U.S. patent application number 16/589114 was filed with the patent office on 2021-04-01 for systems and methods of centrifugal moving wave compressors.
This patent application is currently assigned to Ingersoll-Rand Company. The applicant listed for this patent is Ingersoll-Rand Company. Invention is credited to Charles John Bergh.
Application Number | 20210095688 16/589114 |
Document ID | / |
Family ID | 1000004657233 |
Filed Date | 2021-04-01 |
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United States Patent
Application |
20210095688 |
Kind Code |
A1 |
Bergh; Charles John |
April 1, 2021 |
SYSTEMS AND METHODS OF CENTRIFUGAL MOVING WAVE COMPRESSORS
Abstract
Aspects of this disclosure provide a centrifugal impeller having
a plurality of constant area shrouded channels that inlet or outlet
gas when the channel passes stator inlet port or exit port. The
stator walls and ports are located closely adjacent the inside
diameter (ID) and outside diameter (OD) of the impeller channel
openings, allowing gas to enter or exit a channel of the impeller
as the shrouded channel passes a stator port and allows gas to be
contained within a channel of the impeller as the shrouded channel
passes a stator wall. Further, the impeller reuses the pressurized
gas flow by reinjecting the pressurized gas flow back into the ID
of the impeller via a second inlet port and utilizing moving wave
compression energy. The combination and sequence centrifugal
processes and moving wave processes create a higher stage pressure
ratio, at lower gas flow, with high gas flow turndown as compared
to a conventional centrifugal compressor with similar dimensions
and operating speed.
Inventors: |
Bergh; Charles John;
(Berwyn, PA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ingersoll-Rand Company |
Davidson |
NC |
US |
|
|
Assignee: |
Ingersoll-Rand Company
Davidson
NC
|
Family ID: |
1000004657233 |
Appl. No.: |
16/589114 |
Filed: |
September 30, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04D 29/284 20130101;
F04D 17/10 20130101 |
International
Class: |
F04D 29/28 20060101
F04D029/28; F04D 17/10 20060101 F04D017/10 |
Claims
1. A method of compressing air comprising: increasing velocity of
air flow, via centrifugal energy, within sequential channels of a
centrifugal impeller; capturing the air flow from the sequential
channels; reloading at least some of the captured air flow into
sequential channels of the centrifugal impeller; increasing
pressure of the reloaded air flow by inducing at least one
shockwave traveling in a same direction as the centrifugal energy;
increasing pressure of the reloaded air flow by inducing at least
one shockwave traveling opposite the centrifugal energy;
discharging the increased pressure reloaded air flow from the
sequential channels.
2. The method of claim 1 further comprising: increasing pressure of
the reloaded air flow by inducing at least one additional shockwave
traveling in the same direction as the centrifugal energy.
3. The method of claim 2 wherein the pressure of the reloaded air
flow resulting from the at least one additional shockwave traveling
in the same direction as the centrifugal energy is comparatively
higher than the pressure of the reloaded air flow resulting from
pressure of the reloaded air flow by inducing at least one
shockwave traveling opposite the centrifugal energy.
4. The method of claim 1 further comprising: inducing an adjustment
wave after the discharging.
5. The method of claim 1 further comprising: angularly locating at
least one barrier adjacent the centrifugal impeller, wherein the
reloaded air flow within the sequential channels of the centrifugal
impeller collides with the at least one barrier.
6. The method of claim 1 further comprising: radially locating at
least one barrier adjacent the centrifugal impeller, wherein the
reloaded air flow within the sequential channels of the centrifugal
impeller collides with the at least one barrier.
7. The method of claim 1 further comprising: capturing the
discharged air flow; injecting at least some of the captured
discharged air flow into sequential channels of another centrifugal
impeller.
8. The method of claim 1 further comprising: cooling at least some
of the capturing the air flow prior to the reloading.
9. The method of claim 1 further comprising: changing a speed of
the centrifugal impeller.
10. A gas compressor comprising: a centrifugal impeller configured
to increase velocity of air flow, via centrifugal energy, within
sequential channels of a centrifugal impeller; at least one port
that captures the air flow from the sequential channels; at least
one reload port that reloads the at least some captured air flow
into sequential channels of the centrifugal impeller; and a stator
comprising at least one radially located barrier operable to
increase pressure of the reloaded air flow within the sequential
channels by inducing at least one shockwave of controllable
strength traveling a same direction as the centrifugal energy.
11. The gas compressor of claim 10 wherein the stator further
comprises at least another angularly located barrier operable to
increase pressure of the reloaded air flow by inducing at least one
other shockwave traveling opposite direction of the centrifugal
energy.
12. The gas compressor of claim 10 wherein the stator further
comprises at least an additional angularly located barrier operable
to increase pressure of the reloaded air flow by inducing at least
one other shockwave traveling a same direction as the centrifugal
energy.
13. The gas compressor of claim 10 further comprising: a discharge
port that discharges the increased pressure reloaded air flow from
the sequential channels.
14. The gas compressor of claim 13 wherein at least some of the
discharged air flow is injected into sequential channels of another
centrifugal impeller.
15. The gas compressor of claim 14 further comprising: at least one
cooling unit operable to cool at least some of the discharged air
flow prior to the injecting.
16. The gas compressor of claim 10 further comprising: at least one
cooling unit operable to cool at least some of the captured the air
flow prior to the reload port.
17. The gas compressor of claim 10 wherein the centrifugal impeller
is one of: radial inlet and radial outlet; and axial inlet and
axial outlet.
18. The gas compressor of claim 10 wherein the centrifugal impeller
is radial inlet and axial outlet.
19. The gas compressor of claim 10 wherein the centrifugal impeller
is axial inlet and radial outlet.
