Why is it important to include a steam jet ejector within the surface condenser in a binary-cycle geothermal power plant?

It is important to include a steam jet ejector within the surface condenser in a binary-cycle geothermal power plant to remove non-condensable gases (NCGs) that accumulate in the condenser. In a binary cycle plant, geothermal fluid heats a secondary working fluid, such as isobutane or pentane, which then vaporizes and drives a turbine. After passing through the turbine, the working fluid is condensed in the surface condenser. However, even in a closed-loop system like this, some amount of NCGs, such as air that leaks into the system or gases that evolve from the geothermal fluid, will inevitably accumulate in the condenser. These NCGs reduce the partial pressure of the working fluid vapor, which impairs the condensation process and increases the condenser pressure. This higher condenser pressure reduces the pressure drop across the turbine, lowering power output and overall plant efficiency. The steam jet ejector uses a high-velocity jet of steam to create a vacuum, which draws the NCGs out of the condenser. The ejector system typically consists of multiple stages, with each stage using a steam jet to compress the NCGs to a higher pressure. The steam used in the ejector can be either live steam from the geothermal resource or auxiliary steam. The mixture of steam and NCGs from the ejector is then typically vented to the atmosphere or processed further. Without a steam jet ejector, the buildup of NCGs in the condenser would significantly reduce plant efficiency and potentially lead to operational problems. Therefore, the ejector is a critical component for maintaining the performance of the binary-cycle geothermal power plant.