Note: Descriptions are shown in the official language in which they were submitted.
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Title
Process and apparatus for briquette production
Technical field
The present invention relates to a process for producing a
briquette containing carbon carriers, wherein the carbon
carriers together with a binder system are subjected to mixing
with the introduction of steam and the mixture obtained is
subjected to pressing to form briquettes.
Prior art
Previously, hard coal briquetting was primarily used to
produce lumpy carbon carriers from fine coal for use as
domestic coal or in industrial grate firing. As a result,
numerous processes for hard coal briquetting are known. Hard
coal briquetting is of great importance for the COREX /FINEXCI
processes for the production of liquid pig iron since these
processes are based on a fixed bed process in which the fixed
bed is created by lumpy carbon.
During this process, which is also known by the technical term
melt-reduction process, lumpy carbon carriers are charged
together with pre-reduced iron carriers and admixtures onto
the fixed-bed surface of a so-called melt-down gasifier. In
the melt-down gasifier, the pre-reduced iron carriers are
completely reduced and a molten pig iron and molten slag
produced, which are obtained from time to time from the run-
off. The heat for the melting process is provided by
gasification of the lumpy carbon carriers by means of oxygen.
The hot gases that form hereby penetrate the fixed bed with
the emission of heat and leave the fixed bed at the fixed-bed
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surface. In countercurrent to the hot gases, molten pig iron
and molten slag percolate the fixed bed and accumulate in its
lowermost region, the so-called sump tank. These processes
require sufficient permeability of the fixed bed which is
determined by the granulation of the lumpy carbon carriers
during charging onto the fixed-bed surface and the particle
stability of the lumpy carbon carriers under the conditions
prevailing on the fixed-bed surface or in the fixed bed.
Therefore, during charging onto the fixed-bed surface, the
granulation of the lumpy carbon carriers should have a
sufficiently high coarse particle content and a limited
content of undersized particles. Suitable granulation for the
charged lumpy carbon carriers established from the raw
material for the carbon carriers by screening must not be
= substantially destroyed during the handling up to the charging
onto the fixed-bed surface due to mechanical stresses. In
addition, the granulation of the lumpy carbon carriers under
the conditions prevailing on the fixed-bed surface or in the
fixed bed must ensure a sufficiently large particle content
and a limited content of undersized particles. The ability of
a lumpy carbon carrier to resist destruction of its
granulation during handling up to the charging onto the fixed-
bed surface is referred to as strength at low temperatures,
the ability of a lumpy carbon carrier to resist destruction of
its granulation under the conditions prevailing on or in the
fixed bed is known as high-temperature resistance.
During the COREXO/FINEX0 process for the production of liquid
pig iron, it is usual to use hard coal as the carbon carrier.
Commercially available hard coal usually only contains 30-70%
coarse particles which can be charged directly as lumpy carbon
carriers. Briquetting is a suitable method to enable
undersized particles also to be used in lumpy carbon carriers.
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Unlike the case with pieces of hard coal with which low-
temperature resistance and high-temperature resistance are
naturally occurring properties, during briquetting, the low-
temperature resistance and high-temperature resistance of the
briquettes containing lumpy carbon carriers can be influenced
by the nature of the process used and the features of the way
it is performed.
US No 6332911, W0200250219, W02004020555, W02005071119,
W09901583 and W02010081620 describe hard-coal briquetting
processes in conjunction with COREKO/FINEKO. These documents
name a plurality of possible binder systems for this purpose,
also including starch and polymers. In the embodiments named,
in each case binders in liquid form are with mixed with the
coal to be briquetted. However, starch and polymers - in
particular PVA -, which are present in solid-granular to
powdery consistency, have to be mixed with high proportions of
water - 1 part of dry binder with at least 10 parts water or
more - to produce a manipulable liquid binder. If insufficient
water is added, it is difficult to achieve a uniform
distribution of the binder in the coal. Slight agglomerations
form. This reduces the binder's binding power which then has
to be compensated by the use of additional binder. However,
this is not desirable for reasons of cost. Although, if the
proportion of water in the binder is increased for this
reason, the binder is better distributed in the coal, this
results in a very wet mixture which cannot be easily
briquetted since, due to its adhesiveness, the wet mixture in
the briquette press feed has a greater tendency toward
bridging and the briquettes therefore often stick in the molds
of the press.
