Note: Descriptions are shown in the official language in which they were submitted.
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"CYROGENIC PUMP AND INLET HEADER"
FIELD
[0001] In embodiments, a liquid inlet and pump head for a cryogenic
pumper
are provided, the header having a sump, a return conduit for unused liquid to
a
liquid source, and a freeboard for gas removal, the pump head having long
stroke,
low speed plunger and low back pressure valve assembly.
BACKGROUND
[0002] In many industries, including the oil and gas industry, liquefied
gases
are vaporized to a gaseous form for a variety of high volumetric operations
including
use of vaporized nitrogen liquid for delivery to subterranean destinations for
downhole stimulation. Nitrogen gas is one type of inert gas that can be used
to
reduce the hydrostatic pressure exerted by stimulation fluids. This minimizes
the
amount of fluid pumped into formation and enables rapid clean-up in low
pressure
reservoirs. Further, as a non-reactive gas, nitrogen can be used in a variety
of
ways to support pipelines and industrial facilities, including: displacement,
inerting
otherwise potentially flammable spaces, helium leak testing, pneumatic
testing,
purging, freeze plugs, accelerated cooling, blanketing, catalyst handling
support, hot
stripping and heating.
[0003] Liquid nitrogen is supplied in liquid form, in a cryogenic state.
Stimulation often occurs at high pressures in the order of 10,000 to 15,000
psi. The
nitrogen is pressurized to the high pressures using specialized cryogenic
pumping
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equipment. For the rates and pressure, multiple positive displacement pumps
are
used, arranged in parallel.
[0004] Liquid nitrogen, at very low temperatures is provided to a header
at
the inlet of the gang of pump heads at a pumper. The liquid enters each pump
head suction at a cold end, and is displaced from a displacement chamber by a
pressure stroke of reciprocating plunger of the pump head to discharge through
a
pump outlet at high pressure. The plunger returns and draws more liquid into
the
displacement chamber to repeat the cycle. The associated drop in suction
pressure
upon drawing fluid into the displacement chamber can alter the liquid
properties and
degrade pump performance, even to the point of eventual damage to the pumping
components. Further recirculation of un-used liquid during a pumping cycle is
returned to the source. The circulation and warming of the recirculating
liquid can
result in the entrainment of air with the liquid nitrogen.
[0005] Some of the symptoms of pump distress include cavitation, fluid
knock
or hammer, suction end vibration, reduced plunger life and catastrophic
failures in
the power end including plunger connecting rods, crankshafts and related
fasteners
and seals. Pump distress and failures are exacerbated by high stroke rates.
[0006] While the industry has been focused on net positive suction head
(NPSH) of the liquid delivered to the suction, poor quality of a liquefied gas
delivered to the pump head is a further factor exacerbating poor pump
behaviour
and failure.
[0007] Other areas of frustration for the field operator, pump heads can
suffer
short mean times between failures (MTBF) and repairs are typically performed
in a
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shop environment, requiring frequent transport of each failed pump head or
pump
offsite.
[0008] There is a desire for reduced incidences of pump repair, extended
MTBF, a field repair capabilities when a failure does occur.
SUMMARY
[0009] Herein, Applicant provides a manifold or header to the suction of
one
or more cryogenic liquid pump heads. The manifold provides suction
stabilization,
and thermal maintenance of the cold end of a cryogenic pump. For simplicity,
the
apparatus and methodology is described in the context of providing liquefied
nitrogen for the oil and gas industry although the apparatus and processes
described herein are equally applicable to the pumping of other liquids
handled in
both cryogenic liquid and vaporized gaseous forms.
[0010] Further, in instances of entrained gas, the manifold can also aid
in gas
desaturation of the liquid nitrogen provided to the nitrogen pumper. Applicant
has
determined that the liquid circulated between the source of liquid gas and the
cryogenic pump heads can entrain gas such as air or evolve N2 gas. N2 gas
evolution is exacerbated by warming of the conveyed cryogenic liquids.
Handling of
the liquid, including transfer through piping and vessels can result in the
incorporation of gas during transport or evolution of gas within the liquid,
resulting in
a gassy liquid. Gassy liquids, and the release of gas therefrom under pressure
reduction, including pump suction conditions and flow irregularities, increase
the
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handling difficulty and risk of damage for the form of positive-displacement
or other
pumps used in this area.
[0011] Herein, for convenience, the gassy liquids are referred to as gas-
saturated liquid regardless of the extent of saturation. The extent of gas
removal,
using embodiments described herein, is referred to qualitatively as moving
from a
saturated to a desaturated state even through the liquid may not be fully
saturated,
nor gas free respectively.
[0012] In one aspect, a manifold or intake header is provided having a
vessel
comprising liquid storage belly portion in a lower portion of the vessel, and
a gas
freeboard at a top of the vessel. Provision of a gas freeboard with a liquid
sump in
the belly portion aids gas separation from the liquid destined for the pump
suction.
A recirculation line removes excess liquid such as from a mid-vessel liquid
port or
from an optional launder after an overflow weir.
[0013] The belly portion includes a sump from which a substantially gas-
free
liquid is collected or stored and then drawn from for delivery to the pump
inlet. The
freeboard portion is a gas cap above the liquid sump for collection and
subsequent
removal of any gas released from the liquid stored for pump intake. The
removed
gas can be vented or recirculated to the cryogenic liquid supply.
