U.S. patent application number 16/147040 was filed with the patent office on 2019-01-31 for ejector, ejector production method, and method for setting outlet flow path of diffuser.
This patent application is currently assigned to TLV CO., LTD.. The applicant listed for this patent is TLV CO., LTD.. Invention is credited to Tomonori ITOGA, Fumihiro KAWASHIMA.
Application Number | 20190032679 16/147040 |
Document ID | / |
Family ID | 59962889 |
Filed Date | 2019-01-31 |
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United States Patent
Application |
20190032679 |
Kind Code |
A1 |
KAWASHIMA; Fumihiro ; et
al. |
January 31, 2019 |
EJECTOR, EJECTOR PRODUCTION METHOD, AND METHOD FOR SETTING OUTLET
FLOW PATH OF DIFFUSER
Abstract
An ejector includes a nozzle, a suction chamber, and a diffuser.
An outlet flow path includes a narrowed flow path having a first
tapered surface narrowed toward downstream, a parallel flow path
having a constant sectional area, and a parallel flow path having a
second tapered surface expanded toward downstream. The diffuser
further includes an attachment configured to change the dimensions
of the outlet flow path. The attachment changes the dimensions of
the outlet flow path such that the ratio of the tapered angle of
the first tapered surface to the tapered angle of the second
tapered surface is higher as the sectional area, i.e., the inner
diameter, of the parallel flow path is smaller.
Inventors: |
KAWASHIMA; Fumihiro;
(Kakogawa-shi, JP) ; ITOGA; Tomonori; (Sendai-shi,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TLV CO., LTD. |
Hyogo |
|
JP |
|
|
Assignee: |
TLV CO., LTD.
Hyogo
JP
|
Family ID: |
59962889 |
Appl. No.: |
16/147040 |
Filed: |
September 28, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP2017/005469 |
Feb 15, 2017 |
|
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16147040 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04F 5/18 20130101; F04F
5/44 20130101; F04F 5/16 20130101; F04F 5/46 20130101; F04F 5/469
20130101; F04F 5/461 20130101 |
International
Class: |
F04F 5/16 20060101
F04F005/16; F04F 5/44 20060101 F04F005/44 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 1, 2016 |
JP |
2016-074570 |
Claims
1. An ejector comprising: a nozzle configured to eject first fluid;
a suction chamber configured to house the nozzle and to suck second
fluid by negative pressure generated by ejection of the first fluid
from the nozzle; and a diffuser including an outlet flow path and
configured to mix and discharge the first fluid and the second
fluid of the suction chamber, wherein the outlet flow path includes
a narrowed flow path having a first tapered surface narrowed toward
downstream, a parallel flow path connected to a downstream end of
the narrowed flow path and having a constant sectional area, and an
expanded flow path connected to a downstream end of the parallel
flow path and having a second tapered surface expanded toward
downstream, the diffuser further includes a changing unit
configured to change a dimension of the outlet flow path, and the
changing unit changes the dimension of the outlet flow path such
that a ratio of a tapered angle of the first tapered surface to a
tapered angle of the second tapered surface is higher as the
sectional area of the parallel flow path is smaller.
2. The ejector according to claim 1, wherein the changing unit
changes the dimension of the outlet flow path such that a length of
the parallel flow path is shorter as the sectional area of the
parallel flow path is smaller.
3. The ejector according to claim 2, wherein the changing unit
changes the dimension of the outlet flow path such that the length
of the parallel flow path changes in proportion to an inner
diameter of the parallel flow path.
4. The ejector according to claim 1, wherein part of the diffuser
is formed from a replaceable attachment, the changing unit is the
attachment, the attachment includes at least part of the narrowed
flow path, the parallel flow path, and at least part of the
expanded flow path, and the dimension of the outlet flow path is
changed by replacement of the attachment.
5. A method for manufacturing an ejector including a nozzle
configured to eject first fluid, a suction chamber configured to
house the nozzle and to suck second fluid by negative pressure
generated by ejection of the first fluid from the nozzle, and a
diffuser including an outlet flow path having a narrowed flow path
having a first tapered surface narrowed toward downstream, a
parallel flow path connected to a downstream end of the narrowed
flow path and having a constant sectional area, and an expanded
flow path connected to a downstream end of the parallel flow path
and having a second tapered surface expanded toward downstream and
configured to mix and discharge the first fluid and the second
fluid of the suction chamber, comprising: a setting step of setting
a dimension of the outlet flow path; and a preparation step of
preparing the diffuser having the dimension of the outlet flow path
set at the setting step, wherein at the setting step, the dimension
of the outlet flow path is set such that a ratio of a tapered angle
of the first tapered surface to a tapered angle of the second
tapered surface is higher as the sectional area of the parallel
flow path is smaller.
6. The method for manufacturing the ejector according to claim 5,
wherein at the preparation step, the diffuser having the outlet
flow path set at the setting step is prepared by replacement of a
replaceable attachment of the diffuser including the
attachment.
