Vertical tube heat exchanger and method for exchanging heat

A heat exchanger having tubes intended to extend substantially in a vertical direction, the exchanger comprising:

• a first chamber including
• a lower portion provided with at least one intake inlet for a diphasic fluid including at least one liquid and a first vapor containing a mist,
• an upper portion, and
• a first recovery member suitable for being passed through by the first vapor and for recovering the mist in the form of a liquid phase returned toward the lower portion, the first vapor next arriving in the upper portion,
• a central chamber including the tubes and being suitable for being supplied with said liquid from a liquid bath situated in the lower portion of the first chamber and for forming liquid films running over outer faces of the tubes and vaporizing at least partially to form a second vapor, the tubes being traveled inwardly by a fluid hotter than the diphasic fluid, and
• a second chamber provided to cover the first vapor coming from the upper portion of the first chamber and the second vapor, and to form a third vapor, the second chamber including at least one outlet for the non-vaporized liquid, and at least one outlet for the third vapor,
• the first chamber and the second chamber together forming a volume surrounding the central chamber around the vertical direction.