The task of the forced cooling fan rack is to supply cooling air to the steam turbine to shorten the cooling time after shutdown.
The cooling air is fed to the steam turbine through connections located in the condenser (vacuum breaker) and the HP housing balance flange (hole) – or the cold reheat section upstream of the retention valve assisted by the HP turbine exhaust. The pressurised air (cooling air) is blown through flexible hoses in these two openings with mobile external equipment subject to this specification.
The cooling air flows back through the LP, IP and HP turbine to the common vent connection in the cold reheat steam system and released to the atmosphere.
In addition, the equipment must be able to function as a mobile dehydrating vent with an absorption component (air dryer) and accessories (e.g. manifold, slide valve and spiral hoses with hose connections) as preservation equipment.
The dehumidification and reconditioning processes in the absorption component must be continuous. The wet reconditioning air must be led to the atmosphere in such a way that it cannot be sucked back into the drying or reconditioning air inlet.
Forced cooling is only active until the average temperature of the HP and IP rotor reaches 150°C, the operation of the Blower & Super Dryer rack is independent of the turbine control system and can be turned on and off from the local plate in the rack.
Software modifications will be implemented in the control system in the next C-inspection or in a planned plant shutdown. The same applies at a distance: Hardware modification away from the reheat connection tubing.
After restoring the power plant (excluding GT), the Super Dryer and blower can be used to preserve the ST, WSC and HRSG to be ready from the start. This system can also be installed for preservation reasons only.