U.S. patent application number 11/893725 was filed with the patent office on 2008-02-28 for fluid pump having low pressure metering and high pressure delivering.
Invention is credited to Peter Stemer.
Application Number | 20080047611 11/893725 |
Document ID | / |
Family ID | 35057153 |
Filed Date | 2008-02-28 |
United States Patent
Application |
20080047611 |
Kind Code |
A1 |
Stemer; Peter |
February 28, 2008 |
Fluid pump having low pressure metering and high pressure
delivering
Abstract
A pumping apparatus (1) adapted for delivering fluid against
pressure. The pumping apparatus has a plurality of metering devices
(3,5) adapted for metering a plurality of different fluids, and has
a booster device (7) adapted for increasing the pressure of the
fluids metered by the plurality of metering devices (3,5) to said
high pressure, and has a damping device (9) adapted for
compensating fluctuations of the fluids metered by the plurality of
metering devices (3,5). Each device (3,5,7,9) has an inlet (41) and
an outlet (43). The outlets of the metering devices are coupled to
the inlet (41) of the booster device (7), and the outlet of the
booster device (7) is coupled to the inlet of the damping device
(9).
Inventors: |
Stemer; Peter; (Waldbronn,
DE) |
Correspondence
Address: |
PERMAN & GREEN
425 POST ROAD
FAIRFIELD
CT
06824
US
|
Family ID: |
35057153 |
Appl. No.: |
11/893725 |
Filed: |
August 16, 2007 |
Current U.S.
Class: |
137/171 ;
137/565.3; 417/266 |
Current CPC
Class: |
F04B 11/0008 20130101;
Y10T 137/86139 20150401; F04B 25/00 20130101; F04B 13/02 20130101;
Y10T 137/3003 20150401 |
Class at
Publication: |
137/171 ;
137/565.3; 417/266 |
International
Class: |
F04B 25/00 20060101
F04B025/00; F04B 13/02 20060101 F04B013/02 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 24, 2006 |
WO |
2006/087036 |
Claims
1-50. (canceled)
51. A pumping apparatus adapted for delivering fluid against
pressure, comprising: a plurality of metering devices adapted for
metering a plurality of different fluids, a booster device adapted
for increasing the pressure of the fluids metered by the plurality
of metering devices to said high pressure, and a damping device
adapted for compensating fluctuations of the fluids metered by the
plurality of metering devices and compressed by booster device,
each device having an inlet and an outlet, wherein the outlets of
the metering devices are coupled to the inlet of the booster
device, and the outlet of the booster device is coupled to the
inlet of the damping device.
52. The pumping apparatus of claim 51, comprising at least one of:
the pumping apparatus is adapted for blending at least two
different fluids and for delivering the blended fluid against high
pressures at which compressibility of the fluid becomes noticeable;
the damping device is an active damping device; the plurality of
metering devices comprises a first metering device and a second
metering device; the metering devices are adapted for delivering
fluid synchronously to the booster device.
53. The pumping apparatus of claim 51, wherein the outlets of the
metering devices are coupled to the inlet of the booster device via
a mixing device.
54. The pumping apparatus of claim 53, comprising at least one of:
the mixing device comprises at least one mixing inlet per metering
device and one outlet; the outlet of the first metering device is
coupled to a first mixing inlet of the mixing device via a third
connection conduit and the outlet of the second metering device is
coupled to a second mixing inlet of the mixing device via a fourth
connection conduit; the outlet of the mixing device is coupled to
the inlet of the booster device via a fifth connection conduit; the
mixing device is provided by a branch tee.
55. The pumping apparatus of claim 51, wherein the outlet of the
booster device is coupled to the inlet of the damping device.
56. The pumping apparatus of claim 55, wherein the outlet of the
booster device is coupled to the inlet of the damping device via a
sixth connection conduit.
57. The pumping apparatus of claim 51, wherein the metering devices
are adapted for delivering fluid concurrently to the inlets of the
mixing device.
58. The pumping apparatus of claim 51, wherein the pumping
apparatus comprises--when operated--three different pressure
values: a sucking pressure, a mixing pressure, an output
pressure.
59. The pumping apparatus of claim 58, comprising at least one of:
the first and the second metering devices each are adapted for
letting in fluid at the sucking pressure and for delivering fluid,
in particular to the mixing device, at the mixing pressure; the
first and the second metering devices each are adapted for
delivering fluid to the inlet of the booster device via the mixing
device at the mixing pressure; the booster device is adapted for
letting in fluid at the mixing pressure and for delivering fluid to
the damping device at the output pressure; the damping device is
adapted for letting in fluid and for delivering fluid at the output
pressure.
60. The pumping apparatus of claim 51, comprising at least one of:
the first metering device of the pumping apparatus comprises a
first piston for reciprocation in a first pump chamber; the second
metering device of the pumping apparatus comprises a second piston
for reciprocation in a second pump chamber; the booster device of
the pumping apparatus comprises a third piston for reciprocation in
a booster chamber; the damping device of the pumping apparatus
comprises a fourth piston for reciprocation in a damping chamber;
the booster device comprises a booster pressure sensor; the damping
device comprises a damping pressure sensor.
61. The pumping apparatus of claim 51, wherein the pumping
apparatus comprises a valve arrangement with a plurality of valves
adapted for allowing flow of fluid into the inlets of the metering
devices and the booster devices, and for inhibiting flow in the
opposite direction.
62. The pumping apparatus of claim 61, wherein the valve
arrangement of the pumping apparatus comprises at least one or more
of the following: a flow check valve, an on-off valve, and a flow
control valve.
