U.S. patent application number 12/313611 was filed with the patent office on 2009-05-21 for pumping unit for delivery of liquid medium from a vessel.
This patent application is currently assigned to Arbel Medical, Ltd.. Invention is credited to Miron Kaganovich, Alexander Levin, Didier Toubia.
Application Number | 20090129946 12/313611 |
Document ID | / |
Family ID | 40361444 |
Filed Date | 2009-05-21 |
United States Patent
Application |
20090129946 |
Kind Code |
A1 |
Toubia; Didier ; et
al. |
May 21, 2009 |
Pumping unit for delivery of liquid medium from a vessel
Abstract
A pumping unit for delivering a liquid medium from a low
pressure vessel such that the delivered medium has sufficiently
high pressure, by providing the liquid medium in the form of
separated pulses.
Inventors: |
Toubia; Didier; (Raanana,
IL) ; Levin; Alexander; (Binyamina, IL) ;
Kaganovich; Miron; (Haifa, IL) |
Correspondence
Address: |
HESLIN ROTHENBERG FARLEY & MESITI PC
5 COLUMBIA CIRCLE
ALBANY
NY
12203
US
|
Assignee: |
Arbel Medical, Ltd.
Caesarea
IL
|
Family ID: |
40361444 |
Appl. No.: |
12/313611 |
Filed: |
November 21, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60989744 |
Nov 21, 2007 |
|
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Current U.S.
Class: |
417/208 |
Current CPC
Class: |
F04F 1/18 20130101; F04B
19/24 20130101; F04F 1/04 20130101; F04B 15/08 20130101 |
Class at
Publication: |
417/208 |
International
Class: |
F04B 19/24 20060101
F04B019/24 |
Claims
1. A pumping unit for delivering a liquid medium from a vessel in
the form of separated pulses; said pumping unit comprising: a
conduit, which is at least partially contained within said vessel,
wherein a proximal end of said conduit is situated in a vicinity of
a bottom of said vessel; a first check valve installed on a lower
section of said conduit; an electrical heating element for heating
a lower portion of said conduit; and a second check valve installed
on an upper section of said conduit; wherein heating of said
heating element causes said liquid medium to form vapors in said
conduit, said vapors causing said first check valve to close and
causing said second check valve to open; and upon condensation of
said vapors, said second check valve closes.
2. The pumping unit of claim 1, wherein said liquid medium
comprises a cryogen.
3. The pumping unit of claim 2, wherein said electrical heating
element has low thermal inertia.
4. The pumping unit of claim 3, wherein said conduit comprises a
layer of an outer thermal insulation for reducing heating of the
surrounding liquid medium by said electrical heating element.
5. The pumping unit of claim 1, wherein the condensation occurs in
a section of the central feeding conduit situated in immediate
vicinity of the bottom of the vessel.
6. The pumping unit of claim 1, wherein electrical heating pulses
are applied to the heating element, and duration of the electrical
heating pulses is significantly less than a time required for
floatation of vapor bubbles generated by said electrical heating
pulses to the upper section of the central feeding conduit.
7. The pumping unit of claim 1, wherein said second check valve is
of a normally open type and wherein said first check valve is of a
normally open type.
8. The pumping unit of claim 1, wherein said second check valve is
of the normally closed type and wherein said first check valve is
of a normally open type.
9. The pumping unit of claim 1, wherein the electrical heating
element is of a resistive type.
10. The pumping unit of claim 1, wherein the electrical heating
element is of an inductive type.
11. The pumping unit of claim 1, wherein said separate pulses are
under high pressure of at least about 1.5 atmospheres.
12. A pumping unit for feeding liquid cryogen from a Dewar flask,
comprising: a central feeding conduit; seal means for sealing said
central feeding conduit to the Dewar flask; two check valves
installed on an upper section and a lower section respectively of
said central feeding conduit; an electrical heating element,
situated in immediate contact with or adjacent a section of said
central feeding conduit, said section being above and adjacent to
said lower check valve; a power-control unit supplying pulses of
electrical current to said electrical heating element; and wherein
the liquid cryogen is fed through said central feeding conduit from
the Dewar flask.
13. The pumping unit of claim 12, wherein the upper check valve is
of a normally closed type.
14. The pumping unit of claim 12, wherein the lower check valve is
of a normally open type.
15. The pumping unit of claim 12, wherein the electrical heating
element functions as a resistor.
