U.S. patent number 10,385,862 [Application Number 15/545,242] was granted by the patent office on 2019-08-20 for rotary machine system.
This patent grant is currently assigned to MITSUBISHI HEAVY INDUSTRIES COMPRESSOR CORPORATION. The grantee listed for this patent is MITSUBISHI HEAVY INDUSTRIES COMPRESSOR CORPORATION. Invention is credited to Ryo Egami, Masahiro Hayashi, Takeshi Kaneko, Masaki Shakuda, Tomoaki Takeda, Kazutoshi Yokoo.
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United States Patent |
10,385,862 |
Egami , et al. |
August 20, 2019 |
Rotary machine system
Abstract
A rotary machine system includes: a rotary machine including a
gas seal portion; a gas seal device connected to the rotary machine
and that supplies a seal gas to the gas seal portion; and a
connecting pipe that connects the gas seal portion and the gas seal
device. The rotary machine includes a casing through which a
working fluid flows; a rotatable rotary shaft; and the gas seal
portion that seals the working fluid by the seal gas having a
pressure higher than a pressure of the working fluid in the casing.
The gas seal device includes: a seal gas supply pipe through which
the seal gas delivered to the connecting pipe flows; a pressure
regulating valve provided in the seal gas supply pipe and that
adjusts the pressure of the seal gas supplied to the gas seal
portion; and a control part.
Inventors: |
Egami; Ryo (Tokyo,
JP), Kaneko; Takeshi (Tokyo, JP), Yokoo;
Kazutoshi (Tokyo, JP), Shakuda; Masaki
(Hiroshima, JP), Hayashi; Masahiro (Hiroshima,
JP), Takeda; Tomoaki (Hiroshima, JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
MITSUBISHI HEAVY INDUSTRIES COMPRESSOR CORPORATION |
Tokyo |
N/A |
JP |
|
|
Assignee: |
MITSUBISHI HEAVY INDUSTRIES
COMPRESSOR CORPORATION (Tokyo, JP)
|
Family
ID: |
56416750 |
Appl.
No.: |
15/545,242 |
Filed: |
October 15, 2015 |
PCT
Filed: |
October 15, 2015 |
PCT No.: |
PCT/JP2015/079193 |
371(c)(1),(2),(4) Date: |
July 20, 2017 |
PCT
Pub. No.: |
WO2016/117188 |
PCT
Pub. Date: |
July 28, 2016 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20170370372 A1 |
Dec 28, 2017 |
|
Foreign Application Priority Data
|
|
|
|
|
Jan 23, 2015 [JP] |
|
|
2015-011666 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04D
29/104 (20130101); F16J 15/40 (20130101); F04D
29/4206 (20130101); F16J 15/34 (20130101); F05D
2260/607 (20130101); F05D 2270/3011 (20130101); F04D
29/108 (20130101) |
Current International
Class: |
F04D
29/10 (20060101); F16J 15/34 (20060101); F16J
15/40 (20060101); F04D 29/42 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
3979091 |
|
Sep 2007 |
|
JP |
|
2012082765 |
|
Apr 2012 |
|
JP |
|
Other References
International Search Report issue in corresponding International
Application No. PCT/JP2015/079193 dated Jan. 19, 2016 (2 pages).
cited by applicant .
Written Opinion issued in corresponding International Application
No. PCT/JP2015/079193 dated Jan. 19, 2016 (7 pages). cited by
applicant.
|
Primary Examiner: Nguyen; Ninh H.
Attorney, Agent or Firm: Osha Liang LLP
Claims
What is claimed is:
1. A rotary machine system comprising: a rotary machine comprising
a gas seal portion; a gas seal device connected to the rotary
machine and that supplies a seal gas to the gas seal portion; and a
connecting pipe that connects the gas seal portion and the gas seal
device, wherein the rotary machine comprises: a casing through
which a working fluid flows; a rotatable rotary shaft that passes
through an inside and an outside of the casing; and the gas seal
portion provided between the casing and the rotary shaft and that
seals the working fluid by the seal gas having a pressure higher
than a pressure of the working fluid in the casing, the gas seal
device comprises: a seal gas supply pipe through which the seal gas
delivered to the connecting pipe flows; a pressure regulating valve
provided in the seal gas supply pipe and that adjusts the pressure
of the seal gas supplied to the gas seal portion; and a control
part that controls the pressure regulating valve according to the
pressure of the seal gas, and the connecting pipe has a pipe
diameter larger than a pipe diameter of the seal gas supply
pipe.
2. The rotary machine system according to claim 1, further
comprising a joint portion having an inner diameter gradually
reduced from the connecting pipe side, wherein the joint portion is
provided in at least one of a space between the connecting pipe and
the seal gas supply pipe and a space between the connecting pipe
and a port connection hole through which the connecting pipe is
connected to the casing.
