Abstract
One of the major concerns of the power energy industries is a proper
operation of steam power blocks. Pressurized working medium and high
temperature cause very high stresses in the construction elements such as
collectors, separators or steam valves. They are exposed to sudden
temperature and pressure changes that cause high stresses at certain
points. Additionally, the cyclic character of loading causes material
fatigue, known as low-cyclic fatigue, which may lead to the formation of
fracture. Thus, methodologies offered by many companies should ensure
reliable and safe operation of steam power blocks. The advanced numerical
solutions for determining time-optimum medium temperature changes are
presented. They are based on Levenberg-Marquardt and nonlinear programming
by quadratic Lagrangian methods. The methods allow us to find parameters
for start-up and shut-down operation that can reduce total stresses to
limits governed by European regulations. Furthermore, the heating and
cooling operations are conducted in a shortest time possible.
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