Apparatus And Method For Pumping A Cryogenic Fluid From A Storage Vessel And Diagnosing Cryogenic Pump Performance

• US 20080302111A1
• Filed: 06/20/2008
• Published: 12/11/2008
• Est. Priority Date: 12/23/2005
• Status: Active Grant

• Current Assignee: Westport Fuel Systems Canada Inc. (Westport Fuel Systems, Inc.)
• Original Assignee: Westport Power Inc. (Westport Fuel Systems, Inc.)
• Inventors: Garner, Gage, Harper, Gregory, Batenburg, Greg, Ure, Mike
• Granted Patent: US 7,913,496 B2
• Time in Patent Office: Days
• US Class Current: 62/50.6
• CPC Class Codes: F02D 19/022 to adjust the fuel pressure, temperature or composition
• CPC Class Codes: F02D 19/025 Failure diagnosis or prevention; Safety measures; Testing
• CPC Class Codes: F02D 2041/224 Diagnosis of the fuel system
• CPC Class Codes: F02D 2200/0602 Fuel pressure
• CPC Class Codes: F02M 21/0212 comprising at least 3 C-Atoms, e.g. liquefied petroleum gas [LPG], propane or butane
• CPC Class Codes: F02M 21/0221 Fuel storage reservoirs, e.g. cryogenic tanks
• CPC Class Codes: F02M 21/0245 High pressure fuel supply systems; Rails; Pumps; Arrangement of valves
• CPC Class Codes: F02M 21/0287 characterised by the transition from liquid to gaseous phase F02M21/06 takes precedence; Injection in liquid phase; Cooling and low temperature storage
• CPC Class Codes: F04B 15/08 the liquids having low boiling points
• CPC Class Codes: F04B 2205/06 Pressure in a (hydraulic) circuit
• CPC Class Codes: F04B 49/02 Stopping, starting, unloading or idling control
• CPC Class Codes: F04B 49/022 by means of pressure
• CPC Class Codes: F04B 51/00 Testing machines, pumps, or pumping installations
• CPC Class Codes: F04B 9/105 reciprocating movement of the pumping member being obtained by a double-acting liquid motor
• CPC Class Codes: F04B 9/1172 the movement of each pump piston in the two directions being obtained by a double-acting piston liquid motor
• CPC Class Codes: F17C 2205/0142 bundled in parallel
• CPC Class Codes: F17C 2221/012 Hydrogen
• CPC Class Codes: F17C 2221/033 Methane, e.g. natural gas, CNG, LNG, GNL, GNC, PLNG
• CPC Class Codes: F17C 2223/0161 cryogenic, e.g. LNG, GNL, PLNG
• CPC Class Codes: F17C 2223/033 Small pressure, e.g. for liquefied gas
• CPC Class Codes: F17C 2223/046 : in the liquid
• CPC Class Codes: F17C 2225/0161 : cryogenic, e.g. LNG, GNL, PLNG
• CPC Class Codes: F17C 2225/035 : High pressure, i.e. between 10 and 80 bars
• CPC Class Codes: F17C 2227/0142 : with specified pump type, e.g. piston or impulsive type
• CPC Class Codes: F17C 2227/0178 : in the vessel
• CPC Class Codes: F17C 2227/0323 : in a closed loop
• CPC Class Codes: F17C 2227/0388 : separate
• CPC Class Codes: F17C 2250/01 : Intermediate tanks
• CPC Class Codes: F17C 2250/032 : using computers
• CPC Class Codes: F17C 2250/0408 : Level of content in the vessel
• CPC Class Codes: F17C 2250/043 : Pressure
• CPC Class Codes: F17C 2250/077 : when empty
• CPC Class Codes: F17C 2265/066 : for feeding engines for propulsion
• CPC Class Codes: F17C 2270/0168 : by vehicles
• CPC Class Codes: F17C 9/00 : Methods or apparatus for discharging liquefied or solidified gases from vessels not under pressure
• CPC Class Codes: Y02E 60/32 : Hydrogen storage
• CPC Class Codes: Y02T 10/30 : Use of alternative fuels, e.g. biofuels
• CPC Class Codes: Y10S 417/901 : Cryogenic pumps

Abstract

An apparatus and method are provided for pumping a cryogenic fluid from a storage vessel. The cryogenic fluid is pumped from the storage vessel to a heat exchanger and then to a delivery conduit. A pressure sensor measures fluid pressure in the delivery conduit. An electronic controller is programmed to monitor a signal from the pressure sensor, process the signal to determine from the measured process fluid pressure when cryogenic pump performance is degraded, and to send a signal to an operator of the apparatus indicating when the electronic controller determines that cryogenic pump performance has degraded below a predetermined threshold volumetric efficiency.

