Computer system for monitoring power boiler operation

Abstract The computer-based boiler performance monitoring system was developed to perform thermal-hydraulic computations of the boiler working parameters in an on-line mode. Measurements of temperatures, heat flux, pressures, mass flowrates, and gas analysis data were used to perform the heat transf...

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Bibliographic Details
Published in:Proceedings of the Institution of Mechanical Engineers. Part A, Journal of power and energy Journal of power and energy, 2008-02, Vol.222 (1), p.13-24
Main Authors: Taler, J, Weglowski, B, Zima, W, Duda, P, Gradziel, S, Sobota, T, Cebula, A, Taler, D
Format: Article
Language:English
Subjects:
Boiler tubes
Boilers
Cleanliness
Coal
Combustion chambers
Convection furnaces
Efficiency
Evaporation
Fading
Flowmeters
Fluidized bed combustion
Gas analysis
Heat
Heat flux
Heat transfer
Indication
Monitoring
Monitoring systems
Pipe
Real time
Stagnation
Start up
Stresses
Temperature
Walls
Water circulation
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Summary:Abstract The computer-based boiler performance monitoring system was developed to perform thermal-hydraulic computations of the boiler working parameters in an on-line mode. Measurements of temperatures, heat flux, pressures, mass flowrates, and gas analysis data were used to perform the heat transfer analysis in the evaporator, furnace, and convection pass. A new construction technique of heat flux tubes for determining heat flux absorbed by membrane water-walls is also presented. Flux tubes mounted at different levels in the boiler work at similar conditions as water-walls tubes. The current paper presents the results of heat flux measurement in coal-fired steam boilers. During changes of the boiler load, the necessary natural water circulation cannot be exceeded. A rapid increase of pressure may cause fading of the boiling process in water-wall tubes, whereas a rapid decrease of pressure leads to water boiling in all elements of the boiler's evaporator — water-wall tubes and downcomers. Both cases can cause flow stagnation in the water circulation leading to pipe cracking. Two flowmeters were assembled on central downcomers, and an investigation of natural water circulation in an OP-210 boiler (with steam capacity of 210 × 103 kg/h) was carried out. On the basis of these measurements, the maximum rates of pressure change in the boiler evaporator were determined. The on-line computation of the conditions in the combustion chamber allows for real-time determination of the heat flowrate transferred to the power boiler evaporator. Furthermore, with a quantitative indication of surface cleanliness, selective sootblowing can be directed at specific problem areas. A boiler monitoring system is also incorporated to provide details of changes in boiler efficiency and operating conditions following sootblowing, so that the effects of a particular sootblowing sequence can be analysed and optimized at a later stage. The current paper also presents an analysis of stresses occurring in the boiler drum and the downcomer junction during-start up and shut-down of the boiler.
ISSN:0957-6509
2041-2967
DOI:10.1243/09576509JPE419