U.S. patent application number 13/135831 was filed with the patent office on 2012-02-02 for process and apparatus for generating hydrogen.
This patent application is currently assigned to Spawnt Private S.a.r.l.. Invention is credited to Norbert Auner, Christian Bauch, Birgit Urschel.
Application Number | 20120027643 13/135831 |
Document ID | / |
Family ID | 37758634 |
Filed Date | 2012-02-02 |
United States Patent
Application |
20120027643 |
Kind Code |
A1 |
Bauch; Christian ; et
al. |
February 2, 2012 |
Process and apparatus for generating hydrogen
Abstract
A solution is to be created, with a method and a device for
generating hydrogen, in which silicon and/or an alloy that contains
silicon is reacted in a reaction vessel (1), with an alkaline
solution as a catalyst, so that the process, after starting, runs
continuously and catalytically in the presence of silicon dioxide
as a nucleating agent, without further addition of lye and without
using higher pressures and temperatures (hydrothermal conditions).
This is achieved in that the alkaline solution is used in a
strongly sub-stoichiometric amount with reference to the entire
reaction, whereby the silicon dioxide that is formed is
precipitated onto crystallization nuclei.
Inventors: |
Bauch; Christian; (Usingen,
DE) ; Auner; Norbert; (Glashuetten, DE) ;
Urschel; Birgit; (Usingen, DE) |
Assignee: |
Spawnt Private S.a.r.l.
Luxembourg
LU
|
Family ID: |
37758634 |
Appl. No.: |
13/135831 |
Filed: |
July 15, 2011 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
12084815 |
Jun 3, 2008 |
8012444 |
|
|
PCT/EP2006/010724 |
Nov 9, 2006 |
|
|
|
13135831 |
|
|
|
|
Current U.S.
Class: |
422/105 ;
422/129; 422/187 |
Current CPC
Class: |
Y02E 60/36 20130101;
Y02E 60/362 20130101; C01B 3/065 20130101 |
Class at
Publication: |
422/105 ;
422/129; 422/187 |
International
Class: |
B01J 8/00 20060101
B01J008/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 9, 2005 |
DE |
10 2005 053 781.2 |
May 3, 2006 |
DE |
10 2006 020 786.6 |
Claims
1. A device for generating hydrogen comprising a reaction vessel
(1) for a reaction mixture, a charging device (4) for silicon
and/or an alloy that contains silicon, a device for adding alkaline
solution as a catalyst, and a device for adding crystallization
nuclei.
2. The device according to claim 1, further comprising a control
device for metered addition of the silicon and/or the alloy that
contains silicon and/or the catalyst and/or the crystallization
nuclei.
3. The device according to claim 2, wherein the control device is
configured for time-metered addition of the catalyst and/or the
silicon and/or is configured for addition of the catalyst and/or
the silicon by measurement of hydrogen development.
4. The device according to claim 1, wherein the charging device (4)
for silicon is configured so that a dry flushing gas can flow
through the charging device.
5. The device according to claim 1, further comprising a
circulation pump (30) and a cooler (22).
6. The device according to claim 1, further comprising a separation
device for separating solids from the reaction mixture.
7. The device according to claim 6, wherein the separation device
is configured as a filter press and/or a centrifuge.
8. The device according to claim 1, further comprising a mist
separator (31).
9. The device according to claim 8, wherein the mist separator (31)
comprises a filler body column and/or a cyclone.
10. The device according to claim 1, further comprising a storage
vessel (2) for displacement of the solution.
11. The device according to claim 10, wherein the storage vessel
has cooling.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of and Applicant claims
priority under 35 U.S.C. .sctn..sctn.120 and 121 of parent U.S.
patent application Ser. No. 12/084,815, which application is a
national stage application under 35 U.S.C. .sctn.371 of
PCT/EP2006/010724 filed on Nov. 9, 2006, which claims priority
under 35 U.S.C. .sctn.119 of German Application No. 10 2005 053
781.2 filed on Nov. 9, 2005 and German Application No. 10 2006 020
786.6 filed May 3, 2006, the disclosures of each of which are
hereby incorporated by reference. The international application
under PCT article 21(2) was not published in English.
