DE1253691B - Process for the continuous hydrogenation of coal - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. CL:

Clog

German KL: 12 ο - 1/05

Number: 1 253 691

File number: U6624IVb / 12o

Filing date: November 5, 1959

Opened on: November 9, 1967

The invention relates to a method for hydrogenating coal at high temperature and low pressure, which is carried out in a relatively small reaction space.

The known processes for hydrogenating coal to form liquid fuels and substances containing chemicals have a number of disadvantages, including in particular the low rate of coal hydrogenation, which makes a large reactor volume necessary. In addition, the extraordinarily high pressures in the conversion system and the consumption of large amounts of hydrogen prove to be unfavorable. In these known processes, the flow rate of the coal varies between about 320 and 640 kg of coal per cubic meter of Hochdruckumwandlervolumens per hour (20 to 40 lbs / cuft / h), and that at an operating temperature of 485 ⁰ C or less, and at a hydrogen consumption of 0 , 0825 kg of hydrogen per kg of coal.

The object of the present invention is now to find a method which has a much higher rate of carbohydrate hydrogenation at significantly lower pressure with higher temperatures and lower hydrogen consumption.

The present invention relates to a process for the continuous hydrogenation of coal, in which a preheated, 40 to 70% carbon containing paste at 175 to 840 at and temperatures of 500 ⁰ C and it was hydrogenated with hydrogen, which is characterized in that the hydrogenation at a temperature of 500 to 600 ^° C. with 0.01 to 0.08 kg of hydrogen per kilogram of coal, at a linear speed of the reaction mixture of at least 0.9 m / sec., a residence time of at least 1 minute and a minimum throughput of 2400 kg coal / h / m ³ reaction volume.

Hydrogenation temperatures of up to 550 ⁰ C and throughput rates of up to 4 kg / 1 catalyst volume have been proposed in the catalytic hydrogenation of liquid hydrocarbons, for example in German patents 871 299 and 885 700, but the reaction ratios of these processes are considerably different from those of a carbohydrate hydrogenation, which is generally carried out without a catalyst. As a result of the interaction of the measures according to the invention, surprising results in the direction of rapid carbohydrate hydrogenation with low hydrogen consumption are achieved in the new process. The combination of the various claimed reaction conditions is therefore essential for the present process.

Process for continuous hydrogenation
of coal

Applicant:

Union Carbide Corporation,
New York, NY (V. St. A.)

Representative:

Dr. W. Schalk, Dipl.-Ing. P. Wirth,

Dipl.-Ing. G. E. M. Dannenberg

and Dr. V. Schmied-Kowarzik, patent attorneys,

Frankfurt / M., Große Eschenheimer Str. 39

Named as inventor:

John Hancock Howell, South Charleston, W. Va.

Edward William Doughty, Westfield, N. J .;

Paul Luther Alspaugh,

South Charleston, W. Va. (V. St. A.)

From the drawings shows

Fig. 1 is a flow diagram for the entire coal hydrogenation process,

F i g. 2 is a graph showing the effect of temperature on the rate of reaction of the Coal at two different rates of hydrogen consumption (per kilogram of coal),

F i g. 3 shows a graph of the yields of various products plotted against the amount of hydrogen per kilogram that is consumed per kilogram of coal;
F i g. 4 is a view of a tubular reactor for hydrogenating coal.

The flow scheme in FIG. 1 shows a schematic representation of the flow of coal through the individual stages of the hydrogenation process and the products formed in the process. The mine coal is conveyed from a storage barrel 10 into a pulverizer 11 , in which it is first comminuted and dried in a hot gas stream until it is practically free of water. Then it is finely pulverized to a diameter smaller than about 0.2 cm and the coal thus pulverized is introduced into a coal heater 12 in which it is heated to a temperature between 350 and 375 ° C. This can be done by indirect heat exchange through metal pipes or preferably by direct contact with a heated inert gas atmosphere.