3. The rotary machine system according to claim 1, wherein the
control part increases an opening degree of the pressure regulating
valve when a change amount of the pressure of the seal gas supplied
from the gas seal device to the gas seal portion is equal to or
more than a predetermined threshold value.
4. The rotary machine system according to claim 1, wherein the pipe
diameter of the connecting pipe is formed so that a pressure loss
in the connecting pipe is equal to or less than a predetermined
value which is set in advance.
Description
TECHNICAL FIELD
The present invention relates to a rotary machine system. Priority
is claimed on Japanese Patent Application No. 2015-011666, filed
Jan. 23, 2015, the content of which is incorporated herein by
reference.
BACKGROUND ART
In a rotary machine such as a centrifugal compressor, there is a
rotary shaft of which an end protrudes to an outside of a casing to
input or output a rotational force of a rotary shaft rotatably
provided in the casing. In this case, it is necessary to prevent
leakage of a working fluid in the casing to the outside of the
casing and infiltration of foreign substances or the like into the
casing from the outside thereof through a gap between the rotary
shaft and a shaft insertion hole formed in the casing for the
rotary shaft to pass through the casing. Therefore, a gas seal
portion is provided between the rotary shaft and the casing.
The gas seal portion includes a rotary ring and a stationary ring.
The rotary ring is provided integrally with the rotary shaft on an
outer circumferential portion of the rotary shaft. The stationary
ring is fixed to the casing and is provided to face the rotary ring
in an axial direction of the rotary shaft. The stationary ring is
pressed toward the rotary ring by a coil spring or the like.
Therefore, in a state in which the rotary machine is stopped, the
stationary ring and the rotary ring abut on each other. In
addition, a spiral groove is formed on a surface of the rotary ring
facing the stationary ring. When the rotary machine is operated and
the rotary shaft rotates, a seal gas is introduced between the
rotary ring and the stationary ring by the spiral groove. Due to
the pressure of the gas, the stationary ring is pressed in the
axial direction of the rotary shaft against a biasing force of the
coil spring. As a result, a minute gap is formed between the rotary
ring and the stationary ring. The seal gas is caused to flow
through the gap from an inside of the rotary machine toward an
outside thereof through the gap, and thus sealing between the
rotary shaft and the casing is achieved. In this case, the pressure
of the seal gas is higher than the pressure inside and outside the
rotary machine.
In such a gas seal portion, the seal gas flowing from the inside of
the rotary machine to the outside thereof via the gap between the
rotary ring and the stationary ring is discharged to an outside
through a vent (chimney) connected to the casing.
A gas or the like discharged from equipment other than the rotary
machine may be delivered into the vent and may be discharged to the
outside together with the seal gas. Further, depending on a type of
the gas, the gas may be burned near an outlet of the vent. When the
gas or the like is delivered into the vent from the equipment other
than the rotary machine or the gas is burned, a pressure in the
vent is increased. When the pressure in the vent becomes higher
than that of the inside of the machine, the seal gas flows backward
in the gap between the rotary ring and the stationary ring. Then,
the rotary ring and the stationary ring may collide with each
other, and thus the gas seal portion may be damaged.
Patent Document 1 discloses a constitution which includes a flow
rate switch for detecting a flow rate of a gas leaking from the gas
seal portion to the vent. Accordingly, when the working gas leaks
due to breakage of the gas seal portion and the flow rate of the
gas at the vent is increased, an abnormality is detected.
However, the constitution disclosed in Patent Document 1 is for
detecting the breakage of the gas seal portion due to a backflow or
the like of the seal gas from the vent to the gas seal portion as
the abnormality. That is, it is not for preventing the breakage of
the gas seal portion by suppressing the backflow of the seal
gas.
Therefore, the pressure of the seal gas is usually controlled so
that the pressure of the seal gas in the gas seal portion is
reliably maintained at a higher level than the pressure of the vent
inside and outside the rotary machine.
CITATION LIST
Patent Literature
[Patent Document 1]
Japanese Patent No. 3979091
However, in a pipe constituting a supply line for feeding the seal
gas to the gas seal portion, pressure loss occurs. Even if the seal
gas is delivered from a supply side of the seal gas with a pressure
higher than the pressure inside the vent and the pressure inside
the rotary machine, the pressure of the seal gas is lowered by the
pressure loss in the supply line when the seal gas reaches the gas
seal portion.
Also, the pressure of the gas in the vent which is discharged
through the vent is varied by combustion of the gas delivered from
the equipment other than the rotary machine or the gas in the vent.
Even if the variation is taken into consideration, it is necessary
to keep the pressure of the seal gas in the gas seal portion
high.
