Note: Descriptions are shown in the official language in which they were submitted.
2~9~2~
- 1 - BU 46/47
Process and appar~tus for working up
pyrotechnical material
The invention relates to processes for working up
pyrotechnical material and an apparatus suitable for this
purpose.
Pyrotechnical munitions, such as illumination
elements, flares, propellant charges, for example for
rockets, which are no longer suitable for use owing to
the expiry of their shelf life, must be disposed of.
0 Owing to the pyrotechnical potential and the high
strength of the active material, safe mechanical separ-
ation of the active materials is impossible or is poss-
ible only at a disproportionately high expense.
Illumination elements consist, as a rule, of a
container, which is usually made of metal, preferably of
aluminium, a fuse and the active material. The active
material is composed of a light metal powder as an energy
source, an oxidising agent which csn eliminate oxygen, an
organic binder for mechanical strengthening of the
mixture and optionally colour intensifiers. As a rule,
magnesium is used as the light metal powder since other
suitable metals are either toxicologically unsafe or too
expensive. As a rule, nitrates, in particular sodium
nitrate, are used as oxidising agents, chlorates or
perchlorates also being used in exceptional cases.
Polymers are used as organic binders. Halogen-containing
compounds, in particular fluorine-containing or chlorine-
containing metal salts, are present as colour inten-
sifiers. When the illumination elements burn, predomi-
nantly metal oxides, such as magnesium oxide, sodium
oxide and aluminlum oxide, nitrogen and oxides of
nitrogen and carbon oxides and optionally hydrogen halide
are therefore formed. Propellant charges consist
essentially of nitrogen cellulose.
The active materials of projectiles which are
intended to release irritants contain a high proportion
of chlorinated hydrocarbons in addition to aluminium or
zinc in powder form or as grit and irritation-promoting
.
20~222
- 2 - BU 46/47
~ additives. Propellant charge powders develop a hlgh
proportion of oxides of nitrogen when they undergo
combustion.
The disposal of this pyrotechnical material
therefore presents problems owing to the high proportion
of environmental pollutants, such as oxides of nitrogen
and halohydrocarbons, which are formed during the
combustion and must not escape into the environment. The
working up of such a material and the separation of the
pollutants is, as a rule, very expensive.
DE-B 41 06 615 discloses a process for working up
smoke elements or smoke active materials containing
chlorinated hydrocarbons. These active materials are
processed in such a way that the zinc and aluminiun
compounds contained therein can be recovered and reused.
This process relates to special working up steps for the
chlorinated hydrocarbons contained in the active
materials. Furthermore, DE-A 40 37 919 discloses a
process for disposing of propellant charges from
munitions, in which the propellant charges are comminuted
with the addition of water and then burned using a
special fluidised-bed furnace.
It is the object of the invention to provide a
process by means of which pyrotechnical material, in
particular illumination elements and propellant charges,
can be disposed of, which can be carried out safely and
in which no harmful substances are conveyed into the
environment.
To achieve this ob~ect different process variants
and apparatus for carrying out these proces~es are
provided, which can be ad~usted optimally to the respect-
ive material to be disposed of.
According to one aspect of the invention a
process is provided for working up pyrotechnical
material, which is characteri~ed in that
I. the pyrotechnical material i8 burned in a controlled
manner, the slag is optionally allowed to continue
reacting and the crude gas formed is passed through a
high-temperature region in which the gas is at a tempera-
~9~
- 3 - BU 46/47
ture of at least 1200-C over a predetermined period in
order to decompose organic substances still present;
II. the crude gas formed during the combustion is cooled
to a temperature below 400 C;
III. the crude gas is purified under dry conditions by
first feeding it into a preliminary separator, coarse
particles being separated off, and then feeding it via
fine dust filters in order to separate off finely divided
solids, and/or
IV. the crude gas is purified under wet conditions by
first passing it through a rotary scrubber and feeding it
via one or more absorption units, and
V. the pure gas is released as waste air.
With the process according to the invention, it
is possible to reduce to a very small level the harmful
components, such as oxides of nitrogen and halogen
compounds, which are formed during the combustion of the
pyrotechnical material and to minimise the cost of the
gas purification. In addition, reusable substances are
obtained and the heat generated during the combustion can
be effectively used. For the purposes of the invention,
pyrotechnical material is understood as meaning
pyrotechnical articles or pyrotechnical charges.