[0014] In one embodiment, the liquid supplied to the header is separated
into
liquid pooled in the belly portion and any gas released from the liquid
collects in the
freeboard. Gas is removed from the freeboard leaving a desaturated liquid in a
sump of the belly portion. Desaturated liquid intended for the pump suction,
is
drawn from deep within the liquid sump. In an embodiment, the liquid is
delivered
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along the vessel through a distributor, the distributor releasing supplied
liquid
upwardly into the header for encouraging gas release to the gas freeboard, and
said
release further occurring within the level of the belly portion to minimize
gas portion
re-entrainment with the incoming liquid.
[0015] In an embodiment, the liquid supplied to the vessel is decanted or
overflows a tray weir and collects in a sump portion of the belly portion. The
desaturated liquid overflows the weir, intended for the pump suction, and is
drawn
the liquid sump.
[0016] In an embodiment, liquid removal by each pump suction is through a
conduit extending downward through the vessel, through the freeboard and into
the
liquid stored in the belly portion, to access the sump. The sump provides a
consistent liquid storage for control of the NPSH and supply of substantially
gas-
free liquid under the normal pumping conditions. The liquid removal conduit,
immersed in the cold liquid, maintains the low temperature delivery of liquid
to the
pump head.
[0017] As noted by Applicant, the described intake manifold or header
provides a constant, desaturated liquid flow to the cold ends of the pump
heads.
The intake header separates and eliminates flow of gas-saturated liquid to the
pump
heads and the operational problems associated therewith. Further, the sump and
liquid suction design, including routing through the interior of the header
itself, aids
in maintaining cold temperatures of the suction conduit and conveyed liquid to
the
heads. Any unused, oversupply of desaturated liquid is recirculated back to
the
liquid source tank.
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[0018] All cryogenic plunger pumps benefit from desaturation of entrained
air
or other gas from the liquid through the design of the intake manifold.
[0019] Broadly, an intake header for a high pressure displacement pump
head comprises a horizontal vessel having a liquid storage belly portion, a
gas
freeboard and a mid-vessel liquid input. One or more suctions extend from the
belly
portion to a suction of its respective pump head. In embodiments, the conduit
forming each suction extends upwardly from the sump, internal to the vessel,
and
exits through an upper wall of the vessel for connection to its respective
pump head
cold end. Gas exit ports are formed along the upper wall of the vessel and
collected
in a gas header.
[0020] In one embodiment, a tray divides the belly portion into an upper
liquid
receiving portion and a desaturated liquid sump therebelow. The tray extends
from
one end of the vessel for receipt of gas-saturated liquid, distribution
horizontally
along the header vessel, for separation of gas and for liquid. The gas reports
to a
freeboard and liquid decants from the tray for delivery of desaturated liquid
to the
sump.
[0021] In another aspect, Applicant has determined that pump head cold
end
performance is improved sufficiently to permit longer stroke operation with
reduced
incorporated gas-related problems resulting in maintenance of comparable
volumetric liquid pumping performance at lower pump stroke rates. Lower stroke
rates results in lower stress on pump components and longer MTBF.
[0022] In another aspect, valve design further improves cold end
performance. The implementation of a large cross-sectional liquid inlet area
results
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in a low pressure drop and minimizes gas-release, cavitation and other reduced
pressure liquid effects. Such valve design also results in pump head
configuration
having longer stroke operation for comparable volumetric performance at lower
pump stroke rates.
[0023] In another aspect seal arrangements result in reliable pump
plunger
sealing and ease of field installation and replacement, as a retrofit or as a
provided
sealing arrangements
[0024] In combination, both a desaturated liquid supply header and
improved
valve components, embodiments of both of which are provided herein, result in
a
reliable, long lasting cryogenic pump head.
[0025] Further, in other aspects, embodiments of the pump head design
enable field installation and repair including plunger stroke adjustment on
assembly
and plunger seal repair onsite.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Figure 1 is a process flow diagram of a manifold or intake header
according to one embodiment;
[0027] Figure 2A is a perspective drawing of an embodiment of the intake
header to the heads of a Quintuplex pump;
[0028] Figure 2B is a perspective drawing of the embodiment of Fig. 2A
with
the outer wall of the vessel and the collection header rendered transparent;
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[0029] Figure 3A is a perspective schematic view of a header illustrating
the
liquid supply to the header belly portion, a gas freeboard, liquid flow from
the sump
to each pump head, and liquid recirculation;
[0030] Figure 4A is an end cross-sectional view according to Fig. 3A;
[0031] Figure 3B is a perspective transverse cross-sectional view of a
header
illustrating a liquid supply distributor and suction conduit extending from
the sump to
one of the pump heads;
[0032] Figure 4B is an end cross-sectional view according to Fig. 3B;
[0033] Figure 3C is a perspective transverse cross-sectional view of the
header of Fig. 2B, illustrating a section through a suction conduit of one of
the five
pump heads;
[0034] Figure 4C is an end cross-sectional view according to Fig. 3C;
[0035] Figure 5 is a side view of the intake header of Fig. 2B, with the
internals shown in hidden lines;
[0036] Figure 6 is an end view of the intake header of Fig. 5 with the
internals
shown in hidden lines;
[0037] Figures 7A ¨ 70 illustrate various individual components of the
intake
header;
[0038] Figure 8A shows a partial cross-sectional side view of a triplex
pump
according to the prior art;
[0039] Figure 8B is a perspective view of a side cross-section of a pump
head illustrating the pump cylinder and pump plunger valve, seals and pony rod
connection. The pump inlet is shown as usual on the bottom of the pump
cylinder;
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[0040] Figures 9A and 9B are perspective views of the pump head of Fig.
