Note: Descriptions are shown in the official language in which they were submitted.
CA 02233661 1998-03-31
WO 97/13594 PCT/ALJ9G/OOG2ft
VOLATILE MATERIALS TREATMENT SYSTEM
This invention relates to the treatment of volatile contaminants. The
invention is
particularly suitable for, but not limited to, the removal of contaminants
from solids and liquids.
S
The contaminants may include, but are not limited to, petroleum products (eg.
petrol,
oils, greases); phenols; coaltar; cyanide; pesticides; PCB's; I-iCB's,
organochlor-ine pesticides and
arsenics.
The treatment of contaminated soils and liquid wastes is a worldwide problem.
Ofi en,
the contaminated soils or liquids are simply removed and transferred to a
toxic waste dump or
pond. This does no more than move the problem. For contaminants such as PCB's,
the
environmental protection authorities around the world specify strict
conditions for their disposal
in very high temperature incinerators, eg. found in the vessel "Vulcanus".
1S
International Patent Application No. PCT/AU93/00646 (International Publication
No.
WO 94/1S1S0) (Robertson) discloses a stationery retort where toxic waste and
other
contaminants are removed from soil, the soil being agitated and being brought
into contact with
the retort walls to cause the wastes and contaminants to be desorbed_ The
retort has proved
successful in the removal of toxic waste and contaminants from many types of
soil.
It is an object of the present invention to provide improved methods and
apparatus for
use in removing volatile contaminants from solids or liquids.
2S According to one aspect of the present invention there is provided a method
for t1e
treatment of volatile material (s) in contaminated material (s) including the
steps of:
feeding the contaminated material (s) to a retort assembly which includes a
rotatable
retort at least partially disposed within a combustion chamber which is heated
by heating
means ;
causing the contaminated material (s) to contact the walls) of the retort to
cause the
volatile material (s) to be given off as gases;
SUBST)TLTI'E SKEET (Rule 26)
CA 02233661 1998-03-31
VVO 97~z359a z'C'r~AU9G~oaGZs
-2-
discharging the ueated material from the retort;
uansferring the gases to an afterburner for combustion; and
returning the combustion gases from the afterburner to the retort assembly to
provide
assistance in heating the contaminated materials) being treated in the retort.
S
According to another aspect of the present invention there is provided
apparatus for
the treatment of volatile material (s) in contaminated material (s) including
a retort assembly
which includes a rotatable retort disposed at least partially within a
combustion chamber with
heating means to indirectly heat die rotatable retort; said rotatable retort
include a feed end
through which the contaminated materials) are fed to the retort and a
discharge end from
which the materials are discharged from the retort; an afterburner; means to
uansfer the
volatile materials) given off as gases to the afterburner for combustion; and
means for
passing d1e combustion gases from the afterburner to the retort assembly to
provide additional
heat for use in the heating of contaminated material (s) in the retort.
Preferably, the apparatus includes a high temperature filter through which the
gaseous
volatile material (s) pass after leaving the retort and prior to entering the
afterburner.
According to yet another aspect of the present invention there is provided a
high
temperature filter which is suitable for use.but not limited to the treatment
of volatile gaseous
contaminated material, the filter including a main body having first and
second chambers
therein which chambers when the flter is in its operative position include an
upper region and
a lower region, an opening providing communication between ttze chambers, said
opening
being' at the lower region of the chambers, an inlet for delivering gaseous
contaminated
2S material to the first chamber in the upper region thereof, an outlet for
discharging the gaseous
material from the second chamber, a solids collection zone adjacent the
opening, a solids
discharge outlet for discharging solids from the solids collection zone, a
baffle opposite to and
spaced from the inlet upon which incoming gases impinge and filter means for
filtering die
gaseous material passing out of the second chamber via the outlet.
SUBSTIT'UZ'E SI~ET (Rule 26)
CA 02233661 1998-03-31
WO 97/I3594 F'CT/ATJ9Cr/OOG28
-3-
According to another aspect of the present invention there is provided a
retort for use
in the treatment of volatile material, the retort including a cylindrical body
which is mounted
for rotation about its longitudinal axis, said body having an infeed end and
an outlet end, a
combustion chamber, said cylindrical body being at least partially located
within ttie
combustion chamber, a plurality of balls or like elements disposed witHin the
cylindrical body
arranged to interact wide contaminated material when the cylindrical body is
rotating to break
down the material and dislodge carbonised material which may form on the
internal wall of
the cylindrical body. The retort is particularly suitable for use in apparatus
of the type
described herein.