In the first stage of this embodiment of the
process according to the invention, the pyrotechnical
material is burned in a controlled manner. Combustion may
take place continuously or batchwise, in the continuous
procedure the material supplled preferably being ignited
in each case by the material already present in the
reactor, whereas in the batchwise process a batch is
always burned and thereafter the next batch is fed in and
ignited. The throughput and residence time are dependent
on the material to be burned, the type of process and the
reactor used. In general, the residence time is in the
range from 10 seconds to 1 minute.
Combustion is effected in one or more combustion
chambers. The combustion chamber used is a reactor which
can withstand the h;gh temperatures generated during the
combustion and can be loaded in a suitable manner. Either
- :
-,
2~9~222
- 4 - BU 46/47
B tube reactor or a reactor having a brlck llning i5
preferably used. A vertlcally arranged apparatus whlch
consists of steel resistant to hlgh temperatures and ls
cooled internally with gas is preferably used as the tube
reactor. For this purpose, air is introduced via tangen-
tial nozzles and is passed over tangential plates in such
a way that it flows along the wall of the tube reactor
and hence cools the steel jacket. This ensures that the
reactor jacket is at a temperature of no more than 400-C,
which it withstands without damage. By feeding the air
via tangential nozzles, the high temperature zone is
limited in a defined manner to a certain region. This
ensures on the one hand that organic pollutants are
virtually completely degraded directly on formation by
the combustion of the pyrotechnical elements and, on the
other hand, that caking of material or abrasion at the
internal wall is prevented.
In another embodiment, a reactor having a brick
linlng is used. This reactor constitutes a closed pres-
sure-tight space which is lined on the inside with
refractory material and is preferably a trough reactor or
rotary kiln. Since the refractory material withstands
temperatures of from above 1500 to 2000 C, it need not be
cooled. In a preferred embodiment of the reactor having
a brick lining, a mobile trough which receives melting
material and falllng slag and can be emptied batchwise is
provided below the combustion chamber.
one or more identical or different reactors can
be simultaneously used for the process according to the
invention. A tube reactor ls preferably used for worklng
up pyrotechnlcal materlal where predomlnantly alkallne
compounds escape lnto the crude gas, whereas a trough
reactor i8 used for working up pyrotechnical materlal
which releases predominantly acldic vapours.
After the controlled combustion of the
pyrotechnical material, the crude gas formed is passed
through a high-temperature reglon in which it is kept at
a temperature of at least 1200 C over a predetermined
perlod in order to decompose any organlc substances still
- 5 ~99222 BU 46/47
present. If the crude gas has reached a temperature of
over 1200-C as a result of combustion, it is sufficient
to keep the crude gas in the reaction region over the
predetermined period without additional heating. In an
embodiment, this is effected, for example, by ensuring
that the reactor has a sufficient height so that the
residence time of the ascending crude gas is sufficient
for complete reaction in the high-temperature region. In
another embodiment, in which the air is blown in tangen-
tially, the crude gas (reaction gas) is passed spirallyupwards and thus remains for a sufficiently long time in
the high-temperature region. If the crude gas is not hot
enough, an external heating source is provided in order
to heat the crude gas to the desired temperature. The
period of subsequent heating depends on the proportion of
organic compounds and can be easily determined by one
skilled in the art. As a rule, a period of 2 to
10 seconds is ~ufficient. A temperature of at least
1200-C, preferably at least 1500 C, is required in order
to decompose the organic compounds.
The crude gas which leaves the high-temperature
region contains virtually only inorganic compounds, which
are partly ln gaseous form and partly in the form of very
small particles. Dependlng on the composition of the
crude gas, dry purification and/or wet purification are
carried out. The wet purification can be carried out
before or after the dry purification. Preferably, the
crude gas is flrst purified under dry conditions and then
optionally sub~ected to a wet purification, depending on
reguirements. Since the gas which emerges from the high-
temperature region has a very high temperature, lt is
cooled to a temperature of below 400 C, the heat simulta-
neously possibly being used. In various applications,
cold air can be mixed with the hot gas in the proce~ for
cooling. In addition, heat can be utilised by using known
heat recovery techniques. An example of this i8 the
connection to the heat circulation of a heating station.
