U.S. patent application number 15/618913 was filed with the patent office on 2017-12-14 for circulating fluidized bed boiler with bottom-supported in-bed heat exchanger.
The applicant listed for this patent is The Babcock & Wilcox Company. Invention is credited to Scott B. Anderson, Aaron Gavlak, David L. Kraft, Mikhail Maryamchik, John M. Sanders, Michael J. Szmania.
Application Number | 20170356642 15/618913 |
Document ID | / |
Family ID | 60572562 |
Filed Date | 2017-12-14 |
United States Patent
Application |
20170356642 |
Kind Code |
A1 |
Maryamchik; Mikhail ; et
al. |
December 14, 2017 |
CIRCULATING FLUIDIZED BED BOILER WITH BOTTOM-SUPPORTED IN-BED HEAT
EXCHANGER
Abstract
A circulating fluidized bed (CFB) boiler has one or more
bubbling fluidized bed enclosures containing heating surfaces and
located within a lower portion of the CFB boiler to provide an
in-bed heat exchanger (IBHX). Solids in the bubbling fluidized bed
are maintained in a slow bubbling fluidized bed state by separately
controlled fluidization gas supplies. The beds feature open bottom
distribution grids with hoppers disposed below to collect solids.
The enclosure defining the IBHX is supported from structures below
the grids and the enclosure can be supported from the hoppers.
Inventors: |
Maryamchik; Mikhail;
(Swampscott, MA) ; Anderson; Scott B.; (Clinton,
OH) ; Gavlak; Aaron; (Strongsville, OH) ;
Kraft; David L.; (Massillon, OH) ; Sanders; John
M.; (Akron, OH) ; Szmania; Michael J.;
(Medina, OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
The Babcock & Wilcox Company |
Barberton |
OH |
US |
|
|
Family ID: |
60572562 |
Appl. No.: |
15/618913 |
Filed: |
June 9, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62349627 |
Jun 13, 2016 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F22B 31/0061 20130101;
F23C 2206/102 20130101; F22B 31/0092 20130101; F23C 10/20 20130101;
F22B 31/0069 20130101; F23C 10/22 20130101; F23C 10/12 20130101;
F22B 31/0023 20130101 |
International
Class: |
F22B 31/00 20060101
F22B031/00; F23C 10/12 20060101 F23C010/12; F23C 10/20 20060101
F23C010/20; F23C 10/22 20060101 F23C010/22 |
Claims
1. A circulating fluidized bed (CFB) boiler comprising: a CFB
reaction chamber having side walls and an open-bottom grid defining
a floor at a lower end of the CFB reaction chamber for providing
fluidizing gas into the CFB reaction chamber; at least one bubbling
fluidized bed (BFB) located within a lower portion of the CFB
reaction chamber and being bound by enclosure walls and the floor
of the CFB reaction chamber, with the fluidizing gas feed to the
BFB portion of the grid controlled separately from the fluidizing
gas feed to the CFB portion of the grid; at least one controllable
in-bed heat exchanger (IBHX), the IBHX occupying part of the CFB
reaction chamber floor and being surrounded by the enclosure walls
of the BFB; bottom-supported hoppers containing dormant solids
disposed under the CFB and the BFB; the enclosure walls of the BFB
being supported off the bottom-supported hoppers; the enclosure
walls of the BFB are of cooled membrane gas-tight design around the
perimeter of the BFB, including: at least one top opening for CFB
solids influx into the BFB; at least one overflow port for setting
the BFB height; at least one underflow port for BFB solids
controlled recycle back into the CFB; the gas-tight BFB enclosure
extending below the grid to the elevation sufficient for not
exceeding a preset percentage of leakage of the fluidizing gas from
the BFB into the CFB through the bed of the dormant solids between
the aforementioned elevation and the grid; and the tubes of the BFB
enclosure below that elevation becoming of a loose design with
sufficient flexibility for accommodating differences in thermal
expansion of the tubes and the hoppers as the tubes penetrate the
walls of the hoppers.
2. The CFB boiler according to claim 1, wherein the walls of the
CFB reaction chamber are top supported and an expansion joint is
installed around the perimeter of the reaction chamber between its
walls and the hoppers for providing a pressure seal while allowing
the downward expansion of the walls and the upward expansion of the
hoppers.
3. The CFB boiler according to claim 1, wherein the BFB enclosure
includes a secondary gas duct.
4. The CFB boiler according to claim 3, wherein the secondary gas
duct is made of tubes of the BFB enclosure.