Therefore, the pipe is formed as thick as possible so that the
pressure loss is suppressed and the pressure of the seal gas is
kept high. However, a cost is increased as the pipe becomes
thicker.
Also, the magnitude of the pressure loss to be generated can be
variously varied depending on conditions such as a pipe diameter, a
piping layout, a pressure of a working fluid in a compressor and so
on. Therefore, actually, whenever the rotary machine is installed,
it is necessary to set an optimum pipe diameter according to
various conditions at an installation position thereof, which is
accompanied with effort and cost.
SUMMARY OF INVENTION
One or more embodiments of the present invention provides a rotary
machine system which is capable of suppressing a piping cost, a
design cost and a designing effort for supplying a seal gas while
suppressing a backflow of the seal gas.
A rotary machine system of a first aspect of the present invention
may include a rotary machine having a gas seal portion, a gas seal
device connected to the rotary machine and configured to supply a
seal gas to the gas seal portion, and a connecting pipe configured
to connect the gas seal portion and the gas seal device, wherein
the rotary machine includes a casing through which a working fluid
flows, a rotary shaft configured to pass through an inside and an
outside of the casing and provided to be rotatable, and the gas
seal portion provided between the casing and the rotary shaft and
configured to seal the working fluid by the seal gas having a
pressure higher than that of the working fluid in the casing, and
the gas seal device includes a seal gas supply pipe through which
the seal gas delivered to the connecting pipe flows, a pressure
regulating valve provided in the seal gas supply pipe and
configured to adjust the pressure of the seal gas supplied to the
gas seal portion, and a control part (controller) configured to
control the pressure regulating valve according to the pressure of
the seal gas, and the connecting pipe has a pipe diameter larger
than that of the seal gas supply pipe.
According to one or more embodiments as described above, the pipe
diameter of the connecting pipe is formed to be thicker than that
of the seal gas supply pipe. Therefore, the pressure loss in the
connecting pipe can be suppressed. In addition, since it is only
necessary to thicken the connecting pipe, an increase in cost can
be suppressed.
Meanwhile, in the gas seal device on an upstream side of the
connecting pipe, it is not necessary to make the seal gas supply
pipe thick. Therefore, in the gas seal device, it is not necessary
to set a thickness of the seal gas supply pipe for each rotary
machine system, and the seal gas supply pipe may be formed at a
constant thickness.
Further, a rotary machine system of a second aspect of the present
invention may include a joint portion of which an inner diameter is
gradually reduced from the connecting pipe side may be provided in
at least one of a space between the connecting pipe and the seal
gas supply pipe and a space between the connecting pipe and a port
connection hole through which the connecting pipe is connected to
the casing, in the first aspect.
Accordingly, in one or more embodiments, a cross-sectional area of
a flow path of the seal gas can be suppressed from being varied
discontinuously between the connecting pipe and the seal gas supply
pipe and between the connecting pipe and the port connection hole,
and thus the pressure loss can be suppressed.
Further, in a rotary machine system of a third aspect of the
present invention, the control part in the first or second aspect
may increase an opening degree of the pressure regulating valve
when a change amount of the pressure of the seal gas supplied from
the gas seal device to the gas seal portion is equal to or more
than a predetermined threshold value.
According to one or more embodiments as described above, when the
supply pressure of the seal gas supplied by the gas seal device is
increased, the opening degree of the pressure regulating valve is
temporarily increased. Therefore, a flow rate of the seal gas is
increased, and responsiveness when the supply pressure is changed
can be enhanced. Additionally, when the increase in the supply
pressure of the seal gas supplied by the gas seal device is
stopped, the temporary increase in the opening degree of the
pressure regulating valve is stopped, and thus a usage amount of
the seal gas can be suppressed.
Further, in a rotary machine system of a fourth aspect of the
present invention, the pipe diameter of the connecting pipe in one
of the first to third aspects may be formed so that a pressure loss
in the connecting pipe is equal to or less than a predetermined
value which is set in advance.
In this way, according to one or more embodiments, the pressure
loss in the connecting pipe can be reliably suppressed.
According to one or more embodiments of the above-described rotary
machine system, it is possible to minimize a pipe diameter for
supplying a seal gas to a gas seal portion while reliably
suppressing a backflow of the seal gas, thereby suppressing the
piping cost, the design cost and the designing effort for supplying
the seal gas.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a view showing a schematic constitution of a rotary
machine system with a compressor as an example of a rotary machine
in an embodiment.
FIG. 2 is a view showing a constitution of a gas seal portion
provided at the compressor in a first embodiment.
FIG. 3 is a view showing a constitution of a modified example of a
connection pipe portion in the first embodiment.
FIG. 4 is a view showing a constitution of a gas seal portion
provided at the compressor in a second embodiment.
