Details About Closed Feed System

                        

(by clicking the diagram names will be shown clearly visible.)

Must read ➤Definition Of Open Feed System.

                  ➤Information About Boiler Operation

A closed feed system for a high-pressure water tube boiler supplying a main propulsion steam turbine. The steam turbine will exhaust into the condenser which will be at a high vacuum. A regenerative type of condenser will be used which allows condensing of the steam with the minimum drop in temperature. The condensate is removed by an extraction pump and circulates through an air ejector.  

The condensate is heated in passing through the air ejector. The ejector removes air from the condenser using steam-ope-rated ejectors. The condensate is now circulated through a gland steam condenser where it is further heated. In this heat exchanger the turbine gland steam is condensed and drains to the atmospheric drain tank. The condensate is now passed through a low-pressure heater which is supplied with bled steam from the turbine.

              ➤ Details About De-aerator And Feed Pump

All these various heat exchangers improve the plant efficiency by recovering heat, and the increased feedwater temperature assists in the de-aeration process. The de-aerator is a direct contact feed heater, i.e. the feedwater and the heating steam actually mix. In addition to heating, any dissolved gases, particularly oxygen, are released from the feedwater. The lower part of the de-aerator is a storage tank which supplies feedwater to the main feed pumps, one of which will supply the boiler's requirements. 

The feedwater passes to a high-pressure feed heater and then to the economiser and the boiler water drum. An atmospheric drain tank and a  feed tank are present in the system to store surplus feedwater and supply it when required. The drain tank collects the many drains in the system such as gland steam, air ejector steam, etc.

A recirculating feed line is provided for low load and manoeuvring operation to ensure an adequate flow of feedwater through the air ejector and gland steam condenser. The system described is only typical and variations to meet particular conditions will no doubt be found.