Note: Descriptions are shown in the official language in which they were submitted.
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METHOD AND SYSTEM FOR AN INTEGRATED
GASIFIER AND SYNGAS COOLER
BACKGROUND OF THE INVENTION
[0001] This invention relates generally to partial oxidation gasifiers
and gas coolers and, more particularly, to reducing wear on internal
components of an
integral gasifier and gas cooler combination.
[0002] At least some known gasification vessels include areas that
are prone to elevated amounts of wear due to the flow characteristics of the
raw
effluent gas passing these areas and the adverse conditions of temperature,
pressure,
and chemistry these areas are exposed to. For example, but not limited to a
gasifier
bottom transition, a gasifier throat, and a syngas cooler throat are high wear
zones for
refractory linings because the narrow flow path increases the mass flow rates
of
molten slag along the lining wall. Although some attempts to mitigate the
effects of
the adverse conditions affecting the refractory have been tried, the attempts
have
tended to create other problems. For example, one known attempt to actively
cool the
affected areas resulted in a vertical expansion gap in the throat lining
between the
actively cooled and passively cooled section. The gap provides a potential
leak path
of syngas into the annular space behind the vertical tube cage. Another
attempt used a
vertical steel cylindrical gas barrier with a flanged bottom behind the throat
refractory
to prevent gas from escaping into the stagnant annular zone. However, the
steel
cylinder is not cooled, therefore leading to either overheating of metal or
shorter
refractory life. Further, in the known gasification vessels the inside
diameter of the
flow path in the throat is constrained by the inside diameter of the flanges
of both the
gasifier and syngas cooler. The flow path diameter cannot be changed without
significantly altering the steel vessels.
[0003] Providing a gasifier having an integrated cooler formed
integrally with the gasifier eliminates a forged flange on the gasifier vessel
and a
forged flange on the cooler vessel. Elimination of these two large flanges in
the
integrated gasifier/cooler significantly reduces the cost of the
gasifier/cooler over the
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separate gasifier and cooler configuration. Elimination of the flange-to-
flange joint
between the gasifier and the syngas cooler permits the combined axial length
of the
two vessels to be significantly reduced. The reduced length reduces the
thermal
growth of the combined vessel, thus reducing the mismatch with the
interconnecting
piping (injectors, steam drum, steam piping, instrumentation) that are fixed
to the
support structure which is at ambient temperature with minimal thermal growth.
Elimination of the flange-to-flange joint also improves the integrity of the
vessel and
facilitates eliminating components (flanges, supports, etc.) and reducing
erection
operations.
BRIEF DESCRIPTION OF THE INVENTION
[0004] In one embodiment, an integrated gasifier and syngas cooler
includes a gasifier including a reaction chamber, a syngas cooler integrally
formed
with the gasifier and including at least one heat exchanger element, and a
transition
portion integrally formed with the reaction chamber and the syngas cooler and
extending therebetween, the transition portion further includes a throat
extending
between the reaction chamber and the syngas cooler and the transition portion
further
includes a heat exchanger circumscribing the throat.
[0005] In another embodiment, an integrated gasifier and syngas
cooler system includes a first pressure vessel portion surrounding a gasifier
reaction
chamber wherein the first portion extends from a vessel head to a lower end.
The
system also includes a second pressure vessel portion surrounding a gas cooler
configured to cool a hot raw effluent gas stream from the gasifier reaction
chamber.
The second portion extends from an upper end vertically downward towards a
solids
removal end. The system further includes a transition portion extending
between the
lower end and the upper end wherein each of the first portion, the second
portion, and
the transition portion are in substantial vertical coaxial alignment along a
central
longitudinal axis of each portion. The system includes a throat coaxially
aligned with
each portion and extending therebetween for the free passage of the hot raw
effluent
gas stream from the gasifier reaction chamber to the gas cooler, the throat is
lined
about a radially inner surface with a refractory material. The system further
includes
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a concentric coaxial vertical tube cage surrounding the throat along at least
a portion
of a length of the throat, and a plurality of annular anchoring rings coupled
to at least
one of the first portion and the tube cage, the anchoring rings extending
radially
inward and are configured to support the throat refractory material.
