Patent Publication Number: US-2013233165-A1

Title: Monitoring system for reciprocating pumps

Description:
RELATED APPLICATIONS 
     This nonprovisional patent application claims the benefit of co-pending, provisional patent application U.S. Ser. No. 60/465,043, filed on Apr. 24, 2003, which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     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 
     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 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. 
     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. 
     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 
     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. 
     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. 
     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 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. 
     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. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic elevational view of a reciprocating pump assembly constructed in accordance with this invention. 
         FIG. 2  is a top plan schematic view of the reciprocating pump assembly shown in  FIG. 1 . 
         FIG. 3  is a sectional view of a portion of the pump assembly shown in  FIG. 1 . 
         FIG. 4  is a perspective view of the reciprocating pump assembly shown in  FIG. 1 . 
         FIG. 5  is an enlarged sectional view of a monitoring sensor assembly shown in a cover plate of the reciprocating pump assembly shown in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIGS. 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  FIGS. 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  ( FIG. 2 ). As best shown in  FIG. 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  FIG. 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. 
     Referring to  FIG. 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  FIG. 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  ( FIG. 3 ) extending to cylinder  17 . As shown in  FIG. 2 , each piston throw  23  extends in the same longitudinal direction from crankshaft housing  13 . 
     Referring to  FIG. 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 . 
     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 . 
     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 . 
     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  ( FIG. 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 from 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. 
     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  FIG. 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  FIG. 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. 
     As best illustrated in  FIGS. 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  FIG. 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 . 
     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  FIG. 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. 
     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 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 . 
     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 . 
       FIG. 5  shows an example of the preferred embodiment of the pressure sensor assembly  45 . In the example shown in  FIG. 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 . 
     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  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 . 
     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  ( FIGS. 1-4 ) communicate sensed pressure values electronically to the memory of computer  58 . 
     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 . 
     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 reciprocating pump  12  during long periods of operation rather than only during short test runs. 
     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.