Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
BACKGROUND OF THE INVENTION 13 31~ 73
2 (i) Field_of the Invention
3 The present invention pertains in one aspect to an
4 improved version of a dry thermal processor for extracting
volatile substances from a particulate host material. The
6 processor is of the type incorporating horizontal, concentric,
7 substantially co-extensive, inner and outer tubular members which
8 are interconnected and which rotate together about a horizontal
9 axis. The feedstock enters at one end of the inner tubular
member, advances through it, and is heated by hot solids
11 returning through the annular space between the tubes.12 In another aspect, the invention pertains to an
13 improved version of the process wherein the feedstock is
14 initially advanced through the inner tubular member and is heated
in two stages, firstly to vaporize water contained in the
16 feed6tock and secondly to pyrolyse hydrocarbons and produce coked
17 solids. The coked solids are transferred into the annular space,
18 wherein the coke is burned to produce hot 601ids. Part of the
19 hot solids is recycled into the hydrocarbon vaporization or
reaction zone to provide needed heat for that zone. The balance
21 of the hot solids is returned through the annular space and is
22 used to transfer heat into the water vaporization or pre-heat
23 zone by contact with the wall of the inner tubular member.
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1 (ii) Prior Art
2 The present invention relates to improved versions of
3 the processor and the process disclosed in U.S. Patents 4,280,879
4 and 4,285,773.
A pilot plant-scale processor in accordance with the
6 patents was built and operated on an experimental basis for a
7 number of years. In the course of the work, certain problems
8 were ascertained and solutions to the problems were developed.
9 The processor and its method of operation were signifioantly
modified. The modified versions of apparatus and process provide
11 the basis for the present invention.
12 The patented processor was originally designed with
13 the primary objective of extracting hydrocarbons from the oil
14 sands of the Athabasca region in Northern Alberta. Such oil
sands typically comprise grains of sand individually sheathed in
16 a thin membrane of connate water. The water contains minute clay
17 particles. Bitumen is trapped in the interstices between the
18 water-shèathed sand grains. Stated otherwise, oil sand is a
19 mixture of particulate solids, water and hydrocarbons. The prior
processor was designed to recover some of the hydrocarbons,
21 separate from the water and solids.
22 In the course of the piloting work, the patented
23 processor and its method of operation were shown to be applicable
24 to feedstock other than oil sand. Such ~feedstock also involved
a mixture of particulate solids, water and volatile substances
26 (including hydrocarbons). More specifically, the processor was
27 operated to treat crushed oil shale and contaminated soil
28 mixtures from waste dumps, with beneficial results.
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1 In its original form, the patented processor
2 broadly involved the following:
3 - A pair of concentric, substantially co~
4 extensive, horizontal, radially spaced apart
inner and outer tubes (sometimes referred to
6 as "tubular members") were provided. The
7 tubes were rigidly interconnected and adapted
8 to be rotated together about their
g longitudinal axis;
lo ~ There was thus formed an enclosed, elongate,
11 cylindrical inner space and an enclosed outer
12 annular space. These spaces or passageways
13 were "open", in the sense that they were
14 substantially unobstructed except as described
below;
16 The cylindrical inner passageway was divided
17 at a point along its length by a transverse
18 baffle into an upstream water vaporization
19 sone (or "pre-heat'l zoneJ and a downstream
hydrocarbon vaporization zone (or "reaction"
21 zone). The baffle was supplied to assist in
22 segregating the gaseous atmospheres of the
23 pre-heat and reaction zones. Spiral open-
24 ended chutes were associated with the baffle
and formed passages extending through the
26 baffle at its periphery. These passages
27 enabled solids to move from the pre-heat zone
28 into the reaction zone. The presence of the
29 solids in the chutes combined with the
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1 presence of the baffle itself to substantially
2 prevent the movement of gases from one zone to the
3 other;
4 - A conveyor extended through a first end frame for
feeding feedstock into the first end of the pre-
6 heat zone;
7 - Screwing elements, such as upstanding plates
8 angled relative to the longitudinal axis of the
9 inner tube, were secured to the inner surfaces of
the inner and outer tubes, to add fine control for
11 advancing or retarding the movement of solids
12 through the inner space and the annular space;
13 - A first fan system, having a conduit extending
14 into the pre-heat zone, provided suction and means
for withdrawing water vapour and light hydrocarbon
16 vapours from said zone;
17 - A second fan system, having a conduit extending
18 into the reaction zone, provided suction and means
19 for withdrawing hydrocarbon vapours therefrom;
- A baffle and seal assembly was provided at ths
21 second end of the inner tube. This baffle and
22 seal assembly was also of the previously described
23 spiral chute type and was adapted to prevent gas
2.4 movement between the reaction zone and the annular
space, while still enabling coked solids to move
26 from the reaction zone into the second end of the
27 annular space;
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1 - The annular space provided a combustion zone
2 at its second end and a heat transfer zone at
3 its first end;
4 - An air injection system was provided to supply
pre-heated air through the second end frame
6 into the combustion zone, for supporting
7 combustion of the coked solids;
- A gas burner fire tube also projected through
g the second end frame into the combustion sone;
0 - A recycle assembly, connecting the annular
11 space with the first or upstream end of the
12 reaction zone, was provided at the first or
13 downstream end of the combustion zone, for
14 transferring some of the hot solids, leaving
the combustion zone, back into the reaction
16 zone. The recycle assembly invol~ed a spiral
17 chute coiled around the inner tube and
18 extending through the tube wall. The chute
19 was adapted to scoop hot solids from the
annular space and, as a result of rotation
21 with the inner tube, to deliver the solids to
22 the combustion zone. The chute and its load
23 combined to substantially prevent gas movement
2q between the annular space and the reaction
zone;
26 - - There were lifter elements attached to the
27 inner surface of the outer tube in both the
28 combustion and heat transfer zones. In the
29 cor~oustion zone, these lifter~2 ~ould drop the
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1 coked solids particles in dispersed, curtain-
2 like fashion through the injected air, to
3 encourage combustion. In the heat transfer
4 zone, the hot solids were lifted and cascaded
onto the pre-heat portion of the inner tube,
6 to supply heat to the tube wall by solid-to~
7 solid heat transfer;
8 - A third fan system, having a conduit extending
g into the annular space, provided suction and
means for withdrawing the flue gases
11 therefrom; and
12 - Means, such as a conveyor, extended through
13 the first end frame for removing cooled solids
14 from the downstream end of the annular space.
In the operation of the prior art processor, the
16 following occurred-
17 - T~e feedstock was heated in the pre-heat zone
18 by heat transfer through the tube wall. In
19 the case of oil sand, large cohesive chunks
were ablated by the heating and mild cascading
21 action within the rotating inner tube.
22 Contained water and the lightest, low boiling
23 point hydrocarbons were vaporized and removed
24 by the first fan system. And the contained
rocks were freed from the rest of the oil
26 sands so that they could be separated by
27 screening at the downstream end of the zone
28 and removed from the main feed stream;
l - In the reaction zone, the pre-heated feed was
2 mixed with hot solids recycled from the
3 annulus, to thereby raise the temperature of
4 the feed. Hydrocarbons were vaporized and
cracked. Residue coke formed on the solids
6 particles. And the hydrocarbon gases were
7 separately recovered by the second fan system;
8 - In the combustion sone, the coked solids were
g lifted and dropped through the injected air
and burned to yield hot solids. The solids
11 were also heated in part by the auxil.ary
12 heater. Part of the hot solids was recycled
13 into the reaction zone, to supply the heat
14 needed to raise the temperature of the feed to
the desired hydrocarbon vaporising/cracking
16 temperature. And the balance of the hot
17 solids was advanced into the heat transfer
18 sone of the annulus;
19 - In the heat transfer zone, the hot solids were
lifted and dropped onto the pre-heat portion
21 of the inner tube, to heat the inner tube wall
22 as required;
23 _ And the suction systems plus the seal devices
24 were used to substantially isolate the pre-
heat, reaction and annular zone gaseous
26 atmospheres, one from another.