16. The pumping unit of claim 12, wherein the electrical heating
element comprises a combination of an inductor and an adjacent
section of the central feeding conduit, the adjacent section
comprising a ferromagnetic material.
17. The pumping unit of claim 12, further comprising a condensation
section of the central feeding conduit, the condensation section
including a plurality of outer fins.
18. The pumping unit of claim 12, further comprising a condensation
section of the central feeding conduit, the condensation section
including a plurality of internal fins.
19. The pumping unit of claim 12, wherein said central feeding
conduit further comprises a section constructed as a bellows.
20. The pumping unit of claim 12, further comprising a buffering
vessel in fluid communication with an outer section of the central
feeding conduit, said buffering vessel comprising a safety valve
and a pressure gauge.
21. The pumping unit of claim 20, wherein said buffering vessel
further comprises a heater for evaporating the cryogen provided
from said Dewar flask.
22. The pumping unit of claim 21, wherein said buffering vessel
further comprises an outlet connection and a shut-off valve.
23. The pumping unit of claim 21, wherein the buffering vessel is
equipped with a safety valve and a pressure gauge.
24. The pumping unit of claim 12, wherein the lower section of the
central feeding conduit comprises a plurality of branches, each
branch being provided with an independent check valve, and an
electrical heating unit, the pumping unit further comprising a
sensing unit and a power control unit, wherein said sensing unit
detects an angle and direction of inclination of said Dewar flask
and wherein said power-control unit energizes a selected electrical
heating unit according to data communication from said sensing
unit, to heat a branch that is immersed with its proximal end into
the liquid cryogen in said Dewar flask.
25. The pumping unit of claim 23, further comprising a bellows
section incorporated into each branch of the central feeding
conduit.
26. The pumping unit of claim 12, wherein the central feeding
conduit includes an external vacuum insulation in the form of a
vacuum insulated jacket; a proximal edge of said vacuum insulated
jacket is sealed with the central feeding conduit above the lower
check valve and a distal edge of the jacket is sealed with said
central feeding conduit distally to the upper check valve and
externally to the Dewar flask.
27. The pumping unit of claim 25, wherein said jacket further
comprises an internal threading, such that an internal diameter of
said jacket is fitted to an outer diameter of the central feeding
conduit.
28. The pumping unit of claim 27, wherein outer sections of said
vacuum insulated jacket and said central feeding conduit comprise a
flexible bellows.
Description
FIELD OF THE INVENTION
[0001] The invention relates to a pumping unit and, in particular,
to a high pressure pump, for example for delivery of a liquid
medium such as liquid cryogen from a vessel with sufficiently high
pressure, while maintaining low pressure in the vessel itself.
BACKGROUND OF THE INVENTION
[0002] There are some US patents describing pumping systems, which
operate on the basis of a geyser principle.
[0003] U.S. Pat. No. 4,552,208 describes an apparatus and method
for circulating a heat transfer liquid from a heat collector to a
heat exchanger which is located at a level below that of the heat
collector by at least partially vaporizing the heat transfer liquid
in the steeply sloped collector and the vapor/liquid rises in a
series of "slugs" to a condenser located adjacent the top end
thereof. The vapor is condensed and the hot liquid is forced
downwardly to the heat exchanger by the pressure of the rising
slugs of vapor and liquid. After giving up useful heat in the heat
exchanger the now cooled liquid is recirculated to the condenser
and thence to the collector.
[0004] U.S. Pat. No. 4,611,654 teaches a passive heat transfer
system wherein the vapor generated by the boiling of a working
fluid is harnessed to transport the working fluid from a heat
source to a heat sink below the heat source. A passive circulation
unit is installed in a heat transfer system between the outlet port
of a heat collector and a collector drain duct that leads to a heat
sink that is positioned below the heat collector. In preferred
embodiments, a collector feed duct permits fluid to return to the
heat collector from the heat sink and a check valve prevents flow
in the opposite direction. The passive circulation unit includes an
upper chamber and a lower chamber disposed in vertical array, with
the lower end of the lower chamber being positioned above the heat
collector outlet port. In the simplest embodiment, the two chambers
are connected by a vent duct that leads from the bottom region of
the lower chamber to the top region of the upper chamber. The
collector drain duct connects to an opening in the lower end of the
upper chamber. In a second disclosed embodiment, the passive
circulation unit is fitted with a valve that intermittently
interrupts the flow of working vapor through the lower chamber and
thereby causes working fluid to be displaced into the vent duct and
expelled therefrom into the upper chamber in a cyclical manner.
