DE2803985A1 - Pressure liquefaction of coal - with coking of the liq. product phase under pressure in presence of hydrogen - Google Patents

Abstract

After hydrogenation of powdered coal as a slurry in oil, under heat and pressure, opt. with catalyst, and separation into gas and liquid phases, the liquid phase contg. residual solids is passed without pressure release to a zone in which it is coked in presence of H2 at round the hot separator pressure. Used in conversion of coal to benzine, fuel oil and other fractions. Coking under pressure eliminates wear on the usual release valve and produces a low viscosity, stable distillate tar, which is very aromatic but almost free from asphaltenes. It is very suitable for mixing with fresh coal, since it shows little tendency to polymerise, and for further processing in fixed catalyst beds, where the low asphaltene content prevent coking or sticking in the bed.

Description

The invention relates to a method for liquefying coal,

in which the charcoal is mixed with grind oil to a pulp, pumped under pressure, preheated and then in a reactor zone in the presence of hydrogen and optionally The catalyst is liquefied and the vapor-liquid table leaving the reactor zone is subjected to phase separation in a hot separator.

When coal is liquefied, it prepares for processing in the sump of the liquid residue produced downstream of the reactor Difficulties, as this usually still contains considerable amounts of solids, like unused coal, ash and catalyst particles, but also with asphaltenes and valuable distillates is enriched.

It has become known, the residue of the hot separator in throttle valves to relax and by means of centrifuges into a thinner fraction (thin run) and a to decompose thicker fraction (Dickleuf). The thin sheet is then fresher for mixing Coal used, while the thick barrel is fed to a pressureless Kugelechweler and is further processed into coke and smoldering oil. The petrol-free smoldering oil is then also used as a grinding oil for fresh coal.

It has been shown that this is produced by unpressurized charring Smoldering oil is extremely unstable, which measures polymerisation-friendly, is and will be renewed Use as a grinding oil in the liquefaction reactor, even high reaction pressures are required power.

This in turn leads to a high technical and thus also financial A wall. The carbonization of the hydrogenation residue in spherical furnaces also leads to unpleasant odor nuisance for the environment. Another disadvantage is that that the throttle valves, in which the hydrogenation residue falling in the hot separator relaxes becomes, due to the solids content of the hydrogenation residues, a strong V @@ schlei are exposed and therefore often have to be set for.

The invention is based on the object of developing a method this in a simple and economical way to work up the in the sump of the hot separator resulting liquid residue allows.

According to the invention, this object is achieved by the fact that in the Phase elimination of the liquid fraction @ of the hot separator without relaxation ener coking zone and in this in the presence of hydrogen below about the pressure of the hot separator is coked.

By coking the liquid dhase of the hot separator according to the invention under increased pressure in the presence of hydrogen, preferably under about d pressure of the hot separator, a thin, stable distillation tar falls next to the coke which is very aromatic, but hardly contains any asphalthene. This stable As has been shown, tar is excellent for tempering fresh coal, as it has only a very low tendency to polymerize. Furthermore this coking product can also be used for further processing, for example to the gasoline, leizöl and other cuts required in practice, in solid arranged catalyst beds are fed. Because of the low salary There is no coking or sticking of the catalyst bed on asphalt. as Another advantage of the method according to the invention is that now no Throttle valves subject to high wear are more necessary.

The process proves to be particularly economical when after Another feature, the coking is carried out directly in the hot separator itself is, ie the coking in a separate coking device is now no longer necessary.

The coking itself is expediently carried out in such a way that the hot The sludge from the hot separator is passed onto a moving bed of coke and underneath Adding hot hydrogen is coked. The coke bed can be made by gas be moved in the manner of a fluidized bed or by a stirrer. In the last In this case, the presence of additional solid particles is recommended, for example wise of steel balls, which crush the coke and prevent caking. Of the However, the residue to be coked t <ann also to that provided in the coking zone Coke bed are sprayed, with a kind of spray dryer coking takes place.

The fine coke obtained as a coking product is expedient withdrawn from the coking zone via a lock system. The coke is in usually very fine-grained, so that it can be used directly without additional work-up Flungstromvergeser supplied and can be jernasted there.

Another very important advantage of the invention lies in the Excellent utilization of the sensible heat from the reactor or the hot separator emerging and coking residue. Because the temperature of the residue has already almost reached the required coking temperature is only a small additional supply of heat is required. This can be done by the name Hydrogen.

The fission oils produced in the course of the coking of the residue are saturated by the hydrogen. They become vaporous together with the rest Coking products withdrawn from the coking zone and along with the vapors of the hot separator is cooled in heat exchange with fresh coal pulp.