However, the use of the briquettes in COREM/FINEXO processes
for the production of liquid pig iron requires that a
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briauetting process be controlled not only with respect to
optimizing the strength of the briquettes but also with
respect to restricting the moisture in the briquettes before
use for the production of liquid pig iron.
US1121325 also describes the mixing of starch in powder form
with coal with the simultaneous use of steam. However, the
steam first has to be produced in an expensive way which
impairs the economic efficiency of the process.
US3018227A, US4557733A, US1871104A describe steam in the
context of briquette production, but no waste steam from other
steps of the process is added during the step to mix carbon
carriers and binder system.
Summary of the invention
Technical object
It is the object of the present invention to provide a process
and an apparatus for the production of briquettes which also
enables the process to be performed economically when steam is
used for mixing carbon carriers and binder systems.
Technical solution
This object is achieved by a process for the production of a
briquette containing carbon carriers, wherein the carbon
carriers together with a binder system are subject to mixing
with the introduction of steam and the mixture obtained is
subjected to pressing to form briquettes.
The process according to the invention is characterized in
that
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at least one of the steps from the group consisting of
- drying the carbon carriers before mixing,
- setting the temperature of the carbon carriers to be mixed
with the binder system before mixing in a predefined
temperature range,
- heat treatment of the briquettes after pressing,
is carried out,
wherein
- drying the carbon carriers before mixing and/or
- heat treatment of the briquettes after pressing, and/or
- setting the temperature of the carbon carriers to be mixed
with the binder system before mixing in a predefined
temperature range
are carried out by means of direct or indirect interaction
with superheated steam
and waste steam occurring during the interaction is used as at
least part of the steam introduced during mixing.
The carbon carriers are preferably carbon carriers with a
particle size of less than 4 mm, determined by sieve analysis.
In this application, carbon carriers of this kind are also
called fine coal.
Preferably, the carbon carriers comprise coal, particularly
preferably hard coal, quite particularly preferably the carbon
carriers are hard coal. The carbon carriers can also comprise
coke, petroleum coke, carbonaceous dusts, carbonaceous sludges
or consist thereof. It is possible to use a single type of
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carbon carrier, for example a single type of coal or hard
coal, or mixtures of different types of carbon carriers, for
example different types of coal or hard coal. Here, one type
of carbon carrier means, for example, carbon carriers from one
point of origin or carbon carriers of one rank or, for
example, only metallurgical coal or only thermal coal. Here,
different types of carbon carrier should, for example, be
understood to mean carbon carriers from different points of
origin or carbon carriers with different ranks or, for
example, metallurgical coal and thermal coal.
With the process according to the invention, carbon carriers
are processed to form briquettes in that the carbon carriers
are mixed with a binder system with the introduction of steam
and the mixture obtained is pressed to form briquettes.
Due to the use of steam, much higher strengths of the
briquettes are obtained with the same binder system
consumption compared to processes which do not use steam.
The steam - or its properties, which means its quality - added
during mixing influences the properties of the briquettes
obtained - for example by means of the quantity of the water
introduced into the mixture or by means of the quantity of
energy introduced. The quality of the steam with respect to
energy content and water content per quantity unit of steam
can, for example, be set by means of the extent of
superheating in superheated steam or by means of the extent of
condensation in wet steam. To this end, it is possible to mix
steams of different quality. The mixing can also be set with
respect to optimizing the briquette quality by means of the
quantity of the steam added and/or the duration of the
addition.
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The binder system comprises at least one binder and optionally
further substances, for example solvents for the binder. In
this context, a binder is a substance by means of which solids
with a fine degree of dispersion, for example powders, are
bonded to one another.
In one embodiment, the binders are poorly water-soluble
substances; a poorly water-soluble substance should be
understood to be a substance which requires a weight
percentage ratio of water to binder of equal to or greater
than 5 to 1 for complete dissolution at 20 C.
Binders are for example starch or polyvinyl acetate, PVA. It
is, for example, possible to use starch dissolved in water as
the binder system.
With the process according to the invention, at least one of
the steps from the group of steps consisting of
- drying the carbon carriers before mixing,
- setting the temperature of the carbon carriers to be mixed
with the binder system before mixing in a predefined
temperature range,
- heat treatment of the briquettes after pressing,
is carried out.