27 In a broad context, the processor can be
28 characterized as a self-powered heat transfer machine. Among
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1 the factors that require attention in its design are the
2 following:
3 - Heat must be transferred from the hot solids,
4 moving through the annular space, to the cool
solids moving through the pre-heat zone. The
6 transfer of heat must be sufficient so that the
7 exit temperature of the bed of feed in the pre~
8 heat zone is raised from ambient to a temperature
9 at which vaporization of watér contained in the
feed will be essentially complete, without
11 significant vaporization of hydrocarbons. In the
12 case of oil sand, this exit temperature should
13 typically be about 550F;
14 - Such transfer of heat is affected by the extent
of contact between the hot solids and the pre-
16 heat zone tube wall, the temperature and volume
17 of the hot sand cascaded, the conductance of heat
18 through the tube wall, the transfer of heat from
19 the tube wall into the feed bed, and the movement
of heat through the bed itself;
21 - Combustion of the coked solids and auxiliary fuels
22 must be sufficient to raise the temperature of the
23 solids to the desired value (in the case of oil
2~4 sand~ typically about 1300F), needed to satisfy
the heat demands of the pre-heat and reaction
26 zones;
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1 - The quantum of heat transferred into the reaction
2 zone by recycle of hot solids must be sufficient
3 to achieve the increase of temperature of the feed
4 in the reaction zone which is needed to crack the
hydrocarbons and produce lighter molecular weight
6 hydrocarbons and coked solids;
7 - The foregoing factors must be obtained while
8 maintaining segregation of the gaseous products,
9 80 that contamination and hydrocarbon losses are
minimal; and
11 - The machine is cubject to elongation, expansion ;;
12 and contraction due to variations in temperature
13 to which it is subjected. The outer tube is
14 internally insulated and thus is not heated to a
high temperature. The lnner tube is, however,
16 heated to high temperature. Therefore, there is
17 a significant difference in the axial and radial
18 expansions of the two metal tubes. Therefore, the
19 processor needs to be designed to aocommodate the
relatlvely different physlcal changes whlch occur
21 wlth heatlng.
22 It wlll be understood that there are a number of
23 operating parameters whlch become generally fixed. For example,
24 the rate of feed addition, the rate of reaycle of hot sand to the
reaction zone, and the rate of hot sand movement through the
26 annular space all become relatively steady. -~
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1 It also will be understood that, for the majority of
2 operations, addition o~ supplemental heat is to be minimized, as
3 auxiliary or off-site fuel would be a significant cost factor in
4 the operation of the processor.
And it will further be understood that the machine
6 should be kept as short as possible.
7 With the foregoing background in mind, it is now
8 appropriate to summarize the invention.
9 SUMMARY OF THE INVENTION
In accordance with one aspect of the invention, a
11 processor of the type described is provided with at least one
12 circumferentially corrugated pre-heat tube. In larger forms of
13 the processor, processing a high throughput of feedstock, a
14 plurality of pre-heat tubes are used.
The plurality of pre-heat tubes are preferably
16 interconnected, to form a rigid beam-like structure. The pre-
17 heat tubes also preferably are each formed with a
18 circumferentially corrugated configuration. The corrugated
19 configuration refers to a folding of the shell surface to obtain
a larger surface area within an equivalent length. As previously
21 stated, in the case of very low throughput processors there may
22 not physiaally be enough room for more than one tube. In this
23 circumstance, a single pre-heat tube is provided having a
24 corrugated wall.
As a result of using a pre-heat tube having a
26 corrugated wall, and preferably using a plurality of such
27 corrugated pre-heat tubes, a pre-heat section of relatively
28 high surface area is provided in the shortest processor
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1 length. sy providing increased tube sur~ace area, the heat
2 transfer capacity of the pre-heat tube section is greatly
3 increased.
4 In test work carried out with the pilot processor, it
was discovered that it was relatively easy to bring the required
6 heat to the inside surface of the pre-heat tube. But it was
7 found that the heat did not conduct well through the bed of
8 angular sand particles, which commonly are in point-to-point
9 contact and which do not roll to any significant extent within
the bed. Because of the relatively low heat conductivity of the
11 bed, either the pre-heat zone surface area had to be increased
12 by lengthening the zone or the material throughput had to be
13 reduced in order to reach the desired end temperature. Another
14 affect of unresolved low heat transmission was the poor cooling
of the exiting annular solids. This resulted in excessive solids
16 discharge temperatures.
17 The utilization of a plurality of pre-heat tubes,
18 particularly circumferentially corrugated tubes, significantly
19 alleviates these problems by greatly increasing the quantum of
heat transferred from a quantum of annulus solids into a quantum
21 of feed in a specific time period.
22 The problem is preferably further alleviated by
23 controlling the bed width in a pre-heat tube so that the minimum ~-r~
24 angle, formed by imaginary lines exten~ing radially from the
edges of the bed to the axis of the tube, is in the order of
26 about 110 degrees. By using a bed of these dimensions, there is
27 ensured a broad contact area between the hot steel of the pre-
28 heat tube and the bed of feed.
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1 In summary then, by dint of experimentation we have
2 ascertained that a single tube, plain cylindrical shell pre-
3 heat assembly requires an undesirably low feed rate or an
4 inordinately long pre-heating tube in order to achieve the
desired oil sand bed end temperature. Having ascertained the
6 problem, we have developed a novel processor which is better
7 able to cope with this difficulty.
8 In another preferred aspect of the invention, the
9 plurality of pre-heat tubes are arranged in a ring-like
pattern and a rock recycle tube is provided to extend along
11 the center line of the ring. Means, such as a screen and
12 chute assembly, recovers oversize rocks and lumps from the
13 feed at the downstream end of the pre-heat zone and transfers
them into the rock recycle tube, for return to the feed end
of the processor for removal. This change removes the rocks
16 from the processor in a way such that they will not damage
17 the lifters in the annular space. It was found in the
13 piloting program that the lifters are relatively fragile and
19 become damaged when impacted by the rocks. In the smaller
20 implementation of the processor, using a single pre-heat
21 tube, this rock recycle tube is also provided, centrally
22 located internal to the inner tube.
23In the course of processing oil sand with the pilot
2g processor, it was also discovered that a tarry deposit would
build up on the inner surface of the pre-heat tube,
26 particularly at its downstream end (which is the hottest
27 end). This deposit was found to have an inhibiting effect on
28 heat transfer from the tube steel wall into the feed bed.
29 Two solutions to this problem suggest themselves. One could
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1 overdesign the processor to ensure that production targets
2 could be met in spite of the build-up of such a deposit. The
3 deposit could then be cleaned out during periodic shut-downs
4 of the line. Or one could devise a means for removing the
deposit on an on-going basis or a means for preventing its
6 formation. We chose to explore the latter solutions.
