Storage system leak detection system and method

• US 5,922,943 A
• Filed: 06/17/1997
• Issued: 07/13/1999
• Est. Priority Date: 06/14/1996
• Status: Expired due to Term

• Current Assignee: Environmental Fuel Systems, Inc.
• Original Assignee: Environmental Fuel Systems, Inc.
• Inventors: Chapman, Calvin C. IV
• Primary Examiner(s): BROCK, MICHAEL J
• Application Number:
  US08/877,276
• Time in Patent Office: 756 Days
• Field of Search: 73/49.2 T, 73/40.7, 73/864.71, 73/863.21, 252/964, 502/400
• US Class Current: 73/40.7
• CPC Class Codes: G01M 3/226 for containers, e.g. radiators

Abstract

A leak detection system and method for detecting leaks from a storage system containing a liquid, the leak detection method includes mixing one or more tracers soluble in the liquid to provide a liquid-tracer mixture within the storage system. The tracer provides a detectable component in the liquid-tracer mixture if the liquid-tracer mixture escapes the storage system through a leak. A subsurface sampling device is positioned near the storage system. The sampling device contains an adsorption material for adsorbing tracer from the liquid-tracer mixture that leaks from the system. The adsorption material is a hydrophobic, porous material. In one embodiment, a plurality of sampling devices are contained within a plurality of subsurface monitoring wells positioned around the storage system.

Claims

1. A leak detection system for detecting leaks from a storage system containing a liquid less dense than water in which water has collected at the bottom of the storage system to form a water level and a separate liquid level, comprising:

a tracer, the tracer comprising a substance soluble in the liquid to provide a liquid-tracer mixture upon introduction into the liquid, the tracer operable to provide a detectable component in the liquid-tracer mixture;

a second detectable tracer, soluble in water, operable to mix with water and escape with the water through a leak in the storage system within the water level;

a tracer introduction mechanism for introducing the tracers into the liquid; and

a sampling collection location from which tracer is sampled to determine a leak in the storage system.

2. The system of claim 1, wherein the sampling collection location further comprises a sampling well positioned near the storage system from which a vapor soil sample is collected.

3. The system of claim 2, wherein the sampling well contains a sampling device containing an adsorption material for adsorbing tracer from the liquid-tracer mixture and the water-tracer mixture.

4. The system of claim 3, wherein the adsorption material comprises a synthetic polymer adsorption material and further wherein the first tracer and the second tracer comprise relatively volatile compounds capable of adsorption by the synthetic polymer adsorption material.

5. The system of claim 4, wherein the adsorption material comprises a synthetic, hydrophobic, porous polymer material containing at least 50% divinyl benzene.

6. The system of claim 1, wherein the liquid is a hydrocarbon fuel.

7. The system of claim 1, wherein the tracer comprises a compound selected from the group consisting of halogenated compounds, sulfur hexafluoride, chlorotrifluoromethane, and carbon tetrafluoride.

8. The system of claim 1, wherein the tracer comprises relatively volatile compounds having boiling points less than -73 degrees Celsius and greater than 150 degrees Celsius.

9. The system of claim 1, further comprising an analysis system for analyzing the adsorption material, the analysis system comprising a detector to detect the presence of tracer in the adsorption material.

10. The system of claim 9, wherein the detector comprises an electron capture detector, and wherein the electron capture detector can detect the tracer without having to first perform a water purge operation.

11. A method for detecting a leak from a storage system containing a liquid less dense than water in which water has collected at the bottom of the storage system to form a water level and a separate liquid level, the method comprising;

mixing a first tracer with the liquid in the storage system to form a liquid-tracer mixture;

mixing a second tracer, the second tracer being soluble in water, with the water to form a water tracer mixture at the bottom of the storage system;

sampling for the presence of tracer at a sampling collection location; and

analyzing a sample obtained from the sampling location for the presence of the second tracer to determine if a leak is present in the storage system.

12. The method of claim 11, wherein the sampling collection location further comprises a sampling well positioned near the storage system from which a vapor soil sample is collected.

13. The method of claim 12, wherein the sampling well contains a sampling device containing an adsorption material for adsorbing tracer from the liquid-tracer mixture and the water-tracer mixture.

14. The method of claim 13, wherein the adsorption material comprises a synthetic polymer adsorption material and further wherein the first tracer and the second tracer comprise a relatively volatile compounds capable of adsorption by the synthetic polymer adsorption material.

15. The method of claim 14, further comprising:

placing a sampling device containing an adsorption material near the storage system;

absorbing the first tracer vapor onto the adsorption material within the sampling device; and

absorbing the second tracer vapor from the water-tracer mixture on the adsorption material.

16. The method of claim 15, wherein placing a sampling device containing an adsorption material further comprises placing a hydrophobic, porous, synthetic polymer material containing at least 50% divinyl benzene within the sampling device.

17. The method of claim 15, wherein the analyzing further comprises analyzing the adsorption material for the presence of the first tracer to determine if a leak is present in the storage system.

18. The method of claim 15, wherein the analyzing further comprises analyzing the adsorption material for the presence of the second tracer to determine if a leak is present in the storage system.

19. The method of claim 15, wherein sealing the sampling device within a container further comprises sealing the container with a wrap, the wrap operable to form a hermetic seal to contain the vapors from the adsorption material within the container.

20. The method of claim 15, wherein obtaining a sample further comprises obtaining a sample of headspace vapor from the adsorption material contained within the sealed container.

21. The method of claim 15, wherein obtaining a sample further comprises washing the adsorption material with an organic solvent to form a liquid aliquot sample.

22. The method of claim 21, wherein analyzing the sample further comprises analyzing the headspace vapor contained within sealed container, the analyzing further comprising;

loading the sealed container into a headspace auto-sampler coupled to a gas chromatograph;

injecting headspace vapors within the sealed container into gas chromatograph;

separating the headspace vapors on an analytical column in the chromatograph; and

detecting tracer contained within the headspace vapors with a detector.

23. The method of claim 11, wherein mixing a soluble tracer with the liquid further comprises mixing a tracer compound having a boiling point less than -73 and greater than 150 degrees Celsius with a hydrocarbon fuel in a hydrocarbon fuel storage system.