20. A method of compressing air comprising: increasing velocity of
air flow, via centrifugal energy, within sequential channels of a
centrifugal impeller; capturing the air flow from the sequential
channels; reloading at least some of the captured air flow into
sequential channels of the centrifugal impeller; increasing
pressure of the reloaded air flow by inducing at least one
shockwave traveling in the same direction as the centrifugal
energy; increasing pressure of the reloaded air flow by inducing at
least one shockwave traveling opposite the centrifugal energy;
increasing pressure of the reloaded air flow by inducing at least
one other shockwave traveling opposite the centrifugal energy;
discharging the increased pressure reloaded air flow from the
sequential channels; and angularly locating at least one barrier
adjacent the centrifugal impeller, wherein the reloaded air flow
within the sequential channels of the centrifugal impeller collides
with the at least one barrier.
Description
TECHNICAL FIELD
[0001] The present disclosure relates to gas compressors and, more
specifically but without limitation, centrifugal gas compressor
systems and methods utilizing shockwave energy.
BACKGROUND
[0002] Conventional gas compressors may create and move pressurized
gas. Industries, such as oil refineries, chemical plants, natural
gas plants, typically use gas compressors for continuous,
stationary service. Additionally, ski resorts have used gas
compressors to generate large amounts of snow. Wave engines include
a compression function which compress gas using energy derived from
a thermal process, such as heat transfer or combustion, which
imparts expanding hot gas into compression energy to incoming gas
from expanding heated pressurized gas. Wave engines typically
utilize axial (as distinguished from radial) flow and derive no
compression energy from centrifugal action.
SUMMARY
[0003] A first aspect is directed to a method of compressing air.
Specifically, the method involves: increasing velocity of air flow,
via centrifugal energy, within sequential channels of a centrifugal
impeller; capturing the air flow from the sequential channels;
reloading at least some of the captured air flow into sequential
channels of the centrifugal impeller; increasing pressure of the
reloaded air flow by inducing at least one shockwave traveling in a
same direction as the centrifugal energy; increasing pressure of
the reloaded air flow by inducing at least one shockwave traveling
opposite the centrifugal energy; and discharging the increased
pressure reloaded air flow from the sequential channels.
[0004] In another aspect, the method includes increasing pressure
of the reloaded air flow by inducing at least one additional
shockwave traveling in the same direction as the centrifugal
energy.
[0005] In another aspect, the method includes the pressure of the
reloaded air flow resulting from the at least one additional
shockwave traveling in the same direction as the centrifugal energy
is comparatively higher than the pressure of the reloaded air flow
resulting from pressure of the reloaded air flow by inducing at
least one shockwave traveling opposite the centrifugal energy.
[0006] In another aspect, the method includes inducing an
adjustment wave after the discharging.
[0007] In another aspect, the method includes angularly locating at
least one barrier adjacent the centrifugal impeller, wherein the
reloaded air flow within the sequential channels of the centrifugal
impeller collides with the at least one barrier.
[0008] In another aspect, the method includes radially locating at
least one barrier adjacent the centrifugal impeller, wherein the
reloaded air flow within the sequential channels of the centrifugal
impeller collides with the at least one barrier.
[0009] In another aspect, the method includes capturing the
discharged air flow; injecting at least some of the captured
discharged air flow into sequential channels of another centrifugal
impeller.
[0010] In another aspect, the method includes cooling at least some
of the capturing the air flow prior to the reloading.
[0011] In another aspect, the method includes changing a speed of
the centrifugal impeller.
[0012] Another aspect is directed to a gas compressor. The gas
compressor includes a centrifugal impeller configured to increase
velocity of air flow, via centrifugal energy, within sequential
channels of a centrifugal impeller; at least one port that captures
the air flow from the sequential channels; at least one reload port
that reloads the at least some captured air flow into sequential
channels of the centrifugal impeller; and a stator comprising at
least one radially located barrier operable to increase pressure of
the reloaded air flow within the sequential channels by inducing at
least one shockwave of controllable strength traveling a same
direction as the centrifugal energy.
[0013] In another aspect, the gas compressor includes the stator
further comprises at least another angularly located barrier
operable to increase pressure of the reloaded air flow by inducing
at least one other shockwave traveling opposite direction of the
centrifugal energy.
[0014] In another aspect, the gas compressor includes the stator
further comprises at least an additional angularly located barrier
operable to increase pressure of the reloaded air flow by inducing
at least one other shockwave traveling a same direction as the
centrifugal energy.
[0015] In another aspect, the gas compressor includes a discharge
port that discharges the increased pressure reloaded air flow from
the sequential channels.
[0016] In another aspect, the gas compressor includes at least some
of the discharged air flow is injected into sequential channels of
another centrifugal impeller.
[0017] In another aspect, the gas compressor includes at least one
cooling unit operable to cool at least some of the discharged air
flow prior to the injecting.
[0018] In another aspect, the gas compressor includes at least one
cooling unit operable to cool at least some of the captured the air
flow prior to the reload port.
[0019] In another aspect, the gas compressor includes radial inlet
and radial outlet; and axial inlet and axial outlet.
[0020] In another aspect, the gas compressor includes the
centrifugal impeller is radial inlet and axial outlet.
[0021] In another aspect, the gas compressor includes the
centrifugal impeller is axial inlet and radial outlet.
[0022] Another aspect is directed to a method of compressing air.
Specifically, the method involves: increasing velocity of air flow,
via centrifugal energy, within sequential channels of a centrifugal
impeller; capturing the air flow from the sequential channels;
reloading at least some of the captured air flow into sequential
channels of the centrifugal impeller; increasing pressure of the
reloaded air flow by inducing at least one shockwave traveling in
the same direction as the centrifugal energy; increasing pressure
of the reloaded air flow by inducing at least one shockwave
traveling opposite the centrifugal energy; increasing pressure of
the reloaded air flow by inducing at least one other shockwave
traveling opposite the centrifugal energy; discharging the
increased pressure reloaded air flow from the sequential channels;
and angularly locating at least one barrier adjacent the
centrifugal impeller, wherein the reloaded air flow within the
sequential channels of the centrifugal impeller collides with the
at least one barrier.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 illustrates an example gas compressor.