From the coal heater 12 from the heated, pulverized coal goes to a mixer 13, in which it

709 687/422

is mixed with hot paste oil as described below.

In the mixture of coal and paste oil, the concentration of coal is 40 to 70 percent by weight. From the mixer 13, the coal / paste oil mixture is pressurized by means of a pump 14 set and pumped into a reactor 15. The coal flowing out of the pulverizer 11 can however, it can also be mixed with the paste oil without heating, and the mixture can then be used before introduction in the reactor 15 are heated. From the explanations below, however, it will be seen that the The procedure shown in the flow diagram is to be preferred.

A modification of the method according to the invention can also be carried out before the mixture of coal and make-up oil is introduced into the reactor 15. At this point a suitable catalyst can be added if desired. The actual hydrogenation of the coal takes place in the reactor 15. In this reaction vessel, which, as explained below, can be of various types, hydrogen is introduced and brought into contact with the mixture of coal and paste oil. Since a minimum pressure of 175 kg / cm ^{2 is} necessary to hydrogenate the coal according to the invention, the pump 14 presses the hot mixture of coal and paste oil to a pressure of 175 to 840 kg / cm ² , preferably 280 to 420 kg / cm ² before it is introduced into the reactor 15.

The hydrogen is introduced under a similar pressure. The temperature in the reactor is kept at 500 to 600 ⁰ C, preferably at 500 to 56O ⁰ C,

After leaving the reactor 15, the products can be separated from one another in different ways be separated. For example, a hot separator 16 can be used which separates the reaction product into one vapor stream and one from liquid and solids existing stream.

The steam flow from the hot separator 16 flows to a cold separator 17, in which the easily condensable vapors are condensed, and then by an expansion pump 18 before being in the light oil distillation device 19 enters.

The non-condensable gases are separated in the cold separator 17 and can be in different Way to be treated. If this gas stream consists mainly of hydrogen, then it can with the Be washed under pressure at which it arises, then further compressed and then fed back to the reactor 15 for further carbohydrate hydrogenation. The gas flow can, however, also be expanded by a pump 20 and obtained as such. In the end the gas flow can also be carried out through a high-pressure scrubber (not shown in the flow diagram) passed and the hydrogen separated from the gaseous hydrocarbons and returned to the reactor are supplied, while the so separated gaseous hydrocarbons relaxed and as such are won. The respective treatment of the gas stream used depends primarily on the hydrogen content of the gas flow, which in turn depends largely on the type of gas used Reactor 15 determined. In the case of a reactor equipped with a stirrer, the hydrogen content is relatively high, and recirculation is advantageous. On the other hand, it becomes a tubular When the reactor is used, almost all of the hydrogen supplied to the reactor 15 is used in the hydrogenation consumed, and the hydrogen content of the gas stream is quite low, so that recycling is unnecessary and the entire gas streams can be removed as product. The other stream from the hot Separator 16, which consists of liquids and solids, is by an expansion pump 21 and then passed to the light oil still 19, as well as that containing the light liquids Electricity from the cold separator 17.

The products leaving the reactor 15 can initially also be separated by another method will. In this process, the gases flow through an expansion pump 22 and then into one Cooler 23. After cooling, the products are directed to the cold separator 17, from which the gases can be removed directly as the end product. In this case, the expansion pump 20 is not required, since the gases are already being expanded by the pump 22. After removing the gases in the cold Separator 17, the liquids and solids flow directly to the light oil distillation device 19, the pump 18 being bypassed. Thus, the light oil distillation device 19 contains the same liquids and solids as in the first described method and using the hot one Scheider's 16th

The light oil distillation device yields two end products directly during distillation, one of which is referred to as light oil and contains the majority of the chemical compounds obtained from the coal. This light oil boiling in the range of 75 to 27O ⁰ C at atmospheric pressure. The other end product from the light oil still 19 is a heavier oil fraction, referred to as middle oil, which, as will be described, contains other valuable compounds. The boiling range of this middle oil is 270 to 330 ° C at atmospheric pressure.

