at the reaction temperature using the pressure given by the bottom phase by means of fractional condensation by heat exchange with feed products the hydrogenation stages at least 3 liquid phases are obtained, of which at least one is further hydrogenated in a gas phase in the presence of catalysts using the pressure given by the bottom phase. The fractions used for the gas phase hydrogenation should have a boiling range from 180 to 450 ° C., preferably from 200 to 350 ° C., while the fractions of the bottom phase product boiling at temperatures of more than 250 ° C., preferably more than 350 ° C., at least partly after relaxation be recycled as rubbing oil. Here and in the following, the temperature data for boiling ranges relate to the values obtained at atmospheric pressure (1 bar).

From «The catalytic pressure hydrogenation of coal, tars and mineral oils •, Springer Verlag, Berlin / Göttingen / Heidelberg 1950, page 42, it was also known that non-process oils, e.g. B. to use as starting oils in the coal hydrogenation. The constant supply of certain quantities of suitable "foreign oils" has already been practiced, although the use of foreign oils did not significantly exceed 20% of the total grinding oil requirement.

According to the present invention, on the other hand, the proportion of non-process hydrocarbon mixtures in the grinding oil is more than 30% by weight, preferably more than 50% by weight, and can increase up to 95% by weight. In the case of particularly suitable hydrocarbon mixtures, such as heavy, very low-paraffin oils, it is even possible to use them alone as a grinding oil.

The hydrocarbon mixture used as grinding oil should have an initial boiling point above 200 ° C., preferably above 300 ° C. The process-derived oils returned as grinding oil should also have an initial boiling point of more than 200 ° C., preferably more than 300 ° C.

It was found that mineral oils rich in naphtha or aromatics in general, and especially heavy and heavy oils as well as mineral and oil-derived top and / or vacuum residues as well as sulfur oils in oil shale and tar sand processing, represent surprisingly good grinding oil components that have good asphalt solubility. The amount of process-derived oil used as the grinding component can therefore be reduced, depending on the nature of the non-process hydrocarbon mixture. It is thus possible to obtain hydrogenation product from the bottom phase or gas phase which is otherwise attributed to the grinding process as a valuable product and to replace it with less valuable products in the grinding process. In extreme cases, the total amount of rubbing oil can be provided by non-process oils that are in the. Hydrogenation levels to high quality. Products are processed.

The result is a new type of hydrogenation process which is economically optimized due to the limited or no process oil return and which is characterized by a previously unknown flexibility with regard to the starting materials.

The process according to the invention is optimized in terms of reaction technology by the direct transfer of the gaseous bottom phase product into the gas phase without intermediate relaxation: in addition to the energetic advantages, undesirable reactions of the thermally unstable and reactive oil-like products of the bottom phase hydrogenation during atmospheric distillation are avoided.

This is particularly important when using slightly coking heavy mineral oil-derived hydrocarbon mixtures, heavy and heavy oils as well as oil shale or tar sand heavy oils as grating oils, the products of which from the bottom phase hydrogenation tend to instability and gum formation. The mixtures of oils derived from coal and mineral oil can tend to separate, particularly if the starting materials were less strongly hydrated in the bottom phase hydrogenation.

In addition, the fractional condensation of the gaseous sump or gas phase product allows the adaptation of the oils used as grinding oils amount and quality of oil to the amount and type of non-process rubbing oils.

In the known processes using only process-derived product as grinding oil, attempts are made to make the ratio of coal to grinding oil as large as technically possible in order to be able to keep the complex reaction space of the bottom phase hydrogenation small. Weight ratios of 1: 2 to 1: 1 are achieved. In the present process, on the other hand, in which valuable hydrogenation products are generated not only from coal, but also from the non-process hydrocarbon mixture used, it may be appropriate to lower the coal contents down to 1:20 choose. Weight ratios of coal and grinding oil from 1: 5 to 4: 5 are preferred.

In addition to the process-derived oil obtained by fractional condensation from the gaseous product of the bottom phase hydrogenation, it is also possible to use the oil which is obtained in the thickening of the bottom phase products, which are solid or liquid at the reaction temperature and pressure or at somewhat lower temperatures and, as mentioned above , are separated before the gas phase hydrogenation or the fractional condensation of the gaseous bottom phase product. The thickening is carried out in the usual way, for example by vacuum distillation, smoldering or coking. In addition to suitable non-process hydrocarbon mixtures, the oil obtained during the thickening can also be used alone as part of the grinding oil of process origin.

