Note: Descriptions are shown in the official language in which they were submitted.
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CA 02486126 2011-11-17
MONITORING SYSTEM FOR RECIPROCATING PUMPS
BACKGROUND OF THE INVENTION
1. Field of the Invention
[00021 The present invention relates generally to reciprocating pumps,
more
specifically to an apparatus for monitoring operating conditions of the
reciprocating
pump.
2. Background of the Invention
100031 In oil field operations, reciprocating pumps are often used for
various
purposes. Some reciprocating pumps, generally known as "service pumps," are
typically used for operations such as cementing, acidizing, or fracing the
well.
Typically, these service pumps run for relatively short periods of time but on
a
frequent basis. Often they are mounted to a truck or a skid for transport to
various
well sites. A pump might operate several times a week. Many times, several
pumps
will be connected in parallel to a flow line. The operator will know the
output
pressure of the group of pumps due to a pressure gauge on the flow line, but
may
not know the individual pump output pressure. The operator will often not know
the intake pressure, the individual pump speed, or the extent of vibration of
a
particular pump. A pump might be performing poorly, yet the operator not know.
[00041 To periodically monitor the performance of the pump, an operator
typically calls on the services of testing companies that will set up
temporary
sensors and monitor the performance of the pump during a test period.
Generally,
the testing service connects pressure gauges to the overall intake and
discharge, as
well as each individual pressure chamber. The testing service might also
monitor
the rotational speed and vibration. Then the testing service removes the test
equipment and the pump continues operations without monitoring equipment.
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[00051 Continuous monitoring of the pump through testing companies is not
practical.
Moreover, during operations, the pressure of the fluid inside of the pump can
become
quite high which makes it difficult to obtain readings of pressures within the
pump at
certain locations without leakage. Operators typically will not often use the
testing
equipment due to the cost associated with the testing companies. An operator
may
not have a pump tested unless something appears to be wrong with it.
Accordingly,
operators are often left in the situation of not knowing what the performance
conditions of a pump for long periods of time.
SUMMARY OF THE INVENTION
100061 In this invention, a reciprocating pump assembly includes a pump
housing that
houses a crankshaft. A plurality of pistons are mechanically connected to the
crankshaft for pumping a fluid through a plurality of cylinders or piston
chambers.
Each of the cylinders has a fluid inlet and a fluid outlet. The pump also has
a
monitoring housing connected to the reciprocating pump. Within the monitoring
housing is a computer having a memory. The pump also has a plurality of
pressure
sensor assemblies. Each pressure sensor assembly is in electrical
communication with
the memory. Each pressure sensor assembly is used to sense a pressure value of
a
fluid within the pump.
100071 The invention can optionally also include an accelerometer to measure
vibrations by sensing displacement. The accelerometer is typically positioned
adjacent the pump housing. The accelerometer is also in electrical
communication
with the memory of the computer so that the computer can store sensed
vibrations or
displacements during operations. The invention can also have a proximity
sensor
located within the pump housing to determine the rotational velocity of the
crankshaft. The proximity sensor is in electrical communication with the
memory of
the computer so that the computer can store sensed proximity values during
operations.
100081 A pressure sensor assembly that can be used in this invention includes
a plug
member. The plug member is positioned adjacent a sidewall of the pump. The
sidewall can be selected from various sidewalls that are in fluid
communication with
the fluid pumped within the reciprocating pump. A port is located in the
sidewall of
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the pump that is in fluid communication with the fluid within the pump. The
plug
member has an aperture that registers with the port when the plug member is
positioned adjacent the side wall. A seal member is positioned between the
plug
member and the sidewall. The seal member has a passageway that allows the
aperture to register with the port when the seal member and the plug member
are
in place. A transducer is located within the plug member and is in fluid
communication with the aperture. The transducer converts the pressure into
electronic signals that can be communicated to the computer.
[0009] The computer of the pump assembly can also have a port that allows
an operator to download the stored sensed values in the memory. This allows an
operator to collect the sensed values of the operating conditions over long
periods
of operation for analysis and monitoring purposes. Alternatively, the memory
of the
computer can be a replaceable memory device such as a chip or disk. The
computer
can include a drive for receiving and ejecting the memory so that the operator
can
easily retrieve and replace the memory after predetermined periods of
operations for
analysis.