[0024] FIG. 2A illustrates an example gas compressor.
[0025] FIG. 2B illustrates and describes example flow states across
moving waves of a channel of an example gas compressor.
[0026] FIG. 3 illustrates an example gas compressor an example of
gas compressor timing and sequences.
[0027] FIG. 4 is an example operating cycle diagram of an example
gas compressor.
[0028] FIG. 5 is an example turndown and control cycle diagram of
an example gas compressor.
[0029] FIG. 6 illustrates an example gas compressor in a complete
system.
[0030] FIG. 7 illustrates an example radial inlet, radial outlet
impeller section view of an example gas compressor.
[0031] FIG. 8 illustrates an example axial inlet, axial outlet
impeller of an example gas compressor.
[0032] FIG. 9 illustrates an example axial inlet, radial outlet
impeller section view of an example gas compressor.
[0033] FIG. 10 illustrates an example axial inlet, radial outlet
impeller and stator section view with two compression stages on a
single impeller of an example gas compressor.
[0034] FIGS. 11A and 11B illustrate example operating cycles
discharge flow data of example gas compressors.
[0035] FIG. 12 illustrates example pressure ratio for wave
processes compared to isentropic flow process.
[0036] FIG. 13 is a block diagram illustrating an example method of
operation of an gas compressor.
[0037] Corresponding reference characters indicate corresponding
parts throughout the drawings.
DETAILED DESCRIPTION
[0038] Aspects of this disclosure utilize centrifugal work to drive
an air flow, and controls shockwave strength to in a way that
increases the air pressure of the air flow. The embodiments and
examples described herein provide a centrifugal impeller including
sequential shrouded channels, having an open entry portion (e.g.,
at a small diameter) and an open exit portion (e.g., at a
comparatively larger diameter). The entry end of a channel and the
exit end of the channel become intermittently blocked by one or
more barriers as the centrifugal impeller rotates. The one or more
barriers may define one or more a stator inlet ports or exit ports,
which allows gas to enter or exit a sequential channels of the
impeller as the shrouded channel passes a port and allows gas to be
contained within a channel of the impeller as the shrouded channel
passes a barrier (e.g., barrier wall). In examples, the rotor may
rotate at a fixed speed, which may maintain the integrity of the
wave field and port flows.
[0039] While the impeller rotates, centrifugal force increases the
velocity of the gas flow within the sequential channels. In
examples, the air flow may be captured and reloaded into other
sequential channels of the same impeller. For example, as other
sequential channels of the same impeller pass a reload port, which
allows the captured air flow to reload into the passing sequential
channels. As the sequential channels pass by a barrier, the
velocity of the air flow causes the air flow to collide against the
barrier causing the air flow velocity to dramatically drop and
inducing a shockwave energized in the opposing direction of the
centrifugal force. Strategic radial and/or angular placement of the
barrier and/or the channels' shape and/or area provide a way to
contain the results of the waves in increased or decreased
pressure. As the impeller continues to rotate, the moving shockwave
energy increases the pressure of the air flow located within the
sequential channels. As the impeller continues to rotate, a
shockwave moving in the opposite direction increases the pressure
of the air flow located within the sequential channels. Further, if
desired, as the impeller continues to rotate, a shockwave moving in
the opposite direction increases the pressure of the air flow
located within the sequential channels. After the desired number of
shockwaves have occurred, as the impeller continues to rotate, the
sequential channels to pass by a port causing an opening of an exit
portion of the sequential channels. While the channel opens, the
pressurized gas flows out of the sequential channels.
[0040] While the impeller rotates, centrifugal force increases the
velocity of the gas flow during a reset phase, and shockwave energy
(and in examples, centrifugal force) increases the pressure of the
air flow curing a reload phase. Further rotation of the impeller
causes the sequential channels to pass by a port causing an opening
of an exit portion of the sequential channels during a discharge
phase. While the channel opens, the pressurized gas flows out of
the sequential channels. In examples, the discharge port is
delimited by an inward running expansion wave and by the arrival of
a reflected expansion wave.
[0041] Similar to typical centrifugal compressors, the gas enters
the channel at low velocity and low pressure. Rotation of the
impeller causes the individual shrouded channels to sequentially
pass by a gas inlet port. As such, the individual shrouded channels
are serially exposed to the gas inlet port causing the gas to
sequential enter the shrouded channels at low velocity and low
pressure. Also, similar to conventional centrifugal compressors,
rotation of the impeller creates centrifugal force that drives the
gas flow outward from the inside diameter (ID) of the stator toward
the outside diameter (OD) of the stator. The velocity of the flow
through a given channel begins at low velocity and increases as the
channel rotates through the arc defined by the inlet port [reset
process.
[0042] Conventional centrifugal compressors stop applying flow work
once the gas flow reaches the stator OD, and the pressurized gas
flow exits the stator through a volute moving to gas away from the
impeller and stator and downstream to next stage of the overall
system or to the user. As such, pressurized air provided by
conventional centrifugal compressors are limited based at least on
size and rotational speeds.
[0043] Systems and methods herein solve the above problems of
conventional centrifugal compressors by provide a way to contain
moving wave compression (e.g., shock waves) to create more
parameters that can be used to increase the gas flow's pressure,
while at the same time relying on centrifugal force to energy the
gas flow's velocity, which minimizes the complexity and component
part of the systems and methods. Traditionally, conventional
centrifugal compressors viewed shock waves, which typically occur
at the rotor blade tips, as a problem that rendered conventional
centrifugal compressors unstable. As such, the industry has
expended copious amounts of time, energy, and technology to
minimize, eliminate, or otherwise accomodate shock waves occurring
in conventional centrifugal compressors. As opposed to fighting
shock waves, systems and methods herein seek to harness moving
shock waves within the rotor channels in a manner that increases a
gas flow's pressure. By harnessing and using shock waves (which
achieve higher pressure ratios than isentropic flow process, which
allows more mass in the channels, which permits the rotor to do
more work), the same or more pressure is realized in the gas flow.
