Simulation of a novel waste heat recovery system with sulfide-containing flue gas

Abstract

For further recovering the waste heat from sulfide-containing flue gas, a novel waste heat recovery system is proposed based on the intelligent control and phase-change heat transfer theory. And a mathematical model is also established to investigate the operating characteristics of the novel system. The system performance is analyzed by the simulation method. The results show that the heat recovery coefficient will increase linearly with the design volume flow rate and heat load ratio of flue gas while decrease with the volume flow rate of LiBr solution. The temperature difference between flue gas and LiBr solution will decrease with the volume flow rate of LiBr solution while reduce linearly with the decrease of heat load ratio. When the design volume flow rate is in range of 25,000–75,000 and 75,000–150,000 Nm3/h, the volume flow rate of LiBr solution should be proposed to be 35 and 75 m3/h for the novel system, respectively. In actual operation, the volume flow rate of LiBr solution should be reduced with the decrease of heat load ratio in range of 0.65–1.2 when the design volume flow rate of flue gas is 100,000–150,000 Nm3/h. Otherwise the circulating pump should be operated at the constant volume flow rate. The exergy efficiency will decrease with the heat load ratio of flue gas. But it is only about 0.25–0.30. The above research results can provide theoretical guidance for the design and operation of the novel system.