STATE OF THE ART
[0002] A method for generating hydrogen is disclosed in DE 102 01
773 A1, in which water is sprayed onto fine-particle silicon in a
reaction chamber. In contrast to the method according to the
invention, the addition of a catalyst is not described. [0003] JP
2004115349 discloses a method in which fine-particle silicon powder
is oxidized with water over a long period of time. [0004] JP
2004115348 describes a non-catalytic process in which water heated
for hydrogen production is pressed through a cartridge that
contains silicon.
[0005] Similar methods are state of the art (DE 21 67 68; U.S. Pat.
No. 909,536; U.S. Pat. No. 3,895,102; DE 101 55 171 A1; DE 199 54
513; JP 2004307328). These use different grades of silicon, e.g.
silicon scrap from electronics production (JP 2004307328), for
generating hydrogen, e.g. for the operation of fuel cells. In
addition to practical utilization of silicon scrap, the good
storage and transport capabilities and the comparatively low price
of silicon (as compared with aluminum, for example) stand in the
foreground here. In the patent application JP 2004307328 of Sanyo
Electric Co., a simple device is described, in which scrap silicon
from electronics production is brought into contact with an
alkaline solution, such as caustic soda, in a vessel. In this
connection, the lye reacts with the SiO.sub.2 that covers the
surface of the silicon, to form sodium silicate and H.sub.2O, and
the remaining Si reacts with H.sub.2O to form silicic acid and
hydrogen. It is disadvantageous that one proceeds from the
assumption that the substances to be brought to reaction must stand
in a stoichiometric ratio to one another, thereby establishing the
proportion of the hydrogen to be obtained by means of the molar
ratio of the caustic soda to the silicon oxide (which passivates
the surface) and the silicon that lies underneath, ending with the
completely stoichiometric formation of sodium silicate. This
requires a large amount of relatively expensive caustic soda and
results in a large amount of sodium silicate, which must be
disposed of.
[0006] In another known method (DE 21 67 68), the caustic soda that
is used up is regenerated by adding slaked lime (Ca(OH).sub.2), and
therefore in addition to silicon and water, slaked lime or caustic
lime has to be used, and the amount of waste increases due to the
formation of calcium silicate.
[0007] In another known method (U.S. Pat. No. 909,536), sodium
metal is used for generating hydrogen, and silicon or aluminum is
added to increase the hydrogen yield per kg sodium, since the
latter is expensive. In this connection, the silicon reacts with
the caustic soda that has formed from the sodium metal, to produce
a sodium silicate solution. The high price of the sodium used and
the high risk of using alkali metals (e.g. easy inflammability,
poor storage capability) are disadvantageous.
[0008] Another known method (U.S. Pat. No. 3,669,751) reacts a
mixture of aluminum and silicon with an aqueous lye, whereby
alumosilicate, which has low solubility, is to be formed. Again, it
is disadvantageous that stoichiometric amounts of lye are consumed,
making the method more expensive, and that the amount of waste is
relatively great, due to the formation of the alumosilicate.
[0009] Another method (U.S. Pat. No. 3,895,102), in which silicon
is mixed with NaCl, in order to prevent the deposition of sodium
silicate, which has poor solubility, on the surface of the silicon,
during the subsequent reaction with caustic soda, possesses similar
disadvantages. Here, too, the consumption of NaCl is another
disadvantage, increasing the costs of the process.
[0010] Another known method (WO 02/14213) reacts silicon with
water, at an approximately neutral pH, after it has been intimately
ground together with silicon dioxide (as a "catalyst"). It is
disadvantageous that the reaction yields a noteworthy conversion
only when using large amounts of silicon dioxide, which makes the
grinding process, which is expensive in any case, even more
complicated. Furthermore, the conversion rates are very low,
because the work is carried out at pH values around the neutral
point, and the reactions rapidly come to a halt due to passivation
of the silicon surface, so that renewed grinding of the mixture
becomes necessary.
