Note: Descriptions are shown in the official language in which they were submitted.
S6568
GAS sLAsT ATTENUATION WITH
RECIRCULA~ION OF GAS AND COOLING THEREOF
The present invention is concerned with a process, and
the devices for implementing it, which assures the suppression
of harmful factors and permits the elimination of at least the
majority of the ecologically objectionable pollutant elements--
noxious or undesirable due to their toxicity, their odor, and
their opaqueness--contained in the gas or liquid wastes discarded
by installations manufacturing mineral fibers, and which also
assures reduction of the noise produced by these same installa-
tions.
The invention is concerned with installations for
the manufacturing of fiber blanket, mat padding, or boards of
mineral fibers and especially glass, agglomerated by thermosetting
or th~rmoplastic binders, which coat the fibers and/or bring
about close binding between fibers in the finished product.
The binders commonly used in this type of manufactur-
ing have a base consisting of pure or modified phenoplast or
aminoplast resins, since these present advantageous character-
istics for the manufacturing of agglomerated fibrous products.
They are thermohardenable, soluble or emulsifiable in water,
they adhere well to the fibers, and are relatively low in cost.
Generally, these binding agents are used dissolved
or dispersed in water to which certain ingredients are added,
in order to form the binder which is sprayed on the fibers.
Under the effect of the heat to which they are subject-
ed during the fiber products manufacturing processesl these
binders release toxic volatile elements having a perceptible
pungent odor even at very weak concentrations, such as phenol,
formaldehyde, urea, ammonia, and decomposition products of
organic mateeials. ~
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Other binders are used for certain applications due
to their very low cost. Certain extracts of natural products
are hardened by drying and cross linking, such as occurs with
linseed oil upon oxidation. Others are thermoplastic, as for
example bitumen. During the fiber binding process~ they are
all, at least to some extent, increased in temperature and to
a temperature sufficient to cause the release of volatile ele~
ments, noxious or otherwise undesirable, among other reasons,
due to their odorO
In the text below, the word "binder" will be used
to designate any one or all of the binding products mentioned
above, whether they are used in liquid form, dissolved or sus-
pended in water or in other liquid, or in an emulsion.
The invention relates to that part of the installa-
tion for manufacturing agglomerated fibrous materials calledthe fiber collecting or forming section, which is situated imme-
diately after the fiber production apparatus, and in which the
following operations are carried out primarily:
--the conveying of the fibers from the fiber produc-
tion apparatus to the mat or blanket forming equipment;
--the application of the binder to the fibers, the
binder generally incorporating pollutant elements;
--the formation of the blanket on the fiber collect-
ing device, for which purpose the collecting device generally
consists of a perforated belt;
--the cooling of the fibers and of the gases used
for attenuating or guiding the fibers, such cooling general-
ly being accomplished by air induced by the gases;
--the separation of the fibers from the gases and
induced air by suction of these fluids through the blanket being
formed; and
--the evacuation outside of the installation of all
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the elements not re~ained by the fiber blanket or the mat being
made.
It is in the fiber collecting or forming section that
large quantities of gases and water have contact with the bind~
er whîch contains the pollutant elements, and are contaminated
according to a pollution process which is common to all known
processes for the manufacture of blankets, mats, or boards o
fibers agglomerated by a binder~ and which will nol~ be describ-
ed.
a) The pollution of the gaseous effluents takes place
according to the following process:
The binder is projected into the current made up of
fibers and gases, coming from the fiber production apparatus,
the binder being present in the form of clouds of fine droplets.
Some of this binaer is entrapped by the fibers, some is unavoid-
ably deposited on the walls of the installation, and finally some
is found in the gases or fumes in the form of fine droplets and
in the form of vapor.
Thus two fluid contamination modes coexist, the one
consisting of contamination by droplets of the binder and the
other consisting of contamination by vapors of the binder. In
the binder application, the binder atomization or dispersion
devices used furnish particles or droplets within a very wide
range of diameters. The finest droplets are not entrapped by
the fibers and are drawn through the blanket being formed by
the gaseous cuTrent, in which they are present in suspension.
The droplets of binder deposi~ed on the fibers du~ing
the binder application are subjected to the kinetic effects of
the gaseous current passing through the blanket being formed.
A large quantity o droplets is extracted from the fibers, mi-
grates through the blanket, and is found in suspension in the
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exhausted gases.
Finally, the desire to obtain a homogeneous distribu-
tion of the binder in the blanket makes it necessary to disperse
the binder in the fiber and gaseous current in an area situated
near the fiber production apparatus, where this current still
has a well-defined geometric form but where i~s temperature may
still be high enough so that some o the binder, or at least
its most volatile components, are evaporated. These pollu~ant
vapors mix with the gases and contaminate them.
In the text below, the word "fumes" will be used ~o
designate the gaseous effluents which pass through the fiber
blanket and are evacuated ou~side of the collecting unit, i.e.,
the gases used for attenuating or guiding the fibers, the fluids
;nduced by these gases, and the pollutant elements in the form
of droplets or vapor suspended in these fluids. It is to be
understood that various features of the invention, such as treat-
ment steps and components of the apparatus, may be employed with
"fumes" having a wide range of compositions and pollutants. It
is preferred to treat all components of such fumes, but vari-
ous features of the invention may also be employed with gasesoriginating in fiber production operations in which ~he gases
have pollutant components, whether or not the pollutants have
their origins in fiber binders.
b~ The functions performed by the water in a fiber
collecting unit make a large degree of pollution inevitable in
any installation in which binders are used.
In operation, water is used:
--tl~ to dilute and carry the binder when the latter
is used in liquid form;
--t2) to wash or scrub the fumes, an operation which
consists:
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--(2a~ of causing the largest possibl~ amount
of pollutants contained in the fumes in the form of droplets
or vapor to be captured by the droplets o the scrubbing water,
thus causing the pollut~nt charge of the fumes to be transferred
~o the wash water;
--(2b) of capturing and entraining on the walls
o the collecting unit ~he fibers suspended in khe fumes;
--~3) to ~ash the di~ferent parts of the collecting
înstallation tperforated belt, ~ume flues, etc.~ in order to
evacuate the bincler and the fibers deposited therein.
During these operations the wash water is charged with
binder components which are soluble, insolubleJ or în the vapor
state, and the concentration o pollutant elements may reach
high values.
The oregoing description of the manner in which the
fumes and the water are con~aminated i5 based on an interpreta-
tion of measurements and observations made in actual manufactur-
ing installations.
Data derived from such measurement and observation
is herein given by way of information; but it will be understood
that other data and explanations may be found and that the inven-
tion is not limited by the data given.
In all installations for the manufacturing of agglomer-
ated fibrous products, regardless of the fiberization process
used, the effluent pollution described above involves consider-
able quantities of effluents.
In installations equipped with devices for attenuating
fibers by blowing, in which the material to be attenuated is
transformed into fibers by means of high-energy jets, the quantities
of fumes discharged into the atmosphere are--for the best known
5.
~LOS1~568
processes--on the order of magnitude of the following values:
--100 Nm3 per kilo of fibers for the process described
in the Slayter U.S. Patent No. 2,133,~36;
--300 Nm3 per kilo of fibers for the AEROCOR process
(Stalego U.S. Patent No. 2,489,243);
--70 Nm3 per kilo of fibers for the SUPERTEL process
(Levecgue French Patent No. 1,124,489 and U.S. Patents Nos.
3,114,618 and 3,285,723);
which, for large production plants, leads to outputs ranging
from 500,000 to 1,000,000 Nm3/hr. (In these values, Nm3 refers
to the cubic meter volume at standard atmospheric pressure and
room temperature.)
In installations equipped with fiber attenuating de-
vices, in which the material to be attenuated is transformed
into fibers under the effect of mechanical forces--centrifugal
for example--and where a gaseous current is only used as a med-
ium (generally flowing in an essentially horizontal direction,
see hereinafter described Figure 14, for example) for carrying
the fibers produced towards the collecting device--the quantity
of fumes given off is a little less, but nevertheless very impor-
tant: for example, 30 Nm3 per kilo of fibers, for the process
described in Powell U.S. Patent No. 2,577,431, which for a pro-
duction plant results in outputs on the order of 300,000 to
400,000 Nm3/hr.
The quantities of polluted water are pretty much the
same for all processes, and on the order of 1,000 m3/hr. or
more for large industrial installations.
The volume of these quantlties of polluted effluent
has led legislatures first to limit the concentration of phenol
compounds in the effluents discarded in the atmosphere, and
later to prohibit discarding of any pollutants, at least in
certain countries.
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Furthermore, limitations concernin~ the odors or the
opaqueness o discharged effluents have been established in various
countries.
In addition~ installations for the manufacture of
agglomerated ~ibrous products also tend to pollute in another
respect. In addition to toxic or p~mgent-smelling products,
these installations discard substantial quantities o steam,
on the ord~r o~ 20 to 30 metric tons per hour for large plants,
which steam escapes rom s~acks in very opaque plumes.
Noise is another type of nuisance created by installa-
tions for the manufacturing of agglomerated fibrous products.
In these installations, the noise is essentially emitted by two
sound sources--the apparatus for producing the -Eibers and the
fan for extracting the fumes.