[0006] In yet another embodiment, a method of assembling an
integrated gasifier and syngas cooler includes providing a syngas cooler
vessel that is
integrally formed with a gasification vessel wherein the gasification vessel
includes a
reaction chamber and the syngas cooler vessel includes a heat exchanger. The
method
also includes coupling the reaction chamber and the syngas cooler vessel in
flow
communication using a throat lined with a refractory material wherein the
refractory
material is supported in the throat using one or more annular anchoring rings.
The
method further includes positioning a cooling tube cage surrounding the throat
such
that during operation the refractory material is cooled using the cooling tube
cage.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] Figures 1-5 show exemplary embodiments of the method and
system described herein.
[0008] Figure 1 is a schematic diagram of a vertical elongated high
temperature steel pressure vessel in accordance with an exemplary embodiment
of the
present invention;
[0009] Figure 2 is a schematic diagram of a throat area of a vessel in
accordance with an embodiment of the present invention;
[0010] Figure 3 is a schematic diagram of a throat area of a vessel in
accordance with another embodiment of the present invention;
[0011] Figure 4 is a schematic diagram of a throat area of a vessel in
accordance with still another embodiment of the present invention; and
[0012] Figure 5 is a schematic diagram of a throat area of a vessel in
accordance with yet another embodiment of the present invention.
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DETAILED DESCRIPTION OF THE INVENTION
[0013] It should be noted that although embodiments of the present
invention are described with respect to an integral gasifier and syngas cooler
combination, one of ordinary skill in the art should understand that the
embodiments
of the present invention are not limited to being used only with integral
gasifier and
syngas cooler combinations. Rather, embodiments of the present invention may
be
used with any integrated vessels.
[0014] The following detailed description illustrates embodiments of
the invention by way of example and not by way of limitation. It is
contemplated that
the invention has general application to cooling internal components of
vessels to
extend their life in industrial, commercial, and residential applications.
[0015] As used herein, an element or step recited in the singular and
proceeded with the word "a" or "an" should be understood as not excluding
plural
elements or steps, unless such exclusion is explicitly recited. Furthermore,
references
to "one embodiment" of the present invention are not intended to be
interpreted as
excluding the existence of additional embodiments that also incorporate the
recited
features.
[0016] Figure 1 is a schematic diagram of a vertical elongated high
temperature steel pressure vessel 100 in accordance with an exemplary
embodiment
of the present invention. In the exemplary embodiment, vessel 100 includes a
single
unitarily formed shell 102. Shell 102 includes an upper shell 104 surrounding
a
gasification reaction zone 106 of a partial oxidation gasifier which is used
for the
production of synthesis gas, reducing gas, or fuel gas, a lower shell 108
surrounding a
gas cooler portion 110, and a transition portion 112 surrounding a throat 114
extending between reaction zone 106 and gas cooler portion 110. Upper shell
104
includes a bottom exit passage 116 along a central longitudinal axis 118 of
vessel 100
and an upper head 120 that includes a coaxial inlet opening 122 for the
insertion of a
downwardly discharging gasification burner (not shown). Throat 114 includes a
converging entrance Upper shell 104 includes a thermal refractory lining 124
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surrounding gasification reaction zone 106 and extending radially between
upper shell
104 and reaction zone 106. Throat 114 is a vertical cylindrical annular shaped
elongated conduit lined with a thermal refractory brick lining 126. Throat 114
is
generally coaxial with upper shell 104 and lower shell 108 and extends
therebetween
for the free passage of the hot raw effluent gas stream flowing downwardly
from
reaction zone 106 to gas cooler 110 in lower shell 108. As referred to herein,
an
"axial" direction is a direction that is substantially parallel to axis 118,
"upper" and an
"upward" direction is a direction that is generally towards inlet opening 122,
and
"lower" and a "downward" direction is a direction that is generally away from
inlet
opening 122.
