Compressed Air Energy Storage (CAES) in underground salt caverns is a large-scale energy storage technology in the world. The basic principle of CAES consists of two parts: (1) to use the surplus power of the grid to drive the air compressor to inject air into the underground salt caverns during the low electricity consumption period; (2) to release the high-pressure air in salt caverns during the peak electricity consumption period to drive the gas turbine generator to generate electricity. The electricity is stored as a type of compressed air. Recently, generators and related devices on the ground have experienced corrosion problems in some salt caverns storage energy engineering. This paper aims to explore whether the generator corrosion problems are caused by NaCl which may be carried out by compressed gas from the salt caverns. Two possible mechanisms were considered: evaporation and the other is the fluctuation of the air dissolution rate in brine. Two kinds of experiments were designed and conducted. Firstly, saturated brine evaporation was simulated using the distillation method. Secondly, the precipitation process of air from the saturated brine during the gas extraction process was simulated. The results were analyzed based on the principle of energy balance and thermodynamics. Both test results show that the air flow cannot take out NaCl from the saturated brine under the experimental conditions. The conclusion can be used in the CAES system and provides suggestions for reducing the possibility of corrosion of production pipelines and generators.

1. Introduction

The main component of salt rock is NaCl, which is the characterized by compact structure, low permeability, low porosity, low creep strength, and self-healing of damage (Wang et al., 2021). The mechanical and chemical properties are relatively stable and are considered as an ideal medium for long-term underground storage of oil, natural gas, high-level radioactive nuclear waste (Chen et al., 2015) and compressed air (Li et al., 2003).

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