63. The pumping apparatus of claim 51, comprising at least one of:
a first inlet valve coupled upstream to the first pump chamber of
the first metering device, wherein the first inlet valve is adapted
for allowing flow of fluid into the first pump chamber of the first
metering device and for inhibiting flow in the opposite direction;
a second inlet valve coupled upstream to the second pump chamber of
the second metering device, wherein the second inlet valve is
adapted for allowing flow of fluid into the second pump chamber of
the second metering device and for inhibiting flow in the opposite
direction; an inlet valve coupled upstream to the booster chamber
of the booster device, wherein the inlet valve is adapted for
allowing flow of fluid into the booster chamber of the booster
device and for inhibiting flow in the opposite direction; a booster
outlet valve coupled upstream to the damping chamber of the damping
device, wherein the booster outlet valve is adapted for allowing
flow of fluid into the damping chamber of the damping device and
for inhibiting flow in the opposite direction.
64. The pumping apparatus of claim 51, comprising at least one of:
a first mixing inlet valve coupled upstream to the first mixing
inlet of the mixing device, wherein the first mixing inlet valve is
adapted for allowing flow of fluid into the mixing device and for
inhibiting flow in the opposite direction; a second mixing inlet
valve coupled upstream to the second mixing inlet of the mixing
device, wherein the second mixing inlet valve is adapted for
allowing flow of fluid into the mixing device and for inhibiting
flow in the opposite direction.
65. The pumping apparatus of claim 51, wherein the pumping
apparatus comprising at least one of: a pressure sensor for
measuring the pressure within any of the connection conduits and
chambers of the pumping apparatus a flow sensor for measuring the
flow rate within any of the connection conduits of the pumping
apparatus, and a position sensor for measuring the position of any
of the pistons of the metering devices and the booster devices.
66. The pumping apparatus of claim 51, wherein the pumping
apparatus comprises a control unit communicating for controlling
with one or more than one of each of the following controllable
features of the pumping apparatus: any one of the metering devices,
any one of the booster devices, any one of the valves of the valve
arrangement.
67. The pumping apparatus of claim 66 wherein the control unit
communicates additionally with the sensors for realizing a closed
feedback loop for providing at least one of: a pressure controller,
a position controller, and flow controller for controlling one or
more of the following: the inlet pressure, the mixing pressure, the
output pressure, the switching status of any one of the valves, the
position of any one of the pistons of the metering devices, the
position of any one of the pistons of the booster devices, and the
flow within any one of the connection conduits.
68. The pumping apparatus of claim 66, comprising at least one of:
the control unit controls the booster device in a manner that the
mixing pressure is substantially stabilized; the control unit
controls the damping device for realizing an active pulse damping
unit in a manner that the output pressure is substantially
stabilized; the control unit comprises data of the fluids, in
particular the compressibility, to be mixed used for calculating
and controlling the optimal movement of the pistons of the pumping
apparatus for realizing the substantial stabilized pressures; the
control unit is adapted for measuring the volume contraction of the
metering devices, wherein the mixing pressure is substantially
stabilized; the control unit provides a drive control for all
metering devices and all boosting devices of the pumping apparatus
in a manner that the mixing pressure and the output pressure are
substantially stabilized.
69. A fluid separation system comprising a fluid delivery system
comprising a pumping apparatus of claim 51, and a separation device
for separating components of the fluid delivered by the fluid
delivery system.
70. The fluid separation system of claim 69, wherein the fluid
separation system is or comprises at least one of: a
chromatographic system, a high performance fluid chromatographic
system, an HPLC arrangement comprising a chip and an mass
spectrograph, a high throughput LC/MS system, a purification
system, micro fraction collection/spotting system, a system adapted
for identifying proteins, a system comprising a GPC/SEC column, a
nanoflow LC system, or a multidimensional LC system adapted for
separation of protein digests.
71. The fluid separation system of claim 69, wherein the fluid
separation system comprises a detecting device or a coupling to a
detection device for at least one of analyzing and detecting
components of the fluid separated by the separation device.
72. A method of delivering fluid at high pressure at which
compressibility of the fluid becomes noticeable comprising:
metering a plurality of different fluids with a plurality of
metering devices, receiving the fluids from the plurality of
metering devices, increasing the pressure of the metered fluids
within a booster device to said high pressure.
73. The method of claim 72, comprising at least one of: mixing the
plurality of different fluids; increasing the pressure of the mixed
fluid in the booster device to said high pressure and delivering it
at said high pressure to the damping device; compensating
fluctuations of the mixed fluid by the damping device.
74. A software program or product, embodied on a computer readable
medium, for controlling the method of claim 72, when run on a data
processing system.
75. A software program or product, embodied on a computer readable
medium, for at least one of: executing or controlling the method of
claim 72, controlling the set points of the pumping apparatus while
metering and mixing said plurality of fluids, when run on a data
processing system.
76. A software program or product, embodied on a computer readable
medium, for at least one of: executing or controlling a method of
delivering fluid at high pressure at which compressibility of the
fluid becomes noticeable including: metering a plurality of
different fluids with a plurality of metering devices, receiving
the fluids from the plurality of metering devices, and increasing
the pressure of the metered fluids within a booster device to said
high pressure, controlling the set points of the pumping apparatus
while metering and mixing said plurality of fluids, when run on a
data processing system, implemented in an embedded system of the
pumping apparatus of claim 51 as firmware.
Description
BACKGROUND ART
[0001] The present invention relates to high-pressure fluid
pumps.
[0002] Delivering under high pressure is useful, for example, in
liquid chromatography to pump the mobile phase (specific
composition of solvents) through the chromatographic system
including the separation column. The pumping apparatus may form a
part of a solvent delivery system which then comprises additional
units for drawing in and mixing solvents.
[0003] Different approaches are known in the art for pumping the
mobile phase through a chromatographic system. According pumping
apparatuses usually require a pressure source and may comprise any
possibility for blending different solvents, e.g. proportioning
valves, followed by a mixing device and by filtering them through a
certain amount of volume.
[0004] EP 0 309 596 B1 (by the same applicant), for example, shows
a pumping apparatus comprising two pistons and two according pump
chambers and control means coupled to drive means for adjusting the
stroke length of the pistons.