7 As a first attempt to eliminate the deposit, chains
8 were hung within the tube to slap against the deposit to -~
9 dislodge it. These chains were unsuccessful. Then a
stainless steel liner was applied to the inner surface of the
11 pre-heat tube at its downstream or second end. It was
12 anticipated that the slick surface of the liner, in
combination with a slightly lower shell surface temperature,
14 perhaps lower than the cracking temperature for oil sand,
would eliminate the build-up. However, the liner was also
16 not successul in sufficiently relieving the problem. It was
17 eventually noted that rocks present in the feed were
18 collecting at the pre-heat zone end and were impacting
19 against the tarry layer and shearing it away in chunks.
However, the quantities of rocks associated with the oil sand
21 .eeds treated by the processor were insufficient to
22 satisfactorily control the fouling of the pre-heat tube.
23 It is therefore a preferred aspect of the invention
24 to recycle some of the rocks, returning through the rock
recycle tube, back into the first ends of the pre-heat tubes,
26 to thereby maintain an increased concentration of rocks in
27 the feed, for purposes of removing the tarry deposit.
28 In another preferred aspect of the invention,
29 modifications are made to alleviate the problems arising from
14
7 3
1 the differential thermal expansions and contractions which
2 characterise the inner and outer tubular members. As
3 previously stated, the outer tubular member is internally
4 insulated with refractory. The outer steel tube thus remains
5 relatively cool and its expansion or contraction due to
6 thermal effects is relatively minor. However, the inner
7 tubular member is within the insulation and expands and
8 contracts significantly when the processor changes between
g the operative hot and inoperative cold modes.
lo In the case of the pilot processor, the problem of
11 differential thermal expansion was recognised but not
12 successfully dealt with. The first end of the inner tubular
13 member was supported by spring washer-loaded support posts.
14 These eventually failed and solid posts were welded in place.
15 This approach was subject to eventual cracking of the weld
16 sites. The support of the second end of the inner tubular
17 membèr was originally a group of similar spring washer-
18 loaded, inclined, multiple post supports. This latter
19 assembly eventually failed as well and was replaced by
20 multiple vertical post supports welded to the two tubular
21 members.
22 The original connection of the inner and outer
23 tubular members at the junction of the pre-heat and reaction
24 zones was a spring connected structure wherein radial motion
25 flexed the springs in one plane, while inner member support
26 was provided by the stiff section of the spring in the other
27 plane. After significant operation, inspection of this area
28 revealed cracked welds. Modifications were made to this
29 area. More particularly, a plurality of internal pins, which
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were capable of radial growth, were installed but were
2 restrained from axial and torsional raovements by thrust
3 blocks. This system lasted only a short time before the
4 welds failed. Another modification was made. This second
system involved a solidly welded structure offering some
6 radial flexibility due to outer member solid blocks being
7 welded in the middle of a wide flange which was subsequently
8 welded at either edge to the inner member. Post operation
g inspection has not yet revealed cracking at the connection
lo sites.
11 Investigation of alternate design aspects for this
12 area resulted in the conception of several solutions
13 involving uncoupling the inner and outer tubular members and
14 enabling free and independent movement of the tubular members
in a radial direction with respect to each other, while
16 preventing movement in the axial and rotational directions.
17 These concepts produced mechanically complex arrangements,
18 with components prone to wear and a requirement for periodic
19 replacement.
Recognizing the inherent simplicity and security of
21 the rigid connection, it was determined that the key was not
22 to accept differential radial expansion and work around it
23 but to work with it and manipulate the intensity of
24 differential movement.
25To accommodate the relative dimensional changes of
26the tubular members, there is now provided one or more
27preferred features, namely:
28- Neans are provided for supporting the pre-heat
29tubes of the inner tubular member at their
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1 feed ends in a vertical direction, against
2 sagging, said means being operative to permit3 limited axial elongation or contraction of the
4 tubes. Preferably such means comprises an
inwardly extending thin steel membrane or wall
6 which provides vertical support for the tubes but
7 can bend to accommodate their axial elongation or
8 contraction;
9 - Means are provided, at about the junction of the
pre-heat and reaction zones, for locking the inner
11 and outer tubular members together for rotation
12 as a unit, for pinning them together to prevent
13 relative axial displacement, and to æupport and
14 centralize the inner tubular member in the outer
tubular member. These means are adapted to
16 accommodate differential radial expansion and17 contraction of the two tubular members.
18 In one form, such means may involve providing19 radial spokes extending between the two
tubular members and being solidly secured to
21 each of them. The materials, from which the
22 spokes and the outer tubular member shell (in23 the vicinity of the spokes) are made, are
24 preferably complementary, to minimize the
difference in expansion and contraction. For
26 example, the outer tubular member shell may be
27 formed of material having a relatively high
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1 thermal coefficient of expansion (e.g. an
2 austenitic stainless steel). The spokes, and
3 perhaps the inner tubular member in the vicinity
4 of the spokes, may be formed of material having
a relatively low thermal coefficient of expansion
6 (e.g. a Ni-Cr alloy steel). In a preferred
7 embodiment, the spoke may be hollow and air-
8 cooled through an aperture formed in the outer
9 tubular member.
In another form, the means may comprise a peg-
11 and-socket system wherein one tubular member
12 carries spoke6 and the other carrles sockets which
13 lock onto the spokes but permit of limited radial
14 expansion; and
- Means are provided for supporting the vaporization
16 tube against sagging, while permitting of axial
17 elongation and contraction. Such means may
18 comprise a loosely fitting collar supporting the
19 tube and tangential struts, pivotally secured to
the collar, extending out and affixed to the outer
21 tubular member.
22 In summary then, the spokes and the wall of the outer
23 tubular member at the spokes are adapted to expand and contract
24 substantially the same amount even though the tubular members are
at differing temperatures along most of their length.
26 In another preferred aspect of the invention, a
27 novel riding ring assembly is provided. In applications such
28 as oil sand processing, the processor necessarily has to be
29 very large to process the large tonnages of feedstock that
are needed for economic viability. A typical outer tube
31 diameter might be 30 feet. To rotate and support an outer
18
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1 tube, it would be conventional in the kiln art to use a
2 riding ring having circumferential gear teeth, to be acted on
3 by a driven roller gear. Conventionally, a riding ring would
4 be a cast one-piece steel element or a bolted-together
sectional ring. However toothed ring assemblies having a
6 large diameter tend to oval and are subject to alignment
7 problems.
8 In accordance with a preferred feature of the
g invention, a sectional riding ring assembly comprising inner
and outer ring members is provided. The ring members are
11 radially spaced apart and interconnected by circumferentially
12 spaced apart struts that function as heat-dissipating fins.
Rubber tires are used to support and drive the ring assembly.
This riding ring arrangement is characterized by
the following advantages:
16 the use of tires accommodates alignment
17 changes and reduces the observance of tight
18 tolerances in machining the assembly;
19 - the struts protect the tires from being
damaged by the full extent of the heat
21 associated with the inner ring member of the
22 assembly; and
23 - the tires better spread the load.
24 In accordance with another preferred feature, the
solids transfer chutes associated with the reaction zone are
26 modified by providing internal transverse weirs at spaced
27 points along their passageways. The weirs cause the sand
28 charge moving through the chute passageway to create a
29 plurality of sand seals or plugs along the length of the ~
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1~31573
1 passageway. These multiple plugs reduce the leakage of gas
2 through the passageway. Gas trapped between the plugs has an
3 opportunity to escape back to its original zone through the slots
4 between the weirs and the chute wall. As a result of
incorporating the weirs, the product yield from the reaction zone
6 is enhanced and its contamination is reduced.