The crude gas is cooled to temperatures below 400 C or,
preferably, below 200 C, depending on the subsequent
.:
., .
.
-
.
~' - . '. .. : ., '
2 ~
- 6 - BU 46/47
treatment.
The crude gas is purified under dry and/or wet
conditions. For the dry purification, the gas should be
cooled preferably to below 200 C in order thus effec-
tively to prevent de novo syntheses of organic pollu-
tants. Furthermore, the filters usually used for the
purification cannot as a rule withstand higher tempera-
tures without damage.
For the dry separation, the crude gas is first
fed into a preliminary separator in which coarse
particles are separated off. Coar~e particles are desig-
nated as particles which have a size of at least 10 ym.
The separation of the coarse particles can be effected in
a manner known per se. A multicyclone is preferably used
for the separation. The type of particles separated off
in the multicyclone is dependent on the pyrotechnical
material worked up. If, for example, flare active
materials or illumination elements are burnt, the coarse
particles which are separated off in the multicyclone
consist predominantly of magnesium oxide and/or aluminium
oxide. The oxides separated off in the multicyclone can
be reused.
The crude gas which has been freed from the
coarse partlcles and has been sufficiently cooled by the
pretreatment can then be fed via a fine dust filter to
separate off small solid particles, i.e. particles having
a dlameter of less than 10 ~m. Woven fabric fllters are
preferably used as fine dust filters. In a preferred
embodiment, a system having several filters is used, one
part of the filters being loaded simultaneously and the
other part of the filters being cleaned to remove the
deposited solids mixture. With the fine dust filters, the
crude gas can be purified to a solids content of
S 10 mg/m3. The gas emerging from the fine dust filters
is now at a temperature of about 100 C and, if it no
longer contains any gaseous lmpurities, can be released
directly as waste air. If the gas still has gaseous
impurities, in particular halogen-containing compounds or
oxides of nitrogen, it is ~ub~ected to a wet purification
~.
. :
.
2 ~
- 7 - B~ 46/47
after the dry purification. In the working up of flares
and illumination elements, the gas i8 as a rule so pure
that wet purification is no longer necessary.
Instead of the dry purification of the gas, wet
purification can be carried out. This is useful if the
gas contains predominantly gaseous impurities, such as
halogen compounds and oxides of nitrogen, and a smaller
amount of alkali metal and alkaline earth metal oxides.
The wet purification may also be carried out before or,
preferably, after the dry purification.
If the wet purification of the crude gas is
carried out as a first purification step, the crude gas
is preferably first cooled to a temperature of below
140 C in a heat exchanger unit. The crude gas cooled in
the heat exchanger or the crude gas purified ~nder dry
conditions is then passed into a scrubbing apparatus for
scrubbing the crude gas. Apparatuses of this type are
known to those skilled in the art. For scrubbing, the
crude gas is preferably first fed through a Venturi unit
in order to cool the gas to such an extent that its
temperature is below the boiling point of water. It is
then passed into a rotary scrubber. After the rotary
scrubbing unit, gas scrubbing is carried out in a known
manner usinq one or more absorption units. Packed or tray
columns which are loaded with suitable wash liguids
depending on the loading of the gas are preferably used
for this purpose. Further filter units which are equip-
ped, for example, with cataly8ts or carbon absorption
filters may be connected to these columns lf necessary.
The very pure gas emerging from the absorption unit or
units is removed as waste air.
To ensure that, during the entire process, no
crude gas which has not been completely purified can
escape into the environment, the entire plant is operated
under reduced pressure. Thls ls effected in a manner
known per se, for example by using an extraction fan.
~ he process accordlng to the inventlon can be
adjusted in a variable manner to the conditions which
arise during the combustion of different pyrotechnical
- -
', '
.
2~2~
- 8 - BU 46t47
materials. Thus, the individual stages of the process can
be connected in series depending on requirements. If, for
example, flare and illumination materials which form
predominantly particulate oxides are burnt, the crude gas
is preferably passed via preliminary ~eparators and fine
dust filters after cooling and is then sufficiently pure
to be released into the environment. If pyrotechnical
elements in which a high proportion of gaseous impurities
are formed are worked up, the crude gas is preferably
purified by scrubbing and passage through absorption
units. If the gas furthermore contains solid components,
it can be fed through preliminary separators and fine
dust filters prior to scrubbing. In every case, the
process is carried out Ln such a way that the gas
contains only amounts of solids and gaseous compounds
which are so small that it fulfils existing emission
limits when released into the environment.
