Shell and tube heat exchanger

A shell and tube heat exchanger comprising a first outer shell and a tube bundle, wherein said tube bundle defines a tube side of said exchanger, corresponding to the inside of the tubes of said bundle, and the exchanger comprises a shell side defined on the outside of said tube bundle, and said exchanger comprising inlet and outlet interfaces communicating with the shell side and with the tube side for a first fluid and for a second fluid respectively,

• wherein:
• the exchanger comprises a second shell which is fully inside said first shell and which surrounds said tube bundle;
• said second shell comprising at least one releasable longitudinal joint and comprising a plurality of longitudinal sections connected by releasable joints;
• wherein said longitudinal sections are substantially parallel to an axis of said tube bundle;
• wherein said second shell delimits said shell side of the exchanger, around said tube bundle, and further defines a flushing interspace which is delimited between said first shell and said second shell,
• said interspace communicating with said shell side,
• wherein said first fluid flows through said shell side with one or more longitudinal passages,
• and wherein said first fluid and said second fluid are in counter-current along said one or more longitudinal passages of the first fluid in the shell side,
• said tube bundle being structurally integral with said second shell,
• wherein said tube bundle comprises a plurality of baffles substantially perpendicular to an axis of said tube bundle, and said second shell is structurally cooperating with said baffles;
• wherein said second shell rests on said baffles or is fixed to them.