U.S. patent application number 12/692217 was filed with the patent office on 2011-07-28 for method and apparatus to preheat slurry.
Invention is credited to Aaron John Avagliano, Judeth Helen Brannon Corry, Lorena Yossette Sullivan, Pradeep S. Thacker.
Application Number | 20110179712 12/692217 |
Document ID | / |
Family ID | 44307870 |
Filed Date | 2011-07-28 |
United States Patent
Application |
20110179712 |
Kind Code |
A1 |
Thacker; Pradeep S. ; et
al. |
July 28, 2011 |
METHOD AND APPARATUS TO PREHEAT SLURRY
Abstract
A method of operating a gasification facility includes
channeling steam into a grinding mill via a flow control device and
a conduit. The method also includes mixing carbonaceous fuel,
preheated water, and steam within the grinding mill, to form a
preheated coal slurry stream.
Inventors: |
Thacker; Pradeep S.;
(Bellaire, TX) ; Avagliano; Aaron John; (Houston,
TX) ; Corry; Judeth Helen Brannon; (Manvel, TX)
; Sullivan; Lorena Yossette; (Houston, TX) |
Family ID: |
44307870 |
Appl. No.: |
12/692217 |
Filed: |
January 22, 2010 |
Current U.S.
Class: |
48/73 ;
48/202 |
Current CPC
Class: |
C10J 2300/0903 20130101;
C10J 2300/1678 20130101; C10J 2300/1807 20130101; C10J 3/506
20130101; C10J 2300/1653 20130101; C10L 1/322 20130101; F01K 23/067
20130101; C10J 2300/093 20130101; C10J 2300/0906 20130101; C10K
1/003 20130101; C10J 2300/0973 20130101; Y02E 20/16 20130101; Y02E
20/18 20130101; C10J 2300/0959 20130101 |
Class at
Publication: |
48/73 ;
48/202 |
International
Class: |
C10J 3/20 20060101
C10J003/20; C10J 3/16 20060101 C10J003/16 |
Claims
1. A method of operating a gasification facility, said method
comprising: channeling steam into a grinding mill via a flow
control device and a conduit; and mixing carbonaceous fuel,
preheated water, and steam within the grinding mill, to form a
preheated coal slurry stream.
2. A method in accordance with claim 1, wherein the conduit is one
of rigid conduit and flexible conduit.
3. A method in accordance with claim 1 further comprising:
channeling carbonaceous fuel into the grinding mill via a fuel flow
control device; and channeling preheated water into the grinding
mill via a flow control device.
4. A method in accordance with claim 3 further comprising at least
one of: channeling a slurry viscosity additive into the grinding
mill via a flow control device, thereby mixing the slurry viscosity
additive within the grinding mill; and heating the preheated coal
slurry stream by channeling steam into the preheated coal slurry
stream.
5. A method in accordance with claim 4, wherein mixing carbonaceous
fuel, preheated water, slurry viscosity additive, and steam within
the grinding mill comprises modulating a rate of flow of each of
the carbonaceous fuel, preheated water, slurry viscosity additive,
and steam for discharging the preheated coal slurry stream from the
grinding mill with at least one of a predetermined slurry
temperature and a predetermined slurry viscosity.
6. A method in accordance with claim 5, wherein discharging the
preheated coal slurry stream from the grinding mill comprises
preheating makeup water by at least one of: channeling steam
through at least one heating device immersed within a mixing tank;
channeling heated gasification by-product into the mixing tank and
at least partially mixing the makeup water with the heated
gasification by-product; and channeling at least partially mixed
makeup water and gasification by-product from the mixing tank to
the grinding mill and channeling steam into the makeup water and
the gasification by-product therebetween.
7. A method in accordance with claim 5, wherein discharging the
preheated coal slurry stream from the grinding mill comprises
preheating at least a portion of the carbonaceous fuel by
channeling steam into a coal transfer apparatus comprising at least
one of: channeling steam through at least a portion of a coal
storage bin; and channeling steam through at least a portion of a
coal conveyor.
8. A slurry preparation system coupled in flow communication with a
carbonaceous fuel source, a makeup water source, and a steam
source, said slurry preparation system comprising a fuel grinding
mill coupled in flow communication with the steam source via at
least one conduit.
9. A slurry preparation system in accordance with claim 8, wherein
said at least one conduit is one of a flexible conduit and a rigid
conduit.
10. A slurry preparation system in accordance with claim 8 further
comprising at least one slurry viscosity additive flow control
device coupled in flow communication with a slurry viscosity
additive source.
11. A slurry preparation system in accordance with claim 8 further
comprising at least one of: at least one steam flow control device
coupled in flow communication with the steam source and said at
least one conduit; and at least one temperature control device
coupled in communication with said at least one steam flow control
device.
12. A slurry preparation system in accordance with claim 11 further
comprising at least one mixing tank coupled in flow communication
with the makeup water source and with at least one gasification
by-product source.
13. A slurry preparation system in accordance with claim 12 wherein
said at least one mixing tank is coupled in flow communication with
said grinding mill via a fluid transfer conduit and at least one
of: at least one steam injection device coupled in flow
communication with said fluid transfer conduit; and at least one
fluid flow control device coupled in flow communication with said
fluid transfer conduit.
14. A slurry preparation system in accordance with claim 13 wherein
said at least one fluid flow control device is coupled in
communication with said at least one steam flow control device.
15. A gasification facility comprising: a carbonaceous fuel source;
a makeup water source; a steam source; and a slurry preparation
system coupled in flow communication with said carbonaceous fuel
source, said makeup water source, and said steam source, said
slurry preparation system comprising a fuel grinding mill coupled
in flow communication with said steam source via at least one
conduit.
16. A gasification facility in accordance with claim 15, wherein
said at least one conduit is one of a flexible conduit and a rigid
conduit.
17. A gasification facility in accordance with claim 15 further
comprising at least one slurry viscosity additive flow control
device coupled in flow communication with a slurry viscosity
additive source.
