The Multitube demountable MIXFLO Heat Exchanger is manufactured by small diameter tubes fitted inside an external jacket. It is possible to remove the tubes bundle with this construction typology. This model is not equipped with expansion joint because the tubes sheet are floating. The product to be thermally processed flows inside the smaller tube while service fluid flows inside the jacket. With this model and with some kind of product is possible to flow the product itself inside the jacket in order to optimize energy recovery.