Preferably the retort includes a cage within the cylinder which retains the
balls in t1e
region of the wall of the cylindrical body. Preferably, the balls are arranged
in groups, the
groups being at spaced intervals along the interior of the cylindrical body.
The cage includes
spaced apart peripherally extending members which arc adapted to assist in
retaining the balls
in each group at a particular location within the cylindrical body.
Preferably, the balls are
made of ceramic material. Preferably, the cage is mounted for rotation in the
opposite
direction to the cylindrical body.
In one embodiment of the invention the combustion gases are passed through the
interior of the reCort. In another embodiment_the combustion gases arc passed
to the heating
means _
When the contaminated material to be treated is in the form of solids, the
solids are
preferably passed through a grizzly or sieve prior to entering the retort to
remove oversized
material. If desired the solids may in addition to or alternatively to the
above be passed
through a mill prior to entering the retort so as to reduce the particle or
granule size of t1e
solids.
When the contaminated material is in the form of liquid, floe water content of
the
liquid is preferably reduced prior to entering the retort. To this end the
liquids may be
SLJBSTIT'(TI~ SI~ET (Rule 26)
CA 02233661 1998-03-31
WO 97/13594 PCT/AU9G/()OG28
-4-
preheated to boil off the water prior to entering the retort.
Preferably, the rotary retort rotates about an axis inclined at a small angle
to the
horizontal and is substantially surrounded by a combustion chamber to enable
indirect heating
of the retort.
Preferably, the combustion gases pass through a scrubber before being released
into
the atmosphere after passing through the retort. The gases from the high
temperature filter
may be passed through a condenser, where the condensate contains hydrocarbon
fractions
such as fuel oil and lubrication oil fractions.
In the high temperature filter according to the invention, the baffle is
preferably
defined by a wall which separates the said first and second chambers.
Preferably, the wall
extends from an upper internal wall of the chambers and terminates at a point
spaced from
IS a Iower internal wall of the chambers, the space between the free end of
the wall and the
lower internal wall of the filter defining the opening. The wall may have fins
thereon.
Preferably, the discharge outlet comprises a plurality of outlet ports in the
upper wall
of said second chamber. Preferably, the filter means comprises a plurality of
ceramic
candles, each ceramic candle being associated with a respect outlet, the
ceramic candles
extending into the second chamber.
There may further be provided a gas collecting chamber for receiving the
gaseous
rnai~eriai from tale outlets and a discharge outlet for discharging the
gaseous material from the
gas collecting chamber. Fan suction means may be provided for drawing t1e
gaseous
material from the second chamber through the outlets.
The filter may further include pulsing means for delivering a gas under
pressure to the
filter means in the opposite direction of normal flow for cleaning the filter
means.
Preferably, the gas used in the pulsing means is nitrogen.
SUBSTT»'E SHEET (Rule 2b)
CA 02233661 1998-03-31
..
WO 97/13594 FCT/AU9G/0()C28
-5-
A heat jacket is preferably provided which at least partially surrounds the
main body
of the filter.
A further embodiment of the invention is particularly suited for the treatment
of
material containing organochlorine pesticides such as DDT, DDE and DDD and
various
arsenic based compounds. Such material is found in soil from cattle dip sites.
According to this aspect of the present invention there is provided a method
for
treatment of volatile materials) in contaminated materials) including
organochlorine
pesticides and arsenic based compounds including the steps of:
feeding the contaminated materials) to a retort assembly which includes a
rotatable
retort at least partially disposed within a combustion chamber which is heated
by heating
means;
causing the contaminated materials) to contact the walI(s) of the retort to
cause the
I S volatile materials) to be given off as gases;
discharging the treated material from the retort into a high temperature
filter;
thereafter transferring the gases to an afterburner for combustion and at the
same time
introducing water vapour into the afterburner.
