1. Field of the Invention
In accord with today's need for more and better sources of energy, and sources which create minimum pollution problems, increased attention is being given to geothermal sources of energy. These include capturing and utilizing the heat from naturally hot underground water to do useful work. After absorption of its heat, the water can be returned to the ground and there are usually little or no polluting by-products from such systems.
2. Description of the Prior Art
In some such systems the hot water is passed through a heat exchanger to heat a working fluid and ultimately produce useful work.
One problem with such a system is that the water which is drawn from the ground, and which may in some cases be primarily brine, is unrefined and contains many impurities both in solution and in suspension. In fact, the hot water is often supersaturated with impurities such as silica, calcium sulfate, silicates and other compounds which can cause rapid corrosion, scaling, etc., of the surfaces of a heat exchanger if the unrefined water is passed directly through the heat exchanger. Such water may be purified or refined before passing it through the heat exchanger, as by filtering, however, this requires that the water, filtering systems, etc., be well insulated and/or pressurized so that minimum heat is lost during the refining process. Additionally the purification of the water is costly.