| Abstract |
Flash type power plant uses saturated steam for maximum load generation through a steam turbine. The saturated steam at a particular temperature and pressure would guarantee a certain load given a turbine of a certain efficiency rating and performance. Load in a geothermal steam plant is the electrical energy generated from the Generator driven by a steam turbine. In a steam plant the prime mover is the Turbine while the working fluid is a natural occurring steam found along the East African rift that both Kenya and Ethiopia are located. This steam has to be harnessed from the sub-surface by way of drilling. Cleaning and drying to saturation has to be done so that when it is expanded through a turbine work is done inside the turbine by converting the kinetic energy and enthalpy of steam into mechanical energy (Rotary motion) of the turbine. Steam from the sub-surface comes in its impure form and this causes a lot of corrosion and scaling of most auxiliary components and surface equipment along its way. Scaling of surface equipment such as turbine and steam pipeline ought to be mitigated against lest we stop our business of electricity generation. Steam and blade washing technique is the science of spraying geothermal water on the scaled surface equipment to avoid scale setting through deposition and settling. Steam washing as well as blade washing should be instigated automatically by reducing or avoiding human intervention using some set parameters from the distributed control system (DCS). Steam chest pressure or bowl pressure determines whether steam washing or blade washing should be started or not. A higher bowl pressure indicates that there is a likely resistance for steam to flow in the forward pass through the several turbine stages (Rotary and stationary blades). This resistance is caused by possible deposition of impurities (scaling) on the stationary blades, the rotary blades or both. This resistance causes a build up of back pressure against the incoming steam thereby reducing its net effective steam pressure expanding inside the turbine. Therefore it is because of the build up of the bowl pressure that steam washing and blade washing should be automatically initiated to start spraying the condensate onto the steam increasing its density for scrubbing/cleaning the scaling. The steam and blade wash should be started automatically once a bowl pressure sensor senses a higher bowl pressure which would reduce the Load generated. This pressure sensor should automatically send a signal to start steam and blade washing to clear the scaling and therefore take the load up once again. |