According to yet another aspect of tly,present invention there is provided
apparatus
for treatment of volatile materials) in contaminated material (s) including
organochlorine
pesticides and arsenic based compounds including
a retort assembly which includes a rotatable retort having an infeed end
through which
material is fed to the retort and an outlet, the retort being at least
partially disposed within a
combustion chamber which is heated by heating means, whereby in use, the
contaminated
materials) is caused to contact the walls) of the retort to cause the volatile
materials) to be
given off as gases;
a high temperature filter which receives the material from the retort, an
afterburner
for combustion of the gases and means for introducing water vapour into the
afterburner.
SUBSTITUTE SI~ET (Rule 26)
CA 02233661 1998-03-31
WO 97/I3594 PCT/AU9G/(1OG28
-6-
In this particular process the contaminated material is preferably firstly
pretreated to
remove water from the material. This may be done by the use of a preheater.
The material
is then transferred to a retort where the contaminant compounds are vaporised.
The
contaminarits in the gas stream so formed are then transferred to a high
temperature filter
which may be of die type described earlier where further particulate matter is
separated from
the gas. The remaining gaseous component is transferred to an afterburner. The
afterburner thermally destructs the organochlorine pesticides to produce
simple products of
combustion and hydrogen chloride gas. The arsenic component of the gas will
pass through
the afterburner primarily as arsenic trioxide.
If desired water vapour which may be conveniently drawn from the preheater is
fed
into the afterburner. The introduction of the water vapour causes a water/gas
reaction which
assists in the production of hydrogen chloride and arsenates.
The gas stream then passes to a condenser wherein the gas is rapidly cooled so
as to
condense the arsenates for collection as particulate matter. After the gas
stream leaves the
condenser calcium carbonate can be added to the stream to neutralise the
hydrogen chloride.
The gas can be finally passed tlmough a dust collector device whereafter the
gas can
pass to atmosphere.
As mentioned earlier the gases leaving the afterburner are cooled so as
sublimate
(condense) the arsenic and arsenic trioxide. Two alternative systems are
envisaged
I. indirect air cooled; or
2. evaporative cooling through injection of water into the gas stream.
The gas stxeam leaving the afterburner is cooled to preferably about
110°C in the
condenser and then may be dosed with calcium carbonate (CaC03) (lime). The
calcium
SUBSTITUTE SKEET (Rule 26)
CA 02233661 2004-12-29
carbonate reacts with the constituents ofthe gas stream to neutralise the
hydrochloric acid and
absorb moisture in the gas stream . The lime assists in minimizing moisture
problems on the
filter bags, and can be collected in a dust collection bin.
The dust collector which may be in the form of a baghouse will remove the
particulate arsenic
trioxide which condenses below at approximately 120 ° C and collects on
the filter media. The
gas stream will exit the baghouse at approximately 100 ° C and be
vented to atmosphere. An
auxiliary fan on the baghouse will be used in conjunction with the high
temperature filter fan
in order to overcome the additional pressure loss in the system. The fans will
be balanced
using dampers in the system. The contaminated particulate (arsenic trioxide,
spent lime) can
be collected in plastic lined 200 L drums for disposal at authorized
landfills.
In a broad aspect, then, the present invention relates to a high temperature
filter for
use in the treatment of volatile gaseous contaminated material, the filter
including a main body
having an internal space therein which internal space includes an upper region
and a lower
region, said internal space being separated into first and second chambers, an
opening
providing communication between the chambers, said opening being at the lower
region of
the internal space, an inlet for delivering the gaseous contaminated material
to the first
chamber in the upper region of the internal space, an outlet for discharging
the gaseous
material from the second chamber in the upper region of the internal space, a
solids collection
zone adjacent the opening, a solids discharge outlet for discharging solids
from the solids
collection zone, a baffle directly opposite to and spaced from the inlet upon
which incoming
gases impinge so as to separate the solids from the gaseous material, filter
means for filtering
the gaseous material passing out ofthe second chamber via the outlet and a
heat jacket which
at least partially surrounds the main body of the filter.