Actually, all the equipment for producing fibers mount-
ed in these installations uses jets o-E gases at high speed either
for transforming the material to be drawn or attenuated into fibers
or for directing the fibers produced. It is known that the acous-
tic power level emitted by these jets considerably increases
with the speed of the jets. This level may exceed 100 decibels
adjacent to the fiber production apparatus, where the operators
are required to work. This level is much higher than the level
tolerated by industrial regulations in many countries.
Furthermore, the acoustic power developed by the fume
extraction fan is transmitted along the flues connecting with
the fume exhaust stack. The latter is ordinarily situated outside
the buildings, where i* functîons as an antenna, and radiates
this acoustic power into the surrounding environment. The in-
convenience resulting for the vicinity has caused authorities
in different countries to order the shut-down o certain install-
ations.
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The need ~o reduce or eliminate the pollution produced
--and this at costs low enough not to overly influence the cost
price of the finished product--is pressing. Numerous investiga-
tions have been carried out on this problem, and certain solu-
tions ha~e been developed.
The process accordi.ng to the invention is characteriz-
ed by the fact that the fumes ~as hereinabove d~fine~) are par-
tially recyclecl, so as to C~llSe them repeatedly to trav0rse the
blanket or mat being ormed. The process according to the inven-
tion is also characterized by the fact that the majority of theheat contrihutecl by the gases coming from the fiber production
apparatus and the attenuated fibrous material is transferred
to the wash water, by the fact that the wash water is cooled,
by the fact that the fumes are washed in water after they have
tra~ersed the blanket or mat and the fiber collecting de~ice
in order to transfer ~o the water some of the pollutant products
contained in these fumes, by the fact that the non-recycled part
of the said fumes is puriied before evacuation into the atmo-
sphere, by the fact that at least some o the wash water is re-
cycled--a certain quantity of which has been subjected to a treat-
ment for extracting at least a sizable fraction of the pollu-
tant products contained in the wash water--and by the fact that
the solid wastes are subjected to a purification treatment before
final disposal.
The foregoing process effects cooling of the recircu-
lation gases, wl~ich is important in making possible such recir-
çulation. In combination with such cooling of the recirculating
gases, it is preferred also to spray water on the current of
- fibers an~ gases in the receiving chamber, in order to cool the
fiber and gas current. Such water spraying, with resultant cool-
ing of the current, toge~her with the cooling of the recirculat-
ing gases provides for reduction of the temperature of the current
l~S6~8
notw;thstantling ~he substantial absence of induction of ambien~
air by the attenuating blast.
According to a particularly important characteristic of
the invention, the quantity of fumes discarded into the atmosphere
is essentially equal to the quantity of gases flowing from the
attenuating device,
The invention is particularly concerned Wit}l recycling
the majority oF the fumes in the installa~ion, an~l with treating
and evacuatin~ only a small portion o the ~umes--it bein~ poss-
ible for the recycled portion to reach at least 9S~ of the ~otalquantity of fumes ordinarily evacuated into the atmosphere. The
quantity of fumes to be puri~ied before discarding may thus be
less than 5~ of all of the fumes; which even makes it practicable
to use costly puriication treatment, whose effectiveness is
total--as for example burning--without prohibitive energy expen-
ditures.
Another object of the invention is to render insoluble
the thermohardenable resins contained in the water. These resins
are rendered insoluble J according to the invention, by means
of a heat treatment--preferably at a temperature greater than
100 C., and more advantageously ranging between approximately
150 and 240 C., and under pressure.
The application of the above process ~for rendering
resins insoluble) to at least some of the cooling and washing
water is advantageously used to render insoluble the dissolved
binder components contained in the water~ in order to subsequent-
ly be able--by means of known techniques--to extract insoluble
materials and thus to maintain the concentrations o the pollu-
tant constituents in the washing and cooling waters at a level
compatible with the continuous re-u~ilization of these waters
in the installation. The wash wafer thus circula~es in a closed
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circuit and any extarnal rejection of pollutants with the wash
water is eliminated.
Another ob~ect of the invention consists of a heat
treatment ~o which the wash water is subjected--a treatment which
consists of vaporizing it and of heating this vapor to a tempera-
ture sufficient so that the pollutant constituents are trans-
formed into non-pollutant constituents.
The invention also i5 concerned with means for sound
insulation--adJusted to the particular conflguratlon~ shown--to
the devices Eor conveying and guiding the recycled fumes, in
order to reduce the nolse emi~ted by these devlces, and with a
particular arrangement of the apparatus for evacua~ing the non-
recycled fumes into the atmosphere, which reduces the noise
emitted by this apparatus in the surrounding environment.
Broadly speaking, and in summary of the above, ~he
present invention overcomes the problems of the prior art by
providing a method for manufacture of fibers from thermoplastic~ ;
- material comprising attenuating fibers from the material and
entraining the fibers in a gaseous current, delivering the
current and the entrained fibers into a forming section hav~ng
a foraminous flber collectlng device at a boundary of the forming
section through which the gas of the current passes and on which
the fibers collect to form a blanket, recirculating gas from
the downstream side of the collecting device to and through the
forming section and the collecting device, and cooling the re-
circulating gas in the flow path between the collecting device
and the forming section.
The above method may be carried out in equipment for
manufacture of fibers by attenuation of thermoplastic material
and entrainment of the fibers in a gaseous current, comprising a
for~ing section having an lnlet for a current of the gas and
the entrained attenuated fibers, a suction chamber, a foramlnous
fiber collecting device dlviding the suction chamber from the
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forming section, a suction fan having i~s inlet in communication
with the suction chamber and it~ outlet connected to provide
for recirculation of gas ~rom the suction chamber through the
forming section and through the foraminous fiber collecting
device, and means for cooling the recirculating gas stream in
the recirculation ~low path between the foraminous fiber
collecting device and the forming section.
Other ob~ects and advantages of the invention, includ-
ing in particular numerous specific advantages for the recycling
of fumes, w-lll be given and explained more completely below.
The drawings illustra~e several preferred embodiments
of the invention, all of the figures being at least in part
diagrammatlc and in general showing elevational or vertical
sectional views.
Figure 1 illustrates a conventional fiber collection
installation of a -type to which the present invention is applica-
able.
Figure 2 similarly shows an installation of the type
represented in Figure 1, but in which the walls defining the
~O receiving chamber are extended up to the fiber production device.
Figure 3 shows a fiber collection installation of the
general kind shown in Figures 1 and 2, but modified by the
addition of equipment according to the present invention.
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Figure 4 shows another embodiment of an installation
according to the invention.
Figure 5 shows another embodiment of a ume washing
chamber which may be employed in various installations.
Figure 6 depicts the evolution of the efFiciency level
for the insolubilization treatment based on treatment temperatures
and times.
Figure 7 shows a set-up providing for treatment of
wash waters by heating under pressure, as is contemplated by
the invention.
Figure 8 shows a set-up in continuous operation for
treating the waters.
Figure 9 shows a set-up providing for one of the solid
waste heat treatments of the invention.
Figure 10 shows a set-up pro~iding another solid waste
treatment process.
Figure 11 represents a complete fiber collection install-
a~ion used for the manufacture o fiber glass boards, made accord-
ing to the invention.
Figure 12 shows an embodiment of the invention as appli-
ed to another fiber glass manufacturing process.
Figure 13 shows another embodiment of the invention
adapted to a process or the manufacture of minera] fibers by
blowing.
Figure 14 shows another embodiment of the in~ention
adapted to a process for *he manufacture of mineral fibers, and
especially o slag.
6568
Figure 1 shows a fiber collection installation of
known type to which the invention may be applied. This installa-
tion comprises a fiber production device, represented by ll,
of a known type such as is ordinarily used in installations
for the manufacturing of agglomerated or bonded fibrous panels
or boards, in which the material to be attenuated is subjected
to the action of a centrifugal or aerodynamic force, or to a
combination of the two. The aerodynamic force is applied to
the material to be attenuated or to the fibers by means of
gaseous jets which are generally at a high temperature and high
speed. An example of such e~uipment is shown in Levecque U.S.
Patent No. 3,285,723. The fibers produced leave device 11,
dispersed in a current 12 of fluids generally in the gaseous
state formed by high-energy jets and the air or other gases
which they induce from the surrounding medium, a current which
envelops the fibers and directs them, in the form of a stream
with fairly well-defined contours, towards the collection device.
The equipment further includes a zone for application
of binder, placed in the path of the fiber and gas current,
between the fiber production device ll and the collection device,
in which atomizers 13 disperse the binder, in the state of
a cloud made up of fine droplets, into the fiber and gas current,
A large proportion of these droplets intercepts the fibers
and clings to them, the remainder being present in suspension
in the gases accompanying the fibers either in the form of
droplets or in the form of vapors.
A fiber distribution device which may be any one of
several known types, indicated diagrammatically at 14~ placed in
the path of the fibers and the gases 12, either between the pro-
duction device ll and the binder application zone or between the
binder application zone and the forming section~ as is shown in
Figure l, which by imparting an oscillating movement to the
12-
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~ 56S~8
current of fibers and gas or by deforming this current, makes
it possible to distribute the fibers on the collection surface
so as to form a blanket whose weight per unit of area is essen-
tially uniform.
The collection surface is provided by an endless per-
forated belt 15 r on which the fibers accumulate to form the
blanket 23.
