Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to a process for feeding a sus-
pension of carbon to the reactor of a carbon gasification plant.
The reactor of a carbon gasification plant is preferably
operated at gauge pressure. The gauge pressure and its maintenance
are ensured by installing pressure locks at the feeding and at the
discharge end of the reactor. Certain types of locks for example,
pumps, and worm gear, require at the feeding end usually the use
of a liquid as a carrying agent, for the carbon, being particular-
ly in the form of coal. Pumps and the like require a mixture
adapted to being pumped, the liquid content of which is relatively
high.
The liquid used is preferably water which is simultaneously
used for the production of CO- and H2 -containing gas. The
invention is based on the admixture of gas to the suspension o~
carbon known from the German patent ~,631,185. In that patent,
pre~erably carbon dioxide in liquid Eorm is used as the ~as. The
liquid carbon dioxide acts as a slurrying agent and means of
conveyance for the coal dust. Moreover, the carbon dioxide acts
as a moderator of the gasification process.
The admixture of gaseous media to the suspension of
; carbon is also known from the United States patent ~,07~,981, the
~; United States patent 40,976 and the German patent 2,130,120.
However, the use of liquid carbon dioxide involves con-
siderable problems relating to temperature. Thus, ~or example,
the temperature of the slurry must be maintained at over 0C to
prevent the precipitation of the water contained in the suspension
o~ carbon in the ~orm of ice. The structural and operational
measures required for maintaining the desired temperature consti-
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tute a heavy economic burden for the production of synthesis gas.
According to the invention the economy of producing
synthesis gas is improved considerably through the admixture of gas
to the suspension of carbon. This admixing is obtained by adding
an ammonium carbonate solution to the suspension of carbon; result~
ing suspension of carbon is mixed with an acid and/ox heated. This
shows that small amounts of ammonium carbonate solution are al-
ready sufficient to improve the flowing properties of the suspen-
sion of carbon considerably.
Phosphoric acid is preferably used as the acid for sett-
ing the carbon dioxide free. In accordance with a further feature
of the invention the freed carbon dioxide comes from the carbon
dioxide wash commonly used in a synthesis gas plant. The carbon
dioxde is washed out or precipitated from the crude gas and
dissol~ed in ammonia water and used as the ammonium carbonate
solution.
The drawing illustrates one embodiment of this in~ention.
In a reactor of a carbon gasification plant a suspension of
carbon is charged from above. This is accomplished with aid of
a pump 2. Oxygen is passed, together with the suspension of
carbon, through a conduit 3 into the reactor 1. The operating
temperature inside the reactor is approximately 1,400C and the
operating pressure is approximately 30 bar.
According to this embodiment, the liquid phase of the
suspension of carbon comprises water. However, if a different
consistency is desired, then oil, or an oil residue, or the like
may be used. The water in the suspension of carbon evaporates
under influence of the heat in the reactor. The carbon reacts
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with the oxygen and the produced water vapoux. This reaction pro-
duces a synthesis gas with a hlgh proportion of carbon monoxide
and free hydrogen. This synthesis gas is an important raw material.
A slag or residue is produced simultaneously with the
synthesis gas, derived from the non-combustible ash materials in
the carbon, especially if the feed material is coal. The slag
gathers predominantly in a water bath at the bottom of the reactor
1 and is discharged into the ambient atmosphere with the aid of a
lock 4, while the operational pressure of 30 bar is main-
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tained.
The lock 4 comprises a container and a valve each at ita inlet
and at its outlet end. ~Ihen the feeding end is open, slag gathers in the
container o~ the lock 4 and sinks through the water ba-th to the bottom of
the reactor 1. ~1hen a certain volume has accumulated in the contQiner, the
valve at the inlet end is closed and the second valve is opened so that the
slag can be removed from the container of the lock 4, without inter~ering
with the operation oP the reactor. Thereupon the valve at the outlet end is
closed again, the lock 4 is Pilled with water and the valve at the inlet end
is opened.