[0005] U.S. Pat. No. 4,676,225 describes a geyser pump and a geyser
pumped heat transfer system having a multitude of heat absorbing
tubes from which heated liquid is pumped into a vapor/liquid
separator by geyser action enhanced by positive vapor bubble
generation apparatus and flow control methods. A vapor condenser in
communication with the separator recovers heat contained in the
vapor bubbles and maintains low separator pressure. Pumping starts
and stops in response to temperature differences and the pumping
rate is proportional to the heating rate. For bubble generation a
small volume of the working fluid is isolated in good thermal
contact with the absorbing tube and an aperture is formed in
communication between the isolated volume and the main volume of
working fluid. The small volume of working fluid can be enclosed by
inserting into the geyser pump tube a device in the form of a
flanged cylinder or a U-shaped tube. Vapor forms readily in the
isolated volume and a vapor.+-.liquid interface at the aperture
minimizes superheating in the liquid. A directional flow
constriction in the absorbing tube which may be in the form of a
check valve improves pumping rates and minimizes oscillations which
may be produced by the pulsed flow inherent in a geyser pump
system. A flow restriction which may be in the form of an orifice
or reduced tube diameter moderates peak flow rates by locally and
transiently increasing static pressure in expanding bubbles.
[0006] U.S. Pat. No. 6,042,342 describes a fluid displacement
system having a pressure vessel, an expansion vessel, first and
second tubes in fluid communication with the two vessels, and an
energy source. Fluid contained within the system is transferred
from one vessel to the other by activating the energy source, which
in turn generates pressure in the pressure vessel. The generated
pressure in the pressure vessel, in turn, displaces the fluid in
the expansion vessel.
[0007] Each of the above patents teach a proposed solution which is
not useful for cryogenic devices, but instead is only useful for
the taught application.
SUMMARY OF THE INVENTION
[0008] None of the above background art references teaches or
describes a high pressure pump of the geyser type that is at least
partially inserted into a vessel that is capable of delivering a
liquid or liquid-gaseous medium at high pressure while maintaining
low pressure in the vessel itself. A pumping unit according to the
present invention overcomes these drawbacks by providing such a
pump that delivers a liquid medium (and/or a liquid-gaseous medium)
from a low pressure vessel such that the delivered medium has
sufficiently high pressure, by providing the liquid medium in the
form of separated pulses. The pump preferably features a conduit
embedded into the vessel, such that the proximal end of this
conduit is situated in the vicinity to the bottom of the
vessel.
[0009] By "high pressure" it is meant at least about 1.5
atmospheres, preferably at least about 2 atmospheres and more
preferably at least about 10 atmospheres.
[0010] The lower section of the conduit is preferably provided with
at least a first check valve, which, preferably, is normally open.
In addition, the lower (boiling) section of the conduit is
preferably provided with an electrical heating element, more
preferably of low thermal inertia, and a layer of an outer thermal
insulation to reduce heating of the surrounding liquid medium by
the electrical heating element. The electrical heating element can
be a resistive heating element, or a heating inductive element. The
electrical heating element receives pulses of DC or AC, for example
preferably from an outer power-control unit.
[0011] There is preferably a condensation section of the conduit;
this section is situated in immediate vicinity of the
aforementioned boiling section and, preferably, in the immediate
vicinity of the bottom of the vessel; therefore, this condensation
section in the operation state of the pumping means is immersed
into the liquid medium in the vessel.
[0012] It should be noted that the duration of the electrical
heating pulses is preferably significantly less than the time
required for vapor that is generated by these pulses to rise to the
upper section of the central feeding conduit. Instead, preferably
the gas is formed but then cools in the upper section of the
central feeding conduit, returning to a liquid state before exiting
the conduit. The upper section of the conduit is provided with a
second check valve of open or closed types.
[0013] As described in greater detail below, an exemplary,
non-limiting embodiment of a pump according to the present
invention may be provided wherein the vessel is a Dewar flask and
the liquid or liquid-gaseous medium is a liquid cryogen. In this
case, the pump is called a siphon.
