Experimental Study on Scale Prevention Method using Exhausted Gases from Geothermal Power Station

Abstract

For the utilization of geothermal energy, prevention of the scale problem is one of the most important factors. Usually, scale deposition is recognized at various places along geothermal fluid flow lines in geothermal power stations. The silica scaling from geothermal fluid is brought about by solution supersaturated with silica. It is known that silica deposition is prevented by controlling the pH of solutions maintaining acidic conditions (about 5.0). There are various methods to control the pH condition of solutions. One of them is to add mineral acid into the solution. However, this method has not been applied at present, considering its environmental impact. An alternative pH-control method using geothermal gases discharged from geothermal power stations was studied. From the environmental viewpoint, this method is more desirable than the former, because the gases are mainly composed of carbon dioxide. In this paper, results of the study to prevent silica deposition will be described.