In many geothermal areas, an abatement of hydrochloric acid present in the steam is essential in order to produce energy before turbine expansion. In fact, concentrations of acid higher than 5 ppm risk seriously corroding the turbine, significantly increasing the costs of this energy source. In 2018, Enel Green Power decided to support a research project, called Georockwash, and aimed at identifying a new process for the abatement of HCl in geothermal steam with the collaboration of Magona Technological Pole, as a centre specialized in the experimentation of industrial processes on a pilot scale.
The project has developed a new abatement process based on the use of dry CaCO3, as agent for the neutralization of acid. The process has been tested initially on a laboratory scale and then on a pilot scale with the construction of a 500 kg/h steam plant, skid mounted and transportable.
The experimentation campaign on the pilot plant was conducted first at the facilities of the Magona Pole and then at an Enel Green Power geothermal power plant. In the experimentation the effects of the main operating parameters on the abatement efficiency were evaluated and correlated with a semi-empirical equation.
Finally, the experimentation showed abatement efficiencies often higher than 95%, confirming the suitability of the new process for geothermal use with low investment and operating costs.