Note: Descriptions are shown in the official language in which they were submitted.
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DEVICE AND METHOD FOR THE THERMOCHEMICAL CARBONIZATION AND
GASIFICATION OF WET BIOMASS
The invention relates to a device for the thermochemical carbonization and
gasification of wet,
especially water-containing and/or dry, biomass for producing an energy
carrier and/or raw-material
carrier by means of a heatable carbonization reactor having a closable inlet,
in which the biomass is
converted into a solid, pourable or gaseous energy carrier and/or raw-material
carrier and is
discharged via a closable outlet to a coolable vessel connected to the
carbonization reactor for
interim storage of the energy canier and/or raw-material carrier, which is
connected to a
downstream gasification reactor, in which gas and waste substances, such as
ash, are separated from
the biomass.
Biomass gasification is generally known. This is understood as a process in
which biomass is
converted into a product gas or combustible gas by means of a gasifying or
oxidizing agent
(generally air, oxygen, carbon dioxide or steam) by partial combustion.
Through gasification, the biomass that is in the form of solid fuel can be
converted into a gaseous
secondary fuel, which can be used more efficiently in various usage options,
e.g. production of
electricity or as fuel and propellant (combustible gas) or for use as
synthesis gas for chemical
synthesis. Analogous processes also exist for other solid fuels, especially
for the gasification of coal
(coal gasification).
The gasification of biomass starts after drying at temperatures of approx. 150
C, with steam and
oxygen being evolved first. At higher temperatures, the solid constituents of
the biomass are burnt.
This gas ignites as soon as secondary air is supplied; the flash point is from
230 to 280 C.
Industrial biomass gasification is partial combustion by means of a gasifying
or oxidizing agent
(generally air, oxygen, carbon dioxide or steam) without ignition at
temperatures from 700 to 900 C,
in which it is not oxidized to carbon dioxide (CO2), as in combustion, but
essentially to carbon
monoxide (CO). Further components of the resultant gas are hydrogen (H2),
carbon dioxide (CO2),
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methane (CH4), steam (FLO) and a number of trace gases and impurities,
depending on the biomass
used. A solid residue is left (ash and coke); moreover, some fractions of the
product gas may
condense out as the temperature is lowered (tar and water).
The combustible product gas can be oxidized further in a downstream process by
combustion
(combustible gas) or a chemical synthesis (synthesis gas) with release of
energy (exothermic
process). If the gasification takes place with air, the resultant product gas
diluted with nitrogen is
often also called lean gas (LCV, low calorific value gas).
Hydrothermal carbonization (for instance: "aqueous carbonization at elevated
temperature") is a
chemical process for simple and highly efficient production of lignite,
synthesis gas, liquid
petroleum precursors and humus from biomass with release of energy. In a few
hours, the process
technically duplicates the formation of lignite ("coalification") that occurs
in nature in 50 000 to 50
million years.
The currently known working process is as follows: biomass, especially plant
material, (for
simplicity represented as sugar, with the formula C611206. in the following
reaction equation) is
heated to 180 C together with water in an isochoric process in a pressure
vessel. The pressure may
increase to 2 MPa. During the reaction, oxonium ions are also formed, which
lower the pH to pH 5
or lower. In this process, the carbons pass into an aqueous phase and so are
lost. This energy is no
longer available for the working process. This step can be accelerated by
adding a small amount of
citric acid. It must be borne in mind that at low values of pH, more carbon
passes into the aqueous
phase. The reaction taking place is exothermic, i.e. energy is released. After
12 hours, the carbon of
the educts has been converted completely: 90 to 99% of the carbon is in the
form of solid phase as
an aqueous sludge of porous lignite beads (C6H20) with pore sizes between 8
and 20 nm; the
remaining 1 to 10% of the carbon is either dissolved in the aqueous phase or
has been converted to
carbon dioxide. The reaction equation for the formation of lignite is:
C6H1206 C6FLO +5 H,0 AH = -1.105 kJ/mol
The reaction can be terminated in several stages with incomplete water
cleavage, obtaining different
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intermediates. With termination after a fevs, minutes there is formation of
liquid intermediates,
lipophilic substances, but their manipulation is very difficult on account of
their high reactivity.
Next, these substances polymerize and peat-like structures form, which after
approx. 8 hours are
available as intermediates.