[0017] Figure 2 is a schematic diagram of a throat area of a vessel
200 in accordance with an embodiment of the present invention. In the
exemplary
embodiment, upper shell 104 includes a first layer 202 of refractory brick
stacked
circumferentially about an outer periphery of reaction zone 106, and a second
layer
204 of refractory brick stacked radially outward from first layer 202. First
layer 202
is supported at a lower end 206 by a first annular anchoring ring 208 that
extends
radially inward from upper shell 104. A second annular anchoring ring 210
provides
support to second layer 204 and also extends radially inward from upper shell
104 at a
position spaced axially from first annular anchoring ring 208. First layer 202
and
second layer 204 are stacked such that seams between adjacent bricks in first
layer
202 do not align with seams between adjacent bricks in second layer 204. Such
misalignment presents a labyrinthine path between reaction zone 106 and upper
shell
104 that facilitates preventing hot raw effluent gas from reaction zone 106
from
leaking from reaction zone 106 and entering a space 212 adjacent upper shell
104,
where corrosive constituents of the hot raw effluent gas can attack upper
shell 104.
[0018] Transition portion 112 includes a tube cage comprising a
membrane wall of cooling tubes 214 extending circumferentially around throat
114.
A stagnant annular space 216 extending radially outward from cooling tubes 214
to
transition portion 112 provides an area for risers and downcomers (both not
shown)
that supply water and remove water and steam from cooler 110. Throat 114 is
lined
with a throat layer 218 of refractory bricks that extends from a third annular
anchoring
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ring 220 coupled to cooling tubes 214 upward to bottom exit passage 116.
Anchoring
ring 220 extends radially inward from cooling tubes 214 and supports throat
layer
218. Between throat layer 218 and first layer 202, sloped layer 222 of
refractory brick
is supported by a fourth annular anchoring ring 224 coupled to and extending
radially
inward from cooling tubes 214. Because first layer 202 is supported by first
annular
anchoring ring 208, which is coupled to upper shell 104 and sloped layer 222
is
supported by third anchoring ring 220, which is coupled to cooling tubes 214
during
certain operations of vessel 200, first layer 202 and sloped layer 222 may
move
axially relative to each other due to differential expansion between upper
shell 104
and cooling tubes 214. Accordingly, an abutting joint between first layer 202
and
sloped layer 222 is vertically aligned such that first layer 202 and sloped
layer 222
may slide past each other relatively freely during periods of differential
expansion and
contraction. Such slidable engagement facilitates avoiding compression of
first layer
202 and sloped layer 222 which may cause cracking of first layer 202 and/or
sloped
layer 222 and to avoid forming gaps between first layer 202 and sloped layer
222.
[0019] Stagnant annular space 216 is positioned outside refractory
lined transition throat cylinder 114 and inside transition portion 112 and has
an
increased volume compared to a flanged joint configuration. This increased
volume
permits an embodiment of the present invention with boiler feed water piping
and
support structure inside annular space 216. The embodiment reduces thermal
stress of
pipe components and joints with the vessel due to thermal expansion mismatch
by
permitting more flexible pipe routing. The embodiment also provides sufficient
space
to route a top header (not shown) into annular space 216 above a horizontal
tube wall
(not shown). The embodiment adds additional tube panel surface area inside the
hot
gas path under the horizontal tube wall that increases the heat recovery
performance
or reduces the total axial length of the syngas cooler assembly. Additionally,
the
embodiment simplifies the support structure for the vertical tube panels by
permitting
direct connection to the vessel wall, which frees up more annular space for
better
access and design flexibility.
[0020] Figure 3 is a schematic diagram of a throat area of a vessel
300 in accordance with another embodiment of the present invention. Vessel 300
is
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substantially similar to vessel 200 (shown in Figure 2) and components of
vessel 300
that are identical to components of vessel 200 are identified in Figure 3
using the
same reference numerals used in Figure 2. In the exemplary embodiment, cooling
tubes 214 do not extend into the area of the bottom exit passage 116. As such,
stagnant annular space 216 is smaller than that shown in Figure 2. A support
skirt
301 extends obliquely inward from upper shell 104.
