Lime kiln flue gas desulfurization technology
The emission of sulfur dioxide (SO₂) from the flue gas of lime kilns primarily originates from the sulfur content in the limestone raw material, and its control technology is crucial for meeting environmental standards. The current mainstream desulfurization technologies can be divided into three major categories: wet, dry, and semi-dry methods, among which the limestone-gypsum method is the most widely used in wet desulfurization.
Wet desulfurization technology achieves efficient desulfurization through gas-liquid reactions, with a desulfurization efficiency of over 90%. Its principle involves the reaction of limestone slurry with SO₂ in flue gas to produce calcium sulfite, which is oxidized to form gypsum as a by-product. This technology is highly mature, but it faces issues such as equipment corrosion, high energy consumption, and complex by-product treatment, necessitating the use of supporting anti-corrosion materials and gypsum dewatering systems.
Dry desulfurization technology, such as SDS dry desulfurization, involves the thermal activation of baking soda (NaHCO₃) followed by its reaction with SO₂, resulting in the formation of solid sodium sulfate that is discharged along with the bag filter dust. Its advantages lie in a simple system, no water consumption, and a small temperature drop in the flue gas after desulfurization, which is conducive to chimney dispersion. However, the desulfurization efficiency is generally lower than that of wet methods, and process parameters need to be adjusted according to the sulfur content of the flue gas.
Technical selection advice: For scenarios involving high-sulfur flue gas or strict environmental protection requirements, wet desulfurization should be prioritized; for enterprises with limited space or investment budgets, dry or semi-dry technologies can be chosen. In practical applications, a comprehensive evaluation should be conducted based on flue gas composition, temperature, and enterprise needs.