[0005] A combination of a pump producing a pulsating stream of
liquid such as a diaphragm pump and a pulse damper is disclosed in
EP 0 115 672 B1 (by the same applicant) to achieve delivering fluid
against high pressure.
[0006] U.S. Pat. No. 4,003,679 (by the same applicant) discloses a
pumping system provided in which a low pressure metering pump
injects fluid charges into a high pressure pump which in turn
operates into a high pressure load.
[0007] U.S. Pat. No. 4,599,049 (by the same applicant) discloses a
high pressure meter pump system with improved accuracy by
subdividing a large meter pump capacity into metered subvolume
charges which are incrementally delivered to a high pressure slave
pump.
[0008] Another system is shown in the U.S. Pat. No. 4,714,545 (by
the same applicant), wherein a plurality of fluid solutions are
connected to an input of a pump system having at least two
displacement chambers.
DISCLOSURE OF THE INVENTION
[0009] It is an object of the invention to provide an improved
delivery of fluid. The object is solved by the independent claims.
Preferred embodiments are shown by the dependent claims.
[0010] According to embodiments of the present invention, a pumping
apparatus adapted for metering at least two different fluids, for
example liquids, and for delivering the metered fluids against
pressure, for example against high pressure at which
compressibility of the fluid becomes noticeable, is suggested.
[0011] The pumping apparatus comprises a plurality of metering
devices adapted for metering a plurality of different fluids. Each
metering device comprises an inlet and an outlet, wherein the
outlets of the metering devices all are coupled to an inlet of a
booster device of the pumping apparatus. In other words, the
metering devices can be connected in parallel or side-by-side.
Consequently, different flows, for example flows of different
fluids, can flow through the metering devices in parallel, wherein
all flows of said different fluids lead into one common flow
leading into the booster device.
[0012] Advantageously, the different fluids can be blended by
transporting them to the inlet of the booster device. The outlet of
the booster device is coupled to the inlet of a damping device. The
booster device and the damping device are connected in series,
wherein the booster device can be adapted for increasing the
pressure of the fluids metered by the plurality of metering devices
to said high pressure. Consequently, the different fluids can be
blended precisely under low-pressure condition before reaching the
inlet of the booster device of the pumping apparatus, being
compressed within the booster device, and finally being provided at
the outlet of the damping device under high-pressure condition. The
damping device can be designed and operated to compensate any
occurring flow and thus pressure fluctuation of the fluids metered
by the metering devices and compressed by the booster device. This
makes it possible to deliver a stream of fluid at higher pressures,
relatively low flow rates, and fewer pulsations.
[0013] The booster device and the damping device can be
synchronized with each other and with the metering devices such
that the damping device still delivers flow while the booster
device gets refilled. The metering devices are reloaded while the
booster device is delivering. Consequently, the pumping apparatus
can generate a ripple-free flow of precisely dosed composition
under said high pressure.
[0014] Advantageously, the plurality of metering devices are
adapted for simultaneous dosing of composition combined with a
serial configuration of the booster device and the damping device
employed for generating the continuous flow under said high
pressure. In a minimum configuration comprising two metering
devices, the pumping apparatus needs about the same hardware as a
dual isocratic serial pump, but achieves composition independent of
system backpressure.
[0015] Advantageously, miniaturized chromatographic systems, for
example, which generally need lower flow rates, higher pressures,
and refined mixing ratios, can be supplied with fluid by such a
pumping apparatus. Besides this, the mobile phase can be pumped
through said chromatographic systems with an increased accuracy of
system parameters like flow rate and pressure. Advantageously, said
improved performance of the pumping apparatus enables enhancing the
performance of coupled chromatographic systems. Due to the improved
pumping apparatus, such coupled systems can comprise one or more of
the following features for enhancing the performance: Smaller size
of packing material, smaller id columns, faster linear speed of
solutions during separation, faster compositional gradients, and
longer separations beds. Summarizing, the total amount of liquid in
use can be reduced without seriously endangering the quality of the
separation process.
[0016] For chromatographic analysis, for example, a flow rate of
fluid can be delivered to the column by the pumping apparatus being
adjustable across a wide range of flow rates. Besides this, the
pumping apparatus permits the generation of mixtures of solvents
and changing the compositional ratio of the various solvents of the
mixture in the course of time (gradient operation). Such
versatility of the pumping apparatus allows optimizing the analysis
conditions for the specific sample to be chromatographically
separated.
[0017] Advantageously, the flow rate can be adjustable or
selectable and can be--once selected--kept substantially constant
by the booster devices. Thus reducing fluctuation of the flow rate
through the separation column leading to variations in the
retention time and peak width of the examined sample compounds so
that the areas of the chromatographic peaks produced by a detector
connected to the outlet of the column, for example, an absorption
detector, a fluorescence detector, or a refractive index detector,
would vary. Since the peak areas are representative for the
concentration of the chromatographically separated sample
substances, preventing or reducing fluctuations in the flow rate
can advantageously improve the accuracy and the reproducibility of
quantitative measurements.
[0018] Embodiments may comprise one or more of the following.
Advantageously, the metering devices can deliver fluid
synchronously to the booster device. In embodiments, the damping
device can realize an active pulse damper. An active pulse damper
can comprise at least one correcting element for influencing at
least one parameter, for example the pressure within the damper.
Advantageously, the damping device can actively stabilize the
output pressure of the pumping apparatus. This makes it possible
that the metering devices produce a pulsating stream of exactly
blended fluid at low pressure into the booster device and that the
booster device produces an also pulsating stream of said blended
fluid at high pressure without abandoning the aim of a ripple-free
output stream of blended fluid under high pressure.
[0019] The metering devices can concurrently produce a plurality of
exactly metered streams of fluid into the inlet of the booster
device. Advantageously, the streams can be blended homogenously
just by transporting them into a common connection conduit to the
inlet of the booster device. While the metering devices draw up
fresh fluid the booster device compresses the composition to system
pressure and takes over conveying the high-pressure stream from the
damping device. In this period the damping gets refilled too.
