STTR Phase I: Corrosion Inhibition of Stainless Steel Alloys in High Temperature Chloride Salts for Concentrated Solar Power Applications

这个小企业创新研究第一阶段项目的更广泛的影响/商业潜力是通过为集中太阳能发电厂开发成本效益高的高温熔盐传热流体，这将使太阳能成为大规模消费的经济可行的可再生能源。随着全球对能源需求的不断增长，替代能源一直是过去几十年研究的主要焦点。熔盐传热流体在聚光太阳能电站中的应用是此类研究的一个分支领域。熔盐在高温（650℃）下具有优异的稳定性，可以以合理的成本开采和容易制造成太阳能传热流体。此外，开发的熔盐传热流体将提高太阳能发电厂的发电效率，并通过使用无处不在的经济金属（如不锈钢）提供潜在的成本节约。这种传热流体可能会使公用事业规模的无补贴安装系统价格达到每千瓦时5-6美分的竞争性价格。第一阶段研究项目的技术目标是：(I)对316L不锈钢在熔融氯盐成分中的界面腐蚀有一个基本的了解，（ii）通过使用合适的添加剂来抑制这种腐蚀。众所周知，氯化物盐可以潜在地提高工作温度（到900摄氏度），从而提高太阳能发电厂的能源效率。然而，熔融氯化物对太阳能发电厂中使用的不锈钢管的极端腐蚀行为阻碍了它们的实际应用。通过这个研究项目，Dynalene公司获得了基本的腐蚀洞察，他们打算开发一种专有的缓蚀剂组合物，可以在太阳能发电厂运行期间就地添加到氯化物盐中。这些添加剂通过在不锈钢表面在工作温度下形成连续的惰性陶瓷层来减少腐蚀，同时加强晶界。Dynalene在不锈钢表面生长了几微米厚的惰性连续陶瓷层，取得了一些初步的成功。在这个项目中，Dynalene将开发一种腐蚀包，可以减少钢的脱铬，并将316L不锈钢的腐蚀速度限制在10微米/年

The broader impact/commercial potential of this Small Business Innovation Research Phase I project is through the development of cost effective, high temperature molten salt heat transfer fluids for concentrated solar power plants that would make solar power an economical and viable source of renewable energy for mass consumption. With the worldwide growing need for energy, alternative sources of energy have been the primary focus of research over the past few decades. Molten salt heat transfer fluid used in concentrated solar power plants are one sub-area of such research. Molten salts have excellent stability at high temperature (650C) and can be mined and easily manufactured into solar heat transfer fluids at a reasonable cost. Additionally, the developed molten salt heat transfer fluid would increase the efficiency of energy generation in solar power plants and provide potential cost savings by utilizing ubiquitous economical metals such as stainless steel. The heat transfer fluid could potentially bring the subsidy-free installed system price at the utility scale to a competitive price of 5-6 cents per kilowatt-hour.The technical objectives in this Phase I research project are to (i) develop a fundamental understanding of interfacial corrosion of 316L stainless steel in molten chloride salt compositions and (ii) inhibit this corrosion by utilizing suitable additives. It is known that chloride salts could potentially increase the operating temperatures (to 900 Celcius) and hence enhance the energy efficiency of solar power plants. However, the extreme corrosive behavior of molten chlorides towards the stainless steel pipes utilized in solar plants has prevented their usage for practical applications. With the fundamental corrosion insight gained through this research project, Dynalene intends to develop proprietary inhibitor compositions that can be added to the chloride salt in-situ during the operation of a solar power plant. These additives would minimize corrosion by forming a continuous and inert ceramic layer at the operating temperature on the stainless steel surface, and simultaneo usly strengthen the grain boundaries. Dynalene had some initial success in growing a few micron-thick inert, continuous ceramic layer on a stainless steel surface. In this project, Dynalene will develop a corrosion package that would reduce dechromatization in steel and restrict the corrosion rate of 316L stainless steel to 10 micro-meters/year