Note: Descriptions are shown in the official language in which they were submitted.
212130~
APPARATUS AND METHOD FOR PREFERENTIALLY SEPARATING
VOL~TILIZABLE COMPONENTS OF A MATRIX
5 Related APplications
This is a continuation-in-part of U.S. Serial No.
07/683,299 filed April 10, 1991, which is hereby
incorporated by reference.
10 Backqround of the Invention
Many wastes, such as sludges and contaminated
soils, include a matrix and one or more volatilizable
components. For example, sludges generated by
industrial processes which include a solid matrix
15 component also often include a volatilizable component
which is not suitable for disposal by direct discharge
to the environment. In another example, soil can
become contaminated by oil, gasoline or other
contaminants, such as by leakage from storage vessels
3 20 or during drilling of oil wells.
One attempt to dispose of such wastes is by
containment in sealed land fills. However, seals in
~j land fills can deteriorate and fail, thereby allowing
i3 the wastes to leak into the surrounding ground.
25 Further, land-fills generally require large areas of
land and availability of suitable land-fill sites is
diminishing. In addition, governmental regulation
limits the kinds of waste which can be disposed of in
land fills. Disposal of wastes has also been attempted
30 by incineration. However, airborne pollutants are
~ typically released into the atmosphere as incinerator
i exhaust.
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2121306
Another attempt to dispose of volatilizable
component-containing wastes includes volatilization of
the volatilizable components. The volatilized
components can then be treated separately. Removal of
volatilizable components from matrices, however, has
often been substantially incomplete because of the
relatively low volatility of many volatilizable
components. Following volatilization of these
relatively low volatility components, quenching,
condensation and redeposition of the relatively low
vapor pressure components has occurred due to
intermixing with relatively high vapor pressure
components.
Thus, a need exists for an apparatus and method
for removing volatilizable components from matrices
which overcome or minimize the above-mentioned
problems.
Summarv of the Invention
The present invention relates to a new apparatus
and method for preferentially separating a high vapor
pressure component from a low vapor pressure component,
wherein at least a portion of each volatilizable
component is volatilized from a matrix.
The apparatus includes a housing, having a housing
inlet and a housing outlet, and a means for conveying
the matrix from the housing inlet through the housing
to the housing outlet. The apparatus also includes -
means for volatilizing at least a portion of the high
30 vapor pressure component and the low vapor pressure -
component of the matrix within the housing. A first
2121306
gas outlet is disposed at the housing. A second gas
outlet is also disposed at the housing and is
sufficiently remote from the first gas outlet to enable
preferential separation of the volatilized high vapor
pressure component from the volatilized low vap~r
pressure component. Additionally, the apparatus
includes a means for preferentially directing the
volatilized high vapor pressure component out of the
housing through the first gas outlet and for
preferentially directing the volatilized low vapor
pressure component out of the housing through the
second gas outlet, thereby preferentially separating
the high vapor pressure component from the low vapor
pressure component of the matrix.
The method includes conveying the matrix through a
housing from a housing inlet at an inlet end of the
housing to a housing outlet at an outlet end of the
housing. The matrix is heated to a temperature which ~ -
is sufficient to volatilize at least a portion of the
high vapor pressure component and the low vapor
pressure component. The volatilized high vapor
pressure component is then preferentially directed out
of the housing through a first gas outlet at the
housing. The volatilized low vapor pressure component
is preferentially directed out of the housing through a
second gas outlet, which is disposed at the housing and
which is sufficiently remote from the first gas outlet
to enable preferential separation of the volatilized
high vapor pressure component from the volatilized low
vapor pressure component, thereby preferentially
separating the volatilized high vapor pressure
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2121306
component from the volatilized low vapor pressure
component of the matrix.
This invention has the advantage of preferentially
removing at least a portion of a volatilized high vapor
pressure component from a volatilized low vapor
pressure component of a matrix. Also, redeposition of
the volatilized components into the matrix bed or gas
outlet piping by steam quenching, or by condensation of
the volatilized low vapor pressure component, due to
lo interaction with the volatilized high vapor pressure
component is significantly reduced. The preferential
separation of the volatilized high vapor pressure
component from the volatilized low vapor pressure
component by the apparatus and method of the invention
also permits the use of smaller downstream components
and simplifies subsequent treatment of the discharged
vapor effluent.