According to a further aspect of the present
invention another process for working up pyrotechnical
material is provided, which is characterised in that
I. a pyrotechnical material A, where predominantly
alkaline reaction products are formed, and a pyro-
technical material B, where predominantly acidic reaction
products are formed, are sub~ected to controlled combus-
t~on,
II. the combined crude gases formed during the combustionare cooled to a temperature below 400'C,
III. the combined crude gases are purified under dry
conditions by first feeding them into a preliminary
separator, coarse particles belng separated off, and then
feeding them via fine dust filters in order to separate
off finely divided solids, and/or
IV. the combined crude gases are purified under wet
conditions by first passing them through a rotary
scrubber and feeding them via one or more absorption
unit(s), and
V. the pure gas is released as waste air.
In the first stage of thi~ embodiment according
to the invention, pyrotechnical material A, where pre-
--' 2~9922~
- 9 - BU 46/47
dominantly alkaline reaction products are formed, and
pyrotec~nical material B, where predominantly acidic
reaction products are formed, are subjected to controlled
combustion. The combustion can be carried out con-
tinuously or batchwise, in the continuous procedure thematerial supplied preferably being ignited in each case
by the material already present in the reactor, while in
the batchwise process one batch is always burned and
thereafter the next batch is fed in and ignited. The
throughput and residence time of the material are depen-
dent on the material to be burned, the type of process
and the reactor used. In general, the residence time is
in the range from lO seconds to 1 minute.
According to the invention, two va~iants are
provided for the combustion of the pyrotechnical
material. In a first variant, pyrotechnical material A
and pyrotechnical B are burned separately in two reactors
and the crude gases are then combined by, for example,
feeding the crude gas formed during the combustion of the
pyrotechnical material A into the reactor in which the
pyrotechnical material B is burned. In a second variant,
pyrotechnical material A and pyrotechnical material B in
a suitable ratio are burned simultaneously in one
reactor. An essential feature of the invention is that
predominantly alkaline reaction products are formed
during the combustion of the pyrotechnical material A
whereas predominantly acidic reaction products are formed
during the combustion of the pyrotechnical materlal B.
For example, flare actlve materlals, lllumination
elements and thermite-llke mlxtures are u~ed as
pyrotechnlcal material A. For example, propellant charge
powders, smoke and irritant active materials and coloured
smoke~ may be mentioned as pyrotechnical material B. The
alkaline products formed during the combustion of the
pyrotechnical material A are predominantly alkali metal
and alkaline earth metal oxide~, while the acidic reac-
tion products formed during combustion of the pyro-
technical material B are, as a rule, halogen compounds
and oxides of nitrogen.
" 209~222
- 10 - BU 46~47
For this embodiment, too, the combustion may be
carried out in one of the above described combustion
chambers.
A tube reactor is preferably used for w~rking up
pyrotechnical material A, whereas a reactor having a
brick lining is used for working up pyrotechnical
material B.
After the controlled combustion of pyrotechnical
material A and B, the crude gases formed are optionally
combined, if the combustion was carried out in separate
reactors, by passing the crude gas formed during com-
bustion of one type of pyrotechnical material into the
other reactor. The crude gas formed in each case during
the combustion, or the combined crude gases, is or are
passed through a high-temperature region in which they
are kept at a temperature of at least 1200-C, preferably
up to 1500~C, over a predetermined period in order to
decompose any organic substances still present. If the
crude gas has a temperature of more than 1200-C as a
result of the combustion, it is sufficient to keep the
crude gas in the reaction region over the predetermined
period without additional heating. This is effected in
one embodiment, for example, by ensuring that the reactor
has a xufficient height so that the residence time of the
ascending crude gas is adequate for complete reaction in
the high-temperature region. In another embodiment, in
which the air iB blown in tangentially, the crude gas
(reaction gas) is passed spirally upwards and thus
remains for a sufficiently long time in the high-
temperature region. If the crude gas is not sufficientlyhot, an external heating ~ource i8 provided in order to
heat the crude gas to the desired temperature. The perlod
of subsequent heating depends on the proportion of
organic compounds and can be readily determined by one
skilled in the art. As a rule, a period of 2 to 10
seconds is sufficient. In order to decompose the organic
compounds, a temperature of at least 1200-C, preferably
at least 1500-C, is required.
