Claims
- 1. A method of determining in a volume of liquified gas in a cryogenic storage tank having a liquid space and a head space, comprising the steps of:
entering and storing the dimensions and orientation of the storage tank; entering and storing the type of liquefied gas contained in said tank; entering and storing a stratification coefficient; storing a lookup table of conversion coefficients used to covert a head pressure value into an estimated average pressure value, said conversion coefficients being accessed according to the entered dimensions and orientation of the storage tank; storing a lookup table of density constants, stored according to the estimated average pressure, and liquid type; measuring the differential pressure between the liquid space and the head space; measuring the pressure at the head space; calculating an estimated average pressure using the measured head pressure and the stratification coefficient; reading a liquid density value from a look-up table of density constants using the calculated estimated average pressure and the entered liquid type; and computing in a liquid volume in said tank as a function of said differential pressure, liquid density tank dimensions, tank orientation, and type of liquefied gas.
- 2. The method of claim 1, wherein the step of computing the liquid volume further comprises the step of displaying the liquid volume on a display.
- 3. 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.
- 4. 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.
- 5. 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; a pressure sensor coupled to the head space for sensing a pressure of the head space; 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, a look-up table containing liquid density conversion constants for each of plural tank dimensions, and a look-up table containing cryogenic fluid densities for each of plural liquid types and plural pressure ranges; a micro-controller coupled to the pressure sensor, the differential pressure sensor and the nonvolatile memory, said micro-controller reading from said nonvolatile memory a selected liquid density conversion constant corresponding to said stored dimensions of the container; said micro-controller calculating an estimated average pressure as a difference between said head space pressure and said liquid density conversion constant, and reading from said nonvolatile memory a selected liquid density corresponding to said estimated average pressure and said liquid type; said micro-controller calculating a liquid volume based upon the dimensions of the tank, the type of cryogenic fluid, the tank dimension formulas, and the cryogenic fluid densities; and a display coupled to the micro-controller for displaying the liquid volume.
RELATED APPLICATION
[0001] This application is a continuation-in-part of commonly assigned U.S. patent application Ser. No. 09/628,621 entitled DIFFERENTIAL PRESSURE GAUGE FOR CRYOGENIC FLUIDS filed Jul. 31, 2000.
Continuation in Parts (1)
|
Number |
Date |
Country |
Parent |
09628621 |
Jul 2000 |
US |
Child |
09923636 |
Aug 2001 |
US |