Theoretically the reaction could be catalyzed with certain metal particles,
but these would very
quickly add onto the products and lose their function.
Owing to the exothermic reaction of hydrothermal carbonization, about 3/8 of
the calorific value of
the biomass based on the dry matter is released (with high content of lignin,
resin and/or oil, still at
least 1/4). With skillful process control it could be possible, by means of
this waste heat, to produce
dry biocoal from wet biomass and optionally use some of the converted energy
for power
generation.
The most important aspect is that a simple method is made available for
converting atmospheric CO,
indirectly via biomass into a stable, harmless storage form, a carbon sink.
Using the method of
hydrothermal carbonization, as with other methods of carbonization of biomass,
decentralized
permanent storage of a large amount of carbon throughout the world would thus
be possible. This
would be much safer than the liquid or gaseous sequestration of carbon dioxide
currently being
discussed. With adequate chemical stability of the coal, it could also be used
very well for soil
improvement.
The artificially produced humus could be utilized for the revegetation of
eroded areas. Through this
intensified plant growth, additional carbon dioxide could be bound from the
atmosphere, so that the
final effect would be achievement of a carbon efficiency above 1 or a negative
CO, balance. The
resultant coal slurry could be used for combustion or for operating novel
types of fuel cells with an
efficiency of 60%, which are currently under investigation at Harvard
University. For the production
of conventional fuels, the carbon/water mixture would first have to be heated
strongly, so that so-
called synthesis gas, a gas mixture of carbon monoxide and hydrogen, is
formed:
C6H20 + 5 H20 ¨ 6 CO + 6 H,
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Alternatively the liquid intermediates that form during incomplete reaction of
the biomass could be
used for producing Weis and plastics.
In addition, the resultant coal slurry could be briquetted and marketed as an
environment-friendly ¨
because it is carbon dioxide¨neutral ¨ "natural coal", which, in comparison
with the starting
biomass, it should be possible by means of separation/filtration/compaction to
dry with lower energy
consumption and owing to its higher energy content per volume/mass would incur
lower transport
costs and would require less storage area.
The main problem when producing synthesis gas from biomass is tar formation,
which can largely
be avoided in a hydrothermal process. However, it is not then apparent why the
indirect route via
biocoal should be followed for this. Under supercritical conditions, at 400 C
and a pressure of at
least 221.2 bar (the critical temperature of water is 374 C), it should be
possible to break down a
biomass slurry into CO2 and 112, but this requires a high energy input.
Problems still to be solved are suitable process control, and problems in the
collection, transport and
storage of the biomass in question. These operations also require energy ¨
this should be less than is
released by hydrothermal carbonization.
Finally, every biomass combustion process is preceded by a gasification
process, as the biomass
itself is not combustible ¨ basically it is only the vases produced from the
biomass that are
combustible.
In the carbonization of biomass corresponding to the state of the art, such as
hydrothermal
carbonization HTC in an aqueous or steam environment, additionally water or
steam is supplied to
the reactor from outside. This means considerable additional costs for
construction and operation of
the carbonizing plant. 'Thermal energy is required for providing the water or
the steam and for
heating the water. Utilization or disposal of the process water after
carbonization represents an
additional operation, involving considerable technical and financial costs.
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In the known processes, gases and vapors are formed. These often represent an
additional problem,
which must be solved with technical measures and with considerable additional
costs.
The problem to be solved by the invention is to obtain more or less all the
carbon and gases from the
biomass and to produce these simply and economically.
This problem is solved according to the invention by
a) supplying external thermal energy to the carbonization reactor, which is
connected operatively to
a heating element, in particular is surrounded by a heating jacket, and
supplying further thermal
energy at least from one plant, especially from the gasification reactor,
b) supplying cooling energy from the second vessel or cooling vessel to the
gasification reactor,
c) supplying moisture, especially water, to the second vessel or cooling
vessel, to ensure an almost
continuous process,
d) from the carbonization reactor and/or the second vessel or cooling vessel,
supplying reaction gas
to a gas storage tank, wherein the reaction gas is recycled to the
gasification reactor.
In this way, carbon, especially coal, for heating and for driving units and
moreover also gases are
obtained from biomass in a simple, economical and energy-saving manner with
equipment that is
easy to set up, for use by various consumers, such as gas engines, gas
turbines and heating
installations.