The combined crude gase~ which leave the high-
. ~
~ BU 46/47
temperature region contain virtually only ~norganiccompounds, which are partly gaseous ~nd partly in the
form of very small particles. Depending on the com-
position of the crude gas, dry purification and/or wet
purification are carried out. The wet purification can be
carried out before or after the dry purification. Prefer-
ably, the crude gas is first purified under dry con-
ditions and then optionally subjected to wet purifica-
tion, depending on requirements. Since the gas which
emerges from the high-temperature region has a very high
temperature, it is cooled to a temperature of below
4~0 C, it being possible at the same time to utilise the
heat. In various applications, cold air can be mixed with
the hot gas for cooling in the course of the process. In
addition, heat may be utilised by using known heat
recovery techniques. An example of this is the connection
to the heat circulation of a heating station. The crude
gas is cooled to temperatures below 400 C or preferably
below 200 C, depending on the subsequent treatment.
After thiC cooling stage, the crude gas is
sub~ected to dry and/or wet purification. As a rule, a
- dry purification is carried out since the compounds
formed by reaction of the components of the combined
crude gases are present in finely divided form. Where the
gas contains a high proportion of gaseous impurities, the
cooling can be followed directly by the wet purification.
However, this variant is less preferable. In the pre-
ferred embodiment, the gas is passed to a dry purifica-
tion stage. In this zone in which the gaB c0018 further,
the compounds present in the crude gas react with one
another. The alkaline compounds, in particular alkali
metal and alkaline earth metal oxides, and the acidic
compounds, in particular oxides of nitrogen, chlorides,
fluorides and oxides of ~ulphur ( S~2 ~ S~3 ), can react to
give salts, which can then be readily separated off under
dry conditions. Thus, nitrate and especially nitrite
salts are formed from the gaseous oxides of nitrogen,
while the gaseous chlorides and fluorides are converted
into chloride and fluoride salts, respectively. Dry
~ ~9~
- 12 - BU 46/47
purification of the crude gas is therefore preferably
carried out first, having the ad~antage that no wash
waters which have to be worked up are produced and that
the resulting solids can be directly reused.
The dry separation of the coarse particles in a
preliminary separator and of the finely divided solids
via fine dust filters may be carried out as in the first
embodiment of the present invention as described above.
Depending on the composition of the pyrotechnical
material A and B, after the fine separation the gas can
be purified to such an extent that the proportions of
particulate material and gaseous compounds are below the
emission limits. It can then be released directly as
waste air. If the gas still contains gaseous impurities,
in particular halogen-containing compounds or oxides of
nitrogen, it is sub~ected to a wet purification after the
dry purification. As a rule, however, wet purification is
no longer necessary if the material to be burned is
suitably chosen.
In case, it is necessary to carry out a wet
purification, this can be done as described above for the
first embodiment of the process of the present invention.
The process according to this second embodiment
of the invention can be ad~usted in a variable manner to
the conditions which prevail dùring the combustion of
different p~rotechnical materials. To carry out the
process as effectively as possible, the type and amount
of the pyrotechnical materials A and B are chosen so that
as high a proportion as possible of the substances
escaping in the crude gas react with one another to give
salts, which are deposited under dry conditions. Thus,
for example, it is advantageous to burn propellant charge
powders which give 10 to 50% of oxides of nitrogen (based
on nitro groups present) during the combustion with
illumination active materials which form a high propor-
tion of magnesium oxide, it being possible to reduce the
proportion of oxides of nitrogen in the crude gas to the
range of 10 to 100 ppm after the dry separation. It is
al~o preferable to burn smoke or irritant materials which
2 ~
- 13 - BU 46/47
have a high content of organic halogen compounds with
illumination active materials or thermite-like mixtures
which contain magnesium. ~he ratios are chosen in each
case so that complete binding of the hydrogen halides by
alkali metal and alkaline earth metal elements is
schieved.
