Method and apparatus for providing over-pressure protection for an underground storage cavern

1. A method for providing over-pressure protection for an underground storage cavern and a pipeline in fluid communication with the underground storage cavern, wherein the underground storage cavern is a salt cavern, the method comprising the steps of:

providing an over-pressurization system comprising a pressure monitor, an isolation valve, and a pressure relief valve, wherein the isolation valve is fluidly connected between underground storage and the pipeline, wherein the pressure relief valve is fluidly connected between the underground storage and the pipeline, wherein the pressure relief valve is downstream of the isolation valve;

receiving a pressurized gas from the underground storage cavern, wherein the pressurized gas is at a pressure exceeding the pressure within the pipeline;

flowing the pressurized gas through a pressure reducing device configured to reduce the pressure of the pressurized gas received from the underground storage cavern;

monitoring the pressure of the pressurized gas downstream of the pressure reducing device using the pressure monitor;

introducing the pressurized gas to the pipeline if the pressure of the pressurized gas downstream of the pressure reducing device is below a first threshold value; and

closing the isolation valve upstream of the pressure relief valve if the pressure of the pressurized gas downstream of the pressure reducing device is at or exceeds the first threshold value, such that the flow of the pressurized gas to the pipeline and the pressure relief valve is stopped.

2. The method as claimed in claim 1 , wherein the pressurized gas is at a sufficiently high pressure within the underground storage cavern such that the method comprises an absence of an additional pressurization step between receiving the pressurized gas from the underground storage cavern and introducing the pressurized gas to the pipeline.

3. The method as claimed in claim 1 , further comprising the step of venting at least a portion of the pressurized gas to a vent or flare stack via the pressure relief valve if the pressure of the pressurized gas downstream of the pressure reducing device exceeds a second threshold value.

4. The method as claimed in claim 3 , wherein the first threshold value and the second threshold value are the same.

5. The method as claimed in claim 1 , further comprising the step of removing moisture and/or impurities from the pressurized gas in downstream equipment before the step of introducing the pressurized gas to the pipeline.

6. The method as claimed in claim 5 , wherein the downstream equipment is located downstream the isolation valves and upstream the pipeline.

7. The method as claimed in claim 5 , wherein the downstream equipment comprises driers configured to remove moisture from the lower pressure gas.

8. The method as claimed in claim 5 , wherein the downstream equipment comprises filters configured to remove solid particles from the lower pressure gas.

9. The method as claimed in claim 5 , wherein the first threshold value is based on a pressure rating of the downstream equipment and/or the pipeline.

10. The method as claimed in claim 1 , wherein the pressurized gas is selected from the group consisting of nitrogen, natural gas, air, carbon dioxide, hydrogen, helium, argon, and combinations thereof.

11. The method as claimed in claim 1 , wherein the pressurized gas is hydrogen.

12. A method for providing over-pressure protection for an underground storage cavern and a pipeline fluidly connected to the underground storage cavern, wherein the underground storage cavern is a salt cavern, the method comprising the steps of:

providing an over-pressurization system comprising a pressure monitor, an isolation valve, and a pressure relief valve, wherein the isolation valve is fluidly connected between underground storage and the pipeline, wherein the pressure relief valve is fluidly connected between the underground storage and the pipeline, wherein the pressure relief valve is downstream of the isolation valve;

receiving a pressurized gas from the underground storage cavern, wherein the pressurized gas is at a pressure exceeding the pressure within the pipeline;

flowing the pressurized gas through a pressure reducing device configured to reduce the pressure of the pressurized gas received from the underground storage cavern;

monitoring the pressure of the pressurized gas downstream of the pressure reducing device using the pressure monitor;

determining whether the pressure reducing device has suffered a failure;

in the event of determination of a failure of the pressure reducing device, closing the isolation valve upstream of the pressure relief valve thereby preventing flow of the pressurized gas to the pipeline and the pressure relief valve; and

in the event of determination of a non-failure of the pressure reducing device, introducing the pressurized gas to the pipeline.

13. The method as claimed in claim 12 , wherein said determining step includes the step of comparing the monitored pressure of the pressurized gas downstream of the pressure reducing device to a threshold value, wherein failure of the pressure reducing device is characterized as the monitored pressure of the pressurized gas downstream of the pressure reducing device being above the threshold value.