[0020] Embodiments may comprise one or more of the following. The
outputs of the metering devices can be coupled to the inlet of the
booster device via a mixing device. The mixing device can comprise
a certain volume for filtering the streams of the metering devices.
The mixing device comprises one inlet for each of the metering
devices and one common outlet coupled to the inlet of the booster
device. The apparatus can comprise according connection conduits
between the outlets and inlets of the devices, one for each inlet
of the mixing device and the outlet of the according metering
device, one between the outlet of the mixing device and the inlet
of the booster device, and one between the outlet of the booster
device and the inlet of the damping device.
[0021] Possibly, the mixing device comprises a certain volume for
filtering or mixing the streams produced by the metering devices.
The metering devices are adapted for delivering fluid concurrently
to the inlet of the mixing device.
[0022] Advantageously, the mixing device can be realized by a
simple branch tee--or by a multi-branch connector having a
plurality of inlets and one common outlet when more than two
metering devices are employed--for avoiding any dead volume. The
different fluids can be mixed exactly and simply just by delivering
or metering them concurrently into the connection conduit between
the outlet of the branch tee and the inlet of the booster device.
This reduces any dead volume causing undesired side effects
affecting the quality of the flow rate and/or the output pressure
to a minimum. The different fluids can be blended at a relative low
pressure level. This way decoupling composition blending from the
system backpressure, which makes It possible to reduce any side
effects occurring while blending different fluids affecting the
mixing ratio or the system pressure to a negligibly small value.
Besides this, for reducing any dead volume to a minimum, the length
of said connection conduits can be reduced to a minimum. For
example, the branch tee can be integrated in the booster
device.
[0023] Advantageously, the volume of the booster device can be used
for filtering the inflowing blend of different fluids. By this, the
booster device additionally realizes a mixing device resulting in a
highly homogenous blend of the different fluids deliverable by the
pumping apparatus.
[0024] Embodiments may comprise one or more of the following. The
pumping apparatus is operated substantially at three different
pressures: A sucking pressure, a mixing pressure, and an output
pressure. The metering devices each are adapted for letting in
fluid at the sucking pressure and for delivering fluid, in
particular to the mixing device, at the mixing pressure. The
sucking pressure, for example, may be below ambient pressure or
below the pressure within containers coupled to the metering
devices and comprising the solvents. The mixing pressure is
relatively low, for example, between 10 mbar and where
compressibility becomes noticeable. The booster device is adapted
for letting In fluid at the mixing pressure and for delivering
fluid at the output pressure to the inlet of the damping device.
Consequently, the booster device is adapted for increasing the
system pressure from the relatively low mixing pressure to the high
output pressure. The mixing device as well as the booster device
are operated at both, the low mixing pressure and the high output
pressure. Advantageously, the pressure can be increased after
blending the different fluids, thus having no influence on the
composition of compressible fluids. The damping device is adapted
for letting in and for letting out fluid at the high output
pressure. Advantageously, the damping device can behave like an
active damping device stabilizing the output pressure at a value
resulting from current flow rate and fluid composition, ranging
from 20 bar up to 2000 bar.
[0025] Embodiments may comprise one or more of the following. The
metering devices and the booster devices each comprise a piston for
reciprocation in an according pump or booster chamber. Accordingly,
the pumping apparatus comprises a valve arrangement with a
plurality of valves adapted for allowing the flow of fluid into the
inlets of the metering devices and the booster devices
respectively, the according pump or booster chambers, and for
inhibiting the flow in the opposite direction. The valve
arrangement can comprise one or more flow check valves, on-off
valves, and/or flow control valves or any other valves suitable for
this purpose. Preferably, the pump chambers or rather the inlets of
the metering devices are each coupled downstream to inlet valves
adapted for allowing the flow of fluid into the pump chambers of
the metering devices and for inhibiting the flow in the opposite
direction.
[0026] Accordingly, the inlets of the mixing device, in particular
the branch tee, are coupled to inlet valves adapted for allowing
the flow of fluid into the mixing device and for inhibiting the
flow in the opposite direction. In this configuration, the inlet of
the booster device is just coupled to the outlet of the mixing
device. Alternatively or additionally, the connection conduit
between the mixing device and the booster device can comprise an
according inlet valve.
[0027] Embodiments may comprise one or more of the following.
Advantageously, the pumping apparatus comprises a control unit. The
control unit controls at least one controllable feature such as the
metering devices, the booster devices, and the valves of the valve
arrangement. For this purpose, the control unit can communicate
with the different elements in an open or closed loop mode.
[0028] For realizing a negative feedback closed loop controller,
the embodiments of the pumping apparatus can comprise one or more
different sensors, such as a pressure sensor for measuring the
pressure within any of the conduits or chambers of the pumping
apparatus, a flow sensor for measuring the flow rate within any of
the conduits of the pumping apparatus, a position sensor for
measuring the position of any of the pistons of the metering or
booster devices, or any other suitable sensor using any suited
method of measuring system variables needed by the controller.
Consequently, the control unit can realize, for example, a pressure
controller, a position controller, and/or a flow controller for
controlling at least one of the following pressures, the sucking
pressure, the mixing pressure, and the output pressure, the
switching status of any one of the valves, the position of any one
of the pistons of the metering devices, the position of any one of
the pistons of the booster devices, and/or the flow within any one
of the connection conduits.