Claims

1. An apparatus for delivering a process fluid that is stored at a cryogenic temperature comprises:

(a) a storage vessel defining a thermally insulated cryogen space for storing said process fluid;

(b) a cryogenic pump with a suction inlet in communication with said cryogen space and a discharge outlet in communication with a delivery conduit;

(c) a heat exchanger disposed along said delivery conduit such that process fluid flowing through said delivery conduit flows through said heat exchanger;

(d) a pressure sensor for measuring process fluid pressure in said delivery conduit downstream from said heat exchanger; and

(e) an electronic controller programmed to;

(i) monitor a signal representative of process fluid pressure that is measured by said pressure sensor;

(ii) process said signal to determine from measured process fluid pressure when cryogenic pump performance is degraded; and

(iii) send a signal to an operator of the apparatus indicating when said electronic controller determines that cryogenic pump performance has degraded below a predetermined threshold volumetric efficiency.

2. The apparatus of claim 1 further comprising an accumulator vessel disposed downstream from said cryogenic pump.

3. The apparatus of claim 2 wherein said pressure sensor measures process fluid pressure within said delivery conduit indirectly by measuring process fluid pressure within said accumulator vessel.

4. The apparatus of claim 1 wherein said electronic controller is programmable to calculate the change in measured process fluid pressure over a predetermined number of preceding pump cycles, and to determine that performance of said process pump has degraded if said calculated change in process fluid pressure is less than a predetermined threshold value.

5. The apparatus of claim 4 wherein said predetermined threshold value is zero.

6. The apparatus of claim 4 wherein said electronic controller determines said predetermined threshold value from a look up table as a function of the rate at which said process fluid is removed from said delivery conduit and stroke rate of said cryogenic pump during said predetermined number of pump cycles.

7. The apparatus of claim 4 wherein said electronic controller calculates said predetermined threshold value as a function of a known nominal mass flow capacity of said cryogenic pump, said predetermined number of preceding pumping cycles, and a calculated mass of said process fluid delivered from said delivery conduit.

8. The apparatus of claim 1 wherein said electronic controller is programmable to count the number of pump cycles needed to raise process fluid pressure from a predetermined low set point to a predetermined high set point, and to determine that performance of said process pump has degraded if the number of pump cycles counted is greater than a predetermined threshold number.

9. The apparatus of claim 8 wherein said electronic controller determines said predetermined threshold number from a look up table as a function of average mass flow rate at which said process fluid was removed from said delivery conduit during said predetermined number of pump cycles.

10. The apparatus of claim 8 wherein said electronic controller calculates said predetermined threshold number as a function of a calculated number of pump cycles needed to raise process fluid pressure from said predetermined low set point to said predetermined high set point if said pump operates with a nominal mass flow capacity, after subtracting a calculated mass of said process fluid delivered from said delivery conduit.

11. The apparatus of claim 1 wherein said electronic controller is programmable to:

calculate a target process fluid pressure as a function of a known nominal mass flow capacity of the process pump, the number of pump cycles completed, and the rate that said process fluid was removed from said delivery conduit during the number of completed pump cycles; and

determine that performance of said process pump is degraded if a process fluid pressure is a predetermined amount less than said target process fluid pressure.

12. The apparatus of claim 1 wherein said process fluid is a combustible fuel and said apparatus is a fuel supply system that delivers said process fluid to a combustion chamber of an internal combustion engine.

13. The apparatus of claim 1 further comprising a second cryogenic pump that is in communication with said cryogen space or a second cryogen space defined by a second storage vessel, and a selector valve that is operable to select which one of said cryogenic pumps is operable to deliver said process fluid.

14. The apparatus of claim 13 wherein when said electronic controller determines that the performance of one of said cryogenic pumps has degraded, said electronic controller is programmed to actuate said selector valve to select the other one of said cryogenic pumps.

15. The apparatus of claim 14 wherein when said electronic controller determines that the performance of both of said cryogenic pumps has degraded, said electronic controller is programmed to determine which one of said cryogenic pumps has performance that is less degraded than that of the other, and to actuate said selector valve to select the one of said cryogenic pumps that has the less degraded performance.

