Heating Air with Steam: Efficiency and Options

[dyollnave]

Hey everyone, I have a questions. I am trying to determine the most efficient way to heat pressurized air (35-40 psig, and a flow of 20-30 scfm) at an inlet temperature of 60F, to an exit temperature of 200F with minimal pressure lose. On site I have the availability of saturated steam at (50-80 psig, with a flow rate of 50lb/hr avg, 287 lb/hr max.), as well as electricity(up to 3-phase, 480v). What are the best options given the above information.

What are the advantages/disadvantages of a air-steam heat exchanger vs. an electric coil type heater.

Condensate trapping and drain are not an issue, as waste water disposal is already in place.

Thanks a bunch, I look forward to joining everyone on PF!

 

[dyollnave]

The air will be used to dry items further down the process line, not vented into a room.

 

[edgepflow]

Maybe you checked this, but looking at your numbers, I back of envelope calculated that you have plenty of steam flow available. A small thermodynamic steam trap would also be fine.

Main advantage of steam heater is:

* cost of ownership (less than 10 lb/hr steam vs about a 1.5 kW heater),
* no need for high voltage (240/480 volt, 3 phase, 60 Hz),
* less controls (power must be cut if heater element surface temperature reaches HIGH alarm setpoint).

Of course, you will need to insulate your steam pipes leading to the air heater.

Are you going to control heater outlet temperature?