By compressing air according to systems and methods described
herein the same or more gas pressure may be generated with smaller
rotors, operating at slower revolutions per minute. The benefits
also include mechanical simplicity, high delivered pressure (for a
given gas, diameter and speed) at relatively low gas flow, with a
higher turn down capability (e.g., from 100% to 0% gas flow) at the
design pressure ratio.
[0044] Nonetheless, examples herein are fundamentally distinct from
conventional wave engines, which include a compression process,
which compress gas using wave processes but depend on a thermal
process, such as heat transfer or combustion, which creates an
increased volume of hot gas to create compression energy.
Conventional wave engines rely on thermal energy to drive and
increase the pressure of a gas flow. In contrast, examples
described herein rely on centrifugal force to drive and increase
the velocity of a gas flow. Relying on thermal energy (e.g.,
combustible engines) to drive an air flow is less energy efficient,
less environmentally sound, and significantly more mechanically
complex as compared to relying on centrifugal force to drive and
increase the velocity of a gas flow. Thus, examples described
herein provide substantial benefits over traditional wave
engines.
[0045] In examples, the channels are shrouded, with a constant
area, and the stator ID and OD housing closely follows the curve of
the impeller, and the sequential and rapid changes in the velocity
and pressure of the gas flow generate sequential moving (e.g.,
inward and outward running) shock waves and expansion waves as the
shrouded channels pass stator ports and walls.
[0046] The added centrifugal processes and moving wave processes
improves the steady gas flow discharge, as explained above.
Further, the centrifugal processes are initiated in sequence,
within a single rotation of a centrifugal impeller providing
improved control. Moreover, the close running ID and OD stator
walls reduce leakage from high pressure regions to low pressure
regions. The combination and sequence of centrifugal processes and
moving wave processes create a higher stage pressure ratio, at
lower gas flow, with high gas flow turndown as compared to a
conventional centrifugal compressor with similar dimensions and
operating speed. Energy is imparted to the gas flow by centrifugal
work, with multiple stages of work, and compression/shockwave
recovery of pressure on the impeller allow for the higher stage
pressure ratio. Since the processes are initiated in sectors of the
impeller rotation, less gas flow is processed than in a comparable
centrifugal compressor. The impeller has constant area shrouded
channels, radially oriented, with radial or axial inlets and with
radial or axial channel outlets. Further still, there are two exit
port gas flows per stage, each providing an opportunity to remove
heat from the gas flow, which further increases the compressor's
capacity.
[0047] In examples, changes of the angular location and of one or
more stator inlet ports shape may change the air flow presentation
to the rotor, which may be leveraged to increase optimization. In
examples, changes of the angular location and shape of one or more
stator exit ports change the acceptance of air flow, which may be
leveraged to minimize flow loss. In examples, changing the angular
location includes moving the leading edge and/or trailing edge of
the port. In examples, changes of shapes and positions of exit
diffusers may change the recovery of velocity head, which may be
leveraged to increase recover of velocity head.
[0048] In examples, systems and methods may vary the rotational
speed up or down slightly to mismatch the waves and resultant flows
in the ports (e.g., to permit reduced flows or recirculated flows).
Systems and methods may throttle the flow at the inlet port and/or
throttle the reload flow. Systems and methods may "pinch throat"
the discharge port.
[0049] The embodiments and examples described herein improve
traditional centrifugal compressors by reusing the pressurized gas
flow by injecting the pressurized gas flow back into the ID of the
impeller via a second inlet port, which adds additional centrifugal
energy to the gas flow before allowing the pressurized gas flow to
be delivered to a downstream system or otherwise exit the
compressor. For example, an exit port at the stator OD leads to a
second inlet port adjacent the inner diameter of the impeller.
Thus, the pressurized gas flow exiting the first exit port connects
back toward the stator ID reenters the impeller via a second gas
inlet port allowing the gas flow to enter a sequentially rotating
channel.
[0050] FIG. 1 is an exemplary block diagram illustrating an example
cross sectional view of a gas compressor 100. Gas compressor 100
includes an impeller 102 with radial channels 103a-103n having a
substantially constant area. The channels 103a-103n are enclosed
except at an opening 104 at an inner diameter (ID) and at an
opening 105 at an outer diameter (OD). Channel ID openings may be
radially or axially disposed. Channel OD openings may be radially
or axially disposed.
[0051] Impeller 102 is coupled to a shaft (not shown) supported by
bearings (not shown). The shaft is driven by a motor (not shown).
Gas compressor 100 includes a stator 106 with ports 107a-107d that
are adjacent and in close proximity to the impeller channel
openings 104 and 105. The ports 107a-107d may be disposed at
defined angular sectors of rotation, with defined relationships
between some of the port edges. Two ports conduct gas flow to the
impeller inlets. Two ports conduct gas flow away from the impeller
outlets. The stator 106 contains the various pressures created
within gas compressor 100, conducts gas flow, and converts pressure
to velocity at the inlet ports 107a-107b, which function as nozzles
and converts velocity to pressure at the exit ports 107c-107d,
which function as diffusers. The stator 106 supports the bearings
(not shown) and the coupling to the drive motor (not shown). Stator
walls run close to impeller channel openings and prevent leakage of
gas from high pressure regions to low pressure regions.
[0052] In examples, shaft bearings (not shown) may be included that
support the rotor. Further the shaft bearings may permit rotation,
locate rotor radially for close running of seals, locate rotor
axially for close running of seals, inhibit vibration, resist
unbalanced pressure forces--axial and radial.