[0011] Another known method (DE 199 54 513 A1) circumvents the
problem of the low reaction rate of the previous method by working
at a high temperature (>170.degree. C.) and using caustic soda
as the reaction medium. The lye is then regenerated in a separate
crystallizer, forming crystalline silicon dioxide, under
hydrothermal conditions. Working at high temperatures (hydrothermal
conditions) is disadvantageous, since it causes high pressures to
occur, which make an expensive reactor design necessary.
Furthermore, precise temperature control and constant circulation
pumping of the reaction solution, with adherence to a precise
temperature gradient, are necessary in order to allow the silicon
dioxide crystals to grow in the crystallizer in targeted manner,
and not in the reaction region or on the surface of the silicon
used, if at all possible.
[0012] In another method by the same applicant (DE 101 55 171 A1),
the problem of undesirable growth of the silicon dioxide crystals
on the surface of the silicon used is counteracted in that the
silicon is completely brought into solution with a sufficient
amount of lye. It is disadvantageous that a large amount of lye is
used, which must be regenerated in a subsequent step, in
complicated manner (hydrothermal crystal synthesis).
[0013] The invention is based on the task of clearly improving the
known method of generating hydrogen from silicon or amphoteric
elements such as aluminum or zinc and an aqueous alkaline solution,
in a closed vessel, to the effect that the process proceeds
catalytically and continuously after it starts, in the presence of
silicon oxide as a nucleating agent, without further feed of lye,
and without using high pressures and temperatures (hydrothermal
conditions).
[0014] According to the method according to the invention, an
alkaline solution (catalyst), e.g. sodium silicate solution, is
added to the silicon grains contained in the solution, in a clearly
sub-stoichiometric ratio with reference to the entire reaction, and
crystallization nuclei, e.g. finely ground quartz meal, are added
to the solution for the silicon oxide that newly forms from the
silicon.
[0015] According to the invention, it proves to be advantageous to
work at a catalyst concentration between 10.sup.-4 mol/L -10
mol/L.
[0016] Although the reaction already takes place at room
temperature, it proves to be advantageous to work at an elevated
temperature, e.g. between 50.degree. C. and the boiling point of
the solution, in order to achieve a higher rate of conversion.
Although the reaction releases enough heat to maintain the desired
reaction temperature if the reactor walls are sufficiently
insulated thermally, external heating of the reactor is provided
for a quick start of the reaction. It is also advantageous to
thermally insulate other devices that carry media, in order to
prevent supersaturation of the solution due to cooling.
[0017] In the end result, the silicon placed into the solution is
dissolved, and in this connection reacts with the water of the
solution, in the presence of the catalyst, giving off hydrogen, to
form silicates that decompose on the crystallization nuclei,
splitting off silicon dioxide, and release the catalyst again when
they do so. In order to guarantee a speedy start of the reaction,
it proves to be advantageous to start the reaction with a mixture
of approximately 90% silicon and 10% crystallization nuclei, but
the reaction can also be reliably started with mixture ratios that
deviate significantly from this. Any materials that promote
spontaneous crystallization of an SiO.sub.2 modification, i.e. the
precipitation of hydrated SiO.sub.2 (depending on the reaction
conditions), because of their high surface and their crystal
structure, are suitable as crystallization nuclei, whereby quartz
meal is preferred because of its low price. The silicon grains
themselves, with their adhering oxide layer, can also assume this
task. In this case, it is advantageous to use a relatively high
proportion of fine silicon that possesses the necessary high
surface in the mixture.
[0018] The catalyst allows an extensive reaction of the silicon
with the water, in that it promotes the transport of the oxidized
silicon from the surface of the silicon grains to the
crystallization nuclei, which are added in the form of quartz meal,
for example, or which form during the reaction. The precipitated
SiO.sub.2 can be drawn off by way of a draw-off device. The grain
size of the crystallization nuclei can be varied within broad
ranges, whereby fine material (<10 .mu.m) is preferred due to
its high specific surface. The material containing SiO.sub.2 that
has precipitated during preceding reactions is used with particular
preference.
[0019] The resulting hydrogen is drawn off from the device by way
of a condenser for removing steam, as is known from the state of
the art, then compressed and stored in a pressure vessel, a hydride
storage device or the like, or directly supplied to a consumer, for
example a fuel cell.