8B,
with the pump cylinder (Fig. 9A) illustrated separately from the internal
components
(Fig. 9B);
[0041] Figure 10A is a side cross-sectional view of the pump head of Fig.
8B
with a first embodiment of the field installable plunger seals;
[0042] Figure 10B is a side cross-sectional view of the pump head of Fig.
8B
with an alternate embodiment of the field installable plunger seals and with
the pony
rod coupling shown removed, the clamp 132 shown installed in solid lines and
apart
in dotted lines;
[0043] Figure 10C is a close-up side cross-sectional view of the packing
sleeve and seals of Fig. 10A;
[0044] Figure 10D is a close-up side cross-sectional view of the packing
sleeve and seal of Fig. 10B;
[0045] Figures 11A and 11B illustrate the valve in operation, more
particularly
illustrating the beginning of the liquid intake stoke (Fig. 11A), and the
liquid
discharge stroke (Fig. 11B);
[0046] Figure 12 is an exploded view of the valve illustrating the flow
passages, seals and springs;
[0047] Figure 13 is a transverse cross-section of the cylinder and
plunger to
illustrate the splined internal cylinder sleeve;
[0048] Figure 14 is a transverse cross-section of the cylinder and
plunger to
illustrate the cross-flow ports at the end of the internal cylinder sleeve;
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[0049] Figures 15A and 15B are perspective ends view of the drive end of
the
pump head and illustrating the plunger end and plunger clamp apart (Fig. 15A)
and
assembled (Fig. 15B); and
[0050] Figures 16A and 16B are side cross-sectional views of the drive
end
of the pump head and illustrating the plunger and pony rod interface with
shims
added to adjust the plunger's piston head closer to the valve (Fig. 16A) and
shims
removed to adjust the plunger's piston head further from the valve (Fig. 16B),
the
shims permitting field adjustment of the pump head and drive.
DESCRIPTION
[0051] With reference to Fig. 1 a schematic illustrates an embodiment of
an
intake header coupled between one or more high pressure cryogenic pump heads
and a source of cryogenic liquid. Herein, the treatment and handling of the
cryogenic liquid is described in the context of providing liquefied nitrogen
for
pressurization and then vaporization in the field of fracking and hydraulic
lift
operations. Thus, while the description refers to Nitrogen (N2), in liquid and
gaseous forms, the apparatus and processes described herein are equally
applicable to other liquids capable of handling in both liquid and gaseous
forms.
[0052] A charge pump 10, such as a centrifugal pump, delivers a liquid
supply LS from a liquid source, such as a N2 tank 12 to an embodiment of the
pump
header 20. Gas G separates from the liquid LS and is directed back to the
source
or tank 12. Liquid LP is delivered to the cold end of each pump head 22 and
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pressurized liquid LV is directed to a vaporizer 24 for producing high
pressure gas
to the process.
[0053] In a first embodiment, a header 20 for one or more cryogenic pump
heads 22 is provided.
[0054] With reference to Figs. 2A and 2B, 5 and 6 the header 20 comprises
vessel 30 having a liquid intake 32 for receiving liquid nitrogen from the
source,
such as cryogenic tank 12. The vessel 30 is cylindrical and is oriented
generally
horizontally. In an embodiment, the intake 32 is coupled to a distributor 34
(Fig .2B)
extending generally horizontally along vessel 30 for delivery of liquid along
the
length of the vessel 20.
[0055] The intake 32 is located at about the axis of the vessel 30 with
discharge of the supplied liquid upwardly thereto. In embodiments, the intake
32 is
located in the liquid stored in the vessel.
[0056] Liquid intended for the pumper, is drawn from a sump 38 of a belly
portion 40 of the vessel 30. A freeboard portion 44 above the liquid in the
belly
portion 40 receives any gas released from the liquid or otherwise accompanying
the
liquid into the vessel. Liquid collects in the belly portion, the level of
which can be
controlled including by intake-discharge control, or pressure control of the
gas
collected in the freeboard.
[0057] A plurality of pump suctions 36,36,36 ... are spaced along the
length
of the vessel 30. To minimize disruption to the liquid supply to the pump,
each
pump head has its own pump suction 36 between the pump's cold end and the
sump 38. A portion of the pump suction 36 is also physically located in the
vessel,
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from a suction inlet 42 located in the sump 38, passing upwardly through the
cold
liquid stored in the belly portion, and passing upwardly through a freeboard
portion
44 above the liquid for exit from the vessel. The suction inlet 38 is immersed
in the
liquid in the vessel and remains cold, to minimize thermal disruption to the
liquid
directed to its respective pump head.
[0058] The horizontal distributor 34 delivers the liquid supply LS along
the
length of the vessel 30, such as through discharge of the liquid through a
plurality of
discharge a holes 47. The holes 47, such as circular or slots, can be located
along
an upper wall of the distributor 34 for aiding in gas/liquid separation; gas
separating
upwardly to the freeboard, and de-saturated liquid downwardly to the sump 38.
[0059] The length of the vessel and distributor 34 is dependent upon the
number of pump heads 22 for the pump, the spacing between pumps heads 22
dictating the spacing of pump suctions 36 and the length of the header vessel
necessary to accommodate the number of pump suctions 36. A vessel suitable for
a Quintuplex pump (5 pump heads) is shown, a shorter vessel could be employed
for a single pump and common triplex pumps (3 pump heads) as appropriate.
[0060] As shown in Figs. 3A and 4A, the vessel separates liquid and gas,
the
gas G reporting to the freeboard portion 44 and liquid L reporting to the
belly portion
40. The liquid supply LS is provided to the midpoint of the vessel. G gas
separates
from the liquid L and liquid LP for the pump heads 22 is drawn from the sump
38.