FIG. 5 is a view showing a change in an opening degree of a
pressure regulating valve in the second embodiment.
DETAILED DESCRIPTION OF EMBODIMENTS
Hereinafter, embodiments for implementing a rotary machine system
according to the present invention will be described with reference
to the accompanying drawings. However, the present invention is not
limited to only these embodiments.
First Embodiment
FIG. 1 is a view showing a schematic constitution of a rotary
machine system with a compressor as an example of a rotary machine
in an embodiment.
As shown in FIG. 1, a rotary machine system 1 includes a compressor
(rotary machine) 10, a turbine 20 as a drive source for driving the
compressor 10, and a gas seal module (GSM: gas seal device) 40A for
supplying a seal gas Gs to the compressor 10.
The compressor 10 is, for example, a centrifugal compressor and
includes a rotary shaft 12 and a compression part (not shown) such
as an impeller, which rotates integrally with the rotary shaft 12
and compresses a gas G serving as a working fluid, in a casing 11.
A gas seal portion 30 is provided in a portion on a suction side of
the compressor 10 in which the rotary shaft 12 passes through an
end of the casing 11 and protrudes outward.
FIG. 2 is a view showing a constitution of the gas seal portion 30
provided at the compressor 10 in a first embodiment.
As shown in FIG. 2, the gas seal portion 30 includes a rotary ring
31, a stationary ring 32 and a labyrinth seal 33 on an inside of
the machine.
The rotary ring 31 is provided integrally with the rotary shaft 12
on an outer circumferential portion of the rotary shaft 12. A
cylindrical shaft sleeve 35 is fixed to the outer circumferential
portion of the rotary shaft 12. A holder portion 36 extending
toward an outer circumference side is provided at an end 35a of the
shaft sleeve 35 on the inside A (left side in FIG. 2) of the
machine. In the holder portion 36, a holding recess 36a for holding
the rotary ring 31 is provided on an outside B (right side in FIG.
2) of the machine.
The rotary ring 31 is formed in an annular shape and fitted and
held in the holding recess 36a. In the rotary ring 31, a spiral
groove (not shown) is provided on a surface 31f thereof facing the
stationary ring 32.
The stationary ring 32 is provided on a casing 11 side. A shaft
insertion hole 11h through which an end of the rotary shaft 12
passes through an inside and an outside of the casing 11 is
provided in the casing 11.
An annular retainer 37 is provided on an inner circumferential
surface of the shaft insertion hole 11h. A holding recess 37a for
holding the stationary ring 32 is provided on the inside A of the
machine in the retainer 37. In the holding recess 37a, the
stationary ring 32 is provided to be slide-able in an axial
direction of the rotary shaft 12. A coil spring 38 for biasing the
stationary ring 32 toward the inside A of the machine is provided
in the holding recess 37a between the stationary ring 32 and the
retainer 37.
The rotary ring 31 and the stationary ring 32 are provided to face
each other in the axial direction of the rotary shaft 12. The
stationary ring 32 is pressed toward the rotary ring 31 by the coil
spring 38.
A seal gas supply port 15 which opens on the inner circumferential
surface of the shaft insertion hole 11h is provided in the casing
11. The seal gas supply port 15 is formed between the rotary ring
31 and the labyrinth seal 33 on the inside of the machine in the
axial direction of the rotary shaft 12.
A seal gas supply path 17 is connected to the seal gas supply port
15. The seal gas supply path 17 supplies a part of the gas G
compressed by the compressor 10 as the seal gas Gs from a discharge
side of the compressor 10 to the seal gas supply port 15.
A vent discharge port 16 which opens on the inner circumferential
surface of the shaft insertion hole 11h is provided in the casing
11. The vent discharge port 16 is formed closer to the outside B of
the machine than the rotary ring 31 in the axial direction of the
rotary shaft 12.
A vent (chimney; vent portion) 18 is connected to the vent
discharge port 16. The seal gas Gs flowing out from the gas seal
portion 30 is discharged to an outside via the vent 18. In addition
to the compressor 10, other devices are connected to the vent
18.
In such a gas seal portion 30, the stationary ring 32 and the
rotary ring 31 abut on each other in a state in which the
compressor 10 is stopped.
In a state in which the compressor 10 is operated, the seal gas Gs
is introduced into a space between the shaft insertion hole 11h of
the casing 11 and the rotary shaft 12 through the seal gas supply
path 17 and the seal gas supply port 15. When the compressor 10 is
operated and the rotary shaft 12 rotates, the seal gas Gs is
introduced between the rotary ring 31 and the stationary ring 32
from an outer circumference side of the rotary ring 31 by the
spiral groove formed on the surface 31f of the rotary ring 31. When
the stationary ring 32 is pressed toward the outside B of the
machine in the axial direction of the rotary shaft 12 against a
biasing force of the coil spring 38 by a pressure of the seal gas
Gs, a minute seal gap S is formed between the rotary ring 31 and
the stationary ring 32. The seal gas Gs passes through the seal gap
S and flows toward the outside B of the machine. In this manner,
the seal gas Gs is caused to flow from the inside A of the machine
toward the outside B thereof, and thus sealing between the rotary
shaft 12 and the casing 11 is achieved.