[0053] Rotation of the impeller 106 exposes the impeller channel
openings sequentially to the stator ports and the leading edges and
trailing edges of the ports, initiating a sequence of gas flow
processes. In examples, Port 107a is the first inlet port, which is
adjacent to the impeller channel ID and admits low pressure gas
onto the impeller 102. Port 107c is the reset port, which is
adjacent to the impeller channel (OD) and conducts gas flow away
from the impeller 102 for reduction of velocity and recovery of
pressure after an initial stage of centrifugal compression. First
inlet port 107a and reload port 107c together enable gas flow on
the impeller 102 to reset from an initial state in the impeller
channels of substantially zero velocity and low pressure to a state
of relatively high velocity, at low pressure and at a centrifugal
pressure distribution dictated by the impeller dimensions and
rotational speed.
[0054] Port 107b is the reset port, which is adjacent to the
impeller channel ID, immediately after the inlet port 107a in the
sequence of rotation and in fluid connection with reload port 107c.
Reload port 107c admits the gas flow from OD reset port 107b back
onto the impeller 102 (e.g., reentrant gas flow) driving the
impeller gas flow to an even higher velocity and pressure caused by
an outward running moving shockwave 109. Ports 107a, 107b, and 107c
together create a high velocity gas flow through the impeller 102
at a first intermediate level of pressure.
[0055] The trailing edge of reload port 107c closes off the
impeller OD channel exit, bringing the gas flow to zero velocity on
the impeller 102 and initiating an inward running moving shockwave
110 that raises the pressure. When the inward running shockwave 110
reaches the ID of the impeller channel openings the trailing edge
of reset port 107b closes the opening and traps high pressure gas
on the impeller 102 causing the highest pressure within the
compressor cycle, and highest temperature. The gas flow has
substantially zero velocity relative to the impeller 102 and has a
centrifugal pressure distribution from ID to OD dictated by the
impeller dimensions and rotational speed.
[0056] Continued rotation of the impeller 102 exposes the channel
OD to the discharge port 107d, wherein gas flow is conducted away
from the impeller 102, for reduction of velocity and recovery of
pressure in a diffuser and then for delivery to a user or to a
subsequent compression stage (not shown). The static pressure in
discharge port 107d is lower than the peak pressure achieved on the
impeller 102. Opening of the impeller channel at the leading edge
of discharge port 107d initiates an inward running moving expansion
wave 111 that signals expansion of the gas flow into the discharge
port 107d. The expansion wave 111 reflects from the inner stator
wall adjacent to the impeller ID as an outward running moving
expansion wave 112, which brings gas flow on the impeller 102 to
substantially zero velocity relative to the impeller 102, at low
pressure relative to the impeller 102, with a pressure distribution
dictated by the impeller dimensions and rotational speed. When the
outward running expansion wave 112 reaches the impeller OD, the
trailing edge of discharge port 107d closes of the channel, causing
completion of the sequence, which may be repeated substantially
continuously. Further, when the outward running expansion wave 112
reaches the impeller OD, wave 113, which may be of relatively of
small strength and may be either an inward running expansion wave
or a shock wave, signals the opening of inlet port 107a and reload
port 107c to begin the reset process 114.
[0057] FIG. 2A illustrates an example gas compressor 200. In
example gas compressor 200 moving waves are initiated in four ways,
each following a threshold mismatch (e.g., near-instantaneous
mismatch) of pressure and/or velocity. Shockwave 209 is initiated
by the mismatch of total pressure and velocity as the impeller ID
channel opening is exposed to the reload port 207c. Shockwave 209
drives the flow on the impeller at the trailing edge of the inlet
port 107a to a higher velocity and pressure (e.g., highest velocity
of this partial rotation of the cycle). Shockwave 210 is initiated
by stoppage of the high velocity and intermediate pressure flow at
the trailing edge of the reset port 207b, positioned at location
214. Location 214 is enlarged on the right side of FIG. 2.
Shockwave 210 results in gas flow with zero velocity relative to
the impeller, at the highest pressure.
[0058] Expansion wave 211 is initiated by exposure of the impeller
OD opening to the discharge port 207n, at a static pressure less
than the pressure on the impeller, which occurs at location 215.
Location 215 is enlarged on the left side of FIG. 2. The expansion
wave 211 signals the flow to move, off of the impeller, into the
discharge port 207n. Expansion wave 212 is formed as expansion wave
211 reflects from the ID stator wall causing a mismatch of the
velocity defined by expansion wave 211 and the boundary condition
of the stator wall which is zero velocity.
[0059] Since channel openings are not instantaneous, a wave
formation event occurs, wherein shock waves are formed initially,
that steepens to a shock or a pressure decrease that diffuses as a
spread-out expansion wave. This creates wave timing differences
from exact waves, potential losses and carry-over flows that can be
determined and accounted for. Expansion waves propagate into a flow
region with acoustic velocity. Shocks propagate into a flow region
with a velocity that exceeds the speed of sound for the region. The
equations for moving waves 220 and 230 are shown in FIG. 2B.
Constant area channels with a consistent shape improve propagation
of moving waves as compared to inconsistent area channels and/or
inconsistently shaped channels.
[0060] FIG. 3 illustrates an example of gas compressor timing and
sequences 300. Impeller state 316n is the low pressure, zero
velocity condition, after expansion and before the reset group of
processes is initiated. Impeller state 317n is the high pressure,
zero velocity condition. Stator 306 includes inlet port 307a, reset
port 307b, reload port 307c, and discharge port 307n. Reset port
307b is fluidly coupled to reload port 307c direct the collected
reset flow back on to the impeller at the reload port 307c. The
positions of edges of one or more of the ports 307a-307n may be
based on the flow or wave processes. In examples, the leading edges
for inlet port 307a and reset port 307b are at the same rotation
angle. The angular length of the inlet port 307a is sufficient to
achieve the desired mass flow in the port and flow Mach number at
the trailing edge of the inlet port 307a. The desired mass flow and
flow Mach number may be determined, calculated, adjustable, and
selectable.