The light oil still 19 provides another stream that is heavy, i.e. above 330 ° C Liquids boiling at atmospheric pressure and consists of solids. This stream is in the Solids separator 24 passed, which od from a centrifuge or from a mechanical pressure filter. Like. can exist. The solid residue obtained from the solids separator 24 is an end product of the Process and can be used as fuel if its carbon content is high enough, or it can be similar to the ash from steam plants be worked up. Heavy liquids that make up the solid residue in the solids separator 24 has been removed are introduced into the pitch distiller 25. In this still the heavier oils of a certain area, the so-called paste oil, are distilled off and the remaining residue is removed as a pitch product. The still 25 includes a vacuum device, and the make-up oil is characterized by a boiling range of about 330 ° C at atmospheric Pressure, up to about 350 ° C at a pressure of 5 to 50 mm Hg. Higher boiling material is called Bad luck. This paste oil fraction is preferably not removed directly as the end product, but rather fed to the mixer 13 anew, where it is mixed with the coal pulverized for the process will. The pitch obtained can be used to produce high quality coke from the electrodes and the like can be produced. Given-

if so, some of the heavy liquid from the separator 19 can be added directly to the mixer 13 newly added distilled paste oil can be used.

Bituminous coal containing pitch is preferred for carrying out the method according to the invention. Even Lignite as well as types of tar, which are obtained by coking coal or lignite, turn out to be to be useful.

The paste oil used in the process is preferably obtained in the process itself, ie it is oil, tar or pitch free of solids with an initial boiling point above 325 ^° C. at atmospheric pressure. If the product from the pitch distillation device 25 is used directly as the paste oil, there is the additional advantage that the oil is already hot and can be introduced directly into the mixer 13 after slight heating or without further heating. The charcoal or the paste oil can be heated before mixing, just as the mixture produced at room temperature can be heated after mixing. In the temperature range between 200 and 370 ° C, however, highly concentrated charcoal pastes cause difficulties in their handling, so that it is sometimes beneficial to preheat the mixture ingredients before mixing, since heating the charcoal before mixing with the hot paste oil is a practical method of handling Coal pastes are of a high concentration of coal.

The concentration of the coal in the oil paste is preferably 40 to 70 percent by weight.

Before the coal-paste oil mixture into the hydrogenation device 15 is introduced, a catalyst can, if desired, be added. A useful one However, the catalyst increases the rate of the reaction and reduces the temperature required. Suitable catalysts are, for example, nickel, tin, iron, lead or derivatives of these metals, which are used in liquid state in slurries or solutions with hydrocarbon oils.

If the hot and pressurized mixture of coal and paste oil together with the hot, pressurized hydrogen is introduced into the reactor, the actual carbohydrate reaction takes place instead of. If the process is carried out in such a way that a certain amount of pitch is obtained from the coal one of its advantages is that part of the hydrogen contained in the coal is used for this purpose will produce gases and oil with a higher percentage of hydrogen than the coal itself, at the same time a pitch of low hydrogen content is obtained. Will be one with agitator equipped reactor is used, the gas mixture from the cold separator 17 contains up to 75% Hydrogen and can be returned directly to the mixture. However, a high pressure washer can preferably be used be used, which separates the gaseous hydrocarbons, during the relatively pure hydrogen is fed to the reactor 15 again.

The rate of reaction and the proportions of the various products derived from the coal depend on related factors, namely the temperature, the degree of agitation, the pressure and the ratio of the hydrogen added. The reactor must ensure an intimate mixing of the liquid, solid and gas phases, which corresponds to a vortex flow as defined by an average linear velocity of the gas and the 'liquid phase of at least 0.9 to 3 m / sec. or more is marked. A pressure of 175 to 840 kg / cm ² and a temperature of 500 to 600 ^° C. are of decisive importance for the hydrogenation process according to the invention. The hydrogen will be added in a ratio of 1 to 8 kg per 100 kg of coal, a ratio of 2.5 to 7 kg being preferred.

