Calcined magnesium oxide powder for water heater as well as preparation method and application of calcined magnesium oxide powder

The invention provides calcined magnesium oxide powder for a water heater and a preparation method and application of the calcined magnesium oxide powder, and the calcined magnesium oxide powder comprises the following components in percentage by mass: more than or equal to 95% wt of MgO; less than or equal to 1.5% wt of CaO; less than or equal to 0.6% wt of Fe2O3; less than or equal to 0.5% wt of Al2O3; less than or equal to 2.5% wt of SiO2; and less than or equal to 0.2% wt of LOI. The calcined magnesium oxide powder for the water heater has the advantages of high density (the original density is 2.30-2.34 g/cm , and the current density is 2.35-2.38 g/cm ) and high flow velocity (the original flow velocity under the condition of 100g of magnesium powder), and a heating tube is filled with the magnesium oxide powder more compactly. The invention also discloses a preparation method of the calcined magnesium oxide powder for the water heater. A calcined heating tube of the water heater prepared from the magnes