Performance Analysis of a Waste-to-Energy System Integrated with the Steam–Water Cycle and Urea Hydrolysis Process of a Coal-Fired Power Unit

Yuanyuan Zhang,Qiubai Li,Heng Chen,Kai Zhang,Lai Wei,Qilong Huang,Xin Gao

doi:10.3390/app12020866

Abstract

An innovative hybrid energy system consisting of a waste-to-energy unit and a coal-fired power unit is designed to enhance the energy recovery of waste and decrease the investment costs of waste-to-energy unit. In this integrated design, partial cold reheat steam of the coal-fired unit is heated by the waste-to-energy boiler’s superheater. The heat required for partial preheated air of waste-to-energy unit and its feedwater are supplied by the feedwater of CFPU. In addition, an additional evaporator is deployed in the waste-to-energy boiler, of which the outlet stream is utilized to provide the heat source for the urea hydrolysis unit of coal-fired power plant. The stand-alone and proposed designs are analyzed and compared through thermodynamic and economic methods. Results indicate that the net total energy efficiency increases from 41.84% to 42.12%, and the net total exergy efficiency rises from 41.19% to 41.46% after system integration. Moreover, the energy efficiency and exergy efficiency of waste-to-energy system are enhanced by 10.48% and 9.92%, respectively. The dynamic payback period of new waste-to-energy system is cut down from 11.39 years to 5.48 years, and an additional net present value of $14.42 million is got than before.

Highlights

With the development of economy and society, the urbanization process has accelerated and residents’ living standards have been improved in China
This study develops a deep integration of a 500 t/d waste-to-energy units (WTEUs) and a 660 MW coal-fired power units (CFPUs)
An integrated WTE system based on the steam–water cycle and urea hydrolysis process of a CFPU is developed to improve the performance of WTEU, according to the previous works

Summary

Introduction

With the development of economy and society, the urbanization process has accelerated and residents’ living standards have been improved in China. Municipal solid waste management (MSWM) has become a pronounced problem because of the population concentration and increased consumption during urbanization [1]. More than one-third of the cities and towns have fallen into the predicament of garbage siege and have been surrounded by landfills [2], which seriously hinders the sustainable development of society. During the 10 years from 2010 to 2019, the volume of municipal solid waste (MSW) removal rose from 158 million tons a year to 242 million tons a year in China [3]. Population explosion and rapid urbanization have brought about the rapid growth of MSW in urban areas worldwide. Global MSW may increase by 0.9 billion tons from 2010 to 2025 [4]

Results

Discussion

Conclusion