5. The CFB boiler according to claim 3, wherein the secondary gas
duct is supplied with the secondary gas through at least one
conduit made of membrane panels extending downward to essentially
the same elevation as where the gas-tight BFB enclosure terminates
and turns into a loose-tube design.
6. The CFB boiler according to claim 5, wherein the at least one
secondary gas conduit upon termination of the membrane-panel
design: continues as a plate-type design gas-tightly connected to
the membrane-panel part of the conduit, the connection design
allowing an independent thermal expansion of either part, the
plate-type part further penetrating through the hopper wall, the
penetration design accommodating independent thermal expansions of
the conduit and the hopper, and the tubes forming the membrane-type
part becoming of a loose design with sufficient flexibility for
accommodating differences in thermal expansion of the tubes and the
hopper as the tubes penetrate the hopper wall.
7. The CFB boiler according to claim 1, wherein the walls of the
CFB reaction chamber are bottom supported.
8. A circulating fluidized bed (CFB) boiler comprising: a CFB
reaction chamber having walls and an open-bottom grid defining a
floor at a lower end of the CFB reaction chamber for providing
fluidizing gas into the CFB reaction chamber; at least one bubbling
fluidized bed (BFB) located within a lower portion of the CFB
reaction chamber and being bound by enclosure walls and the floor
of the CFB reaction chamber, with the fluidizing gas feed to the
BFB portion of the grid controlled separately from the fluidizing
gas feed to the CFB portion of the grid; at least one controllable
in-bed heat exchanger (IBHX), the IBHX occupying part of the CFB
reaction chamber floor and being surrounded by the enclosure walls
of the BFB; hoppers containing dormant solids disposed under the
CFB and the BFB; and the enclosure walls of the BFB being supported
off the bottom-supported hoppers.
9. The CFB boiler of claim 8, wherein the hoppers include an inner
hopper for the BFB and an outer hopper for the CFB; a skirt
connected to a portion of the enclosure walls and extending into
the inner hopper to form a seal.
10. The CFB boiler of claim 8, further comprising thermal expansion
accommodating support plates supporting the enclosure walls from
the bottom-supported hoppers.
11. The CFB boiler of claim 10, wherein the enclosure walls include
membranes; the support plates being connected to the membranes.
12. The CFB boiler of claim 11, wherein the membranes terminate
below the connection of the support plates and the membranes.
13. The CFB boiler of claim 8, wherein the walls of the CFB
reaction chamber are top supported and an expansion joint is
disposed around the perimeter of the CFB reaction chamber between
its walls and the hoppers for providing a pressure seal while
allowing the downward expansion of the walls and the upward
expansion of the hoppers.
14. The CFB boiler of claim 8, wherein the enclosure walls of the
BFB are of cooled membrane gas-tight design.
15. The CFB boiler of claim 14, wherein the BFB enclosure includes
a secondary gas duct.
16. The CFB boiler of claim 15, wherein the secondary gas duct is
made of portions of the BFB enclosure walls.
17. The CFB boiler of claim 15, wherein the secondary gas duct is
supplied with the secondary gas through at least one conduit made
of membrane panels extending downward to about the same elevation
as where the BFB enclosure is supported by the hoppers.
18. The CFB boiler of claim 17, wherein the at least one secondary
gas conduit, below the same elevation: continues as a plate-type
design gas-tightly connected to the membrane-panel part of the
conduit, the connection design allowing an independent thermal
expansion of either part; the plate-type part further penetrating
through the hopper wall, the penetration design accommodating
independent thermal expansions of the conduit and the hopper; and
the tubes forming the membrane-type part becoming of a loose design
with sufficient flexibility for accommodating differences in
thermal expansion of the tubes and the hopper as the tubes
penetrate the hopper wall.
19. A circulating fluidized bed (CFB) boiler comprising: a CFB
reaction chamber having walls and an open-bottom grid defining a
floor at a lower end of the CFB reaction chamber for providing
fluidizing gas into the CFB reaction chamber; at least one bubbling
fluidized bed (BFB) located within a lower portion of the CFB
reaction chamber and being bound by enclosure walls and the floor
of the CFB reaction chamber, with the fluidizing gas feed to the
BFB portion of the grid controlled separately from the fluidizing
gas feed to the CFB portion of the grid; the enclosure walls of the
BFB are of cooled membrane gas-tight design; at least one
controllable in-bed heat exchanger (IBHX), the IBHX occupying part
of the CFB reaction chamber floor and being surrounded by the
enclosure walls of the BFB; hoppers containing dormant solids
disposed under the CFB and the BFB; and the enclosure walls of the
BFB being connected to at least one of the bottom-supported hoppers
with supports and becoming of a loose design with sufficient
flexibility for accommodating differences in thermal expansion of
the tubes and the hopper as the tubes penetrate the hopper wall.