[0061] The trailing edge of reset port 307b is a one wave transit
time after the trailing edge of inlet port 307a to allow for the
passage of shockwave 309. The trailing edge of reload port 307c is
located by the transit time of inward running shockwave 310 and its
arrival at the rotor ID. The length of discharge port 307n may be
based on the transit time of expansion waves 311 and 312. Because
expansion waves are diffusive (e.g. the wave spreads out as it
travels), the location of the trailing edge of discharge port 307n
is positioned is at the point where the static pressure on the
rotor moves below (e.g., drops) the static pressure in the
discharge port 307n. In examples, the angle devoted to the highest
pressure portion of the cycle may be minimized to further reduce
leakage loss. In some examples, the cycle angle duration may not
match angle available, and extra rotation angle may be left after
the discharge port 307n, before the leading edges of the inlet port
307a and reset port 307b.
[0062] In examples, the stator wall's outside diameter 3060D and
inside diameter 3061D may be located close to the impeller ID and
OD channel openings (whether axial or radial), which improves
containment of the various levels of pressure and to prevent
leakage from high pressure regions to low pressure regions that
would adversely affect the processes. Further, port leading and
trailing edges may also be located close to the impeller ID and OD
channel openings (whether axial or radial), which further improves
pressure containment and leakage prevention. In some examples, the
shock waves may have a small deviation from ideal (typically less
than 1.5% loss of total pressure ratio across the shock).
[0063] Diffusion of flow to reduce velocity and recover pressure
occurs in stator OD ports (reset port 307b and discharge 307n). An
exemplary static pressure for discharge 307n may be the square root
of the pressure ratio achieved at State D (shown in FIG. 4), which
is the maximum max pressure on the impeller relative to the inlet
total pressure. Positioning the ports such that static pressure for
discharge 307n is at State D optimizes compression by making use of
two expansion waves of equal pressure ratio (e.g., expansion waves
311 and 312).
[0064] FIG. 4 is an example operating cycle diagram of an example
gas compressor. Diagram 400 maps an sequential processes of an
example centrifugal wave compressor operating cycle in a graph of
Pressure vs. Mach number for the flow states at the rotor outside
diameter. (Mach number=(gas flow velocity/speed of sound)).
[0065] Beginning at point A, is a very low flow velocity through
the impeller, at low pressure. This is the impeller condition at
the opening of the inlet and reset ports. From point A, the flow
resets to velocity and pressure point B into the reset port. The
reset port flow, having an elevated total pressure, may be loaded
back onto the impeller ID at the reload port, initiating an outward
running shockwave s1 and returning the flow on the impeller at
intermediate pressure with highest velocity state point C.
[0066] The flow is stopped on the impeller at the trailing edge of
the reset port, which initiates an inward running shockwave s2,
converting the velocity to high pressure with zero velocity in the
rotor channel at point D. The flow is then expanded to an
intermediate static pressure E into the discharge port. The
expansion is defined by expansion wave e1 and reflected expansion
wave e2. After e2, the flow on the impeller is at low pressure and
zero velocity returning to point A. In examples, the steady flow
into the discharge port (stator) is diffused to low velocity and
total pressure Et. An optimal design may position the discharge
port static pressure Pe to be the square root of the pressure ratio
of Pd/Pa, which delivers an optimal combination of flow and
pressure to the discharge port by two balanced expansion waves e1
and e2.
[0067] FIG. 5 is an example turndown and control cycle diagram of
an example gas compressor. In examples, one or more of wave
compressors described herein may turn down flow from 100% to 0% at
a target delivered pressure. Reduction of Point B in M to B'
results in a reduction of mass on the impeller (B'), which reduces
the mass flow delivered at C' or Ct'. Centrifugal work is done in
discrete sectors of rotation, and is positively accelerates making
surge or stall events unlikely. The recovery of velocity to
pressure on the impeller (S2) is driven by a strong moving wave.
Waves S1, E1 and E3 (D1' to D2') are accelerative.
[0068] Control (e.g., reduction of mass flow) may be implemented
effected by a valve in the inlet port and nozzle that adjusts inlet
port total pressure. Additionally or alternatively, the inlet port
may include a variable leading edge that is dynamically adjustable
to change the rotational sector available for reset (e.g., reducing
the Mach number at E to E' and resulting Pa and Ma). Additionally
or alternatively, the impeller speed maybe dynamically adjustable
to implement control by creating a mismatch between the wave field
and the port edges, which causes a limitation or recirculation of
flow. Control may be initiate and or terminated manually and/or
automatically based on a target pressure or a reduce pressure at a
target flow. In examples, a target pressure or a reduce pressure at
a target flow may be dependent one or more characteristic of the
downstream system. Further, flow energy remaining on the rotor at
reduced flow (D1') may be recovered by an extra expansion wave A1'
to a2', and the recovered total pressure is available in the reset
port, minus diffusion loss.
[0069] FIG. 6 illustrates an example gas compressor of an example
system 600. In examples, a flow enters through a filter 601, which
removes particulates. Then, flow enters the impeller through the
inlet port 602. Flow exits the impeller, at an elevated pressure
and temperature, after a single stage of centrifugal compression,
at the reset port 603. Following diffusion in the stator, to
recover velocity as pressure, flow exits the unit. Flow goes
through a first cooler 604, wherein heat is transferred to cooling
media and liquid water condensed from the gas is drained from the
cooler by a drain.
[0070] Flow is reintroduced to the impeller at the reload port 605,
wherein the flow is further compressed on the impeller and exposed
to the discharge port 606 at elevated pressure and temperature.
Following diffusion in the stator, to recover velocity as pressure,
the flow exits the unit and goes to a second cooler 607, wherein
heat is transferred to cooling media, and liquid water condensed
from the gas is drained from the cooler 607 by a drain. Thereafter,
the flow, flows out at 608 and is delivered to a user or to a
subsequent compression stage.