When only one type of pyrotechnical material is
available for disposal, a second additional component
which replaces the other group of materials can be
simultaneously burned. If, for example, only pyro-
technical material A is present, ammonia or amines for
binding nitrite and nitrate salts can be added to this
material during the combustion as a replacement for
pyrotechnical material B. If, on the other hand, only
pyrotechnical material B has to be disposed of,
magnesium, aluminium or iron powder can be added as
pyrotechnical material A during the combustion, in order
once again to promote salt formation.
The invention furthermore relates to an apparatus
for working up pyrotechnical material, which is
characterised by (A) one or more reactor(s) for the
controlled combustion of pyrotechnical material; (B) a
heat exchanger unit for cooling the crude gas to a
temperature of below 400-C; (C) a preliminary separator
for separating off coarse particles; and (D) one or more
fine dust filters.
Optionally the apparatus of the present invention
can additionally include (E) a scrubbing apparatus for
scrubbing the crude gas and (F) one or more ab~orption
unlt(s), the individual components (A) to (F) being
capable of being connected to one another in any manner,
depending on requirements.
Owing to the modular concept, the apparatus
according to the invention is sultable for working up
; 35 various types of pyrotechnical material, such as, for
example, signal and illumination pyrotechnics, propellant
charge~, rocket propellant charges, smoke active
materials, coloured smoke and irritant~. Depending on the
type and state of aggregation of the compounds formed
2 ~ !9 ~ ~ ~ 2
- 14 - BU 46/47
during the controlled combustion, individual components
or all components of the apparatus according to the
invention can be connected to one another in succession.
In a preferred embodiment, as is suitable in particular
for working up signal and illumination pyrotechnics, the
components (A), (B), (C) and (D) are connected in series.
In another preferred embodiment, as is suitable in
particular for working up smoke ac~ive materials, propel-
lant charges and rocket propellant charges, the
components (A), (B), (E) and (F) are connected in series.
If controlled combustion results in a very heterogeneous
system which contains both gaseous impurities and very
small particles, the components (A) to (F) are preferably
connected in series. ~or very economical working up,
component (B) is used in all cases since in this way the
energy formed during the combustion can be recovered and
put to a sensible use.
The apparatus according to the invention is now
described in detail with reference to Figures 1 to 3.
Figure 1 shows an apparatus which is particularly
suitable for working up signal and illumination pyro-
technics. It has a tube reactor 1 in which the flares and
illumination elements are burned in a controlled manner.
The tube reactor 1 is a reactor of heat-resistant steel
without an internal lining. The flares and illumination
elements are supplied to the tube reactor via a batchwise
feed apparatus 4. Furthermore, the tube reactor i 8
supplied with fresh air via a pipe 3 via tangential
nozzles 5. The crude gas formed in the combustion ls kept
at above 1200'C for at least two seconds and then fed via
the pipe 7 into the heat exchanger unit 9. The hot gas
heats water which is fed into an heat exchanger and can
then be fed into the hot water or heating clrculation of
a heating station. The gas leaves the heat exchanger unit
9 via the pipe 11 and is fed into a multicyclone 13,
where coarse particles are separated off. The coarse
particles can be collected batchwise via a cellular wheel
sluice 12 in storage containers 14. From the multi-
cyclone, the gas is passed into fine dust f~lters 15 (A,
-' 2~99222
- 15 - BU 46/47
B, C, D), where fine dust partl~les are ~eparated off.
The fine dust filters are cleaned from time to time,
deposited solids being removed via discharge screw 16 and
collected in storage containers 18. From the fine dust
filters 15, the pure gas is then released into the
environment via the pipe 17. Pipe 17 is provided with a
connection 20, to feed the gas into a wet separation
step~ if necessary.
Figure 2 shows a further preferred embodiment in
which alternatively a tube reactor lOl or a trough
reactor 102 can be used for the controlled combustion of
the pyrotechnical material. The pyrotechnical material
which is to be burned can be supplied to the tube reactor
lO1 via a batchwise feed apparatus. When the trough
reactor 102 is used, the material is supplied continu-
ously via the hopper 106. Both reactors lOl, 102 are
connected to the heat exchange system 109 via pipes 107
and 108, respectively. The gas is passed into the heat
exchange system as in the embodiment described in Figure
1 and then via pipe 111 into the multicyclone 113 and
from there into the fine dust filters 115 (A, ~, C, D).