One of the main disadvantages of previous processes is the slow processing speed of the coal, the high pressures required and the high hydrogen consumption. In the method according to the invention However, these disadvantages are overcome by the use of improved reaction vessels described later, in which lower pressures and higher temperatures can be used.

Investigations have shown that the rate of reaction to gaseous hydrocarbons doubles every 15 ° C increase in temperature if the coal is at a temperature above 490 ° C is hydrogenated. The speed of the reaction to liquid products also increases when also a little slower. The effect of temperature on the rate of hydrogenation is shown in FIG. 2 graphically represented; there is hydrogenated amount per hour and cubic meter of the reactor space against the Temperature plotted, the information being given for two different hydrogen ratios. the end This graph shows the steep increase in the rate of reaction with increasing temperature evident. For the method to be carried out effectively, it is advantageous if a minimum amount of about 2400 kg per cubic meter of the reaction volume per hour is caused to react (150 lbs / cuft / h), about 3200 kg and more being preferred for economic reasons.

In the process according to the invention, coal was converted into gaseous and liquid Products obtained yields of more than 85% using amounts of hydrogen which under the proportions of about 0.0825 kg used on average in known processes Hydrogen per kilogram of coal.

The actual relationships between the three main end products, i.e. H. of gases, oils and des Pechs, is determined by the hydrogen added per unit of quantity of coal. In general, is correct set temperature and pressure conditions, the degree of hydrogenation and thus the proportion of coal, which is converted into gas and liquid, the greater and that which is converted into pitch, the less, the more hydrogen is added. This is in FIG. 3 shows the percentages of the three end products made using different amounts of hydrogen from a coal sample are shown.

A useful reactor is extremely important to the successful practice of the invention. Such a Reactor or converter is a vessel under high pressure and temperature in which the liquid, solid and gaseous phases are mixed well and heat is used to heat or cool the Reaction mixture is effectively transferred, and which contains enough space to allow a reaction time

from 1 to 10 minutes and allow the reactants to flow continuously through the vessel. Such a reactor is preferably equipped with a stirrer so that the individual phases of the reaction mixture are sufficiently mixed.

F i g. Figure 4 of the drawing shows a preferred form of reaction vessel used for carrying out the method is suitable according to the invention. This reactor has a tubular shape and consists of a number vertical tubes 31 and 35, which are connected to one another by reverse bends 33. The mixture from coal in make-up oil, hydrogen and possibly a catalyst flows into the reactor and through an upwardly projecting tube 31 through a reverse bend 33 and down through an after pipe 35 protruding below. Then a reverse bend 33 directs the mixture upwards to another protruding pipe 31, and the mixture then continues to flow alternately up and down through the further reactor tubes. Both the upwardly extending tubes 31 and the downwardly extending tubes 35 have heating jackets 32 and 34, respectively.

These heating jackets surround the lengths of the reaction tubes and are equipped with suitable connections equipped, such that a heat exchange means through the annular cavity between the Jacket and the pipe can flow. The jackets can be used to hold the contents of the pipe either to heat or to cool. The warming jackets are a delicate and precise tool to regulate the temperature of the reactants in the tube. This reactor also has the advantage of that the temperature can be changed at various points in the reaction process by simply changing the temperature of the medium in different parts of the heating jackets.

The high temperature used in the process of the invention enables the mixture to send through the reactor at high speed because the reaction is at high temperature fast going on. A linear speed of at least about 1 to 1.1 m / sec. is in the vertical running pipes are essential for adequate mixing of the reactants, and speeds of over 6 m / sec. be used. The high speed and reaction rate lead to a very high reaction rate per cubic meter of the reactor, which is very important economically.

As stated above, the tubular reactor also has the advantage that the hydrogen is very effective is consumed, whereby a recycle of the contained in the gaseous products Hydrogen becomes unnecessary, which makes operation even more economical.