7. A method for setting an outlet flow path of a diffuser including
an outlet flow path having a narrowed flow path having a first
tapered surface narrowed toward downstream, a parallel flow path
connected to a downstream end of the narrowed flow path and having
a constant sectional area, and an expanded flow path connected to a
downstream end of the parallel flow path and having a second
tapered surface expanded toward downstream and used for an ejector,
comprising: a step of setting a sectional area of the parallel flow
path; and a step of setting a dimension of the outlet flow path
such that a ratio of a tapered angle of the first tapered surface
to a tapered angle of the second tapered surface is higher as the
sectional area of the parallel flow path is smaller.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This is a continuation of PCT International Application No.
PCT/JP2017/005469 filed on Feb. 15, 2017, which claims priority to
Japanese Patent Application No. 2016-074570 field on Apr. 1, 2016.
The disclosures of these applications including the specifications,
the drawings, and the claims are hereby incorporated by reference
in their entirety.
FIELD
[0002] The technique disclosed herein relates to an ejector
configured to suck second fluid by negative pressure generated by
ejection of first fluid to discharge the second fluid together with
the first fluid, the method for manufacturing the ejector, and the
method for setting an outlet flow path of a diffuser used for the
ejector.
BACKGROUND
[0003] For example, a general ejector is disclosed in Japanese
Patent Publication No. 2000-356305. In this ejector, negative
pressure (pressure drop) is generated by ejection of first fluid
(drive fluid) from an injection port, and second fluid (drive
target fluid) is sucked by the negative pressure. Then, the first
fluid and the second fluid are mixed and discharged from a diffuser
(an outlet). An expanded flow path (a flow path whose flow path
sectional area increases toward a downstream side) is provided at
the diffuser. When the fluid mixture of the first fluid and the
second fluid flows in the expanded flow path, the velocity of the
fluid mixture decreases, and the pressure of the fluid mixture
increases. The fluid mixture discharged from the ejector as
described above is supplied to, e.g., an apparatus on the
downstream side of the ejector.
SUMMARY
[0004] In the above-described ejector, a discharge pressure might
change due to, e.g., a change in operation conditions (the usage
amount or usage pressure of the fluid mixture) of the apparatus as
a steam supply destination. For example, when the operation of
temporarily decreasing the usage amount of the fluid mixture in the
apparatus as the supply destination or temporarily increasing the
usage pressure is performed, the discharge flow rate of the ejector
decreases, and the discharge pressure increases. When the discharge
pressure becomes too high, the second fluid is less sucked, and
eventually, the suction flow rate of the second fluid significantly
decreases. In this case, an ejector configured so that a sufficient
suction flow rate of second fluid can be ensured until the highest
possible discharge pressure has been demanded.
[0005] Performance of the ejector such as the discharge pressure of
the fluid mixture and the suction flow rate of the second fluid
varies according to the specifications, i.e., the dimensions, of
the flow path of the diffuser. Note that various dimensions of the
flow path of the diffuser influence the performance of the ejector,
and for this reason, a change in the dimensions of the diffuser
might lower the performance of the ejector.
[0006] The technique disclosed herein has been made in view of the
above-described situation, and an object of the technique is to
reduce degradation of the performance of the ejector upon a
simultaneous change of an upper discharge pressure limit for
ensuring a second fluid suction flow rate.
[0007] The ejector disclosed herein includes a nozzle configured to
eject first fluid, a suction chamber configured to house the nozzle
and to suck second fluid by negative pressure generated by ejection
of the first fluid from the nozzle, and a diffuser including an
outlet flow path and configured to mix and discharge the first
fluid and the second fluid of the suction chamber. The outlet flow
path includes a narrowed flow path having a first tapered surface
narrowed toward downstream, a parallel flow path connected to a
downstream end of the narrowed flow path and having a constant
sectional area, and an expanded flow path connected to a downstream
end of the parallel flow path and having a second tapered surface
expanded toward downstream. The diffuser further includes a
changing unit configured to change the dimensions of the outlet
flow path. The changing unit changes the dimensions of the outlet
flow path such that the ratio of the tapered angle of the first
tapered surface to the tapered angle of the second tapered surface
is higher as the sectional area of the parallel flow path is
smaller.
[0008] Moreover, the method for manufacturing the ejector as
disclosed herein includes the setting step of setting the
dimensions of the outlet flow path, and the preparation step of
preparing the diffuser having the dimensions of the outlet flow
path set at the setting step. At the setting step, the dimensions
of the outlet flow path are set such that the ratio of the tapered
angle of the first tapered surface to the tapered angle of the
second tapered surface is higher as the sectional area of the
parallel flow path is smaller.
[0009] Further, the method for setting the outlet flow path of the
diffuser as disclosed herein includes the step of setting the
sectional area of the parallel flow path, and the step of setting
the dimensions of the outlet flow path such that the ratio of the
tapered angle of the first tapered surface to the tapered angle of
the second tapered surface is higher as the sectional area of the
parallel flow path is smaller.
[0010] According to the above-described ejector, while the upper
discharge pressure limit for ensuring the suction flow rate of the
second fluid can be changed, degradation of the performance of the
ejector can be reduced upon such a change.