[0020] The method according to the invention ends, if no further
silicon is placed into the reaction mixture, with complete
oxidation of the silicon placed into the device, or of the
amphoteric elements placed into the device.
[0021] It proves to be advantageous to provide that a method that
has once been started for generating hydrogen can also be
interrupted. Here, it is provided that removal of the hydrogen from
the device according to the invention can be stopped in that no
further hydrogen is removed from the device, so that pressure
builds up in the device, and the aqueous lye can be pressed into a
second vessel, along with the intermediate reaction products, and
the silicon to be oxidized or the amphoteric elements remain in the
first vessel, within the filter basket, and thereby any further
reactions are interrupted. If the process it supposed to be
continued, solution situated in the second vessel is pressed back
into the first vessel, and the reaction is continued.
[0022] A preferred method for controlling the progress of the
reaction is to add the catalyst to the reaction mixture over a
longer period of time. In this manner, the concentration of the
catalyst is slowly increased, and a more uniform development of
hydrogen is achieved. Another preferred method for controlling the
progress of the reaction is to add the silicon to the reaction
mixture continuously or discontinuously. In this manner, first of
all, a more uniform hydrogen development is achieved, and second,
the amount of hydrogen that can maximally develop is limited, if
the reaction must be shut off for some reason.
[0023] The grain size of the silicon is not critical for the
process, so that both silicon in the form of dust (<1 .mu.m) and
coarse pieces (>1 cm) can be used. The size used is limited when
using a filter basket, in that the pieces should clearly be larger
than the pore size of the filter being used, in order to guarantee
the greatest possible conversion before the particles can fall
through the filter, whereby a more rapid reaction takes place when
using finer particles (e.g. 20-400 .mu.m), because of the higher
specific surface.
[0024] The method for generating hydrogen, according to the
invention, can also be used in that zinc or aluminum or magnesium
are added to the solution in place of silicon.
[0025] Another method for generating hydrogen, according to the
invention, is characterized in that scrap silicon from electronics
production is brought together with caustic soda in a
sub-stoichiometric ratio in a reaction vessel, and crystallization
nuclei of quartz meal are added to the solution, and that the
resulting hydrogen can be drawn off, until the scrap silicon that
has been brought into the solution has completely oxidized on the
crystallization nuclei.
[0026] Instead of silicon, zinc, aluminum, or magnesium can be
added to the solution for oxidation, in advantageous manner.
[0027] It is advantageous that the caustic soda of the solution is
supplied in a sub-stoichiometric ratio between 0.5 and 30.0% at the
beginning of the reaction.
[0028] The solution can be drawn off by way of a filter press, if
necessary, and silicon dioxide can be removed from the solution in
the filter press and taken out of the process.
[0029] In an embodiment, the solution remaining in the filter press
can be passed back into the reaction vessel, adding fresh
water.
[0030] It is advantageous that quartz meal can be supplied to the
reaction vessel discontinuously or continuously, by way of a
device.
[0031] Furthermore, hydrogen gas can be removed from the device by
way of a filter, for compression and storing pressure.
[0032] It is possible that the reaction process in the reaction
vessel is made possible by means of a pressure-related displacement
of the solution in a storage vessel.
[0033] Another alternative embodiment of the method for generating
hydrogen, according to the invention, is characterized in that
silicon is oxidized to form silicon oxide, in a reaction vessel,
catalytically, with an alkaline solution, and that crystallization
nuclei made of quartz meal are added to the solution, and that the
resulting hydrogen can be drawn off.
[0034] Aside from the advantageous embodiments described above,
which are also possible for this additional method according to the
invention, it can be advantageous that the alkaline solution has a
pH between 8 and 15, which corresponds to an OH concentration of
10.sup.-6 mol/L-10 mol/L, and the substance mixture of H.sub.2O,
nuclei-forming agents, and reaction elements is supplied, at the
beginning of the reaction, in a sub-stoichiometric ratio between
0.5 and 30.0% of the ratio between NaOH and the elements to be
oxidized.
