{DESCRIPTION}
{Title of Invention}
POWER-GENERATION PLANT
{Technical Field}
5 {0001}
The present invention relates to a power-generation plant
provided with a gas turbine that uses low-calorific-value gas,
such as blast furnace gas (BFG) or the like, as fuel and to a
fuel-gas cooler that cools fuel gas pressurized at a fuel-gas
10 compressor and recirculated.
{Background Art}
{0002}
There is a known power-generation plant provided with a
gas turbine that uses low-calorific-value gas, such as blast
15 furnace gas (BFG) or the like, as fuel and a fuel-gas cooler
that cools fuel gas pressurized at a fuel-gas compressor
recirculated, for example, as disclosed in PTL 1.
{Citation List}
{Patent Literature}
20 {0003}
{PTL 1}
Japanese Unexamined Patent Application, Publication No. Hei 9-
79046
{0004}
25 In addition, there is a known fuel-gas cooler in which
2
fuel gas is cooled by spraying coolant from a spray nozzle;
the coolant, once it has been sprayed from the spray nozzle,
used to cool the fuel gas, and then dripped, is recovered with
a hopper; and the recovered coolant is recirculated.
5 {Summary of Invention}
{Technical Problem}
{0005}
However, low-calorific-value gas, such as blast furnace
gas (BFG) or the like, contains a large amount of
10 contaminants, and there is a problem in that the contaminants
may gradually be deposited at an outlet (bottom portion) of
the hopper, thus blocking the outlet of the hopper, and the
contaminants may be deposited inside a pipe that guides the
coolant accumulated in the hopper to a coolant pit or at an
15 outlet of the pipe, thus blocking the interior of the pipe or
the outlet of the pipe. There is also a problem in that, once
the outlet of the hopper, the interior of the pipe, or the
outlet of the pipe is blocked, it may become impossible to
recover the coolant that has been sprayed from the spray
20 nozzle, used to cool the fuel gas, and then dripped, with the
hopper alone; the coolant may overflow from the hopper and may
flow into a pipe (bypass line) that guides the fuel gas
pressurized at the fuel-gas compressor to the fuel-gas cooler
or a pipe (extraction line) that extracts the fuel gas from an
25 intermediate stage of the fuel-gas compressor to guide it to
3
the fuel-gas cooler; the coolant may flow into the fuel-gas
compressor and the gas turbine when the power-generation plant
is stopped; and thus, the fuel-gas compressor and the gas
turbine may be damaged.
5 {0006}
In addition, in cold regions, etc., in the case in which
the power-generation plant is in a stopped state and, in
addition, the outdoor temperature falls to 0 ºC or below, a
coolant pump is operated to spray the coolant from the spray
10 nozzle, thus circulating the coolant in order to prevent the
coolant used in the fuel-gas cooler from freezing. However,
there is a problem in that, if the coolant is sprayed into the
fuel-gas cooler when the power-generation plant is in the
stopped state (that is, a state in which high-temperature,
15 high-pressure fuel gas is not supplied (does not flow in)),
the interior of the fuel-gas cooler may immediately become
over-saturated; droplets may form everywhere in the fuel-gas
cooler, thus forming a body of liquid; the liquid may flow
into the fuel-gas compressor and the gas turbine by flowing in
20 reverse through the pipe (bypass line) that guides the fuel
gas pressurized at the fuel-gas compressor to the fuel-gas
cooler or the pipe (extraction line) that extracts the fuel
gas from the intermediate stage of the fuel-gas compressor to
guide it to the fuel-gas cooler; and thus, the fuel-gas
25 compressor and the gas turbine may be damaged.
4
{0007}
The present invention has been conceived in light of the
above-described circumstances, and an object thereof is to
provide a power-generation plant provided with a fuel-gas
5 cooler and a gas turbine, which is capable of preventing
coolant used in the fuel-gas cooler from flowing into a fuelgas
compressor and the gas turbine by flowing in reverse
through a pipe (bypass line) that guides fuel gas pressurized
at the fuel-gas compressor to the fuel-gas cooler or a pipe
10 (extraction line) that extracts the fuel gas from an
intermediate stage of the fuel-gas compressor to guide the
fuel gas to the fuel-gas cooler.
{Solution to Problem}
{0008}
15 The present invention employs the following solutions in
order to solve the above-described problems.
A power-generation plant according to the present
invention is a power-generation plant including a gas turbine
that combusts fuel gas; a fuel-gas cooler that cools the fuel
20 gas, which is pressurized at a fuel-gas compressor and
recirculated, with coolant sprayed from a spray nozzle; an
extraction line that guides the fuel gas extracted from an
intermediate stage of the fuel-gas compressor to the fuel-gas
cooler; a first level detector that detects whether a level of
25 the coolant accumulated at a bottom portion of the fuel-gas
5
cooler has reached a predetermined level; and a controller
that stops the gas turbine on the basis of a detection signal
sent from the first level detector and that outputs a command
signal for stopping a coolant pump that supplies the coolant
5 to the spray nozzle.