[0029] Advantageously, the control unit can control the damping
device, in particular the movement of the piston of the damping
device within the damping chamber of the damping device for
realizing an active pulse damping unit in a manner that the output
pressure is substantially stabilized. Advantageously, this enables
a smother changeover of composed fluid from the metering devices
into the booster device and from the booster device into the
damping device. In other embodiments, the mixing pressure can be
controlled accordingly. In such constant pressure mode for the
mixing pressure, the volume contraction can be measured during the
time when both metering devices dispense their respective volume,
for example by measuring the position of the pistons of the
metering devices and the booster device. Depending on the timing of
dispense/reload cycles, the mixing volume can be adapted to achieve
best performance at a given flow rate by running the pistons at
variable stroke and frequency when the volume of the booster
chamber of the booster device is used for filtering or mixing the
inflowing fluid. A method of running pistons at variable stroke and
frequency is disclosed in the EP 0 309 596 B1, which is
incorporated herein by reference. Advantageously, the inlets and
the outlets of the booster devices are positioned at the booster
chambers of the booster devices in a manner that a first in first
out (FIFO) concept is realized. Consequently, any fluid streaming
into the booster chambers of the booster devices through the
respective inlet is flowing out first as well. This makes it
possible to store a gradient in the pump chamber of the damping
device which is then dispensed to the system as a homogenous
blend.
[0030] Embodiments may comprise one or more of the following. The
pistons of the metering devices can run in synchronous fashion when
individual flow rates are at comparable levels. But when flow rates
differ, say e.g. 10/1, the slower moving piston may just start/stop
dispensing until its volume is at a minimum limit. In other words,
the slower moving piston stops for each half cycle of sucking fresh
fluid. The proportion of the amplitudes of the synchronous strokes
of the pistons of the metering devices is substantially equal to
the mixing ratio, if side effects caused by the compressibility of
the fluids are not taken into consideration.
[0031] Embodiments may comprise one or more of the following. For
realizing an open loop controller, the control unit can comprise
data of the fluids to be mixed, in particular the compressibility,
used for calculating and controlling the optimal movement of the
pistons of the pumping apparatus for realizing the substantial
stabilized output pressure. The data can comprise, for example, one
or more of the following parameters: The compressibility of each
fluid as a function of pressure and temperature, the
compressibility of the blend as a function of pressure and
temperature, the viscosity of the fluids and of the blend as a
function of pressure and temperature, and the mixing volume as a
function of mixing ratio, mixed fluids, temperature, and pressure.
The specific volume of the fluids after blending shall be
understood herein, for example, as the mixing volume. Of special
interest can be the loss or gain of volume during or after
blending.
[0032] By using the data above and calculating said loss or gain of
volume during or after blending, any retroactive effect to the
desired output pressure can be compensated by the control unit.
Consequently, the control unit can calculate the optimal movement
and timing of the pistons of the metering devices and the booster
devices for realizing the open loop controller or, if desired, a
closed loop controller. For each fluid, the control unit can be fed
with the corresponding parameters. Possibly, the control unit can
realize an adaptive system wherein the control unit measures the
parameters needed during an initial phase before operating the
pumping apparatus. Especially advantageously, the control unit can
realize a mixture of the closed and open loop modes.
[0033] Recapitulating, the control unit can realize a drive control
for all metering devices and booster devices of the pumping
apparatus in a manner that the output pressure is substantially
stabilized and a stream of a homogenous blend with an exactly
determined mixing ratio is generated.
[0034] According to other embodiments of the present invention, a
fluid separation system comprising a fluid delivery system
comprising a pumping apparatus as described above and a separation
device for separating components of the fluid delivered by the
fluid delivery system is suggested. Advantageously, the pumping
apparatus can produce an exact ripple-free flow of fluid for
optimizing the performance of the fluid separation system.
[0035] Further embodiments of the present invention relate to a
method of delivering fluid at high pressure at which
compressibility of the fluid becomes noticeable. In a first step, a
plurality of different fluids is metered by a plurality of metering
devices. Subsequently, the fluids are received from the plurality
of metering devices upstream by a booster device and a damping
device. Finally, the pressure of the metered fluids is increased
within the booster device to said high pressure. Advantageously,
the fluids can be blended at a relative low pressure. In
embodiments, a pumping apparatus as described above is employed for
executing the method. Additionally, the different fluids can be
mixed before the booster device receives them. Besides this, the
pressure of the mixed fluid can be increased within the booster
device and delivered at said high pressure to the damping device.
Advantageously, the damping device does not have to increase the
pressure and can be employed for stabilizing the output pressure,
for example actively stabilizing the output pressure. As an
additional step, fluctuations of the mixed fluid can be compensated
by the damping device.
[0036] Embodiments of the invention can be partly or entirely
embodied or supported by one or more suitable software programs,
which can be stored on or otherwise provided by any kind of data
carrier, and which might be executed in or by any suitable data
processing unit. Software programs are preferably applied for
controlling the steps of the method as described above, e.g., by
using a control unit comprising the software programs. Besides
this, the control unit can comprise software programs for
controlling set points of the pumping apparatus.
BRIEF DESCRIPTION OF DRAWINGS
[0037] Other objects and many of the attendant advantages of
embodiments of the present invention will be readily appreciated
and become better understood by reference to the following more
detailed description of embodiments in connection with the
accompanied drawings. Features that are substantially or
functionally equal or similar will be referred to by the same
reference signs.
[0038] FIG. 1 shows a pumping apparatus with two metering devices
and two booster devices connected in series, and
[0039] FIG. 2 shows a schematic view of a fluid separation system
with a fluid delivery system comprising a pumping apparatus.
[0040] FIG. 1 shows a pumping apparatus 1 with a first metering
device 3, a second metering device 5, a booster device 7, and a
damping device 9. The devices 3, 5, 7, and 9 can be controlled by a
control unit 11. The first metering device 3 comprises a first
piston 13 for reciprocation in a first pump chamber 15, the second
metering device 5 comprises a second piston 17 for reciprocation in
a second pump chamber 19, the booster device 7 comprises a third
piston 21 for reciprocation in a booster chamber 23, and the
damping device 9 comprises a fourth piston 25 for reciprocation in
a damping chamber 27.
