To reduce pressure loss while enlarging the working range of pressure and temperature by combining heat exchanger segments forming a high temperature high pressure heat exchanger employing ceramic tubes or pan assemblies and utilizing the heat exchanger to industrial process.

The high temperature high pressure heat exchanger 1 combines two heat exchanger segments 2 and ceramic tubes 86 is supported, at respective end parts, by a common baffle wall 89. A steel shell 52 is coupled through a coupling/tightening member 90 and a bellows expansion joint in the center of the heat exchanger 1 and elongation of the ceramic tubes 86 is absorbed by a spring on the outer circumference of the steel shell. Furthermore, a pan assembly 101 at the tube sheet section is arranged with nitrogen bonded silicon carbide bricks having back face and the ceramic tubes 86 is inserted into a pan opening in the back face. The heat exchanger 1 is utilized in power generating process.