11.1.3 Dump tube
The dump tube is the final section of a by-pass system, where the steam is passed into the condenser at the correct pressure and temperature. Figure 2.84 shows an example.
Steam enters at the narrow section after leaving the pressure control valve. It passes through a number of plates (five or six) each containing a number of orifices. These plates further reduce the steam pressure and the tube section diverges here to accommodate the associated expansion of the steam. The steam then enters a spray-water section where it is desuperheated. Several water-jet entry ports circumscribe this section through which spray water is injected. The spray water is taken from the condensate extraction pump discharge and enters the dump tube via its own set of isolation and control valves. The steam at the reduced pressure and temperature leaves the dump tube through a section known as the dispenser.