Steam ventalation pig caster

[GenevaMech]

Water is used to cool pig castings. im estimating 1000 gal/min of steam generation. the building could be as cool as 50 in winter. i need to know how to decide how much air to ad to the vent system so the steam won't condense. another design parameter is to shoot for 60^ humidity. Please help thanks. also im having trouble determing the humidity ratio. i got psat for the equation % humid=psat/p vapor(from steam table)

thanks and god bless engineers!