If the carbon carriers contain too much moisture to produce
briquettes with acceptable moisture, according to the
invention they are dried before mixing with the binder system
takes place. Preferably, the moisture has a water content less
than or equal to 7 percent by mass, particularly preferably
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the moisture has a water content of less than or equal to 5
percent by mass.
Setting the temperature of the carbon carriers to be mixed
with the binder system enables the strength properties of the
briquettes to be influenced. Therefore, according to the
invention, optionally before mixing, the temperature of the
carbon carriers to be mixed with the binder system is set in a
predefined - selected with respect to the desired strength
properties - temperature range.
The temperature of the carbon carriers initially determines
the quantity of heat which has to be supplied with the steam
in order to set the desired temperature for mixing the binder
system with the carbon carriers. Depending upon how much
energy is withdrawn from the steam by heating the carbon
carriers, condensation takes place to varying degrees. If the
moisture of the mixture, which is, for example, changed by
this condensation, is in an adequate ratio to the quantity of
binder system used, the strength of the briquettes is
influenced favorably.
According to the invention, optionally a heat treatment - for
example heating up- which can take place in one or more stages
- of the briquettes is performed after pressing. The heat
treatment can influence the strength properties of the
briquettes in the sense of hardening.
According to the invention, at least one of the process steps
- drying the carbon carriers before mixing,
- heat treatment of the briquettes after pressing,
- setting the temperature of the carbon carriers to be mixed
with the binder system before mixing in a predefined
temperature range,
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is carried by means of direct or indirect interaction with
superheated steam.
In the case of direct interaction, the superheated steam and
the carbon carriers or briquette are in physical contact,
wherein heat transmission takes place.
In the case of indirect interaction, the superheated steam and
the carbon carriers or briquette are not in physical contact;
heat transmission takes place through a wall, for example.
After completion one more of the tasks
- drying the carbon carriers before mixing,
- heat treatment of the briquettes after pressing,
- setting the temperature of the carbon carriers to be mixed
with the binder system before mixing in a predefined
temperature range,
the superheated steam causes a so-called waste steam with a
lower temperature than the superheated steam to form.
The mixing can be performed with batchwise material feed or
continuous material feed.
Heat treatment should be understood to mean heat input, that
is heating, but not heat removal, that is cooling.
Advantageous impacts of the invention
According to the invention, waste steam that occurs during
direct or indirect interaction is used as at least part of the
steam introduced during mixing. All or a part of the waste
steam that occurs can be used in this way. This increases the
economic efficiency of the process since the waste steam is
used energetically and materially for heating and as a solvent
for the binder system during mixing.
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=
According to a preferred embodiment, with the process
according to the invention, the binder system is mixed with
the carbon carriers in solid state, preferably dry. This
enables the binder system to be mixed more effectively with
the carbon carriers than would be the case if, for example, a
viscous binder system were used.
According to a further embodiment, the binder system is mixed
with the carbon carriers in liquid state; this is in
particular the case with liquid binder systems.
According to a further embodiment, the binder system is mixed
with the carbon carriers in a first mixing step to folm a
premix and the premix is subjected to a second mixing step
with the introduction of the steam. The steam then arrives at
an already extensively homogenized mixture of carbon carriers
and binder system.
In this case, according to a further embodiment, the inlet
temperature of the premix is set in a predefined temperature
range on entry into the second mixing step. This again enables
the properties of the briquettes obtained to be influenced, as
already discussed above.
In this case, according to a further embodiment the inlet
temperature of the premix is set by setting the temperature of
the carbon carriers supplied to the first mixing step in a
predefined temperature interval. Then, the premix does not
have to be additionally heated in the mixing apparatus in
which it is produced thus resulting in reduced complexity of
the equipment.