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7 DESCRIPTION OF THE PRAWINGS
8 - Figure 1 is a schematic side view of a single pre-heat
9 tube version of the processor, with arrows of different types
indicating the various streams that would be present in
11 connection with oil sand processing;
12 Figure 2 is a sectional side view showing both the
13 inner and outer tubular members for a multiple pre-heat tube
14 processor;
Figures 3 - 6 are sectional end views taken along the
16 lines 3--3, 4--4, 5--5, and 6--6 respective of Figure 2;
17 Figure 7 is a sectional side view showing both the
18 inner and outer tubular members for a single pre-heat tube
19 processor;
Figure 7a is a side view of a slightly modified version
21 of the single tube processor of Figure 7, showing an alternative
22 form of support for the pre-heat tube;
23 Figures 8 - 10 are sectional end views taken along the
24 lines 8--8, 9--9, and 10--10 respectively of Figure 7;
Figure 11 is a perspective view from the first end of
26 the internals of the inner tubular member at the feed inlet of
27 the pre-heat zone, showing the junction means or transition tube,
28 the inlet ends of the pre-heat tubes, multiple corrugated pre-
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1 heat tubes, and the pre-heat discharge transition tube - only one
2 of the pre-heat tubes is shown fully corrugated; ~. .
3 Figure 12 is a perspective, partly-broken-away view of4 part of one corrugated pre-heat tube in the inner tubular member,
showing the details of the interrupted corrugations, and internal
6 elements;
7 Figure 13 is a perspective partly-broken-away view from
8 the first end of the internals of the inner tubular member at the
9 junction of the pre-heat and reaction zones, showing the
transition tube, the seal chute and the spokes;
11 Figure 14 is a perspective partly-broken-away view
12 showing the major gas seal and solids transfer chutes for the
13 processor, including the pre-heat zone to reaction zone seal,
14 the recycle sand chutes, and the reaction zone discharge seal;
lS Figure 15 is a sectional view of the pre-heat zone to
16 reaction zone spiral seal chute of Figure 14, showing the sealing
17 action of the particulate bed;
18 Figure 16 is a sectional end view of the helical seal
19 chute used at each of the reaction zone discharge and recycle
areas of the processor shown in Figure 14, illustrating the ;:
21 sealing arrangement involving the weirs and particulate beds;
22 Figure 17 is a side view of the chute of Figure 16;
23 Figure 18 is a perspective, partly-broken-away view of24 part of the chute of Figure 16; : -~
Figure 19 is a sectional side view of an alternative
26 peg-and-hole type spoked support assembly;
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1 Figure 20 is a sectional end view of the of the
2 assembly of Figure 19;
3 Figures 21 and 22 are simplified side views showing
4 the peg-and-hole assembly of Figure 19 when the processor is
cold and hot respectively,
6 Figure 23 is a perspective view of part of the peg-
7 and-hole assembly of Figure 19;
8 Figure 24 is a perspective partly-broken-away view
g of the major inner tubular member supports including the pre-
heat feed end support, the central spoked support, and the
11 reaction zone end support;
12 Figure 25 is a sectional side view of the first end
13 Qf the multiple tube processor showing the end frame, the
14 seals and the rock recycle means;
Figure 26 is a sectional side view of the first end
., -
16 of the single tube processor showing the end frame, the seals
17 and the rock recycle means;
18 Figure 27 is an expanded view of the seal shown in ;
19 Figure 25; and
Figure 28 is a sectional side view of the second
21 end of the processor showing the end frame, the seal, the :~
22 auxiliary burner means, and the combustion air inlet means.
23 DESCRIPTION OF THE PREFERRED EMBODIMENT ~:
24 The processor 1 comprises inner and outer tubular25 members 2, 3. The tubular members 2, 3 are substantially
26 concentric, co-extensive and horizontal. The outer tubular - -
27 member 3 carries external riding rings 4 which are driven,
28 for rotation. The tubular members 2, 3 are interconnected,
22
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1 so that rotation of the outer tubular member 3 induces
2 corresponding rotation of the inner tubular member 2. Stationary
3 end frames 5, 6 seal and enclose the open ends of the outer
4 tubular member 3.
From its left hand (in the drawing) or first end, the
6 inner tubular member 2 forms an internal longitudinal passageway
7 which sequentially provides a pre-heat zone A followed by a
8 reaction zone B. An annular space 7 is formed between the
9 radially spaced apart tubular members 2, 3. This annular space
7 sequentially provides from its second end a combustion zone C
11 followed by a heat transfer zone D.
12 The processor will now be described in greater detail.
13 It will be noted that some of the drawings illustrate a single
14 pre-heat tube version of the processor, which would be used in
a low throughput application such as cleaning waste dump solids.
16 In others of the drawings, there is illustrated a high throughput
17 processor having multiple pre-heat tubes. This latter version
18 would be used for oil sand processing.
19 The Pre-Heat Tubes
The inner tubular member 2 shown in Figure 2
21 comprises multiple, substantially parallel, spaced apart,
22 horizontal pre-heat tubes 8 joined at their first and second
23 ends to vertical baffles 10 and 11 respectively. Figures 2,
24 3 and 4 show five tubes, however this number is based upon
the required throughput of the processor and the minimum
26 tubular dimensions required for maintenance access. The
27 baffle 10 is secured around its periphery to a short first
23
1 3 ~ 3
1 transition tube 9. The baffle 11 is secured around its periphery
2 to a short second transition tube 12. The second end of the
3 second transition tube 12 is joined by a flange 13 to the first
4 end of a vaporization tube 14 of reduced diameter. The internal
passageways 15 of the pre-heat tubes 8 communicate through
6 apertures 16 formed in the baffle 11 with the chamber 17 of the
7 second transition tube 12. The baffle 11, transition tube 12 and
8 flange 13 together form part of a junction means joining the pre-
9 heat tubes 8 and vaporization tube 14.
The pre-heat tubes 8 are arranged in an annular
11 pattern. Their internal passageways 15 collectively form the
12 pre-heat zone A.
13 ~s shown, the side wall of each pre-heat tube 8 is
14 formed in a corrugated configuration. The corrugations 18 are
circumferential in nature. That is, the corrugations lie in
16 vertical radial planes relative to the tube axis. The
17 corrugations increase the area of the heat-conducting steel wall
18 for a given length, compared to a straight-walled tube, and
19 thereby significantly increase the thermal transmissibility of
the tubes. As the corrugations 18 are circumferential in nature,
21 many of the hot particles dropped thereon will momentarily and
22 individually contact the tube wall, so that there is particle-
23 to-steel wall heat transfer. However, due to the roundness of
24 the circumferentially corrugated wall, the initial particles are
quickly shed, so that newly dropped hot particles may repeat the
26 process. Each corrugation is preferably interrupted on its
27 circumference for insertion of an advancing or reversing plate
2~ 19. The plates 19 provide means for controlling, by advancing
24
1331~73
1 or retarding, the movement of the feedstock axially through the
2 pre-heat passageways 15.
3 Advancing plates 20 are secured to the inner surface
4 of the first transition tube 9, to feed the feedstock to be
processed into the inlet ends of the pre-heat passageways 15.
6 Conveyors 21 extend through the first end frame 5 to .
7 deliver fresh feedstock to the transition tube 9. The conveyors
8 21 and end frame 5 are more specifically described below.