{0009}
With the power-generation plant according to the present
invention, when the first level detector detects that the
level of the coolant accumulated in the hopper has reached the
10 predetermined level (a level set at, for example, vertically
above (for example, 0 cm above the liquid surface of the
coolant accumulated in the hopper) a certain level maintained
by a U-shaped pipe and vertically below the bottom end of the
downstream end of the extraction line (for example, 0 cm below
15 the bottom end of the downstream end of the extraction line)),
the detection signal is output from the first level detector
to the controller, and, for example, the command signal is
output from the controller to an emergency shut-off valve that
blocks the supply of the fuel gas to the gas turbine. Then,
20 the emergency shut-off valve, when the command signal is input
thereto from the controller, is quickly closed (set to the
fully-closed state), thus blocking the supply of the fuel gas
to the gas turbine. At the same time, the controller outputs
the command signal to the coolant pump so that the coolant
25 pump is stopped, and, as a result, spraying of the coolant
6
from the spray nozzle is stopped.
Accordingly, the coolant used in the fuel-gas cooler can
be prevented from flowing into the fuel-gas compressor and the
gas turbine by flowing in reverse through the pipe (extraction
5 line) that extracts the fuel gas from the intermediate stage
of the fuel-gas compressor and guides the fuel gas to the
fuel-gas cooler.
{0010}
The above-described power-generation plant more
10 preferably includes a bypass line that guides the fuel gas,
which is pressurized at the fuel-gas compressor and
recirculated, to the fuel-gas cooler; a second level detector
that detects whether a level of the coolant accumulated in the
bypass line has reached a predetermined level; and a
15 controller that stops the gas turbine on the basis of a
detection signal sent from the second level detector and that
outputs a command signal for stopping the coolant pump that
supplies the coolant to the spray nozzle.
{0011}
20 With such a power-generation plant, when the second level
detector detects that the level of the coolant accumulated in
the bypass line has reached the predetermined level (a level
set at, for example, 10 cm above the bottom end of the inner
circumferential surface of the gas inlet pipe), the detection
25 signal is output from the second level detector to the
7
controller, and, for example, the command signal is output
from the controller to an emergency shut-off valve that blocks
the supply of the fuel gas to the gas turbine. Then, the
emergency shut-off valve, when the command signal is input
5 thereto from the controller, is quickly closed (set to the
fully-closed state), thus blocking the supply of the fuel gas
to the gas turbine. At the same time, the controller outputs
the command signal to a coolant pump so that the coolant pump
is stopped, and, as a result, spraying of the coolant from the
10 spray nozzle is stopped.
Accordingly, the coolant used in the fuel-gas cooler can
be prevented from flowing into the fuel-gas compressor and the
gas turbine by flowing in reverse through the pipe (bypass
line) that guides the fuel gas pressurized at the fuel-gas
15 compressor to the fuel-gas cooler.
{0012}
A power-generation plant according to the present
invention is a power-generation plant including a gas turbine
that combusts fuel gas; a fuel-gas cooler that cools the fuel
20 gas, which is pressurized at a fuel-gas compressor and
recirculated, with coolant sprayed from a spray nozzle; and a
bypass line that guides the fuel gas, which is pressurized at
the fuel-gas compressor and recirculated, to the fuel-gas
cooler; a level detector that detects whether a level of the
25 coolant accumulated in the bypass line has reached a
8
predetermined level; and a controller that stops the gas
turbine on the basis of a detection signal sent from the level
detector and that outputs a command signal for stopping a
coolant pump that supplies the coolant to the spray nozzle.
5 {0013}
With the power-generation plant according to the present
invention, when the level detector detects that the level of
the coolant accumulated in the bypass line has reached the
predetermined level (a level set at, for example, 10 cm above
10 the bottom end of the inner circumferential surface of the gas
inlet pipe), the detection signal is output from the level
detector to the controller, and, for example, the command
signal is output from the controller to an emergency shut-off
valve that blocks the supply of the fuel gas to the gas
15 turbine. Then, the emergency shut-off valve, when the command
signal is input thereto from the controller, is quickly closed
(set to the fully-closed state), thus blocking the supply of
the fuel gas to the gas turbine. At the same time, the
controller outputs the command signal to a coolant pump so
20 that the coolant pump is stopped, and, as a result, spraying
of the coolant from the spray nozzle is stopped.
Accordingly, the coolant used in the fuel-gas cooler can
be prevented from flowing into the fuel-gas compressor and the
gas turbine by flowing in reverse through the pipe (bypass
25 line) that guides the fuel gas pressurized at the fuel-gas
9
compressor to the fuel-gas cooler.
{0014}
In the above-described power-generation plant, it is more
preferable that a coolant pipe that supplies the coolant to
5 the spray nozzle be provided, wherein the coolant pipe is
provided with a bypass pipe that returns the coolant to the
interior of the fuel-gas cooler by bypassing the spray nozzle.
{0015}
With such a power-generation plant, even in the case in
10 which, in cold regions, etc., the power-generation plant is in
a stopped state and, in addition, the outdoor temperature
falls to 0 ºC or below, the coolant pump is operated without
spraying the coolant from the spray nozzle, and thus, the
coolant is circulated.
15 Accordingly, the coolant used in the fuel-gas cooler can
be prevented from freezing, and the occurrence of droplets in
the fuel-gas cooler can be prevented.
In addition, by suppressing the occurrence of droplets in
the fuel-gas cooler, the coolant can be prevented from flowing
20 into the fuel-gas compressor and the gas turbine by flowing in
reverse through the pipe (bypass line) that guides the fuel
gas pressurized at the fuel-gas compressor to the fuel-gas
cooler or the pipe (extraction line) that extracts the fuel
gas from the intermediate stage of the fuel-gas compressor and
25 guides it to the fuel-gas cooler.
