Corrosion Issues with Flue Gas Containing BF3 Vapours

I think I would go with one of these...

https://www.hpalloy.com/Alloys/hightemperature.aspx

<...Boron Fluoride...> does not appear in many published corrosion compatibility charts therefore it is likely that some experimental laboratory work may well be needed in order to determine materials compatibility. Contact with metals may well prove unsatisfactory, so consider the use of borosilicate glass (there are a number of commercial manufacturers) and fluoridated plastics as the wetted materials.

Flowrates, which have been withheld from the forum, are useful for determining equipment sizing: a 1in-diameter solution and a 1m-diameter solution may well have different wetted materials.

Consider also ways of reducing the temperature and condensing and retaining the process materials within the equipment rather than wasting them in the flue gas. Glass- and/or graphite-based heat exchanger construction is used for some specialised applications, depending on equipment size.

The dew point in the stack is dependent on the Vapor pressure of the water in the mixture. It might be helpful to determine just what water is in your gas mixture, and just how it gets there, to see if it is controllable.

As our Mr. Rixter has researched, the reaction is exothermic, so may compensate for cooling in the stack, keeping small cracks & crevices in the ducting from collecting an aqueous solution which could damage the material.

Also, as our Mr. Slack notes, there is not a lot of published information on the subject, so our supply of experts could be thin. You may need to supply more clues as to the sort of industry that produces these conditions, or conduct some experiments.

I suspect you don't have a problem, providing you can keep the temperature above 250F, based on history with sulfur containing gases with 30% mostly fuel bound moisture. This target temperature as a rule of thumb seemed to keep all components in contact with the gas above a condensation temperature.

https://www.ftek.com/en-US/products/productssubchemicaltechnologies/chemical-technologies-overview

Contact these folks at the link above. Chemical injection (properly done) can easily control the corrosion issue. I successfully applied liquid fuel treatment to eliminate corrosion problems for more than a decade at multiple East Coast refineries and power stations. It also serves as an effective deposit control agent. The product we used has a long history of success (there several to chose from).

The particular product would be selected on the basis of the process unit configuration and operating parameters. If (when) you contact them tell em' I sent you.