The invention relates to a device consisting of a heat exchanger, that can be used for the heat treatment of products such as juices, pulp and other food, liquid or particulate products. Said device includes a plurality of tubes of product in which the products to be processed circulate, each of said tubes containing an element for rotating and pushing the product, said elements being provided with circular parts that support metal bars from which respective scraper elements project, said scraper elements being pushed towards the walls of the tube by springs arranged inside the metal bars, in such a way that the permanent friction of the scrapers against the inner surface of the tube ensures the perfect cleaning thereof. For particulate products, each tube includes a screw that supports the longitudinal metal bars from which the scraper elements project. The position of the bars also causes turbulences that improve the thermal behaviour of the process.