Carbon-based coatings for suppression of silica adhesion in geothermal power generation
Yuya Nakashima, Noritsugu Umehara, Hiroyuki Kousaka, Takayuki TOKOROYAMA, Motoyuki Murashima, Daisukea Mori
Abstract
Geothermal steam, the power source in geothermal power generation, contains a large amount of silica. Silica adhesion on geothermal power generator equipment hinders stable power generation. This work aimed to suppress silica adhesion by using diamond-like carbon (DLC). DLC with various surface structures was investigated by X-ray fine structure and elastic recoil detection analysis. The adhered silica amount was drastically reduced by using DLC rather than turbine steel. Further, the optimum DLC structure to reduce silica adhesion was revealed. Reducing the sp² bond fraction and increasing the hydrogen content of the outermost surface of DLC reduce the adhered silica amount, although there was no correlation with the surface energy. Therefore, silica adhesion has a different mechanism from conventional adhesion.