System and method for detecting and quantifying changes in the mass content of liquid storage containers

Abstract

A storage tank leak detection system, including a quartz crystal type pressure transducer held at a constant temperature, a bubbler-based pressure sensor for reporting tank bottom pressure measurements to the transducer, a fluid surface measurement apparatus to report liquid surface pressure to the transducer, atmospheric pressure measuring apparatus, and a computing system for, based on data reported by all components, effecting data correction (corrected for atmospheric and container physical variations during data gathering) and regression techniques to yield data indicative of changes, if any, in mass content of a liquid storage container, such as a surface storage tank for petroleum and other chemicals.

1 . A computer system for detecting and measuring changes in the mass content of liquid storage containers comprising:
 A first computer in communication with a differential pressure sensor means, a high pressure measurement means, a low pressure measurement means, an ambient temperature management means and a second computer;   wherein the first computer performs a method comprising:
 receiving data representative of differential between a first and a second pressure parameters from a differential pressure sensor means configured for receiving input representative of said first and said second pressure parameter; 
 receiving data from said high pressure measurement means configured for measuring a first pressure parameter in a liquid medium residing within a container, and engaged with said differential pressure sensor means for facilitating the sensing of said first pressure parameter by said differential pressure sensor means; 
 receiving data from said low pressure measurement means configured, when positioned substantially at the surface of said liquid medium, for measuring said second pressure parameter at said surface of said liquid medium and for facilitating the sensing of said second pressure parameter by said differential pressure sensor means; 
 receiving data indicative of ambient temperature from said ambient temperature measurement means for measuring said ambient temperature near said container; 
 storing said data from said differential pressure sensor means, said high pressure measurement means, said low pressure measurement means and said ambient temperature management means on a storage medium; and 
 transmitting said stored data to said second computer; 
   wherein said first computer is configured for recording in a time continuum basis data from said differential pressure sensor means, said high pressure measurement means, said low pressure measurement means, and said ambient temperature measurement means, and for deriving data indicative of changes over time of the mass of said liquid medium within said container.   
     
     
         2 . The computer system of  claim 1 , wherein said second computer performs a method comprising:
 selecting data from certain periods;   analyzing said selected data to detect changes in mass content data of liquid storage container;   generating a human perceptible indication of changes in said mass content data between a plurality of points in time; and   recording data indicative of changes in said mass content data attributable to leakage of said storage container.   
     
     
         3 . The computer system of  claim 1  wherein the data is collected over 36 to 60 hours. 
     
     
         4 . The computer system of  claim 2  wherein the selected data is free from the significant effects of solar radiant energy, rain and other significant weather event. 
     
     
         5 . The computer system of  claim 2 , wherein the selected data is generated between sunrise and sunset. 
     
     
         6 . The computer system of  claim 2  further comprising barometric pressure measuring means configured for measuring atmospheric pressure near said container and reporting data indicative of said atmospheric pressure to said first computer, and wherein said second computer is further configured for deriving said data indicative of changes over time of the mass of said liquid medium within said container, basing such derivation, in part, on said data indicative of said atmospheric pressure. 
     
     
         7 . The computer system of  claim 1  wherein said high pressure measurement means is a bubbler pressure measurement means. 
     
     
         8 . The computer system of  claim 7  wherein said bubbler pressure measurement means is in sealed fluid communication with a source of substantially constant pressure, inert gas. 
     
     
         9 . The computer system of  claim 1  further comprising temperature management means configured for maintaining the temperature of said differential pressure sensor means at a substantially constant level.