Affordable Process for the Production of Strontium Bromide used in Low Grade Heat Recovery Applications

摘要

Strontium bromide, SrBr_2, has a strong potential for the recovery, storage and controlled release of low grade heat (<100°C). SrBr_2 is currently only produced at lab scale, making it unaffordable for large scale application. In this paper, a route for cost-effective industrial scale production of SrBr_2, of a potentially lower purity but still fit-for-purpose, is sought by modifying and simplifying existing processes. Based on literature, one such modified process is proposed and experimentally investigated. It is based on the Soda Ash method of producing strontium carbonate, SrCO_3, from celestine ores (SrSO_4) available in Spain. The process generates a valuable by-product, ammonium sulfate. It is found that SrBr_2 of up to 97.6% purity could be produced using HBr. If NaBr brine is available, the use of expensive HBr can be avoided, thanks to the high solubility of SrBr_2 in ethanol. Projected prices lie in the range 0.09-0.28 {EUR}/kWh of heat stored based on purified NaBr brines. A simplified LCA based on the SrBr_2 production indicates a climate change contribution of SrBr_2 to the heat storage of ～0.052 kg CO_2 eq./kWh stored. These encouraging results show that hygroscopic salts are a promising sustainable solution for the recovery of solar and/or excess industrial heat.