The method according to the invention preferably uses water-containing
biomass, which mainly
arises as municipal waste and in many cases must be disposed of at great
expense. In this method it
is, however, also possible to use other biomass. which does not have to be
disposed of as residue.
At least two reactors are used for implementing the method. These are on the
one hand the
carbonization reactor and on the other hand the gasification reactor.
In contrast, in the method described here, the energy required for evaporation
is provided by
utilizing heat that is released during cooling of the reactor gas produced.
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Owing to the gasification operation, preceded by carbonization of the biomass,
reactor gas produced
by the method according to the invention is almost completely free from tar or
tar-forming
constituents. This is in particular also achieved because the manner in which
the process is managed
means that the volatile, incombustible fractions from the biomass can be
lowered from the existing
80% to approx. 30%, cf. Tables 1 and 2. The values for an installation of the
prior art are given in
Table 1 and for the equipment according to the invention in Table 2.
After it leaves the gasification reactor, the reactor gas is cleaned by dust
separation to remove solid
particles, e.g. fine dust, and can then be utilized for producing power and
heat.
The small proportion of additional water or heating steam means that only very
little process water
is produced. No additional costs arise for wastewater treatment or wastewater
disposal either, as the
water supplied is evaporated in the plant.
The plant can be employed on a small industrial scale using gas-engine
generator sets with heat
utilization for supplying limited local areas of settlements with power and
heat and in parallel for the
disposal of suitable municipal wastes.
In the method according to the invention, the problem of contamination of the
gases and of tar
formation is also solved in that there is almost complete internal disposal of
critical reaction
products in gaseous and vapor form through combustion in the gasification
reactor.
This leads to avoidance of CO2, wherein in this case only a small part of the
possible energy would
be free.
One advantage of hydrothermal carbonization is that the usable plant biomass
is not restricted to
plants with low moisture contents and the energy obtainable without carbon
dioxide emissions is not
reduced by the drying steps required or if necessary is directly usable for
drying the end products.
Thus, even previously barely usable plant material such as clippings and
prunings from gardens and
from green areas in towns can be used for energy production, at the same time
with a saving of
carbon dioxide, which otherwise would be formed ¨ together with the even more
climate-damaging
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methane ¨ during bacterial transformation of the biomass. The operation of the
complete plant is
-I so energy-saving because almost all the thermal energy released is recycled
to the working
process.
' For this it is advantageous that the moisture-containing biomass received in
the carbonization
reactor is evaporated at pressures between 5 and 30 bar, preferably at
pressures between 15 and 25
bar, especially at pressures of about 20 bar and at temperatures between 200
and 1200 C,
preferably between 400 and 800 C, and reaction gas is formed, which is
supplied directly or
indirectly to the gasification reactor via a line.
It is also advantageous that the gasification reactor operates in a
temperature range between 12000
and 1800 C, preferably between 1000 and 1400 C, and during the working
process releases
thermal energy via a line connecting the gasification reactor and the
carbonization reactor.
According to a development of the invention, an additional possibility is that
a cyclone separator
and/or gas scrubber is connected via a line to the gasification reactor,
wherein a heat exchanger can
be provided between the cyclone separator and/or gas scrubber, which lowers
gas to the working
temperature of the heat exchanger between 40 C and 80 C or between 50 C and 60
C and recycles
the resultant abstracted energy to a heating system and/or to the working
process of the plant. The
thermal energy released from the heat exchanger is supplied via a line to a
consumer, such as a
heating system.
Furthermore, it is advantageous that the harmful substances or impurities
released in the
carbonization reactor and/or in the second vessel or buffer tank are destroyed
or at least partially
destroyed by means of a thermal device or are led away.
