Apparatus for converting coal to hydrocarbons by hydrogenation

A method and apparatus for converting, i.e. hydrogenating, dry particles of coal with hydrogen to give hydrocarbons such as engine or heating fuels. The invention combines together several steps in the hydrogenation process, such as compressing the dry coal, heating, plasticized and hydrogenating, in one apparatus. The apparatus comprises a housing, preferably a cylinder containing a feed and preparation portion of a chamber with a rotatable friction element therein and an immediately adjoining hydrogenation portion of the chamber with a rotating rotor therein and with static mixing nozzles projecting thereinto, through which nozzles heated hydrogen can be injected into the coal which has been brought, by the friction element into a heated, plastic state. The friction element and rotor can be driven by a single drive means, the feed and preparation portion of the chamber can be fed with coal from a hopper through a wheel lock and the hydrocarbon products can be ejected through a valve into a separator.

The invention relates to a method and apparatus for converting, using 
hydrogen, coal to hydrocarbons by hydrogenation. 
A broad field of prior art is known in respect of both methods and 
apparatus for converting coal to hydrocarbons by high pressure 
hydrogenation. Apparatus for high pressure hydrogenation usually operates 
by first producing a coal pulp comprising crushed coal and mixing oil. The 
pulp is fed to a pre-heater, after which it passes into a reactor together 
with the paste-forming oil or mixing oil, which is added only to enable 
the coal to be pumped. The reaction products thereafter pass into a hot 
separator and units which continue the process. 
The main disadvantage of a coal hydrogenating plant of this kind is that 
the pre-heater, which usually comprises coils of piping embedded in a 
metal block and electrically heated, becomes clogged with coking products. 
The previously proposed installations further comprise many separate units 
interconnected by pipe and valve systems. For this reason too a large 
amount of trouble has to be expected in operation. The coal particles 
mixed with a paste forming oil and the hydrogenation products themselves 
are at very high pressures, up to 500 bars, and high temperatures, up to 
500.degree. C. It is obvious that under such conditions products can only 
be conveyed from one unit to another by very expensive, specialized 
equipment. 
Other hydrogenation processes have been proposed, operating without any 
so-called paste forming or mixing oil. Published German specification No. 
2,723,457, for example, describes a method and apparatus for hydrogenating 
coal, starting with particles of dry coal. To enable a hydrogenation 
product to be obtained from dry particles of coal, however, an injector 
system on the rocket drive mechanism principle is used in this case. Many 
disadvantages of the prior art can indeed be avoided by using such a 
method and the appropriate reactor, but the installation itself is 
extremely complicated and therefore very liable to trouble in operation 
and expensive in manufacture, which means that the hydrogenation products 
prepared have to carry high costs. 
The invention has among its objects to provide a method and apparatus for 
converting coal into hydrocarbons by hydrogenation, whereby the steps of 
compressing, heating, plasticized and hydrogenating can be carried out 
inexpensively in one piece of apparatus. 
The invention also aims to provide a method and apparatus for converting, 
using hydrogen, coal into hydrocarbons which can be carried out with dry 
coal particles, without the disadvantages of paste-forming oil, which 
apparatus can be constructed cheaply and be of compact form. 
According to one aspect of the invention, there is provided a method of 
converting, using hydrogen, coal to hydrocarbons, comprising feeding dry 
particles of coal in the form of powder or pieces continuously into a 
chamber from a pressure-sealed volume-controlled dispenser, compressing 
the particles of coal in the chamber and continuously converting them into 
a plastic state by frictional heat, subjecting the plastic coal in the 
chamber to intensive motion and impinging upon it with hydrogen to cause 
distribution, dispersion and hydrogenation and feeding the plastic and 
gaseous hydrogenation products continuously to a hot separator. 
According to another aspect of the invention, there is provided apparatus 
for converting, using hydrogen, coal to hydrocarbons, comprising a 
pressure-sealed volume-controlled dispenser, a chamber into which dry 
particles of coal can be fed from the dispenser, the chamber comprising a 
feed and preparation portion and a hydrogenation portion, a friction 
element in the feed and preparation portion of the chamber to compress the 
coal and convert it into a plastic state by frictional heat and a rotor 
and static mixing nozzles in the hydrogenation portion of the chamber. 
