DD158036A1 - PROCESS FOR THE CONVERSION OF COAL AND / OR HIGH-END EDGE OR TARP-BACK CONDITIONS BY COLUMN PRESSURE HYBRIDIZATION - Google Patents

Abstract

In the splitting pressure hydrogenation, a mixture of ground coal in a low-asphalt oil and / or high-boiling petroleum and / or tar residues and a hydrogenation-active catalyst is introduced into the upper end of a reaction vessel. In an upper heat exchange zone, hydrogen-containing gas at the reaction temperature flows into the mixture in an amount such that the mixture is heated accordingly or the gas is cooled. The hydrogen-containing gas introduced at the lower end of the reaction vessel is heated to the reaction temperature in direct heat exchange with the solids-containing mixture coming from the hydrogenation zone, this mixture in which the majority of the hydrogenation products are present being taken off at the lower end of the reaction vessel becomes. In the upper and lower zones of the direct heat exchange, soils are provided for the countercurrent of gas and liquid in such an amount as to ensure sufficient contact between the hydrogen-containing gas and the liquid mixture.

Description

Process for converting coal, and / or high-boiling petroleum or tar residues by means of cracking pressure hydrogenation

Application of the invention:

The invention relates to a process for the conversion of coal and / or high-boiling petroleum or tar residues by cleavage pressure hydrogenation in a preferably vertically arranged, provided with shelves reaction space under countercurrent flow of the carbonaceous material and the hydrogen-containing gas.

Characteristic of the known technical solutions: The splitting pressure hydrogenation of z. B. hard coal or brown coal has been known for a long time. In general, if appropriate, dried and finely ground coal is treated with a heavy oil to a pulp, first in the so-called sump phase at high pressures, up to about 700 bar, and high temperatures, eg. B. 400-500 ° C, with hydrogen. The product obtained is z. B. initially conducted in a held at slightly below 'reaction temperature hot separator, from which one withdraws a bottom product (blowdown) and hot gases and hydrocarbon-containing vapors, which are in the desired manner, z. B. de.stillativ, worked up.

The pressure hydrogenation is carried out in the presence of catalysts which are generally obtained in fine form, e.g. slurried in the coal slurry, introduced into the reaction room and removed from the process with the sludge. It has already been proposed in the past to work in the pressurized hydrogenation of coal also in the presence of fixed catalysts (DRP 7 208 24), whereby the hydrogen is passed in cocurrent or countercurrent to the coal.

228937

However, such hydrogenation with plague bed catalysts could not prevail because the catalysts lost their activity too quickly. In the art, therefore, one has only suspended in coal slurry finely divided catalysts, eg. As iron compounds, worked. It turned out that only empty reactors, especially those without cross-assemblies, worked satisfactorily, because otherwise very quickly deposits on the internals occurred that could force them to shut down the plant (Krönig, "The catalytic pressure hydrogenation of coals, tars and mineral oils" Springer Verlag 1950, p. 26). Furthermore, a direct current of coal slurry and hydrogen proved to be the most advantageous, since the effect of hydrogen on the fresh pulp is particularly intense and thus the inlet temperature of the reactor could be kept relatively low due to the positive heat of the reaction reaction (1 c, S 31). In addition, it was found that in the preheating of the coal circuit expediently hydrogen should be present, so that the formation of polymers at the necessary preheater temperature, up to about 400 ° C, avoided (1 c., S, 28) and a first hydrogenation of Coal is reached, which already runs to a considerable extent in the preheater (1. α., P. 39). It has therefore been until recently the coal hydrogenation in the bottom phase carried out only in the manner described above, even in new experiments with fixed bed catalysts (DT-OS 2,224,364, DT-OS 2,715,625, DT-AS 2,654,635), although this procedure has significant disadvantages. In addition to the high expenditure on equipment are particularly disturbing the fact that due to the coal-free hydrogen direct current with decreasing Wasserstoffpartikäldruck this does not meet the requirements, as they face in view of the becoming more difficult from reactor to reactor coal removal, so that it to a unsatisfactory utilization of the reaction space comes. Further, the heat exchange between the products introduced at a low temperature and exiting the reaction chamber at a high temperature is not ι ήi ρ heat n & c. AbKnhlamms is not used.

