Differential pressure gauge for cryogenic fluids

• US 6,542,848 B1
• Filed: 07/31/2000
• Issued: 04/01/2003
• Est. Priority Date: 07/31/2000
• Status: Expired due to Term

• Current Assignee: Chart Incorporated (Chart Industries Incorporated)
• Original Assignee: Chart Incorporated (Chart Industries Incorporated)
• Inventors: Neeser, Timothy, Kuechenmeister, Robert
• Primary Examiner(s): Barlow, John
• Assistant Examiner(s): Sun, Xiuqin
• Application Number:
  US09/628,621
• Time in Patent Office: 974 Days
• Field of Search: 700/281, 700/40, 733/04.C, 738/626.8, 702/156, 702/51, 702/173, 702/9, 702/5, 702/55, 585/241, 600/532, 600/16, 417/53, 417/328, 356/506, 361/283, 361/4, 360/246.8, 310/338, 310/324, 222/544, 264/45.5, 290/2, 180/69.5, 181/106, 62/451, 62/502, 62/481, 62/501
• US Class Current: 702/156
• CPC Class Codes: F17C 13/025 having the pressure as the parameter
• CPC Class Codes: F17C 13/028 having the volume as the parameter
• CPC Class Codes: F17C 2201/0109 with exteriorly curved end-piece
• CPC Class Codes: F17C 2201/032 with substantially vertical main axis
• CPC Class Codes: F17C 2201/035 with substantially horizontal main axis
• CPC Class Codes: F17C 2201/056 Small (<1 m3)
• CPC Class Codes: F17C 2203/0391 by vacuum
• CPC Class Codes: F17C 2203/0629 Two walls
• CPC Class Codes: F17C 2221/011 Oxygen
• CPC Class Codes: F17C 2221/012 Hydrogen
• CPC Class Codes: F17C 2221/013 Carbone dioxide
• CPC Class Codes: F17C 2221/016 Noble gases (Ar, Kr, Xe)
• 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 2223/043 in the gas
• CPC Class Codes: F17C 2223/046 in the liquid
• CPC Class Codes: F17C 2250/032 using computers
• CPC Class Codes: F17C 2250/034 using wireless transmissions
• CPC Class Codes: F17C 2250/0426 Volume
• CPC Class Codes: F17C 2250/0434 Pressure difference
• CPC Class Codes: F17C 2250/0491 : Parameters measured at or inside the vessel
• CPC Class Codes: F17C 2250/0495 : the indicated parameter is a converted measured parameter
• CPC Class Codes: F17C 2260/033 : by enhancing insulation
• CPC Class Codes: G01F 22/02 : involving measurement of pressure
• CPC Class Codes: G01F 23/14 : by measurement of pressure
• CPC Class Codes: G01F 25/0084 : for measuring volume
• CPC Class Codes: Y02E 60/32 : Hydrogen storage

Abstract

A differential pressure gauge for a cryogenic storage tank provides onboard entry, by an operator, of tank dimensions, tank orientation, and the type of liquid stored within the tank. A differential pressure sensor supplies a signal corresponding to a differential pressure. The gauge uses the information supplied by an operator, combined with stored formulas and liquid characteristics, to perform real-time liquid volume computations. The liquid volume may be displayed on the gauge itself or may be transmitted via telemetry to an external device.

Claims

1. A method of determining in real time a volume of liquefied gas in a cryogenic storage tank having a liquid space and a head space, comprising the steps of:

a) storing the dimensions and orientation of the storage tank;

b) determining and storing the type of liquefied gas contained in said tank;

c) measuring the differential pressure between the liquid space and the head space;

d) estimating an average liquid pressure;

e) retrieving a liquid density corresponding to the type of liquefied gas and the estimated pressure from a predetermined set of stored density constants;

f) calculating in real time the liquid volume as a function of tank dimensions, tank orientation, differential pressure and liquid density; and

g) displaying the liquid volume on a display.