Parts having the same function as in Figure l are desig-
nated in Figure 2 by the same reference digits, increased
by the number 100. In this embodiment, the gas emerging
from the fine dust filters 115 can also be sub~ected to
wet purification. For this purpose, it i~ fed via con-
nection 120 and a pipe 119 into a rotary scrubbing unit
121 and supplied from there to one or more absorption
unit~s) 123 which are provided with suitable wash vessels
124. The wa8h vessels 124 can be worked up batchwise. For
this purpose, a neutralising solution is pumped from the
neutralisation ves~el 126 via a pump 125 into the liquid
present in the wash vessels. The neutralised solution is
then released lnto the buffer tank 127. After the wet
purification, the gas has ~uch a small proportion of
impuritie~ that it can be released into the environment
via pipe 128.
In Figure 3 a further embodiment of the apparatus
of the present invention is ~hown. Parts having the ~ame
'' 2~9~2%~
- 16 - BU 46/47
function as in Figure 2 are deslgnated in Figure 3 by the
same reference digits, increased by the number 100. In
the apparatus of the present invention as shown in Figure
3, the controlled combustion of pyrotechnical material A
and pyrotechnical material B is carried out in two
separate reactors. Pyrotechnical material where pre-
dominantly alkaline reaction products are formed is fed
by means of feed apparatus 204 to the tube reactor 201
and is subjected to controlled combustion. The tube
reactor 201 is a reactor comprising heat-resistant steel
without an internal lining. Fresh air is fed to the tube
reactor 201 via a pipe 203 via tangential nozzles 205.
The pyrotechnical material where predominantly acidic
reaction products are formed is fed to the trough reactor
202 via the loading hopper 206 and is subjected to
controlled combustion. The crude gas formed during the
combustion in the tube reactor 201 is passed via pipe 207
to the trough reactor 202. The crude gases mix with one
another in a high-temperature zone formed in the trough
reactor 202 and are kept at above 1200-C for at least two
seconds and fed via pipe 208 together into the heat
exchanger unit 209. The hot gas heats water which is fed
into the heat exchanger and which can be passed into the
hot water or heating circulation of a heating station or
for internal heat utilisation. The gas leaves the heat
exchanger un~t 209 via the pipe 211, pipe 211 having
dimensions such that the gas covers a sufficient distance
to permit a reaction of the alkaline and acidic com-
pounds. The gas is fed via pipe 211 lnto a multicyclone
213, where coarse particles are separated off. The coarse
particles are removed batchwi~e via the cellular wheel
sluice 212 and collected in storage container~ 214. From
the multicyclone, the gas is passed into fine dust
filters 215 (A, B, C, D), where fine dust particles are
separated off. The fine dust filters are cleaned from
time to time by blowing compressed air onto them, the
fine dust being fed via the discharge screw 216 into
storage container 218 and being collected there. After
leaving the fine dust filters 215, the gas can either be
2~9g22'~
- 17 - BU 46/47
released into the environment via plpe 217 ~f it is
sufficiently pure or fed to a wet purification ~tage, in
which case it ls fed via pipe 219 ~nto a rotary scrubbing
unit 221. After the rotary scrubbing, it i8 passed
through one or more absorption unit(s) 223 which are
provided with suitable wash vessels 224, after which the
gas has such a low content of impurities that it can be
released into the environment via pipe 228. For disposal,
a neutralising solution is pumped from the neutralisation
vessel 226 via the pump 225 into the liquid present in
the wash vessels 224, and the neutralised solution is
then discharged into the buffer tank 227.
Apart from these three plants described, the
individual elements of the apparatuses according to the
invention can be connected in series in any manner,
depending on the pyrotechnical material used and on the
resulting composition of the flue gas.
According to the invention, processes and an
apparatus are provided in order to work up various types
of pyrotechnical material safely and without pollution of
the environment, valuable material and energy being
recovered at the same time.