[0041] The pistons 13, 17, 21, and 25 each are coupled to a screw
link actuator 29 driven by a motor 31. The screw link actuators 29
are coupled via balls 33 to the according devices 3, 5, 7, and 9.
The screw link actuators 29, the motors 31, and the balls 33 are
component parts of drives 35 for actuating the devices 3, 5, 7, and
9 respectively the pistons 13, 17, 21, and 25. Drives as the drives
35 for actuating pistons for reciprocation in pump chambers are
known in the art and therefore not describer in detail in this
application.
[0042] The outer diameters of the pistons 13, 17, 21, and 25 are
smaller than the inner diameters of bores 37 of the pump chambers
15 and 19 respectively of bores 39 of the booster chambers 23 and
27. This makes it possible that fluid can flow into the gaps
between the pistons 13, 17, 21, and 25 and the inner surface of the
according bores 37 respectively 39.
[0043] Each of the devices 3, 5, 7, and 9 comprises an inlet 41 and
an outlet 43. Advantageously, the inlets 41 of the devices 3, 5, 7
and 9 are coupled to an end off the bores 37, 39 located upstream
of the upstream inflection point of the pistons 13, 17, 21, and 25,
wherein the outlets 43 of the devices 3, 5, 7 and 9 are coupled to
the opposite end of the bores 37, 39 located downstream of the
downstream inflection point of the pistons 13, 17, 21, and 25. By
this, fluid sucked firstly into any one of the chambers 15, 19, 23,
or 27 can be dispensed firstly as well. By this, a first in first
out principle can be realized.
[0044] The pumping apparatus 1 comprises a valve arrangement with a
plurality of valves 45 to 53. The valve arrangement is adapted for
allowing the flow of fluid into the inlets 41 of the devices 3 to 9
respectively the chambers 15, 19, 23, and 27, and for inhibiting
the flow in the opposite direction. In embodiments, the valve
arrangement can comprise one ore more flow check valves, on-off
valves, and/or flow control valves or any other valves suitable for
said purpose. In embodiments, the chambers 15, 19, 23, and 27 each
are coupled downstream to at least one valve of the plurality of
valves 45 to 53 of the valve arrangement.
[0045] The first pump chamber 15 of the first metering device 3 is
coupled downstream to a first inlet valve 45 via the inlet 41 of
the first metering device 3 and a first inlet connection conduit
55. The second pump chamber 19 of the second metering device 5 is
coupled downstream to a second inlet valve 47 via the Inlet 41 of
the second metering device 5 and a second inlet connection conduit
57. In embodiments, the inlet valves 45 and 47 of the metering
devices 3 and 5 are realized as flow check valves. In other
embodiments, as shown in FIG. 1, the inlet valves 45 and 47 can
comprise a valve controller 59, for example, controlled by the
control unit 11. The valve controller 59 together with the control
unit 11 can exactly adjust the flow within the connection conduits
55 and 57 and accordingly within the chambers 15 and 19 of the
metering devices 3 and 5. The valve controllers 59 can open the
valves 45 and 47 while sucking fresh fluid and can close them while
delivering the fluid through the outlets 43 of the metering devices
3 and 5.
[0046] The first pump chamber 15 of the first metering device 3 is
coupled upstream to a mixing device 61 via the outlet 43 of the
first metering device 3 and a third connection conduit 63
comprising a first mixing inlet valve 49. The second pump chamber
19 of the second metering device 5 is coupled upstream to the
mixing device 61 via the outlet 43 of the second metering device 5
and a fourth connection conduit 65 comprising a second mixing inlet
valve 51. The mixing inlet valves 49 and 51 are positioned within
the connection conduits 63 and 65 close to the mixing device 61. In
embodiments, the position of the mixing inlet valves 49 and 51
within the connection conduit 63 and 65 may vary. For example, the
mixing inlet valves 49 and 51 can be positioned as close as
possible to the metering devices 3 and 5.
[0047] The mixing device 61 comprises a first mixing inlet 67
coupled to the third connection conduit and a second mixing inlet
coupled to the fourth connection conduit. The mixing device 61
comprises one inlet 67, 69 per metering device 3, 5. In
embodiments, the pumping apparatus 1 can comprise more or less than
two metering devices and respectively the mixing device 61 can
comprise more than two inlets 67 and 69. All mixing inlets 67 and
69 of the mixing device 61 lead into one common fifth connection
conduit 71. The fifth connection conduit 71 is coupled between a
mixing outlet 73 of the mixing device 61 and the inlet 41 of the
booster device 7.
[0048] The mixing device 61 can comprise a certain volume for
filtering and blending the fluid delivered by the metering devices
3 and 5. Advantageously, the mixing device 61 can comprise a simple
branch tee as indicated with dotted lines 75. Advantageously, the
fluids delivered by the metering devices 3 and 5 can be blended
simply by delivering them, for example, concurrently through the
branch tee--as indicated with the dotted lines 75--of the mixing
device 61 of the pumping apparatus 1 into the fifth connection
conduit via the mixing outlet 73 of the mixing device 61.
[0049] The booster chamber 23 is coupled upstream to the damping
chamber 27 via the outlet 43 of the booster device 7, a sixth
connection conduit 77 comprising a booster outlet valve 53, and the
inlet 41 of the damping device 9. The damping chamber 23 of the
damping device 9 is coupled to an outlet conduit 79 via the outlet
43 of the damping device 9. The outlet conduit 79 can be coupled to
a system, for example a liquid chromatographic system, to be fed
with fluid by the pumping apparatus 1.
[0050] The pistons 13 and 17 or the metering devices 3 and 5 are
moved In phase for delivering fluid concurrently into the booster
chamber 23 of the booster device 7 via the connection conduits 63,
65, 71, and the mixing device 61. The velocities of the single
pistons 13 and 17 of the metering devices 3 and 5 can determine the
mixing ratio of the fluid delivered into the booster chamber
23.