, J ""

In addition, the tube bundles of conventional regenerators quickly pollute, causing the heat transfer values fall sharply. For these reasons, in order to achieve the temperature required for the start of the hydrogenation reactions, it is necessary to operate a preheater which has a high energy consumption.

Object of the invention:

The invention is inter alia based on the object of carrying out the so-called wet phase hydrogenation by means of a process for the conversion of coal and / or high-boiling petroleum or tar residues by cracking pressure hydrogenation at temperatures of 400-500 ° C and under pressures of 80-700 bar, wherein a mixture of ground coal or high-boiling petroleum or tar residues introduced in hydrocarbon oils and a catalyst in the presence of hydrogen-containing gas passes through a hydrogenation zone, both in terms of equipment and energy requirements.

To achieve this object, the invention proposes that a carbon-containing mixture of finely ground, optionally dried coal in a low-asphalt oil and / or high-boiling petroleum and / or tar residues and a present in finely divided form hydrogenation catalyst with a temperature of 80 - 350 ° C at the upper end of a reaction vessel,

supplying the hydrogen-containing gas partially at a temperature of 20-250 ° C at the lower end of the reaction vessel and partly as a cold gas in the hydrogenation zone held in the reaction vessel at a reaction temperature of 400-500 ° C and passing it countercurrently to the carbonaceous mixture;

the carbonaceous mixture after entering the kti on'Rapf ä <s "in rH τ-ρ» V-H nri Hsrmosiicfaiicfh m H + - rl om on Ppi -

heated at the reaction temperature, heated from the hydrogenation up the hydrogen-containing gas to the reaction temperature and then withdrawing the thus cooled gas at the upper end of the reaction vessel,

the hydrogen-containing gas introduced at the lower end of the reaction vessel is heated to the reaction temperature in direct heat exchange with the solids-containing mixture coming from the hydrogenation zone and this mixture, which contains the majority of the hydrogenation products in addition to the solids, is withdrawn at the lower end of the reaction vessel .

wherein in the upper and the lower zone of the direct heat exchange soils for the countercurrent of gas and liquid in such a number that sufficient contact of the hydrogen-containing gas is ensured with the liquid mixture.

As starting materials, all types of coal, with particular advantage lignites, -selected. The coals are generally ground to a particle size of less than about 5 mm and, if necessary, dried to a water content of about 0.1-12%. As Anreiböl for the preparation of the carbon and catalyst-containing mixture is advantageously used an originating from the process oil, eg. B .. a vacuum distillate from the bottom product of a arranged behind the hydrogenation separator or medium and heavy oil distillates. Of course you can also use foreign oils. The asphalt content of the Anreiböls should be below about 5%. In general, a ratio of coal to propellant oil of about 1: 3 to 1: 0.8, in particular 1: 1.5 to 1: 1, is selected in the mixture. The grinding can be carried out in a known manner.

consequences. When choosing the Anreibkomponenten is to ensure that the mixture at the introduction temperatures in the reactor, which should be at about 80-350 ° C, in particular 80-120 ° C, is still sufficiently fluid. Other starting materials are high-boiling petroleum r and / or tar residues, in which also catalyst was introduced.

The catalyst can be added at any point in the feed preparation, e.g. B. in the form of a solution. As a catalyst, all conventional hydrogenation or cleavage-active compounds can be selected, as z. B. from the process of coal or oil hydrogenation are known. Because in general of. a reuse of the catalyst is omitted, one will use inexpensive compounds, eg, iron salts, namely z. B, in amounts of about 0.5 10%, based on the pure carbon used.

The feed mixtures are introduced into the reaction vessel in the usual way at the upper end and reach an upper heat exchange zone. Here, hydrogen-containing gas, which is at the reaction temperature, flows in such an amount that the mixture is heated accordingly or the gas is cooled. The reaction temperature is generally 400-500 ° C, in particular 470-480 ° C, the reaction space is maintained at a pressure zwischen.etwa 80 700, in particular 100 - 300 bar. The pressure is chosen so that the main part of the hydrogenation is in liquid form and thus can be withdrawn at the bottom of the reaction vessel together with the solids.

The countercurrent recycle gas to the carbonaceous mixture entering the top of the reaction vessel is saturated with hydrocarbons produced in the hydrogenation zone. Their main quantity, z. B. 80-85 '%, condensed in the relatively cold countercurrent carbonaceous mixture.

