Process for treating geothermal brine in two phase brine separators

Abstract

A process for treating hot, pressurized geothermal brine in a liquid-vapor phase separator comprises contacting the brine in the separator with between about 0.2 and about 1.5 parts per million of a defoaming agent so as to substantially reduce the amount of foaming in the separator caused, in part, by steam bubbling through the brine. The preferred defoaming agents are polyglycols having molecular weights between about 1000 and about 2500, those agents having molecular weights below about 1000 being too volatile and those above about 2500 being too difficult to solubilize in the brine. If the separator comprises a draft tube-type flash crystallizer in which silica-rich geothermal brine is contacted with a seed material onto which silica from the brine deposits, the process additionally includes establishing and maintaining a brine level in the crystallizer causing circulation of the brine at a rate substantially reducing the rate of silicious scaling of inner walls of the crystallizer which would result in the absence of brine circulation, the established and maintained brine level being such that in the absence of the defoaming agent, excessive amounts of brine in the form of foam would be carried over into steam discharged from the crystallizer. In preexisting separators in which a design steam production rate cannot be attained because of brine foaming, the addition of a defoaming agent by the present process may enable steam production at a rate greater than the design rate.