Further, the seal gas Gs flows from the rotary ring 31 and
stationary ring 32 side to the inside A of the machine through a
space between the labyrinth seal 33 on the inside of the machine
and the rotary shaft 12. As a result, foreign substances or the
like are prevented from being introduced into the seal gap S
between the rotary ring 31 and the stationary ring 32 from the
inside A of the machine.
To prevent the seal gas Gs delivered into the casing 11 through the
seal gas supply path 17 from flowing backward in the gas seal
portion 30, the gas seal module 40A adjusts the pressure of the
seal gas Gs to be higher than that of the inside A of the
machine.
The gas seal module 40A includes a pressure regulating valve 41, a
control part 42A which controls an opening degree of the pressure
regulating valve 41, and a module pipe portion (seal gas supply
pipe) 44 which is provided in the gas seal module 40A to form a
part of the seal gas supply path 17.
The pressure regulating valve 41 is provided in the module pipe
portion 44. The pressure regulating valve 41 includes a valve body
41v and a valve driving part 41d. The valve body 41v is provided in
the seal gas supply path 17 and is driven by the valve driving part
41d to increase or decrease a flow path area of the seal gas supply
path 17. The pressure regulating valve 41 adjusts a supply pressure
P1b of the seal gas Gs supplied into the casing 11 through the seal
gas supply path 17 by varying the opening degree of the valve body
41v by the valve driving part 41d. An operation of the valve
driving part 41d is controlled by the control part 42A.
The control part 42A controls the valve driving part 41d of the
pressure regulating valve 41 on the basis of the supply pressure
P1b of the seal gas Gs and an internal pressure P2 of the
machine.
The supply pressure P1b of the seal gas Gs is detected by a seal
gas pressure sensor S1A provided in the seal gas supply path 17.
The internal pressure P2 of the machine is detected by an internal
pressure sensor S2 provided closer to the inside A of the casing 11
than the gas seal portion 30 and the labyrinth seal 33 on an inside
of the machine.
The seal gas pressure sensor S1A and the internal pressure sensor
S2 are connected to a differential pressure gauge 43A. The
differential pressure gauge 43A detects a differential pressure
PDT1(=P1b-P2) in the machine between the supply pressure P1b of the
seal gas Gs supplied into the casing 11 through the seal gas supply
path 17 and the internal pressure P2 of the machine of the casing
11. A signal indicating the detected differential pressure PDT1 in
the machine is transmitted to the control part 42A.
During an operation of the compressor 10, the control part 42A
obtains the differential pressure PDT1 in the machine which is
detected by the differential pressure gauge 43A at predetermined
time intervals.
When the detected differential pressure PDT1 in the machine is
equal to or more than a predetermined lower limit threshold value,
or less than a predetermined upper limit threshold value, the
supply pressure P1b of the seal gas Gs is sufficiently higher than
the internal pressure P2 of the machine, and thus the operation is
continued as it is without changing the opening degree of the
pressure regulating valve 41.
Further, when the detected differential pressure PDT1 in the
machine is less than the predetermined lower limit threshold value,
the supply pressure P1b of the seal gas Gs is not sufficiently
higher than the internal pressure P2 of the machine, and thus the
opening degree of the pressure regulating valve 41 is increased.
Then, the supply pressure P1b of the seal gas Gs supplied into the
casing 11 through the seal gas supply path 17 is increased. As a
result, the differential pressure PDT1 in the machine between the
supply pressure P1b of the seal gas Gs and the internal pressure P2
in the machine is increased.
Here, when the differential pressure PDT1 in the machine is less
than the predetermined lower limit threshold value, the opening
degree of the pressure regulating valve 41 is increased, but an
amount of change in the opening degree may be, for example, a
preset amount of change in the opening degree according to a
magnitude of the differential pressure PDT1 in the machine. Also,
the opening degree of the pressure regulating valve 41 may be
increased by a predetermined amount in every operation process.
Further, when the detected differential pressure PDT1 in the
machine exceeds the predetermined upper limit threshold value, the
supply pressure P1b of the seal gas Gs is excessively higher than
the internal pressure P2 of the machine, and the flow rate of the
seal gas flowing into the inside A of the machine is increased, and
thus the flow rate of the gas G which is compressed by the
compressor 10 is reduced. Therefore, the control part 42A reduces
the opening degree of the pressure regulating valve 41.