Description
RELATED APPLICATION DATA
[0001] This patent application claims priority to U.S. Provisional
Patent Application No. 62/349,627 filed Jun. 13, 2016 and titled
"CIRCULATING FLUIDIZED BED BOILER WITH BOTTOM-SUPPORTED IN-BED HEAT
EXCHANGER." The complete text of this patent application is hereby
incorporated by reference as though fully set forth herein in its
entirety.
FIELD AND BACKGROUND OF THE INVENTION
1. Technical Field
[0002] The present disclosure generally relates to the field of
circulating fluidized bed (CFB) reactors or boilers such as those
used in electric power generation facilities and, in particular, to
a new and useful CFB reactor arrangement which permits temperature
control within the CFB reaction chamber and/or of the effluent
solids with an in-bed heat exchanger (IBHX). The CFB reactor
arrangement provides a bottom-supported IBHX wherein the enclosure
that defines the IBHX is supported from the dormant solids hoppers
for the CFB and bubbling fluidized bed (BFB) of the IBHX.
2. Background Information
[0003] Circulating fluidized bed (CFB) reactors or boilers are used
in the production of steam for industrial processes and electric
power generation; see, for example, U.S. Pat. Nos. 5,799,593,
4,992,085, 4,891,052, 5,343,830, 5,378,253, 5,435,820, and
5,809,940. For an overview of the design and operation of CFB
boilers, see Steam/its generation and use, 42nd Edition, edited by
G. L. Tomei, Copyright 2015, The Babcock & Wilcox Company, ISBN
978-0-9634570-2-8, the text of which is hereby incorporated by
reference as though fully set forth herein.
[0004] In a CFB boiler, upward gas flow carries reacting and
non-reacting solids to an outlet at the upper portion of the
furnace where the solids are separated from the gas, often by a
staggered array of impact-type particle separators. The solids are
used within the combustion process to transfer heat from the
chemical process to the boiler water-cooled enclosure walls and
other heating surfaces. The solids thus help control the overall
furnace temperature that results in reducing NOx and SO.sub.2. The
bulk of the solids reaching the top of the furnace are collected
and returned to the furnace bottom.
[0005] U.S. Pat. No. 6,532,905 discloses a controllable solids heat
exchanger called an in-bed heat exchanger (IBHX). The heat
exchanger is immersed within a bubbling fluidized bed (BFB). Heat
transfer in the heat exchanger is controlled by controlling the
rate of solids discharge from the lower part of the BFB into the
furnace. The discharge control is accomplished using at least one
non-mechanical valve being operated by controlling flow rate of
fluidizing gas in the vicinity of the non-mechanical valve.
Reducing or completely shutting off fluidizing gas flow to the
controlling fluidizing device (typically, a plurality of bubble
caps are used to distribute the fluidizing gas) hampers local
fluidization and, correspondingly, slows down solids movement
through the non-mechanical valve thus allowing the control of the
solids discharge from the BFB to the CFB. U.S. Pat. No. 8,434,430
discloses an example of a controllable non-mechanical valve for an
IBHX in FIG. 3 of the patent.
[0006] An undesired drawback of reducing the flow rate of the
fluidizing gas in the vicinity of the non-mechanical valve is bed
material agglomeration. The decrease of the local fluidizing
velocity and corresponding reduction of the bed mixing (while
combustion takes place) can result in a local bed temperature rise
sufficient for bed material agglomeration. Solids agglomeration may
also happen elsewhere in the bed of the IBHX because generally
lower fluidizing velocity in the BFB (compared to CFB) results in
less vigorous mixing and thus higher potential for temperature and
chemical non-uniformity leading to forming agglomerates. To be
discharged from the IBHX through a dedicated drain opening, the
agglomerates have to be moved towards this opening by the solids
discharge flow. If the flow is not sufficient to move the
agglomerates, they will eventually accumulate in the IBHX rendering
its inoperable.