[0051] After delivering the fluid with the desired mixing ratio,
said fluid can be compressed within the booster chamber 23 by the
third piston 21 and delivered via the sixth connection conduit 77
into the damping chamber 27 of the damping device 9. The pumping
apparatus 1 comprises substantially three pressure levels. For
example, fresh fluid can be sucked into the pump chambers 15 and 17
by the metering devices 3 and 5 at a pressure level lower than the
ambient pressure, a first sucking pressure. For transporting the
fluid into the booster chamber 23, said fluid can be compressed to
a second higher mixing pressure. Finally, the booster device 7 can
increase the pressure of said fluid up to a third pressure, the
desired output pressure of the pumping apparatus 1.
[0052] FIG. 2 shows a schematic view of a fluid separation system
95 with a fluid delivery system 97 comprising the pumping apparatus
1 and a separation device 99 for separating components of the fluid
delivered by the fluid delivery system 97. The fluid separation
system 95 can comprise a detecting device 101 or a coupling 103 to
the detection device 101. The detection device 101 can be employed
for detecting components of the fluid separated by the separation
device 99. Besides this, the fluid separation system 95 can be
connected to a not shown apparatus, for example a mass
spectrograph, for analyzing the fluid, for example liquid, via a
connection conduit 105. The separation device 99 can be realized,
for example, as a high performance liquid chromatography chip. The
pumping apparatus, for example coupled to the control unit 11, 1
can deliver a ripple-free stream of a blend of different liquids,
for example a gradient of two solvents, to the separation device
99, for example the high performance liquid chromatography
chip.
[0053] In the following different phases of operation of the
pumping apparatus 1 are described in detail by referring to the
different pressure levels and to FIG. 1:
[0054] In a first phase, fresh fluid is sucked by the metering
devices 3 and 5. In this first phase, the pistons 13 and 17 of the
metering devices 3 and 5 are moved--in direction of the FIG.
1--downwards. This increases the volume within the pump chambers 15
and 19, whereas fresh fluid can flow into the pump chambers 15 and
19 through the connection conduits 55 and 57. In the first phase,
the valves 45 and 47 are opened and the mixing inlet valves 49 and
51 are closed. In this phase, the pumping apparatus 1 is operated
downstream to the mixing inlet valves 49 and 51 at the lowest
pressure level, at the sucking pressure.
[0055] In a second phase, the inlet valves 45 and 47 are dosed and
the pressure upstream of the mixing inlet valves 49 and 51 is
increased up to a second higher pressure level, the mixing
pressure, by moving the pistons 13 and 17 of the metering devices 3
and 5--in direction of the FIG. 1--upwards. Due to the
compressibility of the fluids within the metering devices 3 and 5
and possibly existing elasticity of fluid conducting component
parts of the pumping apparatus 1, the mixing inlet valves 67 and 69
stay closed although the pistons 13 and 17 of the metering devices
3 and 5 are moving upwards. Therefore, no fluid is delivered from
the metering devices to the mixing device in the second phase.
Advantageously, the second phase can be reduced to a minimum by
choosing a relatively low mixing pressure. At such a low mixing
pressure any side effects caused by the compressibility of the
different fluids to be blended within the mixing device 61 can be
reduced to a minimum.
[0056] In a third phase, the metering devices 3 and 5 deliver fluid
concurrently into the booster chamber 23 of the booster device 7.
In this phase, the damping device 9 still delivers fluid into the
outlet conduit 79. The third phase equals the phase of a serial
dual isocratic piston pump sucking fresh fluid. In difference, the
fresh fluid is transported actively into the booster chamber 23 of
the booster device at the mixing pressure by the metering devices 3
and 5. For this purpose, the movements of the pistons 13, 17, and
21 of the metering devices 3 and 5 and the booster device 7 have to
be synchronized in a manner that the pressure between the booster
outlet valve 53 and the inlet valves 45 and 47 of the pumping
apparatus 1 is stabilized at the mixing pressure. Volume
contraction of the fluid while blending can be corrected in this
phase.
[0057] In a fourth phase, after filling the booster chamber 23 with
blended fluid, the mixing inlet valves 49 and 51 are closed and the
fluid within the chambers 15 and 19 of the metering devices 3 and 5
is decompressed until the sucking pressure is reached and
consequently the inlet valves 45 and 47 open by moving the pistons
13 and 17 of the metering devices 3 and 5--in direction of the FIG.
1--downwards. At the same time, the booster device 7 starts
compressing the blended fluid up to the high output pressure and
delivering the blended fluid into the damping chamber 27 as
described above.
[0058] The part-cycle of the booster device 7 of compressing,
delivering, and decompressing the mixed or blended fluid has to be
stopped at the moment when the metering devices 3 and 5 are ready
again (see phase three) for delivering freshly sucked fluid at the
mixing pressure into the booster chamber 23 via the mixing device
61. At the same moment, the pressure within the pump chambers 15
and 19, within the mixing device, and within the booster chamber 23
has to be reached the mixing pressure.
[0059] The booster outlet valve 53 closes at the moment when the
pressure within the booster chamber 23 starts dropping from the
output pressure to the mixing pressure. Consequently, starting from
this moment, the damping device 9 has to deliver the fluid alone
and the movement of the fourth piston 25 of the damping device 9
has to be changed or reversed for avoiding any pulsation or any
pressure failure in the outlet connection conduit 79 of the pumping
apparatus 1.
[0060] In the first, second, and fourth phase, the system upstream
of the mixing inlet valves 49 and 51 is operated at a pressure
level between the mixing pressure and the high output pressure.
More precisely, the pressure upstream of the booster outlet valve
53 is always kept stable at the high output pressure by the damping
device 9. For this purpose, the damping device 9 can be coupled to
a pressures sensor 81 for realizing, for example, a pressure
controller 83 for the output pressure of the pumping apparatus 1.
The pressure controller 83 can be implemented in the control unit
11. The booster device 7 can comprise an according booster pressure
sensor.