10
{0016}
In the above-described power-generation plant, it is more
preferable that a pipe leading to the spray nozzle be provided
with a pressure detector for detecting the pressure of the
5 coolant that passes through the pipe.
{0017}
With such a power-generation plant, it is possible to
easily ascertain whether or not the coolant is flowing through
the pipe leading to the spray nozzle, that is, whether the
10 coolant is supplied to the spray nozzle or the coolant is
supplied to the bypass pipe, and it is possible to prevent
forgetting to switch the three-way valve from the spray nozzle
side to the bypass pipe side or from the bypass pipe side to
the spray nozzle side.
15 {0018}
A power-generation plant according to the present
invention is a power-generation plant including a gas turbine
that combusts fuel gas; a fuel-gas cooler that cools the fuel
gas, which is pressurized at a fuel-gas compressor and
20 recirculated, with coolant sprayed from a spray nozzle; and a
coolant pipe that supplies the coolant to the spray nozzle,
wherein the coolant pipe is provided with a bypass pipe that
returns the coolant to the interior of the fuel-gas cooler by
bypassing the spray nozzle.
25 {0019}
11
With the power-generation plant according to the present
invention, even in the case in which, in cold regions, etc.,
the power-generation plant is in a stopped state and, in
addition, the outdoor temperature falls to 0 ºC or below, the
5 coolant pump is operated without spraying the coolant from the
spray nozzle, and thus, the coolant is circulated.
Accordingly, the coolant used in the fuel-gas cooler can
be prevented from freezing, and the occurrence of droplets in
the fuel-gas cooler can be prevented.
10 In addition, by suppressing the occurrence of droplets in
the fuel-gas cooler, the coolant can be prevented from flowing
into the fuel-gas compressor and the gas turbine by flowing in
reverse through the pipe (bypass line) that guides the fuel
gas pressurized at the fuel-gas compressor to the fuel-gas
15 cooler or the pipe (extraction line) that extracts the fuel
gas from the intermediate stage of the fuel-gas compressor and
guides it to the fuel-gas cooler.
{0020}
In the above-described power-generation plant, it is more
20 preferable that a pipe leading to the spray nozzle be provided
with a pressure detector for detecting the pressure of the
coolant that passes through the pipe.
{0021}
With such a power-generation plant, it is possible to
25 easily ascertain whether or not the coolant is flowing through
12
the pipe leading to the spray nozzle, that is, whether the
coolant is supplied to the spray nozzle or the coolant is
supplied to the bypass pipe, and it is possible to prevent
forgetting to switch the three-way valve from the spray nozzle
5 side to the bypass pipe side or from the bypass pipe side to
the spray nozzle side.
{0022}
A method of stopping a power-generation plant according
to the present invention is a method of stopping a power10
generation plant including a gas turbine that combusts fuel
gas, a fuel-gas cooler that cools the fuel gas, which is
pressurized at a fuel-gas compressor and recirculated, with
coolant sprayed from a spray nozzle, and an extraction line
that guides the fuel gas extracted from an intermediate stage
15 of the fuel-gas compressor to the fuel-gas cooler, the method
including stopping the gas turbine when a level of the coolant
accumulated at a bottom portion of the fuel-gas cooler has
reached a predetermined level; and stopping a coolant pump,
which supplies the coolant to the spray nozzle.
20 {0023}
With the method of stopping a power-generation plant
according to the present invention, when the level of the
coolant accumulated in the hopper has reached the
predetermined level (a level set at, for example, vertically
25 above a certain level maintained by a U-shaped pipe (for
13
example, 0 cm above the water surface of the coolant
accumulated in the hopper) and vertically below the bottom end
of the downstream end of the extraction line (for example, 0
cm below the bottom end of the downstream end of the
5 extraction line)), an emergency shut-off valve that blocks the
supply of the fuel gas to the gas turbine is quickly closed
(set to the fully-closed state), thus blocking the supply of
the fuel gas to the gas turbine. At the same time, the
coolant pump is stopped, and, as a result, spraying of the
10 coolant from the spray nozzle is stopped.
Accordingly, the coolant used in the fuel-gas cooler can
be prevented from flowing into the fuel-gas compressor and the
gas turbine by flowing in reverse through the pipe (extraction
line) that extracts the fuel gas from the intermediate stage
15 of the fuel-gas compressor and guides it to the fuel-gas
cooler.
{0024}
The above-described method of stopping a power-generation
plant more preferably includes stopping the gas turbine when a
20 level of the coolant accumulated in a bypass line that guides
the fuel gas, which is pressurized at the fuel-gas compressor
and recirculated, to the fuel-gas cooler has reached a
predetermined level; and stopping the coolant pump, which
supplies the coolant to the spray nozzle.
25 {0025}
14
With such a method of stopping a power-generation plant,
when the level of the coolant accumulated in the bypass line
has reached the predetermined level (a level set at, for
example, 10 cm above the bottom end of the inner
5 circumferential surface of the gas inlet pipe), for example,
an emergency shut-off valve that blocks the supply of the fuel
gas to the gas turbine is quickly closed (set to the fullyclosed
state), thus blocking the supply of the fuel gas to the
gas turbine. At the same time, the coolant pump is stopped,
10 and, as a result, spraying of the coolant from the spray
nozzle is stopped.
