Hydrogen Cavern Pad Gas Management via Brine Injection
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Solution Overview
Problem
Hydrogen production plants face challenges in maintaining reliability and meeting peak demand due to the need for large storage capacities, which existing storage facilities in salt caverns struggle to manage effectively, especially when plants require maintenance or demand exceeds production capacity.
Innovation Solution
A method for managing pad gas in salt caverns by storing a compressible fluid like hydrogen and using an incompressible fluid, such as brine, to maintain safe operating pressures and ensure cavern integrity, with controlled pressure gradients and flow rates to optimize gas and liquid movement, ensuring the cavern remains within safe operating ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large storage capacity is provided in salt caverns, then hydrogen supply reliability is improved, but cavern integrity is compromised due to excessive gas removal
Solution Approach 1:
An incompressible fluid (brine) is introduced as an intermediary substance to replace the removed pad gas volume. This brine acts as a mediator that maintains the minimum pressure required for cavern integrity while allowing maximum hydrogen storage capacity. The brine injection system enables continuous monitoring and adjustment of cavern pressure to prevent structural collapse.
Solution Approach 2:
The invention changes the physical state parameters within the cavern by introducing liquid brine to replace gaseous pad gas. This parameter change from gas to liquid allows for precise volume control and pressure maintenance, enabling the cavern to operate at optimal storage capacity while maintaining structural integrity through controlled pressure gradients.
2Productivity
If pad gas volume is reduced to increase working gas capacity, then storage efficiency is improved, but transient pressure conditions become unsafe
Solution Approach 1:
The brine injection system operates continuously to maintain safe pressure conditions as pad gas is removed. By providing continuous liquid replacement rather than batch operations, the system eliminates transient pressure fluctuations that could compromise cavern safety, ensuring smooth transitions during pad gas reduction while maximizing working gas capacity.
Solution Approach 2:
The system implements feedback control by continuously monitoring cavern pressure conditions during pad gas removal and brine injection. Pressure sensors detect transient conditions in real-time, and the injection rate is automatically adjusted to maintain pressure within safe operating limits, preventing harmful pressure drops while optimizing storage efficiency.
3Stability of the object's composition
If high pressure is maintained for cavern integrity, then structural stability is improved, but storage flexibility is reduced
Solution Approach 1:
The invention creates a dynamic pressure management system where brine injection rates are continuously adjusted based on operational needs. During normal operations, pressure is maintained at minimum levels for structural stability. During hydrogen injection or withdrawal, the system dynamically increases pressure support through brine injection, providing flexibility while maintaining stability. This dynamic approach allows the cavern to adapt to varying storage demands without compromising structural integrity.
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 approach allows for effective storage and retrieval of hydrogen, maintaining cavern integrity and meeting demand fluctuations, thereby supporting plant operations and compliance with availability agreements by managing pressure and volume within defined safe limits.
Implementation Method 1
determining a transient pressure gradient (G trans) for the underground storage volume, such that P trans < P act
Implementation Method 2
using an incompressible fluid, such as brine, to maintain safe operating pressures and ensure cavern integrity
Implementation Method 3
storing a first compressible fluid in a salt cavern... The first compressible fluid may be selected from the group consisting of nitrogen, air, carbon dioxide, hydrogen, helium, and argon
Implementation Method 4
For the purpose of this invention, the definition of high pressure is defined as a pressure at or above 10 atm
Implementation Method 5
A minimum volume of gas is stored in the cavern to provide adequate pressure to maintain the integrity of the cavern... A length of casing, permanently cemented into the surrounding rock formations
Data Source
Figure 1
AI summary
A method of pad gas management in an underground storage volume including storing a first compressible fluid, determining a transient minimum operating pressure (Ptrans), measuring the pressure (Pact), removing at least a portion of the first compressible fluid, concurrently, introducing an incompressible fluid, thereby producing a transient pressure condition controlled by the flow rate of the incompressible fluid, such that Ptrans < Pact. The method may also include a length of casing, permanently cemented into the surrounding rock formations, with a final cemented casing shoe defining the practical endpoint at an approximate depth (Dcasing), determining a transient pressure gradient (Gtrans) for the underground storage volume, wherein Ptrans < Dcasing x Gtrans. The maximum removal of the first compressible fluid is controlled such that Pmin < Pact, and wherein the transient pressure condition has a duration (D) of less than 7 days, more preferably less than 5 days.