18. A gasification facility in accordance with claim 15 further
comprising at least one of: at least one steam flow control device
coupled in flow communication with the steam source and said at
least one conduit; and at least one temperature control device
coupled in communication with said at least one steam flow control
device.
19. A gasification facility in accordance with claim 18 further
comprising at least one mixing tank coupled in flow communication
with the makeup water source and with at least one gasification
by-product source, wherein said at least one mixing tank is coupled
in flow communication with said grinding mill via a fluid transfer
conduit and at least one of: at least one steam injection device
coupled in flow communication with said fluid transfer conduit; and
at least one fluid flow control device coupled in flow
communication with said fluid transfer conduit.
20. A gasification facility in accordance with claim 19 further
comprising a coal transfer apparatus coupled in flow communication
with said carbonaceous fuel source, said coal transfer apparatus
comprises a fuel flow control device coupled in communication with
said at least one fluid flow control device and said at least one
steam flow control device.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention herein relates generally to slurry
transport systems, and more particularly, to methods and apparatus
for preheating slurries to facilitate operation of synthetic gas
production facilities.
[0002] At least some known gasification plants include a
gasification system that is integrated with at least one
power-producing turbine system, to form an integrated gasification
combined cycle (IGCC) power generation plant. Such known
gasification systems convert a mixture of fuel, air or oxygen,
steam, and/or CO.sub.2 into a synthetic gas, or "syngas". Also,
many of such known gasification systems include a gasification
reactor that generates syngas therein. The syngas is channeled to
the combustor of a gas turbine engine, for use in powering a
generator that supplies electrical power to a power grid. Exhaust
from at least some known gas turbine engines is supplied to a heat
recovery steam generator (HRSG) that generates steam for use in
driving a steam turbine. Power generated by the steam turbine also
drives an electrical generator that provides electrical power to
the power grid.
[0003] At least some of the known gasification systems also include
at least one slurry feed pump that channels a fuel slurry to the
gasification reactor. Moreover, some of such known gasification
systems also include a slurry heating system that includes at least
one shell and tube heat exchanger. Preheating the slurry prior to
supplying the slurry to the gasification reactor generally
increases an efficiency of gasification. Such heat exchangers are
typically positioned downstream from the slurry feed pump and use
steam as the heating medium. Many of such heat exchangers may be
subject to a potential for fouling, plugging, and erosion.
Moreover, because a viscosity of the slurry may be high and because
the slurry flow through the heat exchanger tubes generally tends
towards laminar flow conditions, a heat transfer coefficient
associated with the heat exchanger is generally low, which actually
decreases efficiency of the heat exchanger. Other known
gasification systems may heat the slurry using direct steam
injection and mixing. However, such injection and mixing dilutes
the slurry and the efficiency of gasification may be subsequently
reduced.
BRIEF DESCRIPTION OF THE INVENTION
[0004] In one aspect, a method of operating a gasification facility
is provided. The method includes channeling steam into a grinding
mill via a flow control device and a conduit. The method also
includes mixing carbonaceous fuel, preheated water, and steam
within the grinding mill, to form a preheated coal slurry
stream.
[0005] In another aspect, a slurry preparation system is provided.
The slurry preparation system is coupled in flow communication with
a carbonaceous fuel source, a makeup water source, and a steam
source. The slurry preparation system includes a fuel grinding mill
coupled in flow communication with the steam source via at least
one conduit.
[0006] In yet another aspect, a gasification facility is provided.
The gasification facility includes a carbonaceous fuel source, a
makeup water source, and a steam source. The gasification facility
also includes a slurry preparation system coupled in flow
communication with the carbonaceous fuel source, the makeup water
source, and the steam source. The slurry preparation system
includes a fuel grinding mill coupled in flow communication with
the steam source via at least one conduit.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] The embodiments described herein may be better understood by
referring to the following description in conjunction with the
accompanying drawings.
[0008] FIG. 1 is a schematic diagram of an exemplary integrated
gasification combined-cycle (IGCC) power generation plant;
[0009] FIG. 2 is a schematic diagram of an exemplary slurry
preparation system that may be used with the IGCC power generation
plant shown in FIG. 1; and
[0010] FIG. 3 is a flow chart illustrating an exemplary method of
operating the IGCC power generation plant shown in FIG. 1.
DETAILED DESCRIPTION OF THE INVENTION
[0011] FIG. 1 is a schematic diagram of an exemplary chemical
production system, and more specifically, an exemplary integrated
gasification combined-cycle (IGCC) power generation plant 100. In
the exemplary embodiment, IGCC power generation plant 100 includes
a gas turbine engine 110 that includes a turbine 114 that is
rotatably coupled to a first electrical generator 118 via a first
rotor 120. Turbine 114 is coupled in flow communication with at
least one fuel source and at least one air source and receives fuel
and air from the fuel and air sources, respectively. Turbine 114
mixes the air and fuel, produces hot combustion gases (not shown),
and converts heat energy within the gases to rotational energy.
That is transmitted to generator 118 via rotor 120. Generator 118
converts the rotational energy to electrical energy (not shown) for
transmission to at least one load, such as, but not limited to, an
electrical power grid (not shown).
[0012] IGCC power generation plant 100 also includes a steam
turbine engine 130. In the exemplary embodiment, engine 130
includes a steam turbine 132 that is coupled to a second electrical
generator 134 via a second rotor 136.
[0013] Moreover, in the exemplary embodiment, IGCC power generation
plant 100 also includes a steam generation system 140 that includes
at least one heat recovery steam generator (HRSG) 142 coupled in
flow communication with at least one heat transfer apparatus 144
via at least one heated boiler feedwater conduit 146. HRSG 142
receives boiler feedwater (not shown) from apparatus 144 via
conduit 146. The boiler feedwater is heated into steam (not shown).