The invention is illustrated by the following
examples:
Example 1
In a reactlon chamber, propellant charges were
first reacted at a flow rate of 100 kg/h. The propellant
charges were burned with excess air at a temperature of
about 800 C without additional heating. Of the 13.7 kg/h
of nitrogen introduced as part of the propellant charges,
5~ was converted to NO2. The waste gas contained
6294 mg/m3 (S.T.P.) of NO2, based on a waste gas contain-
ing 11% of oxygen. In a second reaction, S0 kg/h of
propellant charge were disposed of together with 100 kg
of active material of the signal salt of the green hand
flare. Although the lntroduct~on of nitrogen in the
mixture to be disposed off wa reduced only from
13.7 kg/h to 11.16 kg/h, on the other hand the output of
2~9~222
- 18 - BU 46/4~
oxides of nitrogen decreased from 6294 m~/m3 (S.T.P.) to
200 mg/m3 (S.T.P.) (98 ppm by volume).
As a result of the reducing effect of the actlve
materials reacted, the NO content of the waste gas
initially decreased as a result of the increasing
reaction temperature. On further cooling of the gas,
formation of nitrates and especially of nitrites took
place on the way from the heat exchanger to the coarse
filter, the said nitrates and nitrites in turn reacting
with alkaline earth metal compounds present in the gas to
form alkaline earth metal nitrates and nitrites.
Example 2
The propellant charge flow rate used in Example
1 (about 50 kg~h) was reacted in a reaction chamber
together with a combustion salt which consisted of 52% of
magnesium powder and 48% of NaNO3.
The thermite-like mixture reached temperatures of
more than 2000 C during its reaction and simultaneously
led to lncreased reduction of the NOX groups formed
during the combustion of the propellant charges. As a
result of the reaction temperature being higher than in
Example 1, it was possible further to reduce the NOX
content in the ~as.
Example 3
Irritant elements whlch contained 64% of
hexachlorocyclohexane, 34~ of aluminium, 1.25~ of liquid
paraffin and 0.75~ of chloroazetophenone were reacted
together with combustion salt for flares, whlch salt
contained 75% of KNO3, 15% of magnesium and 10% of
iditol. 50 kg cf the irritant active material contained
23.5 kg of chlorine. The chlorine of the irritant reacted
during the oxidative process in primary and secondary
reaction steps with formation of potassium chloride and
magnesium chloride in addition to aluminium chloride.
Without the addition of further chemical poten-
tials, it was possible, by pairing the two sub~tances to
be disposed of, to reduce the HCl content of the waste
~ ~992~s~
- 19 - BU 46/47
gas to s 5 mg/m3 ~S.T.P.), based on the pure gas.
Example 4
75 kg~h of propellant charge were burned with
50 kg of fuel oil in a separate reaction chamber 1. The
resultin~ crude gases reached a temperature of more than
1200~C. 10~ of the nitrogen present in the propellant
charge were converted to NOX. The resulting crude gas
flow, which contained 2009 m3 (S.T.P.)/h, corresponding
to 2050 mg/m3 (S.T.P.) of NOX, was fed completely or
partly to a reaction chamber 2 in which propellant
char~es according to Claim 1 were reacted. The NOX fed in
with the crude gas was further reduced analogously to the
reaction of Example 1 by the reducing and catalytic
effect of the pyrotechnical propellant charges and
combined in the remaining part with the oxidic dusts to
give a content of nitrites which was effective for the
process gas purification. By splitting the process gas
stream fed into the reaction chamber 2, it was possible
to control the process gas stream from reaction chamber
2 in such a way that the NOX values of the resulting pure
gas corresponded to the standards < 200 mg/m3 (S.T.P.)
with 11% of ~2 in the waste gas.
Example 5
Propellant charges were burned continuously in a
reaction chamber with the addition of combustion air,
supported by an oil or gas burner. At the same tlme,
powdered reaction products of the disposed pyrotechnical
active materials which contained potassium oxide,
magnesium oxide, barium oxide, etc., were introduced into
the reaction zone. These reactive dusts were thoroughly
mixed with the crude gas and discharged via an after-com-
bustion chamber. The dusts further increased formation of
N2 from the nitro groups of the propellant charges and,
during the subsequent removal of dust from the gas at
temperatures below 200 ~, aqain led to the formation of
nitrites/nitrate~ and thus to the reduction of the NOX
content of the process gas.
