Optimum heating of pressure components of large steam boilers

In this paper, the method of determining the optimum time changes of fluid temperature during heating process of boiler structural pressure elements is presented. The method allows to keep stresses at the maximum allowed levels. The optimization procedure is based on the discrete form of the Duhamel’s integral. The optimal temperature changes of the fluid were determined for the cylin-drical and spherical components, and Y-branch. The heating of the elements with- and without the internal pressure was analyzed. The examples of the optimum heating processes of the boiler pressure elements are also presented as the illustration of the application of the developed method. 2. Keywords: optimum heating, steam boilers, pressure components, large boiler operation Variable and high thermal stresses occurring in thick-walled elements of boilers during the start-up and turn-off process often lead to material fatigue and premature usage of the lifetime of the element subjected to pressure [1,2]. The greatest values of thermal stresses are recorded on the internal surface of the element, in particular at the points of their concentration, that is at the edges of the openings and in the notches. The control of these stresses is not easy due to technical difficulties in the tensometer placement on th