Reciprocating pump system and method for operating same

• US 5,846,056 A
• Filed: 04/07/1995
• Issued: 12/08/1998
• Est. Priority Date: 04/07/1995
• Status: Expired due to Fees

• Current Assignee: National Oilwell Varco LP (NOV, Inc.)
• Original Assignee: Jasbir S. Dhindsa, Leroy M. Rambin Jr
• Inventors: Dhindsa, Jasbir S., Rambin, Leroy M. Jr.
• Primary Examiner(s): Thorpe, Timothy
• Assistant Examiner(s): THAI, XUAN MARIAN
• Application Number:
  US08/418,761
• Time in Patent Office: 1,341 Days
• Field of Search: 417/1-6, 417/12, 417/32, 417/45, 417/44.2, 417/53, 417/205, 417/208, 417/286, 417/292, 417/904, 417/269, 417/270, 417/271, 417/44.3, 91/472, 91/473, 92/12.2, 73/152.22, 73/152.51, 73/152.52
• US Class Current: 417/44.2
• CPC Class Codes: F04B 2201/0205 Piston ring wear
• CPC Class Codes: F04B 2201/0802 Vibration
• CPC Class Codes: F04B 2201/1207 Wear of the bearings
• CPC Class Codes: F04B 2203/0409 Linear speed
• CPC Class Codes: F04B 2205/03 Pressure in the compression chamber
• CPC Class Codes: F04B 2205/10 Inlet temperature
• CPC Class Codes: F04B 2207/0421 maximum
• CPC Class Codes: F04B 2207/701 Sound
• CPC Class Codes: F04B 23/06 the pumps being all of reciprocating positive-displacement type
• CPC Class Codes: F04B 47/02 the driving mechanisms being situated at ground level F04B47/12 takes precedence
• CPC Class Codes: F04B 49/065 and making use of computers

Abstract

This invention provides a reciprocating pump system having means for determining the cylinder head pressure of at least one cylinder of each pump in the system. A control circuit continually determines the average cylinder head pressure, estimates the pump bearing life that has been consumed and the remaining pump bearing life from the pressure head information. The control circuit also controls the operation of the pumps as a function of cylinder head pressure. A temperature sensor coupled to the pump system provides temperature of the pump oil. The control circuit controls the operation of the pump as function of the pump oil temperature. The pump speed is decrease when the pump oil temperature exceeds a predetermined value. A vibration sensor coupled to the pump provides vibration level to the control circuit, which controls the pump operation in response thereto.

Claims

1. A reciprocating pump, comprising:

(a) a pump cylinder for receiving a fluid at an inlet at a suction pressure and discharging the fluid at an outlet at a discharge pressure;

(b) a pressure sensor coupled to the pump cylinder for providing signals representative of pressure in the cylinder; and

(c) a circuit coupled to the pressure sensor, said circuit receiving signals from the pressure sensor and utilizing such received signals to determine at least one operating parameter of the reciprocating pump selected from a group of parameters consisting (i) cavitation in the reciprocating pump, (ii) average pump cylinder pressure, (iii) the discharge pressure, (iv) the suction pressure, (v) pump operating cycle, (vi) pump speed, (vii) pump operating time, (vii) an estimate relating to consumed life of the reciprocating pump, (viii) an estimate relating to the remaining operating life of the reciprocating pump, and (ix) volumetric output of the reciprocating pump.

2. A reciprocating pump, comprising:

(a) a pump cylinder for receiving a fluid at an inlet at a suction pressure and discharging the fluid at an outlet at a discharge pressure;

(b) a piston in the pump cylinder, said piston adapted to move between a first and a second position, the movement of the piston from the first position to the second position defining a suction cycle and the movement from the second position to the first position defining a discharge cycle and a combination of a suction cycle and a discharge cycle defining a piston stroke;

(c) a pressure sensor coupled to the pump cylinder for providing signals representative of pressure in the chamber during the piston stroke; and

(d) a circuit coupled to the pressure sensor for receiving signals from the pressure sensor, said circuit determining a pressure response curve from the received signals and determining therefrom an operating parameter of the reciprocating pump selected from a group of parameters consisting (i) cavitation in the reciprocating pump, (ii) average pump cylinder pressure, (iii) the discharge pressure, (iv) the suction pressure, (v) pump operating cycle, (vi) pump speed, (vii) pump operating time, (vii) an estimate relating to consumed life of the reciprocating pump, (viii) an estimate relating to remaining operating life of the reciprocating pump, (ix) volumetric output of the reciprocating pump, and (x) number of piston strokes over a predetermined time period.