HRSG 142 also receives exhaust gases (not shown) from turbine 114
via an exhaust gas conduit 148. The exhaust gases also heat the
boiler feedwater into steam. HRSG 142 is coupled in flow
communication with turbine 132 via a steam conduit 150. Excess
gases and steam (both not shown) are exhausted from HRSG 142 to the
atmosphere via stack gas conduit 152.
[0014] Conduit 150 channels steam (not shown) from HRSG 142 to
turbine 132. Turbine 132 receives steam from HRSG 142 and converts
the thermal energy in the steam to rotational energy. The
rotational energy is transmitted to generator 134 via rotor 136,
wherein generator 134 converts the rotational energy to electrical
energy (not shown) for transmission to at least one load,
including, but not limited to, an electrical power grid. The steam
is condensed and returned as boiler feedwater via a condensate
conduit (not shown).
[0015] In the exemplary embodiment IGCC power generation plant 100
also includes a gasification system 200 that includes at least one
air separation unit 202 that is coupled in flow communication with
an air source via an air conduit 204. Such air sources may include,
but are not limited to, dedicated air compressors and compressed
air storage units (neither shown). Unit 202 separates air into
oxygen (O.sub.2), nitrogen (N.sub.2), and other components (neither
shown) that are either released via a vent (not shown) or channeled
and/or collected for further use. For example, in the exemplary
embodiment, N.sub.2 is channeled to gas turbine 114 via a N.sub.2
conduit 206 to facilitate combustion.
[0016] System 200 includes a gasification reactor 208 that is
coupled in flow communication with unit 202 to receive oxygen
channeled from unit 202 via an O.sub.2 conduit 210. System 200 also
includes a fuel preparation system 211, that in the exemplary
embodiment, is, a slurry preparation system 211. Slurry preparation
system 211 is coupled in flow communication with a carbonaceous
fuel source (not shown), such as, a coal source and a water source,
via a coal supply conduit 212 and a water supply conduit 213,
respectively. System 211 mixes coal and water to form a coal slurry
stream that has a predetermined temperature and viscosity, that is
channeled to reactor 208 via a coal slurry conduit 214.
[0017] Reactor 208 receives the coal slurry stream and an O.sub.2
stream (not shown) via respective conduits 214 and 210. Reactor 208
produces a hot, raw synthetic gas (syngas) stream (not shown), that
includes carbon monoxide (CO), hydrogen (H.sub.2), carbon dioxide
(CO.sub.2), carbonyl sulfide (COS), and hydrogen sulfide
(H.sub.2S). While CO.sub.2, COS, and H.sub.2S are typically
collectively referred to as acid gases, or acid gas components of
the raw syngas, CO.sub.2 will be discussed herein separately from
the remaining acid gas components. Moreover, reactor 208 also
produces a hot slag stream (not shown) as a first gasification
by-product resulting from syngas production. The slag stream is
channeled to a slag handling unit 215 via a hot slag conduit 216.
Unit 215 quenches and breaks up the slag into smaller slag pieces
wherein a slag removal stream is produced and channeled through
conduit 217.
[0018] Reactor 208 is coupled in flow communication with heat
transfer apparatus 144 via a hot syngas conduit 218. Apparatus 144
receives the hot, raw syngas stream and transfers at least a
portion of the heat to HRSG 142 via conduit 146. Subsequently,
apparatus 144 produces a cooled raw syngas stream (not shown) that
is channeled to a scrubber and low temperature gas cooling (LTGC)
unit 221 via a syngas conduit 219. Unit 221 removes a second
gasification by-product, that is, particulate matter entrained
within the raw syngas stream, and discharges the removed matter via
a fly ash conduit 222. Unit 221 facilitates cooling the raw syngas
stream, and converts at least a portion of COS in the raw syngas
stream to H.sub.2S and CO.sub.2 via hydrolysis.
[0019] System 200 also includes an acid gas removal subsystem 300
that is coupled in flow communication with unit 221 to receive the
cooled raw syngas stream via a raw syngas conduit 220. Subsystem
300 removes at least a portion of acid components (not shown) from
the raw syngas stream as described in more detail below. Such acid
gas components may include, but are not limited to, CO.sub.2, COS,
and H.sub.2S. Subsystem 300 also separates at least some of the
acid gas components into components that include, but are not
limited to, CO.sub.2, COS, and H.sub.2S. Moreover, subsystem 300 is
coupled in flow communication with a sulfur reduction subsystem 400
via a conduit 223. Subsystem 400 receives and separates at least
some of the acid gas components into components that include, but
are not limited to, CO.sub.2, COS, and H.sub.2S. Such acid
components removed and separated are channeled into at least one
third gasification by-product stream (not shown) that is removed
from system 200.
[0020] Furthermore, subsystem 400 channels a final integrated gas
stream (not shown) to reactor 208 via subsystem 300 and via a final
integrated gas stream conduit 224. The final integrated gas stream
includes predetermined concentrations of CO.sub.2, COS, and
H.sub.2S that result from previous integrated gas streams (not
shown). Subsystem 300 is coupled in flow communication with reactor
208 via conduit 224, wherein the final integrated gas stream is
channeled to portions of reactor 208. The separation and removal of
CO.sub.2, COS, and H.sub.2S via subsystems 300 and 400 facilitates
producing a clean syngas stream (not shown) that is channeled to
gas turbine 114 via a clean syngas conduit 228.
[0021] In operation, air separation unit 202 receives air via
conduit 204. The air is separated into O.sub.2, N.sub.2 and other
components that are vented to atmosphere via a vent. The N.sub.2 is
channeled to turbine 114 via conduit 206 and the O.sub.2 is
channeled to gasification reactor 208 via conduit 210. Also, in
operation, slurry preparation system 211 receives coal and water
via conduits 212 and 213, respectively, forms a coal slurry stream
and channels the coal slurry stream to reactor 208 via conduit
214.