[0007] Using an open bottom design (see Steam: Its Generation and
Use, 41st ed., page 17-3 (2005; The Babcock & Wilcox Company,
Barberton, Ohio) allows draining agglomerates from any location of
the IBHX thus greatly improving its operation reliability. Using an
open bottom design with an IBHX, however, is associated with a
substantial weight of bed material in the hopper(s) below the IBHX
and corresponding load increase on the boiler support steel.
SUMMARY OF THE INVENTION
[0008] The present disclosure improves reliability of the CFB
boiler with IBHX while reducing its cost and widening the range of
design options.
[0009] The disclosure provides a configuration wherein the
enclosure of the IBHX is supported from the dormant solids hoppers
for CFB and IBHX located under the distribution grids.
[0010] The disclosure provides a support configuration wherein the
membranes between the tubes of the enclosure walls are removed to
define loose tubes that extend through the hopper walls to
accommodate thermal expansion.
[0011] The disclosure provides a support configuration wherein a
skirt is disposed inside the IBHX hopper to prevent gas leakage
from the IBHX hopper to the CFB hopper around the enclosure
supports.
[0012] The disclosure provides a support configuration wherein a
secondary gas conduit is supported by the CFB hopper with a
secondary gas duct carried by the IBHX enclosure with nozzles to
provide secondary gas to the CFB.
[0013] One embodiment of the invention discloses a circulating
fluidized bed (CFB) boiler comprising: a CFB reaction chamber
having side walls and an open-bottom grid defining a floor at a
lower end of the CFB reaction chamber for providing fluidizing gas
into the CFB reaction chamber; at least one bubbling fluidized bed
(BFB) located within a lower portion of the CFB reaction chamber
and being bound by enclosure walls and the floor of the CFB
reaction chamber, with the fluidizing gas feed to the BFB portion
of the grid controlled separately from the fluidizing gas feed to
the CFB portion of the grid; at least one controllable in-bed heat
exchanger (IBHX), the IBHX occupying part of the CFB reaction
chamber floor and being surrounded by the enclosure walls of the
BFB; bottom-supported hoppers containing dormant solids disposed
under the CFB and the BFB; the enclosure walls of the BFB being
supported off the bottom-supported hoppers; the enclosure walls of
the BFB are of cooled membrane gas-tight design around the
perimeter of the BFB, including: at least one top opening for CFB
solids influx into the BFB; at least one overflow port for setting
the BFB height; at least one underflow port for BFB solids
controlled recycle back into the CFB; the gas-tight BFB enclosure
extending below the grid to the elevation sufficient for not
exceeding a preset percentage of leakage of the fluidizing gas from
the BFB into the CFB through the bed of the dormant solids between
the aforementioned elevation and the grid; and the tubes of the BFB
enclosure below that elevation becoming of a loose design with
sufficient flexibility for accommodating differences in thermal
expansion of the tubes and the hoppers as the tubes penetrate the
walls of the hoppers.
[0014] Another embodiment of the invention discloses a circulating
fluidized bed (CFB) boiler comprising: a CFB reaction chamber
having walls and an open-bottom grid defining a floor at a lower
end of the CFB reaction chamber for providing fluidizing gas into
the CFB reaction chamber; at least one bubbling fluidized bed (BFB)
located within a lower portion of the CFB reaction chamber and
being bound by enclosure walls and the floor of the CFB reaction
chamber, with the fluidizing gas feed to the BFB portion of the
grid controlled separately from the fluidizing gas feed to the CFB
portion of the grid; at least one controllable in-bed heat
exchanger (IBHX), the IBHX occupying part of the CFB reaction
chamber floor and being surrounded by the enclosure walls of the
BFB; hoppers containing dormant solids disposed under the CFB and
the BFB; and the enclosure walls of the BFB being supported off the
bottom-supported hoppers.
[0015] Yet another embodiment of the invention discloses a
circulating fluidized bed (CFB) boiler comprising: a CFB reaction
chamber having walls and an open-bottom grid defining a floor at a
lower end of the CFB reaction chamber for providing fluidizing gas
into the CFB reaction chamber; at least one bubbling fluidized bed
(BFB) located within a lower portion of the CFB reaction chamber
and being bound by enclosure walls and the floor of the CFB
reaction chamber, with the fluidizing gas feed to the BFB portion
of the grid controlled separately from the fluidizing gas feed to
the CFB portion of the grid; the enclosure walls of the BFB are of
cooled membrane gas-tight design; at least one controllable in-bed
heat exchanger (IBHX), the IBHX occupying part of the CFB reaction
chamber floor and being surrounded by the enclosure walls of the
BFB; hoppers containing dormant solids disposed under the CFB and
the BFB; and the enclosure walls of the BFB being connected to at
least one of the bottom-supported hoppers with supports and
becoming of a loose design with sufficient flexibility for
accommodating differences in thermal expansion of the tubes and the
hopper as the tubes penetrate the hopper wall.