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According to a further embodiment, the second mixing step is
regulated and/or controlled by changing at least one of the
parameters from the group consisting of the members
- quantity - with batchwise operation -, for example in kg, or
mass flow - with continuous operation -, for example in kg/
time unit, of the carbon carriers,
- inlet temperature of the carbon carriers from the first
mixing step or inlet temperature of the premix in the second
mixing step,
- inlet moisture of the carbon carriers from the first mixing
step or inlet moisture of the premix,
- quantity of the added steam based on the quantity of the
carbon carriers,
- pressure and/or temperature of the added steam,
- water addition, preferably in a desired ratio to the
quantity of the carbon carriers in the second mixing step,
- quantity of steam - with batchwise operation -, for example
in kg, or steam mass flow - with continuous operation -, for
example in kg/time unit,
- duration of the addition of the steam, preferably a duration
of 0.5 to 30 min, particularly preferably 2 to 7 min. The
quantity of the added steam based on the quantity of the
carbon carriers in the second mixing step is preferably
regulated by one of the following parameters:
- quantity of steam - with batchwise operation -, for example
in kg,
- steam mass flow - with continuous operation -, for example
in kg/time unit,
- duration of the addition of the steam - with batchwise
operation -, preferably a duration of 0.5 to 30 min,
particularly preferably 2 to 7 min.
- with continuous operation dwell time of the steam and/or the
premix in the second mixing step.
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If, with batchwise operation, the quantity of the added steam
based on the quantity of the carbon carriers in the second
mixing step is regulated for the duration of the addition of
the steam, this obviously requires the prevailing steam mass
flow in this time to be known.
According to a further embodiment, with at least one member of
the group consisting of the members
- setting the inlet temperature of the premix on entry into
the second mixing step in a predefined temperature range,
- setting the inlet temperature of the premix by setting the
temperature of the carbon carriers supplied to the first
mixing step in a predefined temperature interval,
direct or indirect interaction with steam takes place.
Preferably, superheated steam is used in this case.
According to a further embodiment, waste steam that occurs
during this interaction is used as at least part of the steam
introduced during mixing. This has the advantage that it is
returned materially and energetically to the process.
Advantageously, the binder system contains starch. Starch is
cheap and easily available and not harmful to the environment.
According to a further embodiment, the binder system contains
at least one component from the group consisting of the
members
- synthetic polymers,
- monomers polymerized under the conditions of the second
mixing step to form synthetic polymers,
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- monomers polymerized under the conditions of the drying of
the briquettes obtained during the pressing to form synthetic
polymers.
Synthetic polymers should, for example, be understood to mean:
- styrene-butadiene mixed polymers,
- acrylates,
- thermoplastics and synthetic resins, such as for example
o polystyrene,
o polyethylene,
o polyvinyl alcohol,
o polyethylene wax,
o phenolic resin,
o xylene-formaldehyde resin,
- polyurethanes such as for example
=
o polyether
o polyisocyanates
The binder system preferably contains polyvinyl acetate.
Polyvinyl acetate is easily obtained and available in large
quantities and, for example as claimed in claim 12, can be
produced during the course of a process for the production of
pig iron.
According to a further embodiment, components that increase
the heat resistance of briquettes are added to the carbon
carriers in a quantity of 1 to up to 10 percent by mass, based
on the mass of the supplied for mixing. This can, for example,
involve bitumens in granular form or as spray droplets,
dusts/sludge from metallurgical processes or coal with a
higher heat resistance than the carbon carriers.
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According to a further embodiment of the process according to
the invention before being subject to pressing to form
briquettes, the mixture is subjected to pre-agglomeration. The
pressing of the pre-agglomerated mixture achieves advantages
with respect to the properties of the briquettes, especially a
higher density, resulting in more solid briquettes.
A further subject matter of the present application is the use
of briquettes produced using the process according to the
invention in a process for the production of pig iron with
gasification of the carbon carriers. Preferably, waste heat
that occurs during the process for the production of pig iron
with gasification of the carbon carriers is used to produce at
least part of a steam used in the process according to the
invention.
A further subject matter of the present application is a
process with which the binder system contains polyvinyl
acetate, wherein the polyvinyl acetate is at least partially
produced from monomers, which are obtained by means of a
synthesis gas, which is based on export gas that occurs during
the process according to the invention for the production of
pig iron with gasification of the carbon carriers, with
conversion of CO of the synthesis gas via acetic acid into
vinyl acetate.