[0022] Reactor 208 receives O.sub.2 via conduit 210, coal via
conduit 214, and the final integrated gas stream from subsystem 300
via conduit 224. Reactor 208 produces a hot raw syngas stream that
is channeled to apparatus 144 via conduit 218. The slag by-product
formed in reactor 208 is removed via slag handling unit 215 and
conduits 216 and 217. Apparatus 144 facilitates cooling the hot raw
syngas stream to produce a cooled raw syngas stream that is
channeled to scrubber and LTGC unit 221 via conduit 219 wherein
particulate matter is removed from the syngas via fly ash conduit
222, the syngas is cooled further, and at least a portion of COS is
converted to H.sub.2S and CO.sub.2 via hydrolysis. The cooled raw
syngas stream is channeled to acid gas removal subsystem 300
wherein acid gas components are substantially removed to form a
clean syngas stream that is channeled to gas turbine 114 via
conduit 228.
[0023] Moreover, during operation, at least a portion of the acid
components removed from the syngas stream are channeled to
subsystem 400 via conduit 223, wherein the acid components are
removed and separated into at least a third gasification by-product
stream (not shown) that is removed from the syngas stream, such
that the final integrated gas stream is channeled to reactor 208
via subsystem 300 and conduit 224. In addition, turbine engine 110
receives N.sub.2 and clean syngas via conduits 206 and 228,
respectively. Turbine engine 110 combusts the syngas fuel, produces
hot combustion gases and channels hot combustion gases downstream
to induce rotation of turbine 114 which subsequently rotates first
generator 118 via rotor 120.
[0024] At least a portion of heat removed from the hot syngas via
heat transfer apparatus 144 is channeled to HRSG 142 via conduit
146 for use in boiling water to form steam. The steam is channeled
through steam turbine 132 via conduit 150 and induces rotation of
turbine 132, which powers second generator 134 via second rotor
136.
[0025] FIG. 2 is a schematic diagram of slurry preparation system
211. As described above, slurry preparation system 211 receives
coal (not shown) and water (not shown) via respective conduits 212
and 213. Conduit 212 is coupled to any coal supply (not shown) that
enables system 211 to operate as described herein. Conduit 213 is
coupled to any water supply (not shown) that enables system 211 to
operate as described herein. In the exemplary embodiment, makeup
water is channeled to slurry preparation system 211 at
approximately ambient temperature. Alternatively, makeup water
channeled to system 211 is heated to any temperature that enables
operation of system 211 as described herein.
[0026] In the exemplary embodiment, slurry preparation system 211
includes a mixing tank, or recycle solids tank 502. Recycle solids
tank 502 includes at least one mixing apparatus 504 and at least
one heating device 506 contained therein. In the exemplary
embodiment, mixing apparatus 504 is a motor-driven propeller-type
mixer, and heating device 506 is a low pressure steam heating
element coupled in flow communication with a low pressure (LP)
steam source 505, that, in the exemplary embodiment, is coupled to
HRSG 142 (shown in FIG. 1). Alternatively, mixing apparatus 504,
heating device 506, and LP steam source 505 are any apparatus,
device, and/or steam source, respectively, that enables operation
of system 211 as described herein. Heating device 506 preheats the
makeup water channeled into tank 502 via conduit 213.
[0027] Recycle solids tank 502 is coupled in flow communication
with portions of system 200 that include, but are not limited to,
acid gas removal subsystem 300 and sulfur reduction subsystem (both
shown in FIG. 1) via an acid gas removal (AGR) regeneration conduit
508. Conduit 508 channels gasification by-product materials (not
shown) that include, but are not limited to, caustic and
regeneration solids. In the exemplary embodiment, materials
channeled to tank 502 via conduit 508 are at a temperature that is
higher than the ambient temperature, and as such, gasification
by-product materials entering tank 502 via conduit 508 preheat the
makeup water channeled into tank 502 via conduit 213.
[0028] Recycle solids tank 502 is also coupled in flow
communication with a slag collection facility (not shown)
associated with slag handling unit 215 (shown in FIG. 1) via a slag
supply conduit 510. Slag supply conduit 510 channels gasification
by-product materials (not shown) that include, but are not limited
to, slag fines and other slag-type materials to tank 502 from a
slag sump (not shown) that collects fines and slag from slag
handling unit 215. In the exemplary embodiment, materials channeled
to tank 502 via conduit 510 are at a temperature that is greater
than ambient temperatures, therefore, such gasification by-product
materials entering tank 502 via conduit 510 preheat the makeup
water channeled into tank 502.
[0029] Recycle solids tank 502 is also coupled in flow
communication with a settling tank (not shown) associated with a
bottom portion (not shown) of gasification reactor 208 (shown in
FIG. 1) via a settler bottoms conduit 512. Settler bottoms conduit
512 channels gasification by-product materials (not shown) that
include, but are not limited to, reusable materials from the bottom
portion of gasification reactor 208. In the exemplary embodiment,
materials channeled to tank 502 via conduit 512 are at a
temperature that is higher than the ambient temperature, and as
such, gasification by-product materials entering tank 502 via
conduit 512 preheat the makeup water channeled into tank 502 via
conduit 213.
[0030] In the exemplary embodiment, each of the described heat
input mechanisms, including conduits 508, 510, and 512, and heating
device 506 preheats the water in recycle solids tank 502 to a range
of approximately 54.4 degrees Celsius (.degree. C.) (130 degrees
Fahrenheit (.degree. F.)) to approximately 76.6.degree. C.
(170.degree. F.), with a target median of approximately
65.6.degree. C. (150.degree. F.). Alternatively, the water in
recycle solids tank 502 may be heated to any temperature that
enables operation of system 211 as described herein. Such
gasification by-product materials as described herein are
collectively referred to herein as "entrained solids."