[0035] In another advantageous embodiment, the reaction of the
reaction mixture preferably takes place within a filter basket
within the reaction vessel.
[0036] In this connection, it is advantageously possible that when
the solution with fresh water is supplied again, the solution flows
through a device that produces turbulence and eddying.
[0037] This device will be explained in greater detail below,
together with other advantageous embodiments, along with the method
according to the invention, using several drawings. These show,
in:
[0038] FIGS. 1 to 4 the results of various experiments to implement
the method according to the invention,
[0039] FIG. 5 a device for technical implementation of the method
according to the invention, in a schematic representation,
[0040] FIG. 6 another device for technical implementation of the
method according to the invention,
[0041] FIG. 7 another alternative device for technical
implementation of the method according to the invention, and in
[0042] FIG. 8 yet another alternative device for technical
implementation of the method according to the invention.
[0043] The invention will be described below, using exemplary
embodiments:
EXAMPLE 1
[0044] Comparison of silicon batches having different grain sizes
(cf. FIG. 1):
[0045] 20 g Si (0-70 .mu.m or 200-400 .mu.m), 100 ml demineralized
water, and 10 ml silicate of sodium are heated to boiling in a
reaction vessel, while stirring. The resulting hydrogen is freed of
the major portion of the steam adhering to it in an intensive
cooler, and is passed through a tube containing glass wool to
remove aerosol particles. The hydrogen development is recorded with
a flow measurement device and plotted graphically. This shows that
finer silicon powder yields a higher hydrogen flow at a shorter
experiment time. When using a silicon batch having a grain size of
0-70 .mu.m, the hydrogen development continues for approximately
5.5 h. When using a silicon batch having a grain size of 200-400
.mu.m, the hydrogen development continues for approximately 9 h.
During this experiment, the gas development is very strong at the
beginning, then decreases rapidly, and becomes very weak towards
the end (cf. FIG. 3, V. 5 and V. 6).
EXAMPLE 2
[0046] Constant hydrogen development over a longer period of time
(cf. FIG. 2):
[0047] 20 g Si (0-70 .mu.m) and 50 ml demineralized water are
heated to boiling in a reaction vessel, while stirring. A mixture
of 10 ml silicate of sodium and 40 ml demineralized water is
dripped into this suspension.
[0048] At the beginning, a high drip speed is selected (300 ml/h),
in order to get the reaction underway quickly, but this is
regulated back during the rapid increase. When the maximum is
reached, the hydrogen development is kept approximately constant
over approximately 1.5 h, by varying the drip speed. The decrease
in gas development takes place relatively rapidly when the reaction
is conducted this way.
EXAMPLE 3
[0049] Reaction on a larger scale (cf. FIG. 3):
[0050] 80 g Si (200-400 .mu.m) and 350 ml demineralized water are
heated to boiling in a reaction vessel, while stirring. A mixture
of 40 ml silicate of sodium and 10 ml demineralized water is
dripped into this suspension.
[0051] At the beginning, a high drip speed is selected (300 ml/h),
in order to get the reaction underway quickly, but this is
regulated back during the rapid increase. At the beginning, the gas
development runs out of the measurement range, so that it has to be
shut off for a few minutes. Afterwards, it is possible to regulate
the reaction well. A comparison with smaller batches shows that the
reaction can be scaled directly.
EXAMPLE 4
[0052] Experiments concerning the catalytic nature of the method
(cf. FIG. 4):
[0053] The mixture from Example 2, which has finished reacting, is
refreshed with 20 g Si (0-70 .mu.m) and 25 ml demineralized water
after 24 h, and again heated to boiling, while stirring. The
reaction starts spontaneously and yields a similar amount of
hydrogen as the first reaction, in a comparable time.
[0054] After another 24 h, the mixture from the previous
experiment, which has finished reacting, is refreshed with another
20 g Si (0-70 .mu.m) and 25 ml demineralized water, and heated to
boiling, while stirring. In this case, too, the reaction starts
spontaneously and again yields a comparable amount of hydrogen in a
similar time. This shows that the catalyst survives three reaction
cycles without any clear loss in activity.
[0055] In the following exemplary embodiments, elements that are
the same or have the same effect are provided with the same
reference symbols.
