Development of integrated technology for waste heat recovery from humid flue gas of hot water boiler

Abstract

For coal-fired hot water boilers, we developed a comprehensive waste heat recovery system coupled with a packed tower, industrial steam turbine, and absorption heat pump, which can directly reduce the auxiliary power consumption, realize energy cascade utilization, and waste heat recovery. The ASPEN Plus software was used to simulate the packed tower, absorption heat pump, and industrial steam turbine system. The design parameters of the system were obtained and the operation characteristics of the system under load rates of 25%, 50%, 75%, and 100% were investigated, the feasibility of steam subsystem transformation was also analyzed. Taking a 140 MW coal-fired boiler as an example, in the range of 25%~100% load rate, the direct energy saving can reach 118 to 523 kW∙h, the waste heat recovery power is 2.7 to 11.4 MW, and the coal saving can reach 374 to 1605 kg/h, resulting in energy and resource consumption reduction effect, the system also has CO2 and pollutant emission reduction effect. The RadFrac model can be used in packed tower design, the system can work well under variable load conditions.