[0031] Also, in the exemplary embodiment, slurry preparation system
211 includes a recycle fluid transfer pump 514 that is coupled to
tank 502 via a tank discharge conduit 516. Pump 514 induces a
motive force on entrained solids and water within tank 502 to
enable such entrained solids and water to be channeled in a recycle
fluid stream (not shown) for use within other portions of system
211 via a recycle fluid transfer conduit 518.
[0032] Moreover, in the exemplary embodiment, slurry preparation
system 211 includes a first LP steam injection system 520 that is
coupled in flow communication with LP steam source 505.
Alternatively, any steam source may be used that enables operation
of system 211 as described herein. In the exemplary embodiment,
first LP steam injection system 520 includes a LP steam injection
device 522 that, in the exemplary embodiment is a LP steam
injection venturi 522 that is coupled in flow communication with a
first LP steam flow control device or valve 524. Alternatively, LP
steam injection device 522 is any injection device that enables
operation of system 211 as described herein. Valve 524 is coupled
in flow communication with LP steam source 505 and is coupled in
communication with a first temperature control sensor 526, wherein
sensor 526 generates and transmits signals (not shown) that are
representative of the temperatures of the preheated recycle fluid
stream downstream of injection device 522.
[0033] First LP steam injection system 520 channels LP steam into
the recycle fluid stream within conduit 518. In the exemplary
embodiment, the injected steam mixes and condenses within the
recycle fluid stream and downstream of system 520, thereby
preheating the recycle fluid stream with entrained solids to a
predetermined temperature range of approximately 71.1.degree. C.
(160.degree. F.) to approximately 93.3.degree. C. (200.degree. F.),
with a target median of approximately 82.2.degree. C. (180.degree.
F.). Alternatively, the recycle fluid stream may be preheated to
any temperature that enables operation of system 211 as described
herein.
[0034] In the exemplary embodiment, first temperature control
sensor 526 and first LP steam flow control valve 524 are coupled to
an extensive slurry temperature and viscosity control system (not
shown). Alternatively, first temperature control sensor 526 and
first LP steam flow control valve 524 use any control architecture
that enables system 211 to operate as described herein.
[0035] Further, in the exemplary embodiment, slurry preparation
system 211 includes a coal transfer apparatus 530 that includes a
coal storage bin 532 coupled in flow communication to the coal
supply via conduit 212. Coal storage bin 532 includes a plurality
of steam coils 534 that are coupled in flow communication with LP
steam source 505. Steam coils 534 preheat the coal in coal storage
bin 532 to any temperature that facilitates operation of system
211. Coal transfer apparatus 530 also includes a coal conveyor 536
that includes a coal flow control device 538 and a plurality of
steam coils 539 that are coupled in flow communication with LP
steam source 505. Steam coils 539 preheat the coal on coal conveyor
536 to any temperature that enables operation of system 211 as
described herein.
[0036] Coal flow control device 538 includes a speed control device
540 and a weight control device 542 that cooperate to control a
flow of coal on coal conveyor 536. In the exemplary embodiment,
coal flow control device 538 is coupled to a more extensive slurry
temperature and viscosity control system (not shown), and devices
540 and 542 generate and transmit signals (not shown) that are
representative of a speed of conveyor 536 and a weight of coal on
conveyor 536, respectively. Moreover, speed control device 540
facilitates automatic adjustment of speed of conveyor 536 as a
function of weight of coal on conveyor 536. For example, a decrease
in weight of coal on conveyor 536 causes an increase in speed of
conveyor 536 to maintain an approximately constant rate of coal
flow at a predetermined or operator-selected value. Alternatively,
coal flow control device 538, with or without speed control device
540 and/or weight control device 542, includes any control
architecture that enables system 211 to operate as described
herein. Coal flow control device 538 cooperates with coal conveyor
536 to generate a coal stream 544.
[0037] Moreover, in the exemplary embodiment, slurry preparation
system 211 includes a grinding mill 550. Grinding mill 550 includes
an intake conduit 552 that receives coal stream 544. Intake conduit
552 is coupled in flow communication with recycle fluid transfer
conduit 518 and receives the mixture of preheated recycle water
with entrained solids. Intake conduit 552 is also coupled in flow
communication with a second LP steam injection system 554 that is
coupled in flow communication with LP steam source 505.
[0038] Intake conduit 552 is further coupled in flow communication
with a slurry viscosity additive system 553. System 553 includes a
slurry viscosity additive source 555. System 553 also includes a
flow control device 557 coupled in flow communication with source
555 and intake conduit 552 via a slurry viscosity additive conduit
559. Flow control device 557 channels a predetermined amount of
slurry viscosity additive (not shown) into grinding mill 550.
[0039] In the exemplary embodiment, second LP steam injection
system 554 includes a second LP steam flow control device 556 that
is coupled in communication with a second temperature control
sensor 558. Also, in the exemplary embodiment, device 556 is a
second LP steam flow control valve 556. Alternatively, second LP
steam flow control device 556 is any flow control device that
enables operation of system 211 as described herein. Second LP
steam injection system 554 also includes a mill supply LP steam
conduit 560 that is coupled in flow communication with valve 556.
Second LP steam injection system 554 also includes a conduit 562
that is coupled in flow communication with conduit 560. In the
exemplary embodiment, conduit 562 is a flexible conduit, for
example, but not limited to, rubber hose. Alternatively, conduit
562 is a rigid conduit, for example, but not limited to, plastic.
Also, alternatively, conduit 562 is any device fabricated from any
material that enables operation of system 211 as described
herein.
[0040] Grinding mill 550 also includes a grinding device 564 that,
after receiving coal pieces from coal stream 544, grinds the coal
into smaller pieces within a predetermined size range. Grinding
mill 550 further includes a coal discharge port 566 that is coupled
in flow communication with grinding device 564.
[0041] In the exemplary embodiment, conduit 562 is positioned
within grinding mill 550 to enable LP steam to mix with the
preheated coal as it is ground by grinding device 564, and with the
preheated recycle fluid as it is mixed with the ground coal. Such
mixing facilitates increasing the mixing action of coal, fluid, and
steam, while reducing heat losses therefrom.
