This invention pertains generally to steam turbine condenser arrangements and more particularly to such arrangements that generate large vacuum loads which act upon the turbine support.
Basically a steam turbine system converts steam under pressure in a turbine to mechanical energy which is commonly employed to drive electrical generators. The steam exhausted from the turbine is usually communicated to a condenser where it is liquified and returned to the feedwater system of a steam generator to complete a closed loop cycle. Normally, the condenser and turbine are arranged in a multi-level facility with the condenser supported rigidly at a lower level below the turbine, which is independently supported. The turbine exhaust and condenser inlet are usually hermetically connected through an expandable coupling designed to accommodate thermal gradients and the relative movement of components. In operation, the change of state of steam within the condenser creates a large vacuum within the condensate chamber which can place large loads on the turbine housing and support. In large turbine facilities the vacuum loading may reach proportions which require turbine supports with increased load bearing capability to meet turbine deflection limitations. Such an increase in turbine support regidity provides a corresponding increase in weight and cost to the facility.
The foregoing condition can have a greater adverse effect in a turbine arrangement which employs a spring loaded support. The vacuum loading of the condenser in such an arrangement will result in excessive deflections for turbine operation.
One proposed modification to compensate for the vacuum load on the turbine support is to fixedly couple the turbine exhaust to the condenser inlet and mount the condenser on spring supports capable of accommodating thermal expansions and contractions experienced in operation. While this proposed solution may accommodate the vacuum load on a rigidly mounted turbine, it increases the potential for excessive movement in resilient systems, which is unacceptable in a floating barge mounted turbine facility, where the roll and pitch of the barge can further affect the movement of operating components.
Accordingly, a new type of condenser vacuum load compensating system is desired that will relieve the vacuum load on the turbine support without introducing additional flexibility into the turbine condenser arrangement.