The chosen remedy was to install wet electrostatic precipitators. While this worked in capturing and washing out most of the fine caustic particulate, the amount that moved through still did a notable damage, just over a longer period of time. It is also interesting to note that electrostatic precipitators, like the one to match the size of a RTO in the OSB wood industry, cost about same on a $/scfm basis, as does an RTO itself.
After much trial and expense, some companies:
Choose to purchase premium, high alumina, caustic resistant heat recovery media and
Some other end users, depending on severity of the problem, kicked the can down the road and waited until flow was restricted (sometimes only a year or two before being forced to change the media).
It is interesting to note that many that “kicked the can down the road”, when it came time to purchase media, the majority of them once again chose commodity pricing instead of the high alumina, or purchased a product with non-stated ingredients because the supplier said it was caustic resistant. Again the decision was most likely short sighted as purchasing a product with greater than 50% alumina product would have been the correct economic choice.