Air tightness of compressed air storage energy caverns with polymer sealing layer subjected to various air pressures

Abstract

During the operation of compressed air storage energy system, the rapid change of air pressure in a cavern will cause drastic changes in air density and permeability coefficient of sealing layer. To calculate and properly evaluate air tightness of polymer sealing caverns, the air-pressure-related air density and permeability must be considered. In this context, the high-pressure air penetration in the polymer sealing layer is studied in consideration of thermodynamic change of the cavern structure during the system operation. The air tightness model of compressed air storage energy caverns is then established. In the model, the permeability coefficient and air density of sealing layer vary with air pressure, and the effectiveness of the model is verified by field data in two test caverns. Finally, a compressed air storage energy cavern is taken as an example to understand the air tightness. The air leakage rate in the caverns is larger than that using air-pressure-independent permeability coefficient and air density, which is constant and small in the previous leakage rate calculation. Under the operating pressure of 4.5–10 MPa, the daily air leakage in the compressed air storage energy cavern of Yungang Mine with high polymer butyl rubber as the sealing material is 0.62%, which can meet the sealing requirements of compressed air storage energy caverns. The air tightness of the polymer sealing cavern is mainly affected by the cavern operating pressure, injected air temperature, cavern radius, and sealing layer thickness. The cavern air leakage rate will be decreased to reduce the cavern operating pressure the injection air temperature, or the cavern radius and sealing layer thickness will be increased.

Keywords

• Compressed air storage energy
• Polymer sealing layer
• Air tightness
• Permeability coefficient
• Air density