Accordingly, the coolant used in the fuel-gas cooler can
be prevented from flowing into the fuel-gas compressor and the
gas turbine by flowing in reverse through the pipe (bypass
15 line) that guides the fuel gas pressurized at the fuel-gas
compressor to the fuel-gas cooler.
{0026}
A method of stopping a power-generation plant according
to the present invention is a method of stopping a power20
generation plant including a gas turbine that combusts fuel
gas, a fuel-gas cooler that cools the fuel gas, which is
pressurized at a fuel-gas compressor and recirculated, with
coolant sprayed from a spray nozzle, and a bypass line that
guides the fuel gas, which is pressurized at the fuel-gas
25 compressor and recirculated, to the fuel-gas cooler, the
15
method including stopping the gas turbine when a level of the
coolant accumulated in the bypass line has reached a
predetermined level; and stopping a coolant pump that supplies
the coolant to the spray nozzle.
5 {0027}
With the method of stopping a power-generation plant
according to the present invention, when the level of the
coolant accumulated in the bypass line has reached the
predetermined level (a level set at, for example, 10 cm above
10 the bottom end of the inner circumferential surface of the gas
inlet pipe), for example, an emergency shut-off valve that
blocks the supply of the fuel gas to the gas turbine is
quickly closed (set to the fully-closed state), thus blocking
the supply of the fuel gas to the gas turbine. At the same
15 time, the coolant pump is stopped, and, as a result, spraying
of the coolant from the spray nozzle is stopped.
Accordingly, the coolant used in the fuel-gas cooler can
be prevented from flowing into the fuel-gas compressor and the
gas turbine by flowing in reverse through the pipe (bypass
20 line) that guides the fuel gas pressurized at the fuel-gas
compressor to the fuel-gas cooler.
{Advantageous Effects of Invention}
{0028}
A power-generation plant according to the present
25 invention affords an advantage in that coolant used in a fuel16
gas cooler can be prevented from flowing into a fuel-gas
compressor and a gas turbine by flowing in reverse through a
pipe (bypass line) that guides fuel gas pressurized at the
fuel-gas compressor to the fuel-gas cooler or a pipe
5 (extraction line) that extracts the fuel gas from an
intermediate stage of the fuel-gas compressor to guide it to
the fuel-gas cooler.
{Brief Description of Drawings}
{0029}
10 {FIG. 1} Fig. 1 is a diagram showing, in outline, the
configuration of a power-generation plant according to a first
embodiment of the present invention.
{FIG. 2} Fig. 2 is diagram showing, in outline, the
configuration of a power-generation plant according to a
15 second embodiment of the present invention.
{FIG. 3} Fig. 3 is diagram showing, in outline, the
configuration of a power-generation plant according to a third
embodiment of the present invention.
{Description of Embodiments}
20 {0030}
{First Embodiment}
A power-generation plant according to a first embodiment
of the present invention will be described below with
reference to Fig. 1.
25 Fig. 1 is a diagram showing, in outline, the
17
configuration of a power-generation plant according to this
embodiment.
{0031}
As shown in Fig. 1, a power-generation plant 10 according
5 to this embodiment is provided with a gas turbine 11, a BFG
compressor 12, which is a fuel-gas compressor, a generator
(not shown), a fuel-gas cooler (hereinafter, referred to as
"gas cooler") 13, a BFG (blast furnace gas) supply system 14,
and a COG (coke oven gas) supply system (not shown).
10 The gas turbine 11 is provided with an air compressor 15
and (gas-turbine) combustor 16, and a turbine 17. In
addition, the gas turbine 11, the BFG compressor 12, and the
generator are linked via a decelerating mechanism (not shown),
and thus, when the gas turbine 11 is rotated, the BFG
15 compressor 12 and the generator are also rotated.
{0032}
The BFG supply system 14 is a fuel supply line that
guides BFG (low-calorific-value fuel) to a gas nozzle (not
shown) that forms a combustor 16; the COG supply system is a
20 fuel supply line that guides COG (high-calorific-value fuel)
to a pilot nozzle (not shown) that forms the combustor 16; and
the BFG supply system 14 and the COG supply system are
connected to the combustor 16 at the downstream ends thereof.
{0033}
25 The BFG supply system 14 is provided with an upstream
18
line 12 that guides BFG generated in a blast furnace (not
shown) to the BFG compressor 12; a downstream line 22 that
guides the BFG that has been compressed at the BFG compressor
12 (sent out (expelled) from the BFG compressor 12) to a gas
5 nozzle; a bypass line 23 that communicates between an
intermediate portion of the upstream line 21 and an
intermediate portion of the downstream line 22, and that
returns the BFG passing through the downstream line 22 to the
upstream line 21 as needed; and an extraction line 24 that
10 guides the BFG removed (extracted) from an intermediate stage
of the BFG compressor 12 to the gas cooler 13.
{0034}
A mixer (not shown), which mixes the BFG guided thereto
from the blast furnace with cooling N2 and/or heating COG so
15 as to adjust the heat (caloric value) of the BFG to an
appropriate level, and a dust collector (for example,
electrostatic precipitator) 25, which separates/removes
microparticles, such as dust or the like, from the BFG guided
from the mixer toward the BFG compressor 12, are provided at
20 intermediate portions of the upstream line 21.
In addition, a shut-off valve 26 and an emergency shutoff
valve 27 are provided in intermediate portions of the
downstream line 22.