[0021] A first layer 302 of refractory brick is stacked
circumferentially about an outer periphery of reaction zone 106, and a second
layer
304 of refractory brick stacked radially outward from first layer 302. First
layer 302
is supported at a lower end 306 by a first annular anchoring ring 308 that
extends
radially inward from support skirt 301. A second annular anchoring ring 310
provides
support to second layer 304 and also extends radially inward from support
skirt 301 at
a position spaced axially from first annular anchoring ring 308. First layer
302 and
second layer 304 are stacked such that seams between adjacent bricks in first
layer
302 do not align with seams between adjacent bricks in second layer 304. Such
misalignment presents a labyrinthine path between reaction zone 106 and upper
shell
104 that facilitates preventing hot raw effluent gas from reaction zone 106
from
leaking from reaction zone 106 and entering space 212, where corrosive
constituents
of the hot raw effluent gas can attack upper shell 104.
[0022] Transition portion 112 includes a tube cage comprising a
membrane wall of cooling tubes 214 extending circumferentially around throat
114.
Stagnant annular space 216 extends radially outward from cooling tubes 214 to
transition portion 112 to provide an area for risers and downcomers (both not
shown)
that supply water and remove water and steam from gas cooler 110. Throat 114
is
lined with a throat layer 218 of refractory bricks that extends from a third
annular
anchoring ring 220 coupled to cooling tubes 214 upward to bottom exit passage
116.
Anchoring ring 220 extends radially inward from cooling tubes 214 and supports
throat layer 218.
[0023] A fourth anchoring ring 312 extends radially inward from
support skirt 301 to a radially outer periphery of throat layer 218. Anchoring
ring 312
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supports a transition layer 314 of refractory brick and/or castable refractory
material.
Transition layer 314 provides for sliding engagement between first layer 302
and
transition layer 314, and between throat layer 218 and transition layer 314 to
account
for differential expansion and contraction between cooling tubes 214 and upper
shell
104.
[0024] Figure 4 is a schematic diagram of a throat area of a vessel
400 in accordance with another embodiment of the present invention. Vessel 400
is
substantially similar to vessel 300 (shown in Figure 3) and components of
vessel 400
that are identical to components of vessel 300 are identified in Figure 4
using the
same reference numerals used in Figure 3. In the exemplary embodiment, throat
layer
218 includes a converging-diverging cross section that facilitates removal of
entrained
particles and slag from reaction zone 106. The converging cross-section at
throat
entrance 123 tends to increase a velocity of the hot raw effluent gas steam
exiting
reaction zone 106 and tends to increase a back pressure inside reaction zone
106 that
also reduces backflow of gas into reaction zone 106. The diverging cross-
section
provides an overhang for slag to drip through throat 114 rather than flow down
the
refractory brick of the lower portion of throat layer 218.
[0025] Figure 5 is a schematic diagram of a throat area of a vessel
500 in accordance with another embodiment of the present invention. Vessel 500
is
substantially similar to vessel 300 (shown in Figure 3) and components of
vessel 500
that are identical to components of vessel 300 are identified in Figure 5
using the
same reference numerals used in Figure 3. In the exemplary embodiment, throat
layer
502 includes a first layer 504 and a second layer 506 that includes a step 508
at a joint
510 between first layer 504 and a second layer 506. A gap 512 is provided to
permit
axial movement between first layer 504 and a second layer 506 during
differential
expansion and contraction of cooling tubes 214 and upper shell 104. Gap 512
prevents an underhang 514 of layer 506 from bearing on an overhang 516 of
layer 504
and causing cracking and/or displacement of the refractory brick comprising
first
layer 504 and a second layer 506. Step 508 also provides an additional
tortuous path
for the hot raw effluent gas steam to pass before it can reach upper shell
104, cooling
tubes 214, or other metal portions of vessel 500.
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[0026] Exemplary embodiments of systems and methods for an
integral gasifier and syngas cooler combination are described above in detail.