It is also advantageous that the device for the thermochemical carbonization
and gasification of wet,
especially water-containing and/or dry, biomass for producing an energy
carrier and/or raw-material
carrier by means of a heatable carbonization reactor having a closable inlet,
in which the biomass is
converted into a solid, pourable or gaseous energy carrier and/or raw-material
carrier and is
discharged via a closable outlet to a coolable vessel connected to the
carbonization reactor for
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interim storage of the energy carrier and/or raw-material carrier, which is
connected to a
downstream gasification reactor, in which gas and waste substances, such as
ash, are separated from
the biomass, is characterized by the following features:
a) the thermochemical carbonization and gasification device or the first
vessel of wet, especially
water-containing and/or dry, biomass is connected via a closable connection to
a second vessel or
buffer tank;
b) the first vessel and/or the second vessel or buffer tank are in each case
connected via a line to a
gas storage tank, especially reaction gas storage tank;
c) the reaction gas storage tank is connected via the line to the gasification
reactor;
d) the gasification reactor is connected directly or indirectly to a cleaning
device, such as a cyclone
separator and/or gas scrubber;
e) the thermal energy obtained or energy released in the gasification reactor
is supplied via at least
one line for process control of the thermochemical carbonization and
gasification device or to the
first vessel.
It is advantageous that the gasification reactor is connected via a line to a
processing device for
treatment and/or further processing of the coal obtained in the gasification
reactor.
It is especially important for the present invention that the second vessel
and/or the gasification
reactor is connected via the line to the processing device for treatment or
further processing of the
coal obtained in the vessel and/or in the gasification reactor and a spun-
bonded fabric or a ribbon
fabric is used as carrying layer.
It is also advantageous that saturated steam is obtained in the gasification
reactor, which is
connected via a line conveying saturated steam to a consumer or to a heating
system and/or a steam
piston engine.
Moreover, it is advantageous that the gasification reactor is connected via at
least one line to a
consumer or at least to a gas compressor and/or gas engine.
:30
It is also advantageous that the gasification reactor and/or the second vessel
can be cooled by means
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of a cooling device, or in each case is surrounded by a cooling jacket and the
cooling device is fed
with cooling water, wherein at least also cooling water from the cooling
jacket of the second vessel
supplied via a line to the gasification reactor.
Furthermore, it is advantageous that the method is characterized by the
following method steps:
a) the biomass is converted in a carbonization reactor by means of external
thermal energy and
further thermal energy, which is supplied from the plant to the carbonization
reactor, into a solid,
pourable or gaseous energy carrier and/or raw-material carrier;
b) the gas formed in the carbonization reactor is received in a reaction gas
storage tank;
c) the reaction gas obtained or present in the first and second vessel is
supplied directly or indirectly
to the gasification reactor;
d) at least a proportion of the energy obtained in the method of
thermochemical carbonization and
gasification of wet, especially water-containing and/or dry, biomass is
recycled to the processing
process, especially to the vessel;
e) the coal obtained in the gasification reactor is supplied to a further
processing device;
f) the cooling energy fed in the second vessel is supplied simultaneously or
subsequently to the
cooling jacket of the gasification reactor;
g) the released energy produced in the gasification reactor or the saturated
steam is supplied to one
or more consumers, such as a heating system, and/or to a steam piston engine.
According to a development of the invention, an additional possibility is that
the reaction gas
produced in the complete plant or in the first vessel is supplied directly or
indirectly to a cyclone
separator and/or to a gas scrubber, then to a dehumidifier, or directly or
indirectly via a compressor
to the consumer.
It is also advantageous that in one or more lines, control valves are
provided, which can be turned
off or on manually or by a drive device, wherein the drive devices can be
controlled via a computer
in relation to the working process.
Further advantages and details of the invention are explained in the patent
claims and in the
description and are shown in the drawings, showing:
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Fig. 1 the flowsheet for a device for thermochemical carbonization and
gasification of wet,
especially water-containing and/or dry, biomass for producing an energy
carrier and/or raw-material
carrier by means of a heatable carbonization reactor that has a closable
inlet, in which the biomass is
converted into a solid, pourable or gaseous energy carrier and/or raw-material
carrier;
5
Fig. 2 a general view of a device for thermochemical carbonization and
gasification of wet,
especially water-containing and/or dry, biomass for producing an energy
carrier and/or raw-material
carrier;
10 Fig. 3 a partial view of the device according to Fig. 1;
Fig. 4 a partial view of the gasification reactor with a gasifier head, a
gasifier middle part and a
gasifier bottom.
Fig. 1 shows a carbonization reactor or first vessel 1 for thermochemical
carbonization and
gasification of wet, especially water-containing and/or dry, biomass for
producing an energy carrier
and/or raw-material carrier. The carbonization reactor or first vessel 1 is
supplied with biomass via a
receiving tank 2, which is provided with an inlet valve or flat slide valve 13
and a flat slide valve or
outlet valve 15. In the carbonization reactor or first vessel 1, a stirrer 5
is provided, in which the
biomass is mixed, which consists of a wet, especially water-containing and/or
dry, biomass. This can
include, among other things, wastes, such as foodstuff residues, biological
wastes, and wood. The
stirrer 5 can be operated manually or by means of a motor 3.