The vaporous coking products can thus be used in the same facilities how the vapors from the hot separator are condensed, relaxed and worked up which results in a further increase in the economic efficiency of the process.

tim to prevent high-boiling points occurring in the coking zone Fission oils through undesired secondary reactions, which lead to a reduction in the yield would lead to decomposition, it is necessary to remove them quickly from the coking zone to remove.

According to a further feature of the invention, there is provision for cracking oils the coking zone of a "supercritical gas extraction using lower boiling Hydrogen coal, such as liquefied petroleum gas, which mainly comes from pumps and butane, or from gasoline cuts that fall off during the hydrogenation itself as an extractant to undergo. Due to the high pressure, the density is about critical extraction agent is relatively hoc7, i.e. it is up to 40% of the corresponding density in the liquid state, while the viscosity almost does not change compared to the gaseous state. by succeeding in the cracking oils can be removed quickly without entrained coke particles in an undesirable manner.

The supercritical extraction is also recommended as an additional one Thicken the residue to be coked before it flows onto the bed of coke. Appropriately he follows this already at the end of the reactor and / or at the end of the hot separator. Propane and / or is also suitable as an extractant for this purpose Butane @ and gasoline cuts resulting from hydrogenation.

The method according to the invention is also suitable for coal extraction and is by no means restricted to the production of distillates by catalytic carbon hydrogenation bcrestricted.

Further explanations of the invention are shown schematically in FIG shown embodiment.

According to the figure, a plant for the catalytic hydrogenation of coal shows, finely ground and dried coal is fed via a line 1 to a mixing vessel 2 and there with a grinding wedge fed in via a line 3 to form a pulp stirred. The required catalyst is fed to the mixing vessel 2 via a line 4 fed-.

The coal pulp is by means of a pump 5 to a pressure of about 220 bar and then in the series qeschniteten heat exchangers 6 and 7 as well in cross section 8 of the externally heated furnace 14 to the start-up temperature of the hydrogenation heated from about 430 ° C and finally in the first stage of a two-stage hydrogenation reactor 9 fed, in which the hydrogenation of coal in the presence of hydrogen and of the catalyst takes place at an average temperature of about 480% C. The hydrogen is added to the system via a Line 10 supplied.

A product fraction falls at the top of the second hydrogenation stage of reactor 9 on, those from lower-boiling hydrocarbons in the gas phase, higher-boiling ones (heavy) hydrocarbons in the liquid phase, solids, such as unreacted Coal, ash and catalyst particles.

In addition, the product fraction also contains, among other things Hydrogen and water vapor. This product fraction is in a hot separator 11 passed and subjected to a phase separation in this.

In the sump of the hot separator 11, one containing the solids falls liquid fraction, which is fed to a coking unit 13 by means of a pump 12 will. The liquid residue from the hot separator is within the coking zone 13 11 under about the pressure of the hot separator in a mechanically moved and with Coke bed provided with steel balls in the presence of hydrogen at medium temperatures add about 450 - 600 U coked. For heating the residue to be coked serve both the hydrogen, which is heated in the furnace 14 to about 600 P and a Line 15 is fed to the coking zone, as well as supercritical gasoline vapors with a boiling range between about 70 and 160 ° C, which also falls in oven 14 heated to about 450 ° C and then via lines 16 and 17 of the coking zone 13 are supplied for supercritical gas phase extraction. By supplying Hydrogen as well as by performing the supercritical gas extraction succeeds it, to saturate the spinning oils arising in the coking ions and avoiding it quickly remove secondary reactions from the coking zone.

The extracted vapors as well as those produced by the coking from the coking zone 13 are withdrawn via a line 18 and together with the vapors of the hot separator 11, which are discharged via a line 19, fed via a line 20 to the heat exchanger 7, in this with the heat exchanger Coal pulp cooled to about 370 ° C, partially condensed and then in a separator 21 subjected to a phase separation.

In the bottom of the separator 21 falls a liquid fraction with a Beginning of boiling of about 280 ° C and an end of boiling of about 420 pounds, so essentially a medium and heavy oil. Part of this distillate is pumped out 22 via the branch lines 23 and 24 directly zuqemischt the Kohltrei, whereby this in an advantageous manner as well as diluted oil is also further heated.

As a result of the procedure described, it is possible to achieve a considerable Part of the exothermic excess heat generated in the reactor is fed back into the system, EO that, as has surprisingly been shown, external heat from the furnace 14 as a rule is only required to start up the system.