[0071] FIG. 7 illustrates an example radial inlet, radial outlet
impeller 700 section view of an example gas compressor. Inlet port
707a or reset port 707b and discharge port 707n are shown in a
radial inlet and outlet configuration.
[0072] FIG. 8 illustrates an example axial inlet, axial outlet
impeller 800 of an example gas compressor. An axial face radial
channel 801 is shown in an axial inlet and axial outlet
configuration.
[0073] FIG. 9 illustrates an example axial inlet, radial outlet
impeller 900 section view of an example gas compressor. Channel 901
is shown in an axial inlet radial outlet configuration.
[0074] FIG. 10 illustrates an example axial inlet, radial outlet
impeller and stator section view with two compression stages on a
single impeller of an example gas compressor 1000. Example inlet
1001 and example outlet 1002 is shown in an axial inlet and radial
outlet configuration.
[0075] FIG. 11A illustrates an example operating cycle discharge
flow data of an example three port gas compressor. X axis 1101
represents time, and Y axis 1102 represents the flow. FIG. 11B
illustrates an example operating cycle discharge flow data of an
example four port gas compressor (e.g., as shown in FIG. 1). X axis
1101B represents time, and Y axis 1102B represents the flow. FIG.
12 shows example pressure ratio for wave processes compared to
isentropic flow process. X axis 1203 represents the flow Mach
number, and the Y axis 1204 represents pressure ratio.
[0076] FIG. 13 is an example block diagram illustrating an example
method 1300 of compressing gas. In this example method, the reset
phase, reload phase, and discharge phase illustrated in FIG. 1 is
shown by way of example. FIG. 13 is an example block diagram
illustrating an example method 1300 of compressing gas. In this
example method, the reset phase, reload phase, and discharge phase
illustrated in FIG. 1 is shown by way of example. At operation
1301, example method 1300 increases velocity of air flow, via
centrifugal energy, within sequential channels of a centrifugal
impeller. At operation 1302, example method 1300 captures the air
flow from the sequential channels. At operation 1303, example
method 1300 reloads at least some of the captured air flow into
sequential channels of the centrifugal impeller. At operation 1304,
example method 1300 increases pressure of the reloaded air flow by
inducing at least one shockwave traveling in the same direction as
the centrifugal energy. At operation 1305, example method 1300
increases pressure of the reloaded air flow by inducing at least
one shockwave traveling opposite the centrifugal energy. At
operation 1306, example method 1300 increases pressure of the
reloaded air flow by inducing at least one other shockwave
traveling opposite the centrifugal energy. At operation 1307,
example method 1300 discharges the increased pressure reloaded air
flow from the sequential channels. Some steps of example method
1300 may be skipped if desired and additional step may be added if
desired.
[0077] Example 1300 may be used according to any and/or any
combination of the example impellers, example gas compressors
and/or systems described and/or illustrated herein (e.g., FIGS.
1-12). Further, example method 1300 may include additional aspects
for example, a temperature and pressure of the gas flow when
exiting the first exit port is elevated compared to the temperature
and pressure of the gas flow prior to entering the first inlet
port. In another aspect, a temperature and pressure of the gas flow
when exiting the discharge port is elevated compared to the
temperature and pressure of the gas flow when exiting the first
exit port. Another aspect also includes: after the releasing the
gas flow via the first exit port, intercooling the gas flow before
the reintroducing the gas flow via a second inlet port. Another
aspect also includes, after the discharging the gas flow via the
discharge port, delivering the gas flow to a subsequent compression
stage. Another aspect also includes, detecting a characteristic of
a downstream operation; and adjusting a target pressure or a target
gas flow of the centrifugal impeller. Another aspect also includes:
detecting a target pressure or a target gas flow of the centrifugal
impeller; and adjusting a mass gas flow at the first inlet port by
at least one of: adjusting a valve at the first inlet port,
adjusting a nozzle at the first inlet port, adjusting a position of
an adjustable leading edge of the first inlet port, and adjusting a
rotation speed of the centrifugal impeller.
Additional Examples
[0078] A first aspect is directed to a gas compressor.
Specifically, the gas compressor involves: a centrifugal impeller
comprising constant area shrouded channels and a stator. The stator
includes: an inside diameter adjacent at least two inside diameter
gas ports including a first inlet port having a leading edge and a
trailing edge; a second inlet port having a leading edge and a
trailing edge; and an outside diameter adjacent at least two
outside diameter gas ports. The outside gas ports include: a first
exit port having a leading edge and a trailing edge, and a second
exit port having a leading edge and a trailing edge. A channel of
the centrifugal impeller passes the two inside diameter gas ports
and the two outside diameter gas ports during a single revolution
of the centrifugal impeller.
[0079] In another aspect, the first exit port fluidly couples to
the second inlet port.
[0080] In another aspect, the leading edges and the trailing edges
of the two inside diameter gas ports and two outside diameter gas
ports are positioned based at least on a selected mass gas flow, a
selected gas flow Mach number, and wave trajectory.
[0081] In another aspect, the leading edge of the first inlet port
and the leading edge of the first exit port are positioned at a
same rotation angle.
[0082] In another aspect, an angular length of the first inlet port
is based at least on: a selected mass gas flow of the first inlet
port, and a selected gas flow Mach number at the trailing edge of
the first inlet port.
[0083] In another aspect, an angular length of the first inlet port
is adjustable via adjustable positions of the leading edge of the
first inlet port.
[0084] In another aspect, an angular distance between the trailing
edge of the first inlet port and the trailing edge of the first
exit port provides at least one moving shockwave that travels from
the inside diameter of the stator to the outside diameter of the
stator.
[0085] In another aspect, an angular distance between the trailing
edge of the first exit port and the trailing edge of the second
inlet port provides at least one moving shockwave that travels from
the outside diameter of the stator to the inside diameter of the
stator.
