scholarly journals Rapid Start-Up of the Steam Boiler Considering the Allowable Rate of Temperature Changes

Automation ◽  
10.5772/51289 ◽  
2012 ◽  
Author(s):  
Jan Taler ◽  
Piotr Harchut
2018 ◽  
Vol 240 ◽  
pp. 05007
Author(s):  
Piotr Dzierwa

The paper shows the method of determining the start-up curves of a steam boiler, which enables its faster start-up. Faster temperature changes cause thermal stress, especially in thick-walled boiler elements. Critical elements that limit the rate of change of working fluid units include drums, outlet chamber, injection chamber, fresh steam superheater of steam coolers, tees and valve casings, rotor and turbine casing. The walls of these elements have the thickest walls due to the high pressure values occurring in them during operation. Allowable changes in temperature and pressure during start-up and shut-down can be determined by the European Standard EN 12952-3. The article shows how the start-up curves of a steam boiler can be determined using the European Standard and the method proposed by the author. Calculation results show that the starting time of the analyzed block can be significantly shortened.


2014 ◽  
Vol 875-877 ◽  
pp. 1176-1182 ◽  
Author(s):  
Bohdan Węglowski ◽  
Paweł Ocłoń ◽  
Andrzej Majcher

The calculations of stresses acting on the wall of boiler drum during the start-up process are presented in this paper. On the basis of the temperature measurements, which were carried out to determine the temperature distribution along the circumference of the outer wall of boiler drum, the temperature at the inner wall surface is determined using the inverse methods. The computations are carried out for the whole operation cycle of the power plant. Therefore, the pressure and temperatures are updated at consecutive time steps. These parameters allow determining the maximum values of circumferential, axial and Von Misses stresses during the operation cycle of steam boiler.


2004 ◽  
Author(s):  
Satoru Tokuda ◽  
Esa M. Rantanen ◽  
Jessica C. M. Gonzalez de Sather

2012 ◽  
Vol 33 (3) ◽  
pp. 126-138
Author(s):  
Dariusz Rząsa ◽  
Piotr Duda

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.


Author(s):  
Satoru Tokuda ◽  
Esa M. Rantanen ◽  
Jessica C. M. Gonzalez de Sather

Author(s):  
Yeshayahu Talmon

To achieve complete microstructural characterization of self-aggregating systems, one needs direct images in addition to quantitative information from non-imaging, e.g., scattering or Theological measurements, techniques. Cryo-TEM enables us to image fluid microstructures at better than one nanometer resolution, with minimal specimen preparation artifacts. Direct images are used to determine the “building blocks” of the fluid microstructure; these are used to build reliable physical models with which quantitative information from techniques such as small-angle x-ray or neutron scattering can be analyzed.To prepare vitrified specimens of microstructured fluids, we have developed the Controlled Environment Vitrification System (CEVS), that enables us to prepare samples under controlled temperature and humidity conditions, thus minimizing microstructural rearrangement due to volatile evaporation or temperature changes. The CEVS may be used to trigger on-the-grid processes to induce formation of new phases, or to study intermediate, transient structures during change of phase (“time-resolved cryo-TEM”). Recently we have developed a new CEVS, where temperature and humidity are controlled by continuous flow of a mixture of humidified and dry air streams.


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