[0016] The preceding non-limiting aspects, as well as others, are
more particularly described below. A more complete understanding of
the processes and equipment can be obtained by reference to the
accompanying drawings, which are not intended to indicate relative
size and dimensions of the assemblies or components thereof. In
those drawings and the description below, like numeric designations
refer to components of like function. Specific terms used in that
description are intended to refer only to the particular structure
of the embodiments selected for illustration in the drawings, and
are not intended to define or limit the scope of the
disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a sectional side elevation view of a CFB boiler
depicting a first exemplary configuration of the disclosure,
illustrating a bubbling fluidized bed (BFB) enclosure within the
CFB boiler.
[0018] FIG. 2 is an enlarged view of a portion of the BFB enclosure
disposed below the distribution grid of the CFB.
[0019] FIG. 2A is a view taken along line 2A-2A of FIG. 2.
[0020] FIG. 3 is a plan view looking down along line 3-3 of FIG.
1.
[0021] FIG. 4 is a section view taken along line 4-4 of FIG. 3.
DETAILED DESCRIPTION OF THE DISCLOSURE
[0022] As shown in FIGS. 1-4, a circulating fluidized bed (CFB)
furnace 1 includes walls 2 (including roof 2a) and an in-bed heat
exchanger (IBHX) 3 immersed in bubbling fluidized bed (BFB) 4. The
circulating fluidized bed of furnace 1 predominantly includes
solids made up of the ash of fuel 5, sulfated sorbent 6 and, in
some cases, external inert material 7 fed through at least one of
walls 2 and fluidized by fluidizing gas (typically, primary air) 8
supplied through a distribution grid 9 fed from pipes 10. Dormant
solids below grid 9 effectively define a part of the furnace floor.
Some solids are entrained by gases resulting from the fuel
combustion and move upward (arrows 15) eventually reaching a
particle separator 16 at the furnace exit. While some of the solids
(arrow 17) pass separator 16, the bulk of them (arrow 18) are
captured and recycled back to the furnace. Those solids along with
others (arrow 19), falling out of upflow solids stream 15, feed BFB
4 that is being fluidized by fluidizing gas (typically, air) 22
supplied through a BFB distribution grid 24 fed from pipes 25.
Dormant solids below grid 24 effectively define another part of the
furnace floor. The dormant solids under CFB and BFB are contained
in hoppers (26 and 27, correspondingly) equipped with outlets for
draining solids from CFB and BFB (28 and 29, correspondingly).
Pipes 10 and 25 are supported off hoppers 26 and 27,
correspondingly (supports are not shown).
[0023] BFB 4 is separated from the CFB by an enclosure 30 made of
gas-tight cooled membrane panels. Enclosure 30 surrounds the
perimeter of BFB 4 but is essentially open from the top allowing
solids influx from CFB into BFB (arrow 19). Enclosure 30 includes
overflow ports (that can be formed as vertical slots connected to
top opening 31; see FIG. 3) 32, which lowest elevation essentially
defines the height of BFB 4. Enclosure 30 also includes underflow
ports 34. Controlling rate of solids recycle 35 through underflow
ports 34 allows controlling the heat duty of IBHX 3. The rate of
solids recycle 35 is controlled by separately controlling (not
shown) feed rate of fluidizing medium 22 to BFB plan areas adjacent
to underflow ports 34.
[0024] The pressure within enclosure 30 equals the pressure outside
of it at the elevation of the top of BFB 4. Due to higher bulk
density of BFB compared to CFB, the pressure below that elevation
is higher on the BFB side, i.e. within enclosure 30. The highest
pressure differential is at the elevation of the distribution grids
(9 and 24, located essentially at the same elevation). Cooled
membrane panels 60 are used as stiffeners of enclosure walls 30
providing the rigidity necessary to withstand the pressure
differential. The height of panels 60 depends on the amount of heat
transfer surface required for the furnace heat duty. They can
extend all the way through the furnace roof 2A or be cut shorter
and topped with headers 65, from which pipes 70 continue up to roof
2A. The lower ends of panels 60 penetrate through hoppers 27 and
terminate with headers 61.
