Handbook of air conditioning and refrigeration / Shan K

15.74 CHAPTER FIFTEEN
inner steam pipe and an outer jacket. The inner steam tube is connected to a header and controlled
by a control valve. Steam is supplied at a pressure less than 10 psig (69 kPag) and throttled to a
lower pressure after the controlled valve. It then enters the inner tube and discharges through the
small holes to the outer jacket. The dry steam is again discharged through the orifices of the jacket
to the ambient airstreams to humidify them, as shown in Fig. 15.42b. The condensate inside the
jacket is discharged to a drainpipe and steam trap located at the opposite side. The inner tube and
the outer jacket are slightly pitched toward the drainpipe and steam trap.
Steam Humidifiers with Separators
FIGURE 15.42 Steam grid humidifiers: (a) steam grid and piping connections;
(b) cross section of jacketed distribution manifold.
A steam humidifier with a separator is illustrated in Fig. 15.43. Steam is supplied to a jacketed
distribution manifold and then enters a separating chamber with its condensate. It then flows
through a control valve, is throttled to slightly above atmospheric pressure, and enters a drying
chamber. Because of the lower pressure and temperature in the drying chamber compared with the
higher pressure and temperature in the surrounded separating chamber, the steam is superheated.
Dry steam is then discharged into the ambient airstream through the orifices of the inner steam
discharging tubes. Noise is produced mainly during the throttling of the steam at the control valve.
It is attenuated as steam flows through the silencing materials.