Over the years our stack flow rate has run at about 80k wet scfm, during this year the flow gradually increased until it became constant at a rate of 100k wet scfm. At the same time, we experienced a loss in production of about 14%. The oxygen level has not increased so I would have to rule out inleakage. Flue gas temperature has remained constant, so I do not believe is an air density problem. Of course there has been an increased specific fuel consumption of ~ 11%. Clinker temperature remained normal, cooler exhaust and tower exit temperatures normal as well. We really can not explain the loss in efficiency but I suspect that the increased air flow is related to it.
Thanks,