A chamber 16, placed beneath the perforated belt,
in the area where the fibers are deposited and the blanket or
mat is formed, i.e. the area of the forming zone or sectionr
and in which chamber a pressure reduction or negative pressure
created by a fan 19, causes all of the gases accompanying the
fibers along their path between production device 11 and per-
forated belt 15 to traverse the blanket being formed.
Vertical walls 21, which extend from the perforated
belt 15 to a level near the fiber production device 11 r and
which mark off the area where the blanket is formedr define
a section or chamber 22, surrounding the current of fibers and
gas, open at its upper end, in an area near the fiber production
device. This is commonly desighated as the forming "hood".
A fan 19, provides a negative pressure in chamber
16 sufficient to force all of the gases accompanying the fibers
(as they are being deposited in the forming section) through
the blanket being formed, and evacuates the fumes to the atmos-
phere through stack 5.
It has already been mentioned that the quantitiesof fumes to be evacuated from a forming section of the type
described above are considerable. In effect, in the fiber produc-
tion devices of these installations, the drawing and attenuation of
13.
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the material to be Eiberized, or the guiding of this material,
or the guiding of the fibers, is achie~ed by gaseous jets, which
have a very high output and speed.
This speed, w~lich is generally greater than 100 meters
per second, is desirable or the formation of the fibers but
is much greater than the speed necessary--in order to form an
appropriate blanket--as the fibers and gases arrive at the per~orat
ed belt 15, which latter in general need not exceed 10 meters
per second. In fact, it is necessary to substantially slow down
the jets coming from the fiber production device. This is achie~-
ed by transferring some of the momentum of these jets to the
ambient fluid in which they flow. Portions of the ambient fluid
are induced and accelerated in the direction of the jets~ and
mixed with the jets. It is this mixture of jets from the fiber
production device and the induced fluid which constitutes the
gas current accompanying the fibers.
The induction of surrounding fluid by the jets coming
from the fiber production device is a well-known phenomenon char-
acteristic of any jet flowing in the open air, or in a chamber
containing a fluid. Fluid mechanics teaches us in effect that
such a jet induces important quantitîes of surrounding gas, and
that these quantities of induced gas flow increase with the out-
put of the jet and the length of its course in the ambient gas.
However, since the induction phenomenon is a progressive pheno-
menon, the drop in speed of the inducing jet is only significantafter this jet has traveled a sufficient distance through the
ambient gas.
In installations of the type described above, in order
to provide a speed of the current of fibers and accompanying
gases, upon arrival at the collection belt 15, equal to the value
given above (on the order of or less than 10 meters per second),
14.
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the length of the path followed by this current from the fiber
production device 11 to the belt 15 is generally greater than
2 or 3 meters, and the quantities of gases which the jets from
the production device ll haYe induced in this distance, and which
traverse the belt 15, are at least equal to 10 OT 20 times the
quantity of gases constituting the jets issuing from the iber
production device 11.
In addition to the slowing down which must be imparted
to the current of fibers and accompanying gases, in order that
the blanket be formed under good conditions J it is necessary
that the 10w directions of the ibers and the gases be parallel
and oriented in the general direction of flow from the fiber
production device to belt 15.
In order to further explain the matter, the current
or stream 12 of fibers and accompanying gases may be divided
in segments, limited by sections perpendicular to the direction
of flow, i.e., sections lying between lines M, N, 0, and P.
In any segment such as that marked off by section lines
M and N for example, the stream maintains a well-determined direc-
~0 tion and undergoes a well-determined loss of speed.
These two factors--direction and reduction in speed--
~ill have the desi~ed characteristics in each segment, if the
current or stream can uniformly induce along the periphery of
the segment all the quantity of fluid necessary--this being pro-
portional ~o the product of the fluid mass constituting thecurrent at the entrance at line M times the relative speed re-
duction undergone by the current upon crossing the segment con^
sidered, for instance the segment MN.
This relati~e speed reduction is equal to the differ-
ence between the speed of the current entering at line M, and
15.
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the speed of the current leaving at line N, related to this firstspeed~
If foT each of the current segments between the fiber
production de~ice and the collection belt the ambi~nt air or
gases can supply the quantity of gases necessary ~or the direction
and slowing down of the current to have the desired charac~eris-
tics3 an induced surrounding gas flow will be established along
the current of fibers and accompanying gases and in the direction
from production device 11 to the collection belt lS. This flow
is represented on Fi~ure 1 by lines 27.
In fiber forming and collecting installations of the
type represented in Figure 1, all the gas induced by current
12 is formed by the atmospheric air entering chamber 22 through
opening 28 which is of large dimensions near fiber production
device 11.
Figure 2 shows a configuration of the fluid flow in
a forming chamber when the surrounding medium cannot freely supply
the jets coming from the attenuating device with all of the gases
that they may induce; this configuration is given by way of example
in order to clarify the description.
Figure 2 represents part of the collection installation
containing a fiber production device 11, from which a current
of fibe~s and gases 12 flows, a binder application device 13,
a fiber distribution device 14, a collection belt 15, and a suc-
tion chamber 16 into which fumes 29 flow a~ter they have travers-
ed the blanket 23 being formed. All of these elements are iden-
tical to those in Figure 1, However, in Figure 2, walls 21 defining
receiving chamber 2~ are extended up to fiber production device
11, so as to extensively reduce the opening 28 through which
chamber 22 communicates with ~he atmosphere, and consequently
the quantity of atmospheric air entering this chamber.
16.
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Thus, if in any segment of current 12, and especially
segments such for example as ~, (situated in a zone near the
fiber production device ll--i.e., near the ejection orifices
of the guiding or attenuating jets for the material to be fiber-
ized, or near the guiding jets of the fibers, and therefore inthe region where the s~eeds of these jets are the highest) the
surrounding meclium cannot supply current 12 with all the gases
that the current may induce~ the segments of current 12 situated
downstream, sush for example as OP, tin which current 12 has
a slower speed) will furnish the lacking quantity.
Gas currents 30, emanating from the downstream zones
of the current or stream 12 itself, will rise along walls 21
towards the upstream zones at higher speeds, will be picked up
by the current and will be reaccelerated in the general flow
lS direction of this current. Thus, the eddies represented by 31
will appear and develo~ between the boundaries of current 12
and the walls 21 of the chamber. The intensity of these eddies
increases with the quantity of fluid that the surrounding medium
has not been able to furnish. Their direction of circulation
is such that the fibers which they extract from the blanket 23
being formed and which they carry, are directed along walls 21
of the chamber towards the fiber distribution device 14, the
binder application devices 13, or the fiber production device
11 .
If the quantity of atmospheric air entering the re-
ceiving chamber of an installation of the type shown in Figures
1 and 2 is reduced to a value much less than the quantity of
air that the current can induce, the intensities of eddies 31
may be sufficient so that the fibers that they carry cling to
the fiber distribution and binder application devices, disturbing
the smooth functioning of those devices. These eddies also have
the effect of disorganizing the blanke~ 23 being formed, as is
17.
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indicated in Figure 2.
The industrial use of installations of this type shows
that the phenomenon whereby the fibers are driven upwards may
be acceptable as long as the quantity of air entering the cham-
ber is no less than 60 or 70~ of the necessary quantity. Belowthis value, operation is no longer industrially practicable.
If it is desired to further reduce, or totally elimi-
nate, the quantity of atmospheric air entering the chamber,
the turbulence in the chamber would be such that the fibers
could not be deposited on the collection belt.
One of the objects of the invention is to furnish
a process making it possible to considerably reduce the quantity
of atmospheric air entering the forming section, while preserv-
ing the conditions suitable to the formation of the blanket.
This process consists of using as induced fluid, not
the atmospheric air, but some of the fumes taken from the outlet
of the exhaust fan, i.e., returning to or recycling in the form-
ing section some of the fumes that are withdrawn from this section.
A set-up permitting the implementation of this process
is represented in Figure 3. The upper part of receiving chamber
22 is closed by a cover 32 containing an orifice through which
current 12 of fibers and accompanying gases coming from fiberi-
zation device 11 penetrates forming section 22. The edge portion
33 of the cover 32 is tangential to current 12 and are of such
a profile as to facilitate passage of the above-mentioned current.
For the sake of operating convenience, cover 32 may
be placed at a distance ~ from fiberization device 11.
The set-up in Figure 3 consists of a washing chamber
17, placed downstream from the suction chamber 16 and generally
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.'105~ 8
larger in section than the latter chamber, equipped with appara-
~us in which fumes 29--i.e., the gases accompanying the fibers
between produc~ion de~ice 11 and collection belt 15, and the
- pollutants in suspension--are placed in contact with a washing
fluid, in particular water. In this washing chamber 17, the
fumes are separated from a portion of t}le elements that they
contain in suspension--the latter elements essentially consist-
ing o~ fibers and the binder with which they are charged upon
passing through the zone where binder is applied and the ~iber
blanket is formed. In contact with the washing water, the fibers
contained in the ~umes retain droplets of water and subsequently
have a tendency to be deposited by gravity on the bottom of cham-
ber 17, this phenomenon being moreover accelerated by the abrupt
reduction in speed of the fumes as a result of the variation
in the flow section along their path of tra~el from chamber 16
to chamber 17. Some of the droplets or pollutant vapors are inter-
cepted by the droplets of washing water, and are dissol~ed by
this water. It is the functioning of these two operations to-
gether which constitutes the washing of the fumes. The water
2~ which was used for washing, and to which at least some of the
pollutant charge of the fumes was transferredl is discharged
through orifice 24.