~: 24a
- 1~31~73
1 At their inlet ends, the pre-heat tubes 8 are
2 supported by a thin vertical steel wall or membrane 22,
3 secured around its periphery to the outer tubular member 3.
4 This membrane 22 is adapted to provide sufficient vertical
support to constrain the pre-heat tubes ~ from bending or
6 sagging significantly. However, the membrane 22 is
7 sufficiently flexible in a transverse direction so as to flex
8 with the pre-heat tubes 8 when they elongate, expand or
9 contract due to thermal effects. The membrane 22 surface is
lo sufficiently perforated or discontinuous to allow the spent
solids from the heat transfer zone D to pass through it and
12 exit the processor 1.
13 As shown in Figure 3, the pre-heat tu~es 8 are
14 preferably tied together in a plurality of vertical planes by
links 23, for mutual support.
16 In the single pre-heat tube version shown in Figure
17 7a, the pre-heat tube 8 is supported by pivotally mounted
8 braces 22a extending from the outer tubular member 3. Four
19 braces 22a are provided in a vertical plane in spaced
relation around the pre-heat tube 8.
21 It will be noted that the membrane 22, or,
22 alternatively, the braces 22a provide means for supporting
23 the pre-heat tubes in a generally vertical direction to
24 prevent sagging thereof, said means being operative to so
support the pre-heat tube(s) while enabling them to expand
26 and contract axially and radially.
:~ ~ 3 1 ~ 7 3
1 Oversize Screen/Rock Return Tube
2 In the case where oil sand is the feedstock, it
3 contains oversize solids, such as rocks and oil sand lumps. The
4 pre-heat step is designed to mechanically ablate the lumps and
heat the feed from an inlet ambient temperature to an outlet
6 temperature (e.g. 550F) at which the contained connate water has
7 been vaporized and the oversize solids may reasonably be
8 separated form the rest of the tacky feed by screening. The
9 oversize solids should not be allowed to proceed into the
downstream zones, as they can damage the lifters and plug the
11 chute seals which are described below and which are located in
12 the downstream zones. So at the outlet of the pre-heat tubes 8
13 there is provided means for screening and separating oversize
14 solids from the feed stream. There is also provided means for
conveying the screened oversize solids to the first end of the
16 processor for removal and means for transferring the oversize
17 solids between the screening means and the conveying means.
18 More particularly, in the case of the multiple pre-
19 heat tube processor, there is provided a rock recycle or
return tube 24 which extends centrally through the ring of
21 pre-heat tubes 8. The rock return tube 24 has upstanding
22 angled plates 25 mounted on its inner surface for advancing
23 the oversize solids from its second end to its first end. At
24 its first end, the rock return tube 24 is joined to the
baffle 10 and at its second end to the baffle 11. At its second
26 end, the rock return tube 24 communicates through an aperture
27 16a with the chamber 17 of the transition tube 12. A tubular
28 cage 26, formed by the spaced-apart coils 27 of a continuous,
~J~
:..~.~'
31~73
1 circularly formed bar, is positioned in the chamber 17
2 immediately downstream of the pre-heat tubes discharge
3 apertures 16. A rock chute 28 of spaced bars leads from the
4 cage 26 to the inlet aperture 16a of the rock return tube 24.
Thus, the pre-heated feed exiting the pre-heat
6 tubes 8 drops onto the coils 27 of the cage 26. The oily
7 sand particles drop through the openings in the screen or
8 cage 26 while the oversize solids are transferred by chute 28
g into the inlet end of the rock return tube 24, for conveyance
lo to the first end of the processor 1. Here the greatest part
11 of the oversize solids drops into a chute 29 for removal from
12 the processor 1.
13 Rock RecYcle
14 As previously mentioned, it has been found in the
case of oil sand feed that a tacky layer of tarry sand
16 gradually builds up on the inner surface of the wall of each
17 pre-heat tube 8 at its second end. This layer impedes
18 transfer of heat from the tube wall to the oil sand bed. As
19 mentioned, it has been found that impacting the layer with
rocks will cause chunks of the deposit to shear off. This
21 finding has led to our concept of using rocks to scour the
22 layer from the second ends of the pre-heat tubes 8.
23 To this end, we recycle some of the rocks,
24 returning through the rock return tube 24, back into the
inlet ends of the pre-heat tubes 8. We thereby maintain a
26 greater concentration of rocks in the pre-heat zone A than
27 would normally be contributed by the feed. This concentrated
28 stream of rocks is used to scour the inner surface of the
~3~
1 pre-heat tubes 8. The quantity of rocks recycled would be
2 determined during operation.
3 To achieve such recycling, the pre-heat inlet end
of the rock return tube 24 is provided with slots 30 which
function to allow some of the returning smaller rocks to drop
6 back into the pre-heat feed stream, while the tube 24
7 functions to eject the remainder out of the processors
8 through a center line chute 29.
9 The profile of the rock recycle tube corrugations
lo 18 would be appropriately matched to the feedstock. A
11 feedstock less prone to depositing the tarry sand would not
12 need large rocks recycled and the profile could be more
13 pointed, like a sawtooth. In situations where it is expected
14 to process very tacky feedstock, a corrugation profile more
like that of a square thread, with a wide flatter profile,
16 could be used to provide access to all surfaces by the
17 recycling rock charge.
18 Advancin~ Means
19 Material moves in a rotating kiln by natural and
induced means. Hydraulic action is a powerful impetus to
21 solids movement. As the processor rotates, the bed of solids
22 rises to its dynamic angle of repose and then begins a
23 slumping and rolling action. The material will readily roll
24 to an area of no solids, much like fluids flow downslope.
This results in a natural progression of solids away from the
26 source of feed. In the situation where this action is more
27 than required and the solids are moving too quickly, then
28 artificial retarding mechanisms are used. Where the solid
28
1 material is moving too slowly and the material is
2 accumulating in the zones, then advancing means may be
3 utilized.
4 In the corrugated pre-heat tubes 8, the
corrugations 18 may be interrupted on their circumference
6 with upstanding, angled plates 19, installed to advance the
7 material to the next corrugation.
8 If the rate of advance through the pre-heat zone A
9 is excessive, then oppositely directed back-up plates 19 may
lo be provided to spill some of the feed backwards and retard
11 its advance.
12 Angled plates are similarly provided on the inside
13 surfaces of the remainder of the inner and outer tubular
14 members, as required, to advance the feed stream
15 therethrough.
16 Such plates are provided to advance the feed at a
17 controlled rate through the various zones.
18 In the case of oil sand feed, we seek to heat the
19 incoming feed from ambient temperature (32 - 70F) to about
550F. As previously stated, this is done to vaporize
21 contained water, to ablate lumps, and to render the oil sand
22 amenable to screening. The temperature change is achieved
23 through the mechanism of cascading hot sand, issuing from the
24 combustion zone C at about 1300F, onto the outer surfaces of
25 the pre-heat tubes 8. As a result of heat transfer to the
26 tubes 8, the now-cooled sand issuing from the first end of
27 the heat transfer zone D is at a temperature of about 600F.
28 It has been determined that the coefficient of heat
29 transfer U through the steel wall of a pre-heat tube
~9
7 ~ ~
typically is about lOO ~tu/hour/sqft/F, while that through
2 the sand bed in the pre-heat tube is only about 10 such
3 units.
