Analysis of thermal and water equilibrium and desulfurization efficiency after waste heat recovered from a wet flue gas desulfurization system

Abstract

Waste heat recovery for wet flue gas desulfurization (WFGD) system is quite necessary so that both heat and water consumption can be saved. However, formerly, there existed no clear concept about the upper limit quantity of waste heat that can be recovered for a target WFGD system, and where the final operation status of WFGD system after waste heat recovered will be located is also absent. Therefore, in the current paper, a methodology is developed first to simulate the magnesium method desulfurization system with circulating water considered using Aspen Plus V8.4. After validation, the methodology with slight modification is then used to investigate the theoretical maximal quantity of waste heat that can be recovered under different conditions and study the corresponding variation tendencies of updated thermal and water equilibrium states. Desulfurization efficiency is also discussed qualitatively. Results indicate that there exist maximal 1.41 to 2.27 MW heat that can be recovered at WFGD system for an 80 t/hr coal‐fired boiler, equivalent to save standard coal from about 1,385 to 2,230 t/a. All the streams temperature are reduced after recovering waste heat, but different streams behave different variation tendency. Water consumption and desulfurization efficiency also could get improved.

Energy efficiency enhancement of a thermal power plant by novel heat integration of Internal Combustion Engine, Boiler, and Organic Rankine Cycle

“…In the past, there have been numerous approaches investigated to recover waste heat with the aim of improving energy efficiency 4–6 . ORC is gaining considerable attention as a bottoming cycle for low‐temperature waste mediums 7–9 .…”

“…In the past, there have been numerous approaches investigated to recover waste heat with the aim of improving energy efficiency. [4][5][6] ORC is gaining considerable attention as a bottoming cycle for low-temperature waste mediums. [7][8][9] Guoqiang et al studied the plant efficiency for a 300-MW (Xiaologtan, Country) thermal power plant, and the results exposed that the major energy losses of 51.57% and 6.64% came from the condenser and boiler, respectively.…”