Ann: Completion Xstrata Review , page-13

Thank you for the link dictionary it was very informative.

You wrote
"It's all about the constant temperature - not just heating up the first tank"

That is correct however I was just musing that if the first tank is helped in being heated up to operating temperature faster through an external heat source then the reaction will start earlier in the process.
That would actually give a more constant temperature through the series of tanks as the first tank heated up faster would be closer in operating temperature to the last tank which is utilising solely exothermic heat from the reaction.

Hopefully the chemists are far smarter than us anyway and get it sorted.