{0035}
25 A bypass valve (flow-rate adjusting valve) 28, which
19
adjusts the flow rate of the BFG returned (extracted) from the
intermediate portion of the downstream line 22 to the
intermediate portion of the upstream line 21 located between
the mixer and the dust collector 25, and a gas cooler 13
5 provided downstream of the bypass valve 28 to cool the BFG,
which is returned (extracted) from the intermediate portion of
the downstream line 22 to the intermediate portion of the
upstream line 21 located between the mixer and the dust
collector 25, are provided at intermediate portions of the
10 bypass line 23.
{0036}
The downstream end (outlet end) of the extraction line 24
is connected to a center portion of a drum section 41 located
below spray nozzles 45, described later, and above the top end
15 of a hopper 38; the BFG that has flowed out from the
downstream end (outlet end) of the extraction line 24 is
horizontally sprayed out toward a longitudinal axis (center
axis) of the gas cooler 13; and thus, the BFG flows into the
gas cooler 13. In addition, an extraction valve (flow-rate
20 adjusting valve) 29 that adjusts flow rate of the BFG removed
(extracted) from the intermediate stage of the BFG compressor
12 is provided at an intermediate portion of the extraction
line 24.
{0037}
25 The gas cooler 13 is provided with a casing 31, a gas
20
inlet pipe 32, the hopper 38, and a diffuser 39.
The casing 31 is provided with the drum section 41 that
has a substantially cylindrical shape extending in the
vertical direction and a top portion 42 that has a
5 substantially circular cone shape continuously connected with
the drum section 41. A gas outlet 43 is provided at a center
portion of the top portion 42, and the bypass line 23 is
connected to the gas outlet 43.
{0038}
10 The gas inlet pipe 32 is bent from the horizontal
direction to the vertical direction directly below the gas
cooler 13, and the diffuser 39 for preventing the coolant from
directly flowing in from spray nozzles 44 and the spray
nozzles 45 is provided at a gas outlet of the gas inlet pipe
15 32.
{0039}
The diffuser 39 has an umbrella-like shape that is
inclined downward from the center toward the edge so as to
cover the gas outlet of the gas inlet pipe 32. Because the
20 coolant sprayed from the spray nozzles 44 and 45 is blocked by
the diffuser 39, the coolant does not directly flow into the
gas outlet of the gas inlet pipe 32. The coolant sprayed on
the diffuser 39 flows over the top surface of the diffuser 39,
which serves as a roof, thus flowing into the hopper 38.
25 {0040}
21
The BFG that has flowed out from the gas outlet of the
gas inlet pipe 32 is gradually depressurized while passing
through an internal space of the drum section 41 from the
diffuser 39, and is returned to the intermediate portion of
5 the upstream line 21 by passing through the bypass line 23
after being guided to the gas outlet 43 along an inner wall
surface (roof surface) of the top portion 42 are.
{0041}
In the internal space of the drum section 41, a plurality
10 of spray nozzles 44 are disposed in the form of a ring along a
circumferential direction of the drum section 41 and a
plurality of spray nozzles 45 are disposed in the form of a
ring along the circumferential direction of the drum section
41. The spray nozzles 44 are disposed closer to the gas
15 outlet 43 than the spray nozzles 45.
{0042}
A coolant supply pipe 51 is a pipe for individually
guiding the coolant to the plurality of spray nozzles 44 and
the plurality of spray nozzles 45. The BFG passing through
20 the drum section 41 is cooled first by liquid sprayed from the
spray nozzles 45 in the form of a mist via a second branch
pipe 48, moves toward the gas outlet 43, and is then cooled
further by liquid sprayed from the spray nozzles 44 in the
form of a mist via a first branch pipe 47. In addition, a
25 coolant pump 53 and a cooler 54 are provided at intermediate
22
portions of the coolant supply pipe 51 closer to an upstream
side.
{0043}
The hopper 38 is disposed at a lower potion (bottom
5 portion) of the drum section 41 along the longitudinal axis
(center axis) of the gas cooler 13 and vertically below the
diffuser 39; is a funnel-like member having a substantially
circular cone shape whose diameter gradually decreases from
one end (top end) to the other end (bottom end); recovers the
10 coolant that has been sprayed from the spray nozzles 44 and
45, used to cool the BFG, and then dripped; and accumulates
the coolant to a certain level. In addition, a coolant return
pipe 55 that (naturally) returns, of the coolant accumulated
in the hopper 38, the coolant that exceeds the certain level
15 to a coolant pit 52 is provided at a bottom portion of the
hopper 38.
{0044}
Note that a U-shaped tube 55a provided at the most
upstream portion of the coolant return pipe 55 (naturally)
20 maintains the level of the coolant that accumulates in the
hopper 38 at the certain level.
In addition, with the coolant accumulated in the U-shaped
tube 55a, the interior of the gas cooler 13, the interior of
the coolant return pipe 55 located downstream of the U-shaped
25 pipe 55a, and the interior of the coolant pit 52 are
23
partitioned (water sealed) so that the BFG that passes through
the gas cooler 13 is prevented from flowing into the coolant
pit 52 and the coolant return pipe 55 located downstream of
the U-shaped pipe 55a.
5 {0045}
The gas cooler 13 according to this embodiment is
provided with a (first) level detector (level gauge) 61 that
detects the level of the coolant accumulated in the hopper 38
when it reaches a predetermined level, which is set above the
10 certain level in the vertical direction (for example, 0 cm
above the water surface of the coolant accumulated in the
hopper 38) and also vertically below the bottom end of the
downstream end of the extraction line 24 (for example, 0 cm
below the bottom end of the downstream end of the extraction
15 line 24).