10009A1 The invention in one broad aspect pertains to an oilfield
reciprocating
pump assembly having a pump housing that houses a crankshaft with a plurality
of
pistons mechanically connected to the crankshaft for pumping a fluid into a
plurality
of cylinder chambers, each of the cylinder chambers having a fluid inlet with
an
inlet valve and a fluid outlet with an outlet valve. A fluid inlet chamber is
upstream
of the inlet valve of each of the cylinder chambers, and a discharge flange is
downstream of the outlet valve of each of the fluid outlets for receiving
fluid from
the plurality of cylinder chambers. The reciprocating pump comprises a
monitoring
housing mounted to the reciprocating pump assembly, and a computer is in
electrical
communication with the monitoring housing, the computer having a memory. A
plurality of cylinder chamber pressure sensor assemblies, each mounted to the
pump
in fluid communication with one of the cylinder chambers is provided to sense
a
presure value of the fluid within each of the cylinder chambers of the pump.
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[0009131 In a still
further aspect, the invention comprehends a method of
monitoring the operating conditions of an oilfield reciprocating pump assembly
having a pump housing that houses a crankshaft. A plurality of pistons are
mechanically connected to the crankshaft for pumping a fluid through a
plurality of
cylinder chambers, each of the cylinder chambers having a fluid inlet with an
inlet
valve and a fluid outlet with an outlet valve. A fluid inlet chamber is
upstream of
the inlet valve of each of the cylinder chambers, and a discharge flange is
downstream of the outlet valve of each of the fluid outlets for receiving
fluid from
the plurality of cylinder chambers. The method comprises mounting a monitoring
housing to the reciprocating pump assembly, positioning a plurality of
cylinder
pressure sensor assemblies in fluid communication with ports leading to each
of the
cylinder chambers and electrically connecting the sensor assemblies to the
computer
of the reciprocating pump, and positioning an intake pressure sensor assembly
in
fluid communication with the fluid inlet chamber and a discharge pressure
sensor
assembly in fluid communication with the discharge flange. A wire harness is
connected between the cylinder pressure, intake pressure and discharge
pressure
sensor assemblies and the monitoring housing. The pump operates to cause a
dynamic fluid pressure within each of the cylinder chambers to increase when
its
piston makes a pressure stroke and to decrease when its piston makes a suction
stroke. The dynamic fluid pressure is sensed within each of the cylinder
chambers
with the cylinder pressure sensor assemblies, and intake and discharge
pressures are
sensed with the intake and discharge pressure sensor assemblies. Sensed values
of
the dynamic fluid pressure, the intake pressure and the discharge pressure
from the
sensor assemblies are electrically communicated to the monitoring housing via
the
wire harness, and the sensed values from the monitoring housing are
electrically
communicated to a computer to determine a condition of the valves.
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BRIEF DESCRIPTION OF THE DRAWINGS
100101 Figure 1 is a schematic elevational view of a reciprocating pump
assembly constructed in accordance with this invention.
[0011] Figure 2 is a top plan schematic view of the reciprocating pump
assembly shown in Figure 1.
[0012] Figure 3 is a sectional view of a portion of the pump assembly
shown
in Figure 1.
10013] Figure 4 is a perspective view of the reciprocating pump assembly
shown in Figure 1.
[0014] Figure 5 is an enlarged sectional view of a monitoring sensor
assembly shown in a cover plate of the reciprocating pump assembly shown in
Figure 1.
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0015] Referring to Figures 1 and 3, reciprocating pump or pump assembly 12
includes a monitoring assembly 11 is shown attached to a reciprocating pump
12. In
the preferred embodiment, reciprocating pump 12 includes a crankshaft housing
13
that comprises a majority of the outer surface of reciprocating pump 12 shown
in
Figures 1 and 3. A plunger or piston rod housing 15 attaches to a side of
crankshaft
housing 13 and extends to a cylinder 17. Each cylinder 17 preferably includes
a fluid
inlet 19 and a fluid outlet 21 (Figure 2). As best shown in Figure 3, a cover
plate 22
connects to an end of each cylinder 17 opposite from the piston rod housing
15.
While pump 12 is shown in Figure 4 as free-standing on the ground, pump 12 can
easily be mounted to a trailer that can be towed between operational sites, or
to a skid
such as for offshore operations. Accordingly a pump assembly is defined as
including
either a pump 12 mounted directly to the ground or support structure, a skid,
or a
trailer.