This set-up also contains a separation system 18, of
the cyclone or electrostatic type, placed between washing chamb-
er 17 and the suction fan 19, in which the fumes are at leastpartially stripped of the water droplets with which they are
charged during the washing operation, and which it is important
to eliminate before entering fan 19. The washing water extract-
ed from the fumes in the liquid form is evacuated from the separa-
tion system through orifice 25.
A collector 26 leads the washing water evacuated throughorifices 24 and 25 towards the treatment zone.
lg .
:1~5~;5~i8
As above mentioned, the current of fibers and qases
passes the binder devices 13 and then fiber distribution device
14. The fibers are deposited on collection belt 15 and the
fumes 29 pass through the fiber blanket 23 being formed, through
chamber 16, through washing chamber 17, and through water sepa-
rating unit 18, and are driven upwards by a fan 19 into flue
34. Some of these fumes are evacuated from the system through
orifice 35. The rest are led through flue 34 towards forming
section 22, in which they penetrate through an opening 36 placed
in a zone situated near the fiber production device 11.
The quantity of gas entering the forming section through
opening lying within the edge portion 33 is equal to the sum
of the quantity of gas coming from production device 11 and
the quantity of air induced by the latter as they pass in the
open air, along the length H. The quantity of gas entering
the chamber therefore increases with the length ~.
For the system to be in equilibrium, it is necessary
that the quantity of fumes evacuated from the system through
discharge orifice 35 be equal to the quantity of gas entering
the system through orifice 33. The quantity of fumes to be
evacuated will thus decrease when the distance H is reduced.
Figure 4 shows a particular embodiment according to
the invention, in which distance H is zero, i.e., in which fiber-
ization device ll--or at least the ejection orifices of the
at~enuating and guiding jets--are situated in chamber or section
22. The quantity of fumes to be evacuated from the system will
be very nearly egual to the quantity of fluids coming from pro-
duction device 11~
The proportion of recycled fumes may thus reach values
equal to at least 96-97~ in this embodiment.
20.
~,
~05~ 8
In the installations built according to the invention
and represented in Figures 3 and 4, the recycled quantities of
gases correspond to the quantities induced by the jets coming
from device 11, and this flow of the fluids through the section
22 will take place in the direction of 1Ow of the attenuating
jets, and therefore in the absence of disturbing eddies. The
recycled fumes essentially follow the current lines represented
by arrows 37.
One o:f the advantages of the invention is based on
the Eact that1 by means of fan 19, currents 37 of recycled fumes
may be provided with a speed that is slightly ~reater than that
of currents 27 of atmospheric air which current 12 of fibers
and gas induces in installations of the type represented in
Figure 1. Thus currents 37 have enough momentum to overcome
the possibility of causing counterflow or "blow-back" of the
fibers back to the binder nozzles 13 and the distributor 14,
as explained above in connection with Pigure 2.
One of the most important advantag~s of the process
according to the invention lies in the fact that the ~uantity
of fumes evacuated from the system may comprise only from 3 to
4% of the quantities ordinarily evacuated (the order of magni-
tude of which has been given above), and in the fact that, with
such a small quantity of fumes, it is practical ~o apply a highly
effective purification treatment notwithstanding that such treat-
ment is costly.
In operation, the invention provides for treating thefumes evacuated through orifice 35 by burning, an operation which
consists of heating the fumes to a temperature sufficient to
burn organic components, preferably greater than 600 C.--beyond
which the pollutants of the fumes, and especially the phenol com-
pounds, are transformed by combustion into non-pollutant elements,
~ ~ S ~ ~ ~ 8
such as CO2 and ll20. This treatment also has the advantage of
destroying odors. As shown in Figure 3, the burning procedure
takes place in device 38, of a known type, consisting of a com-
bustion chamber 39, a burner 40 supplied with a combustible mixture,
` and provided with a grid or any other flame stabilization device
41. The treatment temperature may be reduced to a value ranging
between 300 and 400 C. in the presence of a combustion catalyst.
The puri~ied fumes are discharged to the atmosphere
through stack ~2. At the outlet of stack 42, the temperature
of the fumes is high enough, and due to recycling their output
is small enough, so that the steam contained in these fumes is
not condensed before total dilution of the fumes in the atmo-
sphere. Thus no cloudy plume appears at the outlet of stack 42.
Another advantage of the invention lies in ~he fact
that since the fumes are recycled and subjected to a total puri-
fication treatment, it is not necessary to subject them to a very
complete preliminary washing, which makes it possible to reduce
the dimensions and the in~estments with respect to washing device
17 and water separating device 18 placed upstream of the suction
fan 19.
Installa~ions built according to the invention and
represented in ~igures 3 and 4 consist of a forming section 22
surrounding the binder and fiber distribution devices 13 and 14
making access to the latter devices difficult. During opera-
tion, it may be necessary to provide access to binder nozzle13 or fiber distribution device 14. In order to do this, it is
necessary to open inspection windows which are desirably placed
in the walls of the chamber in a zone situated near the iber
production device 11.
I~ is also contemplated to maintain the pressure in
the forming section 22 equal to or lower than atmospheric press-
~5~5~8
ure, by a few millimeters of water column, in order to prevent
the f~es from escaping from chamber 22 during the recycling of
the fumes~ which still carry pollutants.
l~hen ~he inspection windows are closed, this also makes
it possible to prevent any untimely escape due to sealing defects.
The pressure in section 22 is adjusted to the desired value by
regula~ing ~he negati~e pressure created in chamber 16 by fan
19, in the exemplified embodiment represented in Figure 3.
Another process consists o removing the quantity of
fumes to be evacuated, not from recycling 1ue 34, but ~as shown
in Figure 4) directly from forming sectioll 22, via an opening
43 placed in the walls of the chamber in the zone where it is
necessary to maintain ~he pressure at the desired value. The
fumes are extracted from section 22 by means of a small auxiliary
fan 44 and evacuated through flue 35~ Thus fan 19 is relied
upon only to assure recycling of the fumes. This type of set-
up facilitates more precisely establishing a pressure in the
chamber 22 in the neighborhood of atmospheric pressure.
One of the characteristics of the invention consists
of the fact that it is possible to regulate the flow of the atom-
ized binder through nozzles 13 as a function of the quantity
of binder components in suspension in the recycled fumes, which
are deposited on the fiber blanket when these fumes pass through
it.
In operation9 recycling causes the fumes to make re-
peated and very frequent passes through the fiber blanket being
formed and, although the retaining capability of this blanket
is limited, because the speed of the fumes transversing it is
low, the number of successi~e passes ~around 15 per minute3 is
such that an appreciable quantity of binder components in sus-
pension in the fumes is retained by the blanket. This makes
l~S6Stil~
it possible to reduce to the same extent the quantity of binder
atomized or dispersed by the application devices 13, which per-
mits an increase in the binder efficiency on the o~der of 5~,
an economic advanta~e not to be neglected.
In an installation such as that represented in Figure
1, it is necessary to maintain a specific temperature in the
forming section 22, and thus to evacuate the heat supplied by
the material to be drawn and by the attenuating or ~uiding ~luids.
In operation, since the binder used for bonding the fibers is
usually ~hermohardenable~ under ~he effect of the he~, it under-
goes a continuous evolution which progressively converts it from
the liquid state, in which it is atomized, to the solid state.
If the temperature in section 22 is excessive, during formation
of the blanket the binder may reach a state of evolution suffi-
ciently advanced to alter its power to bind the fibers. Thisphenomenon is sometimes called pregelification, ana this may
be prevented by cooling the forming section 22.
In an installation as represented in Figure l, this
cooling is achieved by induction of atmospheric air, which is
generally at a temperature lower than the minimum temperature
desired in section 22. The quantities of heat brought into the
chambeT by the material to be attenuated and by the attenuating
or guiding fluias and which, depending upon the fiberization
processes used, are on the order o 1,500 to 15,000 Kcal per kilo
of material, are transmitted to the induced air and then to the
fumes, which transfer a small quantity of the heat to the washing
water and exhaust the rest into the atmosphere.
In the installations represented in Pigures 3 and 4,
since the small volume of fumes evacuated ~o the atmosphere only
eliminates a very small quantity of heat, the invention provides
other means for cooling the forming section 22.
24.
~ 5 ~ S~ 8
The foregoing is accomplished by transferring the heat
brough~ into section 22 by ~he material to be attenuated and by
the attenuating or guiding fluids, at least partially to a heat
transfer fluid such as water, by placing the current of fibers
s and accompanying gas or the fumes in contact with t}liS heat trans-
fer fluid. This fluid is discharged, after it has absorbed the
heat brought into section 22, outside of this chamber, and it
is cooled by means of any appropriate system situa~ed outside
o~ the installation.
The heat exchange between the current of fibers and
accompanying gas or the fumes and the cooling water takes place
either by direct contact between fluids or through a heat-conduct-
ing or heat transfer wall. It is known that the quantities of
heat exchanged per unit of time by means of such heat transfer
lS are proportional to the temperature differential between the
fluid to be cooled and the cooling fluid, and also to the area
of the contact surface.