2. The method of claim 1 further comprising the steps of:

selecting one of a predetermined stored set of units of measurement for displaying the liquid volume on the display;

computing a number representative of the liquid volume as a function of the differential pressure, tank dimensions, tank orientation, and liquid density; and

converting the computed number to a measurement having the selected unit of measurement for displaying on the display.

3. The method of claim 1 further comprising the steps of:

receiving an analog signal from a differential pressure sensor, the signal being proportionate to a differential pressure between the liquid space and the head space;

converting the analog signal to a digital signal; and

analyzing the digital signal.

4. The method of claim 1, wherein the step of storing the dimensions of the storage tank comprises the step of storing a tank height and diameter.

5. The method of claim 1, further comprising the steps of:

storing an alert volume; and

generating an alert signal if the calculated liquid volume is below the alert volume.

6. The method of claim 1, further comprising the step of

transmitting the computed liquid volume to a remote device.

7. The method of claim 6, further comprising the step of

transmitting the alert signal to a remote device.

8. The method of claim 7, further comprising the step of

transmitting a request for additional liquified gas to a location remote from the storage tank.

9. The method of claim 1, further comprising the step of

storing the liquefied gas properties, unit of measure conversion formulas, and the tank dimensional formula are stored in nonvolatile memory coupled to the microcontroller.

10. A system for displaying liquid volume of a cryogenic fluid stored in a cryogenic tank, the fluid stored within the tank, the tank containing a liquid space and a head space, the system comprising:

a differential pressure sensor coupled to the head space and to the liquid space for sensing a differential pressure between the liquid space and head space and generating a differential pressure signal as a function of the differential pressure;

an operator input interface for entering the dimensions of the container and the type of cryogenic fluid;

a nonvolatile memory coupled to the operator input interface, for storing the dimensions of the tank, the type of cryogenic fluid, tank dimension formulas, and cryogenic fluid densities;

a microcontroller coupled to the pressure sensor and the nonvolatile memory adapted to receive the differential pressure signal, which calculates, in real time, liquid volume based upon the dimensions of the tank, the type of cryogenic fluid, the desired average pressure level, the tank dimension formulas, and the cryogenic fluid densities; and

a display coupled to the microcontroller for displaying the liquid volume.

11. The system of claim 10, further comprising an analog to digital converter coupled to the differential pressure sensor and the microcontroller for converting an analog signal generated by the differential pressure sensor to a digital differential pressure signal to be received by the microprocessor.

12. The system of claim 10, further comprising a transmitter, for transmitting the calculated liquid volume to a remote device.

13. The system of claim 12, wherein the transmitter comprises a phone transmitter.

14. The system of claim 10, wherein the operator input interface comprises a keypad.

15. A high-pressure housing for a differential pressure sensor chip comprising:

a) first and second housing portions, each of said portions including;

i. a tap connection formed through the portion and leading from an outside surface of the portion to an inside surface of the portion;

ii. an annular groove formed in the inside surface of the portion and concentrically positioned about the tap connection;

iii. a channel formed in the inside surface of the portion including a chip segment that surrounds the annular groove and tap connection and a longitudinal segment extending from the chip segment to an edge of the portion;

b) first and second O-rings positioned with the annular grooves of the first and second portions, respectively;

c) a fastener for joining the first and second portions with their inside surfaces in an abutting configuration; and

d) said chip segments of said first and second portion channels sized so that when the first and second portions are joined, the differential pressure sensor chip may be received within a resulting chip passageway and secured in position by said O-rings with electrical leads of the sensor chip exiting the housing through an electrical lead passageway formed by the joined longitudinal segments of the first and second portion channels.

16. The housing of claim 15 wherein said first and second housing portions are constructed from brass.

17. The housing of claim 15 wherein said fastener is a set screw.

18. The housing of claim 15 further comprising a gasket positioned upon the edges of said first and second portions, said gasket surrounding the electrical lead passageway.

19. The housing of claim 15 further comprising a gasket sandwiched between the joined first and second portions.

20. The housing of claim 15 wherein the chip segments of the channels of the first and second portion are circular.