A further subject matter of the present application is an
apparatus,
suitable for carrying out a process according to the invention
with a mixing mechanism for mixing carbon carriers with a
binder system
and with a pressing mechanism for pressing briquettes on the
basis of a mixture obtained from the mixing mechanism,
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wherein the mixing mechanism comprises a steam supply conduit
for supplying steam,
characterized in
that at least one member of the group consisting of
- dryer for drying carbon carriers,
- heat treatment apparatus for heat treatment of the
briquettes,
- apparatus for changing the temperature of the carbon
carriers before entry into the mixing mechanism
is present,
wherein
- the dryer, and/or
- the apparatus for changing the temperature of the carbon
carriers before entry into the mixing mechanism, and/or
- the heat treatment apparatus for heat treatment of the
briquettes,
is an apparatus for direct or indirect interaction with steam
into which a steam-feeder conduit for feeding steam opens and
from which the waste-steam conduit leads,
and wherein the waste-steam conduit opens into the steam
supply conduit and/or in the mixing mechanism.
If in
- the dryer, and/or
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- the apparatus for changing the temperature of the carbon
carriers before entry into the mixing mechanism, and/or
- the heat treatment apparatus for heat treatment of the
briquettes,
the pressure is higher than that of the environment, pressure-
equalizing locks for the materials contain in the respective
units - for example carbon carriers, mixture, briquettes - are
installed before and after the respective unit.
For example, pressure-equalizing locks are installed for the
briquettes if the pressure in the heat treatment apparatus for
heat treatment of the briquettes is higher than that of the
environment.
The mixing mechanism can be operated batchwise or
continuously.
The apparatus for changing the temperature of the carbon
carriers before entry into the mixing mechanism can, for
example, be embodied as a heatable chamber.
According to a preferred embodiment, the dryer is the
apparatus for changing the temperature of the carbon carriers
before entry into the mixing mechanism. This reduces the
complexity of the equipment, the amount of maintenance and
capital expenditure and operating costs.
The heat treatment apparatus for heat treatment of the
briquettes can, for example, be embodied as a heatable
chamber.
In one embodiment, a carbon-carrier store is provided from
which a carbon-carrier output conduit opens into the dryer.
Preferably, the carbon-carrier store is provided with an
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apparatus for changing the temperature of carbon carriers in
the carbon-carrier store. This means that no extra unit is
required for changing the temperature of the carbon carriers.
Preferably, the mixing mechanism comprises
- a premixing unit for carrying out a first mixing step,
- a binder supply conduit opening into the premixing unit for
adding a binder system to the premixing unit,
- a carbon-carrier-supply conduit opening into the premixing
unit for supplying carbon carriers, preferably carbon carriers
from the dryer, to the premixing unit,
- a final mixing unit for carrying out a second mixing step,
into which the steam supply conduit opens.
Preferably, the premixing unit comprises an apparatus for
changing the temperature of premix in the premixing unit; for
example heating elements through which steam or thermal oil
flow or electrical heating elements.
Preferably, an apparatus for regulating and/or controlling the
quantity of steam
per time unit
and/or
per quantity unit of material to be briquetted
to be introduced into the final mixing unit is provided. This
can increase the efficiency of the process according to the
invention in that the treatment conditions are optimized to
the mixture to be briquetted.
Preferably, at least one member of the group consisting of the
members
- apparatus for changing the temperature of premix in the
premixing unit,
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- apparatus for changing the temperature of carbon carriers in
the carbon-carrier store,
is an apparatus for direct or indirect interaction with steam,
into which a steam feeder conduit for feeding steam opens.
This enables changes to the temperature to be made with the
aid of steam.
In some embodiments, the waste-steam conduit opens into the
steam supply conduit and/or in the mixing mechanism.
According to a further embodiment, the waste-steam conduit
opens into the final mixing unit.
In some embodiments, the premixing unit and final mixing unit
are combined in one piece of equipment in the mixing
mechanism. This reduces the complexity of the equipment, the
amount of maintenance and capital expenditure and operating
costs.
According to a further embodiment, the apparatus according to
the invention also comprises an apparatus for the pre-
agglomeration of the mixture produced in the mixing mechanism.
This is then connected via a mixture feed conduit to the
mixing mechanism and to pre-agglomerate discharge conduit with
the pressing mechanism for pressing briquettes. Optionally,
the mixture produced in the mixing mechanism is kneaded before
being introduced into the apparatus for pre-agglomeration in
an optionally provided kneader. This improves the consistency
of the mixture for the briquetting process compared to the
state following the mixing mechanism.
For the purposes of the present application, the word steam
always means water vapor.
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Short description of the drawings
In the following, the present invention is described with
reference to some exemplary schematic figures.
