Well, lets see.... I'm sure entire books have been dedicated to this subject - but to try and get some quick ballpark...
- If the stove is quoted at 74,000 btu/hr @ 70% efficiency, then that should mean you're burning 74,000 / .70 or ~106,000 btu of wood per hour.
- Wood generally has about 7,600 btu/lb regardless of species, so that is 106,000 / 7,6000 or ~14 lbs of wood per hour
- This article
http://mha-net.org/html/p-tieg02.htm says gaseous combustion stops when the air-fuel ratio falls below 15:1, and most stoves are operated with substantial excess air, so 18:1 or even 20:1 is probably closer to reality. So based on those ratios, 14lbs of wood:
@ 15:1 AFR = 14x15 = 210 lbs air
@ 18:1 AFR = 14x18 = 252 lbs air
@ 20:1 AFR = 14x20 = 280 lbs air
So it looks like your initial assumption is at least in the ballpark. As a bonus question - density of air @ standard temp/pressure is 0.075 lb/cu ft - so you're talking anywhere from 210/0.075 ~ 2,800cu ft per hour to 280/0.075 ~ 3,700 cu ft per hour. Or given a standard 8 foot ceiling, all the air in a room roughly 19' x 19' on the small end up to a room 21.5' x 21.5' on the large end, or all the air in a 2,000 square foot house roughly every 4-6 hours.