[0011] According to the above-described method for manufacturing
the ejector, the ejector can be provided, which is configured to
reduce degradation of the performance of the ejector upon a
simultaneous change of the upper discharge pressure limit for
ensuring the suction flow rate of the second fluid.
[0012] According to the above-described method for setting the
outlet flow path of the diffuser, the ejector can be realized,
which is configured to reduce degradation of the performance of the
ejector upon a simultaneous change of the upper discharge pressure
limit for ensuring the suction flow rate of the second fluid.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a schematic view of a configuration of an ejector
according to an embodiment.
[0014] FIG. 2 is a graph of a relationship between a discharge
pressure and a suction flow rate.
[0015] FIG. 3 is a schematic sectional view of a diffuser to which
a first attachment is attached.
[0016] FIG. 4 is a schematic sectional view of a diffuser to which
a second attachment is attached.
DESCRIPTION OF EMBODIMENTS
[0017] Hereinafter, an exemplary embodiment will be described in
detail with reference to the drawings.
[0018] An ejector 10 is a steam ejector configured to suck
low-pressure steam (second fluid) by ejection of high-pressure
steam (first fluid), thereby mixing and discharging these types of
steam. That is, in the ejector 10, the high-pressure steam is drive
fluid, and the low-pressure steam is suction fluid. The ejector 10
includes a nozzle 20, a suction chamber 30, and a diffuser 40.
[0019] An inflow pipe 91 connected to a high-pressure steam supply
source is connected to the nozzle 20. The nozzle 20 is configured
to eject the supplied high-pressure steam. A tip end portion of the
nozzle 20 is housed in the suction chamber 30.
[0020] A low-pressure steam suction port 31 is provided at the
suction chamber 30. Using negative pressure (pressure drop)
generated by ejection of the high-pressure steam from the nozzle
20, the low-pressure steam is sucked into the suction chamber 30
through the suction port 31. That is, in the suction chamber 30,
suction force for sucking the low-pressure steam is generated by
the negative pressure generated by a jet pump effect of the
high-pressure steam. A suction pipe 92 connected to a low-pressure
steam supply source is connected to the suction port 31.
[0021] The diffuser 40 is connected to the suction chamber 30. The
diffuser 40 is configured to mix and discharge the high-pressure
steam ejected to the suction chamber 30 and the low-pressure steam
sucked into the suction chamber 30. An outflow pipe 93 connected to
a steam mixture supply destination is connected to a downstream end
of the diffuser 40.
[0022] The diffuser 40 has a divided structure including an
upstream portion 41, an attachment 42, and a downstream portion 43.
An upstream end of the upstream portion 41 is connected to the
suction chamber 30. A flange 41a is provided at a downstream end of
the upstream portion 41. A first flange 43a is provided at an
upstream end of the downstream portion 43, and a second flange 43b
is provided at a downstream end of the downstream portion 43. The
downstream portion 43 is connected to the outflow pipe 93 through
the second flange 43b. The attachment 42 is sandwiched between the
upstream portion 41 and the downstream portion 43. The flange 41a
of the upstream portion 41 and the first flange 43a of the
downstream portion 43 are fastened with bolts 44, and in this
manner, the attachment 42 is held by the upstream portion 41 and
the downstream portion 43. That is, the attachment 42 can be
replaced by loosening of the fastened bolts 44. The attachment 42
is one example of a changing unit.
[0023] An outlet flow path 50 of the high-pressure steam and the
low-pressure steam is formed at the diffuser 40, the outlet flow
path 50 communicating with the suction chamber 30. The outlet flow
path 50 includes a narrowed flow path 51, a parallel flow path 52,
and an expanded flow path 53 in this order from an upstream side.
The section of the outlet flow path 50 is in a substantially
circular shape. The diffuser 40 decreases the velocity of the steam
mixture and increases the pressure of the steam mixture when the
steam mixture flows in the expanded flow path 53.
[0024] An upstream end of the narrowed flow path 51 opens to the
suction chamber 30. The upstream end of the narrowed flow path 51
faces a downstream end of the nozzle 20 in the suction chamber 30.
The sectional area, i.e., the inner diameter, of the narrowed flow
path 51 gradually decreases toward a downstream side. That is, the
narrowed flow path 51 has a first tapered surface 54 narrowed
toward the downstream side. The parallel flow path 52 is connected
to a downstream end of the narrowed flow path 51. The parallel flow
path 52 is a flow path having a constant sectional area, i.e., a
constant inner diameter. The parallel flow path 52 is a portion
having the smallest inner diameter in the outlet flow path 50, and
forms a so-called throat portion. The expanded flow path 53 is
connected to a downstream end of the parallel flow path 52. The
sectional area, i.e., the inner diameter, of the expanded flow path
53 gradually increases toward the downstream side. That is, the
expanded flow path 53 has a second tapered surface 55 expanded
toward the downstream side.