Fig. 1 is a schematic representation of an apparatus according
to the invention.
Fig. 2 is a schematic view of the use of briquettes produced
according to the invention in a process for the production of
pig iron with gasification of the carbon carriers and the use
of the export gas formed for the production of polyvinyl
acetate.
Description of the embodiments
Fig. 1 shows an apparatus according to the invention with a
mixing mechanism 1 for mixing carbon carriers 2 with a binder
= system 3. The apparatus also comprises a pressing mechanism 4
for pressing briquettes on the basis of a mixture obtained
from the mixing mechanism 1. The mixing mechanism 1 has a
steam supply conduit 5 for supplying steam. Also provided are
a dryer 6 for drying the carbon carriers 2 and a heat
treatment apparatus 7 for heat treatment of the briquettes.
The dryer 6 is an apparatus for indirect interaction with
steam and the heat treatment apparatus 7 for heat treatment of
the briquettes is an apparatus for direct interaction with
steam; a steam-feeder conduit 8a, 8b for feeding steam opens
into both apparatuses and a waste-steam conduit 9a, 9b leads
from both apparatuses, wherein the waste-steam conduit 9a
opens into the steam supply conduit 5 and the waste-steam
conduit 9b opens into the mixing mechanism 1.
The carbon carriers 2, in this case a mixture of fine coals of
different origin and different granulation, are subjected to
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mixing with the introduction of steam in the mixing mechanism
1 with a binder system 3, in this case starch powder. The
mixture obtained thereby is then subjected to pressing to form
briquettes in the pressing mechanism 4. The drying in the
dryer 6 is performed to a water content of less than or equal
to 7 percent by mass. The drying of the carbon carriers before
mixing and the heat treatment of the briquettes after pressing
is performed by means of superheated steam supplied via steam
feeder conduits 8a, 8b. The waste steam that occurs thereby is
introduced into the steam supply conduit 5 via the waste-steam
conduit 9a and into the mixing mechanism 1 via the waste-steam
conduit 9b where it is a part of the steam introduced during
mixing.
The mixing mechanism 1 comprises a premixing unit 10 for
carrying out a first mixing step, and a final mixing unit 11
for carrying out a second mixing step. In the mixing mechanism
1, premixing unit 10 and final mixing unit 11 are combined in
one piece of equipment. A binder supply conduit 12 for the
addition of the binder system 3 to the premixing unit 10 opens
into the premixing unit 10. A carbon-carrier supply conduit 13
for supplying carbon carriers 3 from the dryer 6 to the
premixing unit 10 also opens into the premixing unit 10. The
steam supply conduit 5 opens into the final mixing unit 11. In
a first mixing step, the binder system 3 is mixed with the
carbon carriers 2 in the premixing unit 10 to form a premix
and the premix is subjected to a second mixing step in the
final mixing unit 11 with the introduction of the steam via
the steam supply conduit 5. The steam supply conduit 5
contains an apparatus 14 for regulating and/or controlling the
quantity of steam to be introduced into the final mixing unit
per time unit and/or per quantity unit of material to be
briquetted. This enables the regulation and/or control of the
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second mixing step by changing at least one of the parameters
from the group consisting of the members
- quantity - with batchwise operation -, for example in kg, or
mass flow - with continuous operation -, for example in kg/
time unit, of the carbon carriers,
- inlet temperature of the carbon carriers from the first
mixing step or inlet temperature of the premix in the second
mixing step,
- inlet moisture of the carbon carriers from the first mixing
step or inlet moisture of the premix,
- quantity of the added steam based on the quantity of the
carbon carriers,
- pressure and/or temperature of the added steam,
- water addition, preferably in a desired ratio to the
quantity of the carbon carriers in the second mixing step,
- quantity of steam - with batchwise operation -, for example
in kg, or steam mass flow - with continuous operation -, for
example in kg/time unit,
- duration of the addition of the steam, preferably a duration
of 0.5 to 30 min, particularly preferably 2 to 7 min.
Apparatuses of this kind for regulation and/or control are
also provided in the waste-steam conduits 9a, 9b, but these
are not shown for reasons of clarity.