A definite advantage of the tubular reactor

there is the possibility of doing without moving parts for stirring the mixture. The only way to properly mix the respondents is that they are forced through the pipes at high speeds. In the pipe 31 protruding upwards the gas phase rises in bubbles through the liquid phase, creating an intimate mixture. In the downwardly projecting pipes, however, there is a tendency that the liquid phase on the walls the tube forms a film through which the other phases flow in the middle. Around The downwardly protruding tubes 35 reduce the appearance and facilitate good mixing 25 to 75% smaller in diameter than the upstanding tubes 31, thereby reducing the reactants are compressed and a separation of the individual phases is prevented.

F i g. Figure 4 of the drawings shows that in accordance with the preferred embodiment of the invention, a reactor is used in which the pipes are in a vertical position. This arrangement has several Advantages, for example the good use of space and more thorough mixing of the phases at lower speeds caused by the constant changes in direction and the narrow after pipes protruding below is effected. However, pipes can also be used that are less than 90 ° to the horizontal, or even horizontal pipes can be used if the The speed at which the reactants run through the tubes is kept high enough to ensure turbulence and careful mixing of the phases. For non-vertical pipes are speeds of about 2.50 m / sec. the minimum required while speeds up to about 24 m / sec. are permitted.

In the case of horizontally stored pipes, their diameters are of course equal to one another.

Comparison of operating conditions for carbohydrate hydrogenation

Operating conditions

Erflndu
Ve
minimum ngs according to
drive
maximum 6.0 Known procedure
A *
Minimum | maximum beta 700 Known procedure
B **
Minimum | maximum Behj 700 140 700 0.08 210 480 525 470 490 560 15th 450 0.05 liter 445 0.04 filter With agitator
provided Be
container or pipe 16000 40 60 1.05 70 320 0.12 384 0.11 0.01 30th 80 30th 1.5 640 416 2400 50 45 40

Pressure, kg / cm ² ..
Temperature ⁰ C.
Type of reactor

Reactor mixture speed, m / sec. .

Hydrogen consumption, kg / kg coal

Response time, minutes

Passage speed of the coal through the
Reactor, kg / h / m ^{3 of} the reactor volume

Charcoal in charcoal paste,%

* High pressure hydrogenation according to Ludwigshafen-Heidelberg, ATI No. 76, 480, August 1950, Central Air Documents Office. ** United States Department of the Interior, Bureau of Mines, Report of Investigations 5043, April 1954.

The advantages of the carbohydrate hydrogenation process according to the invention over the two most important known ones Procedures are clearly shown in the table.

The method according to the invention leads to a large number of valuable chemicals. The analysis of the products from different batches or fractions of the process according to the invention has shown that, under the preferred operating conditions described above, the process yields gas, oil and pitch products which have certain properties of former compounds. For example, it has been found that in the process according to the invention at least 10 percent by weight of coal is converted into a light oil ^{fraction with a boiling range between 75 and 300 0} C at atmospheric pressure and that this fraction contains at least 20 percent by weight of phenol-containing substances and at least 4 percent by weight of nitrogen-containing organic compounds, the remaining amount consists mainly of aromatic hydrocarbons. It was also found that the phenols present in the light oil fraction, which boil at a temperature between 230 and 270 ° C., contain 15 to 30 percent by weight of indanols, while the final yield of indanols is 0.1 to 0.3% of the weight of the coal processed and for every cubic meter of the reactor space there are at least about 3.2 kg (0.2 lbs / cuft / h) of indanols per hour. In addition, it was found that in these phenols boiling between 230 and 270 ° C., at least 70% of the o- and p-positions are unsubstituted, ie only substituted by hydrogen.

The phenols as a whole represent at least 4% of the weight of the coal processed and their yield is at least about 128 kg per cubic meter of reactor volume per hour (8 lbs / cuft / hour). 40 to 50% of the weight of the phenols which boil at temperature between 207 and 23O ⁰ C, consist of äthylsubstituierten phenols.