Brief Description of the Drawings
Figure 1 is a section view of one embodiment of a
thermal removal system of the invention.
Figure 2 is a plan view taken along line II-II of ;~
the thermal removal system illustrated in Figure 1.
Figure 3 is a section view taken along line
III-III of the thermal removal system illustrated in
Figure 1.
Detailed Descri~tion of the Invention
The features and other details of the apparatus
and method of the invention will now be more
particularly described with reference to the
212130fi
--5--
accompanying drawings and pointed out in the claims.
The same number present in different figures represents
the same item. It will be understood that the
particular embodiments of the invention are shown by
way of illustration and not as limitations of the
invention. The principle features of this invention
can be employed in various embodiments without
departing from the scope of the invention.
The present invention generally relates to an
apparatus and method for preferentially separating at
least a portion of a high vapor pressure component from
a low vapor pressure component previously volatilized
from a matrix.
One embodiment of the invention is illustrated in
Figure 1. Therein, thermal removal system 10 includes
housing 12 having inlet end 14 and outlet end 16.
, Housing inlet 18 is disposed at inlet end 14 and
housing outlet 20 is disposed at outlet end 16. Lid 22
is disposed on housing 12. Housing chamber 24 is ~ - -
;l 20 defined by housing 12 and lid 22. Housing 12 and lid
22 can be insulated by layer 26 to prevent significant
heat loss from thermal removal system 10 through
housing 12 or lid 22.
, Means for conveying a matrix from housing inlet 18
c1 25 through housing 12 to housing outlet 20 are disposed
within housing 12. In one embodiment, the means for
conveying the matrix include screw conveyors 28,30.
Screw conveyors 28,30 are disposed within housing
chamber 20. Each screw conveyor includes a shaft 32
and flights 34 disposed about shaft 32. Additionally,
screw conveyors 28,30 each define a conduit 35
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212130~
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1 -6-
extending through shaft 32 and flights 34. Each
conduit 36 has an annular conduit inlet 38 and a
conduit outlet 40. Screw conveyors 28,30 are identical
s except that screw conveyors 28,30 are counter-rotating.
Screw conveyor 28 is a left-hand screw conveyor and
screw conveyor 30 is a right-hand screw conveyor.
Alternate suitable means for conveying matrix 42,
including, for example, belt conveyors, can also be
employed.
Housing 12 and screw conveyors 28,30 are disposed
at a slight incline from housing inlet 18 to housing
outlet 20 to substantially prevent discharge of matrix
~j which includes an appreciable amount of the
volatilizable components from thermal removal system
10. Preferably, the angle to the horizontal of the
incline is in the range of between about 1 and 15.
Housing 12 and screw conveyors 28,30 can be of a
suitable screw processor, such as is known in the art.
~ One example of a suitable screw processor is a "Holo~
;~ 20 Flite" type screw processor, disclosed in U.S. Patent
2,731,241 and in U.S. Patent 2,753,159. In a
particularly preferred embodiment, the screw processor
is a D7-10-6 model "Holo-Flite" screw processor,
commercially available from Denver Equipment Company.
~ 25 Volatilizable component-containing matrix 42 is
$~ directed from matrix source 44 by feeding means 46
?~ through housing inlet 18 into housing chamber 24.
Examples of suitable matrices containing volatilizable
components include sludges, contaminated soil, etc.
Examples of suitable sludges for removal of
volatilizable components from a matrix within the
?
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2121306
--7--
^` sludge by thermal removal system 10 include oil-
refinery sludges, wood treatment sludges, papermill
sludgesj etc. Examples of volatilizable contaminants
of which a portion can be removed from a matrix by
thermal removal system 10 include volatilizable organic
compounds, such as oils, gasoline, creosotes,
transformer fluids, etc.
A high vapor pressure component, as defined
herein, is a volatilizable component which will
volatilize from a matrix at a relatively low
temperature. A low vapor pressure component, as
defined herein, is a volatilizable component, which
will volatilize from a matrix at a temperature
significantly higher than the volatilization
15 temperature of the high vapor pressure component. -
In one embodiment, examples of high vapor pressure
components include water and organic chemicals which
have a vapor pressure greater than or about equal to
3~ that of water. Examples of corresponding low vapor
;~ 20 pressure components in this embodiment include organic
chemicals which have a vapor pressure which is
significantly lower than that of water.