[0056] In the first embodiment of a device according to the
invention shown in FIG. 5, silicon and caustic soda, for example,
and crystallization nuclei are brought together in a reaction
vessel 1. The resulting hydrogen is passed to a hydrogen filter 6
by way of the drain line 5, and to a pressure storage unit 9 by way
of a pressure increase device 7 and a filling valve 8.
[0057] The mixture in the reaction vessel 1 is circulated by way of
a removal device 12, whereby resulting solids can be removed from
the circulation by way of a kick-back valve 14 and a removal device
15. Fresh water can be supplied by way of the container 10 and a
control valve 11. Silicon and/or quartz meal can be added to the
reaction vessel 1 by way of a charging device 4. If no hydrogen is
removed from circulation, the aqueous solution with the reaction
mixture is pressed into a storage vessel 2 with its liquid
components, by way of control valves 3, and hydrogen formation in
the reaction vessel 1 comes to a standstill. When pressure is
relieved from the reaction vessel 1, for example by removing
hydrogen by way of the pressure increase device 7 and the filling
valve 8, the solution is pressed out of the storage vessel 2 back
into the reaction vessel 1, and hydrogen formation can be
continued.
[0058] The device shown in FIG. 6 has a similar fundamental
structure as the one shown in FIG. 5.
[0059] Supplementally, the reaction vessel 1 has a filter basket 20
that can retain solid components of the reaction mixture.
Furthermore, the removal device 12 is disposed at the bottom of the
reaction vessel. The circulated reaction mixture is passed back to
the reaction vessel 1 by way of a turbulence generator 17, for
example a nozzle that produces an eddy or spin, in order to achieve
better, more thorough mixing in the reaction vessel 1. Aside from
the separation or pressure increase device 7 for hydrogen, a
hydrogen consumer 19, such as a fuel cell, and a removal valve 18
are directly connected with the apparatus, in addition to the
pressure storage unit 9. The reaction vessel 1 is insulated by
means of a heating/insulation mantle 21, in order to achieve better
temperature stability.
[0060] Another embodiment of a device according to the invention is
shown in FIG. 7.
[0061] A mixture of water and silicon is heated to the reaction
temperature (e.g. boiling temperature of water) in the reaction
vessel 1, using the heating mantle 21; catalyst is added by way of
the metering device for catalyst 26, in the desired amount, and the
desired amount of nucleating agent (e.g. SiO.sub.2 from the
preceding reaction) is added to the reaction mixture from the
supply container for nucleating agent 27, using the metering device
16, for a quick and reliable start of the reaction. The motor 24
with stirrer shaft 23 prevents the solids from clumping together,
by thoroughly mixing the suspension. The hydrogen that has
developed passes through the mist separator 31 after it leaves the
reactor, where entrained droplets are precipitated, and through the
cooler 22, where entrained steam is condensed. The drain line 5
contains a hydrogen filter 6 that is designed in accordance with
the purity requirements for the hydrogen produced. The device 7
compresses the hydrogen for storage in the pressure container 9, or
pumps it to the consumer 19 (e.g. a fuel cell).
[0062] As examples, two variants for operating the device are
described:
[0063] Variant 1: Water, catalyst, and nucleating agent are
presented and brought to reaction temperature (e.g. 90.degree. C.)
by means of heating mantle 21. The desired amount of silicon is
added by way of the charging device 4, and continues to be metered
in during the reaction, in order to keep the gas flow constant or
to change it in desired manner, whereby the circulation pump 30
draws dried hydrogen in through the cooler 22, by way of the
circulation line 29, and generates a circulation that prevents the
silicon from becoming damp from rising steam out of the reaction
vessel 1, and the silicon powder from therefore clumping together
in the region of the charging device 4. Consumed water is replaced
by adding fresh water via the control valve 11. The addition of
more silicon is stopped, at the latest, when the reaction mixture
reaches a specific viscosity that makes it necessary to remove the
silicon dioxide that has formed from the reaction mixture. For this
purpose, the removal device 12 transports the reaction mixture into
the filter device 13, in which the solid components are separated
(e.g. with filter cloth presses) and conveyed into the supply
container 27 by way of the removal device 15. From this container,
the desired amount of nucleating agent is placed into the reaction
vessel 1 as needed (e.g. when starting a new reaction after
cleaning the reaction vessel 1). Excess solid is removed by way of
the drain valve 14 and the drain connector 36 and passed on to
further utilization (cement industry, glass producers, etc.). The
filtrate is passed back into the reaction vessel 1 and enriched
with fresh water from the supply container 10 there. The type of
fresh water is not critical, in this connection, so that not only
demineralized water but also drinking water, process water, river
water, etc., can be used.