As described above, by adjusting the opening degree of the pressure
regulating valve 41 by the control part 42A on the basis of the
supply pressure P1b of the seal gas Gs which is detected by the
seal gas pressure sensor S1A and the internal pressure P2 of the
machine which is detected by the internal pressure sensor S2, a
pressure P1a of the seal gas Gs in the gas seal portion 30 inside
the casing 11 can always be kept higher than the internal pressure
P2 of the machine.
Accordingly, a backflow of the seal gas Gs from the gas seal
portion 30 toward the inside A of the compressor 10 can be
prevented.
Here, in the seal gas supply path 17, a port connection hole
(connection hole portion) 71A is provided on an outer
circumferential surface of the casing 11 and communicates with the
seal gas supply port 15 and one or more connecting pipes 72 (the
example of FIG. 2 shows one, and they are connected to each other
when there are a plurality) are provided at a connection pipe
portion 70A which connects the gas seal module 40A and the casing
11 of the compressor 10.
One end of the connecting pipe 72 is connected to the port
connection hole 71A, and the other end is connected to the module
pipe portion 44 of the gas seal module 40A.
The connecting pipe 72 has a pipe diameter larger than that of the
module pipe portion 44, that is, the inner diameter thereof is
larger. More specifically, in the connecting pipe 72, the pressure
loss in the connecting pipe 72 is equal to or lower than a
predetermined value which is set in advance.
The pressure loss .DELTA.P in the connecting pipe 72 is expressed
by the following Equation (1).
.times..DELTA..times..times..lamda..rho..times..times.
##EQU00001##
In Equation (1), .lamda. is a friction loss coefficient, L is a
length of the connecting pipe 72, D is an inner diameter of the
connecting pipe 72, .rho. is a density of the seal gas Gs, and v is
the average flowing velocity of the seal gas Gs.
Further, a cross-sectional area S of the connecting pipe 72 is
S=.pi.D.sup.2/4 (2),
and assuming that m is a volume flow rate, v=m/S (3).
From Equations 2 and 3, v=4m/D.sup.2 (4).
When Equation (4) is substituted into Equation (1), it is expressed
by the following Equation (5), and the pressure loss .DELTA.P is
inversely proportional to a fifth power of the inner diameter D of
the connecting pipe.
.times..DELTA..times..times..times..lamda..rho..times..times..pi..times..-
times..times..lamda..rho..times..times..times..pi..times..times..lamda..ti-
mes..times..rho..function..times..times..times..times..pi.
##EQU00002##
That is, the pressure loss .DELTA.P in the connecting pipe 72 is as
shown in Equation (5). Therefore, based on Equation (5), the inner
diameter D of the connecting pipe 72 is set so that the pressure
loss .DELTA.P in the connecting pipe 72 becomes a predetermined
value or less which is set in advance.
The connecting pipe 72 has a straight tubular shape in FIG. 2 but
is actually appropriately bent to avoid interference with various
devices arranged around the compressor 10. Also, a length of the
connecting pipe 72 is determined according to an installation
interval between the compressor 10 and the gas seal module 40A and
may have a range of, for example, 20 to 30 m.
According to the rotary machine system 1 described above, the inner
diameter of the connecting pipe 72 is formed larger than that of
the seal gas supply path 17 on the gas seal module 40A side.
Therefore, the pressure loss in the connecting pipe 72 can be
suppressed. Further, since only the connecting pipe 72 needs to be
thickened, it is possible to suppress an increase in cost.
Meanwhile, in the gas seal module 40A on an upstream side of the
connecting pipe 72, it is not necessary to make the module pipe
portion 44 thick. Therefore, in the gas seal module 40A, it is not
necessary to set a thickness of the module pipe portion 44 for each
rotary machine system 1, and the module pipe portion 44 may be
formed at a constant thickness. As a result, the gas seal module
40A can be formed as a unit with high versatility, and design
effort and a design cost thereof can be suppressed. Also, since it
is not necessary to make the module pipe portion 44 thick, cost
reduction and downsizing of the gas seal module 40A can be
achieved.
Accordingly, the piping cost, the design cost and the design effort
of the pipe for supplying the seal gas can be suppressed while the
backflow of the seal gas is suppressed.
Modified Example of First Embodiment
In the first embodiment, an inner diameter of the connecting pipe
72 is set to be larger than that of the seal gas supply path 17 on
the gas seal module 40A side. Additionally, a cross-sectional area
of a flow path is varied discontinuously at a connection portion
between the connecting pipe 72 and the module pipe portion 44 and a
connection portion between the connecting pipe 72 and the port
connection hole 71A.