Gas GV, for venting or return to the liquid supply 12 is withdrawn from the
freeboard
portion 44. Liquid L is typically provided in excess of the amount of liquid
LP used
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by the pump heads and therefore a recirculation liquid LR is return to the
liquid
supply 12.
[0061] As shown in Figs. 3B and 4B, a portion of the vessel 30
incorporating
two horizontally spaced pump suctions 36,36 is shown. The distributor 34 is
shown
extending along the axis of the vessel 30. Liquid supply LS from the source
12, is
discharged to the vessel interior, such as through holes 47. A liquid
interface or
level LL is formed.
[0062] A port 46 for recirculation of excess liquid LR is provided at a
distal
end of the horizontal distributor 34. At a top of the vessel 30, a chamber 48
is
provided for the collection of gas G. One or more gas outlets 50 are provided
for the
controlled removal of collected gas. Equilibrium between gas arriving with the
liquid
supply LS, and gas removed from the vessel, can be controlled, including
through a
sized orifice, or needle valve, or large capacity valve fit with a bleed
orifice. A large
capacity valve at gas outlet 50, when opened, permits a large capacity, cold
liquid,
recirculation for startup, and when closed permits a small bleed flow of gas
therethrough to maintain a liquid gas interface in the vessel. While the
provision of
freeboard 44 provides a chamber for collection of separated gas G, separation
can
be further aided by low pressure drop release of gas from the distributor,
such as
through generously sized holes 47, and by releasing the liquid supply beneath
the
interface or liquid level LL.
[0063] As shown in Figs. 3C and 40, in this additional embodiment, the
length of the vessel 30 can also fit with a generally transverse extending
baffle for
forming an upper liquid storage thereabove, a still sump 38 below and liquid
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communication therebetween. One form of baffle can be an internal tray 60.
Saturated or partially saturated liquid supply LS containing some gases,
spills from
the distributor 34 into the tray 60. At least some gas G separates from the
liquid LS
and rises to the upper, liquid-free volume of the freeboard 44.
[0064] The liquid LS, which can still be partially saturated, flows into
the
upper liquid receiving portion of the tray 60 and collects until steady-state
operations in which the liquid level LL reaches a tray level TL, all the while
being
provided with an opportunity to release gas, after which the liquid spills
over a weir
portion 62 of the tray and into the lower desaturated liquid sump 38 in the
lower
volume of the belly portion 40.
[0065] Gas G in the freeboard 44 is collected in the chamber 48 along an
upper wall of the vessel 30 for return to the source tank. As stated, the gas
outlet
50 can be controlled to meter the gas exiting the vessel, controlling the
liquid level
LL. Other known liquid level controllers can be employed.
[0066] As above, the de-saturated liquid LP intended for the pumper, is
drawn from the sump 38. To minimize disruption to the liquid supply to each
pump
head 22, each pump head has its own suction 36. Each suction 36 is a conduit
also
physically located in the vessel, having liquid inlet 42 immersed in the
liquid of the
sump 38, the conduit of the suction passing through the freeboard 44 and
through
the upper wall of the vessel 30 for connection to the cold end of the pump
head 22.
The suction 36 and a large portion of the conduit forming the suction, in this
embodiment being greater than half the length, is immersed in the liquid of
the
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sump and remains cold, minimizing thermal disruption to the liquid directed to
its
respective pump head.
[0067] The tray 60 is shaped, in cross-section as a letter "J"-shape or
eaves-
trough shape, having a raised tip or spillover weir 62 at a lower end. The
generally
vertical portion 64 of the upper stem of the "J"-shape separates the
gas/liquid
separation volume of the freeboard from the conduit of the pump suction 36
rising
from the sump 38 to exit the vessel 30. One or more portals 66 in the upper
wall of
the vessel permit gas therein to be collected in the discharge header or
chamber
48.
Example:
[0068] A vessel about 3.5 feet long and 8 inches in diameter can process
150
USgpm for supplying a triplex pump (three (3) pump heads 22 and corresponding
suctions 36) and 300 USgpm for a quintuplex pump (five (5) pump heads 22 and
corresponding suctions 36). The saturated liquid enters via a 2 inch (Sch 40)
pipe
as a distributor 34 with a plurality of exit holes 47 formed along the wall
along the
top, in this embodiment twenty-eight (28) holes are shown, each about 0.375
inches
in diameter. Gas exits through openings 66 along the top of the 8 inch vessel.
For
integrity, the openings are spaced apart with vessel structure therebetween,
formed
as several (three) 1.75" wide slots, each 10 inches long, aligned end to end.
Each
suction 36 is 1.25" (Sch 40) is a pipe with a 90 elbow as an inlet 42. The gas
chamber 48 can be a 2" (Sch 40) pipe cut longitudinally along its axis for
forming a
half-pipe to sealably cover the openings 66.
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[0069] PUMP HEAD
[0070] The cryogenic pump 22 contemplated herein is a plunger-type pump
having a reciprocating plunger. One pump of a prior art triplex pump is shown
in
Fig. 8A, the figure drawn from issued US Patent 8543245B2 issued 2013-09-24 to
Halliburton. As shown a conventional arrangement is a pump head 90 having a
plunger 91 that alternately draws liquid through a one way intake valve 92
into a
pump chamber 94 and then pushes the liquid out of the chamber through a one
way
discharge valve 95. The chamber 94, plunger 91, valves 92,95 and seals 96 for
the
plunger are part of the pump head 90, otherwise known as a cold end. The
plunger
91 is driven in a reciprocating manner by a crankshaft 97 and drive
arrangement 98.