To enable the invention to be fully understood, preferred embodiments ofthe
invention
in its various aspects will now be described with reference to the
accompanying drawings in
which:
CA 02233661 2004-12-29
-7a-
Figure 1 is a schematic circuit diagram of a first embodiment for the
treatment of
contaminated solids;
Figure 2 is a schematic view of the retort of the first embodiment;
Figure 3 is a more detailed schematic view of the retort of the first
embodiment;
Figure 4 si a schematic sectional side view of a high temperature filter
according to
the present invention;
Figure 5 is a schematic side view of an afterburner for use in the present
invention;
Figure 6 is a schematic view of a second embodiment for the treatment of
CA 02233661 1998-03-31
WO 97/13594 i'CT/AU9G100G28
_g_
contaminated liquids;
Figure 7 is a schematic view of a third embodiment for the treatment of
contaminated
liquids;
Figure 8 is a schematic view of a further embodiment particularly suited for
the
treatment of organochlorine pesticides and arsenic compounds;
Figure 9 is a schematic side elevation of a part of a high temperature filter
according
to another form of the invention;
Figure 10 is a side elevation of a manifold as shown in Figure 9;
Figure I I is a schematic side elevation of one form of condenser which can be
used
in the embodiment of Figure 8;
Figure 12 is a schematic side elevation of another form of condenser 4vhich
can be
used in the embodiment of Figure 8;
Figure I3 is a sectional view of a retort according to one embodiment of the
invention;
and
Figure 14 is a modified form of the retort shown in Figure 13.
Referring to Figures 1-3, die rotary retort 10 has a cytindricai retort wall 1
1 rotatably
journal led within a combustion chamber I2 heated by a plurality of burners 13
to provide
indirect heating to the interior of the retort 10.
Ceramic seals form an airproof seal between the moving retort wall I 1 and the
fixed
ends of the combustion chamber 12 (or of a support structure for the retort),
and also act as
SUBST)TLJT'E SFWET (Rule 2fi)
CA 02233661 1998-03-31
VVO 97/13594
PCT/A L79G/OOG28
-9-
an explosion vent in case of a volatile mix release caused by oxygen in the
retort. (Preferably,
a nitrogen purge is provided for the retort to prevent the oxygen levels
becoming dangerous.)
As shown in Figure 3, fins, blades or the like 14 are provided on the inner
face of the
retort wall 11 to increase the agitation of materials passing through the
retort and to improve
the heat transfer from the retort wall 1 1 to the materials.
Contaminated solids 20 are transferred via conveyor 21 to a grizzly 22 where
oversized particles are removed. The acceptable particles are fed to the
interior of the retort
IO via a rotary valve 23. As the contaminated solids move through tte retort
I0, volatile
contaminants are given off as gases and are transferred via a gas line 15 to a
high temperature
filter 30 to be hereinafter described in more detail. The high temperature
filter 30 is heated
by the combustion gases from the combustion chamber 12 (being transferred via
a line 1G).
A rotary valve I7 discharges the treated solids to a product in I8 and a
conveyor 19
may be provided to transfer the treated solids from the product bin 18 to a
dump pile 19A.
Referring now to Figure 4, the high temperature filter 30 is maintained above
500°C
above the combustion gases from the retort being fed via line 1G to a heat
jacket 31 to prevent
' 20 condensation of the volatile gases 32. The volatile gases enter a first
chamber 33 and impinge
on a wall 34 which acts as a baffle and separates the first chamber 33 from a
second chamber
35. The wall 34 may have fins or plates thereon for the transfer of heat as
well as to slow the
gas stream down. As the volatile gases 32 sharply change path when passing
from the first
-L-~L~__'7'1 ~ .t__ J 1.
~mamu~r » ~o me secona cnamber 35, most of tile particuiates 3G in tile
voiatiie gases 32
collect at the bottom of the high temperature filter 30 and can be selectively
discharged by
a rotary valve 37 and line 38 to the product bin 18. The combustion gases 32
then pass
through ceramic candles 39 which capture particles down to -1 micron. The
interiors of the
ceramic candles 39 are connected to a pIenum or chamber 40 and the volatile
gases 32 are
drawn from the plenum by a suction fan 41. The suction fan generates a partial
vacuum in
the high temperature filter 30 (and the retort IO) and assists in causing the
ceramic seals to
SLJBSTITUT73 5F-~ET (Rule 2G)
CA 02233661 1998-03-31
WO 97113694 YCT/AU9G/OO128
- 10-
seal against the ends of the retort wall I I . An explosion vent in the form
of a door 63 may
be provided in the wall of the filter the door being arranged to open in the
event of an
explosion.