~ The concentration of high vapor pressure and low
,~ vapor pressure components is sufficient to enable
25 removal of at least a portion of each of the two
~ volatilizable components from matrix 42 by
i volatilization in thermal removal system 10.
S Preferably, the combined concentration of volatilizable
components in matrix 42 before volatilization in
30 housing chamber 24 is less than about eighty percent by
weight.
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2121306
-8-
Matrix 42 is directed through housing inlet 18
~ into housing chamber 24 at a rate sufficient to allow
i at least a portion of each of the two volatilizable
components in matrix 42 to be volatilized by heat
transferred to matrix 42 from screw conveyors 28,30.
In one embodiment, matrix 42 is directed into housing
chamber 24 at a rate in the range of between five
hundred and about eight thousand pounds per hour. -~
' An example of a suitable feeding means 46 is an
t 10 air lock, or "double dump," wherein matrix 42 can be
directed into housing chamber 24 while maintaining a
significant pressure difference between housing chamber
24 and the atmosphere. Typically, housing chamber 24
is maintained at a pressure lower than atmospheric,
15 such as vacuum up to about 0.5 inches water. An
example of a suitable air lock is a 18-24-C model air
lock, commercially available from Prater Industries.
Screw conveyors 28,30 are in parallel arrangement
and are rotated by screw rotating means 48 in opposite
20 directions, whereby matrix 42 at housing inlet 18 is
conveyed by rotation of screw conveyors 28,30 from
housing inlet 18 to housing outlet 20. Conveyance of
matrix 42 through housing chamber 24 causes matrix 42
to form matrix bed 50 within housing chamber 24. In
25 one embodiment, matrix bed 50 has a depth in housing
chamber 24 sufficient to submerge a substantial portion
of screw conveyors 28,30. Preferably, the tops of
flights 34 are elevated about one-half inch above the
top of matrix bed 50. Matrix 42 is conveyed through
30 housing chamber 24 at a rate sufficient to allow at
least a portion of each of the two volatilizable
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212130~
g
components to volatilize by transfer of heat from screw
conveyors 28,30 to matrix 42. Preferably, screw
conveyors 28,30 are rotated at a rate in the range of
between about 0.5 and about 10.0 revolutions per
minute. In a particularly preferred embodiment, screw
conveyors 28,30 are rotated at a rate sufficient to
cause matrix 42 to have a residence time in housing
chamber 24 in the range of between about 20 minutes and -~
o minutes.
Means for volatilizing at least a portion of the
high vapor pressure component and the low vapor
pressure component of matrix 42 are disposed within
housing 12.
In one embodiment, a suitable means for
volatilizing the high and low vapor pressure components
in matrix 42 is provided by heating screw conveyors
28,30 to a temperature sufficient to volatilize at
least a portion of each of the two volatilizable
components. A suitable hot medium is directed from hot
medium source 52 through hot medium conduit 54 to
conduit inlet 38 by a suitable means, such as by
operation of a pump, not shown. The hot medium is then
directed from conduit inlet 38 through conduit 36 to
' conduit outlet 40. The rate at which the hot medium is
.~ 25 directed through conduit 36 is sufficient to cause
! turbulent flow of the hot medium and to heat screw
,: conveyors 2B,30 to a temperature sufficient to
volatilize at least a portion of each of the two
- volatilizable components from the matrix 42. At least
a portion of the high and low vapor pressure components
in matrix 42 are thereby volatilized and enter head
.
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2121306
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--10--
space 56, which is defined by housing 12, lid 22, and
matrix bed 50. The high vapor pressure component
volatilizes substantially at inlet end 14 of housing 12
~ while the low vapor pressure component, volatilizes at
,! 5 outlet end 16 of housing 12.
A suitable hot medium is a medium which can be
heated, without significant degradation, at hot medium
source 52 to a temperature sufficient to heat screw
conveyors 28,30 to a temperature sufficient to cause
10 screw conveyors 28,30 to volatilize at least a portion ~ ~:
of each of the two volatilizable components in matrix :.
42. Preferably, the hot medium is a liquid, such as an
oil or a eutectic salt solution.
In one embodiment, the medium is heated to a
i 15 temperature in the range between about 100C and about
600C. The medium can be heated by a suitable heating
means, not shown, such as is known in the art.