[0016] Referring to Figure 2, piston rod housing 15 is segmented into three
portions,
each portion comprising a plunger or piston throw 23. Reciprocating pump 12 as
shown in Figure 2 has three piston throws 23, which is commonly know as a
triplex,
but could also be segmented for five piston throws 23, which is commonly known
as a
quintuplex pump. The description focuses on a triplex pump, but as will be
readily
apparent to those skilled in the art, the features and aspects described are
easily
applicable for a quintuplex or other type of pump. Each piston throw 23 houses
a
piston rod 33 (Figure 3) extending to cylinder 17. As shown in Figure 2, each
piston
throw 23 extends in the same longitudinal direction from crankshaft housing
13.
100171 Referring to Figure 3, a portion of reciprocating pump 12 housed within
crankshaft housing 13 is shown. Crankshaft housing 13 houses a crankshaft 25,
which is typically mechanically connected to a motor (not shown). The motor
(not
shown) rotates crankshaft 25 in order to drive reciprocating pump 12. In the
preferred
embodiment, crankshaft 25 is cammed so that fluid is pumped from each piston
throw
23 at alternating times. As is readily appreciable by those skilled in the
art,
alternating the cycles of pumping fluid from each of cylinders 17 helps
minimize the
primary, secondary, and tertiary (et al.) forces associated with reciprocating
pump 12.
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100181 In the preferred embodiment, a gear 24 is mechanically connected to
crankshaft 25. Gear 24 can be for mechanically connecting crankshaft 25 to the
motor (not shown), or for conveying rotational energy to another gear for
driving
another assembly, such as a lubrication pump for lubricating. Gear 24
typically has
teeth 26 spaced around the circumference of gear 24. In the preferred
embodiment, a
proximity sensor 28 is positioned adjacent crankshaft 25 for calculating the
rotational
velocity of crankshaft 25. One manner proximity sensor 28 can help calculate
rotational velocity is by counting teeth 26 as gear 24 rotates. For example,
one type
of proximity sensor creates a magnetic field within its close proximity. As
the each
tooth 26 rotates past the proximity sensor 28, there is a disruption in the
magnetic
field. These disruptions can be counted and compared to time to help calculate
a
rotational speed of the gear 24, which in turn can be used to calculate the
rotational
speed of crankshaft 25.
100191 In the preferred embodiment, a connector rod 27 includes an end that
connects
to crankshaft 25 and another end that engages a crosshead 29. Connector rod 27
connects to crosshead 29 through a crosshead pin 31, which holds connector rod
27
longitudinally relative to crosshead 29. Connector rod 27 pivots about
crosshead pin
31 as crankshaft 25 rotates with the other end of connector rod 27. A piston
rod 33
extends from crosshead 29 in a longitudinally opposite direction from
crankshaft 25.
Connector rod 27 and crosshead 29 convert rotational movement of crankshaft 25
into
longitudinal movement of piston rod 33.
100201 A piston 35 connects to piston rod 33 for pumping the fluid passing
through
reciprocating pump 12. Cylinder 17 connects to the end of piston rod housing
15
extending away from crankshaft housing 13 (Figure 1). Cylinder 17 typically
includes a cylinder chamber 39, which is where the fluid being pumped by
reciprocating pump 12 is compressed by piston 35. Cylinder 17 preferably
includes
an inlet valve 41 and an outlet valve 43. Valves 41 and 43 are preferably
spring-
loaded valves, which are actuated by a predetermined differential pressure.
Inlet
valve 41 actuates to control fluid flow through fluid inlet 19 into cylinder
chamber 39,
and outlet valve 43 actuates to control fluid flow through fluid outlet 21
from cylinder
chamber 39. Piston 35 reciprocates, or moves longitudinally toward and away
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cylinder 17, as crankshaft 25 rotates. As piston 35 moves longitudinally away
from
cylinder chamber 39, the pressure of the fluid inside chamber 39 decreases
creating a
differential pressure across inlet valve 41, which actuates valve 41 and
allows the
fluid to enter cylinder chamber 39 from fluid inlet 19. The fluid being pumped
enters
cylinder chamber 39 as piston 35 continues to move longitudinally away from
cylinder 17 until the pressure difference between the fluid inside chamber 39
and the
fluid in fluid inlet 19 is small enough for inlet valve 41 to actuate to its
closed
position. As piston 35 begins to move longitudinally towards cylinder 17, the
pressure on the fluid inside of cylinder chamber 39 begins to increase. Fluid
pressure
inside cylinder chamber 39 continues to increase as piston 35 approaches
cylinder 17
until the differential pressure across outlet valve 43 is large enough to
actuate valve
43 and allow the fluid to exit cylinder 17 through fluid outlet 21. In the
preferred
embodiment, fluid is only pumped across one side of piston 35, therefore
reciprocating pump 12 is a single-acting reciprocating pump. If fluid were
also being
pumped on the side of piston 35 that connects to piston rod 33, this would be
a double
acting pump.