It was also found that at least 2 percent by weight of the according to the invention Process produced light oil present mononuclear bases, heterocyclic, tertiary amino compounds are. The indoles also make up at least 0.1% of the total weight of the processed coal, and the yield of indoles is at least 3.2 kg per cubic meter of reactor volume per hour (0.2 lbs / cuft / h). 50 to 90 weight percent of the hydrocarbons present in the light oil product aromatic, and at least 10% are naphthalenes.

The method according to the invention was carried out in the method shown in FIG. 1 of the drawings shown 1 month long carried out using a tubular reactor. The following are the operating conditions and the yields obtained during this period are listed.

Operating conditions
Type of coal: Pittsburgh No. 8, seam coal

Reactor pressure, kg / cm ² 315

Maximum reactor ^{temperature, 0} C ... 510
Speed of passage of coal

through the reactor, kg / h / m ³ des

Reactor volume 2400

Coal in the coal paste,% 50

Hydrogen feed rate,

m ³ / h 1960

Hydrogen feed line in kilograms per 100 kg of coal

Speed of the reaction mixture, m / sec

Ash-free, benzene-insoluble components in kilograms per 100 kg coal.

Ash-free and pyridine-insoluble components in kilograms per 100 kg money

Converted hydrogen in kilograms per 100 kg of coal

Crude yield (kilograms per 100 kg coal)

Raw light oil

Raw medium oil

gas

bad luck

Yield of purified products (kilograms per 100 kg coal)

Phenol 80 - 20 (80% phenol and 20% cresol)

Cresols

Low boiling phenols

m-phenols

High-boiling phenols

Total phenols

aniline

Toluidines

Xylidines

Quinolines

Other bases

Bases total

naphthalene

Methylnaphthalenes

Tetralin

Low-boiling hydrocarbons.

Aromatic solvents

High boiling hydrocarbons 230-260 ° C

High-boiling hydrocarbons above 26O ⁰ C

Total neutral light oil

4.0 3 29

7 3.0

16.2

7.1

13.8

30.0

0.37

1.05

1.47

1.09

1.65

4.21

0.018

0.058

0.17

0.02

0.534

0.80

0.48

0.62

0.18

1.28

2.34

2.06

3.48 10.99

Claims (5)

Patent claims: 1. A process for the continuous hydrogenation of coal, in which a preheated paste containing 40 to 70% coal at 175 to 840 atm and temperatures of 500 ⁰ C and above is hydrogenated with hydrogen, characterized in that the hydrogenation is carried out at a temperature of 500 to 600 ⁰ C with 0.01 to 0.08 kg of hydrogen per kilogram of coal, a linear speed of the reaction mixture of at least 0.9 m / sec., A residence time of at least 1 minute and a minimum throughput of 2400 kg of coal per hour each Kilogram reaction volume carries out. 2. The method according to claim 1, characterized in that the reaction temperature between 500 and 56O ⁰ C and the reaction pressure between 280 and 420 kg / cm ² . 3. The method according to claim 1 and 2, characterized in that a reactor with horizontal stored tubes and the average linear velocity of the gas phase and the liquid phase at least about 2.5 m / sec. amounts to. 709 687/422 4. The method according to claim 1 and 2, characterized in that a reactor with perpendicular stored pipes is used, in which the pipes are connected so that the gas phase and the liquid phase at an average linear velocity of at least about 1 m / sec. flow alternately up and down. 5. The method according to claim 4, characterized in that a reactor is used in which that part of the vertical tubes through which the The gas phase and the liquid phase flow downwards, has a diameter that is 25 to 75% smaller as the part of the vertical tubes through which the phases flow upwards. Considered publications:
German patent specifications No. 615 397, 712 311,
871299, 885 700; German Auslegeschrift No. 1 018 406;
U.S. Patent No. 2,832,724. 1 sheet of drawings 709 687/422 10.67 Q Bundesdruckerei Berlin