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One feedwater heater taken out of service as a strategy to maintain full load and its effect on steam power cycle parameters and performance
Author(s) -
Riesgo Adrián,
Folgueras María Belén
Publication year - 2019
Publication title -
international journal of energy research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.808
H-Index - 95
eISSN - 1099-114X
pISSN - 0363-907X
DOI - 10.1002/er.4450
Subject(s) - boiler feedwater , feedwater heater , boiler (water heating) , heat recovery steam generator , superheated steam , superheating , nuclear engineering , combined cycle , process engineering , engineering , environmental science , steam drum , waste management , mechanical engineering , thermal power station , turbine , thermodynamics , physics
Summary The aim of this study is to analyze the suitability of one heater removal as a strategy for maintaining full load operation of steam power cycles when superheated and/or reheated temperatures ( T SS , T RS ) decrease and the effect on the net heat rate (HR Net ). For this purpose, three regenerative cycles with different numbers of closed feedwater heaters were chosen. The cycles were analyzed at different steady states with Thermoflex software. Removing a heater has an important influence on the cycle operation and performance, leading to the redistribution of extraction mass flows, with the heater immediately downstream being the most affected. This may make it necessary to reduce the load of the cycle. However, when the highest pressure heater (highest PH) is removed from service, the changes are not so significant. When T SS and/or T RS decrease, the plant may not achieve full load operation. Nevertheless, if the highest PH is removed from service, it can help to recover full load. This is due to the decrease in the water/steam mass flow through the steam generator, which produces an increase in T SS and/or T RS . On the one hand, this measure leads to higher HR Net in comparison to that of the nominal conditions. On the other hand, there are certain conditions at which HR Net is lower than when all the heaters are in service and the values of T SS and/or T RS are low. Thus, for maintaining full load, the highest PH removal can be applied and cycle parameters optimized in order to reach a HR Net closer to its nominal value. The higher the number of closed feedwater heaters, the more adequate is the application of this strategy.