28937

This is the. Circulation gas, ζ. B. cooled to about the mixture inlet temperature and withdrawn at the upper end of the reaction vessel. It can directly in this or z. B. are passed over a heat exchanger in a Flüssigproduktabscheider. In the heat exchanger, the gas leaving the reaction vessel can be converted by indirect heat exchange, for example, into a heat exchanger. B. are cooled with originating from the liquid product separator cycle gas from the previously contained in it hydrocarbons z. B. were removed by an oil wash.

The loaded with the condensed hydrocarbons mixture moves down in the reaction vessel in the hydrogenation. Here, the carbon degradation takes place with positive heat of reaction, wherein by supplying cold gas, the reaction temperature to the desired level, z. B. 470 480 ° C, is set. When passing through the hydrogenation zone, the carbon in the mixture is degraded up to 99% depending on the feedstock. This applies in particular also z. The residence time of the carbon-containing mixture or of the liquid hydrogenation products is about 15 to 12.0, preferably 30 to 60 minutes. It is an advantage of the inventive method that, in contrast to the operation of a conventional liquid phase reactor in which the newly formed hydrocarbons are removed in vapor form from the process and thus escape further action of the active only in the liquid mixture catalyst, the majority of the hydrocarbons liquid remains, which improves the hydrogenation.

The hydrogen-containing gas which is not consumed for the hydrogenation is introduced into the reaction vessel in a circulation gas stream in countercurrent to the carbonaceous mixture at the lower end or laterally under the desired reaction pressure. Its hydrogen content will generally be above about 65% by volume, more preferably above about 75% by volume. You can preheat the cycle gas stream, z. In the

gases and vapors discharged, ζ. Β. to temperatures of up to about 250 ° C / in particular up to about 100 ° C. The further heating of the cycle gas stream to the reaction temperature then takes place in a heat exchange zone in the lower part of the reaction vessel, wherein the products coming from the hydrogenation, at reaction temperature products their Transfer heat to the gas. The amount of cycle gas stream is advantageously chosen so large that this in the lower heat exchange zone with appropriate cooling of the products to the desired reaction temperature, for. B. 470 - 480 ° C, is heated. The introduced into the hydrogenation cold gas is brought to the reaction temperature by the heat of reaction.

The hydrogen, which is to replace the hydrogen consumed in the hydrogenation and removed with the products of the reaction chamber in dissolved form hydrogen, is called a "fresh gas", which advantageously has a hydrogen content of z. B. has more than 95 vol .-%, added to the cycle gas or introduced in the form of cold gas at one or more points of the reactor. The amount of cold gas must be chosen so that it is sufficient; to remove the heat released during the chemical reaction, as far as these are not dissipated with the products leaving the reaction space or by radiation. The heat thus available for any use is greater than in the previously customary apparatus arrangement of a sump phase in which the radiated and therefore unusable amount of heat due to the larger number of necessary apparatus, eg. As generators, coolers, hot lines, is considerably larger than in the inventive method.

The further workup of the .Umsetzungsprodukte as well as the solids contained in them takes place in known and customary procedures. In the case of the inventive type of hydrogenation, it may also be advantageous, in addition to the part of the bottom product from the separator or certain oil fractions, which are used as Anreibö'l use, more

-a- 228937 O

Quantities in the cycle .in the implementation due. In general, this is not required.

Since a return of a portion of the solids-containing sludge, as it is carried out in the usual procedure in a sump phase, can be omitted in the inventive method, and because of the short residence time of the solids, the asphalt content in the discharged. The product is very low and the solids present in it are not prone to form incrustations or unwanted granular precipitates, the so-called caviar, which are otherwise very annoying by gradual addition of reactor and lines. This also results in a lower pressure drop than e.g. in the previously customary sump phase hydrogenation.

The inventive combination of heat exchange and hydrogenation in countercurrent allows a particularly good utilization of the reaction volume, d. H. higher throughputs of carbon than previously possible. For the preparation of the carbon-containing mixture, it is also possible to add, in addition to the oils mentioned, fractions of lower-boiling hydrocarbons, for example from the benzine range. Thereby, the amount of carbon supplied can be increased because these hydrocarbons are at least partially removed from the reactor with the recycle gas stream, so that they do not significantly burden the reaction zone.