[0071] In the case of the cold end, conventional problems with volumetric
pumping capacity and reliability are usually related to the inflow and outflow
of liquid
nitrogen on the return stroke of the plunger. Flow restrictions, resulting in
high dP
across both intake and discharge, can result in one or more of flashing of gas
from
the liquid and cavitation, resulting in damage to the components.
Conventionally,
pump stroke is limited to minimize such phenomenon and lessen damage
associated therewith. A limitation on plunger stroke and pumping stroke rate
limits
pump capacity.
[0072] Herein, the axial length of the stroke of the plunger has been
significantly increased without degradation of the fluid handling performance.
Indeed fluid handling is improved. Applicant has directed the improvement in
design to mechanical reliability and ease maintenance rather than increasing
pump
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output. Industry output rates are maintained while reducing the stress on the
pump
components.
[0073] In an embodiment, Applicant has adapted having about three times
the stroke length which results in three times the volume of fluid per stoke.
Accordingly, given a design flow rate, one can pump the same flow rate as the
prior
pumps at one third (1/3) the stroke speed.
[0074] The reduced stroke speed of the reciprocation of the plunger
results in
multiple improvements in mechanical component life. The conventional pump
comprises a drive including a motor and a gear box, a crank, a piston or pony
rod
and a piston plunger, the plunger reciprocating in the pump head. Seals are
located
between the moving plunger and a cylinder head and also within one-way or
check
valves to regulate liquid intake to the cylinder chamber.
[0075] Reduction of the speed of the plunger results in reduced wear on
seals and the check valve. Heat generated by the reciprocating plunger and
seal
friction is reduced. Forces are reduced on the piston rod connections, the
gear box
and the motor.
[0076] Herein, additional improvements include an improved liquid inlet
and
discharge head, and improved seals. The seals are both simpler and shorter.
The
plunger and cylinder are longer and better supported for co-axial alignment.
[0077] Further, various improvements are possible to aid in field
maintenance
including ease of installation and seal and head repair. During installation,
the head
needs to be aligned with the plunger to minimize seal misalignment and wear
resulting therefrom. Further, the connection between the piston and the pony
rod
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needs to be carefully set to avoid bottoming out the end of the piston and the
head
whilst ensuring maximal pump performance.
[0078] Further, after some time, seals will wear and require repair. Here
prior
art seals need to be repaired in a shop setting, herein a seal cartridge or
sleeve is
provided that can be replaced in the field.
[0079] In more detail and with reference to Fig. 8B, pump head 100
supports
a cylinder such as a cylinder sleeve 102 supported in a pump housing 104 and
having a pump plunger 106. The plunger 106 is slidable within the sleeve 102
for
alternately increasing and decreasing the pump chamber 108 within. The plunger
106 is has a piston end 110 that reciprocates in the cylinder sleeve 102. The
cylinder head 112 is a cylindrical body arranged axially opposing the piston
end
110. The piston end 110 is reciprocated away from a cylinder head 112 to
create a
suction in the chamber 108 so as to draw new liquid into the chamber 108
through
an intake valve 116. The piston end 110 is reciprocated towards the cylinder
head
112 to compress liquid in the chamber 108 against a cylinder head 112 and
discharge liquid through a discharge valve 114.
[0080] The piston end 110 is fit with a rider ring 120 and seals 122 for
sealing
the plunger's piston end 110 to the cylinder sleeve 102. The plunger 106 is
cylindrical, and is sealable in a tubular surround, the piston end 110
sealable in a
cylindrical cylinder sleeve 102 and the balance of the plunger sealable in a
cylindrical bore of the pump housing 104. Annular seals 124 are fit about the
plunger 106 at a tail or connection end 126 opposing the piston end 110.
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[0081] The plunger 106 is removably connected at the connection end 126
to
a pony rod (not shown) that is driven back and forth along a plunger axis by a
connection rod and crank arrangement. The pump housing 104 is secured to a
skid
or other structure, securing the housing 104 at a flange 128. The flange 128
is
secured to a fixed frame which is dimensionally set or also fixed
dimensionally for
locational stability relative to the connecting rod and crank arrangement.
[0082] As shown, the pump housing has an inlet 117 for the receipt of
cryogenic liquid FP. The inlet 117 is shown as usual and conventional, located
on
the bottom of the pump housing 104. Liquid can be provided by a header, such
as
that used in conventional ganged cryogenic pumps, or a header as set forth in
Figs.
1 through 7C.
[0083] From the valve end, the internal components comprise a valve
assembly 130 comprising the intake valve 116 and the discharge valve 114. The
intake valve 116 receives liquid through the liquid inlet 117 and the
discharge valve
114 discharges liquid through discharge outlet 115. The cylinder housing 104
supports the cylinder sleeve 102 within which the piston end 110 reciprocates.
The
piston end 110 is the leading end of the plunger 106 adjacent the cylinder
head.
The tail end 126 of the plunger 106 extends sealingly through the seal packing
124
for coupling to a pony rod end (not shown) by a rod end clamp 132.
[0084] Note that while other drawings may be oriented with the liquid
inlet
117 as oriented upwards, this is merely an artifact of the computer generated
drawings.
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[0085] Figs. 9A and 9B illustrate the cylinder housing 104 in isolation
and
internal components for housing therein respectively. From a discharge end of
the
cylinder housing 104, an installation bore 105 is provided for axially
receiving the
cylinder sleeve 102 and valves 114,116. From the tail end 126, the housing 104
comprises a packing bore 107 for receiving a seal assembly including the seal
packing 124.
