Understanding the Impacts of Water Vapor on CaO Sulfurization in a Laboratory Scale Fluidized Bed
Limestone has been widely used to remove SO2 from circulating fluidized bed (CFB) boilers. As the main component of limestone, CaCO3 first undergoes calcination to CaO, which is then sulfated by SO2 to form CaSO4 in the furnace. Water vapor accounts for a high concentration in coal fired CFB furnaces, which could influence CaO sulfurization. This work aims to understand this issue. Sulfurization experiments were conducted with the CaO calcined from a natural limestone in a laboratory scale fluidized bed reactor. Scanning electron microscopy, a mercury injection apparatus along with a N2 adsorption instrument, and X ray diffraction were employed to test the micromorphology, pore structure, and crystal structure of the sulfurization products, respectively. The results show that CaO sulfurization was improved by water vapor. In addition, an optimum amount of water vapor exists to achieve maximum sulfurization. The results of micromorphology results indicate that sintering, fusion, and growth of grains of sul.