The
systems and methods illustrated are not limited to the specific embodiments
described
herein, but rather, components of the system may be utilized independently and
separately from other components described herein. Further, steps described in
the
method may be utilized independently and separately from other steps described
herein. For example, step 508 shown in Figure 5 may be combined with throat
layer
218 having a converging-diverging cross-section shown in Figure 4. Other
combinations of the various embodiments of the present invention are also
contemplated.
[0027] Embodiments of the integral vessel that encloses the reactor,
the syngas cooler, and the transition in between eliminate a flanged joint
between the
reactor, the syngas cooler, and the transition, thus separating the gas path
transition
(throat) 114 from the outer vessel transition 112. Such a configuration
permits a
shorter throat length than vessel configurations that include separate vessels
with a
flanged transition between them while maintaining the same or a larger annular
space
216. The integral configuration also permits cooling throat refractory lining
218
along its entire length and/or cooling transition refractory 314.
[0028] Embodiments of the present invention provide for reducing
overall vessel length, reducing piping length and pipe stress, reducing
material and
fabrication cost, and the following improvement concepts and benefits; a steam-
cooled throat refractory lining, a steam-cooled transition portion and throat
refractory
lining, "drip points" in the throat flow path, which are only effective using
the
reduced length throat that embodiments of the present invention permit.
Embodiments of the present invention also permit gas flow moderation and a
longer
life transition point, an expansion feature of the gasification portion-to-
throat
transition brick allowing thicker brick for longer life at a high wear point,
a ship lap
expansion joint, a steam cooled refractory brick lining, modified support
features of
gasifier sidewall, gasifier transition, gasifier throat and syngas cooler
throat linings, an
integral gasifier and syngas cooler vessel, and a flexible flow path diameter
and shape
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in the refractory lined throat wherein the variable diameter can be realized
using
stepwise increase in lining thickness.
[0029] The steam cooled refractory lining in the transition and/or
throat allows longer run life and less down times for refractory replacement,
which
increases the availability of gasification process and reduces operation cost.
The
steam cooled refractory lining also adds flexibility in adjusting syngas
velocity and/or
mass and momentum flux exiting the throat by means of variable diameter in the
refractory lined throat. Active cooling of the refractory lining is
accomplishing by
extending the steam cooled tubes from the syngas cooler into the gasifier
and/or tube
cage. The integrated vessel and refractory lining permits the flexibility of
varying the
refractory lined throat flow path diameter and shape without alternating the
steel
vessel flanges. The throat shape could be cylindrical, conical, or flaring out
with the
diameter increasing as the flow approaches the downstream exit of the throat.
[0030] The above-described embodiments of a method and system
for an integrated gasifier and syngas cooler system provides a cost-effective
and
reliable means for eliminating the horizontal flange-to-flange joint between
the
gasifier and the syngas cooler using instead a non-continuous and integral
vessel that
encloses the refractory-lined gasification reaction chamber and the syngas
cooler heat
exchanger internals together in the single vessel. Additionally, embodiments
of the
present invention provide sufficient internal volume in the gasifier-to-syngas
cooler
transition area to extend the throat tube cage to the bottom transition of the
gasifier,
which enables steam cooling of the refractory lining of the entire length of
the throat,
and/or of the entire throat plus the 45 degree bottom transition in the
gasifier. The
steam-cooled refractory lining has a longer life that without active steam
cooling in
the throat. Further, the supports of the refractory linings in the gasifier
sidewall,
transition, and throat sections accommodate the expansion and contraction of
the
gasifier sidewall, transition, and throat sections during periods of
temperature
changes. Accordingly, direct leak paths in the refractory lining for syngas to
flow into
the transition area are substantially eliminated. As a result, the methods and
systems
described herein facilitate gasification and cooling of a fuel in a cost-
effective and
reliable manner.
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[0031 ] While the disclosure has been described in terms of various
specific embodiments, it will be recognized that the disclosure can be
practiced with
modification within the spirit and scope of the claims.
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