International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

This paper shows analysis of each regenerative heater’s influence on global steam power plant operating parameters. Analysis is performed for nine steam power plant versions (configurations) – from the Base power plant without regenerative heating system up to the Final plant which consists of eight regenerative heaters (one mixing and seven non-mixing regenerative heaters). According to the defined fluid operating parameters throughout the plant, it is obtained that each new regenerative heater added to the plant continuously reduces the mechanical power produced by the turbine, for 4.33 MW on average. Simultaneously, each added regenerative heater increases feedwater temperature at the steam generator inlet, which results in power plant cumulative fuel consumption continuous decrease (for 0.414 kg/s on average) to obtain the same steam outlet parameters. Considering plant overall efficiency, it must be highlighted that each regenerative heater added to the plant continuously increases plant overall efficiency from the Base plant until the Final plant, for 0.43% on average.

This paper presents an exergy analysis of six pressure reduction valves which operate in a condensate/feedwater heating system of a 660 MW coal-fired steam power plant. For all observed pressure reduction valves is additionally investigated the ambient temperature change influence of their exergy parameters. Second pressure reduction valve (PRV2) has the highest exergy destruction of all observed valves (equal to 1003.36 kW at the base ambient state). The first five observed pressure reduction valves (from PRV1 to PRV5) have very high exergy efficiencies at the base ambient state, higher than 90%. The last observed valve, PRV6, has an exergy efficiency at the base ambient state notably lower in comparison to other five valves, equal to 64.90% only. The exergy variables of any pressure reduction valve are more and more influenced by the ambient temperature change when the operating parameters of working fluid which flows through the valve (fluid pressure and temperature) are closer to the ambient state.

This paper presents results of the Main Feedwater Pump (MFP) isentropic and exergy analyses at three power plant loads. Observed MFP is a constituent component of condensate/feedwater sub-system from conventional steam power plant. In real exploitation conditions, MFP uses mechanical power higher than 3000 kW, considering all observed power plant loads. Main isentropic and exergy parameters of the MFP at various plant loads show the same general trends (increase in power plant load simultaneously increases MFP losses and efficiencies and vice versa, from both isentropic and exergy viewpoints). Analyzed MFP has high isentropic and exergy efficiencies, considering all plant loads and ambient temperatures (at any plant load MFP isentropic efficiency is higher than 85%, while the lowest MFP exergy efficiency is equal to 89.24% at the lowest observed plant load and the highest observed ambient temperature). The change in isentropic and exergy efficiency of the MFP is small if all observed plant loads and ambient temperatures are taken into consideration.

The exergy analysis of deaerator at three different steam power plant loads is performed in this paper. Also, the influence of the ambient temperature change on deaerator exergy efficiency and losses is analyzed. From the exergy viewpoint, deaerator operation shows the best characteristics at middle and high power plant loads. The lowest deaerator exergy destruction of 363.94 kW and the highest exergy efficiency of 93.27 % will be obtained at middle power plant load and at the ambient temperature of 5 °C. The highest deaerator exergy destruction of 1349.99 kW and the lowest exergy efficiency of 81.83 % will be obtained at low power plant load and at the ambient temperature of 45 °C. Deaerator operation is preferable at the lowest possible ambient temperature, regardless of the current power plant load.