[0086] Fig. 10A is a side cross-sectional view of the internals according
to
Fig. 9B and having a first embodiment of a field installable seal assembly
including
the plunger seals 124. The seals 124 are housed in a packing sleeve 140. The
packing sleeve has a plunger bore for receiving the plunger 106 therethrough.
When the pony rod¨to-plunger clamp 132 is removed, a packing nut 142 can be
removed and the entire packing seal sleeve 140 and contained seals 124 can be
removed for replacement.
[0087] The packing sleeve 140 has a first proximal shoulder or inboard
lip
150 at an inboard end and a distal shoulder 144 at an outboard end. The
inboard
lip 150 axially supports the seal pack 124 firstly as a stop for enabling
axial retention
of the seal pack 124 therein and as a pull structure enabling removal of the
seal
pack 124 as a complete set of otherwise individual seals, the sleeve 140 and
seals
124 removable over the tail end 126 of the plunger 106. The proximal lip 150
of the
packing sleeve 140 is sealed, such as at an 0-ring 146, for sealing the sleeve
140
to the pump housing 104. The opposing or outboard end of the sleeve 140 is
open
for axially receiving the seals 124.
CA 02957321 2017-02-08
[0088] Fig. 10B is a side cross-sectional view of the field installable
plunger
seals and according to a second embodiment having a reduced number of seal
components and hence being a less expensive seal. The seal sleeve 140 and
packing 124 can be of the same length as that of Fig. 10A, such as for ease of
retrofitting a seal of the first embodiment with a seal of the second
embodiment.
Alternatively, as shown, the seal sleeve 140 and packing 124 can be axially
shorter,
such as by incorporating a fewer number of hat or lip seals. A shorter seal
can
resulting in a shorter pump housing when engineered in combination.
[0089] With reference to Fig. 100, in greater detail, and illustrated
from left to
right, the inboard lip 150 of the sleeve 140 is shoulder 150 having opposing
shoulder faces, one inboard face against the pump housing 104 and the other
outboard face against the seal pack 124.
[0090] The seal pack 124 of Figs.10A and 10B comprises a first seal
adjacent the inboard end, a stack of lip seals adjacent the outboard end, and
a
spacer therebetween. The entire seal pack is axially retained to the sleeve
140 and
the sleeve is retained to the housing 104. The first seal, is axially
compressible by
the balance of the seal pack 124 to actuate a radial energizing profile such
as a
wedge to drive the seal against the plunger 106.
[0091] The first seal can comprise a first ring seal carrier 152 at the
proximal
end adjacent the outboard face of the inboard lip 150. The ring seal carrier
152
supports a rod seal 158 that is axially compressible to actuate a radial
energizing
profile to drive the rod seal 158 into sealing engagement with the plunger
106. The
carrier 152 forms an annular space to the plunger 106 for supporting a ring
seal
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compressor 156 axially slidable therein and a spring 157, such as a Belleville
washer, for energizing the structure of the compressor 156 relative to a
carrier
shoulder 150b. The carrier shoulder 150b is sealably supported at the sleeve's
inboard shoulder 150. Compressor 156 has a ramp or wedge corresponding to a
matching wedge on the rod seal 158 for driving the rod seal 158 radially
inwardly
and sealably against the plunger 106.
[0092] Next is a lantern ring 160 spacing the rod seal 158 from a series
of hat
seals assemblies 162,162 ... .
[0093] Six hat seal assemblies are shown, each seal assembly 162
comprising an annular seal spacer 164 having a generally square or slightly
trapezoidal cross section, and a hat seal 166 itself having a generally "L"
shape
supported over the seal spacer/spacer 164.
[0094] All of the ring carrier 152, lantern ring 160 and hat seal
assemblies
162 are supported in the plunger bore forming, a packer sleeve annulus. Axial
extraction of the packer seal sleeve 140, and support by the sleeve shoulder
inboard lip 150, pulls all of the seal components from the cylinder housing
104.
[0095] The packer seal sleeve 140 is releasably retained to the cylinder
housing 104 using a packer nut 170. The nut 170 has a narrow annular shoulder
172 that engages a hat ring 0-ring seal 176 that engages the packing seals
124.
The seals are compressed axially, for increasing the radial sealing
capability. The
axially engaged seals press on the seal sleeve shoulder, retaining the
assembly to
the cylinder housing 104. The nut can include a rider ring 179 for axial
alignment
with the plunger 106.
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[0096] Fig. 10D is a close-up side cross-sectional view of the alternate
packing sleeve and seal of Fig. 10B. The sleeve and seal are shown removed
from
the plunger. Again, from left to right, the sleeve and seal comprise from the
sleeve
shoulder 150: a rider ring 180 instead of a ring seal carrier and seals, an
extended
length lantern ring 182 and a diminished number of hat or lip seal assemblies
162.
The lantern ring 182 can be as long as needed to space the seal assemblies 162
from the rider ring 180 and, in some embodiments, to match the previous length
of
the first seal assembly for retrofit applications, or shortened so as the
entire sleeve
and seal assembly can be shortened.
[0097] Figs. 11A and 11B illustrate the intake and discharge valves
116,114
in operation. Fig. 12 illustrates the valve assembly 130 in exploded view
illustrating
various flow passages, seals and springs.