[0086] In another aspect, an angular length of the second exit port
is based at least on a selected travel time of an moving expansion
wave that travels from the outside diameter of the stator to the
inside diameter of the stator and a reflective expansion wave that
travels from the inside diameter of the stator to the outside
diameter of the stator.
[0087] In another aspect, the trailing edge of the second exit port
is positioned at a location that static pressure on the impeller
reduces below static pressure in the second exit port.
[0088] In another aspect, an angular distance between the trailing
edge of the second inlet port and the leading edge of the second
exit port is a shorter than any other angular distance between any
other trailing edge of the stator and any other leading edge of the
stator.
[0089] Another aspect is directed to a gas compression method.
Specifically, the gas compression method includes: receiving a gas
flow into one or more shrouded channels of a centrifugal impeller
via a first inlet port adjacent an inside diameter of a stator
during a partial revolution of the centrifugal impeller; releasing
the gas flow from the one or more channels of the centrifugal
impeller via a first exit port adjacent an outside diameter of the
stator during a subsequent partial revolution of the centrifugal
impeller; reintroducing the gas flow into the one or more channels
of the centrifugal impeller via another inlet port adjacent the
inside diameter of the stator during another subsequent partial
revolution of the centrifugal impeller; and discharging the gas
flow from the one or more channels of the centrifugal impeller via
a discharge port adjacent the outside diameter of the stator during
an additionally subsequent partial revolution of the centrifugal
impeller, wherein a sum of the partial revolution, the subsequent
partial revolution, the another subsequent partial revolution, and
the additionally subsequent partial revolution is less than a
single revolution of the centrifugal impeller.
[0090] In another aspect, a temperature and pressure of the gas
flow when exiting the first exit port is elevated compared to the
temperature and pressure of the gas flow prior to entering the
first inlet port.
[0091] In another aspect, a temperature and pressure of the gas
flow when exiting the discharge port is elevated compared to the
temperature and pressure of the gas flow when exiting the first
exit port.
[0092] Another aspect also includes: after the releasing the gas
flow via the first exit port, intercooling the gas flow before the
reintroducing the gas flow via a second inlet port.
[0093] Another aspect also includes: after the discharging the gas
flow via the discharge port, delivering the gas flow to a
subsequent compression stage.
[0094] Another aspect also includes: detecting a characteristic of
a downstream operation; and adjusting a target pressure or a target
gas flow of the centrifugal impeller.
[0095] Another aspect also includes: detecting a target pressure or
a target gas flow of the centrifugal impeller; and adjusting a mass
gas flow at the first inlet port by at least one of: adjusting a
valve at the first inlet port, adjusting a nozzle at the first
inlet port, adjusting a position of an adjustable leading edge of
the first inlet port, and adjusting a rotation speed of the
centrifugal impeller.
[0096] Another aspect is directed to a centrifugal moving wave gas
compressor. Specifically, the centrifugal moving wave gas
compressor involves: a centrifugal impeller comprising constant
area shrouded channels and a stator. The stator includes: a first
gas inlet port adjacent an inside diameter of the stator operable
to receive a gas flow having an initial pressure into the impeller,
a first gas exit port adjacent an outside diameter of the stator
operable to release the gas flow from the impeller at a first
elevated pressure after a partial revolution of the impeller, a
reload gas port adjacent an inside diameter of the stator operable
to reload the gas flow into the impeller, and a discharge gas port
adjacent an outside diameter of the stator operable to rerelease
the gas flow from the impeller at a second elevated pressure after
a partial revolution of the impeller. The second elevated pressure
is higher than the first elevated pressure, which is higher than
the initial pressure, and wherein a channel of the centrifugal
impeller passes the two inside diameter gas ports and the two
outside diameter gas ports during a single revolution of the
centrifugal impeller.
[0097] In another aspect, at least an outward moving first
shockwave raises the initial pressure to the first elevated
pressure, and wherein at least an inward moving second shock wave,
an inward moving expansion wave, and an outward moving expansion
wave raises the first elevated pressure to the second elevated
pressure.
[0098] The examples and designs illustrated and described herein as
well as examples and designs not specifically described herein
(e.g., impellers, stators, and/or compressors not specifically
illustrated in the figures) are within the scope of aspects of the
disclosure. The order of execution or performance of the operations
in examples of the disclosure illustrated and described herein is
not essential, unless otherwise specified. That is, the operations
may be performed in any order, unless otherwise specified, and
examples of the disclosure may include additional or fewer
operations than those disclosed herein. For example, it is
contemplated that executing or performing a particular operation
before, contemporaneously with, or after another operation is
within the scope of aspects of the disclosure.
[0099] When introducing elements of aspects of the disclosure or
the examples thereof, the articles "a," "an," "the," and "said" are
intended to mean that there are one or more of the elements. The
terms "comprising," "including," and "having" are intended to be
inclusive and mean that there may be additional elements other than
the listed elements. The term "exemplary" is intended to mean "an
example of." The phrase "one or more of the following: A, B, and C"
means "at least one of A and/or at least one of B and/or at least
one of C."
[0100] Having described aspects of the disclosure in detail, it
will be apparent that modifications and variations are possible
without departing from the scope of aspects of the disclosure as
defined in the appended claims. As various changes could be made in
the above constructions, products, and methods without departing
from the scope of aspects of the disclosure, it is intended that
all matter contained in the above description and shown in the
accompanying drawings shall be interpreted as illustrative and not
in a limiting sense.
[0101] While the disclosure is susceptible to various modifications
and alternative constructions, certain illustrated examples thereof
are shown in the drawings and have been described above in detail.
It should be understood, however, that there is no intention to
limit the disclosure to the specific forms disclosed, but on the
contrary, the intention is to cover all modifications, alternative
constructions, and equivalents falling within the spirit and scope
of the disclosure.
* * * * *