[0025] The narrowed flow path 51 is formed from the upstream
portion 41 to the attachment 42. The parallel flow path 52 is
formed at the attachment 42. The expanded flow path 53 is formed
from the attachment 42 to the downstream portion 43. That is, at
least an upstream end portion of the narrowed flow path 51 is
formed at the upstream portion 41. At least a downstream end
portion of the narrowed flow path 51, the parallel flow path 52,
and at least an upstream end portion of the expanded flow path 53
are formed at the attachment 42. At least a downstream end portion
of the expanded flow path 53 is formed at the downstream portion
43.
[0026] In the ejector 10 configured as described above, the
high-pressure steam flowing in the inflow pipe 91 is ejected to the
suction chamber 30 through the nozzle 20, and the low-pressure
steam is sucked into the suction chamber 30 through the suction
port 31 by ejection of the high-pressure steam. Then, the
high-pressure steam and the low-pressure steam in the suction
chamber 30 are mixed together, and are discharged from the diffuser
40. The steam discharged from the diffuser 40 is supplied to an
apparatus on the downstream side. The flow velocity of the steam
mixture reaches about a sound velocity at the parallel flow path 52
of the diffuser 40. Thereafter, when the steam mixture flows in the
expanded flow path 53, the velocity of the steam mixture is
decreased, and the pressure of the steam mixture is increased.
[0027] The discharge pressure of the ejector 10 might increase
according to an operation status or a specification change of the
apparatus as the steam supply destination. However, as illustrated
in FIG. 2, there is an upper discharge pressure limit (this
discharge pressure will be hereinafter referred to as a "maximum
discharge pressure") for ensuring a low-pressure steam suction flow
rate in the ejector 10. When the discharge pressure increases
beyond the maximum discharge pressure Pmax, a suction pressure also
starts increasing. Eventually, the flow velocity in the parallel
flow path 52 decreases as compared to the sound velocity, and a
non-critical state is brought. Accordingly, the suction pressure
increases to a value substantially equal to the discharge pressure.
That is, when the discharge pressure exceeds the maximum discharge
pressure Pmax, the low-pressure steam suction flow rate decreases
rapidly.
[0028] The maximum discharge pressure Pmax can be changed according
to the specifications, i.e., the dimensions, of the outlet flow
path 50. The diffuser 40 is configured such that the dimensions of
the outlet flow path 50 is changeable by replacement of the
attachment 42.
[0029] For example, it is conceivable that the inner diameter D of
the parallel flow path 52 is decreased in order to increase the
maximum discharge pressure Pmax. With a decrease in the inner
diameter D of the parallel flow path 52, the flow velocity of the
steam mixture in the parallel flow path 52 increases, and
therefore, a critical state of the pressure in the parallel flow
path 52 is easily ensured.
[0030] However, when only the inner diameter D of the parallel flow
path 52 is changed, not only the maximum discharge pressure Pmax
cannot be increased, but also performance of the ejector 10 cannot
be maintained. For example, the low-pressure steam suction flow
rate might significantly decrease while the maximum discharge
pressure Pmax is increased. Conversely, the maximum discharge
pressure Pmax might decrease. That is, the performance of the
ejector 10 relates to various dimensions of the outlet flow path
50, and other dimensions of the parallel flow path 52 than the
inner diameter D need to be changed.
[0031] For these reasons, in the ejector 10, the dimensions of the
outlet flow path 50 are set such that the ratio (hereinafter
referred to as a "tapered angle ratio") .alpha./.beta. of the
tapered angle .alpha. of the first tapered surface 54 to the
tapered angle .beta. of the second tapered surface 55 is higher as
the sectional area, i.e., the inner diameter D, of the parallel
flow path 52 is smaller.
[0032] Specifically, the inner diameter D of the parallel flow path
52 is set smaller for a higher target maximum discharge pressure.
Moreover, for reducing degradation of the performance of the
ejector 10, the tapered angles .alpha., .beta. are set such that
the tapered angle ratio .alpha./.beta. is higher as the inner
diameter D is smaller.
[0033] In the diffuser 40, the upstream portion 41 and the
downstream portion 43 are not replaceable. Thus, the entire length
of the attachment 42, the inner diameter of the narrowed flow path
51 at an upstream end of the attachment 42, and the inner diameter
of the expanded flow path 53 at a downstream end of the attachment
42 are not changed. Thus, according to a change in the inner
diameter D, the tapered angle .alpha. of a portion of the first
tapered surface 54 formed at the attachment 42 and the tapered
angle .beta. of a portion of the second tapered surface 55 formed
at the attachment 42 are changed. Unless otherwise stated, the
"tapered angle .alpha." and the "tapered angle .beta." will
hereinafter mean the tapered angles of the tapered surface portions
formed at the attachment 42.
[0034] The tapered angle .alpha. of the first tapered surface 54 is
changed greater for a smaller inner diameter D. In this case, the
tapered angles .alpha., .beta. are set such that the tapered angle
ratio .alpha./.beta. is higher as the inner diameter D is smaller.