[0014] The pumping unit of the present invention comprises a
central feeding conduit, which is preferably largely positioned
within the Dewar flask such that at least about 50% and more
preferably at least about 60%, and most preferably at least about
75% of the central feeding conduit is positioned within the Dewar
flask. Its lower section is situated in the Dewar flask and the
upper section is located outside the Dewar flask; a sealing unit,
preferably in the form of a annular rubber ring, allows
installation of the pumping unit in the Dewar flask neck. A section
of a tubular piece surrounding the central feeding conduit is
joined sealingly with the annular rubber ring. The tubular piece
acts as a jacket and will be named in the following text
"jacket".
[0015] According to preferred embodiments of the present invention,
the central feeding conduit is preferably fabricated from a metal
including but not limited to brass, stainless steel etc.
[0016] The upper edge of the external conduit or jacket is sealed
with the outer section of the central feeding conduit.
[0017] Two check valves are installed on the central feeding
conduit: a lower check valve and an upper one. The upper check
valve can be positioned in the upper or middle internal spaces of
the Dewar flask or outside the Dewar flask. The lower check valve
is positioned near the lower end of the central feeding
conduit.
[0018] The upper check valve may optionally be either of the type
that is normally closed or normally open, and the lower check valve
may optionally be of the normally closed type or of the normally
open type. When the first or lower check valve is open, cryogen
enters into the central feeding conduit via this first check valve
under hydrostatic pressure of the cryogen in the Dewar flask.
[0019] Preferably an electrical heating element is positioned on
the central feeding conduit in the immediate vicinity of the lower
check valve and somewhat above it. This electrical heating element
is preferably of low thermal inertia.
[0020] The electrical heating element may optionally be of the
resistive and/or electromagnetic inductor types. In the second
case, the section of the central feeding conduit, which is
surrounded by the electromagnetic inductor, preferably contains
elements from ferromagnetic material. In such a way, in the second
case, the electrical heating element consists of the inductor and
the ferromagnetic tubular section of the central feeding conduit
surrounded by the inductor.
[0021] The electric heating element is optionally and preferably
thermally insulated from its outside, which is faced outwardly in
respect to the central feeding conduit.
[0022] A source of electrical current (AC or DC) is situated
outside the Dewar flask and connected with the electric heating
element (the resistor or the inductor) by wires. This source can be
named as a control-power unit. The control-power unit ensures
delivery of electrical current to the electrical heating element in
the form of separated pulses. It should be noted, that in the case
of AC application, the frequency of the pulses of the electrical
current is preferably some orders of magnitude lower than the
frequency of the applied AC.
[0023] Delivery of a pulse to the electrical heating element causes
the liquid cryogen to boil in the internal space of the central
feeding conduit in the section, which is in contact with the
electrical heating element, resulting in sharp elevation of its
pressure. As a result, the lower check valve closes; the high
pressure portion of the liquid-gaseous cryogen then causes the
upper check valve to open. Thereafter, as the result of heat
exchange between the central feeding conduit and the liquid cryogen
in the Dewar flask, the evaporated portion of the cryogen in the
central feeding conduit condenses again while reducing the pressure
in the central feeding conduit. The lower check valve then opens
and the upper check valve closes.
[0024] The internal surface of the section to be heated by
electrical pulses can be provided with internal fins or a porous
coating with open porosity, which facilitates boiling process of
the liquid cryogen contained in this section.
[0025] The electrical heating element can be provided with outer
thermal insulation allowing diminishing heat losses to the liquid
cryogen in the Dewar flask and outside the central feeding
conduit.
[0026] The upper section of the central feeding conduit, which is
adjacent to the section with the electrical heating element, can be
provided with means improving heat exchange with the surrounding
liquid cryogen. This ensures quick cooling and condensation of the
vapors obtained by pulse-wise heating of the lower section, which
is in immediate contact with the electrical heating element. These
means may optionally be realized as external and/or internal
fins.
[0027] The portions of liquid-gaseous cryogen under sufficiently
high pressure caused by its partial evaporation by pulses of
electrical current can be supplied immediately onto a target area
to be cooled via the outer section of the central feeding
conduit.
[0028] In another embodiment, the portion of the gaseous-liquid
cryogen under high pressure is introduced via the upper check valve
into a buffering vessel, which is provided with an evaporation
member and an outlet connection with a shut-off valve for supplying
the evaporated pressurized cryogen. In addition, the buffering
vessel is preferably equipped with required safety and measuring
mechanisms (a pressure gauge, safety and relief valves etc), to
prevent build up of excessive pressure.