The relatively high speeds of the gases or fumes, with
respect to the dimensions of the installation, permit only short
periods of time for the heat exchange to take place. It is there-
fore necessary that the quantities of heat exchanged per unit
of time be large if sufficient cooling is to be accomplished.
The invention provides processes and devices for achiev-
ing this goal.
One of the processes consists of discharging, outside
forming section 22, the calories brought in by the material to
be attenuated and by the attenuating or guiding fluids, by cooling
the fumes in chamber 16 and in washing chamber 173 where the
~olumes available make it possible to have large surface con-
tact areas between the fumes and the cooling water. This large
contact surface is obtained in several ways: either by dispersing
1~i65~8
the water in the form of ine dro~lets, or by making it flow in
the form o a very thin film, or finally by making the fumes
bubble in the water.
In the arrangement represented in Figure 3, for exam-
ple, atomizers 45 disperse the cooling wa~er in the form of sheetsor curtains of fine droplets, these sheets being generally per-
pendicular to the direction o:E flow oE fumes as indicated at
29. Once the fumes have traversed the fiber blanket being formed,
they enter chamber 16 at a temperature on the order of from 80
to 100~ C. and are cooled by contac~ with the sheets of water
to a temperature on the order of 30 C, The temperature of the
water at the entrance to atomizers 45 is on the order of 15~
to 20 C., according to the capability of the cooling devices
ser~ing to supply the atomizers. By contact with the fumes, the
water is reheated to a temperature on the order of 3Q to 40
C., ac~ording to the flow rate through the atomizers 45.
The recycled part of the cooled fumes, after passing
through separating device 18 and fan 19~ reenters forming section
22 where, by mixing with the gases from fiber production device
11, the recycled fumes cool these gases and the fibers in the
same way as the atmospheric air in the device represented in
Figure 1.
Another exemplary embodiment is represented in Figure
4, in which the water flows over baffles 46 in the form of very
2~ thin films. The current of fumes indicated at 29 flows along
these partitions, licks over the films of water, and is cooled
in contact with the water.
Another exemplary embodiment is shown in Figure 5. In
this set-up~ the current of fumes indicated at 2g emerges through
orifices 47 below the free surface of the water mass contained
in vat 48 placed downstream from suction chamber 16, creatin~
26.
l~)Slt;5~8
in this mass an~l a~ the level of oriEices 47, an intense bubbling--
generating gaseous bubbles whose liquid walls have a large water-
fumes contact sur-face.
Another process consists of directly cooling the current
12 of fibers and gas by projecting water on it, and discharging
this water outside of forming section 22 to thereby remove the
heat brought in by the materials to be fiberized and the attenu-
ating or guiding fluids. The projection of water on the current
thus takes place in the zone where the contact surfaces cannot
be very large since the available space is small, but where the
temperature differential between the fluid to be cooled and the
cooling fluid is large. For example in tl~e embodiment represented
in Figure 3, atomizers 49, placed between fiber production device
11 and binder devices 139 project a cloud of fine droplets of
water against the attenuated fibers and gases of the current
to be cooled.
The droplets reach the current of gas and fibers in
a zone where this current is at a high temperature, which may
reach 600 C., and are immediately vaporizedJ thereby effecting
cooling at high efficiency. The large quantities of hea~--on
the order of 650 to 700 Kcal per kg of water--necessary to va~or-
ize the droplets are taken from the current of fibers and gas,
which consequently undergoes a very rapid cooling. This reduces
the temperature of the current, at the level of binder devices
13, to a value on the order of 100 to 120 C. The vapor produced
is evacuated with the fumes, through fiber blanket 23, into chamber
16 and washing chamber 17, where in contact with the curtain
of water sprays emitted by atomizers 45, the vapor condenses,
transferring its latent heat of vaporization to the cooling water
coming from atomizers 45. This heat is thus discharged from the
system along with the water from the atomizers 45.
~ ~ S 6 ~ ~ 8
The placement of the spray devices 49 for projecting
the cooling water against current lZ, between fiber pro~uction
device 11 and binder nozzles 13, is the preferred arrangement
according to the invention, since in operation this arrangement
has certain special advantages:
First o all, it is in ~his zone that the temperature
diferential between the current to be cooled and the water is
the ~reatest and where the }leat trans~er is consequently the
highest,
The binder is then sprayed on a current of cooled fibers
and gases~ at a temperature that is su~ficiently low (100 to
120 C.) so that breaking down of the binder due to volatiliza-
tion of constituents thereof is very limited or non-existent.
As a result, there is an increase in the binder effi-
ciency of the order of 5%, and a çonsequent reduction in thepollution from the fumes.
Another embodiment is shown in Figure 4, in whirh devices
50 for spraying cooling water against the current of fibers and
gas 12, is placed between binder device 13 and the collection
belt 15. As in the embodiment shown in Figure 3, the cooling
water in the form of vapor passes through the blanket 23 being
formed. This water condenses, transferring its heat to the films
of water flowing over partitions 46 of washing chamber 17.
This water is discharged externally of the installation
by orifices 24 and 25 placed at low points in chambers 16 and
17 and in water separating unit 18, into device 51, in which
the solid particles in suspension in the water, notably fibers,
are separated.
Device 51 may be either a filter, with meshes, of a
known rotating or vibrating type, or a decanter, or a centrifuge,
28.
1~565~8
also of known type,
Th~ ~ater, -free of suspended solid parti~les, is collect-
ed in a tank 52 and, in the embodiment of Figure 3, the water
is then directed, by gravity or by means of a pump 53, into a
cooling station 54. IJpon leaving this station, the cooled water
may be discharged outside or reused in the system.
As shown in Figure 3, station 54 may include a cooling
tower 106, of known type, in which water is cooled by contact
with air. The cooling water is circulated through ~he s~ray
cooling tower by means of a pump 107. The wa~er ~om tank 52
is brought into indirect heat excllange relation to the cooled
water o~ the tower 54 by means o-~ the heat exchanger indicated
at 105, from which the cooled water may be returned to the tank
52. Make-up water may be introduced as by the water supply connec-
tion indicated at 111.
It is preferred to cool the washing water by indirect
heat exchange with the cooling water ~or other cooling fluid)
circulating through the cooling tower 106, because this completely
avoids polluting the air with any remaining volatile pollutants
in the wash water, although the content of such remaining pollu-
tants in many installations is so very low ~for instance, less
than 5~ of the quantity discharged by the gas offtake of a non-
recycled installation such as shown in Figure 1) that it may be
practicable to directly cool the wash water in the spray cooling
tower 106.
An advantage provided by the invention, is that it is
contemplated that no water in liquid state be discharged outside
of the installation, so as not to contaminate the environment
even by the small content of pollutants that the water still con-
tains.
2~.
1~)56568
This implies that the water introduced through nozzles49 or 50 and the washing water circulate in a closed circuit
within the installation.
On the installations represented in Figures 3, 4 and
5, the closed circuit made by the cooling and washing water is
the following:
--The water leaving cooling station 54 is sent via pump
55 to cooling devices 49 and/or 50 situated in chamber 22, and
also to the ~apor condensation devices and fume washing devices
placed in chamber 17, which include either the atomizers 45 as
shown in Figure 3, or the baffles with water film 46 as shown
in Figure 4, or the water may be sent towards the tank 48 shown
in Figure 5.
--The washing water and the condensed vapor, charged
lS with pollutants, fibers, and binder components, flow through orifices
24 and 25 placed at low points in washing chamber 17 and water
separator 18, into a collec~or 26 which leads them towards filtra-
tion device Sl; this separates solid wastes 56 in suspension,
fibers, and insoluble binder components from the washing water.
These wastes are collected on a conveyor 57. Since
the filtered washing water only contains dissolved binder com-
ponents and pollutants, it is sent by gravity or via pump 53 to-
wards cooling station 54.
The applicants have observed that when the washing
water circulates in a closed circuit, it is necessary to maintain
the concentration of the materials dissolved or suspended in
the filtered water below a certain value, this being on the
order of 3 to 4%--computed in unit of mass of dry materials
per unit of mass of water. Above this value, some of the materials
dissolved or suspended in the washing water (essentially microfib-
1~5~5~:;8
ers or micropartlclcs of binder not ca~tured by Eiltration device
51, and soluble binder components) are aeposited on different
parts of the installation. The binder is polymerized, forming
viscous or solid layers which progressively obstruct the washing
water ejection orifices 45, 49 and 50 and also the orifices in
collection belt 15 for the passage of fumes 29. As a result,
there is a reduction in the quantity oE fumes evacuated from the
hood and in the cooling of these fumes, soon leading to shut-
down of the installation.
In order to maintain the concentration of materials
carried in the water below the value which will obstruct spraying
or fume e~acuation, i* is necessary to extract large quantities
of materials -from the washing water. In operation~ a large pro-
portion, on the order of 20 to 30~ of the binder sprayed on the
fibers by nozzles 13 ends up in the washing water, in the manner
already described. For large plants, this makes it unavoidable
that 3,000 to 5,000 kilograms of binder per day (counted in dry
material) will be introduced into the closed circuit for circula-
tion of the washing water3 and it is necessary to extract from
the water quantities of binder identical to those introduced
in order to maintain the concentration at an equilibrium value.
