Chastukhin – Thermal calculation of industrial steam generators
The purpose of the design calculation is to develop a new steam generator design for specified performance, steam parameters, and fuel.
A verification calculation is performed for an existing steam generator. Using the existing design characteristics and a given fuel load, the temperatures of water, steam, air, and combustion products at the boundaries between the heating surfaces, the unit’s efficiency, and fuel consumption are determined. The verification calculation provides the initial data necessary for selecting auxiliary equipment and performing hydraulic, aerodynamic, and strength calculations.
This manual describes the methodology for the verification thermal calculation of the steam generator and the design calculation of its individual components. If the design conditions differ little from those for which a standard steam generator is designed, the general layout and main components of the standard steam generator are retained. In this case, the verification calculation determines the technical performance of the unit under the specified conditions and, if necessary, outlines measures for the reconstruction of its individual sections. The scope of the reconstruction is determined by the design calculation of the sections subject to reconstruction.
When developing a steam generator reconstruction project, for example, due to an increase in its steam capacity, changes in steam parameters, or a switch to a different fuel, it may be necessary to modify a number of unit components. However, the main components of the steam generator and its overall layout are generally retained, while the reconstruction of those components that require modification is carried out in a manner that, where possible, maintains the basic units and components of a standard steam generator. In this case, a verification calculation is performed for the components that are not being modified, and a design calculation is performed for the components being reconstructed.
The course project “Thermal Calculation of Industrial Steam Generators” consists of an explanatory note with a thermal calculation of the unit, layout drawings of the steam generator, and some of its individual components, prepared at the supervisor’s request.
At the beginning of the note, a summary of the steam generator’s technical characteristics should be included, along with a description of the circulation system and separation devices. The furnace, superheater, economizer, and air preheater are briefly described as part of the calculation.
Thermal calculations for industrial steam generators are performed using a sequential calculation process with explanations of the steps involved. Calculation formulas are first written in general terms, then the numerical values of all the variables included are substituted, and finally the final calculation result is presented.
When performing thermal calculations, the values of a number of quantities—for example, excess air coefficients from the furnace to the flue gas ducts, thermal efficiency coefficients, and convective surface utilization factors, among others—are assumed to be approximate, with three to four significant digits. Therefore, attempting to improve calculation accuracy by introducing five- or six-digit quantities, even if they are obtained by adding a large value to a small one, is impractical. The resulting values should be rounded.
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