S To prevent the oxygen level in the high temperature filter 30 reaching
dangerous
levels, sensor means (not shown) monitor the oxygen levels and if required,
nitrogen from
a supply tank 42 is injected into die line IS via one or more nozzles
connected to a valve 43.
To remove the particulates 36 which tend to coat the exterior of the ceramic
candles
39, an air compressor 44 is connected to a manifold 4S via a valve 46. A
respective pipe 47
extends from the manifold 4S into the interior of each ceramic candle 39 and
sensor means
(not shown) which monitor the gas flow through the ceramic candles, operate
t1e valve 46
so that a blast of air is injected into the interior of the ceramic candles,
via the pipes 47 to
cause a countercurrent flow to die flow of the volatile gases 32 to dislodge
the particulates
1 S from the candles for collection in the bottom of the high temperature
filter 30.
Figures 9 and 10 show a modified form of apparatus for introducing nitrogen
into the
high temperature filter as well as for removing the particles from the
candles. In the
apparatus as shown nitrogen is fed from a manifold 401 having a plurality of
outlets 402 to
406_ Each outlet is connected to a transfer tube 407 which extends into the
filter at a
position above the candles 39. The tube has a series of downwardly facing
holes 408 each
hole being associated with a respective candle. T7ie arrangement is such that
a blast of
nitrogen can tie directed downwardly to clear the candles and at the same time
deliver
nitrogen to the f-tlter_
2S
The volatile gases 32 are conveyed via a line 48 to an afterburner SO (see
Figure S)
in which combustion air is injected via a number of inclined injection pipes
51 to create a
vortex for efficient combustion of the volatile gases. In one embodiment the
combustion gases
52 from the afterburner pass through a plenum S3 to a line S4 which is
connected to a pipe
or conduit SS extending through the interior of the retort 10. In another
embodiment the
SLTBSTTZ'UZ'E SI~ET (Rule 26)
CA 02233661 1998-03-31
' ~ w0 97/I3594 t'CT/AU9G/OOG28
gases can pass along line 54 and instead of passing through the retort can be
fed to the burners
I3 as shown by dash line 62 in Figure I.
The pipe 55 has a plurality of helical flytes 56 to further promote the
agitation of the
laminated solids 50 in the retort I0, and to promote the transfer of heat from
die combustion
gases to the solids. /~s shown in Figure I , the flow of the combustion gases
52 from the
afterburner is concurrent with the flow of solids through the retort IO and
the heat from the
combustion gases 52 reduces the heat requirements for the retort provided by
the burners I5,
thereby reducing the input energy demand and cost. (This means flat the
volatile
contaminants in the soil are used to provide a portion of the energy demands
for the treatment
of the soil and so the volatile materials, which normally have a highly
negative economic
value, are given at least a partial positive economic value.) From the pipe
55, a line 57
transfers the combustion gases 52 to a scrubber 58 and thereby to the end
stack 59 for release
to the atmosphere.
IS
Referring now to a second embodiment of Figure 6, liquid contaminants from a
pond
I20 are fed to a concentrator 12I where the water content of the liquids is
minimised and the
concentrated contaminated liquid is transferred to a tank 122. The
contaminated liquid is
pumped via a pump I22a to spray nozzles I23 which inject the contaminated
liquid into the
retort 10. The contaminated liquid comes into contact with the interior of the
retort wall 11
and the conduit SS to cause the volatile contaminants to be given off as gases
as hereinbefore
described and any non-volatile solids are discharged via rotary valve 17 to
the product bin I8.
It will be noted that line 54 connects the afterburner 50 to the conduit 55 so
that t1e
2S flow of combustion gases 52 from the afterburner is countercurrent to the
flow of the
contaminated liquids through t1e retort 10.