The reactor used for the process according to the invention should, at least in the heat exchange zones located above and below in the reaction vessel, have devices which ensure thorough mixing of the reactants but also ensure that the best possible separation of the liquid and gaseous products takes place after thorough mixing. For these purposes, the incorporation of soils into the reaction space is particularly suitable, while that of fillers has not proven so well. In a preferred embodiment, the trays should alternately be located opposite one another, on the wall of the reactor

Have recesses and can additionally be perforated in a variety of ways. They are arranged either horizontally or obliquely downward pointing towards the recess. In a particularly advantageous embodiment, they receive at the recesses downwardly bent edges, which may be broken to increase the Durchinischung, z. B. are toothed. It must be provided a sufficient number of such soils, especially in the sensed reaction chambers, in each of which takes place the heat exchange between discharged and supplied products. With advantage one can also use the soils in the hydrogenation zone, distributed over these or in certain sections. Attach. ·

In the recesses of the soil gas and liquid are mixed with vigorous turbulence and then flow. at the bottom surfaces in z. B. horizontal opposite direction past each other to then separate again. Due to the bent down, optionally broken edges on the recesses form under the floors Gacräume, which favor the process described. In a particularly advantageous embodiment, the floors, in particular at reactor diameters up to z. B. 1500 mm, in groups, for. B. four floors or more, arranged. In this way, with a good utilization of the reaction space, a virtually complete separation of gas and liquid after mixing thereof is achieved and a backflow of the liquid is avoided. With larger reactor diameters, fewer soils may suffice. It may be advantageous to provide the uppermost baffle plate of each group in the hydrogenation zone with a plurality of perforations through which the gas can exit and ascend to the next baffle group, By arranging the bpdes in groups, the reaction space is divided into sections. which changes abruptly the partial pressure of hydrogen, whereby the reactions are advantageously influenced .werden.

228937 0

The reactors can otherwise the übl.ichen devices, eg. For example, while carrying out the splitting pressure hydrogenation according to the known methods, the internal reactor diameter up to e.twa 1500 ram, otherwise the mixing was not sufficient, in the process according to the invention reactors with inner diameters of 3000 mm and more can be used since the devices to be mounted according to the invention also effect a good mixing even with these dimensions and the cold gases can be done in a known manner.

Of course, one can combine the inventive countercurrent reactors with the known, conventional DC reactors or switch several countercurrent reactors in series. Then, one will generate the countercurrent between the upper part of the first reactor and the lower part of the last reactor. However, this should only be necessary in exceptional cases, since the reactors operated according to the invention 'because of the ability to operate them with a larger diameter than the reactors previously used, allow much higher throughputs, especially since the pressure drop in the reactor is low.

A very significant advantage of the method according to the invention is that the expenditure on apparatus is considerably lower than in the case of the bottoms phase apparatus used in the usual way. This comprises separate means for preheating the starting materials, for carrying out the hydrogenation reaction and for cooling the products obtained. It is z. B. the preheater particularly susceptible to contamination, corrosion and erosion, - as are the zwis' are the apparatuses hot lines. These 'complex and error-prone facilities omitted in the inventive method, since here the heat exchangers and the hydrogenation zone in an apparatus together

are caught. Accordingly, ζ. B. reduces the cost of installation and repair.

Further advantages are an improved utilization of the reaction space as well as considerable savings in energy when carrying out the process according to the invention, since the otherwise required complex preheating of the starting materials is eliminated and also the heat of the sludge, d. H. of the product mixture discharged at the lower end of the reaction vessel is used optimally. In addition, because of the possibility of being able to build the hydrogenation reactor very large according to the invention can be thought of the combination of several conventional 'sump phase chambers, whereby considerable economic advantages are achieved.

Embodiment:

In-der.Figur the inventive method, for example, shown in principle, with the sake of simplicity to the representation of the necessary and conventional ancillary equipment, eg. As pumps, compressors, washes, was omitted. Coal was chosen as the feedstock.