Two embodiments of the method according to the invention are described below with reference to the flow diagrams Fig. 1 and 2. In Fig. 1 the procedure is shown in which only a part of the bottom phase product is subjected to hydrogenation in the gas phase.

Finely ground and dried coal is fed via line 1, possibly with the addition of a catalyst via line 2, with a non-process-derived liquid hydrocarbon mixture in tank 4, possibly with the addition of one or more process-derived oils from line 5 a mixture of coal and liquid hydrocarbons.

Process oil can be used as a thickener of the bottom product of the hot separator 6, e.g. B. by vacuum distillation 7, vacuum gas oil fraction obtained via line 8 or as a condensed in the separator 9 01 via line 10, optionally after separating light components in an atmospheric distillation 28 via line 11.

The slurry is fed via line 12 to the pump 13, brought to a pressure of 300 to 700 bar there and via line 14 through the heat exchangers 15, 16 and, after addition of hydrogen via line 18, through the heat exchanger 17 and after heating in the preheater 19 pumped into the bottom phase hydrogenation 20, which usually consists of several reactors connected in series.

The reaction products leave the reaction part via line 21 and are separated in the hot separator 6.

The bottom product of the hot separator, which is composed of unreacted coal, possibly catalysts, asphaltenes and high-boiling oils, leaves the hot separator via line 22 in order to suitably, for. B. by vacuum distillation (7) or coke processes (7) to be worked up to high-boiling oils and a residual product. The oil-like product is either fed via lines 8 and 5 into the grinding container 4 or via lines 23 and 53 and intermediate compression with pump 25 to the pressure of the gas phase hydrogenation of the gas phase hydrogenation 24. Compressed product after pump 25 can be heated via line 57 in preheater 26 and introduced via lines 44 and 53 into the gas phase hydrogenation. In addition, oil-like product can be removed from the process via line 27.

The residual product of the hot separator sump processing leaves the process via line 29.

The products present in gaseous form in the hot separator 6 leave it after passing through the heat exchanger 31 via line 30 and are partially condensed by heat exchange with the fresh mash in the heat exchangers 17, 16 and 15 at the pressure predetermined by the phase-phase hydrogenation.

From the separator 9 connected downstream of the heat exchanger 17, the resulting liquid fraction is fed to the mashing tank 4 after condensation and a discharge of the gases released via lines 10 and 5, which is not shown in the flow diagram. If necessary, this fraction can reach an atmospheric distillation 28 via line 32, in which further light fractions are distilled off and removed from the process via line 33. The heavy fractions remaining in atmospheric distillation 28 are fed via lines 11 and 5 to the mashing container 4 or leave the process via line 34.

The fraction remaining in gaseous form in the separator 9 is fed to the separator 36 via line 35 by further heat exchange with the fresh mash in the heat exchanger 16. The resulting liquid fraction is via line 37, after adding hydrogen via line 38 and after heat exchange with products of the bottom and gas phase in the heat exchangers 39 and 31, via lines 58, 44 and 53, or after a possibly necessary Heating in the preheater 26 via lines 56, 44 and 53, into the gas phase hydrogenation 24. Thus the process pressure given by the bottom phase hydrogenation is used for the gas phase hydrogenation. The reaction products leave the gas phase reactor 24 and are supplied via the heat exchanger 39 and line 40 after expansion of the distillation 41.

The resulting heavy products leave the process via line 42. The gaseous products obtained in the distillation 41 are removed from the process via line 45, the lighter liquid products via line 46.

The gaseous products obtained in the separator 36 are fed to the separator 48 via line 47 and heat exchange with the fresh mash in the heat exchanger 15. The resulting liquid products leave the process via line 49. The gaseous products obtained in the separator 48 leave the process via line 50 and are released into a gas processing unit. The separators 9 and 36 are designed to improve the separation effect as amplifier columns with return 51, 52.