16. A method of delivering a process fluid that is stored at a cryogenic temperature comprises:

(a) storing said process fluid inside a cryogen space defined by a storage vessel;

(b) pumping said process fluid from said cryogen space with a cryogenic pump;

(c) heating said process fluid to shift said process fluid into a gaseous phase;

(d) measuring process fluid pressure downstream from said cryogenic pump;

(e) determining from said measured process fluid pressure when performance of said cryogenic pump has degraded; and

(f) signaling to an operator of said cryogenic pump when its performance is degraded below a predetermined threshold volumetric efficiency.

17. The method of claim 16 wherein said method of determining that cryogenic pump performance has degraded further comprises:

(g) recording an initial measured process fluid pressure each time said cryogenic pump is commanded to an active pumping state;

(h) recording a final measured process fluid pressure after said cryogenic pump completes a predetermined number of consecutive pump cycles;

(i) calculating a change in process fluid pressure by subtracting said initial measured process fluid pressure from said final measured process fluid pressure;

(j) adding one to an error count if said change in process fluid pressure is less than a threshold value; and

(k) determining and signaling to an operator of said cryogenic pump that performance of said pump is degraded if said error count reaches a predetermined number N_d.

18. The method of claim 17 wherein said threshold value is a predetermined fixed value.

19. The method of claim 17 further comprising determining said threshold value from a look up table as a function of the rate at which said process fluid was removed from said delivery conduit and stroke rate of said cryogenic pump during said predetermined number of consecutive pump cycles.

20. The method of claim 17 further comprising calculating said threshold value as a function of a known nominal mass flow capacity of said cryogenic pump, said predetermined number of consecutive pump cycles, and a calculated mass of process fluid that was removed from a delivery conduit.

21. The method of claim 17 further comprising subtracting one from said error count if said change in process fluid pressure is greater than a threshold value and said error count is a positive number.

22. The method of claim 16 further comprising determining that performance of said cryogenic pump has degraded if a calculated change in measured process fluid pressure is negative after a predetermined number of consecutive cryogenic pump cycles.

23. The method of claim 16 wherein said method further comprises beginning a number count from zero each time said cryogenic pump is activated from an idle state, and adding 1 to said number count for each cryogenic pump cycle needed to raise process fluid pressure by a predetermined amount, and determining that performance of said cryogenic pump has degraded if said number count reaches a value that is greater than a predetermined threshold number.

24. A method of delivering a process fluid that is stored at a cryogenic temperature comprises:

(a) storing said process fluid inside a cryogen space defined by a storage vessel;

(b) pumping said process fluid from said cryogen space with a cryogenic pump;

(c) heating said process fluid to shift said process fluid into a gaseous phase;

(d) measuring process fluid pressure downstream from said cryogenic pump;

(e) commanding said cryogenic pump to an active pumping state when measured process fluid pressure is less than or equal to a predetermined low pressure set point;

(f) commanding said cryogenic pump to an idle state when measured process fluid pressure is greater than or equal to a predetermined high-pressure set point;

(g) recording an initial measured process fluid pressure each time said cryogenic pump is commanded to said active pumping state;

(h) recording a final measured process fluid pressure after said cryogenic pump completes a predetermined number of consecutive pump cycles;

(i) calculating a change in process fluid pressure by subtracting said initial measured process fluid pressure from said final measured process fluid pressure;

(j) adding one to an error count if said change in process fluid pressure is less than a threshold value; and

(k) determining and signaling to an operator of said cryogenic pump that performance of said pump is degraded if said error count reaches a predetermined number N_d.

25. A method of delivering a process fluid that is stored at a cryogenic temperature comprises:

(a) storing said process fluid inside a cryogen space defined by a storage vessel;

(b) pumping said process fluid from said cryogen space with a cryogenic pump;

(c) heating said process fluid to shift said process fluid into a gaseous phase;

(d) measuring process fluid pressure downstream from said cryogenic pump;

(e) commanding said cryogenic pump to an active pumping state when measured process fluid pressure is less than or equal to a predetermined low pressure set point;

(f) commanding said cryogenic pump to an idle state when measured process fluid pressure is greater than or equal to a predetermined high-pressure set point;

(g) detecting when said cryogenic pump is commanded to said active pumping state from said idle state, and keeping a number count of pump cycles performed by said cryogenic pump to raise process fluid pressure downstream from said cryogenic pump to said high pressure set point;

(h) resetting said number count to zero when said cryogenic pump is commanded to said idle state,

(i) adding one to an error count if said number count is greater than or equal to a threshold number; and

(j) determining and signaling to an operator of said cryogenic pump that performance of said pump is degraded if said error count reaches a predetermined number N_d.