[0098] In greater detail, the valve assembly 130 is supported in the
cylinder
housing 104 at the piston end 110 of the plunger 106. The cylinder sleeve 102
is
first installed axially into the installation bore 105, and then the valve
assembly 130,
forming the liquid pumping end of the pump head 100. From the piston end 110
(right side, moving left), the cylinder sleeve 102 has a valve end 190 which
axially
supports and seal the cylinder head 112 thereto. The valve end 190 has a
stepped
bore for forming an annular sealing shoulder 191 for sealably and supportably
receiving the cylinder head 112, between the liquid inlet and the chamber 108.
The
valve end's stepped bore further forms a smaller diameter within the sealing
shoulder 191 for forming the pump chamber 108. The chamber 108, of variable
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axial extent, is formed between the piston end 110 of the plunger 106 and the
cylinder head 112.
[0099] The
intake valve 116 is operable against and works in combination
with a piston face of the cylinder head 112.
[0100] The
body of the cylinder head 112 has a plurality of intake ports
therein, arranged about the annular periphery of the cylinder head to access a
radial
periphery of the chamber, the intake ports being alternately opened and
blocked by
a ring-plate of the intake valve 116. The plurality of intake ports are
arranged and
spaced circumferentially about an annular valve seat on the face of the
cylinder
head. The
valve seat of the cylinder head 112 is fit with a plurality of
circumferentially-spaced inlet passages forming the intake ports 192 to the
chamber
108. The intake ports 192 are located between the fluid inlet and the chamber
108
for fluid communication therealong. The intake valve 116 comprises a ring-
plate
194 biased against, and to close, valve seat having the inlet ports 192
therein. The
ring-plate is an annular ring having a bore through which the piston end 100
can
reciprocate. The complementary annular faces of the cylinder head 112 at the
ports
192 and the ring-plate 194 seal when engaged.
[0101]
Radially within the annular valve seat, the face of the cylinder head
112 is concave or dished, having a truncated, right conical recessed portion
therein
and a face of the piston end 110 can also have a complementary convex
truncated,
right conical protruding portion. The
dished and protruding portions are
complementary to minimize the chamber volume on the discharge stroke.
24
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[0102] A coil spring 196 is fit operably between a shoulder the stepped
bore
of the cylinder sleeve piston end 190 and the ring-plate 194. The ring-plate
is
operable axially between open and closed positions. The ring-plate 194 is
movable
axially against the biasing of the spring 196 to move away from and open the
ports
192 as the piston end reciprocates away from an intake valve seat the cylinder
head
112. The ring-plate 194 is movable axially with the biasing of the spring 196
to
move towards the cylinder head 112 to close the ports 192 as the piston end
reciprocates towards from the cylinder head 112. The interface of the intake
valve
seat of the cylinder head 112 and ring-plate is a sealing interface, shown as
a
finished and complementary metal-to-metal surface.
[0103] The stepped shoulder of the cylinder sleeve can include an annular
and axially extending recess as an axial stop and to retain the coil spring
196 about
its periphery.
[0104] An annular inlet port 199 about the outer circumference of the
body of
the cylinder head fluidly communicates with the inlet ports 192. The annular
inlet
port aligns axially with the liquid inlet 117 in the cylinder housing 104 and
distributes
liquid received from the header about the annular inlet port for access to the
intake
ports 192.
[0105] The intake ports 192 are distributed and spaced circumferentially
about the intake valve 116 and provide significant cross-sectional area for
minimal
restriction to the incoming flow from the liquid inlet 117. Minimal pressure
drop
minimizes gas evolution. Liquid provided to the annulus inlet port is
distributed
thereabout to each port.
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[0106] The cylinder head 112 also supports the discharge valve 114
retained
in the installation bore 105 in the cylinder housing 104. The discharge valve
114 is
a one way valve having a valve plunger 200 biased by spring 202 closed against
an
annular valve seat 204 in the downstream side of the cylinder head 112. In
this
embodiment the plunger 200 is arranged along the axis of the valve assembly.
The
plunger has a valve face and a shaft 201 supporting the valve plunger 200 for
axial
movement between open and closed positions. An annular discharge passage 203
is formed axially through the cylinder head 112 and about the plunger 200 and
is in
fluid communication with the discharge port 115 through a discharge cover 206.
[0107] The discharge cover 206 is an annular plate having a plurality of
circumferentially spaced discharge passages 208 formed therein, also comprises
a
boss 209 and a bushing 211, located along the axis, for slidably supporting
the
plunger's shaft 201. The discharge cover 206 receives liquid flowing from the
annular discharge passage 203 of the discharge valve 114 and discharges same
to
the discharge outlet 115. A discharge valve retainer 210, having a discharge
bore
forming the outlet 115 therein, concludes the functional valve components. The
discharge valve retainer 210 retains the discharge cover 206 against the
cylinder
head 112.
[0108] Downstream from the discharge valve retainer 210, a retaining ring
nut 212, with wrench ports 214 arranged circumferentially thereabout,
threadably
engages the cylinder housing 104 to retain the valve components 114,116 and a
distal end 220 of the cylinder sleeve 102 axially against a main shoulder 222
of the
cylinder housing 104 (Figs. 9A,96). The retaining nut 212 engages a wear ring
216
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sized to the installation bore, extending all along the installation bore 105
to the
main shoulder 222.
[0109] Fit to the installation bore 105 are the wear ring 216 and the
discharge
valve retainer 210, with an 0-ring 230 sandwiched therebetween. The discharge
valve retainer 210 engages the ported discharge cover206, having a copper ring
seal 232 sandwiched therebetween. The ported discharge cover 21- supports the
boss 209 and coil spring 202 for guiding and biasing the discharge valve
plunger
200 upstream against valve seat 204. The ported discharge cover 206 engages
the
cylinder head 112, having a copper ring seal 234 sandwiched therebetween.