Meanwhile, as shown in FIG. 3, a joint pipe 75 may be provided at
at least one of a space between the connecting pipe 72 and the
module pipe portion 44 and a space between the connecting pipe 72
and the port connection hole 71A. An inner diameter of the joint
pipe (joint portion) 75 is gradually reduced from the connecting
pipe 72 side thereof toward the module pipe portion 44 and the port
connection hole 71A, and a step is smoothly formed between an inner
circumferential surface of the connecting pipe 72 and an inner
circumferential surface of the module pipe portion 44. Accordingly,
it is possible to suppress the discontinuous change in the
cross-sectional area of the flow path in the seal gas supply path
17 and thus to suppress the pressure loss.
Second Embodiment
Next, a second embodiment of the rotary machine system according to
the present invention will be described. The second embodiment to
be described is different from the first embodiment in only a
control method of the gas seal module 40A, and the constitution of
the rotary machine system 1 is common to the first embodiment.
Therefore, the same reference numerals are provided for the
elements common to those of the first embodiment, and the
description thereof will be omitted.
As shown in FIG. 1, the rotary machine system 1 of the embodiment
includes a compressor 10, a turbine 20 and a gas seal module (gas
seal device) 40B.
FIG. 4 is a view showing a constitution of a gas seal portion 30
provided at the compressor 10 in a second embodiment.
As shown in FIG. 4, the compressor 10 includes a rotary shaft 12
and a compressing part (not shown) in a casing 11. In a suction
side of the compressor 10, a gas seal portion 30 is provided in a
portion in which the rotary shaft 12 passes through an end of the
casing 11 and protrudes outward.
To prevent the seal gas Gs delivered into the casing 11 through the
seal gas supply path 17 from flowing backward in the gas seal
portion 30, the gas seal module 40B adjusts a pressure of the seal
gas Gs to be higher than that in an inside A of the machine.
The gas seal module 40B includes a pressure regulating valve 41, a
control part 42B which controls an opening degree of the pressure
regulating valve 41 and a module pipe portion 44 which is provided
in the gas seal module 40B to form a part of the seal gas supply
path 17.
The control part 42B controls a valve driving part 41d of the
pressure regulating valve 41 on the basis of a pressure P1a of the
seal gas Gs in the gas seal portion 30, an internal pressure P2 of
the machine and the vent pressure P3 in the vent 18.
A supply pressure P1b of the seal gas Gs is detected by a seal gas
pressure sensor S1A provided in the seal gas supply path 17. An
internal pressure P2 of the machine is detected by an internal
pressure sensor S2 provided closer to the inside A of the machine
of the casing 11 than the gas seal portion 30 and a labyrinth seal
33 on the inside of the machine. A vent pressure P3 is detected by
a vent pressure sensor S3 provided in a vent 18.
The seal gas pressure sensor S1A and the internal pressure sensor
S2 are connected to a differential pressure gauge 43A. The
differential pressure gauge 43A detects a differential pressure
PDT1(=P1b-P2) in the machine between the supply pressure P1b of the
seal gas Gs supplied into the casing 11 through the seal gas supply
path 17 and the internal pressure P2 of the machine of the casing
11. A signal indicating the detected differential pressure PDT1 in
the machine is transmitted to the control part 42B.
During an operation of the compressor 10, the control part 42B
obtains the differential pressure PDT1 in the machine which is
detected by the differential pressure gauge 43A at predetermined
time intervals which is set in advance.
When the detected differential pressure PDT1 in the machine is
equal to or more than a predetermined lower limit threshold value
and less than a predetermined upper limit threshold value, the
supply pressure P1b of the seal gas Gs is sufficiently higher than
the internal pressure P2 of the machine, and thus the operation is
continued as it is without changing the opening degree of the
pressure regulating valve 41.
When the detected differential pressure PDT1 in the machine is less
than the predetermined lower limit threshold value, the supply
pressure P1b of the seal gas Gs is not sufficiently higher than the
internal pressure P2 of the machine, and thus the opening degree of
the pressure regulating valve 41 is increased. Then, the supply
pressure P1b of the seal gas Gs supplied into the casing 11 through
the seal gas supply path 17 is increased. As a result, the
differential pressure PDT1 in the machine between the supply
pressure P1b of the seal gas Gs and the internal pressure P2 of the
machine is increased.
FIG. 5 is a view showing a change in the opening degree of the
pressure regulating valve in the second embodiment.
Here, in order to monitor an increase amount of a supply flow rate
of the seal gas Gs, the control part 42B calculates an increase
amount of the vent pressure P3 in the vent 18 detected by the vent
pressure sensor S3 at predetermined time intervals. The control
part 42B may calculate an increase amount of the supply pressure
P1b of the seal gas Gs instead of the vent pressure P3.