Gas inlet tube 58 is disposed in head space 56 and
includes gas inlet end 60 and sealed end 62. Apertures
64 are defined by gas inlet tube 58 and are disposed at
regular intervals along the length of gas inlet tube
58. Gas inlet tube 58 and apertures 64 each have a
diameter sufficient to allow a hot gas to be directed
through gas inlet tube 58 at a rate sufficient to
remove at least a portion of each of the volatilized
high and low vapor pressure components from head space
56 at the operating conditions of thermal removal
system 10. Preferably, gas inlet tube 58 has a
diameter in the range between about 0.125 and about two
inches. In a particularly preferred embodiment,
wherein housing 12, lid 18, and screw conveyors 28,30
,-1; - -
212130~
are a D7-10-6 model Holo-Flite screw processor, gas
inlet tube 58 has a diameter of about 1.75 inches and :
apertures 64 of about 3/32 inches. Alternatively, gas
inlet tube 58 can define a single slot, not shown,
extending along a substantial portion of the length of
gas inlet tube 58 rather than define a plurality of
apertures 64.
A first gas outlet and a second gas outlet are
disposed at housing 12, with the second gas outlet
situated at a location which is sufficiently remote
from the first gas outlet, to enable the preferential
separation of the volatilized high vapor pressure
component from the volatilized low vapor pressure
component of matrix 42.
In one embodiment, the first and second gas
outlets include gas outlet tubes 66,68. Gas outlet
tubes 66,6~ run along the length of housing 12 from
housing inlet 18 to housing outlet 20 and extend
outside of housing 12 through housing inlet end 14 and
through outlet end 16. The portions of gas outlet tubes
66,68 located in housing 12 are disposed in head space
56 and are substantially parallel to screw conveyors
28,30 and to gas inlet tube 58. Gas outlet tubes 66,68
are disposed on opposite sides of gas inlet tube 58.
First and second outlet ports 70,72 are defined by gas
outlet tubes 66,68 at regular intervals along the
length of gas outlet tubes 66,68 inside housing 12.
First outlet ports 70 are disposed at inlet end 14 of
housing 12 and second outlet ports 72 are disposed at
outlet end 16 of housing 12. First and second outlet
ports 70,72 are situated proximate to the surface of
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2~21306
-12-
matrix bed 50. The high and low vapor pressure
components volatilized from matrix 42 are directed into
gas outlet tubes 66,68 through outlet ports 70,72.
Gas outlet tubes 66,68 and outlet ports 70,72 each
have a diameter sufficient to allow at least a portion
of the volatilized components in head space 56 to
discharge into the gas outlet tubes 66,68 through
outlet ports 70,72 proximate to the locations within
housing 12 wherein the high and low vapor pressure
components volatilized from matrix 42. The preferred
diameters of gas outlet tubes 66,68 are four inches
outside diameter and of outlet ports 70,72 are five-
eighths inches.
Fluid communication is provided between hot gas
15 source 74 and gas inlet tube 58 by hot gas conduit 76
for directing a suitable hot gas from hot gas source 7
through hot gas conduit 76 into gas inlet tube 58.
Suitable gases are gases which are sufficiently stable
to transport the two volatilized components within head
space 56 without significant reaction with the two
I volatilizable components. Examples of suitable gases
I include steam, carbon dioxide, nitrogen, etc.
¦ Preferably, the hot gas is a substantially inert gas,
such as nitrogen.
The temperature of the hot gas is sufficient to
prevent significant condensation of the high or low
volatilized vapor pressure components in gas outlet
tubes 66,68. Preferably, the temperature of the hot gas
is in the range between about 31SC and about 540C.
The rate at which hot gas is directed into gas inlet
tube 58 is sufficient to cause the hot gas to pass
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21213~6 ~
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-13-
across matrix bed 50 at a rate sufficient to remove at
least a portion of the two volatilized components from
head space 56. In a particularly preferred embodiment,
the hot gas is nitrogen which is directed into gas
inlet tube 58 at a rate of about thirty cubic feet per
minute, a pressure of between thirty and eighty psig,
and a temperature of about 540C.
~ The hot gas is directed by a suitable delivery
; means from hot gas source 74 through hot gas conduit 7
and into gas inlet tube 58 through gas inlet end 60.