[0110] An outside diameter of the cylinder head 112 engages the cylinder
sleeve 190 and drives the sleeve against the housing's main shoulder.
Annularly
within the cylinder head end of the cylinder sleeve is an annular suction
valve
chamber. The suction valve, having an annular ring valve, is biased downstream
to
seal the inlet passages. The spring is sandwiched between the annular ring
valve
and annular chamber wall at the cylinder sleeve.
[0111] As shown in Fig. 11A, on the liquid intake stroke, the piston end
110
moves away from the cylinder head 112 and a low pressure results in the pump
chamber 108. The annular ring-plate 194 pulls away from the circumferentially
spaced inlet passages, against the spring bias. The one way discharge valve is
securely retained in the closed position by the large differential pressure
between
the discharge and the pump chamber. Thus liquid flows from about the annular
inlet port 198, through the inlet ports 192, physically displacing the annular
ring-
plate 194 axially to fill the piston chamber 108.
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[0112] As shown in Fig. 11B, on the liquid discharge stroke, the piston
end
110 is craven towards the cylinder head 112 for generate a high pressure in
the
pump chamber 108. The annular ring-plate 194 is biased closed against the
cylinder head 112 to avoid any backflow and pressure differential ensures it
stays
closed against the circumferentially spaced inlet ports 192. The plunger 200
of the
one way discharge valve 114 is forced open, off of valve seat 204, against the
small
biasing of the coil spring 202 and liquid flows around the valve plunger 200
and out
the discharge ports 208 of the discharge cover. The liquid flows through the
bore of
the discharge valve retainer 210 and out the pump outlet 115.
[0113] The cylinder sleeve 102 is provided with cooling circulation. Fig.
13 is
a transverse cross-section of the cylinder housing 104 and plunger 106 to
illustrate
an externally-splined internal cylinder sleeve 102. The cylinder sleeve 102
firstly
provides a piston barrel or complementary cylindrical surface 240 for
receiving the
piston end 110. The piston end 110 is sealably and slidable thereon. Secondly,
the
cylinder sleeve has an external surface 242, upon which is formed one or more
axially-extending splines 244 forming passages 246 therebetween. The sleeve
102
is fluid cooled by the flow of liquid through the passages 246 and therealong.
[0114] As shown in Figs. 8B, 9B, 13 and 14 a first annular cooling
passage
248 is located circumferentially about the cylinder sleeve 102 and about the
piston
end adjacent the cylinder head 112. The axial passages 246 are fluidly
connected
to the annular cooling passage 248 end and extend axially back toward shoulder
222. As also shown in Fig. 8B, a circulation port 250 is provided at the
shoulder
222, for fluid communication with a second annular cooling passage 252 and
axial
28
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passages 246. The circulation port 250 fluidly connected at the distal end of
the
cylinder sleeve 102. The second annular cooling passage 252 is fit with radial
cross
ports 254 through the sleeve 102 and in fluid communication with a backside
chamber 256 of the piston end 110. Fig. 14 illustrates the cross-flow ports
254 at
the distal end of the internal cylinder sleeve 102.
[0115] Fig. 15A and 15B are perspective ends view of the drive end of the
pump head 100 and illustrating the tail or connection end 126 of the plunger
106
and plunger clamp 132. In Fig. 15A, the clamp 132 is illustrate split apart
for
disconnecting the plunger 106 from the pony rod 260 (See Fig. 16A), and in
Fig.
15B is shown assembled for connecting the components drivably together.
[0116] Turning to Figs. 16A and 16B, cross-sectional views of the plunger
106 and pony rod 260 connection of Fig. 15A illustrate field adjustment of the
plunger's axial position, to adjust the top dead center (TDC) to the plunger's
piston
end 110 closer and further from the cylinder head 112. The stroke and axial
position of the pony rod 260 is set by the motor, gear box, crank and
connecting rod
position on a pumper. Once installed in the field, the TDC can be adjusted.
[0117] In Fig. 16A, one or more ring shims 261 are added to the end of
the
pony rod 260 to space the plunger's tail end 126 a distance h further from the
pony
rod 260, in turn locating in the piston end 110 closer to the cylinder head
112. Ring
shims 261 can be removed to draw the plunger closer to the pony rod 260, in
turn
spacing the piston end 110 a clearance c further from the cylinder head 112.
[0118] The tail end and the pony rod are fit with beveled ends 262,264
respectively, the bevelled ends being complementary with internal annular
beveled
29
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surfaces 272,274 of the clamp 132. The end of the pony rod is fit with an
insert 280
having the bevelled end 264 formed thereon. The insert 280 has a shaft portion
282 and a larger upset end 284 bearing the beveled end 264. The ring shims 261
are located about the shaft portion 282 and axially between the upset end 284
and
the pony rod. The insert 280 is secured to the pony rod 260 with a cap screw
288
or other suitable fastener.
[0119] A
face 300 of the insert 280 of the pony rod 206 engages a 302 face
the tail end 126 of the plunger 106. Thus, the relative axial position of the
piston
end 110 and pony rod 206 are set. Removing one or more ring shims 261 causes
the plunger 106 to be secured by the clamp 132 closer to the drive end, with
the
piston end 110 further from the cylinder head 112. Thus, onsite maintenance
and
adjustments can be performed by adding and removal of shims to adjust the
plunger's piston end 110 closer and further from the cylinder had and valve
assembly 130.