4 So the difficulty is not in getting heat to the
inner surface of the tube wall - it is in getting heat
6 distributed through the sand bed.
7 In order to improve heating of the sand bed, we
8 have centered on increasing two factors, namely:
9 - the surface area of the steel wall forming a
pre-heat zone A of given length; and
11 - the extent of the sand bed width within each
12 pre-heat tube.
13 Nore particularly, we use one or more corrugated
lg pre-heat tubes and we prefer to maintain the width of the
15 sand bed as wide as is practical, whereby the extent of the
16 steel wall in direct contact with the sand bed is maximized.
17 Preferably, we utilize a bed angle of about 110 degrees (the
18 ~Ibed angle~ is the imaginary angle established by drawing
19 lines from the edges of the bed to the central axis of the
20 tubeJ. The bed depth and width can be controlled by
21 utilization of the advance and back-up plates l9.
22 The spokes
23 A plurality of spokes 61 are joined to the
24 transition tube 12 and extend outwardly and radially from it.
25 These spokes 61 rigidly connect the inner tubular member 2 to
26 the outer tubular member 3 to prevent rotational shifting of
27 the latter relative to the former and to transfer load
28 between the members 2, 3. The spokes 61 and outer tubular
~:
3 1~ ~! 3
1 member 3, in the area of the spokes, are formed of complementary
2 materials so that their thermal expansion rate is about equal.
3 In a broader statement of this feature, the rates of
4 expansion of the materials are complementary so that the amount
of radial expansion is about the same, notwithstanding the
6 different temperatures of the inner and outer tubular members.
7 Thus the inner and outer tubular members 2, 3 are
8 pinned together at this central point along the length of the ~ ~-
9 processor, so that one may not shift axially relative to the
other. The inner tubular member 2 is suspended concentrically
11 within the outer tubular member 3. And a drive connection is
12 supplled between the outer and inner tubular members 3, 2 so that
13 they rotate as one. Yet these ends are achieved while permitting
14 of limited radial movement of the spokes 61 due to thermal
expansion or contraction of the inner tubular member 2.
16 The spokes 61 elongate or contract as the outer tubular
17 member 3 also expands and contracts radially at a complementary
18 rate, due to an appropriate selection and use of material of
19 construction.
In summary then, the spokes/materials of construction
21 arrangement supplies drive connection and centralization while
22 accommodating the differing thermal expansion and contraction
23 rates of the inner and outer tubular members. ;~
24 Figure 19 illustrates an alternative spoked support
scheme. Instead of a rigid connection between the spoke and
26 the outer tubular member support, a spoke 65 and matching hole
27 66 system iB used. Inwardly projecting spokes 6S, attached
28 to the outer tubular member 3, fit in to matching holes
29 66 formed in a flange 67 attached to the inner tubular
member 2. The dimensions of holes 66 are sufficiently ~
31 ~ --
- 1331~7~
1 precise to prevent axial or torsional movements of the inner
2 tubular member 2, yet will permit of radial expansion.
3 In either of these embodiments, the differential
4 radial expansions for inner and outer tubular members are
enabled without deformation or forced displacement of said
6 members.
7 Inlet End Frame -~
8 The stationary end frame 5 se2~es the purpose of
9 sealing the annular space 7 and the pre-heat passageways 15
against the oxygenated atmosphere while allowing the
11 processor 1 to rotate.
12 The stationary end frame 5 comprises a first
13 housing 50 having a ring seal 51 which seals against the
14 outer surface of the rotating first end of the outer tubular
mem~er 3. The first housing has a second ring seal 52 which
16 seals the annular space 7 against the outer surface of the
17 rotating inner member 2. Together, ring seals 51 and 52
13 close the open first end of the outer tubu7ar member 3.
19 A conduit 53 connects the first housing 50 to a
suction fan 54, thereby providing means for drawing flue
21 gases from the annular space 7.
22 A chute 55 connects the first housing 50 to a
23 conveyor 56, thereby providing means for removing ~rocessed
24 solids from the annular space 7.
A second housing 57 provides a stationary mounting
26 frame to which the feed conveying means 21 may be fastened.
27 The second housing 57 has a ring seal 58 which seals against
28 the outer surface of the rotating inner tubular member 2,
'~ `' ;F`
1~31 ~73
1 thus enclosing its open first end. The feed conveying means
2 21 is connected with the second housing 57, whereby it may
3 introduce feed into the pre-heat tubes 8.
4 A conduit 59 connects the second housing 57 to a
suction fan 60, thereby providing means for drawing released
6 vapors from the pre-heat zone passageways 15.
7 Seal at Second End of Pre-~eat Zone
8 A baffle 70 extends vertically across the second
9 end of the transition tube 12 and is an extension of the
lo flange 13.
11 Helical tubular chutes 71 extend through openings
12 formed in the peripheral portion of the baffle 70, as shown
13 in Figure 13. The inlet 72 of each chute 71 communicates
14 with the chamber 17 of the transition tube 12. The outlet 73
of each chute 71 communicates with the reaction sone B. In
16 operation, rotation of the chute 71 along a vertical plane
17 will cause a unit of sand to enter the chute inlet 72 when it
13 passes through the sand bed in the transition tube chamber
19 17. This unit of sand will pass through the baffle 70 via
the chute 71 and will drain out the outlet 73 into the
21 reaction zone B later in the rotational movement.
22 The opening 74 between the transition tube chamber
23 17 and the reaction zone B, central to the helical seal
24 chutes 71, is an access port only and must be fitted with a
cover baffle plate 75 for operation.
26 The baffle 70 and chutes 71 thus function to enable
27 solids to move between the transition tube chamber 17 and the
28 reaction zone B. But as explained below, they also function
;~ 33
~31~73
1 to prevent the gases from moving therebetween in significant
2 amount. More particularly, if the chute 71 spirals through 360
3 degrees, there is always a sealing plug 76 of sand present in the
4 chute along part of its length. This plug 76 and the solid
baffle 70 combine to minimize gas movement, although there is
6 always some small amount of gas that gets pumped through by the
7 sand plug.
8 The atmosphere in the pre-heat zone A is almost
9 entirely steam to the exclusion of most oxygen. There is no
æerious harm done if some of the steam reaches the reaction zone
11 B. So the seal system between the two zones A and B can permit
12 of some gas leakage.
13 The baffles 70 and 11 combine with the transition tube
14 12 to provide junction means between the pre-heat and
vaporization tubes.
16 Sealing the Vaporization Tube
17 It is desirable to provide as effective a seal against
18 gas movement between the reaction zone B and the annular space
19 7 as one aan manage. If hydrocarbons move from the reaction zone
B into the combustion zone C, they of course burn and the product
21 yield from the processor 1 is reduced. If flue gases move from
22 the annular space 7 into the reaction zone B, they contaminate
23 the product stream and one must provide downstream means for
24 cleaning the product.
In this connect~on, it is necessary to provide, at the
26 interface between the second end of the reaction zone B and the
27 combustion zone C and at the point at which hot solids are
28 recycled from the annulus 7 into the first end of the reaction
34
--- 133~73
1 zone C, means for conveying particulate solids through a solid
2 wall (~uch as a baffle or tube wall) while still maintaining a
3 seal against gas migration. We use helical chutes 82, 81 for
4 this purpose.
The combination of a solid wall and a helical chute
6 extending therethrough is however subject to the disadvantage
7 that a slug of gas will be pumped through the chute ahead of each
8 discrete chute-filling charge of sand moving through it.