An example of a suitable delivery means includes a
suitable pressurizing means, not shown, such as is
known in the art, for applying pressure to hot gas at
hot gas source 74. The hot gas is then directed
15 through apertures 64 of gas inlet tube 58 into head
space 56 along at least a substantial portion of the
length of housing 12. Hot gas directed into head space
56 passes across the top of matrix bed 50 to gas outlet
tubes 66,68. The volatilized components in head space
20 56 are then transported by the hot gas to gas outlet
tubes 66,68 and through outlet ports 70,72 into gas
outlet tubes 66,68.
The two volatilized components in matrix 42 are
directed through outlet ports 70,72 into gas outlet
25 tubes 66,68 by reducing the pressure within gas outlet
tubes 66,68 to less than the pressure within head space
56. The pressures within gas outlet tubes 66,68 are
reduced by providing fluid communication between gas
Y outlet tubes 66,68 and a suitable vacuum means for
30 applying vacuum to gas outlet tubes 66,68, such as
vacuum pump 78, through header 80. The volatilized
.
21213~6
-14-
high vapor pressure component is preferentially
directed into gas outlet tubes 66,68 through a first
outlet port 70, which is disposed at inlet end 14 of
housing 12 and the volatilized low vapor pressure
component is preferentially directed through a second
outlet port 72, which is disposed at outlet end 16 of
housing 12.
A means for preferentially directing the
volatilized high and low vapor pressure components out
of housing 12 through the first and second gas outlets,
respectively, is disposed at housing inlet end 18 and
housing outlet end 20.
In one embodiment, a suitable means for
preferentially directing volatilized components
includes header 80, which is disposed outside of
housing 12 and includes a wye having two gas discharge
lines 82,84. Gas discharge line 82 connects to
portions of gas outlet tubes 66,68 which extend outside :
of housing 12 at inlet end 14. Gas discharge line 84
connects to the portions of gas outlet tubes 62,64
which extend outside of housing 12 at outlet end 16.
Operation of the vacuum pump 78 reduces the
pressure in head space 56 by preferentially directing
the two volatilized components from the matrix 42 and
any other gases present in head space 56 through outlet
ports 70,72, into gas outlet tubes ~6,68, bi-
directionally out of housing 12 through the portions of ~:
gas outlet tubes 66,68, extending outside of inlet end
14 and outlet end 16 into gas discharge lines 82,84 of
header 80.
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212130~
-15-
Gas discharge lines 82,84 include a separation
means, for removing at least a portion of a solid
component of the volatilized components discharged from
housing 12, a flow-control means, for controlling the
relative flow rates of the volatilized components
through gas discharge lines 82,84.
In one embodiment, in gas discharge line 82, a
suitable separation means is provided by cyclone
separators 86, a suitable flow-control means for
volatilized components in gas discharge lines includes
temperature monitors 88,90 and control valve 92. In
addition suitable condensing means is provided by first
off-gas control system gas.
Cyclone separators 86 are disposed in gas
discharge line 82 between vacuum pump 78 and gas outlet
tubes 66,68 and are proximate in position to the
juncture of gas outlet tubes 66,68 with gas discharge
line 82. Temperature monitor 88 is disposed in gas
discharge line 82 between vacuum pump 78 and cyclone
separators 86. Temperature monitor 88 measures the
temperature inside gas discharge line 82, thereby
measuring the temperature of the volatilized components
directed through gas discharge line 82. Control valve
92 is disposed in gas discharge line 82 between vacuum
pump 78 and temperature monitor 88. Control valve 92
is adjusted to throttle the relative flow rates of the
two volatilized components and other gases directed
from head space 56 through gas discharge lines 82,84. ~ ;
Temperature monitor 90 is disposed in gas discharge
line 84 between vacuum pump 78 and gas outlet tubes
66,68. Temperature monitor 90 measures the temperature
:
2121306
-16-
~~ inside gas discharge line 84, thereby measuring the
:~ temperature of the volatilized components directed
`' through gas discharge line 84.
'I First off-gas control system 94 is disposed in gas
discharge line 82 between control valve 92 and
temperature monitor 88. First off-gas control system
94 condenses a portion of the volatilized component
directed from head space 56 into gas discharge line 82.