[0029] The parameters of electrical pulses supplied to the
electrical heating element can be adjusted by the control-power
unit in accordance with the pressure in the buffering vessel.
[0030] Optionally a bellows section may be incorporated in the
central feeding conduit; the expansion and contraction of this
bellows section dampens any rapid elevation of pressure in the
central feeding conduit.
[0031] Optionally and preferably, other safety and relief valves
are installed on the outer section of the aforementioned jacket of
the pumping unit.
[0032] Preferably, a pressure gauge is installed on the outer
section of the jacket which serves for measuring pressure in the
Dewar flask.
[0033] The lower edge of the central feeding conduit may optionally
be provided with a filter in order to collect mechanical particles
contained in the supplied liquid cryogen.
[0034] The lower section of the internal surface of the jacket can
be provided with a divider for dividing the upper and lower
internal spaces of the Dewar flask, with the divider featuring high
hydraulic resistance for passage of the gas through it. This
prevents the liquid cryogen in the Dewar flask from being forced up
and out in the case of opening the relief valve of the pumping
unit. The divider may optionally comprise an internal threading of
the jacket with an internal diameter, which fits the outer diameter
of the central feeding conduit. Such an embodiment enables the
spiral groove of the threading to present a high hydraulic
resistance, which prevents boiling and overflow of the liquid
cryogen in the Dewar flask when opening the relief valve.
[0035] In addition, the pumping unit of these embodiments of the
present invention can be provided with an inlet port in its jacket
for introducing pressurized gas into the Dewar flask in order to
establish a required pressure in it.
[0036] The pumping unit of these embodiments of the present
invention, which is partially situated in a Dewar flask, is
optionally provided with a shut-off valve positioned distally to
the upper check valve on the outer section of the upper feeding
conduit.
[0037] However, it is possible to obviate application of this
shut-off valve because the electrical heating element in
combination with the lower and upper check valves may instead
optionally fulfill the role of the shut-off valve. In this case,
preferably the central feeding conduit includes an external vacuum
insulation in the form of a vacuum insulated jacket; the proximal
edge of this jacket is preferably sealed with the central feeding
conduit above the lower check valve and its distal edge is sealed
with the central feeding conduit distally to the upper check valve
and externally to the Dewar flask itself.
[0038] The outer sections of the vacuum insulated jacket and the
central feeding conduit are preferably implemented as flexible
bellows, thereby enabling the use of liquid neon as a cryogen with
significant reduction of operation temperature of the geyser pump
of the present invention in comparison with application of liquid
nitrogen as the cryogen.
[0039] According to some embodiments, the Dewar flask may
optionally be used as a fuel tank with LNG (liquid natural gas),
for example for installation in a vehicle. For such embodiments
preferably the pumping unit is still able to ensure delivery of LNG
under different inclination angles of the Dewar flask. Preferably
the lower section of the central feeding conduit is divided into a
plurality of branches, in which each branch is provided with an
independent check valve and an electrical heating unit.
[0040] In addition, a sensing unit supplies to the power-control
unit data regarding an angle and direction of inclination of the
Dewar flask. For example, two clinometers can play a role of such
sensing unit. In such a way, in accordance to the data of the
sensing unit, the power-control unit energizes the electrical
heating unit, which is related at a certain moment to the branch
with its proximal end immersed into liquid cryogen (for example,
into LNG). A bellows' section can be incorporated into each branch
in order to provide required flexibility to this construction.
BRIEF DESCRIPTION OF THE DRAWINGS
[0041] FIG. 1a and FIG. 1b show an axial cross-sectional view of a
Dewar flask with a pumping unit installed in its neck, when an
upper check valve is positioned inside of the Dewar flask (FIG. 1a)
or outside of the Dewar flask (FIG. 1c).
[0042] FIG. 1c shows an enlarged axial cross- and a sectional view
of the upper section of the Dewar flask and the pumping unit.
[0043] FIG. 1d shows an axial cross-sectional view of the lower
section of the Dewar flask and the pumping unit.
[0044] FIG. 2 shows an enlarged axial cross-sectional view of the
lower section of the Dewar flask and the pumping unit with an
inductor used as an electrical heating element.
[0045] FIG. 3 shows an axial cross-sectional view of a pumping unit
with a bellows section incorporated into the central feeding
conduit.