The dryer 6 is simultaneously an apparatus for changing the
temperature of the carbon carriers before entry into the
mixing mechanism. This dryer 6 can be used to set the inlet
temperature of the premix on entry into the second mixing step
in a predefined temperature range by setting the temperature
of the carbon carriers 3 supplied to the first mixing step in
a predefined temperature interval. In addition thereto, the
inlet temperature of the premix on entry into the second
mixing step can be set in a predefined temperature range by an
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apparatus 15 belonging to the premixing unit for changing the
temperature of premix in the premixing unit. The settings of
the inlet temperature of the premix on entry into the second
mixing step are performed by means of indirect interaction
with steam. Waste steam that occurs during an interaction of
this kind can be used as a component of the steam supplied to
the final mixing unit 11, although, this and a steam feeder
conduit for feeding steam to the apparatus 15 is not shown
additionally reasons of clarity.
The carbon carriers 2 are conducted from a carbon-carrier
store 16, in which they are stored prior to being supplied to
the mixer 6 into the dryer via a carbon-carrier output conduit
17. The carbon-carrier store 16 is provided with an apparatus
18 for changing the temperature Of carbon carriers 2 in the
carbon-carrier store. This apparatus 18 is also an apparatus
for indirect interaction with steam, into which a steam feeder
conduit, which is not additionally shown for reasons of
clarity, for feeding steam opens.
Before pressing briquettes, pre-agglomeration can be performed
by means of an apparatus 28 for pre-agglomeration of the
mixture in the mixing mechanism 1. Optionally, before
introduction into the apparatus 28 for pre-agglomeration, the
mixture produced in the mixing mechanism 1 is kneaded in an
optionally provided kneader 29.
The briquettes produced according to the invention are used in
a process for the production of pig iron with gasification of
the carbon carriers; Fig. 2 shows this schematically for a
COREM process. Briquettes taken from the heat treatment
apparatus 7, in which briquettes are hardened, are supplied to
a coal bunker 19, to which lump coal 20 is also added. From
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the coal bunker 19, this material is supplied to a melt-down
gasifier 21. Iron carriers are also added thereto; liquid pig
iron is obtained by under gasification inter alia of the
carbon carriers. Heat can be extracted from the so-called
generator gas withdrawn from the melt-down gasifier 21 by
means of a heat exchanger 22 for the purpose of producing at
least part of the steam used in the process according to the
invention. After treatment, the generator gas is used as
reduction gas in a dust-removal mechanism in the reduction
unit 23, which is not additionally shown for reasons of
clarity, in which the iron carriers intended to be input into
the melt-down gasifier are generated. After flowing through
the reduction unit 23, so-called top gas 24 can be withdrawn
from the reduction unit 23. Once again, heat can be withdrawn
from this, for example by means of a heat exchanger 25, in
order to produce at least part of the steam used in the
= process according to the invention. Fig. 2 shows how, after
passing through the heat exchanger 25, the cooled top gas -
optionally after further treatment steps, which are not shown
- can be used export gas 26 in a binder factory 27 for the
production of binders for a binder system used according to
the invention. In this case, a synthesis gas rich in carbon
monoxide is produced from the export gas and converted via
= acetic acid and vinyl acetate to produce polyvinyl acetate.
Although the invention has been illustrated and described in
greater detail by the preferred exemplary embodiment, the
invention is not restricted by the disclosed examples and
other variations can be derived herefrom by the person skilled
in the art without departing from the scope of the invention.
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201208232
List of reference numbers
1 Mixing mechanism
2 Carbon carriers
3 Binder system
4 Pressing mechanism
Steam supply conduit
6 Dryer
7 Heat treatment apparatus
8a, 8b Steam-feeder conduit
9a, 9b Waste-steam conduit
Premixing unit
11 Final mixing unit
12 Binder supply conduit
13 Carbon-carrier supply conduit
14 Apparatus for regulating and/or
controlling the quantity of steam that can
be introduced into the final mixing unit
per time unit and/or per quantity unit of
material to be briquetted
Apparatus for changing the temperature of
premix in the premixing unit
16 Carbon-carrier store
17 Carbon-carrier output conduit
18 Apparatus for changing the temperature of
carbon carriers in the carbon-carrier
store
19 Coal bunker
Lump coal
21 Melt-down gasifier
22 Heat exchanger
23 Reduction unit
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24 Top gas
25 Heat exchanger
26 Export gas
27 Binder factory
28 Apparatus for pre-agglomeration
29 Kneader