Condensate from first off-gas control system 94 is
condensed by a suitable means, such as an indirect heat
exchanger i.e. a shell-and-tube heat exchanger.
Gas discharge line 82 also includes temperature
monitor 96 which is disposed in gas discharge line 82
between control valve 92 and first off-gas control
system 94. Temperature monitor 96 measures the
temperature of the non-condensed gases flowing in gas
discharge line 82 from first off-gas control system 94.
: In a preferred embodiment, the temperature inside gas
discharge line 82, as measured by temperature monitor
96, is about 100F.
'`Preferential separation," as that term is
employed herein, means the separation of a high vapor
pressure component from a low vapor pressure component,
wherein a substantial portion of the volatilized high
vapor pressure component is discharged from the housing
through one outlet at the housing and a substantial
. portion of the volatilized low vapor pressure c~mponent
is discharyed through a ceparate outlet at the housing.
The valve position of control valve 92 is
~L; 30 throttled to preferentially direct the volatilized high
;~. vapor pressure component from head space 56, through
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212130~
first outlet ports 70, in inlet end 14 of housing 12,
into outlet tubes 66,68 and then, into gas discharge
line 82. Control valve 92 is throttled to maintain the
temperature inside of gas discharge line 82, as
measured by temperature monitor 88, in a temperature
range which causes a substantial portion of the
volatilized high vapor pressure component to separate
from the volatilized low vapor pressure component. In
one embodiment, control valve 92 is adjusted to cause
the temperature in gas discharge line 82 to stay
significantly below the saturation temperature of the
low vapor pressure component and to cause the
temperature of the volatilized low vapor pressure
component in gas discharge line 84, as measured by
temperature monitor 90, to stay above the saturation
temperature of the low vapor pressure component. As a
result of throttling control valve 92, the volatilized
low vapor pressure component is preferentially directed
from head space 56, through outlet ports 72, in outlet
end 1~ of housing 12, into outlet tubes 66,68, and then
into gas discharge line 84. Consequently, a
substantial portion of the high vapor pressure
component is preferentially separated from the low
vapor pressure component.
In a particularly preferred embodiment, water
volatilized as the high vapor pressure component, is
substantially separated from oil, which is the
volatilized low vapor pressure component, by adjusting
the openins of control valve 92 to maintain the
temperature inside of gas discharge line 82, as
measured by temperature monitor 88, between about 220F
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- -18-
~ and 250F. Consequently, the temperature of the
~ volatilized low vapor pressure component inside of gas
Z discharge line 84, as measured by temperature monitor
90, is maintained generally above 250F and typically
5 about 700F.
In this embodiment to adequately separate water
from oil and produce relatively oil-free water, the
opening of control valve 92 is established to maintain
a sufficiently low temperature inside gas discharge
10 line 82, as measured by temperature monitor 88, thereby
substantially ensuring that no significant amount of
! oil vapor will pass from matrix 42 into gas discharge
line 82. However, the opening of control valve 92 is
also set to maintain a sufficiently high temperature,
15 as measured by temperature monitor 88, thereby removing
a substantial portion of the water vapor from matrix 42
through gas discharge line 82.
In one embodiment gas discharge line 84 also
includes a suitable separation means, such as cyclone
20 separators 98 and a suitable condensing means, as
provided by second off-gas control system 100. Cyclone
separators 98 are disposed in gas discharge line 84
between temperature monitor 90 and gas outlet tubes
66,68 and are proximate in position to the juncture of
gas discharge line 84 and gas outlet tubes 66,68.
Cyclone separators 86,98 substantially strip
entrained solids and dust from the gases entering gas
~i discharge lines 82,84 from gas outlet tubes 66,68.
::~ Cyclone separators 86,98 are also heated by suitable
means, such as heat tracing, to substantially preclude
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~1~130~
.. --19--
the condensation of volatilized components from matrix
42 inside cyclone separators 86,98.
Second off-gas control system 100 is disposed in
gas discharge line 84 between temperature monitor 90
and vacuum pump 78. Second off-gas control system 100
condenses a portion of the volatilized component
directed from head space 56 into gas discharge line 84.
Condensate from second off-gas control system 100 is
; condensed by a suitable means, such as an indirect heat
exchanger or a shell and tube heat exchanger.
