US 6,742,282 B2 · Detecting liquid dry conditions for liquefied compressed gases

Abstract

A method and an apparatus are disclosed for detecting an occurrence of a liquid dry condition in a container containing a liquefied compressed gas while the gaseous phase of the liquefied compressed gas is being removed from the container over time. The apparatus includes a first sensor, a second sensor, and a computer, preferably a programmed logic controller (PLC). The first sensor senses temperature (T) inside the container and provides a signal indicative thereof. The second sensor senses pressure (P) inside the container and provides a signal indicative thereof. The computer receives signals from the first and second sensors, and determines the rates of change in the pressure (dP/dt) and the temperature (dT/dt) inside the container over time. The computer identifies an occurrence of a sudden increase in the rate of change in the temperature (dT/dt) inside the container and a substantial simultaneous occurrence of a sudden decrease in the rate of change in the pressure (dP/dt) inside the container, said substantially simultaneous occurrences indicating an occurrence of a liquid dry condition in the container. The preferred embodiment includes a third sensor for sensing ambient temperature (Ta) and for providing a signal indicative thereof. The computer receives a signal from the third sensor and accounts for a change in the ambient temperature in determining the rate of change in the temperature (dT/dt) inside the container over time.

Claims12

Dependent claims

A transport vehicle for delivering a high-purity industrial liquefied compressed gas in gaseous phase, the vehicle being of the type having multiple tubes which contain the liquefied compressed ups having an apparatus for detecting an occurrence of a liquid dry condition in said tubes containing a liquefied compressed gas while the liquefied gaseous phase of the compressed gas is being removed from said tubes over time, comprising:

a first sensor for sensing temperature (T) inside said tubes and for providing a signal indicative thereof;
a second sensor for sensing pressure (P) inside said tubes and for providing a signal indicative thereof;
and
a computer for receiving signals from the first and second sensors, determining rates of change in the pressure (dP/dt) and the temperature (dT/dt) inside over time, and identifying an occurrence of a sudden increase in the rate of change in the temperature (dT/dt) inside said tubes and a substantially simultaneous occurrence of a sudden decrease in the rate of change in the pressure (dP/dt) inside said tubes, said substantially simultaneous occurrences indicating an occurrence of a liquid dry condition in said tubes.

1 more element

A transport vehicle for delivering a high-purity industrial liquefied compressed gas in gaseous phase, the vehicle being of the type having multiple tubes which contain the liquefied compressed gas having an apparatus for directing a crossover to a second supply of liquefied compressed gas upon an occurrence of a liquid dry condition in at least one of the tubes containing a first supply of a liquefied compressed gas while the gaseous phase of the first supply of liquefied compressed gas is being removed from the at least one of the tubes over time, comprising:

means for measuring pressure (P) inside the at least one of the tubes over time;
means for measuring temperature (T) inside the at least one of the tubes over time;
means for determining a rate of change in the pressure (dP/dt) inside the at least one of the tubes over time;
means for determining a rate of change in the temperature (dT/dt) inside the at least one of the tubes over time;
means for identifying an occurrence of a sudden increase in the rate of change in the temperature (dT/dt) inside the at least one of the tubes and a substantially simultaneous occurrence of a sudden decrease in the rate of change in the pressure (dP/dt) inside the at least one of the tubes, said substantially simultaneous occurrences indicating an occurrence of a liquid dry condition in the at least one of the tubes;
and
means for actuating a crossover to the second supply of liquefied compressed gas upon identifying an occurrence of a sudden increase in the rate of change in the temperature (dT/dt) inside the at least one of the tubes and a substantially simultaneous occurrence of a sudden decrease in the rate of change in the pressure (dP/dt) inside the at least one of the tubes.

4 more elements

Dependencies are inferred from the claim text.

Detecting liquid dry conditions for liquefied compressed gases

Life of this patent

Detecting liquid dry conditions for liquefied compressed gases

Life of this patent

Abstract

Claims12