Underground Cavern Pressure Control via Liquid Buffer
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Solution Overview
Problem
Hydrogen production plants face challenges in maintaining pressure in underground storage caverns during transient operations, particularly when taken offline for maintenance or when demand exceeds production capacity, risking cavern collapse and violating supply agreements.
Innovation Solution
A method involving the controlled storage and removal of compressible fluids and introduction of incompressible fluids within underground storage volumes, using pressure and flow control to maintain safe operating pressures, preventing cavern collapse and ensuring integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large storage capacity is provided to maintain plant availability during maintenance or peak demand, then reliability is improved, but device complexity and operational difficulty increase due to the need to maintain minimum pad gas volumes and prevent cavern collapse
Solution Approach 1:
A liquid intermediary substance is introduced into the underground storage cavern to act as a pressure buffer. The liquid maintains hydrostatic pressure on the cavern walls and prevents collapse during gas withdrawal, enabling reliable storage operation without complex active pressure control systems. The liquid serves as a passive mediator that automatically maintains structural integrity.
Solution Approach 2:
The invention applies hydraulic principles by using liquid to maintain pressure in the gas storage cavern. The liquid column creates hydrostatic pressure that supports the cavern structure, replacing the need for complex pneumatic pressure control systems. This hydraulic approach simplifies the operational complexity while maintaining reliability.
2Adaptability or versatility
If compressible gas is removed from underground storage during transient operation, then hydrogen supply flexibility is improved, but cavern integrity deteriorates due to pressure drop and risk of collapse
Solution Approach 1:
The liquid intermediary substance maintains continuous hydrostatic pressure on the cavern walls during gas withdrawal operations. This passive pressure support system allows flexible gas removal to meet varying demand while automatically preventing pressure drops that would compromise cavern structural integrity.
3Strength
If active pressure control systems are used to maintain cavern pressure during transient operation, then cavern integrity is improved, but device complexity and operational difficulty increase
Solution Approach 1:
The liquid in the storage cavern provides self-service pressure support through its inherent hydrostatic properties. The liquid automatically maintains pressure on the cavern walls without requiring external active control systems, sensors, or actuators. This passive self-service approach maintains cavern integrity while eliminating complex pressure control infrastructure.
4Quantity of substance
If large volumes of gas are stored in underground caverns, then storage capacity is improved, but the risk of cavern collapse increases due to weight of overburden and pressure fluctuations
Solution Approach 1:
The liquid intermediary substance acts as a protective buffer between the stored gas and the cavern structure. It maintains constant hydrostatic pressure on the walls, isolating the structure from pressure fluctuations caused by gas withdrawal or injection. This allows large storage capacities to be utilized while minimizing collapse risk.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method effectively maintains cavern integrity by controlling pressure within defined safe ranges, preventing collapse and ensuring reliable hydrogen supply during transient operations.
Implementation Method 1
introducing an incompressible fluid into the underground storage volume, wherein the flow rate of the incompressible fluid is controlled such that Pmin ≤ Pact ≤ Pmax
Implementation Method 2
removing at least a portion of the first compressible fluid from the underground storage volume, and concurrently, introducing an incompressible fluid into the underground storage volume
Data Source
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AI summary
A method of maintaining pressure in an underground storage volume during transient operation is presented. Including storing a first compressible fluid, determining a safe minimum operating pressure (Pmin), and a safe maximum operating pressure (Pmax), measuring the pressure (Pact), removing or introducing the first compressible fluid, and concurrently, introducing or removing an incompressible wherein the flow rate of the incompressible fluid is controlled such that Pmin < Pact < Pmax. The method may include injecting a second compressible fluid into an incompressible fluid within the underground storage volume, thereby producing a gas lift fluid.