Temperature monitor 102 is also disposed in gas
~ discharge line 84 between vacuum pump 78 and secondq off-gas control system 100. Temperature monitor 102
measures the temperature of the non-condensed gases
~, 15 flowing in discharge line 84 from the second off-gas
control system 100.
In a particularly preferred embodiment, second
off-gas control system 100 is operated in a manner ~:
suitable to condense the oil vapor in gas discharge
l 20 line 84, such that no significant amount of oil vapor ~ :
is discharged from second off-gas control 100, but to
not condense the water vapor so that a substantial ;~
portion of the water vapor present will not condense. ~- :
In this embodiment, the temperature measured by
temperature monitor 102 is about 212~F. -
Additionally, in another preferred embodiment, the
preferential separation of the volatilized high vapor
pressure component from the volatilized low vapor
pressure component is enhanced through suitable testing
of the condensates discharged from first off-yas
control 94 and second off-gas control 100, followed by
i
2121306
-20-
adjustments to the valve position of control valve 92 :~
desired to alter the relative flow rates of volatilized
high and low vapor pressure components through gas
discharge lines 82,84.
Header 80 also includes third off-gas control
system 104 and temperature monitor 106. Third off-gas
control system 104 is disposed between vacuum pump 78
and gas discharge lines 82,84. Third off-gas control
system 104 condenses at least a portion of any high
vapor pressure component not condensed by first and
second off-gas control systems 94,100. Temperature ~
monitor 106 is disposed between vacuum pump 78 and
third off-gas control system 104. Temperature monitor
106 measures the temperature of the non-condensed gases
in header 80 flowing out of third off-gas control
system 104.
In a particularly preferred embodiment, wherein
the high vapor pressure component is water and the low
vapor pressure component is oil, third off-gas control :
system 104 is operated to condense at least a portion
of non-condensed water vapor discharged from first and
second off-gas control systems 94,100. In this
embodiment, the temperature inside header 80 as
measured by temperature monitor 106 is typically below
50F.
In a further embodiment, baffles 108 are disposed
within head space 56, above screw conveyors 28,30,
below gas inlet tube 58, and between gas outlet tubes
66,68. Baffles 108 are disposed perpendicular to a
major axis of screw conveyors 28,30, gas inlet tube 58,
and gas outlet tubes 66,68. Baffles 108 significantly
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impede confluence of the volatilized high and low vapor
pressure components above matrix bed 50 by
substantially restricting migration of the volatilized
components from locations in head space 52 proximate to
the locations at which the components were volatilized.
This impedance of volatilized component confluence
thereby enhances the separation of the two volatilized
components directed into gas discharge lines 82,84
, through the gas outlet tubes 66,68.
Preferably, the vacuum attained in head space 56
- through gas discharge lines 82,84 of header 80 and gas
outlet tubes 66,68 by vacuum pump 78 reduces the
pressure in housing chamber 24 in an amount sufficient
to prevent significant leakage of volatilized
components to the atmosphere. In a particularly
preferred embodiment, the pressure in housing chamber
24 is in the range of up to about 0.5 inches of water
below atmospheric pressure.
Matrix 42, from which at least a portion of the
, 20 high and low vapor pressure components have been
removed, is then directed through housing outlet 20 by
gravitational force and into air lock 110. Matrix 42
j! is then discharged from thermal removal system 10 into
a suitable matrix receiving means, such as bin 112.
. 25 Housing 12, lid 22, screw conveyors 28,30, gas
~l inlet tube 58, and gas outlet tubes 66,68 are formed of
;~ materials which are suitable for contact with
volatilizable component-containing matrices at
temperatures of up to about 540C. Examples of
~; 30 suitable materials of construction include 304-type
stainless steel, 316-type stainless steel, incoloy,
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hastelloy, etc. Preferably, screw conveyors 28,30 are
formed of stainless steel having a nickel content which
is at least that of 304-type stainless steel.
As can be seen in Figure 2, gas inlet tube 58
5 extends along a substantial portion of the length of -.
housing chamber 24 and is disposed centrally to the
width of housing chamber 24 above screw conveyors
28,30. Gas outlet tubes 66,68, extend within head
space 56 of housing chamber 24 on opposite sides of gas
inlet tube 58 and along the length of housing 12 from
inlet end 14 to outlet end 16. Portions of gas outlet
tubes 66,68 protrude through inlet end 14 and through
outlet end 16. The portions of gas outlet tubes 66,68
within head space 56 are also disposed outwards of
screw conveyors 28,30. Outlet ports 70,72 in gas .
outlet tubes 66,68 are disposed in close proximity to
apertures 64 in gas inlet tube 58.