The remainder of the liquid hydrocarbon fraction obtained in the separator 21 is fed into a distillation stage 27 via lines 25 and 2G and added there valuable cm product oil processed.

The gaseous top fraction occurring in the separator 21 is over a line 28 is fed to the heat exchanger 6, ir heat exchange with fresh coal pulp partially condensed and then urlterzoqen in a separator 29 of a phase separation.

The hydrogen-containing gas obtained as the top product will zuntichst fed via a line 30 to an oil pressure washing stage 31 and then by means of a pump 32 is again pumped to system pressure. Fin part of the hydrogen gets into the system again via line 33, while the rest via line i5 withdrawn, heated up in the oven 14 and then, as already explained, the coking zone 13 is supplied.

The liquid bottoms of the separator 29, which is essentially Consists of medium oil, naphtha and water, comes via lines 34 and 26 also in the distillation stage 2i.

[n the distillation stage 27 takes place by distillation ..

In addition to separating the water, the fractions fed in are broken down, essentially in naphtha-rich, medium-rich and heavy-oil-rich partial fractions, which partially liter lines 35 are withdrawn as end products from the system. @ In a wider part of the distillation product of the distillation stage 27 is over the line 3 is supplied as an Abreib- @ ldem mixing container 2.

Darübert @naus turns the distillation stage 27 into a gasoline fraction withdrawn with a boiling point between about 70 and 160 ° C via line 16, then heated in furnace 14 to about 450 ° C and in the supercritical state, as already explained, Via the line 17 of the coking zone 13 for supercritical gas phase extraction fed.

@s also proves to be a useful part of the Supercritical gasoline vapors leaving the furnace via lines 36 and / or 39 the residue to be coked is already poor exit from the pump 12 and / or at Moden of the hot separator 11 to be supplied. This will be by overcritical Gas extraction Distillate oils carried along in the residue are driven out, so that in more advantageous Way, the liquid content of the residue to be coked is reduced.

Another coking product falls into the coking zone 13 fine-grain coke, which is withdrawn via a line 37 and that of a gasification plant can be supplied or burned.

It may prove useful, at least in part the vapors withdrawn from the coking zone via line 18 via a line 38 to be fed to the hot separator 11. Such a procedure is then of interest.

if the gases and vapors emerging from the coking zone are too much Contain extremely high boiling hydrocarbons and dust.

These impurities are countercurrent to the from the Reactor coming liquid stream precipitated in the crack separator or can in the upper part washed out and fed back to the coking process. Through appropriate Control of the supercritical gas extraction in the coking zone can also be ashless Bitumen can be produced as a product. In this case, those in line 1P The conducted vapors are subjected to partial condensation in the decomposition unit 40.

The bitumen accumulating in the dismantling unit is conveyed through a pipe 41 withdrawn and can at least partially fed to the mixing container 2 as a grinding oil will.

L e r s e i t e

Claims (8)

Method for liquefying coal Patent claims (4) '. procedure for liquefying coal, in which the coal is mixed with grind oil to a pulp, pumped to pressure, preheated and then in a reactor zone in the presence of hydrogen and optionally catalyst is liquefied and in which the reactor zone leaving vapor-liquid mixture in a hot separator of a phase separation is subjected, characterized in that the resulting from the phase separation liquid fraction of the hot separator fed to a coking zone without relaxation and in this in the presence of hydrogen under approximately the pressure of the hot separator is coked. 2. The method according to claim 1, characterized in that the coking zone is provided in the lower area of the hot separator. 3. The method according to claims 1 or 2, characterized in that that the coking of the liquid phase takes place in a moving bed of coke. 4. The method according to any one of claims 1 to 3, characterized in that that the hot vapors resulting from coking together with the hot top product of the hot separator are cooled in heat exchange with the coal pulp to be heated. 5. The method according to any one of claims 1 to 4, characterized in that that in the coking zone occurring cracking oils of a supercritical gas extraction To be subjected. 6. The method according to any one of claims 1 to 5, characterized in that that those present at the end of the liquefaction reactor and, or in the hot separator Liquefaction products subjected to supercritical gas extraction Werrl (! N. 7. The method according to claims 5 or 6, characterized in that that as an extractant lower boiling hydrocarbons, preferably liquid total and / or gasoline cuts. 8. The method according to claims 1 bts 7, characterized in that that optionally in the top product of the hot separator and / or the coking zone contained bitumen-derived extracts at least partially separated therefrom under pressure and reused oil as an incentive and / or withdrawn from the plant as an end product will.