As shown in FIG. 5, when the increase amount of the vent pressure
P3 exceeds a predetermined threshold value, the opening degree of
the pressure regulating valve 41 is multiplied by a coefficient
.alpha. of 1 or more, and the pressure regulating valve 41 is
opened to be larger than a target opening degree.
Then, when the increase amount of the vent pressure P3 is reduced
below a predetermined threshold value, the multiplication of the
opening degree of the pressure regulating valve 41 by the
coefficient .alpha. of 1 or more is stopped, and the opening degree
of the pressure regulating valve 41 is adjusted to the target
opening degree.
Further, when the detected differential pressure PDT1 in the
machine exceeds a predetermined upper limit threshold value, the
supply pressure P1b of the seal gas Gs is excessively higher than
the internal pressure P2 of the machine, and therefore a flow rate
of the seal gas flowing into the inside A of the machine is
increased, and the flow rate of the gas G which is compressed by
the compressor 10 is reduced. Therefore, the control part 42B
reduces the opening degree of the pressure regulating valve 41.
As described above, by adjusting the opening degree of the pressure
regulating valve 41 by the control part 42B on the basis of the
supply pressure P1b of the seal gas Gs which is detected by the
seal gas pressure sensor S1A and the internal pressure P2 of the
machine which is detected by the internal pressure sensor S2, the
pressure P1a of the seal gas Gs in the gas seal portion 30 inside
the casing 11 is always kept higher than the internal pressure P2
of the machine. Accordingly, backflow of the seal gas Gs from the
gas seal portion 30 toward the inside A of the compressor 10 is
suppressed.
According to the rotary machine system 1 described above, the
pressure loss in the connecting pipe 72 can be suppressed by
forming the connecting pipe 72 to be thicker than the seal gas
supply path 17 on the gas seal module 40 B side. However,
responsiveness when the supply pressure P1b of the seal gas Gs
supplied by the gas seal module 40B is changed is lowered because
the connecting pipe 72 is formed to be thick. Therefore, in the
embodiment, when the supply pressure P1b of the seal gas Gs
supplied by the gas seal module 40B is increased, the opening
degree of the pressure regulating valve 41 is caused to be
temporarily increased. Accordingly, the flow rate of the seal gas
Gs is increased, and the responsiveness when the supply pressure
P1b is changed can be enhanced. Additionally, when the increase in
the supply pressure P1b of the seal gas Gs supplied by the gas seal
module 40B is stopped, the increase in the opening degree of the
pressure regulating valve 41 is stopped, and thus a usage amount of
the seal gas Gs can be suppressed.
Other Embodiments
In addition, the rotary machine system of the present invention is
not limited to each of the above-described embodiments described
with reference to the drawings, and various modifications are
conceivable within the technical scope thereof.
For example, the constitution of the gas seal portion 30 can be
appropriately changed.
Further, although the gas seal portion 30 has been provided on the
suction side of the compressor 10, the present invention is not
limited thereto. The gas seal portion 30 may be provided on a
discharge side of the compressor 10. In this case, the same
operational effects as those in the above-described embodiments can
be obtained.
In addition, for example, the overall constitution of the
compressor 10 and the rotary machine system 1 may have any
types.
Although the disclosure has been described with respect to only a
limited number of embodiments, those skilled in the art, having
benefit of this disclosure, will appreciate that various other
embodiments may be devised without departing from the scope of the
present invention. Accordingly, the scope of the invention should
be limited only by the attached claims.
INDUSTRIAL APPLICABILITY
According to one or more embodiments of the above-described rotary
machine system, it is possible to surely suppress the backflow of
the seal gas, thereby suppressing the piping cost, the design cost
and the designing effort for supplying the seal gas.
REFERENCE SIGNS LIST
1 Rotary machine system 10 Compressor 11 Casing 11h Shaft insertion
hole 12 Rotary shaft 15 Seal gas supply port 16 Vent discharge port
17 Seal gas supply path 18 Vent 20 Turbine 30 Gas seal portion 31
Rotary ring 31f Surface 32 Stationary ring 33 Labyrinth seal on
inside of the machine 35 Shaft sleeve 35a End 36 Holder portion 36a
Holding recess 37 Retainer 37a Holding recess 38 Coil spring 40A,
40B Gas seal module 41 Pressure regulating valve 41d Valve driving
part 41v Valve body 42A, 42B Control part 43A Differential pressure
gauge 44 Module pipe portion 70A Connection pipe portion 71A Port
connection hole 72 Connecting pipe 75 Joint pipe (joint portion) A
Inside of machine B Outside of machine G Gas Gs Seal gas S Seal gap
S1A Seal gas pressure sensor S2 Internal pressure sensor S3 Vent
pressure sensor
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