Method And Apparatus For Providing Over-Pressure Protection For An Underground Storage Cavern

Abstract

A method and apparatus is provided which will provide over-pressure protection for an underground storage cavern by reducing the pressure of a pressurized gas stream originating from the an underground storage cavern to form a lower pressure gas stream, monitoring the pressure of a lower pressure gas stream and stopping the flow of the lower pressure gas stream to the pipeline should the pressure of the lower pressure gas stream exceed a threshold value.

I claim: 
     
         1 . A method for providing over-pressure protection for an underground storage cavern, the method comprising the steps of:
 removing a pressurized gas from the underground storage cavern;   reducing the pressure of the pressurized gas to form a lower pressure gas;   monitoring the pressure of the lower pressure gas;   introducing the lower pressure gas to the pipeline if the pressure of the lower pressure gas is below a first threshold value; and   closing an isolation valve upstream of a pressure relief valve if the pressure of the lower pressure gas is at or exceeds the first threshold value such that the flow of the lower pressure gas to the pipeline 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 removing the pressurized gas from the underground storage cavern and introducing the lower pressure gas to the pipeline. 
     
     
         3 . The method as claimed in  claim 1 , further comprising the step of venting at least a portion of the lower pressure gas to a vent or flare stack via a pressure relief valve if the pressure of the lower pressure gas 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 lower pressure gas in downstream equipment before the step of introducing the lower pressure 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 . An apparatus for providing over-pressure protection for an underground storage cavern, the apparatus comprising:
 a pressure reducing device in fluid communication with the underground storage cavern, the pressure reducing device configured to reduce the pressure of the pressurized gas received from the underground storage cavern to form a lower pressure gas;   a pressure monitor configured to monitor the pressure of the lower pressure gas;   at least one isolation valve in fluid communication with the pressure reducing device, the at least one isolation valve configured to stop the flow of gas if the pressure monitor senses the pressure of the lower pressure gas exceeds a first threshold value; and   downstream equipment disposed downstream the pressure reducing device, the downstream equipment having a maximum operating pressure.   
     
     
         12 . The apparatus as claimed in  claim 11 , wherein the downstream equipment comprises a water removing device having a pair of desiccant driers configured in a permutable fashion such that one of the driers can be in operation while the other dryer is being regenerated. 
     
     
         13 . The apparatus as claimed in  claim 11 , wherein the downstream equipment comprises a particle removal device having a mechanical filtration system having a filter housing, wherein the mechanical filtration system is configured to allow for isolation of the filter housing. 
     
     
         14 . The apparatus as claimed in  claim 13 , wherein the particle removal system comprises a magnetic separation system configured to remove fine dust particles based on magnetic properties. 
     
     
         15 . The apparatus as claimed in  claim 11 , wherein the first threshold value is based on the maximum operating pressure of the downstream equipment. 
     
     
         16 . The apparatus as claimed in  claim 11 , further comprising a pressure relief valve located downstream the isolation valve, the pressure relief valve configured to send at least a portion of the lower pressure gas to a vent or flare stack if the pressure of the lower pressure gas exceeds a second threshold value. 
     
     
         17 . The apparatus as claimed in  claim 16 , wherein the first threshold value and the second threshold value are the same.