At initial start-up of the complete plant, first wood or charcoal is put in a
gasification reactor 16 and
then the plant is started up. The reaction gas obtained in the gasification
reactor 16 is supplied via a
line 32 to a heating element 4, which surrounds the carbonization reactor or
first vessel 1. As a
result, the carbonization is started. The gas received in the heating element
4 is constantly cooled
through introduction of biomass. Energy is saved as a result of this working
process. The energy loss
that arises is supplied to the plant with external energy.
The carbonization reactor or first vessel I is connected operatively to a
heating element, in particular
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1 I
is surrounded by a heating jacket 4. The carbonization reactor 1 is supplied
at least with external
thermal energy 60 and in an advantageous, energy-saving manner with further
thermal energy at
least from the complete plant, especially from a gasification reactor 16, so
that in this way the plant
can be operated very economically. The biomass can be supplied continuously or
batchwise to the
vessel 1. A blow-off valve 7 for controlling the pressure of vessel 1 is
provided in the upper part of
vessel 1. If the biomass is supplied batchwise to vessel 1, then vessel 1 is
filled with cold or also
warmed biomass and is heated by the heating element, so that the water present
in the biomass
evaporates. The steam is supplied to a reaction storage tank 21, so that the
energy, which is also
made available to the gasification reactor 16. can be fully utilized. With
further heat supply above
approx. 180 C, the chemical reaction starts and largely coal and gaseous
reaction products are
produced from the biomass.
The reaction gas led away from vessel 1 has a temperature of at least 300-400
C. This is led at least
partially via line 28 into the reaction gas storage tank 21 and from there
into the gasification reactor
16. In line 28 there is a nonreturn valve 80, so that excess pressure from the
reaction gas storage
tank 21 cannot escape to vessel 1.
In the reaction gas storage tank 21, the gas is cooled by the cooling device
49, which is connected
via a line 51 and 30 to the vessel 9, to a temperature of approx. 80 . A
pressure of approx. 2 to 5 bar
prevails in vessel 9 and in the reaction gas storage tank 21. The cooling
water is conveyed from the
reaction gas storage tank 21 via a line 78 to the cooling jacket 52 of the
gasification reactor 16. As a
result, more saturated steam can be produced. Via line 78, the reaction gas
storage tank 21 for the
gasification reactor 16 can be emptied completely.
In vessel 16, various measuring points 81 are provided, with the aid of which
the temperature in
vessel 16 can be controlled.
The gas storage tank 21 has a regulating function and serves for receiving the
reaction gases from
vessels 1 and 9. The reaction gas from the reaction gas storage tank 21 is
burnt with the coal in the
gasification reactor 16.
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During combustion of the reaction gas and of the coal in the gasification
reactor 16, there is
formation of synthesis gas, which is then supplied to one or more consumers,
such as a gas engine.
After the required reaction temperature is reached, the chemical reaction
begins in the biomass and
in addition to the biocoal there is also formation of gas, mainly CO, and
steam. This gas-steam
mixture is called reaction exhaust gas. The total pressure inside the reactor
is found from the sum of
the boiling pressure of steam and the partial pressure of the inert gas
fraction in vessel I. The
reaction is associated with generation of heat, i.e. an exothermic reaction
takes place in the vessel.
For limiting the pressure, the carbonization reactor or first vessel 1 has the
pressure-regulated or
controlled valve 7. After completion of the reaction, the carbonization
reactor or first vessel 1 is
relieved from pressure by fully opening valve 7, until it can be opened safely
and the biocoal can be
removed.
In continuous operation, the biomass is supplied to the carbonization reactor
or first vessel 1 in small
amounts and in short time intervals via a pressurized air lock or a receiving
tank 9 from above. In
the carbonization reactor 1 there is always high pressure and high temperature
of about 16 bar and
200 C. The biomass supplied is heated in the carbonization reactor 1 and the
water it contains
evaporates at least partially, or even completely, depending on the process
time. The reacting
biomass passes through the reactor from top to bottom, with continuous
stirring. After the reaction
process, coal is removed from a second vessel or buffer tank 9, also called a
pressurized air lock. To
limit the pressure in the vessel, reaction exhaust gas is released continually
by the pressure control
valve 7 from the carbonization reactor. The pressurized air lock 9 can also be
in the form of a buffer
tank.