9 This problem has been significantly ameliorated by
providing transverse weirs 80 at spaced intervals along the
11 length of the internal passageways 131, 134 of each of the
12 recycle chutes 81 and the end chutes 82 respectively. The sand
13 forms plugs 83 at the weirs 80, which plugs substantially prevent
14 gas passage. The small amounts of remaining entrapped gases 84
can in part work their way back through the slot 80a left between
16 the lip of each weir 80 and the chute wall as the plug drains to
17 the following section between subsequent weirs. -~-
18 Thus, at the second end of the vaporization tube 14
19 there is provided a transverse baffle 85 having twin helical end
chutes 82 equipped with internal weire 80. Each chute 82 extends
21 through a minimum of 360 degrees of rotation, typically 540
22 degrees or one and one half revolutions. The helical end chutes
23 82 communicate with apertures 133 in the baffle 85 and are ;~
24 operative to transfer coked solids from the reaction zone B
through the baffle 85, while cooperating with contained sand
26 plugs 83 to substantially prevent movement of gas therethrough.
27 Each of the helical end chutes 82 progresses through 540 degrees
28 of rotation, while occupying the minimum space by following twin,
1331573
-
1 parallel, helical paths, finally discharging into the combustion
2 zone C through apertures 135.
3 A tube 86 is joined to the downstream side of the
4 baffle 85. The tube 86 is open at its downstream end and
contains a helical screw 87. This tube 86 is provided simply as
6 a spacer, to extend the delivery of the coked solids to the
7 second end of the combustion zone C. The coked solids exiting
8 the end chutes 82 are discharged into this tube 86 and are fed
9 by the screw 87 through the tube outlet 88 into the second end
of the combustion zone C.
11 Twin recycle chutes 81 are mounted around the first
12 end of the vaporization tube 14. These rotating helical recycle
13 chutes 81 extend through apertures 130 in the wall of the
14 vaporization tube 14 and function to transfer hot solids, issuing
from the combustion zone C, into the first end of the reaction
16 zone B. The recycle chutes 81 also have internal weirs 80 to
17 improve sealing against flue gas migration with sand plugs. The
18 discharge aperture 132 of each recycle chute 81 is fitted with
19 a variable orifice member 89 adjustable external to the outer
tubular member 3.
21 Comparative runs were carried out in the pilot
22 processor wherein, on the one hand, the chutes 81, 82 were
23 not equipped with weirs 80, and on the other hand, they were.
:.r~
24 These runs indicated that the oil product from the reaction
zone B was improved by about 2 degrees API in quality when
26 the weirs were used. Also, it was found that the hydrocarbon
~- 133~L573
1 content in the gas stream drawn from the reaction zone B
2 increased from about 35% by volume to about 55% when the
3 weirs were in place.
4 Sg~port For The VaPorization Tube
In the case of the single pre-heat tube processor,
6 a plurality of rigid radially attached rod assemblies 90
7 interconnect the conduit 95 around its periphery with the
8 outer tubular member 3. Dependent upon the process
9 requirements, tube 86 may be too short or non-existent, thus
lo requiring rods assemblies 90 to be attached to the conduit
95. These rod assemblies 90 function to support the second
end of the inner tubular member 2, while permitting of
13 differing radial and axial expansion and contraction of the
tubular members 2, 3.
In the case of the multiple pre-heat tube
16 processor, the rod assemblies 90 are shown connected
17 tangentially and pivotally to a collar 91, which is mounted
18 on the vaporisation tube 14/86, whereby elongation of the rod
19 as~emblies 90 would result in rotation of the collar while
preserving its central location. Elongation of the second
21 end of the inner member 2 and the rotation of the collar 91
22 are allowed for by an adequate clearance gap between the
23 collar 91 and the tube 86.
24 The Reaction Zone
In the reaction zone B, pre-heated solids having a
26 temperature of about 550F are mixed with recycled hot solids
27 having a temperature of about 1300F. The recycle rate of
~33~ ~7~
hot solids is controlled to ensure a mixture temperature of
2 about 975F. At this temperature, the lighter hydrocarbons
3 are vaporized and are withdrawn through the conduit 95. Coke
4 is formed on the sand, typically being about 3% by weight of
the composite particle.
6 The rate of recycle may be controlled by the
7 adjustment of the recycle chute discharge orifice member 89.
8 This adjustment is made by a mechanism mounted external to
9 the outer tubular member 3. It would suffice in most
lo instances to make a single adjustment for a particular
11 feedstock and the resulting process requirements. Recycle
12 rates of l to 3 times the feed rate are typical. This means
13 that material is being transported through the reaction zone
14 B at 2 to 4 times the processor feed rate.
The Combustion Zone
16 The outer tubular member 3 has a layer 100 of
17 refractory on its inner surface. Some of the working
18 components positioned in the annular space 7 are secured to
19 the wall of the outer tubular member 3, but they project and
function internal to the refractory layer lO0.
21 A conventional burner lOl extends into the second
22 end of the combustion zone C, for the supply of supplemental
23 heat.
24 Combustion air is supplied to the con~ustion zone
C, in about the stoichiometric amount or a slight excess
26 oxygen condition, via a tube 102 extending into the second
27 end of the combustion zone, for combustion of the coke.
38
~331573
1 Llfters 104 and 104a are attached to the wall of the
2 outer tubular member 3 and the vaporization tube 14 at spaced
3 intervals throughout the length of the combustion zone C.
4 The coke particles only burn satisfactorily when they
are repeatedly lifted and dropped in the form of a curtain
6 through the pre-heated air flow. So the lifting capacity of the
7 lifters 104 has to be sufficient to ensure that the process
8 objectives for heat supply are achieved.
9 The heat supplied by the burner 101 is utilized to
supplement the heat derived from combustion, as required to bring
11 the solids to the desired 1300F in the case of oil sand.
12 The solids are advanced through the annular space 7 by
13 a combination of the gas carrying capabilities of the exhaust
14 stream and angled plates (not shown) affixed to the inside
surface of the outer tubular member 3.
16 As has previously been mentioned, part of the burned
17 hot solids are picked up by the recycle chute 81 and returned to
18 reaction zone B. To ensure that thi capability is maintained
19 during start-up and operation of the processor 1, we have
provided a structure associated with the spokes 61 which prevents
21 the hot solids from moving downstream of the recycle chute 81
22 until it is being well supplied with solids to be recycled.
23 More particularly, the spokes 61 are attached to an
24 air plenum 107 which is secured to the transition tube 12.
Between the spokes 61, web segments 109 are also attached
26 to the air plenum 107, the outer edges of the web segments 109
27 are spaced from the inside surface of the outer tubular
c-.~
133~73
member 3, to thus form an annular gap lO9a. Some of the web
2 segments 109 have an aperture 110 close to the air plenum
3 107. The web segments lO9 are adapted to reverse the sand
4 advancing through the annular space 7, yet the gaps lO9a
enable free passage of the exhaust gases flowing through the
6 annular space 7. Thus the sand builds up when it first
7 begins to move through the annular space 7. The sand begins
8 to spill through the apertures 110 when it reaches them - but
9 by that time the recycle chutes 81 are able to scoop deeply
lo into the built-up bank of sand. The apertures 110 lead the
11 overspill solids to the heat transfer sone B.
