A simple method for the inhibition of the corrosion of carbon steel by molten nitrate salt for thermal storage in concentrating solar power applications

Abstract

Corrosion is an important issue in high-temperature applications such as Concentrated Solar Power (CSP) technology, playing a crucial role in the long-term use of storage tanks, heat exchanger and piping materials which account for a considerable component of the investment costs. While there are many studies regarding the corrosion rates of container materials under the conditions of CSP, there is little progress in the field of their degradation prevention by anticorrosion methods. This work presents an analysis of the corrosion mechanisms between the most economical construction material-carbon steel-and molten nitrate salt. A method to protect the carbon steel against corrosion by molten salt at high temperature was proposed, involving the formation of a calcium carbonate layer on the carbon steel surface. The stability of the layer was tested under isothermal and temperature cycling conditions up to 500°C, in both inert and air atmospheres in the presence or absence of humidity. The protection method proposed has potential to reduce investment costs for CSP technology.

High-Temperature Monitoring in Central Receiver Concentrating Solar Power Plants with Femtosecond-Laser Inscribed FBG

“…Mean outlet temperature in the solar receiver is typically about 550 °C. Operation with MS are constraint by their metal corrosion capability, which requires special selection of materials in contact with the MS, and working temperature limits [ 5 , 6 ]. MS must be kept in liquid state at temperatures higher than their melting temperature range (260–270 °C) usually working over 290 °C, otherwise undesirable pipe blocking could be occurred.…”

Rheological Characteristics of Molten Salt Seeded with Al2O3 Nanopowder and Graphene for Concentrated Solar Power

“…Besides the common nanoparticles, graphene has drawn researchers' attention recently and has been studied extensively [30][31][32][33][34][35][36]. Liu et al [34] prepared and characterized two types of reduced graphene oxide (GO) combined with alkane, alcohol and carboxylic acid phase change materials (PCMs), and the thermal conductivity of the rGO/stearic acid composite could be increased to 3.21 (W/m•K).…”

“…Kant et al [35] pointed out that emulsifying graphene nanoparticles in PCM resulted in a relative increase of the dynamic viscosity, and significantly degraded its natural convection heat transfer performance. Furthermore, the corrosion of carbon steel with the contact of molten nitrate salt is always an important issue, and it was found that graphite could form a protective carbonate layer to improve the resistance of carbon steel [36]. Thus, adding graphene into the salt should positively affect the corrosion of container in the CSP system.…”

Thermal Energy Storage in Solar Power Plants: A Review of the Materials, Associated Limitations, and Proposed Solutions

“…Grosu et al developed a calcium carbonate layer onto steel to inhibit corrosion. The corrosion tests were conducted under inert and air exposure conditions with isothermal temperature up to 500 • C [67]. The layer was stable in the tests; however, dynamic testing is required to verify the efficacy of the layer.…”

“…The layer was stable in the tests; however, dynamic testing is required to verify the efficacy of the layer. Furthermore, the presence of layer onto the whole steel structure is extremely important to avoid localized corrosion [67]. Problems of such corrosion are not only the failure of the container-reaction of iron in steel with the eutectic PCM forms non-melting aluminides which cannot work for the next cycle of melting-freezing [68].…”