[0042] In the exemplary embodiment, slurry preparation system 211
includes a recycle fluid flow control sensor 568 that is coupled in
flow communication with recycle fluid transfer conduit 518 and to a
recycle fluid flow control device 570. Any recycle flow control
device such as a valve, enables system 211 to operate as described
herein may be used. Sensor 568 generates and transmits signals (not
shown) that are representative of a rate of flow of the preheated
recycle fluid stream entering grinding mill 550. Sensor 568 and
valve 570 cooperate to control a flow of preheated recycle water
and entrained solids into mill grinder 550.
[0043] Also, in the exemplary embodiment, slurry preparation system
211 includes a LP steam flow control sensor 572 that is coupled in
flow communication with mill supply LP steam conduit 560 and with
LP steam source 505. Sensor 572 generates and transmits signals
(not shown) that are representative of a rate of flow of LP steam
into grinding mill 550.
[0044] Further, in the exemplary embodiment, LP steam flow control
sensor 572 is coupled in communication with recycle fluid flow
control sensor 568, recycle fluid flow control valve 570, and coal
flow control device 538, including speed control device 540 and
weight control device 542. Sensor 572, sensor 568, valve 570, and
device 538 cooperate to control a flow of preheated recycle water
and entrained solids, steam, and coal entering mill grinder 550,
and thereby control a temperature, flow, and viscosity of the
slurry within mill grinder 550. Moreover, grinding mill 550 mixes
steam, ground coal, preheated recycle water and the associated
entrained solids to form a preheated slurry stream 574 that is
channeled from grinding mill 550 at a predetermined flow rate.
Further, sensor 572, sensor 568, valve 570, and device 538
cooperate to control temperature and viscosity of slurry stream
574. Also, the predetermined slurry viscosity additive channeled
into grinding mill 550 via slurry viscosity additive system 553,
and more specifically, flow control device 557, facilitates
decreasing a viscosity of stream 574 as a function of temperature.
Therefore, the additive, in conjunction with an increased
temperature of stream 574, facilitates an increase in a coal
content, or coal density, of stream 554.
[0045] Further, in the exemplary embodiment, slurry preparation
system 211 includes a mill discharge tank 576 that receives
preheated slurry stream 574 from grinding mill 550. Mill discharge
tank 576 includes a mixing apparatus 578 that functions similarly
to mixing apparatus 504. Second temperature control sensor 558 is
coupled with tank 576.
[0046] Sensor 558 cooperates with sensor 572, sensor 568, valve
570, device 538, and valve 556 to facilitate control of
temperature, rate of flow, and viscosity of preheated slurry stream
574. More specifically, sensor 558 transmits temperature feedback
signals (not shown) that are representative of a temperature of the
slurry within discharge tank 576. Therefore, in the exemplary
embodiment, sensor 558 facilitates control of steam flow into
grinding mill 550 via modulation of valve 556. Sensor 572 generates
and transmits a signal (not shown) to device 538 and valve 570 via
sensor 568 that is substantially representative of steam flow
through system 554 into grinding mill 550. Device 538 and valve 570
modulate a flow rate of coal stream 544 and recycle fluid stream
via conduit 518, respectively. Such modulation of flows of coal,
water, and steam facilitates reducing a potential for undue
dilution of slurry stream 574.
[0047] In the exemplary embodiment, the temperature range of
preheated slurry stream 574 is approximately 71.1.degree. C.
(160.degree. F.) to approximately 93.3.degree. C. (200.degree. F.),
with a target median of approximately 82.2.degree. C. (180.degree.
F.). Alternatively, preheated slurry stream 574 may be preheated to
any temperature that enables operation of system 211 as described
herein. Mixing apparatus 578 agitates the coal and recycle solids
within the water in mill discharge tank 576 to control of the
viscosity of preheated slurry stream 574 within tank 576.
[0048] In the exemplary embodiment, second temperature control
sensor 558, second LP steam flow control valve 556, recycle fluid
flow control sensor 568, recycle fluid flow control valve 570, coal
flow control device 538, including speed control device 540 and
weight control device 542, and LP steam flow control sensor 572 are
coupled to a more extensive control system (not shown).
Alternatively, sensor 558, valve 556, sensor 568, valve 570, device
538, and sensor 572 may use or be coupled to any control
architecture that enables system 211 to operate as described
herein.
[0049] Moreover, in the exemplary embodiment, slurry preparation
system 211 includes a mill discharge pump 580 that is coupled in
flow communication to mill discharge tank 576 via a slurry conduit
582. Slurry preparation system 211 also includes a slurry run tank
584 that is coupled in flow communication with mill discharge pump
580 via a slurry conduit 586. Mill discharge pump 580 channels
preheated slurry (not shown) from mill discharge tank 576 to slurry
run tank 584. Tank 584 includes a slurry flow control device 588
that facilitates flow control of preheated slurry into slurry run
tank 584. Slurry run tank 584 also includes a mixing apparatus 590
that functions similarly to mixing apparatus 504 and 578.
[0050] Also, in the exemplary embodiment, slurry preparation system
211 includes a slurry booster pump 592 that is coupled in flow
communication with slurry run tank 584 via a slurry conduit 594.
Further, slurry preparation system 211 includes a slurry charge
pump 596 that is coupled in flow communication with slurry booster
pump 592 via a slurry conduit 598. Slurry booster pump 592 channels
a preheated slurry stream (not shown) from slurry run tank 584 to
slurry charge pump 596. In the event that slurry run tank 584
cannot provide a sufficient net positive suction head (NPSH) to
slurry charge pump 596, because of elevated temperatures, for
example, i.e., lower densities, of the preheated slurry stream,
slurry booster pump 592 provides additional NPSH. Alternatively,
slurry preparation system 211 does not include a slurry booster
pump 592.