12 The Combustion Zone End Frame
13 The combustion zone stationary end frame 6 at the
14 second end of the outer tubular member serves the purpose of
sealing the annular space 7 and the combustion zone C from
16 the external oxygenated atmosphere, while allowing the
17 processor 1 to rotate. The end frame 6 has a ring seal 116
18 which seals against the outer surface of the rotating second
19 end of the outer tubular member 3. The auxiliary burner 101
is installed in the end frame 6 and projects into the
21 combustion zone annulus C. The tube 102 projects through the
22 end frame 6, for supplyihg combustion air from a blower fan
23 1 03.
24 The Heat Transfer Zone
The outer tubular member 3 has lifters 120 attached
26 to it in the heat transfer zone D, for lifting the hot solids
27 and dropping them onto the pre-heat tubes 8.
1~31573
1 Since it is desirable that the hot solids be repeatedly
2 brought into contact with the pre-heat tubes, the lifter capacity
3 may be as much as the space available allows, yet maintaining
4 adequate access for maintenance. Similar rules apply here as for
the determination of combustion zone lifter size and number. The
6 free cross section area of the zone preferably should not be less
7 than that of the combustion zone cross sectional area as this
8 affects the gas velocities. The zone length and volume is
9 dependent upon the pre-heat zone length which has been previously
determined.
11 The Ridina Ring Assemblies
12 A plurality of riding ring assemblies 150 are provided
13 at spaced points along the length of the outer tubular member 3.
14 The assemblies 150 function to support and rotate the processor.
More particularly, each riding ring assembly 150 comprises an
16 inner ring 151, affixed to the outer tubular member 3, and an
17 outwardly spaced outer ring 152 attached to the inner ring by a
18 plurality of webs 153. The webs 153 function as heat dissipating
19 fins so that the outer ring 152 is considerably cooler than the
inner ring 151. Each ring assembly 150 is rotatably supported
21 by rubber tires 154 mounted on support standards 155. The ring
22 assemblies 150 are rotated by driven tires 156.
23 This arrangement has the following advantages:
24 - the double ring structure with intermediate heat
exchange webs 153 is designed to ensure that the
26 outer rings 152 are sufficiently cool so as not
27 to damage the rubber tires 154; and
41
. .,
-~ 1331~73
- the use of the r~bber tires 154, preferably
2 inflated, permits of reasonable variation in
3 the manufacturing tolerances for the rings.
4 Example I ;
The performance of the processor is illustrated by
6 results achieved using the pilot plant unit. This unit
7 processed a variety of feedstocks, including oil sand
8 obtained from the Athabasca region of Alberta, Canada. The ~r~f~
g average continuous feed rate achieved was about 4.5 tons per
o hour at a ro~ational speed of 4.5 to 5 rpm. -
The unit was nearly 27 feet in length, with an
12 outer member diameter of just over 9 feet. Due to its small
13 size, experimental nature, and a desire for economical
14 modifications, a single pre-heat tube version was
15 implemented. The inner tubular member formed a corrugated,
16 11.5 foot long, 5.5 foot outer diameter pre-heat sone and a
17 7.9 foot long, 3.9 foot inner diameter reaction zone. The
18 second end of the pre-heat tube was connected to a 2 foot
long transition tube which contained the pre-heat-to-reaction
20 zone seal. The pre-heat zone had a surface area of 340
21 square feet, which is a 45% increase over a plain non-
22 corrugated shell. The depth of the bed in the pre-heat zone
23 was about 6 inches, resulting in a bed angle of about 110
24 degrees. The reaction zone depth was operated to achieve a
25 zone fill of about 20% of the total volume. With a recycling
26 sand ratio of about 1 to 1.5, this resulted in reaction zone
27 material retention times of about 4 minutes. The combustion ~-
28 zone comprised a volume defined by a length of 9.8 feet and a - ~-
-:
42 `~
~ 333L~73
inner process diameter within the insulation of 7.8 feet.
2 Sixteen equally spaced combustion zone lifters were provided,
3 mounted internally to the outer tubular member. The lifters
4 were of an "L" shape, projecting ~0 inches radially inward
with a 6 inch right angle tip. rhe heat transfer zone was
6 13.5 feet long with an inner process diameter of 7.8 feet.
7 This zone contained 16 lifter sets with a 4 inch by 4 inch
8 ~L" shape configuration. Feed was delivered to the pre-
9 heating zone via a sealed belt conveyor projecting through
lo the end frame at the first end. Flue gases were extracted
11 through a hood and spent hot solids were discharged through a
12 chute in this end frame. Pre-heat zone vapors were drawn
13 from the pre-heat zone through a conduit projecting through
14 the end frame. Twin fuel oil auxiliary burners and twin
combustion air conduits projected through the end frame at
16 the second end. ~he processor rotated on two steel riding
17 rings, powered by a variable speed, hydraulic chain drive.
18 Illustration of the pilot plant performance may be
19 characterized by a selected group of runs totalling nearly
175 hours of operation at an average 4.4 tons/hour. This
21 group of runs was specifically performed on Athabasca oil
22 sand run-of-the-mine material, where no selection of the
23 feedstock quality was made. These runs were selected from a
24 much larger body of information with many different feed
25 stock and operating objectives. The hydrocarbon products
26 were processed only once, that is, no recycling of the
27 heavier products to the reaction zone were performed.
28 This material had a average bitumen content of 10.0
29 weight %, 5.4% water, the remaining 84.6% being quartz sand. ;
1331~73
The bitumen was converted to a number of products
2 when processed through the pilot unit. The bitumen products
3 were converted to 77.0% butane (C4H10) and heavier
4 hydrocarbons, 8.1% propane (C3H8) and lighter hydrocarbons
(including hydrogen), 4.4% coke and 10.5% carbon present in
6 the gas streams as carbon monoxide (COJ and carbon dioxide
7 (CO2J. This was achieved with an average reaction zone
8 temperature of 976 degrees F and a combustion zone
g temperature of 1216F.
The product oil, which is considered to be the
11 butane and heavier hydrocarbons, had an overall product
12 gravity of 23 degrees API, which is equivalent to a specific
13 gravity of 0.916. The average viscosity was 8.5 centipoise
14 at 30 degrees C. Athabasca bitumen gravity averages about
8.8 degrees API or a specific gravity of 1.009, being heavier
16 than water.
17 The processor consumed 3.4 million 8tu/hour of
18 which 1.4 million or over 40% was supplied by the combustion
19 of coke, the rest being supplied by auxiliary fuel. An
20 average 70% of the available coke was consumed. Over 0.7
21 million Btu/hour were lost through the outer tubular member.
'' :',
22 ExamPle II
23 A typical application of the single pre-heat tube
2~ processors is dump site clean-up or waste processing, in
25 which a hydrocarbon contaminated soil must be processed to
6 recover the hydrocarbons and discharge an environmentally
27 inert soil. These sites are often of a low overall tonnage
28 and are widely placed geographically. This suggests using a
133~L573 : ~
1 processor of a low capacity and one small enough to be
2 transported from site to site.
3 One example of a contaminated soil application is that ~ .
4 of a soil impregnated with polychlorinated biphenyl or PCB's as ~ :
known in the current terminology of the media.
6 The pilot unit was tested on about 23 on artificially
7 prepared soils, contaminated by mixing with nearly 600 pounds of
8 PCB's.
9 Of 100% of the PCB oil fed to the processor, only 0.04%
was detected as discharges to the environment, 93% was recovered
11 as liquid oils, and the remaining 7% was in large part converted
12 to coke or combustion byproducts CO or CO~.
~ .