Another portion of the slag produced in the reactor l, being the
portion capable oP being air-borne, is discharged Prom the reactor l together
with the synthesis gas. This gas iæ selectively cooled by means of a waste
heat system, :~orming an integral part of the reactor l. After discharge Prom
the reactor, further cooling may be carried out (not illustrated) before the
crude gas en-ters a device for washing with carbon dioxide. This washing
device 5 comprises two pressure tanks 6 and 7 which are interconnected by
conduits 8 and 9. In the conduit 8 a pump lO is disposed and in the conduit
9 a choke ll. The conduit 8 terminates at either end at, the bottom of the
tank, whereas the conduit 9 terminates at the end ~acing the tank 6 on its
inside, below the level oP the water bath 12. The opposite end of the con-
duit 9 terminates inside the tank 7 above the level of a water bath 13.
The water bath 13 is placed under either the same or a slightly
lower pressure than the inside chamber o~ the reactor l. Due to this pres-
sure, a substantial portion oP the carbon dioxide contained in the crude gas
dissolves in the water. The water enriched with carbon dioxide enters the
tank 7 through -the conduit 9 and the choke ll by virtue oP a considerable
drop in pressure between the -two tanks 6 and 7. The water pressure is
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reduced with the aid o~ the choke 11 to the pressuredesired in-
side the tank 7. After the reduction o~ pressure,the carbon diox-
ide contained in the water bubbles off.
The water accumulating in the tank 7 is removed with the
aid of a pump and returned to the tank 6 through the conduit 8.
The crude gas flowing through the water bath 12 in the
tank 6 is prevented from entering the conduit 9 by maintaining the
level in the water bath 12 above the termination of the conduit 9
in the tank 6. This is achieved with the aid of the choke 11 and/
or the pump 10. Any adjustment to the choke 11 and/or to the pump
10 is effected by means of a non-illustrated float inside the tank
6 which is connected with the choke 11 and/or the pump 10 by means
of a suitable control system.
Any loss in water is compensated from a feeder line 14 by
a slide 15 which functions either automatically, or is hand-operat-
ed at intervals.
The slag washed out from the crude gas, together with
the carbon dioxide, is collected inside a non-illustrated concen-
trator, and is then discharged.
Moreover, precipitation may replace the washing with
carbon dioxide. The precipitation is aimed at merely removing the
carbon dioxide from the crude gas, whereas in the conventional
washing with carbon dioxide usually an undesirable washing out of
other components simultaneously takes place. In the case or pre-
cipitation of the carbon dioxide a base solution is necessary to
be present in the tank 6.
The reaction of the carbon dioxide with the base material
produces a salt which is drawn from the tank 6 and char~edwi~ water
and heated, so that a Free carbon dioxide is produced.
The carbon dioxide gathering in the tank 7 above the
water bath 13 passes through a conduit 16, into which a non-return
valve 17 has been inserted, on to a tank 18. Inside this tank is
concentrated ammonium hydroxide. When the carbon dioxide flows
through the tank 18 and the ammonium hydroxide, a substantial por-
tion of the carbon dloxide is dissolved or is converted into
ammonium carbonate. The ammonium hydroxide containing dissolved
carbon dioxide an ammonium carbonate is drawn off with the aid of
a pump 20 at the bottom of the tank 18 and passed to the carbon
feed 21. The quantity of drawn-off solution is continuously re-
placed through a feeder conduit 22, having a valve 23 inserted
therein and with the aid of a pump 24.
Any carbon enterin~ the carbon feed 21 together with the
ammonium hydroxide containing carbon dioxide as ammonium carbonate
in dissolved form is wet -comminuted in a mill 25. However, the
solution may likewise be added beyond the mill 25 after dry com-
minution. The carbon dioxide is freed again by means of heating
the suspension of carbon and liquid in the conduit to the reactor
1. The ammonium carbonate disintegrates after small quantities of
phosphoric acid have been admi~ed. The necessary dosaging of
phosphoric acid is provided from a conduit 26. To this ef~ect, a
dosing pump is inserted into this conduit. The pump may be either
of the continuous type continuously feeding through a suitable
control valve, or of the intermittently injecting type.
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The carbon dioxide being released in the conduit forms
a multitude of small bubbles which substantially improve the
flowing properties of the suspension of carbon and liquid. Smal:L
bubbles have a slower rising speed than larger bubbles and are
capable of maintaining the admixture of gas substantially stable.
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