In the embodiment of Figure 7, which is particularly suitable for the
treatment of
refinery tank bottoms, the contaminated refinery products containing, eg. 50-
80 % water, is
pumped from a refinery tank 220 to a preheater 222 where the water and light
hydrocarbon
SUBSTTTUTB SF~ET (Rule 26)
CA 02233661 1998-03-31
T
' WO 97/I3594 ~ I'CT/AU9G/OOG28
- 12-
fractions) are boiled off at, eg. 120°C plus and fed by line 260 to the
afterburner S0. A hot
filtering device 261 removes particulates from the water/gas stream and feeds
them to the
high temperature filter 30 via a rotary valve 262_ The concentrated liquid
from the preheater
222 is sprayed into the retort IO as hereinbefore described. The preheater I22
is heated by
S combustion gases from the retort IO via line 223.
From the retort, the non-volatile solids are discharged via rotary valve I7 to
the bin
I8, and the volatile gases are transferred to the high temperature filter 30.
The volatile gases
are transferred from the filter 30 to a condenser 270 via line 27I at a
temperature of, eg.
S00°C. The gases are cooled and the condensate is collected as fuel
oil, which is drawn off
to tank 272 via line 273. By arranging the Condenser 270 as a "fractional
distillation unit",
the condensate may be separated into a lubrication oil component (drawn off
at, eg.
300-500°C) to tank 274 via line 275, and a diesel substitute component
(at, eg. 200-300°C)
via line 273 to tank 272.
1S
The remaining volatiles from the condenser 270 are fed to the afterburner SO
via line
48. These voIatiles, and the 222 water/light 1vC fraction from the preheater,
may be burnt at,
eg. 1200°C with a residence time of, eg. 20 seconds. The energy from
the afterburner SO
is recycled to heat the preheater 223 and die high temperature filter 30. The
high temperature
filter and pre-treatment feed and product lines.are surrounded by a heating
jacket to maintain
temperature and the heat is sourced from the combustion chamber excess gases.
This method markedly reduces the costs of treating the refinery tac~lc
bottoms, and the
~oto .rr~ ..FF....~ h.. r1... _ _r .a -
~~~w me wmc~ uy 1.11C: Lel:VVery oc me vaiuabie eondensates(s).
2S
Figure 8 shows a further embodiment of the invention which is particularly
suited for
the treatment of material containing organochlorine pesticides such as DDT,
DDE and DDD
and various arsenic based compounds. Such material is found in soil from
cattle dip sites.
In this particular arrangement die contaminated material is preferably firstly
pretreated
SU13STT'f(JT'E SFiF~T (Rule 2G)
CA 02233661 1998-03-31
WO 97/13594 PCT/Atl9G/OOG28
-13-
to remove water from the material. This may be done by the use of a preheater
501. The
material is then transferred to retort 503 where the contaminant compounds are
vaporised.
The contaminants in the gas stream so formed are then transferred to high
temperature filter
504 which may be which may be of the type described earlier where further
particulate matter
is separated from the gas. The remaining gaseous component is transferred to
afterburner
506. The afterburner thermally destructs the organochlorine pesticides to
produce simple
products of combustion and hydrogen chloride gas. The arsenic component of the
gas will
pass through the after burner primarily as arsenic trioxide.
If desired water vapour which may be conveniently drawn from the preheater 501
is
fed into the afterburner 506 via line 510. The introduction of the water
vapour causes a
water/gas reaction which assisu in the production of hydrogen chloride and
arsenates.
The gas stream then passes to condenser 512 wherein the gas is rapidly cooled
so as
to condense the arsenates for collection as particulate matter at vessel 514.
After the gas
stream leaves the condenser SI2 calcium carbonate can be added to t1e stream
via hopper 516
to neutralise the hydrogen chloride.
The gas can be finally passed through a dUSt collector device 518 whereafter
the gas
can pass to atmosphere. The dust collector 518 which may be in the form of a
baghouse will
remove the particulate arsenic trioxide which condenses below at approximately
120°C and
collects on the filter media. The gas stream will exit the baghouse at
approximately 100°C
and be vented to atmosphere. An auxiliary fan on the baghouse will be used in
conjunction
with the high temperature filter fan in order to overcome the additional
pressure loss in the
system_ The fans will be balanced using dampers in the system. The
contaminated
particulate (arsenic trioxide, spent lime) will be collected in plastic lined
200 L drums for
disposal at authorised landfills.
Two examples of condensers which can be used are shown in Figures 1 l and 12.