[0061] During the phases 1, 2, and 4, the booster device 7 delivers
fluid into the damping chamber 27 of the damping device 9 by moving
the third piston 21 of the booster device within the booster
chamber--in direction of the FIG. 1--upwards. After compressing the
blended fluid within the booster chamber 23, the booster outlet
valve 53 opens and the fourth piston 25 of the damping device 9 can
change its direction of movement--in direction of the FIG.
1--downwards. The booster device 7 and the damping device 9 realize
a serial dual isocratic piston pump for delivering a constant flow
of fluid under high pressure.
[0062] For realizing a drive control for the described phases one
to four of the pumping apparatus 1 and for delivering a ripple free
stream of blended fluid into the outlet conduit 79 of the pumping
apparatus 1, the pumping apparatus 1 can be coupled with the
control unit 11 via a plurality of control connections 85. The
control unit 11 can realize, for example, the pressure controller
83 for the output pressure of the pumping apparatus 1, a position
controller 87 for the drives 35 of the devices 3 to 9, or a flow
controller 89 for controlling the flow rates within the connection
conduits 55, 57, 63, 65, 71, 77 and 79. For this purpose, the
pumping apparatus 1 can additionally comprise not shown pressures
sensors, flow sensors, and/or position sensors.
[0063] Besides this, in embodiments, the control unit 9 can
communicate with encoders 91 coupled to the motors 31 of the drives
35. Besides this, each of the drives 35 of the pumping apparatus 1
can comprise one drive controller 93 connected via at least one of
the control connections 85 to the control unit 11. The control unit
11 interprets all data delivered by the pumping apparatus 1 for
realizing a highly sophisticated drive control for the pistons 13,
17, 21, and 25. For this purpose, the drive control realized by the
control unit 11 can store, calculate, and/or measure relevant
parameters within the connection conduits within the pumping
apparatus 1, for example the compressibility or viscosity of the
fluids transported through the pumping apparatus 1. The control
unit 11 can realize one or more open and/or closed loop
controllers.
[0064] At the high pressures encountered, for example, in high
performance liquid chromatography, compressibility of the solvents
becomes noticeable resulting in an additional source of pulsation.
The reason is that during each compressing cycle of the booster
device 7, the third piston 21 of the booster device 7 has to move a
certain path to compress the fluid to its final output pressure
before actual delivery to the damping device 9 starts.
Advantageously, the damping device 9 can compensate this effect.
Besides this, side effects caused by the change of the mixing
volume or the viscosity of the different fluids while blending them
are negligibly small because of blending at the relative low mixing
pressure. This results in a ripple-free and constant flow under
high pressure at the outlet 43 of the damping device 9 of the
pumping apparatus 1.
[0065] Recapitulating, the control unit 11 controls the movement of
all pistons 13, 17, 21, and 25 for guaranteeing an optimal
handshake or better a smooth changeover of the metering devices 3
and 5 with the booster devices 7 and 9 and of the booster device 7
with the damping device 9 for ensuring a ripple-free and constant
stream of fluid delivered by the pumping apparatus 1. On account of
the drive control by the control unit 11 the damping device 9 can
act as an active damping device.
[0066] In the following a method of delivering fluid at high
pressure at which compressibility of the fluid becomes noticeable,
for example by using a pumping apparatus of FIG. 1 or a fluid
separation system of FIG. 2, is described by referring to the
figures.
In a first step, a plurality of different fluids is metered with
the plurality of metering devices 3, 5. Subsequently, the fluids
are received from the plurality of metering devices 3, 5, for
example by the booster device 7 via the mixing device 61. The
fluids can be transported from the plurality of metering devices 3,
5 into the mixing device 61, and from there into the booster device
7. Finally, the pressure of the metered fluids is increased within
the booster device 7 to said high pressure and can be delivered at
said high pressure to the damping device 9. The fluids can be
mixed, for example within the mixing device 61 and/or within the
booster chamber 23 of the booster device 7, for example by metering
them concurrently. As an additional step, fluctuations of the mixed
fluid can be compensated by the damping device 9. During executing
the method, a control unit 11, for example comprising suited
software programs or routines, can control the steps as described
above.
[0067] The pumping apparatus can be coupled to a fluid separation
system for analyzing and or separating fluid, more specifically,
for executing at least one microfluidic process, for example a
liquid chromatographic process, for example a high performance
liquid chromatographic process (HPLC). For analyzing a fluid, for
example a liquid, or rather one or more components within the fluid
or liquid, the coupled system can comprise a detection area, such
as an optical detection area and/or an electrical detection area
being arranged close to a flow path within the system.
Alternatively, the fluid separation system can be coupled to a
detection area or a detecting apparatus such as a mass
spectrograph. The fluid separation system can be realized as a
chromatographic system (LC), a high performance fluid
chromatographic (HPLC) system, an HPLC arrangement comprising a
chip and an mass spectrograph (MS), a high throughput LC/MS system,
a purification system, micro fraction collection/spotting system, a
system adapted for identifying proteins, a system comprising a
GPC/SEC column, a nanoflow LC system, and/or a multidimensional LC
system adapted for separation of protein digests, or alike. Besides
this, the pumping apparatus can be a component part of a laboratory
arrangement.
[0068] It is to be understood, that this invention is not limited
to the particular component parts of the devices described or to
process steps of the methods described as such devices and methods
may vary. It is also to be understood, that different features as
described in different embodiments, for example illustrated with
different Fig., may be combined to new embodiments. It is finally
to be understood, that the terminology used herein is for the
purposes of describing particular embodiments only and it is not
intended to be limiting. It must be noted, that as used in the
specification and the appended claims, the singular forms of "a",
"an", and "the" include plural referents until the context clearly
dictates otherwise. Thus, for example, the reference to "a damping
device" or "an inlet valve" includes two or more such functional
elements.
* * * * *