In the reaction space l, which is under elevated pressure, fine-ground, containing only small amounts of water coal, along with finely divided catalyst mixed in a heavy oil fraction, introduced at a relatively low temperature via line 5. The reaction chamber is equipped with groups of horizontally arranged trays 2, which alternately have at the opposite walls recesses 3, which are provided with nach'unten bent edges with sawtooth-like recesses. The upper and lower groups comprise more soils than those in the middle reaction space. After heat exchange in the upper group, in which the carbonaceous mixture is fed to the reaction mixture by countercurrent hot hydrogen-containing gas.

temperature is brought, the mixture flows down through the mixing groups serving soil groups, wherein the hydrogenation of the coal takes place. Through the lines 9 cold, hydrogen-containing gas is introduced, with the help of which the heat which is formed in the exothermic hydrogenation, as far as is discharged, 'that the desired reaction temperature is maintained in the middle reaction space. The hydrogen-containing gases introduced in these, i. H. the cold gases and the circulating gas introduced via line 7 at the lower part of the reaction space leave the reaction space via line 8. At the top of the reaction vessel, a free space 14 is set by liquid products. From the hydrogenation zone, the mixture containing the major part of the hydrogenation products enters the lowest bottom group, which also serves as a heat exchanger. Here, the heat of the mixture at the reaction temperature is transferred to the hydrogen-containing cycle gas supplied via line 7, which was previously preheated in the indirect heat exchange in the heat exchanger 10. After appropriate cooling, the mixture is withdrawn via line 6 from the reaction space and fed to a (not shown) workup. The withdrawn via line 8 at the upper end of the reaction chamber gases that were brought in the upper floor group at a low temperature and lead hydrocarbon vapors' pass, after passing through the heat exchanger 10, in which they transfer their heat indirectly to the recycle gas in the Separator 11, from which the condensed hydrocarbons are withdrawn via line 12, via lines 13 or 13a can be added to the recycled via line 7 recycle gas, optionally after the (not shown) laundry, fresh hydrogen.

Claims (8)

Invention claim: 1. A process for the conversion of coal and / or high-boiling petroleum or tar residues by cracking pressure hydrogenation at temperatures of 400-500 ° C and at pressures of 80-700 bar, whereby a mixture of milled coal or high-boiling petroleum or tar residues and a catalyst in the presence of hydrogen-containing gas passes through a hydrogenation, zone, characterized in that comprising a carbonaceous mixture of finely ground, possibly dried coal in a low-asphalt oil and / or high-boiling petroleum and / or tar residues and a finely divided Feeds the form of hydrogenation-active catalyst having a temperature of 80-350 ° C. at the upper end of a reaction vessel, partially feeds the hydrogen-containing gas at a temperature of 20-250 ° C. at the lower end of the reaction vessel and partly as a cold gas into the hydrogenation zone held in the reaction vessel at a reaction temperature of 400-500 ° C. and conducts it in countercurrent to the carbon-containing mixture, the carbonaceous mixture, after it has entered the reaction vessel, is heated to the reaction temperature in direct heat exchange with the hydrogen-containing gas at the reaction temperature, flowing upwards from the hydrogenation zone, and then the thus cooled gas is removed at the upper end of the reaction vessel, introduced at the lower end of the reaction vessel hydrogen-containing gas in direct heat exchange with the reaction temperature, coming from the hydrogenation zone solids-containing mixture to the reaction temperature heats up and this mixture, in which.neben the solids is the main amount of Hydriefungsprodukte, at the bottom of the Withdrawing reaction vessel, ii 228937 O wherein in the upper and the lower zone of the direct heat exchange soils for the counter-flow of gas and liquid in such a number that ensures sufficient contact of the hydrogen-containing gas is ensured with the liquid mixture. 2. The method according to item 1, characterized in that adjusting the residence time of the carbonaceous mixture in the hydrogenation to 15 to 120, preferably 30 to 60 minutes. 3. Method according to. Item 1-2, characterized in that one uses the reaction vessel leaving hydrogen-containing gas in the indirect heat exchange for heating the recycle gas and / or fresh hydrogen. 4. The method according to item 1-3, characterized in that one attaches soils with alternately opposite, located on the wall of the reaction vessel recesses. 5. The method according to item 1-4, characterized in that one attaches to the recesses of the floors downwardly bent open edges' .. 6. The method according to item 1-5, characterized in that applying perforated floors. 7. The method according to item 1-6, characterized in that one attaches soils in the hydrogenation zone. 8. The method according to item 1-7, characterized in that four or more soils combined in groups attaches. H} eF2u'iSeiia drawings