This design adopts condensation waste heat recovery scheme to recover sensible heat and latent heat in flue gas, and eventually produces continuous and stable saturated steam (0.8MPa gauge pressure) according to user requirements for subsequent use or incorporation into steam pipe network. Through the condensing waste heat recovery of flue gas at 520 C, 560 kW heat in flue gas can be effectively recovered, 8 kg steam 7200 kg/h can be directly produced, and the annual economic benefit is about 10 million yuan.