[0046] FIG. 4 shows an axial cross-sectional view of a Dewar flask
with the pumping unit installed in its neck and a buffing vessel
equipped with an evaporating member.
[0047] FIG. 5a shows an axial cross-sectional view of a Dewar flask
with the pumping unit installed in its neck and a split lower
section of the central feeding conduit.
[0048] FIG. 5b shows an axial cross-sectional view of the lower
section of a Dewar flask according FIG. 5a.
[0049] FIG. 6 shows an axial cross-sectional view of a Dewar flask
according to some embodiments of the present invention, featuring a
vacuum insulated jacket that is situated partially in the Dewar
flask and partially outside of the Dewar flask
DESCRIPTION OF PREFERRED EMBODIMENTS
[0050] FIG. 1a shows a Dewar flask 101 with neck 102, which is
intended to be filled with a liquid cryogen to be supplied by the
pumping unit 120. Pumping unit 120 comprises a central feeding
conduit 103 for supplying the liquid cryogen to an external
location, and jacket 104 surrounding the central feeding conduit
103 with gap 117 formed between them. The central feeding conduit
103 comprises an external section 111. The upper edge of jacket 104
is sealed with the central feeding conduit 103 as shown. An annular
rubber ring 105 is installed on jacket 104 and inserted partially
into neck 102, for holding pumping unit 120 in Dewar flask 101 and
for sealing jacket 104 to the Dewar flask 101. Also, preferably a
shut-off valve 108 is installed on the external section 111 of the
central feeding conduit 103. The shut-off valve 108 ensures control
of the supply of the liquid cryogen.
[0051] In a preferred embodiment, preferably safety and relief
valves 109 and 110 are installed on ports of the outer section of
jacket 104 for releasing the pressure in the Dewar flak 101. Jacket
104 also preferably features a pressure gauge 114 which is
installed on the external section 111 of the central feeding
conduit 103 for measuring internal pressure in the Dewar flask
101.
[0052] The lower section of the internal surface of jacket 104 is
provided with an internal threading 115 with an internal diameter,
which fits the outer diameter of the central feeding conduit
103.
[0053] Two check valves are installed in the internal section of
the central feeding conduit: a lower check valve 106 and an upper
check valve 119.
[0054] An electrical heating element 107 is positioned onto the
central feeding conduit 103 in the immediate vicinity of the lower
check valve 106 and somewhat above it. This electrical heating
element 107 is preferably of low thermal inertia, but may
optionally be of the resistive and/or electromagnetic inductor
types. The electric heating element 107 is optionally and
preferably thermally insulated from its outside with a thermal
insulation 123.
[0055] A control-power unit 116 of electrical current (AC or DC) is
situated outside the Dewar flask 101 and connected with the
electric heating element 107 by wires 112 and 113. This
control-power unit 116 ensures delivery of electrical current to
the electrical heating element 107 in the form of separated
pulses.
[0056] FIG. 1b shows the Dewar flask 101 with the pumping unit
designed similarly to that shown in FIG. 1a, but the upper check
valve 119 is installed in the central feeding conduit outside of
the Dewar flask 101.
[0057] FIG. 1c shows an enlarged axial cross- and a sectional view
of the upper section of the Dewar flask and the pumping unit 120.
Pumping unit 120 comprises a Dewar flask 101 with neck 102, which
is intended to be filled with a liquid cryogen to be supplied by
the pumping unit 120. The upper section of the pumping unit
comprises a central feeding conduit 103 and jacket 104 surrounding
the central conduit 103 with gap 117 formed between them. The upper
edge of jacket 104 is sealed with the central feeding conduit 103
as shown. Also a seal for sealing jacket 104 to the Dewar flask is
provided, along with an annular rubber ring 105 installed on jacket
104 and inserted partially into neck 102, for holding pumping unit
120 in Dewar flask 101. Also, preferably a shut-off valve 108 is
installed on the external section 111 of the central feeding
conduit 103. The shut-off valve 108 ensures control of the supply
of the liquid cryogen.
[0058] In the preferred embodiment, preferably safety and relief
valves 109 and 110 are installed on ports 129 and 128,
respectively, of the outer section of jacket 104 for establishing
and releasing the pressure in the Dewar flask 101. Jacket 104 also
preferably features a pressure gauge 114 which is installed on the
external section 111 of the central feeding conduit 103 for
measuring internal pressure in the Dewar flask.