3. The reciprocating pump according to claim 2, wherein the circuit further determines from the pressure response curve a mean discharge pressure in the pump cylinder.

4. The reciprocating pump according to claim 3, wherein the piston is operated by a motor and the circuit causes the motor to reduce speed of the pump when the mean discharge pressure reaches a predetermined upper limit.

5. The reciprocating pump according to claim 2, wherein the circuit further determines a peak pressure value of the discharge pressure during each stroke and causes the motor to reduce speed of the pump if such peak pressure reaches a predetermined value.

6. The reciprocating pump according to claim 2, wherein the circuit determines a pressure response curve from the pressure signals and compares such response curve with a predetermined pressure response curve to determine whether a cavitation condition is present in the pump.

7. The reciprocating pump according to claim 2, wherein the reciprocating pump contains a bearing whose operating life is a function of the number of the piston strokes and wherein the circuit provides an estimate of the operating life of the bearing that has been consumed.

8. The apparatus according to claim 2, wherein the circuit contains a microprocessor and a silicon control rectifier based circuit for controlling speed of the reciprocating pump.

9. The reciprocating pump according to claim 2, wherein the piston moves in a piston cylinder having a replaceable liner and the circuit determines from the pressure response curve an expected remaining life of the liner.

10. The reciprocating pump according to claim 2, wherein the pump cylinder comprises:

(i) a cylinder head; and

(ii) a plug disposed In the cylinder head.

11. The reciprocating pump according to claim 10, wherein the pressure sensor is disposed in the plug.

12. The reciprocating pump according to claim 2, wherein the pressure sensor is coupled to the piston.

13. A reciprocating pump having a plurality of chambers, wherein each said chamber has an associated piston chamber in fluid communication with the chamber and wherein each said piston strokes within its associated chamber to cause the its associated chamber to receive a fluid from a source at a suction pressure and discharge the received fluid at a common outlet at a discharge pressure, said pump comprising:

(a) a pressure sensor coupled to a single chamber in said plurality of chambers for providing signals representative of pressure in such chamber; and

(b) a circuit coupled to the pressure sensor, said circuit determining response of the pressure in the chamber to which said pressure sensor is coupled, said circuit determining from the response of said sensor in said single chamber at least one operating parameter of the reciprocating pump selected from a group consisting (i) cavitation in the reciprocating pump, (ii) average pump cylinder pressure, (iii) the discharge pressure, (iv) the suction pressure, (v) pump operating cycle, (vi) pump speed, (vii) pump operating time, (vii) an estimate relating to consumed life of the reciprocating, (viii) an estimate relating to the remaining operating life of the reciprocating pump, and (ix) volumetric output of the reciprocating pump, and (x) number of piston strokes over a predetermined time period.

14. A method of operating a reciprocating pump having a pump cylinder for receiving a fluid at a suction pressure and for discharging the fluid at a discharge pressure, said reciprocating pump having a piston reciprocating within a piston cylinder which is in fluid communication with the pump cylinder, each reciprocating cycle of the piston defining a pump stroke, said method comprising:

(a) providing a pressure sensor in the chamber for determining pressure in the chamber during operation of the reciprocating pump;

(b) operating the pump at a predetermined speed;

(c) determining from the pressure sensor response a pressure response curve of the reciprocating pump when the pump is operating, said pressure response curve having characteristics that include a leading edge, a discharge pressure region, a trailing edge, and a suction pressure; and

(b) determining at least one operating parameter of the reciprocating pump by utilizing at least one of the characteristics of the pressure in the pump cylinder.

15. The method according to claim 14, wherein the at least one operating parameter of the pump includes number of piston strokes over a predetermined time period.

16. The method as described in claim 15, wherein the at least one parameter includes life of a piston liner in the reciprocating pump.

17. The method as described in claim 14, wherein the at least one parameter includes life of a pump bearing in the reciprocating pump.

18. The method of operating a reciprocating pump according to claim 14 further comprising:

(a) determining vibration level of the pump at a suitable place on the pump; and

(b) reducing speed of the prime mover and thereby reducing the pump speed when the vibration level reaches a predetermined upper limit.

