Gas expander based power plant system

Abstract

A gas expander based power plant system for generating electricity at a pressure reducing station of a gas transmission pipeline is disclosed where gas at high pressure is being delivered to the distribution or gas utilization system; by means of pressure reduction with a gas expander system capable of accommodating fluctuating high pressure gas conditions and maintaining desired lower pressure gas conditions, which comprise the steps of generating steam, condensing the steam in a heat exchanger and using the heat of condensation of the steam to heat a portion of high pressure gas in a controlled manner to maintain the required gas conditions of the lower pressure line throughout the range of operation, and passing the high pressure gas through a gas expander to drive an electrical generator. In one embodiment of the system, a portion of the gas fuel supplied to a steam generator is utilized as a motive gas supply for a gas ejector which creates a vacuum in the shaft sealing chamber of the gas expander, evacuates the leakage gas thereby preventing the release of gas to the surrounding, and combines evacuated gas with remainder of gas fuel for combustion in a steam generator.

Dependencies are inferred from the claim text.