100211 In the preferred embodiment, a pressure sensor assembly monitors the
pressure of fluid being pumped by reciprocating pump 12. Preferably there are
a
plurality of pressure sensor assemblies advantageously positioned adjacent
various
sidewalls of pump 12 to sense fluid pressure values at various locations
throughout
pump 12. For example, as best shown in Figure 4, there is a pressure sensor
assembly
45 mounted to each cover plate 22, which allows for sensing the output fluid
pressure
individually within each cylinder 17. In the embodiment shown in Figure 4,
there is
also preferably a pressure sensor assembly 46 mounted to fluid inlet 19, which
feeds
into each of cylinders 17, to sense the overall suction fluid pressure of the
fluid
entering pump 12. Additionally, there is also preferably a pressure sensor
assembly
47 mounted to each discharge flange or well fluid outlet 21 to sense the
individual
fluid pressure of the fluid exiting each cylinder 17. In the preferred
embodiment,
wires 49 are in electrical communication with pressure sensors 45, 46, and 47.
In the
preferred embodiment, each pressure sensor assembly 45 includes a plurality of
wires
49 extending therefrom. A preferred structure of each pressure sensor assembly
is
provided in more detail below.
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[0022] As best illustrated in Figures 2-4, wires 49 extending from each
pressure
sensor assembly 45 combine to form a single bundle or wire harness 51. Wire
harness
51 preferably extends below cylinders 17 toward crankshaft housing 13.
Referring
back to Figure 2, the end of wire harness 51 extending toward crankshaft
housing 13
connects to a wire harness disconnect 53 located on crankshaft housing 13.
Wire
harness disconnect 53 preferably allows an operator to selectively disengage
wire
harness 51 while replacing or repairing cylinders 17. A second bundle or wire
harness 55 extends from wire harness disconnect 53 toward an upper portion of
crankshaft housing 13.
[0023] In the preferred embodiment, a monitoring housing or data collector 57
is
located on an upper portion of crankshaft housing 13. Data collector 57
preferably
comprises a computer 58 (Fig. 1) that receives and stores data about the
operating
conditions of pump 12. In a manner known in the art, computer 58 includes
memory.
As shown in Figure 4, computer 58 can include a port 60 for downloading data
from
the memory to another computer. Additionally, computer 58 can optionally
include
portable memory that is removable and insertable through a drive 62. Such
replaceable memory 'allows an operator to store operating conditions on the
memory
of computer 58 for a predetermined length of time, and then retrieve the
memory with
the stored data for analysis and replace the previous memory with a
replacement
memory for storing data for another predetermined length of time.
[0024] The end of wire harness 55 extending from wire harness disconnect 53
connects to data collector 57. Data collector 57 receives and records the
inlet and
outlet pressures for each of cylinders 17 associated with reciprocating pump
12 as
pistons 35 stroke. As will be appreciated by those skilled in the art, the
inlet and
outlet pressures from each cylinder 17 can then be transmitted from data
collector 57
to a centrally located facility or the measurements can be digitally stored
until
retrieved by an operator. Additionally, proximity sensor 28 (Fig. 3) is also
preferably
in electrical communication with the memory of computer 58 so that proximity
sensor
can transmit the sensed proximities of teeth 26 for storage in the memory of
computer
58. Computer 58 computes speed of rotation based on the rate that proximity
sensor
28 senses teeth 26. In the preferred embodiment, data collector 57 includes
memory
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CA 02486126 2004-10-28
that receives and stores the information. Monitoring inlet and outlet
pressures within
cylinder chambers 39 allows operators to monitor the efficiency of
reciprocating
pump 12 as well as the differential pressures associated with inlet and outlet
valves
41, 43. By monitoring inlet and outlet pressures within cylinder chamber 39,
operators can more effectively determine the appropriate time for replacing
inlet and
outlet valves 41, 43.
[0025] Accelerometer 59 is supported on pump housing 13 and monitors the
vibrations of reciprocating pump 12 as crankshaft 25 drives each piston 35
with piston
rods 33. Typically, accelerometer 59 transmits various voltages responsive to
vibrations to data collector 57 for computer 58 to calculate vibrations.