In addition, when the level detector 61 detects that the
level of the coolant in the hopper 38 has reached the
predetermined level set vertically above the certain level, a
detection signal is output to a controller (not shown) from
20 the level detector 61, and the controller outputs a command
signal to the emergency shut-off valve 27. Then, the
emergency shut-off valve 27, when the command signal is input
thereto from the controller, is quickly closed (set to the
fully-closed state) so as to block the supply of the BFG to
25 the combustor 16. At the same time, the controller also
24
outputs a command signal to an emergency shut-off valve (not
shown) provided in the COG supply system. Then, the emergency
shut-off valve, when the command signal is input thereto from
the controller, is quickly closed (set to the fully-closed
5 state) so that the supply of the COG to the combustor 16 is
also blocked. As a result, the supply of fuel (BFG and COG)
to the combustor 16 is blocked so that the gas turbine 11 is
tripped (set to an emergency stop).
{0046}
10 Furthermore, when the controller outputs the command
signals to the emergency shut-off valve 27 provided in the BFG
supply system 14 and the emergency shut-off valve (not shown)
provided in the COG supply system, the controller
simultaneously outputs a command signal also to the coolant
15 pump 53 so that the coolant pump 53 is stopped. As a result,
the supply of the coolant to the coolant supply pipe 51 is
stopped so that spraying of the coolant from the spray nozzles
44 and 45 is stopped.
{0047}
20 With the power-generation plant 10 according to this
embodiment, when the level detector 61 detects that the level
of the coolant accumulated in the hopper 38 has reached the
predetermined level (a level set at, for example, vertically
above (for example, 0 cm above the liquid surface of the
25 coolant accumulated in the hopper 38) the certain level
25
maintained by the U-shaped pipe 55a and vertically below the
bottom end of the downstream end of the extraction line 24
(for example, 0 cm below the bottom end of the downstream end
of the extraction line 24)), the detection signal is output
5 from the level detector 61 to the controller, and the command
signal is output from the controller to the emergency shut-off
valve 27 that blocks the supply of the fuel gas to the gas
turbine 11. Then, the emergency shut-off valve 27, when the
command signal is input there to from the controller, is
10 quickly closed (set to the fully-closed state), thus blocking
the supply of the fuel gas to the gas turbine 11. At the same
time, the controller also outputs the command signal to the
coolant pump 53 so that the coolant pump 53 is stopped, and,
as a result, spraying of the coolant from the spray nozzles
15 and 44 and 45 is stopped.
Accordingly, the coolant used in the gas cooler 13 can be
prevented from flowing into the gas compressor 12 and the gas
turbine 11 by flowing in reverse through the extraction line
24 that extracts the fuel gas from the intermediate stage of
20 the gas compressor 12 and guides the fuel gas to the gas
cooler 13.
{0048}
{Second Embodiment}
A power-generation plant according to a second embodiment
25 of the present invention will be described below with
26
reference to Fig. 2.
Fig. 2 is a diagram showing, in outline, the
configuration of a power-generation plant according to this
embodiment.
5 {0049}
As shown in Fig. 2, a gas cooler 13 according to this
embodiment differs from that of the first embodiment described
above in that a (second) level detector (level gauge) 62 is
provided instead of the (first) level detector (level gauge)
10 61. Because other constituent components are the same as
those in the first embodiment described above, descriptions of
those constituent components will be omitted herein.
Note that the same reference signs are given to members
that are the same as those in the above-described first
15 embodiment.
{0050}
The gas cooler 13 according to this embodiment is
provided with the (second) level detector (level gauge) 62
that, in the case in which the coolant has accumulated inside
20 the gas inlet pipe 32, detects that the level thereof has
reached a predetermined level (which is set, for example, 0 cm
above a bottom end of an inner circumferential surface of the
gas inlet pipe 32).
In addition, in this embodiment, when the level detector
25 62 detects that the level of the coolant accumulated in the
27
gas inlet pipe 32 has reached the predetermined level (which
is set, for example, 10 cm above the bottom end of the inner
circumferential surface of the gas inlet pipe 32), the level
detector 62 outputs a detection signal to a controller (not
5 shown), and the controller outputs a command signal to the
emergency shut-off valve 27. Then, the emergency shut-off
valve 27, when the command signal is input thereto from the
controller, is quickly closed (set to the fully-closed state),
thus blocking the supply of the BFG to the combustor 16. At
10 the same time, the controller also outputs the command signal
to the emergency shut-off valve (not shown) provided in the
COG supply system. Then, the emergency shut-off valve, when
the command signal is input thereto from the controller, is
quickly closed (set to the fully-closed state), thus blocking
15 the supply of the COG to the combustor 16. As a result, the
supply of fuel (BFG and COG) to the combustor 16 is blocked so
that the gas turbine 11 is tripped (set to an emergency stop).
{0051}
Furthermore, when the controller outputs the command
20 signals to the emergency shut-off valve 27 provided in the BFG
supply system 14 and the emergency shut-off valve (not shown)
provided in the COG supply system, the controller
simultaneously outputs the command signal also to the coolant
pump 53 so that the coolant pump 53 is stopped. As a result,
25 the supply of the coolant to the coolant supply pipe 51 is
28
stopped so that spraying of the coolant from the spray nozzles
44 and 45 is stopped.