By feeding dry particles of coal into the feed and preparation portion of 
the chamber by means of the pressure-sealed volume-controlled dispenser, 
an initial pressure can be built up even in the feed and preparation 
portion of the chamber, which initial pressure can considerably accelerate 
the compressing process and the heating process by means of frictional 
heat. The pressure is prevented from spreading from the feed and 
preparation portion of the chamber to the dispenser. 
Since dry coal particles with a relatively high bulk weight can be fed in, 
the compressing of the particles can provide a pre-requisite for the next 
step in the method, namely the heating by friction. 
Intensive shearing, can cause internal friction of the individual particles 
of coal resulting in rapid heating of the particles. 
The quantity of frictional heat transferred to the coal depends on the 
geometrical formation of the friction element and the induced drive power 
transferred to the coal material by the rotating friction element. The 
faster the friction element turns the more rapidly the coal particles are 
converted to the plastic state and conveyed into the hydrogenation portion 
of the chamber. 
When the friction treatment applied to the compressed particles of coal 
enables the agglomerating or plasticizing temperature to be reached (this 
may be from 350.degree.-450.degree. C. depending on the type of coal) the 
fluid, heated hydrogen is injected. This is accompanied by intensive 
eddying of the plasticized coal, i.e. intensive distribution and 
dispersion or spreading out. 
When the heated hydrogen comes into contact with the high-temperature, 
plasticized coal, hydrocarbons of different valencies will be formed 
according to the conditions of the process (pressure, temperature, 
residence time) in an exothermic reaction. 
The fact that the hot hydrogen injected strikes the very finely distributed 
coal in motion and strikes the whole content of the hydrogenation portion 
of the chamber almost simultaneously can ensure extremely rapid 
conversion, i.e. hydrogenation, to hydrocarbon, and the apparatus 
therefore can achieve a very high output. 
The plastic and gaseous hydrogenation products can thereafter be fed 
continuously to a hot or cold separator and, according to their character, 
are further processed into engine or heating fuel. 
The feed and preparation portion of the chamber in which the dry coal 
particles are compressed is preferably cylindrical and the rotating 
friction element exerts a conveying action and heats the coal to 
hydrogenating temperature by frictional heat. The material then passes 
into the hydrogenation portion of the chamber which is also preferably 
cylindrical and adjoins the preparation chamber without any transition. 
The hydrogenation portion of the chamber contains the rotating rotor, which 
rotor has vanes and is secured against relative rotation with respect to 
the friction element. The static mixing nozzles are preferably of 
different lengths and project into the hydrogenation portion of the 
chamber, ensuring that the hydrogen will be ejected in different planes 
and thus uniformly throughout the volume of the hydrogenation portion of 
the chamber. The speed of hydrogenation and the output of the apparatus 
can be controlled dependent on the peripheral speed of the rotor and of 
the friction element connected thereto. 
By providing the hydrogenating portion of the chamber and the feed and 
preparation portion of the chamber in a single housing, it becomes 
possible to carry out the compressing step, the heating process, the 
plasticized process and even the hydrogenating process in one piece of 
apparatus, thereby eliminating many of the sources of trouble experienced 
in prior art apparatus. 
For example it is no longer necessary for the dry coal particles to be 
pre-heated in a separate apparatus as in U.S. Pat. No. 3,030,297 and fed 
into a pipe by means of a further machine, namely a conveyor, and for the 
pre-heated carbon particles in the pipe to be further heated by heated 
hydrogen and conveyed into the pre-heater. Since the heating in the 
pre-heater and in the reactor, which can be equated with the chamber of 
this invention, is carried out by means of coiled pipes which are taken 
through in a helical or cage shaped arrangement and to which heat is 
applied, the danger of these coiled pipes, carrying the coal particles and 
hydrogen, coking up is particularly great because heating to hydrogenating 
temperature is effected by heat conduction. Furthermore there is a danger 
of the valves and pipes becoming clogged. 
In the apparatus of this invention the combination of the steps necessary 
for the hydrogenation process and the processing conditions which become 
necessary, in one machine unit accommodated in a single chamber, thus can 
avoid the aggravating disadvantages of prior art. 