That is, in a case where at least one of the tapered angles
.alpha., .beta. needs to increase as the inner diameter D gets
lower, the tapered angle .alpha. is more increased, and an increase
in the tapered angle .beta. is suppressed.
[0035] For example, in a case where both of the tapered angles
.alpha., .beta. increase as the inner diameter D gets lower, the
tapered angles .alpha., .beta. are set such that the increase rate
of the tapered angle .alpha. (i.e., the tapered angle .alpha. after
change/the tapered angle .alpha. before change) is greater than the
increase rate of the tapered angle .beta. (i.e., the tapered angle
.beta. after change/the tapered angle .beta. before change).
[0036] In this manner, degradation of the performance of the
ejector 10 is reduced. Specifically, the tapered angle .alpha. of
the first tapered surface 54 and the tapered angle .beta. of the
second tapered surface 55 might influence turbulence of the flow of
the steam mixture. Greater angles result in more flow turbulence
due to separation. Greater flow turbulence results in lower
performance of the ejector 10. In the diffuser 40, the tapered
angle .beta. of the expanded flow path 53 more influences flow
turbulence as compared to the tapered angle .alpha. of the narrowed
flow path 51. Thus, in a case where the tapered angles .alpha.,
.beta. need to increase as the inner diameter D of the parallel
flow path 52 gets lower, the tapered angle .alpha. is more greatly
changed, and an increase in the tapered angle .beta. is suppressed.
In this manner, worsening of flow turbulence can be reduced, and
degradation of the performance of the ejector 10 can be
reduced.
[0037] In addition, for further reducing degradation of the
performance of the ejector 10, the length P of the parallel flow
path 52 is set shorter for a smaller inner diameter D.
Specifically, the length P of the parallel flow path 52 is set to
satisfy the following expression (1), i.e., in proportion to the
inner diameter D.
P=M.times.D (1),
where M represents a constant.
[0038] That is, even in a case where the dimensions of the parallel
flow path 52 are changed, the expression (1) is satisfied before
and after change. In other words, P/D is substantially equal
between before and after change.
[0039] Note that as a result of a larger tapered angle .alpha. for
a smaller inner diameter D, the length Q of the narrowed flow path
51 is also shorter as the inner diameter D gets smaller.
[0040] Moreover, the length of the expanded flow path 53 is set to
such a value that the performance of the ejector 10 is not
influenced even when the lengths of the narrowed flow path 51 and
the parallel flow path 52 are changed.
[0041] FIG. 3 is a schematic sectional view of the diffuser 40 to
which a first attachment 42A is attached, and FIG. 4 is a schematic
sectional view of the diffuser 40 to which a second attachment 42B
is attached.
[0042] The first attachment 42A has the parallel flow path 52 whose
inner diameter D is d1. In this case, the length p1 of the parallel
flow path 52 is M.times.d1. Moreover, the length of the narrowed
flow path 51 is q1. The tapered angle .alpha.1 of a portion of the
first tapered surface 54 formed at the first attachment 42A is the
same as the tapered angle .alpha.0 of a portion of the first
tapered surface 54 formed at the upstream portion 41. The tapered
angle .beta.1 of a portion of the second tapered surface 55 formed
at the first attachment 42A is the same as the tapered angle
.beta.0 of a portion of the second tapered surface 55 formed at the
downstream portion 43.
[0043] On the other hand, the second attachment 42B has the
parallel flow path 52 whose inner diameter D is d2. In this case,
the length p2 of the parallel flow path 52 at the second attachment
42B is M.times.d2. Moreover, the length of the narrowed flow path
51 is q2. The tapered angle .alpha.2 of a portion of the first
tapered surface 54 formed at the second attachment 42B is greater
than the tapered angle .alpha.0 of the portion of the first tapered
surface 54 formed at the upstream portion 41. The tapered angle
.beta.2 of a portion of the second tapered surface 55 formed at the
second attachment 42B is greater than the tapered angle .beta.0 of
the portion of the second tapered surface 55 formed at the
downstream portion 43.
[0044] The inner diameter d2 of the parallel flow path 52 of the
second attachment 42B is smaller than the inner diameter d1 of the
parallel flow path 52 of the first attachment 42A, and therefore,
the parallel flow path 52 of the second attachment 42B is shorter
than the parallel flow path 52 of the first attachment 42A.
[0045] In this case, in association with a smaller inner diameter
d2 than the inner diameter d1, the tapered angle .alpha.2 of the
first tapered surface 54 of the second attachment 42B is greater
than the tapered angle .alpha. 1 of the first tapered surface 54 of
the first attachment 42A, and the tapered angle .beta.2 of the
second tapered surface 55 of the second attachment 42B is greater
than the tapered angle .beta.1 of the second tapered surface 55 of
the first attachment 42A. In this case, the tapered angle ratio
.alpha.2/.beta.2 of the second attachment 42B is greater than the
tapered angle ratio .alpha.1/.beta.1 of the first attachment 42A.
That is, when the inner diameter D is changed from d1 to d2, the
increase rate of the tapered angle .alpha. is greater than the
increase rate of the tapered angle .beta..
