Air Products and Chemicals, Inc.

Sukla Chandra

Naser Mahmud Chowdhury

Warren Matthew Janigian

John Irven

Dao-Hong Zheng

Reiner Reinhard Taege

Kenneth Coull

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 (T ) 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.

Detecting liquid dry conditions for liquefied compressed gases

Detecting liquid dry conditions for liquified compressed gases

A method [and an apparatus are] is 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] method uses 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 (T.sub.a) 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.]

A control vent system is disclosed for reducing volatile impurities in a gaseous product of ultra-high purity delivered from a storage vessel containing an inventory of a non-cryogenic liquid product, as well as a method and a system for delivering the product from the storage vessel. The control vent system includes a vent line attached to the storage vessel and a condenser in the vent line. Coolant (e.g., a refrigerant) is transferred between the condenser and a source of coolant, such as a refrigeration unit. The method of reducing volatile impurities includes three steps. The first step is to vent part of the gaseous vapor from the gaseous vapor space to a condenser. The second step is to cool the vented gaseous vapor in the condenser to a temperature below the boiling point of the liquid product and above the boiling points of the volatile impurities. As a result, a first portion of the vented gaseous vapor is condensed and a second portion of the vented gaseous vapor is not condensed. The final step is to vent the second portion of the vented gaseous vapor from the condenser.

Growing community of inventors

Calcutta, India

Sukla Chandra