Development of New Structural Elements of Gas Coolers in Atomic and Thermal Power Plants with Improved Corrosion-Mechanic Resistance

Abstract

Introduction. In power engineering, there is a need to improve the performance of gas coolers in contact with explosive atmospheres to ensure reliable operation of turbogenerators.
Problem Statement. Important problems that require constant improvement of equipment are local corrosion, hydrogenation, etc., in particular, of pipe joints with pipe boards, which is characterized by the emergence and development of cracks under the influence of simultaneous mechanical stress and corrosive environment. The
cracks promote depressurization that leads to emergency stop of turbogenerator.
Purpose. To develop a new design of sealing joints of heat exchange tubes and tube sheet with increased corrosion and corrosion-mechanical resistance.
Materials and methods. The samples made of steel 09G2S, M2 copper, steel 09G2S with a clad layer of copper M2, cupronickel МNZhМC 30-1-1, brass L68 have been tested. The vacuum extraction of hydrogen under elevated temperature, corrosion-fatigue, metallographic, and X-ray spectral test methods have been used.
Results. A new structural element of gas coolers with improved characteristics has been designed. It is based on a welded-rolled joint of a copper tube with a copper-clad tube sheet, which does not cause deformation of the structure and crack formation. The studies of the effect of different modes of flaring of such joints on their resistance to failure under the simultaneous action of cyclic loads and the environment have shown that as the degree of flaring of copper tubes 19 1.5 and 19 1 mm increases, the crack generation period and durability combined with connections grows ~1.5 times.
Conclusions. The new structural element reduces the probability of corrosion and mechanical destruction of parts of heat exchange equipment and helps to extend the period of its trouble-free operation.