Hot gas directed into gas inlet tube 58 is
discharged into housing chamber 24 through apertures 64
so that hot gas is discharged into housing chamber 24
along a substantial portion of the length of housing
12. Hot gas discharged through apertures 64 passes
over matrix bed 50 toward outlet ports 70,72 at gas
outlet tubes 66,68 in a direction substantially
perpendicular to the path of matrix 42. The hot gas
flow, from apertures 64 to first outlet ports 70 at gas
outlet tubes 66,68, that preferentially transports the
volatilized high vapor pressure component from matrix
bed 50 into gas outlet tubes 66,68, is shown as arrows
114,116.
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The flow of hot gas, from apertures 64 to second
outlet ports 72 at gas outlet tubes 66,68, that
transports preferentially the volatilized low vapor
pressure component from matrix bed 50 into gas outlet
tubes 66,68, is shown as arrows 118,120.
screw conveyor 28 has a left-hand orientation and :
screw conveyor 30 has a right-hand orientation, whereby
counter-rotation of screw conveyors 28,30 causes matrix
42 in matrix bed 50 to be conveyed in a single
direction through housing chamber 24 to housing outlet
20. Flights 34 of screw conveyor 28 are in non- :
interfering relation with flights 34 of screw conveyor ~:
30.
Figure 3 is a section view of thermal removal
~ 15 system 10 taken along line III-III of Figure 1. . ~ ;
¦ Flights 34 of screw conveyor 28 slightly overlap ~ ~:
flights 34 of screw conveyor 30. Arrows 122,124,
indicate the direction of rotation of screw conveyors ~:
28,30, respectively. Rotation of screw conveyors
~ Z0 28,30, in the directions indicated by arrows 122,124,
$ can cause matrix 42 in matrix bed 50 to move at the top : ~
of matrix bed 50 toward-the center of housing chamber ~ : :
24 as indicated by arrows 126,128.
Volatilizable components which have been
volatilized by heat conducted from screw conveyors
28,30 to matrix bed 50 enter head space 56. The
volatilized components are thereby directed into head
space 56. Volatilized low vapor pressure component in
head space 56 is then transported through outlet ports
70,72 into gas outlet tubes 66,68 by reducing the
2 gaseous pressure within head space 56 by the flow of
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hot gas from apertures 64 of gas inlet tube 58 over
matrix bed 50 and into outlet ports 70,72 in gas outlet
tubes 66,68. At least a portion of the high and low
vapor pressure volatilized components are
preferentially directed to outlet ports 70,72,
respectively, proximate to the surface of matrix bed 50
~/ and proximate to the location along the length of
:~ housing chamber 24 from which the volatilizable
components were volatilized from matrix bed 50 into
' 10 head space 56.
. The volatilized components are then preferentially
.~ directed through outlet ports 70,72, respectively, into
gas outlet tubes 66,68, and out of housing 12. Arrows
130,132, indicate the direction of flow of hot gas from
apertures 64 of gas inlet tube 58, over matrix bed 50,
through head space 56, and into second outlet ports 72
at gas outlet tubes 66,68.
As screw conveyors 28,30, continue to rotate,
volatilizable component-containing matrix 42 which has
been introduced into housing chamber 24, is directed to
housing outlet 20. The volatilized components enter
head space 56 and are transported out of head space 56,
by hot gas discharged from apertures 64 over matrix bed
l 50, through outlet ports 70,72 into gas outlet tubes
~$ 25 66,68. The partial pressure of volatilized components
' in head space 56 is thereby maintained at a level that
is sufficiently low to prevent significant leakage of
volatilized volatilizable components from housing 12 as
i matrix 42 is directed along matrix bed 50 to housing
i 30 outlet 20.
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Equivalents :~
Those skilled in the art will recognize, or be
able to ascertain using no more than routine
experimentation, many equivalents to specific ~.
embodiments of the invention described specifically
herein. Such equivalents are intended to be ~ ~i
encompassed in the scope of the following claims.
~';
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