19. A pump system for use in pumping a fluid into a wellbore, comprising:

(a) a plurality of reciprocating pumps, each said pump in said plurality of pumps having a plurality of chambers, wherein each said chamber having an associated piston chamber in fluid communication therewith and wherein each said piston stroking within its associated piston chamber for causing its associated chamber to receive a fluid from a source at a suction pressure and discharging the received fluid at common outlet at a discharge pressure;

(b) a pressure sensor coupled to at least one chamber of each said pump in said plurality of pumps, each said pressure sensor providing signals representative of pressure in the chamber to which such pressure sensor is coupled; and

(c) a circuit coupled to each of the pressure sensors, said circuit determining the pressure in each of the chambers to which a pressure sensor is coupled, said circuit providing information about at least one operating parameter of each of the pumps in said plurality of pumps that is selected from a group of parameters consisting of (i) cavitation in the reciprocating pump, (ii) average pump cylinder pressure, (iii) the discharge pressure, (iv) the suction pressure, (v) pump operating cycle, (vi) pump speed, (vii) pump operating time, (vii) an estimate relating to consumed life of the reciprocating pump, (viii) an estimate relating to the remaining operating life of the reciprocating pump, and (ix) volumetric output of the reciprocating pump.

20. A reciprocating pump, comprising:

(a) a pump cylinder for receiving a fluid at an inlet at a suction pressure and discharging the received fluid at an outlet at a discharge pressure;

(b) a piston in the pump cylinder, said piston adapted to move between a first and a second position, the movement of the piston from the first position to the second position defining a suction cycle and from second position to the first position defining a discharge cycle and a combination of a suction cycle and a discharge cycle defining a piston stroke;

(c) a pressure sensor coupled to the chamber for providing signals representative of pressure in the chamber during the piston stroke; and

(d) a circuit coupled to the pressure sensor for receiving signals from the pressure sensor, said circuit determining from the received signals a pressure response curve for the reciprocating pump corresponding to the piston stroke and analyzing said pressure response curve to determine an operating parameter of the reciprocating pump.

21. The reciprocating pump according to claim 20, wherein the operating parameter is selected from a group of parameters consisting (i) cavitation in the reciprocating pump, (ii) average pump cylinder pressure, (iii) the discharge pressure, (iv) the suction pressure, (v) pump operating cycle, (vi) pump speed, (vii) pump operating time, (vii) an estimate relating to consumed life of the reciprocating pump, (viii) an estimate relating to the remaining operating life of the reciprocating pump, end (ix) volumetric output of the reciprocating pump, and (x) number of piston strokes over a predetermined time period.

22. The reciprocating pump according to claim 20, wherein the pressure response curve includes characteristics selected from a group consisting a leading edge rising from a suction pressure to a discharge pressure, a region of discharge pressure, a trailing edge dropping from the discharge pressure to the suction pressure and a suction pressure region.

23. The reciprocating pump according to claim 22, wherein the operating parameter is the discharge pressure and wherein the circuit determines the discharge pressure from the discharge pressure region of the pressure response curve.

24. The reciprocating pump according to claim 22, wherein the operating parameter is the suction pressure and wherein the circuit determines the suction pressure from the suction pressure region of the pressure response curve.

25. The reciprocating pump according to claim 22, wherein the operating parameter is average pump cylinder pressure and wherein the circuit determines the average pump cylinder pressure from the suction pressure region and the discharge pressure region of the pressure response curve.

26. The reciprocating pump according to claim 22, wherein (i) the operating parameter Is cavitation in the pump cylinder, and (ii) the circuit determines the cavitation by comparing the pressure response curve with a predefined pressure response curve provided to the circuit.

27. The reciprocating pump according to claim 22, wherein the operating parameter is number of pump strokes over a time period, and wherein the circuit determines the number of strokes by analyzing at least one characteristic associated with the pressure response curve.

28. The reciprocating pump according to claim 27, wherein the characteristic is selected from a group consisting (i) the leading edge, and (ii) the trailing edge.

29. The reciprocating pump according to claim 20, wherein the piston reciprocates within a piston cylinder having a replaceable liner whose operating life is a function of number of piston strokes.

30. The reciprocating pump according to claim 29, wherein the circuit computes cumulative number of strokes from the pressure response curve and determines an estimate of the remaining life of the liner as a function of the cumulative number of piston strokes.

31. The reciprocating pump according to claim 20, wherein the operating parameter is volumetric output of the reciprocating pump and wherein the circuit computes number of strokes from the pressure response curve and determines therefrom the volumetric output of the reciprocating pump.

32. The reciprocating pump according to claim 20, wherein the pump contains a bearing and wherein the circuit determines from the pressure response curve a physical condition of the bearing from the pressure response curve and programmed instructions provided to the circuit.

33. The reciprocating pump according to claim 20, wherein (i) the pump contains a piston liner, and (ii) the circuit determines from the pressure response curve a physical condition of the liner from the pressure response curve and programmed instructions provided to the circuit.