Several extraction processes are possible:
One of these processes consists of treating at least
some of the washing water in a centrifuge, which is capable of
separating from the water solid particles in suspension that
are much smaller than can be handled by filter 51. Thus, as
seen in Figure 3, the water treated by centrifuge 58 may return
to vat 52, as is shown on Figure 3, or more advantageously may
be sent to cooling device 49.
Another process consists of treating the water by the
addition of a flocculant, followed by separating the flocculated
31.
~ s~s~
material.
These t~o proces~es hav~ the disadvantage of essential-
ly extracting from the water only the insoluble materials that
it contains. The dissolved binder, l~hich constitutes the great-
est part of of the materials to be extracted, is not affectedor is affectecl only slightly.
The invention provides several processes for extract-
ing the binder dissolved in the washing water.
One process consists oE using the il~ered or centri-
fuged was}lin~ water to dilute the binding agents upon preparationof the binders applied to the fibers by application device 13.
The filtered ~ater may be removed from any point whatsoever in
the circuit downstream from cooling station 54, or more advantag-
eously downstream from centrifuge 58, as shown in Figure 3, by
means of valve 59.
Another process consists of using the washing water
as a fluid for cooling current 12 of fibers and gas, in chamber
22. The washing water is thus projected against curren~ 12 by
cooling device 49, as shown in Figure 3, or by 50 in Pigure 4.
These two processes have the advantage that they per-
mit the reutilization of some of the binder contained in the
washing wa~er, and it is contemplated by the invention to regu-
late the quantity of binder dispersed by application device 13
as a function of the quantity of binder that the blanket 23 being
formed retains from the water projected by devices 49 or 50,
which permits an improvement in the binder efficiency; but these
processes do not permit extracting from the washing water quan-
tities of dissolved binder sufficient so that the concentration
of this water is maintained below the desired value. It is or
this reason that the invention provides two processes which make
~ 56~8
it possible ~o complete thc ~xtraction of large binder quantities
dissolved in the l~ater circul~ting in the closed circuit.
One of these proc~sses consists of burning a small
portion, on the order of 1 to 5~, of the washing water flowing
into the circulation circuit, in an appropriate device 60. This
device~ represented on ~igure 4, is of known type and contains:
--a burner 61 supplied with a combustible air-fuel mix-
ture;
--an atomizer injector 62) in which the water to be
treated arriving through pipe 63 is projecked in the form of
pressurized droplets into the flame of burner 61, under the effec~
of atomization air 64; and
--a reaction chamber 65 in which~ under the effect of
the heat released by burner 61, the l~ashing water treatment is
carried out. This consists first of all of vaporizing the wash-
ing water and then of raising the vapor produced as well as the
binder components provided by the water to a temperature on the
order of 800 C.--which permits these binder and pollutant com-
ponents to be transformed into non-pollutant elements such as
CO2 and H2O.
The non-pollutant vapor escapes through stack 66 exter-
nally of the installation, at a high temperature--thus preventing
the ormation of a cloudy plume.
The point where the water to be treated is removed
is gene~ally located between pump 55 and the devices 50 and 46,
as is shown on Figure 4.
This process has the advantage of extracting and trans-
forming into non-pollutant elements all the binder components
contained in the treated washing water. It has the disadvan-
tage of requiring a large expenditure o energy and thus of being
very costly. The influence of the treatment cost on the price
:~S65~8
of th~ fibrous products manufactured may be reduced by recovering
some of the quantity of h~at Erom the hig}l-temperature vapor,
in an exchanger producing superheated vapor for various uses.
Thc other process consists of subjecting to a heat
treatment a small portion--on thc order of 1 to 5~--of the flow
of washing water charged with dissol~ed binder circulating in
the circuit, so as to insolubilize the binder, ollowed by sepa-
rating the binder from the water by any appropriate ~neans of
separation such as filtration, flocculation, centrifuging...
In operation, the applicants have observed that if
the water usecl for cooling and washing of the fumes- -and thus,
after filtration, containing the binder or dissolved binder com-
ponents--is maintained at a given temperature for a given period
of time, a proportion of the dissolved binder increasing with
the temperature and the time would be transformed into insoluble
particles and would subsequently be found in suspension in the
water and could then be easily separated from the water.
The proportion of dissolved material--insolubilized
by the treatment--characterizes the efficiency of the treatment.
The treatment temperature has a very important influ-
ence on the efficiency. For example, it has been found that
for a water containing 1% dissolved ~inder component, the treat-
ment efficiency is:
40% if the water is main~ained at 40C. for eight days;
~5 40~ if the water is maintained at 70C. for three days;
40% if the water is maintained at 160C. for three
minutes;
60% if the water is maintained at 180C. for three
minutes;
95% if the water is maintained at 240C. for three
minutes.
34.
~L0~i6568
Figure 6 shows tlle ~volution o~ the treatment eficien-
cy as a function of the temperature and o the treatment time.
In large capacity plants manufacturing panels of agglo-
merated fibers, since the quantities of water to be treated may
reach 50 m3/h, in order to avoid ~he installation of treatment
plants of considerable d;mensions, it is necessary to determine
the shortest treatment times and thus to work at high tempera-
tures, greater than 100 C. This means carrying out the treatment
in a pressurized chamber, at a temperature maintained at approxi-
mately 5 C. below the boiling temperature of water at the press-
ure of the chamber, so that the water remains in the liquid phase
throughout the duration of treatment. This solution also has
the advantage of requiring only a small ~nergy expendlture which,
with respect to the wastes, only corresponds to the increase in
heat imparted to the water in order to raise its temperature.
Thus, with an identical quantity of dissolved binder
extracted, this process is one-quarter as costly as the process
by burning previously described.
One of the disadvantages ordinarily encountered when
heating in a chamber water containing the binder or dissolved
binder ~omponents, even in a wea~ concentration, is that an in-
solubilized binder deposit foTms on the walls of the chamber which
very quickly becomes thick enough to obstruct the e~acuation orifices
of the chamber, or the chamber itself.
The applicants have observed that if the heat necess-
ary for treatment is released in the water mass to be treated
and the wall of the chamber is maintained thraughout the treat-
ment at a temperature less than that of the~water mass treated,
there is no formation of deposit on the wall, the insolubilized
binder remaining in suspension in the water. This leads to heating
the water, either by mixing with hot fluids such as steam that
1 0 5 6 56 ~
llas preferably been superheated, or with immersed burner combustion
ga~es, or by m~ans localizing ~he energy in thc midst of the water
mass such as an electric arc.
A wide range of operating conditions is possible, for
example 6 to 40 bars for the absolute pressures, from 150 to
240 C. for the temperatures, and from 3 to lO minutes for the
treatment duration.
The following conditions are the result oE a satisfac-
tory compromis~ between the energy cost and the equipment main-
10 tenance cost:
--temperature: 200 C,
--pressure : 16 bars absolute
--duration : 5 minutes
--efficiency : from 70 to 80~.
This method of treatment may be applied to a discon-
tinuous operation set-up or to a continuous operation set-up.
Figure 7 shows a discontinuous operation set-up for
the application of this treatment process. The water to be treat-
ed is introduced to chamber 68 through motorized valve 67. The
quantity of water introduced, or the charge, represents 70 to
80% o-f the capacity of this chamber. The heating fluid or vapor--
preferably superheated--then penetrates the chamber through injec-
tor 69, whose outlet orifice is immersed. The quantity of vapor
is regulated by motorized valve 70, controlled by regulator 71.
The treatment cycle takes place as follows.
Chamber 68 contains a water charge to be treated which
is initially under atmospheric pressure.
The treatment pressure desired, for example 16 bars
absolute, is recorded on regulator 71.
Valve 70 opens and the vapor flows through injector
36.
~ s~s~
69, mixes with the ~Yater to be treatetl ~ and upon condensing trans-
mits all of its latent and sensible heat to the water. The tem-
perature and the pressure in chamber 68 rise until reaching approxi-
mately 200 C. and 16 bars absolute.
The introduction o-E vapor is then terminated. Injector
69 has been adjusted so that this temperaturc and pressure rise
is rapid, occurring in less than one minute.
Thc water is ma;ntained at 200 C. and lfi bars absolute
for two to four minutes.
At the end of this period of time, a pump 72 is put
in operation in order to deliver through jacket 74 a new charge
o~ water to be treated, into a vat 73. As it passes through the
jacket the water to be treated--which is at a temperature of
approximately 40 C. at the entrance--initiates the cooling of
the treated water contained in chamber 68. The dimension of
jacket 74 is adjusted so that the water to be treated reaches
vat 73 at a temperature of approximately 80 C.
A supplementary cooling fluid circulates in the jacket
75 and completes the cooling of the treated water contained in
chamber 68. This cooling is considered to be completed when the
temperature of the treated water drops below 100 C., and pre-
ferably 40 to 50 C. ~t this moment, a motorized valve 76 is
progressively opened in order to decompress chamber 68.
The treated water flows towards a filtration station
51, or a flocculation9 decantation, or centrifu~ing device, which
separates the binder insolubilized by the treatment from the treat-
ed water.
The filtered water flows into ~at 52 and the extracted
wastes 56 are delivered to a conveyor 57.
When chamber 68 is empty, valve 76 is closed and valve
1 0 5 ~ 56 8
67 is opened, thus permitting the preheated charge o~ water in
vat 73 to flow by means of gravity into chamber 68. An exhaust
67a completes the installation.