{0052}
With the power-generation plant 10 according to this
5 embodiment, when the level detector 62 detects that the level
of the coolant accumulated in the gas inlet pipe 32 has
reached the predetermined level (a level set at, for example,
10 cm above the bottom end of the inner circumferential
surface of the gas inlet pipe 32), the detection signal is
10 output from the level detector 62 to the controller, and the
command signal is output from the controller to the emergency
shut-off valve 27 that blocks the supply of the fuel gas to
the gas turbine 11. Then, the emergency shut-off valve 27,
when the command signal is input thereto from the controller,
15 is quickly closed (set to the fully-closed state), thus
blocking the supply of the fuel gas to the gas turbine 11. At
the same time, the controller also outputs the command signal
to the coolant pump 53 so that the coolant pump 53 is stopped,
and, as a result, spraying of the coolant from the spray
20 nozzles and 44 and 45 is stopped.
Accordingly, the coolant used in the gas cooler 13 can be
prevented from flowing into the gas compressor 12 and the gas
turbine 11 by flowing in reverse through the bypass line 23
that guides the fuel gas pressurized at the gas compressor 12
25 to the gas cooler 13.
29
{0053}
{Third Embodiment}
A power-generation plant according to a third embodiment
of the present invention will be described below with
5 reference to Fig. 3.
Fig. 3 is a diagram showing, in outline, the
configuration of a power-generation plant according to this
embodiment.
{0054}
10 As shown in Fig. 3, a gas cooler 13 according to this
embodiment differs from those of the embodiments described
above in that a coolant pipe 36 that includes a bypass pipe 63
is provided and that the (first) level detector (level gauge)
61 and the (second) level detector (level gauge) 62 are
15 omitted. Because other constituent components are the same as
those in the embodiments described above, descriptions of
those constituent components will be omitted herein.
Note that the same reference signs are given to members
that are the same as those in the above-described embodiments.
20 {0055}
The coolant pipe 36 of the gas cooler 13 according to
this embodiment is provided with the bypass pipe 63 that
returns the coolant to the hopper 38 without passing it
through the first branch pipe 47 and the second branch pipe 48
25 (that is, so that the coolant is not sprayed from the spray
30
nozzles 44 and 45).
An upstream end (inlet end) of the bypass pipe 63 is
connected, via a three-way valve 64, to a main pipe 46 located
upstream of a position where an upstream end (inlet end) of
5 the first branch pipe 47 is connected, and an orifice 65,
which causes (generates) the same level of pipe resistance as
when the coolant is sprayed from the spray nozzles 44 and 45,
is provided at an intermediate portion of the bypass pipe 63.
In addition, a downstream end (outlet end) of the bypass pipe
10 63 is connected to a center portion of the drum section 41
located below the spray nozzles 45 and above the downstream
end (outlet end) of the extraction line 24, and the coolant
that has flowed out from the downstream end (outlet end) of
the bypass pipe 63 is horizontally expelled toward the
15 longitudinal axis (center axis) of the gas cooler 13 so as to
flow into the gas cooler 13 and is subsequently accumulated in
the hopper 38. Specifically, the coolant circulates in the
following order: the coolant pit 52 → the coolant supply pipe
51 → the coolant pump 53 → the coolant supply pipe 51 → the
20 cooler 54 → the cooler supply pipe 51 → the main pipe 46 → the
bypass pipe 63 → the hopper 38 → the U-shaped pipe 55a → the
coolant return pipe 55 → the coolant pit 52.
{0056}
With the power-generation plant 10 according to this
25 embodiment, even in the case in which, in cold regions, etc.,
31
the power-generation plant 10 is in a stopped state and the
outdoor temperature reaches 0ºC or below, the coolant pump 53
is operated without spraying the coolant from the spray
nozzles 44 and 45, and thus, the coolant is circulated.
5 Accordingly, the coolant used in the gas cooler 13 can be
prevented from freezing while suppressing the occurrence of
droplets in the gas cooler 13.
In addition, by suppressing the occurrence of droplets in
the gas cooler 13, the coolant can be prevented from flowing
10 into the gas compressor 12 and the gas turbine 11 by flowing
in reverse through the bypass line 23 that guides the fuel gas
pressurized at the gas compressor 12 to the gas cooler 13 or
the extraction line 24 that extracts the fuel gas from the
intermediate stage of the gas compressor 12 and guides it to
15 the gas cooler 13.
{0057}
Note that, in this embodiment, it is more preferable that
the first branch 47 and the second branch pipe 48 be
individually provided with pressure detectors 66 that detect
20 the pressure of the coolant that passes through the pipes.
By doing so, it is possible to easily ascertain whether
or not the coolant is flowing through the first branch pipe 47
and the second branch pipe 48, that is, which side the threeway
vale 64 is switched (set) to (whether the three-way valve
25 64 is set to a side that supplies the coolant to the spray
32
nozzles 44 and 45 or to a side that makes the coolant
circulate via the bypass pipe 63), and it is possible to
prevent the three-way valve 64 from accidentally being left
unswitched.
5 {0058}
Note that the present invention is not limited to the
embodiments described above, and appropriate
modifications/alterations are possible as needed.
For example, the first embodiment and the second
10 embodiment described above may be combined, or the second
embodiment and the third embodiment described above may be
combined, and, in addition, the first embodiment to the third
embodiment may all be combined.