Since the apparatus can have a considerable output despite the appreciable 
reduction in the number of pieces of apparatus, because a positive and 
controllable eddying speed for the coal with the hot hydrogen is produced 
in the hydrogenating chamber, i.e. the reactor, the installation can be 
very economical. 
Separate drives for the friction element and the rotor can be provided if 
desired in order that the respective peripheral speeds can be adapted to 
different grades of coal. 
If two drives are used, it is possible to arrange the hydrogenation portion 
of the chamber at right angles to the feed and preparation portion of the 
chamber but with the two portions still in one housing. 
Using a friction element and a rotor turning in a cylinder can give a 
machine which is very robust and durable, less expensive and also less 
subject to trouble. This becomes particularly clear in a comparison with 
the machines formerly employed for carrying out the component processes, 
such as mixing units, piston pumps and preliminary heaters which were very 
liable to trouble. 
Units rotating in cylinders are far safer and more readily controlled from 
the engineering point of view.

Referring to the drawings, and firstly to FIGS. 1 to 5, apparatus for 
converting coal to hydrocarbons with hydrogen, comprises a 
pressure-sealable feed hopper 1 which is closed at its top end by a valve 
2. At the bottom end of the hopper 1 there is a cellular wheel lock 3 
which shuts off the hopper 1 from a feed and preparation portion 4 of a 
chamber. 
The feed and preparation portion 4 is formed by a cylinder 4a (FIG. 2) with 
tempering passages 5 extending in a longitudinal or radial direction 
therein. A circulating heating or cooling medium may be applied to the 
passages 5 by means of a tempering system (not shown). 
In the feed and preparation portion 4 there is a friction element 6 
carrying friction webs 7 in a helical arrangement. The angle of the web 7 
i.e. the lead angle between a vertical and the axis of the friction 
element, is chosen according to the conveying speed desired. 
The pitch width 7f, i.e. the spacing between adjacent friction webs 7, is 
chosen according to the size of the coal particles to be hydrogenated or 
to the viscosity of decomposed coal paste to be used. It is also possible 
to vary the pitch depth between the individual friction webs 7, e.g. to 
allow for control of pressure in the feed and preparation portion 4 at the 
downstream end thereof. As the pitch depth and pitch width 7f are reduced 
there is an increasing build-up of pressure from a pressure build-up 
region 23 to a friction region 24 towards a hydrogenation portion 9 of the 
chamber. 
The friction element 6 and a rotor 8, secured against rotation with respect 
thereto and located in the hydrogenation portion 9 of the chamber are set 
in rotation by drive means 10, which will not be described in detail. 
The rotor 8 in the hydrogenation portion 9 has vanes 11 thereon. These may 
be arranged obliquely to the axis of the rotor 8, to produce a conveying 
action in the chamber 9. FIG. 2 of the drawings shows spoon-like vanes 11. 
However, the vanes could be constructed differently, e.g. in the form of 
coiled webs 11b on the rotor 8, which are interrupted at positions 11c, 
where static mixing nozzles 12 project into the portion 9 of the chamber. 
The hydrogenation portion 9 is formed by a cylinder 13 which has integral 
tempering passages 14. The passages 14 may extend around the cylinder 13 
in a radial direction or may extend axially. A tempering system which will 
not be further explained is connected to the passages 14. This system 
allows for steplessly adjustable tempering, that is to say, for heating 
the cylinder 13 when the installation is being started up and for cooling 
it during subsequent operation. 
The static mixing nozzles 12 project into the hydrogenation portion 9 and 
fulfil two functions. The nozzles 12 are disposed between the rotor vanes 
11 in such a way that they reach the rotor 8. The vanes 11 impart a 
conveying movement to the material, which is thus acted upon by the 
following row of static mixing nozzles 12 and subjected to intensive 
mixing and eddying. A succeeding row 11a of vanes then picks up the stream 
of material, and the intensive mixing and shearing movements are repeated. 
In addition to their mixing function the nozzles 12 have the function of 
feeding hydrogen to the portion 9 of the chamber. Thus passages 15 (FIGS. 
3 and 4) are provided in the nozzles 12, the passages 15 being closed at 
the end and also at the side half way along the length by non-return 
valves 16 and being connected to a hydrogen supply system 17. The system 
17 is connected to a compressor 18 and a hydrogen source 18a, whereby 
hydrogen is forced into the portion 9 of the chamber under pressure. 