So that sufficient moisture can be made available to the biocoal in vessel 9
during the working
process, fresh water is supplied to it via the cooling device 49 and line 51.
Furthermore, vessel 9 can
be equipped with a stirrer, to ensure better penetration of the biocoal with
moisture.
The plant can also be operated cyclically or with varying pressure, with a
pressure of approx. 20 bar
and a temperature of 200 C in the carbonization reactor 1. The biocoal present
in the second vessel
or buffer tank 9 is cooled. For this, the vessel or buffer tank 9 has a
cooling jacket 51. The pressure
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in the buffer tank 9 is also controlled by a pressure-controlled valve 12,
depending on how the
process is operated.
Depending on how the process is operated, the moisture-containing biomass
received in the
carbonization reactor 1 can evaporate at pressures between 5 and 30 bar,
preferably at pressures
uthween 15 and 25 bar, especially at pressures of about 20 bar and at
temperatures between 2000 and
1200 C, preferably between 400 and 800 C, and reaction gas can be formed,
which is supplied
directly or indirectly to the gasification reactor 16 via a line 30.
The gasification reactor 16 according to Fig. 1 or according to Fig. 4
(partial representation)
operates at atmospheric pressure. It is subdivided into a gasifier head 61, a
gasifier middle part 62
and a gasifier bottom 63. The biocoal received in vessel 9 is fed via a feed
hole 64 into the gasifier
head 61. There it is heated by the heat supplied from the gasifier middle part
62 to a temperature of
up to approx. 900 C, at which the further gasification of the coal or biocoal
begins.
At this temperature, the biocoal reaches the middle part 62 of the
gasification reactor 16. There,
gasification takes place at temperatures above 900 C. The reaction gas that is
released from the
biocoal reaches temperatures of up to 1800 C. By suitably controlling the
reaction process with the
aid of a computer by manual control, the temperature of the solids still in
the gasification reactor 16
is limited so that the ash does not melt.
As can be seen from Fig. 4, the gasification reactor 16 consists of an outer
casing 66, in which a
gasifier part 67 is housed in a funnel-shaped part, which has a larger cross
section in the upper
region than in the middle region. The bottom of the gasification reactor 63
gets wider toward its
discharge end. The discharge end consists of several outlets 68 provided in
the gasification reactor
bottom 63 for discharge of the reactor gas and the ash.
The reactor gas is led via the outlets 68 in a perforated, partially
cylindrically or conically expanded,
internal wall 69 of the gasification reactor bottom 63 into an annular gap 70
that is formed between
an external wall 71 and the internal wall 69 of the gasification reactor
bottom 63.
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The gasification reactor 16 is also connected directly or indirectly to a
cleaning device, such as a
cyclone separator 18 and/or gas scrubber 20. From there, the gas is conveyed
to a gas compressor 44
and/or to a gas engine 48.
The gasification reactor 16 is also connected via line 30 to the reaction gas
storage tank 21 (Fig. 1).
In addition, the gasification reactor 16 has maintenance openings 82, which
can be opened if
necessary.
In the upper part of the casing 66 of the gasification reactor 16 there are
one or more outlets 72
distributed round the circumference, through which the reactor gas is
withdrawn from the
gasification reactor 16. Lines 73 connected thereto open into one or more dust
separators, which are
for example in the form of cyclone separators 18 and from which the reactor
gas is supplied for
further use or is supplied to the consumers, such as the gas engine 48 or gas
compressor 44. The ash
is discharged at the lower end of the gasification reactor bottom 63 via an
outlet 65 and is
transported from there by a conveyor to a disposal tank.
In the lower region of the external periphery of the gasifier middle part 62,
one or more gas lances
or thermally connected melting units 74 are provided, so that reaction exhaust
gas 75 from the
carbonization reactor 1 and optionally also from the second vessel or buffer
tank or the pressurized
air lock 9 can be injected into the gasification zone of the gasification
reactor 16. As a result, by
means of the high temperatures, waste substances still present, such as sulfur
and chlorine
compounds, are burnt.
