Heat exchanger system for a boiler having a circulating fluidized bed

A heat exchanger system comprising;

• a first heat exchanger having an inlet and an outlet through which a fluid is input and output, respectively;
• a second heat exchanger disposed in a dense fluidized bed, and connected downstream from said first heat exchanger, the second heat exchanger including:
• an inlet through which particles are fed into the dense fluidized bed in suspension,
• a plurality of nests of tubes disposed perpendicularly along the path of the particles in suspension in the dense fluidized bed, and
• at least two feeds situated on either side of a center of said second heat exchanger, each of said feeds receiving a predetermined mixture of the input fluid and of the output fluid of said first heat exchanger, so that a temperature of a fluid fed into each of said nests from said first heat exchanger is an increasing function of an increasing distance between each of said nests and the inlet via which the particles are fed into the dense fluidized bed;
• and
• wherein an output temperature at an outlet of each of the nests, is substantially equal.