[0046] Note that in association with an increase in the tapered
angle .alpha., the length Q of the narrowed flow path 51 decreases
from q1 to q2.
[0047] As described above, the inner diameter d2 of the parallel
flow path 52 of the second attachment 42B is smaller than that of
the first attachment 42A, and therefore, the maximum discharge
pressure Pmax of the diffuser 40 into which the second attachment
42B is incorporated is higher than that in the case of
incorporating the first attachment 42A. In this case, the tapered
angle .alpha. is more increased, and an increase in the tapered
angle .beta. is suppressed. In this manner, degradation of the
performance of the ejector 10 is reduced. Specifically, the tapered
angle .alpha. of the first tapered surface 54 and the tapered angle
.beta. of the second tapered surface 55 are increased, and
therefore, flow turbulence might occur. However, the tapered angle
.alpha. of the first tapered surface 54 is more increased, and an
increase in the tapered angle .beta. of the second tapered surface
55 is suppressed. Thus, worsening of flow turbulence can be
reduced. As a result, the maximum discharge pressure Pmax can be
increased with a sufficient suction flow rate being ensured. Note
that the inner diameter D of the parallel flow path 52 is
decreased, and therefore, the low-pressure steam suction flow rate
is slightly decreased.
[0048] Note that from a different point of view, the portion of the
first tapered surface 54 formed at the upstream portion 41 and the
portion of the second tapered surface 55 formed at the downstream
portion 43 are not changed, and therefore, the tapered angle ratio
.alpha.2/.beta.2 at the second attachment 42B is, with reference to
the tapered angle .alpha.0 at the upstream portion 41 and the
tapered angle .beta.0 at the downstream portion 43, greater than
the tapered angle ratio .alpha.0/.beta.0 at the upstream portion 41
and the downstream portion 43. That is, in a case where at least
one of the tapered angles .alpha., .beta. of the attachment 42 is
greater than the tapered angles .alpha.0, .beta.0 at the upstream
portion 41 and the downstream portion 43, the tapered angle .alpha.
is more increased as compared to the tapered angle .beta., and an
increase in the tapered angle .beta. is suppressed.
[0049] Further, the relationship of the expression (1) is
maintained before and after change in the dimensions of the outlet
flow path 50. That is, p2/d2 is substantially equal to p1/d1. This
also reduces degradation of the performance of the ejector 10.
[0050] As a result, the low-pressure steam suction flow rate can be
ensured even when the discharge pressure of the ejector 10
increases due to the operation status or the specification change
of the apparatus as the steam supply destination.
[0051] Subsequently, the method for manufacturing the
above-described ejector 10 will be described.
[0052] Specifically, the method for manufacturing the ejector 10
includes the setting step of setting the dimensions of the outlet
flow path 50, and the preparation step of preparing the diffuser 40
having the dimensions set at the setting step.
[0053] At the setting step, the inner diameter D and the length P
of the parallel flow path 52, the tapered angle .alpha. of the
first tapered surface 54, and the tapered angle .beta. of the
second tapered surface 55 at the attachment 42 are set. At this
step, the tapered angles .alpha., .beta. are set such that the
tapered angle ratio .alpha./.beta. is higher as the sectional area,
i.e., the inner diameter D, of the parallel flow path 52 is
smaller.
[0054] For example, the inner diameter D (i.e., the sectional area)
of the parallel flow path 52 is set so that the target maximum
discharge pressure can be realized. With the inner diameter D, the
length P of the parallel flow path 52 is set based on the
expression (1). Then, the tapered angles .alpha., .beta. are set
such that the tapered angle ratio .alpha./.beta. is higher as the
inner diameter D is smaller. A relationship among the inner
diameter D and the tapered angles .alpha., .beta. is obtained in
advance. With the inner diameter D, the corresponding tapered
angles .alpha., .beta. are set.
[0055] When the length P of the parallel flow path 52 and the
tapered angles .alpha., .beta. are set, the length of the narrowed
flow path 51 and the length Q of the expanded flow path 53 are
inevitably determined from the entire length of the attachment
42.
[0056] At the preparation step, the diffuser 40 having the
dimensions of the outlet flow path 50 set at the setting step is
prepared. For example, the attachment 42 having the dimensions of
the outlet flow path 50 set at the setting step is produced.
Alternatively, the attachment 42 suitable for the operation status
or the specifications of the apparatus as the steam supply
destination is selected from multiple attachments 42 having
different inner diameters D of the narrowed flow path 51 and having
a greater tapered angle ratio .alpha./.beta. for a smaller inner
diameter D.
[0057] The method for manufacturing the ejector 10 further includes
an assembly step. At the assembly step, the nozzle 20, the suction
chamber 30, and the diffuser 40 are assembled together.
Specifically, the nozzle 20 and the upstream portion 41 of the
diffuser 40 are attached to the suction chamber 30. Then, the
attachment 42 and the downstream portion 43 are attached to the
upstream portion 41 with the attachment 42 being sandwiched between
the upstream portion 41 and the downstream portion 43.
