Thermodynamic and economic analysis of a partially-underground tower-type boiler design for advanced double reheat power plants

An increasing number of tower-type boilers have been selected for advanced double reheat power plants, due to the uniform flue gas profile and the smooth steam temperature increase. The tall height and long steam pipelines lengths will however, result in dramatic increases in the difficulty of construction, as well as increased power plant investment cost. Given these factors, a novel partially-underground tower-type boiler design has been proposed in this study, which has nearly half of the boiler embedded underground, thereby significantly reducing the boiler height and steam pipeline lengths. Thermodynamic and economic analyses were quantitatively conducted on a 1000 MW advanced double reheat steam cycle. Results showed that compared to the reference power plant, the power plant with the proposed tower-type boiler design could reduce the net heat rate by 18.3 kJ/kWh and could reduce the cost of electricity (COE) by $0.60/MWh. The study also investigated the effects of price fluctuations on the cost-effectiveness of the reference power plant, for both the conventional and the proposed tower-type boilers designs, and found that the double reheat power plant with the proposed tower-type boiler design would be even more competitive and price-effective when the coal price and the investment costs increase. The research of this paper may provide a promising tower-type boiler design for advanced double reheat power plants with lower construction complexity and better cost-effectiveness.