[0051] Further, in the exemplary embodiment, slurry preparation
system 211 includes a slurry recirculation conduit 600 that is
coupled in flow communication with conduit 598 and slurry run tank
584. Slurry recirculation conduit 600 enhances flow control of the
preheated slurry to slurry charge pump 596 by channeling excess
slurry back to tank 584. Slurry charge pump 596 channels the
preheated slurry stream into coal slurry conduit 214.
[0052] Moreover, in the exemplary embodiment, slurry preparation
system 211 includes a third LP steam injection system 602 that is
coupled in flow communication with LP steam source 505. In the
exemplary embodiment, third LP steam injection system 602 includes
an LP steam injection device 604 coupled in flow communication with
a third LP steam flow control device 606. In the exemplary
embodiment, device 604 is a steam injection venturi 604 and device
606 is a steam flow control valve 606. Alternatively, devices 604
and 606 are any respective injection devices and/or flow devices
that enable operation of system 211 as described herein.
[0053] Valve 606 is coupled in flow communication with LP steam
source 505 and with a third temperature control sensor 608, wherein
sensor 608 generates and transmits signals (not shown) that are
representative of temperatures of the preheated slurry in conduit
214 downstream of venturi 604. Third LP steam injection device 602
channels LP steam into the preheated slurry stream within conduit
214 and, as the injected steam mixes and condenses within the
preheated slurry stream downstream of device 602, facilitates
preheating the preheated slurry stream from a temperature range of
approximately 71.1.degree. C. (160.degree. F.) to approximately
93.3.degree. C. (200.degree. F.), with a target median of
approximately 82.2.degree. C. (180.degree. F.) to a temperature
range of approximately 126.7.degree. C. (260.degree. F.) to
approximately 148.9.degree. C. (300.degree. F.), with a target
median of approximately 137.7.degree. C. (280.degree. F.).
Alternatively, the preheated slurry stream is heated to any
temperature that enables operation of system 211 and gasification
reactor 208 (shown in FIG. 1) as described herein. In the exemplary
embodiment, third temperature control sensor 608 and third LP steam
flow control valve 606 are coupled to a more extensive slurry
temperature and viscosity control system (not shown).
[0054] Also, in the exemplary embodiment, mill discharge tank 576,
mill discharge pump 580, slurry run tank 584, slurry booster pump
592, slurry charge pump 596, and associated conduits 582, 586, 594,
598, and 214 are sufficiently insulated to facilitate maintaining a
temperature and viscosity of the slurry materials channeled
therein.
[0055] In operation, makeup water via water supply conduit 213 and
warm gasification by-products via AGR regeneration conduit 508,
slag supply conduit 510, and settler bottoms conduit 512, are
channeled into recycle solids tank 502. The make-up water and warm
gasification by-products are agitated and mixed by mixing apparatus
504 to form preheated water with suspended solids, or preheated
fluid. LP steam is channeled through heating device 506 to
facilitate heating the fluid to a temperature range of, in the
exemplary embodiment, approximately 54.4 degrees Celsius (.degree.
C.) (130 degrees Fahrenheit (.degree. F.)) to approximately
76.6.degree. C. (170.degree. F.), with a target median of
approximately 65.6.degree. C. (150.degree. F.).
[0056] Recycle fluid transfer pump 514 and tank discharge conduit
516 channel the fluid from tank 502 into recycle fluid transfer
conduit 518 to form a preheated recycle fluid stream. LP steam
injection system 520 injects LP steam into the recycle fluid stream
via LP steam injection venturi 522 and first LP steam flow control
valve 524. First temperature control sensor 526 generates and
transmits temperature feedback signals that are representative of
the temperatures of the preheated recycle fluid stream downstream
from injection device 522.
[0057] Coal that has been preheated within coal storage bin 532 is
channeled to coal conveyor 536, wherein the coal is further heated
by LP steam within steam coils 539. Preheated coal stream 544 is
channeled to grinding mill 550 and the preheated recycle fluid
stream is channeled into grinding mill 550 via conduit 518 and
recycle flow control valve 570. LP steam is then channeled into
grinding mill 550 via second LP steam flow control valve 556 and
conduit 562. Grinding mill 550 grinds the preheated coal into
smaller pieces (not shown) with grinding device 564 and mixes the
coal, steam, and preheated recycle fluid to form preheated slurry
stream 574. Stream 574 is channeled into mill discharge tank 576 to
facilitate mixing of the preheated slurry with mixing apparatus 578
and to facilitate controlling the viscosity of the preheated slurry
within tank 576.
[0058] Moreover, in operation, second temperature control sensor
558 indirectly cooperates with LP steam flow control sensor 572,
recycle fluid flow control sensor 568, recycle fluid flow control
valve 570, second LP steam flow control valve 556 and coal flow
control device 538, including speed control device 540 and weight
control device 542, to facilitate control of temperature, rate of
flow, and viscosity of preheated slurry stream 574. More
specifically, sensor 558 transmits temperature feedback signals
that are representative of a temperature of the preheated, mixed
slurry within discharge tank 576, such tank slurry temperature
being at least partially indicative of a temperature of preheated
slurry stream 574.
[0059] Also, in operation, speed control device 540 and weight
control device 542 cooperate to control a flow of coal on coal
conveyor 536. Devices 540 and 542 transmit signals that are
representative of a speed of conveyor 536 and weight of coal on
conveyor 536, respectively. Moreover, speed control device 540
enables automatic adjustments of the speed of conveyor 536 as a
function of weight of coal on conveyor 536.
[0060] Further, in operation, sensor 572 generates and transmits
signals that are representative of a rate of flow of LP steam into
grinding mill 550 to device 538 and valve 570 via sensor 568.
Furthermore, sensor 568 transmits signals that are representative
of a rate of flow of the preheated recycle fluid stream into
grinding mill 550. Sensor 568 and valve 570 cooperate to control a
flow of preheated recycle water and entrained solids into mill
grinder 550.
