Heat recovery from flue gas condensing and overall impact on CHP efficiency
Khadka, Nishan (2019)
Diplomityö
2019
School of Energy Systems, Energiatekniikka
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Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi-fe201903057130
https://urn.fi/URN:NBN:fi-fe201903057130
Tiivistelmä
This thesis paper investigates the flue gas condensing (FGC) and its integration in combined heat and power plant (CHP). FGC method utilizes the latent heat from flue gas and heat is released during condensation. It is considerable choice to increase the power plant efficiency and reduce the emission levels. The heat recovery from flue gas can be effectively achieved by the addition of heat pump or combustion air humidifier. The recovered heat could be utilized to increase district heat (DH) production or other industrial purposes.
Spray tower and heat pump are modeled in IPSEpro software for condensing and energy recovery and, modeling is entirely based on heat and mass transfer principle. The integration of FGC was carried out in 8 MWel CHP plant, which is based on biomass fuel with 55% moisture content. Spray tower was modeled for two stage scrubbing with liquid water. Heat pump was modeled taking account only heat transfer in condenser and evaporator, and was simulated with different values of coefficient of performance (COP).
The simulation on CHP model integrated with spray tower and heat pump showed the increase in DH production and overall efficiency of CHP plant compared to stand-alone CHP model. The simulation also indicated the significant decrease in exhaust gas temperature and lower consumption of fuel. However, electricity consumed by heat pump and higher temperature supply to DH condenser resulted in lower electricity production.
Spray tower and heat pump are modeled in IPSEpro software for condensing and energy recovery and, modeling is entirely based on heat and mass transfer principle. The integration of FGC was carried out in 8 MWel CHP plant, which is based on biomass fuel with 55% moisture content. Spray tower was modeled for two stage scrubbing with liquid water. Heat pump was modeled taking account only heat transfer in condenser and evaporator, and was simulated with different values of coefficient of performance (COP).
The simulation on CHP model integrated with spray tower and heat pump showed the increase in DH production and overall efficiency of CHP plant compared to stand-alone CHP model. The simulation also indicated the significant decrease in exhaust gas temperature and lower consumption of fuel. However, electricity consumed by heat pump and higher temperature supply to DH condenser resulted in lower electricity production.