[0059] The lower section of the internal surface of jacket 104 is
provided with an internal threading 115 with an internal diameter,
which fits the outer diameter of the central feeding conduit
103.
[0060] An upper check valve 119 is installed in the internal
section 122 of the central feeding conduit 103.
[0061] A control-power unit 116 of electrical current (AC or DC) is
situated outside the Dewar flask 101 and connected with the
electric heating element by wires 112 and 113. Opening 121 and 122
in jacket 104 serve for installation and routing of wires 113.
[0062] FIG. 1d shows an axial cross-sectional view of the lower
section of the Dewar flask and the pumping unit. It shows the Dewar
flask 101, the central feeding conduit 103, a lower check valve 106
that is installed in the central feeding conduit, and an electrical
heating element 107, which is positioned onto or adjacent the
central feeding conduit 103 in the immediate vicinity of the lower
check valve 106 and somewhat above it. A thermal insulation 123 is
optionally and preferably provided on the exterior of electric
heating element 107 for thermal insulation; electric heating
element 107 is preferably connected with a power-control unit via
wires or cables 113.
[0063] Delivery of each pulse to the electrical heating element 107
causes the liquid cryogen to boil in the internal space 122 of the
central feeding conduit 103 in the section which is in contact with
or adjacent the electrical heating element 107, resulting in sharp
elevation of its pressure. As a result, the lower check valve 106
closes; the high pressure portion of the liquid-gaseous cryogen
then causes the upper check valve 119 to open. Thereafter, as the
result of heat exchange between the central feeding conduit 103 and
the liquid cryogen in the Dewar flask, the evaporated portion of
the cryogen in the central feeding conduit 103 condenses again
while reducing the pressure in the central feeding conduit 103. The
lower check valve 106 then opens and the upper check valve 119
closes.
[0064] FIG. 2 shows an enlarged axial cross-sectional view of the
lower section of the Dewar flask and the pumping unit with an
inductor used as an electrical heating element. Components having
the same or similar function as those shown in FIG. 1 have the same
reference numbers.
[0065] An inductor 207 and a ferromagnetic tubular piece 224 are
optionally and preferably positioned onto or adjacent the central
feeding conduit 103, in this embodiment, in the immediate vicinity
of the lower check valve 106 and preferably somewhat above lower
check valve 106, for heating through induction. Inductor 207 is
optionally and preferably thermally insulated from its outside with
a thermal insulation 123 and connected with a power-control unit
(not shown) via cables 113.
[0066] FIG. 3 shows an axial cross-sectional view of a pumping unit
with a bellows section incorporated into the central feeding
conduit. Components having the same or similar function as those
shown in FIG. 1 have the same reference numbers.
[0067] A section 328 of the central feeding conduit 103 is
preferably situated adjacent to and above the section surrounded by
the electrical heating element 107, and preferably features outer
longitudinal fins 325 and internal longitudinal fins 326.
[0068] Optionally a bellows' section 327 of the central feeding
conduit 103, preferably situated above the finned section 328, is
provided for preventing a rapid rise in pressure of the central
feeding conduit 103. The bellows section 327 is preferably made of
an elastic material.
[0069] FIG. 4 shows an axial cross-sectional view of a Dewar flask
with the pumping unit installed in its neck and a buffering vessel
equipped with an evaporating member. Components having the same or
similar function as those shown in FIG. 1 have the same reference
numbers.
[0070] Optionally and preferably a buffering vessel 430 is in fluid
communication with the outer section of the central feeding conduit
103, for providing a constant or at least relatively steady supply
of the liquid medium. This buffering vessel 430 is equipped with a
safety valve 433 and a pressure gauge 432. In addition, an
electrical heater 434 is installed in the buffering vessel 430;
this electrical heater serves for evaporation the cryogen provided
from the Dewar flask 101. The electrical heater 434 is connected
with the power-control unit 116 via cables 435. The buffering
vessel 430 also preferably comprises an outlet connection 431 with
a shut-off valve 436.