{0059}
15 In addition, although the embodiments described above
have been described with COG (coke oven gas) as a concrete
example of high-calorific value fuel and BFG (blast furnace
gas) as a concrete example of low-calorific-value fuel, the
types of fuel may be fuel other than COG (coke oven gas) and
20 BFG (blast furnace gas), for example, process gases that are
by-products produced from various plants (such as LDG (Linz-
Donawitz converter gas), MXG (mixed by-product gas), and so
forth).
{Reference Signs List}
25 {0060}
33
10 power-generation plant
11 gas turbine
12 BFG compressor (fuel-gas compressor)
13 (fuel) gas cooler
5 23 bypass line
24 extraction line
44 spray nozzle
45 spray nozzle
53 coolant pump
10 61 (first) level detector
62 (second) level detector
63 bypass pipe
66 pressure detector

{CLAIMS}
1. A power-generation plant comprising:
a gas turbine that combusts fuel gas;
5 a fuel-gas cooler that cools the fuel gas, which is
pressurized at a fuel-gas compressor and recirculated, with
coolant sprayed from a spray nozzle;
an extraction line that guides the fuel gas extracted
from an intermediate stage of the fuel-gas compressor to the
10 fuel-gas cooler;
a first level detector that detects whether a level of
the coolant accumulated at a bottom portion of the fuel-gas
cooler has reached a predetermined level; and
a controller that stops the gas turbine on the basis of a
15 detection signal sent from the first level detector and that
outputs a command signal for stopping a coolant pump that
supplies the coolant to the spray nozzle.
2. A power-generation plant according to Claim 1, further
20 comprising:
a bypass line that guides the fuel gas, which is
pressurized at the fuel-gas compressor and recirculated, to
the fuel-gas cooler;
a second level detector that detects whether a level of
25 the coolant accumulated in the bypass line has reached a
35
predetermined level; and
a controller that stops the gas turbine on the basis of a
detection signal sent from the second level detector and that
outputs a command signal for stopping the coolant pump that
5 supplies the coolant to the spray nozzle.
3. A power-generation plant comprising:
a gas turbine that combusts fuel gas;
a fuel-gas cooler that cools the fuel gas, which is
10 pressurized at a fuel-gas compressor and recirculated, with
coolant sprayed from a spray nozzle;
a bypass line that guides the fuel gas, which is
pressurized at the fuel-gas compressor and recirculated, to
the fuel-gas cooler;
15 a level detector that detects whether a level of the
coolant accumulated in the bypass line has reached a
predetermined level; and
a controller that stops the gas turbine on the basis of a
detection signal sent from the level detector and that outputs
20 a command signal for stopping a coolant pump that supplies the
coolant to the spray nozzle.
4. A power-generation plant according any one of Claims 1 to
3, further comprising:
25 a coolant pipe that supplies the coolant to the spray
36
nozzle,
wherein the coolant pipe is provided with a bypass pipe
that returns the coolant to the interior of the fuel-gas
cooler by bypassing the spray nozzle.
5
5. A power-generation plant according to Claim 4, wherein a
pipe leading to the spray nozzle is provided with a pressure
detector for detecting the pressure of the coolant that passes
through the pipe.
10
6. A power-generation plant comprising:
a gas turbine that combusts fuel gas;
a fuel-gas cooler that cools the fuel gas, which is
pressurized at a fuel-gas compressor and recirculated, with
15 coolant sprayed from a spray nozzle; and
a coolant pipe that supplies the coolant to the spray
nozzle,
wherein the coolant pipe is provided with a bypass pipe
that returns the coolant to the interior of the fuel-gas
20 cooler by bypassing the spray nozzle.
7. A power-generation plant according to Claim 6, wherein a
pipe leading to the spray nozzle is provided with a pressure
detector for detecting the pressure of the coolant that passes
25 through the pipe.
37
8. A method of stopping a power-generation plant including
a gas turbine that combusts fuel gas;
a fuel-gas cooler that cools the fuel gas, which is
5 pressurized at a fuel-gas compressor and recirculated, with
coolant sprayed from a spray nozzle; and
an extraction line that guides the fuel gas extracted
from an intermediate stage of the fuel-gas compressor to the
fuel-gas cooler,
10 the method comprising:
stopping the gas turbine when a level of the coolant
accumulated at a bottom portion of the fuel-gas cooler has
reached a predetermined level; and
stopping a coolant pump, which supplies the coolant to
15 the spray nozzle.
9. A method of stopping a power-generation plant according to
Claim 8, further comprising:
stopping the gas turbine when a level of the coolant
20 accumulated in a bypass line that guides the fuel gas, which
is pressurized at the fuel-gas compressor and recirculated, to
the fuel-gas cooler has reached a predetermined level; and
stopping the coolant pump, which supplies the coolant to
the spray nozzle.
25
38
10. A method of stopping a power-generation plant including a gas turbine that combusts fuel gas;
a fuel-gas cooler that cools the fuel gas, which is pressurized at a fuel-gas compressor and recirculated, with coolant sprayed from a spray nozzle; and a bypass line that guides the fuel gas, which is pressurized at the fuel-gas compressor and recirculated, to the fuel-gas cooler, the method comprising: stopping the gas turbine when a level of the coolant accumulated in the bypass line has reached a predetermined level; and stopping a coolant pump that supplies the coolant to the
spray nozzle.