Fig. 2 shows the procedure in which the entire gaseous bottom phase product is further hydrogenated in the gas phase. Here, too, finely ground and dried coal via line 1, possibly with the addition of a catalyst via line 2, is mixed with a non-process-derived liquid hydrocarbon mixture supplied via line 3 and in container 4, possibly with the addition of a thickened bottom product the hot separator 6, e.g. B. by means of vacuum distillation 7, obtained oil via line 5, to a mixture of coal and liquid hydrocarbons. The mixture has a solids content of 5-50% by weight.

The slurry passes via line 12 to the pump 13, which brings it to a pressure of 300-700 bar and via line 14 through the heat exchangers 15, 16 and 17 and after heating in the preheater 19 into the bottom phase hydrogenation 20, which generally pumps out there are several reactors connected in series. Hydrogen is added to the slurry in line 14 via line 18. The reaction products leave the reaction part via line 21 and are separated in the hot separator 6.

The bottom product of the hot separator consists of unreacted coal, possibly catalysts, asphaltenes and high-boiling oils. It comes via line 22 to a workup 7, z. B. a vacuum distillation or a coker to be worked up in a suitable manner to high-boiling oils and a residual product. The oil-like product is fed via line 5 into the grinding container 4 or via lines 23 and 53 and intermediate compression with pump 25 to the pressure of the gas phase hydrogenation of the gas phase hydrogenation 24. If necessary, compressed product after the pump 25 can be brought via line 57 to the preheater 26, heated there and fed via lines 44 and 53 into the gas phase hydrogenation 24. Oil-like product can also be removed from the process via line 27.

The remaining product of the hot separator 7 leaves the process via line 29.

The products present in gaseous form under the conditions prevailing in the hot separator leave the hot separator 6 and are conveyed via lines 43, 44 and 53 using the pressure and heat content given by the phase-phase hydrogenation, if necessary after heating in the preheater 26 via lines 56, 44 and 53, the gas phase hydrogenation 24 fed.

The products of the gas phase hydrogenation 24 are partially condensed via line 55 by heat exchange with the fresh mash in the heat exchangers 15, 16 and 17 under the pressure given by the gas phase hydrogenation.

From the separator 9 downstream of the heat exchanger 17, the liquid fraction obtained, preferably a fraction of the medium oil and vacuum gas oil boiling range, is led out of the process via line 59.

The fraction remaining in gaseous form in the separator 9 is fed to the separator 36 via line 35 and further heat exchange with the fresh mash in the heat exchanger 16. The resulting liquid fraction, preferably a fraction of the naphthase boiling range, is removed from the process via line 54.

Gaseous product obtained in the separator 36 is fed to the separator 48 via line 47 and heat exchanger 15, condensed portions leave the process via line 49, gaseous products obtained in separator 48 are led out of the process via line 50 and into gas processing. given.

Claims (4)

1. Process for the hydrogenation of coal, in which finely ground coal is pasted with pasting oil which consists of hydrocarbon mixtures extraneous to the process and, for the remainder, of oil originating from the process, and is hydrogenated at pressures of 100 to 700 bar, preferably 250 to 350 bar, and temperatures of 350 to 520 °C, preferably 440 to 490 °C, with hydrogen, optionally in the presence of catalysts, in a bottom phase, the products which are liquid and solid at these pressures and temperatures are separated off, and gaseous product, if appropriate after intermediate condensation, is further hydrogenated without pressure release in a gas phase. over fixed catalysts and liquid product is isolated by fractional condensation, characterized in that the pasting oil consists to the extent of 30 to 100 % by weight, preferably 50-95 % by weight, of hydrocarbon mixtures, extraneous to the process, from the group of petroleum-derived top residue and/or vacuum residue, heavy oil or very heavy oil or oil from low temperature carbonization of oil shale and/or tar sand, having a boiling range such that boiling commences above 200 °C and preferably above 300 °C, with the remainder consisting of oil originating from the process and having a boiling range such that boiling commences above 200 °C, preferably above 300 °C.

2. Process according to Claim 1, characterized in that the coal and the pasting oil are employed in a weight ratio 1 : 20 to 1 : 1, preferably 1 : 5 to 4 : 5.

3. Process according to Claim 1, characterized in that the part of the pasting oil originating from the process consists, at least partially, of an oil obtained by fractional condensation of the gaseous product.

4. Process according to Claim 1, characterized in that the part of the pasting oil originating from the process consists, at least partially, of the oil obtained on thickening the liquid and solid products separated off.

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