A new cycle may be started again
Figure 8 shows a continuous operation set-up for the
application of the treatment process.
A pump 77, under the ~reatment press-~re, sends the
water to be treated ko a mixer 78 in which an injector 79 is
arranged, through which the heating 1uid consisting of steam
is introducecl. This steam mixes with the water to be treated
and, upon conaensing, transmits its total heat to this water.
The steam flow is regulated by motorized valve 80 controlled by
regulator 81, in order to maintain the desired treatment tempera-
ture at the outlet of mixer 78. Subsequent to leaving mixer 78
in which it has remained for 10 seconds, the water to be treated
passes through a reactor 82~ where insolubilization of the binder
takes place--the dimensions of which are adjusted so that the
retention time of the water to be treated csrresponds to the dura-
tion of treatment, ~or instance 2 to 4 minutes.
Subsequent to leaving the reactor, the water is cooled
in an exchanger 83, to a temperature less than 100 C., and pre-
ferably from 40 to 50 C. Some of this cooling is provided
by the water to be treated, which is thus preheated in coil 84
from approximately 40 C. to approximately 80 C.
The rest of the cooling is provided by a cooling fluid
circulating in coil 85.
Subsequent to leaving exchanger 83, the treated and
cooled water is decompressed to atmospheric pressure through a
pressure-reducing valve 86 which, controlled by a regulator 87,
maintains the treatment pressure in the installation.
38.
~56~;t;8
The decompressed water ~lows towards a fil~ration device
51, or a flocculation-decantation or centri~uging device, which
separates the binder insolubilized by the treatment from the treat-
ed water. The filtered water flows towards vat 52 and the wastes
56--residues of the treatment--are delivered to a conveyor 57.
The set-up shown in Figur~ 8, of the continuous opera~
tion type, permits a more flexible and less costly treatment
than that shown in Figure 7.
Another process consists of subjecting some of the
washing water, containing the pollutant elements, to a bacterio-
logical treatment in an aerated pond. In such a pond, the bac-
terial organisms present are responsible for the enzymatic destruc-
tion of the phenol products, in particular, present in the water.
By means of an operation corresponding to a total oxidation reac-
tion, the treatment leads to the transformation of the phenolproducts, in particular~ into non-pollutant elements such as CO2
and H 0. In order for this reaction to be total, it is necessary
by aerating the pond to supply the bacterial organisms and the
oxidation reaction with the necessary oxygen.
The installations for the manufacturing of agglomerated
fibrcus panels discharge a large quantity of waste varying in
make-up, but always containing the binder or pollutant binder
components.
It is irst of all the manufacturing wastes of the
panels which are rejected by quality control. These wastes con-
tain extensively dispersed pollutant elements, but are very vol-
uminous. Then there are the wastes coming from the cooling and
washing water filtration, which contain fibers and a very large
concentration of binder and binder components. Up to the present,
all of these wastes have ordinarily been stored in quarries.
1056S68
This practice is objectionable because of resultant
pollution.
The invention provides a process for transforming
the wastes into non-pollutant elements. After a preliminary
preparation, it consists of submitting the wastes to a heat
treatment which, by burning, transforms the pollutant materials
into non-pollutant elements such as CO2 and H2O.
Figure 9 shows a set-up permitting the application
o the process.
Wastes 56 coming from thermal treatment and water
filtration stations are carried by conveyor 57 and delivered
into a comminuter 88, where they are mixed with waste agglomer-
ated fibrous products 87 coming from the manufacturing process.
Upon leaving comminuter 88, the mixture is poured
into an incinerator 90, by means of conveyor 89. The heat re~
leased by burner 91 increases the wastes to a temperature greater
than 1,000 C. At this temperature, the binder and the binder
components are transformed into non-pollutant elements such
as H2O and CO2 and evacuated into the atmosphere with the com-
bustion gases from burner 91, through stack 93. ThQ materialconstituting the fibers, softened by the heat, accumulates on
the bottom of furnace 90, is evacuated from this furnace via
drain 92 in the form of a viscous stream and cooled in vat 94
filled with water. The cooled material thus appears in the
form of granules, which may be retransformed into fibers.
Figure 10 shows another set-up permitting the treat-
ment of the wastes.
The mixture of wa~tes 56 and 87, leaving comminuter
- 88, is deposited by conveyor 89 on a belt 94 which extends through
furnace 95O By means of the heat released by the radiating burn-
4~.
,~
~I~)S6568
ers or electric resistances 96, this furnace increases the wastesto a temperature on the order of 600 to 700 C. At this tempera-
ture, the binder or binder components contained in the wastes
are transformed into non-pollutant elements such as CO2 and H2O,
evacuated through stack 97. The fibers constituting the majority
of the was~es by ~olume are softened Imder the effect of tlle heat,
are consolidated, and agglomerate by sintering in the ~orm of
plates 9S having a volume that is a great deal less than the initial
volume of the wastes. These plates may then be reinjected inko
the fiber production circuit.
Another important characteristic of the invention is
to reduce the noise emitted by the receiving installations with
which the invention is concerned.
In these installations, the most important source of
noise is the fiber production device, and more precisely the
high-speed fluid jets that it emits. The noise level around
the fiber production device, where the operators ar0 brought
to work~ generally exceeds 100 decibels. The configuration of
the zone surrounding the acoustic source in the open installa-
tion, such as are represented in Figura 1, does not permit an
effective insulation of the acoustic source with respect to the
outside, because it is necessary to provide a free space of large
dimensions for the passage of the induced air. On the installa-
tions built according to the invention and represented in Figures
3 and 4, closing wall 32--which contains orifice 33 through which
the current of fibers and gas 12 enters chamber 22--and walls
21 of chamber 22 are given a configuration permitting the install-
ation of absorbent acoustic panels 99, inside chamber 22, and
insulating acoustic panels 100 outside chamber 22.
The reduction in the noise level obtained by installing
these panels, in the zones surrounding fiber production device
41.
~ ~ S 6 S~ ~
11~ is from 20 to 30 decibels--which considerably improves the
working conditions of the opera~ors.
Another source of sound is the fume exhaust fan 19.
The acoustic power emitted by this fan is transmitted through
the flues connecting with the stack which, situated outside the
buildings housing the installation, radiate the sound into the
surroundin~ en~ironment.
On the installations representecl in Figure 1, the large
~olumes to be evacuated through stack 35, and the problem of
limiting the pressure drop in this stack, have led to the install-
ation of a large diameter stack directly at the outlet of fan
19, so that almost all of the acoustic power emitted by this
fan is radiated.
On the installations built according to the invention
and represented by Figures 3 and 4~ the small volume of fumes
evacuated makes it possible to place the point where the fumes
are evacuated at a distance from fan 19. In Figure 3, it is
situated on recyling flue 34 at a point separated from fan 19
by at least one bend and a flue length sufficient so that at
- 20 least part of the acoustic power emitted by fan 19 is absorbed
by conduit 34. In the arrangement of Figure 4 the offtake is
also small and remote from the fan 19.
The reduction in the acoustic level in the zone surround-
ing stack 35 may reach 10 decibels or more.
Figure 11 represents a set-up according ~o the inven-
tion, which contains:
--A fiberization device 101 in which the melted material
102 is in~roduced to a unit revolving at a high speed; this has
a certain number of orifices on its periphery, through which the
material leaves under the action of the centrifugal force; the
42.
1~56St~8
resulting iber ~ilaments are then subjected to the action of
a concentric annular jet of high-speed hot gases generally direct-
ed downwards, which a~tenuates them into fine fibers;
--A fiber distribution device made up o an oscillat-
ing tuyere 14 (for example as illustrated in U.S.A. Patent No.
- 3,134,145~, which surrounds current 12 o ibers ancl gas coming
from the fiberization device;
--A cooling device containing atomizers 50 for project-
ing cooling water on current 12. This device is placed between
distribution apparatus 14 and binder application deYice 13;
--A blanket collection device 15, consisting o a per-
forated belt;
--A forming section 22, o a parallelepiped shape,
bordered in the bottom by the perforated belt 15, laterally by
vertical walls 21, and at the top by a horizontal wall 32 at
a distance o 200 mm. under fiberization device 101, and contain-
ing a circular orifice 33 through which current 12 passes; ~he
edges of this orifice are profiled so as to facilitate the entrance
of current 12, and are tangential to this current; vertical walls
21 mark off the zone where the blanket is formed on perforated
belt 15;
--A compar~ment 16, positioned below the perforated
belt 15 in the zone where the blanket is formed, and having its
pressure reduced by a fan 19;
--A suction and washing chamber 17, placed downstream
from compartment 16, which contains atomizers 45 arrangsd so as
to form sheets of water droplets upon the path of fumes indicat-
ed at 29;
--Downstream from chamber 17, a water separator 18
of the cyclone type;
--A fan 19, which forces all of the gases accompanying
the fibers to pass through the belt 15, and which drives the gases
into flue 34;
43.
