Chimney - to line or not to line?

[Puy de Dome]

Ok, so I have been reading the back posts about chimneys, but I'm one the wiser as to wether I should install a liner, or even have a pipe stiking out of the top at all!

Dmun - thanks for the tip about acids damaging metal liners. But really what I need to know is if my existing brick chimney can cope/act as a chimney in the sense that people here would understand?

Could these acids also damage a brick chimney, or would it be best, if not using a liner of any kind, to spread fire cement over the inside of the chimney?

I also thought that a nice rectanglar terracotta pipe from a builder's merchants cold do the trick. I have seen these used to transmit air from under the suspended floor of a house to the outside airbrick.

Presumeably a flue would have to be sealed/fitted securely at the bottom of the chimney - but if there were no flue, doesn't this negate the problem?

PdD

ps, something like these?