The portion 9 is closed at its downstream end by a valve 19 which opens 
when a pre-selected pressure is exceeded. When the hydrogenation products 
have passed through the valve 19 they enter a hot separator 20, which can 
be closed by means of valves 21 and 22. 
The operation of the apparatus for converting coal into hydrocarbons with 
hydrogen, will now be described. 
Coal is fed into the hopper 1 in the form of powder or pieces. The valve 2 
in the hopper is closed and pressure builds up. The coal in powder or 
piece form passes into the feed and preparation portion 4 through the 
cellular wheel lock 3. Care must of course be taken to ensure that bridges 
do not form in the hopper 1 and cause trouble. For this purpose agitating 
elements (not shown) are preferably fitted in the hopper 1 to keep the 
contents of the hopper 1 constantly in motion. To allow for continuous 
operation a second feed hopper can be provided, its valves and feed to the 
feed and preparation portion 4 being switched over when the first hopper 
has been emptied. 
The cellular wheel lock 3 enables controlled quantities of the pieces of 
coal to be fed into the feed and preparation portion 4 of the chamber. At 
the same time it ensures that the pressure prevailing in the feed portion 
4 cannot spread into the hopper 1. 
In the feed portion 4, which is divided into two regions, namely the 
pressure build-up region 23 and the friction region 24, the coal is moved 
towards the hydrogenation portion 9 of the chamber by the rotating 
friction element 6. The material is constantly compressed by the friction 
webs on the friction element 6, which webs define a passage between them. 
The rotating movement of the element 6 conveys the pieces of coal by means 
of the conveying side faces of the webs 7 towards the hydrogenation 
portion 9. The coal particles are thus subjected to a shearing movement by 
the webs 7, thereby generating frictional heat and increasingly 
agglomerating them. The particles pass from their powder or piece form 
into an agglomerated state and from there into a plastic state as a result 
of the increasing shearing action. 
The frictional element 6 is preferably constructed as described below and 
shown in FIG. 5. In the pressure build-up region 23 the friction webs 7 
may have a pocket-like undercut 7a, to allow for conveying without great 
friction losses and thus for a build-up of pressure in the direction of 
arrow 7d. 
The webs 7 provided with undercuts 7a extend approximately into the region 
where adequate pressure is reached in the feed and preparation portion of 
the chamber, and into the region where the aggregate state of the coal is 
converted into paste form or into a plastic phase. 
In the friction region 24 the webs 7 may be provided with inclined portions 
7b and 7c on both sides, so that they preponderantly exert a rubbing 
action on the coal particles or on the plastic phase of the coal. 
The rubbing action of the inclined portions 7b and 7c generates 
considerable frictional heat to raise the temperature of the coal in paste 
or plastic form. 
It is also important that, once the coal has become pasty or plastic, it 
should adhere to the inner wall of the cylinder 4a and be removed 
therefrom by the rotating movement of the friction element 6, through the 
conveying action of the web sides 7a, 7b. In this way a large amount of 
frictional heat is transferred to the coal, thereby aiding in rapid and 
very strong internal heating. 
The conversion of the aggregate state of the coal from the piece or powder 
form to the plastic form is assisted during a starting-up phase of the 
installation by heating the cylinder 4a of the portion 4 by means of a 
tempering medium which circulates in the tempering passages 5. This 
enables the installation to be brought rapidly to its operating 
temperature. 
To accelerate the hydrogenation process hydrogen may be fed into the coal 
even at the end of the feed and preparation portion 4. The coal will be 
plastic by then and be at a temperature of approximately 400.degree. C. 
and a pressure of approximately 400 bars. For this purpose static mixing 
nozzles 12a, fitted with a non-return valve, extend through the wall of 
the cylinder 4a. The nozzles 12a communicate with a hydrogen supply system 
17 connected to the compressor 18 and the hydrogen source 18a. 
The plastic coal, already enriched with hydrogen and brought to a high 
temperature in the feed and preparation portion 4, is passed into the 
hydrogenation portion 9 by the conveying action of the friction webs 7. In 
the portion 9 it is subjected to an intensive mixing and shearing action 
by the rotor vanes 11 and the static mixing nozzles 12 disposed between 
the vanes. 