[0064] Variant 2: Water, nucleating agent, and the entire amount of
silicon are presented and brought to reaction temperature. For this
purpose, a little catalyst is added by way of the metering device
26, so that the reaction starts. By metering catalyst in during the
reaction, the desired hydrogen flow is established. Processing
takes place as described for Variant 1.
[0065] The embodiment of the invention shown in FIG. 8
fundamentally corresponds to that shown in FIG. 7. In addition, it
allows interruption of the hydrogen development, in that the
reaction solution is pressed into the storage vessel 2 by means of
the refilling device 3. In this connection, the filter basket 20
ensures that the silicon remains in the reaction vessel 1, for the
most part, whereby the meshes of the filter basket should be
clearly smaller than the average particle size of the silicon
grains. The gas dispensing line 32 assures pressure equalization
when solution is pumped back and forth between the two vessels, and
ensures that hydrogen that forms from fine silicon particles that
are not retained by the filter basket can escape. The refilling
device 3 does not necessarily have to be a pump, but instead, the
refilling process can also be achieved by lifting and lowering the
storage vessel (if flexible lines are provided), for example. In
order to allow fast stopping of the reaction in the storage vessel
2 even in the presence of fine-particle residual silicon, if
necessary, the storage vessel 2 is equipped with a cooling device
33.
[0066] The invention is not limited to the above exemplary
embodiments and operational variants, but instead can still be
modified in many different ways, without departing from the basic
idea. The precise type of structure of the devices, in particular,
can be modified within broad ranges, as long as the fundamental
method according to the invention can run on them. The type and
configuration of the different supply, feed, drain, mixing,
heating, and cooling devices can be varied in accordance with the
skill of a person skilled in the art, as can the related control
and system technology. The same holds true for the type and use of
the hydrogen generated, the waste products, and other intermediate
reaction products. The starting materials can stem from different
sources, as long as they have the chemical properties required for
the reaction to proceed.
REFERENCE SYMBOL LIST
[0067] 1. reaction vessel [0068] 2. storage vessel for production
interruption [0069] 3. control valves between reaction vessel and
storage vessel [0070] 4. charging device for silicon and quartz
meal [0071] 5. drain line for hydrogen [0072] 6. hydrogen filter
[0073] 7. pressure increase device or compressor for hydrogen
[0074] 8. filling valve for hydrogen pressure container [0075] 9.
pressure storage unit for hydrogen [0076] 10. supply container for
fresh water [0077] 11. control valve for fresh water feed [0078]
12. removal device or pump for reaction mixture [0079] 13. filter
device or press for separating solid and liquid [0080] 14.
kick-back valve [0081] 15. removal device for solid [0082] 16.
metering device for nucleating agent [0083] 17. turbulence
generator [0084] 18. removal valve for hydrogen [0085] 19. hydrogen
consumer [0086] 20. filter basket [0087] 21. heating/insulation
mantle [0088] 22. cooler/condenser for steam [0089] 23. stirrer
mechanism [0090] 24. stirrer motor [0091] 25. supply container for
catalyst [0092] 26. metering device for catalyst [0093] 27. supply
container for nucleating agent [0094] 28. supply container for
silicon [0095] 29. circulation line for hydrogen [0096] 30.
circulation pump for hydrogen [0097] 31. mist separator [0098] 32.
gas dispensing line [0099] 33. cooling device [0100] 34. refilling
device between reaction vessel and storage vessel [0101] 35. drain
valve for solid [0102] 36. drain connector for solid
* * * * *