[0071] FIG. 5a shows a Dewar flask 501 with neck 502, which is
intended to be filled with a liquid cryogen to be supplied by the
pumping unit 520. Pumping unit 520 comprises a central feeding
conduit 503, this central feeding conduit serves for supply of the
liquid cryogen to a target place, and jacket 504 surrounding the
central conduit 503 with gap 517 formed between them. The upper
edge of jacket 504 is sealed with the central feeding conduit 503
as shown. Also a seal for sealing jacket 504 to the Dewar flask is
provided, along with an annular rubber ring 505 installed on jacket
504 and inserted partially into neck 502, for holding pumping unit
520 in Dewar flask 501. Also, preferably a shut-off valve 508 is
installed on the outer section of the central feeding conduit 503.
The shut-off valve 508 ensures control of the supply of the liquid
cryogen.
[0072] In the preferred embodiment, preferably safety and relief
valves 509 and 510 are installed on ports of the outer section of
jacket 504 for establishing and releasing the pressure in the Dewar
flak 501. Jacket 504 also preferably features a pressure gauge 514
which is installed on the outer section of the central feeding
conduit 503 for measuring internal pressure in the Dewar flask
501.
[0073] The lower section of the internal surface of jacket 504 is
provided with an internal threading 515 with an internal diameter,
which fits the outer diameter of the central feeding conduit
503.
[0074] Two types of check valves are installed in the internal
section the central feeding conduit: lower check valves 506 and an
upper check valve 519.
[0075] Electrical heating elements 507 are positioned onto the
lower branches of the central feeding conduit 503 in the immediate
vicinity of the lower check valves 506 and somewhat higher than
them. These electrical heating elements 507 should preferably be of
low thermal inertia.
[0076] The electrical heating elements can be resistors or
electromagnetic inductors. The electric heating elements are
optionally and preferably thermally insulated with thermal
insulations 523.
[0077] A control-power unit 516 of electrical current (AC or DC) is
situated outside the Dewar flask 501 and connected with the
electric heating elements 507 by wires 512 and 513. The
control-power unit 516 ensures delivery of electrical current to
one of the electrical heating elements 507 in the form of separated
pulses and in accordance with data provided from a clinometer 524,
as a non-limiting example of a sensor for sensing angle of
declination (tilt). This clinometer 524 measures an inclination
angle and orientation of the Dewar flask 501 at a certain
moment.
[0078] As shown in FIG. 5b, the lower branches of the central
feeding conduit 503 may also be provided with a bellows section
525, preferably made of elastic material, to permit the branches to
be inserted into Dewar flask 501.
[0079] FIG. 6 shows an axial cross-sectional view of another
embodiment of Dewar flask with a vacuum insulated jacket situated
partially in the Dewar flask and partially outside of the Dewar
flask. In this embodiment, Dewar flask 101 with neck 102 is filled
with a liquid cryogen to be supplied by the pumping unit 620.
Pumping unit 620 comprises central feeding conduit 103 for
supplying the liquid cryogen to an external location, and has
jacket 104 surrounding the central conduit 103 with gap 117 formed
between them. Preferably, pumping unit 620 is held in Dewar flask
101 through some type of device, such as a ring 105 (which may
optionally be an annular rubber ring), installed on jacket 104 and
inserted partially into neck 102.
[0080] The central feeding lumen 103 is preferably surrounded by a
vacuum insulated jacket 630, which is sealed with central feeding
lumen 103 at the distal and proximal ends and which is located
within jacket 104, for providing a greater degree of thermal
insulation. Vacuum insulated jacket 630 preferably comprises an
internal jacket section 631 with its proximal end sealed with the
central feeding conduit 103 above the lower check valve 106; and an
external jacket section 632, which is sealed at its distal end with
the external section of the central feeding lumen 103. The central
feeding lumen 103 preferably also comprises an external flexible
section 633, which is optionally and preferably designed as a
bellows, to provide flexibility to a hose 634.
[0081] The operation of dewar flask 101 and pumping unit 620 is
substantially similar to that described previously, for example in
FIG. 1; however, the additional thermal insulation provided by
vacuum insulated jacket 630 further reduces heating of the
cryogenic material. External jacket section 632 is preferably
flexible, as is flexible section 633, so as to provide flexibility
to hose 634 during operation, for provision of the cryogenic
material through hose 634. Electrical heating element 107 also
replaces the on-off valve of FIG. 1 (element 108 in FIG. 1); pulses
of electrical current switch on the geyser pump due to heating of
electrical heating element 107, and their absence switches off the
geyser pump.
[0082] While the invention has been described with respect to a
limited number of embodiments, it will be appreciated that many
variations, modifications and other applications of the invention
may be made.
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