[0061] Moreover, in operation, device 538 and valve 570 modulate a
flow rate of coal stream 544 and preheated recycle fluid stream via
conduit 518, respectively, thereby controlling flow rate,
temperature, and viscosity of the slurry stream 574 channeled from
grinding mill 550. Such modulation of flows of coal, water, and
steam facilitates reducing a potential for undue dilution of slurry
stream 574. In the exemplary embodiment, temperature of preheated
slurry stream 574 is controlled to approximately 82.2.degree. C.
(180.degree. F.). Also, in operation, the preheated slurry is
channeled from mill discharge tank 576 to slurry run tank 584 via
mill discharge pump 580 and slurry conduits 582 and 586. Mixing
apparatus 590 agitates the preheated slurry to facilitate
recovering a potential for temperature and viscosity
stratification. Also, in operation, the preheated slurry is
channeled to gasification reactor 208 via slurry booster pump 592,
slurry charge pump 596, slurry conduits 594 and 598. Excess
preheated slurry may channel excess slurry back to tank 584 via
slurry recirculation conduit 600.
[0062] LP steam is injected into the preheated slurry channeled
into conduit 214 via LP steam injection venturi 604 and third LP
steam flow control valve 606. Third temperature control sensor 608
transmits signals that are representative of temperatures of the
preheated slurry in conduit 214 downstream of venturi 604. As the
injected steam mixes and condenses within the preheated slurry
stream downstream of device 602, the preheated slurry stream is
further heated.
[0063] A plurality of benefits are facilitated by injecting LP
steam into a coal slurry and its associated constituents. For
example, heating the slurry facilitates reducing oxygen consumption
associated with syngas production since less oxygen is needed to
combine with the fuel to attain a predetermined temperature.
Moreover, heating the slurry facilitates maintaining slurry
viscosity such that a spray pattern of the slurry within
gasification reactor 208 is enhanced. As such, a droplet
evaporation time is provided, while an efficiency of carbon
conversion therein is improved. Reducing the oxygen consumption and
improving the carbon conversion efficiency facilitates reducing
operational costs of IGCC power generation plant 100. Moreover,
such improvements in efficiency facilitates broadening a coal
envelope, that is, a range of coals that may be used within IGCC
power generation plant 100, including lower-cost coals.
[0064] FIG. 3 is a flow chart illustrating an exemplary method 700
of operating gasification system, and more specifically, exemplary
IGCC power generation plant 100 (shown in FIGS. 1 and 2). In the
exemplary embodiment, makeup water is preheated by channeling 702
steam through at least one heating device 506 (shown in FIG. 2)
immersed within mixing tank 502. Makeup water is further heated by
channeling 704 heated gasification by-product into recycle solids
tank 502 and by at least partially mixing the makeup water with the
heated gasification by-product. Makeup water is also further heated
by channeling 706 the at least partially mixed makeup water and
gasification by-product from recycle solids tank 502 to grinding
mill 550 (shown in FIG. 2) and by channeling steam into the makeup
water and the gasification by-product therebetween. At least a
portion of a carbonaceous fuel is preheated by channeling 708 LP
steam into coal transfer apparatus 530 (shown in FIG. 2), or more
specifically, channeling LP steam through at least a portion of
coal storage bin 532 (shown in FIG. 2) and by channeling LP steam
through at least a portion of coal conveyor 536 (shown in FIG.
2).
[0065] Also, in the exemplary embodiment, the carbonaceous fuel is
channeled 710 into grinding mill 550 via fuel flow control device
538 (shown in FIG. 2). The at least partially mixed preheated
makeup water and gasification by-product, are channeled 712 into
grinding mill 550 via recycle fluid flow control valve 570 (shown
in FIG. 2). The slurry viscosity additive is channeled 713 into
grinding mill 550 via flow control device 557 (shown in FIG. 2),
and steam is channeled 714 into grinding mill 550 via second LP
steam flow control valve 556 and conduit 562 (both shown in FIG.
2).
[0066] The carbonaceous fuel, preheated water, slurry viscosity
additive, and steam are mixed 716 within grinding mill 550, to form
preheated coal slurry stream 574 (shown in FIG. 2). Preheated coal
slurry stream 574 is discharged 718 from grinding mill 550 with at
least one of a predetermined slurry temperature and a predetermined
slurry viscosity. Preheated coal slurry stream 574 is further
heated 720 by channeling steam into preheated coal slurry stream
574.
[0067] Described herein are exemplary embodiments of methods and
apparatus that facilitate production of synthetic gas (syngas),
specifically, preheating a fuel slurry used to produce the syngas,
and more specifically, by injecting low pressure steam into the
fuel slurry and its associated constituents. Heating the fuel
slurry within predetermined temperature parameters facilitates
reducing oxygen consumption associated with syngas production, as
less oxygen is required to attain a predetermined temperature
within the gasification reactor. Moreover, heating the fuel slurry
facilitates maintaining a fuel slurry viscosity within
predetermined parameters that facilitates an improvement in a spray
pattern of the fuel slurry within the gasification reactor. Such
spray pattern improvement facilitates decreasing a droplet
evaporation time and improving an efficiency of carbon conversion
therein. Such reduction in oxygen consumption and improvement in
carbon conversion efficiency reducing lower operational costs
associated with syngas production. Moreover, such improvements in
efficiency facilitate broadening a coal envelope, that is, a range
of coals that may be used within any one gasification facility,
including lower-cost coals.
[0068] The methods and systems described herein are not limited to
the specific embodiments described herein. For example, components
of each system and/or steps of each method may be used and/or
practiced independently and separately from other components and/or
steps described herein. In addition, each component and/or step may
also be used and/or practiced with other assembly packages and
methods.
[0069] While the invention has been described in terms of various
specific embodiments, those skilled in the art will recognize that
the invention can be practiced with modification within the spirit
and scope of the claims.
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