[0058] Alternatively, in a case where a new ejector 10 is
manufactured by replacement of the attachment 42 of the
already-assembled ejector 10, the attachment 42 having a smaller
inner diameter D and a greater tapered angle ratio .alpha./.beta.
than those before replacement is prepared at the preparation step.
Such an attachment 42 is newly produced, or is selected from
multiple attachments 42. Then, the attachment 42 of the ejector 10
is replaced with the attachment 42 prepared at the preparation
step.
[0059] As described above, the ejector 10 includes the nozzle 20
configured to eject the high-pressure steam (the first fluid), the
suction chamber 30 configured to house the nozzle 20 and to suck
the low-pressure steam (the second fluid) by the negative pressure
generated by ejection of the high-pressure steam from the nozzle
20, and the diffuser 40 having the outlet flow path 50 and
configured to mix and discharge the high-pressure steam and the
low-pressure steam of the suction chamber 30. The outlet flow path
50 includes the narrowed flow path 51 having the first tapered
surface 54 narrowed toward the downstream side, the parallel flow
path 52 connected to the downstream end of the narrowed flow path
51 and having the constant sectional area, and the expanded flow
path 53 connected to the downstream end of the parallel flow path
52 and having the second tapered surface 55 expanded toward the
downstream side. The diffuser 40 further includes the attachment 42
(the changing unit) configured to change the dimensions of the
outlet flow path 50. The attachment 42 changes the dimensions of
the outlet flow path 50 such that the ratio .alpha./.beta. of the
tapered angle .alpha. of the first tapered surface 54 to the
tapered angle .beta. of the second tapered surface 55 is higher as
the sectional area of the parallel flow path 52 is smaller.
[0060] According to this configuration, the dimensions of the
outlet flow path 50 are changed by the attachment 42. Upon such a
change, when the sectional area, i.e., the inner diameter D, of the
parallel flow path 52 is changed, the maximum discharge pressure
Pmax of the ejector 10 can be changed. In this case, the dimensions
of the outlet flow path 50 are set such that the tapered angle
ratio .alpha./.beta. is higher as the sectional area of the
parallel flow path 52 is smaller. That is, in a case where at least
one of the tapered angles .alpha., .beta. needs to be increased in
response to a decrease in the sectional area of the parallel flow
path 52, the tapered angle .alpha. is more increased, and an
increase in the tapered angle .beta. is suppressed. In this manner,
the maximum discharge pressure Pmax of the ejector 10 can be
changed. In addition, flow disturbance due to an increase in the
tapered angles .alpha., .beta. can be reduced, and degradation of
the performance of the ejector 10 can be reduced.
[0061] Moreover, the attachment 42 changes the dimensions of the
outlet flow path 50 such that the length P of the parallel flow
path 52 is shorter as the sectional area of the parallel flow path
52 is smaller.
[0062] According to this configuration, not only the sectional area
but also the length P of the parallel flow path 52 are changed.
Thus, while degradation of the performance of the ejector 10 can be
further reduced, the maximum discharge pressure Pmax can be
changed.
[0063] More specifically, the attachment 42 changes the dimensions
of the outlet flow path 50 such that the length P of the parallel
flow path 52 is changed in proportion to the inner diameter D of
the parallel flow path 52.
[0064] According to this configuration, a relationship between the
inner diameter D and the length P is held constant before and after
change in the dimensions of the parallel flow path 52. Thus, while
degradation of the performance of the ejector 10 can be reduced,
the maximum discharge pressure Pmax can be changed.
[0065] Further, part of the diffuser 40 is formed from the
replaceable attachment 42. The attachment 42 includes at least part
of the narrowed flow path 51, the parallel flow path 52, and at
least part of the expanded flow path 53. The dimensions of the
outlet flow path 50 are changed by replacement of the attachment
42.
[0066] That is, the diffuser 40 is configured such that the
attachment 42 is replaceable. The outlet flow paths 50 with
different dimensions are formed at multiple attachments 42. In
comparison among the attachments 42 with different sectional areas,
i.e., different inner diameters D, of the parallel flow path 52,
the tapered angle ratio .alpha./.beta. at the attachment 42 with a
smaller inner diameter D is greater than the tapered angle ratio
.alpha./.beta. at the attachment 42 with a greater inner diameter
D. As a result, the maximum discharge pressure Pmax of the ejector
10 can be changed by replacement of the attachment 42 without the
need for replacement of the entirety of the diffuser 40, and
degradation of the performance of the ejector 10 can be reduced.
Moreover, it is not necessary to replace the entirety of the
ejector 10, and therefore, the dimensions of the outlet flow path
50 can be easily changed.
[0067] In addition, the method for manufacturing the ejector 10
includes the setting step of setting the dimensions of the outlet
flow path 50, and the preparation step of preparing the diffuser 40
having the dimensions of the outlet flow path 50 set at the setting
step. At the setting step, the dimensions of the outlet flow path
50 are set such that the ratio .alpha./.beta. of the tapered angle
.alpha. of the first tapered surface 54 to the tapered angle .beta.
of the second tapered surface 55 is higher as the sectional area of
the parallel flow path 52 is smaller.