[0025] Enclosure 30 is topped with a header 72 that is connected
with the outside of the furnace through pipes 74. If temperature of
the cooling medium in enclosure 30 and/or panels 60 differs from
that of walls 2, corresponding penetrations through roof 2A are
equipped with expansion joints 76 and 78. The lower part of
enclosure 30 extends below grid 24. The weight of enclosure 30 is
supported off hoppers 26 and 27. An exemplary configuration of a
supports 79 and 80 for supporting enclosure 30 is depicted in FIGS.
2 and 2A. Support 79 is welded to the walls of the hoppers 26 and
27 while support 80 is welded to membranes 81. Horizontal pads 82
and 83 are welded to supports 79 and 80, respectively. The pads 82
and 83 can slide against each other that allows for independent
thermal expansion of enclosure 30 and hoppers 26 and 27. FIGS. 2
and 2A depict one exemplary configuration but other support
arrangements can be used to support enclosure 30 from one or both
of hoppers 26 and 27. Below the support elevation, the membranes 81
in the panels forming enclosure 30 terminate, and the resulting
configuration of loose tubes 84 provides flexibility to accommodate
differences in thermal expansion of tubes 84 and hoppers 26 and 27
as tubes 84 penetrate the walls of hopper 26. Skirt 86 is attached
to the inside of enclosure 30 above support 80 and extends into
hopper 27. Positive pressure in hopper 27 (compared to hopper 26)
pushes skirt 86 against the wall of hopper 27 creating a seal
(along with the resistance of the layer of dormant solids below
grid 24) that essentially eliminates fluidizing gas leakage between
hoppers 26 and 27. Loose tubes 84 are connected to headers 88
outside hoppers 26 and 27.
[0026] IBHX 3 can be supported off platework between hoppers 27 or
off enclosure 30 or some combination thereof. IBHX 3 terminates at
headers 89.
[0027] Enclosure 30 also includes a duct 92 for supplying part of
secondary gas (typically, secondary air) 95 through nozzles 98 into
the CFB. Nozzles 98 can be formed of enclosure 30 tubes. Another
part of secondary gas 95 is supplied through nozzles 99 on walls 2.
The combination of nozzles 98 and 99 allows effective coverage of
furnace 1 plan area by secondary gas 95. One type of nozzle that
can be used is disclosed in U.S. Pat. No. 8,622,029, the text of
which is hereby incorporated by reference as though fully set forth
herein. At certain conditions, e.g. for smaller furnace sizes, it
is possible to provide an acceptable secondary gas coverage by
using only nozzles 99 on walls 2. In such a configuration, duct 92
is not required and can be removed.
[0028] Duct 92 is supplied with secondary gas 95 through a conduit
102 made of membrane panels 104. As shown in FIG. 4, part of the
panel 104 between duct 92 and conduit 102 turns into screen 105 to
allow a passage for the secondary gas from conduit 102 into duct
92. Panels 104 at the upper end can terminate at header 72 and/or
dedicated headers (not shown). Their lower ends extend downward to
essentially the same elevation as where gas-tight BFB enclosure 30
turns into a loose-tube type design. At that elevation conduit 102
made of panels 104 is connected gas-tightly to plate-type conduit
106 that continues to the wall of hopper 26 and penetrates the
wall. Conduit 106 is equipped with expansion joints 107 on its both
ends for accommodating its thermal expansion versus conduit 102 and
hopper 26. Upon the connection with conduit 106, membrane panels
104 turn into loose tubes 108, which configuration allows
accommodation of the difference in thermal expansion between tubes
108 and hopper 26 as the tubes penetrate the hopper wall and
terminate at header 109.
[0029] Furnace walls 2 are supported off top steel 110 and expand
downwards. Hoppers 26 and 27 have bottom supports 115 and expand
upwards. A pressure seal allowing both expansions is provided by
expansion joint 120 around the perimeter of furnace 1. At certain
conditions, e.g. lower furnace height due to high fuel reactivity
and/or relaxed combustion efficiency requirements and/or relaxed
emissions requirements, etc., the entire boiler can be
bottom-supported. This would eliminate the need in expansion joint
120.
[0030] The foregoing description has been made with reference to
exemplary embodiments. Modifications and alterations of those
embodiments will be apparent to one who reads and understands this
general description. The present disclosure should be construed as
including all such modifications and alterations insofar as they
come within the scope of the appended claims or equivalents
thereof.
[0031] The relevant portion(s) of any specifically referenced
patent and/or published patent application is/are incorporated
herein by reference.
* * * * *