Abstract Nowadays, the most matured thermal energy storage (TES) technology for Concentrated Solar Power (CSP) plants is the use of molten solar salts (60 wt% NaNO3 – 40 wt% KNO3), but the thermal decomposition of nitrate salts can result in changes in the composition of molten salts or potential risks of NOx emissions. Up to now, all studies on the decomposition of nitrates in TES systems focus on the effect of the effect of sodium and potassium nitrates in contact with the container material and the NOx emissions formation, but none investigate the effect or contribution of impurities in it. Moreover, although the chemistry of the nitrates decomposition is well known, there is a big uncertainty in commercial solar plants on the production rate of NOx. The only cation in nitrates from mining origin is magnesium, and since it occurs as nitrate, it does contribute to NOx formation. This paper studies the effect of such impurity in the thermal decomposition of the solar salt. The results show that the impurity Mg(NO3)2 is the main source of NOx emissions in solar salts during the commissioning of the plant due to its thermal decomposition during the melting process. But as described this NOx production can be handled by vents and abatement systems if it is needed.

中文翻译：

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杂质硝酸镁对日光盐热分解的影响

摘要 目前，聚光太阳能 (CSP) 发电厂最成熟的热能储存 (TES) 技术是使用熔融太阳能盐 (60 wt% NaNO3 – 40 wt% KNO3)，但硝酸盐的热分解会导致熔盐成分的变化或 NOx 排放的潜在风险。到目前为止，所有关于 TES 系统中硝酸盐分解的研究都集中在硝酸钠和硝酸钾与容器材料接触和 NOx 排放形成的影响上，但没有研究其中杂质的影响或贡献。此外，虽然硝酸盐分解的化学过程是众所周知的，但商业太阳能发电厂对 NOx 的产生率存在很大的不确定性。采矿来源的硝酸盐中唯一的阳离子是镁，因为它以硝酸盐的形式存在，它确实有助于 NOx 的形成。本文研究了这种杂质对太阳盐热分解的影响。结果表明，杂质 Mg(NO3)2 由于其在熔化过程中的热分解，是该装置调试期间太阳盐中 NOx 排放的主要来源。但如上所述，如果需要，可以通过通风口和减排系统处理这种 NOx 产生。