[0068] According to this configuration, while degradation of the
performance of the ejector 10 can be reduced, the ejectors 10 with
different maximum discharge pressures Pmax can be manufactured.
[0069] Moreover, at the preparation step, the diffuser 40 having
the outlet flow path 50 set at the setting step is prepared by
replacement of the attachment 42 of the diffuser 40 including the
replaceable attachment 42.
[0070] That is, the dimensions of the outlet flow path 50 of the
diffuser 40 are changed by replacement of the attachment 42. Thus,
the dimensions of the narrowed flow path 51 and the parallel flow
path 52 can be changed without the need for changing the entirety
of the diffuser 40.
[0071] Moreover, the method for setting the outlet flow path of the
diffuser 40 includes the step of setting the sectional area of the
parallel flow path 52, and the step of setting the dimensions of
the outlet flow path 50 such that the ratio .alpha./.beta. of the
tapered angle .alpha. of the first tapered surface 54 to the
tapered angle .beta. of the second tapered surface 55 is higher as
the sectional area of the parallel flow path 52 is smaller.
OTHER EMBODIMENTS
[0072] As described above, the embodiment has been described as an
example of the technique disclosed in the present application.
However, the technique of the present disclosure is not limited to
above, and is also applicable to embodiments to which changes,
replacements, additions, omissions, etc. are made as necessary.
Moreover, each component described above in the embodiment may be
combined to form a new embodiment. Further, the components
described in the detailed description with reference to the
attached drawings may include not only components essential for
solving the problems, but also components not essential for solving
the problems and provided for illustrating the above-described
technique by an example. Thus, description of the non-essential
components in the detailed description with reference to the
attached drawings should not be directly recognized as these
non-essential components being essential.
[0073] The above-described embodiment may have the following
configurations.
[0074] The diffuser 40 has the structure divided into three
portions, but may have a structure divided into two portions or
four or more portions.
[0075] Moreover, the method for fixing the attachment 42 is not
limited to sandwiching between the upstream portion 41 and the
attachment 42. As long as the attachment 42 can be fixed, an
optional fixing method can be employed.
[0076] Further, the configuration for changing the dimensions of
the outlet flow path 50 is not limited to the configuration by the
attachment 42. For example, the diffuser may include a deformable
mechanism capable of changing the inner diameter. The deformable
mechanism may have a tubular wall portion configured to form the
outlet flow path 50 and exhibiting flexibility, and multiple
pressing members (e.g., bolts) arranged at the outer periphery of
the wall portion in a circumferential direction and configured to
press the wall portion inward in a radial direction. The wall
portion is deformed in such a manner that the wall portion is
pressed inward in the radial direction by the pressing member.
Accordingly, the inner diameter of the wall portion is decreased.
Thus, the inner diameter D, i.e., the sectional area, of the
parallel flow path 52 can be changed. Further, multiple sets of the
pressing members are provided at different positions of the wall
portion in an axial direction thereof, multiple pressing members
arranged in the circumferential direction of the wall portion being
taken as a single set. That is, depending on at which positions in
the axial direction the pressing members are pressed, the length Q
of the narrowed flow path 51 can be changed. Furthermore, the
tapered angle .alpha. of the first tapered surface 54, the length Y
of the parallel flow path 52, and the length of the expanded flow
path 53 can be changed.
[0077] Furthermore, the tapered angle .beta. of the second tapered
surface 55 can be changed. In other configurations than above, an
optional configuration capable of changing the dimensions of the
outlet flow path 50 can be employed.
[0078] Further, the diffuser 40 has the divided structure including
the attachment 42, but is not limited to above. For example, the
diffuser 40 may have an integrated structure. In this case,
multiple diffusers 40 each have the outlet flow paths 50 with
different dimensions, and each diffuser 40 is configured such that
the tapered angle ratio .alpha./.beta. is higher as the inner
diameter D is smaller. Among these diffusers 40, the suitable
diffuser 40 is selected, and is incorporated into the ejector 10.
That is, at the preparation step in the method for manufacturing
the ejector 10, the diffuser 40 having the dimensions (the inner
diameter D and the tapered angles .alpha., .beta.) of the outlet
flow path 50 set at the setting step is selected from multiple
diffusers 40, or is newly produced.
[0079] In the examples of FIGS. 3 and 4 as described above, both of
the tapered angle .alpha. of the first tapered surface 54 and the
tapered angle .beta. of the second tapered surface 55 are increased
in such a manner that the inner diameter D is decreased from d1 to
d2, but the present invention is not limited to these examples.
While the tapered angle .alpha. increases as the inner diameter D
gets smaller, the tapered angle .beta. may be held constant or may
decrease. Even in this case, an increase in the tapered angle
.beta. is suppressed, and worsening of the flow is reduced.
[0080] The technique disclosed herein is useful for the ejector,
the method for manufacturing the ejector, and the method for
setting the outlet flow path of the diffuser used for the
ejector.
* * * * *