~056561~3
--~ recycling flue 34, whose downstream end empties~-
thro-lgh opening 36 in the upper portion of chamber 22--into a
zone surrounding fiber distribution device 14; quantities of
recycled fumes on the order of 90 to 95% of those passing through
perforated belt 15 are led into section 22 through opening 36,
via recycling flue 34;
--A conduit 35 situated on flue 34 evacuates Erom S
to 10~ of the fumes passing through the belt 15 towards the burn-
ing device 39; after passing throug}l the burning device, whère
they are brought to a temperature greater than 600 C., the fumes
are discharged into the atmosphere;
--Absorbent panels 9~ and insulating panels 100, placed
on ~Yalls 21 and 32, in the zone near fiber production device 101;
--A sump 103, which collects the washing-cooling wat~rs
chargad with fibers and with the binder and binder components,
dissolved or in suspension, coming from orifices 24 and 25 plac-
ed at low points in chamber 17 and cyclone 18;
--A pump 104, which delivers the water contained in
the sump to a filtration device 51;
--A filtration device 51 of the vibrating type with
a screen, which separàtes the insoluble wastes from the washing
water;
--A vat 52 placed under filter 51, in which the filter-
ed water is collected;
--An indirect heat exchanger 105, in which the water
contained in vat 52 circulates and is returned to the vat 52
under the action of pump 53, and is cooled by releasing the heat
absorbed by contact with fumes 29, as it passes through chambers
22 and 17 and compartment 16;
--A cooling tower 106, in which the cooling water from
exchanger 105 circulates under the action of pump 107;
--A pump 55 which puts the water from vat 52 back into
circulation and delivers it toward the spray cooling devices
44.
~ ~ 5 ~ 5 ~ ~
50 for the fiber and gas current, and toward the condensa~ion
and washing spray devices 45 for the ~umes 29, and still further
toward the binder preparation station 108, and the water treatment
station 109;
--~ t~ater treatment station 109, in which the water
to be treated is subjected to an increased pressure o~ 16 bars
absolute via pump 77, subsequently p~ssing through an exchanger
83 in which it is heated up to ap~roximately 80 C.; upon leaving
this exchanger, the water to be treated enters a mixer 78, where
it is placed in contact with a flow o~ steam that has preferably
been superheated, consequently increasing its temperature ~o
200 C.--at which it is maintained for two to four minutes in
reactor 82 connected with the outlet of mixer 78; upon leaving
reactor 82, the treated water is passed through the exchanger
83 and is cooled to a temperature of 40 to 50 and then decom-
pressed to atmosphe~ic pressure via pressure-reducing valve 86
after which it is sent to a centrifuge 110 which separates ~he
binder insolubilized by the treatment from the treated water;
the treated water is returned to vat 52;
--A fresh water supply line 111, delivering into vat
52, makes it possible to maintain the quantity of water in the
installation constant;
--Conveyors 57 and 112, carrying the wastes from fil-
tration station 51 and water treatment station 109, and also
the waste materials from the manufacturing line, toward the waste
treatment station 113; and
--A waste treatment station 113, consisting of a fur-
nace equipped with radiant gas tubes or electric resistances,
in which the wastes are brought to a temperature on the order
of 600 to 700 C., so as to burn the binder and the binder com-
ponents, and to sinter the fibers in thin plates of reduced dimen-
sions~ which may be reintroduced in the fiber production circuit.
45.
1~5~;568
Figure 12 represcnts another set-up according to the
invention, which includes:
--A fiberization device in which the melted material,
and especially glass, flows rom a crucible 114 in the form of
ine primary streams 115 that solidify before coming into contact
with pulling rollers 116~ which introduce the solid Eilaments
or rods into a high-speed hot gaseous jet 117--orclinarily in
a direction practically perpendicular to this jet. As a result
lQ the ends o the rods are heated and softened, so that the jet
can attenuate them into fibers and carry these fibers to the
blanket or mat forming unit 15, in the form of a current 12 made
up of fibers and gas. Figure 12 further includes:
--A cooling device containing atomizers S0, for pro-
jecting cooling water on current 12;
--Binder application devices 13 for projecting the bind-
er on current 12, situated downstream from the cooling device,
in the direction o-f flow o current 12;
--A blanket formation unit 15, consisting of a per-
forated belt; and
--A forming section 22, having a parallelepiped shape,
bordered at the bottom by perforated belt 15, laterally by vert-
ical walls 21, at the top by wall 32, and in the rear by vertical
wall 118 placed approximately 200 mm. from the ejection orifice
of jet 117 and containing a rectangular orifice 33 through which
the current 12 passes. The edges oE this orifice are proiled
so as to facilitate the entrance of current 12, and are tangen-
tial to this current. Vertical walls 21 border the zone where
the blanket is formed on perforated belt 15.
Figure 12 further includes:
--A suction compartment 16 9 placed beneath perforated
belt 15, in the zone where the blanket is formed;
--A washing chamber 17, placed beneath compartment
46.
~ ~ S ~5 6 ~
16, containing orifices 47 which open below the surface of a body
of water 48, and through which fumes indicated at 29 flow; atom-
izers 45 spray the washing water, and the wa~er overflows through
pipe 24 for delivery to collector 26;
--Downstream from chamber 17, a water separator 18
of the cyclone type;
--A fan l~, which forces all of the gases accompanying
the fibers to pass through the fiber collection device and to
deliver the ~ases into fluc 3~;
--A recycling flue 34~ whose downstream end empties
into chamber 22 through two openings in the t~o vertical walls
~1 situated one on each side of the fiberization apparatus, in
a zone near this apparatus; quantities of recycled fumes, which
may reach as high as 95% of the quantities passing through per-
forated belt 15, are led into chamber ~2 through these openings;
--A conduit 43, communicating with chamber 22 in a
zone situated in an upstream zone of *his chamber, which evac-
uates the non-recycled fumes ~hrough fan 44 to the burning device
39;
--Absorbent panels 99 and insulating panels lO0, plac-
ed on walls 21, 32 and 118 in the zone near the fiberization device;
--A sump 103, which collects the washing-cooling waters
charged with fibers and wi*h the binder and binder components,
dissolved or in suspension, coming from orifices 24 and 25 plac-
ed a~ low points in chamber 17 and cyclone 18;
--A pump 104, which leads the water contained in the
sump to a filtration device 51;
--A filtration device 51 of the vibrating type wlth
a screen, which separates the insoluble wastes from the washing
water;
--A vat 52 placed beneath filter 51~ this vat collect-
ing the filtered water; and
--A heat exchanger 105, in which the water contained
47.
;5~8
in vat 52 circulates und~r the action o pump 53 and is cooled
by releasing the hea~ absorbed from the fumes 29, as they pass
through chambers 22 and 17.
The installation that was just described also contains--
as is shown--a water treatment station an~l a waste treatment
station as described above with reference to Figure 11.
Figure 13 shows another set-up according to the inven-
tion, which comprises the following.
A fiberization clevice, in which the molten material
flows from forehearth 118 of a furnace through the orifice~ of
one or several rows of tips provided on a bushing ll9, produces
a large number of strands of material that flow into an attenuat-
ing zone, where they pass between high-speed convergent, gaseous
jets. Jet ejection devices 120 are situated very close to the
glass fibers, and the jets are directed downwardly, in a direc-
tion that is practically parallel to the direction of movement
of the glass fibers. Usually, the jets consist of high-pressure
steam. The fibers produced, the attenuating jets, and the surround-
ing fluid that they induce constitute current 12.
Cooling spray devices S0 project cooling water on
current 12.
Binder spraying devices 13 project the binder on curr-
ent 12.
A fiber distribution deuice 14, such as is shown in
Berthon et al U.S. Patent No. 3,020,585, is made up of two press-
urized air injectors, for directing the fibers in the desired
direction.
The rest of the installation represented in Figure 13
is similar to that shown in Figure 11.
~8.
~:)S~;S68
In an installation o~ the general arrangement of Fig-
ure 13 the fiberization may alternatively be of the toration
type as disclosed in copending Canadian application of Marcel
Levecque and Jean A. Battigelli, Serial No. 196,120, fil~d March
27, 1974. Thus, in the general position of the devices indicated
at 119 and 120 in Figure 13, and in place of such devices 119
and 120, one or more intersecting and interacting glass carrier
jets and blasts may be arranged to provide Eor the production
of a current 12 of gases and attenuated fibers.
Figure 14 shows another set-up accordiny to the inven-
tion, which comprises the following.
A fiberization device is provided, in which material
in the molten state and in the form of stream 121, is directed
by high-speed jets coming from orifices 123, against the peri-
phery of a rotor 122 turning at a high speed. Under the effect
of the centrifugal force, revolving unit 122 transforms some
of the material that it receives into fibers and sends the rest
of the material to a second rotor 124, wbich transforms some
of the material that it receives into fibers by means of a simi-
lar process. The number of rotors such as 122 is generallylimited to two or three. By means of a ring provided with ori-
fices 125 surrounding rotors such as 122 and 124, jets of fluid
are emitted--also at a high speed--which act on the fibers pro-
duced, to direct them towards the receiving unit. These jets
consist of air or steam under high pressure. Generally, orifices
125 are also used to project the binder on the fibers. Current
12 is made up of the fibers, the guiding jets, and the surround-
ing fluid that they induce.
Cooling spray devices 50, for projecting cooling water
on current 12, are placed downstream from orifices 125, the
49.
~I~S6S61~3
binder being atomized via certain of these orifices. The
rest of the installation represented in Figure 14 is similar
to that shown in Figure 13.
50.
~3
