With an average heating value of 10 MJ/kg from the municipal solid waste (MSW), an estimated 500 kWhe/tonne waste of energy can be generated from the incineration of MSW. This amount has the potential for higher energy recovery by using higher steam parameters (i.e. temperature and pressure), yet it is limited due to (i) corrosion of ferrous tubes at high temperature, and (ii) fluctuation in steam temperature. This project aims to design and develop a novel technology to solve these problems by replacing the existing water-wall technology with technology based on Phase Change Materials (PCM).
The proposed technology stores and controls the thermal energy from the combustion process, thus achieving net electrical efficiencies above 30%, while still maintaining low maintenance costs and high plant availability. Moreover, this technology can be integrated in the best available plant configurations and combustion control systems.
This technology will replace the existing water-wall technology in the combustion chamber with a PCM-based brick. The PCM-based brick is capable of storing a variable heat flux and to release it on demand, providing a steady output of heat flux. This mitigates the steam fluctuation problem, and at the same time, increases the temperature of superheated steam over the current corrosion limits (450°C) without using coated superheaters.
This technology can be employed in all waste-to-energy plants that experience steam fluctuation and ferrous tubes corrosion issue at high temperature. Our technology uses a PCM-based brick to replace the existing water-wall technology to firstly, increase the steam parameters and secondly, to reduce the temperature fluctuation, thereby improving the net electrical efficiency up to 34%. The PCM-based brick can be easily adapted to any existing waste-to-energy plants.
The main benefit of incorporating this technology into the waste-to-energy plant is the increase in electric efficiency, without compromising on the life span of the superheaters or increasing the maintenance cost. Moreover, the technology can be easily integrated into the existing plant configuration.