The gasification reactor 16 (Figs. 1 and 4) and/or the second vessel 9 are
cooled by means of a
cooling device 49 and are in each case surrounded by a cooling jacket 51, 52.
The cooling device 49
is fed with cooling water, wherein at least also cooling water from the
cooling jacket 51 of the
second vessel 9 can be supplied via a line 54 to the gasification reactor 16.
The heat taken up by the coolant can be used for evaporation of the cooling
water and for
superheating the high-pressure steam 76 thus produced.
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The gasification reactor 16 can be operated continuously. The biomass is
supplied in short time
intervals or continuously. The reactor gas and the ash are discharged
continuously as volume or
mass flows from the gasification reactor 16.
5 The reactors 1 and 16 described are operated roughly simultaneously.
By arranging the carbonization reactor 1, the buffer tank 9 and the
gasification reactor 16 according
to Fig. 4 as an operational unit, a space-saving arrangement is achieved. As
already mentioned, the
biomass feed is located above the complete device, consisting, of 1, 9. 16.
The biomass is received
via the entry pressurized air lock in the receiving tank 2 and is supplied to
the gasification reactor
10 16. It passes through this from top to bottom and on completion of
carbonization is discharged into
the buffer tank 9. In continuous operation of the carbonization reactor 1, the
buffer tank 9, which
receives biocoal from the carbonization reactor 1, is operated intermittently.
The moisture-containing biomass received in the carbonization reactor 1
evaporates at pressures
15 between 5 and 30 bar, preferably at pressures between 15 and 25 bar,
especially at pressures of about
bar and at temperatures between 200 and 1200 C, preferably between 400 and
800 C. Reaction
gas is also formed, which is supplied directly or indirectly to the
gasification reactor 16 via line 30.
Another possibility for construction of the complete device, consisting of
vessels 1, 9, 16, is shown
20 in Fig. 4. This is suitable when a vertical arrangement is not possible for
reasons of space.
The biocoal leaving the buffer tank 9 is transported by means of mechanical
conveying devices,
such as a conveyor belt or worm conveyor 77, into the filling hopper of the
adjacent gasification
reactor 16, feeding the latter continuously.
A flow chart of the complete plant is shown in Fig. 3.
The gasification reactor 16 is connected via a line 34 to a further processing
device 36 for treatment
and/or further processing of the coal obtained in the gasification reactor 16.
The saturated steam that is formed in the gasification reactor 1 is connected
via the saturated steam
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line 38 to a consumer or to a heating system and/or a steam piston engine 42.
The reaction gas produced in the complete plant or in the first vessel 1 is
supplied directly or
indirectly to the cyclone separator 18 and/or gas scrubber 20 and then to a
dehumidifier 56 or
directly or indirectly to a compressor 44 or to the consumer 48.
In one or more lines 26-34, 38, 50, 53, 54, control valves can be provided,
which can be turned on or
off manually or by a drive device, wherein the drive devices are controlled
via a computer in relation
to the working process.
Analysis values from the prior art HTC
(hydrothermal carbonization) charcoal
Table 1 Analysis Air-dried charcoal Dry charcoal
HTC HTC
Proximate analysis Moisture 8.8 0.0
Ash 6.9 7.6
Volatile constituents 58.5 64.1
Fixer carbon 25.8 28.3
Sulfur Total sulfur 0.58 0.6
Calorific values in Lower calorific 4668 5169
kcal/kg value kcal/kg
Upper calorific 4969 5446
value kcal/kg
Elemental analysis C 53.86 59.0
5.92 5.4
5.36 5.9
0 34.86 29.7
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Analysis values of the plant and device according to the invention
Table 2 Analysis Original Air-dried Dry
charcoal charcoal charcoal
Proximate Moisture 34.9% 21.6% 0.0%
analysis % Ash 1.9% 2.3% 2.9%
Volatile 24.2% 29.2% 37.2%
constituents
Fixer carbon 39.0 46.9 59.9
Sulfur Total sulfur 0.2 0.2 0.2
Calorific values Lower calorific 4382 5392 7030
in kcal/kg value kcal /kg
Upper calorific 4730 5699 7269
value kcal/kg
Elemental C 63.2 83.64
analysis H 5.56 4
N 0.22 0.29
0 30.82 14.89