Figure 1 1 shows an evaporate cooling arrangement wherein the gases leave the
afterburner
SUBSTTTUTE SHEET (Rule 26)
CA 02233661 1998-03-31
' ~ WO 97/13594 PCT/AU9G/OOG28
- 14-
and travel along an inverted U-tube 601. Water spray a fed from reservoir 602
to spray
heads 603 by pump 604 so as to rapidly cool the gas before it leaves the
condenser.
Figure 12 shows an indirect air cooled arrangement where gases enter die top
of the
condenser 700. A series of fans 701 create an air flow across the condenser
thereby cooling
the gases before they exit at the bottom.
Figures 13 and 14 show two arrangements of a retort which is suitable for use
in
various forms of apparatus described herein. Referring to the drawings the
retort 800
includes a cylindrical body 80I which is mounted for rotation about its
central axis for
example on shaft 810. The retort 800 is disposed within a combustion chamber
(not shown)
the ends being sealed by ceramic seals (not shown). The retort has an infeed
end 802
through contaminated material is fed into the retort and an outlet 803. A
plurality of flytes
808 are formed on the internal wall of the cylindrical body 801 the flytes
preferably having
a 5° pitch.
The retort 800 further includes a cage 815 which is mounted within the
cylindrical
body 801. The cage 815 comprises a series of horizontal elements or rods 816
and a series
of circumferential elements 817 connected together to form a unitary
structure. The
circumferentiaI elements 817 are arranged in pairs on the region of the space
between adjacent
flytes 808. The cross-sectional diameter of the cage 8I5 is less than that of
the internal
cross-sectional diameter of cylindrical body 801 thereby forming an annular
space 818
between the cylindrical body 801 and the cage 815.
The cage 8I5 is mounted for rotation and preferably is arranged to rotate in
the
opposite direction to flat of the cylindrical body.
A plurality of balls 806 or like elements are disposed in the space 818 and
are
arranged to interact with contaminated material when the parts are rotating to
break down the
material and dislodge carbonised material which may form on the internal wall
of the
SUBSTrI UTE 5F1~T {Rulc 26)
CA 02233661 1998-03-31
WO 97/13s94 PC'I'/A119G/OOG28
- 15 -
cylindrical body 801. The balls 806 are arranged in groups disposed at spaced
intervals
along the cylindrical body and are retained in position by respective pairs of
circumferential
elements 817
In the embodiment shown in Figure 14 there is further provided a series of
arms 820
which can assist in moving the balls during rotation of the parts. The arms
820 can either
rotate with the cage on shaft 8I0 or can be fixed to tte internal wall of the
cylindrical body
801.
The balls are arranged in groups each group which are held in place by the
cage 815
and more particularly by the element 817 projecting into space 818. The groups
of balls are
being disposed at spaced intervals along the cylindrical body.
NB: For both contaminated solids or liquids, the flow of the combustion gases
52
through the retort may be eidter concurrent or countercurrent to the flow of
the contaminated
materials.
The recycling of the afterburner gases back into the retort 10 via the tube,
pipe or
conduit 55 minimises the energy input to the retort by the burners.
The provision of the heat fins or flytes 56 on the pipe or conduit 55 not only
increases
the radiant surface area of die retort, but also assists in breaking up any
large particles. In
addition, the recycling pipe or conduit also helps create a convection
environment with
improves the volatile removal process, ttie convection improvement being
created by the
moving retort wall and by rotation of the pipe or conduit 55.
The energy sources for the burners 13 may include liquid petroleum gas,
propane,
natural gas, recycled hydrocarbons or other readily available energy sources.
The volatiles which may be treated by the method and apparatus of the present
SUBSTT»I~ SHEET (Rule 26)
CA 02233661 1998-03-31
w0 97/I3594 PCT/AU9C/OOG28
- 16-
invention include hydrocarbons, organo-chlorides, arsenics, hydrogenated
hydrocarbons,
PCB's, coaltars and the like.
The operating temperature in the retort will be dependent on t1e volatile
contaminants
being treated and the retort may be operated at different temperatures to
enable different
volatiles to be treated on a fractional basis.
Various changes and modifications may be made to the embodiments described
without departing from the present invention.
SUBSTITUI~ SF~ET (Rule 26)