Monitoring
vibrations associated with reciprocating pump 12 allows operators to detect
any
abnormal operating conditions of reciprocating pump 12. In the
preferred
embodiment, the chip (not shown) in data collector 57 also receives and stores
the
information from accelerometer 59. In the preferred embodiment, monitoring
assembly 11 includes the combined assembly of data collector 57, accelerometer
59,
proximity sensor 28, wires and wire harnesses 49, 51, 55, wire harness
disconnect 53,
and pressure sensor assemblies 45, 46 and 47.
[0026] Figure 5 shows an example of the preferred embodiment of the pressure
sensor
assembly 45. In the example shown in Figure 5, pressure sensor assembly 45 is
connected to one of cover plates 22 to sense discharge pressure. As will be
readily
appreciated by those skilled in the art, this arrangement is easily suitable
for the
positioning of pressure sensor assemblies 45, 46, 47 on the other various
selected
sidewalls of pump 12, like at pump inlet and outlets 19, 21.
100271 Pressure sensor assembly 45 is positioned on the outer surface of cover
plate
22. A port 71 extends from an interior surface of cover plate 22 toward the
outer
surface of cover plate 22. Port 71 is in fluid communication with the fluid
pumped by
one of the pistons 35. A plug member 73 preferably extends into a portion of
cover
plate 22. An aperture 75 extending through a portion of plug member 73
registers
with port 71. In the preferred embodiment, a thread 77 formed on a portion of
the
outer circumference of plug member 73 that engages a counter-bored thread 79
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formed in cover plate 22 for securing plug member 73 to cover plate 22. The
counter-
bore portion of port 71 defines an outward facing shoulder 80.
100281 A metal seal member 81 is sealingly positioned and compressed between
an
end of plug member 73 and shoulder 80. A passageway 83 extends longitudinally
through seal member 81 so that aperture 75 can register with port 71. In the
preferred
embodiment, seal member 81 has a pair of frusto-conical surfaces 85 formed at
each
longitudinal end for engaging plug member 73 and shoulder 80. The pair of
frusto-
conical ends 85 form a metal to metal seal with seal member 81 between plug
member 73 and shoulder 80 when plug member is installed. A transducer 87 is
located within plug member in fluid communication with aperture 75. A set of
electrical prongs 89 extend from transducer 87 for connection to a plug on
each wire
49. Wires 49 (Figures 1-4) communicate sensed pressure values electronically
to the
memory of computer 58.
100291 In operation, pressure assemblies 45, 46, 47 are fixedly positioned
adjacent
various selected sidewalls of pump 12. Seal member 81 of each pressure sensor
assembly 45 provides a seal against leakage of the fluid pumped by pump 12
from
exiting through pressure sensor assemblies 45. Wires 49 are connected to
pressure
sensor assemblies 45 so that wires 49 are in electrical communication with
prongs 89
extending from each transducer 87. During operation of pump 12, the fluid
communicates with transducer 87 through port 71, passageway 83, and aperture
75.
Transducer converts the sensed pressure to an electrical signal and
communicates the
signal to the memory in computer 58 via wires 49. In the preferred embodiment,
accelerometer 59 and proximity sensor 28 are also communicating their sensed
displacement and proximity readings to the memory in computer 58.
100301 Computer 58 stores the sensed values from pressure sensor assemblies
45, 46,
47, accelerometer 59, and proximity sensor 28 in the computer memory. The
operator
can download the sensed values from the memory via a port 60. In the preferred
embodiment, the operator can alternatively remove the memory with the stored
values
from computer 58 via drive 62, and insert a replacement memory for receiving
and
storing continued sensed operating conditions. This allows continuous
monitoring of
sensed pressure values of fluid at various positions, and at high pressures
within
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reciprocating pump 12 during long periods of operation rather than only during
short
test runs.
[00311 While the invention has been shown in only some of its forms, it should
be
apparent to those skilled in the art that it is not so limited, but is
susceptible to various
changes without departing from the scope of the invention. For example, wires
49
can extend through various sides or ends of cylinders 17 to connect with
pressure
transducers 45, 46, 47. Furthermore, in situations where the pump assembly is
mounted to a skid or a trailer, it will be readily appreciated by those
skilled in the art
that equipment that is mounted to a pump or crankshaft housing (e.g. data
collector
57) can easily be mounted to the skid or trailer instead of the crankshaft
housing with
a minimal changes and a little extra length of wiring. As a further example,
while all
the figures illustrate service pumps that are typically used for cementing,
acidizing, or
fracing, the monitoring assembly 11 could also easily be used on mud pumps for
drilling operations.