Referring now to FIG. 4, eight vanes 11 are provided on the rotor 8 
disposed around its periphery. This number may be increased or reduced 
depending upon the length and efficiency of the hydrogenation portion of 
the chamber. 
The hydrogen, which is put under very high pressure by the compressor 18, 
is injected into the portion 9 through all the mixing nozzles 12 
simultaneously. The fact that the nozzles project different distances into 
the portion 9 enables the hydrogen to be injected at many places 
simultaneously and almost centrally into the portion 9. This allows the 
hydrogen and plastic coal to be intensively and evenly distributed and 
dispersed throughout the whole volume of the portion 9, and results in 
extremely intensive and rapid hydrogenation. 
In this connection the term "distribution" refers to mixing of the various 
components, while the term "dispersion" is used to describe the separation 
of individual coal particles by rubbing. The dispersion considerably 
accelerates the splitting up of agglomerated parts of the coal and thus 
the hydrogenation process. The dispersion and spreading out of the 
contents of the hydrogenation chamber take place primarily on the inner 
wall of the cylinder 13. 
Since the hydrogenation portion 9 of the chamber is also surrounded by the 
radial or axial tempering passages 14, additional heat can be supplied 
from outside while the installation is in its starting phase. The passages 
14 are connected to tempering systems (not shown) which provide a 
circulating tempering action. 
Since the hydrogenation reaction in the chamber 9 is exothermic, the 
tempering passages 14 are switched over when the starting-up time for the 
installation is over, and are used as cooling passages with a circulating 
cooling medium to dissipate the heat. 
A very high pressure of up to 500 bars is maintained in the feed and 
preparation portion 4 and in the hydrogenation portion 9. Care must 
therefore be taken to ensure that the outlet of the portion 9 can be 
pressure-sealed by means of the valve 19 which will open when a 
preselected pressure is exceeded. When the hydrogenation products have 
passed through the valve 19 they enter the hot separator 20, which 
separates solid from liquid products. The hydrogenation products then 
undergo further processing in the usual, known manner. 
To enable the friction element 6 in the feed and preparation portion 4 and 
the rotor 8 in the hydrogenation portion 9 to be driven at different 
speeds, the arrangement shown in FIG. 6 can be used, where the portions 4 
and 9 are accommodated in a common housing but the drive 10 drives only 
the friction element 6 and a separate drive 10a drives the rotor 8. The 
friction element 6 and the rotor 8 are either engaged one within the other 
at their position of contact or run freely centered in the respective 
cylinders 4a and 13. The speed difference is advantageous for 
hydrogenating charge coal with different properties and hydrocarbon 
content. 
FIG. 7 shows an installation with a vertical hydrogenation portion 9. In 
this arrangement the friction element in the feed and preparation portion 
4 drives the rotor in the hydrogenation portion 9 by means of the bevel 
gearing 28 indicated. The rotor in the hydrogenation portion 9 is mounted 
at its ends in bearings 29 and 30. Such a disposition of the hydrogenation 
portion 9 and the feed and preparation portion 4 can take up very little 
space and be particularly advantageous in certain cases. 
FIG. 8 shows an embodiment where the portions 9 and 4, arranged in a common 
housing, are of the same diameter. The advantage of such an embodiment is 
that a cylinder extending right through the apparatus can be used, this 
being simpler and cheaper to manufacture than a stepped cylinder. 
Providing the internal diameter of the cylinder 13 of the portion 9 twice 
as large as that of the cylinder 4a of the portion 4 has the advantage 
that the volume in the hydrogenation portion can be up to four times as 
great, so that the hydrogenating performance in a given time can be 
quadrupled. However, if the diameters of the portions 4 and 9 are equal as 
in FIG. 8, it is desirable for the diameter of the shaft of the rotor 8 to 
be reduced accordingly, in order to have more volume available for 
carrying out the hydrogenation process. In a preferred embodiment the 
diameter of the shaft of the rotor 8 in such a case is chosen to be down 
to half the diameter of the shaft of the friction element 6. The shaft 
diameter is understood as being the diameter measured without the rotor 
vanes 11 and without the webs 7 on the friction element 6.